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Sample records for ankle dorsiflexor motoneurons

  1. Bilateral neuromuscular plasticity from unilateral training of the ankle dorsiflexors.

    PubMed

    Dragert, Katie; Zehr, E Paul

    2011-01-01

    Training a muscle group in one limb yields strength gains bilaterally-the so-called cross-education effect. However, to date there has been little study of the targeted application of this phenomenon in a manner relevant to clinical rehabilitation. For example, it may be applicable post-stroke, where hemiparesis leads to ankle flexor weakness. The purpose of this study was to examine the effects of high-intensity unilateral dorsiflexion resistance training on agonist (tibialis anterior, TA) and antagonist (plantarflexor soleus, SOL) muscular strength and H-reflex excitability in the trained and untrained limbs. Ankle flexor and extensor torque, as well as SOL and TA H-reflexes evoked during low-level contraction, were measured before and after 5 weeks of dorsiflexion training (n = 19). As a result of the intervention, dorsiflexor maximal voluntary isometric contraction force (MVIC) significantly increased (P < 0.05) in both the trained and untrained limbs by 14.7 and 8.4%, respectively. No changes in plantarflexor MVIC force were observed in either limb. Significant changes in H-reflex excitability threshold were also detected: H(@thresh) significantly increased in the trained TA and SOL; and H(@max) decreased in both SOL muscles. These findings reveal that muscular crossed effects can be obtained in the ankle dorsiflexor muscles and provide novel information on agonist and antagonist spinal adaptations that accompany unilateral training. It is possible that the ability to strengthen the ankle dorsiflexors bilaterally could be applied in post-stroke rehabilitation, where ankle flexor weakness could be counteracted via dorsiflexor training in the less-affected limb.

  2. Simulations of foot stability during gait characteristic of ankle dorsiflexor weakness in the elderly.

    PubMed

    Gefen, A

    2001-12-01

    Falls are common among the elderly and often cause injuries. They most frequently occut during walking and are associated with the chronic deterioration in neuromuscular and sensory systems, as well as with ankle dorsiflexor muscular weakness and lowered endurance of these muscles to fatigue. In the present study, a three-dimensional (3-D) finite element model of the structure of the foot was utilized to determine the effects of ankle dorsiflexor muscle weakness on the structural stability of the foot and, consequently, on the risk of falls during gait. The medial-lateral tendency of instability of the foot during gait in such conditions of weakness was analyzed by means of this model to identify the most important muscles used in controlling foot stability in affected individuals. The values of the eccentricity of the center of pressure under the heel during foot placement were used to indicate the degree of foot stability. The computational analysis indicated that it is the tibialis anterior muscle's weakness that dramatically decreases foot stability. Clinical investigation is now needed to correlate the significance of tibialis anterior muscle weakness with other known risk factors affecting the tendency to falls among the elderly, e.g., deterioration of sensory abilities. Rehabilitation practitioners and physical therapists may apply the present analytic approach to evaluate the stability of a foot before treatment and compare the predicted with the actual therapeutic results in terms of optimization of foot-ground pressure.

  3. Explosive Resistance Training Increases Rate of Force Development in Ankle Dorsiflexors and Gait Function in Adults With Cerebral Palsy.

    PubMed

    Kirk, Henrik; Geertsen, Svend S; Lorentzen, Jakob; Krarup, Kasper B; Bandholm, Thomas; Nielsen, Jens B

    2016-10-01

    Kirk, H, Geertsen, SS, Lorentzen, J, Krarup, KB, Bandholm, T, and Nielsen, JB. Explosive resistance training increases rate of force development in ankle dorsiflexors and gait function in adults with cerebral palsy. J Strength Cond Res 30(10): 2749-2760, 2016-Alterations in passive elastic properties of muscles and reduced ability to quickly generate muscle force contribute to impaired gait function in adults with cerebral palsy (CP). In this study, we investigated whether 12 weeks of explosive and progressive heavy-resistance training (PRT) increases rate of force development of ankle dorsiflexors (RFDdf), improves gait function, and affects passive ankle joint stiffness in adults with CP. Thirty-five adults (age: 36.5; range: 18-59 years) with CP were nonrandomly assigned to a PRT or nontraining control (CON) group in this explorative trial. The PRT group trained ankle dorsiflexion, plantarflexion, leg press, hamstring curls, abdominal curls, and back extension 3 days per week for 12 weeks, with 3 sets per exercise and progressing during the training period from 12 to 6 repetition maximums. RFDdf, 3-dimensional gait analysis, functional performance, and ankle joint passive and reflex-mediated muscle stiffness were evaluated before and after. RFDdf increased significantly after PRT compared to CON. PRT also caused a significant increase in toe lift late in swing and a significantly more dorsiflexed ankle joint at ground contact and during stance. The increased toe-lift amplitude was correlated to the increased RFDdf (r = 0.73). No other between-group differences were observed. These findings suggest that explosive PRT may increase RFDdf and facilitate larger range of movement in the ankle joint during gait. Explosive PRT should be tested in clinical practice as part of a long-term training program for adults with CP.

  4. Gait training facilitates central drive to ankle dorsiflexors in children with cerebral palsy.

    PubMed

    Willerslev-Olsen, Maria; Petersen, Tue Hvass; Farmer, Simon Francis; Nielsen, Jens Bo

    2015-03-01

    data show that daily intensive gait training increases beta and gamma oscillatory drive to ankle dorsiflexor motor neurons and that it improves toe lift and heel strike in children with cerebral palsy. We propose that intensive gait training may produce plastic changes in the corticospinal tract, which are responsible for improvements in gait function.

  5. Cocontraction of Ankle Dorsiflexors and Transversus Abdominis Function in Patients With Low Back Pain

    PubMed Central

    Chon, Seung-Chul; You, Joshua H.; Saliba, Susan A.

    2012-01-01

    difference was observed in RF onset time (t38 = 1.63, P = .11) or the cocontracted TrA/IO peak (t38 = −1.90, P = .07) and mean (t38 = −1.81, P = .08). The test-retest reliability for the muscle thickness measure revealed excellent correlations (intraclass correlation coefficient range, 0.95–0.99). Conclusions We are the first to demonstrate that a cocontraction of the ankle dorsiflexors with ADIM training might result in a thickness change in the TrA muscle and associated pain management in patients with chronic LBP. PMID:22889653

  6. Failure of normal development of central drive to ankle dorsiflexors relates to gait deficits in children with cerebral palsy.

    PubMed

    Petersen, Tue Hvass; Farmer, Simon F; Kliim-Due, Mette; Nielsen, Jens Bo

    2013-02-01

    Neurophysiological markers of the central control of gait in children with cerebral palsy (CP) are used to assess developmental response to therapy. We measured the central common drive to a leg muscle in children with CP. We recorded electromyograms (EMGs) from the tibialis anterior (TA) muscle of 40 children with hemiplegic CP and 42 typically developing age-matched controls during static dorsiflexion of the ankle and during the swing phase of treadmill walking. The common drive to TA motoneurons was identified through time- and frequency-domain cross-correlation methods. In control subjects, the common drive consists of frequencies between 1 and 60 Hz with peaks at beta (15-25 Hz) and gamma (30-45 Hz) frequencies known to be caused by activity within sensorimotor cortex networks: this drive to motoneurons strengthens during childhood. Similar to this drive in control subjects, this drive to the least affected TA in the CP children tended to strengthen with age, although compared with that in the control subjects, it was slightly weaker. For CP subjects of all ages, the most affected TA muscle common drive was markedly reduced compared with that of their least affected muscle as well as that of controls. These differences between the least and most affected TA muscles were unrelated to differences in the magnitude of EMG in the two muscles but positively correlated with ankle dorsiflexion velocity and joint angle during gait. Time- and frequency-domain analysis of ongoing EMG recruited during behaviorally relevant lower limb tasks provides a noninvasive and important measure of the central drive to motoneurons in subjects with CP.

  7. Velocity during Strength and Power Training of the Ankle Plantar and Dorsiflexor Muscles in Older Patients Attending Day Hospital Rehabilitation.

    PubMed

    Rajan, Pavithra; Porter, Michelle M

    2015-01-01

    Power training has been proposed as a more effective type of resistance training for older adults for functional performance. It is not yet known whether older adults respond appropriately to instructions for power versus strength training. The purpose of this study was to determine the velocity during strength and power training, with elastic resistance bands, in older adults attending a geriatric rehabilitation day program. It was hypothesized that power training would be faster than strength training, but that there would be large interindividual differences. Nine older patients (70 to 86 years) performed power and strength training of the ankle dorsiflexor and plantar flexor muscles using elastic resistance bands. Training sessions were filmed to assess the velocity of training. Power training occurred at faster velocities as compared to strength training (P < 0.01) for both muscle groups. However, a wide variation was observed between participants in the training velocities. Older adults attending geriatric rehabilitation do have the potential to develop faster contractions during power training as compared to strength training. Nevertheless, the actual velocities achieved differed between individuals. This could explain some of the mixed findings of studies on power training. Hence, researchers should monitor velocity when comparing different types of resistance training.

  8. Increase in group II excitation from ankle muscles to thigh motoneurones during human standing

    PubMed Central

    Marchand-Pauvert, Véronique; Nicolas, Guillaume; Marque, Philippe; Iglesias, Caroline; Pierrot-Deseilligny, Emmanuel

    2005-01-01

    In standing subjects, we investigated the excitation of quadriceps (Q) motoneurones by muscle afferents from tibialis anterior (TA) and the excitation of semitendinosus (ST) motoneurones by muscle afferents from gastrocnemius medialis (GM). Standing with a backward lean stretches the anterior muscle pair (TA and Q) and they must be cocontracted to maintain balance. Equally, forward lean stretches the posterior muscle pair (GM and ST) and they must be cocontracted. We used these conditions of enhanced lean to increase the influence of γ static motoneurones on muscle spindle afferents, which enhances the background input from these afferents to extrafusal motoneurones. The effects of the conditioning volleys on motoneurone excitability was estimated using the modulation of the on-going rectified EMG and of the H reflex. Stimulation of afferents from TA in the deep peroneal nerve at 1.5–2 × MT (motor threshold) evoked early group I and late group II excitation of Q motoneurones. Stimulation of afferents in the GM nerve at 1.3–1.8 MT evoked only late group II excitation of ST motoneurones. The late excitation produced by the group II afferents was significantly greater when subjects were standing and leaning than when they voluntarily cocontracted the same muscle pairs at the same levels of activation. The early effect produced by the group I afferents was unchanged. We propose that this increase in excitation by group II afferents reflects a posture-related withdrawal of a tonic inhibition that is exerted by descending noradrenergic control and is specific to the synaptic actions of group II afferents. PMID:15860524

  9. Electrical Stimulation of Low-Threshold Proprioceptive Fibers in the Adult Rat Increases Density of Glutamatergic and Cholinergic Terminals on Ankle Extensor α-Motoneurons

    PubMed Central

    Gajewska-Woźniak, Olga; Grycz, Kamil; Czarkowska-Bauch, Julita; Skup, Małgorzata

    2016-01-01

    The effects of stimulation of low-threshold proprioceptive afferents in the tibial nerve on two types of excitatory inputs to α-motoneurons were tested. The first input is formed by glutamatergic Ia sensory afferents contacting monosynaptically α-motoneurons. The second one is the cholinergic input originating from V0c—interneurons, located in lamina X of the spinal cord, modulating activity of α-motoneurons via C-terminals. Our aim was to clarify whether enhancement of signaling to ankle extensor α-motoneurons, via direct electrical stimulation addressed predominantly to low-threshold proprioceptive fibers in the tibial nerve of awake rats, will affect Ia glutamatergic and cholinergic innervation of α-motoneurons of lateral gastrocnemius (LG). LG motoneurons were identified with True Blue tracer injected intramuscularly. Tibial nerve was stimulated for 7 days with continuous bursts of three pulses applied in four 20 min sessions daily. The Hoffmann reflex and motor responses recorded from the soleus muscle, LG synergist, allowed controlling stimulation. Ia terminals and C-terminals abutting on LG-labeled α-motoneurons were detected by immunofluorescence (IF) using input-specific anti- VGLUT1 and anti-VAChT antibodies, respectively. Quantitative analysis of confocal images revealed that the number of VGLUT1 IF and VAChT IF terminals contacting the soma of LG α-motoneurons increased after stimulation by 35% and by 26%, respectively, comparing to the sham-stimulated side. The aggregate volume of VGLUT1 IF and VAChT IF terminals increased by 35% and by 30%, respectively. Labeling intensity of boutons was also increased, suggesting an increase of signaling to LG α-motoneurons after stimulation. To conclude, one week of continuous burst stimulation of proprioceptive input to LG α-motoneurons is effective in enrichment of their direct glutamatergic but also indirect cholinergic inputs. The effectiveness of such and longer stimulation in models of injury is a

  10. A HRP study of the relation between cell size and motor unit type in cat ankle extensor motoneurons.

    PubMed

    Burke, R E; Dum, R P; Fleshman, J W; Glenn, L L; Lev-Tov, A; O'Donovan, M J; Pinter, M J

    1982-07-20

    The dimensions of the somata and stem dendrites of 57 alpha- and three gamma-motoneurons, identified as to motor unit type and labeled by intracellular injection of horseradish peroxidase, were measured in the triceps surae and plantaris motor pools. The somata of type S motoneurons tended to be smaller (mean diameter 47.9 micrometers) than those of FF and FR units (52.5 and 53.1 micrometer, respectively) but these mean values were not significantly different and the data distributions showed considerable overlap between the unit types. The mean numbers and diameters of stem dendrites exhibited somewhat larger differences related to motor unit type and some of these were statistically significant. The total membrane area (AN) of each cell was estimated from measurements of the soma and stem dendrites, by using recent data and Ulfhake and Kellerth ('81) to calculate the membrane area of a dendritic tree from stem dendrite diameter. Mean AN varied with motor unit type in the sequence FF greater than FR greater than S (average values: 369 X 100(3) micrometers 2, 323 X 100(3) micrometers 2, and 250 X 100(3) micrometers 2, respectively). There was covariation between AN and the conduction velocity of the motor axon as well as with the force output from the muscle unit. Comparison of AN and motoneuron input resistance (RN) in 19 alpha-motoneurons suggested that the specific resistivity of the cell membrane in type S motoneurons was systematically higher than that characteristic of type FF or FR motoneurons.

  11. Static balance improvement in elderly after dorsiflexors electrostimulation training.

    PubMed

    Amiridis, Ig; Arabatzi, F; Violaris, P; Stavropoulos, E; Hatzitaki, V

    2005-07-01

    The purpose of the present study was to determine the effect of dorsiflexors' ElectroStimulation (ES) training, on postural tasks of increasing difficulty in the elderly. Twenty-one elderly adults were randomly assigned into one of two groups: a Training (TG) and a Control Group (CG). The TG (n = 10) performed (4 weeks, 4 s/week, 40 min/session) superimposed (electrically evoked and voluntary activation) isometric dorsiflexions (ankle 100 degrees ) while seated. Biphasic, rectangular symmetrical pulses (300 ms, 70 Hz, 20-60 mA) were used to provoke maximal muscle activation. Participants performed three static balance tasks (Normal Quiet Stance, Sharpened Romberg, and One-Legged Stance) during which postural sway was quantified using maximum range and standard deviation of Centre of Pressure displacement (Kistler 9281C, 1,000 Hz). Bipolar surface electrodes were used to record the Electromyographic activity (EMG) of Tibialis Anterior, Medial Gastrocnemius, Rectus Femoris and Semi-Tendineous. Two-dimensional kinematic data were collected (60 Hz) and analyzed using the APAS Motion Analysis software. The body was modeled as a five-segment rigid link system. Isometric dorsiflexion moment/angular position relationship was also established using a Cybex dynamometer. ES training resulted in decreased postural sway (P < 0.05), greater ankle muscles EMG activity (P < 0.001), greater stability of the ankle joint (P < 0.05) and significant changes in mean position of all three joints of the lower limb. In addition, dorsiflexion moment significantly (P < 0.001) increased as a result of ES training. It is concluded that dorsiflexors' ES training, could reduce postural sway and the use of ankle muscles, more characteristic of young adults, might appear in the elderly as well.

  12. Unloaded shortening velocity of voluntarily and electrically activated human dorsiflexor muscles in vivo.

    PubMed

    Sasaki, Kazushige; Ishii, Naokata

    2010-09-27

    We have previously shown that unloaded shortening velocity (V(0)) of human plantar flexors can be determined in vivo, by applying the "slack test" to submaximal voluntary contractions (J Physiol 567:1047-1056, 2005). In the present study, to investigate the effect of motor unit recruitment pattern on V(0) of human muscle, we modified the slack test and applied this method to both voluntary and electrically elicited contractions of dorsiflexors. A series of quick releases (i.e., rapid ankle joint rotation driven by an electrical dynamometer) was applied to voluntarily activated dorsiflexor muscles at three different contraction intensities (15, 50, and 85% of maximal voluntary contraction; MVC). The quick-release trials were also performed on electrically activated dorsiflexor muscles, in which three stimulus conditions were used: submaximal (equal to 15%MVC) 50-Hz stimulation, supramaximal 50-Hz stimulation, and supramaximal 20-Hz stimulation. Modification of the slack test in vivo resulted in good reproducibility of V(0), with an intraclass correlation coefficient of 0.87 (95% confidence interval: 0.68-0.95). Regression analysis showed that V(0) of voluntarily activated dorsiflexor muscles significantly increased with increasing contraction intensity (R(2) = 0.52, P<0.001). By contrast, V(0) of electrically activated dorsiflexor muscles remained unchanged (R(2)<0.001, P = 0.98) among three different stimulus conditions showing a large variation of tetanic torque. These results suggest that the recruitment pattern of motor units, which is quite different between voluntary and electrically elicited contractions, plays an important role in determining shortening velocity of human skeletal muscle in vivo.

  13. Ankle pain

    MedlinePlus

    Pain - ankle ... Ankle pain is often due to an ankle sprain. An ankle sprain is an injury to the ligaments, which ... the joint. In addition to ankle sprains, ankle pain can be caused by: Damage or swelling of ...

  14. High-intensity unilateral dorsiflexor resistance training results in bilateral neuromuscular plasticity after stroke.

    PubMed

    Dragert, Katie; Zehr, E Paul

    2013-03-01

    Hemiparesis after stroke decreases ability to dorsiflex the more-affected ankle during walking. Increased strength would be beneficial, but the more-affected limb is often too weak to be trained. In neurologically intact participants, training one limb induces strength gains in the contralateral, untrained limb. This approach remains unexplored post-stroke. The aim of this study was to test the hypothesis that unilateral dorsiflexor high-intensity resistance training on the less-affected side increases strength and motor output bilaterally following stroke. 19 participants (84.1 ± 77.6 months post-infarct) performed 6 weeks of maximal isometric dorsiflexion training using the less-affected leg. Voluntary isometric strength (dorsiflexion torque, muscle activation), reciprocal inhibition (RI), walking ability (gait speed, kinematics, EMG patterns), and clinical function were measured within 1 week before and 4 days following training. Post-intervention, dorsiflexion torque increased by ~31 % (p < 0.05) in the more-affected (untrained) and by ~34 % (p < 0.05) in the less-affected (trained) legs. Muscle activation significantly increased bilaterally, by ~59 and ~20 % in the trained and untrained legs, respectively. Notably, 4 participants who were unable to generate functional dorsiflexion on the more-affected side before training could do so post-intervention. Significant correlations between muscle activation and size of RI were noted across muscle groups before and after training, and the relation between size of RI and level of muscle activation in the more-affected tibialis anterior muscle was significantly altered by training. Thus, significant gains in voluntary strength and muscle activation on the untrained, more-affected side after stroke can be invoked through training the opposite limb. We demonstrate residual plasticity existing many years post-stroke and suggest clinical application of the cross-education effect where training the more-affected limb is

  15. Effects of using an unstable inclined board on active and passive ankle range of motion in patients with ankle stiffness.

    PubMed

    Yoo, Won-Gyu

    2015-07-01

    [Purpose] The present study assessed the effects of using an unstable inclined board on the active and passive ankle range of motion in patients with ankle stiffness. [Subjects] The study included 10 young female patients with ankle stiffness. [Methods] The patients were divided into the following two groups: a group that performed ankle dorsiflexion stretching exercises using a wooden inclined board and a group that performed stretching exercises using an air-cushioned inclined board (unstable inclined board). Active and passive ankle dorsiflexion angles were measured bilaterally using a goniometer. [Results] Both inclined boards significantly increased active and passive ankle dorsiflexion. After performing ankle stretching exercises, active dorsiflexion significantly increased the unstable inclined board compared to that using the wooden inclined board. However, the passive dorsiflexion angles did not differ significantly between the two groups after ankle stretching exercises. [Conclusion] The use of an unstable inclined board might stimulate activation of the ankle dorsiflexors in addition to stretching muscle or tissue. Active ankle dorsiflexion was more effectively improved with stretching exercises using an unstable inclined board than with exercises using a wooden inclined board.

  16. An ankle-foot orthosis powered by artificial pneumatic muscles.

    PubMed

    Ferris, Daniel P; Czerniecki, Joseph M; Hannaford, Blake

    2005-05-01

    We developed a pneumatically powered orthosis for the human ankle joint. The orthosis consisted of a carbon fiber shell, hinge joint, and two artificial pneumatic muscles. One artificial pneumatic muscle provided plantar flexion torque and the second one provided dorsiflexion torque. Computer software adjusted air pressure in each artificial muscle independently so that artificial muscle force was proportional to rectified low-pass-filtered electromyography (EMG) amplitude (i.e., proportional myoelectric control). Tibialis anterior EMG activated the artificial dorsiflexor and soleus EMG activated the artificial plantar flexor. We collected joint kinematic and artificial muscle force data as one healthy participant walked on a treadmill with the orthosis. Peak plantar flexor torque provided by the orthosis was 70 Nm, and peak dorsiflexor torque provided by the orthosis was 38 Nm. The orthosis could be useful for basic science studies on human locomotion or possibly for gait rehabilitation after neurological injury.

  17. An Ankle-Foot Orthosis Powered by Artificial Pneumatic Muscles

    PubMed Central

    Ferris, Daniel P.; Czerniecki, Joseph M.; Hannaford, Blake

    2005-01-01

    We developed a pneumatically powered orthosis for the human ankle joint. The orthosis consisted of a carbon fiber shell, hinge joint, and two artificial pneumatic muscles. One artificial pneumatic muscle provided plantar flexion torque and the second one provided dorsiflexion torque. Computer software adjusted air pressure in each artificial muscle independently so that artificial muscle force was proportional to rectified low-pass-filtered electromyography (EMG) amplitude (i.e., proportional myoelectric control). Tibialis anterior EMG activated the artificial dorsiflexor and soleus EMG activated the artificial plantar flexor. We collected joint kinematic and artificial muscle force data as one healthy participant walked on a treadmill with the orthosis. Peak plantar flexor torque provided by the orthosis was 70 Nm, and peak dorsiflexor torque provided by the orthosis was 38 Nm. The orthosis could be useful for basic science studies on human locomotion or possibly for gait rehabilitation after neurological injury. PMID:16082019

  18. Modulation of Ankle Muscle Postural Reflexes in Stroke: Influence of Weight-bearing Load

    PubMed Central

    Marigold, Daniel S.; Eng, Janice J.; Inglis, J. Timothy

    2011-01-01

    Objective Given the known sensorimotor deficits and asymmetric weight-bearing posture in stroke, the aim of this study was to determine whether stroke affects the modulation of standing postural reflexes with varying weight-bearing load. Methods Ten individuals with chronic stroke and 10 healthy older adult controls were exposed to unexpected forward and backward platform translations while standing. Three different stance conditions were imposed: increased weight-bearing load, decreased weight-bearing load, and self-selected stance. Surface EMG from bilateral ankle dorsiflexors (tibialis anterior) and extensors (gastrocnemius) were recorded and the magnitude of background muscle activity (prior to the platform translation) and postural reflex onset latency and magnitude (75 ms following reflex onset) were determined. Results Load modulation of ankle extensors was found in controls and individuals with stroke. Although controls demonstrated modulation of ankle dorsiflexors to different loads, individuals with stroke did not show this modulation. Further, load did not change the onset latency of postural reflexes of the individuals with stroke. Conclusion The delayed paretic muscle onset latencies in conjunction with impaired modulation of ankle dorsiflexor postural reflexes may contribute to the instability and frequent falls observed among individuals with stroke. Significance The results provide some insight into standing postural reflexes following stroke. PMID:15546787

  19. Effects of Motoneuron Properties on Reflex Stability in Spastic Subjects: A Simulation Study

    DTIC Science & Technology

    2007-11-02

    was tested using a comprehensive model of the reflex pathway. This model included the passive and active components of the triceps surae muscles...became unstable and oscillations developed similar to those observed in spastic patients. In parallel, when reflex delay times typical for triceps ... surae in man were chosen, and motoneuron excitability increased progressively, oscillatory ankle movements were readily elicited. Conversely, as pathway

  20. Are there any relationships among ankle proprioception acuity, pre-landing ankle muscle responses, and landing impact in man?

    PubMed

    Fu, Siu Ngor; Hui-Chan, Christina Wan Ying

    2007-05-01

    Proprioceptive input has been suggested to contribute to the pre-landing muscle responses associated with drop-landing, but its precise role has yet to be delineated. This study set out to examine the relationships among ankle proprioception, pre-landing muscle responses, and landing impact on drop-landing in healthy man. Fifteen healthy male basketball players aged 18 to 26 participated in this study. Passive ankle joint repositioning errors were used to examine ankle joint proprioception. Pre-landing EMG responses in the ankle muscles and the impact force on landing were recorded while the players performed self-initiated drops from a height of 30 cm. Results demonstrated that averaged ankle repositioning errors were significantly correlated with the co-contraction indexes between left tibialis anterior and medial gastrocnemius muscles (TA/MG CoI) (r=0.67, p=0.006), and showed a trend towards a relationship with the right TA/MG CoI (r=0.47, p=0.079). TA/MG CoI from both ankles were further related to the magnitude of the total impact force on landing (r=0.54 and 0.53, respectively; p<0.05). We concluded that male basketball players with less accurate ankle joint sense adopted greater co-contraction of ankle dorsiflexors and platarflexors, which was in turn associated with greater impact force at the moment of landing.

  1. Comparative study on isokinetic capacity of knee and ankle joints by functional injury

    PubMed Central

    Jeon, Kyoungkyu; Seo, Byoung-Do; Lee, Sang-Ho

    2016-01-01

    [Purpose] To collect basic data for exercise programs designed to enhance functional knee and ankle joint stability based on isokinetic measurement and muscle strength evaluations in normal and impaired functional states. [Subjects and Methods] Twenty-four subjects were randomly assigned to the athlete group and the control group (n = 12 each). Data were collected of isokinetic knee extensor and flexor strength at 60°/sec, 180°/sec, and 240°/sec and ankle plantar and dorsiflexor strength at 30°/sec and 120°/sec. [Results] Significant intergroup differences were observed in peak torque of the right extensors at 60°/sec, 180°/sec, and 240°/sec and the right flexors at 240°/sec. Significant differences were observed in peak torque/body weight in the right extensors at 60°/sec, 180°/sec, and 240°/sec and in the right flexors at 180°/sec and 240°/sec. Significant peak torque differences were noted in the left ankle joint dorsiflexor at 30°/sec and 120°/sec, right plantar flexor at 120°/sec, left plantar flexor at 30°/sec, left dorsiflexor at 30°/sec and 120°/sec, and right dorsiflexor at 120°/sec. [Conclusion] Isokinetic evaluation stimulates muscle contraction at motion-dependent speeds and may contribute to the development of intervention programs to improve knee and ankle joint function and correct lower-extremity instability. PMID:26957768

  2. Synaptic Control of Motoneuronal Excitability

    PubMed Central

    Rekling, Jens C.; Funk, Gregory D.; Bayliss, Douglas A.; Dong, Xiao-Wei; Feldman, Jack L.

    2016-01-01

    Movement, the fundamental component of behavior and the principal extrinsic action of the brain, is produced when skeletal muscles contract and relax in response to patterns of action potentials generated by motoneurons. The processes that determine the firing behavior of motoneurons are therefore important in understanding the transformation of neural activity to motor behavior. Here, we review recent studies on the control of motoneuronal excitability, focusing on synaptic and cellular properties. We first present a background description of motoneurons: their development, anatomical organization, and membrane properties, both passive and active. We then describe the general anatomical organization of synaptic input to motoneurons, followed by a description of the major transmitter systems that affect motoneuronal excitability, including ligands, receptor distribution, pre- and postsynaptic actions, signal transduction, and functional role. Glutamate is the main excitatory, and GABA and glycine are the main inhibitory transmitters acting through ionotropic receptors. These amino acids signal the principal motor commands from peripheral, spinal, and supraspinal structures. Amines, such as serotonin and norepinephrine, and neuropeptides, as well as the glutamate and GABA acting at metabotropic receptors, modulate motoneuronal excitability through pre- and postsynaptic actions. Acting principally via second messenger systems, their actions converge on common effectors, e.g., leak K+ current, cationic inward current, hyperpolarization-activated inward current, Ca2+ channels, or presynaptic release processes. Together, these numerous inputs mediate and modify incoming motor commands, ultimately generating the coordinated firing patterns that underlie muscle contractions during motor behavior. PMID:10747207

  3. Characterization of postsynaptic potentials evoked by sural nerve stimulation in hindlimb motoneurons from acute and chronic spinal cats.

    PubMed

    Baker, L L; Chandler, S H

    1987-09-15

    The purpose of this study was to characterize the changes in postsynaptic potentials recorded in ankle extensor motoneurons resulting from activation of the sural nerve after spinal cord transection in the adult cat. Eight acute and nine chronic animals were spinalized at T12. Intracellular recordings from motoneurons innervating the triceps surae were performed. Sural nerve stimulation evoked complex synaptic potentials consisting of early and late components in all motoneurons. Early excitatory and inhibitory postsynaptic potentials (PSPs), as well as long latency excitatory postsynaptic potentials were recorded and averaged for assessment of PSP amplitude and duration. Early PSPs, both excitatory and inhibitory, were significantly larger in the motoneurons of cats spinalized 4-6 months earlier. Central latency of excitatory potentials were similar in the two samples of motoneurons, but the central latency associated with the initial inhibitory PSP was significantly shorter in the recordings from motoneurons of chronic spinal cats. In most recordings, an additional inhibitory PSP followed the initial excitatory PSP in motoneurons, and this secondary inhibitory PSP was similar in peak amplitude and duration in both samples of motoneurons. Also, a long latency excitatory PSP was recorded in a large percentage of motoneurons from both samples. This potential was typically of greater amplitude and longer duration in the motoneurons from chronic animals, when compared to recordings from acute animals. Although changes in amplitude and duration of PSP activity could be documented, there was no marked alteration in the frequency of occurrence of each PSP pattern recorded from the two preparations. This suggests that the synaptic pathways mediating the sural nerve reflexes have not qualitatively changed in the chronic spinal animal. The changes in amplitudes and durations of the PSPs in the chronic spinal cat indicate, however, that quantitative changes have occurred

  4. A Novel Neuromuscular Electrical Stimulation Treatment for Recovery of Ankle Dorsiflexion in Chronic Hemiplegia

    PubMed Central

    Knutson, Jayme S.; Chae, John

    2011-01-01

    Objective To evaluate the feasibility of improving active ankle dorsiflexion with contralaterally controlled neuromuscular electrical stimulation (CCNMES). Design CCNMES dorsiflexes the paretic ankle with a stimulation intensity that is directly proportional to the degree of voluntary dorsiflexion of the unimpaired contralateral ankle, which is detected by an instrumented sock. Three subjects with chronic (>6-mo poststroke) dorsiflexor paresis participated in a 6-wk CCNMES treatment, which consisted of self-administering CCNMES-assisted ankle dorsiflexion exercises at home daily and practicing an ankle motor control task in the research laboratory twice a week. Results For subjects 1 and 2, respectively, maximum voluntary ankle dorsiflexion increased by 13 and 17 degrees, ankle movement tracking error decreased by ~57% and 57%, and lower limb Fugl-Meyer score (maximum score is 34) increased by 4 and 5 points. Subject 3 had no appreciable improvement in these measures. Both subjects 1 and 2 maintained their performance in ankle movement tracking through the 3-mo follow-up; subject 2 also maintained the gains in maximum ankle dorsiflexion and Fugl-Meyer score. Conclusions These results suggest that CCNMES may have a positive effect on ankle motor impairment in some stroke survivors. Further investigation of the effect of CCNMES on gait is warranted. PMID:20531158

  5. Ankle Sprains

    MedlinePlus

    ... the sole of the foot is facing inwards, stretching and possibly damaging the ligaments on the outer ... sprains: Always warm up and use the recommended stretching techniques for your ankles before playing sports, exercising, ...

  6. Ankle replacement

    MedlinePlus

    ... is surgery to replace the damaged bone and cartilage in the ankle joint. Artificial joint parts (prosthetics) ... Your surgeon will remove the damaged bone and cartilage. Your surgeon will replace the damaged part of: ...

  7. Sprained Ankles

    MedlinePlus

    ... are usually stronger than the growing bones and cartilage to which they are attached. Therefore, the growing part of the bone might separate or tear away before the ligament is injured. Types of Sprains In young children, the ankle is ...

  8. Effects of ankle biofeedback training on strength, balance, and gait in patients with stroke

    PubMed Central

    Kim, Sung-jin; Cho, Hwi-young; Kim, Kyung-hoon; Lee, Suk-min

    2016-01-01

    [Purpose] This study aimed to investigate the effects of ankle biofeedback training on muscle strength of the ankle joint, balance, and gait in stroke patients. [Subjects and Methods] Twenty-seven subjects who had had a stroke were randomly allocated to either the ankle biofeedback training group (n=14) or control group (n=13). Conventional therapy, which adhered to the neurodevelopmental treatment approach, was administered to both groups for 30 minutes. Furthermore, ankle strengthening exercises were performed by the control group and ankle biofeedback training by the experimental group, each for 30 minutes, 5 days a week for 8 weeks. To test muscle strength, balance, and gait, the Biodex isokinetic dynamometer, functional reach test, and 10 m walk test, respectively, were used. [Results] After the intervention, both groups showed a significant increase in muscle strength on the affected side and improved balance and gait. Significantly greater improvements were observed in the balance and gait of the ankle biofeedback training group compared with the control group, but not in the strength of the dorsiflexor and plantar flexor muscles of the affected side. [Conclusion] This study showed that ankle biofeedback training significantly improves muscle strength of the ankle joint, balance, and gait in patients with stroke. PMID:27799701

  9. Compensatory strategies during walking in response to excessive muscle co-contraction at the ankle joint.

    PubMed

    Wang, Ruoli; Gutierrez-Farewik, Elena M

    2014-03-01

    Excessive co-contraction causes inefficient or abnormal movement in several neuromuscular pathologies. How synergistic muscles spanning the ankle, knee and hip adapt to co-contraction of ankle muscles is not well understood. This study aimed to identify the compensation strategies required to retain normal walking with excessive antagonistic ankle muscle co-contraction. Muscle-actuated simulations of normal walking were performed to quantify compensatory mechanisms of ankle and knee muscles during stance in the presence of normal, medium and high levels of co-contraction of antagonistic pairs gastrocnemius+tibialis anterior and soleus+tibialis anterior. The study showed that if co-contraction increases, the synergistic ankle muscles can compensate; with gastrocmemius+tibialis anterior co-contraction, the soleus will increase its contribution to ankle plantarflexion acceleration. At the knee, however, almost all muscles spanning the knee and hip are involved in compensation. We also found that ankle and knee muscles alone can provide sufficient compensation at the ankle joint, but hip muscles must be involved to generate sufficient knee moment. Our findings imply that subjects with a rather high level of dorsiflexor+plantarflexor co-contraction can still perform normal walking. This also suggests that capacity of other lower limb muscles to compensate is important to retain normal walking in co-contracted persons. The compensatory mechanisms can be useful in clinical interpretation of motion analyses, when secondary muscle co-contraction or other deficits may present simultaneously in subjects with motion disorders.

  10. Postnatal growth of genioglossal motoneurons.

    PubMed

    Brozanski, B S; Guthrie, R D; Volk, E A; Cameron, W E

    1989-01-01

    The postnatal growth of kitten genioglossal motoneurons were examined in six different age groups (newborn, 2, 4, 8, and 12 weeks and adult) using the technique of retrograde transport of horseradish peroxidase (HRP). The cell bodies of 100-150 motoneurons in each age group were analyzed in a transverse plane of section using standard techniques. Somatic genioglossal motoneuron growth occurred primarily along the major axis, which increased from 25.2 microns to 41.3 microns between birth and 8 weeks of postnatal age, after which time there was no further increase in either major or minor dimension of the cell body. The form factor decreased from 0.94 to 0.80 from birth to adulthood indicating an increased eccentricity of the cell body. The number of primary dendrites visible with this technique remained constant throughout the postnatal period. Calculated somal surface area increased in a linear fashion from birth through 8 weeks of postnatal life. There was no further increase in surface area beyond this age. The rate of increase in somal surface area with age was significantly different from both the rate of increase of animal weight and animal surface area with age. The correlations between the demonstrated immature genioglossal morphology and its cellular electrophysiology or integrated respiratory function remain unknown. The recent demonstration of decreased activation of the genioglossus muscle following airway occlusion in premature infants with apnea suggests that the relationships between developing genioglossal motoneuron structure and function warrant further investigation.

  11. Ankle replacement - discharge

    MedlinePlus

    You had an ankle replacement. Your surgeon removed and reshaped damaged bones, and put in an artificial ankle joint. You received pain medicine and were shown how to treat swelling around your new ankle joint.

  12. Chronic Ankle Instability

    MedlinePlus

    ... foot and ankle surgeons. All Fellows of the College are board certified by the American Board of Foot and Ankle Surgery. Copyright © 2017 American College of Foot and Ankle Surgeons (ACFAS), All Rights ...

  13. A portable powered ankle-foot orthosis for rehabilitation.

    PubMed

    Shorter, K Alex; Kogler, Géza F; Loth, Eric; Durfee, William K; Hsiao-Wecksler, Elizabeth T

    2011-01-01

    Innovative technological advancements in the field of orthotics, such as portable powered orthotic systems, could create new treatment modalities to improve the functional out come of rehabilitation. In this article, we present a novel portable powered ankle-foot orthosis (PPAFO) to provide untethered assistance during gait. The PPAFO provides both plantar flexor and dorsiflexor torque assistance by way of a bidirectional pneumatic rotary actuator. The system uses a portable pneumatic power source (compressed carbon dioxide bottle) and embedded electronics to control the actuation of the foot. We collected pilot experimental data from one impaired and three nondisabled subjects to demonstrate design functionality. The impaired subject had bilateral impairment of the lower legs due to cauda equina syndrome. We found that data from nondisabled walkers demonstrated the PPAFO's capability to provide correctly timed plantar flexor and dorsiflexor assistance during gait. Reduced activation of the tibialis anterior during stance and swing was also seen during assisted nondisabled walking trials. An increase in the vertical ground reaction force during the second half of stance was present during assisted trials for the impaired subject. Data from nondisabled walkers demonstrated functionality, and data from an impaired walker demonstrated the ability to provide functional plantar flexor assistance.

  14. Total ankle joint replacement.

    PubMed

    2016-02-01

    Ankle arthritis results in a stiff and painful ankle and can be a major cause of disability. For people with end-stage ankle arthritis, arthrodesis (ankle fusion) is effective at reducing pain in the shorter term, but results in a fixed joint, and over time the loss of mobility places stress on other joints in the foot that may lead to arthritis, pain and dysfunction. Another option is to perform a total ankle joint replacement, with the aim of giving the patient a mobile and pain-free ankle. In this article we review the efficacy of this procedure, including how it compares to ankle arthrodesis, and consider the indications and complications.

  15. Shank Muscle Strength Training Changes Foot Behaviour during a Sudden Ankle Supination

    PubMed Central

    Hagen, Marco; Lescher, Stephanie; Gerhardt, Andreas; Lahner, Matthias; Felber, Stephan; Hennig, Ewald M.

    2015-01-01

    Background The peroneal muscles are the most effective lateral stabilisers whose tension braces the ankle joint complex against excessive supination. The purpose of this study was to identify the morphological and biomechanical effects of two machine-based shank muscle training methods. Methods Twenty-two healthy male recreationally active sports students performed ten weeks of single-set high resistance strength training with 3 training sessions per week. The subjects conducted subtalar pronator/supinator muscle training (ST) with the right leg by using a custom-made apparatus; the left foot muscles were exercised with machine-based talocrural plantar and dorsiflexor training (TT). Muscle strength (MVIC), muscle volume and foot biomechanics (rearfoot motion, ground reaction forces, muscle reaction times) during a sudden ankle supination were recorded before and after the intervention. Results Compared to TT, ST resulted in significantly higher pronator (14% vs. 8%, P<0.01) and supinator MVIC (25% vs. 12%, P<0.01). During sudden foot inversions, both ST and TT resulted in reduced supination velocity (-12%; P<0.01). The muscle reaction onset time was faster after the training in peroneus longus (PL) (P<0.01). Muscle volume of PL (P<0.01) and TA (P<0.01) increased significantly after both ST and TT. Conclusion After both ST and TT, the ankle joint complex is mechanically more stabilised against sudden supinations due to the muscle volume increase of PL and TA. As the reduced supination velocities indicate, the strength training effects are already present during free-fall. According to a sudden ankle supination in standing position, both machine-based dorsiflexor and pronator strength training is recommended for enhancing the mechanical stability of the ankle. PMID:26110847

  16. Experimental evaluation of a portable powered ankle-foot orthosis.

    PubMed

    Shorter, Kenneth A; Li, Yifan; Morris, Emily A; Kogler, Géza F; Hsiao-Wecksler, Elizabeth T

    2011-01-01

    Ankle-foot orthoses (AFOs) ameliorate the impact of impairments to the lower limb neuromuscular motor system that affect gait. Emerging technologies provide a vision for fully powered, untethered AFOs. The portable powered AFO (PPAFO) provides both plantarflexor and dorsiflexor torque assistance via a bi-directional pneumatic rotary actuator. The system uses a portable pneumatic power source (bottle of compressed CO(2)) and embedded electronics to control foot motion during level walking. Experimental data were collected to demonstrate functionality from two subjects with bilateral impairments to the lower legs. These data demonstrated the PPAFO's ability to provide functional assistance during gait. The stringent design requirements of light weight, small size, high efficiency and low noise make the creation of daily wear assist devices challenging; but once such devices appear, they will present new opportunities for clinical treatment of gait abnormalities.

  17. The Effect of Ankle Joint Muscle Strengthening Training and Static Muscle Stretching Training on Stroke Patients’ C.O.P Sway Amplitude

    PubMed Central

    Kim, Tae Ho; Yoon, Joo Soo; Lee, Jin Hwan

    2014-01-01

    [Purpose] This study implement ankle joint dorsiflexion training for ankle muscle the weakness that impairs stroke patients’ gait performance, to examine the effect of the training on stroke patients’ plantar pressure and gait ability. [Subjects and Methods] In this study, 36 stroke patients diagnosed with stroke due to cerebral infarction or cerebral hemorrhage performed the training. Static muscle stretching was performed four times a week for 20 minutes at a time for 6 weeks by the training group. Ankle dorsiflexor training was performed four times a week, two sets per time in the case of females and three sets per time in the case of males for 6 weeks, by another group. Center of pressure sway amplitude was measured using the F-scan system during gait. All subjects were assessed with the same measurements at a pre-study examination and reassessed at eight weeks. Data were analyzed statistically using the paired t-test and one-way ANOVA. [Results] Among the between ankle dorsiflexor training group, static muscle stretching group, and control group, the difference before and after the training were proven to be statistically significant. [Conclusion] Compared to other training groups, the ankle muscle strength training group showed statistically significant increases of forward thrust at stroke patients’ toe-off which positively affected stroke patients’ ability to perform gait. PMID:24409032

  18. Effect of Wiihabilitation on strength ratio of ankle muscles in adults

    PubMed Central

    Khalil, Aya A.; Mohamed, Ghada A.; El Rahman, Soheir M. Abd; Elhafez, Salam M.; Nassif, Nagui S.

    2016-01-01

    [Purpose] This study was conducted to investigate the effect of Wiihabilitation on the ankle dorsiflexion/plantar flexion strength ratio in adults. [Subjects and Methods] Thirty-two healthy male volunteers were randomly assigned to two equal groups (experimental and control). Participants in the experimental group received a Wiihabilitation training program for six weeks. Data were collected using a Biodex system 3 Isokinetic dynamometer. Peak torques of the dorsiflexors and plantar flexors were measured at an angular velocity of 60°/sec which in turn were used to derive the ankle dorsiflexion/plantar flexion strength ratio. [Results] The mean values of the ankle dorsiflexion/plantar flexion strength ratio decreased significantly between before and after the training in the experimental group, meanwhile there was no significant difference between before and after the training period in the control group . [Conclusion] Wiihabilitation has an impact on the ankle dorsiflexion/plantar flexion strength ratio, so it can be considered an effective training tool in terms of the ankle strength ratio. Thus, it could be recommended for both prevention and rehabilitation of ankle instability patients. PMID:27821951

  19. Effect of ankle proprioceptive training on static body balance

    PubMed Central

    Karakaya, Mehmet Gürhan; Rutbİl, Hİlal; Akpinar, Ercan; Yildirim, Alİ; Karakaya, İlkİm Çitak

    2015-01-01

    [Purpose] This study aimed to investigate the effect of ankle proprioceptive training on static body balance. [Subjects and Methods] In this randomized-controlled, single-blind study, 59 university students (35 females, 24 males) were randomized into study (n=29) and control (n=30) groups. The study group received a foot and ankle proprioceptive exercise program including stretching, strengthening (plantar and dorsi-flexors, invertor and evertor muscles), and balance board exercises, each with 10 repetitions per session, 5 days a week, for a total of 10 sessions. The control group did not receive any intervention. Static body balance was evaluated by a kinesthetic ability trainer, which showed the balance index scores under both single foot and both feet conditions. This evaluation was repeated at the end of two weeks for both groups. [Results] Outcome measures of the groups were similar at the baseline. Balance index scores of both groups improved at the end of two weeks, and the study group had significantly lower index scores than those of the control group, indicating better balance. [Conclusion] Ankle proprioceptive training had positive effects on static body balance parameters in healthy individuals, and it is worth investigating the effects of this type of training in patients with balance disorders. PMID:26644697

  20. Discharge properties of motor units during steady isometric contractions performed with the dorsiflexor muscles.

    PubMed

    Jesunathadas, Mark; Klass, Malgorzata; Duchateau, Jacques; Enoka, Roger M

    2012-06-01

    The purpose of this study was to record the discharge characteristics of tibialis anterior motor units over a range of target forces and to import these data, along with previously reported observations, into a computational model to compare experimental and simulated measures of torque variability during isometric contractions with the dorsiflexor muscles. The discharge characteristics of 44 motor units were quantified during brief isometric contractions at torques that ranged from recruitment threshold to an average of 22 ± 14.4% maximal voluntary contraction (MVC) torque above recruitment threshold. The minimal [range: 5.8-19.8 pulses per second (pps)] and peak (range: 8.6-37.5 pps) discharge rates of motor units were positively related to the recruitment threshold torque (R(2) ≥ 0.266; P < 0.001). The coefficient of variation for interspike interval at recruitment was positively associated with recruitment threshold torque (R(2) = 0.443; P < 0.001) and either decreased exponentially or remained constant as target torque increased above recruitment threshold torque. The variability in the simulated torque did not differ from the experimental values once the recruitment range was set to ∼85% MVC torque, and the association between motor twitch contraction times and peak twitch torque was defined as a weak linear association (R(2) = 0.096; P < 0.001). These results indicate that the steadiness of isometric contractions performed with the dorsiflexor muscle depended more on the distributions of mechanical properties than discharge properties across the population of motor units in the tibialis anterior.

  1. The effects of posterior talar glide with dorsiflexion of the ankle on mobility, muscle strength and balance in stroke patients: a randomised controlled trial

    PubMed Central

    Lee, Jin; Kim, Ju-O; Lee, Byoung-Hee

    2017-01-01

    [Purpose] The purpose of this study was to examine the effectiveness of posterior talar glide (PTG) with dorsiflexion of the ankle on stroke patients ankle mobility, muscle strength, and balance ability. [Subjects and Methods] Thirty-four subjects were randomly assigned to either a PTG with dorsiflexion group (PTG; n=17), or a weight-bearing with placebo PTG group (control; n=17). Subjects in the PTG group performed PTG with dorsiflexion, designed to improve ankle mobility, muscle strength and balance ability with proprioceptive control of the ankle, for 10 glides of 5 sets/day, 5 days/week, for 4 weeks. [Results] The experimental group showed significant improvement on the Ankle Dorsiflexion Range of Motion assessment, Ankle Dorsiflexor Manual Muscle Test, Functional Reach Test, Time Up and Go test, and Functional Gait Assessment compared to the control group. However, regarding Ankle Plantarflexion Range of Motion assessment and the Ankle Plantarflexor Manual Muscle Test, no significant differences were found between the two groups. [Conclusion] The results of this study show that PTG with dorsiflexion can improve ankle mobility, muscle strength and balance ability in patients recovering from stroke. This exercise may prove useful in clinical rehabilitation. Further research on the long-term effectiveness of PTG on gait ability is suggested. PMID:28356629

  2. Adaptability of the oxidative capacity of motoneurons

    NASA Technical Reports Server (NTRS)

    Chalmers, G. R.; Roy, R. R.; Edgerton, V. R.

    1992-01-01

    Previous studies have demonstrated that a chronic change in neuronal activation can produce a change in soma oxidative capacity, suggesting that: (i) these 2 variables are directly related in neurons and (ii) ion pumping is an important energy requiring activity of a neuron. Most of these studies, however, have focused on reduced activation levels of sensory systems. In the present study the effect of a chronic increase or decrease in motoneuronal activity on motoneuron oxidative capacity and soma size was studied. In addition, the effect of chronic axotomy was studied as an indicator of whether cytoplasmic volume may also be related to the oxidative capacity of motoneurons. A quantitative histochemical assay for succinate dehydrogenase activity was used as a measure of motoneuron oxidative capacity in experimental models in which chronic electromyography has been used to verify neuronal activity levels. Spinal transection reduced, and spinal isolation virtually eliminated lumbar motoneuron electrical activity. Functional overload of the plantaris by removal of its major synergists was used to chronically increase neural activity of the plantaris motor pool. No change in oxidative capacity or soma size resulted from either a chronic increase or decrease in neuronal activity level. These data indicate that the chronic modulation of ionic transport and neurotransmitter turnover associated with action potentials do not induce compensatory metabolic responses in the metabolic capacity of the soma of lumbar motoneurons. Soma oxidative capacity was reduced in the axotomized motoneurons, suggesting that a combination of axoplasmic transport, intracellular biosynthesis and perhaps neurotransmitter turnover represent the major energy demands on a motoneuron. While soma oxidative capacity may be closely related to neural activity in some neural systems, e.g. visual and auditory, lumbar motoneurons appear to be much less sensitive to modulations in chronic activity levels.

  3. Assessment of Ankle Injuries

    ERIC Educational Resources Information Center

    Mai, Nicholas; Cooper, Leslie

    2009-01-01

    School nurses are faced with the challenge of identifying and treating ankle injuries in the school setting. There is little information guiding the assessment and treatment of these children when an injury occurs. It is essential for school nurses to understand ankle anatomy, pathophysiology of the acute ankle injury, general and orthopedic…

  4. Development of an efficient rehabilitation exercise program for functional recovery in chronic ankle instability

    PubMed Central

    Kim, Kewwan; Jeon, Kyoungkyu

    2016-01-01

    [Purpose] The aim of the present study was to construct an integrated rehabilitation exercise program to prevent chronic pain and improve motor ability in cases of ankle injury and re-injury. [Subjects and Methods] Twenty-six male soccer players who required functional strength exercises due to repeated ankle injury were the subjects. A 12-week rehabilitation exercise program was constructed with the aim of improving muscle strength in the ankle and dynamic coordination of the lower limb. Muscle strength and dynamic coordination were evaluated using the Y Balance Test, and isokinetic muscle strength of ankle dorsiflexion, plantarflexion, inversion, and eversion were measured before and after the 12-week program. [Results] Following 12 weeks of rehabilitation exercise, there were statistically significant improvements in the ratios of dorsiflexor strength to plantarflexor strength, eversion strength, and inversion strength on the left side. The other variables showed no significant changes. [Conclusion] The rehabilitation exercise program for chronic ankle instability helped to reduce pain, and to restore normal joint range of motion, muscle strength and endurance, and functional ability. Active protocols to improve complex functions need to be developed to complement these results. PMID:27313347

  5. Fatigability of the dorsiflexors and associations among multiple domains of motor function in young and old adults.

    PubMed

    Justice, Jamie N; Mani, Diba; Pierpoint, Lauren A; Enoka, Roger M

    2014-07-01

    Declines in neuromuscular function, including measures of mobility, muscle strength, steadiness, and patterns of muscle activation, accompany advancing age and are often associated with reduced quality of life and mortality. Paradoxically, older adults are less fatigable than young adults in some tasks. The purpose of this study was to determine the influence of age on fatigability of the dorsiflexors and to evaluate the ecological validity of this test by comparing it to motor function subdomains known to decline with advancing age. The community-dwelling older adults (n=52, 75.2±6.0years) were more fatigable than young adults (n=26, 22.2±3.7years), as assessed by endurance time for supporting a submaximal load (20% of one-repetition maximum; 1-RM) with an isometric contraction of the dorsiflexor muscles (8.9±0.6min and 15.5±0.9min, p<0.001), including participants matched for 1-RM load and sex (Y: 13.3±4.0min, O: 8.5±6.1min, n=11 pairs, 6 women, p<0.05). When the older adults were separated into two groups (65-75 and 76-90years), however, only endurance time for the oldest group was less than that for the other two groups (p<0.01). All measures of motor function were significantly correlated (all p<0.05) with dorsiflexor endurance time for the older adults, and multiple regression analysis revealed that the variance in endurance time was most closely associated with age, steadiness, and knee flexor strength (R(2)=0.50, p<0.001). These findings indicate that dorsiflexor fatigability provides a valid biomarker of motor function in older adults.

  6. Sigma-1 Receptor in Motoneuron Disease.

    PubMed

    Mancuso, Renzo; Navarro, Xavier

    2017-01-01

    Amyotrophic Lateral Sclerosis (ALS ) is a neurodegenerative disease affecting spinal cord and brain motoneurons , leading to paralysis and early death. Multiple etiopathogenic mechanisms appear to contribute in the development of ALS , including glutamate excitotoxicity, oxidative stress , protein misfolding, mitochondrial defects, impaired axonal transport, inflammation and glial cell alterations. The Sigma-1 receptor is highly expressed in motoneurons of the spinal cord, particularly enriched in the endoplasmic reticulum (ER) at postsynaptic cisternae of cholinergic C-terminals. Several evidences point to participation of Sigma-1R alterations in motoneuron degeneration. Thus, mutations of the transmembrane domain of the Sigma-1R have been described in familial ALS cases. Interestingly, Sigma-1R KO mice display muscle weakness and motoneuron loss. On the other hand, Sigma-1R agonists promote neuroprotection and neurite elongation through activation of protein kinase C on motoneurons in vitro and in vivo after ventral root avulsion. Remarkably, treatment of SOD1 mice, the most usual animal model of ALS , with Sigma-1R agonists resulted in significantly enhanced motoneuron function and preservation, and increased animal survival. Sigma-1R activation also reduced microglial reactivity and increased the glial expression of neurotrophic factors. Two main interconnected mechanisms seem to underlie the effects of Sigma-1R manipulation on motoneurons: modulation of neuronal excitability and regulation of calcium homeostasis. In addition, Sigma-1R also contributes to regulating protein degradation, and reducing oxidative stress. Therefore, the multi-functional nature of the Sigma-1R represents an attractive target for treating aspects of ALS and other motoneuron diseases .

  7. Physiological coxa varus-genu valgus influences internal knee and ankle joint moments in females during crossover cutting.

    PubMed

    Nyland, J A; Caborn, D N M

    2004-07-01

    This study evaluated the ankle and knee electromyographic, kinematic, and kinetic differences of 20 nonimpaired females with either neutral (group 1) or coxa varus-genu valgus (group 2) alignment during crossover cutting stance phase. Two-way mixed model ANOVA (group, session) assessed mean differences ( p<0.05) and correlation analysis further delineated relationships. During impact absorption, group 2 displayed earlier peak horizontal braking (anterior-posterior) ground reaction force timing, decreased and earlier peak internal knee extension moments (eccentric function), and earlier peak internal ankle dorsiflexion moment timing (eccentric function). During the pivot phase, group 2 displayed later and eccentrically-biased peak ankle plantar flexion moments, increased peak internal knee flexion moments (eccentric function), and later peak knee internal rotation timing. Correlation analysis revealed that during impact absorption, subjects with coxa varus-genu valgus alignment (group 2) displayed a stronger relationship between knee internal rotation velocity and peak internal ankle dorsiflexion moment onset timing ( r= -0.64 vs r = -0.26) and between peak horizontal braking ground reaction forces and peak internal ankle dorsiflexion moment onset timing ( r= 0.61 vs r= 0.24). During the pivot phase these subjects displayed a stronger relationship between peak horizontal braking ground reaction forces and peak internal ankle plantar flexion moment onset timing ( r= -0.63 vs r= -0.09) and between peak horizontal braking forces and peak internal ankle plantar flexion moments ( r= -0.72 vs r= -0.26). Group differences suggest that subjects with coxa varus-genu valgus frontal-plane alignment have an increased dependence on both ankle dorsiflexor and plantar flexor muscle group function during crossover cutting. Greater dependence on ankle muscle group function during the performance of a task that requires considerable 3D dynamic knee joint control suggests a greater

  8. Intracellular autogenetic and synergistic effects of muscular contraction on flexor motoneurones

    PubMed Central

    Green, D. G.; Kellerth, J.-O.

    1967-01-01

    1. Intracellular records have been taken from cat motoneurones innervating flexor muscles of the hind limb. Contractions of the ankle flexors tibialis anterior and extensor digitorum longus were elicited by stimulation of the peripheral end of the cut L 7 ventral root and the reflex effects of these contractions were recorded in silent and repetitively firing motoneurones. 2. Contraction usually produces a hyperpolarizing response inside flexor motoneurones. This hyperpolarization is tension-sensitive in the sense that when, at constant muscle extension, the strength of the contraction is increased, the magnitude of the inhibitory response is augmented. 3. Increasing the resting length of the muscles, while using a stimulus of constant strength to the ventral root, causes this inhibitory response to increase in some cells. More often, however, the hyperpolarization caused by contraction is gradually reduced in duration and/or amplitude as the muscles are extended. 4. Even with the muscles slackened, so that they develop no tension at their ends, contraction usually produces prominent hyperpolarization of the motoneurones. 5. By passing polarizing currents or injecting chloride ions through the intracellular micro-electrode, the hyperpolarizing potentials produced by contraction of the slack and extended muscles are shown to be, at least in part, genuinely post-synaptic inhibitory events. 6. When the neurone is fired repetitively by injected current, the `silent period' in contraction corresponds to the hyperpolarization of the post-synaptic membrane. 7. Monosynaptic testing of the flexor motoneurone pool has been used to confirm the essential features of the intracellularly recorded activity. 8. Acutely spinalizing the animal increases the magnitude of the inhibitory responses caused by contraction. 9. Recordings from dorsal root fibres show that Golgi tendon organs of the ankle flexors are very sensitive to contraction and are indeed often activated by the

  9. Modulation of motoneuron activity by serotonin.

    PubMed

    Perrier, Jean-François

    2016-02-01

    Serotonin is a major neuromodulator in the central nervous system involved in most physiological functions including appetite regulation, sexual arousal, sleep regulation and motor control. The activity of neurons from the raphe spinal tract, which release serotonin on motoneurons, is positively correlated with motor behaviour. During moderate physical activity, serotonin is released from synaptic terminals onto the dendrites and cell bodies of motoneurons. Serotonin increases the excitability of motoneurons and thereby facilitate muscle contraction by acting on several parallel intracellular pathways. By activating 5-HT1A receptors, serotonin inhibits TWIK-related acid-sensitive potassium channels and small conductance calcium-activated potassium channels. In parallel, serotonin binds to 5-HT2 receptors, which promotes the low-threshold L-type Ca(2+) channels. During intense physical activity, more serotonin is released. The reuptake systems saturate and serotonin spills over to reach extrasynaptic 5-HT1A receptors located on the axon initial segment of motoneurons. This in turn induces the inhibition of the Na(+) channels responsible for the initiation of action potentials. Fewer nerve impulses are generated and muscle contraction becomes weaker. By decreasing the gain of motoneurons, serotonin triggers central fatigue.

  10. Ankle Fractures Often Not Diagnosed

    MedlinePlus

    ... foot and ankle surgeons. All Fellows of the College are board certified by the American Board of Foot and Ankle Surgery. Copyright © 2017 American College of Foot and Ankle Surgeons (ACFAS), All Rights ...

  11. Defects in Motoneuron-Astrocyte Interactions in Spinal Muscular Atrophy.

    PubMed

    Zhou, Chunyi; Feng, Zhihua; Ko, Chien-Ping

    2016-02-24

    Spinal muscular atrophy (SMA) is a motoneuron disease caused by loss or mutation in Survival of Motor Neuron 1 (SMN1) gene. Recent studies have shown that selective restoration of SMN protein in astrocytes partially alleviates pathology in an SMA mouse model, suggesting important roles for astrocytes in SMA. Addressing these underlying mechanisms may provide new therapeutic avenues to fight SMA. Using primary cultures of pure motoneurons or astrocytes from SMNΔ7 (SMA) and wild-type (WT) mice, as well as their mixed and matched cocultures, we characterized the contributions of motoneurons, astrocytes, and their interactions to synapse loss in SMA. In pure motoneuron cultures, SMA motoneurons exhibited normal survival but intrinsic defects in synapse formation and synaptic transmission. In pure astrocyte cultures, SMA astrocytes exhibited defects in calcium homeostasis. In motoneuron-astrocyte contact cocultures, synapse formation and synaptic transmission were significantly reduced when either motoneurons, astrocytes or both were from SMA mice compared with those in WT motoneurons cocultured with WT astrocytes. The reduced synaptic activity is unlikely due to changes in motoneuron excitability. This disruption in synapse formation and synaptic transmission by SMN deficiency was not detected in motoneuron-astrocyte noncontact cocultures. Additionally, we observed a downregulation of Ephrin B2 in SMA astrocytes. These findings suggest that there are both cell autonomous and non-cell-autonomous defects in SMA motoneurons and astrocytes. Defects in contact interactions between SMA motoneurons and astrocytes impair synaptogenesis seen in SMA pathology, possibly due to the disruption of the Ephrin B2 pathway.

  12. Chronic ankle instability: Current perspectives

    PubMed Central

    Al-Mohrej, Omar A.; Al-Kenani, Nader S.

    2016-01-01

    Ankle sprain is reported to be among the most common recurrent injuries. About 20% of acute ankle sprain patients develop chronic ankle instability. The failure of functional rehabilitation after acute ankle sprain leads to the development of chronic ankle instability. Differentiation between functional and anatomical ankle instability is very essential to guide the proper treatment. Stability testing by varus stress test and anterior drawer test should be carried out. Subtalar instability is an important pathology that is commonly by passed during the assessment of chronic ankle instability. Unlike acute ankle sprain, chronic ankle instability might require surgical intervention. The surgical and conservative management options can be very much developed by in-depth knowledge of the ankle anatomy, biomechanics, and pathology. Anatomical repair, augmentation by tendon, or both are the basic methods of surgical intervention. Arthroscopy is becoming more popular in the management of chronic ankle instability. PMID:27843798

  13. Posterior ankle impingement syndrome.

    PubMed

    Maquirriain, Javier

    2005-10-01

    Posterior ankle impingement syndrome is a clinical disorder characterized by posterior ankle pain that occurs in forced plantar flexion. The pain may be acute as a result of trauma or chronic from repetitive stress. Pathology of the os trigonum-talar process is the most common cause of this syndrome, but it also may result from flexor hallucis longus tenosynovitis, ankle osteochondritis, subtalar joint disease, and fracture. Patients usually report chronic or recurrent posterior ankle pain caused or exacerbated by forced plantar flexion or push-off maneuvers, such as may occur during dancing, kicking, or downhill running. Diagnosis of posterior ankle impingement syndrome is based primarily on clinical history and physical examination. Radiography, scintigraphy, computed tomography, and magnetic resonance imaging depict associated bone and soft-tissue abnormalities. Symptoms typically improve with nonsurgical management, but surgery may be required in refractory cases.

  14. Antagonist mechanical contribution to resultant maximal torque at the ankle joint in young and older men.

    PubMed

    Simoneau, Emilie M; Billot, Maxime; Martin, Alain; Van Hoecke, Jacques

    2009-04-01

    A recorded muscular torque at one joint is a resultant torque corresponding to the participation of both agonist and antagonist muscles. This study aimed to examine the effect of aging on the mechanical contributions of both plantar- and dorsi-flexors to the resultant maximal voluntary contraction (MVC) torques exerted at the ankle joint, in dorsi-flexion (DF) and plantar-flexion (PF). The estimation of isometric agonist and antagonist torques by means of an EMG biofeedback technique was made with nine young (mean age 24 years) and nine older (mean age 80 years) men. While there was a non-significant age-related decline in the measured resultant DF MVC torque (-15%; p=0.06), there was a clear decrease in the estimated agonist MVC torque exerted by the dorsi-flexors (-39%; p=0.001). The DF-to-PF resultant MVC torque ratio was significantly lower in young than in older men (0.25 vs. 0.31; p=0.006), whereas the DF-to-PF agonist MVC torque ratio was no longer different between the two populations (0.38 vs. 0.35; p>0.05). Thus, agonist MVC torques in PF and DF would be similarly affected by aging, which could not be deduced when only resultant torques were examined.

  15. Modified Evans peroneus brevis lateral ankle stabilization for balancing varus ankle contracture during total ankle replacement.

    PubMed

    Roukis, Thomas S

    2013-01-01

    Lateral ankle instability is frequently encountered when performing total ankle replacement and remains a challenge. In the present techniques report, I have described a modification of the Evans peroneus brevis tendon lateral ankle stabilization harvested through limited incisions using simple topographic anatomic landmarks. The harvested peroneus brevis is then transferred either to the anterior distal tibia concomitantly with total ankle replacement or through the tibia when performed after total ankle replacement and secured with plate and screw fixation. This modified Evans peroneus brevis tendon is useful in providing lateral ankle stability during or after primary and revision total ankle replacement.

  16. Changes in GABAA receptor subunit gamma2 in extensor and flexor motoneurons and astrocytes after spinal cord transection and motor training

    PubMed Central

    Khristy, Windyanne; Ali, Noore J.; Bravo, Arlene B.; de Leon, Ray; Roy, Roland R.; Zhong, Hui; London, Nik J. L.; Edgerton, V. Reggie; Tillakaratne, Niranjala J. K.

    2009-01-01

    GABA signaling plays an important role in the spinal cord response to injury and subsequent motor training. Since benzodiazepines are commonly used to treat muscle spasticity in spinal cord injured subjects and the γ2 subunit of the GABAA receptor is necessary for benzodiazepine binding, this subunit may be an important factor modulating sensorimotor function after an injury. Changes in γ2 levels in muscle-specific motoneurons and surrounding astrocytes were determined ~3 months after a complete mid-thoracic spinal cord transection at P5 in non-trained and in step-trained spinal rats. Soleus (ankle extensor) and tibialis anterior (TA, ankle flexor) motor pools were identified using retrograde labeling via intramuscular injections of Fast Blue or Fluoro Gold, respectively. Lumbar spinal cord sections showed γ2 immunostaining in both soleus and TA motoneurons and astrocytes. γ2 immunoreactivity on the soma of soleus and TA motoneurons in spinal rats was differentially modulated. Compared to intact rats, spinal rats had higher levels of γ2 in TA, and lower levels in soleus motoneurons. Step training restored GABAA γ2 levels towards control values in motoneuronal pools of both muscles. In contrast, the γ2 levels were elevated in surrounding astrocytes of both motor pools in spinal rats, and step training had no further effect. Thus, motor training had a specific effect on those neurons that were directly involved with the motor task. Since the γ2 subunit is involved with GABAA receptor trafficking and synaptic clustering, it appears that this subunit could be an important component of the activity-dependent response of the spinal cord after a spinal injury. PMID:19358834

  17. Ankle fracture - aftercare

    MedlinePlus

    Malleolar fracture; Tri-malleolar; Bi-malleolar; Distal tibia fracture; Distal fibula fracture; Malleolus fracture ... Some ankle fractures may require surgery when: The ends of the bone are out of line with each other (displaced). The ...

  18. Postnatal development of phrenic motoneurons in the cat.

    PubMed

    Cameron, W E; Brozanski, B S; Guthrie, R D

    1990-01-01

    The postnatal growth of phrenic motoneurons in the cat was studied using retrograde transport of horseradish peroxidase (HRP). The mean somal surface area of these developing motoneurons increased 2.5 times from day 3 to adult while the mean somal volume increased four-fold. This change in mean somal surface area during postnatal development was found to be correlated with the change in mean axonal conduction velocity measured from phrenic motoneurons.

  19. Stresses in the ankle joint and total ankle replacement design.

    PubMed

    Kakkar, Rahul; Siddique, M S

    2011-06-01

    The ankle is a highly congruent joint with a surface area of 11-13 cm(2). Total ankle replacements have been attempted since the early 1970s and design has continually evolved as the early designs were a failure. This was because the stresses involved and the mutiaxial motion of the ankle has not been understood until recently. It has been shown that the talus slides as well as rolls during the ankle arc of motion from plantarflexion to dorsiflexion. Furthermore, the articular surfaces and the calcaneofibular and tibiocalcaneal ligaments have been shown to form a four bar linkage dictating ankle motion. A new design ankle replacement has been suggested recently which allows multiaxial motion at the ankle while maintaining congruency throughout the arc of motion. The early results of this ankle replacement have been encouraging without any reported failures due to mechanical loosening.

  20. Broken Ankle/Broken Foot

    MedlinePlus

    ... not warming up and stretching, also can cause foot and ankle injuries. Work in certain occupations. Certain work environments, such ... too little light may lead to falls and foot and ankle injuries. Have certain conditions. Having fragile bones (osteoporosis) or ...

  1. X-Ray Exam: Ankle

    MedlinePlus

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Ankle KidsHealth > For Parents > X-Ray Exam: Ankle A A A What's in this ... español Radiografía: tobillo What It Is An ankle X-ray is a safe and painless test that uses ...

  2. X-Ray Exam: Ankle

    MedlinePlus

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Ankle KidsHealth > For Parents > X-Ray Exam: Ankle Print A A A What's in ... español Radiografía: tobillo What It Is An ankle X-ray is a safe and painless test that uses ...

  3. Evidence for restricted central convergence of cutaneous afferents on an excitatory reflex pathway to medial gastrocnemius motoneurons.

    PubMed

    LaBella, L A; McCrea, D A

    1990-08-01

    1. We previously reported that excitatory postsynaptic potentials (EPSPs) produced by low-threshold electrical stimulation of the caudal cutaneous sural nerve (CCS) occur preferentially and with the shortest central latencies in the medial gastrocnemius (MG) portion of the triceps surae motor nuclei. The present study employs the spatial facilitation technique to assess interneuronal convergence on the short-latency excitatory pathway from CCS to MG by several other ipsilateral hindlimb afferents [the lateral cutaneous sural (LCS), caudal cutaneous femoral (CCF), saphenous (SAPH), superficial peroneal (SP), posterior tibial (TIB), and posterior articular (Joint) nerves]. 2. Spatial facilitation of CCF EPSPs in MG motoneurons was demonstrated with conditioning stimulation of the LCS, CCF, SAPH, SP, and TIB nerves, but was most readily and consistently observed with CCF conditioning. Facilitation of CCS and CCF EPSPs was obtained in individual MG motoneurons with a wide range of condition-test intervals. 3. CCF EPSPs in MG motoneurons produced by twice threshold (2T) afferent stimulation had a mean latency of 4.8 ms and often appeared as slowly rising, asynchronous potentials. On the other hand, 2T CCS EPSPs had a mean latency of 2.8 ms and appeared as sharper rising, less variable depolarizations. The optimum condition-test interval for facilitation of CCS and CCF EPSPs was found to be 5.2 ms on average, with CCS stimulation delayed from that of CCF. The longer latency of CCF EPSPs and the finding that the minimum condition-test interval was on the order of 3.9 ms suggests that convergence occurs late in the excitatory CCF pathway to MG motoneurons. 4. Convergence between excitatory pathways to MG from CCF and CCS afferents is discussed with regard to the original observations of Hagbarth on the location of cutaneous receptive fields and excitation of ankle extensors. In addition, evidence for the segregation of these specialized reflex pathways from those involved

  4. Ankle Arthroscopic Reconstruction of Lateral Ligaments (Ankle Anti-ROLL)

    PubMed Central

    Takao, Masato; Glazebrook, Mark; Stone, James; Guillo, Stéphane

    2015-01-01

    Ankle instability is a condition that often requires surgery to stabilize the ankle joint that will improve pain and function if nonoperative treatments fail. Ankle stabilization surgery may be performed as a repair in which the native existing anterior talofibular ligament or calcaneofibular ligament (or both) is imbricated or reattached. Alternatively, when native ankle ligaments are insufficient for repair, a reconstruction of the ligaments may be performed in which an autologous or allograft tendon is used to reconstruct the anterior talofibular ligament or calcaneofibular ligament (or both). Currently, ankle stabilization surgery is most commonly performed through an open incision, but arthroscopic ankle stabilization using repair techniques has been described and is being used more often. We present our technique for anatomic ankle arthroscopic reconstruction of the lateral ligaments (anti-ROLL) performed in an all–inside-out manner that is likely safe for patients and minimally invasive. PMID:26900560

  5. Ankle Arthroscopic Reconstruction of Lateral Ligaments (Ankle Anti-ROLL).

    PubMed

    Takao, Masato; Glazebrook, Mark; Stone, James; Guillo, Stéphane

    2015-10-01

    Ankle instability is a condition that often requires surgery to stabilize the ankle joint that will improve pain and function if nonoperative treatments fail. Ankle stabilization surgery may be performed as a repair in which the native existing anterior talofibular ligament or calcaneofibular ligament (or both) is imbricated or reattached. Alternatively, when native ankle ligaments are insufficient for repair, a reconstruction of the ligaments may be performed in which an autologous or allograft tendon is used to reconstruct the anterior talofibular ligament or calcaneofibular ligament (or both). Currently, ankle stabilization surgery is most commonly performed through an open incision, but arthroscopic ankle stabilization using repair techniques has been described and is being used more often. We present our technique for anatomic ankle arthroscopic reconstruction of the lateral ligaments (anti-ROLL) performed in an all-inside-out manner that is likely safe for patients and minimally invasive.

  6. Development of Connectivity in a Motoneuronal Network in Drosophila Larvae

    PubMed Central

    Couton, Louise; Mauss, Alex S.; Yunusov, Temur; Diegelmann, Soeren; Evers, Jan Felix; Landgraf, Matthias

    2015-01-01

    Summary Background Much of our understanding of how neural networks develop is based on studies of sensory systems, revealing often highly stereotyped patterns of connections, particularly as these diverge from the presynaptic terminals of sensory neurons. We know considerably less about the wiring strategies of motor networks, where connections converge onto the dendrites of motoneurons. Here, we investigated patterns of synaptic connections between identified motoneurons with sensory neurons and interneurons in the motor network of the Drosophila larva and how these change as it develops. Results We find that as animals grow, motoneurons increase the number of synapses with existing presynaptic partners. Different motoneurons form characteristic cell-type-specific patterns of connections. At the same time, there is considerable variability in the number of synapses formed on motoneuron dendrites, which contrasts with the stereotypy reported for presynaptic terminals of sensory neurons. Where two motoneurons of the same cell type contact a common interneuron partner, each postsynaptic cell can arrive at a different connectivity outcome. Experimentally changing the positioning of motoneuron dendrites shows that the geography of dendritic arbors in relation to presynaptic partner terminals is an important determinant in shaping patterns of connectivity. Conclusions In the Drosophila larval motor network, the sets of connections that form between identified neurons manifest an unexpected level of variability. Synapse number and the likelihood of forming connections appear to be regulated on a cell-by-cell basis, determined primarily by the postsynaptic dendrites of motoneuron terminals. PMID:25702582

  7. Testing the evolutionary conservation of vocal motoneurons in vertebrates.

    PubMed

    Albersheim-Carter, Jacob; Blubaum, Aleksandar; Ballagh, Irene H; Missaghi, Kianoush; Siuda, Edward R; McMurray, George; Bass, Andrew H; Dubuc, Réjean; Kelley, Darcy B; Schmidt, Marc F; Wilson, Richard J A; Gray, Paul A

    2016-04-01

    Medullary motoneurons drive vocalization in many vertebrate lineages including fish, amphibians, birds, and mammals. The developmental history of vocal motoneuron populations in each of these lineages remains largely unknown. The highly conserved transcription factor Paired-like Homeobox 2b (Phox2b) is presumed to be expressed in all vertebrate hindbrain branchial motoneurons, including laryngeal motoneurons essential for vocalization in humans. We used immunohistochemistry and in situ hybridization to examine Phox2b protein and mRNA expression in caudal hindbrain and rostral spinal cord motoneuron populations in seven species across five chordate classes. Phox2b was present in motoneurons dedicated to sound production in mice and frogs (bullfrog, African clawed frog), but not those in bird (zebra finch) or bony fish (midshipman, channel catfish). Overall, the pattern of caudal medullary motoneuron Phox2b expression was conserved across vertebrates and similar to expression in sea lamprey. These observations suggest that motoneurons dedicated to sound production in vertebrates are not derived from a single developmentally or evolutionarily conserved progenitor pool.

  8. Current thoughts on ankle arthritis.

    PubMed

    Ritterman, Scott A; Fellars, Todd A; Digiovanni, Christopher W

    2013-03-01

    The ankle is the most commonly injured joint in athletic and work activities. In contrast, osteoarthritis of the ankle joint is relatively rare and is typically post-traumatic or inflammatory in nature. Common symptoms that prompt an orthopaedic consultation include pain, disability and altered gait mechanics. Non-operative management has been the mainstay for previously undiagnosed patients. For those with advanced disease, ankle fusion or total ankle replacement may be the only surgical options. Though some recent studies have shown patients' preference for a well functioning ankle replacement, significant long- term follow-up data is lacking.

  9. Ankle sprain - slideshow

    MedlinePlus

    ... anatomy URL of this page: //medlineplus.gov/ency/presentations/100209.htm Ankle sprain - Series—Normal anatomy To use the sharing features on this page, please enable JavaScript. Go to slide 1 out of 4 Go to slide 2 ...

  10. Ankle Sprain Treatment

    MedlinePlus

    ... Treatment Page Content Article Body Acute ankle and foot injuries are common in athletes and other active young ... heels by pushing on the balls of your feet. Repeat steps 1 through 3. ... criteria Because injuries and recovery rates are different for every athlete, ...

  11. Dopamine effects on identified rat vagal motoneurons

    PubMed Central

    Zheng, Zhongling; Travagli, R. Alberto

    2011-01-01

    Catecholaminergic neurons of the A2 area play a prominent role in brain stem vagal circuits. It is not clear, however, whether these neurons are noradrenergic or adrenergic, i.e., display tyrosine hydroxylase (TH) and dopamine-β-hydroxylase (DβH) immunoreactivity (-IR) or dopaminergic (i.e., TH- but not DβH-IR). Our aims were to investigate whether a subpopulation of neurons in the A2 area was dopaminergic and, if so, to investigate the effects of dopamine (DA) on the membrane of gastric-projecting vagal motoneurons. We observed that although the majority of A2 neurons were both TH- and DβH-IR, a small percentage of nucleus tractus solitarius neurons were TH-IR only, suggesting that DA itself may play role in these circuits. Whole cell recordings from thin brain stem slices showed that 71% of identified gastric-projecting motoneurons responded to DA (1–300 µM) with either an excitation (28%) or an inhibition (43%) of the membrane; the remaining 29% of the neurons were unresponsive. The DA-induced depolarization was mimicked by SK 38393 and prevented by pretreatment with SCH 23390. Conversely, the DA-induced inhibition was mimicked by bromoergocryptine and prevented by pretreatment with L741626. When tested on the same neuron, the effects of DA and NE were not always similar. In fact, in neurons in which DA induced a membrane depolarization, 77% were inhibited by NE, whereas 75% of neurons unresponsive to DA were inhibited by NE. Our data suggest that DA modulates the membrane properties of gastric-projecting motoneurons via D1- and D2-like receptors, and DA may play different roles than norepinephrine in brain stem vagal circuits. PMID:17170022

  12. Adaptations to long-term strength training of ankle joint muscles in old age.

    PubMed

    Simoneau, Emilie; Martin, Alain; Van Hoecke, Jacques

    2007-07-01

    The aim of this study was to enquire whether older adults, who continue plantar-flexion (PF) strength training for an additional 6-month period, would achieve further improvements in neuromuscular performance, in the ankle PFs, and in the antagonist dorsi-flexors (DFs). Twenty-three healthy older volunteers (mean age 77.4 +/- 3.7 years) took part in this investigation and 12 of them followed a 1-year strength-training program. Both neural and muscular factors were examined during isometric maximal voluntary contraction (MVC) torques in ankle PF and DF pre-training, post 6 and post 12 months. The main finding was that 6 months of additional strength training of the PFs, beyond 6 months, allowed further improvements in neuromuscular performance at the ankle joint in older adults. Indeed, during the first 6 months of progressive resistance training, there was an increase in the PF MVC torque of 11.1 +/- 19.9 N m, and then of 11.1 +/- 17.9 N m in the last 6-month period. However, it was only after 1 year that there was an improvement in the evoked contraction at rest in PF (+ 8%). The strength training of the agonist PF muscles appeared to have an impact on the maximal resultant torque in DF. However, it appeared that this gain was first due to modifications occurring in the trained PFs muscles, then, it seemed that the motor drive of the DFs per se was altered. In conclusion, long-term strength training of the PFs resulted in continued improvements in neuromuscular performance at the ankle joint in older adults, beyond the initial 6 months.

  13. Decompression of Posterior Ankle Impingement With Concomitant Anterior Ankle Pathology by Posterior Ankle Arthroscopy in the Supine Position.

    PubMed

    Lui, Tun Hing

    2016-10-01

    Posterior ankle endoscopy is a safe and effective approach for treatment of posterior ankle impingement. This is usually performed with the patient in prone position. The purpose of this technical note is to describe an arthroscopic approach of decompression of posterior ankle impingement with the patient in supine position. This is indicated if there is posterior ankle impingement together with other ankle pathology requiring anterior ankle arthroscopy. This approach allows treatment of both anterior ankle and posterior ankle pathology with the patient in the supine position. Concomitant anterior ankle arthroscopy can be performed with the usual orientation without the need of change of patient's position.

  14. Cat hindlimb motoneurons during locomotion. II. Normal activity patterns.

    PubMed

    Hoffer, J A; Sugano, N; Loeb, G E; Marks, W B; O'Donovan, M J; Pratt, C A

    1987-02-01

    Activity patterns were recorded from 51 motoneurons in the fifth lumbar ventral root of cats walking on a motorized treadmill at a range of speeds between 0.1 and 1.3 m/s. The muscle of destination of recorded motoneurons was identified by spike-triggered averaging of EMG recordings from each of the anterior thigh muscles. Forty-three motoneurons projected to one of the quadriceps (vastus medialis, vastus lateralis, vastus intermedius, or rectus femoris) or sartorius (anterior or medial) muscles of the anterior thigh. Anterior thigh motoneurons always discharged a single burst of action potentials per step cycle, even in multifunctional muscles (e.g., sartorius anterior) that exhibited more than one burst of EMG activity per step cycle. The instantaneous firing rates of most motoneurons were lowest upon recruitment and increased progressively during a burst, as long as the EMG was still increasing. Firing rates peaked midway through each burst and tended to decline toward the end of the burst. The initial, mean, and peak firing rates of single motoneurons typically increased for faster walking speeds. At any given walking speed, early recruited motoneurons typically reached higher firing rates than late recruited motoneurons. In contrast to decerebrated cats, initial doublets at the beginning of bursts were seen only rarely. In the 4/51 motoneurons that showed initial doublets, both the instantaneous frequency of the doublet and the probability of starting a burst with a doublet decreased for faster walking speeds. The modulations in firing rate of every motoneuron were found to be closely correlated to the smoothed electromyogram of its target muscle. For 32 identified motoneurons, the unit's instantaneous frequencygram was scaled linearly by computer to the rectified smoothed EMG recorded from each of the anterior thigh muscles. The covariance between unitary frequencygram and muscle EMG was computed for each muscle. Typically, the EMG profile of the target

  15. Nicotinic excitation of rat hypoglossal motoneurons.

    PubMed

    Chamberlin, N L; Bocchiaro, C M; Greene, R W; Feldman, J L

    2002-01-01

    Hypoglossal motoneurons (HMNs), which innervate the tongue muscles, are involved in several important physiological functions, including the maintenance of upper airway patency. The neural mechanisms that affect HMN excitability are therefore important determinants of effective breathing. Obstructive sleep apnea is a disorder characterized by recurrent collapse of the upper airway that is likely due to decline of pharyngeal motoneuron activity during sleep. Because cholinergic neuronal activity is closely coupled to wake and sleep states, we tested the effects and pharmacology of nicotinic acetylcholine receptor (nAChR) activation on HMNs. We made intracellular recordings from HMNs in medullary slices from neonatal rats and found that local application of the nicotinic agonist, 1,1-dimethyl-4-phenylpiperazinium iodide, excited HMNs by a Ca(2+)-sensitive, and TTX-insensitive inward current that was blocked by dihydro-beta-erythroidine (IC(50): 19+/-3 nM), methyllycaconitine (IC(50): 32+/-7 nM), and mecamylamine (IC(50): 88+/-11 nM), but not by alpha-bungarotoxin (10 nM). This is consistent with responses being mediated by postsynaptic nAChRs that do not contain the alpha7 subunit. These results suggest that nAChR activation may contribute to central maintenance of upper airway patency and that the decline in firing rate of cholinergic neurons during sleep could potentially disfacilitate airway dilator muscle activity, contributing to airway obstruction.

  16. Kinesio-Taping Application and Corticospinal Excitability at the Ankle Joint

    PubMed Central

    Tremblay, Francois; Karam, Siobhan

    2015-01-01

    Context Physiotherapists and athletic trainers often use Kinesio Taping (KT) to prevent and treat musculoskeletal injuries in athletes, yet evidence about its effects on neuromuscular performance is conflicting. Objective To investigate the influence of a KT application directed at the ankle joint on measures of corticospinal excitability with transcranial magnetic stimulation. Design Controlled laboratory study. Setting Research laboratory. Patients or Other Participants Twelve healthy young women (age = 23.1 ± 1.9 years; range, 19–26 years). Intervention(s) Participants were tested under no-tape and KT conditions according to a random sequence order. The KT was applied to the skin overlying the dorsiflexor and plantar-flexor muscles of the ankle. Main Outcome Measure(s) We assessed changes in the amplitude of motor-evoked potentials elicited at rest and during movement and changes in the silent period and background muscle activity during movement. Results Taping conditions had no effect on motor-evoked potential amplitude at rest or during movement or on the silent-period duration and background muscle activity. Conclusions Our results concur with other recent reports, showing KT applications have little influence at the neuromuscular level. Alterations in sensory feedback ascribed to elastic taping are likely insufficient to modulate corticospinal excitability in a functionally meaningful manner. PMID:26090708

  17. Arthroscopic Capsular Release of the Ankle Joint.

    PubMed

    Lui, Tun Hing

    2016-12-01

    Adhesive capsulitis of the ankle is also known as frozen ankle and results in marked fibrosis and contracture of the ankle capsule. Arthroscopic capsular release is indicated for symptomatic frozen ankle that is resistant to conservative treatment. It is contraindicated for ankle stiffness due to degenerative joint disease, intra-articular malunion, or adhesion of the extensors of the ankle. The procedure consists of endoscopic posterior ankle capsulectomy and arthroscopic anterior ankle capsulotomy. It has the advantages of being minimally invasive surgery and allowing early postoperative vigorous mobilization of the ankle joint.

  18. US in ankle impingement syndrome.

    PubMed

    Pesquer, Lionel; Guillo, Stephane; Meyer, Philippe; Hauger, Olivier

    2014-06-01

    Ankle impingement is a common condition occurring secondary to sprain or repeated microtrauma. Clinical symptoms are chronic pain located in the affected region and limited range of ankle motion. There are three types of ankle impingement syndrome: anterior impingement, which can be subdivided into anterolateral, anteromedial and purely anterior impingement; posterior impingement, which can be subdivided into posterior and posteromedial impingement; and calcaneal peroneal impingement which is secondary to planovalgus foot deformity. This paper evaluates physiological and clinical elements of these three types of ankle impingement syndrome as well as the role of ultrasound (US) imaging and US-guided treatment.

  19. What Is a Foot and Ankle Surgeon?

    MedlinePlus

    ... foot and ankle surgeons. All Fellows of the College are board certified by the American Board of Foot and Ankle Surgery. Copyright © 2017 American College of Foot and Ankle Surgeons (ACFAS), All Rights ...

  20. Osteoarthritis of the Foot and Ankle

    MedlinePlus

    ... foot and ankle surgeons. All Fellows of the College are board certified by the American Board of Foot and Ankle Surgery. Copyright © 2017 American College of Foot and Ankle Surgeons (ACFAS), All Rights ...

  1. Sports Injuries to the Foot and Ankle

    MedlinePlus

    ... foot and ankle surgeons. All Fellows of the College are board certified by the American Board of Foot and Ankle Surgery. Copyright © 2017 American College of Foot and Ankle Surgeons (ACFAS), All Rights ...

  2. Type C botulinum toxin causes degeneration of motoneurons in vivo.

    PubMed

    Zhao, Li-Chun; Yang, Bo; Wang, Rengang; Lipton, Stuart A; Zhang, Dongxian

    2010-01-06

    All botulinum toxins (BoNTs, types A-G) inhibit synaptic transmitter release from motoneurons, and thus result in respiratory arrest and death. Rapid treatment with anti-BoNT antibodies can prevent progression, but recovery still requires weeks on a ventilator. Even after recovery, there is a potential for persistent fatigue in some cases of botulism even years after the insult, possibly because of motoneuron dropout for previously unknown reasons. Unique among BoNTs, the C-type (BoNT/C) cleaves two proteins involved in neurotransmitter release, syntaxin and SNAP-25, and induces apoptotic cell death in cultured cerebellar neurons. It is not clear, however, whether BoNT/C also affects neurons that encounter toxin in vivo, namely motoneurons. Here, we provide experimental evidence that BoNT/C causes a slow degeneration of motoneurons both in vitro and in vivo. This novel form of BoNT/C-induced cell death may require new treatment strategies.

  3. Myosin phosphatase Fine-tunes Zebrafish Motoneuron Position during Axonogenesis

    PubMed Central

    Granato, Michael

    2016-01-01

    During embryogenesis the spinal cord shifts position along the anterior-posterior axis relative to adjacent tissues. How motor neurons whose cell bodies are located in the spinal cord while their axons reside in adjacent tissues compensate for such tissue shift is not well understood. Using live cell imaging in zebrafish, we show that as motor axons exit from the spinal cord and extend through extracellular matrix produced by adjacent notochord cells, these cells shift several cell diameters caudally. Despite this pronounced shift, individual motoneuron cell bodies stay aligned with their extending axons. We find that this alignment requires myosin phosphatase activity within motoneurons, and that mutations in the myosin phosphatase subunit mypt1 increase myosin phosphorylation causing a displacement between motoneuron cell bodies and their axons. Thus, we demonstrate that spinal motoneurons fine-tune their position during axonogenesis and we identify the myosin II regulatory network as a key regulator. PMID:27855159

  4. Androgen regulation of axon growth and neurite extension in motoneurons

    PubMed Central

    Fargo, Keith N.; Galbiati, Mariarita; Foecking, Eileen M.; Poletti, Angelo; Jones, Kathryn J.

    2008-01-01

    Androgens act on the CNS to affect motor function through interaction with a widespread distribution of intracellular androgen receptors (AR). This review highlights our work on androgens and process outgrowth in motoneurons, both in vitro and in vivo. The actions of androgens on motoneurons involve the generation of novel neuronal interactions that are mediated by the induction of androgen-dependent neurite or axonal outgrowth. Here, we summarize the experimental evidence for the androgenic regulation of the extension and regeneration of motoneuron neurites in vitro using cultured immortalized motoneurons, and axons in vivo using the hamster facial nerve crush paradigm. We place particular emphasis on the relevance of these effects to SBMA and peripheral nerve injuries. PMID:18387610

  5. Saccular and utricular inputs to sternocleidomastoid motoneurons of decerebrate cats.

    PubMed

    Kushiro, K; Zakir, M; Ogawa, Y; Sato, H; Uchino, Y

    1999-06-01

    Connections from the otolithic organs to sternocleidomastoid (SCM) motoneurons were studied in 20 decerebrate cats. The electrical stimulation was selective for the saccular or the utricular nerves. Postsynaptic potentials were recorded from antidromically identified SCM motoneurons; these muscles participate mainly in neck rotation and flexion. Partial transections of the brainstem at the level of the obex were performed to identify the possible pathway from the otolithic organs to the SCM motoneurons. Saccular or utricular nerve stimulation mainly evoked inhibitory postsynaptic potentials (IPSPs) in the ipsilateral SCM motoneurons. Some of the sacculus-induced IPSPs were preceded by small-amplitude excitatory PSPs (EPSPs). The latencies of the PSPs ranged from 1.8 to 3.1 ms after saccular nerve stimulation and from 1.7 to 2.8 ms after utricular nerve stimulation, indicating that most of the ipsilateral connections were disynaptic. In the contralateral SCM motoneurons, saccular nerve stimulation had no or faint effects, whereas utricular nerve stimulation evoked EPSPs in about two-thirds of neurons, and no visible PSPs in about one-third of neurons. The latencies of the EPSPs ranged from 1.5 to 2.0 ms, indicating the disynaptic connection. Thus, the results suggest a difference between the two otolithic innervating patterns of SCM motoneurons. After transection of the medial vestibulospinal tract (MVST), saccular nerve stimulation did not evoke IPSPs at all in ipsilateral SCM motoneurons, but some (11/40) neurons showed small-amplitude EPSPs. Most (24/33) of the utricular-activated IPSPs disappeared after transection, whereas the other 9 neurons still indicated IPSPs. In the contralateral SCM motoneurons, no utricular-activated EPSPs were recorded after transection. These MVST transection results suggest that most of the otolith-SCM pathways are located in the MVST at the obex level. However, the results also suggest the possibility that other otolith-SCM pathways

  6. Discharge patterns of hindlimb motoneurons during normal cat locomotion.

    PubMed

    Hoffer, J A; O'Donovan, M J; Pratt, C A; Loeb, G E

    1981-07-24

    Long-term recording from single lumbar motoneurons of intact cats revealed activation patterns fundamentally different from those seen in decerebrate preparations. In intact cats, motoneuron bursts showed marked rate modulation without initial doublets. Each unit's frequencygram generally resembled the envelope of the gross electromyogram simultaneously recorded from the corresponding muscle. Average and peak discharge rates increased for faster gaits. These findings suggest that, in cat locomotion, rate modulation is a more important contributor to force regulation than was previously thought.

  7. Distribution of vestibulospinal synaptic input to cat triceps surae motoneurons.

    PubMed

    Westcott, S L; Powers, R K; Robinson, F R; Binder, M D

    1995-01-01

    We applied supramaximal, repetitive stimulation to the lateral vestibular nucleus (Deiters' nucleus, DN) at 200 Hz to evoke stead-state synaptic potentials in ipsilateral triceps surae motoneurons of the cat. The effective synaptic currents underlying these potentials were measured using a modified voltage-clamp technique. The steady-state effective synaptic currents evoked by activating DN were generally small and depolarizing (mean 2.5 +/- 2.6 nA). DN stimulation generated hyperpolarizing synaptic currents in 2 of the 34 triceps motoneurons studied. The effective synaptic currents from DN tended to be larger in putative type F motoneurons than in putative type S cells (type F mean 3.0 +/- 3.1 nA; type S mean 1.8 +/- 1.0 nA). There was a statistically significant difference between the inputs to putative type FF and putative type S motoneurons (mean difference 2.8 nA, t = 2.87, P < 0.01). The synaptic input from DN to medial gastrocnemius motoneurons had approximately the same amplitude as that from homonymous Ia afferent fibers. However, the distribution of DN input with respect to putative motor unit type was the opposite of that previously reported for Ia afferent input. Thus, the synaptic input from DN might act to compress the range of recruitment thresholds within the motoneuron pool and thereby increase the gain of its input-output function.

  8. The effect of the ankle joint angle in the level of soleus Ia afferent presynaptic inhibition.

    PubMed

    Patikas, D A; Kotzamanidis, C; Robertson, C T; Koceja, D M

    2004-12-01

    The factors that are responsible for the relationship between motoneuron excitability and muscle length may have both mechanical and/or neurophysiologic origins. The aim of the study was to investigate the changes in the level of presynaptic inhibition, as measured with a soleus H-reflex conditioning protocol, and muscle length. Ten healthy volunteers were measured at three different ankle angles: 30 degrees plantar flexion, neutral position (0 degrees) and 15 degrees dorsiflexion. At each position the soleus H-reflex and the maximum M-wave were measured while the limb was relaxed. The H-reflex was conditioned by a stimulation of the common peroneal nerve, 100 ms prior to the tibial nerve stimulation. The results revealed that the level of presynaptic inhibition was higher at the neutral position in comparison to the dorsiflexed or plantarflexed positions. Additionally, the HMAX/MMAX ratio was significantly decreased when the joint position was set at dorsiflexion. Further, there was a significant correlation, independent of ankle joint angle, between presynaptic inhibition levels and the HMAX/MMAX ratio. The above findings support the concept that peripheral feedback from passive, static modifications in the joint angle and consequently in muscle length, can modify the input/output threshold of the motoneurons on a presynaptic level.

  9. Developing electrical properties of postnatal mouse lumbar motoneurons

    PubMed Central

    Durand, Jacques; Filipchuk, Anton; Pambo-Pambo, Arnaud; Amendola, Julien; Borisovna Kulagina, Iryna; Guéritaud, Jean-Patrick

    2015-01-01

    We studied the rapid changes in electrical properties of lumbar motoneurons between postnatal days 3 and 9 just before mice weight-bear and walk. The input conductance and rheobase significantly increased up to P8. A negative correlation exists between the input resistance (Rin) and rheobase. Both parameters are significantly correlated with the total dendritic surface area of motoneurons, the largest motoneurons having the lowest Rin and the highest rheobase. We classified the motoneurons into three groups according to their discharge firing patterns during current pulse injection (transient, delayed onset, sustained). The delayed onset firing type has the highest rheobase and the fastest action potential (AP) whereas the transient firing group has the lowest rheobase and the less mature AP. We found 32 and 10% of motoneurons with a transient firing at P3–P5 and P8, respectively. About 20% of motoneurons with delayed onset firing were detected at P8. At P9, all motoneurons exhibit a sustained firing. We defined five groups of motoneurons according to their discharge firing patterns in response to ascending and descending current ramps. In addition to the four classical types, we defined a fifth type called transient for the quasi-absence of discharge during the descending phase of the ramp. This transient type represents about 40% between P3–P5 and tends to disappear with age. Types 1 and 2 (linear and clockwise hysteresis) are the most preponderant at P6–P7. Types 3 and 4 (prolonged sustained and counter clockwise hysteresis) emerge at P8–P9. The emergence of types 3 and 4 probably depends on the maturation of L type calcium channels in the dendrites of motoneurons. No correlation was found between groups defined by step or triangular ramp of currents with the exception of transient firing patterns. Our data support the idea that a switch in the electrical properties of lumbar motoneurons might exist in the second postnatal week of life in mice. PMID

  10. Reverse Evans peroneus brevis medial ankle stabilization for balancing valgus ankle contracture during total ankle replacement.

    PubMed

    Roukis, Thomas S; Prissel, Mark A

    2014-01-01

    Medial ankle instability secondary to deltoid ligament insufficiency is frequently encountered when performing total ankle replacement and remains a challenge. In the present techniques report, we describe a "reverse" Evans peroneus brevis tendon nonanatomic deltoid ligament reconstruction for medial ankle stabilization harvested through limited incisions using simple topographic anatomic landmarks. The harvested peroneus brevis tendon is brought through a drill hole in the talus from laterally to medially, aiming for the junction of the talar neck and body plantar to the midline. The tendon is the brought superiorly and obliquely to the anterior medial aspect of the distal tibia where it is secured under a plate and screw construct. This modified Evans peroneus brevis tendon nonanatomic deltoid ligament reconstruction is useful in providing medial ankle stability during or after primary and revision total ankle replacement.

  11. Behaviour of the motoneurone pool in a fatiguing submaximal contraction.

    PubMed

    McNeil, Chris J; Giesebrecht, Sabine; Gandevia, Simon C; Taylor, Janet L

    2011-07-15

    During fatigue caused by a sustained maximal voluntary contraction (MVC), motoneurones become markedly less responsive when tested during the silent period following transcranial magnetic stimulation (TMS). To determine whether this reduction depends on the repetitive activation of the motoneurones, responses to TMS (motor evoked potentials, MEPs) and to cervicomedullary stimulation (cervicomedullary motor evoked potentials, CMEPs) were tested during a sustained submaximal contraction at a constant level of electromyographic activity (EMG). In such a contraction, some motoneurones are repetitively activated whereas others are not active. On four visits, eight subjects performed a 10 min maintained-EMG elbow flexor contraction of 25% maximum. Test stimuli were delivered with and without conditioning by TMS given 100 ms prior. Test responses were MEPs or CMEPs (two visits each, small responses evoked by weak stimuli on one visit and large responses on the other). During the sustained contraction, unconditioned CMEPs decreased ∼20% whereas conditioned CMEPs decreased ∼75 and 30% with weak and strong stimuli, respectively. Conditioned MEPs were reduced to the same extent as CMEPs of the same size. The data reveal a novel decrease in motoneurone excitability during a submaximal contraction if EMG is maintained. Further, the much greater reduction of conditioned than unconditioned CMEPs shows the critical influence of voluntary drive on motoneurone responsiveness. Strong test stimuli attenuate the reduction of conditioned CMEPs which indicates that low-threshold motoneurones active in the contraction are most affected. The equivalent reduction of conditioned MEPs and CMEPs suggests that, similar to findings with a sustained MVC, impaired motoneurone responsiveness rather than intracortical inhibition is responsible for the fatigue-related impairment of the MEP during a sustained submaximal contraction.

  12. Cat hindlimb motoneurons during locomotion. III. Functional segregation in sartorius.

    PubMed

    Hoffer, J A; Loeb, G E; Sugano, N; Marks, W B; O'Donovan, M J; Pratt, C A

    1987-02-01

    Cat sartorius has two distinct anatomical portions, anterior (SA-a) and medial (SA-m). SA-a acts to extend the knee and also to flex the hip. SA-m acts to flex both the knee and the hip. The objective of this study was to investigate how a "single motoneuron pool" is used to control at least three separate functions mediated by the two anatomical portions of one muscle. Discharge patterns of single motoneurons projecting to the sartorius muscle were recorded using floating microelectrodes implanted in the L5 ventral root of cats. The electromyographic activity generated by the anterior and medial portions of sartorius was recorded with chronically implanted electrodes. The muscle portion innervated by each motoneuron was determined by spike-triggered averaging of the EMGs during walking on a motorized treadmill. During normal locomotion, SA-a exhibited two bursts of EMG activity per step cycle, one during the stance phase and one during the late swing phase. In contrast, every recorded motoneuron projecting to SA-a discharged a single burst of action potentials per step cycle. Some SA-a motoneurons discharged only during the stance phase, whereas other motoneurons discharged only during the late swing phase. In all cases, the instantaneous frequencygram of the motoneuron was well fit by the rectified smoothed EMG envelope generated by SA-a during the appropriate phase of the step cycle. During normal locomotion, SA-m exhibited a single burst of EMG activity per step cycle, during the swing phase. The temporal characteristics of the EMG bursts recorded from SA-m differed from the swing-phase EMG bursts generated by SA-a.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. Can Chronic Ankle Instability be Prevented? Rethinking Management of Lateral Ankle Sprains.

    ERIC Educational Resources Information Center

    Denegar, Craig R.; Miller, Sayers J., III

    2002-01-01

    Investigates whether chronic ankle instability can be prevented, discussing: the relationship between mechanical and functional instability; normal ankle mechanics, sequelae to lateral ankle sprains, and abnormal ankle mechanics; and tissue healing, joint dysfunction, and acute lateral ankle sprain management. The paper describes a treatment model…

  14. [Ankle brachial index measurement].

    PubMed

    Rucigaj, Tanja Planinsek

    2014-10-01

    Ultrasound examinations are noninvasive diagnostic methods which, along with appropriate history and clinical examination, provide basic information on the etiology and spread of the disease, as well as on treatment options required in patients with chronic venous insufficiency and arterial flow impairment. Doppler flow meter offers useful data on venous blood return, primarily in great veins, while both deep and superficial veins as well as arteries can be visualized and data on venous and arterial hemodynamics obtained by duplex ultrasonography. In addition, Doppler flow meter provides data on the peripheral arterial system action through ankle brachial index measurement, which will guide the choice of compression therapy when deciding on the treatment of peripheral arterial disease and mixed arteriovenous leg ulcers. However, diagnosis of arterial insufficiency requires additional examinations.

  15. GABA and glycine actions on spinal motoneurons.

    PubMed

    Krnjević, K; Puil, E; Werman, R

    1977-06-01

    Applied microiontophoretically in the spinal cord of cats, glycine is consistently more powerful than gamma-aminobutyric acid (GABA) in raising the membrane conductance of lumbosacral motoneurons (mean ratio of equipotent iontophoretic currents tested on same cells is 5.6:1). This is the reverse of the situation in cerebral cortex. The effect of glycine is well maintained during applications lasting about 1 min, but that of GABA, after an early peak, drops to a much lower plateau (mean plateau-over-peak ratio is 0.23). The reversal potentials for the action of GABA and glycine are initially similar but they behave differently during a prolonged application; that for glycine usually remains constant or becomes more negative whereas that for GABA tends to shift in the positive direction. Various explanations of these phenomena are considered. It is suggested that a single process, electrogenic uptake of GABA, may account for both desensitization (by removing GABA from its site of action) and the positive shift in GABA reversal potential (became uptake is probably associated with an influx of Na+).

  16. Side-Alternating Vibration Training for Balance and Ankle Muscle Strength in Untrained Women

    PubMed Central

    Spiliopoulou, Styliani I.; Amiridis, Ioannis G.; Tsigganos, Georgios; Hatzitaki, Vassilia

    2013-01-01

    Context: Side-alternating vibration (SAV) may help reduce the risk of falling by improving body balance control. Such training has been promoted as a strength-training intervention because it can increase muscle activation through an augmented excitatory input from the muscle spindles. Objective: To determine the effect of SAV training on static balance during 3 postural tasks of increasing difficulty and lower limb strength. Design: Randomized controlled clinical trial. Setting: Laboratory. Patients or Other Participants: A total of 21 healthy women were divided into training (n = 11; age = 43.35 ± 4.12 years, height = 169 ± 6.60 cm, mass = 68.33 ± 11.90 kg) and control (n = 10; age = 42.31 ± 3.73 years, height = 167 ± 4.32 cm, mass = 66.29 ± 10.74 kg) groups. Intervention(s): The training group completed a 9-week program during which participants performed 3 sessions per week of ten 15-second isometric contractions with a 30-second active rest of 3 exercises (half-squat, wide-stance squat, 1-legged half-squat) on an SAV plate (acceleration = 0.91–16.3g). The control group did not participate in any form of exercise over the 9-week period. Main Outcome Measure(s): We evaluated isokinetic and isometric strength of the knee extensors and flexors and ankle plantar flexors, dorsiflexors, and evertors. Static balance was assessed using 3 tasks of increasing difficulty (quiet bipedal stance, tandem stance, 1-legged stance). The electromyographic activity of the vastus lateralis, semitendinosus, medial gastrocnemius, tibialis anterior, and peroneus longus was recorded during postural task performance, baseline and pretraining, immediately posttraining, and 15 days posttraining. Results: After training in the training group, ankle muscle strength improved (P = .03), whereas knee muscle strength remained unaltered (P = .13). Improved ankle-evertor strength was observed at all angular velocities (P = .001). Postural sway decreased in both directions but was greater

  17. Osteoligamentous injuries of the medial ankle joint.

    PubMed

    Lötscher, P; Lang, T H; Zwicky, L; Hintermann, B; Knupp, M

    2015-12-01

    Injuries of the ankle joint have a high incidence in daily life and sports, thus, playing an important socioeconomic role. Therefore, proper diagnosis and adequate treatment are mandatory. While most of the ligament injuries around the ankle joint are treated conservatively, great controversy exists on how to treat deltoid ligament injuries in ankle fractures. Missed injuries and inadequate treatment of the medial ankle lead to inferior outcome with instability, progressive deformity, and ankle joint osteoarthritis.

  18. Characterization of the AMPA-activated receptors present on motoneurons.

    PubMed

    Greig, A; Donevan, S D; Mujtaba, T J; Parks, T N; Rao, M S

    2000-01-01

    Motoneurons have been shown to be particularly sensitive to Ca2+-dependent glutamate excitotoxicity, mediated via AMPA receptors (AMPARs). To determine the molecular basis for this susceptibility we have used immunocytochemistry, RT-PCR, and electrophysiology to profile AMPARs on embryonic day 14.5 rat motoneurons. Motoneurons show detectable AMPAR-mediated calcium permeability in vitro and in vivo as determined by cobalt uptake and electrophysiology. Motoneurons express all four AMPAR subunit mRNAs, with glutamate receptor (GluR) 2 being the most abundant (63.9+/-4.8%). GluR2 is present almost exclusively in the edited form, and electrophysiology confirms that most AMPARs present are calcium-impermeant. However, the kainate current in motoneurons was blocked an average of 32.0% by Joro spider toxin, indicating that a subset of the AM PARs is Ca2+-permeable. Therefore, heterogeneity of AMPARs, rather than the absence of GluR2 or the presence of unedited GluR2, explains AMPAR-mediated Ca2+ permeability. The relative levels of flip/flop isoforms of each subunit were also examined by semiquantitative PCR. Both isoforms were present, but the relative proportion varied for each subunit, and the flip isoform predominated. Thus, our data show that despite high levels of edited GluR2 mRNA, some AMPARs are Ca2+-permeable, and this subset of AMPARs can account for the AMPAR-mediated Ca2+ inflow inferred from cobalt uptake and electrophysiology studies.

  19. Intrinsic excitability differs between murine hypoglossal and spinal motoneurons.

    PubMed

    Tadros, M A; Fuglevand, A J; Brichta, A M; Callister, R J

    2016-05-01

    Motoneurons differ in the behaviors they control and their vulnerability to disease and aging. For example, brain stem motoneurons such as hypoglossal motoneurons (HMs) are involved in licking, suckling, swallowing, respiration, and vocalization. In contrast, spinal motoneurons (SMs) innervating the limbs are involved in postural and locomotor tasks requiring higher loads and lower movement velocities. Surprisingly, the properties of these two motoneuron pools have not been directly compared, even though studies on HMs predominate in the literature compared with SMs, especially for adult animals. Here we used whole cell patch-clamp recording to compare the electrophysiological properties of HMs and SMs in age-matched neonatal mice (P7-P10). Passive membrane properties were remarkably similar in HMs and SMs, and afterhyperpolarization properties did not differ markedly between the two populations. HMs had narrower action potentials (APs) and a faster upstroke on their APs compared with SMs. Furthermore, HMs discharged APs at higher frequencies in response to both step and ramp current injection than SMs. Therefore, while HMs and SMs have similar passive properties, they differ in their response to similar levels of depolarizing current. This suggests that each population possesses differing suites of ion channels that allow them to discharge at rates matched to the different mechanical properties of the muscle fibers that drive their distinct motor functions.

  20. Foot and Ankle Conditioning Program

    MedlinePlus

    ... and ankle pain and prevent further injury. Flexibility: Stretching the muscles that you strengthen is important for restoring range of motion and preventing injury. Gently stretching after strengthening exercises can help reduce muscle soreness ...

  1. Foot, leg, and ankle swelling

    MedlinePlus

    ... feet - legs; Ankle swelling; Foot swelling; Leg swelling; Edema - peripheral; Peripheral edema ... 51. Trayes KP, Studdiford JS, Pickle S, Tully AS. Edema: Diagnosis and management. Am Fam Phys . 2013;88( ...

  2. Co-expression of GAP-43 and nNOS in avulsed motoneurons and their potential role for motoneuron regeneration.

    PubMed

    Yuan, Qiuju; Hu, Bing; Chu, Tak-Ho; Su, Huanxing; Zhang, Wenming; So, Kwok-Fai; Lin, Zhixiu; Wu, Wutian

    2010-12-15

    Neuronal nitric oxide synthase (nNOS) is induced after axonal injury. The role of induced nNOS in injured neurons is not well established. In the present study, we investigated the co-expression of nNOS with GAP-43 in spinal motoneurons following axonal injury. The role of induced nNOS was discussed and evaluated. In normal rats, spinal motoneurons do not express nNOS or GAP-43. Following spinal root avulsion, expression of nNOS and GAP-43 were induced and colocalized in avulsed motoneurons. Reimplantation of avulsed roots resulted in a remarkable decrease of GAP-43- and nNOS-IR in the soma of the injured motoneurons. A number of GAP-43-IR regenerating motor axons were found in the reimplanted nerve. In contrast, the nNOS-IR was absent in reimplanted nerve. These results suggest that expression of GAP-43 in avulsed motoneurons is related to axonal regeneration whereas nNOS is not.

  3. Cramps: a sign of motoneurone 'bistability' in a human patient.

    PubMed

    Baldissera, F; Cavallari, P; Dworzak, F

    1991-12-09

    In a patient suffering from severe long-lasting cramps, cramps were triggered in the triceps surae by volleys in homonymous Ia afferents (elicited by electrical stimulation or by tendon taps) and were interrupted by antidromic invasion and Renshaw inhibition of triceps surae motoneurones (evoked by a single maximal stimulation of motor axons). This result suggests that the mechanisms which generate the cramps are intrinsic to alpha-motoneurone somata. A similar on-off switching of a self-sustained motor discharge has been observed in the decerebrate cat and recognized to depend on 'bistability' of the motoneuronal membrane. We propose that the same mechanism may be at the origin of the cramp discharge.

  4. Motoneuron differentiation of immortalized human spinal cord cell lines.

    PubMed

    Li, R; Thode, S; Zhou, J; Richard, N; Pardinas, J; Rao, M S; Sah, D W

    2000-02-01

    Human motoneuron cell lines will be valuable tools for spinal cord research and drug discovery. To create such cell lines, we immortalized NCAM(+)/neurofilament(+) precursors from human embryonic spinal cord with a tetracycline repressible v-myc oncogene. Clonal NCAM(+)/neurofilament(+) cell lines differentiated exclusively into neurons within 1 week. These neurons displayed extensive processes, exhibited immunoreactivity for mature neuron-specific markers such as tau and synaptophysin, and fired action potentials upon current injection. Moreover, a clonal precursor cell line gave rise to multiple types of spinal cord neurons, including ChAT(+)/Lhx3(+)/Lhx4(+) motoneurons and GABA(+) interneurons. These neuronal restricted precursor cell lines will expedite the elucidation of molecular mechanisms that regulate the differentiation, maturation and survival of specific subsets of spinal cord neurons, and the identification and validation of novel drug targets for motoneuron diseases and spinal cord injury.

  5. Effects of ankle balance taping with kinesiology tape for a patient with chronic ankle instability.

    PubMed

    Kim, Byeong-Jo; Lee, Jung-Hoon; Kim, Chang-Tae; Lee, Sun-Min

    2015-07-01

    [Purpose] To report the effects of ankle balance taping for a patient with chronic ankle instability (CAI). [Subject] A 33-year-old man with a 10 year history of chronic ankle stability. [Methods] ABT with kinesiology tape was performed for 2 months (average, 16 h/day) around the right ankle. [Results] At the end of two months, no ankle instability was noted when ascending and descending the stairs, jumping, turning, operating the pedals while driving, and lifting heavy objects. [Conclusion] The repeated use of kinesiology tape in ankle balance taping may be an effective treatment for recovering the ankle stability of patients with chronic ankle instability.

  6. Effects of ankle balance taping with kinesiology tape for a patient with chronic ankle instability

    PubMed Central

    Kim, Byeong-Jo; Lee, Jung-Hoon; Kim, Chang-Tae; Lee, Sun-Min

    2015-01-01

    [Purpose] To report the effects of ankle balance taping for a patient with chronic ankle instability (CAI). [Subject] A 33-year-old man with a 10 year history of chronic ankle stability. [Methods] ABT with kinesiology tape was performed for 2 months (average, 16 h/day) around the right ankle. [Results] At the end of two months, no ankle instability was noted when ascending and descending the stairs, jumping, turning, operating the pedals while driving, and lifting heavy objects. [Conclusion] The repeated use of kinesiology tape in ankle balance taping may be an effective treatment for recovering the ankle stability of patients with chronic ankle instability. PMID:26311206

  7. Electrical stimulation of transplanted motoneurons improves motor unit formation.

    PubMed

    Liu, Yang; Grumbles, Robert M; Thomas, Christine K

    2014-08-01

    Motoneurons die following spinal cord trauma and with neurological disease. Intact axons reinnervate nearby muscle fibers to compensate for the death of motoneurons, but when an entire motoneuron pool dies, there is complete denervation. To reduce denervation atrophy, we have reinnervated muscles in Fisher rats from local transplants of embryonic motoneurons in peripheral nerve. Since growth of axons from embryonic neurons is activity dependent, our aim was to test whether brief electrical stimulation of the neurons immediately after transplantation altered motor unit numbers and muscle properties 10 wk later. All surgical procedures and recordings were done in anesthetized animals. The muscle consequences of motoneuron death were mimicked by unilateral sciatic nerve section. One week later, 200,000 embryonic day 14 and 15 ventral spinal cord cells, purified for motoneurons, were injected into the tibial nerve 10-15 mm from the gastrocnemii muscles as the only neuron source for muscle reinnervation. The cells were stimulated immediately after transplantation for up to 1 h using protocols designed to examine differential effects due to pulse number, stimulation frequency, pattern, and duration. Electrical stimulation that included short rests and lasted for 1 h resulted in higher motor unit counts. Muscles with higher motor unit counts had more reinnervated fibers and were stronger. Denervated muscles had to be stimulated directly to evoke contractions. These results show that brief electrical stimulation of embryonic neurons, in vivo, has long-term effects on motor unit formation and muscle force. This muscle reinnervation provides the opportunity to use patterned electrical stimulation to produce functional movements.

  8. Electrical stimulation of transplanted motoneurons improves motor unit formation

    PubMed Central

    Liu, Yang; Grumbles, Robert M.

    2014-01-01

    Motoneurons die following spinal cord trauma and with neurological disease. Intact axons reinnervate nearby muscle fibers to compensate for the death of motoneurons, but when an entire motoneuron pool dies, there is complete denervation. To reduce denervation atrophy, we have reinnervated muscles in Fisher rats from local transplants of embryonic motoneurons in peripheral nerve. Since growth of axons from embryonic neurons is activity dependent, our aim was to test whether brief electrical stimulation of the neurons immediately after transplantation altered motor unit numbers and muscle properties 10 wk later. All surgical procedures and recordings were done in anesthetized animals. The muscle consequences of motoneuron death were mimicked by unilateral sciatic nerve section. One week later, 200,000 embryonic day 14 and 15 ventral spinal cord cells, purified for motoneurons, were injected into the tibial nerve 10–15 mm from the gastrocnemii muscles as the only neuron source for muscle reinnervation. The cells were stimulated immediately after transplantation for up to 1 h using protocols designed to examine differential effects due to pulse number, stimulation frequency, pattern, and duration. Electrical stimulation that included short rests and lasted for 1 h resulted in higher motor unit counts. Muscles with higher motor unit counts had more reinnervated fibers and were stronger. Denervated muscles had to be stimulated directly to evoke contractions. These results show that brief electrical stimulation of embryonic neurons, in vivo, has long-term effects on motor unit formation and muscle force. This muscle reinnervation provides the opportunity to use patterned electrical stimulation to produce functional movements. PMID:24848463

  9. Total ankle replacement. Design evolution and results.

    PubMed

    van den Heuvel, Alexander; Van Bouwel, Saskia; Dereymaeker, Greta

    2010-04-01

    The ankle joint has unique anatomical, biomechanical and cartilaginous structural characteristics that allow the joint to withstand the very high mechanical stresses and strains over years. Any minor changes to any of these features predispose the joint to osteoarthritis. Total ankle replacement (TAR) is evolving as an alternative to ankle arthrodesis for the treatment of end-stage ankle osteoarthritis. Initial implant designs from the early 1970s had unacceptably high failure and complication rates. As a result many orthopaedic surgeons have restricted the use of TAR in favour of ankle arthrodesis. Long term follow-up studies following ankle arthrodesis show risks of developing adjacent joint osteoarthritis. Therefore research towards a successful ankle replacement continues. Newer designs and longer-term outcome studies have renewed the interest in ankle joint replacement. We present an overview of the evolution, results and current concepts of total ankle replacement.

  10. The postnatal growth of motoneurons at three levels of the cat neuraxis.

    PubMed

    Cameron, W E; Fang, H; Brozanski, B S; Guthrie, R D

    1989-10-09

    The postnatal growth of motoneuron cell bodies located in the brainstem, cervical and lumbosacral spinal cord was investigated using retrograde transport of horseradish peroxidase in kittens ages 2, 12, 30, 55, 82 and 114 postnatal days and in an adult. The motoneurons innervating an extrinsic tongue muscle, the genioglossus, reached their adult size by eight weeks after birth. In contrast, the phrenic motoneurons innervating the diaphragm achieved adult size by 12 weeks and the motoneurons innervating the medial gastrocnemius muscle continued to grow beyond the twelfth postnatal week. The sizes of these motoneurons relative to one another remained constant during periods of development.

  11. Chronic ankle instability.

    PubMed

    Gerstner Garces, Juan Bernardo

    2012-09-01

    Chronic instability of the ankle and anterolateral impingement syndrome are abnormalities that present as a result of inversion and forced plantar-flexion traumas of the foot, despite strict conservative management in the ER and in rehabilitation. A conservative approach is always the first choice of treatment, including anti-inflammatory medications, rehabilitation and proprioception, infiltration with steroids in impingement cases, and use of orthotics, whose true effectiveness is the subject of multiple studies and much debate. Good to excellent results can be obtained surgically with a minimally invasive approach, such as the arthroscopic technique presented herein. Such an approach is useful in managing a combination of conditions such as anterolateral impingement, synovitis, and osteochondral lesions of the talus. The method is easily reproducible, its learning curve is rapid, and it has the advantage of not preventing the use other arthroscopic methods, or open anatomic or nonanatomic methods (tendon transfers), in the case of failure. No nerve lesion was recorded, probably owing to the use of the security zone, and neither was there any arthrofibrosis, possibly related to the use of nonsteroidal anti-inflammatory medications in the immediate postsurgical period coupled with aggressive rehabilitation from the fourth week. The success of the technique is due to multidisciplinary team work leading to the ultimate achievement of patient satisfaction. This technique is not indicated for patients with a high sports demand or for sport professionals, until further biomechanical studies on its use and success are completed.

  12. Mechanism and Design Analysis of Articulated Ankle Foot Orthoses for Drop-Foot

    PubMed Central

    Choudhury, Imtiaz Ahmed; Mamat, Azuddin Bin

    2014-01-01

    Robotic technologies are being employed increasingly in the treatment of lower limb disabilities. Individuals suffering from stroke and other neurological disorders often experience inadequate dorsiflexion during swing phase of the gait cycle due to dorsiflexor muscle weakness. This type of pathological gait, mostly known as drop-foot gait, has two major complications, foot-slap during loading response and toe-drag during swing. Ankle foot orthotic (AFO) devices are mostly prescribed to resolve these complications. Existing AFOs are designed with or without articulated joint with various motion control elements like springs, dampers, four-bar mechanism, series elastic actuator, and so forth. This paper examines various AFO designs for drop-foot, discusses the mechanism, and identifies limitations and remaining design challenges. Along with two commercially available AFOs some designs possess promising prospective to be used as daily-wear device. However, the design and mechanism of AFO must ensure compactness, light weight, low noise, and high efficiency. These entailments present significant engineering challenges to develop a new design with wide consumer adoption. PMID:24892102

  13. Human distal sciatic nerve fascicular anatomy: implications for ankle control using nerve-cuff electrodes.

    PubMed

    Gustafson, Kenneth J; Grinberg, Yanina; Joseph, Sheeba; Triolo, Ronald J

    2012-01-01

    The design of neural prostheses to restore standing balance, prevent foot drop, or provide active propulsion during ambulation requires detailed knowledge of the distal sciatic nerve anatomy. Three complete sciatic nerves and branches were dissected from the piriformis to each muscle entry point to characterize the branching patterns and diameters. Fascicle maps were created from serial sections of each distal terminus below the knee through the anastomosis of the tibial and common fibular nerves above the knee. Similar branching patterns and fascicle maps were observed across specimens. Fascicles innervating primary plantar flexors, dorsiflexors, invertors, and evertors were distinctly separate and functionally organized in the proximal tibial, common fibular, and distal sciatic nerves; however, fascicles from individual muscles were not apparent at these levels. The fascicular organization is conducive to selective stimulation for isolated and/or balanced dorsiflexion, plantar flexion, eversion, and inversion through a single multicontact nerve-cuff electrode. These neuroanatomical data are being used to design nerve-cuff electrodes for selective control of ankle movement and improve current lower-limb neural prostheses.

  14. Reduced expression of regeneration associated genes in chronically axotomized facial motoneurons.

    PubMed

    Gordon, T; You, S; Cassar, S L; Tetzlaff, W

    2015-02-01

    Chronically axotomized motoneurons progressively fail to regenerate their axons. Since axonal regeneration is associated with the increased expression of tubulin, actin and GAP-43, we examined whether the regenerative failure is due to failure of chronically axotomized motoneurons to express and sustain the expression of these regeneration associated genes (RAGs). Chronically axotomized facial motoneurons were subjected to a second axotomy to mimic the clinical surgical procedure of refreshing the proximal nerve stump prior to nerve repair. Expression of α1-tubulin, actin and GAP-43 was analyzed in axotomized motoneurons using in situ hybridization followed by autoradiography and silver grain quantification. The expression of these RAGs by acutely axotomized motoneurons declined over several months. The chronically injured motoneurons responded to a refreshment axotomy with a re-increase in RAG expression. However, this response to a refreshment axotomy of chronically injured facial motoneurons was less than that seen in acutely axotomized facial motoneurons. These data demonstrate that the neuronal RAG expression can be induced by injury-related signals and does not require acute deprivation of target derived factors. The transient expression is consistent with a transient inflammatory response to the injury. We conclude that transient RAG expression in chronically axotomized motoneurons and the weak response of the chronically axotomized motoneurons to a refreshment axotomy provides a plausible explanation for the progressive decline in regenerative capacity of chronically axotomized motoneurons.

  15. Modulation of human motoneuron activity by a mental arithmetic task.

    PubMed

    Bensoussan, Laurent; Duclos, Yann; Rossi-Durand, Christiane

    2012-10-01

    This study aimed to determine whether the performance of a mental task affects motoneuron activity. To this end, the tonic discharge pattern of wrist extensor motor units was analyzed in healthy subjects while they were required to maintain a steady wrist extension force and to concurrently perform a mental arithmetic (MA) task. A shortening of the mean inter-spike interval (ISI) and a decrease in ISI variability occurred when MA task was superimposed to the motor task. Aloud and silent MA affected equally the rate and variability of motoneuron discharge. Increases in surface EMG activity and force level were consistent with the modulation of the motor unit discharge rate. Trial-by-trial analysis of the characteristics of motor unit firing revealed that performing MA increases activation of wrist extensor SMU. It is suggested that increase in muscle spindle afferent activity, resulting from fusimotor drive activation by MA, may have contributed to the increase in synaptic inputs to motoneurons during the mental task performance, likely together with enhancement in the descending drive. The finding that a mental task affects motoneuron activity could have consequences in assessment of motor disabilities and in rehabilitation in motor pathologies.

  16. Motoneuron glutamatergic receptor expression following recovery from cervical spinal hemisection.

    PubMed

    Gransee, Heather M; Gonzalez Porras, Maria A; Zhan, Wen-Zhi; Sieck, Gary C; Mantilla, Carlos B

    2017-04-01

    Cervical spinal hemisection at C2 (SH) removes premotor drive to phrenic motoneurons located in segments C3-C5 in rats. Spontaneous recovery of ipsilateral diaphragm muscle activity is associated with increased phrenic motoneuron expression of glutamatergic N-methyl-D-aspartate (NMDA) receptors and decreased expression of α-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA) receptors. Glutamatergic receptor expression is regulated by tropomyosin-related kinase receptor subtype B (TrkB) signaling in various neuronal systems, and increased TrkB receptor expression in phrenic motoneurons enhances recovery post-SH. Accordingly, we hypothesize that recovery of ipsilateral diaphragm muscle activity post-SH, whether spontaneous or enhanced by adenoassociated virus (AAV)-mediated upregulation of TrkB receptor expression, is associated with increased expression of glutamatergic NMDA receptors in phrenic motoneurons. Adult male Sprague-Dawley rats underwent diaphragm electromyography electrode implantation and SH surgery. Rats were injected intrapleurally with AAV expressing TrkB or GFP 3 weeks before SH. At 14 days post-SH, the proportion of animals displaying recovery of ipsilateral diaphragm activity increased in AAV-TrkB-treated (9/9) compared with untreated (3/5) or AAV-GFP-treated (4/10; P < 0.027) animals. Phrenic motoneuron NMDA NR1 subunit mRNA expression was approximately fourfold greater in AAV-TrkB- vs. AAV-GFP-treated SH animals (P < 0.004) and in animals displaying recovery vs. those not recovering (P < 0.005). Phrenic motoneuron AMPA glutamate receptor 2 (GluR2) subunit mRNA expression decreased after SH, and, albeit increased in animals displaying recovery vs. those not recovering, levels remained lower than control. We conclude that increased phrenic motoneuron expression of glutamatergic NMDA receptors is associated with spontaneous recovery after SH and enhanced recovery after AAV-TrkB treatment. J. Comp. Neurol. 525:1192-1205, 2017.

  17. American Orthopaedic Foot and Ankle Society

    MedlinePlus

    ... education site of the American Orthopaedic Foot & Ankle Society. Patients Visit the official patient education site of the American Orthopaedic Foot & Ankle Society. Patients Visit the official patient education site of ...

  18. American College of Foot and Ankle Surgeons

    MedlinePlus

    ... Week @ ACFAS Poll Results Arthroscopy e-Book The Journal of Foot & Ankle Surgery Read some of the latest research from the official peer-reviewed scientific journal of ACFAS, The Journal of Foot & Ankle Surgery ( ...

  19. Evidence for the maintenance of motoneurone properties by msucel activity.

    PubMed Central

    Czéh, G; Gallego, R; Kudo, N; Kuno, M

    1978-01-01

    1. Electrophysiological properties of soleus motoneurones in adult cats were examined with intracellular electrodes following alterations of activity of the soleus muscle induced by transection of the thoracic spinal cord or by conduction block of the muscle nerve with tetrodotoxin (TTX) cuffs. Attempts were also made to maintain muscle activity by daily stimulation of the maintain muscle activity by daily stimulation of the peripheral nerve. 2. Within 8 days after transection of the thoracic cord, soleus motoneurones showed a significant decrease in the duration of afterhyperpolarization following action potentials. This change in motoneurone properties induced by cord transection was prevented by daily stimulation of the sciatic nerve. 3. Soleus motoneurones showed a significant decrease in the duration of after-hyperpolarization within 8 days after conduction block of the soleus nerve with TTX. This change in montoneurone properties was prevented by daily stimulation of the nerve peripheral to the TTX cuff but not central to the cuff. 4. The soleus muscle showed a significant decrease in weight relative to body weight within 8 days after transection of the thoracic cord. This decrease in muscle weight following cord transection was prevented by daily stimulation of the sciatic nerve. 5. No fibrillation was detected in the soleus muscle 8 days after conduction block of the soleus nerve with TTX. The maximum twitch tension of the soleus muscle evoked by nerve stimulation showed no significant difference between the two sides treated and untreated with TTX. Fast axoplasmic transport measured with cholinesterase as a marker was not affected by TTX. Thus, there was no sign of functional although morphological abnormalities were found in some nerve fibres. 6. It is concluded that motoneurone properties in an adult depend partly upon some factors associated with activity of the innervated muscles and that such trophic signals are retrogradely carried by the motor axons

  20. Subperiosteal Hematoma of the Ankle

    PubMed Central

    Hui, S H; Lui, T H

    2016-01-01

    Introduction: Periosteal reaction has a long list of differential diagnoses ranging from trauma, infection, metabolic disease to malignancy. The morphology of periosteal reaction shown in imaging studies helps to narrow down the list of differential diagnoses. Case report: A 25 year old gentleman had an inversion injury to his left ankle. He complained of lateral ankle and posterior heel pain and swelling after the injury. Radiograph of his left ankle revealed solid, smooth periosteal reaction at posterior aspect of left distal tibia. MRI showed periosteal reaction at the corresponding site, which was better demonstrated in CT scan. Follow up MRI and CT showed maturation of the new bone formation at the site of periosteal reaction. Findings were compatible with subperiosteal hematoma formation from injury, which ossified with time. Conclusion: Smooth, thick periosteal reaction favours benign process, while interrupted pattern is an alarming feature for more aggressive causes. PMID:27299131

  1. Effects of ankle eversion taping using kinesiology tape in a patient with ankle inversion sprain

    PubMed Central

    Lee, Sun-Min; Lee, Jung-Hoon

    2016-01-01

    [Purpose] The aim of this study was to report the effects of ankle eversion taping using kinesiology tape on ankle inversion sprain. [Subject] The subject was a 21-year-old woman with Grade 2 ankle inversion sprain. [Methods] Ankle eversion taping was applied to the sprained left ankle using kinesiology tape for 4 weeks (average, 15 h/day). [Results] Ankle instability and pain were reduced, and functional dynamic balance was improved after ankle eversion taping for 4 weeks. The Cumberland Ankle Instability Tool score and reach distances in the Y-Balance and lunge tests were increased. [Conclusion] Repeated ankle eversion taping may be an effective treatment intervention for ankle inversion sprain. PMID:27064668

  2. The Incidence of Ankle Sprains in Orienteering.

    ERIC Educational Resources Information Center

    Ekstrand, Jan; And Others

    1990-01-01

    Investigates relationship between ankle sprains and participation time in competitive orienteering. Examined 15,474 competitors in races in the Swedish O-ringen 5-day event in 1987. Injuries requiring medical attention were analyzed, showing 137 (23.9 percent) ankle sprains. Injury incidence was 8.4/10,000 hours. Incidence of ankle sprains was…

  3. Early intrinsic hyperexcitability does not contribute to motoneuron degeneration in amyotrophic lateral sclerosis

    PubMed Central

    Leroy, Félix; Lamotte d'Incamps, Boris; Imhoff-Manuel, Rebecca D; Zytnicki, Daniel

    2014-01-01

    In amyotrophic lateral sclerosis (ALS) the large motoneurons that innervate the fast-contracting muscle fibers (F-type motoneurons) are vulnerable and degenerate in adulthood. In contrast, the small motoneurons that innervate the slow-contracting fibers (S-type motoneurons) are resistant and do not degenerate. Intrinsic hyperexcitability of F-type motoneurons during early postnatal development has long been hypothesized to contribute to neural degeneration in the adult. Here, we performed a critical test of this hypothesis by recording from identified F- and S-type motoneurons in the superoxide dismutase-1 mutant G93A (mSOD1), a mouse model of ALS at a neonatal age when early pathophysiological changes are observed. Contrary to the standard hypothesis, excitability of F-type motoneurons was unchanged in the mutant mice. Surprisingly, the S-type motoneurons of mSDO1 mice did display intrinsic hyperexcitability (lower rheobase, hyperpolarized spiking threshold). As S-type motoneurons are resistant in ALS, we conclude that early intrinsic hyperexcitability does not contribute to motoneuron degeneration. DOI: http://dx.doi.org/10.7554/eLife.04046.001 PMID:25313866

  4. Motoneurons dedicated to either forward or backward locomotion in the nematode Caenorhabditis elegans.

    PubMed

    Haspel, Gal; O'Donovan, Michael J; Hart, Anne C

    2010-08-18

    Multifunctional motoneurons and muscles, which are active during forward and backward locomotion are ubiquitous in animal models. However, studies in the nematode Caenorhabditis elegans suggest that some locomotor motoneurons are necessary only for forward locomotion (dorsal B-motoneurons, DB), while others (dorsal A-motoneurons, DA) are necessary only for backward locomotion. We tested this hypothesis directly by recording the activity of these motoneurons during semirestrained locomotion. For this purpose, we used epifluorescence imaging of the genetically encoded calcium sensor cameleon, expressed in specific motoneurons, while monitoring locomotor behavior through the microscope condenser using a second camera. We found that ventral and dorsal B-motoneurons (DB and VB) were coactive during forward locomotion while ventral A-motoneurons (VA) were only active during backward locomotion. The signals we recorded correlated with the direction of locomotion but not with the faster undulatory cycles. To our knowledge, these are the first recordings of motoneuron activity in C. elegans and the only direction-dedicated motoneurons described to date.

  5. Dual encoding of muscle tension and eye position by abducens motoneurons

    PubMed Central

    Davis-López de Carrizosa, María A.; Morado-Díaz, Camilo J.; Miller, Joel M.; de la Cruz, Rosa R.; Pastor, Ángel M.

    2011-01-01

    Extraocular muscle tension associated with spontaneous eye movements has a pulse-slide-step profile similar to that of motoneuron firing rate. Existing models only relate motoneuron firing to eye position, velocity and acceleration. We measured and quantitatively compared lateral rectus muscle force and eye position with the firing of abducens motoneurons in the cat to determine fundamental encoding correlations. During fixations (step), muscle force increased exponentially with eccentric eye position, consistent with a model of estimate ensemble motor innervation based on neuronal sensitivities and recruitment order. Moreover, firing rate in all motoneurons tested was better related to eye position than to muscle tension during fixations. In contrast, during the postsaccadic slide phase, the time constant of firing rate decay was closely related to that of muscle force decay, suggesting that all motoneurons encode muscle tension as well. Discharge characteristics of abducens motoneurons formed overlapping clusters of phasic and tonic motoneurons, thus, tonic units recruited earlier and had a larger slide signal. We conclude that the slide signal is a discharge characteristic of the motoneuron that controls muscle tension during the post-saccadic phase and that motoneurons are specialized for both tension and position-related properties. The organization of signal content in the pool of abducens motoneurons from the very phasic to the very tonic units is possibly a result of the differential trophic background received from distinct types of muscle fibers. PMID:21307263

  6. Succinate dehydrogenase activity and soma size of motoneurons innervating different portions of the rat tibialis anterior

    NASA Technical Reports Server (NTRS)

    Ishihara, A.; Roy, R. R.; Edgerton, V. R.

    1995-01-01

    The spatial distribution, soma size and oxidative enzyme activity of gamma and alpha motoneurons innervating muscle fibres in the deep (away from the surface of the muscle) and superficial (close to the surface of the muscle) portions of the tibialis anterior in normal rats were determined. The deep portion had a higher percentage of high oxidative fibres than the superficial portion of the muscle. Motoneurons were labelled by retrograde neuronal transport of fluorescent tracers: Fast Blue and Nuclear Yellow were injected into the deep portion and Nuclear Yellow into the superficial portion of the muscle. Therefore, motoneurons innervating the deep portion were identified by both a blue fluorescent cytoplasm and a golden-yellow fluorescent nucleus, while motoneurons innervating the superficial portion were identified by only a golden-yellow fluorescent nucleus. After staining for succinate dehydrogenase activity on the same section used for the identification of the motoneurons, soma size and succinate dehydrogenase activity of the motoneurons were measured. The gamma and alpha motoneurons innervating both the deep and superficial portions were located primarily at L4 and were intermingled within the same region of the dorsolateral portion of the ventral horn in the spinal cord. Mean soma size was similar for either gamma or alpha motoneurons in the two portions of the muscle. The alpha motoneurons innervating the superficial portion had a lower mean succinate dehydrogenase activity than those innervating the deep portion of the muscle. An inverse relationship between soma size and succinate dehydrogenase activity of alpha, but not gamma, motoneurons innervating both the deep and superficial portions was observed. Based on three-dimensional reconstructions within the spinal cord, there were no apparent differences in the spatial distribution of the motoneurons, either gamma or alpha, associated with the deep and superficial compartments of the muscle. The data

  7. Foot and ankle problems in dancers.

    PubMed

    Kadel, Nancy

    2014-11-01

    The dancer's foot and ankle are subjected to high forces and unusual stresses in training and performance. Injuries are common in dancers, and the foot and ankle are particularly vulnerable. Ankle sprains, ankle impingement syndromes, flexor hallucis longus tendonitis, cuboid subluxation, stress fractures, midfoot injuries, heel pain, and first metatarsophalangeal joint problems including hallux valgus, hallux rigidus, and sesamoid injuries will be reviewed. This article will discuss these common foot and ankle problems in dancers and give typical clinical presentation and diagnostic and treatment recommendations.

  8. Posterior tibial nerve lesions in ankle arthroscopy.

    PubMed

    Cugat, Ramon; Ares, Oscar; Cuscó, Xavier; Garcia, Montserrat; Samitier, Gonzalo; Seijas, Roberto

    2008-05-01

    Ankle arthroscopy provides a minimally invasive approach to the diagnosis and treatment of certain ankle disorders. Neurological complications resulting from ankle arthroscopy have been well documented in orthopaedic and podiatric literature. Owing to the superficial location of the ankle joint and the abundance of overlying periarticular neurovascular structures, complications reported in ankle arthroscopy are greater than those reported for other joints. In particular, all reported neurovascular injuries following ankle arthroscopy have been the direct result of distractor pin or portal placement. The standard posteromedial portal has recognized risks because of the proximity of the posterior neurovascular structures. There can be considerable variability in the course of these portals and their proximity to the neurovascular structures. We found one report of intra-articular damage to the posterior tibial nerve as a result of ankle arthroscopy in the English-language literature and we report this paper as a second case described in the literature.

  9. Ankle inversion taping using kinesiology tape for treating medial ankle sprain in an amateur soccer player

    PubMed Central

    Lee, Sun-Min; Lee, Jung-Hoon

    2015-01-01

    [Purpose] The purpose of this study was to report the effects of ankle inversion taping using kinesiology tape in a patient with a medial ankle sprain. [Subject] A 28-year-old amateur soccer player suffered a Grade 2 medial ankle sprain during a match. [Methods] Ankle inversion taping was applied to the sprained ankle every day for 2 months. [Results] His symptoms were reduced after ankle inversion taping application for 2 months. The self-reported function score, the reach distances in the Star Excursion Balance Test, and the weight-bearing ankle dorsiflexion were increased. [Conclusion] This study showed that ankle inversion taping using kinesiology tape may be an effective therapy for a patient with a medial ankle sprain. PMID:26311991

  10. Inhibition of Sirt1 promotes neural progenitors toward motoneuron differentiation from human embryonic stem cells

    SciTech Connect

    Zhang, Yun; Wang, Jing; Chen, Guian; Fan, Dongsheng; Deng, Min

    2011-01-14

    Research highlights: {yields} Nicotinamide inhibit Sirt1. {yields} MASH1 and Ngn2 activation. {yields} Increase the expression of HB9. {yields} Motoneurons formation increases significantly. -- Abstract: Several protocols direct human embryonic stem cells (hESCs) toward differentiation into functional motoneurons, but the efficiency of motoneuron generation varies based on the human ESC line used. We aimed to develop a novel protocol to increase the formation of motoneurons from human ESCs. In this study, we tested a nuclear histone deacetylase protein, Sirt1, to promote neural precursor cell (NPC) development during differentiation of human ESCs into motoneurons. A specific inhibitor of Sirt1, nicotinamide, dramatically increased motoneuron formation. We found that about 60% of the cells from the total NPCs expressed HB9 and {beta}III-tubulin, commonly used motoneuronal markers found in neurons derived from ESCs following nicotinamide treatment. Motoneurons derived from ESC expressed choline acetyltransferase (ChAT), a positive marker of mature motoneuron. Moreover, we also examined the transcript levels of Mash1, Ngn2, and HB9 mRNA in the differentiated NPCs treated with the Sirt1 activator resveratrol (50 {mu}M) or inhibitor nicotinamide (100 {mu}M). The levels of Mash1, Ngn2, and HB9 mRNA were significantly increased after nicotinamide treatment compared with control groups, which used the traditional protocol. These results suggested that increasing Mash1 and Ngn2 levels by inhibiting Sirt1 could elevate HB9 expression, which promotes motoneuron differentiation. This study provides an alternative method for the production of transplantable motoneurons, a key requirement in the development of hESC-based cell therapy in motoneuron disease.

  11. Innovations in motoneuron synchrony drive rapid temporal modulations in vertebrate acoustic signaling

    PubMed Central

    Chagnaud, Boris P.; Zee, Michele C.; Baker, Robert

    2012-01-01

    Rapid temporal modulation of acoustic signals among several vertebrate lineages has recently been shown to depend on the actions of superfast muscles. We hypothesized that such fast events, known to require synchronous activation of muscle fibers, would rely on motoneuronal properties adapted to generating a highly synchronous output to sonic muscles. Using intracellular in vivo recordings, we identified a suite of premotor network inputs and intrinsic motoneuronal properties synchronizing the oscillatory-like, simultaneous activation of superfast muscles at high gamma frequencies in fish. Motoneurons lacked spontaneous activity, firing synchronously only at the frequency of premotor excitatory input. Population-level motoneuronal output generated a spike-like, vocal nerve volley that directly determines muscle contraction rate and, in turn, natural call frequency. In the absence of vocal output, motoneurons showed low excitability and a weak afterhyperpolarization, leading to rapid accommodation in firing rate. By contrast, vocal activity was accompanied by a prominent afterhyperpolarization, indicating a dependency on network activity. Local injection of a GABAA receptor antagonist demonstrated the necessity of electrophysiologically and immunohistochemically confirmed inhibitory GABAergic input for motoneuronal synchrony and vocalization. Numerous transneuronally labeled motoneurons following single-cell neurobiotin injection together with electrophysiological collision experiments confirmed gap junctional coupling, known to contribute to synchronous activity in other neural networks. Motoneuronal synchrony at the premotor input frequency was maintained during differential recruitment of variably sized motoneurons. Differential motoneuron recruitment led, however, to amplitude modulation (AM) of vocal output and, hence, natural call AM. In summary, motoneuronal intrinsic properties, in particular low excitability, predisposed vocal motoneurons to the

  12. Significance of 2,4-dinitrophenol action on spinal motoneurones.

    PubMed

    Krnjević, K; Puil, E; Werman, R

    1978-02-01

    1. Extracellular iontophoretic applications of DNP lead to an increase in the membrane conductance of cat spinal motoneurones, manifested by a rise in input conductance, a slower rate of rise and fall of action potentials, and occlusion of the afterhyperpolarization. 2. There is also some hyperpolarization, but the reversal potential for the action of DNP is only about 12 mV more negative than the resting potential. 3. These effect of DNP can be abolished or significantly reduced by intracellular injections of EGTA. On the other hand, DNP can partly reverse the decreased conductance and the depression of the slow afterhyperpolarization caused by EGTA. 4. Intracellular injections of DNP also induce a rise in input conductance; when repeated, they tend to have a depolarizing effect, mainly irreversible. 5. It is concluded that DNP acts principally inside the motoneurone, by liberating bound internal Ca, the free Ca ions then raising membrane conductance, especially GK.

  13. Progesterone neuroprotection in traumatic CNS injury and motoneuron degeneration.

    PubMed

    De Nicola, Alejandro F; Labombarda, Florencia; Gonzalez Deniselle, Maria Claudia; Gonzalez, Susana L; Garay, Laura; Meyer, Maria; Gargiulo, Gisella; Guennoun, Rachida; Schumacher, Michael

    2009-07-01

    Studies on the neuroprotective and promyelinating effects of progesterone in the nervous system are of great interest due to their potential clinical connotations. In peripheral neuropathies, progesterone and reduced derivatives promote remyelination, axonal regeneration and the recovery of function. In traumatic brain injury (TBI), progesterone has the ability to reduce edema and inflammatory cytokines, prevent neuronal loss and improve functional outcomes. Clinical trials have shown that short-and long-term progesterone treatment induces a significant improvement in the level of disability among patients with brain injury. In experimental spinal cord injury (SCI), molecular markers of functional motoneurons become impaired, including brain-derived neurotrophic factor (BDNF) mRNA, Na,K-ATPase mRNA, microtubule-associated protein 2 and choline acetyltransferase (ChAT). SCI also produces motoneuron chromatolysis. Progesterone treatment restores the expression of these molecules while chromatolysis subsided. SCI also causes oligodendrocyte loss and demyelination. In this case, a short progesterone treatment enhances proliferation and differentiation of oligodendrocyte progenitors into mature myelin-producing cells, whereas prolonged treatment increases a transcription factor (Olig1) needed to repair injury-induced demyelination. Progesterone neuroprotection has also been shown in motoneuron neurodegeneration. In Wobbler mice spinal cord, progesterone reverses the impaired expression of BDNF, ChAT and Na,K-ATPase, prevents vacuolar motoneuron degeneration and the development of mitochondrial abnormalities, while functionally increases muscle strength and the survival of Wobbler mice. Multiple mechanisms contribute to these progesterone effects, and the role played by classical nuclear receptors, extra nuclear receptors, membrane receptors, and the reduced metabolites of progesterone in neuroprotection and myelin formation remain an exciting field worth of exploration.

  14. Programmed Cell Death of Embryonic Motoneurons Triggered through the FAS Death Receptor

    PubMed Central

    Raoul, Cédric; Henderson, Christopher E.; Pettmann, Brigitte

    1999-01-01

    About 50% of spinal motoneurons undergo programmed cell death (PCD) after target contact, but little is known about how this process is initiated. Embryonic motoneurons coexpress the death receptor Fas and its ligand FasL at the stage at which PCD is about to begin. In the absence of trophic factors, many motoneurons die in culture within 2 d. Most (75%) of these were saved by Fas-Fc receptor body, which blocks interactions between Fas and FasL, or by the caspase-8 inhibitor tetrapeptide IETD. Therefore, activation of Fas by endogenous FasL underlies cell death induced by trophic deprivation. In the presence of neurotrophic factors, exogenous Fas activators such as soluble FasL or anti-Fas antibodies triggered PCD of 40–50% of purified motoneurons over the following 3–5 d; this treatment led to activation of caspase-3, and was blocked by IETD. Sensitivity to Fas activation is regulated: motoneurons cultured for 3 d with neurotrophic factors became completely resistant. Levels of Fas expressed by motoneurons varied little, but FasL was upregulated in the absence of neurotrophic factors. Motoneurons resistant to Fas activation expressed high levels of FLICE-inhibitory protein (FLIP), an endogenous inhibitor of caspase-8 activation. Our results suggest that Fas can act as a driving force for motoneuron PCD, and raise the possibility that active triggering of PCD may contribute to motoneuron loss during normal development and/or in pathological situations. PMID:10579724

  15. BDNF-mediated modulation of glycine transmission on rat spinal motoneurons.

    PubMed

    Ding, Jian-Dong; Tang, Xian-Ye; Shi, Jian-Gang; Jia, Lian-Shun

    2014-08-22

    BDNF has a widespread distribution in the central and peripheral nervous systems, suggesting that BDNF may play a role in the regulation of motor control. However, the direct actions of BDNF on the motoneurons and their underlying mechanisms are still largely unknown to date. Therefore, by using whole-cell patch clamp recordings, quantitative RT-PCR and immunocytochemistry, the present study was designed to investigate the effects of BDNF on electrical activity and glycinergic transmission on the motoneurons and the underlying receptor mechanism. The results reveal: (i) BDNF did not produce a direct excitatory or inhibitory effect on the motoneurons; (ii) BDNF dose-dependently increased the glycinergic transmission on the motoneurons; (iii) glycinergic transmission on motoneurons was a direct postsynaptic effect; (iv) BDNF-induced enhancement of the glycinergic transmission was mediated by the activation of TrkB receptors; and (v) BDNF and its receptors TrkB had an extensive expression in the motoneurons. These results suggest that BDNF is directly involved in the regulation of glycinergic transmission on the motoneurons through postsynaptic TrkB receptors. Considering that the glycinergic synaptic transmission of motoneurons mainly comes from Renshaw cells, the important inhibitory interneurons of spinal cord, we speculate that BDNF may play an important role in the information integration in the spinal cord and participate in the sensitivity of motoneurons.

  16. Extraocular motoneuron pools develop along a dorsoventral axis in zebrafish, Danio rerio

    PubMed Central

    Privorotskiy, Ann E.; D'Elia, Kristen P.

    2016-01-01

    ABSTRACT Both spatial and temporal cues determine the fate of immature neurons. A major challenge at the interface of developmental and systems neuroscience is to relate this spatiotemporal trajectory of maturation to circuit‐level functional organization. This study examined the development of two extraocular motor nuclei (nIII and nIV), structures in which a motoneuron's identity, or choice of muscle partner, defines its behavioral role. We used retro‐orbital dye fills, in combination with fluorescent markers for motoneuron location and birthdate, to probe spatial and temporal organization of the oculomotor (nIII) and trochlear (nIV) nuclei in the larval zebrafish. We describe a dorsoventral organization of the four nIII motoneuron pools, in which inferior and medial rectus motoneurons occupy dorsal nIII, while inferior oblique and superior rectus motoneurons occupy distinct divisions of ventral nIII. Dorsal nIII motoneurons are, moreover, born before motoneurons of ventral nIII and nIV. The order of neurogenesis can therefore account for the dorsoventral organization of nIII and may play a primary role in determining motoneuron identity. We propose that the temporal development of extraocular motoneurons plays a key role in assembling a functional oculomotor circuit. J. Comp. Neurol. 525:65–78, 2017. © 2016 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc. PMID:27197595

  17. The Scandinavian Total Ankle Replacement and the ideal biomechanical requirements of ankle replacements

    PubMed Central

    Robati, Shibby; Salih, Alan; Ghosh, Koushik; Vinayakam, Parthiban

    2016-01-01

    The complex anatomy of the articular bone surfaces, ligaments, tendon attachments and muscles makes the ankle joint difficult to replicate in prosthetic replacements. Ever since the early 1970s, which saw the dawn of the first total ankle replacements, there have been numerous other attempts at replicating the joint, often with poor clinical outcomes. The anatomy of the ankle is discussed, followed by evidence of the normal ankle biomechanics and the ideal requirements of an ankle replacement. We focus on the Scandinavian Total Ankle Replacement and evaluate whether these requirements have been met. PMID:26955224

  18. The Scandinavian Total Ankle Replacement and the ideal biomechanical requirements of ankle replacements.

    PubMed

    Robati, Shibby; Salih, Alan; Ghosh, Koushik; Vinayakam, Parthiban

    2016-03-01

    The complex anatomy of the articular bone surfaces, ligaments, tendon attachments and muscles makes the ankle joint difficult to replicate in prosthetic replacements. Ever since the early 1970s, which saw the dawn of the first total ankle replacements, there have been numerous other attempts at replicating the joint, often with poor clinical outcomes. The anatomy of the ankle is discussed, followed by evidence of the normal ankle biomechanics and the ideal requirements of an ankle replacement. We focus on the Scandinavian Total Ankle Replacement and evaluate whether these requirements have been met.

  19. Brainstem origin of preganglionic cardiac motoneurons in the muskrat.

    PubMed

    Panneton, W M; McCulloch, P F; Tan, Y; Tan, Y; Yavari, P

    1996-11-04

    The muskrat, and aquatic rodent with a brisk and reliable diving response, shows a remarkable bradycardia after nasal stimulation. However, the medullary origin of cardiac preganglionic motoneurons is unknown in this species. We injected fat pads near the base of the heart of muskrats with a WGA-HRP solution to label retrogradely preganglionic parasympathetic neurons that project to the cardiac plexi. Results showed that the preponderance of labeled neurons was in ventrolateral parts of the medulla from 1.5 mm caudal to the obex to 2.0 mm rostral. Eighty-nine percent of the labeled neurons were located bilaterally in the external formation of the nucleus ambiguus, 5.6% were in the lateral extreme of the dorsal motor nucleus of the vagus nerve and 5.3% were found in the intermediate area in between these two nuclei. Although controversy still exists concerning the medullary origin of preganglionic cardiac motoneurons, our results from muskrats agree with those from most other species where preganglionic cardiac motoneurons were located just ventral to the nucleus ambiguus.

  20. Motoneuron activity in patients with different types of tremor.

    PubMed

    Milanov, I

    2001-12-01

    The aim of this work was to examine the segmental motoneuron activity as a possible mechanism of tremor generation. Eighty-three patients with different types of tremor (25 with Parkinsonian, 29 with essential, and 30 with enhanced physiological tremor due to anxiety), 25 Parkinsonian patients without tremor and 30 healthy volunteers were examined. The tremor was studied clinically and by electromyography in all limb positions. The F wave was examined for assessment of motoneuron activity. The wave was recorded after stimulation of the ulnar, median, tibial and fibular nerves. The maximal and mean F wave amplitudes, frequency of occurrence and number of phases were increased, and the duration was prolonged in all group of patients as compared to the healthy persons. The maximal and the mean F/M amplitude ratios, as well as the Fmean./Fmax amplitude ratio were increased in all groups of patients. All F wave parameters were most altered in Parkinsonian tremor patients followed by patients with rigidity. In conclusion increased motoneuron activity participates in generation of different types of tremor and in Parkinsonian rigidity.

  1. A systematic review on ankle injury and ankle sprain in sports.

    PubMed

    Fong, Daniel Tik-Pui; Hong, Youlian; Chan, Lap-Ki; Yung, Patrick Shu-Hang; Chan, Kai-Ming

    2007-01-01

    This article systematically reviews epidemiological studies on sports injury from 1977 to 2005 in which ankle injury was included. A total of 227 studies reporting injury pattern in 70 sports from 38 countries were included. A total of 201,600 patients were included, with 32,509 ankle injuries. Ankle injury information was available from 14,098 patients, with 11 847 ankle sprains. Results show that the ankle was the most common injured body site in 24 of 70 included sports, especially in aeroball, wall climbing, indoor volleyball, mountaineering, netball and field events in track and field. Ankle sprain was the major ankle injury in 33 of 43 sports, especially in Australian football, field hockey, handball, orienteering, scooter and squash. In sports injuries throughout the countries studied, the ankle was the second most common injured body site after the knee, and ankle sprain was the most common type of ankle injury. The incidence of ankle injury and ankle sprain was high in court games and team sports, such as rugby, soccer, volleyball, handball and basketball. This systematic review provides a summary of the epidemiology of ankle injury in sports.

  2. Direct excitation of rat spinal motoneurones by serotonin.

    PubMed Central

    Takahashi, T; Berger, A J

    1990-01-01

    1. The effects of serotonin (5-HT) on visually identified motoneurones were investigated using the whole-cell recording technique in a neonatal rat spinal cord slice preparation. 2. In current-clamp recordings, bath application of 5-HT depolarized motoneurones. This effect was observed after synaptic inputs were abolished by replacing external Ca2+ with Mg2+. 3. In voltage-clamp recordings at holding potentials of -70 to -90 mV, 5-HT induced an inward current (I5-HT) in motoneurones in a Ca2(+)-free-Mg2+ solution containing tetrodotoxin. This inward current was accompanied by an increase in membrane conductance, which was prominent at voltages negative to the holding potential. 4. The inward I5-HT response declined with repeated short applications of 5-HT. I5-HT produced by a single prolonged application (5 min) was only slightly diminished during the application period. 5. The minimum effective dose of 5-HT for initiating the inward I5-HT was less than 10 nM. At 10 microM, I5-HT approached maximal levels. The averaged dissociation constant (Kd) for 5-HT was approximately 120 nM. 6. Application of spiperone, the mixed 5-HT1A, 5-HT2 receptor antagonist, blocked the inward I5-HT. Application of (+)-8-OH-dipropylaminotetralin (8-OHDPAT), a 5-HT1A agonist, mimicked the action of 5-HT. 7. Various K+ channel blockers including tetraethylammonium chloride (30 mM), 4-aminopyridine (4 mM) and apamin (100 nM) did not abolish I5-HT. Application of extracellular Cs+ (10 mM) blocked I5-HT. 8. Peak inward I5-HT became larger with increasing extracellular K+. With low Cl- pipette solution (less than 1 mM), or in low extracellular Na+ solution (26 mM), the inward I5-HT was not abolished. 9. The current-voltage relation of I5-HT displayed inward rectification. In high external K+ concentration (20 mM), the reversal potential was about -29 mV, which is close to that of the inward rectifier evoked in motoneurones by membrane hyperpolarization. 10. The current generated by 5-HT

  3. Posterior ankle impingement in the dancer.

    PubMed

    Moser, Brad R

    2011-01-01

    Dancers spend a lot of time in the relevé position in demi-pointe and en pointe in their training and their careers. Pain from both osseous and soft tissue causes may start to occur in the posterior aspect of their ankle. This article reviews the potential causes of posterior ankle impingement in dancers. It will discuss the clinical evaluation of a dancer and the appropriate workup and radiographic studies needed to further evaluate a dancer with suspected posterior ankle impingement.

  4. Total Ankle Arthroplasty: An Imaging Overview

    PubMed Central

    Kim, Da-Rae; Potter, Hollis G.; Li, Angela E.; Chun, Ka-Young; Jung, Yoon Young; Kim, Jin-Su; Young, Ki-Won

    2016-01-01

    With advances in implant technology, total ankle arthroplasty (TAA) has become an increasingly popular alternative to arthrodesis for the management of end-stage ankle arthritis. However, reports in the literature do not focus on the imaging features of TAA. Through a literature review, we demonstrate basic design features of the current ankle arthroplasty system, and the normal and abnormal postoperative imaging features associated with such devices. Pre- and postoperative evaluations of ankle arthroplasty mainly include radiography; in addition, computed tomography and magnetic resonance imaging provide further characterization of imaging abnormalities. Familiarization with multimodal imaging features of frequent procedural complications at various postoperative intervals is important in radiological practice. PMID:27134529

  5. Ankle instability and arthroscopic lateral ligament repair.

    PubMed

    Acevedo, Jorge I; Mangone, Peter

    2015-03-01

    Over the last 50 years, the surgical management of chronic lateral ankle ligament insufficiency has focused on 2 main categories: local soft-tissue reconstruction and tendon grafts/transfer procedures. There is an increasing interest in the arthroscopic solutions for chronic instability of the ankle. Recent biomechanical studies suggest the at least one of the arthroscopic techniques can provide equivalent results to current open local soft-tissue reconstruction (such as the modified Brostrom technique). Arthroscopic lateral ankle ligament reconstruction is becoming an increasingly acceptable method for the surgical management of chronic lateral ankle instability.

  6. Complications of Pediatric Foot and Ankle Fractures.

    PubMed

    Denning, Jaime R

    2017-01-01

    Ankle fractures account for 5% and foot fractures account for approximately 8% of fractures in children. Some complications are evident early in the treatment or natural history of foot and ankle fractures. Other complications do not become apparent until weeks, months, or years after the original fracture. The incidence of long-term sequelae like posttraumatic arthritis from childhood foot and ankle fractures is poorly studied because decades or lifelong follow-up has frequently not been accomplished. This article discusses a variety of complications associated with foot and ankle fractures in children or the treatment of these injuries.

  7. Fusion following failed total ankle replacement.

    PubMed

    Wünschel, Markus; Leichtle, Ulf G; Leichtle, Carmen I; Walter, Christian; Mittag, Falk; Arlt, Eva; Suckel, Andreas

    2013-04-01

    Although mid- to long-term results after total ankle replacement have improved because of available second- and third-generation devices, failure of total ankle replacement is still more common compared with total hip replacement and total knee replacement. The portfolio of available total ankle replacement revision component options is small. Furthermore, the bone stock of the tibiotalar region is scarce making it difficult and in some situations impossible to perform revision total ankle replacement. In these cases tibiotalar and tibiotalocalcaneal fusions are valuable options. This article describes which surgical procedures should be performed depending on the initial situation and gives detailed advice on surgical technique, postoperative care, and clinical results.

  8. Search the Foot and Ankle: Interactive Foot Diagram

    MedlinePlus

    ... foot and ankle surgeons. All Fellows of the College are board certified by the American Board of Foot and Ankle Surgery. Copyright © 2017 American College of Foot and Ankle Surgeons (ACFAS), All Rights ...

  9. The relationship between lateral ankle sprain and ankle tendinitis in ballet dancers.

    PubMed

    Ritter, Stephanie; Moore, Marjorie

    2008-01-01

    The lateral ligament complex of the ankle is the most frequently injured structure in the body. Although most simple ankle sprains do not result in long-term disability, a significant number do not completely resolve, leading to residual symptoms that may persist for years. The most commonly reported symptoms, particularly among athletes, include instability, re-injury, and tendinitis. Ballet dancers are a combination of artist and high-performance athlete; consequently, they are subjected to the same types of injuries as other athletes, including lateral ankle sprains and their sequelae. Furthermore, ballet dancers perform in unusual positions such as en pointe, which places the ankle in extreme plantar flexion, requiring stabilization by surrounding muscles. Dancers' extraordinary performance demands place them at risk for other ankle injuries as well, including inflammation ofseveral tendons, especially the peroneals. This report reviews the relevant literature to characterize the scope of lateral ankle sprains and sequelae, discuss the importance of the peroneal muscles in ankle stability, and explore a relationship between lateral ankle sprain and ankle tendinitis in ballet dancers. Informal interviews were conducted with physical therapists who specialize in treating ballet dancers, providing a clinical context for this report. An extensive review of the literature was conducted, including electronic databases, reference lists from papers, and relevant reference texts. Numerous studies have investigated ankle sprains and residual complaints; nearly all report that lateral ankle sprains commonly lead to chronic ankle instability. Studies exploring ankle stability have demonstrated that the peroneal muscles play a crucial role in ankle stabilization; EMG studies confirm they are the first to contract during ankle inversion stress. The dancer's need for exceptional ankle stabilization may lead to peroneal overuse and tendinitis. Studies have linked peroneal

  10. Transcriptional enhancement of Smn levels in motoneurons is crucial for proper axon morphology in zebrafish

    PubMed Central

    Spiró, Zoltán; Koh, Angela; Tay, Shermaine; See, Kelvin; Winkler, Christoph

    2016-01-01

    An unresolved mystery in the field of spinal muscular atrophy (SMA) is why a reduction of the ubiquitously expressed Smn protein causes defects mostly in motoneurons. We addressed the possibility that this restricted vulnerability stems from elevated Smn expression in motoneurons. To explore this, we established an ex vivo zebrafish culture system of GFP-marked motoneurons to quantitatively measure Smn protein and smn mRNA levels as well as promoter activity in motoneurons versus other cell types. Importantly, we uncovered that Smn levels are elevated in motoneurons by means of transcriptional activation. In addition, we identified the ETS family transcription factor Etv5b to be responsible for increased smn transcription in motoneurons. Moreover, we established that the additional supply of Smn protein in motoneurons is necessary for proper axonogenesis in a cell-autonomous manner. These findings demonstrate the reliance of motoneurons on more Smn, thereby adding a novel piece of evidence for their increased vulnerability under SMA conditions. PMID:27273160

  11. Regeneration-associated genes decline in chronically injured rat sciatic motoneurons.

    PubMed

    Gordon, Tessa; Tetzlaff, Wolfram

    2015-11-01

    Chronic nerve injuries are notorious for their poor regenerative outcomes. Here, we addressed the question of whether the established reduced ability of injured motoneurons to regenerate their axons with time of disconnection with targets (chronic axotomy) is associated with a failure of injured motoneurons to express and sustain their expression of regeneration-associated genes. Sciatic motoneurons were prevented from regenerating by ligation of the transected nerves (chronic axotomy), and then subjected to a second nerve transection (acute axotomy) to mimic the clinical surgical procedure of refreshing the proximal nerve stump prior to delayed nerve repair. The expression of α1-tubulin, actin and GAP-43 mRNA was analysed in axotomized sciatic motoneurons by the use of in situ hybridization followed by autoradiography and silver grain quantification. The expression of these regeneration-associated genes by naive (acutely) axotomized motoneurons declined exponentially, to reach baseline levels within 6 months. These chronically injured motoneurons responded to a refreshment axotomy by elevating the expression of the genes to the same levels as in acutely (i.e. for the first time) axotomized sciatic motoneurons. However, the expression of these declined more rapidly than after acute axotomy. We conclude that a progressive decline in the expression of the regeneration-associated genes in chronically axotomized motoneurons and the even more rapid decline in their expression in response to a refreshment axotomy may explain why the regenerative capacity of chronically axotomized neurons declines with time.

  12. Force regulation of ankle extensor muscle activity in freely walking cats.

    PubMed

    Donelan, J M; McVea, D A; Pearson, K G

    2009-01-01

    To gain insight into the relative importance of force feedback to ongoing ankle extensor activity during walking in the conscious cat, we isolated the medial gastrocnemius muscle (MG) by denervating the other ankle extensors and measured the magnitude of its activity at different muscle lengths, velocities, and forces accomplished by having the animals walk up and down a sloped pegway. Mathematical models of proprioceptor dynamics predicted afferent activity and revealed that the changes in muscle activity under our experimental conditions were strongly correlated with Ib activity and not consistently associated with changes in Ia or group II activity. This allowed us to determine the gains within the force feedback pathway using a simple model of the neuromuscular system and the measured relationship between MG activity and force. Loop gain increased with muscle length due to the intrinsic force-length property of muscle. The gain of the pathway that converts muscle force to motoneuron depolarization was independent of length. To better test for a causal relationship between modulation of force feedback and changes in muscle activity, a second set of experiments was performed in which the MG muscle was perturbed during ground contact of the hind foot by dropping or lifting the peg underfoot. Collectively, these investigations support a causal role for force feedback and indicate that about 30% of the total muscle activity is due to force feedback during level walking. Force feedback's role increases during upslope walking and decreases during downslope walking, providing a simple mechanism for compensating for changes in terrain.

  13. Induction of phosphorylated c-Jun in neonatal spinal motoneurons after axonal injury is coincident with both motoneuron death and regeneration.

    PubMed

    Yuan, Qiuju; Su, Huanxing; Guo, Jiasong; Wu, Wutian; Lin, Zhi-Xiu

    2014-05-01

    c-Jun activation has been implicated not only in neuronal degeneration, but also in survival and regeneration. Here, we investigated c-Jun activation in injured motoneurons by using a nerve crush model in neonatal rats. We identified two distinct subpopulations of motoneurons: about 60% underwent degeneration following injury whereas the remaining 40% survived and induced a regeneration response at 3 weeks post injury. However, all motoneurons examined expressed phosphorylated-c-Jun-immunoreactivity (p-c-Jun-IR) at the early stage of 3 days following injury. These results suggest that active c-Jun was induced in all neonatal motoneurons following nerve crush injury, regardless of whether they were destined to degenerate or undergo successful regeneration at a later stage. Our findings therefore support the hypothesis that active c-Jun is involved in both neuronal degeneration and regeneration.

  14. Induction of phosphorylated c-Jun in neonatal spinal motoneurons after axonal injury is coincident with both motoneuron death and regeneration

    PubMed Central

    Yuan, Qiuju; Su, Huanxing; Guo, Jiasong; Wu, Wutian; Lin, Zhi-Xiu

    2014-01-01

    c-Jun activation has been implicated not only in neuronal degeneration, but also in survival and regeneration. Here, we investigated c-Jun activation in injured motoneurons by using a nerve crush model in neonatal rats. We identified two distinct subpopulations of motoneurons: about 60% underwent degeneration following injury whereas the remaining 40% survived and induced a regeneration response at 3 weeks post injury. However, all motoneurons examined expressed phosphorylated-c-Jun-immunoreactivity (p-c-Jun-IR) at the early stage of 3 days following injury. These results suggest that active c-Jun was induced in all neonatal motoneurons following nerve crush injury, regardless of whether they were destined to degenerate or undergo successful regeneration at a later stage. Our findings therefore support the hypothesis that active c-Jun is involved in both neuronal degeneration and regeneration. PMID:24506149

  15. The giant fiber and pectoral fin adductor motoneuron system in the hatchetfish.

    PubMed

    Gilat, E; Hall, D H; Bennett, M V

    1986-02-12

    In the medulla of the hatchetfish each Mauthner fiber forms chemical synapses on a number of large myelinated axons termed giant fibers. The giant fibers form rectifying electrotonic synapses on pectoral fin adductor motoneurons, and in this fish bilateral pectoral fin adduction is an important component of the Mauthner fiber-mediated escape reflex. The branching patterns of giant fibers were determined by intracellular injection of Lucifer yellow. Dye coupling to the motoneuron somata was not observed, although a low level of transfer might have been obscured by autofluorescence. Individual giant fibers terminate primarily on pectoral fin motoneurons contralateral to their cell bodies, but may also send a branch back across the midline to ipsilateral motoneurons. The rostral process of each giant fiber ends on neurons presumably associated with cranial musculature. The number and geometry of the pectoral fin motoneurons were determined using Golgi and Nissl staining and serial reconstruction methods.

  16. Molecular determinants of emerging excitability in rat embryonic motoneurons

    PubMed Central

    Alessandri-Haber, Nicole; Alcaraz, Giséle; Deleuze, Charlotte; Jullien, Florence; Manrique, Christine; Couraud, François; Crest, Marcel; Giraud, Pierre

    2002-01-01

    Molecular determinants of excitability were studied in pure cultures of rat embryonic motoneurons. Using RT-PCR, we have shown here that the spike-generating Na+ current is supported by Nav1.2 and/or Nav1.3 α-subunits. Nav1.1 and Nav1.6 transcripts were also identified. We have demonstrated that alternatively spliced isoforms of Nav1.1 and Nav1.6, resulting in truncated proteins, were predominant during the first week in culture. However, Nav1.6 protein could be detected after 12 days in vitro. The Navβ2.1 transcript was not detected, whereas the Nav β1.1 transcript was present. Even in the absence of Navβ2.1, α-subunits were correctly inserted into the initial segment. RT-PCR (at semi-quantitative and single-cell levels) and immunocytochemistry showed that transient K+ currents result from the expression of Kv4.2 and Kv4.3 subunits. This is the first identification of subunits responsible for a transient K+ current in spinal motoneurons. The blockage of Kv4.2/Kv4.3 using a specific toxin modified the shape of the action potential demonstrating the involvement of these conductance channels in regulating spike repolarization and the discharge frequency. Among the other Kv α-subunits (Kv1.3, 1.4, 1.6, 2.1, 3.1 and 3.3), we showed that the Kv1.6 subunit was partly responsible for the sustained K+ current. In conclusion, this study has established the first correlation between the molecular nature of voltage-dependent Na+ and K+ channels expressed in embryonic rat motoneurons in culture and their electrophysiological characteristics in the period when excitability appears. PMID:12015418

  17. Enrichment of spinal cord cell cultures with motoneurons

    PubMed Central

    1978-01-01

    Spinal cord cell cultures contain several types of neurons. Two methods are described for enriching such cultures with motoneurons (defined here simply as cholinergic cells that are capable of innervating muscle). In the first method, 7-day embryonic chick spinal cord neurons were separated according to size by 1 g velocity sedimentation. It is assumed that cholinergic motoneurons are among the largest cells present at this stage. The spinal cords were dissociated vigorously so that 95-98% of the cells in the initial suspension were isolated from one another. Cells in leading fractions (large cell fractions: LCFs) contain about seven times as much choline acetyltransferase (CAT) activity per unit cytoplasm as do cells in trailing fractions (small cell fractions: SCFs). Muscle cultures seeded with LCFs develop 10-70 times as much CAT as cultures seeded with SCFs and six times as much CAT as cultures seeded with control (unfractionated) spinal cord cells. More than 20% of the large neurons in LCF-muscle cultures innervate nearby myotubes. In the second method, neurons were gently dissociated from 4-day embryonic spinal cords and maintained in vitro. This approach is based on earlier observations that cholinergic neurons are among the first cells to withdraw form the mitotic cycle in the developing chick embryo (Hamburger, V. 1948. J. Comp. Neurol. 88:221- 283; and Levi-Montalcini, R. 1950. J. Morphol. 86:253-283). 4-Day spinal cord-muscle cultures develop three times as much CAT as do 7-day spinal cord-muscle plates, prepared in the same (gentle) manner. More than 50% of the relatively large 4-day neurons innervate nearby myotubes. Thus, both methods are useful first steps toward the complete isolation of motoneurons. Both methods should facilitate study of the development of cholinergic neurons and of nerve-muscle synapse formation. PMID:566275

  18. Effects of background noise on the response of rat and cat motoneurones to excitatory current transients.

    PubMed Central

    Poliakov, A V; Powers, R K; Sawczuk, A; Binder, M D

    1996-01-01

    1. We studied the responses of rat hypoglossal motoneurones to excitatory current transients (ECTs) using a brainstem slice preparation. Steady, repetitive discharge at rates of 12-25 impulses s-1 was elicited from the motoneurones by injecting long (40 s) steps of constant current. Poisson trains of the ECTs were superimposed on these steps. The effects of additional synaptic noise was simulated by adding a zero-mean random process to the stimuli. 2. We measured the effects of the ECTs on motoneurone discharge probability by compiling peristimulus time histograms (PSTHs) between the times of occurrence of the ECTs and the motoneurone spikes. The ECTs produced modulation of motoneurone discharge similar to that produced by excitatory postsynaptic currents. 3. The addition of noise altered the pattern of the motoneurone response to the current transients: both the amplitude and the area of the PSTH peaks decreased as the power of the superimposed noise was increased. Noise tended to reduce the efficacy of the ECTs, particularly when the motoneurones were firing at lower frequencies. Although noise also increased the firing frequency of the motoneurones slightly, the effects of noise on ECT efficacy did not simply result from noise-induced changes in mean firing rate. 4. A modified version of the experimental protocol was performed in lumbar motoneurones of intact, pentobarbitone-anaesthetized cats. These recordings yielded results similar to those obtained in rat hypoglossal motoneurones in vitro. 5. Our results suggest that the presence of concurrent synaptic inputs reduces the efficacy of any one input. The implications of this change in efficacy and the possible underlying mechanisms are discussed. PMID:8866358

  19. Brain areas associated with force steadiness and intensity during isometric ankle dorsiflexion in men and women.

    PubMed

    Yoon, Tejin; Vanden Noven, Marnie L; Nielson, Kristy A; Hunter, Sandra K

    2014-10-01

    Although maintenance of steady contractions is required for many daily tasks, there is little understanding of brain areas that modulate lower limb force accuracy. Functional magnetic resonance imaging was used to determine brain areas associated with steadiness and force during static (isometric) lower limb target-matching contractions at low and high intensities. Fourteen young adults (6 men and 8 women; 27.1 ± 9.1 years) performed three sets of 16-s isometric contractions with the ankle dorsiflexor muscles at 10, 30, 50, and 70 % of maximal voluntary contraction (MVC). Percent signal changes (PSCs, %) of the blood oxygenation level-dependent response were extracted for each contraction using region of interest analysis. Mean PSC increased with contraction intensity in the contralateral primary motor area (M1), supplementary motor area, putamen, pallidum cingulate cortex, and ipsilateral cerebellum (p < 0.05). The amplitude of force fluctuations (standard deviation, SD) increased from 10 to 70 % MVC but relative to the mean force (coefficient of variation, CV %) was greatest at 10 % MVC. The CV of force was associated with PSC in the ipsilateral parietal lobule (r = -0.28), putamen (r = -0.29), insula (r = -0.33), and contralateral superior frontal gyrus (r = -0.33, p < 0.05). There were minimal sex differences in brain activation across the isometric motor tasks indicating men and women were similarly motivated and able to activate cortical motor centers during static tasks. Control of steady lower limb contractions involves cortical and subcortical motor areas in both men and women and provides insight into key areas for potential cortical plasticity with impaired or enhanced leg function.

  20. Implantable optical-electrode device for stimulation of spinal motoneurons

    NASA Astrophysics Data System (ADS)

    Matveev, M. V.; Erofeev, A. I.; Zakharova, O. A.; Pyatyshev, E. N.; Kazakin, A. N.; Vlasova, O. L.

    2016-08-01

    Recent years, optogenetic method of scientific research has proved its effectiveness in the nerve cell stimulation tasks. In our article we demonstrate an implanted device for the spinal optogenetic motoneurons activation. This work is carried out in the Laboratory of Molecular Neurodegeneration of the Peter the Great St. Petersburg Polytechnic University, together with Nano and Microsystem Technology Laboratory. The work of the developed device is based on the principle of combining fiber optic light stimulation of genetically modified cells with the microelectrode multichannel recording of neurons biopotentials. The paper presents a part of the electrode implant manufacturing technique, combined with the optical waveguide of ThorLabs (USA).

  1. Adaptation of cat motoneurons to sustained and intermittent extracellular activation.

    PubMed Central

    Spielmann, J M; Laouris, Y; Nordstrom, M A; Robinson, G A; Reinking, R M; Stuart, D G

    1993-01-01

    1. The main purpose of this study was to quantify the adaptation of spinal motoneurons to sustained and intermittent activation, using an extracellular route of stimulating current application to single test cells, in contrast to an intracellular route, as has been used previously. In addition, associations were tested between firing rate properties of the tested cells and other type (size)-related properties of these cells and their motor units. 2. Motoneurons supplying the medial gastrocnemius muscle of the deeply anaesthetized cat were stimulated for 240 s with microelectrodes which passed sustained extracellular current at 1.25 times the threshold for repetitive firing. Many cells were also tested following a rest period with intermittent 1 s current pulses (duration 600 ms) at the same relative stimulus strength. Cell discharge was assessed from the EMG of the motor unit innervated by the test neuron. The motoneurons and their motor units were assigned to four categories (i.e. types FF, FR, S and F; where F = FF + FR) based on conventional criteria. In all, twenty F (16 FF, 4 FR) and fourteen S cells were studied with sustained stimulation. Thirty of these cells (17 F, 13 S) and an additional two cells (1 F, 1 S) were studied with intermittent stimulation. 3. The mean threshold current required for sustained firing for a period of > or = 2 s was not significantly different for F and S cells. However, most of the other measured parameters of motoneuron firing differed significantly for these two cell groups. For example, at 1.25 times the threshold current for repetitive firing, the mean firing duration in response to 240 s of sustained activation was 123 +/- 88 s (+/- S.D.) for F cells vs. 233 +/- 19 s for S cells. These values were significantly longer than those from a comparable, previously reported study that employed intracellular stimulation. With intermittent stimulation, the firing durations of F and S cells were not significantly different from each

  2. Electrophysiological properties of neonatal rat motoneurones studied in vitro.

    PubMed Central

    Fulton, B P; Walton, K

    1986-01-01

    The electroresponsive properties of neonatal lumbar spinal motoneurones were studied using isolated, hemisected spinal cords from neonatal rats aged 3-12 days. The extracellular and intracellular responses to electrical stimulation of the ventral and dorsal root were studied as well as the intracellular response to current injection. Field potentials recorded in the lateral motor area following electrical stimulation of lumbar ventral roots had a triphasic positive-negative-positive wave form. The negative component did not return to the base line smoothly but exhibited a 'shoulder' where the negativity increased in duration. Following electrical stimulation of the dorsal root, presynaptic field potentials were recorded upon activation of the afferent axons as well as following synaptic activation of interneurones and motoneurones. The input resistances of neonatal motoneurones determined from the slope of current-voltage plots were high compared with the adult. The resistance decreased with age with a mean of 18.1 M omega for animals 3-5 days old, 8.8 M omega for animals 6-8 days old and 5.4 M omega for animals 9-11 days old. Values for the membrane time constant were similar to those in the adult with a mean of 4.5 ms. Action potentials elicited by ventral or dorsal root stimulation or by intracellular current injection were marked by a pronounced after-depolarization (a.d.p.) and an after-hyperpolarization (a.h.p.). The amplitude of the a.h.p. varied with that of the a.d.p. The amplitude of excitatory post-synaptic potentials (e.p.s.p.s) elicited by electrical stimulation of the dorsal root was affected by intracellular current injection. Two types of e.p.s.p.s were distinguished: those with a biphasic reversal (early phase first) and those in which the early phase was unaffected by inward current injection while the later phase was reversed. Unlike in the adult, the reversals could be achieved with low current levels and the amplitude of both types of e

  3. Haemophilic arthropathy of the ankle treated by total ankle replacement: a case series.

    PubMed

    Barg, A; Elsner, A; Hefti, D; Hintermann, B

    2010-07-01

    The standard treatment for end-stage osteoarthritis of the ankle joint in haemophilic patients has been fusion of the ankle joint. Total ankle replacement is still controversial as a treatment option. The objective of this prospective study was to evaluate the mid-term outcome in patients treated with total ankle replacement using an unconstrained three-component ankle implant. Ten haemophilic ankles in eight patients (mean age: 43.2 years, range 26.7-57.5) treated with total ankle replacement were followed up for a minimum of 2.7 years (mean: 5.6, range 2.7-7.6). The outcome was measured with clinical and radiological evaluations. There were no intra- or peri-operative complications. The AOFAS-hindfoot-score increased from 38 (range 8-57) preoperatively to 81 (range 69-95) postoperatively. All patients were satisfied with the results. Four patients became pain free; in the whole patient cohort pain level decreased from 7.1 (range 4-9) preoperatively to 0.8 (range 0-3) postoperatively. All categories of SF-36 score showed significant improvements in quality of life. In one patient, open ankle arthrolysis was performed because of painful arthrofibrosis. For patients with haemophilic osteoarthritis of the ankle joint, total ankle replacement is a valuable alternative treatment to ankle fusion.

  4. Assessment of acute foot and ankle sprains.

    PubMed

    Lynam, Louise

    2006-07-01

    Acute ankle and foot trauma is a regular emergency presentation and prompt strategic assessment skills are required to enable nurses to categorise and prioritise these injuries appropriately. This article provides background information on the anatomy and physiology of the lower limb to help nurses to identify various grades of ankle sprain as well as injuries that are limb threatening

  5. How to Care for a Sprained Ankle

    MedlinePlus

    ... in shape with good muscle balance, flexibility and strength in your soft tissues. Additional Resources How to Stretch Your Ankle After a Sprain How to Strengthen Your Ankle After a Sprain This material was codeveloped by the American Academy of Orthopaedic ...

  6. Whole-cell patch clamp recordings from rhythmically active motoneurons in the isolated spinal cord of the chick embryo.

    PubMed

    Sernagor, E; O'Donovan, M J

    1991-07-22

    Whole-cell patch clamp recordings were obtained during motor activity from electrically identified motoneurons within the spinal cord of the chick embryo maintained in vitro. Most recordings were performed on E11-E13 motoneurons although it was also possible to record from younger cells (E7-E9). Voltage clamp recordings were used to characterize the synaptic currents expressed in femoro-tibialis (extensor) motoneurons during motor activity. These motoneurons exhibited rhythmic excitatory currents with reversal potentials near 0 mV. This powerful technique enables high resolution recordings from identified motoneurons in situ and allows investigation of the membrane and synaptic mechanisms involved in the development of embryonic motility.

  7. Pharmacological characterization of the rhythmic synaptic drive onto lumbosacral motoneurons in the chick embryo spinal cord.

    PubMed

    Sernagor, E; Chub, N; Ritter, A; O'Donovan, M J

    1995-11-01

    The isolated spinal cord of the chick embryo generates episodes of rhythmic bursting in which sartorius (hip flexor) and femorotibialis (knee extensor) motoneurons exhibit characteristic patterns of activity. At the beginning of each cycle both sets of motoneurons discharge synchronously. Following this brief synchronous activation sartorius motoneurons stop firing at the time of peak femorotibialis activity, producing a period of alternation between the two sets of motoneurons. Intracellular recording from motoneurons has suggested that the pause is mediated by a synaptically induced shunt conductance. However, the pharmacological basis for this shunt and the nature of the excitatory drive to motoneurons is unknown. To address these questions we have investigated the pharmacology of the rhythmic, synaptic drive to lumbosacral motoneurons using local and bath application of several excitatory and inhibitory antagonists, and documenting their effects on motor output in E10-E12 chick embryos. Local application of bicuculline or picrotoxin over sartorius motoneurons abolished the pause in firing recorded from the sartorius muscle nerve. As a consequence, the pattern of sartorius and femorotibialis activity was similar and the motoneurons were coactive. The pause in sartorius firing was shortened following local application of the glycine antagonist strychnine the nicotinic, cholinergic antagonists mecamylamine, and dihydro-beta-erythroidine and several excitatory amino acid antagonists. Application of the GABA uptake inhibitor nipecotic acid depressed the slow potentials and discharge recorded from the sartorius muscle nerve. These findings suggest that the pause is determined primarily by synaptic inputs acting at motoneuron GABAA receptors with contributions from glycinergic, cholinergic, and glutamatergic inputs. The actions of locally applied GABA onto spinal neurons are consistent with these findings because the neurotransmitter depolarizes spinal neurons and

  8. Total ankle replacement - surgical treatment and rehabilitation.

    PubMed

    Prusinowska, Agnieszka; Krogulec, Zbigniew; Turski, Piotr; Przepiórski, Emil; Małdyk, Paweł; Księżopolska-Orłowska, Krystyna

    2015-01-01

    Functions of the ankle joint are closely connected with the gait and ability to maintain an upright position. Degenerative lesions of the joint directly contribute to postural disorders and greatly restrict propulsion of the foot, thus leading to abnormal gait. Development of total ankle replacement is connected with the use of the method as an efficient treatment of joint injuries and continuation of achievements in hip and knee surgery. The total ankle replacement technique was introduced as an alternative to arthrodesis, i.e. surgical fixation, which made it possible to preserve joint mobility and to improve gait. Total ankle replacement is indicated in post-traumatic degenerative joint disease and joint destruction secondary to rheumatoid arthritis. In this paper, total ankle replacement and various types of currently used endoprostheses are discussed. The authors also describe principles of early postoperative rehabilitation as well as rehabilitation in the outpatient setting.

  9. [Lateral instability of the upper ankle joint].

    PubMed

    Harrasser, N; Eichelberg, K; Pohlig, F; Waizy, H; Toepfer, A; von Eisenhart-Rothe, R

    2016-11-01

    Because of their frequency, ankle sprains are of major clinical and economic importance. The simple sprain with uneventful healing has to be distinguished from the potentially complicated sprain which is at risk of transition to chronic ankle instability. Conservative treatment is indicated for the acute, simple ankle sprain without accompanying injuries and also in cases of chronic instability. If conservative treatment fails, good results can be achieved by anatomic ligament reconstruction of the lateral ankle ligaments. Arthroscopic techniques offer the advantage of joint inspection and addressing intra-articular pathologies in combination with ligament repair. Accompanying pathologies must be adequately addressed during ligament repair to avoid persistent ankle discomfort. If syndesmotic insufficiency and tibiofibular instability are suspected, the objective should be early diagnosis with MRI and surgical repair.

  10. Tumours of the foot and ankle.

    PubMed

    Khan, Zeeshan; Hussain, Shakir; Carter, Simon R

    2015-09-01

    Sarcomas are rare tumours and particularly rarer in the foot and ankle region. The complex anatomy of the foot and ankle makes it unique and hence poses a challenge to the surgeon for limb salvage surgery. Other lesions found in the foot and ankle region are benign bone and soft tissue tumours, metastasis and infection. The purpose of this article is to discuss the relevance of the complex anatomy of the foot and ankle in relation to tumours, clinical features, their general management principles and further discussion about some of the more common bone and soft tissue lesions. Discussion of every single bone and soft tissue lesion in the foot and ankle region is beyond the scope of this article.

  11. Regional variations in the extent and timing of motoneuron cell death in the lumbosacral spinal cord of the chick embryo.

    PubMed

    Williams, C; Wohlenberg, G; O'Donovan, M J

    1987-08-01

    We have examined the distribution of motoneurons in different segments of the chick lumbosacral spinal cord before and after the period of motoneuron cell death. The extent of cell death was found to be greatest at the boundaries of the lumbosacral cord where over 60% of the motoneurons died and least in the central region where only 30% died. After cell death at stage 40 the number of motoneurons in each segment was linearly correlated with segment length, suggesting that growth of the segment and motoneuron numbers may be regulated by a common factor. The time of completion of motoneuron cell death exhibited a rostrocaudal gradient along the lumbar cord. Cell death was complete in the anterior segments by stage 35 but not until stage 38 in the caudal 4 segments. The regional variations in the extent and timing of motoneuron cell death suggest that the relative importance of the factors mediating cell death vary in different regions of the lumbar cord.

  12. Axotomized neonatal motoneurons overexpressing the bcl2 proto-oncogene retain functional electrophysiological properties.

    PubMed Central

    Alberi, S; Raggenbass, M; de Bilbao, F; Dubois-Dauphin, M

    1996-01-01

    Bcl2 overexpression prevents axotomy-induced neuronal death of neonatal facial motoneurons, as defined by morphological criteria. However, the functional properties of these surviving lesioned transgenic neurons are unknown. Using transgenic mice overexpressing the protein Bcl2, we have investigated the bioelectrical properties of transgenic facial motoneurons from 7 to 20 days after neonatal unilateral axotomy using brain-stem slices and whole cell patch-clamp recording. Nonaxotomized facial motoneurons from wild-type and transgenic mice had similar properties; they had an input resistance of 38 +/- 6 M omega and fired repetitively after injection of positive current pulses. When cells were voltage-clamped at or near their resting membrane potential, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-D-aspartic acid (NMDA), or vasopressin generated sustained inward currents. In transgenic axotomized mice, facial motoneurons could be found located ipsilaterally to the lesion; they had an input resistance of 150 +/- 30 M omega, indicating that they were smaller in size, fired repetitively, and were also responsive to AMPA, NMDA, and vasopressin. Morphological measurements achieved 1 week after the lesion have shown that application of brain-derived neurotrophic factor prevented the reduction in size of axotomized transgenic motoneurons. These data indicate that Bcl2 not only prevents morphological apoptotic death of axotomized neonatal transgenic motoneurons but also permits motoneurons to conserve functional electrophysiological properties. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:8633001

  13. Noradrenergic Modulation of Intrinsic and Synaptic Properties of Lumbar Motoneurons in the Neonatal Rat Spinal Cord

    PubMed Central

    Tartas, Maylis; Morin, France; Barrière, Grégory; Goillandeau, Michel; Lacaille, Jean-Claude; Cazalets, Jean-René; Bertrand, Sandrine S.

    2009-01-01

    Although it is known that noradrenaline (NA) powerfully controls spinal motor networks, few data are available regarding the noradrenergic (NAergic) modulation of intrinsic and synaptic properties of neurons in motor networks. Our work explores the cellular basis of NAergic modulation in the rat motor spinal cord. We first show that lumbar motoneurons express the three classes of adrenergic receptors at birth. Using patch-clamp recordings in the newborn rat spinal cord preparation, we characterized the effects of NA and of specific agonists of the three classes of adrenoreceptors on motoneuron membrane properties. NA increases the motoneuron excitability partly via the inhibition of a KIR like current. Methoxamine (α1), clonidine (α2) and isoproterenol (β) differentially modulate the motoneuron membrane potential but also increase motoneuron excitability, these effects being respectively inhibited by the antagonists prazosin (α1), yohimbine (α2) and propranolol (β). We show that the glutamatergic synaptic drive arising from the T13-L2 network is enhanced in motoneurons by NA, methoxamine and isoproterenol. On the other hand, NA, isoproterenol and clonidine inhibit both the frequency and amplitude of miniature glutamatergic EPSCs while methoxamine increases their frequency. The T13-L2 synaptic drive is thereby differentially modulated from the other glutamatergic synapses converging onto motoneurons and enhanced by presynaptic α1 and β receptor activation. Our data thus show that the NAergic system exerts a powerful and complex neuromodulation of lumbar motor networks in the neonatal rat spinal cord. PMID:20300468

  14. Neuronal pathways from foot pad afferents to hindlimb motoneurons in the low spinalized cats.

    PubMed

    Wada, N; Kanda, Y; Takayama, R

    1998-07-01

    Experiments were performed on 16 adult spinalized (L2) cats. Postsynaptic potentials (PSPs) produced by electrical stimulation of afferent nerves innervating foot pads were recorded from hindlimb motoneurons innervating the following hindlimb muscles: the posterior biceps and semitendinosus (PBSt), anterior biceps and semimembranosus (ABSm), lateral gastrocnemius and soleus (LGS), medial gastrocnemius (MG), plantaris (P1), tibialis anterior (TA), popliteus (Pop), flexor digitorum longus and flexor hallucis longus (FDHL) and peroneus longus (Per.l). The rate of occurrence of different types of PSPs (EPSPs, IPSPs and mixed PSPs), the size of the PSPs and their central latencies were analyzed for each group of motoneurons to identify the neural pathways from the afferents innervating foot pads to hindlimb motoneurons. The rates of occurrence of different types of PSPs did not depend on the foot pad stimulated in PBSt, ABSm and LGS motoneurons, but for other groups of motoneurons their rates of occurrence depended on the foot pad stimulated. It was often noted that the size of PSPs in the same motoneurons differed according to the foot pad stimulated. Measurements of the central latencies of the PSPs indicated that the shortest neural pathways for EPSPs and IPSPs were disynaptic (central latencies < 1.8 ms). The functional role of neuronal pathways from afferent nerves innervating foot pads to hindlimb motoneurons could be to maintain stability of the foot during different postural and motor activities.

  15. Segmental differences in firing properties and potassium currents in Drosophila larval motoneurons

    PubMed Central

    Srinivasan, Subhashini; Lance, Kimberley

    2012-01-01

    Potassium currents play key roles in regulating motoneuron activity, including functional specializations that are important for locomotion. The thoracic and abdominal segments in the Drosophila larval ganglion have repeated arrays of motoneurons that innervate body-wall muscles used for peristaltic movements during crawling. Although abdominal motoneurons and their muscle targets have been studied in detail, owing, in part, to their involvement in locomotion, little is known about the cellular properties of motoneurons in thoracic segments. The goal of this study was to compare firing properties among thoracic motoneurons and the potassium currents that influence them. Whole-cell, patch-clamp recordings performed from motoneurons in two thoracic and one abdominal segment revealed both transient and sustained voltage-activated K+ currents, each with Ca++-sensitive and Ca++-insensitive [A-type, voltage-dependent transient K+ current (IAv)] components. Segmental differences in the expression of voltage-activated K+ currents were observed. In addition, we demonstrate that Shal contributes to IAv currents in the motoneurons of the first thoracic segment. PMID:22157123

  16. Childhood development of common drive to a human leg muscle during ankle dorsiflexion and gait.

    PubMed

    Petersen, Tue Hvass; Kliim-Due, Mette; Farmer, Simon F; Nielsen, Jens Bo

    2010-11-15

    Corticospinal drive has been shown to contribute significantly to the control of walking in adult human subjects. It is unknown to what extent functional change in this drive is important for maturation of gait in children. In adults, populations of motor units within a muscle show synchronized discharges during walking with pronounced coherence in the 15-50 Hz frequency band. This coherence has been shown to depend on cortical drive. Here, we investigated how this coherence changes with development. Forty-four healthy children aged 4-15 years participated in the study. Electromyographic activity (EMG) was recorded from pairs of electrodes placed over the right tibialis anterior (TA) muscle during static dorsiflexion and during walking on a treadmill (speed from 1.8 to 4.8 km h(-1)). A significant increase of coherence with increasing age was found in the 30-45 Hz frequency band (gamma) during walking and during static ankle dorsiflexion. A significant correlation with age was also found in the 15-25 Hz frequency band (beta) during static foot dorsiflexion. χ(2) analysis of differences of coherence between different age groups of children (4-6, 7-9, 10-12 and 13-15 years of age) revealed a significantly lower coherence in the gamma band for recordings during walking in children aged 4-6 years as compared to older children. Recordings during static dorsiflexion revealed significant differences in both the beta and gamma bands for children in the 4-6 and 7-9 years age groups as compared to the older age groups. A significant age-related decrease in step-to-step variability of toe position during the swing phase of walking was observed. This reduction in the step-to-step variability of gait was correlated with increased gamma band coherence during walking. We argue that this may reflect an increased ability to precisely control the ankle joint position with age, which may be contingent on maturation of corticospinal control of the foot dorsiflexor muscles.

  17. Reliability and smallest real difference of the ankle lunge test post ankle fracture.

    PubMed

    Simondson, David; Brock, Kim; Cotton, Susan

    2012-02-01

    This study aimed to determine the reliability and the smallest real difference of the Ankle Lunge test in an ankle fracture patient population. In the post immobilisation stage of ankle fracture, ankle dorsiflexion is an important measure of progress and outcome. The Ankle Lunge test measures weight bearing dorsiflexion, resulting in negative scores (knee to wall distance) and positive scores (toe to wall distance), for which the latter has proven reliability in normal subjects only. A consecutive sample of ankle fracture patients with permission to commence weight bearing, were recruited to the study. Three measurements of the Ankle Lunge Test were performed each by two raters, one senior and one junior physiotherapist. These occurred prior to therapy sessions in the second week after plaster removal. A standardised testing station was utilised and allowed for both knee to wall distance and toe to wall distance measurement. Data was collected from 10 individuals with ankle fracture, with an average age of 36 years (SD 14.8). Seventy seven percent of observations were negative. Intra and inter-rater reliability yielded intra class correlations at or above 0.97, p < .001. There was a significant systematic bias towards improved scores during repeated measurement for one rater (p = .01). The smallest real difference was calculated as 13.8mm. The Ankle Lunge test is a practical and reliable tool for measuring weightbearing dorsiflexion post ankle fracture.

  18. Neuroprotective effects of NGF, BDNF, NT-3 and GDNF on axotomized extraocular motoneurons in neonatal rats.

    PubMed

    Morcuende, S; Muñoz-Hernández, R; Benítez-Temiño, B; Pastor, A M; de la Cruz, R R

    2013-10-10

    Neurotrophic factors delivered from target muscles are essential for motoneuronal survival, mainly during development and early postnatal maturation. It has been shown that the disconnection between motoneurons and their innervated muscle by means of axotomy produces a vast neuronal death in neonatal animals. In the present work, we have evaluated the effects of different neurotrophic factors on motoneuronal survival after neonatal axotomy, using as a model the motoneurons innervating the extraocular eye muscles. With this purpose, neonatal rats were monocularly enucleated at the day of birth (postnatal day 0) and different neurotrophic treatments (NGF, BDNF, NT-3, GDNF and the mixture of BDNF+GDNF) were applied intraorbitally by means of a Gelfoam implant (a single dose of 5 μg of each factor). We first demonstrated that extraocular eye muscles of neonatal rats expressed these neurotrophic factors and therefore constituted a natural source of retrograde delivery for their innervating motoneurons. By histological and immunocytochemical methods we determined that all treatments significantly rescued extraocular motoneurons from axotomy-induced cell death. For the dose used, NGF and GDNF were the most potent survival factors for these motoneurons, followed by BDNF and lastly by NT-3. The simultaneous administration of BDNF and GDNF did not increase the survival-promoting effects above those obtained by GDNF alone. Interestingly, the rescue effects of all neurotrophic treatments persisted even 30 days after lesion. The administration of these neurotrophic factors, with the exception of NT-3, also prevented the loss of the cholinergic phenotype observed by 10 days after axotomy. At the dosage applied, NGF and GDNF were revealed again as the most effective neuroprotective agents against the axotomy-induced decrease in ChAT. Two remarkable findings highlighted in the present work that contrasted with other motoneuronal types after neonatal axotomy: first, the extremely

  19. How to Stretch Your Ankle After a Sprain

    MedlinePlus

    ... ankle, which orthopaedic foot and ankle specialists call proprioception. Consider these home exercises when recuperating from an ankle sprain. Perform them twice per day. While seated, bring your ankle and foot all the way up as much as you can. Do this slowly, ...

  20. Resistance of extraocular motoneuron terminals to effects of amyotrophic lateral sclerosis sera

    NASA Technical Reports Server (NTRS)

    Mosier, D. R.; Siklos, L.; Appel, S. H.

    2000-01-01

    In sporadic ALS (s-ALS), axon terminals contain increased intracellular calcium. Passively transferred sera from patients with s-ALS increase intracellular calcium in spinal motoneuron terminals in vivo and enhance spontaneous transmitter release, a calcium-dependent process. In this study, passive transfer of s-ALS sera increased spontaneous release from spinal but not extraocular motoneuron terminals, suggesting that the resistance to physiologic abnormalities induced by s-ALS sera in mice parallels the resistance of extraocular motoneurons to dysfunction and degeneration in ALS.

  1. Revision of the aseptic and septic total ankle replacement.

    PubMed

    Espinosa, Norman; Wirth, Stephan Hermann

    2013-04-01

    Total ankle replacement has become a popular treatment of symptomatic end-stage ankle osteoarthritis. Contemporary total ankle replacement systems provide more anatomic and biomechanically sound function. However, longevity is still limited and long-term results of modern total ankle replacement designs are not available. In the case of failure, conversion into arthrodesis has remained the treatment of choice but at the cost of hindfoot function and potential degeneration of the adjacent joints. Thus, revision total ankle replacement by exchange of the prosthetic components represents an attractive solution. This article focuses on revision total ankle replacement and conversion to ankle arthrodesis.

  2. Group I projections from intrinsic foot muscles to motoneurones of leg and thigh muscles in humans

    PubMed Central

    Marque, Philippe; Nicolas, Guillaume; Marchand-Pauvert, Véronique; Gautier, Julien; Simonetta-Moreau, Marion; Pierrot-Deseilligny, Emmanuel

    2001-01-01

    Group I projections from intrinsic plantar muscles to motoneurones (MNs) of human leg and thigh muscles were investigated. Changes in firing probability of single motor units (MUs) in the tibialis anterior (TA), peroneus brevis (Per brev), soleus (Sol), gastrocnemius medialis (GM), vastus lateralis (VL), semitendinosus (ST) and biceps (Bi) were studied after electrical stimuli applied to: (i) the tibial nerve (TN) at ankle level, (ii) the corresponding homonymous nerve, and (iii) the skin of the heel, to mimic the TN-induced cutaneous sensation.Homonymous facilitation, attributable to monosynaptic Ia excitation, was found in all the sampled units. Early heteronymous excitation elicited by TN stimulation was found in many MUs. Later effects (3–5 ms central delay) were bigger and more frequently observed: excitation in most TA and Per brev MUs, and inhibition in most Sol, GM and Bi MUs and in many ST and VL MUs. The low threshold (∼0.5–0.6 × motor threshold) and the inability of a pure cutaneous stimulation to reproduce these effects (except the late excitation in TA MUs) indicate that they were due to stimulation of group I muscle afferents.The early excitation was accepted to be monosynaptic when its central delay differed from that of the homonymous Ia excitation by less than 0.5 ms. Such a significant TN-induced monosynaptic Ia excitation was found in MUs belonging to all leg and thigh motor nuclei tested. Although its mean strength was relatively weak, it is argued that these monosynaptic connections might affect already depolarized MNs.The late excitation found in TA and Per brev MUs is argued to be mediated through interneurones located rostral to MNs.The late suppression, found in most Sol, GM and Bi MUs, and in many ST and VL MUs, was the dominant effect. It was accompanied by an inhibition of the Sol and quadriceps H reflexes at rest, and therefore reflects an inhibition directed to MNs. Its long latency is argued to reflect transmission by

  3. Ankle fractures in elderly patients.

    PubMed

    Giannini, Sandro; Chiarello, Eugenio; Persiani, Valentina; Luciani, Deianira; Cadossi, Matteo; Tedesco, Giuseppe

    2013-10-01

    The incidence of ankle fractures (AFs) in the elderly is rising due to the increase in life expectancy. Rather than directly related to osteoporosis, AFs are a predictor of osteoporotic fractures in other sites. In women AFs are associated with weight and BMI. AFs are difficult to categorize; therapeutic options are non-operative treatment with plaster casts or surgical treatment with Kirschner's wires, plates and screws. The choice of treatment should be based not only on the fracture type but also on the local and general comorbidity of the patient. Considering the new evidence that postmenopausal women with AFs have disrupted microarchitecture and decreased stiffness of the bone compared with women with no fracture history, in our opinion low-trauma AFs should be considered in a similar way to the other classical osteoporotic fractures.

  4. Conversion of ankle autofusion to total ankle replacement using the Salto XT revision prosthesis.

    PubMed

    Williamson, Emilie R C; Demetracopoulos, Constantine A; Ellis, Scott J

    2016-09-01

    Few reports in the literature have described the conversion of a surgically fused ankle to a total ankle replacement. The takedown of an autofusion and conversion to a prosthesis has not been described. We report the case of a patient with severe rheumatoid arthritis with an ankle autofusion fixed in equinus and severe talonavicular arthritis that was converted to ankle replacement using the Salto XT revision system. We describe the reasons why the decision was made to perform total ankle arthroplasty while concomitantly fusing the talonavicular joint, and discuss the rationale of the various surgical treatment options considered. We describe the clinical and radiographic outcomes achieved in this case. At 12 months post-operatively the patient reported significant reduction of pain, increased FAOS scores and had increased ankle range of motion.

  5. Position versus force control: using the 2-DOF robotic ankle trainer to assess ankle's motor control.

    PubMed

    Farjadian, Amir B; Nabian, Mohsen; Hartman, Amber; Corsino, Johnathan; Mavroidis, Constantinos; Holden, Maureen K

    2014-01-01

    An estimated of 2,000,000 acute ankle sprains occur annually in the United States. Furthermore, ankle disabilities are caused by neurological impairments such as traumatic brain injury, cerebral palsy and stroke. The virtually interfaced robotic ankle and balance trainer (vi-RABT) was introduced as a cost-effective platform-based rehabilitation robot to improve overall ankle/balance strength, mobility and control. The system is equipped with 2 degrees of freedom (2-DOF) controlled actuation along with complete means of angle and torque measurement mechanisms. Vi-RABT was used to assess ankle strength, flexibility and motor control in healthy human subjects, while playing interactive virtual reality games on the screen. The results suggest that in the task with 2-DOF, subjects have better control over ankle's position vs. force.

  6. Biomechanics of the ankle joint and clinical outcomes of total ankle replacement.

    PubMed

    Michael, Junitha M; Golshani, Ashkahn; Gargac, Shawn; Goswami, Tarun

    2008-10-01

    Until the 1970s ankle arthrodesis was considered to be the "gold-standard" to treat arthritis. But the low fusion rate of ankle arthrodeses along with the inability to achieve normal range of motion led to the growing interest in the development of total ankle replacements. Though the short-term outcomes were good, their long-term outcomes were not as promising. To date, most models do not exactly mimic the anatomical functionality of a natural ankle joint. Therefore, research is being conducted worldwide to either enhance the existing models or develop new models while understanding the intricacies of the joint more precisely. This paper reviews the anatomical and biomechanical aspects of the ankle joint. Also, the evolution and comparison of clinical outcomes of various total ankle replacements are presented.

  7. Foot and ankle injuries in theatrical dancers.

    PubMed

    Hardaker, W T; Margello, S; Goldner, J L

    1985-10-01

    The theatrical dancer is a unique combination of athlete and artist. The physical demands of dance class, rehearsal, and performance can lead to injury, particularly to the foot and ankle. Ankle sprains are the most common acute injury. Chronic injuries predominate and relate primarily to the repeated impact loading of the foot and ankle on the dance floor. Contributing factors include anatomic variation, improper technique, and fatigue. Early and aggressive conservative management is usually successful and surgery is rarely indicated. Orthotics play a limited but potentially useful role in treatment. Following treatment, a structured rehabilitation program is fundamental to the successful return to dance.

  8. The Salto Talaris XT Revision Ankle Prosthesis.

    PubMed

    Roukis, Thomas S

    2015-10-01

    The Salto Talaris XT Revision Ankle Prosthesis is an anatomically designed fixed-bearing prosthesis available in the United States based on the design of previous Salto systems. The Salto Talaris XT Revision Ankle Prosthesis design optimizes surface area, cortical contact, and ultrahigh-molecular-weight polyethylene conformity. Two tibial component designs, both with the same base plate dimensions, are available, the standard conical fixation plug affixed to a short keel and a long-stemmed version. The author presents an overview of the Salto Talaris XT Revision Ankle Prosthesis surgical technique and pearls for successful application.

  9. All-inside, anatomical lateral ankle stabilization for revision and complex primary lateral ankle stabilization: a technique guide.

    PubMed

    Prissel, Mark A; Roukis, Thomas S

    2014-12-01

    Lateral ankle instability is a common mechanical problem that often requires surgical management when conservative efforts fail. Historically, myriad open surgical approaches have been proposed. Recently, consideration for arthroscopic management of lateral ankle instability has become popular, with promising results. Unfortunately, recurrent inversion ankle injury following lateral ankle stabilization can occur and require revision surgery. To date, arthroscopic management for revision lateral ankle stabilization has not been described. We present a novel arthroscopic technique combining an arthroscopic lateral ankle stabilization kit with a suture anchor ligament augmentation system for revision as well as complex primary lateral ankle stabilization.

  10. Primary ankle arthrodesis for neglected open Weber B ankle fracture dislocation.

    PubMed

    Thomason, Katherine; Ramesh, Ashwanth; McGoldrick, Niall; Cove, Richard; Walsh, James C; Stephens, Michael M

    2014-01-01

    Primary ankle arthrodesis used to treat a neglected open ankle fracture dislocation is a unique decision. A 63-year-old man presented to the emergency department with a 5-day-old open fracture dislocation of his right ankle. After thorough soft tissue debridement, primary arthrodesis of the tibiotalar joint was performed using initial Kirschner wire fixation and an external fixator. Definitive soft tissue coverage was later achieved using a latissimus dorsi free flap. The fusion was consolidated to salvage the limb from amputation. The use of primary arthrodesis to treat a compound ankle fracture dislocation has not been previously described.

  11. Transfibular ankle arthrodesis: A novel method for ankle fusion – A short term retrospective study

    PubMed Central

    Balaji, S Muthukumar; Selvaraj, V; Devadoss, Sathish; Devadoss, Annamalai

    2017-01-01

    Background: Ankle arthrodesis has long been the traditional operative treatment for posttraumatic arthritis, rheumatoid arthritis, infection, neuromuscular conditions, and salvage of failed ankle arthroplasty. It remains the treatment of choice for patients in whom heavy and prolonged activity is anticipated. We present our short term followup study of functional outcome of patients who underwent transfibular ankle arthrodesis for arthritis of ankle due to various indications. Materials and Methods: 29 transfibular ankle arthrodesis in 29 patients performed between April 2009 and April 2014 were included in this study. The mean age was 50 years (range 22-75 years). The outcome analysis with a minimum of 1-year postoperative followup were included. All the patients were assessed with the American Orthopaedic Foot and Ankle Society (AOFAS) Hindfoot scale. Results: All cases of ankle fusions (100%) progressed to solid union in a mean postoperative duration of 3.8 months (range 3–6 months). All patients had sound arthrodesis. The mean followup period was 32.52 months (standard deviation ± 10.34). The mean AOFAS score was 74 (pain score = 32, functional score = 42). We found that twenty patients (68.96%) out of 29, had excellent results, 7 (24.13%) had good, and 2 (6.89%) showed fair results. Conclusion: Transfibular ankle arthrodesis is a simple and effective procedure for ankle arthritis. It achieves a high rate of union and good functional outcome on midterm followup. PMID:28216754

  12. RNA content in spinal cord motoneurons during hypokinesia

    NASA Technical Reports Server (NTRS)

    Gorbunova, A. V.

    1980-01-01

    The effect of a diminished motor activity of rats upon the ribonucleic and (RNA) content in a single isolated motoneuron of frontal of their spinal cord was studied. Within a 1 to 30 day exposure of rats to the hypokinetic conditions, RNA content was found to decrease on the 1st, 3rd, and 5th day and to return to the initial level by the 7th day. No changes in RNA content were observed during the subsequent stages of the xperiments. The volume of the nerve cells declined on the 3rd and 5th day, whereas RNA concentration reduced on the 1st, 3rd, 5th, and 30th day.

  13. Noncholinergic excitatory actions of motoneurons in the neonatal mammalian spinal cord

    PubMed Central

    Mentis, George Z.; Alvarez, Francisco J.; Bonnot, Agnes; Richards, Dannette S.; Gonzalez-Forero, David; Zerda, Ricardo; O'Donovan, Michael J.

    2005-01-01

    Mammalian spinal motoneurons are considered to be output elements of the spinal cord that generate exclusively cholinergic actions on Renshaw cells, their intraspinal synaptic targets. Here, we show that antidromic stimulation of motor axons evokes depolarizing monosynaptic potentials in Renshaw cells that are depressed, but not abolished, by cholinergic antagonists. This residual potential was abolished by 2-amino-5-phosphonovaleric acid and 6-cyano-7-nitroquinoxaline-2,3-dione. In the presence of cholinergic antagonists, motor axon stimulation triggered locomotor-like activity that was blocked by 2-amino-5-phosphonovaleric acid. Some cholinergic motoneuronal terminals on both Renshaw cells and motoneurons were enriched in glutamate, but none expressed vesicular glutamate transporters. Our results raise the possibility that motoneurons release an excitatory amino acid in addition to acetylcholine and that they may be more directly involved in the genesis of mammalian locomotion than previously believed. PMID:15883359

  14. Noncholinergic excitatory actions of motoneurons in the neonatal mammalian spinal cord.

    PubMed

    Mentis, George Z; Alvarez, Francisco J; Bonnot, Agnes; Richards, Dannette S; Gonzalez-Forero, David; Zerda, Ricardo; O'Donovan, Michael J

    2005-05-17

    Mammalian spinal motoneurons are considered to be output elements of the spinal cord that generate exclusively cholinergic actions on Renshaw cells, their intraspinal synaptic targets. Here, we show that antidromic stimulation of motor axons evokes depolarizing monosynaptic potentials in Renshaw cells that are depressed, but not abolished, by cholinergic antagonists. This residual potential was abolished by 2-amino-5-phosphonovaleric acid and 6-cyano-7-nitroquinoxaline-2,3-dione. In the presence of cholinergic antagonists, motor axon stimulation triggered locomotor-like activity that was blocked by 2-amino-5-phosphonovaleric acid. Some cholinergic motoneuronal terminals on both Renshaw cells and motoneurons were enriched in glutamate, but none expressed vesicular glutamate transporters. Our results raise the possibility that motoneurons release an excitatory amino acid in addition to acetylcholine and that they may be more directly involved in the genesis of mammalian locomotion than previously believed.

  15. Somatic and axonal LIGHT signaling elicit degenerative and regenerative responses in motoneurons, respectively

    PubMed Central

    Otsmane, Belkacem; Moumen, Anice; Aebischer, Julianne; Coque, Emmanuelle; Sar, Chamroeun; Sunyach, Claire; Salsac, Céline; Valmier, Jean; Salinas, Sara; Bowerman, Melissa; Raoul, Cédric

    2014-01-01

    A receptor–ligand interaction can evoke a broad range of biological activities in different cell types depending on receptor identity and cell type-specific post-receptor signaling intermediates. Here, we show that the TNF family member LIGHT, known to act as a death-triggering factor in motoneurons through LT-βR, can also promote axon outgrowth and branching in motoneurons through the same receptor. LIGHT-induced axonal elongation and branching require ERK and caspase-9 pathways. This distinct response involves a compartment-specific activation of LIGHT signals, with somatic activation-inducing death, while axonal stimulation promotes axon elongation and branching in motoneurons. Following peripheral nerve damage, LIGHT increases at the lesion site through expression by invading B lymphocytes, and genetic deletion of Light significantly delays functional recovery. We propose that a central and peripheral activation of the LIGHT pathway elicits different functional responses in motoneurons. PMID:24668263

  16. Lichen simplex chronicus on the ankle (image)

    MedlinePlus

    Lichen simplex chronicus on the ankle: Lichen simplex chronicus is also known as neurodermatitis. A minor itch may encourage scratching which increases the irritation, leading to more scratching. This ...

  17. Foot and ankle injuries in dance.

    PubMed

    Kadel, Nancy J

    2006-11-01

    Although dancers develop overuse injuries common in other athletes, they are also susceptible to unique injuries. This article reviews common foot and ankle problems seen in dancers and provides some basic diagnosis and treatment strategies.

  18. Autologous split peroneus longus lateral ankle stabilization.

    PubMed

    Budny, Adam M; Schuberth, John M

    2012-01-01

    Lateral ankle instability is a common clinical entity, and a variety of surgical procedures are available for stabilization after conservative management fails. Herein the authors reviewed outcomes after performing autologous split peroneus longus lateral ankle stabilization, using a previously described surgical technique to anatomically recreate the anterior talofibular and calcaneofibular ligaments. Twenty-five consecutive patients from 2 surgeons' practices underwent reconstruction between March 2007 and January 2011 with a minimum follow-up of 12 (range 12 to 51) months (mean 29.5 months). Follow-up interviews demonstrated 92.0% good or excellent outcomes with only 8.0% rating the outcome as fair and none as poor; 92.0% had no recurrent sprains or difficulty going up or down hills; 88.0% related no difficulty with uneven ground. The authors conclude that the autologous split peroneus longus lateral ankle stabilization results in a stable ankle with a low rate of complications and high patient satisfaction.

  19. Arthroscopic Taloplasty for an Anterolateral Snapping Ankle.

    PubMed

    Lui, Tun Hing

    2016-12-01

    Anterior ankle snapping syndrome is rare. Snapping of the extensor digitorum longus due to attenuated inferior extensor retinaculum and snapping due to hypertrophied or low-lying peroneal tertius muscle have been reported. We reported a new mechanism of anterolateral snapping due to a hypertrophied talar head. Anterolateral snapping ankle can be revealed by active dorsiflexion and plantarflexion of the ankle with the foot inverted. Foot inversion will tension the inferior extensor retinaculum and uncover the dorsolateral prominence of the talar head. The dorsolateral prominence of the talar head will snap over the proximal edge of the inferior extensor retinaculum. This technical note reports the technique of arthroscopic contouring of the talar head via extra-articular ankle arthroscopy. We named this technique arthroscopic taloplasty.

  20. A quantitative ultrastructural comparison of alpha and gamma motoneurons in the thoracic region of the spinal cord of the adult cat.

    PubMed

    Johnson, I P

    1986-08-01

    The cell bodies of motoneurons supplying both the levator costae and external intercostal muscles were identified after retrograde labelling with horseradish peroxidase. A quantitative ultrastructural comparison of cell bodies of large (greater than 40 microns) and small (less than 30 microns) diameter revealed that the intracellular appearance of large and small motoneurons was similar. However, small motoneurons had less than half the synaptic terminal frequency or cover of large motoneurons. Furthermore, only synapses of the S- and F-type were seen on small motoneurons, while S- T- F- and C-type terminals were consistently seen on large motoneurons. The variation between individual small motoneurons for various aspects of their synaptic features was more than twice that found for large motoneurons. No correlation between small motoneuronal ultrastructure and cell body diameter was found, although scatter diagrams of synaptic terminal cover against cell body size indicated the presence of two groups of small motoneurons: one with relatively high values for synaptic cover and the other with relatively low values. On the basis of the similarity of their cell body diameters to those of electrophysiologically identified alpha and gamma motoneurons, it is concluded that the large and small motoneurons examined in the present study are alpha and gamma motoneurons respectively. The synaptic difference found between alpha and gamma motoneurons is discussed in relation to both their different functional properties and the different natures of their respective peripheral targets.

  1. Marked and variable inhibition by chemical fixation of cytochrome oxidase and succinate dehydrogenase in single motoneurons

    NASA Technical Reports Server (NTRS)

    Chalmers, G. R.; Edgerton, V. R.

    1989-01-01

    The effect of tissue fixation on succinate dehydrogenase and cytochrome oxidase activity in single motoneurons of the rat was demonstrated using a computer image processing system. Inhibition of enzyme activity by chemical fixation was variable, with some motoneurons being affected more than others. It was concluded that quantification of enzymatic activity in chemically fixed tissue provides an imprecise estimate of enzyme activities found in fresh-frozen tissues.

  2. Motoneuron axon pathfinding errors in zebrafish: Differential effects related to concentration and timing of nicotine exposure

    SciTech Connect

    Menelaou, Evdokia; Paul, Latoya T.; Perera, Surangi N.; Svoboda, Kurt R.

    2015-04-01

    Nicotine exposure during embryonic stages of development can affect many neurodevelopmental processes. In the developing zebrafish, exposure to nicotine was reported to cause axonal pathfinding errors in the later born secondary motoneurons (SMNs). These alterations in SMN axon morphology coincided with muscle degeneration at high nicotine concentrations (15–30 μM). Previous work showed that the paralytic mutant zebrafish known as sofa potato exhibited nicotine-induced effects onto SMN axons at these high concentrations but in the absence of any muscle deficits, indicating that pathfinding errors could occur independent of muscle effects. In this study, we used varying concentrations of nicotine at different developmental windows of exposure to specifically isolate its effects onto subpopulations of motoneuron axons. We found that nicotine exposure can affect SMN axon morphology in a dose-dependent manner. At low concentrations of nicotine, SMN axons exhibited pathfinding errors, in the absence of any nicotine-induced muscle abnormalities. Moreover, the nicotine exposure paradigms used affected the 3 subpopulations of SMN axons differently, but the dorsal projecting SMN axons were primarily affected. We then identified morphologically distinct pathfinding errors that best described the nicotine-induced effects on dorsal projecting SMN axons. To test whether SMN pathfinding was potentially influenced by alterations in the early born primary motoneuron (PMN), we performed dual labeling studies, where both PMN and SMN axons were simultaneously labeled with antibodies. We show that only a subset of the SMN axon pathfinding errors coincided with abnormal PMN axonal targeting in nicotine-exposed zebrafish. We conclude that nicotine exposure can exert differential effects depending on the levels of nicotine and developmental exposure window. - Highlights: • Embryonic nicotine exposure can specifically affect secondary motoneuron axons in a dose-dependent manner.

  3. Functional recovery after cervical spinal cord injury: Role of neurotrophin and glutamatergic signaling in phrenic motoneurons.

    PubMed

    Gill, Luther C; Gransee, Heather M; Sieck, Gary C; Mantilla, Carlos B

    2016-06-01

    Cervical spinal cord injury (SCI) interrupts descending neural drive to phrenic motoneurons causing diaphragm muscle (DIAm) paralysis. Recent studies using a well-established model of SCI, unilateral spinal hemisection of the C2 segment of the cervical spinal cord (SH), provide novel information regarding the molecular and cellular mechanisms of functional recovery after SCI. Over time post-SH, gradual recovery of rhythmic ipsilateral DIAm activity occurs. Recovery of ipsilateral DIAm electromyogram (EMG) activity following SH is enhanced by increasing brain-derived neurotrophic factor (BDNF) in the region of the phrenic motoneuron pool. Delivery of exogenous BDNF either via intrathecal infusion or via mesenchymal stem cells engineered to release BDNF similarly enhance recovery. Conversely, recovery after SH is blunted by quenching endogenous BDNF with the fusion-protein TrkB-Fc in the region of the phrenic motoneuron pool or by selective inhibition of TrkB kinase activity using a chemical-genetic approach in TrkB(F616A) mice. Furthermore, the importance of BDNF signaling via TrkB receptors at phrenic motoneurons is highlighted by the blunting of recovery by siRNA-mediated downregulation of TrkB receptor expression in phrenic motoneurons and by the enhancement of recovery evident following virally-induced increases in TrkB expression specifically in phrenic motoneurons. BDNF/TrkB signaling regulates synaptic plasticity in various neuronal systems, including glutamatergic pathways. Glutamatergic neurotransmission constitutes the main inspiratory-related, excitatory drive to motoneurons, and following SH, spontaneous neuroplasticity is associated with increased expression of ionotropic N-methyl-d-aspartate (NMDA) receptors in phrenic motoneurons. Evidence for the role of BDNF/TrkB and glutamatergic signaling in recovery of DIAm activity following cervical SCI is reviewed.

  4. Complex ankle arthrodesis: Review of the literature

    PubMed Central

    Rabinovich, Remy V; Haleem, Amgad M; Rozbruch, S Robert

    2015-01-01

    Complex ankle arthrodesis is defined as an ankle fusion that is at high risk of delayed and nonunion secondary to patient comorbidities and/or local ankle/hindfoot factors. Risk factors that contribute to defining this group of patients can be divided into systemic factors and local factors pertaining to co-existing ankle or hindfoot pathology. Orthopaedic surgeons should be aware of these risk factors and their association with patients’ outcomes after complex ankle fusions. Both external and internal fixations have demonstrated positive outcomes with regards to achieving stable fixation and minimizing infection. Recent innovations in the application of biophysical agents and devices have shown promising results as adjuncts for healing. Both osteoconductive and osteoinductive agents have been effectively utilized as biological adjuncts for bone healing with low complication rates. Devices such as pulsed electromagnetic field bone stimulators, internal direct current stimulators and low-intensity pulsed ultrasound bone stimulators have been associated with faster bone healing and improved outcomes scores when compared with controls. The aim of this review article is to present a comprehensive approach to the management of complex ankle fusions, including the use of biophysical adjuncts for healing and a proposed algorithm for their treatment. PMID:26396936

  5. Preparatory co-activation of the ankle muscles may prevent ankle inversion injuries.

    PubMed

    DeMers, Matthew S; Hicks, Jennifer L; Delp, Scott L

    2017-02-08

    Ankle inversion sprains are the most frequent acute musculoskeletal injuries occurring in physical activity. Interventions that retrain muscle coordination have helped rehabilitate injured ankles, but it is unclear which muscle coordination strategies, if any, can prevent ankle sprains. The purpose of this study was to determine whether coordinated activity of the ankle muscles could prevent excessive ankle inversion during a simulated landing on a 30° incline. We used a set of musculoskeletal simulations to evaluate the efficacy of two strategies for coordinating the ankle evertor and invertor muscles during simulated landing scenarios: planned co-activation and stretch reflex activation with physiologic latency (60-ms delay). A full-body musculoskeletal model of landing was used to generate simulations of a subject dropping onto an inclined surface with each coordination condition. Within each condition, the intensity of evertor and invertor co-activity or stretch reflexes were varied systematically. The simulations revealed that strong preparatory co-activation of the ankle evertors and invertors prior to ground contact prevented ankle inversion from exceeding injury thresholds by rapidly generating eversion moments after initial contact. Conversely, stretch reflexes were too slow to generate eversion moments before the simulations reached the threshold for inversion injury. These results suggest that training interventions to protect the ankle should focus on stiffening the ankle with muscle co-activation prior to landing. The musculoskeletal models, controllers, software, and simulation results are freely available online at http://simtk.org/home/ankle-sprains, enabling others to reproduce the results and explore new injury scenarios and interventions.

  6. Test-Retest Reliability of Sudden Ankle Inversion Measurements in Subjects With Healthy Ankle Joints

    PubMed Central

    Eechaute, Christophe; Vaes, Peter; Duquet, William; Van Gheluwe, Bart

    2007-01-01

    Context: Sudden ankle inversion tests have been used to investigate whether the onset of peroneal muscle activity is delayed in patients with chronically unstable ankle joints. Before interpreting test results of latency times in patients with chronic ankle instability and healthy subjects, the reliability of these measures must be first demonstrated. Objective: To investigate the test-retest reliability of variables measured during a sudden ankle inversion movement in standing subjects with healthy ankle joints. Design: Validation study. Setting: Research laboratory. Patients or Other Participants: 15 subjects with healthy ankle joints (30 ankles). Intervention(s): Subjects stood on an ankle inversion platform with both feet tightly fixed to independently moveable trapdoors. An unexpected sudden ankle inversion of 50° was imposed. Main Outcome Measure(s): We measured latency and motor response times and electromechanical delay of the peroneus longus muscle, along with the time and angular position of the first and second decelerating moments, the mean and maximum inversion speed, and the total inversion time. Correlation coefficients and standard error of measurements were calculated. Results: Intraclass correlation coefficients ranged from 0.17 for the electromechanical delay of the peroneus longus muscle (standard error of measurement = 2.7 milliseconds) to 0.89 for the maximum inversion speed (standard error of measurement = 34.8 milliseconds). Conclusions: The reliability of the latency and motor response times of the peroneus longus muscle, the time of the first and second decelerating moments, and the mean and maximum inversion speed was acceptable in subjects with healthy ankle joints and supports the investigation of the reliability of these measures in subjects with chronic ankle instability. The lower reliability of the electromechanical delay of the peroneus longus muscle and the angular positions of both decelerating moments calls the use of these

  7. Permanent reorganization of Ia afferent synapses on motoneurons after peripheral nerve injuries

    PubMed Central

    Alvarez, Francisco J.; Bullinger, Katie L.; Titus, Haley E.; Nardelli, Paul; Cope, Timothy C.

    2010-01-01

    After peripheral nerve injuries to a motor nerve the axons of motoneurons and proprioceptors are disconnected from the periphery and monosynaptic connections from group I afferents and motoneurons become diminished in the spinal cord. Following successful reinnervation in the periphery, motor strength, proprioceptive sensory encoding, and Ia afferent synaptic transmission on motoneurons partially recover. Muscle stretch reflexes, however, never recover and motor behaviors remain uncoordinated. In this review, we summarize recent findings that suggest that lingering motor dysfunction might be in part related to decreased connectivity of Ia afferents centrally. First, sensory afferent synapses retract from lamina IX causing a permanent relocation of the inputs to more distal locations and significant disconnection from motoneurons. Second, peripheral reconnection between proprioceptive afferents and muscle spindles is imperfect. As a result, a proportion of sensory afferents that retain central connections with motoneurons might not reconnect appropriately in the periphery. A hypothetical model is proposed in which the combined effect of peripheral and central reconnection deficits might explain the failure of muscle stretch to initiate or modulate firing of many homonymous motoneurons. PMID:20536938

  8. Mutant SOD1-expressing astrocytes release toxic factors that trigger motoneuron death by inducing hyperexcitability

    PubMed Central

    Fritz, Elsa; Izaurieta, Pamela; Weiss, Alexandra; Mir, Franco R.; Rojas, Patricio; Gonzalez, David; Rojas, Fabiola; Brown, Robert H.; Madrid, Rodolfo

    2013-01-01

    Amyotrophic lateral sclerosis (ALS) is a devastating paralytic disorder caused by dysfunction and degeneration of motoneurons starting in adulthood. Recent studies using cell or animal models document that astrocytes expressing disease-causing mutations of human superoxide dismutase 1 (hSOD1) contribute to the pathogenesis of ALS by releasing a neurotoxic factor(s). Neither the mechanism by which this neurotoxic factor induces motoneuron death nor its cellular site of action has been elucidated. Here we show that acute exposure of primary wild-type spinal cord cultures to conditioned medium derived from astrocytes expressing mutant SOD1 (ACM-hSOD1G93A) increases persistent sodium inward currents (PCNa), repetitive firing, and intracellular calcium transients, leading to specific motoneuron death days later. In contrast to TTX, which paradoxically increased twofold the amplitude of calcium transients and killed motoneurons, reduction of hyperexcitability by other specific (mexiletine) and nonspecific (spermidine and riluzole) blockers of voltage-sensitive sodium (Nav) channels restored basal calcium transients and prevented motoneuron death induced by ACM-hSOD1G93A. These findings suggest that riluzole, the only FDA-approved drug with known benefits for ALS patients, acts by inhibiting hyperexcitability. Together, our data document that a critical element mediating the non-cell-autonomous toxicity of ACM-hSOD1G93A on motoneurons is increased excitability, an observation with direct implications for therapy of ALS. PMID:23486205

  9. Pattern of innervation and recruitment of different classes of motoneurons in adult zebrafish.

    PubMed

    Ampatzis, Konstantinos; Song, Jianren; Ausborn, Jessica; El Manira, Abdeljabbar

    2013-06-26

    In vertebrates, spinal circuits drive rhythmic firing in motoneurons in the appropriate sequence to produce locomotor movements. These circuits become active early during development and mature gradually to acquire the flexibility necessary to accommodate the increased behavioral repertoire of adult animals. The focus here is to elucidate how different pools of motoneurons are organized and recruited and how membrane properties contribute to their mode of operation. For this purpose, we have used the in vitro preparation of adult zebrafish. We show that different motoneuron pools are organized in a somatotopic fashion in the motor column related to the type of muscle fibers (slow, intermediate, fast) they innervate. During swimming, the different motoneuron pools are recruited in a stepwise manner from slow, to intermediate, to fast to cover the full range of locomotor frequencies seen in intact animals. The spike threshold, filtering properties, and firing patterns of the different motoneuron pools are graded in a manner that relates to their order of recruitment. Our results thus show that motoneurons in adult zebrafish are organized into distinct modules, each with defined locations, properties, and recruitment patterns tuned to precisely match the muscle properties and hence produce swimming of different speeds and modalities.

  10. Muscle atrophy is associated with cervical spinal motoneuron loss in BACHD mouse model for Huntington's disease.

    PubMed

    Valadão, Priscila Aparecida Costa; de Aragão, Bárbara Campos; Andrade, Jéssica Neves; Magalhães-Gomes, Matheus Proença S; Foureaux, Giselle; Joviano-Santos, Julliane Vasconcelos; Nogueira, José Carlos; Ribeiro, Fabíola Mara; Tapia, Juan Carlos; Guatimosim, Cristina

    2017-03-01

    Involuntary choreiform movements are clinical hallmark of Huntington's disease, an autosomal dominant neurodegenerative disorder caused by an increased number of CAG trinucleotide repeats in the huntingtin gene. Involuntary movements start with an impairment of facial muscles and then affect trunk and limbs muscles. Huntington's disease symptoms are caused by changes in cortex and striatum neurons induced by mutated huntingtin protein. However, little is known about the impact of this abnormal protein in spinal cord motoneurons that control movement. Therefore, in this study we evaluated abnormalities in the motor unit (spinal cervical motoneurons, motor axons, neuromuscular junctions and muscle) in a mouse model for Huntington's disease (BACHD). Using light, fluorescence, confocal, and electron microscopy, we showed significant changes such as muscle fibers atrophy, fragmentation of neuromuscular junctions, axonal alterations, and motoneurons death in BACHD mice. Noteworthy, the surviving motoneurons from BACHD spinal cords were smaller than WT. We suggest that this loss of larger putative motoneurons is accompanied by a decrease in the expression of fast glycolytic muscle fibers in this model for Huntington's disease. These observations show spinal cord motoneurons loss in BACHD that might help to understand neuromuscular changes in Huntington's disease.

  11. Acidotoxicity and acid-sensing ion channels contribute to motoneuron degeneration.

    PubMed

    Behan, A T; Breen, B; Hogg, M; Woods, I; Coughlan, K; Mitchem, M; Prehn, J H M

    2013-04-01

    Amyotrophic lateral sclerosis (ALS) is a fatal neurological condition with no cure. Mitochondrial dysfunction, Ca(2+) overloading and local hypoxic/ischemic environments have been implicated in the pathophysiology of ALS and are conditions that may initiate metabolic acidosis in the affected tissue. We tested the hypothesis that acidotoxicity and acid-sensing ion channels (ASICs) are involved in the pathophysiology of ALS. We found that motoneurons were selectively vulnerable to acidotoxicity in vitro, and that acidotoxicity was partially reduced in asic1a-deficient motoneuron cultures. Cross-breeding of SOD1(G93A) ALS mice with asic1a-deficient mice delayed the onset and progression of motor dysfunction in SOD1 mice. Interestingly, we also noted a strong increase in ASIC2 expression in motoneurons of SOD1 mice and sporadic ALS patients during disease progression. Pharmacological pan-inhibition of ASIC channels with the lipophilic amiloride derivative, 5-(N,N-dimethyl)-amiloride hydrochloride, potently protected cultured motoneurons against acidotoxicity, and, given post-symptom onset, significantly improved lifespan, motor performance and motoneuron survival in SOD1 mice. Together, our data provide strong evidence for the involvement of acidotoxicity and ASIC channels in motoneuron degeneration, and highlight the potential of ASIC inhibitors as a new treatment approach for ALS.

  12. Effects of the application of ankle functional rehabilitation exercise on the ankle joint functional movement screen and isokinetic muscular function in patients with chronic ankle sprain

    PubMed Central

    Ju, Sung-Bum; Park, Gi Duck

    2017-01-01

    [Purpose] This study was conducted to investigate the effects of ankle functional rehabilitation exercise on ankle joint functional movement screen results and isokinetic muscular function in patients with chronic ankle sprain patients. [Subjects and Methods] In this study, 16 patients with chronic ankle sprain were randomized to an ankle functional rehabilitation exercise group (n=8) and a control group (n=8). The ankle functional rehabilitation exercise centered on a proprioceptive sense exercise program, which was applied 12 times for 2 weeks. To verify changes after the application, ankle joint functional movement screen scores and isokinetic muscular function were measured and analyzed. [Results] The ankle functional rehabilitation exercise group showed significant improvements in all items of the ankle joint functional movement screen and in isokinetic muscular function after the exercise, whereas the control group showed no difference after the application. [Conclusion] The ankle functional rehabilitation exercise program can be effectively applied in patients with chronic ankle sprain for the improvement of ankle joint functional movement screen score and isokinetic muscular function. PMID:28265157

  13. Effects of the application of ankle functional rehabilitation exercise on the ankle joint functional movement screen and isokinetic muscular function in patients with chronic ankle sprain.

    PubMed

    Ju, Sung-Bum; Park, Gi Duck

    2017-02-01

    [Purpose] This study was conducted to investigate the effects of ankle functional rehabilitation exercise on ankle joint functional movement screen results and isokinetic muscular function in patients with chronic ankle sprain patients. [Subjects and Methods] In this study, 16 patients with chronic ankle sprain were randomized to an ankle functional rehabilitation exercise group (n=8) and a control group (n=8). The ankle functional rehabilitation exercise centered on a proprioceptive sense exercise program, which was applied 12 times for 2 weeks. To verify changes after the application, ankle joint functional movement screen scores and isokinetic muscular function were measured and analyzed. [Results] The ankle functional rehabilitation exercise group showed significant improvements in all items of the ankle joint functional movement screen and in isokinetic muscular function after the exercise, whereas the control group showed no difference after the application. [Conclusion] The ankle functional rehabilitation exercise program can be effectively applied in patients with chronic ankle sprain for the improvement of ankle joint functional movement screen score and isokinetic muscular function.

  14. [Revision arthroplasty of the ankle joint].

    PubMed

    Hintermann, B; Barg, A; Knupp, M

    2011-11-01

    In the last 20 years total ankle replacement has become a viable alternative to arthrodesis for end-stage osteoarthritis of the ankle. Numerous ankle prosthesis designs have appeared on the market in the past and attracted by the encouraging intermediate results reported in the literature, many surgeons have started to perform this procedure. With increased availability on the market the indications for total ankle replacement have also increased in recent years. In particular, total ankle replacement may now be considered even in younger patients. Therefore, despite progress in total ankle arthroplasty the number of failures may increase. Up to now, arthrodesis was considered to be the gold standard for salvage of failed ankle prostheses. Because of extensive bone loss on the talar side, in most instances tibiocalcaneal fusion is the only reliable solution. An alternative to such extended hindfoot fusions would be revision arthroplasty. To date, however, there are no reported results of revision arthroplasty for salvage of a failed ankle replacement.Based on our experience prosthetic components with a flat undersurface are most likely to be able to find solid support on remaining bone stock. The first 83 cases (79 patients, 46 males, 33 females, average age 58.9 years, range 30.6-80.7 years) with a average follow-up of 5.4 years (range 2-11 years) showed excellent to good results in 69 cases (83%), a satisfactory result in 12 cases (15%) and a fair result in 2 cases (2%) and 47 patients (56%) were pain free. Primary loosening was noted in three cases and of these two cases were successfully revised by another total ankle replacement and in one case with arthrodesis. Another case with hematogenous infection was also revised by arthrodesis. At the last follow-up control two components were considered to be loose and the overall loosening rate was thus 6%.This series has proven that revision arthroplasty can be a promising option for patients with failed total

  15. The ankle meter: an instrument for evaluation of anterior talar drawer in ankle sprain.

    PubMed

    Spahn, Gunter

    2004-07-01

    The aim of this study was to work out a clinical test which is possible to measure the anterior talar drawer (ATD) in patients after ankle sprain. The instrument for evaluation was called "ankle meter". The instrument consists of two plastic scales (heal scale and tibia scale). The instrument allows quantifying the results of the anterior drawing test. A total of 38 persons (16 men, 22 women) were available as control group. The persons were 28.8+/-10.1 years old. No proband had any ankle problems in his history. A total of 45 patients (25 males, 20 females) suffering from ankle sprain were included in the study. In these patients stress radiography (147.1 N) was performed to measure the ATD. In control group the clinical measured ATD was 1.7+/-1.3 mm. Measurement for detect the interobserver validity did not detect significant differences. The ATD of the joint after ankle sprain was significantly higher (8.9+/-4.3 mm). The difference between healthy and injured ankle in case of an ankle sprain was 7.4+/-4.2 mm. There was a significant correlation between clinical and radiological measured ATD (R=0.91). The results suggest that it is possible to measure the ATD exactly. The values of the clinical ATD measurement showed a good correlation with the results of stress radiography. Diligent clinical examination in combination with this special test are after this experiences sufficient to classify the severity of injury after ankle sprain.

  16. The effectiveness of the parachutist ankle brace in reducing ankle injuries in an airborne ranger battalion.

    PubMed

    Schumacher, J T; Creedon, J F; Pope, R W

    2000-12-01

    The purpose of this study was to determine if the parachutist ankle brace (PAB) decreases the number and severity of ankle injuries in an airborne Ranger battalion. A retrospective study was performed covering a 38-month period. A computer database was used to track all jump injuries with a diagnosis of ankle pain, sprain, or fracture. The frequency was calculated for ankle injuries per 1,000 jumps and the average length of medically restricted duty per ankle injury. A total of 13,782 static line parachute jumps were conducted during the study period. Without the PAB, 35 ankle injuries were seen (4.5/1,000 jumps), with 9 fractures and 316 days of medical restriction per 1,000 jumps. Using the PAB, 9 ankle injuries were seen (1.5/1,000 jumps), with 3 fractures and 71 days of medical restriction per 1,000 jumps. The correct use of the PAB appeared to significantly decrease the incidence of ankle injuries in this battalion.

  17. Effect of treadmill walking with ankle stretching orthosis on ankle flexibility and gait

    PubMed Central

    Cho, Young-ki; Kim, Si-hyun; Jeon, In-cheol; Ahn, Sun-hee; Kwon, Oh-yun

    2015-01-01

    [Purpose] The purpose of this study was to evaluate the kinematics of the ankle in the lunge to estabilish effectiveness of an ankle stretching orthosis (ASO) on the ankle dorsiflexion range of motion (ROM) of individuals with limited dorsiflexion ROM. [Subjects and Methods] Forty ankles with decreased dorsiflexion ROM of 20 participants were evaluated in this study. After wearing the ASO, participants walked on a treadmill for 15 minutes. Participants walked on the treadmill at a self-selected comfortable speed. Ankle dorsiflexion ROM, maximum dorsiflexion ROM before heel-off, and time to heel-off during the stance phase of gait were measured before and after 15 minutes of treadmill walking with the ASO. The differences in all variables between before and after treadmill walking with ASO were analyzed using the paired t-test. [Results] Ankle active and passive ROM, and dorsiflexion ROM during lunge increased significantly after treadmill walking with ASO. Treadmill walking with the ASO significantly increased the angle of maximal dorsiflexion before heel-off and time to heel-off during the stance phase. [Conclusion] The results of this study show that treadmill walking with the ASO effectively improved ankle flexibility and restored the normal gait pattern of the ankle joint by increasing dorsiflexion ROM, maximal angle of dorsiflexion, and time to heel-off in the stance phase. PMID:25995601

  18. The results of ankle arthrodesis with screws for end stage ankle arthrosis.

    PubMed

    Torudom, Yingyong

    2010-02-01

    Aim of this study was to evaluate the results of ankle arthrodesis with screws in patients with ankle arthrosis. The author studied 19 patients (20 feet) who had been treated by ankle arthrodesis with screws from 2003 to 2008. Ten patients were men (11 feet) and nine (9 feet) were women. Their mean age was 56 years (30 to 65), and the average duration of follow-up was four years (2 to 6). Two compression screws were used in all feet. Union was achieved in 19 of the 20 feet (95%). Average scores for pain and clinical condition are increase after operation. One re-operation was performed for nonunion. Author conclude that ankle arthrodesis with screws was effective treatment for ankle arthrosis.

  19. Differential synaptic effects on physiological flexor hindlimb motoneurons from cutaneous nerve inputs in spinal cat.

    PubMed

    Leahy, J C; Durkovic, R G

    1991-08-01

    1. We previously demonstrated in the spinal cat that superficial peroneal cutaneous nerve stimulation produced strong reflex contraction in tibialis anterior (TA) and semitendinosus (St) muscles but unexpectedly produced mixed effects in another physiological flexor muscle, extensor digitorum longus (EDL). The goal of the present study was to further characterize the organization of ipsilateral cutaneous reflexes by examining the postsynaptic potentials (PSPs) produced in St, TA, and EDL motoneurons by superficial peroneal and saphenous nerve stimulation in decerebrate, spinal cats. 2. In TA and St motoneurons, low-intensity cutaneous nerve stimulation that activated only large (A alpha) fibers [i.e., approximately 2-3 times threshold (T)], typically produced biphasic PSPs consisting of an initial excitatory phase and subsequent inhibitory phase (EPSP, IPSP). Increasing the stimulus intensity to activate both large (A alpha) and small (A delta) myelinated cutaneous fibers supramaximally (15-45 T) tended to enhance later excitatory components in TA and St motoneurons. 3. In EDL motoneurons, 2-3 T stimulation of the superficial peroneal nerve evoked initial inhibition (of variable magnitude) in 7/10 EDL motoneurons tested, with either excitation (n = 2) or mixed effects (n = 1) observed in the remaining EDL motoneurons. Saphenous nerve stimuli produced excitation either alone, or preceded by an inhibitory phase in EDL. Increasing the stimulus intensity enhanced later inhibitory influences from superficial peroneal and excitatory influences both from superficial peroneal and saphenous nerve inputs in EDL motoneurons. 4. Short-latency (less than 1.8 ms) EPSPs were observed in a few motoneurons in all reflex pathways examined, except for EPSPs in EDL motoneurons evoked by saphenous stimulation. IPSPs with central latencies less than 1.8 ms were also produced by both saphenous (TA, n = 1; EDL, n = 2) and superficial peroneal (EDL, n = 4) nerve stimulation. 5. The results

  20. Organization of hindlimb muscle afferent projections to lumbosacral motoneurons in the chick embryo.

    PubMed

    Lee, M T; O'Donovan, M J

    1991-08-01

    We have examined the organization of muscle afferent projections to motoneurons in the lumbosacral spinal cord of chick embryos between stage 37, when muscle afferents first reach the motor nucleus, and stage 44, which is just before hatching. Connectivity between afferents and motoneurons was assessed by stimulating individual muscle nerves and recording the resulting motoneuron synaptic potentials intracellularly or electrotonically from other muscle nerves. Most of the recordings were made in the presence of DL-2-amino-5-phosphonovaleric acid (APV), picrotoxin, and strychnine to block long-latency excitatory and inhibitory pathways. Activation of muscle afferents evoked slow, positive potentials in muscle nerves but not in cutaneous nerves. These potentials were abolished in 0 mM Ca2+, 2mM Mn2+ solutions, indicating that they were generated by the action of chemical synapses. The muscle nerve recordings revealed a wide-spread pattern of excitatory connections between afferents and motoneurons innervating six different thigh muscles, which were not organized according to synergist-antagonist relationships. This pattern of connectivity was confirmed using intracellular recording from identified motoneurons, which allowed the latency of the responses to be determined. Short-latency potentials in motoneurons were produced by activation of homonymous afferents and the heteronymous afferents innervating the hip flexors sartorius and anterior iliotibialis. Stimulation of anterior iliotibialis afferents also resulted in some short-latency excitatory postsynaptic potentials (EPSPs) in motoneurons innervating the knee extensor femorotibialis, though other connections were of longer latency. Afferents from the adductor, a hip extensor, did not evoke short-latency EPSPs in any of these three types of motoneurons. Short-latency, but not long-latency EPSPs, persisted during repetitive stimulation at 5 Hz, suggesting that they were mediated monosynaptically. Long

  1. Fluctuations of excitability in the monosynaptic reflex pathway to lumbar motoneurons in the cat.

    PubMed

    Gossard, J P; Floeter, M K; Kawai, Y; Burke, R E; Chang, T; Schiff, S J

    1994-09-01

    1. It is well known that the amplitude of successive monosynaptic reflexes (MSR), elicited by afferent stimuli of constant strength, fluctuate from trial to trial. Previous evidence suggests that such excitability fluctuations within the motor pool can be introduced either pre- and/or postsynaptically. Using unanesthetized decerebrate or decerebrate/spinal cats, we attempted to evaluate the relative importance of pre- and postsynaptic mechanisms to MSR variability and the potential contribution of changes in the identities of responding motoneurons to such variability. 2. Comparisons between the MSR amplitude, measured in a severed ventral root, and the probability of firing of up to three individual motoneurons in fine filaments teased from the same root, confirmed that both correlated and uncorrelated fluctuations of motoneuron excitability are involved in MSR variability. Linear regression analysis from concurrent intracellular recordings from homonymous motoneurons showed that the MSR fluctuations were correlated with the variations in membrane potential baseline, as well as with the fluctuations in the monosynaptic excitatory postsynaptic potential peak amplitude. In all 11 cases tested, the former correlation was stronger than the latter. 3. Stimulation of the caudal cutaneous sural nerve (CCS) was used to alter the postsynaptic potential background on which triceps surae (GS) MSRs were generated. The interval chosen between CCS conditioning and the GS stimulation excluded the involvement of presynaptic inhibition. When conditioned by preceding CCS stimulation, GS population MSRs generally (8/9 cases tested) increased in amplitude without much change in their overall variance. However, the individual motoneurons that contributed to the population responses did show changes in both relative excitability and in the uncorrelated component of their response variance. About half of the concurrently recorded motoneurons (6/13) showed a decrease in relative

  2. Synaptic Connectivity between Renshaw Cells and Motoneurons in the Recurrent Inhibitory Circuit of the Spinal Cord

    PubMed Central

    Moore, Niall J.; Bhumbra, Gardave S.; Foster, Joshua D.

    2015-01-01

    Renshaw cells represent a fundamental component of one of the first discovered neuronal circuits, but their function in motor control has not been established. They are the only central neurons that receive collateral projections from motor outputs, yet the efficacy of the excitatory synapses from single and converging motoneurons remains unknown. Here we present the results of dual whole-cell recordings from identified, synaptically connected Renshaw cell-motoneuron pairs in the mouse lumbar spinal cord. The responses from single Renshaw cells demonstrate that motoneuron synapses elicit large excitatory conductances with few or no failures. We show that the strong excitatory input from motoneurons results from a high probability of neurotransmitter release onto multiple postsynaptic contacts. Dual current-clamp recordings confirm that single motoneuron inputs were sufficient to depolarize the Renshaw cell beyond threshold for firing. Reciprocal connectivity was observed in approximately one-third of the paired recordings tested. Ventral root stimulation was used to evoke currents from Renshaw cells or motoneurons to characterize responses of single neurons to the activation of their corresponding presynaptic cell populations. Excitatory or inhibitory synaptic inputs in the recurrent inhibitory loop induced substantial effects on the excitability of respective postsynaptic cells. Quantal analysis estimates showed a large number of converging inputs from presynaptic motoneuron and Renshaw cell populations. The combination of considerable synaptic efficacy and extensive connectivity within the recurrent circuitry indicates a role of Renshaw cells in modulating motor outputs that may be considerably more important than has been previously supposed. SIGNIFICANCE STATEMENT We have recently shown that Renshaw cells mediate powerful shunt inhibition on motoneuron excitability. Here we complete a quantitative description of the recurrent circuit using recordings of

  3. [Ankle joint arthritis--etiology, diagnosis and treatment].

    PubMed

    Uri, Ofir; Haim, Amir

    2008-11-01

    Ankle joint arthritis causes functional limitation and affects the quality of life many patients. It follows traumatic injuries, inflammatory joint arthritis, primary osteoarthritis, hemochromatosis and infections. Understanding the unique anatomy and biomechanics of the ankle is important for diagnosis and treatment of ankle joint pathology. The treatment of ankle joint arthritis has advanced considerably in recent years and it is still a surgical challenge. Total ankle replacement seems to be a promising form of treatment, even though current data does not demonstrate advantages over ankle joint arthrodesis.

  4. Arthroscopic Management of Complications Following Total Ankle Replacement.

    PubMed

    Lui, Tun Hing; Roukis, Thomas S

    2015-10-01

    There is great potential of managing the complications of total ankle replacement arthroscopically and endoscopically, and these procedures can be summarized into 3 groups. Group 1 includes procedures of the ankle joint proper with close proximity to the articular components of the total ankle replacement. Group 2 includes procedures of the tibia and talus with close proximity to the nonarticular parts of the total ankle replacement. Group 3 includes procedures that are away from the total ankle replacement. However, these remain master arthroscopist procedures and should be performed by foot and ankle surgeons who perform them with regularity.

  5. [Chronic diseases of the ankle joint].

    PubMed

    Rand, T; Trattnig, S; Breitenseher, M; Kreuzer, S; Wagesreither, S; Imhof, H

    1999-01-01

    The etiology of chronic diseases of the ankle joint comprises a wide spectrum including chronic inflammatory processes and chronic degenerative, tumorous and neuropathic processes, as well as some specific syndromes based on chronic changes of the ankle joint. Of the inflammatory processes, chronic juvenile arthritis (JVC) is the most common disease. However, also Reiter disease, psoriasis or chronic monoarthritid diseases such as gout, as well as granulomatous diseases (tuberculosis, sarcoidosis) and fungal infections, may affect the ankle joint in a chronic course. Chronic degenerative changes are usually secondary due to abnormal positioning of the joint constituents or repetitive trauma. Neuropathic changes, as frequently seen in the course of diabetes, present with massive osseous destruction and malposition of the articular constituents. Chronic osseous as well as cartilaginous and synovial changes are seen in hemophilic patients. Chronic traumatic changes are represented by pigmented villonodular synovitis (PVNS), and chondromatosis, both with a predilection for the ankle joint. Due to the possibilities of magnetic resonance imaging (MRI), diagnosis of chronic ankle changes includes chronic ligamentous, tendinous and soft tissue changes. With the use of MRI, specific syndromes can be defined which particularly affect the ankle joint in a chronic way, such as the os trigonum syndrome, the anterolateral impingement syndrome and the sinus tarsi syndrome. Nevertheless, plain film radiographs are still the basic element of any investigation. MRI, however, can be potentially used as a second investigation, saving an unnecessary cascade of investigations with ultrasound and CT. The latter investigations are used only with very specific indications, for instance CT for subtle bone structures and sonography for a limited investigation of tendons or evaluation of fluid. Particularly due to the possibilities of MRI and the development of special gradient-echo imaging

  6. Ankle-Dorsiflexion Range of Motion After Ankle Self-Stretching Using a Strap

    PubMed Central

    Jeon, In-cheol; Kwon, Oh-yun; Yi, Chung-Hwi; Cynn, Heon-Seock; Hwang, Ui-jae

    2015-01-01

    Context  A variety of ankle self-stretching exercises have been recommended to improve ankle-dorsiflexion range of motion (DFROM) in individuals with limited ankle dorsiflexion. A strap can be applied to stabilize the talus and facilitate anterior glide of the distal tibia at the talocrural joint during ankle self-stretching exercises. Novel ankle self-stretching using a strap (SSS) may be a useful method of improving ankle DFROM. Objective  To compare the effects of 2 ankle-stretching techniques (static stretching versus SSS) on ankle DFROM. Design  Randomized controlled clinical trial. Setting  University research laboratory. Patients or Other Participants  Thirty-two participants with limited active dorsiflexion (<20°) while sitting (14 women and 18 men) were recruited. Main Outcome Measure(s)  The participants performed 2 ankle self-stretching techniques (static stretching and SSS) for 3 weeks. Active DFROM (ADFROM), passive DFROM (PDFROM), and the lunge angle were measured. An independent t test was used to compare the improvements in these values before and after the 2 stretching interventions. The level of statistical significance was set at α = .05. Results  Active DFROM and PDFROM were greater in both stretching groups after the 3-week interventions. However, ADFROM, PDFROM, and the lunge angle were greater in the SSS group than in the static-stretching group (P < .05). Conclusions  Ankle SSS is recommended to improve ADFROM, PDFROM, and the lunge angle in individuals with limited DFROM. PMID:26633750

  7. Paratrooper's Ankle Fracture: Posterior Malleolar Fracture

    PubMed Central

    Young, Ki Won; Cho, Jae Ho; Kim, Hyung Seuk; Cho, Hun Ki; Lee, Kyung Tai

    2015-01-01

    Background We assessed the frequency and types of ankle fractures that frequently occur during parachute landings of special operation unit personnel and analyzed the causes. Methods Fifty-six members of the special force brigade of the military who had sustained ankle fractures during parachute landings between January 2005 and April 2010 were retrospectively analyzed. The injury sites and fracture sites were identified and the fracture types were categorized by the Lauge-Hansen and Weber classifications. Follow-up surveys were performed with respect to the American Orthopedic Foot and Ankle Society ankle-hindfoot score, patient satisfaction, and return to preinjury activity. Results The patients were all males with a mean age of 23.6 years. There were 28 right and 28 left ankle fractures. Twenty-two patients had simple fractures and 34 patients had comminuted fractures. The average number of injury and fractures sites per person was 2.07 (116 injuries including a syndesmosis injury and a deltoid injury) and 1.75 (98 fracture sites), respectively. Twenty-three cases (41.07%) were accompanied by posterior malleolar fractures. Fifty-five patients underwent surgery; of these, 30 had plate internal fixations. Weber type A, B, and C fractures were found in 4, 38, and 14 cases, respectively. Based on the Lauge-Hansen classification, supination-external rotation injuries were found in 20 cases, supination-adduction injuries in 22 cases, pronation-external rotation injuries in 11 cases, tibiofibular fractures in 2 cases, and simple medial malleolar fractures in 2 cases. The mean follow-up period was 23.8 months, and the average follow-up American Orthopedic Foot and Ankle Society ankle-hindfoot score was 85.42. Forty-five patients (80.36%) reported excellent or good satisfaction with the outcome. Conclusions Posterior malleolar fractures occurred in 41.07% of ankle fractures sustained in parachute landings. Because most of the ankle fractures in parachute injuries were

  8. The activation patterns of embryonic chick motoneurones projecting to inappropriate muscles.

    PubMed Central

    Landmesser, L T; O'Donovan, M J

    1984-01-01

    Chick lumbosacral motoneurones were caused to innervate foreign muscles by surgically rotating or shifting the limb bud about the anterior-posterior axis in stage 17-18 embryos. The activation pattern of such wrongly projecting motoneurones was assessed at stages 35-38 by recording electromyographic activity from muscles in an isolated spinal cord/hind limb preparation. Muscle activity was classed as flexor- or extensor-like according to the characteristics of the patterned sequence of bursts elicited by a single shock to the thoracic cord. Wrongly projecting motoneurones did not have their activation pattern altered to one appropriate for the muscle innervated; therefore in some cases a particular muscle was activated with a pattern similar to its original one, and in other cases in an opposite manner. Mixed flexor-extensor-like activation of a single muscle was, however, rare. The identity of motoneurones projecting to a muscle was determined by their cord location following retrograde labelling with horseradish peroxidase. This allowed us to conclude that motoneurones could develop their normal pattern of activation even when projecting to foreign muscles. It is concluded that the cord circuits (presumably composed of local interneurones responsible for the activation of motoneurones in the isolated cord preparation are not altered by retrograde influences from the muscle. Wrongly projecting motoneurones, which were maintained throughout the normal cell death period, were activated during spontaneous embryonic movements, and in many cases were found to have a behaviourally inappropriate activation pattern. These observations are discussed in relation to proposed mechanisms by which developmental errors in connectivity are corrected. Images Fig. 1 PMID:6707957

  9. The activation patterns of embryonic chick motoneurones projecting to inappropriate muscles.

    PubMed

    Landmesser, L T; O'Donovan, M J

    1984-02-01

    Chick lumbosacral motoneurones were caused to innervate foreign muscles by surgically rotating or shifting the limb bud about the anterior-posterior axis in stage 17-18 embryos. The activation pattern of such wrongly projecting motoneurones was assessed at stages 35-38 by recording electromyographic activity from muscles in an isolated spinal cord/hind limb preparation. Muscle activity was classed as flexor- or extensor-like according to the characteristics of the patterned sequence of bursts elicited by a single shock to the thoracic cord. Wrongly projecting motoneurones did not have their activation pattern altered to one appropriate for the muscle innervated; therefore in some cases a particular muscle was activated with a pattern similar to its original one, and in other cases in an opposite manner. Mixed flexor-extensor-like activation of a single muscle was, however, rare. The identity of motoneurones projecting to a muscle was determined by their cord location following retrograde labelling with horseradish peroxidase. This allowed us to conclude that motoneurones could develop their normal pattern of activation even when projecting to foreign muscles. It is concluded that the cord circuits (presumably composed of local interneurones responsible for the activation of motoneurones in the isolated cord preparation are not altered by retrograde influences from the muscle. Wrongly projecting motoneurones, which were maintained throughout the normal cell death period, were activated during spontaneous embryonic movements, and in many cases were found to have a behaviourally inappropriate activation pattern. These observations are discussed in relation to proposed mechanisms by which developmental errors in connectivity are corrected.

  10. Normal distribution of VGLUT1 synapses on spinal motoneuron dendrites and their reorganization after nerve injury.

    PubMed

    Rotterman, Travis M; Nardelli, Paul; Cope, Timothy C; Alvarez, Francisco J

    2014-03-05

    Peripheral nerve injury induces permanent alterations in spinal cord circuitries that are not reversed by regeneration. Nerve injury provokes the loss of many proprioceptive IA afferent synapses (VGLUT1-IR boutons) from motoneurons, the reduction of IA EPSPs in motoneurons, and the disappearance of stretch reflexes. After motor and sensory axons successfully reinnervate muscle, lost IA VGLUT1 synapses are not re-established and the stretch reflex does not recover; however, electrically evoked EPSPs do recover. The reasons why remaining IA synapses can evoke EPSPs on motoneurons, but fail to transmit useful stretch signals are unknown. To better understand changes in the organization of VGLUT1 IA synapses that might influence their input strength, we analyzed their distribution over the entire dendritic arbor of motoneurons before and after nerve injury. Adult rats underwent complete tibial nerve transection followed by microsurgical reattachment and 1 year later motoneurons were intracellularly recorded and filled with neurobiotin to map the distribution of VGLUT1 synapses along their dendrites. We found in control motoneurons an average of 911 VGLUT1 synapses; ~62% of them were lost after injury. In controls, VGLUT1 synapses were focused to proximal dendrites where they were grouped in tight clusters. After injury, most synaptic loses occurred in the proximal dendrites and remaining synapses were declustered, smaller, and uniformly distributed throughout the dendritic arbor. We conclude that this loss and reorganization renders IA afferent synapses incompetent for efficient motoneuron synaptic depolarization in response to natural stretch, while still capable of eliciting EPSPs when synchronously fired by electrical volleys.

  11. Rehabilitation of Syndesmotic (High) Ankle Sprains

    PubMed Central

    Williams, Glenn N.; Allen, Eric J.

    2010-01-01

    Context: High ankle sprains are common in athletes who play contact sports. Most high ankle sprains are treated nonsurgically with a rehabilitation program. Evidence Acquisition: All years of PUBMED, Cochrane Database of Systematic Reviews, CINAHL PLUS, SPORTDiscuss, Google Scholar, and Web of Science were searched to August 2010, cross-referencing existing publications. Keywords included syndesmosis ankle sprain or high ankle sprain and the following terms: rehabilitation, treatment, cryotherapy, braces, orthosis, therapeutic modalities, joint mobilization, massage, pain, pain medications, TENS (ie, transcutaneous electric nerve stimulation), acupuncture, aquatic therapy, strength, neuromuscular training, perturbation training, and outcomes. Results: Level of evidence, 5. A 3-phase rehabilitation program is described. The acute phase is directed at protecting the joint while minimizing pain, inflammation, muscle weakness, and loss of motion. Most patients are treated with some form of immobilization and have weightbearing restrictions. A range of therapeutic modalities are used to minimize pain and inflammation. Gentle mobilization and resistance exercises are used to gain mobility and maintain muscle size and strength. The subacute phase is directed at normalizing range of motion, strength, and function in activities of daily living. Progressive mobilization and strengthening are hallmarks of this phase. Neuromuscular training is begun and becomes the central component of rehabilitation. The advanced training phase focuses on preparing the patient for return to sports participation. Perturbation of support surfaces, agility drills, plyometrics, and sport-specific training are central components of this phase. Conclusion: The rehabilitation guidelines discussed may assist clinicians in managing syndesmotic ankle sprains. PMID:23015976

  12. Analysis of the Effects of Normal Walking on Ankle Joint Contact Characteristics After Acute Inversion Ankle Sprain.

    PubMed

    Bae, Ji Yong; Park, Kyung Soon; Seon, Jong Keun; Jeon, Insu

    2015-12-01

    To show the causal relationship between normal walking after various lateral ankle ligament (LAL) injuries caused by acute inversion ankle sprains and alterations in ankle joint contact characteristics, finite element simulations of normal walking were carried out using an intact ankle joint model and LAL injury models. A walking experiment using a volunteer with a normal ankle joint was performed to obtain the boundary conditions for the simulations and to support the appropriateness of the simulation results. Contact pressure and strain on the talus articular cartilage and anteroposterior and mediolateral translations of the talus were calculated. Ankles with ruptured anterior talofibular ligaments (ATFLs) had a higher likelihood of experiencing increased ankle joint contact pressures, strains and translations than ATFL-deficient ankles. In particular, ankles with ruptured ATFL + calcaneofibular ligaments and all ruptured ankles had a similar likelihood as the ATFL-ruptured ankles. The push off stance phase was the most likely situation for increased ankle joint contact pressures, strains and translations in LAL-injured ankles.

  13. [Chronic ankle instability in sports -- a review for sports physicians].

    PubMed

    Valderrabano, V; Leumann, A; Pagenstert, G; Frigg, A; Ebneter, L; Hintermann, B

    2006-12-01

    Chronic ankle instability represents a typical sports injury which can mostly be seen in basketball, soccer, orienteering and other high risk sports. 20 to 40 % of the acute ankle sprains develop into chronic ankle instability. From a sports orthopaedic point of view, chronic ankle instability can be subdivided into a lateral, medial or a combination of both so called rotational ankle instability. From a pathophysiological point of view, chronic ankle instability can be either mechanical with a structural ligament lesion or functional with loss of the neuromuscular control. For the sports physician, the chronic ankle instability is a difficult entity as the diagnosis is usually complex and the therapy usually surgical. This review on chronic ankle instability addresses pathomechanism, diagnostics, indications for conservative and surgical treatments, and possible long-term sequelae, as ligamentous osteoarthritis.

  14. Measurement of passive ankle stiffness in subjects with chronic hemiparesis using a novel ankle robot.

    PubMed

    Roy, Anindo; Krebs, Hermano I; Bever, Christopher T; Forrester, Larry W; Macko, Richard F; Hogan, Neville

    2011-05-01

    Our objective in this study was to assess passive mechanical stiffness in the ankle of chronic hemiparetic stroke survivors and to compare it with those of healthy young and older (age-matched) individuals. Given the importance of the ankle during locomotion, an accurate estimate of passive ankle stiffness would be valuable for locomotor rehabilitation, potentially providing a measure of recovery and a quantitative basis to design treatment protocols. Using a novel ankle robot, we characterized passive ankle stiffness both in sagittal and in frontal planes by applying perturbations to the ankle joint over the entire range of motion with subjects in a relaxed state. We found that passive stiffness of the affected ankle joint was significantly higher in chronic stroke survivors than in healthy adults of a similar cohort, both in the sagittal as well as frontal plane of movement, in three out of four directions tested with indistinguishable stiffness values in plantarflexion direction. Our findings are comparable to the literature, thus indicating its plausibility, and, to our knowledge, report for the first time passive stiffness in the frontal plane for persons with chronic stroke and older healthy adults.

  15. Osteochondral defects in the ankle: why painful?

    PubMed

    van Dijk, C Niek; Reilingh, Mikel L; Zengerink, Maartje; van Bergen, Christiaan J A

    2010-05-01

    Osteochondral defects of the ankle can either heal and remain asymptomatic or progress to deep ankle pain on weight bearing and formation of subchondral bone cysts. The development of a symptomatic OD depends on various factors, including the damage and insufficient repair of the subchondral bone plate. The ankle joint has a high congruency. During loading, compressed cartilage forces its water into the microfractured subchondral bone, leading to a localized high increased flow and pressure of fluid in the subchondral bone. This will result in local osteolysis and can explain the slow development of a subchondral cyst. The pain does not arise from the cartilage lesion, but is most probably caused by repetitive high fluid pressure during walking, which results in stimulation of the highly innervated subchondral bone underneath the cartilage defect. Understanding the natural history of osteochondral defects could lead to the development of strategies for preventing progressive joint damage.

  16. Lateral ligament reconstruction procedures for the ankle.

    PubMed

    Tourné, Y; Mabit, C

    2017-02-01

    Capsule/ligament lesions of the lateral compartment of the ankle lead to lateral laxity, which is a prime contributor to chronic ankle instability. Lateral ligament reconstruction stabilizes the joint. Exhaustive preoperative clinical and paraclinical work-up is essential. The present article classifies, presents and criticizes the main techniques in terms of long-term stabilization and reduction of osteoarthritis risk. Anatomic ligament repair with reinforcement (mainly extensor retinaculum) or anatomic ligament reconstruction are the two recommended options. Non-anatomic reconstructions using the peroneus brevis should be abandoned. Arthroscopy is increasingly being developed, but results need assessment on longer follow-up than presently available. Postoperative neuromuscular reprogramming is fundamental to optimal recovery. Finally, the concept of complex ankle instability is discussed from the diagnostic and therapeutic points of view. The various forms of ligament reconstruction failure and corresponding treatments are reported.

  17. VISCOSUPPLEMENTATION IN ANKLE OSTEOARTHRITIS: A SYSTEMATIC REVIEW

    PubMed Central

    Faleiro, Thiago Batista; Schulz, Renata da Silva; Jambeiro, Jorge Eduardo de Schoucair; Tavares, Antero; Delmonte, Fernando Moreira; Daltro, Gildásio de Cerqueira

    2016-01-01

    ABSTRACT To evaluate the efficacy of viscosupplementation in patients with osteoarthritis of the ankle. A systematic review to evaluate the evidence in the literature on the use of viscosupplementation for osteoarthritis of the ankle. For this review, we considered blind randomized prospective studies involving the use of viscosupplementation for osteoarthritis of the ankle. A total of 1,961 articles were identified in various databases. After examining each of the articles, five articles were included in this review. Treatment with intraarticular hyaluronic acid is a safe treatment modality that significantly improves functional scores of patients, with no evidence of superiority in relation to other conservative treatments. Further clinical trials with larger numbers of patients are needed so that we can recommend its use and address unanswered questions. Systematic Review of Randomized Clinical Trials. PMID:26997916

  18. VISCOSUPPLEMENTATION IN ANKLE OSTEOARTHRITIS: A SYSTEMATIC REVIEW.

    PubMed

    Faleiro, Thiago Batista; Schulz, Renata da Silva; Jambeiro, Jorge Eduardo de Schoucair; Tavares, Antero; Delmonte, Fernando Moreira; Daltro, Gildásio de Cerqueira

    2016-01-01

    To evaluate the efficacy of viscosupplementation in patients with osteoarthritis of the ankle. A systematic review to evaluate the evidence in the literature on the use of viscosupplementation for osteoarthritis of the ankle. For this review, we considered blind randomized prospective studies involving the use of viscosupplementation for osteoarthritis of the ankle. A total of 1,961 articles were identified in various databases. After examining each of the articles, five articles were included in this review. Treatment with intraarticular hyaluronic acid is a safe treatment modality that significantly improves functional scores of patients, with no evidence of superiority in relation to other conservative treatments. Further clinical trials with larger numbers of patients are needed so that we can recommend its use and address unanswered questions . Systematic Review of Randomized Clinical Trials.

  19. Bilateral ankle edema with bilateral iritis.

    PubMed

    Kumar, Sunil

    2007-07-01

    I report two patient presented to me with bilateral symmetrical ankle edema and bilateral acute iritis. A 42-year-old female of Indian origin and 30-year-old female from Somalia both presented with bilateral acute iritis. In the first patient, bilateral ankle edema preceded the onset of bilateral acute iritis. Bilateral ankle edema developed during the course of disease after onset of ocular symptoms in the second patient. Both patients did not suffer any significant ocular problem in the past, and on systemic examination, all clinical parameters were within normal limit. Lacrimal gland and conjunctival nodule biopsy established the final diagnosis of sarcoidosis in both cases, although the chest x-rays were normal.

  20. A study of the interaction between motoneurones in the frog spinal cord

    PubMed Central

    Grinnell, A. D.

    1966-01-01

    1. A short-latency interaction between motoneurones has been studied with intracellular and root potential recordings from the isolated spinal cord of the frog. Antidromic stimulation of one ventral root causes brief depolarization (VR-EPSP) of the motoneurones of adjacent, non-excited motoneurones. The summed activity of many such VR-EPSPs can be seen as a brief depolarization (VR-VRP) passing out an adjacent ventral root. 2. Both intracellular and root-recorded signs of this interaction are graded in amplitude. 3. It was found that this interaction decreased with increasing temperature. This is in contrast to the behaviour of the ventral root potential resulting from dorsal root stimulation (DR-VRP) or the dorsal root potentials resulting from either dorsal root (DR-DRP) or ventral root (VR-DRP) stimulation, all of which increased in amplitude from below 10 to about 17° C. 4. Pharmacological evidence suggests that the interaction between motoneurones is not chemically mediated. The VR-VRP was not affected by a large variety of transmitter blocking agents, including curare, dihydro-β-erythroidine, atropine, succinylcholine, hexamethonium and DOPA, while the VR-DRP, which probably originates with the release of ACh from an axon collateral, was consistently blocked. 5. Mg2+ suppressed the VR-VRP more slowly than the other potentials, and this suppression was increased by adding Ca2+, rather than reversed, as in the case of the other root potentials, which are presumably mediated by chemical transmission. 6. The interaction between motoneurones is strongly facilitated by orthodromic depolarization of the motoneurones being antidromically stimulated. Extracellular recordings within the cord support the conclusion that this facilitation is a result of the enhancement of antidromic invasion, perhaps especially of the dendrites, by slight depolarization. 7. One VR-VRP (or VR-EPSP) first suppresses response to another (for about 10 msec), then facilitates response to

  1. Acute stimulation of transplanted neurons improves motoneuron survival, axon growth, and muscle reinnervation.

    PubMed

    Grumbles, Robert M; Liu, Yang; Thomas, Christie M; Wood, Patrick M; Thomas, Christine K

    2013-06-15

    Few options exist for treatment of pervasive motoneuron death after spinal cord injury or in neurodegenerative diseases such as amyotrophic lateral sclerosis. Local transplantation of embryonic motoneurons into an axotomized peripheral nerve is a promising approach to arrest the atrophy of denervated muscles; however, muscle reinnervation is limited by poor motoneuron survival. The aim of the present study was to test whether acute electrical stimulation of transplanted embryonic neurons promotes motoneuron survival, axon growth, and muscle reinnervation. The sciatic nerve of adult Fischer rats was transected to mimic the widespread denervation seen after disease or injury. Acutely dissociated rat embryonic ventral spinal cord cells were transplanted into the distal tibial nerve stump as a neuron source for muscle reinnervation. Immediately post-transplantation, the cells were stimulated at 20 Hz for 1 h. Other groups were used to control for the cell transplantation and stimulation. When neurons were stimulated acutely, there were significantly more neurons, including cholinergic neurons, 10 weeks after transplantation. This led to enhanced numbers of myelinated axons, reinnervation of more muscle fibers, and more medial and lateral gastrocnemius muscles were functionally connected to the transplant. Reinnervation reduced muscle atrophy significantly. These data support the concept that electrical stimulation rescues transplanted motoneurons and facilitates muscle reinnervation.

  2. Postsynaptic muscarinic m2 receptors at cholinergic and glutamatergic synapses of mouse brainstem motoneurons.

    PubMed

    Csaba, Zsolt; Krejci, Eric; Bernard, Véronique

    2013-06-15

    In many brain areas, few cholinergic synapses are identified. Acetylcholine is released into the extracellular space and acts through diffuse transmission. Motoneurons, however, are contacted by numerous cholinergic terminals, indicating synaptic cholinergic transmission on them. The muscarinic m2 receptor is the major acetylcholine receptor subtype of motoneurons; therefore, we analyzed the localization of the m2 receptor in correlation with synapses by electron microscopic immunohistochemistry in the mouse trigeminal, facial, and hypoglossal motor nuclei. In all nuclei, m2 receptors were localized at the membrane of motoneuronal perikarya and dendrites. The m2 receptors were concentrated at cholinergic synapses located on the perikarya and most proximal dendrites. However, m2 receptors at cholinergic synapses represented only a minority (<10%) of surface m2 receptors. The m2 receptors were also enriched at glutamatergic synapses in both motoneuronal perikarya and dendrites. A relatively large proportion (20-30%) of plasma membrane-associated m2 receptors were located at glutamatergic synapses. In conclusion, the effect of acetylcholine on motoneuron populations might be mediated through a synaptic as well as diffuse type of transmission.

  3. A perimotor framework reveals functional segmentation in the motoneuronal network controlling locomotion in Caenorhabditis elegans.

    PubMed

    Haspel, Gal; O'Donovan, Michael J

    2011-10-12

    The neuronal connectivity dataset of the nematode Caenorhabditis elegans attracts wide attention from computational neuroscientists and experimentalists. However, the dataset is incomplete. The ventral and dorsal nerve cords of a single nematode were reconstructed halfway along the body and the posterior data are missing, leaving 21 of 75 motoneurons of the locomotor network with partial or no connectivity data. Using a new framework for network analysis, the perimotor space, we identified rules of connectivity that allowed us to approximate the missing data by extrapolation. Motoneurons were mapped into perimotor space in which each motoneuron is located according to the muscle cells it innervates. In this framework, a pattern of iterative connections emerges which includes most (0.90) of the connections. We identified a repeating unit consisting of 12 motoneurons and 12 muscle cells. The cell bodies of the motoneurons of such a unit are not necessarily anatomical neighbors and there is no obvious anatomical segmentation. A connectivity model, composed of six repeating units, is a description of the network that is both simplified (modular and without noniterative connections) and more complete (includes the posterior part) than the original dataset. The perimotor framework of observed connectivity and the segmented connectivity model give insights and advance the study of the neuronal infrastructure underlying locomotion in C. elegans. Furthermore, we suggest that the tools used herein may be useful to interpret, simplify, and represent connectivity data of other motor systems.

  4. Adenosine-mediated modulation of ventral horn interneurons and spinal motoneurons in neonatal mice

    PubMed Central

    Witts, Emily C.; Nascimento, Filipe

    2015-01-01

    Neuromodulation allows neural networks to adapt to varying environmental and biomechanical demands. Purinergic signaling is known to be an important modulatory system in many parts of the CNS, including motor control circuitry. We have recently shown that adenosine modulates the output of mammalian spinal locomotor control circuitry (Witts EC, Panetta KM, Miles GB. J Neurophysiol 107: 1925–1934, 2012). Here we investigated the cellular mechanisms underlying this adenosine-mediated modulation. Whole cell patch-clamp recordings were performed on ventral horn interneurons and motoneurons within in vitro mouse spinal cord slice preparations. We found that adenosine hyperpolarized interneurons and reduced the frequency and amplitude of synaptic inputs to interneurons. Both effects were blocked by the A1-type adenosine receptor antagonist DPCPX. Analysis of miniature postsynaptic currents recorded from interneurons revealed that adenosine reduced their frequency but not amplitude, suggesting that adenosine acts on presynaptic receptors to modulate synaptic transmission. In contrast to interneurons, recordings from motoneurons revealed an adenosine-mediated depolarization. The frequency and amplitude of synaptic inputs to motoneurons were again reduced by adenosine, but we saw no effect on miniature postsynaptic currents. Again these effects on motoneurons were blocked by DPCPX. Taken together, these results demonstrate differential effects of adenosine, acting via A1 receptors, in the mouse spinal cord. Adenosine has a general inhibitory action on ventral horn interneurons while potentially maintaining motoneuron excitability. This may allow for adaptation of the locomotor pattern generated by interneuronal networks while helping to ensure the maintenance of overall motor output. PMID:26311185

  5. Uncoupling nicotine mediated motoneuron axonal pathfinding errors and muscle degeneration in zebrafish

    SciTech Connect

    Welsh, Lillian; Tanguay, Robert L.; Svoboda, Kurt R.

    2009-05-15

    Zebrafish embryos offer a unique opportunity to investigate the mechanisms by which nicotine exposure impacts early vertebrate development. Embryos exposed to nicotine become functionally paralyzed by 42 hpf suggesting that the neuromuscular system is compromised in exposed embryos. We previously demonstrated that secondary spinal motoneurons in nicotine-exposed embryos were delayed in development and that their axons made pathfinding errors (Svoboda, K.R., Vijayaraghaven, S., Tanguay, R.L., 2002. Nicotinic receptors mediate changes in spinal motoneuron development and axonal pathfinding in embryonic zebrafish exposed to nicotine. J. Neurosci. 22, 10731-10741). In that study, we did not consider the potential role that altered skeletal muscle development caused by nicotine exposure could play in contributing to the errors in spinal motoneuron axon pathfinding. In this study, we show that an alteration in skeletal muscle development occurs in tandem with alterations in spinal motoneuron development upon exposure to nicotine. The alteration in the muscle involves the binding of nicotine to the muscle-specific AChRs. The nicotine-induced alteration in muscle development does not occur in the zebrafish mutant (sofa potato, [sop]), which lacks muscle-specific AChRs. Even though muscle development is unaffected by nicotine exposure in sop mutants, motoneuron axonal pathfinding errors still occur in these mutants, indicating a direct effect of nicotine exposure on nervous system development.

  6. Adenosine-mediated modulation of ventral horn interneurons and spinal motoneurons in neonatal mice.

    PubMed

    Witts, Emily C; Nascimento, Filipe; Miles, Gareth B

    2015-10-01

    Neuromodulation allows neural networks to adapt to varying environmental and biomechanical demands. Purinergic signaling is known to be an important modulatory system in many parts of the CNS, including motor control circuitry. We have recently shown that adenosine modulates the output of mammalian spinal locomotor control circuitry (Witts EC, Panetta KM, Miles GB. J Neurophysiol 107: 1925-1934, 2012). Here we investigated the cellular mechanisms underlying this adenosine-mediated modulation. Whole cell patch-clamp recordings were performed on ventral horn interneurons and motoneurons within in vitro mouse spinal cord slice preparations. We found that adenosine hyperpolarized interneurons and reduced the frequency and amplitude of synaptic inputs to interneurons. Both effects were blocked by the A1-type adenosine receptor antagonist DPCPX. Analysis of miniature postsynaptic currents recorded from interneurons revealed that adenosine reduced their frequency but not amplitude, suggesting that adenosine acts on presynaptic receptors to modulate synaptic transmission. In contrast to interneurons, recordings from motoneurons revealed an adenosine-mediated depolarization. The frequency and amplitude of synaptic inputs to motoneurons were again reduced by adenosine, but we saw no effect on miniature postsynaptic currents. Again these effects on motoneurons were blocked by DPCPX. Taken together, these results demonstrate differential effects of adenosine, acting via A1 receptors, in the mouse spinal cord. Adenosine has a general inhibitory action on ventral horn interneurons while potentially maintaining motoneuron excitability. This may allow for adaptation of the locomotor pattern generated by interneuronal networks while helping to ensure the maintenance of overall motor output.

  7. Selective reinnervation of transplanted muscles by their original motoneurons in the axolotl.

    PubMed

    Wigston, D J; Kennedy, P R

    1987-06-01

    The motoneurons innervating 3 hindlimb extensor muscles, anterior and posterior iliotibialis and iliofibularis, were studied separately by retrograde labeling with HRP. The motor pools for these 3 muscles overlapped to such an extent that individual motoneurons between ventral roots 16 and 17 could not be assigned unambiguously to one pool or another. Thus, conventional retrograde labeling could not identify particular axolotl motoneurons. Instead, a double retrograde-labeling technique was employed to mark the motoneurons innervating a particular muscle, the left posterior iliotibialis. Either diamidino yellow (DY) or HRP satisfactorily labeled axolotl motoneurons for at least 3 months in vivo. After labeling, both anterior and posterior iliotibialis muscles were removed from the injected limb and replaced with their counterparts from the opposite limb, in reversed anterior-posterior orientation. Several weeks later, a second marker (DY or HRP) injected into the posterior iliotibialis muscle in its new, more anterior, position labeled the neurons that reinnervated this muscle; the number of neurons labeled with both first and second tracers gave an indication of the selectivity of reinnervation. Using this approach, we have found that the majority of neurons reinnervating a particular muscle are members of that muscle's original motor pool.

  8. Management of Osseous and Soft-Tissue Ankle Equinus During Total Ankle Replacement.

    PubMed

    Roukis, Thomas S; Simonson, Devin C

    2015-10-01

    Obtaining functional alignment of a total ankle replacement, including physiologic sagittal plane range of motion, is paramount for a successful outcome. This article reviews the literature on techniques available for correction of osseous and soft-tissue equinus at the time of index total ankle replacement. These techniques include anterior tibiotalar joint cheilectomy, posterior superficial muscle compartment lengthening, posterior ankle capsule release, and release of the posterior portions of the medial and lateral collateral ligament complexes. The rationale for these procedures and the operative sequence of events for these procedures are presented.

  9. Foot and Ankle Injuries in American Football.

    PubMed

    Hsu, Andrew R; Anderson, Robert B

    Physicians need to be aware of a variety of foot and ankle injuries that commonly occur in American football, including turf toe, Jones fractures, Lisfranc injuries, syndesmotic and deltoid disruption, and Achilles ruptures. These injuries are often complex and require early individual tailoring of treatment and rehabilitation protocols. Successful management and return to play requires early diagnosis, a thorough work-up, and prompt surgical intervention when warranted with meticulous attention to restoration of normal foot and ankle anatomy. Physicians should have a high suspicion for subtle injuries and variants that can occur via both contact and noncontact mechanisms.

  10. Dietary and viscosupplementation in ankle arthritis.

    PubMed

    Khosla, Shaun K; Baumhauer, Judith F

    2008-09-01

    Glucosamine and chondroitin sulfate are the most well-marketed dietary supplements directed toward managing symptoms associated with osteoarthritis. The presumption of their benefit in the ankle is based largely on promising results from their use in knee osteoarthritis. Likewise, viscosupplementation has proved to be efficacious in the management of osteoarthritis of the knee. Preliminary studies demonstrate a realization of this benefit in the ankle joint, but further research is required. So far, the literature has shown the dietary and viscosupplementation discussed in this article to be relatively safe for use.

  11. Ankle injuries. Tips from sports medicine physicians.

    PubMed

    Swain, R A; Holt, W S

    1993-02-15

    In dealing with an ankle sprain, worrisome features are few but important to recognize. A "pop" heard or felt at the time of injury, a prolonged course, or a history of several previous injuries are all of concern. Medial tenderness on palpation, positive results on a squeeze test, or markedly positive results on stress testing are also indicators of severe injuries, which may require referral for treatment. Stress testing by an experienced clinician is appropriate for chronic or severe cases. Otherwise, treatment of the acute, uncomplicated ankle injury is straightforward, focusing on early mobilization, rehabilitation, and protection.

  12. Acceleration dependence and task-specific modulation of short- and medium-latency reflexes in the ankle extensors.

    PubMed

    Finley, James M; Dhaher, Yasin Y; Perreault, Eric J

    2013-08-01

    Involuntary responses to muscle stretch are often composed of a short-latency reflex (SLR) and more variable responses at longer latencies such as the medium-latency (MLR) and long-latency stretch reflex (LLR). Although longer latency reflexes are enhanced in the upper limb during stabilization of external loads, it remains unknown if they have a similar role in the lower limb. This uncertainty results in part from the inconsistency with which longer latency reflexes have been observed in the lower limb. A review of the literature suggests that studies that only observe SLRs have used perturbations with large accelerations, possibly causing a synchronization of motoneuron refractory periods or an activation of force-dependent inhibition. We therefore hypothesized that the amplitude of longer latency reflexes would vary with perturbation acceleration. We further hypothesized that if longer latency reflexes were elicited, they would increase in amplitude during control of an unstable load, as has been observed in the upper limb. These hypotheses were tested at the ankle while subjects performed a torque or position control task. SLR and MLR reflex components were elicited by ankle flexion perturbations with a fixed peak velocity and variable acceleration. Both reflex components initially scaled with acceleration, however, while the SLR continued to increase at high accelerations, the MLR weakened. At accelerations that reliably elicited MLRs, both the SLR and MLR were reduced during control of the unstable load. These findings clarify the conditions required to elicit MLRs in the ankle extensors and provide additional evidence that rapid feedback pathways are downregulated when stability is compromised in the lower limb.

  13. Acceleration dependence and task-specific modulation of short- and medium-latency reflexes in the ankle extensors

    PubMed Central

    Finley, James M; Dhaher, Yasin Y; Perreault, Eric J

    2013-01-01

    Involuntary responses to muscle stretch are often composed of a short-latency reflex (SLR) and more variable responses at longer latencies such as the medium-latency (MLR) and long-latency stretch reflex (LLR). Although longer latency reflexes are enhanced in the upper limb during stabilization of external loads, it remains unknown if they have a similar role in the lower limb. This uncertainty results in part from the inconsistency with which longer latency reflexes have been observed in the lower limb. A review of the literature suggests that studies that only observe SLRs have used perturbations with large accelerations, possibly causing a synchronization of motoneuron refractory periods or an activation of force-dependent inhibition. We therefore hypothesized that the amplitude of longer latency reflexes would vary with perturbation acceleration. We further hypothesized that if longer latency reflexes were elicited, they would increase in amplitude during control of an unstable load, as has been observed in the upper limb. These hypotheses were tested at the ankle while subjects performed a torque or position control task. SLR and MLR reflex components were elicited by ankle flexion perturbations with a fixed peak velocity and variable acceleration. Both reflex components initially scaled with acceleration, however, while the SLR continued to increase at high accelerations, the MLR weakened. At accelerations that reliably elicited MLRs, both the SLR and MLR were reduced during control of the unstable load. These findings clarify the conditions required to elicit MLRs in the ankle extensors and provide additional evidence that rapid feedback pathways are downregulated when stability is compromised in the lower limb. PMID:24303134

  14. [Back to the emergency department with a painful ankle].

    PubMed

    van Egmond, Pim W; van de Rest, Hendrik J M; Nolte, Peter A

    2014-01-01

    A 31-year-old woman came to the Emergency Department with a painful ankle 2 days after a fall off a horse. On the day of the accident, she was misdiagnosed with a lateral ankle sprain. A lateral X-ray of the ankle showed a positive 'V-sign', which is pathognomonic for a fracture of the lateral process of the talus.

  15. Mild Hyperbaric Oxygen Improves Decreased Oxidative Capacity of Spinal Motoneurons Innervating the Soleus Muscle of Rats with Type 2 Diabetes.

    PubMed

    Takemura, Ai; Ishihara, Akihiko

    2016-09-01

    Rats with type 2 diabetes exhibit decreased oxidative capacity, such as reduced oxidative enzyme activity, low-intensity staining for oxidative enzymes in fibers, and no high-oxidative type IIA fibers, in the skeletal muscle, especially in the soleus muscle. In contrast, there are no data available concerning the oxidative capacity of spinal motoneurons innervating skeletal muscle of rats with type 2 diabetes. This study examined the oxidative capacity of motoneurons innervating the soleus muscle of non-obese rats with type 2 diabetes. In addition, this study examined the effects of mild hyperbaric oxygen at 1.25 atmospheres absolute with 36 % oxygen for 10 weeks on the oxidative capacity of motoneurons innervating the soleus muscle because mild hyperbaric oxygen improves the decreased oxidative capacity of the soleus muscle in non-obese rats with type 2 diabetes. Spinal motoneurons innervating the soleus muscle were identified using nuclear yellow, a retrograde fluorescent neuronal tracer. Thereafter, the cell body sizes and succinate dehydrogenase activity of identified motoneurons were analyzed. Decreased succinate dehydrogenase activity of small-sized alpha motoneurons innervating the soleus muscle was observed in rats with type 2 diabetes. The decreased succinate dehydrogenase activity of these motoneurons was improved by mild hyperbaric oxygen. Therefore, we concluded that rats with type 2 diabetes have decreased oxidative capacity in motoneurons innervating the soleus muscle and this decreased oxidative capacity is improved by mild hyperbaric oxygen.

  16. Motor activity in the isolated spinal cord of the chick embryo: synaptic drive and firing pattern of single motoneurons.

    PubMed

    O'Donovan, M J

    1989-03-01

    The cellular mechanisms underlying embryonic motility were investigated using intracellular recording from motoneurons and electrotonic recording from muscle nerves during motor activity generated by an isolated spinal cord preparation of 12- to 15-d-old chick embryos. DC-coupled recordings from sartorius (a flexor) and femorotibialis (an extensor) muscle nerves revealed that both sets of motoneurons were depolarized at the same time in each cycle even when the motoneurons fired out of phase. Sartorius motoneurons fired briefly on the rising phase of the depolarization and then stopped firing before discharging a second burst of spikes as the depolarization decayed. By contrast, femorotibialis motoneurons fired at the peak of their depolarization, which was coincident with the interruption in sartorius activity. Intracellular recordings from antidromically identified motoneurons confirmed that flexor and extensor motoneurons were depolarized at the same time during each cycle of activity. The discharge of femorotibialis motoneurons, and others presumed to be extensors, followed changes in membrane potential so that maximal firing occurred during peak depolarization. The relationship between discharge and membrane potential was different in sartorius motoneurons (and in others presumed to be flexors) because they fired briefly on the rising phase of the depolarization and then stopped firing during peak depolarization. In some of these cells firing resumed as the membrane potential decayed back to rest. Intracellular injection of depolarizing current into sartorius motoneurons during motor activity reversed the direction of the membrane potential change from depolarizing to hyperpolarizing during the pause in sartorius discharge. In addition, the discharge evoked by the depolarizing current was blocked during the reversed part of the synaptic potential revealing its inhibitory nature. The occurrence of the IPSP was accompanied by a large reduction in motoneuronal

  17. Neuroplasticity and Repair in Rodent Neurotoxic Models of Spinal Motoneuron Disease

    PubMed Central

    Gulino, Rosario

    2016-01-01

    Retrogradely transported toxins are widely used to set up protocols for selective lesioning of the nervous system. These methods could be collectively named “molecular neurosurgery” because they are able to destroy specific types of neurons by using targeted neurotoxins. Lectins such as ricin, volkensin, or modeccin and neuropeptide- or antibody-conjugated saporin represent the most effective toxins used for neuronal lesioning. Some of these specific neurotoxins could be used to induce selective depletion of spinal motoneurons. In this review, we extensively describe two rodent models of motoneuron degeneration induced by volkensin or cholera toxin-B saporin. In particular, we focus on the possible experimental use of these models to mimic neurodegenerative diseases, to dissect the molecular mechanisms of neuroplastic changes underlying the spontaneous functional recovery after motoneuron death, and finally to test different strategies of neural repair. The potential clinical applications of these approaches are also discussed. PMID:26862439

  18. Analyzing the Effects of Gap Junction Blockade on Neural Synchrony via a Motoneuron Network Computational Model

    PubMed Central

    Memelli, Heraldo; Horn, Kyle G.; Wittie, Larry D.; Solomon, Irene C.

    2012-01-01

    In specific regions of the central nervous system (CNS), gap junctions have been shown to participate in neuronal synchrony. Amongst the CNS regions identified, some populations of brainstem motoneurons are known to be coupled by gap junctions. The application of various gap junction blockers to these motoneuron populations, however, has led to mixed results regarding their synchronous firing behavior, with some studies reporting a decrease in synchrony while others surprisingly find an increase in synchrony. To address this discrepancy, we employ a neuronal network model of Hodgkin-Huxley-style motoneurons connected by gap junctions. Using this model, we implement a series of simulations and rigorously analyze their outcome, including the calculation of a measure of neuronal synchrony. Our simulations demonstrate that under specific conditions, uncoupling of gap junctions is capable of producing either a decrease or an increase in neuronal synchrony. Subsequently, these simulations provide mechanistic insight into these different outcomes. PMID:23365560

  19. Effectiveness of an outside-the-boot ankle brace in reducing parachuting related ankle injuries

    PubMed Central

    Schmidt, M; Sulsky, S; Amoroso, P

    2005-01-01

    Objectives: To examine the efficacy of an outside-the-boot parachute ankle brace (PAB) in reducing risk of ankle injury to army paratrooper trainees and to identify inadvertent risks associated with PAB use. Design: The authors compared hospitalization rates for ankle, musculoskeletal, and other traumatic injury among 223 172 soldiers trained 1985–2002 in time periods defined by presence/absence of PAB use protocols. Multiple logistic regression analysis estimated adjusted odds ratios (OR) and 95% confidence intervals for injury outcomes, comparing pre and post brace periods to the brace protocol period. Setting: A research database consisting of training rosters from the US Army Airborne training facility (Fort Benning, GA) occupational, demographic, and hospitalization information. Main outcome measures: Injuries were considered training related if they occurred during a five week period starting with first scheduled static line parachute jump and a parachuting cause of injury code appeared in the hospital record. Results: Of 939 parachuting related hospitalizations during the defined risk period, 597 (63.6%) included an ankle injury diagnosis, 198 (21.1%) listed a musculoskeletal (non-ankle) injury, and 69 (7.3%) cited injuries to multiple body parts. Risk of ankle injury hospitalization was higher during both pre-brace (adjusted OR 2.38, 95% CI 1.92 to 2.95) and post-brace (adjusted OR 1.72, 95% CI 1.27 to 2.32) periods compared with the brace protocol period. Odds of musculoskeletal (non-ankle) injury or injury to multiple body parts did not change between the brace and post-brace periods. Conclusion: Use of a PAB during airborne training appears to reduce risk of ankle injury without increasing risk of other types of traumatic injury. PMID:15933409

  20. Calcium dynamics and buffering in motoneurones of the mouse spinal cord

    PubMed Central

    Palecek, Jiri; Lips, Mario B; Keller, Bernhard U

    1999-01-01

    A quantitative analysis of endogenous calcium homeostasis was performed on 65 motoneurones in slices of the lumbar spinal cord from 2- to 8-day-old mice by simultaneous patch-clamp and microfluorometric calcium measurements. Somatic calcium concentrations were monitored with a temporal resolution in the millisecond time domain. Measurements were performed by using a monochromator for excitation and a photomultiplier detection system. Somatic calcium signalling was investigated during defined voltage-clamp protocols. Calcium responses were observed for membrane depolarizations positive to −50 mV. A linear relation between depolarization time and free calcium concentrations ([Ca2+]i) indicated that voltage-dependent calcium influx dominated the response. Endogenous calcium homeostasis was quantified by using the ‘added buffer’ approach. In the presence of fura-2 and mag-fura-5, calcium transients decayed according to a monoexponential function. Decay-time constants showed a linear dependence on dye concentration and the extrapolated constant in the absence of indicator dye was 371 ± 120 ms (n= 13 cells, 21 °C). For moderate elevations (< 1 μm), recovery kinetics of depolarization-induced calcium transients were characterized by a calcium-independent, ‘effective’ extrusion rate γ = 140 ± 47 s−1 (n= 13 cells, 21 °C). The endogenous calcium binding ratio for fixed buffers in spinal motoneurones was κB’ = 50 ± 17 (n= 13 cells), indicating that less than 2% of cytosolic calcium ions contributed to [Ca2+]i. Endogenous binding ratios in spinal motoneurones were small compared to those found in hippocampal or cerebellar Purkinje neurones. From a functional perspective, they provided motoneurones with rapid dynamics of cytosolic [Ca2+]i for a given set of influx, extrusion and uptake mechanisms. With respect to pathophysiological conditions, our measurements are in agreement with a model where the selective vulnerability of spinal motoneurones during

  1. Retrograde Gene Delivery to Hypoglossal Motoneurons Using Adeno-Associated Virus Serotype 9

    PubMed Central

    ElMallah, Mai K.; Falk, Darin J.; Lane, Michael A.; Conlon, Thomas J.; Lee, Kun-Ze; Shafi, Nadeem I.; Reier, Paul J.

    2012-01-01

    Abstract Retrograde viral transport (i.e., muscle to motoneuron) enables targeted gene delivery to specific motor pools. Recombinant adeno-associated virus serotype 9 (AAV9) robustly infects motoneurons, but the retrograde transport capabilities of AAV9 have not been systematically evaluated. Accordingly, we evaluated the retrograde transduction efficiency of AAV9 after direct tongue injection in 129SVE mice as well as a mouse model that displays neuromuscular pathology (Gaa−/−). Hypoglossal (XII) motoneurons were histologically evaluated 8 weeks after tongue injection with AAV9 encoding green fluorescent protein (GFP) with expression driven by the chicken β-actin promoter (1×1011 vector genomes). On average, GFP expression was detected in 234±43 XII motoneurons 8 weeks after AAV9-GFP tongue injection. In contrast, tongue injection with a highly efficient retrograde anatomical tracer (cholera toxin β subunit, CT-β) resulted in infection of 818±88 XII motoneurons per mouse. The retrograde transduction efficiency of AAV9 was similar between the 129SVE mice and those with neuromuscular disease (Gaa−/−). Routine hematoxylin and eosin staining and cluster of differentiation (CD) immunostaining for T cells (CD3) indicated no persistent inflammation within the tongue or XII nucleus after AAV9 injection. Additional experiments indicated no adverse effects of AAV9 on the pattern of breathing. We conclude that AAV9 can retrogradely infect a significant portion of a given motoneuron pool in normal and dystrophic mice, and that its transduction efficiency is approximately 30% of what can be achieved with CT-β. PMID:22693957

  2. Morphology of motoneurons in different subdivisions of the rat facial nucleus stained intracellularly with horseradish peroxidase.

    PubMed

    Friauf, E

    1986-11-08

    Horseradish peroxidase was injected into single facial motoneurons of the rat. Neurons were identified by antidromic stimulation of either the buccal or the marginal mandibular or the posterior auricular nerve branches. Motoneuronal cell bodies supplying the buccal branch were located in the lateral subdivision of the facial nucleus, those supplying the marginal mandibular branch were in the intermediate subdivision, and those supplying the posterior auricular branch were in the medial subdivision. Eleven motoneurons were reconstructed with a computer-assisted technique. Their soma diameters averaged 20 microns; the average number of primary dendrites was 7.9 and the combined lengths of the dendritic trees averaged 17,650 microns. There was no distinction between the three motoneuron groups in terms of these and other quantitative data. However, on the basis of reconstructed dendritic tree orientation (i.e., dendritic distribution), major differences were observed between motoneurons of the three groups. Dendrites from all groups extended beyond the boundaries of the facial nucleus into the reticular formation. The border between the intermediate and the lateral subdivision was crossed by some dendrites but the overlap was small. In contrast, no dendrite of a motoneuron in the medial subdivision entered the intermediate subdivision and vice versa. The dendritic extent was totally restricted by the borders between these two subdivisions. Outside the Nissl-defined nuclear border, however, dendrites from cells in adjacent subdivisions overlapped. It is concluded that the medial subdivision of the facial nucleus can be distinguished from the intermediate and lateral subdivisions not only by its sharp Nissl-defined border but also by the discrete organization of its dendritic field.

  3. Non-Cell-Autonomous Regulation of Retrograde Motoneuronal Axonal Transport in an SBMA Mouse Model

    PubMed Central

    Halievski, Katherine; Kemp, Michael Q.; Breedlove, S. Marc; Miller, Kyle E.

    2016-01-01

    Abstract Defects in axonal transport are seen in motoneuronal diseases, but how that impairment comes about is not well understood. In spinal bulbar muscular atrophy (SBMA), a disorder linked to a CAG/polyglutamine repeat expansion in the androgen receptor (AR) gene, the disease-causing AR disrupts axonal transport by acting in both a cell-autonomous fashion in the motoneurons themselves, and in a non-cell-autonomous fashion in muscle. The non-cell-autonomous mechanism is suggested by data from a unique “myogenic” transgenic (TG) mouse model in which an AR transgene expressed exclusively in skeletal muscle fibers triggers an androgen-dependent SBMA phenotype, including defects in retrograde transport. However, motoneurons in this TG model retain the endogenous AR gene, leaving open the possibility that impairments in transport in this model also depend on ARs in the motoneurons themselves. To test whether non-cell-autonomous mechanisms alone can perturb retrograde transport, we generated male TG mice in which the endogenous AR allele has the testicular feminization mutation (Tfm) and, consequently, is nonfunctional. Males carrying the Tfm allele alone show no deficits in motor function or axonal transport, with or without testosterone treatment. However, when Tfm males carrying the myogenic transgene (Tfm/TG) are treated with testosterone, they develop impaired motor function and defects in retrograde transport, having fewer retrogradely labeled motoneurons and deficits in endosomal flux based on time-lapse video microscopy of living axons. These findings demonstrate that non-cell-autonomous disease mechanisms originating in muscle are sufficient to induce defects in retrograde transport in motoneurons. PMID:27517091

  4. Non-Cell-Autonomous Regulation of Retrograde Motoneuronal Axonal Transport in an SBMA Mouse Model.

    PubMed

    Halievski, Katherine; Kemp, Michael Q; Breedlove, S Marc; Miller, Kyle E; Jordan, Cynthia L

    2016-01-01

    Defects in axonal transport are seen in motoneuronal diseases, but how that impairment comes about is not well understood. In spinal bulbar muscular atrophy (SBMA), a disorder linked to a CAG/polyglutamine repeat expansion in the androgen receptor (AR) gene, the disease-causing AR disrupts axonal transport by acting in both a cell-autonomous fashion in the motoneurons themselves, and in a non-cell-autonomous fashion in muscle. The non-cell-autonomous mechanism is suggested by data from a unique "myogenic" transgenic (TG) mouse model in which an AR transgene expressed exclusively in skeletal muscle fibers triggers an androgen-dependent SBMA phenotype, including defects in retrograde transport. However, motoneurons in this TG model retain the endogenous AR gene, leaving open the possibility that impairments in transport in this model also depend on ARs in the motoneurons themselves. To test whether non-cell-autonomous mechanisms alone can perturb retrograde transport, we generated male TG mice in which the endogenous AR allele has the testicular feminization mutation (Tfm) and, consequently, is nonfunctional. Males carrying the Tfm allele alone show no deficits in motor function or axonal transport, with or without testosterone treatment. However, when Tfm males carrying the myogenic transgene (Tfm/TG) are treated with testosterone, they develop impaired motor function and defects in retrograde transport, having fewer retrogradely labeled motoneurons and deficits in endosomal flux based on time-lapse video microscopy of living axons. These findings demonstrate that non-cell-autonomous disease mechanisms originating in muscle are sufficient to induce defects in retrograde transport in motoneurons.

  5. Failure modes of current total ankle replacement systems.

    PubMed

    Pappas, Michael J; Buechel, Frederick F

    2013-04-01

    Methodology for evaluation of total ankle replacements is described. Fusion and its problems are discussed as are those of total ankle joint replacement. Fusion is an imperfect solution because it reduces ankle functionality and has significant complications. Early fixed-bearing total ankles were long-term failures and abandoned. Currently available fixed-bearing ankles have proved inferior to fusion or are equivalent to earlier devices. Only mobile-bearing devices have been shown reasonably safe and effective. One such device, the STAR, has been approved by the Food and Drug Administration after a rigorous controlled clinical trial and is available for use in the United States.

  6. Malignant melanoma of the foot and ankle.

    PubMed

    John, K J; Hayes, D W; Green, D R; Dickerson, J

    2000-04-01

    Malignant melanoma is a serious and devastating skin disease that podiatrists may be called upon to treat. It is pertinent that delays in diagnosis and treatment of malignant melanoma be avoided. Some of the topics discussed in this article are causes, clinical features, classification, and treatment of malignant melanoma, focusing on the foot and ankle.

  7. Treatment algorithm for chronic lateral ankle instability

    PubMed Central

    Giannini, Sandro; Ruffilli, Alberto; Pagliazzi, Gherardo; Mazzotti, Antonio; Evangelisti, Giulia; Buda, Roberto; Faldini, Cesare

    2014-01-01

    Summary Introduction: ankle sprains are a common sports-related injury. A 20% of acute ankle sprains results in chronic ankle instability, requiring surgery. Aim of this paper is to report the results of a series of 38 patients treated for chronic lateral ankle instability with anatomic reconstruction. Materials and methods: thirty-eight patients were enrolled in the study. Seventeen patients underwent a surgical repair using the Brostrom-modified technique, while the remaining underwent anatomic reconstruction with autologous or allogenic graft. Results: at a mean follow-up of 5 years the AOFAS score improved from 66.1 ± 5.3 to 92.2 ± 5.6. Discussion: the findings of this study confirm that anatomic reconstruction is an effective procedure with satisfactory subjective and objective results which persist at long-term follow-up along with a low complication rate. No differences, in term of clinical and functional outcomes, were observed between the Brostrom-modified repair and the anatomic reconstruction technique. Level of evidence: level IV. PMID:25767783

  8. Invariant ankle moment patterns when walking with and without a robotic ankle exoskeleton.

    PubMed

    Kao, Pei-Chun; Lewis, Cara L; Ferris, Daniel P

    2010-01-19

    To guide development of robotic lower limb exoskeletons, it is necessary to understand how humans adapt to powered assistance. The purposes of this study were to quantify joint moments while healthy subjects adapted to a robotic ankle exoskeleton and to determine if the period of motor adaptation is dependent on the magnitude of robotic assistance. The pneumatically powered ankle exoskeleton provided plantar flexor torque controlled by the wearer's soleus electromyography (EMG). Eleven naïve individuals completed two 30-min sessions walking on a split-belt instrumented treadmill at 1.25m/s while wearing the ankle exoskeleton. After two sessions of practice, subjects reduced their soleus EMG activation by approximately 36% and walked with total ankle moment patterns similar to their unassisted gait (r(2)=0.98+/-0.02, THSD, p>0.05). They had substantially different ankle kinematic patterns compared to their unassisted gait (r(2)=0.79+/-0.12, THSD, p<0.05). Not all of the subjects reached a steady-state gait pattern within the two sessions, in contrast to a previous study using a weaker robotic ankle exoskeleton (Gordon and Ferris, 2007). Our results strongly suggest that humans aim for similar joint moment patterns when walking with robotic assistance rather than similar kinematic patterns. In addition, greater robotic assistance provided during initial use results in a longer adaptation process than lesser robotic assistance.

  9. Cat hindlimb motoneurons during locomotion. I. Destination, axonal conduction velocity, and recruitment threshold.

    PubMed

    Hoffer, J A; Loeb, G E; Marks, W B; O'Donovan, M J; Pratt, C A; Sugano, N

    1987-02-01

    Fine flexible wire microelectrodes chronically implanted in the fifth lumbar ventral root (L5 VR) of 17 cats rendered stable records of the natural discharge patterns of 164 individual axons during locomotion on a treadmill. Fifty-one out of 164 axons were identified as motoneurons projecting to the anterior thigh muscle group. For these axons, the centrifugal propagation of action potentials was demonstrated by the technique of spike-triggered averaging using signals recorded from cuff electrodes implanted around the femoral nerve. The axonal conduction velocity was measured from the femoral nerve cuff records. For 43/51 motoneurons, the corresponding target muscle was identified by spike-triggered averaging of signals recorded from bipolar EMG electrodes implanted in each of the anterior thigh muscles: vastus intermedius, medialis and lateralis, sartorius anterior and medialis, and rectus femoris. For 32/51 motoneurons, the recruitment threshold during locomotion was determined from the mean value of the rectified digitally smoothed EMG of the target muscle measured at the time when the motoneuron fired its first spike for each step. The recruitment threshold of every motoneuron was relatively constant for a given speed of walking, but for some units there were small systematic variations as a function of treadmill speed (range: 0.1-1.3 m/s). Recruitment thresholds were standardized with respect to the mean value of peak EMG activity of the target muscle during 16 s of walking at 0.5 m/s. For 28/51 motoneurons recorded in nine cats, recruitment thresholds (range: 3-93% of peak target muscle EMG) were linearly correlated (r = 0.51, P less than 0.02) to axonal conduction velocities (range: 57-117 m/s). In addition, for seven recorded pairs of motoneurons that projected to the same muscle in the same cat, the recruitment thresholds were ordered by relative conduction velocities. Taken together, these results are consistent with the notion that, in normal cat

  10. Reflex origin for the slowing of motoneurone firing rates in fatigue of human voluntary contractions.

    PubMed Central

    Bigland-Ritchie, B R; Dawson, N J; Johansson, R S; Lippold, O C

    1986-01-01

    During fatigue from a sustained maximal voluntary contraction (m.v.c.) the mean motoneurone discharge rates decline. In the present experiments we found no recovery of firing rates after 3 min of rest if the fatigued muscle was kept ischaemic, but near full recovery 3 min after the blood supply was restored. Since 3 min is thus sufficient time for recovery of any central changes in excitability, the results support the hypothesis that, during fatigue, motoneurone firing rates may be regulated by a peripheral reflex originating in response to fatigue-induced changes within the muscle. PMID:3560001

  11. Mechanisms of spinal motoneurons survival in rats under simulated hypogravity on earth

    NASA Astrophysics Data System (ADS)

    Islamov, R. R.; Mishagina, E. A.; Tyapkina, O. V.; Shajmardanova, G. F.; Eremeev, A. A.; Kozlovskaya, I. B.; Nikolskij, E. E.; Grigorjev, A. I.

    2011-05-01

    It was previously shown that different cell types in vivo and in vitro may die via apoptosis under weightlessness conditions in space as well as in simulated hypogravity on the Earth. We assessed survivability of spinal motoneurons of rats after 35-day antiorthostatic hind limb suspension. Following weight bearing, unloading the total protein content in lumbar spinal cord is dropped by 21%. The electrophysiological studies of m. gastrocnemius revealed an elevated motoneurons' reflex excitability and conduction disturbances in the sciatic nerve axons. The number of myelinated fibers in the ventral root of experimental animals was insignificantly increased by 35-day of antiorthostatic hind limb suspension, although the retrograde axonal transport was significantly decreased during the first week of simulated hypogravity. The results of the immunohistochemical assay with antibodies against proapoptotic protein caspase 9 and cytotoxicity marker neuron specific nitric oxide synthase (nNOS) and the TUNEL staining did not reveal any signs of apoptosis in motoneurons of suspended and control animals. To examine the possible adaptation mechanisms activated in motoneurons in response to simulated hypogravity we investigated immunoexpression of Hsp25 and Hsp70 in lumbar spinal cord of the rats after 35-day antiorthostatic hind limb suspension. Comparative analysis of the immunohistochemical reaction with anti-Hsp25 antibodies revealed differential staining of motoneurons in intact and experimental animals. The density of immunoprecipitate with anti-Hsp25 antibodies was substantially higher in motoneurons of the 35-day suspended than control rats and the more intensive precipitate in this reaction was observed in motoneuron neuritis. Quantitative analysis of Hsp25 expression demonstrated an increase in the Hsp25 level by 95% in experimental rats compared to the control. The immunoexpression of Hsp70 found no qualitative and quantitative differences in control and experimental

  12. Ankle impingement syndromes: a review of etiology and related implications.

    PubMed

    Hess, Gregory William

    2011-10-01

    Ankle injuries are common occurrences in athletics involving and requiring extreme ranges of motion. Ankle sprains specifically occur with a 1 in 10,000 person rate in active individuals each day. If trauma is repetitive, the ankle structures have potential to experience secondary injury and dysfunction. Included in this category of dysfunction are both anterior and posterior ankle impingement syndromes where disruption of the bony structures, joint capsule, ligaments, and tendons typically occurs. Ankle impingement is described as ankle pain that occurs during athletic activity, with recurrent, extreme dorsiflexion or plantar flexion with the joint under a load. Ankle impingements can be classified according to what structures become involved both anteriorly and posteriorly. Osseous impingement, soft tissue impingement, impingement of the distal fascicle of anterior inferior tibiofibular ligament, and meniscoid lesions are all documented causes of ankle impingement. These changes tend to be brought about and exacerbated by extreme ranges of motion. Understanding various impingement types will better enable the clinician to prevent, identify, treat, and rehabilitate affected ankles. Acknowledging activities that predispose to ankle impingement syndrome will enhance prevention and recovery processes. Description of ankle impingement etiology and pathology is the objective of the current review.

  13. Factors Contributing to Chronic Ankle Instability: A Strength Perspective

    PubMed Central

    Kaminski, Thomas W.; Hartsell, Heather D.

    2002-01-01

    Objective: To examine the concept of dynamic ankle stability and closely critique the relevant research over the past 50+ years focusing on strength as it relates to those with chronic ankle instability (CAI). Data Sources: We reviewed the literature regarding the assessment of strength related to CAI. We searched MEDLINE and ISI Web of Science from 1950 through 2001 using the key words functional ankle instability, chronic ankle instability, strength, ankle stability, chronic ankle dysfunction, and isokinetics. Data Synthesis: An overview of dynamic stability in the ankle is established, followed by a comprehensive discussion involving the variables used to assess ankle strength. Additionally, a historical look at deficits in muscular stability leading to CAI is provided, and a compilation of numerous contemporary approaches examining strength as it relates to CAI is presented. Conclusions/Recommendations: Although strength is an important consideration during ankle rehabilitation, deficits in ankle strength are not highly correlated with CAI. More contemporary approaches involving the examination of reciprocal muscle-group ratios as a measure of strength have recently been investigated and offer an insightful, albeit different, avenue for future exploration. Evidence pertaining to the effects of strength training on those afflicted with CAI is lacking, including what, if any, implication strength training has on the various measures of ankle strength. PMID:12937561

  14. [Arthroscopically assisted treatment of ankle fractures].

    PubMed

    Braunstein, M; Baumbach, S F; Böcker, W; Mutschler, W; Polzer, H

    2016-02-01

    Acute ankle fractures are one of the most common fractures in adults with an incidence of 0.1-0.2 % per year. Operative treatment by open reduction and internal fixation (ORIF) is the standard method of treatment for unstable or dislocated fractures. The main goal of the operation is the anatomical realignment of the joint and restoration of ankle stability; nevertheless, anatomical reduction does not automatically lead to favorable clinical results. According to several studies the mid-term and in particular the long-term outcome following operative treatment is often poor with residual symptoms including chronic pain, stiffness, recurrent swelling and ankle instability. There is growing evidence that this poor outcome might be related to occult intra-articular injuries involving cartilage and soft tissues. In recent studies the frequency of fracture-related osteochondral lesions was reported to be approximately 64 %. By physical examination, standard radiography or even computed tomography (CT), these intra-articular pathologies cannot be reliably diagnosed; therefore, many authors emphasize the value of ankle arthroscopy in acute fracture treatment as it has become a safe and effective diagnostic and therapeutic procedure. Arthroscopically assisted open reduction and internal fixation (AORIF) allows control of the reduction as well examination of all intra-articular structures. If necessary, intra-articular pathologies can be addressed by removing ruptured ligaments and loose bodies, performing chondroplasty or microfracturing. So far there is no evidence that supplementary ankle arthroscopy increases the complication rate. On the other hand, the positive effect of AORIF has also not been clearly documented; nevertheless, there are clear indications that arthroscopically assisted fracture treatment is beneficial, especially in complex fractures.

  15. A new ankle foot orthosis for running.

    PubMed

    Bishop, David; Moore, Allan; Chandrashekar, Naveen

    2009-09-01

    Traumatic knee injuries in automobile accidents and sports often lead to damage of the peroneal nerve. A lack of control of muscles innervated by the peroneal nerve due to this damage, results in the inability to dorsiflex and evert the foot and to extend the toes. This condition is commonly known as foot drop. Foot drop reduces the stability in the body while walking and running and may also cause injury due to lack of foot clearance during the swing phase of the gait. Traditionally, an ankle foot orthosis (AFO), comprised of a moulded sheet of plastic that conforms around the posterior calf and distally contains all or part of the calcaneous as well as the plantar foot, is used to treat foot drop. The intent of this orthosis is to dorsiflex the foot to provide clearance during the swing phase of walking and running. Traditional AFO results in increased pressures due to a decrease in dorsiflexion range of motion at the ankle and make the orthosis increasingly uncomfortable to wear. Several other existing designs of foot drop AFO suffer from similar inadequacies. To address these issues, a new AFO was developed. The device was successfully used by one person with foot drop without issues for more than one year. This new design conforms to the lower anterior shin and dorsum of the foot using dorsiassist Tamarack ankle joints to allow for greater plantar and dorsiflexion range of motion. While still limiting ankle inversion it does allow for more ankle eversion. This orthosis can be discretely worn inside shoes due to its smaller size, and can be worn for a longer period of time without discomfort.

  16. Osteochondral Allografts in the Ankle Joint

    PubMed Central

    Vannini, Francesca; Buda, Roberto; Ruffilli, Alberto; Cavallo, Marco; Giannini, Sandro

    2013-01-01

    Purpose: The aim of this systematic review is to report about the clinical use of partial and total fresh osteochondral allograft in the ankle joint. The state of the art of allografts with regard to basic science, procurement and storage methods, immunogenicity, generally accepted indications and contraindications, and the rationale of the allografting procedure have been described. Methods: All studies published in PubMed from 2000 to January 2012 addressing fresh osteochondral allograft procedures in the ankle joint were identified, including those that fulfilled the following criteria: (a) level I-IV evidence addressing the areas of interest outlined above; (b) measures of functional, clinical, or imaging outcome; and (c) outcome related to ankle cartilage lesions or ankle arthritis treated by allografts. Results: The analysis showed a progressively increasing number of articles from 2000. The number of selected articles was 14; 9 of those focused on limited dimension allografts (plugs, partial) and 5 on bipolar fresh osteochondral allografts. The evaluation of evidence level showed 14 case series and no randomized studies. Conclusions: Fresh osteochondral allografts are now a versatile and suitable option for the treatment of different degrees of osteochondral disease in the ankle joint and may even be used as total joint replacement. Fresh osteochondral allografts used for total joint replacement are still experimental and might be considered as a salvage procedure in otherwise unsolvable situations. A proper selection of the patients is therefore a key point. Moreover, the patients should be adequately informed about the possible risks, benefits, and alternatives to the allograft procedure. PMID:26069666

  17. Design of a simple, lightweight, passive-elastic ankle exoskeleton supporting ankle joint stiffness

    NASA Astrophysics Data System (ADS)

    Kim, Seyoung; Son, Youngsu; Choi, Sangkyu; Ham, Sangyong; Park, Cheolhoon

    2015-09-01

    In this study, a passive-elastic ankle exoskeleton (PEAX) with a one-way clutch mechanism was developed and then pilot-tested with vertical jumping to determine whether the PEAX is sufficiently lightweight and comfortable to be used in further biomechanical studies. The PEAX was designed to supplement the function of the Achilles tendon and ligaments as they passively support the ankle torque with their inherent stiffness. The main frame of the PEAX consists of upper and lower parts connected to each other by tension springs (N = 3) and lubricated hinge joints. The upper part has an offset angle of 5° with respect to the vertical line when the springs are in their resting state. Each spring has a slack length of 8 cm and connects the upper part to the tailrod of the lower part in the neutral position. The tailrod freely rotates with low friction but has a limited range of motion due to the stop pin working as a one-way clutch. Because of the one-way clutch system, the tension springs store the elastic energy only due to an ankle dorsiflexion when triggered by the stop pin. This clutch mechanism also has the advantage of preventing any inconvenience during ankle plantarflexion because it does not limit the ankle joint motion during the plantarflexion phase. In pilot jumping tests, all of the subjects reported that the PEAX was comfortable for jumping due to its lightweight (approximately 1 kg) and compact (firmly integrated with shoes) design, and subjects were able to nearly reach their maximum vertical jump heights while wearing the PEAX. During the countermovement jump, elastic energy was stored during dorsiflexion by spring extension and released during plantarflexion by spring restoration, indicating that the passive spring torque (i.e., supportive torque) generated by the ankle exoskeleton partially supported the ankle joint torque throughout the process.

  18. P75 and phosphorylated c-Jun are differentially regulated in spinal motoneurons following axotomy in rats.

    PubMed

    Yuan, Qiuju; Su, Huanxing; Wu, Wutian; Lin, Zhi-Xiu

    2012-09-15

    The neurotrophin receptor (p75) activates the c-Jun N-terminal kinase (JNK) pathway. Activation of JNK and its substrate c-Jun can cause apoptosis. Here we evaluate the role of p75 in spinal motoneurons by comparing immunoreactivity for p75 and phosphorylated c-Jun (p-c-Jun), the production of JNK activation in axotomized motoneurons in postnatal day (PN)1, PN7, PN14 and adult rats. Intensive p-c-Jun was induced in axotomized motoneurons in PN1 and PN7. In PN14, p-c-Jun expression was sharply reduced after the same injury. The decreased expression of p-c-Jun at this age coincided with a developmental switch of re-expression of p75 in axotomized cells. In adult animals, no p-c-Jun but intensive p75 was detected in axotomized motoneurons. These results indicate differential expression or turnover of phosphorylation of c-Jun and p75 in immature versus mature spinal motoneurons in response to axonal injury. The non-co-occurrence of p75 and p-c-Jun in injured motoneurons indicated that p75 may not activate JNK pathway, suggesting that the p75 may not be involved in cell death in axotomized motoneurons.

  19. The Drosophila Hox gene Ultrabithorax acts in both muscles and motoneurons to orchestrate formation of specific neuromuscular connections

    PubMed Central

    Hessinger, Christian; Technau, Gerhard M.

    2017-01-01

    Hox genes are known to specify motoneuron pools in the developing vertebrate spinal cord and to control motoneuronal targeting in several species. However, the mechanisms controlling axial diversification of muscle innervation patterns are still largely unknown. We present data showing that the Drosophila Hox gene Ultrabithorax (Ubx) acts in the late embryo to establish target specificity of ventrally projecting RP motoneurons. In abdominal segments A2 to A7, RP motoneurons innervate the ventrolateral muscles VL1-4, with VL1 and VL2 being innervated in a Wnt4-dependent manner. In Ubx mutants, these motoneurons fail to make correct contacts with muscle VL1, a phenotype partially resembling that of the Wnt4 mutant. We show that Ubx regulates expression of Wnt4 in muscle VL2 and that it interacts with the Wnt4 response pathway in the respective motoneurons. Ubx thus orchestrates the interaction between two cell types, muscles and motoneurons, to regulate establishment of the ventrolateral neuromuscular network. PMID:27913640

  20. Regulation of locomotion and motoneuron trajectory selection and targeting by the Drosophila homolog of Olig family transcription factors

    PubMed Central

    Oyallon, Justine; Apitz, Holger; Miguel-Aliaga, Irene; Timofeev, Katarina; Ferreira, Lauren; Salecker, Iris

    2012-01-01

    During the development of locomotion circuits it is essential that motoneurons with distinct subtype identities select the correct trajectories and target muscles. In vertebrates, the generation of motoneurons and myelinating glia depends on Olig2, one of the five Olig family bHLH transcription factors. We investigated the so far unknown function of the single Drosophila homolog Oli. Combining behavioral and genetic approaches, we demonstrate that oli is not required for gliogenesis, but plays pivotal roles in regulating larval and adult locomotion, and axon pathfinding and targeting of embryonic motoneurons. In the embryonic nervous system, Oli is primarily expressed in postmitotic progeny, and in particular, in distinct ventral motoneuron subtypes. oli mediates axonal trajectory selection of these motoneurons within the ventral nerve cord and targeting to specific muscles. Genetic interaction assays suggest that oli acts as part of a conserved transcription factor ensemble including Lim3, Islet and Hb9. Moreover, oli is expressed in postembryonic leg-innervating motoneuron lineages and required in glutamatergic neurons for walking. Finally, over-expression of vertebrate Olig2 partially rescues the walking defects of oli-deficient flies. Thus, our findings reveal a remarkably conserved role of Drosophila Oli and vertebrate family members in regulating motoneuron development, while the steps that require their function differ in detail. PMID:22796650

  1. Treatment of anterolateral impingements of the ankle joint by arthroscopy.

    PubMed

    Hassan, Al-Husseiny Moustafa

    2007-09-01

    Impingement syndromes of the ankle joint are among the most common intraarticular ankle lesions. Soft tissue impingement lesions of the ankle usually occur as a result of synovial, or capsular irritation secondary to traumatic injuries, usually ankle sprains, leading to chronic ankle pain. The aim of this prospective study was to evaluate arthroscopic debridement of an anterolateral soft tissue impingement of the ankle. During the period between October 2000 and February 2004, 23 patients with residual complaints after an ankle sprain were diagnosed as anterolateral impingement of the ankle, and were treated by arthroscopic debridement. At a minimum of 6 months follow up, patients were asked to complete an American orthopaedic foot and ankle society (AOFAS) ankle and hind foot score. The average follow-up was 25 months (range 12-38). The average pre-operative patient assessed AOFAS score was 34 (range 4-57). At the end of follow-up the mean AOFAS score was 89 (range 60-100). In terms of patient satisfaction 22 patients said they would accept the same arthroscopic procedure again for the same complaints. At the end of follow-up, 7 patients had excellent results, and 14 patients had good results while two patients had fair results. We believe that arthroscopic debridement of the anterolateral impingement soft tissues are a good, and effective method of treatment.

  2. Dual effect of GABA on descending monosynaptic excitatory postsynaptic potential in frog lumbar motoneurons.

    PubMed

    Ovsepian, S V; Vesselkin, N P

    2004-01-01

    Monosynaptic excitatory postsynaptic potentials (EPSPs) evoked by stimulating ipsilateral ventrolateral column (VLC) in the thoracic section were recorded in lumbar motoneurons within the isolated spinal cord of the frog Rana ridibunda. Bath application of the selective GABAB receptor agonist (-)-baclofen (0.05 mM) caused a reduction in the peak amplitude of VLC EPSP. Baclofen did not cause any consistent change in the membrane potential or in the EPSP waveform within frog motoneurones. The selective GABA(B) receptor antagonist saclofen (0.1 mM) completely blocked the effect of (-)-baclofen on VLC EPSP. A decrease in VLC EPSP peak amplitude was also observed during GABA (0.5 mM) application. Unlike (-)-baclofen, inhibition of VLC EPSP induced by GABA was accompanied by a shortening of the EPSP time course and a reduction in membrane input resistance within lumbar motoneurons. The decrease in VLC EPSP peak amplitude induced by (-)-baclofen and GABA was accompanied by an increase in the paired-pulse facilitation. These data provide evidence for a dual pre- and postsynaptic GABAergic inhibition of the VLC monosynaptic EPSP in lumbar motoneurons within the frog spinal cord.

  3. Neurotrophic factors improve motoneuron survival and function of muscle reinnervated by embryonic neurons.

    PubMed

    Grumbles, Robert M; Sesodia, Sanjay; Wood, Patrick M; Thomas, Christine K

    2009-07-01

    Motoneuron death can occur over several spinal levels with disease or trauma, resulting in muscle denervation. We tested whether cotransplantation of embryonic neurons with 1 or more neurotrophic factors into peripheral nerve improved axon regeneration, muscle fiber area, reinnervation, and function to a greater degree than cell transplantation alone. Sciatic nerves of adult Fischer rats were cut to denervate muscles; 1 week later, embryonic ventral spinal cord cells (days 14-15) were transplanted into the tibial nerve stump as the only source of neurons for muscle reinnervation. Factors that promote motoneuron survival (cardiotrophin 1; fibroblast growth factor 2; glial cell line-derived neurotrophic factor; insulin-like growth factor 1; leukemia inhibitory factor; and hepatocyte growth factor) were added to the transplant individually or in combinations. Inclusion of a single factor with the cells resulted in comparable myelinated axon counts, muscle fiber areas, and evoked electromyographic activity to cells alone 10 weeks after transplantation. Only cell transplantation with glial cell line-derived neurotrophic factor, hepatocyte growth factor, and insulin-like growth factor 1 significantly increased motoneuron survival, myelinated axon counts, muscle reinnervation, and evoked electromyographic activity compared with cells alone. Thus, immediate application of a specific combination of factors to dissociated embryonic neurons improves survival of motoneurons and the long-term function of reinnervated muscle.

  4. Spinal organization and steroid sensitivity of motoneurons innervating the pubococcygeus muscle in the male rat.

    PubMed

    Manzo, J; Nicolas, L; Hernandez, M E; Cruz, M R; Carrillo, P; Pacheco, P

    1999-07-05

    Male rat motoneurons innervating the pubococcygeus muscle were located in the ventral nucleus of lamina IX at the sixth lumbar (L6) and first sacral (S1) spinal cord segments. Retrograde labeling with horseradish peroxidase-wheat germ agglutinin was transported up to second-order dendrites and revealed that these motoneurons have a "U-shaped arborization" of dendrites toward the intermediolateral and intermediomedial nuclei area of lamina VII. This dendritic organization makes a wide "final common path" that probably integrates afferent information from several sources, accounting for the participation of the pubococcygeus muscle in autonomic and somatic processes, such as those related to micturition and reproduction. Castration produced a decrement in the morphometry of these motoneurons. A main effect was a decrement in dendritic length. Steroid replacement indicated that testosterone and estradiol, but not dihydrotestosterone, are able to induce a recovery of morphometric alterations. However, estrogen induced recovery after 2 weeks of treatment, whereas testosterone took 4 weeks. Thus, it is proposed that supraspinal aromatization of testosterone in the male central nervous system might be an important process for the appropriate organization of the pubococcygeus muscle motoneurons and that estradiol seems to need a shorter time of action than testosterone because of differential up-regulation and down-regulation of steroid receptors.

  5. Output of human motoneuron pools to corticospinal inputs during voluntary contractions.

    PubMed

    Martin, P G; Gandevia, S C; Taylor, J L

    2006-06-01

    This study investigated transmission of corticospinal output through motoneurons over a wide range of voluntary contraction strengths in humans. During voluntary contraction of biceps brachii, motor evoked potentials (MEPs) to transcranial magnetic stimulation of the motor cortex grow up to about 50% maximal force and then decrease. To determine whether the decrease reflects events at a cortical or spinal level, responses to stimulation of the cortex and corticospinal tract (cervicomedullary motor evoked potentials, CMEPs) as well as maximal M-waves (M(max)) were recorded during strong contractions at 50 to 100% maximum. In biceps and brachioradialis, MEPs and CMEPs (normalized to M(max)) evoked by strong stimuli decreased during strong elbow flexions. Responses were largest during contractions at 75% maximum and both potentials decreased by about 25% M(max) during maximal efforts (P < 0.001). Reductions were smaller with weaker stimuli, but again similar for MEPs and CMEPs. Thus the reduction in MEPs during strong voluntary contractions can be accounted for by reduced responsiveness of the motoneuron pool to stimulation. During strong contractions of the first dorsal interosseous, a muscle that increases voluntary force largely by frequency modulation, MEPs declined more than in either elbow flexor muscle (35% M(max), P < 0.001). This suggests that motoneuron firing rates are important determinants of evoked output from the motoneuron pool. However, motor cortical output does not appear to be limited at high contraction strengths.

  6. Loss of ATF2 function leads to cranial motoneuron degeneration during embryonic mouse development.

    PubMed

    Ackermann, Julien; Ashton, Garry; Lyons, Steve; James, Dominic; Hornung, Jean-Pierre; Jones, Nic; Breitwieser, Wolfgang

    2011-04-21

    The AP-1 family transcription factor ATF2 is essential for development and tissue maintenance in mammals. In particular, ATF2 is highly expressed and activated in the brain and previous studies using mouse knockouts have confirmed its requirement in the cerebellum as well as in vestibular sense organs. Here we present the analysis of the requirement for ATF2 in CNS development in mouse embryos, specifically in the brainstem. We discovered that neuron-specific inactivation of ATF2 leads to significant loss of motoneurons of the hypoglossal, abducens and facial nuclei. While the generation of ATF2 mutant motoneurons appears normal during early development, they undergo caspase-dependent and independent cell death during later embryonic and foetal stages. The loss of these motoneurons correlates with increased levels of stress activated MAP kinases, JNK and p38, as well as aberrant accumulation of phosphorylated neurofilament proteins, NF-H and NF-M, known substrates for these kinases. This, together with other neuropathological phenotypes, including aberrant vacuolisation and lipid accumulation, indicates that deficiency in ATF2 leads to neurodegeneration of subsets of somatic and visceral motoneurons of the brainstem. It also confirms that ATF2 has a critical role in limiting the activities of stress kinases JNK and p38 which are potent inducers of cell death in the CNS.

  7. Influence of proprioceptive feedback on the firing rate and recruitment of motoneurons

    NASA Astrophysics Data System (ADS)

    De Luca, C. J.; Kline, J. C.

    2012-02-01

    We investigated the relationships of the firing rate and maximal recruitment threshold of motoneurons recorded during isometric contraction with the number of spindles in individual muscles. At force levels above 10% of maximal voluntary contraction, the firing rate was inversely related to the number of spindles in a muscle, with the slope of the relationship increasing with force. The maximal recruitment threshold of motor units increased linearly with the number of spindles in the muscle. Thus, muscles with a greater number of spindles had lower firing rates and a greater maximal recruitment threshold. These findings may be explained by a mechanical interaction between muscle fibres and adjacent spindles. During low-level (0% to 10%) voluntary contractions, muscle fibres of recruited motor units produce force twitches that activate nearby spindles to respond with an immediate excitatory feedback that reaches maximal level. As the force increases further, the twitches overlap and tend towards tetanization, the muscle fibres shorten, the spindles slacken, their excitatory firings decrease, and the net excitation to the homonymous motoneurons decreases. Motoneurons of muscles with greater number of spindles receive a greater decrease in excitation which reduces their firing rates, increases their maximal recruitment threshold, and changes the motoneuron recruitment distribution.

  8. Impaired motoneuronal retrograde transport in two models of SBMA implicates two sites of androgen action.

    PubMed

    Kemp, Michael Q; Poort, Jessica L; Baqri, Rehan M; Lieberman, Andrew P; Breedlove, S Marc; Miller, Kyle E; Jordan, Cynthia L

    2011-11-15

    Spinal and bulbar muscular atrophy (SBMA) impairs motor function in men and is linked to a CAG repeat mutation in the androgen receptor (AR) gene. Defects in motoneuronal retrograde axonal transport may critically mediate motor dysfunction in SBMA, but the site(s) where AR disrupts transport is unknown. We find deficits in retrograde labeling of spinal motoneurons in both a knock-in (KI) and a myogenic transgenic (TG) mouse model of SBMA. Likewise, live imaging of endosomal trafficking in sciatic nerve axons reveals disease-induced deficits in the flux and run length of retrogradely transported endosomes in both KI and TG males, demonstrating that disease triggered in muscle can impair retrograde transport of cargo in motoneuron axons, possibly via defective retrograde signaling. Supporting the idea of impaired retrograde signaling, we find that vascular endothelial growth factor treatment of diseased muscles reverses the transport/trafficking deficit. Transport velocity is also affected in KI males, suggesting a neurogenic component. These results demonstrate that androgens could act via both cell autonomous and non-cell autonomous mechanisms to disrupt axonal transport in motoneurons affected by SBMA.

  9. Emerging Roles of Filopodia and Dendritic Spines in Motoneuron Plasticity during Development and Disease

    PubMed Central

    Kanjhan, Refik; Noakes, Peter G.; Bellingham, Mark C.

    2016-01-01

    Motoneurons develop extensive dendritic trees for receiving excitatory and inhibitory synaptic inputs to perform a variety of complex motor tasks. At birth, the somatodendritic domains of mouse hypoglossal and lumbar motoneurons have dense filopodia and spines. Consistent with Vaughn's synaptotropic hypothesis, we propose a developmental unified-hybrid model implicating filopodia in motoneuron spinogenesis/synaptogenesis and dendritic growth and branching critical for circuit formation and synaptic plasticity at embryonic/prenatal/neonatal period. Filopodia density decreases and spine density initially increases until postnatal day 15 (P15) and then decreases by P30. Spine distribution shifts towards the distal dendrites, and spines become shorter (stubby), coinciding with decreases in frequency and increases in amplitude of excitatory postsynaptic currents with maturation. In transgenic mice, either overexpressing the mutated human Cu/Zn-superoxide dismutase (hSOD1G93A) gene or deficient in GABAergic/glycinergic synaptic transmission (gephyrin, GAD-67, or VGAT gene knockout), hypoglossal motoneurons develop excitatory glutamatergic synaptic hyperactivity. Functional synaptic hyperactivity is associated with increased dendritic growth, branching, and increased spine and filopodia density, involving actin-based cytoskeletal and structural remodelling. Energy-dependent ionic pumps that maintain intracellular sodium/calcium homeostasis are chronically challenged by activity and selectively overwhelmed by hyperactivity which eventually causes sustained membrane depolarization leading to excitotoxicity, activating microglia to phagocytose degenerating neurons under neuropathological conditions. PMID:26843990

  10. Extrasynaptic α6 Subunit-Containing GABAA Receptors Modulate Excitability in Turtle Spinal Motoneurons

    PubMed Central

    Andres, Carmen; Aguilar, Justo; González-Ramírez, Ricardo; Elias-Viñas, David; Felix, Ricardo; Delgado-Lezama, Rodolfo

    2014-01-01

    Motoneurons are furnished with a vast repertoire of ionotropic and metabotropic receptors as well as ion channels responsible for maintaining the resting membrane potential and involved in the regulation of the mechanisms underlying its membrane excitability and firing properties. Among them, the GABAA receptors, which respond to GABA binding by allowing the flow of Cl− ions across the membrane, mediate two distinct forms of inhibition in the mature nervous system, phasic and tonic, upon activation of synaptic or extrasynaptic receptors, respectively. In a previous work we showed that furosemide facilitates the monosynaptic reflex without affecting the dorsal root potential. Our data also revealed a tonic inhibition mediated by GABAA receptors activated in motoneurons by ambient GABA. These data suggested that the high affinity GABAA extrasynaptic receptors may have an important role in motor control, though the molecular nature of these receptors was not determined. By combining electrophysiological, immunofluorescence and molecular biology techniques with pharmacological tools here we show that GABAA receptors containing the α6 subunit are expressed in adult turtle spinal motoneurons and can function as extrasynaptic receptors responsible for tonic inhibition. These results expand our understanding of the role of GABAA receptors in motoneuron tonic inhibition. PMID:25531288

  11. Does alpha-motoneurone size correlate with motor unit type in cat triceps surae?

    PubMed

    Ulfhake, B; Kellerth, J O

    1982-11-18

    The cell bodies and first-order dendrites of alpha-motoneurones supplying different functional types of muscle units in the cat gastrocnemius (type FF, FR and S units) and soleus (type SOL-S units) muscles, were studied after intracellular injection of horseradish peroxidase. The SOL-S neurones had smaller values for cell body diameter in comparison with both the FF and FR neurones. The SOL-S neurones also had significantly thinner first-order dendrites than the FF, FR and S neurones. In the gastrocnemius pool the S neurones had smaller values for dendritic diameters than the FF and FR cells. The values for combined diameter of the first-order dendrites indicated that the dendritic trees of the FF and FR neurones are, on the average, larger than those of the S and SOL-S neurones. Furthermore, the relationship between the combined dendritic diameter and the mean soma diameter, indicated that a difference in relative scaling of soma and dendrites exists between the FF and FR neurones on the one hand and the S and SOL-S neurones on the other. Similar results were obtained also when relating the combined dendritic parameter sigma d3/2 to the soma surface area. Although a certain statistical relation seems to exist between motoneurone size and motoneurone type, it should be emphasized, however, that the range of values for each parameter studied overlapped considerably between the different types of motoneurones.

  12. Sensitization of neonatal rat lumbar motoneuron by the inflammatory pain mediator bradykinin

    PubMed Central

    Bouhadfane, Mouloud; Kaszás, Attila; Rózsa, Balázs; Harris-Warrick, Ronald M; Vinay, Laurent; Brocard, Frédéric

    2015-01-01

    Bradykinin (Bk) is a potent inflammatory mediator that causes hyperalgesia. The action of Bk on the sensory system is well documented but its effects on motoneurons, the final pathway of the motor system, are unknown. By a combination of patch-clamp recordings and two-photon calcium imaging, we found that Bk strongly sensitizes spinal motoneurons. Sensitization was characterized by an increased ability to generate self-sustained spiking in response to excitatory inputs. Our pharmacological study described a dual ionic mechanism to sensitize motoneurons, including inhibition of a barium-sensitive resting K+ conductance and activation of a nonselective cationic conductance primarily mediated by Na+. Examination of the upstream signaling pathways provided evidence for postsynaptic activation of B2 receptors, G protein activation of phospholipase C, InsP3 synthesis, and calmodulin activation. This study questions the influence of motoneurons in the assessment of hyperalgesia since the withdrawal motor reflex is commonly used as a surrogate pain model. DOI: http://dx.doi.org/10.7554/eLife.06195.001 PMID:25781633

  13. F-wave of single firing motor units: correct or misleading criterion of motoneuron excitability in humans?

    PubMed

    Kudina, Lydia P; Andreeva, Regina E

    2017-03-01

    Motoneuron excitability is a critical property for information processing during motor control. F-wave (a motoneuronal recurrent discharge evoked by a motor antidromic volley) is often used as a criterion of motoneuron pool excitability in normal and neuromuscular diseases. However, such using of F-wave calls in question. The present study was designed to explore excitability of single low-threshold motoneurons during their natural firing in healthy humans and to ascertain whether F-wave is a correct measure of motoneuronal excitability. Single motor units (MUs) were activated by gentle voluntary muscle contractions. MU peri-stimulus time histograms and motoneuron excitability changes within a target interspike interval were analysed during testing by motor antidromic and Ia-afferent volleys. It was found that F-waves could be occasionally recorded in some low-threshold MUs. However, during evoking F-wave, in contrast with the H-reflex, peri-stimulus time histograms revealed no statistically significant increase in MU discharge probability. Moreover, surprisingly, motoneurons appeared commonly incapable to fire a recurrent discharge within the most excitable part of a target interval. Thus, the F-wave, unlike the H-reflex, is the incorrect criterion of motoneuron excitability resulting in misleading conclusions. However, it does not exclude the validity of the F-wave as a clinical tool for other aims. It was concluded that the F-wave was first explored in low-threshold MUs during their natural firing. The findings may be useful at interpretations of changes in the motoneuron pool excitability in neuromuscular diseases.

  14. Diminished Foot and Ankle Muscle Volumes in Young Adults With Chronic Ankle Instability

    PubMed Central

    Feger, Mark A.; Snell, Shannon; Handsfield, Geoffrey G.; Blemker, Silvia S.; Wombacher, Emily; Fry, Rachel; Hart, Joseph M.; Saliba, Susan A.; Park, Joseph S.; Hertel, Jay

    2016-01-01

    Background: Patients with chronic ankle instability (CAI) have demonstrated altered neuromuscular function and decreased muscle strength when compared with healthy counterparts without a history of ankle sprain. Up to this point, muscle volumes have not been analyzed in patients with CAI to determine whether deficits in muscle size are present following recurrent sprain. Purpose: To analyze intrinsic and extrinsic foot and ankle muscle volumes and 4-way ankle strength in young adults with and without CAI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Five patients with CAI (mean age, 23.0 ± 4 years; 1 male, 4 females) and 5 healthy controls (mean age, 23.8 ± 4.5 years; 1 male, 4 females) volunteered for this study. Novel fast-acquisition magnetic resonance imaging (MRI) was used to scan from above the femoral condyles through the foot and ankle. The perimeter of each muscle was outlined on each axial slice and then the 2-dimensional area was multiplied by the slice thickness (5 mm) to calculate the muscle volume. Plantar flexion, dorsiflexion, inversion, and eversion isometric strength were measured using a handheld dynamometer. Patients with CAI were compared with healthy controls on all measures of muscle volume and strength. Extrinsic muscle volumes of patients with CAI were also compared with a normative database of healthy controls (n = 24) by calculating z scores for each muscle individually for each CAI subject. Results: The CAI group had smaller total shank, superficial posterior compartment, soleus, adductor hallucis obliqus, and flexor hallucis brevis muscle volumes compared with healthy controls as indicated by group means and associated 90% CIs that did not overlap. Cohen d effect sizes for the significant group differences were all large and ranged from 1.46 to 3.52, with 90% CIs that did not cross zero. The CAI group had lower eversion, dorsiflexion, and 4-way composite ankle strength, all with group means and associated 90

  15. Motoneuron BDNF/TrkB signaling enhances functional recovery after cervical spinal cord injury.

    PubMed

    Mantilla, Carlos B; Gransee, Heather M; Zhan, Wen-Zhi; Sieck, Gary C

    2013-09-01

    A C2 cervical spinal cord hemisection (SH) interrupts descending inspiratory-related drive to phrenic motoneurons located between C3 and C5 in rats, paralyzing the ipsilateral hemidiaphragm muscle. There is gradual recovery of rhythmic diaphragm muscle activity ipsilateral to cervical spinal cord injury over time, consistent with neuroplasticity and strengthening of spared, contralateral descending premotor input to phrenic motoneurons. Brain-derived neurotrophic factor (BDNF) signaling through the tropomyosin related kinase receptor subtype B (TrkB) plays an important role in neuroplasticity following spinal cord injury. We hypothesized that 1) increasing BDNF/TrkB signaling at the level of the phrenic motoneuron pool by intrathecal BDNF delivery enhances functional recovery of rhythmic diaphragm activity after SH, and 2) inhibiting BDNF/TrkB signaling by quenching endogenous neurotrophins with the soluble fusion protein TrkB-Fc or by knocking down TrkB receptor expression in phrenic motoneurons using intrapleurally-delivered siRNA impairs functional recovery after SH. Diaphragm EMG electrodes were implanted bilaterally to verify complete hemisection at the time of SH and 3days post-SH. After SH surgery in adult rats, an intrathecal catheter was placed at C4 to chronically infuse BDNF or TrkB-Fc using an implanted mini-osmotic pump. At 14days post-SH, all intrathecal BDNF treated rats (n=9) displayed recovery of ipsilateral hemidiaphragm EMG activity, compared to 3 out of 8 untreated SH rats (p<0.01). During eupnea, BDNF treated rats exhibited 76±17% of pre-SH root mean squared EMG vs. only 5±3% in untreated SH rats (p<0.01). In contrast, quenching endogenous BDNF with intrathecal TrkB-Fc treatment completely prevented functional recovery up to 14days post-SH (n=7). Immunoreactivity of the transcription factor cAMP response element-binding protein (CREB), a downstream effector of TrkB signaling, increased in phrenic motoneurons following BDNF treatment (n=6

  16. The effects of ankle Kinesio taping on ankle stiffness and dynamic balance.

    PubMed

    Fayson, Shirleeah D; Needle, Alan R; Kaminski, Thomas W

    2013-01-01

    The purpose of this study was to determine the effects of Kinesio® taping on static restraint and dynamic postural control of the ankle joint. Thirty female subjects with no history of ankle injury participated in this study. Subjects were tested for passive ankle laxity and stiffness, and time to stabilization following forward, backward, medial, and lateral hops. Subjects were tested prior to tape application, immediately following application, and following 24 hours of use. Differences between taping conditions were investigated using analyses of variance and pairwise comparisons. Stiffness increased following initial application and 24 hours of Kinesio® tape use (F = 6.99, p = .003), despite no observed changes in ankle laxity (F = 0.77, p = .49); however, no changes were observed in time-to-stabilization (F = 0.03, p = .97). Our results suggest that Kinesio® tape may improve static restraint in the ankle joint without altering peak motion or dynamic postural control. A future investigation into Kinesio® tape efficacy in injury prevention or rehabilitation is warranted.

  17. Foot and ankle injuries in dance.

    PubMed

    Brown, Treg D; Micheli, Lyle J

    2004-06-01

    This review focuses on many of the foot and ankle injuries commonly seen among dancers. These unique athletes place extreme demands on their musculoskeletal system and thereby face a variety of acute and overuse injuries. Conservative treatment is successful in the majority of cases, but these patients often continue to dance while healing--commonly prolonging and at times complicating treatment. When surgery is being contemplated, the dancer's performance level and expectations about returning to dance after surgery should be thoroughly explored. Foot and ankle surgeries that routinely yield good to excellent results in the general population can prematurely end a dancer's otherwise promising career. The physician must consider all these factors when designing an appropriate treatment plan for a dancer.

  18. Movements causing ankle fractures in parachuting.

    PubMed Central

    Ellitsgaard, N; Warburg, F

    1989-01-01

    The parachutist injured in a dramatic accident often describes the injury in an incomplete and biased way and evaluation of materials based solely upon subjective information of this kind can be misleading and of no value for recommendations. As the relation between the mechanical factors of the injury and the lesion in ankle fractures is well documented, an investigation of clinical, radiological and operative findings in 46 parachutists with ankle fractures was conducted. Classification was possible in 44 of 46 fractures. The description of the cause of the trauma in 21 supination-eversion fractures and in 13 pronation-eversion fractures was most frequently faulty landing position or obstacles. The cause of seven supination fractures was oscillation of the parachutist whilst descending with sudden impact against the lateral aspect of the foot. For prophylaxis we recommend improvement of landing and steering techniques and the support of semi-calf boots. PMID:2730996

  19. Calcium imaging of motoneuron activity in the en-bloc spinal cord preparation of the neonatal rat.

    PubMed

    Lev-Tov, A; O'Donovan, M J

    1995-09-01

    1. This paper describes the use of calcium imaging to monitor patterns of activity in neonatal rat motoneurons retrogradely labeled with the calcium-sensitive dye, calcium green-dextran. 2. Pressure ejection of calcium green-dextran into ventral roots and into the surgically peeled ventrolateral funiculi (VLF) at the lumbar cord labeled spinal motoneurons and interneurons. The back labeled motoneurons often formed two or three discrete clusters of cells. 3. Fluorescent changes (10-20%) could be detected in labeled motoneurons after a single antidromic stimulus of the segmental ventral root. These changes progressively increased in amplitude during stimulus trains (1-5 s) at frequencies from 5 to 50 Hz, presumably reflecting a frequency-dependent increase in free intracellular calcium. 4. Stimulation of the ipsilateral VLF at the caudal lumbar level (L6), elicited frequency-dependent, synaptically induced motoneuronal discharge. Frequency-dependent fluorescent changes could be detected in calcium green-labeled motoneurons during the VLF-induced synaptic activation. 5. The spatial spread of synaptic activity among calcium green-labeled clusters of motoneurons could be resolved after dorsal root stimulation. Low-intensity stimulation of the roots produced fluorescence changes restricted to the lateral clusters of motoneurons. With increasing stimulation intensity the fluorescence change increased in the lateral cells and could spread into the medial motoneuronal group. After a single supramaximal stimulus a similar pattern was observed with activity beginning laterally and spreading medially. 6. Substantial changes in fluorescence of calcium green-labeled motoneurons were also observed during motoneuron bursting induced by bath application of the glycine receptor antagonist strychnine or the potassium channel blocker 4-aminopyridine (4-AP). 7. Our results show that membrane-impermeant fluorescent calcium indicators can be used as a tool to study the activity of

  20. Discharge profiles of abducens, accessory abducens, and orbicularis oculi motoneurons during reflex and conditioned blinks in alert cats.

    PubMed

    Trigo, J A; Gruart, A; Delgado-García, J M

    1999-04-01

    The discharge profiles of identified abducens, accessory abducens, and orbicularis oculi motoneurons have been recorded extra- and intracellularly in alert behaving cats during spontaneous, reflexively evoked, and classically conditioned eyelid responses. The movement of the upper lid and the electromyographic activity of the orbicularis oculi muscle also were recorded. Animals were conditioned by short, weak air puffs or 350-ms tones as conditioned stimuli (CS) and long, strong air puffs as unconditioned stimulus (US) using both trace and delayed conditioning paradigms. Motoneurons were identified by antidromic activation from their respective cranial nerves. Orbicularis oculi and accessory abducens motoneurons fired an early, double burst of action potentials (at 4-6 and 10-16 ms) in response to air puffs or to the electrical stimulation of the supraorbital nerve. Orbicularis oculi, but not accessory abducens, motoneurons fired in response to flash and tone presentations. Only 10-15% of recorded abducens motoneurons fired a late, weak burst after air puff, supraorbital nerve, and flash stimulations. Spontaneous fasciculations of the orbicularis oculi muscle and the activity of single orbicularis oculi motoneurons that generated them also were recorded. The activation of orbicularis oculi motoneurons during the acquisition of classically conditioned eyelid responses happened in a gradual, sequential manner. Initially, some putative excitatory synaptic potentials were observed in the time window corresponding to the CS-US interval; by the second to the fourth conditioning session, some isolated action potentials appeared that increased in number until some small movements were noticed in eyelid position traces. No accessory abducens motoneuron fired and no abducens motoneuron modified their discharge rate for conditioned eyelid responses. The firing of orbicularis oculi motoneurons was related linearly to lid velocity during reflex blinks but to lid position during

  1. Pediatric Ankle Fractures: Concepts and Treatment Principles

    PubMed Central

    Su, Alvin W.; Larson, A. Noelle

    2016-01-01

    Synopsis Current clinical concepts are reviewed regarding the epidemiology, anatomy, evaluation and treatment of pediatric ankle fractures. Correct diagnosis and management relies on appropriate exam, imaging, and knowledge of fracture patterns specific to children. Treatment is guided by patient history, physical examination, plain film radiographs and, in some instances, CT. Treatment goals are to restore acceptable limb alignment, physeal anatomy, and joint congruency. For high risk physeal fractures, patients should be monitored for growth disturbance as needed until skeletal maturity. PMID:26589088

  2. [Ankle joint prosthesis for bone defects].

    PubMed

    Lampert, C

    2011-11-01

    Large defects of the talus, i.e. due to tumors, large areas of osteolysis in total ankle replacement (TAR) and posttraumatic talus body necrosis are difficult to manage. The gold standard in these circumstances is still tibiocalcaneal arthrodesis with all the negative aspects of a completely rigid hindfoot. We started 10 years ago to replace the talus by a custom-made, all cobalt-chrome implant (laser sintering). The first patient with a giant cell tumor did very well but the following patients showed all subsidence of the metal talus into the tibia due to missing bony edges. Therefore, we constructed a custom-made talus (mirrored from the healthy side) and combined it with a well functioning total ankle prosthesis (Hintegra). So far we have implanted this custom-made implant into 3 patients: the first had a chondrosarcoma of the talus (1 year follow-up), the second had massive osteolysis/necrosis of unknown origin (6 months follow-up) and the third massive osteolysis following a correct TAR (2 months follow-up). The results are very encouraging as all of the patients are practically pain free and have a good range of movement (ROM): D-P flexion 15°-0-20° but less motion in the lower ankle joint: ROM P-S 5°-0-5°. No subsidence was detected in the tibia or the calcaneus. The custom-made talus combined with the Hintegra total ankle replacement will probably be an interesting alternative to a tibiocalcaneal arthrodesis in selected cases with massive defects of the talus.

  3. Symptomatic anterior subtalar arthrosis after ankle arthrodesis.

    PubMed

    Lui, Tun Hing

    2014-05-13

    A 76-year-old man reported right lateral heel pain 11 years after ankle arthrodesis. Clinically, there was tenderness in the right sinus tarsi and over the junction point between the talonavicular and calcaneocuboid joints. Radiographs showed that the joint spaces of the posterior subtalar joint and the talonavicular joint were preserved although there were osteophytes at both joints. Arthroscopic findings showed degeneration of the anterior subtalar and talonavicular joints. The symptoms subsided after arthroscopic debridement.

  4. Estimating the time course of population excitatory postsynaptic potentials in motoneurons of spastic stroke survivors.

    PubMed

    Hu, Xiaogang; Suresh, Nina L; Rymer, William Z

    2015-03-15

    Hyperexcitable motoneurons are likely to contribute to muscle hypertonia after a stroke injury; however, the origins of this hyperexcitability are not clear. One possibility is that the effective duration of the Ia excitatory postsynaptic potential (EPSP) is prolonged, increasing the potential for temporal summation of EPSPs, making action potential initiation easier. Accordingly, the purpose of this study was to quantify the time course of EPSPs in motoneurons of stroke survivors. The experimental protocol, which was based on parameters derived from simulation, involved sequential subthreshold electrical stimuli delivered to the median nerve of hemispheric stroke survivors. The resulting H-reflex responses were recorded in the flexor carpi radialis muscle. H-reflex response probability was then used to quantify the time course of the underlying EPSPs in the motoneuron pool. A population EPSP was estimated based on the probability of evoking an H reflex from the second electrical stimulus in the absence of a reflex response to the first stimulus. The accuracy of this time-course estimate was quantified using a computer simulation that explored a range of feasible EPSP parameters. Our experimental results showed that in all five hemispheric stroke survivors the rate of decay of the population EPSP was consistently slower in spastic compared with the contralateral motoneuron pools. We propose that one potential mechanism for hyperexcitability of motoneurons in spastic stroke survivors may be linked to this prolongation of the Ia EPSP time course. Our subthreshold double-stimulation approach also provides a noninvasive tool for quantifying the time course of EPSPs in both healthy and pathological conditions.

  5. Electrical coupling synchronises spinal motoneuron activity during swimming in hatchling Xenopus tadpoles.

    PubMed

    Zhang, Hong-Yan; Li, Wen-Chang; Heitler, William J; Sillar, Keith T

    2009-09-15

    The role of electrical coupling between neurons in the swimming rhythm generator of Xenopus embryos has been studied using pharmacological blockade of gap junctions. A conspicuous effect of 18beta-glycyrrhetinic acid (18beta-GA) and carbenoxolone, which have been shown to block electrical coupling in this preparation, was to increase the duration of ventral root bursts throughout the spinal cord during swimming. The left-right coordination, the swimming frequency and the duration of swimming episodes were not affected by concentrations of 18beta-GA which significantly increased burst durations. However, the longitudinal coupling was affected such that 18beta-GA led to a significant correlation between rostrocaudal delays and cycle periods, which is usually only present in older larval animals. Patch clamp recordings from spinal motoneurons tested whether gap junction blockers affect the spike timing and/or firing pattern of motoneurons during fictive swimming. In the presence of 18beta-GA motoneurons continued to fire a single, but broader action potential in each cycle of swimming, and the timing of their spikes relative to the ventral root burst became more variable. 18beta-GA had no detectable effect on the resting membrane potential of motoneurons, but led to a significant increase in input resistance, consistent with the block of gap junctions. This effect did not result in increased firing during swimming, despite the fact that multiple spikes can occur in response to current injection. Applications of 18beta-GA at larval stage 42 had no discernible effect on locomotion. The results, which suggest that electrical coupling primarily functions to synchronize activity in synergistic motoneurons during embryo swimming, are discussed in the context of motor system development.

  6. Eye Movements and Abducens Motoneuron Behavior During Cholinergically Induced REM Sleep

    PubMed Central

    Marquez-Ruiz, Javier; Escudero, Miguel

    2009-01-01

    Study objectives: The injection of cholinergic drugs in the pons has been largely used to induce REM sleep as a useful model to study different processes during this period. In the present study, microinjections of carbachol in the nucleus reticularis pontis oralis (NRPO) were performed to test the hypothesis that eye movements and the behavior of extraocular motoneurons during induced REM sleep do not differ from those during spontaneous REM sleep. Methods: Six female adult cats were prepared for chronic recording of eye movements (by means of the search-coil technique) and electroencephalography, electromyography, ponto-geniculo-occipital (PGO) waves at the lateral geniculate nucleus, and identified abducens motoneuron activities after microinjections of the cholinergic agonist carbachol into the NRPO. Results: Unilateral microinjections (n = 13) of carbachol in the NRPO induced REM sleep-like periods in which the eyes performed a convergence and downward rotation interrupted by phasic complex rapid eye movements associated to PGO waves. During induced-REM sleep abducens motoneurons lost their tonic activity and eye position codification, but continued codifying eye velocity during the burst of eye movements. Conclusion: The present results show that eye movements and the underlying behavior of abducens motoneurons are very similar to those present during natural REM sleep. Thus, microinjection of carbachol seems to activate the structures responsible for the exclusive oculomotor behavior observed during REM sleep, validating this pharmacological model and enabling a more efficient exploration of phasic and tonic phenomena underlying eye movements during REM sleep. Citation: Marquez-Ruiz J; Escudero M. Eye movements and abducens motoneuron behavior during cholinergically induced REM sleep. SLEEP 2009;32(4):471–481. PMID:19413141

  7. Forces predicted at the ankle during running.

    PubMed

    Burdett, R G

    1982-01-01

    A biomechanical model of the ankle joint was developed and was used to predict the forces at the ankle during the stance phase of running. Measurements from five cadavers were averaged to obtain insertion points and directions of pull of equivalent tendons with respect to the assumed center of the ankle joint. A minimum joint force solution was obtained by assuming that only two equivalent muscle groups could exert force at one time. Three subjects ran at 4.47 m/s across a force platform that recorded the external forces and moments acting on the foot. Cinematography was used to measure the foot and leg positions during stance. Peak resultant joint forces ranging from 9.0 to 13.3 times body weight and peak Achilles tendon forces ranging from 5.3 to 10.0 times body weight were predicted. Small variations in some cases resulted in large differences in predicted forces. The highest tendon forces predicted exceeded those reported to cause damage to cadaver tendons in other studies.

  8. Orthopedic rehabilitation using the "Rutgers ankle" interface.

    PubMed

    Girone, M; Burdea, G; Bouzit, M; Popescu, V; Deutsch, J E

    2000-01-01

    A novel ankle rehabilitation device is being developed for home use, allowing remote monitoring by therapists. The system will allow patients to perform a variety of exercises while interacting with a virtual environment (VE). These game-like VEs created with WorldToolKit run on a host PC that controls the movement and output forces of the device via an RS232 connection. Patients will develop strength, flexibility, coordination, and balance as they interact with the VEs. The device will also perform diagnostic functions, measuring the ankle's range of motion, force exertion capabilities and coordination. The host PC transparently records patient progress for remote evaluation by therapists via our existing telerehabilitation system. The "Rutgers Ankle" Orthopedic Rehabilitation Interface uses double-acting pneumatic cylinders, linear potentiometers, and a 6 degree-of-freedom (DOF) force sensor. The controller contains a Pentium single-board computer and pneumatic control valves. Based on the Stewart platform, the device can move and supply forces and torques in 6 DOFs. A proof-of-concept trial conducted at the University of Medicine and Dentistry of New Jersey (UMDNJ) provided therapist and patient feedback. The system measured the range of motion and maximum force output of a group of four patients (male and female). Future medical trials are required to establish clinical efficacy in rehabilitation.

  9. Posterior malleolar fractures of the ankle.

    PubMed

    Bartoníček, J; Rammelt, S; Tuček, M; Naňka, O

    2015-12-01

    Despite an increasing awareness of injuries to PM in ankle fracture-dislocations, there are still many open questions. The mere presence of a posterior fragment leads to significantly poorer outcomes. Adequate diagnosis, classification and treatment require preoperative CT examination, preferably with 3D reconstructions. The indication for surgical treatment is made individually on the basis of comprehensive assessment of the three-dimensional outline of the PM fracture and all associated injuries to the ankle including syndesmotic instability. Anatomic fixation of the avulsed posterior tibiofibular ligament will contribute to syndesmotic stability and restore the integrity of the incisura tibiae thus facilitating anatomic reduction of the distal fibula. A necessary prerequisite is mastering of posterolateral and posteromedial approaches and the technique of direct reduction and internal fixation. Further clinical studies with higher numbers of patients treated by similar methods and evaluation of pre- and postoperative CT scans will be necessary to determine reliable prognostic factors associated with certain types of PM fractures and associated injuries to the ankle.

  10. Neuromuscular control and rehabilitation of the unstable ankle

    PubMed Central

    Hung, You-jou

    2015-01-01

    Lateral ankle sprain is a common orthopedic injury with a very high recurrence rate in athletes. After decades of research, it is still unclear what contributes to the high recurrence rate of ankle sprain, and what is the most effective intervention to reduce the incident of initial and recurrent injuries. In addition, clinicians often implement balance training as part of the rehabilitation protocol in hopes of enhancing the neuromuscular control and proprioception of the ankle joint. However, there is no consensus on whether the neuromuscular control and proprioception are compromised in unstable ankles. To reduce the prevalence of ankle sprains, the effectiveness of engaging balance training to enhance the neuromuscular control and proprioception of the ankle joint is also questionable. PMID:26085985

  11. Talar Osteochondroma Fracture Presenting as Posterior Ankle Impingement.

    PubMed

    Ercin, Ersin; Bilgili, Mustafa Gokhan; Gamsizkan, Mehmet; Avsar, Serdar

    2016-05-01

    Osteochondromas are the most common benign bone tumors. They are usually asymptomatic and found incidentally. When symptomatic, the symptoms are usually due to its location and size. Fracture of an osteochondroma presenting as posterior ankle impingement is a rare condition. We describe a 22-year-old man with solitary exostosis who presented with a posterior ankle mass and posterior ankle impingement with 2 years of follow-up. Surgical intervention was the treatment of choice in this patient, and histologic examination revealed a benign osteochondroma. Osteochondromas found in the posterior aspect of the talus can be complicated by fracture due to persistent motion of the ankle. Talar osteochondroma should be included in the differential diagnosis of posterior ankle impingement causes. Posterior talar osteochondromas, especially when a stalk is present, should be treated surgically before it is more complicated by a fracture and posterior ankle impingement.

  12. [Advances on biomechanics and kinematics of sprain of ankle joint].

    PubMed

    Zhao, Yong; Wang, Gang

    2015-04-01

    Ankle sprains are orthopedic clinical common disease, accounting for joint ligament sprain of the first place. If treatment is not timely or appropriate, the joint pain and instability maybe develop, and even bone arthritis maybe develop. The mechanism of injury of ankle joint, anatomical basis has been fully study at present, and the diagnostic problem is very clear. Along with the development of science and technology, biological modeling and three-dimensional finite element, three-dimensional motion capture system,digital technology study, electromyographic signal study were used for the basic research of sprain of ankle. Biomechanical and kinematic study of ankle sprain has received adequate attention, combined with the mechanism research of ankle sprain,and to explore the the biomechanics and kinematics research progress of the sprain of ankle joint.

  13. Design, modelling and simulation aspects of an ankle rehabilitation device

    NASA Astrophysics Data System (ADS)

    Racu, C. M.; Doroftei, I.

    2016-08-01

    Ankle injuries are amongst the most common injuries of the lower limb. Besides initial treatment, rehabilitation of the patients plays a crucial role for future activities and proper functionality of the foot. Traditionally, ankle injuries are rehabilitated via physiotherapy, using simple equipment like elastic bands and rollers, requiring intensive efforts of therapists and patients. Thus, the need of robotic devices emerges. In this paper, the design concept and some modelling and simulation aspects of a novel ankle rehabilitation device are presented.

  14. Assessment and management of patients with ankle injuries.

    PubMed

    Walker, Jennie

    2014-08-19

    Foot and ankle injuries are common and can have a significant effect on an individual's daily activities. Nurses have an important role in the assessment, management, ongoing care and support of patients with ankle injuries. An understanding of the anatomy and physiology of the ankle enables nurses to identify significant injuries, which may result in serious complications, and communicate effectively with the multidisciplinary team to improve patient care and outcomes.

  15. Ankle arthritis: review of diagnosis and operative management.

    PubMed

    Grunfeld, Robert; Aydogan, Umur; Juliano, Paul

    2014-03-01

    The diagnostic and therapeutic options for ankle arthritis are reviewed. The current standard of care for nonoperative options include the use of nonsteroidal antiinflammatory drugs, corticosteroid injections, orthotics, and ankle braces. Other modalities lack high-quality research studies to delineate their appropriateness and effectiveness. The gold standard for operative intervention in end-stage degenerative arthritis remains arthrodesis, but evidence for the superiority in functional outcomes of total ankle arthroplasty is increasing. The next few years will enable more informed decisions and, with more prospective high-quality studies, the most appropriate patient population for total ankle arthroplasty can be identified.

  16. Multivariable static ankle mechanical impedance with relaxed muscles.

    PubMed

    Lee, Hyunglae; Ho, Patrick; Rastgaar, Mohammad A; Krebs, Hermano I; Hogan, Neville

    2011-07-07

    Quantitative characterization of ankle mechanical impedance is important to understand how the ankle supports lower-extremity functions during interaction with the environment. This paper reports a novel procedure to characterize static multivariable ankle mechanical impedance. An experimental protocol using a wearable therapeutic robot, Anklebot, enabled reliable measurement of torque and angle data in multiple degrees of freedom simultaneously, a combination of inversion-eversion and dorsiflexion-plantarflexion. The measured multivariable torque-angle relation was represented as a vector field, and approximated using a method based on thin-plate spline smoothing with generalized cross validation. The vector field enabled assessment of several important characteristics of static ankle mechanical impedance, which are not available from prior single degree of freedom studies: the directional variation of ankle mechanical impedance, the extent to which the ankle behaves as a spring, and evidence of uniquely neural contributions. The method was validated by testing a simple physical "mock-up" consisting of passive elements. Experiments with young unimpaired subjects quantified the behavior of the maximally relaxed human ankle, showing that ankle mechanical impedance is spring-like but strongly direction-dependent, being weakest in inversion. Remarkably, the analysis was sufficiently sensitive to detect a subtle but statistically significant deviation from spring-like behavior if subjects were not fully relaxed. This method may provide new insight about the function of the ankle, both unimpaired and after biomechanical or neurological injury.

  17. Influence of the paraventricular nucleus and oxytocin on the retrograde stain of pubococcygeus muscle motoneurons in male rats.

    PubMed

    Pérez, César Antonio; Concha, Adriana; Hernández, María Elena; Manzo, Jorge

    2005-04-11

    Lumbosacral cord motoneurons innervating the pubococcygeus muscle (Pcm) at the pelvic floor of male rats were analyzed. We showed previously that these motoneurons participate in sexual functions and are sensitive to fluctuations of systemic androgen and estrogen. Though estrogen receptors have not been identified in Lamina IX at these spinal areas, the release of oxytocin from the paraventricular nucleus of the hypothalamus (PvN) has been found to control pelvic sexual physiology. We therefore worked on the hypothesis that steroid hormones in the PvN induce the release of oxytocin at the lumbosacral level to modulate the function of Pcm motoneurons. Four experiments were developed, and results were observed with the retrograde staining of motoneurons with horseradish peroxidase. Data indicated that morphometric parameters of Pcm motoneurons were significantly reduced after castration or blocking of the steroids at the PvN site, or following complete transection of the spinal cord at the T8 level. In each case, the reduction of the stain was recovered after intrathecal treatment with oxytocin. Thus, present results show that Pcm motoneurons respond to spinal oxytocin. The conclusive model that we propose is that steroids stimulate the PvN, causing the nucleus to release oxytocin at the level of the lumbosacral spinal cord, and the release of the peptide regulates the spread of the stain of Pcm motoneurons. This work also shows that motoneurons distal to a transected area in the spinal cord could respond to exogenous oxytocin, an important finding for the research of spinal cord lesioned subjects.

  18. Excitatory effect of histamine on rat spinal motoneurons by activation of both H₁ and H₂ receptors in vitro.

    PubMed

    Wu, Guan-Yi; Han, Xiao-Hu; Zhuang, Qian-Xing; Zhang, Jun; Yung, Wing-Ho; Chan, Ying-Shing; Zhu, Jing-Ning; Wang, Jian-Jun

    2012-01-01

    The central histaminergic nervous system, originating from the tuberomammillary nucleus of the hypothalamus, widely innervates almost the whole brain as well as the spinal cord. However, the effect of histamine on spinal motoneurons, the final common path for motor control, is still unknown. By using 8-14-day-old rat spinal slice preparations and intracellular recordings, the effect of histamine on motoneurons in lumbar spinal cord and the underlying mechanisms were studied. Bath application of histamine (30-300 μM) induced a membrane depolarization in the majority of recorded spinal motoneurons (78/90, 86%). Perfusing slices with tetrodotoxin or low-Ca(2+) /high-Mg(2+) medium did not block the histamine-induced excitation, indicating a direct postsynaptic action of histamine on motoneurons. Separate application of the selective histamine H(1) receptor antagonist mepyramine or the selective histamine H(2) receptor antagonist ranitidine partially suppressed the histamine-induced excitation, whereas a combination of ranitidine and mepyramine totally blocked the excitatory effect of histamine on motoneurons. On the other hand, both the selective histamine H(1) receptor agonist 2-pyridylethylamine and the selective histamine H(2) receptor agonist dimaprit mimicked the excitation of histamine on spinal motoneurons. These agonist-induced excitations were also blocked by mepyramine or ranitidine. Furthermore, histamine affected membrane input resistance and potentiated repetitive firing behavior of spinal motoneurons. These results demonstrate that histamine excites rat spinal motoneurons via the histamine H(1) and H(2) receptors and increases their excitability, suggesting that the hypothalamospinal histaminergic fibers may directly modulate final motor outputs and actively regulate ongoing motor execution andspinal motor reflexes.

  19. Electrical interaction between antidromically stimulated frog motoneurones and dorsal root afferents: enhancement by gallamine and TEA

    PubMed Central

    Grinnell, Alan D.

    1970-01-01

    1. Electrical interactions have been studied in the isolated frog spinal cord preparation. It is found that gallamine and tetraethylammonium chloride (TEA) markedly enhance all non-cholinergic synaptic interactions, including the electrical interaction between motoneurones (VR-VRP). In addition, in the presence of either of these drugs, a short-latency interaction is seen to exist between antidromically stimulated motoneurones and dorsal root afferents (early VR-DRP). The early VR-DRP is rarely seen in the absence of gallamine or TEA. 2. The early VR-DRP is of the same short latency as the VR-VRP and fulfils the same criteria for electrical interaction: it increases in amplitude with cooling from 17-10° C, it is not blocked by a wide variety of pharmacological blocking agents, and it is suppressed by both Mg2+ and Ca2+, with no antagonism of action between the two. 3. The early VR-DRP appears as a cluster of unitary events: all-or-none spikes conducted out the dorsal root fibres. No initial graded slow potentials are seen. Often there are two peaks in the response. 4. The early VR-DRP is facilitated by a dorsal root volley, with a time course normally intermediate between that of the orthodromic ventral root potential (DR-VRP) and the dorsal root potential (DR-DRP). This orthodromic facilitation apparently is achieved by increasing invasion of motoneurone dendritic trees and depolarization of dorsal root afferents toward threshold. 5. If the same ventral root is stimulated twice, or adjacent roots stimulated at different intervals, the second early VR-DRP, like the VR-VRP, is seen to be occluded for 10-20 msec, then facilitated to supranormal amplitudes. It is concluded that motoneurone dendrites are presynaptic to both interactions. 6. Evidence is presented that gallamine and TEA act by increasing the duration of activity both in axon terminals and in antidromically invaded motoneurones. Often second or multiple spikes result. The increased duration of

  20. Bone marrow transplantation in hindlimb muscles of motoneuron degenerative mice reduces neuronal death and improves motor function.

    PubMed

    Pastor, Diego; Viso-León, Mari Carmen; Botella-López, Arancha; Jaramillo-Merchan, Jesus; Moraleda, Jose M; Jones, Jonathan; Martínez, Salvador

    2013-06-01

    Bone marrow has proved to be an adequate source of stem cells for the treatment of numerous disorders, including neurodegenerative diseases. Bone marrow can be easily and relatively painlessly extracted from a patient or allogenic donor and then transplanted into the degenerative area. Here, the grafted cells will activate a number of mechanisms in order to protect, repair, and/or regenerate the damaged tissue. These properties make the bone marrow a feasible source for cell therapy. In this work, we transplanted bone marrow cells into a mouse model of motoneuron degeneration, with the particularity of placing the cells in the hindlimb muscles rather than in the spinal cord where neuronal degeneration occurs. To this end, we analyze the possibility for the transplanted cells to increase the survival rate of the spinal cord motoneurons by axonal-guided retrograde neurotrophism. As a result, the mice significantly improved their motor functions. This coincided with an increased number of motoneurons innervating the treated muscle compared with the neurons innervating the non-treated contralateral symmetric muscle. In addition, we detected an increase in glial-derived neurotrophic factor in the spinal cord, a neurotrophic factor known to be involved in the rescue of degenerating motoneurons, exerting a neuroprotective effect. Thus, we have proved that bone marrow injected into the muscles is capable of rescuing these motoneurons from death, which may be a possible therapeutic approach for spinal cord motoneuron degenerative diseases, such as amyotrophic lateral sclerosis.

  1. Neonatal motoneurons overexpressing the bcl-2 protooncogene in transgenic mice are protected from axotomy-induced cell death.

    PubMed Central

    Dubois-Dauphin, M; Frankowski, H; Tsujimoto, Y; Huarte, J; Martinou, J C

    1994-01-01

    In vitro, the overexpression of the bcl-2 protooncogene in cultured neurons has been shown to prevent apoptosis induced by neurotrophic factor deprivation. We have generated transgenic mice overexpressing the Bcl-2 protein in neurons, including motoneurons of the facial nucleus. We have tested whether Bcl-2 could protect these motoneurons from experimentally induced cell death in new born mice. To address this question, we performed unilateral lesion of the facial nerve of wild-type and transgenic 2-day-old mice. In wild-type mice, the lesioned nerve and the corresponding motoneuron cell bodies in the facial nucleus underwent rapid degeneration. In contrast, in transgenic mice, facial motoneurons survived axotomy. Not only their cell bodies but also their axons were protected up to the lesion site. These results demonstrate that in vivo Bcl-2 protects neonatal motoneurons from degeneration after axonal injury. A better understanding of the mechanisms by which Bcl-2 prevents neuronal cell death in vivo could lead to the development of strategies for the treatment of motoneuron degenerative diseases. Images PMID:8159744

  2. Restricted patterns of Hoxd10 and Hoxd11 set segmental differences in motoneuron subtype complement in the lumbosacral spinal cord

    PubMed Central

    Misra, Mala; Shah, Veeral; Carpenter, Ellen; McCaffery, Peter; Lance-Jones, Cynthia

    2009-01-01

    During normal vertebrate development, Hoxd10 and Hoxd11 are expressed by differentiating motoneurons in restricted patterns along the rostrocaudal axis of the lumbosacral (LS) spinal cord. To assess the roles of these genes in the attainment of motoneuron subtypes characteristic of LS subdomains, we examined subtype complement after overexpression of Hoxd10 or Hoxd11 in the embryonic chick LS cord and in a Hoxd10 loss-of-function mouse embryo. Data presented here provide evidence that Hoxd10 defines the position of the lateral motor column (LMC) as a whole and, in rostral LS segments, specifically promotes the development of motoneurons of the lateral subdivision of the lateral motor column (LMCl). In contrast, Hoxd11 appears to impart a caudal and medial LMC (LMCm) identity to some motoneurons and molecular profiles suggestive of a suppression of LMC development in others. We also provide evidence that Hoxd11 suppresses the expression of Hoxd10 and the retinoic acid synthetic enzyme, retinaldehyde dehydrogenase 2 (RALDH2). In a normal chick embryo, Hoxd10 and RALDH2 are expressed throughout the LS region at early stages of motoneuron differentiation but their levels decline in Hoxd11-expressing caudal LS segments that ultimately contain few LMCl motoneurons. We hypothesize that one of the roles played by Hoxd11 is to modulate Hoxd10 and local retinoic acid levels and thus, perhaps define the caudal boundaries of the LMC and its subtype complement. PMID:19306865

  3. The influence of a 5-wk whole body vibration on electrophysiological properties of rat hindlimb spinal motoneurons.

    PubMed

    Baczyk, M; Hałuszka, A; Mrówczyński, W; Celichowski, J; Krutki, P

    2013-06-01

    The study aimed at determining the influence of a whole body vibration (WBV) on electrophysiological properties of spinal motoneurons. The WBV training was performed on adult male Wistar rats, 5 days a week, for 5 wk, and each daily session consisted of four 30-s runs of vibration at 50 Hz. Motoneuron properties were investigated intracellularly during experiments on deeply anesthetized animals. The experimental group subjected to the WBV consisted of seven rats, and the control group of nine rats. The WBV treatment induced no significant changes in the passive membrane properties of motoneurons. However, the WBV-evoked adaptations in excitability and firing properties were observed, and they were limited to fast-type motoneurons. A significant decrease in rheobase current and a decrease in the minimum and the maximum currents required to evoke steady-state firing in motoneurons were revealed. These changes resulted in a leftward shift of the frequency-current relationship, combined with an increase in slope of this curve. The functional relevance of the described adaptive changes is the ability of fast motoneurons of rats subjected to the WBV to produce series of action potentials at higher frequencies in a response to the same intensity of activation. Previous studies proved that WBV induces changes in the contractile parameters predominantly of fast motor units (MUs). The data obtained in our experiment shed a new light to possible explanation of these results, suggesting that neuronal factors also play a substantial role in MU adaptation.

  4. Inhibitory synaptic drive patterns motoneuronal activity in rhythmic preparations of isolated thoracic ganglia in the stick insect.

    PubMed

    Büschges, A

    1998-02-09

    During active leg movements of an insect leg, the activity of the motoneuron pools of each individual leg joint is generated by the interaction between signals from central rhythm generating sources, peripheral signals as well as coordinating signals from other leg joints and legs. The nature of the synaptic drive from the central rhythm generators onto the motoneuron pools of the individual leg joints during rhythmic motor activity of the stick insect (Carausius morosus) middle leg has been investigated. In the isolated mesothoracic ganglion central rhythm generators were activated pharmacologically by topical application of the muscarinic agonist pilocarpine. Motoneurons supplying the femur-tibia (FT) joint were investigated in detail. Recordings from neuropil processes of these motoneurons revealed that patterning of their rhythmic activity is based on cyclic hyperpolarizing synaptic inputs. These inputs are in clear antiphase for extensor and flexor motoneurons. DCC (discontinuous current clamp) and dSEVC (discontinuous single electrode voltage clamp) recordings showed reversal potentials of the inhibitory inputs between -80 to -85 mV (FETi, N=7; Flex MN, N=3). After intracellular injection of TEA rhythmic inhibition in FETi was decreased by about 84% (N=4). Both findings indicate that the cyclic inhibition is mediated by potassium ions. Thus, it appears that central rhythm generators pattern motor activity in antagonistic tibial motoneuron pools by cyclic alternating inhibition.

  5. Potassium currents dynamically set the recruitment and firing properties of F-type motoneurons in neonatal mice

    PubMed Central

    Lamotte d'Incamps, Boris; Zytnicki, Daniel

    2015-01-01

    In neonatal mice, fast- and slow-type motoneurons display different patterns of discharge. In response to a long liminal current pulse, the discharge is delayed up to several seconds in fast-type motoneurons and their firing frequency accelerates. In contrast, slow-type motoneurons discharge immediately, and their firing frequency decreases at the beginning of the pulse. Here, we identify the ionic currents that underlie the delayed firing of fast-type motoneurons. We find that the firing delay is caused by a combination of an A-like potassium current that transiently suppresses firing on a short time scale and a slowly-inactivating potassium current that inhibits the discharge over a much longer time scale. We then show how these intrinsic currents dynamically shape the discharge threshold and the frequency-input function of fast-type motoneurons. These currents contribute to the orderly recruitment of motoneurons in neonates and might play a role in the postnatal maturation of motor units. PMID:26269551

  6. Bone Marrow Transplantation in Hindlimb Muscles of Motoneuron Degenerative Mice Reduces Neuronal Death and Improves Motor Function

    PubMed Central

    Viso-León, Mari Carmen; Botella-López, Arancha; Jaramillo-Merchan, Jesus; Moraleda, Jose M.; Jones, Jonathan; Martínez, Salvador

    2013-01-01

    Bone marrow has proved to be an adequate source of stem cells for the treatment of numerous disorders, including neurodegenerative diseases. Bone marrow can be easily and relatively painlessly extracted from a patient or allogenic donor and then transplanted into the degenerative area. Here, the grafted cells will activate a number of mechanisms in order to protect, repair, and/or regenerate the damaged tissue. These properties make the bone marrow a feasible source for cell therapy. In this work, we transplanted bone marrow cells into a mouse model of motoneuron degeneration, with the particularity of placing the cells in the hindlimb muscles rather than in the spinal cord where neuronal degeneration occurs. To this end, we analyze the possibility for the transplanted cells to increase the survival rate of the spinal cord motoneurons by axonal-guided retrograde neurotrophism. As a result, the mice significantly improved their motor functions. This coincided with an increased number of motoneurons innervating the treated muscle compared with the neurons innervating the non-treated contralateral symmetric muscle. In addition, we detected an increase in glial-derived neurotrophic factor in the spinal cord, a neurotrophic factor known to be involved in the rescue of degenerating motoneurons, exerting a neuroprotective effect. Thus, we have proved that bone marrow injected into the muscles is capable of rescuing these motoneurons from death, which may be a possible therapeutic approach for spinal cord motoneuron degenerative diseases, such as amyotrophic lateral sclerosis. PMID:23282201

  7. Increased intramuscular nerve branching and inhibition of programmed cell death of chick embryo motoneurons by immunoglobulins from patients with motoneuron disease.

    PubMed

    Hernández, Sara; Texidó, Laura; Calderó, Jordi; Ciutat, Dolors; Piedrafita, Lídia; Casanovas, Anna; Blasi, Joan; Solsona, Carles; Povedano, Mònica; Rojas, Ricardo; Illa, Isabel; Caress, James; Prevette, David; Oppenheim, Ronald W; Milligan, Carol; Esquerda, Josep E

    2010-12-15

    Massive programmed cell death (PCD) of developing chick embryo motoneurons (MNs) occurs in a well defined temporal and spatial sequence between embryonic day (E) 6 and E10. We have found that, when administered in ovo, either circulating immunoglobulins G (IgGs) or cerebrospinal fluid from patients with MN disease can rescue a significant number of chick embryo MNs from normally occurring PCD. An increase of branching of intramuscular nerves was also observed that may account for the rescuing effects of pathologic IgGs. Proteomic analysis and further analysis by ELISA indicated that these effects may be mediated by the interaction of circulating human immunoglobulins with proteins of the semaphorin family.

  8. The lumbar cord location of the motoneurons innervating psoas and iliacus muscles: a single and double labeling study in the female Syrian golden hamster.

    PubMed

    Gerrits, P O; Boers, J; Holstege, G

    1997-11-21

    The spinal cord location of the motoneurons innervating the psoas and iliacus muscles was determined in the golden hamster. The results of single and double labeling studies, using the retrograde tracers horseradish peroxidase (HRP) and cholera toxin B-subunit (CTB), showed that both psoas and iliacus motoneurons were present ventrolaterally in the ventral horn in the caudal L1 to rostral L5 lumbar spinal segments with their motoneurons intermingled in one cell group. Further retrograde tracing studies demonstrated abdominal muscle motoneurons ventrolaterally in the ventral horn of the L1 and upper L2 segments. Double labeling experiments revealed that at these levels (caudal L1 and rostral L2), the abdominal muscle motoneurons were located dorsomedial to the psoas and iliacus motoneurons.

  9. 10-year survival of total ankle arthroplasties

    PubMed Central

    2011-01-01

    Background and purpose There is an ongoing need to review large series of total ankle replacements (TARs) for monitoring of changes in practice and their outcome. 4 national registries, including the Swedish Ankle Register, have previously reported their 5-year results. We now present an extended series with a longer follow-up, and with a 10-year survival analysis. Patients and methods Records of uncemented 3-component TARs were retrospectively reviewed, determining risk factors such as age, sex, and diagnosis. Prosthetic survival rates were calculated with exchange or removal of components as endpoint—excluding incidental exchange of the polyethylene meniscus. Results Of the 780 prostheses implanted since 1993, 168 (22%) had been revised by June 15, 2010. The overall survival rate fell from 0.81 (95% CI: 0.79–0.83) at 5 years to 0.69 (95% CI: 0.67–0.71) at 10 years. The survival rate was higher, although not statistically significantly so, during the latter part of the period investigated. Excluding the STAR prosthesis, the survival rate for all the remaining designs was 0.78 at 10 years. Women below the age of 60 with osteoarthritis were at a higher risk of revision, but age did not influence the outcome in men or women with rheumatoid arthritis. Revisions due to technical mistakes at the index surgery and instability were undertaken earlier than revisions for other reasons. Interpretation The results have slowly improved during the 18-year period investigated. However, we do not believe that the survival rates of ankle replacements in the near future will approach those of hip and knee replacements—even though improved instrumentation and design of the prostheses, together with better patient selection, will presumably give better results. PMID:22066551

  10. A Survey of Parachute Ankle Brace Breakages

    DTIC Science & Technology

    2008-01-10

    reduced since it was subject to abrasion from the concrete in the harness shed, asphalt on the loading ramp, and dirt on the drop zone. b. DJ...strap was also directly under the heel and subject to abrasion from concrete in the harness shed, asphalt on the loading ramp, and dirt on the drop...airborne injuries), airborne students who did not wear the brace were 1.90 times more likely to experience an ankle sprain, 1.47 times more likely to

  11. Normal Variants: Accessory Muscles About the Ankle.

    PubMed

    Cheung, Yvonne

    2017-02-01

    Accessory muscles around the ankle are commonly encountered as incidental findings on cross-sectional imaging. Mostly asymptomatic, accessory muscles sometimes mimic mass lesions. They have been implicated as the cause of tarsal tunnel syndrome, impingement of surrounding structures, and chronic pain. Distinguishing these muscles can be challenging, because some travel along a similar path. This article describes these accessory muscles in detail, including their relationships to the aponeurosis of the lower leg. An imaging algorithm is proposed to aid in identification of these muscles, providing a valuable tool in diagnostic accuracy and subsequent patient management.

  12. Robotic Ankle for Omnidirectional Rock Anchors

    NASA Technical Reports Server (NTRS)

    Parness, Aaron; Frost, Matthew; Thatte, Nitish

    2013-01-01

    Future robotic exploration of near-Earth asteroids and the vertical and inverted rock walls of lava caves and cliff faces on Mars and other planetary bodies would require a method of gripping their rocky surfaces to allow mobility without gravitational assistance. In order to successfully navigate this terrain and drill for samples, the grippers must be able to produce anchoring forces in excess of 100 N. Additionally, the grippers must be able to support the inertial forces of a moving robot, as well gravitational forces for demonstrations on Earth. One possible solution would be to use microspine arrays to anchor to rock surfaces and provide the necessary load-bearing abilities for robotic exploration of asteroids. Microspine arrays comprise dozens of small steel hooks supported on individual suspensions. When these arrays are dragged along a rock surface, the steel hooks engage with asperities and holes on the surface. The suspensions allow for individual hooks to engage with asperities while the remaining hooks continue to drag along the surface. This ensures that the maximum possible number of hooks engage with the surface, thereby increasing the load-bearing abilities of the gripper. Using the microspine array grippers described above as the end-effectors of a robot would allow it to traverse terrain previously unreachable by traditional wheeled robots. Furthermore, microspine-gripping robots that can perch on cliffs or rocky walls could enable a new class of persistent surveillance devices for military applications. In order to interface these microspine grippers with a legged robot, an ankle is needed that can robotically actuate the gripper, as well as allow it to conform to the large-scale irregularities in the rock. The anchor serves three main purposes: deploy and release the anchor, conform to roughness or misalignment with the surface, and cancel out any moments about the anchor that could cause unintentional detachment. The ankle design contains a

  13. Adaptive sports ankle prosthetics. Interview by Sarah A. Curran.

    PubMed

    Lyle, David K

    2012-09-01

    Participating in sport at all levels is gaining a dedicated following and this is also apparent in individuals with an amputation. Currently, there is a wide variety of ankle prostheses available which attempt to provide function, control, and comfort, as well as good aesthetic appeal. Participation in sport, however, increases the demands placed upon ankle prostheses. This can compromise function and performance, and constrain the opportunities of participation in various outdoor and water sports. In acknowledging this limitation and the need to develop more versatile ankle prostheses, this article introduces the evolution of a prototype ankle prosthesis referred to as "Adaptive Sports Ankle." The ankle prosthesis, which is compatible with any foot pyramid adapter, offers the same range of motion as the normal human ankle joint and is made up of components that are chemical and corrosion resistant. These design features that are specifically created to accommodate below-the-knee amputees provide an ideal prosthesis for those wishing to lead an active lifestyle and participate in aquatic (i.e. swimming, surfing, and scuba diving), snowboarding, and equestrian activities. Although it is acknowledged that there is a need to establish research on the Adaptive Sports Ankle, its introduction to the market will enhance and expand opportunities of those individuals with a lower limb amputation to lead an active and healthy lifestyle.

  14. How to Strengthen Your Ankle After a Sprain

    MedlinePlus

    ... of the band with your hand and gently push your ankle down as far as you can and then back to the starting ... with your foot pointing down and pull your ankle up as far as you can. Return to the ...

  15. Review on design and control aspects of ankle rehabilitation robots.

    PubMed

    Jamwal, Prashant K; Hussain, Shahid; Xie, Sheng Q

    2015-03-01

    Ankle rehabilitation robots can play an important role in improving outcomes of the rehabilitation treatment by assisting therapists and patients in number of ways. Consequently, few robot designs have been proposed by researchers which fall under either of the two categories, namely, wearable robots or platform-based robots. This paper presents a review of both kinds of ankle robots along with a brief analysis of their design, actuation and control approaches. While reviewing these designs it was observed that most of them are undesirably inspired by industrial robot designs. Taking note of the design concerns of current ankle robots, few improvements in the ankle robot designs have also been suggested. Conventional position control or force control approaches, being used in the existing ankle robots, have been reviewed. Apparently, opportunities of improvement also exist in the actuation as well as control of ankle robots. Subsequently, a discussion on most recent research in the development of novel actuators and advanced controllers based on appropriate physical and cognitive human-robot interaction has also been included in this review. Implications for Rehabilitation Ankle joint functions are restricted/impaired as a consequence of stroke or injury during sports or otherwise. Robots can help in reinstating functions faster and can also work as tool for recording rehabilitation data useful for further analysis. Evolution of ankle robots with respect to their design and control aspects has been discussed in the present paper and a novel design with futuristic control approach has been proposed.

  16. Find an Orthopaedic Foot and Ankle MD/DO

    MedlinePlus

    ... of the Smaller Toes How To... Foot Health Foot Injury Footwear News Videos Find a Surgeon Información en ... all ages. They perform reconstructive procedures, treat sports injuries, and manage and treat trauma of the foot and ankle. Orthopaedic foot and ankle surgeons work ...

  17. Rehabilitation of the Ankle after Acute Sprain or Chronic Instability.

    ERIC Educational Resources Information Center

    Mattacola, Carl G.; Dwyer, Maureen K.

    2002-01-01

    Outlines rehabilitation concepts applicable to acute and chronic ankle injury, providing evidence for current techniques used in ankle rehabilitation and describing a functional rehabilitation program that progresses from basic to advanced, while taking into account empirical data from the literature and clinical practice. The article notes that…

  18. Descending pathways to the cutaneus trunci muscle motoneuronal cell group in the cat

    NASA Technical Reports Server (NTRS)

    Holstege, Gert; Blok, Bertil F.

    1989-01-01

    The descending pathways to the motoneuronal cell group of the cutaneous trunci muscle (CTM) of the cat were investigated by injecting H-3-labeled lucine into the brain stem, the diencephalon, or the C1, C2, C6, and C8 segments of the spinal cord, and examining fixed autoradiographic sections of the spinal cord and brain regions. Results demonstrate presence of specific supraspinal projectons to the CTM motor nucleus originating in the contralateral nucleus retroambiguous and the ipsilateral dorsolateral pontine tegmentum. Results also suggest that propriospinal pathways to the CTM motor nucleus originating in the cervical cord do not exist, although these propriospinal projections to all other motoneuronal cell groups surrounding the CTM nucleus are very strong.

  19. Neuropathology in respiratory-related motoneurons in young Pompe (Gaa(-/-)) mice.

    PubMed

    Turner, Sara M F; Hoyt, Aaron K; ElMallah, Mai K; Falk, Darin J; Byrne, Barry J; Fuller, David D

    2016-06-15

    Respiratory and/or lingual dysfunction are among the first motor symptoms in Pompe disease, a disorder resulting from absence or dysfunction of the lysosomal enzyme acid α-glucosidase (GAA). Here, we histologically evaluated the medulla, cervical and thoracic spinal cords in 6 weeks old asymptomatic Pompe (Gaa(-/-)) mice to determine if neuropathology in respiratory motor regions has an early onset. Periodic acid-Schiff (PAS) staining indicated glycogen accumulation was exclusively occurring in Gaa(-/-) hypoglossal, mid-cervical and upper thoracic motoneurons. Markers of DNA damage (Tunel) and ongoing apoptosis (Cleaved Caspase 3) did not co-localize with PAS staining, but were prominent in a medullary region which included the nucleus tractus solitarius, and also in the thoracic spinal dorsal horn. We conclude that respiratory-related motoneurons are particularly susceptible to GAA deficiency and that neuronal glycogen accumulation and neurodegeneration may occur independently in early stage disease. The data support early therapeutic intervention in Pompe disease.

  20. The ER proteostasis network in ALS: Determining the differential motoneuron vulnerability.

    PubMed

    Rozas, Pablo; Bargsted, Leslie; Martínez, Francisca; Hetz, Claudio; Medinas, Danilo B

    2017-01-01

    Amyotrophic lateral sclerosis (ALS) is a fatal late-onset neurodegenerative disease characterized by the selective loss of motoneurons. The mechanisms underlying neuronal degeneration in ALS are starting to be elucidated, highlighting abnormal protein aggregation and altered mRNA metabolism as common phenomena. ALS involves the selective vulnerablility of a subpopulation of motoneurons, suggesting that intrinsic factors may determine ALS pathogenesis. Accumulating evidence indicates that alterations to endoplasmic reticulum (ER) proteostasis play a critical role on disease progression, representing one of the earliests pathological signatures of the disease. Here we discuss recent studies uncovering a fundamental role of ER stress as the driver of selective neuronal vulnerability in ALS and discuss the potential of targeting the unfolded protein response (UPR) as a therapeutic strategy to treat ALS.

  1. Understanding acute ankle ligamentous sprain injury in sports.

    PubMed

    Fong, Daniel Tp; Chan, Yue-Yan; Mok, Kam-Ming; Yung, Patrick Sh; Chan, Kai-Ming

    2009-07-30

    This paper summarizes the current understanding on acute ankle sprain injury, which is the most common acute sport trauma, accounting for about 14% of all sport-related injuries. Among, 80% are ligamentous sprains caused by explosive inversion or supination. The injury motion often happens at the subtalar joint and tears the anterior talofibular ligament (ATFL) which possesses the lowest ultimate load among the lateral ligaments at the ankle. For extrinsic risk factors to ankle sprain injury, prescribing orthosis decreases the risk while increased exercise intensity in soccer raises the risk. For intrinsic factors, a foot size with increased width, an increased ankle eversion to inversion strength, plantarflexion strength and ratio between dorsiflexion and plantarflexion strength, and limb dominance could increase the ankle sprain injury risk. Players with a previous sprain history, players wearing shoes with air cells, players who do not stretch before exercising, players with inferior single leg balance, and overweight players are 4.9, 4.3, 2.6, 2.4 and 3.9 times more likely to sustain an ankle sprain injury. The aetiology of most ankle sprain injuries is incorrect foot positioning at landing - a medially-deviated vertical ground reaction force causes an explosive supination or inversion moment at the subtalar joint in a short time (about 50 ms). Another aetiology is the delayed reaction time of the peroneal muscles at the lateral aspect of the ankle (60-90 ms). The failure supination or inversion torque is about 41-45 Nm to cause ligamentous rupture in simulated spraining tests on cadaver. A previous case report revealed that the ankle joint reached 48 degrees inversion and 10 degrees internal rotation during an accidental grade I ankle ligamentous sprain injury during a dynamic cutting trial in laboratory. Diagnosis techniques and grading systems vary, but the management of ankle ligamentous sprain injury is mainly conservative. Immobilization should not be

  2. Understanding acute ankle ligamentous sprain injury in sports

    PubMed Central

    Fong, Daniel TP; Chan, Yue-Yan; Mok, Kam-Ming; Yung, Patrick SH; Chan, Kai-Ming

    2009-01-01

    This paper summarizes the current understanding on acute ankle sprain injury, which is the most common acute sport trauma, accounting for about 14% of all sport-related injuries. Among, 80% are ligamentous sprains caused by explosive inversion or supination. The injury motion often happens at the subtalar joint and tears the anterior talofibular ligament (ATFL) which possesses the lowest ultimate load among the lateral ligaments at the ankle. For extrinsic risk factors to ankle sprain injury, prescribing orthosis decreases the risk while increased exercise intensity in soccer raises the risk. For intrinsic factors, a foot size with increased width, an increased ankle eversion to inversion strength, plantarflexion strength and ratio between dorsiflexion and plantarflexion strength, and limb dominance could increase the ankle sprain injury risk. Players with a previous sprain history, players wearing shoes with air cells, players who do not stretch before exercising, players with inferior single leg balance, and overweight players are 4.9, 4.3, 2.6, 2.4 and 3.9 times more likely to sustain an ankle sprain injury. The aetiology of most ankle sprain injuries is incorrect foot positioning at landing – a medially-deviated vertical ground reaction force causes an explosive supination or inversion moment at the subtalar joint in a short time (about 50 ms). Another aetiology is the delayed reaction time of the peroneal muscles at the lateral aspect of the ankle (60–90 ms). The failure supination or inversion torque is about 41–45 Nm to cause ligamentous rupture in simulated spraining tests on cadaver. A previous case report revealed that the ankle joint reached 48 degrees inversion and 10 degrees internal rotation during an accidental grade I ankle ligamentous sprain injury during a dynamic cutting trial in laboratory. Diagnosis techniques and grading systems vary, but the management of ankle ligamentous sprain injury is mainly conservative. Immobilization should not

  3. Multiple ionic mechanisms mediate inhibition of rat motoneurones by inhalation anaesthetics

    PubMed Central

    Sirois, Jay E; Pancrazio, Joseph J; Lynch, Carl; Bayliss, Douglas A

    1998-01-01

    We studied the effects of inhalation anaesthetics on the membrane properties of hypoglossal motoneurones in a neonatal rat brainstem slice preparation. In current clamp, halothane caused a membrane hyperpolarization that was invariably associated with decreased input resistance; in voltage clamp, halothane induced an outward current and increased input conductance. Qualitatively similar results were obtained with isoflurane and sevoflurane. The halothane current reversed near the predicted K+ equilibrium potential (EK) and was reduced in elevated extracellular K+ and in the presence of Ba2+ (2 mm). Moreover, the Ba2+-sensitive component of halothane current was linear and reversed near EK. The halothane current was not sensitive to glibenclamide or thyrotropin-releasing hormone (TRH). Therefore, the halothane current was mediated, in part, by activation of a Ba2+-sensitive K+ current distinct from the ATP- and neurotransmitter-sensitive K+ currents in hypoglossal motoneurones. Halothane also inhibited Ih, a hyperpolarization-activated cationic current; this was primarily due to a decrease in the absolute amount of current, although halothane also caused a small, but statistically significant, shift in the voltage dependence of Ih activation. Extracellular Cs+ (3 mm) blocked Ih and a component of halothane-sensitive current with properties reminiscent of Ih. A small component of halothane current, resistant to Ba2+ and Cs+, was observed in TTX-containing solutions at potentials depolarized to ∼−70 mV. Partial Na+ substitution by N-methyl-D-glucamine completely abolished this residual current, indicating that halothane also inhibited a TTX-resistant Na+ current active near rest potentials. Thus, halothane activates a Ba2+-sensitive, relatively voltage-independent K+ current and inhibits both Ih and a TTX-insensitive persistent Na+ current in hypoglossal motoneurones. These effects of halothane decrease motoneuronal excitability and may contribute to the

  4. Intramuscular AAV delivery of NT-3 alters synaptic transmission to motoneurons in adult rats

    PubMed Central

    Petruska, Jeffrey C.; Kitay, Brandon; Boyce, Vanessa S.; Kaspar, Brian; Pearse, Damien; Gage, Fred H.; Mendell, Lorne M.

    2010-01-01

    We examined whether elevating levels of neurotrophin-3 (NT-3) in the spinal cord and dorsal root ganglion (DRG) would alter connections made by muscle spindle afferent fibers on motoneurons. Adeno-associated virus (AAV) serotypes AAV1, AAV2 and AAV5, selected for their tropism profile, were engineered with the NT-3 gene and administered to the medial gastrocnemius muscle in adult rats. ELISA studies in muscle, DRG and spinal cord revealed that NT-3 concentration in all tissues peaked about 3 months after a single viral injection; after 6 months NT-3 concentration returned to normal values. Intracellular recording in triceps surae motoneurons revealed complex electrophysiological changes. Moderate elevation in cord NT-3 resulted in diminished segmental excitatory postsynaptic potential (EPSP) amplitude, perhaps as a result of the observed decrease in motoneuron input resistance. With further elevation in NT-3 expression, the decline in EPSP amplitude was reversed indicating that NT-3 at higher concentration could increase EPSP amplitude. No correlation was observed between EPSP amplitude and NT-3 concentration in the DRG. Treatment with control viruses could elevate NT-3 levels minimally resulting in measurable electrophysiological effects, perhaps as a result of inflammation associated with injection. EPSPs elicited by stimulation of the ventrolateral funiculus underwent a consistent decline in amplitude independent of NT-3 level. These novel correlations between modified NT-3 expression and single-cell electrophysiological parameters indicate that intramuscular administration of AAV(NT-3) can exert long lasting effects on synaptic transmission to motoneurons. This approach to neurotrophin delivery could be useful in modifying spinal function after injury. PMID:20849530

  5. Eye Movements and Abducens Motoneuron Behavior after Cholinergic Activation of the Nucleus Reticularis Pontis Caudalis

    PubMed Central

    Márquez-Ruiz, Javier; Escudero, Miguel

    2010-01-01

    Study Objectives: The aim of this work was to characterize eye movements and abducens (ABD) motoneuron behavior after cholinergic activation of the nucleus reticularis pontis caudalis (NRPC). Methods: Six female adult cats were prepared for chronic recording of eye movements (using the scleral search-coil technique), electroencephalography, electromyography, ponto-geniculo-occipital (PGO) waves in the lateral geniculate nucleus, and ABD motoneuron activities after microinjections of the cholinergic agonist carbachol into the NRPC. Results: Unilateral microinjections of carbachol in the NRPC induced tonic and phasic phenomena in the oculomotor system. Tonic effects consisted of ipsiversive rotation to the injected side, convergence, and downward rotation of the eyes. Phasic effects consisted of bursts of rhythmic rapid eye movements directed contralaterally to the injected side along with PGO-like waves in the lateral geniculate and ABD nuclei. Although tonic effects were dependent on the level of drowsiness, phasic effects were always present and appeared along with normal saccades when the animal was vigilant. ABD motoneurons showed phasic activities associated with ABD PGO-like waves during bursts of rapid eye movements, and tonic and phasic activities related to eye position and velocity during alertness. Conclusion The cholinergic activation of the NRPC induces oculomotor phenomena that are somewhat similar to those described during REM sleep. A precise comparison of the dynamics and timing of the eye movements further suggests that a temporal organization of both NRPCs is needed to reproduce the complexity of the oculomotor behavior during REM sleep. Citation: Márquez-Ruiz J; Escudero M. Eye movements and abducens motoneuron behavior after cholinergic activation of the nucleus reticularis pontis caudalis. SLEEP 2010;33(11):1517-1527. PMID:21102994

  6. Shaping the Output of Lumbar Flexor Motoneurons by Sacral Neuronal Networks.

    PubMed

    Cherniak, Meir; Anglister, Lili; Lev-Tov, Aharon

    2017-02-01

    The ability to improve motor function in spinal cord injury patients by reactivating spinal central pattern generators (CPGs) requires the elucidation of neurons and pathways involved in activation and modulation of spinal networks in accessible experimental models. Previously we reported on adrenoceptor-dependent sacral control of lumbar flexor motoneuron firing in newborn rats. The current work focuses on clarification of the circuitry and connectivity involved in this unique modulation and its potential use. Using surgical manipulations of the spinal gray and white matter, electrophysiological recordings, and confocal microscopy mapping, we found that methoxamine (METH) activation of sacral networks within the ventral aspect of S2 segments was sufficient to produce alternating rhythmic bursting (0.15-1 Hz) in lumbar flexor motoneurons. This lumbar rhythm depended on continuity of the ventral funiculus (VF) along the S2-L2 segments. Interrupting the VF abolished the rhythm and replaced it by slow unstable bursting. Calcium imaging of S1-S2 neurons, back-labeled via the VF, revealed that ∼40% responded to METH, mostly by rhythmic firing. All uncrossed projecting METH responders and ∼70% of crossed projecting METH responders fired with the concurrent ipsilateral motor output, while the rest (∼30%) fired with the contralateral motor output. We suggest that METH-activated sacral CPGs excite ventral clusters of sacral VF neurons to deliver the ascending drive required for direct rhythmic activation of lumbar flexor motoneurons. The capacity of noradrenergic-activated sacral CPGs to modulate the activity of lumbar networks via sacral VF neurons provides a novel way to recruit rostral lumbar motoneurons and modulate the output required to execute various motor behaviors.

  7. Effect of prolonged riluzole exposure on cultured motoneurons in a mouse model of ALS

    PubMed Central

    Schuster, J. E.; Fu, R.; Siddique, T.

    2012-01-01

    Riluzole is the only FDA-approved drug to treat amyotrophic lateral sclerosis, but its long-term effects on motoneurons are unknown. Therefore, we treated primary mouse spinal cord cultures with 2 μM riluzole for 4–9 days and then used whole cell patch clamp to record the passive and active properties of both wild-type and SOD1G93A motoneurons. At this concentration, riluzole blocks >50% of the sodium component of a persistent inward current that plays a major role in determining motoneuron excitability. Prolonged riluzole treatment significantly decreased the amplitude of the persistent inward current. This effect was specific for SOD1G93A motoneurons, where the amplitude decreased by 55.4%. In addition, prolonged treatment hyperpolarized the resting membrane potential as well as the voltage onset and voltage maximum of the persistent inward current (∼2–3 mV in each case). These effects appeared to offset one another and resulted in no change in the firing properties. In a subset of cells, acute reapplication of 2 μM riluzole during the recording decreased repetitive firing and the persistent inward current, which is consistent with the normal effects of riluzole. The downregulation of the persistent inward current in response to prolonged riluzole administration is in contrast to the strong upregulation of this same current after descending neuromodulatory drive to the cord is lost following spinal injury. This dichotomy suggests that decreased activation of G protein-coupled pathways can induce upregulation in the persistent inward current but that direct channel block is ineffective. PMID:22013234

  8. Functional Design in Rehabilitation: Modular Mechanisms for Ankle Complex

    PubMed Central

    2016-01-01

    This paper is aimed at presenting an innovative ankle rehabilitation device based on a parallel mechanism. A functional analysis and design are described to obtain a device able to guarantee ankle movement while patient's body remains stationary. Human ankle is a challenging context where a series of joints are highly integrated. The proposed rehabilitation device permits a patient with walking defects to improve his or her gait. The research focuses on plantar-flexion-dorsiflexion movement. The robust design starts from an accurate modelling of ankle movements during walking, assessing motion data from healthy individuals and patients. The kinematics analysis and functional evaluations lead the study and development of the articulated system. In particular, results of simulations support the effectiveness of the current design. A 3D prototype is presented highlighting that the ankle motion is successfully demonstrated. PMID:27524881

  9. Finite element analysis of a composite artificial ankle

    NASA Technical Reports Server (NTRS)

    Perkins, Leigh Ann; Johnston, Lawrence; Denniston, Charles; Czekalski, Blaise E.

    1993-01-01

    Ultra-light carbon fiber composite materials are being utilized in artificial limbs with increasing frequency in recent years. Dr. Arthur Copes, an orthotist from Baton Rouge, Louisiana, has developed a graphite expoxy composite material artificial ankle (Copes/Bionic Ankle) that is intended to be used by amputees who require the most advanced above-and-below-the-knee prosthetic devices. The Copes/Bionic Ankle is designed to reproduce the function of the natural ankle joint by allowing the composite material to act as a spring mechanism without the use of metal mechanical parts. NASA Marshall Space Flight Center has agreed to participate in the design effort by providing the structural analysis of the artificial ankle design.

  10. Total ankle replacement – surgical treatment and rehabilitation

    PubMed Central

    Krogulec, Zbigniew; Turski, Piotr; Przepiórski, Emil; Małdyk, Paweł; Księżopolska-Orłowska, Krystyna

    2015-01-01

    Functions of the ankle joint are closely connected with the gait and ability to maintain an upright position. Degenerative lesions of the joint directly contribute to postural disorders and greatly restrict propulsion of the foot, thus leading to abnormal gait. Development of total ankle replacement is connected with the use of the method as an efficient treatment of joint injuries and continuation of achievements in hip and knee surgery. The total ankle replacement technique was introduced as an alternative to arthrodesis, i.e. surgical fixation, which made it possible to preserve joint mobility and to improve gait. Total ankle replacement is indicated in post-traumatic degenerative joint disease and joint destruction secondary to rheumatoid arthritis. In this paper, total ankle replacement and various types of currently used endoprostheses are discussed. The authors also describe principles of early postoperative rehabilitation as well as rehabilitation in the outpatient setting. PMID:27407223

  11. Corticospinal Inputs to Primate Motoneurons Innervating the Forelimb from Two Divisions of Primary Motor Cortex and Area 3a

    PubMed Central

    Witham, Claire L.; Fisher, Karen M.; Edgley, Steve A.

    2016-01-01

    Previous anatomical work in primates has suggested that only corticospinal axons originating in caudal primary motor cortex (“new M1”) and area 3a make monosynaptic cortico-motoneuronal connections with limb motoneurons. By contrast, the more rostral “old M1” is proposed to control motoneurons disynaptically via spinal interneurons. In six macaque monkeys, we examined the effects from focal stimulation within old and new M1 and area 3a on 135 antidromically identified motoneurons projecting to the upper limb. EPSPs with segmental latency shorter than 1.2 ms were classified as definitively monosynaptic; these were seen only after stimulation within new M1 or at the new M1/3a border (incidence 6.6% and 1.3%, respectively; total n = 27). However, most responses had longer latencies. Using measures of the response facilitation after a second stimulus compared with the first, and the reduction in response latency after a third stimulus compared with the first, we classified these late responses as likely mediated by either long-latency monosynaptic (n = 108) or non-monosynaptic linkages (n = 108). Both old and new M1 generated putative long-latency monosynaptic and non-monosynaptic effects; the majority of responses from area 3a were non-monosynaptic. Both types of responses from new M1 had significantly greater amplitude than those from old M1. We suggest that slowly conducting corticospinal fibers from old M1 generate weak late monosynaptic effects in motoneurons. These may represent a stage in control of primate motoneurons by the cortex intermediate between disynaptic output via an interposed interneuron seen in nonprimates and the fast direct monosynaptic connections present in new M1. SIGNIFICANCE STATEMENT The corticospinal tract in Old World primates makes monosynaptic connections to motoneurons; previous anatomical work suggests that these connections come only from corticospinal tract (CST) neurons in the subdivision of primary motor cortex within the

  12. Comparison of cell body size and oxidative enzyme activity in motoneurons between the cervical and lumbar segments in the rat spinal cord after spaceflight and recovery.

    PubMed

    Ishihara, A; Yamashiro, J; Matsumoto, A; Higashibata, A; Ishioka, N; Shimazu, T; Ohira, Y

    2006-03-01

    The cell body sizes and succinate dehydrogenase (SDH) activities of motoneurons in the dorsolateral region of the ventral horn at the cervical and lumbar segments in the rat spinal cord were determined following 9 days of spaceflight with or without 10 days of recovery on Earth. The motoneurons were divided into three types based on their cell body sizes; small-, medium-, and large-sized motoneurons. In control rats, there was no difference in the cell body size or SDH activity of small- and large-sized motoneurons between the cervical and lumbar segments. The SDH activity of medium-sized motoneurons in control rats was higher in the lumbar segment than in the cervical segment, while the cell body sizes of medium-sized motoneurons were identical. The SDH activity of medium-sized motoneurons in the lumbar segment decreased to a level similar to that in the cervical segment of control rats following spaceflight. In addition, the decreased SDH activity of medium-sized motoneurons persisted for at least 10 days of recovery on Earth. It is concluded that spaceflight selectively affects the SDH activity of medium-sized motoneurons in the lumbar segment of the spinal cord, which presumably innervate skeletal muscles having an antigravity function.

  13. Axon-somatic back-propagation in detailed models of spinal alpha motoneurons

    PubMed Central

    Balbi, Pietro; Martinoia, Sergio; Massobrio, Paolo

    2015-01-01

    Antidromic action potentials following distal stimulation of motor axons occasionally fail to invade the soma of alpha motoneurons in spinal cord, due to their passing through regions of high non-uniformity. Morphologically detailed conductance-based models of cat spinal alpha motoneurons have been developed, with the aim to reproduce and clarify some aspects of the electrophysiological behavior of the antidromic axon-somatic spike propagation. Fourteen 3D morphologically detailed somata and dendrites of cat spinal alpha motoneurons have been imported from an open-access web-based database of neuronal morphologies, NeuroMorpho.org, and instantiated in neurocomputational models. An axon hillock, an axonal initial segment and a myelinated axon are added to each model. By sweeping the diameter of the axonal initial segment (AIS) and the axon hillock, as well as the maximal conductances of sodium channels at the AIS and at the soma, the developed models are able to show the relationships between different geometric and electrophysiological configurations and the voltage attenuation of the antidromically traveling wave. In particular, a greater than usually admitted sodium conductance at AIS is necessary and sufficient to overcome the dramatic voltage attenuation occurring during antidromic spike propagation both at the myelinated axon-AIS and at the AIS-soma transitions. PMID:25729362

  14. Supraspinal control of a short-latency cutaneous pathway to hindlimb motoneurons.

    PubMed

    Fleshman, J W; Rudomin, P; Burke, R E

    1988-01-01

    The effects of two supraspinal systems on transmission through a short latency hindlimb cutaneous reflex pathway were studied in cats anesthetized with pentobarbital or alpha-chloralose. Fleshman et al. (1984) described a mixed excitatory-inhibitory input from low threshold superficial peroneal (SP) afferents to flexor digitorum longus (FDL) motoneurons with central latencies so short as to suggest a disynaptic component in the initial excitatory phase of the PSP. In the present study, conditioning stimulation of either the red nucleus (RN) or the pyramidal tract (PT) caused a marked decrease in latency and increase in amplitude of both the excitatory and inhibitory components of the SP PSP in FDL motoneurons and several other motoneuron species. The minimal central latencies of the conditioned initial excitatory phase of the PSPs were on the order of 1.5 ms, consistent with the possibility of a disynaptic linkage. The facilitatory effects of RN and PT conditioning were observed in both anesthetic conditions, although preparation-specific differences in latency were observed. Lesion experiments suggested that the interneurons involved in this pathway are located caudal to the L5 segment, most likely in segments L6 and L7.

  15. The projection of jaw elevator muscle spindle afferents to fifth nerve motoneurones in the cat.

    PubMed Central

    Appenteng, K; O'Donovan, M J; Somjen, G; Stephens, J A; Taylor, A

    1978-01-01

    1. By spike-triggered averaging of intracellular synaptic noise it has been shown in pentobarbitone anaesthetized cats that jaw elevator muscle spindle afferents with their cell bodies in the mid-brain have a relatively weak monosynaptic projection to masseter and temporalis motoneurones. 2. Extending the spike-triggered averaging method to recording extracellular excitatory field potentials it has been shown that virtually all the spindles do project monosynaptically to the motoneurone pool. It is concluded that the general weakness of the projection is due to its restriction to a small proportion of the motoneurones, possibly those concerned most with tonic postural functions. 3. The shape of individual intracellular e.p.s.p.s together with the spatial distribution of extracellular excitatory potential fields provide some evidence for a dentrically weighted distribution of the synapses. 4. Evidence is presented that both primary- and secondary-type spindle afferents project monosynaptically, the secondary effects being some 71% of the strength of the primary ones. PMID:149860

  16. Glutamatergic motoneurons in the stomatogastric ganglion of the mantis shrimp Squilla oratoria.

    PubMed

    Chiba, C; Tazaki, K

    1992-07-01

    1. Transmitters of motoneurons in the stomatogastric ganglion (STG) of Squilla were identified by analyzing the excitatory neuromuscular properties of muscles in the posterior cardiac plate (pcp) and pyloric regions. 2. Bath and iontophoretic applications of glutamate produce depolarizations in these muscles. The pharmacological experiments and desensitization of the junctional receptors elucidate the glutamatergic nature of the excitatory junctional potentials (EJPs) evoked in the constrictor and dilator muscles. The reversal potentials for the excitatory junctional current (EJC) and for the glutamate-induced current are almost the same. 3. Some types of dilator muscle show sensitivity to both glutamate and acetylcholine (ACh) exogenously applied. The pharmacological evidence and desensitization of the junctional receptors indicate the glutamatergic nature of neuromuscular junctions in these dually sensitive muscles. The reversal potentials for the EJC and for the ACh-induced current are not identical. 4. Glutamate is a candidate as an excitatory neuro-transmitter at the neuromuscular junctions which the STG motoneurons named PCP, PY, PD, LA and VC make with the identified muscles. Kainic and quisqualic acids which act on glutamate receptors are potent excitants of these muscles. Extrajunctional receptors to ACh are present in two types of the muscle innervated by LA and VC. 5. Neurotransmitters used by the STG motoneurons of stomatopods are compared to those of decapods.

  17. The projection of jaw elevator muscle spindle afferents to fifth nerve motoneurones in the cat.

    PubMed

    Appenteng, K; O'Donovan, M J; Somjen, G; Stephens, J A; Taylor, A

    1978-06-01

    1. By spike-triggered averaging of intracellular synaptic noise it has been shown in pentobarbitone anaesthetized cats that jaw elevator muscle spindle afferents with their cell bodies in the mid-brain have a relatively weak monosynaptic projection to masseter and temporalis motoneurones. 2. Extending the spike-triggered averaging method to recording extracellular excitatory field potentials it has been shown that virtually all the spindles do project monosynaptically to the motoneurone pool. It is concluded that the general weakness of the projection is due to its restriction to a small proportion of the motoneurones, possibly those concerned most with tonic postural functions. 3. The shape of individual intracellular e.p.s.p.s together with the spatial distribution of extracellular excitatory potential fields provide some evidence for a dentrically weighted distribution of the synapses. 4. Evidence is presented that both primary- and secondary-type spindle afferents project monosynaptically, the secondary effects being some 71% of the strength of the primary ones.

  18. Preoperative gait characterization of patients with ankle arthrosis.

    PubMed

    Khazzam, Michael; Long, Jason T; Marks, Richard M; Harris, Gerald F

    2006-08-01

    The purpose of this study was to evaluate the kinematic changes that occur about the foot and ankle during gait in patients with degenerative joint disease (DJD). By comparing a normal adult population with what was found in the DJD population we determined how the motion of theses groups differed, thereby characterizing how this pathology affects foot and ankle motion. A 15-camera Vicon Motion Analysis System was used in conjunction with weight bearing radiographs to obtain three-dimensional motion of the foot and ankle during ambulation. The study was comprised of 34 patients and 35 ankles diagnosed with DJD (19 men and 15 women) of the ankle and 25 patients with normal ankles (13 men and 12 women). Dynamic foot and ankle motion was analyzed using the four-segment Milwaukee Foot Model (MFM). The data from this model resulted in three-dimensional (3D) kinematic parameters in the sagittal, coronal, and transverse planes as well as spatial-temporal parameters. Patient health status was evaluated using the SF-36 Health Survey and American Orthopaedics Foot and Ankle Society (AOFAS) hindfoot scores. The DJD group showed significant differences (p<0.001) as compared to normals with prolonged stance time, shortened stride length, reduced cadence and a walking speed which was only 66.96% of normal. Overall, kinematic data in the DJD cohort showed significant differences (p<0.001) in all planes of motion for tibial, hindfoot and forefoot motion as compared to normals. The average preoperative AOFAS hindfoot score was 26. DJD of the ankle results in decreased range of motion during gait. This decreased range of motion may be related to several factors including bony deformity, muscle weakness, and attempts to decrease the pain associated with weight bearing. To date there has not been a study which describes the effect of this disease process on motion of the foot and ankle. These findings may prove to be useful in the pre-operative assessment of these patients.

  19. Imaging appearances of lateral ankle ligament reconstruction.

    PubMed

    Chien, Alexander J; Jacobson, Jon A; Jamadar, David A; Brigido, Monica Kalume; Femino, John E; Hayes, Curtis W

    2004-01-01

    Six patients were retrospectively identified as having undergone lateral ligament reconstruction surgery. The surgical procedures were categorized into four groups: direct lateral ligament repair, peroneus brevis tendon rerouting, peroneus brevis tendon loop, and peroneus brevis tendon split and rerouting. At radiography and magnetic resonance (MR) imaging, the presence of one or more suture anchors in the region of the anterior talofibular ligament indicates direct ligament repair, whereas a fibular tunnel indicates peroneus brevis tendon rerouting or loop. Both ultrasonography (US) and MR imaging demonstrate rerouted tendons as part of lateral ankle reconstruction; however, MR imaging can also depict the rerouted tendon within an osseous tunnel if present, especially if T1-weighted sequences are used. Artifact from suture material may obscure the tendon at MR imaging but not at US. With both modalities, the integrity of the rerouted peroneus brevis tendon is best evaluated by following the tendon proximally from its distal attachment site, which typically remains unchanged. The rerouted tendon or portion of the tendon can then be traced proximally to its reattachment site. Familiarity with the surgical procedures most commonly used for lateral ankle ligament reconstruction, and with the imaging features of these procedures, is essential for avoiding diagnostic pitfalls and ensuring accurate assessment of the ligament reconstruction.

  20. [Chronic instability in the ankle area].

    PubMed

    Dubrana, F; Poichotte, A; Toullec, E; Colin, D; Guillodo, Y; Moati, J-C; Brilhauht, J; Musset, T; Feron, F; Richou, J; Henri, M; Guillemot, E

    2006-06-01

    For ankle sprains, the initial radiological work-up must include weight-bearing AP and lateral stress views of the sprained and healthy ankle. Films are taken in auto-varus. Other explorations included arthroMRI, arthroscanner or MRI which can be indicated preoperatively to confirm suspected cartilage injury or an associated ligament tear. These techniques should be employed when pertinent information can be expected according to the clinical situation and the operator's experience. In the emergency setting, ultrasonography can provide a simple low-cost confirmation of joint hematoma which is more precise than x-rays with a positive predictive value of nearly 100%. The objective and subjective clinical outcome after surgical anatomic repair or ligamentoplasty are quite similar. The two principal differences relate to persistent subjective instability and post-operative surgical complications. Thus there are advantages and disadvantages for each option advantage for anatomical repair because of the low rate of surgical complications and advantage for ligament repairs which stabilize the subtalar joint with a low rate of residual instability.

  1. The foot and ankle of Australopithecus sediba.

    PubMed

    Zipfel, Bernhard; DeSilva, Jeremy M; Kidd, Robert S; Carlson, Kristian J; Churchill, Steven E; Berger, Lee R

    2011-09-09

    A well-preserved and articulated partial foot and ankle of Australopithecus sediba, including an associated complete adult distal tibia, talus, and calcaneus, have been discovered at the Malapa site, South Africa, and reported in direct association with the female paratype Malapa Hominin 2. These fossils reveal a mosaic of primitive and derived features that are distinct from those seen in other hominins. The ankle (talocrural) joint is mostly humanlike in form and inferred function, and there is some evidence for a humanlike arch and Achilles tendon. However, Au. sediba is apelike in possessing a more gracile calcaneal body and a more robust medial malleolus than expected. These observations suggest, if present models of foot function are correct, that Au. sediba may have practiced a unique form of bipedalism and some degree of arboreality. Given the combination of features in the Au. sediba foot, as well as comparisons between Au. sediba and older hominins, homoplasy is implied in the acquisition of bipedal adaptations in the hominin foot.

  2. Biomechanics of the Ankle-Foot System during Stair Ambulation: Implications for Design of Advanced Ankle-Foot Prostheses

    DTIC Science & Technology

    2011-12-15

    A.H., 2007. Effect of ankle–foot orthosis on roll-over shape in adults with hemiplegia. Journal of Rehabilitation Research and Development 44 (1), 11...20. Gates, D.H., 2004. Characterizing Ankle Function During Stair Ascent, Descent, And Level Walking For Ankle Prosthesis And Orthosis Design. M.S

  3. Chloride-sensitive MEQ fluorescence in chick embryo motoneurons following manipulations of chloride and during spontaneous network activity.

    PubMed

    Chub, Nikolai; Mentis, George Z; O'donovan, Michael J

    2006-01-01

    Intracellular Cl(-) ([Cl(-)](in)) homeostasis is thought to be an important regulator of spontaneous activity in the spinal cord of the chick embryo. We investigated this idea by visualizing the variations of [Cl(-)](in) in motoneurons retrogradely labeled with the Cl-sensitive dye 6-methoxy-N-ethylquinolinium iodide (MEQ) applied to cut muscle nerves in the isolated E10-E12 spinal cord. This labeling procedure obviated the need for synthesizing the reduced, cell-permeable dihydro-MEQ (DiH-MEQ). The specificity of motoneuron labeling was confirmed using retrograde co-labeling with Texas Red Dextran and immunocytochemistry for choline acetyltransferase (ChAT). In MEQ-labeled motoneurons, the GABA(A) receptor agonist isoguvacine (100 muM) increased somatic and dendritic fluorescence by 7.4 and 16.7%, respectively. The time course of this fluorescence change mirrored that of the depolarization recorded from the axons of the labeled motoneurons. Blockade of the inward Na(+)/K(-)/2Cl(-) co-transporter (NKCC1) with bumetanide (20 microM) or with a low-Na(+) bath solution (12 mM), increased MEQ fluorescence by 5.3 and 11.4%, respectively, consistent with a decrease of [Cl(-)](in). After spontaneous episodes of activity, MEQ fluorescence increased and then declined to the pre-episode level during the interepisode interval. The largest fluorescence changes occurred over motoneuron dendrites (19.7%) with significantly smaller changes (5.2%) over somata. Collectively, these results show that retrogradely loaded MEQ can be used to detect [Cl(-)](in) in motoneurons, that the bumetanide-sensitive NKCC1 co-transporter is at least partially responsible for the elevated [Cl(-)](in) of developing motoneurons, and that dendritic [Cl(-)](in) decreases during spontaneous episodes and recovers during the inter-episode interval, presumably due to the action of NKCC1.

  4. Organization of the sural cutaneous input regulating the discharge of triceps surae gamma-motoneurones in the cat.

    PubMed

    Ellaway, P H; Davey, N J; Ljubisavljevic, M

    1997-01-01

    The organization of the cutaneous afferent influence on the discharge of gamma-motoneurones has been investigated in the decerebrated, spinal cat. gamma-Motoneurone discharges were recorded from cut nerve filaments. Time and frequency domain analyses were used to reveal the strength of coupling between gamma-motoneurone discharge and cutaneous afferents excited by natural skin stimulation. Time domain analysis (cross-correlation) was also used to reveal the sigh (facilitation or inhibition) and time course of the cutaneous influence on individual gamma-motoneurones. Mechanical stimulation of discrete areas of skin within the sural nerve field caused facilitation or inhibition of individual gamma-motoneurones supplying the gastrocnemius and soleus muscles. In a few cases, a gamma-motoneurone facilitated by stimulation at one site could be inhibited from another location. The effect of cutaneous afferent stimulation was not evident in the decerebrated cat with intact spinal cord. The intensity of facilitation and inhibition was mapped for the sural nerve field. Facilitation had focus of highest intensity to stimulation applied between the calcaneum and lateral malleolus. The focus for inhibition was either the same as for facilitation or, more frequently, tended to be lateral and dorsal to the calcaneum at the edge of the sural field. Cutaneous stimulation at the edge of the sural field could also reduce the coherence between the discharges of gamma-motoneurones, particularly at low frequencies of association (1-5 Hz), indicating disfacilitation of other sources of afferent input. The results reveal a detailed pattern of cutaneous inputs to the fusimotor system that could participate in a wide range of behavioural adjustments to stretch or contact of the skin at the heel.

  5. Ammodytoxins efficiently release arachidonic acid and induce apoptosis in a motoneuronal cell line in an enzymatic activity-dependent manner.

    PubMed

    Jenko-Pražnikar, Zala; Petan, Toni; Pungerčar, Jože

    2013-03-01

    Secreted phospholipases A2 (sPLA2s) are phospholipolytic enzymes and receptor ligands whose action affects cell death and survival. We have previously shown that ammodytoxin A (AtxA), a snake venom sPLA2, is rapidly internalized into motoneuronal NSC34 cells, inducing characteristic neurotoxic sPLA2 cell damage and apoptosis. In this study, we have analyzed the role of sPLA2 enzymatic activity, including arachidonic acid (AA) release, in the induction of motoneuronal apoptosis by AtxA and homologous recombinant sPLA2s with different enzymatic properties: an AtxA mutant (V31W) with very high enzymatic activity, enzymatically inactive S49-sPLA2 (ammodytin L, AtnL), its mutant (LW) with restored enzymatic activity, and non-toxic, enzymatically active sPLA2 (AtnI2). Addition of AA, AtxA, AtxA-V31W and AtnL-LW, but not AtnL and AtnI2, to NSC34 cells resulted in caspase-3 activation, DNA fragmentation and disruption of mitochondrial membrane potential, leading to a significant and rapid decrease in motoneuronal cell viability that was not observed in C2C12 myoblasts and HEK293 cells. AtxA, AtxA-V31W and AtnL-LW, but not AtnL and AtnI2, also liberated large amounts of AA specifically from motoneuronal cells, and this ability correlated well with the ability to induce apoptotic changes and decrease cell viability. The enzymatic activity of AtxA and similar sPLA2s is thus necessary, but not sufficient, for inducing motoneuronal apoptosis. This suggests that specific binding to the motoneuronal cell surface, followed by internalization and enzymatic activity-dependent induction of apoptosis, possibly as a consequence of extensive extra- and intracellular AA release, is necessary for Atx-induced motoneuronal cell death.

  6. Static γ-motoneurones couple group Ia and II afferents of single muscle spindles in anaesthetised and decerebrate cats

    PubMed Central

    Gladden, M H; Matsuzaki, H

    2002-01-01

    Ideas about the functions of static γ-motoneurones are based on the responses of primary and secondary endings to electrical stimulation of single static γ-axons, usually at high frequencies. We compared these effects with the actions of spontaneously active γ-motoneurones. In anaesthetised cats, afferents and efferents were recorded in intramuscular nerve branches to single muscle spindles. The occurrence of γ-spikes, identified by a spike shape recognition system, was linked to video-taped contractions of type-identified intrafusal fibres in the dissected muscle spindles. When some static γ-motoneurones were active at low frequency (< 15 Hz) they coupled the firing of group Ia and II afferents. Activity of other static γ-motoneurones which tensed the intrafusal fibres appeared to enhance this effect. Under these conditions the secondary ending responded at shorter latency than the primary ending. In another series of experiments on decerebrate cats, responses of primary and secondary endings of single muscle spindles to activation of γ-motoneurones by natural stimuli were compared with their responses to electrical stimulation of single γ-axons supplying the same spindle. Electrical stimulation mimicked the natural actions of γ-motoneurones on either the primary or the secondary ending, but not on both together. However, γ-activity evoked by natural stimuli coupled the firing of afferents with the muscle at constant length, and also when it was stretched. Analysis showed that the timing and tightness of this coupling determined the degree of summation of excitatory postsynaptic potentials (EPSPs) evoked by each afferent in α-motoneurones and interneurones contacted by terminals of both endings, and thus the degree of facilitation of reflex actions of group II afferents. PMID:12181298

  7. A modelling study of locomotion-induced hyperpolarization of voltage threshold in cat lumbar motoneurones

    PubMed Central

    Dai, Yue; Jones, Kelvin E; Fedirchuk, Brent; McCrea, David A; Jordan, Larry M

    2002-01-01

    During fictive locomotion the excitability of adult cat lumbar motoneurones is increased by a reduction (a mean hyperpolarization of ≈6.0 mV) of voltage threshold (Vth) for action potential (AP) initiation that is accompanied by only small changes in AP height and width. Further examination of the experimental data in the present study confirms that Vth lowering is present to a similar degree in both the hyperpolarized and depolarized portions of the locomotor step cycle. This indicates that Vth reduction is a modulation of motoneurone membrane currents throughout the locomotor state rather than being related to the phasic synaptic input within the locomotor cycle. Potential ionic mechanisms of this locomotor-state-dependent increase in excitability were examined using three five-compartment models of the motoneurone innervating slow, fast fatigue resistant and fast fatigable muscle fibres. Passive and active membrane conductances were set to produce input resistance, rheobase, afterhyperpolarization (AHP) and membrane time constant values similar to those measured in adult cat motoneurones in non-locomoting conditions. The parameters of 10 membrane conductances were then individually altered in an attempt to replicate the hyperpolarization of Vth that occurs in decerebrate cats during fictive locomotion. The goal was to find conductance changes that could produce a greater than 3 mV hyperpolarization of Vth with only small changes in AP height (< 3 mV) and width (< 1.2 ms). Vth reduction without large changes in AP shape could be produced either by increasing fast sodium current or by reducing delayed rectifier potassium current. The most effective Vth reductions were achieved by either increasing the conductance of fast sodium channels or by hyperpolarizing the voltage dependency of their activation. These changes were particularly effective when localized to the initial segment. Reducing the conductance of delayed rectifier channels or depolarizing their

  8. Improved lentiviral transduction of ALS motoneurons in vivo via dual targeting.

    PubMed

    O'Leary, Valerie B; Ovsepian, Saak V; Bodeker, Macdara; Dolly, J Oliver

    2013-11-04

    Treatment of amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disease, is hampered by its complex etiology and lack of efficient means for targeted transfer of therapeutics into motoneurons. The objective of this research was engineering of a versatile motoneuron targeting adapter--a full-length atoxic tetanus toxin fused to core-streptavidin (CS-TeTIM)--for retro-axonal transduction of viral vectors; validation of the targeting efficiency of CS-TeTIM in vivo, by expression of green fluorescence protein (GFP) reporter in motoneurons of presymptomatic and symptomatic ALS-like SOD1(G93A) mice, and comparison with age-matched controls; and appraisal of lentiviral transduction with CS-TeTIM relative to (1) a HC binding fragment of tetanus toxin CS-TeTx(HC), (2) rabies glycoprotein (RG), and (3) a CS-TeTIM-RG dual targeting approach. CS-TeTIM and CS-TeTx(HC) were engineered using recombinant technology and site-directed mutagenesis. Biotinylated vectors, pseudotyped with vesicular stomatitis virus glycoprotein (VSV-G) or RG, were linked to these adaptors and injected intraperitoneally (ip) into presymptomatic (12 weeks old), symptomatic SOD1(G93A) (22 weeks old) or wild type control mice, followed by monitoring of GFP expression in the spinal cord and supraspinal motor structures with quantitative PCR and immuno-histochemistry. Transcripts were detected in the spinal cord and supraspinal motor structures of all mice 2 weeks after receiving a single ip injection, although in symptomatic SOD1(G93A) animals reporter RNA levels were lower compared to presymptomatic and wild-type controls irrespective of the targeting approach. GFP transduction with CS-TeTIM proved more efficient than CS-TeTx(HC) across all groups while CS-TeTIM-RG dual-targeted vectors yielded the highest transcript numbers. Importantly, in both wild-type and presymptomatic SOD1(G93A) mice strong colabeling of choline-acetyltransferase (ChAT) and GFP was visualized in neurons of the

  9. Control by Preynaptic Correlation: a mechanism affecting information transmission from Ia fibers to motoneurons.

    PubMed

    Rudomin, P; Burke, R E; Núñez, R; Madrid, J; Dutton, H

    1975-03-01

    1. In the unanesthetized spinal cord of the cat, simultaneous intracellular recordings were made from two motoneurons belonging to the gastronemius motor nucleus. 2. Supramaximal iterative stimulation of small branches of the gastrocnemius nerve produced monosynaptic EPSPs (Ia EPSPs) of varying amplitude superimposed on a fluctuating base line. 3. In most cases the variance of the motoneuron membrane potential was increased above base-line levels with a time course approximately matching the Ia EPSP. This suggests that Ia EPSP fluctuations are greater than can be accounted for by the base-line fluctuations alone. 4. For a given series of Ia EPSPs, the smaller responses in the series had about the same decay phase as the larger EPSPs, suggesting that most of the Ia EPSP fluctuations were not due to systematic changes in postsynaptic conductances produced by ongoing activity, but rather to a presynaptic mechanism. 5. Simultaneous recording from two motoneurons showed that base-line fluctuations were positively correlated. In most cases, however, there was an additional increased correlation above base-line levels resembling the time course of the Ia EPSPs, indicating positive correlation between EPSP fluctuations which is attributed to a presynaptic mechanism. 6. Conditioning volleys to group I muscle afferents or to low-threshold cutaneous afferents reduced the variance of the Ia EPSPs and also their correlation in motoneuron pairs, often without changing the mean Ia EPSPs. 7. It is concluded that, in the unanesthetized spinal cord, in addition to the random process which governs transmitter release intrinsic to a given synaptic terminal, there is another stochastic process affecting, in a correlated manner, transmitter release in large sets of Ia synaptic terminals. Most likely, the correlation in transmitter release is achieved by membrane potential fluctuations imposed on the Ia terminal arborizations by ongoing activity of the segmental mechanism mediating

  10. Mechanism and function of mixed-mode oscillations in vibrissa motoneurons.

    PubMed

    Golomb, David

    2014-01-01

    Vibrissa motoneurons in the facial nucleus innervate the intrinsic and extrinsic muscles that move the whiskers. Their intrinsic properties affect the way they process fast synaptic input from the vIRT and Bötzinger nuclei together with serotonergic neuromodulation. In response to constant current (I(app)) injection, vibrissa motoneurons may respond with mixed mode oscillations (MMOs), in which sub-threshold oscillations (STOs) are intermittently mixed with spikes. This study investigates the mechanisms involved in generating MMOs in vibrissa motoneurons and their function in motor control. It presents a conductance-based model that includes the M-type K+ conductance, g(M), the persistent Na+ conductance, g(NaP), and the cationic h conductance, g(h). For g(h) = 0 and moderate values of g(M) and g(NaP), the model neuron generates STOs, but not MMOs, in response to I(app) injection. STOs transform abruptly to tonic spiking as the current increases. In addition to STOs, MMOs are generated for g(h)>0 for larger values of I(app); the I(app) range in which MMOs appear increases linearly with g(h). In the MMOs regime, the firing rate increases with I(app) like a Devil's staircase. Stochastic noise disrupts the temporal structure of the MMOs, but for a moderate noise level, the coefficient of variation (CV) is much less than one and varies non-monotonically with I(app). Furthermore, the estimated time period between voltage peaks, based on Bernoulli process statistics, is much higher in the MMOs regime than in the tonic regime. These two phenomena do not appear when moderate noise generates MMOs without an intrinsic MMO mechanism. Therefore, and since STOs do not appear in spinal motoneurons, the analysis can be used to differentiate different MMOs mechanisms. MMO firing activity in vibrissa motoneurons suggests a scenario in which moderate periodic inputs from the vIRT and Bötzinger nuclei control whisking frequency, whereas serotonergic neuromodulation controls

  11. The pattern of excitation of human lower limb motoneurones by probable group II muscle afferents

    PubMed Central

    Simonetta-Moreau, M; Marque, P; Marchand-Pauvert, V; Pierrot-Deseilligny, E

    1999-01-01

    Heteronymous group II effects were investigated in the human lower limb. Changes in firing probability of single motor units in quadriceps (Q), biceps (Bi), semitendinosus (ST), gastrocnemius medialis (GM) and tibialis anterior (TA) were studied after electrical stimuli between 1 and 3 times motor threshold (MT) applied to common peroneal (CP), superficial (SP) and deep (DP) peroneal, Bi and GM nerves in those nerve-muscle combinations without recurrent inhibition. Stimulation of the CP and Bi nerves evoked in almost all of the explored Q motor units a biphasic excitation with a low-threshold early peak, attributable to non-monosynaptic group I excitation, and a higher threshold late peak. When the CP nerve was cooled (or the stimulation applied to a distal branch, DP), the increase in latency was greater for the late than for the early peak, indicating that the late excitation is due to stimulation of afferents with a slower conduction velocity than group I fibres, presumably in the group II range. In ST motor units the group II excitation elicited by stimulation of the GM and SP nerves was particularly large and frequent, and the non-monosynaptic group I excitation was often replaced by an inhibition. A late group II-induced excitation from CP to Q motoneurones and from GM and SP to ST motoneurones was also observed when using the H reflex as a test. The electrical threshold and conduction velocity of the largest diameter fibres evoking the group II excitation were estimated to be 2·1 and 0·65 times those of the fastest Ia afferents, respectively. In the combinations tested in the present investigation the group II input seemed to be primarily of muscle origin. The potent heteronymous group II excitation of motoneurones of both flexors and extensors of the knee contrasted with the absence of a group II effect from DP to GM and from GM to TA. In none of the combinations explored was there any evidence for group II inhibition of motoneurones. The possible

  12. The electrical geometry, electrical properties and synaptic connections onto rat V motoneurones in vitro.

    PubMed Central

    Curtis, J C; Appenteng, K

    1993-01-01

    1. We have developed a tissue slice preparation which allows the study of the actions of single presynaptic neurones onto single trigeminal motoneurones in the immature rat. Our aim in this first stage of the work has been to assess the validity of this preparation as a model for responses obtained in vivo from trigeminal motoneurones in adult rats. We have quantified the integrative properties of the motoneurones and also the variability in transmission at synapses of single presynaptic neurones onto the motoneurones. This data has then been compared to similar published data obtained from adult (rat) trigeminal motoneurones in vivo. 2. Quantitative reconstructions were made of the morphology of three motoneurones which had been labelled with biocytin by intracellular injection. The neurones gave off six to nine dendrites, of mean length 522 microns (S.D. = 160; n = 22), which branched on average 10.5 times to produce 11.45 end-terminations per dendrite (S.D. = 8.57; n = 22). The mean surface area of the dendrites was 0.92 x 10(4) microns2 (S.D. = 0.67; n = 22), and, for individual cells, the ratio of the combined dendritic surface area to the total neuronal surface area ranged from 98.3 to 99.2% (n = 3). At dendritic branch points the ratio of the summed diameters of the daughter dendrites to the 3/2 power against the parent dendrite to the 3/2 power was 1.09 (S.D. = 0.21; n = 217), allowing branch points to be collapsed into a single cylinder. The equivalent cylinder diameter of the combined dendritic tree remained approximately constant over the proximal 25-40% of the equivalent electrical length of the dendritic tree and then showed tapering. The tapering could be ascribed to termination of dendrites at different electrical distances from the soma. 3. Electrical properties were determined for a total of eighty-seven motoneurones, all with membrane potentials more negative than 60 mV (mean = 66.0 mV; S.D. = 5.2) and spikes which overshot zero (mean spike

  13. Foot and ankle injuries in dance.

    PubMed

    Macintyre, J; Joy, E

    2000-04-01

    Acute traumatic injuries are common in ballet dancers. A careful history, thorough examination, and appropriate imaging should allow for the diagnosis of most problems. The clinician must have a high index of suspicion for occult bony injuries, especially if the patient fails to recover as expected. Aggressive treatment of the sprained ankle is essential to maintain foot and ankle mobility and prevent prolonged disability and subsequent overuse injuries. Kinetic chain dysfunctions are common in ballet dancers with overuse injuries and commonly follow ankle sprains. They may represent a secondary phenomenon that developed in response to the compensatory movement changes caused by the initial injury. It is important to remember, however, that these dysfunctions may have been long standing and a causative factor in the injury. Regardless of the time of onset of the dysfunction, residual kinetic chain dysfunction associated with incomplete rehabilitation of an injury may predispose the dancer to further injuries. Untreated dysfunctions at one site in the kinetic chain may predispose to compensatory dysfunction at other sites in the chain. Accordingly, it is essential to thoroughly examine the entire chain for functional movements when dealing with an injury, because identification and treatment of the kinetic chain dysfunction is important in the rehabilitation of the dancing athlete. Kinetic chain dysfunctions are common in injured ballet dancers and may be a cause of repeated injury. Why then are these dysfunctions left untreated? Medical personnel caring for dancers are sometimes guilty of tunnel vision, and focus solely on the injured site without considering what is happening at other sites in the kinetic chain. This oversight is compounded when the physicians or therapists are satisfied with discovering simply what injury has occurred rather than asking why the injury has occurred. The significance of kinetic chain dysfunctions is only just beginning to be

  14. Multivariable Dynamic Ankle Mechanical Impedance With Active Muscles

    PubMed Central

    Lee, Hyunglae; Krebs, Hermano Igo; Hogan, Neville

    2015-01-01

    Multivariable dynamic ankle mechanical impedance in two coupled degrees-of-freedom (DOFs) was quantified when muscles were active. Measurements were performed at five different target activation levels of tibialis anterior and soleus, from 10% to 30% of maximum voluntary contraction (MVC) with increments of 5% MVC. Interestingly, several ankle behaviors characterized in our previous study of the relaxed ankle were observed with muscles active: ankle mechanical impedance in joint coordinates showed responses largely consistent with a second-order system consisting of inertia, viscosity, and stiffness; stiffness was greater in the sagittal plane than in the frontal plane at all activation conditions for all subjects; and the coupling between dorsiflexion–plantarflexion and inversion–eversion was small—the two DOF measurements were well explained by a strictly diagonal impedance matrix. In general, ankle stiffness increased linearly with muscle activation in all directions in the 2-D space formed by the sagittal and frontal planes, but more in the sagittal than in the frontal plane, resulting in an accentuated “peanut shape.” This characterization of young healthy subjects’ ankle mechanical impedance with active muscles will serve as a baseline to investigate pathophysiological ankle behaviors of biomechanically and/or neurologically impaired patients. PMID:25203497

  15. Summary of Human Ankle Mechanical Impedance During Walking.

    PubMed

    Lee, Hyunglae; Rouse, Elliott J; Krebs, Hermano Igo

    2016-01-01

    The human ankle joint plays a critical role during walking and understanding the biomechanical factors that govern ankle behavior and provides fundamental insight into normal and pathologically altered gait. Previous researchers have comprehensively studied ankle joint kinetics and kinematics during many biomechanical tasks, including locomotion; however, only recently have researchers been able to quantify how the mechanical impedance of the ankle varies during walking. The mechanical impedance describes the dynamic relationship between the joint position and the joint torque during perturbation, and is often represented in terms of stiffness, damping, and inertia. The purpose of this short communication is to unify the results of the first two studies measuring ankle mechanical impedance in the sagittal plane during walking, where each study investigated differing regions of the gait cycle. Rouse et al. measured ankle impedance from late loading response to terminal stance, where Lee et al. quantified ankle impedance from pre-swing to early loading response. While stiffness component of impedance increases significantly as the stance phase of walking progressed, the change in damping during the gait cycle is much less than the changes observed in stiffness. In addition, both stiffness and damping remained low during the swing phase of walking. Future work will focus on quantifying impedance during the "push off" region of stance phase, as well as measurement of these properties in the coronal plane.

  16. Summary of Human Ankle Mechanical Impedance During Walking

    PubMed Central

    Rouse, Elliott J.; Krebs, Hermano Igo

    2016-01-01

    The human ankle joint plays a critical role during walking and understanding the biomechanical factors that govern ankle behavior and provides fundamental insight into normal and pathologically altered gait. Previous researchers have comprehensively studied ankle joint kinetics and kinematics during many biomechanical tasks, including locomotion; however, only recently have researchers been able to quantify how the mechanical impedance of the ankle varies during walking. The mechanical impedance describes the dynamic relationship between the joint position and the joint torque during perturbation, and is often represented in terms of stiffness, damping, and inertia. The purpose of this short communication is to unify the results of the first two studies measuring ankle mechanical impedance in the sagittal plane during walking, where each study investigated differing regions of the gait cycle. Rouse et al. measured ankle impedance from late loading response to terminal stance, where Lee et al. quantified ankle impedance from pre-swing to early loading response. While stiffness component of impedance increases significantly as the stance phase of walking progressed, the change in damping during the gait cycle is much less than the changes observed in stiffness. In addition, both stiffness and damping remained low during the swing phase of walking. Future work will focus on quantifying impedance during the “push off” region of stance phase, as well as measurement of these properties in the coronal plane. PMID:27766187

  17. Bone alterations are associated with ankle osteoarthritis joint pain

    PubMed Central

    Nakamura, Yukio; Uchiyama, Shigeharu; Kamimura, Mikio; Komatsu, Masatoshi; Ikegami, Shota; Kato, Hiroyuki

    2016-01-01

    The etiology of ankle osteoarthritis (OA) is largely unknown. We analyzed 24 ankle OA of 21 patients diagnosed by plain radiographs using magnetic resonance imaging (MRI). Ankle joint pain disappeared in 22 out of 24 joints by conservative treatment. MRI bone signal changes in and around the ankle joints were observed in 22 of 24 joints. Bone signal changes along the joint line were seen in 10 of 11 joints as a Kellgren-Lawrence (KL) grade of II to IV. Such signal changes were witnessed in only 4 of 13 joints with KL grade 0 or I. In the talocrural joint, bone alterations occurred in both tibia and talus bones through the joint line in cases of KL grade III or IV, while focal bone alterations were present in the talus only in KL grade I or II cases. Sixteen of 24 joints exhibited intraosseous bone signal changes, which tended to correspond to joint pain of any ankle OA stage. Our results suggest that bone alterations around the ankle joint might be one of the etiologies of OA and associated with ankle joint pain. PMID:26776564

  18. Registry data trends of total ankle replacement use.

    PubMed

    Roukis, Thomas S; Prissel, Mark A

    2013-01-01

    Joint arthroplasty registry data are meaningful when evaluating the outcomes of total joint replacement, because they provide unbiased objective information regarding survivorship and incidence of use. Critical evaluation of the registry data information will benefit the surgeon, patient, and industry. However, the implementation and acceptance of registry data for total ankle replacement has lagged behind that of hip and knee implant arthroplasty. Currently, several countries have national joint arthroplasty registries, with only some procuring information for total ankle replacement. We performed an electronic search to identify publications and worldwide registry databanks with pertinent information specific to total ankle replacement to determine the type of prostheses used and usage trends over time. We identified worldwide registry data from 33 countries, with details pertinent to total ankle replacement identified in only 6 countries. The obtained information was arbitrarily stratified into 3 distinct periods: 2000 to 2006, 2007 to 2010, and 2011. Within these study periods, the data from 13 total ankle replacement systems involving 3,980 ankles were identified. The vast majority (97%) of the reported ankle replacements were 3-component, mobile-bearing, uncemented prostheses. Three usage trends were identified: initial robust embracement followed by abrupt disuse, minimal use, and initial embracement followed by sustained growth in implantation. Before the widespread acceptance of new total ankle replacements, the United States should scrutinize and learn from the international registry data and develop its own national joint registry that would include total ankle replacement. Caution against the adoption of newly released prostheses, especially those without readily available revision components, is recommended.

  19. Motoneuronal pre-compensation for the low-pass filter characteristics of muscle. A quantitative appraisal in cat muscle units.

    PubMed

    Baldissera, F; Cavallari, P; Cerri, G

    1998-09-01

    1. The relevance of motoneurone dynamic sensitivity in compensating for the low-pass filter properties of muscle was assessed by stimulating cat muscle units (MUs) with impulse discharges generated by two current-to-rate converters: (i) a spinal motoneurone, sensitive to both the input intensity and its first derivative, and (ii) a linear current-to-rate converter, i.e. a neurone model with the same static sensitivity as the motoneurone but lacking dynamic sensitivity. 2. Discharges generated by injection of sine-wave currents in three motoneurones of the 'fast' type and in the three related model versions were applied to the axon of forty-six MUs. The MU isometric tension was modulated at the frequency of the current sine wave (0.5-20 Hz). Phase and gain of the current-to-force transduction were measured. 3. When MUs were driven by the model, the force lagged the current by 90 deg at 1 Hz in slow MUs and at around 5 Hz in fast MUs. Under motoneurone drive, the 90 deg phase lag was attained at frequencies about twice as high. 4. The gain of the transduction (peak-to-peak force modulation/peak-to-peak current modulation) decayed when the modulation frequency was increased. In all but five units, the cut-off frequency, Fco (gain attenuated by -3 dB), was higher when the unit was motoneurone driven (FcoCell) then when it was model driven (FcoMod). In both conditions, Fco was inversely correlated with the MU's time-to-peak. The advantage conferred by the motoneurone dynamic sensitivity was expressed by the Fco ratio (FcoCell/FcoMod). Across the MU population this ratio ranged from 0. 6-2.8, was inversely correlated with the time-to peak, and was directly correlated with the half-tension rate, i.e. the impulse rate at which MUs develop 50 % of their maximal tetanic force. The largest improvement (Fco ratio > 2.0) was found in units with mechanical features similar to those presumably coupled 'in vivo' to the motoneurones utilized for stimulation. 5. This estimate was

  20. FUS Mislocalization and Vulnerability to DNA Damage in ALS Patients Derived hiPSCs and Aging Motoneurons

    PubMed Central

    Higelin, Julia; Demestre, Maria; Putz, Stefan; Delling, Jan P.; Jacob, Christian; Lutz, Anne-Kathrin; Bausinger, Julia; Huber, Anne-Kathrin; Klingenstein, Moritz; Barbi, Gotthold; Speit, Günter; Huebers, Annemarie; Weishaupt, Jochen H.; Hermann, Andreas; Liebau, Stefan; Ludolph, Albert C.; Boeckers, Tobias M.

    2016-01-01

    Mutations within the FUS gene (Fused in Sarcoma) are known to cause Amyotrophic Lateral Sclerosis (ALS), a neurodegenerative disease affecting upper and lower motoneurons. The FUS gene codes for a multifunctional RNA/DNA-binding protein that is primarily localized in the nucleus and is involved in cellular processes such as splicing, translation, mRNA transport and DNA damage response. In this study, we analyzed pathophysiological alterations associated with ALS related FUS mutations (mFUS) in human induced pluripotent stem cells (hiPSCs) and hiPSC derived motoneurons. To that end, we compared cells carrying a mild or severe mFUS in physiological- and/or stress conditions as well as after induced DNA damage. Following hyperosmolar stress or irradiation, mFUS hiPS cells recruited significantly more cytoplasmatic FUS into stress granules accompanied by impaired DNA-damage repair. In motoneurons wild-type FUS was localized in the nucleus but also deposited as small punctae within neurites. In motoneurons expressing mFUS the protein was additionally detected in the cytoplasm and a significantly increased number of large, densely packed FUS positive stress granules were seen along neurites. The amount of FUS mislocalization correlated positively with both the onset of the human disease (the earlier the onset the higher the FUS mislocalization) and the maturation status of the motoneurons. Moreover, even in non-stressed post-mitotic mFUS motoneurons clear signs of DNA-damage could be detected. In summary, we found that the susceptibility to cell stress was higher in mFUS hiPSCs and hiPSC derived motoneurons than in controls and the degree of FUS mislocalization correlated well with the clinical severity of the underlying ALS related mFUS. The accumulation of DNA damage and the cellular response to DNA damage stressors was more pronounced in post-mitotic mFUS motoneurons than in dividing hiPSCs suggesting that mFUS motoneurons accumulate foci of DNA damage, which in turn

  1. Agility to INBONE: anterior and posterior approaches to the difficult revision total ankle replacement.

    PubMed

    DeVries, J George; Scott, Ryan T; Berlet, Gregory C; Hyer, Christopher F; Lee, Thomas H; DeOrio, James K

    2013-01-01

    Total ankle replacement is now acknowledged as a viable alternative to ankle arthrodesis for end-stage ankle arthritis. The authors present a series of 14 patients who were converted from the Agility total ankle replacement to an INBONE total ankle replacement. This report is unique in that anterior and posterior approaches are discussed and detailed. Although the authors present successful conversion of the Agility total ankle replacement to an INBONE total ankle replacement, the difficulty of this procedure is demonstrated by the high complication rate and 2 early failures.

  2. Static ankle impedance in stroke and multiple sclerosis: a feasibility study.

    PubMed

    Lee, Hyunglae; Patterson, Tara; Ahn, Jooeun; Klenk, Daniel; Lo, Albert; Krebs, Hermano Igo; Hogan, Neville

    2011-01-01

    Quantitative characterization of ankle mechanical impedance is critical for understanding lower extremity function in persons with neurological disorders. In this paper, we examine the feasibility of employing an ankle robot and multivariable analysis to determine static ankle impedance in 4 patients: 1 with multiple sclerosis and 3 with stroke. We employed a scalar based vector field approximation method which was successful in identifying young healthy subjects' ankle impedance. It enabled clear interpretation of spatial ankle impedance structure and intermuscular feedback at the ankle for both affected and unaffected legs. Measured impedance of two patients was comparable to healthy young subjects, while the other two patients had significantly different static ankle impedance properties.

  3. Outcome of unilateral ankle arthrodesis and total ankle replacement in terms of bilateral gait mechanics.

    PubMed

    Chopra, Swati; Rouhani, Hossein; Assal, Mathieu; Aminian, Kamiar; Crevoisier, Xavier

    2014-03-01

    Previous studies assessed the outcome of ankle arthrodesis (AA) and total ankle replacement (TAR) surgeries; however, the extent of postoperative recovery towards bilateral gait mechanics (BGM) is unknown. We evaluated the outcome of the two surgeries at least 2 years post rehabilitation, focusing on BGM. 36 participants, including 12 AA patients, 12 TAR patients, and 12 controls were included. Gait assessment over 50 m distance was performed utilizing pressure insoles and 3D inertial sensors, following which an intraindividual comparison was performed. Most spatiotemporal and kinematic parameters in the TAR group were indicative of good gait symmetry, while the AA group presented significant differences. Plantar pressure symmetry among the AA group was also significantly distorted. Abnormality in biomechanical behavior of the AA unoperated, contralateral foot was observed. In summary, our results indicate an altered BGM in AA patients, whereas a relatively fully recovered BGM is observed in TAR patients, despite the quantitative differences in several parameters when compared to a healthy population. Our study supports a biomechanical assessment and rehabilitation of both operated and unoperated sides after major surgeries for ankle osteoarthrosis.

  4. Use of a trabecular metal implant in ankle arthrodesis after failed total ankle replacement

    PubMed Central

    2010-01-01

    Background and purpose Arthrodesis after failed total ankle replacement is complicated and delayed union, nonunion, and shortening of the leg often occur—especially with large bone defects. We investigated the use of a trabecular metal implant and a retrograde intramedullary nail to obtain fusion. Patients and methods 13 patients with a migrated or loose total ankle implant underwent arthrodesis with the use of a retrograde intramedullary nail through a trabecular metal Tibial Cone. The mean follow-up time was 1.4 (0.6–3.4) years. Results At the last examination, 7 patients were pain-free, while 5 had some residual pain but were satisfied with the procedure. 1 patient was dissatisfied and experienced pain and swelling when walking. The implant-bone interfaces showed no radiographic zones or gaps in any patient, indicating union. Interpretation The method is a new way of simplifying and overcoming some of the problems of performing arthrodesis after failed total ankle replacement. PMID:21067435

  5. Dscam1 is required for normal dendrite growth and branching but not for dendritic spacing in Drosophila motoneurons.

    PubMed

    Hutchinson, Katie M; Vonhoff, Fernando; Duch, Carsten

    2014-01-29

    Down syndrome cell adhesion molecule, Dscam, serves diverse neurodevelopmental functions, including axon guidance and synaptic adhesion, as well as self-recognition and self-avoidance, depending on the neuron type, brain region, or species under investigation. In Drosophila, the extensive molecular diversity that results from alternative splicing of Dscam1 into >38,000 isoforms provides neurons with a unique molecular code for self-recognition in the nervous system. Each neuron produces only a small subset of Dscam1 isoforms, and distinct Dscam1 isoforms mediate homophilic interactions, which in turn, result in repulsion and even spacing of self-processes, while allowing contact with neighboring cells. While these mechanisms have been shown to underlie mushroom body development and spacing of mechanosensory neuron dendrites, here we report that Dscam1 plays no role in adult Drosophila motoneuron dendrite spacing, but is required for motoneuron dendritic growth. Targeted expression of Dscam-RNAi in an identified flight motoneuron did not impact dendrite spacing, but instead produced overgrowth. Increasing the knockdown strength severely reduced dendritic growth and branching. Similarly, Dscam mutant motoneurons in an otherwise control background (MARCM) were completely devoid of mature dendrites. These data suggest that Dscam1 is required cell autonomously for normal adult motoneuron dendrite growth in Drosophila. This demonstrates a previously unreported role of Drosophila Dscam1 in central neuron development, and expands the current understanding that Dscam1 operates as a cell adhesion molecule that mediates homophilic repulsion.

  6. A peri-motor framework reveals functional segmentation in the motoneuronal network controlling locomotion in Caenorhabditis elegans

    PubMed Central

    Haspel, Gal; O'Donovan, Michael J

    2011-01-01

    The neuronal connectivity dataset of the nematode Caenorhabditis elegans attracts wide attention from computational neuroscientists and experimentalists. However, the dataset is incomplete. The ventral and dorsal nerve cords of a single nematode were reconstructed halfway along the body and the posterior data is missing, leaving 21 of 75 motoneurons of the locomotor network with partial or no connectivity data. Using a new framework for network analysis, the peri-motor space, we identified rules of connectivity that allowed us to approximate the missing data by extrapolation. Motoneurons were mapped into peri-motor space in which each motoneuron is located according to the muscle cells it innervates. In this framework, a pattern of iterative connections emerges which includes most (0.90) of the connections. We identified a repeating unit consisting of 12 motoneurons and 12 muscle cells. The cell bodies of the motoneurons of such a unit are not necessarily anatomical neighbors and there is no obvious anatomical segmentation. A connectivity model, comprised of six repeating units, is a description of the network that is both simplified (modular and without non-iterative connections) and more complete (includes the posterior part) than the original dataset. The peri-motor framework of observed connectivity and the segmented connectivity model give insights and advance the study of the neuronal infrastructure underlying locomotion in C. elegans. Furthermore, we suggest that the tools used herein may be useful to interpret, simplify and represent connectivity data of other motor systems. PMID:21994377

  7. Supramalleolar osteotomy for ankle valgus in myelomeningocele.

    PubMed

    Abraham, E; Lubicky, J P; Songer, M N; Millar, E A

    1996-01-01

    Fifty-five supramalleolar osteotomies were performed in 35 patients for progressive hindfoot valgus in myelomeningocele. All patients were ambulatory. The most common motor level of innervation was L3 in 42 limbs. The average age at surgery was 12 years. The average follow-up was 8 years. Preoperatively, all patients experienced progressive difficulty with brace use, and anteroposterior weight-bearing ankle radiographs showed a valgus tilt of the talotibial angle (TTA) of > or = 10 degrees with an average of 18 degrees. The average postoperative correction of TTA was 17 degrees. The results were graded as follows: excellent, 42 limbs; good, eight limbs; fair, three limbs; and poor, two limbs. The fair and poor limb results were the result of loss of correction or nonunion. The best results were seen when the TTA was corrected to 5 degrees of varus.

  8. [Lateral ligament injuries of the ankle joint].

    PubMed

    Walther, M; Kriegelstein, S; Altenberger, S; Volkering, C; Röser, A; Wölfel, R

    2013-09-01

    Lateral ligament injuries are the most common sports injury and have a high incidence even in non-sportive activities. Although lateral ligament injuries are very common there is still a controversial debate on the best management. The diagnosis is based on clinical examination and X-ray images help to rule out fractures. Further imaging, especially magnetic resonance imaging (MRI) is used to diagnose associated injuries. According to the recommendations of the various scientific societies the primary therapy of lateral ligament injuries is conservative. Chronic ankle instability develops in 10-20 % of patients and the instability can be a result of sensomotoric deficits or insufficient healing of the lateral ligament complex. If the patient does not respond to an intensive rehabilitation program an operative reconstruction of the lateral ligaments has to be considered. Most of the procedures currently performed are anatomical reconstructions due to better long-term results compared to tenodesis procedures.

  9. Arthroscopic Management of Posteromedial Ankle Impingement

    PubMed Central

    Lui, Tun Hing

    2015-01-01

    Posteromedial ankle impingement is a rare clinical entity. It usually follows an inversion injury, with compression of the posterior tibiotalar ligament between the medial malleolus and talus. This can be treated by posterior ankle endoscopy through the posteromedial and posterolateral portals. The flexor hallucis longus tendon can be examined for any tenosynovitis or tendinopathy. The posteromedial corner of the ankle joint is reached with the instruments staying on the lateral side of the flexor hallucis longus tendon. The inflamed synovium, scar tissue, and fibrillated cartilage are debrided. PMID:26697299

  10. Diabetic charcot neuroarthropathy of the foot and ankle with osteomyelitis.

    PubMed

    Ramanujam, Crystal L; Stapleton, John J; Zgonis, Thomas

    2014-10-01

    One of the most devastating foot and/or ankle complications in the diabetic population with peripheral neuropathy is the presence of Charcot neuroarthropathy (CN). In recent years, diabetic limb salvage has been attempted more frequently as opposed to major lower extremity amputation for CN of the foot and ankle with ulceration and/or deep infection. Treatment strategies for osteomyelitis in the diabetic population have evolved. This article reviews some of the most common surgical strategies recommended for the diabetic patient with CN of the foot and/or ankle and concomitant osteomyelitis.

  11. Use of talectomy in modern foot and ankle surgery.

    PubMed

    Joseph, Thomas N; Myerson, Mark S

    2004-12-01

    Talectomy is a procedure that is undertaken rarely in modern orthopedic surgery; however, it has been performed for many years. Talectomy has been used most commonly in pediatric orthopedics with some degree of success in severe clubfoot deformity, arthrogryposis multiplex congenita, myelomeningocele, tuberculosis, and tumors. In adults, talectomy has been used in salvage procedures that involve nonunion of ankle fusions, failed total ankle arthroplasty, inflammatory arthropathy, neuroarthropathy, failed talar prostheses, failed pantalar fusions, adult neglected clubfoot, posttraumatic avascular necrosis talus, and deformities that are due to sciatic nerve palsy and compartment syndrome. This article consider what place talectomy has in modern adult foot and ankle surgery.

  12. Ankle-foot orthosis function in low-level myelomeningocele.

    PubMed

    Hullin, M G; Robb, J E; Loudon, I R

    1992-01-01

    Six children with low-level myelomeningocele underwent gait analysis. All showed excessive ankle dorsiflexion and knee flexion when walking barefoot. A rigid thermoplastic ankle-foot orthosis (AFO) improved gait by preventing ankle dorsiflexion and reducing knee flexion. Biomechanically, the AFO caused a reduction in external knee moment by aligning the knee with the ground reaction force. Small changes in the foot-shank angle of the orthosis had profound effects on knee mechanics. Knee hyperextension could be controlled by a rocker sole. Kinetic gait analysis permits understanding of the biomechanical effects of orthoses.

  13. [High complication rate after surgical treatment of ankle fractures].

    PubMed

    Bjørslev, Naja; Ebskov, Lars; Lind, Marianne; Mersø, Camilla

    2014-08-04

    The purpose of this study was to determine the quality and re-operation rate of the surgical treatment of ankle fractures at a large university hospital. X-rays and patient records of 137 patients surgically treated for ankle fractures were analyzed for: 1) correct classification according to Lauge-Hansen, 2) if congruity of the ankle joint was achieved, 3) selection and placement of the hardware, and 4) the surgeon's level of education. Totally 32 of 137 did not receive an optimal treatment, 11 were re-operated. There was no clear correlation between incorrect operation and the surgeon's level of education.

  14. Seasonality of Ankle Swelling: Population Symptom Reporting Using Google Trends.

    PubMed

    Liu, Fangwei; Allan, G Michael; Korownyk, Christina; Kolber, Michael; Flook, Nigel; Sternberg, Harvey; Garrison, Scott

    2016-07-01

    In our experience, complaints of ankle swelling are more common in summer, typically from patients with no obvious cardiovascular disease. Surprisingly, this observation has never been reported. To objectively establish this phenomenon, we sought evidence of seasonality in the public's Internet searches for ankle swelling. Our data, obtained from Google Trends, consisted of all related Google searches in the United States from January 4, 2004, to January 26, 2016. Consistent with our expectations and confirmed by similar data for Australia, Internet searches for information on ankle swelling are highly seasonal (highest in midsummer), with seasonality explaining 86% of search volume variability.

  15. Arthroscopic Management of Posteromedial Ankle Impingement.

    PubMed

    Lui, Tun Hing

    2015-10-01

    Posteromedial ankle impingement is a rare clinical entity. It usually follows an inversion injury, with compression of the posterior tibiotalar ligament between the medial malleolus and talus. This can be treated by posterior ankle endoscopy through the posteromedial and posterolateral portals. The flexor hallucis longus tendon can be examined for any tenosynovitis or tendinopathy. The posteromedial corner of the ankle joint is reached with the instruments staying on the lateral side of the flexor hallucis longus tendon. The inflamed synovium, scar tissue, and fibrillated cartilage are debrided.

  16. Optimal management of ankle syndesmosis injuries

    PubMed Central

    Porter, David A; Jaggers, Ryan R; Barnes, Adam Fitzgerald; Rund, Angela M

    2014-01-01

    Syndesmosis injuries occur when there is a disruption of the distal attachment of the tibia and fibula. These injuries occur commonly (up to 18% of ankle sprains), and the incidence increases in the setting of athletic activity. Recognition of these injuries is key to preventing long-term morbidity. Diagnosis and treatment of these injuries requires a thorough understanding of the normal anatomy and the role it plays in the stability of the ankle. A complete history and physical examination is of paramount importance. Patients usually experience an external rotation mechanism of injury. Key physical exam features include detailed documentation about areas of focal tenderness (syndesmosis and deltoid) and provocative maneuvers such as the external rotation stress test. Imaging workup in all cases should consist of radiographs with the physiologic stress of weight bearing. If these images are inconclusive, then further imaging with external rotation stress testing or magnetic resonance imaging are warranted. Nonoperative treatment is appropriate for stable injuries. Unstable injuries should be treated operatively. This consists of stabilizing the syndesmosis with either trans-syndesmotic screw or tightrope fixation. In the setting of a concomitant Weber B or C fracture, the fibula is anatomically reduced and stabilized with a standard plate and screw construct. Proximal fibular fractures, as seen in the Maisonneuve fracture pattern, are not repaired operatively. Recent interest is moving toward repair of the deltoid ligament, which may provide increased stability, especially in rehabilitation protocols that involve early weight bearing. Rehabilitation is focused on allowing patients to return to their pre-injury activities as quickly and safely as possible. Protocols initially focus on controlling swelling and recovery from surgery. The protocols then progress to restoration of motion, early protected weight bearing, restoration of strength, and eventually a

  17. Effects of hip and head position on ankle range of motion, ankle passive torque, and passive gastrocnemius tension.

    PubMed

    Andrade, R J; Lacourpaille, L; Freitas, S R; McNair, P J; Nordez, A

    2016-01-01

    Ankle joint range of motion (ROM) is notably influenced by the position of the hip joint. However, this result remains unexplained. Thus, the aim of this study was to test if the ankle passive torque and gastrocnemius muscle tension are affected by the hip and the head positions. The torque and the muscle shear elastic modulus (measured by elastography to estimate muscle tension) were collected in nine participants during passive ankle dorsiflexions performed in four conditions (by combining hip flexion at 90 or 150°, and head flexed or neutral). Ankle maximum dorsiflexion angle significantly decreased by flexing the hip from 150 to 90° (P < 0.001; mean difference 17.7 ± 2.5°), but no effect of the head position was observed (P > 0.05). Maximal passive torque and shear elastic modulus were higher with the hip flexed at 90° (P < 0.001). During submaximal ROM, no effects of the head and hip positioning (P > 0.05) were found for both torque and shear elastic modulus at a given common ankle angle among conditions. Shifts in maximal ankle angle due to hip angle manipulation are not related neither to changes in passive torque nor tension of the gastrocnemius. Further studies should be addressed to better understand the functional role of peripheral nerves and fasciae in the ankle ROM limits.

  18. Ankle control and strength training for children with cerebral palsy using the Rutgers Ankle CP: a case study.

    PubMed

    Cioi, Daniel; Kale, Angad; Burdea, Grigore; Engsberg, Jack; Janes, William; Ross, Sandy

    2011-01-01

    The purpose of the study described here was to develop and feasibility test the Rutgers Ankle CP, aimed at ankle strengthening and improved control for children with cerebral palsy (CP). The system was an upgrade in hardware (new foot attachment, new robot controller) and software (new games and programming language) of the earlier Rutgers Ankle in order to permit training of children with CP. The new Rutgers Ankle CP was used to train ankle strength and motor control in a 7 year old boy with CP during 36 rehabilitation sessions (12 weeks, 3 times/week). Assessments for impairment, function and quality of life were taken before and after training. Results indicated improvements in both strength and motor control. Gait function improved substantially in ankle kinematics, speed and endurance. Overall function (GMFM) indicated improvements that were typical of other ankle strength training programs. Quality of life increased beyond what would be considered a minimal clinical important difference. While these results are only for a single participant, they are very encouraging toward improving the function and quality of life of children with cerebral palsy. Further research with a larger number of participants is planned.

  19. MIDFOOT AND FOREFOOT INVOLVEMENT IN LATERAL ANKLE SPRAINS AND CHRONIC ANKLE INSTABILITY. PART 1: ANATOMY AND BIOMECHANICS

    PubMed Central

    Feger, Mark A.; Hertel, Jay

    2016-01-01

    The modern human foot is the culmination of more than five million years of evolution. The ankle-foot complex absorbs forces during loading, accommodates uneven surfaces, and acts as a lever for efficient propulsion. The ankle-foot complex has six independent functional segments that should be understood for proper assessment and treatment of foot and ankle injuries: the shank, rearfoot, midfoot, lateral forefoot, and the medial forefoot. The compliance of the individual segments of the foot is dependent on velocity, task, and active and passive coupling mechanisms within each of the foot segments. It is also important to understand the passive, active, and neural subsystems that are functionally intertwined to provide structure and control to the multisegmented foot. The purpose of the first part of this clinical commentary and current concepts review was to examine foot and ankle anatomy, detail the roles of the intrinsic and extrinsic foot and ankle musculature from a multisegmented foot perspective, and discuss the biomechanics of the ankle-foot complex during function. The interplay of segmental joint mobility, afferent and efferent sensorimotor function, and movement and stabilization provided by the extrinsic and intrinsic musculature is required to coordinate and execute the complex kinematic movements in the ankle-foot complex during propulsion. Level of Evidence 5 PMID:27904801

  20. MIDFOOT AND FOREFOOT INVOLVEMENT IN LATERAL ANKLE SPRAINS AND CHRONIC ANKLE INSTABILITY. PART 1: ANATOMY AND BIOMECHANICS.

    PubMed

    Fraser, John J; Feger, Mark A; Hertel, Jay

    2016-12-01

    The modern human foot is the culmination of more than five million years of evolution. The ankle-foot complex absorbs forces during loading, accommodates uneven surfaces, and acts as a lever for efficient propulsion. The ankle-foot complex has six independent functional segments that should be understood for proper assessment and treatment of foot and ankle injuries: the shank, rearfoot, midfoot, lateral forefoot, and the medial forefoot. The compliance of the individual segments of the foot is dependent on velocity, task, and active and passive coupling mechanisms within each of the foot segments. It is also important to understand the passive, active, and neural subsystems that are functionally intertwined to provide structure and control to the multisegmented foot. The purpose of the first part of this clinical commentary and current concepts review was to examine foot and ankle anatomy, detail the roles of the intrinsic and extrinsic foot and ankle musculature from a multisegmented foot perspective, and discuss the biomechanics of the ankle-foot complex during function. The interplay of segmental joint mobility, afferent and efferent sensorimotor function, and movement and stabilization provided by the extrinsic and intrinsic musculature is required to coordinate and execute the complex kinematic movements in the ankle-foot complex during propulsion.

  1. Ankle Arthrodesis Using an Anterior Titanium Dual Locked Plating Construct.

    PubMed

    Flint, Wesley W; Hirose, Christopher B; Coughlin, Michael J

    Ankle arthrodesis is currently the reference standard treatment for end-stage tibiotalar arthrosis. The fusion rates have varied in the published data from 59% to 100%. We reviewed 60 cases of consecutive anterior ankle arthrodesis using an anterior dual locked plating construct with respect to the fusion rate, time to fusion, pain relief, and complications. The patients were followed up for a mean of 1.1 years (range 16 weeks to 4 years). We found that our fusion rate was 97% for ankles not requiring structural allograft. The mean interval to fusion was 11.7 weeks, excluding those with a structural allograft. The mean visual analog scale pain scores decreased from 7 preoperatively to 2 at the final follow-up visit. Anterior ankle arthrodesis with dual locked plating provides excellent results with respect to the fusion rate with a low complication rate.

  2. Limiting the use of routine radiography for acute ankle injuries.

    PubMed Central

    Cockshott, W. P.; Jenkin, J. K.; Pui, M.

    1983-01-01

    In the diagnosis of ankle injuries routine radiography is often productive. An international survey of the average number of radiographs made of injured ankles suggested that two projections are adequate to detect fractures. This was confirmed in a prospective study of 242 patients coming to a hospital emergency department with recent ankle injuries. All the fractures could be identified on an anteroposterior or a lateral projection, although some were more obvious on an oblique view. As well, all the fractures were associated with malleolar soft-tissue swelling. Thus, radiography for acute ankle injuries could safely be restricted to patients with soft-tissue swelling, and fractures could be diagnosed using only two routine projections, though for management purposes additional projections might be needed. With a policy of limiting the use of radiography substantial cost reductions are possible. Images FIG. 1 PMID:6407744

  3. Magnetic resonance imaging of sports injuries of the ankle.

    PubMed

    Morrison, William B

    2003-04-01

    Basic sports-related injuries of the ankle include ligament tear, tendon degeneration and tear, bone bruise, fracture, impingement, osteochondral defect, and plantar fasciitis. This article discusses the magnetic resonance imaging appearance of these injuries.

  4. Posteromedial dislocation of the ankle without fracture or diastasis.

    PubMed

    Wang, L C; Love, M B

    1993-02-01

    This case report describes a patient with posteromedial dislocation of the ankle without fracture and without disruption of the tibiofibular syndesmosis. The pathogenesis of this uncommon lesion is discussed.

  5. Efficacy and Safety of Split Peroneal Tendon Lateral Ankle Stabilization.

    PubMed

    Shibuya, Naohiro; Bazán, D Issac; Evans, Andrew M; Agarwal, Monica R; Jupiter, Daniel C

    2016-01-01

    Chronic lateral ankle instability is a common condition. Split peroneal tendon lateral ankle stabilization, a modification of the Chrisman-Snook procedure, is biomechanically stable and often used for severe and/or recurrent chronic lateral ankle instability. The purpose of the present study was to evaluate the efficacy and safety of this technique. Specifically, the midterm recurrence of instability and postoperative complications, such as stiffness, neurologic pain, and wound healing complications, were evaluated. We evaluated 30 consecutive procedures with a minimal follow-up period of 1 year. The mean follow-up period was 25 ± 13 (median 19, range 13 to 62) months. Five patients (17%) developed recurrent ankle instability, of whom 4 underwent revision surgery. One superficial infection and two wound disruptions developed. Two patients experienced stiffness and eight (27%) surgically induced neurologic complaints, such as sural neuritis. Finally, 2 patients developed complex regional pain syndrome.

  6. Ultrasound of ankle and foot: overuse and sports injuries.

    PubMed

    Khoury, Viviane; Guillin, Raphaël; Dhanju, Jag; Cardinal, Etienne

    2007-06-01

    Sports and overuse injuries of the ankle and foot are commonly encountered in clinical practice. Ultrasound (US) has been established as an excellent diagnostic modality for foot and ankle injuries, providing a rapid noninvasive, economical, and readily available tool that is well tolerated by the patient with acute or chronic pain. The opportunity for dynamic examination is another advantage of US in evaluating ankle and foot pathology, where maneuvers such as muscle contraction and stressing of the joint may be particularly helpful. In many cases, US can be used as a first-line and only imaging modality for diagnosis. This article focuses on ankle disorders related to sports or overuse that affect tendons, including tendinosis, tenosynovitis, paratendinitis, rupture, dislocation, and ligaments that are commonly torn. The sonographic features of certain common foot disorders related to physical activity and overuse are also discussed, including plantar fasciitis, Morton's neuroma, stress fractures, and plantar plate injury.

  7. Reorganization of laryngeal motoneurons after crush injury in the recurrent laryngeal nerve of the rat

    PubMed Central

    Hernández-Morato, Ignacio; Valderrama-Canales, Francisco J; Berdugo, Gabriel; Arias, Gonzalo; McHanwell, Stephen; Sañudo, José; Vázquez, Teresa; Pascual-Font, Arán

    2013-01-01

    Motoneurons innervating laryngeal muscles are located in the nucleus ambiguus (Amb), but there is no general agreement on the somatotopic representation and even less is known on how an injury in the recurrent laryngeal nerve (RLN) affects this pattern. This study analyzes the normal somatotopy of those motoneurons and describes its changes over time after a crush injury to the RLN. In the control group (control group 1, n = 9 rats), the posterior cricoarytenoid (PCA) and thyroarytenoid (TA) muscles were injected with cholera toxin-B. In the experimental groups the left RLN of each animal was crushed with a fine tip forceps and, after several survival periods (1, 2, 4, 8, 12 weeks; minimum six rats per time), the PCA and TA muscles were injected as described above. After each surgery, the motility of the vocal folds was evaluated. Additional control experiments were performed; the second control experiment (control group 2, n = 6 rats) was performed labeling the TA and PCA immediately prior to the section of the superior laryngeal nerve (SLN), in order to eliminate the possibility of accidental labeling of the cricothyroid (CT) muscle by spread from the injection site. The third control group (control group 3, n = 5 rats) was included to determine if there is some sprouting from the SLN into the territories of the RLN after a crush of this last nerve. One week after the crush injury of the RLN, the PCA and TA muscles were injected immediately before the section of the SLN. The results show that a single population of neurons represents each muscle with the PCA in the most rostral position followed caudalwards by the TA. One week post-RLN injury, both the somatotopy and the number of labeled motoneurons changed, where the labeled neurons were distributed randomly; in addition, an area of topographical overlap of the two populations was observed and vocal fold mobility was lost. In the rest of the survival periods, the overlapping area is larger, but the movement of

  8. Reorganization of laryngeal motoneurons after crush injury in the recurrent laryngeal nerve of the rat.

    PubMed

    Hernández-Morato, Ignacio; Valderrama-Canales, Francisco J; Berdugo, Gabriel; Arias, Gonzalo; McHanwell, Stephen; Sañudo, José; Vázquez, Teresa; Pascual-Font, Arán

    2013-04-01

    Motoneurons innervating laryngeal muscles are located in the nucleus ambiguus (Amb), but there is no general agreement on the somatotopic representation and even less is known on how an injury in the recurrent laryngeal nerve (RLN) affects this pattern. This study analyzes the normal somatotopy of those motoneurons and describes its changes over time after a crush injury to the RLN. In the control group (control group 1, n = 9 rats), the posterior cricoarytenoid (PCA) and thyroarytenoid (TA) muscles were injected with cholera toxin-B. In the experimental groups the left RLN of each animal was crushed with a fine tip forceps and, after several survival periods (1, 2, 4, 8, 12 weeks; minimum six rats per time), the PCA and TA muscles were injected as described above. After each surgery, the motility of the vocal folds was evaluated. Additional control experiments were performed; the second control experiment (control group 2, n = 6 rats) was performed labeling the TA and PCA immediately prior to the section of the superior laryngeal nerve (SLN), in order to eliminate the possibility of accidental labeling of the cricothyroid (CT) muscle by spread from the injection site. The third control group (control group 3, n = 5 rats) was included to determine if there is some sprouting from the SLN into the territories of the RLN after a crush of this last nerve. One week after the crush injury of the RLN, the PCA and TA muscles were injected immediately before the section of the SLN. The results show that a single population of neurons represents each muscle with the PCA in the most rostral position followed caudalwards by the TA. One week post-RLN injury, both the somatotopy and the number of labeled motoneurons changed, where the labeled neurons were distributed randomly; in addition, an area of topographical overlap of the two populations was observed and vocal fold mobility was lost. In the rest of the survival periods, the overlapping area is larger, but

  9. Influence of stretch-evoked synaptic potentials on firing probability of cat spinal motoneurones.

    PubMed

    Gustafsson, B; McCrea, D

    1984-02-01

    Shapes of post-synaptic potentials (p.s.p.s) in cat motoneurones were compared with the time course of correlated changes in firing probability during repetitive firing. Excitatory and inhibitory post-synaptic potentials (e.p.s.p.s. and i.p.s.p.s) were evoked by brief triangular stretches of the triceps surae-plantaris muscles. Depolarizing current was injected through the recording micro-electrode to evoke repetitive firing and the post-stimulus time histogram of motoneurone spikes was obtained. E.p.s.p.s (n = 80) of different sizes (30-1040 microV) and rise times (1.1-8.2 ms) were investigated in fifty-nine motoneurones. The majority of the e.p.s.p.s were recorded in triceps surae-plantaris motoneurones with high levels of synaptic noise (estimated peak-to-peak fluctuations of 1.5-3.5 mV). This noise was generated by keeping the triceps surae-plantaris muscles stretched to a near maximal degree. The remaining e.p.s.p.s were recorded in motoneurones to other hind-limb muscles with a low level of synaptic noise. The height of the primary peak of the correlogram with respect to base-line firing rate increased in proportion to both amplitude and rising slope of the e.p.s.p.s. Using normalization procedures or using e.p.s.p.s of constant amplitude but different slopes and vice versa, the relative peak height increased with e.p.s.p. peak derivative with a slope of around 6/mV per millisecond and with e.p.s.p peak amplitude with a slope of about 1/mV. The shape of the correlogram (peak and trough) seemed well described by a linear combination of the shape of the e.p.s.p. derivative and that of the e.p.s.p. itself. The relative e.p.s.p. contribution (e.p.s.p.:e.p.s.p. derivative ratio) varied with e.p.s.p. amplitude and noise level, being largest (mostly 0.25-1.0) for small e.p.s.p.s (100-300 microV) in high levels of synaptic noise and smaller (0-0.25) for larger e.p.s.p.s and for e.p.s.p.s in a low noise background. In conformity with the above finding, a leaky

  10. Ultrasound-guided intervention in the ankle and foot

    PubMed Central

    Allen, Gina M; Watura, Roland

    2016-01-01

    In this comprehensive review, we discuss the main interventions performed in the foot and ankle for Achilles tendinopathy, Morton's neuromas and Plantar fasciitis as well as techniques for intra-articular and peritendinous injections. We present the different imaging techniques and injectable agents that can be used in clinical practice, trying to help the reader decide the most appropriate way of managing the patient with a problem in the ankle and foot. PMID:26537692

  11. The ANKLE TRIAL (ANKLE treatment after injuries of the ankle ligaments): what is the benefit of external support devices in the functional treatment of acute ankle sprain? : a randomised controlled trial

    PubMed Central

    2012-01-01

    Background Acute lateral ankle ligament injuries are very common problems in present health care. Still there is no hard evidence about which treatment strategy is superior. Current evidence supports the view that a functional treatment strategy is preferable, but insufficient data are present to prove the benefit of external support devices in these types of treatment. The hypothesis of our study is that external ankle support devices will not result in better outcome in the treatment of acute ankle sprains, compared to a purely functional treatment strategy. Overall objective is to compare the results of three different strategies of functional treatment for acute ankle sprain, especially to determine the advantages of external support devices in addition to functional treatment strategy, based on balance and coordination exercises. Methods/design This study is designed as a randomised controlled multi-centre trial with one-year follow-up. Adult and healthy patients (N = 180) with acute, single sided and first inversion trauma of the lateral ankle ligaments will be included. They will all follow the same schedule of balancing exercises and will be divided into 3 treatment groups, 1. pressure bandage and tape, 2. pressure bandage and brace and 3. no external support. Primary outcome measure is the Karlsson scoring scale; secondary outcomes are FAOS (subscales), number of recurrent ankle injuries, Visual Analogue Scales of pain and satisfaction and adverse events. They will be measured after one week, 6 weeks, 6 months and 1 year. Discussion The ANKLE TRIAL is a randomized controlled trial in which a purely functional treated control group, without any external support is investigated. Results of this study could lead to other opinions about usefulness of external support devices in the treatment of acute ankle sprain. Trial registration Netherlands Trial Register (NTR): NTR2151 PMID:22340371

  12. Antibiotic-loaded cement beads for Charcot ankle osteomyelitis.

    PubMed

    Ramanujam, Crystal L; Zgonis, Thomas

    2010-10-01

    The concomitant presence of osteomyelitis and diabetic Charcot neuroarthropathy of the foot and ankle places those patients affected at increased risk for limb loss. Antibiotic-loaded cement has been reported to be useful in the treatment of deep soft tissue and joint infections. The authors present an overview of this adjunctive treatment modality and present a case report using antibiotic-loaded cement beads in staged reconstruction for Charcot ankle osteomyelitis.

  13. Supramalleolar osteotomy for realignment of the ankle joint.

    PubMed

    Siddiqui, Noman A; Herzenberg, John E; Lamm, Bradley M

    2012-10-01

    Ankle replacement systems have not been as reliable as hip replacements in providing long-term relief of pain, increased motion, and return to full activity. Supramalleolar Osteotomy is an extraarticular procedure that realigns the mechanical axis, thereby restoring ankle function. The literature discussing knee arthritis has shown that realignment osteotomies of the tibia improve function and prolong total knee replacement surgery. The success of the procedure is predicated on understanding the patient's clinical and radiographic presentation and proper preoperative assessment and planning.

  14. Multivariable Dynamic Ankle Mechanical Impedance With Relaxed Muscles

    PubMed Central

    Lee, Hyunglae; Krebs, Hermano Igo; Hogan, Neville

    2015-01-01

    Neurological or biomechanical disorders may distort ankle mechanical impedance and thereby impair locomotor function. This paper presents a quantitative characterization of multivariable ankle mechanical impedance of young healthy subjects when their muscles were relaxed, to serve as a baseline to compare with pathophysiological ankle properties of biomechanically and/or neurologically impaired patients. Measurements using a highly backdrivable wearable ankle robot combined with multi-input multi-output stochastic system identification methods enabled reliable characterization of ankle mechanical impedance in two degrees-of-freedom (DOFs) simultaneously, the sagittal and frontal planes. The characterization included important ankle properties unavailable from single DOF studies: coupling between DOFs and anisotropy as a function of frequency. Ankle impedance in joint coordinates showed responses largely consistent with a second-order system consisting of inertia, viscosity, and stiffness in both seated (knee flexed) and standing (knee straightened) postures. Stiffness in the sagittal plane was greater than in the frontal plane and furthermore, was greater when standing than when seated, most likely due to the stretch of bi-articular muscles (medial and lateral gastrocnemius). Very low off-diagonal partial coherences implied negligible coupling between dorsiflexion-plantarflexion and inversion-eversion. The directions of principal axes were tilted slightly counterclockwise from the original joint coordinates. The directional variation (anisotropy) of ankle impedance in the 2-D space formed by rotations in the sagittal and frontal planes exhibited a characteristic “peanut” shape, weak in inversion-eversion over a wide range of frequencies from the stiffness dominated region up to the inertia dominated region. Implications for the assessment of neurological and biomechanical impairments are discussed. PMID:24686292

  15. Activation properties of trigeminal motoneurons in participants with and without bruxism

    PubMed Central

    D'Amico, Jessica M.; Yavuz, Ş. Utku; Saraçoğlu, Ahmet; Atiş, Elif Sibel; Türker, Kemal S.

    2013-01-01

    In animals, sodium- and calcium-mediated persistent inward currents (PICs), which produce long-lasting periods of depolarization under conditions of low synaptic drive, can be activated in trigeminal motoneurons following the application of the monoamine serotonin. Here we examined if PICs are activated in human trigeminal motoneurons during voluntary contractions and under physiological levels of monoaminergic drive (e.g., serotonin and norepinephrine) using a paired motor unit analysis technique. We also examined if PICs activated during voluntary contractions are larger in participants who demonstrate involuntary chewing during sleep (bruxism), which is accompanied by periods of high monoaminergic drive. In control participants, during a slowly increasing and then decreasing isometric contraction, the firing rate of an earlier-recruited masseter motor unit, which served as a measure of synaptic input to a later-recruited test unit, was consistently lower during derecruitment of the test unit compared with at recruitment (ΔF = 4.6 ± 1.5 imp/s). The ΔF, therefore, is a measure of the reduction in synaptic input needed to counteract the depolarization from the PIC to provide an indirect estimate of PIC amplitude. The range of ΔF values measured in the bruxer participants during similar voluntary contractions was the same as in controls, suggesting that abnormally high levels of monoaminergic drive are not continually present in the absence of involuntary motor activity. We also observed a consistent “onion skin effect” during the moderately sized contractions (<20% of maximal), whereby the firing rate of higher threshold motor units discharged at slower rates (by 4–7 imp/s) compared with motor units with relatively lower thresholds. The presence of lower firing rates in the more fatigue-prone, higher threshold trigeminal motoneurons, in addition to the activation of PICs, likely facilitates the activation of the masseter muscle during motor activities

  16. Functional Motor Recovery from Motoneuron Axotomy Is Compromised in Mice with Defective Corticospinal Projections

    PubMed Central

    Ding, Yuetong; Qu, Yibo; Feng, Jia; Wang, Meizhi; Han, Qi; So, Kwok-Fai; Wu, Wutian; Zhou, Libing

    2014-01-01

    Brachial plexus injury (BPI) and experimental spinal root avulsion result in loss of motor function in the affected segments. After root avulsion, significant motoneuron function is restored by re-implantation of the avulsed root. How much this functional recovery depends on corticospinal inputs is not known. Here, we studied that question using Celsr3|Emx1 mice, in which the corticospinal tract (CST) is genetically absent. In adult mice, we tore off right C5–C7 motor and sensory roots and re-implanted the right C6 roots. Behavioral studies showed impaired recovery of elbow flexion in Celsr3|Emx1 mice compared to controls. Five months after surgery, a reduced number of small axons, and higher G-ratio of inner to outer diameter of myelin sheaths were observed in mutant versus control mice. At early stages post-surgery, mutant mice displayed lower expression of GAP-43 in spinal cord and of myelin basic protein (MBP) in peripheral nerves than control animals. After five months, mutant animals had atrophy of the right biceps brachii, with less newly formed neuromuscular junctions (NMJs) and reduced peak-to-peak amplitudes in electromyogram (EMG), than controls. However, quite unexpectedly, a higher motoneuron survival rate was found in mutant than in control mice. Thus, following root avulsion/re-implantation, the absence of the CST is probably an important reason to hamper axonal regeneration and remyelination, as well as target re-innervation and formation of new NMJ, resulting in lower functional recovery, while fostering motoneuron survival. These results indicate that manipulation of corticospinal transmission may help improve functional recovery following BPI. PMID:25003601

  17. Frequency-dependent amplification of stretch-evoked excitatory input in spinal motoneurons.

    PubMed

    Powers, Randall K; Nardelli, Paul; Cope, T C

    2012-08-01

    Voltage-dependent calcium and sodium channels mediating persistent inward currents (PICs) amplify the effects of synaptic inputs on the membrane potential and firing rate of motoneurons. CaPIC channels are thought to be relatively slow, whereas the NaPIC channels have fast kinetics. These different characteristics influence how synaptic inputs with different frequency content are amplified; the slow kinetics of Ca channels suggest that they can only contribute to amplification of low frequency inputs (<5 Hz). To characterize frequency-dependent amplification of excitatory postsynaptic potentials (EPSPs), we measured the averaged stretch-evoked EPSPs in cat medial gastrocnemius motoneurons in decerebrate cats at different subthreshold levels of membrane potential. EPSPs were produced by muscle spindle afferents activated by stretching the homonymous and synergist muscles at frequencies of 5-50 Hz. We adjusted the stretch amplitudes at different frequencies to produce approximately the same peak-to-peak EPSP amplitude and quantified the amount of amplification by expressing the EPSP integral at different levels of depolarization as a percentage of that measured with the membrane hyperpolarized. Amplification was observed at all stretch frequencies but generally decreased with increasing stretch frequency. However, in many cells the amount of amplification was greater at 10 Hz than at 5 Hz. Fast amplification was generally reduced or absent when the lidocaine derivative QX-314 was included in the electrode solution, supporting a strong contribution from Na channels. These results suggest that NaPICs can combine with CaPICs to enhance motoneuron responses to modulations of synaptic drive over a physiologically significant range of frequencies.

  18. Multimodal distribution of amplitudes of miniature and spontaneous EPSPs recorded in rat trigeminal motoneurones.

    PubMed Central

    Min, M Y; Appenteng, K

    1996-01-01

    1. The whole-cell variant of the patch recording method has been used to obtain voltage recordings from trigeminal motoneurones in tissue slices (500 microns thick) taken from rats aged 8 days. Membrane properties (input resistance, membrane time constant and rheobase, i.e. threshold current required to elicit an action potential) of the motoneurones were determined and recordings made of the (untriggered) EPSP activity. 2. Untriggered EPSP activity was recorded in standard artificial cerebrospinal fluid (ACSF), ACSF with added tetrodotoxin (TTX) and in nominally Ca(2+)-free ACSF with added TTX. In each case the amplitude distributions of single EPSPs were peaky and could be fitted by a model consisting of the sum of equidistant Gaussians (n = 7/9 cells). In contrast, the amplitude distribution of the noise was always unimodal. 3. All EPSP activity recorded in the presence of TTX was abolished by addition of 6-cyano-7-nitroquinoxaline-2-3-dione (CNQX; 10 microM), suggesting the activity was all mediated by glutamate acting primarily at AMPA/kainate receptors. 4. In the majority of cases, there was no correlation between the amplitude of EPSPs underlying each Gaussian and the EPSP rise time but there was a positive correlation between the EPSP half-width and EPSP rise time. The rise times of EPSPs underlying the first, and all, fitted Gaussians were similar to that for the total sample of EPSPs in each motoneurone. Taken together, this suggests that the EPSPs underlying each Gaussian arise from inputs to different dendritic compartments, and that the range of compartments is similar for EPSPs underlying successive Gaussians. 5. Two conclusions are drawn. First, EPSPs of different dendritic origin have similar amplitudes at the soma. Second, the multimodal distribution of EPSP amplitudes recorded in the presence of TTX raises the possibility that individual boutons may contain multiple release sites, with each perhaps operating on a separate functional group of

  19. Motoneuronal TASK channels contribute to immobilizing effects of inhalational general anesthetics

    PubMed Central

    Lazarenko, Roman M.; Willcox, Sarah C.; Shu, Shaofang; Berg, Allison P.; Jevtovic-Todorovic, Vesna; Talley, Edmund M.; Chen, Xiangdong; Bayliss, Douglas A.

    2010-01-01

    General anesthetics cause sedation, hypnosis and immobilization via central nervous system mechanisms that remain incompletely understood; contributions of particular anesthetic targets in specific neural pathways remain largely unexplored. Among potential molecular targets for mediating anesthetic actions, the TASK subgroup (TASK-1, K2P3.1& TASK-3, K2P9.1) of background K+ channels are appealing candidates since they are expressed in CNS sites relevant to anesthetic actions and activated by clinically relevant concentrations of inhaled anesthetics. Here, we used global and conditional TASK channel single and double subunit knockout mice to demonstrate definitively that TASK channels account for motoneuronal anesthetic-activated K+ currents and to test their contributions to sedative, hypnotic and immobilizing anesthetic actions. In motoneurons from all knockout mice lines, TASK-like currents were reduced and cells were less sensitive to hyperpolarizing effects of halothane and isoflurane. In an immobilization assay, higher concentrations of both halothane and isoflurane were required to render TASK knockout animals unresponsive to a tail pinch; in assays of sedation (loss of movement) and hypnosis (loss-of-righting reflex), TASK knockout mice showed a modest decrease in sensitivity, and only for halothane. In conditional knockout mice, with TASK channel deletion restricted to cholinergic neurons, immobilizing actions of the inhaled anesthetics and sedative effects of halothane were reduced to the same extent as in global knockout lines. These data indicate that TASK channels in cholinergic neurons are a molecular substrate for select actions of inhaled anesthetics; for immobilization, which is spinally mediated, these data implicate motoneurons as the likely neuronal substrate. PMID:20519544

  20. Motoneuronal TASK channels contribute to immobilizing effects of inhalational general anesthetics.

    PubMed

    Lazarenko, Roman M; Willcox, Sarah C; Shu, Shaofang; Berg, Allison P; Jevtovic-Todorovic, Vesna; Talley, Edmund M; Chen, Xiangdong; Bayliss, Douglas A

    2010-06-02

    General anesthetics cause sedation, hypnosis, and immobilization via CNS mechanisms that remain incompletely understood; contributions of particular anesthetic targets in specific neural pathways remain largely unexplored. Among potential molecular targets for mediating anesthetic actions, members of the TASK subgroup [TASK-1 (K2P3.1) and TASK-3 (K2P9.1)] of background K(+) channels are appealing candidates since they are expressed in CNS sites relevant to anesthetic actions and activated by clinically relevant concentrations of inhaled anesthetics. Here, we used global and conditional TASK channel single and double subunit knock-out mice to demonstrate definitively that TASK channels account for motoneuronal, anesthetic-activated K(+) currents and to test their contributions to sedative, hypnotic, and immobilizing anesthetic actions. In motoneurons from all knock-out mice lines, TASK-like currents were reduced and cells were less sensitive to hyperpolarizing effects of halothane and isoflurane. In an immobilization assay, higher concentrations of both halothane and isoflurane were required to render TASK knock-out animals unresponsive to a tail pinch; in assays of sedation (loss of movement) and hypnosis (loss-of-righting reflex), TASK knock-out mice showed a modest decrease in sensitivity, and only for halothane. In conditional knock-out mice, with TASK channel deletion restricted to cholinergic neurons, immobilizing actions of the inhaled anesthetics and sedative effects of halothane were reduced to the same extent as in global knock-out lines. These data indicate that TASK channels in cholinergic neurons are molecular substrates for select actions of inhaled anesthetics; for immobilization, which is spinally mediated, these data implicate motoneurons as the likely neuronal substrates.

  1. Astrocytes expressing mutant SOD1 and TDP43 trigger motoneuron death that is mediated via sodium channels and nitroxidative stress

    PubMed Central

    Rojas, Fabiola; Cortes, Nicole; Abarzua, Sebastian; Dyrda, Agnieszka; van Zundert, Brigitte

    2013-01-01

    Amyotrophic lateral sclerosis (ALS) is a fatal paralytic disorder caused by dysfunction and degeneration of motor neurons. Multiple disease-causing mutations, including in the genes for SOD1 and TDP-43, have been identified in ALS. Astrocytes expressing mutant SOD1 are strongly implicated in the pathogenesis of ALS: we have shown that media conditioned by astrocytes carrying mutant SOD1G93A contains toxic factor(s) that kill motoneurons by activating voltage-sensitive sodium (Nav) channels. In contrast, a recent study suggests that astrocytes expressing mutated TDP43 contribute to ALS pathology, but do so via cell-autonomous processes and lack non-cell-autonomous toxicity. Here we investigate whether astrocytes that express diverse ALS-causing mutations release toxic factor(s) that induce motoneuron death, and if so, whether they do so via a common pathogenic pathway. We exposed primary cultures of wild-type spinal cord cells to conditioned medium derived from astrocytes (ACM) that express SOD1 (ACM-SOD1G93A and ACM-SOD1G86R) or TDP43 (ACM-TDP43A315T) mutants; we show that such exposure rapidly (within 30–60 min) increases dichlorofluorescein (DCF) fluorescence (indicative of nitroxidative stress) and leads to extensive motoneuron-specific death within a few days. Co-application of the diverse ACMs with anti-oxidants Trolox or esculetin (but not with resveratrol) strongly improves motoneuron survival. We also find that co-incubation of the cultures in the ACMs with Nav channel blockers (including mexiletine, spermidine, or riluzole) prevents both intracellular nitroxidative stress and motoneuron death. Together, our data document that two completely unrelated ALS models lead to the death of motoneuron via non-cell-autonomous processes, and show that astrocytes expressing mutations in SOD1 and TDP43 trigger such cell death through a common pathogenic pathway that involves nitroxidative stress, induced at least in part by Nav channel activity. PMID:24570655

  2. Permanent central synaptic disconnection of proprioceptors after nerve injury and regeneration. II. Loss of functional connectivity with motoneurons.

    PubMed

    Bullinger, Katie L; Nardelli, Paul; Pinter, Martin J; Alvarez, Francisco J; Cope, Timothy C

    2011-11-01

    Regeneration of a cut muscle nerve fails to restore the stretch reflex, and the companion paper to this article [Alvarez FJ, Titus-Mitchell HE, Bullinger KL, Kraszpulski M, Nardelli P, Cope TC. J Neurophysiol (August 10, 2011). doi:10.1152/jn.01095.2010] suggests an important central contribution from substantial and persistent disassembly of synapses between regenerated primary afferents and motoneurons. In the present study we tested for physiological correlates of synaptic disruption. Anesthetized adult rats were studied 6 mo or more after a muscle nerve was severed and surgically rejoined. We recorded action potentials (spikes) from individual muscle afferents classified as IA like (*IA) by several criteria and tested for their capacity to produce excitatory postsynaptic potentials (EPSPs) in homonymous motoneurons, using spike-triggered averaging (STA). Nearly every paired recording from a *IA afferent and homonymous motoneuron (93%) produced a STA EPSP in normal rats, but that percentage was only 17% in rats with regenerated nerves. In addition, the number of motoneurons that produced aggregate excitatory stretch synaptic potentials (eSSPs) in response to stretch of the reinnervated muscle was reduced from 100% normally to 60% after nerve regeneration. The decline in functional connectivity was not attributable to synaptic depression, which returned to its normally low level after regeneration. From these findings and those in the companion paper, we put forward a model in which synaptic excitation of motoneurons by muscle stretch is reduced not only by misguided axon regeneration that reconnects afferents to the wrong receptor type but also by retraction of synapses with motoneurons by spindle afferents that successfully reconnect with spindle receptors in the periphery.

  3. Distribution and density of contacts from noradrenergic and serotonergic boutons on the dendrites of neck flexor motoneurons in the adult cat.

    PubMed

    Maratta, Robert; Fenrich, Keith K; Zhao, Ethan; Neuber-Hess, Monica S; Rose, P Ken

    2015-08-01

    Serotonergic (5-HT) and noradrenergic (NA) input to spinal motoneurons is essential for generating plateau potentials and self-sustained discharges. Extensor motoneurons are densely innervated by 5-HT and NA synapses and have robust plateau potentials and self-sustained discharges. Conversely, plateau potentials and self-sustained discharges are very rare in flexor motoneurons. The most likely reasons for this difference are that flexor motoneurons have few 5-HT and NA synapses and/or they are distributed distant to the channels responsible for plateau potentials and self-sustained discharges. However, the distribution of 5-HT and NA synapses on flexor motoneurons is unknown. Here we describe the distribution and density of 5-HT and NA synapses on motoneurons that innervate the flexor neck muscle, rectus capitis anterior (RCA), in the adult cat. Using a combination of intracellular staining, fluorescent immunohistochemistry, and 3D reconstruction techniques, we found that 5-HT and NA synapses are widely distributed throughout the dendritic trees of RCA motoneurons, albeit with a strong bias to small-diameter dendrites and to medial dendrites in the case of NA contacts. The number of 5-HT and NA contacts per motoneuron ranged, respectively, from 381 to 1,430 and from 642 to 1,382, which is 2.3- and 1.4-fold less than neck extensor motoneurons (Montague et al., J Comp Neurol 2013;521:638-656). These results suggest that 5-HT and NA synapses on flexor motoneurons may provide a powerful means of amplifying synaptic currents without incurring plateau potentials or self-sustained discharges. This feature is well suited to meet the biomechanical demands imposed on flexor muscles during different motor tasks.

  4. Modulation of voltage-gated sodium channels hyperpolarizes the voltage threshold for activation in spinal motoneurones.

    PubMed

    Power, Kevin E; Carlin, Kevin P; Fedirchuk, Brent

    2012-03-01

    Previous work has shown that motoneurone excitability is enhanced by a hyperpolarization of the membrane potential at which an action potential is initiated (V(th)) at the onset, and throughout brainstem-evoked fictive locomotion in the adult decerebrate cat and neonatal rat. Modeling work has suggested the modulation of Na(+) conductance as a putative mechanism underlying this state-dependent change in excitability. This study sought to determine whether modulation of voltage-gated sodium channels could induce V(th) hyperpolarization. Whole-cell patch-clamp recordings were made from antidromically identified lumbar spinal motoneurones in an isolated neonatal rat spinal cord preparation. Recordings were made with and without the bath application of veratridine, a plant alkaloid neurotoxin that acts as a sodium channel modulator. As seen in HEK 293 cells expressing Nav1.2 channels, veratridine-modified channels demonstrated a hyperpolarizing shift in their voltage-dependence of activation and a slowing of inactivation that resulted in an enhanced inward current in response to voltage ramp stimulations. In the native rat motoneurones, veratridine-modified sodium channels induced a hyperpolarization of V(th) in all 29 neonatal rat motoneurones examined (mean hyperpolarization: -6.6 ± 4.3 mV). V(th) hyperpolarization was not due to the effects on Ca(2+) and/or K(+) channels as blockade of these currents did not alter V(th). Veratridine also significantly increased the amplitude of persistent inward currents (PICs; mean increase: 72.5 ± 98.5 pA) evoked in response to slow depolarizing current ramps. However, the enhancement of the PIC amplitude had a slower time course than the hyperpolarization of V(th), and the PIC onset voltage could be either depolarized or hyperpolarized, suggesting that PIC facilitation did not mediate the V(th) hyperpolarization. We therefore suggest that central neuronal circuitry in mammals could affect V(th) in a mechanism similar to that of

  5. Evidence for interneuronally mediated Ia excitatory effects to human quadriceps motoneurones.

    PubMed Central

    Fournier, E; Meunier, S; Pierrot-Deseilligny, E; Shindo, M

    1986-01-01

    The possibility was investigated that interneuronal pathways contribute to Ia excitation of quadriceps motoneurones in normal man. Two techniques were used: the indirect spatial facilitation technique for investigating summation of Ia excitatory effects in interneurones which may be interposed in pathways to quadriceps motoneurones; the post-stimulus time histogram method for time course measurement of the firing probability of voluntarily activated motor units following femoral nerve stimulation. The spatial facilitation technique was applied while using the quadriceps H reflex to assess the excitability of the whole motoneurone pool: the comparison was made between the excitatory effects of two conditioning stimuli applied either separately or together. Summation of effects at a premotoneuronal level is suggested if facilitation of the reflex evoked on combined conditioning stimulation is larger than the algebraic sum of facilitations evoked by separate stimuli. Quadriceps tendon tap and electrical stimulations applied to either the femoral nerve or to two of its branches, the nerves to the vastus lateralis and vastus medialis muscles, were used as conditioning stimuli. Since these stimuli were very weak (their strength being about at the threshold for facilitation of the test reflex), it can be assumed that they activated predominantly Ia fibres. The facilitation of the quadriceps H reflex evoked on combined stimulation was significantly larger than the algebraic sum of facilitations evoked by separate stimuli. In many experiments, although conditioning stimuli did not evoke any reflex facilitation when applied alone, a significant facilitation appeared on combined stimulation. This 'extra' facilitation of the reflex on combined stimulation appeared with a central latency of 4-5 ms. It is argued that the only mechanism compatible with such a latency is summation at a premotoneuronal level. Post-stimulus time histograms (p.s.t.h.s) of voluntarily activated

  6. Gait generation for powered Hip-Ankle-Linkage-Orthosis.

    PubMed

    Jaeryoung Lee; Mizumoto, Ryota; Obinata, Goro; Genda, Eiichi; Stefanov, Dimitar; Aoki, Hirofumi; Yanling Pei

    2015-08-01

    A hip-knee-ankle-foot orthotic system called `HALO'(Hip and Ankle Linked Orthosis) for paraplegic walking has been developed in our previous study. Each ankle joint of the HALO system is linked with a medial single joint via a wire which allows both feet of the orthosis to stay always parallel to the floor during walking and assists swinging the leg. The tests of the HALO system demonstrated that it allows smoother walking and easy don/doff. In order to improve further the characteristics of the previous design, we started a new project called pHALO aiming at further reducing of the energy expenditure during walking. As a difference from the previous solution where ankle joints were restrained, the new solution will incorporate two actuators to control the ankle joints angles. As an intermediate step from the development of the pHALO system, in this study we added to the existing system a feedback PI controller to control the ankle joint angle of the right foot in the push-off phase and conducted an experiment to evaluate the effect of the new design on the walking patterns and energy efficiency. The results showed longer stride length, faster gait speed, smaller variation of the CoG, and less energy consumption.

  7. In vitro measurement of intraarticular pressure in the ankle joint.

    PubMed

    Suckel, Andreas; Muller, Otto; Wachter, Nikolaus; Kluba, Torsten

    2010-05-01

    Ankle joint affections and injuries are common problems in sports traumatology and in the daily routine of arthroscopic surgeons. However, there is little knowledge regarding intraarticular loads. Pressures on the ankle were determined in a dynamic model on 8 cadaver specimens, applying forces to tendons of the foot over the stance phase under vertical loading. A characteristic course of loading in the tibiotalar joint with a rapid increase upon heel contact was observed. It increased gradually to reach a maximum after 70% of the stance phase, during the push-off phase. The major torque in the ankle joint is located anterolaterally. A dynamic loading curve of the ankle joint can be demonstrated. These observations explain phenomena such as the appearance of osteophytes on the anterior tibia in the case of ankle osteoarthritis and the relatively low incidence of posterior tibial edge fragments in the case of trimalleolar ankle fracture. Furthermore, the medial side of the talus is less loaded compared to the lateral side, which appears relevant to the treatment of osteochondrosis dissecans.

  8. Conservative management of posterior ankle impingement: a case report

    PubMed Central

    Senécal, Isabelle; Richer, Nadia

    2016-01-01

    Objective: To describe the pain and functional improvements of a patient with posterior ankle impingement following a treatment plan incorporating soft tissue therapy, chiropractic adjustment and a progressive rehabilitation program. Clinical Features: A 37-year- old male presented with posterolateral ankle pain exacerbated by plantar flexion two weeks after sustaining an inversion ankle sprain. Oedema was present and the patient was describing a sensation of instability while walking. The initial diagnosis of lateral ankle sprain was found to be complicated by a posterior ankle impingement caused by a tenosynovitis of the flexor hallucis longus sheath suspected during the physical examination and confirmed by MRI. Intervention and Outcome: The patient was treated over a 14-week period. Soft tissue therapy, a rehabilitation program and cortisone injection were used to treat this condition. A precise description of the rehabilitation program that contains open kinetic chain, closed kinetic chain, proprioception, and conditioning exercises prescribed to the patient is given. After the treatment plan, the patient returned to play pain free and had no daily living restrictions. Summary: A protocol including rest, soft tissue therapy, open and closed kinetic chain exercises, sport-specific exercises and cortisone injection appeared to facilitate complete recovery of this patient’s posterior ankle impingement. PMID:27385836

  9. Valdecoxib provides effective pain relief following acute ankle sprain.

    PubMed

    Diaz, J A; Cuervo, C; Valderrama, A M; Kohles, J

    2006-01-01

    We sought to determine whether valdecoxib is as effective as diclofenac in treating acute ankle sprain. Patients (n=202) with acute first- and second-degree ankle sprain were randomized to valdecoxib (40 mg twice daily on day 1 followed by 40 mg once daily on days 2-7) or diclofenac (75 mg twice daily). The primary efficacy end-point was the Patient's Assessment of Ankle Pain visual analogue scale (VAS, 0-100 mm) value on day 4. Valdecoxib was as efficacious as diclofenac in treating the signs and symptoms of acute ankle sprain. The mean VAS reduction in ankle pain on day 4 was not different between groups; the two-sided 95% confidence interval for the between-group difference was within the prespecified limit for non-inferiority (10 mm). There were no significant differences between groups for all secondary efficacy end-points. The two treatments were similarly effective and well tolerated for treatment of acute ankle sprain.

  10. CLINICAL COMMENTARY ON MIDFOOT AND FOREFOOT INVOLVEMENT IN LATERAL ANKLE SPRAINS AND CHRONIC ANKLE INSTABILITY. PART 2: CLINICAL CONSIDERATIONS

    PubMed Central

    Feger, Mark A.; Hertel, Jay

    2016-01-01

    Lateral ankle sprains (LAS) and chronic ankle instability (CAI) are common musculoskeletal injuries that are a result of inversion injury during sport. The midfoot and forefoot is frequently injured during a LAS, is often overlooked during clinical examination, and maybe contributory to the development of CAI. The purpose of part two of this clinical commentary and current concept review is to increase clinician's awareness of the contribution of midfoot and forefoot impairment to functional limitation and disability of individuals who experience LAS and CAI and to facilitate future research in this area. The importance of multisegmented foot and ankle assessment from a clinical and research perspective is stressed. Select physical assessment and manual therapeutic techniques are presented to assist the clinician in examination and treatment of the ankle-foot complex in patients with LAS and CAI. PMID:27999731

  11. Ankle mechanics during sidestep cutting implicates need for 2-degrees of freedom powered ankle-foot prostheses.

    PubMed

    Ficanha, Evandro M; Rastgaar, Mohammad; Kaufman, Kenton R

    2015-01-01

    The ankle joint of currently available powered prostheses is capable of controlling one degree of freedom (DOF), focusing on improved mobility in the sagittal plane. To increase agility, the requirements of turning in prosthesis design need to be considered. Ankle kinematics and kinetics were studied during sidestep cutting and straight walking. There were no significant differences between the ankle sagittal plane mechanics when comparing sidestep cutting and straight walking; however, significant differences were observed in ankle frontal plane mechanics. During straight walking, the inversion-eversion (IE) angles were smaller than with sidestep cutting. The ankle that initiated the sidestep cutting showed progressively increasing inversion from 2 to 13 degrees while the following contralateral step showed progressively decreasing inversion from 8 to -4 degrees during normal walking speed. The changes in IE kinematics were the most significant during sidestep cutting compared with straight walking. The IE moments of the step that initiated the sidestep cutting were always in eversion, acting as a braking moment opposing the inverting motion. This suggests that an ankle-foot prosthesis with active DOFs in the sagittal and frontal planes will increase the agility of gait for patients with limb loss.

  12. Biomechanics of the ankle-foot system during stair ambulation: implications for design of advanced ankle-foot prostheses.

    PubMed

    Sinitski, Emily H; Hansen, Andrew H; Wilken, Jason M

    2012-02-02

    Unilateral lower limb prosthesis users display temporal, kinematic, and kinetic asymmetries between limbs while ascending and descending stairs. These asymmetries are due, in part, to the inability of current prosthetic devices to effectively mimic normal ankle function. The purpose of this study was to provide a comprehensive set of biomechanical data for able-bodied and unilateral transtibial amputee (TTA) ankle-foot systems for level-ground (LG), stair ascent (SA), and stair descent (SD), and to characterize deviations from normal performance associated with prosthesis use. Ankle joint kinematics, kinetics, torque-angle curves, and effective shapes were calculated for twelve able-bodied individuals and twelve individuals with TTA. The data from this study demonstrated the prosthetic limb can more effectively mimic the range of motion and power output of a normal ankle-foot during LG compared to SA and SD. There were larger differences between the prosthetic and able-bodied limbs during SA and SD, most evident in the torque-angle curves and effective shapes. These data can be used by persons designing ankle-foot prostheses and provide comparative data for assessment of future ankle-foot prosthesis designs.

  13. Quantitative analysis of human ankle characteristics at different gait phases and speeds for utilizing in ankle-foot prosthetic design

    PubMed Central

    2014-01-01

    Background Ankle characteristics vary in terms of gait phase and speed change. This study aimed to quantify the components of ankle characteristics, including quasi-stiffness and work in different gait phases and at various speeds. Methods The kinetic and kinematic data of 20 healthy participants were collected during normal gait at four speeds. Stance moment-angle curves were divided into three sub-phases including controlled plantarflexion, controlled dorsiflexion and powered plantarflexion. The slope of the moment-angle curves was quantified as quasi-stiffness. The area under the curves was defined as work. Results The lowest quasi-stiffness was observed in the controlled plantarflexion. The fitted line to moment-angle curves showed R2 > 0.8 at controlled dorsiflexion and powered plantarflexion. Quasi-stiffness was significantly different at different speeds (P = 0.00). In the controlled dorsiflexion, the ankle absorbed energy; by comparison, energy was generated in the powered plantarflexion. A negative work value was recorded at slower speeds and a positive value was observed at faster speeds. Ankle peak powers were increased with walking speed (P = 0.00). Conclusions Our findings suggested that the quasi-stiffness and work of the ankle joint can be regulated at different phases and speeds. These findings may be clinically applicable in the design and development of ankle prosthetic devices that can naturally replicate human walking at various gait speeds. PMID:24568175

  14. Immobile survival of motoneuron (SMN) protein stored in Cajal bodies can be mobilized by protein interactions.

    PubMed

    Förthmann, Benjamin; Brinkmann, Hella; Ratzka, Andreas; Stachowiak, Michal K; Grothe, Claudia; Claus, Peter

    2013-07-01

    Reduced levels of survival of motoneuron (SMN) protein lead to spinal muscular atrophy, but it is still unknown how SMN protects motoneurons in the spinal cord against degeneration. In the nucleus, SMN is associated with two types of nuclear bodies denoted as gems and Cajal bodies (CBs). The 23 kDa isoform of fibroblast growth factor-2 (FGF-2(23)) is a nuclear protein that binds to SMN and destabilizes the SMN-Gemin2 complex. In the present study, we show that FGF-2(23) depletes SMN from CBs without affecting their general structure. FRAP analysis of SMN-EGFP in CBs demonstrated that the majority of SMN in CBs remained mobile and allowed quantification of fast, slow and immobile nuclear SMN populations. The potential for SMN release was confirmed by in vivo photoconversion of SMN-Dendra2, indicating that CBs concentrate immobile SMN that could have a specialized function in CBs. FGF-2(23) accelerated SMN release from CBs, accompanied by a conversion of immobile SMN into a mobile population. Furthermore, FGF-2(23) caused snRNP accumulation in CBs. We propose a model in which Cajal bodies store immobile SMN that can be mobilized by its nuclear interaction partner FGF-2(23), leading to U4 snRNP accumulation in CBs, indicating a role for immobile SMN in tri-snRNP assembly.

  15. Depletion of TDP-43 affects Drosophila motoneurons terminal synapsis and locomotive behavior.

    PubMed

    Feiguin, Fabian; Godena, Vinay K; Romano, Giulia; D'Ambrogio, Andrea; Klima, Raffaella; Baralle, Francisco E

    2009-05-19

    Pathological modifications in the highly conserved and ubiquitously expressed heterogeneous ribonucleoprotein TDP-43 were recently associated to neurodegenerative diseases including amyotrophic lateral sclerosis (ALS), a late-onset disorder that affects predominantly motoneurons [Neumann, M. et al. (2006) Ubiquitinated TDP-43 in frontotemporal lobar degeneration and amyotrophic lateral sclerosis. Science 314, 130-133, Sreedharan, J. et al. (2008) TDP-43 mutations in familial and sporadic amyotrophic lateral sclerosis. Science 319, 1668-1672, Kabashi, E. et al. (2008) TARDBP mutations in individuals with sporadic and familial amyotrophic lateral sclerosis. Nat. Genet. 40, 572-574]. However, the function of TDP-43 in vivo is unknown and a possible direct role in neurodegeneration remains speculative. Here, we report that flies lacking Drosophila TDP-43 appeared externally normal but presented deficient locomotive behaviors, reduced life span and anatomical defects at the neuromuscular junctions. These phenotypes were rescued by expression of the human protein in a restricted group of neurons including motoneurons. Our results demonstrate the role of this protein in vivo and suggest an alternative explanation to ALS pathogenesis that may be more due to the lack of TDP 43 function than to the toxicity of the aggregates.

  16. Participation of estradiol and progesterone in the retrograde labeling of pubococcygeus motoneurons of the female rat.

    PubMed

    Cuevas, E; Camacho, M; Alvarado, M; Hudson, R; Pacheco, P

    2006-07-21

    Retrograde labeling with horseradish peroxidase conjugated to wheat germ agglutinin showed that the pubococcygeus muscles of the female rat are innervated by a population of motoneurons located in a column approximately 2 mm in length in the central region of lamina IX of the sixth lumbar-first sacral spinal cord segments. These neurons have a dendritic distribution that projects to the lateral, medial and ventral regions of the gray matter. Values for soma size, primary dendrite length and arborization area obtained from intact animals that were in diestrous-2, were significantly reduced following ovariectomy. After hormone priming of the ovariectomized animals with estradiol benzoate and progesterone, an additional injection of estradiol benzoate alone or followed by progesterone increased the labeled length of the primary dendrites distributed to the lateral, but not to the medial or ventral regions of the gray matter in the spinal cord. However, dendritic labeling was not significantly increased when only progesterone was additionally injected. It therefore seems that pubococcygeus muscle motoneurons of the female rat are sensitive to the effects of gonadal hormones.

  17. The mouse mutation muscle deficient (mdf) is characterized by a progressive motoneuron disease.

    PubMed

    Blot, S; Poirier, C; Dreyfus, P A

    1995-11-01

    Muscle deficient (mdf) is an autosomal-recessive mutation mapped to mouse chromosome 19. The clinical phenotype and the muscle histopathology, briefly described in 1980, and the nervous system histopathology are detailed in the present study. Homozygotes develop a posterior waddle at 4 to 8 weeks of age. Soon thereafter, the hindlimbs become paralyzed and weakness appears in forelimbs, leading to a serious disability. The disease progresses slowly and the mean lifespan is reduced to 8 months. Skeletal muscles exhibit a neurogenic atrophy with signs of reinnervation. Peripheral nerves display axonal degeneration. Neurons within the spinal cord ventral horn, and some motor nuclei of the brain stem, are affected by a cytoplasmic vacuolar degeneration. Ascending and descending spinal cord tracts appear normal. An astrogliosis, restricted to the ventral horn of the spinal cord, occurs in mdf/mdf mice of 10 weeks of age. These clinical and histological features are indicative of a progressive motor neuronopathy. Among the murine spinal muscular atrophies, the programmed cell death of the mdf motoneurons is morphologically similar to wobbler. Because of the long time course, the mdf mutation may represent a valuable tool for understanding juvenile motoneuron diseases with chronic evolution, even though the murine locus is not syntenic with the human ones.

  18. Perineal striated muscles: Anatomy, spinal motoneurons, and participation on copulatory behavior in male rabbits (Oryctolagus cuniculus).

    PubMed

    Zempoalteca, R; Lucio, R A; Eguibar, J R

    2008-09-01

    Despite the importance of rabbits in reproductive studies, little information is available on the anatomy and participation of the striated-perineal muscles in male copulatory behavior. In our study, we describe the gross anatomy of two striated-perineal muscles: the ischiocavernosus (ICm) and the bulbospongiosus (BSm). Both muscles have their origin at the ischiadic arc, but the ICm is inserted into the penile crura and the BSm onto the ligamentum suspensorium of the penis. The motoneurons of both muscles were identified using retrograde labeling with horseradish peroxidase coupled to wheat-germ agglutinin. Motoneurons were dispersed in the lower-lumbar and upper-sacral spinal-cord segments, instead of being aggregated in the neuronal nucleus as in other species: the rat, mouse, gerbil, cat, and man. Bilateral dennervation of the ICm or BSm or both in sexually experienced male rabbits did not affect copulatory variables measured at 10, 20, and 30 days after surgery. However, muscular dennervation produced extravaginal ejaculations in 42% of copulatory tests and no ejaculation in 7% of tests, although male pelvic thrusting occurred. These results suggest the participation of the ICm and BSm perineal muscles in penile orientation during copulation but not in seminal emission as described in other mammalian species.

  19. Neuropathology in respiratory-related motoneurons in young Pompe (Gaa−/−) mice

    PubMed Central

    Turner, Sara M.F.; Hoyt, Aaron K.; ElMallah, Mai K.; Falk, Darin J.; Byrne, Barry J.; Fuller, David D.

    2016-01-01

    Respiratory and/or lingual dysfunction are among the first motor symptoms in Pompe disease, a disorder resulting from absence or dysfunction of the lysosomal enzyme acid α-glucosidase (GAA). Here, we histologically evaluated the medulla, cervical and thoracic spinal cords in 6 weeks old asymptomatic Pompe (Gaa−/−) mice to determine if neuropathology in respiratory motor regions has an early onset. Periodic acid-Schiff (PAS) staining indicated glycogen accumulation was exclusively occurring in Gaa−/− hypoglossal, mid-cervical and upper thoracic motoneurons. Markers of DNA damage (Tunel) and ongoing apoptosis (Cleaved Caspase 3) did not co-localize with PAS staining, but were prominent in a medullary region which included the nucleus tractus solitarius, and also in the thoracic spinal dorsal horn. We conclude that respiratory-related motoneurons are particularly susceptible to GAA deficiency and that neuronal glycogen accumulation and neurodegeneration may occur independently in early stage disease. The data support early therapeutic intervention in Pompe disease. PMID:26921786

  20. Dynamic expression of neurotrophic factor receptors in postnatal spinal motoneurons and in mouse model of ALS.

    PubMed

    Zhang, Jiasheng; Huang, Eric J

    2006-07-01

    Neurotrophic factors support the survival of spinal motoneurons (MNs) and have been considered as strong candidates for treating motoneuron diseases. However, it is unclear if the right combination of neurotrophic factor receptors is present in postnatal spinal MNs. In this study, we show that the level of c-ret expression remains relatively stable in embryonic and postnatal spinal MNs. In contrast, the mRNA and protein of GFRalpha1 and -2 are progressively down-regulated in postnatal life. By 3 and 6 months of age, both receptors are barely detectable in spinal MNs. The down-regulation of GFRalpha1 appears accelerated in transgenic mice expressing mutant SOD1(G93A). Despite the progressive loss of GFRalpha1 and -2, phosphorylation of c-ret shows no detectable reduction on tyrosine residues or on serine 696. In addition to the GFRalpha subunits, expression of TrkB also shows a dynamic change. During embryogenesis, there is twice as much full-length TrkB as the truncated TrkB isoform. However, this ratio is reversed in postnatal spinal cord. Expression of the mutant SOD1(G93A) appears to have no effect on the TrkB receptor ratio. Taken together, our data indicate that the expression of neurotrophic factor receptors, GFRalpha1, -2, and TrkB, is not static, but undergoes dynamic changes in postnatal spinal MNs. These results provide insights into the use of neurotrophic factors as therapeutic agents for ALS.

  1. Motoneuron model of self-sustained firing after spinal cord injury

    PubMed Central

    Kurian, Mini; Jung, Ranu

    2016-01-01

    Under many conditions spinal motoneurons produce plateau potentials, resulting in self-sustained firing and providing a mechanism for translating short-lasting synaptic inputs into long-lasting motor output. During the acute-stage of spinal cord injury (SCI), the endogenous ability to generate plateaus is lost; however, during the chronic-stage of SCI, plateau potentials reappear with prolonged self-sustained firing that has been implicated in the development of spasticity. In this work, we extend previous modeling studies to systematically investigate the mechanisms underlying the generation of plateau potentials in motoneurons, including the influences of specific ionic currents, the morphological characteristics of the soma and dendrite, and the interactions between persistent inward currents and synaptic input. In particular, the goal of these computational studies is to explore the possible interactions between morphological and electrophysiological changes that occur after incomplete SCI. Model results predict that some of the morphological changes generally associated with the chronic-stage for some types of spinal cord injuries can cause a decrease in self-sustained firing. This and other computational results presented here suggest that the observed increases in self-sustained firing following some types of SCI may occur mainly due to changes in membrane conductances and changes in synaptic activity, particularly changes in the strength and timing of inhibition. PMID:21526348

  2. Extraarticular Supramalleolar Osteotomy for Managing Varus Ankle Osteoarthritis, Alternatives for Osteotomy: How and Why?

    PubMed

    Lee, Woo-Chun

    2016-03-01

    The supramalleolar osteotomy has been reported to be a joint preserving surgery with good clinical outcome for asymmetric ankle osteoarthritis, especially varus ankle osteoarthritis. Conventional supramalleolar osteotomy of the tibia and fibula creates angulation and translation of the ankle joint without changing the width of the ankle mortise. Distal tibial oblique osteotomy improved the preoperative clinical and radiological parameters; however, mean talar tilt angle did not decrease. Assessment of the ankle arthritis in sagittal, axial, and coronal planes may be helpful to achieve a decrease of the talar tilt in ankle osteoarthritis.

  3. The medial malleolus osteoligamentous complex and its role in ankle fractures.

    PubMed

    Davidovitch, Roy I; Egol, Kenneth A

    2009-01-01

    Ankle stability in ankle fractures is dependent on multiple factors. The medial malleolus and the associated deltoid ligament provide for ankle stability on the medial side. Over the years, the relative importance of this medial malleolar osteoligamentous complex (MMOLC) has been debated. This review will describe the evolution of ankle fracture surgery from the perspective of the contribution of the MMOLC to re-establishing ankle stability. Also discussed are the surgical and nonsurgical treatment options, various presentations of medial sided injuries in ankle fractures, and, finally, current recommendations for fixation.

  4. Functional instability in non-contact ankle ligament injuries

    PubMed Central

    Rose, A.; Lee, R.; Williams, R.; Thomson, L.; Forsyth, A.

    2000-01-01

    Objectives—To measure objectively functional standing balance in the acute stages of non-contact ankle sprain, and to compare patients with controls. Methods—A Chattanooga balance machine was used to measure postural stability in patients with acute ankle sprain and uninjured controls over a two week period, in one and two legged stance, with eyes open and closed. Participants also completed the Olerud and Molander questionnaire to provide a subjective measure of ankle function. Results—There was a highly significant improvement in questionnaire scores for the patients during the study period (p<0.0001). Patients appeared to be less stable than controls in all balance tests, although the difference did not reach significance. There was evidence of improvement over time in the number of tests successfully completed on the injured leg in single legged stance with eyes closed (p = 0.043) between visits 1 and 3. Conclusions—The patient group showed a subjective improvement, which supports clinical experience of treating acute ankle injuries. There is some evidence that on average the patient group appeared to be less stable than controls in all balance tests, although the difference did not reach statistical significance, even on the uninjured leg. There is a need to carry out further studies to confirm the results found in this pilot study and to investigate the hypotheses generated. It would be useful to evaluate a simple test that could be used clinically to monitor progress after ankle injury, and also to identify athletes with decreased functional stability, who may be more at risk of sustaining ankle injury. Key Words: balance; ankle; sprain; postural stability; injury prevention PMID:11049145

  5. Does ice immersion influence ankle joint position sense?

    PubMed

    Hopper, D; Whittington, D; Davies, J; Chartier, J D

    1997-01-01

    The purpose of this study was to determine whether a fifteen minute ice immersion treatment influenced the normal ankle joint position sense at 40% and 80% range of inversion and to establish the length of treatment effect through monitoring the rewarming process. Forty nine healthy volunteers between the ages of 17 and 28 were tested. Subjects were screened to exclude those with a history of ankle injuries. The subject's skin temperature over antero-lateral aspect of the ankle was measured using a thermocouple device during the fifteen minutes ice intervention and thirty minutes post-intervention. Testing of ankle joint position sense using the pedal goniometer was performed before and after a clinical application of ice immersion. The testing required the subject to actively reposition their ankle at 40% and 80% of their total range of inversion. The majority of subjects experienced numbness of the foot and ankle by the fifth or sixth minute during ice immersion. One minute after immersion skin temperatures averaged 15 degrees C + 1.7 degrees C. Skin temperature was seen to rise relatively rapidly for the first ten minutes and then slowed considerably. Subjects had not returned to the pre-test skin temperatures by thirty minutes. A significant difference in ankle joint position sense (p < 0.0499) following fifteen minutes of ice immersion was found. However, the magnitude of this difference (0.5 degree) would not be deemed significant in clinical practice. The research found no significant difference in joint position sense between 40% and 80% of the range of inversion both before and after cryotherapy. These findings suggest that the clinical application of cryotherapy is not deleterious to joint position sense and assuming normal joint integrity patients may resume exercise without increased risk of injury.

  6. Ultrastructural evidence for a direct excitatory pathway from the nucleus retroambiguus to lateral longissimus and quadratus lumborum motoneurons in the female golden hamster.

    PubMed

    Gerrits, Peter O; Mouton, Leonora J; de Weerd, Henk; Georgiadis, Janniko R; Krukerink, Marco; Holstege, Gert

    2004-12-20

    During mating, the female golden hamster displays a stereotyped specific receptive posture, characterized by lordosis of the back, elevation of the tail, and extension of the legs. Muscles involved in this posture are thought to be iliopsoas, cutaneus trunci, lateral longissimus (LL), and quadratus lumborum (QL). Lesion studies in rats suggest that mating behavior is controlled by the mesencephalic periaqueductal gray (PAG). The PAG does not project directly to the motoneurons innervating the muscles involved in mating, but is thought to make use of the nucleus retroambiguus (NRA) as relay. The NRA is located ventrolaterally in the most caudal medulla, and projects directly to iliopsoas and cutaneus trunci motoneuronal cell groups. The question is whether this is also true for LL and QL muscles. Retrograde HRP tracing experiments revealed that LL and QL motoneurons are located medially in the ventral horn of the T12-L6 and T13-L4 segments, respectively. A subsequent ultrastructural study combined wheatgerm agglutinin-conjugated horseradish peroxidase injections in the NRA with cholera-toxin B-subunit injections in LL and QL muscles. The results revealed monosynaptic contacts between anterogradely labeled NRA-fiber terminals with retrogradely labeled dendrites of both LL and QL motoneurons. Almost all these terminals had asymmetrical synapses and contained spherical vesicles, suggesting an excitatory function of this NRA-motoneuronal pathway. These results correspond with the hypothesis that in hamster the PAG-NRA-motoneuronal projection not only involves motoneurons of iliopsoas and cutaneus trunci but also of LL and QL.

  7. PTX-induced hyperexcitability affects dendritic shape and GABAergic synapse density but not synapse distribution during Manduca postembryonic motoneuron development.

    PubMed

    Meseke, Maurice; Evers, Jan Felix; Duch, Carsten

    2009-05-01

    During the metamorphosis of the holometabolous insect, Manduca sexta, the postembryonic acquisition of adult specific motor behaviors is accompanied by changes in dendritic architecture, membrane currents, and input synapses of identified motoneurons. This study aims to test whether increased activity affects dendritic architecture and sub-dendritic input synapse distribution of the identified flight motoneuron 5 (MN5). Systemic injections of the chloride channel blocker, picrotoxin (PTX), during early pupal stages increase pupal reflex responsiveness, but overall development is not impaired. MN5 input resistance, resting membrane potential, and spiking threshold are not affected. Bath application of PTX to isolated ventral nerve cords evokes spiking in pupal and adult flight motoneurons. Quantitative three-dimensional reconstructions of the dendritic tree of the adult MN5 show that systemic PTX injections into early pupae cause dendritic overgrowth and reduce the density of GABAergic inputs. In contrast, the distribution patterns of GABAergic terminals throughout the dendritic tree remain unaltered. This indicates that increased overall excitability might cause dendritic overgrowth and decreased inhibitory input during postembryonic motoneuron remodeling, whereas sub-dendritic synapse targeting might be controlled by activity-independent signals. Behavioral testing reveals that these neuronal changes do not impede the animal's ability to fly, but impair maximum flight performance.

  8. Selective Requirement for Maintenance of Synaptic Contacts onto Motoneurons by Target-Derived trkB Receptors.

    PubMed

    Zhu, Xiya; Ward, Patricia J; English, Arthur W

    2016-01-01

    Synaptic contacts onto motoneurons were studied in mice in which the gene for the trkB neurotrophin receptor was knocked out selectively in a subset of spinal motoneurons. The extent of contacts by structures immunoreactive for either of two different vesicular glutamate transporters (VGLUT1 and VGLUT2), the vesicular GABA transporter, or glutamic acid decarboxylase 67 (GAD67) with the somata of motoneurons, was studied in wild type and trkB knockout cells in tamoxifen treated male and female SLICK-trkB(-/-) mice. Selective knockout of the trkB gene resulted in a marked reduction in contacts made by VGLUT2- and GAD67-immunoreactive structures in both sexes and a significant reduction in contacts containing only glycine in male mice. No reduction was found for glycinergic contacts in female mice or for VGLUT1 immunoreactive contacts in either sex. Signaling through postsynaptic trkB receptors is considered to be an essential part of a cellular mechanism for maintaining the contacts of some, but not all, synaptic contacts onto motoneurons.

  9. The control of eye movements by the cerebellar nuclei: polysynaptic projections from the fastigial, interpositus posterior and dentate nuclei to lateral rectus motoneurons in primates.

    PubMed

    Prevosto, Vincent; Graf, Werner; Ugolini, Gabriella

    2017-02-22

    Premotor circuits driving extraocular motoneurons and downstream motor outputs of cerebellar nuclei are well known. However, there is, as yet, no unequivocal account of cerebellar output pathways controlling eye movements in primates. Using retrograde transneuronal transfer of rabies virus from the lateral rectus (LR) eye muscle, we studied polysynaptic pathways to LR motoneurons in primates. Injections were placed either into the central or distal muscle portion, to identify innervation differences of LR motoneurons supplying singly innervated (SIFs) or multiply innervated muscle fibers (MIFs). We found that SIF motoneurons receive major cerebellar 'output channels' bilaterally, while oligosynaptic cerebellar innervation of MIF motoneurons is negligible and/or more indirect. Inputs originate from the fastigial nuclei di- and trisynaptically, and from a circumscribed rostral portion of the ventrolateral interpositus posterior and from the caudal pole of the dentate nuclei trisynaptically. While disynaptic cerebellar inputs to LR motoneurons stem exclusively from the caudal fastigial region involved in saccades, pursuit and convergence (via its projections to brainstem oculomotor populations), minor trisynaptic inputs from the rostral fastigial nucleus, which contributes to gaze shifts, may reflect access to vestibular and reticular eye-head control pathways. Trisynaptic inputs to LR motoneurons from the rostral ventrolateral interpositus posterior, involved in divergence (far-response), is likely mediated by projections to the supraoculomotor area, contributing to LR motoneuron activation during divergence. Trisynaptic inputs to LR motoneurons from the caudal dentate, which also innervates disynaptically the frontal and parietal eye fields, can be explained by its superior colliculus projections, and likely target saccade-related burst neurons.

  10. Range of Motion of the Ankle According to Pushing Force, Gender and Knee Position

    PubMed Central

    Cho, Kang Hee; Lee, Hyunkeun

    2016-01-01

    Objective To investigate the difference of range of motion (ROM) of ankle according to pushing force, gender and knee position. Methods One hundred and twenty-eight healthy adults (55 men, 73 women) between the ages of 20 and 51, were included in the study. One examiner measured the passive range of motion (PROM) of ankle by Dualer IQ Inclinometers and Commander Muscle Testing. ROM of ankle dorsiflexion (DF) and plantarflexion (PF) according to change of pushing force and knee position were measured at prone position. Results There was significant correlation between ROM and pushing force, the more pushing force leads the more ROM at ankle DF and ankle PF. Knee flexion of 90° position showed low PF angle and high ankle DF angle, as compared to the at neutral position of knee joint. ROM of ankle DF for female was greater than for male, with no significant difference. ROM of ankle PF for female was greater than male regardless of the pushing force. Conclusion To our knowledge, this is the first study to assess the relationship between pushing force and ROM of ankle joint. There was significant correlation between ROM of ankle and pushing force. ROM of ankle PF for female estimated greater than male regardless of the pushing force and the number of measurement. The ROM of the ankle is measured differently according to the knee joint position. Pushing force, gender and knee joint position are required to be considered when measuring the ROM of ankle joint. PMID:27152277

  11. Total ankle replacement--evolution of the technology and future applications.

    PubMed

    Yu, John J; Sheskier, Steven

    2014-01-01

    Total ankle arthroplasty was developed to reduce pain and retain motion of the ankle joint in patients with osteoarthritis much like its total hip and knee counterparts. Orthopaedic surgeons are well equipped to evaluate and treat patients with end-stage hip or knee arthritis; however, the management of patients with ankle arthritis represents a challenge to both general orthopaedic surgeons and to the foot and ankle surgeons to whom these patients are often referred. Although techniques for both hip and knee arthroplasty have evolved to provide long-term pain relief and functional improvement, neither ankle arthrodesis nor arthroplasty has demonstrated comparably favorable outcomes in long-term follow-up studies. Early ankle arthroplasty designs with highly constrained cemented components were abandoned due to unacceptably high failure rates and complications. While arthrodesis is still considered the "gold standard" for treatment of end-stage ankle arthritis, progression of adjacent joint arthrosis and diminished gait efficiency has led to a resurgence of interest in ankle arthroplasty. Long-term outcome studies for total ankle replacement found excellent or good results in 82% of patients who received a newer generation ankle device compared with 72% if undergoing ankle fusion. Continued long-term follow-up studies are necessary, but total ankle arthroplasty has become a viable option for surgical treatment of ankle arthritis.

  12. The Effects of Kinesiotape Applied to the Lateral Aspect of the Ankle: Relevance to Ankle Sprains – A Systematic Review

    PubMed Central

    Wilson, Brendan; Bialocerkowski, Andrea

    2015-01-01

    Objective To identify, evaluate and synthesise evidence on the effect of kinesiotape applied to the lateral aspect of the ankle, through a systematic review of quantitative studies. Data Sources A search for quantitative studies was undertaken using key terms of “kinesiotape” and “ankle” in seven electronic databases, using the maximum date ranges. Databases included: the Cochrane Library, Cumulative Index to Nursing and Allied Health Literature, Medline, Physiotherapy Evidence Database, Scopus, SPORTDiscus and Web of Science. Study Selection Database hits were evaluated against explicit inclusion criteria. From 107 database hits, 8 quantitative studies were included. Data Extraction Two independent reviewers appraised the methodological rigour of the studies using the McMaster Critical Review Form for Quantitative Studies. Data were extracted on participant characteristics, kinesiotape parameters, comparison interventions, outcome measures and findings. Data Syntheses Most studies (n=7) had good to very good methodological rigour. Meta-analysis was not possible due to heterogeneity in participants, interventions and outcome measures. No adverse events were reported. Kinesiotape may produce different effects in healthy and injured ankles. In healthy ankles, kinesiotape may increase postural control, whereas in injured ankles it may improve proprioception, plantarflexor endurance and the performance of activities. These trends were identified from a small body of evidence including 276 participants. Conclusions It is recommended that kinesiotape may be used in clinical practice to prevent lateral ankle injuries (through its effects on postural control) and manage lateral ankle injuries due to its positive effects on proprioception, muscle endurance and activity performance. It appears that kinesiotape may not provide sufficient mechanical support to improve postural control in unstable ankles. Adverse events associated with kinseiotape are unlikely. PMID

  13. Immunohistochemical study of motoneurons in lumbar spinal cord of c57black/6 mice after 30-days space flight

    NASA Astrophysics Data System (ADS)

    Tyapkina, Oksana; Islamov, Rustem; Nurullin, Leniz; Petrov, Konstantin.; Rezvyakov, Pavel; Nikolsky, Evgeny

    To investigate mechanisms of hypogravity motor syndrome development the immunoexpression of heat shock proteins (Hsp27 and Hsp70), proteins of synaptic transmission (Synaptophysin and PSD95) and neuroprotective proteins (VEGF and Flt-1) in motoneurons of lumbar spinal cord in c57black/6 control mice (n=2) and after 30-days space flight (n=2) was studied. For a quantitative assessment of target proteins level in motoneurons frozen cross sections of lumbar spinal cord were underwent to immunohistochemical staining. Primary antibodies against VEGF, Flt-1, Hsp27 and Hsp70 (SantaCruz Biotechnology, inc. USA), against Synaptophysin and PSD95 (Abcam plc, UK) were visualized by streptavidin-biotin method. Images of spinal cords were received using OlympusBX51WI microscope with AxioCamMRm camera (CarlZeiss, Germany) and the AxioVisionRel. 4.6.3 software (CarlZeiss, Germany). The digitized data were analyzed using ImageJ 1.43 software (NIH, the USA). Quantitively, protein level in motoneurons was estimated by the density of immunoprecipitation. Results of research have not revealed any reliable changes in the immunnoexpression of vascular endothelial growth factor (VEGF) and its Flt-1 receptor in motoneurons of lumbar spinal cord in control and in mice after 30-day space flight. Studying of heat shock proteins, such as Hsp27 and Hsp70, revealed the decrease in level of these proteins immunoexpression in motoneurons of mice from flight group by 15% and 10%, respectively. Some decrease in level of immunnoexpression of presynaptic membrane proteins (synaptophysin, by 21%) and proteins of postsynaptic area (PSD95, by 55%) was observed after space flight. The data obtained testify to possible changes in a functional state (synaptic activity and stress resistance) of motoneurons of lumbar spinal cord in mice after space flight. Thus, we obtained new data on involvement of motoneurons innervating skeletal muscles in development of hypogravity motor syndrome. Research was supported

  14. Ankle arthrodesis: A systematic approach and review of the literature

    PubMed Central

    Yasui, Youichi; Hannon, Charles P; Seow, Dexter; Kennedy, John G

    2016-01-01

    Ankle arthrodesis is a common treatment used for patients with end-stage ankle arthritis (ESAA). The surgical goal of ankle arthrodesis is to obtain bony union between the tibia and talus with adequate alignment [slight valgus (0°-5°)], neutral dorsiflexion, and slight external rotation positions) in order to provide a pain-free plantigrade foot for weightbearing activities. There are many variations in operative technique including deferring approaches (open or arthroscopic) and differing fixation methods (internal or external fixation). Each technique has its advantage and disadvantages. Success of ankle arthrodesis can be dependent on several factors, including patient selection, surgeons’ skills, patient comorbidities, operative care, etc. However, from our experience, the majority of ESAA patients obtain successful clinical outcomes. This review aims to outline the indications and goals of arthrodesis for treatment of ESAA and discuss both open and arthroscopic ankle arthrodesis. A systematic step by step operative technique guide is presented for both the arthroscopic and open approaches including a postoperative protocol. We review the current evidence supporting each approach. The review finishes with a report of the most recent evidence of outcomes after both approaches and concerns regarding the development of hindfoot arthritis. PMID:27900266

  15. Ankle arthrodesis: A systematic approach and review of the literature.

    PubMed

    Yasui, Youichi; Hannon, Charles P; Seow, Dexter; Kennedy, John G

    2016-11-18

    Ankle arthrodesis is a common treatment used for patients with end-stage ankle arthritis (ESAA). The surgical goal of ankle arthrodesis is to obtain bony union between the tibia and talus with adequate alignment [slight valgus (0°-5°)], neutral dorsiflexion, and slight external rotation positions) in order to provide a pain-free plantigrade foot for weightbearing activities. There are many variations in operative technique including deferring approaches (open or arthroscopic) and differing fixation methods (internal or external fixation). Each technique has its advantage and disadvantages. Success of ankle arthrodesis can be dependent on several factors, including patient selection, surgeons' skills, patient comorbidities, operative care, etc. However, from our experience, the majority of ESAA patients obtain successful clinical outcomes. This review aims to outline the indications and goals of arthrodesis for treatment of ESAA and discuss both open and arthroscopic ankle arthrodesis. A systematic step by step operative technique guide is presented for both the arthroscopic and open approaches including a postoperative protocol. We review the current evidence supporting each approach. The review finishes with a report of the most recent evidence of outcomes after both approaches and concerns regarding the development of hindfoot arthritis.

  16. Adaptation to walking with an exoskeleton that assists ankle extension.

    PubMed

    Galle, S; Malcolm, P; Derave, W; De Clercq, D

    2013-07-01

    The goal of this study was to investigate adaptation to walking with bilateral ankle-foot exoskeletons with kinematic control that assisted ankle extension during push-off. We hypothesized that subjects would show a neuromotor and metabolic adaptation during a 24min walking trial with a powered exoskeleton. Nine female subjects walked on a treadmill at 1.36±0.04ms(-1) during 24min with a powered exoskeleton and 4min with an unpowered exoskeleton. Subjects showed a metabolic adaptation after 18.5±5.0min, followed by an adapted period. Metabolic cost, electromyography and kinematics were compared between the unpowered condition, the beginning of the adaptation and the adapted period. In the beginning of the adaptation (4min), a reduction in metabolic cost of 9% was found compared to the unpowered condition. This reduction was accompanied by reduced muscular activity in the plantarflexor muscles, as the powered exoskeleton delivered part of the necessary ankle extension moment. During the adaptation this metabolic reduction further increased to 16%, notwithstanding a constant exoskeleton assistance. This increased reduction is the result of a neuromotor adaptation in which subjects adapt to walking with the exoskeleton, thereby reducing muscular activity in all leg muscles. Because of the fast adaptation and the significant reductions in metabolic cost we want to highlight the potential of an ankle-foot exoskeleton with kinematic control that assists ankle extension during push-off.

  17. Diagnosing, planning and evaluating osteochondral ankle defects with imaging modalities

    PubMed Central

    van Bergen, Christiaan JA; Gerards, Rogier M; Opdam, Kim TM; Terra, Maaike P; Kerkhoffs, Gino MMJ

    2015-01-01

    This current concepts review outlines the role of different imaging modalities in the diagnosis, preoperative planning, and follow-up of osteochondral ankle defects. An osteochondral ankle defect involves the articular cartilage and subchondral bone (usually of the talus) and is mostly caused by an ankle supination trauma. Conventional radiographs are useful as an initial imaging tool in the diagnostic process, but have only moderate sensitivity for the detection of osteochondral defects. Computed tomography (CT) and magnetic resonance imaging (MRI) are more accurate imaging modalities. Recently, ultrasonography and single photon emission CT have been described for the evaluation of osteochondral talar defects. CT is the most valuable modality for assessing the exact location and size of bony lesions. Cartilage and subchondral bone damage can be visualized using MRI, but the defect size tends to be overestimated due to bone edema. CT with the ankle in full plantar flexion has been shown a reliable tool for preoperative planning of the surgical approach. Postoperative imaging is useful for objective assessment of repair tissue or degenerative changes of the ankle joint. Plain radiography, CT and MRI have been used in outcome studies, and different scoring systems are available. PMID:26716090

  18. Ankle injury mechanisms: lessons learned from cadaveric studies.

    PubMed

    Funk, James R

    2011-04-01

    The biomechanics of ankle injury have been studied extensively, primarily through mechanical testing of human cadavers. Cadaveric testing is an invaluable methodology in biomechanics, because the magnitude and direction of the loading can be measured precisely and correlated with the resulting injury pattern. Clinical and epidemiological studies provide useful descriptions of injury patterns that occur in the real world, but their retrospective nature precludes a definitive analysis of the forces that caused the injury. Understanding the mechanism of ankle injuries is essential for developing countermeasures to prevent injury and for reconstructing injurious events. Knowledge of an injury's mechanism can also suggest potential associated injuries, which is helpful in diagnosis and treatment. The purpose of this review is to summarize the published research on ankle injury mechanisms with an emphasis on biomechanical experiments on human cadavers. Injury patterns are described based on the principal axis of force or torque producing the injury in conjunction with off-axis forces and out-of-plane foot positions. A mechanistic description of ankle injuries is complicated by the fact that the same mechanism can sometimes produce different injuries and the same injury can sometimes be caused by multiple mechanisms. Nonetheless, a framework for relating injury mechanisms and injury patterns is a valuable tool in the understanding, prevention, and treatment of ankle injuries.

  19. Total ankle arthroplasty with severe preoperative varus deformity.

    PubMed

    Hanselman, Andrew E; Powell, Brian D; Santrock, Robert D

    2015-04-01

    Advancements in total ankle arthroplasty (TAA) over the past several decades have led to improved patient outcomes and implant survivorship. Despite these innovations, many implant manufacturers still consider a preoperative coronal plane deformity greater than 10° a relative contraindication to TAA. Without proper intraoperative alignment, these implants may experience abnormal wear and hardware failure. Correcting these deformities, often through the use of soft tissue procedures and/or osteotomies, not only increases the difficulty of a case, but also the intraoperative time and radiation exposure. The authors report a case in which a 54-year-old man with a severe right ankle varus deformity of 29° underwent successful TAA using the INBONE II Prophecy total ankle system (Wright Medical Technology, Inc, Memphis, Tennessee) and additional soft tissue reconstruction. Intraoperatively, the patient's coronal deformity was corrected to 1.8°. At 8 months postoperatively, the patient ambulated without restriction and had substantial improvement in validated patient outcome scores, specifically the Academy of Orthopaedic Surgeons Foot and Ankle Module and the Short Form Health Survey-12 This unique report documents the first time that this particular implant, with an exclusive preoperative computed tomography-derived patient-specific guide, has been used effectively for a severe preoperative varus deformity greater than 20° without the need for an osteotomy. Future studies should be directed toward the prospective evaluation of different total ankle implant systems and their outcomes with severe coronal plane deformity, specifically computed tomography-derived patient-specific guided implants.

  20. [Arthrodesis versus total joint replacement of the ankle].

    PubMed

    Mittlmeier, T

    2013-06-01

    In general, for the treatment of end-stage osteoarthritis of the ankle joint arthrodesis is considered to be the gold standard based on its versatility and eligibility for numerous indications. Nowadays, total ankle arthroplasty represents a viable alternative to ankle arthrodesis taking into account distinct premises as both procedures provide a calculable reduction of the preoperative pain level and a comparable functional gain. Furthermore, current 10-year-survival rates of total ankle replacement are reported to range between 76 % and 89 %. Revision rates of up to 10 % for both techniques have been reported with manifest differences within the respective spectrum of complications. Due to the fact that more than two thirds of patients suffer from post-traumatic osteoarthritis with a relatively low average of age concomitant malalignment, soft tissue damage or instability may frequently occur. A restoration of anatomic axes and an adequate centering of the talus under the tibia appear to be crucial for the outcome as well as an adequate soft tissue balancing, in particular in total ankle replacement. Thus, the selection of the correct indication and the right choice of treatment on the basis of complete preoperative diagnostics considering necessary additive surgical measures are of paramount importance for the final outcome.

  1. Diagnosing deltoid injury in ankle fractures: the gravity stress view.

    PubMed

    Michelson, J D; Varner, K E; Checcone, M

    2001-06-01

    In the lateral malleolar ankle fracture without talar shift there is much uncertainty regarding the diagnosis of deltoid ligament injury severe enough to require surgical treatment. The current study evaluated the mechanical integrity of the ankle using a novel gravity-stress mortise radiographic view, which is practical for clinical use. Eight cadaveric lower extremities were tested under the following conditions: (1) intact ankle, (2) distal fibular oblique osteotomy, (3) plated fibula after osteotomy, (4) transection of the superficial deltoid with fibula osteotomized or plated, and (5) all possible combinations of deep deltoid transection with superficial deltoid transected or repaired and fibula osteotomized or plated. For each condition, a mortise radiograph was taken of the specimen while it was mounted horizontally, lateral side down. Fibular osteotomy with or without transection of the superficial deltoid did not alter the mortise radiograph appearance of the ankles. With combined deep and superficial deltoid transection and fibular osteotomy, the talus always (eight of eight specimens) showed a lateral shift of 2 mm or greater and a valgus tilt of 15 degrees or more. The gravity stress view of the ankle was found to reproducibly document destabilizing deltoid ligament damage.

  2. Is Hardware Removal Recommended after Ankle Fracture Repair?

    PubMed Central

    Jung, Hong-Geun; Kim, Jin-Il; Park, Jae-Yong; Park, Jong-Tae; Eom, Joon-Sang

    2016-01-01

    The indications and clinical necessity for routine hardware removal after treating ankle or distal tibia fracture with open reduction and internal fixation are disputed even when hardware-related pain is insignificant. Thus, we determined the clinical effects of routine hardware removal irrespective of the degree of hardware-related pain, especially in the perspective of patients' daily activities. This study was conducted on 80 consecutive cases (78 patients) treated by surgery and hardware removal after bony union. There were 56 ankle and 24 distal tibia fractures. The hardware-related pain, ankle joint stiffness, discomfort on ambulation, and patient satisfaction were evaluated before and at least 6 months after hardware removal. Pain score before hardware removal was 3.4 (range 0 to 6) and decreased to 1.3 (range 0 to 6) after removal. 58 (72.5%) patients experienced improved ankle stiffness and 65 (81.3%) less discomfort while walking on uneven ground and 63 (80.8%) patients were satisfied with hardware removal. These results suggest that routine hardware removal after ankle or distal tibia fracture could ameliorate hardware-related pain and improves daily activities and patient satisfaction even when the hardware-related pain is minimal. PMID:27819005

  3. The reduction in human motoneurone responsiveness during muscle fatigue is not prevented by increased muscle spindle discharge.

    PubMed

    McNeil, Chris J; Giesebrecht, Sabine; Khan, Serajul I; Gandevia, Simon C; Taylor, Janet L

    2011-08-01

    Motoneurone excitability is rapidly and profoundly reduced during a sustained maximal voluntary contraction (MVC) when tested in the transient silent period which follows transcranial magnetic stimulation (TMS) of the motor cortex. One possible cause of this reduction in excitability is a fatigue-induced withdrawal of excitatory input to motoneurones from muscle spindle afferents. We aimed to test if muscle spindle input produced by tendon vibration would ameliorate suppression of the cervicomedullary motor-evoked potential (CMEP) in the silent period during a sustained MVC. Seven subjects performed a 2 min MVC of the elbow flexors. Stimulation of the corticospinal tract at the level of the mastoids was preceded 100 ms earlier by TMS. These stimulus pairs were delivered every 10 s during the 2 min MVC. Stimulus pairs at 30, 50, 70, 90 and 110 s were delivered while vibration (-80 Hz) was applied to the distal tendon of biceps. On a separate day, the protocol was repeated with both stimuli delivered to the motor cortex. The CMEP in the silent period decreased rapidly with fatigue (to -9% of control) and was not affected by tendon vibration (P = 0.766). The motor-evoked potential in the silent period also declined rapidly (to -5% of control) and was similarly unaffected by tendon vibration (P = 0.075). These data suggest motoneurone disfacilitation due to a fatigue-related decrease of muscle spindle discharge does not contribute significantly to the profound suppression of motoneurone excitability during the silent period. Therefore, a change to intrinsic motoneurone properties caused by repetitive discharge is most probably responsible.

  4. Glycinergic and GABA(A)-mediated inhibition of somatic motoneurons does not mediate rapid eye movement sleep motor atonia.

    PubMed

    Brooks, Patricia L; Peever, John H

    2008-04-02

    A hallmark of rapid eye movement (REM) sleep is a potent suppression of postural muscle tone. Motor control in REM sleep is unique because it is characterized by flurries of intermittent muscle twitches that punctuate muscle atonia. Because somatic motoneurons are bombarded by strychnine-sensitive IPSPs during REM sleep, it is assumed that glycinergic inhibition underlies REM atonia. However, it has never been determined whether glycinergic inhibition of motoneurons is indeed responsible for triggering the loss of postural muscle tone during REM sleep. Therefore, we used reverse microdialysis, electrophysiology, and pharmacological and histological methods to determine whether glycinergic and/or GABA(A)-mediated neurotransmission at the trigeminal motor pool mediates masseter muscle atonia during REM sleep in rats. By antagonizing glycine and GABA(A) receptors on trigeminal motoneurons, we unmasked a tonic glycinergic/GABAergic drive at the trigeminal motor pool during waking and non-rapid eye movement (NREM) sleep. Blockade of this drive potently increased masseter muscle tone during both waking and NREM sleep. This glycinergic/GABAergic drive was immediately switched-off and converted into a phasic glycinergic drive during REM sleep. Blockade of this phasic drive potently provoked muscle twitch activity in REM sleep; however, it did not prevent or reverse REM atonia. Muscle atonia in REM even persisted when glycine and GABA(A) receptors were simultaneously antagonized and trigeminal motoneurons were directly activated by glutamatergic excitation, indicating that a powerful, yet unidentified, inhibitory mechanism overrides motoneuron excitation during REM sleep. Our data refute the prevailing hypothesis that REM atonia is caused by glycinergic inhibition. The inhibitory mechanism mediating REM atonia therefore requires reevaluation.

  5. Retrograde response in axotomized motoneurons: nitric oxide as a key player in triggering reversion toward a dedifferentiated phenotype.

    PubMed

    González-Forero, D; Moreno-López, B

    2014-12-26

    The adult brain retains a considerable capacity to functionally reorganize its circuits, which mainly relies on the prevalence of three basic processes that confer plastic potential: synaptic plasticity, plastic changes in intrinsic excitability and, in certain central nervous system (CNS) regions, also neurogenesis. Experimental models of peripheral nerve injury have provided a useful paradigm for studying injury-induced mechanisms of central plasticity. In particular, axotomy of somatic motoneurons triggers a robust retrograde reaction in the CNS, characterized by the expression of plastic changes affecting motoneurons, their synaptic inputs and surrounding glia. Axotomized motoneurons undergo a reprograming of their gene expression and biosynthetic machineries which produce cell components required for axonal regrowth and lead them to resume a functionally dedifferentiated phenotype characterized by the removal of afferent synaptic contacts, atrophy of dendritic arbors and an enhanced somato-dendritic excitability. Although experimental research has provided valuable clues to unravel many basic aspects of this central response, we are still lacking detailed information on the cellular/molecular mechanisms underlying its expression. It becomes clear, however, that the state-switch must be orchestrated by motoneuron-derived signals produced under the direction of the re-activated growth program. Our group has identified the highly reactive gas nitric oxide (NO) as one of these signals, by providing robust evidence for its key role to induce synapse elimination and increases in intrinsic excitability following motor axon damage. We have elucidated operational principles of the NO-triggered downstream transduction pathways mediating each of these changes. Our findings further demonstrate that de novo NO synthesis is not only "necessary" but also "sufficient" to promote the expression of at least some of the features that reflect reversion toward a dedifferentiated

  6. 78 FR 68908 - Agency Information Collection (Ankle Conditions Disability Benefits Questionnaire) Under OMB Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-15

    ... AFFAIRS Agency Information Collection (Ankle Conditions Disability Benefits Questionnaire) Under OMB... Questionnaire)'' in any correspondence. FOR FURTHER INFORMATION CONTACT: Crystal Rennie, Enterprise Records... Disability Benefits Questionnaire)''. SUPPLEMENTARY INFORMATION: Title: Ankle Conditions Disability...

  7. 78 FR 34708 - Proposed Information Collection (Ankle Conditions Disability Benefits Questionnaire) Activity...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-10

    ... AFFAIRS Proposed Information Collection (Ankle Conditions Disability Benefits Questionnaire) Activity... Control No. 2900--NEW (Ankle Conditions Disability Benefits Questionnaire)'' in any correspondence. During... Conditions Disability Benefits Questionnaire, VA Form 21-0960M-2. OMB Control Number: 2900--NEW...

  8. Assessment of AK (Above Knee) Prosthesis with Different Ankle Assembly Using GRF Pattern in Stance Phase

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Min; Kim, Sung-Jae; Bae, Ha-Suk

    In this study, ground reaction force (GRF), absolute symmetry index (ASI) and coefficient of variation (CV) of fixed, single-axis and multi-axis prosthetic ankle assemblies were investigated by biomechanical evaluation of above knee amputees. In the experiments, 37 normal male volunteers, two male and two female Above Knee (AK) amputees GRF data were tested with fixed, single-axis and multi-axis prosthetic ankle assembly. A gait analysis was carried out to derive the ratio of GRF to weight as the percentage of total stance phase for ten points. The results showed that fixed-axis ankle assembly was superior to other two ankle assemblies for forwarding and braking forces. Multi-axis ankle was relatively superior to other two ankle assemblies for gait balancing and movement of the mass center. Single-axis ankle was relatively superior to the other two ankle assemblies for CV and ASI of GRF.

  9. Modeling and stress analyses of a normal foot-ankle and a prosthetic foot-ankle complex.

    PubMed

    Ozen, Mustafa; Sayman, Onur; Havitcioglu, Hasan

    2013-01-01

    Total ankle replacement (TAR) is a relatively new concept and is becoming more popular for treatment of ankle arthritis and fractures. Because of the high costs and difficulties of experimental studies, the developments of TAR prostheses are progressing very slowly. For this reason, the medical imaging techniques such as CT, and MR have become more and more useful. The finite element method (FEM) is a widely used technique to estimate the mechanical behaviors of materials and structures in engineering applications. FEM has also been increasingly applied to biomechanical analyses of human bones, tissues and organs, thanks to the development of both the computing capabilities and the medical imaging techniques. 3-D finite element models of the human foot and ankle from reconstruction of MR and CT images have been investigated by some authors. In this study, data of geometries (used in modeling) of a normal and a prosthetic foot and ankle were obtained from a 3D reconstruction of CT images. The segmentation software, MIMICS was used to generate the 3D images of the bony structures, soft tissues and components of prosthesis of normal and prosthetic ankle-foot complex. Except the spaces between the adjacent surface of the phalanges fused, metatarsals, cuneiforms, cuboid, navicular, talus and calcaneus bones, soft tissues and components of prosthesis were independently developed to form foot and ankle complex. SOLIDWORKS program was used to form the boundary surfaces of all model components and then the solid models were obtained from these boundary surfaces. Finite element analyses software, ABAQUS was used to perform the numerical stress analyses of these models for balanced standing position. Plantar pressure and von Mises stress distributions of the normal and prosthetic ankles were compared with each other. There was a peak pressure increase at the 4th metatarsal, first metatarsal and talus bones and a decrease at the intermediate cuneiform and calcaneus bones, in

  10. Membrane currents in visually identified motoneurones of neonatal rat spinal cord.

    PubMed Central

    Takahashi, T

    1990-01-01

    1. Ionic currents induced by depolarization of motoneurones were analysed by tight-seal, whole-cell recording in thin slices of neonatal rat lumbar spinal cord. Identification of motoneurones viewed under Nomarski optics was confirmed by retrograde labelling with the fluorescent dye, Evans Blue. 2. Under whole-cell voltage clamp, depolarizing command pulses from a holding potential of about -70 mV evoked a fast inward current followed by an outward current. The former was suppressed either by lowering external Na+ concentration or by application of tetrodotoxin (TTX). The apparent dissociation constant of TTX was about 13 nM. 3. The outward current remaining after TTX application was activated by depolarization above -50 mV, showing marked outward rectification in the current-voltage relation. Outward tail currents reversed in polarity near the K+ equilibrium potential calculated from the external and pipette K+ concentrations. 4. When external Ca2+ was replaced by Mg2+, the outward K+ current was suppressed markedly and reversibly. Subtraction of current recorded in Ca2+-free-Mg2+ solution from that in control solution revealed a Ca2(+)-dependent K+ current, IK(Ca) with both a transient, IC, and a sustained component IAHP; its tail current lasted for several hundred milliseconds. 5. The sustained outward current observed in Ca2(+)-free-Mg2+ solution was largely suppressed by external application of tetraethylammonium chloride (30 mM), suggesting that it was mostly the delayed rectifier current, IK. In Ca2(+)-free-Mg2+ solution containing TEA and TTX, another transient outward current was observed, which was inactivated by depolarizing pre-pulses in a time- and voltage-dependent manner. The steady-state inactivation curve indicated 50% inactivation at about -77 mV. 4-Aminopyridine (4-AP, 4 mM) largely and reversibly suppressed this current, whereas it did not affect IK observed in the absence of TEA. It is suggested that the transient outward current corresponds to

  11. Activity-dependent depression of the recurrent discharge of human motoneurones after maximal voluntary contractions.

    PubMed

    Khan, Serajul I; Giesebrecht, Sabine; Gandevia, Simon C; Taylor, Janet L

    2012-10-01

    Despite maximal voluntary effort, the output of human motoneurone pools diminishes during fatigue. To assess motoneurone behaviour, we measured recurrent discharges evoked antidromically by supramaximal nerve stimulation after isometric maximal voluntary contractions (MVCs).They were measured as F-waves in the electromyographic activity (EMG). Supramaximal stimuli to the common peroneal and ulnar nerves evoked F-waves at rest before and after MVCs in tibialis anterior (TA) and abductor digit minimi (ADM), respectively. F-waves were depressed immediately after a sustained MVC. For TA, the size and time course of depression of the F-wave area (26 ± 13%; mean ± SD; P =0.007) and persistence (∼20%) were similar after a 10-s or 1-min MVC. For ADM, the decline in F-wave area (39.8 ± 19.6%; P <0.01) was similar after the two contractions but the decline in persistence (probability of occurrence) of the F-wave differed (14.6 ± 10.5% and 32.5 ± 17.1% after 10-s and 1-min MVCs respectively). Comparison of a very long (2-min) with a very short (2-s)MVC in ADM showed that the depression of F-wave area, as well as persistence, was greater after the longer contraction. This suggests, at least for ADM, that the depression is related to the duration of voluntary activity and that the decrease in F-waves could contribute to central fatigue. To examine whether changes in motor axon excitability caused the depression, we measured compound muscle action potentials (M-waves) to submaximal stimulation of the ulnar nerve after a 2-s and 2-min MVC. Submaximal M-waves were not depressed after a 2-s MVC. They were depressed by a 2-min MVC, but the time course of depression of the F- and M-waves differed. Thus, depression of F-waves does not simply reflect reduced excitability of peripheral motor axons.Hence, we propose that activity-dependent changes at the soma or the initial segment depress the recurrent discharge of human motoneurones and that this may contribute to central

  12. Distally based perforator sural flaps for foot and ankle reconstruction

    PubMed Central

    Chang, Shi-Min; Li, Xiao-Hua; Gu, Yu-Dong

    2015-01-01

    Distally based perforator sural flaps from the posterolateral or posteromedial lower leg aspect are initially a neurofasciocutaneous flap that can be transferred reversely to the foot and ankle region with no need to harvest and sacrifice the deep major artery. These flaps are supplied by a perforating artery issued from the deep peroneal artery or the posterior tibial artery, and the chain-linked adipofascial neurovascular axis around the sural/saphenous nerve. It is a versatile and reliable technique for soft-tissue reconstruction of the heel and ankle region with 180-degrees rotation. In this paper, we present its developing history, vascular basis, surgical techniques including flap design and elevation, flap variations in pedicle and component, surgical indications, and illustrative case reports with different perforating vessels as pivot points for foot and ankle coverage. PMID:25893175

  13. Salto Talaris fixed-bearing total ankle replacement system.

    PubMed

    Rush, Shannon M; Todd, Nicholas

    2013-01-01

    The Salto Talaris total ankle replacement is an anatomically designed fixed bearing prosthesis available in the United States based on the successful design of the mobile-bearing Salto prosthesis available outside the United States. The original mobile-bearing design was modified and the mobile-bearing was transferred to the precision instrumentation at the trial phase evaluation. Instrumentation and technique allow the surgeon to determine the functional joint axis before final implantation. The Salto Talaris total ankle replacement design blends minimal bone resection and optimizes surface area, cortical contact, and ultra-high molecular weight polyethylene conformity. The authors present an overview of the Salto Talaris total ankle replacement surgical technique and pearls for successful application.

  14. Depth of ankle inversion and discrimination of foot positions.

    PubMed

    Symes, Michael; Waddington, Gordon; Adams, Roger

    2010-10-01

    Ankle inversion injuries are common, yet little is known about the error associated with different positions as inversion depth increases. In this study, absolute judgments made without feedback were used to measure discrimination of different extents of ankle inversion which arose from active movements made to physical stops by 20 self-reported right side-dominant participants. Testing was conducted over three sets of five inversion depths that were within a range of 1.4 degrees and centered around mean depths of 8,11, and 14 degrees. Discrimination of ankle inversion movements decreased linearly with depths of movement further into inversion, both within and across the sets of inversion depths. Thus, error in assessing movement position increased with inversion depth. Inversion movements that were made with the left foot were significantly better discriminated at all depths than those made with the right foot.

  15. Fixation orientation in ankle fractures with syndesmosis injury.

    PubMed

    Nimick, Craig J; Collman, David R; Lagaay, Pieter

    2013-01-01

    Accurate reduction of the syndesmosis has been shown to be an important prognostic factor for functional outcome in ankle injuries that disrupt the syndesmosis. The purpose of the present case series was to assess the fixation orientation and the position of the fibula within the tibial incisura after open reduction and internal fixation of ankle fractures with syndesmosis injury. Computed tomography was used to assess the accuracy of the reduction. Twelve patients were included in the present case series. A ratio representing the relationship between the tibia and fibula and the orientation of the syndesmotic fixation was measured preoperatively and postoperatively and compared with the uninjured contralateral ankle, representing the patient's normal anatomy. The measurements were accomplished electronically to one tenth of 1 mm using Stentor Intelligent Informatics, I-site, version 3.3.1 (Phillips Electronics; Andover, MA). Posteriorly oriented syndesmotic fixation caused posterior translation of the fibula with respect to the tibia and anteriorly oriented syndesmotic fixation caused anterior translation.

  16. Engineering considerations in the design of an ankle joint.

    PubMed

    Kempson, G E; Freeman, M A; Tuke, M A

    1975-05-01

    A prothesis has been designed to replace the articulating surfaces of the human ankle joint. The prothesis is in two parts, each forming a segment of a right circular cylinder with a single axis of rotation. The concave tibial component is manufactured from ultra-high molecular weight polyethylene and the talar component is manufactured from medical grade stainless steel. It is likely, however, that the talar component will be commercially manufactured from cobalt chrome alloy (Vitallium or Vinertia). The two components are secured to the cancellous bone by polymethylmethacrylate bone cement and laboratory tests have indicated that the bond should be strong enough to withstand the loads encountered at the ankle joint in vivo. The tests have also shown that the stability and strength of the ankle are not seriously reduced by implantation of the prosthesis. Laboratory wear tests and clinical experience over the last two years encourage optimism over the long term performance of the prothesis.

  17. Altered Knee and Ankle Kinematics During Squatting in Those With Limited Weight-Bearing–Lunge Ankle-Dorsiflexion Range of Motion

    PubMed Central

    Dill, Karli E.; Begalle, Rebecca L.; Frank, Barnett S.; Zinder, Steven M.; Padua, Darin A.

    2014-01-01

    Context: Ankle-dorsiflexion (DF) range of motion (ROM) may influence movement variables that are known to affect anterior cruciate ligament loading, such as knee valgus and knee flexion. To our knowledge, researchers have not studied individuals with limited or normal ankle DF-ROM to investigate the relationship between those factors and the lower extremity movement patterns associated with anterior cruciate ligament injury. Objective: To determine, using 2 different measurement techniques, whether knee- and ankle-joint kinematics differ between participants with limited and normal ankle DF-ROM. Design: Cross-sectional study. Setting: Sports medicine research laboratory. Patients or Other Participants: Forty physically active adults (20 with limited ankle DF-ROM, 20 with normal ankle DF-ROM). Main Outcome Measure(s): Ankle DF-ROM was assessed using 2 techniques: (1) nonweight-bearing ankle DF-ROM with the knee straight, and (2) weight-bearing lunge (WBL). Knee flexion, knee valgus-varus, knee internal-external rotation, and ankle DF displacements were assessed during the overhead-squat, single-legged squat, and jump-landing tasks. Separate 1-way analyses of variance were performed to determine whether differences in knee- and ankle-joint kinematics existed between the normal and limited groups for each assessment. Results: We observed no differences between the normal and limited groups when classifying groups based on nonweight-bearing passive-ankle DF-ROM. However, individuals with greater ankle DF-ROM during the WBL displayed greater knee-flexion and ankle-DF displacement and peak knee flexion during the overhead-squat and single-legged squat tasks. In addition, those individuals also demonstrated greater knee-varus displacement during the single-legged squat. Conclusions: Greater ankle DF-ROM assessed during the WBL was associated with greater knee-flexion and ankle-DF displacement during both squatting tasks as well as greater knee-varus displacement during

  18. Perineural fibrosis of superficial peroneal nerve complicating ankle sprain: a case report.

    PubMed

    Acus, R W; Flanagan, J P

    1991-02-01

    The peroneal nerve is susceptible to traction injury during inversion ankle sprains. Previously, these traction lesions have been identified only at the fibular neck and popliteal fossa level. This report illustrates a previously unreported condition of perineural fibrosis of the superficial peroneal nerve at the level of the ankle following an inversion ankle sprain. Perineural fibrosis should be considered in the differential diagnosis of patients with persistent pain after ankle sprain.

  19. Effect of an Ankle Compression Garment on Fatigue and Performance.

    PubMed

    Šambaher, Nemanja; Aboodarda, Saied J; Silvey, Dustin B; Button, Duane C; Behm, David G

    2016-02-01

    The aim of this study was to examine the effects of an ankle compression garment (CG) on muscle performance and physiological variables associated with recovery from fatigue. Fifteen participants took part in a randomized crossover study design with 2 experimental conditions (ankle CG and control). The dependent variables skin temperature, evoked muscle contractile properties, maximal voluntary contraction (MVC) force, electromyography (EMG), drop jump performance (20, 35, and 50 cm box heights), continuous drop jump (30 cm), time to fatigue (TTF), and blood lactate concentration were measured pre- and post-warm-up and postfatigue. Compared with control condition, ankle CG condition had significantly reduced half-relaxation times (p = 0.043) and higher skin temperatures at post-warm-up and post-fatigue protocol (p < 0.001, Δ3.2 and Δ4%, respectively). Participants also exhibited significantly lower ground reaction forces (GRFs) for 50-cm drop jumps (p = 0.044, Δ9.9%) with ankle CG at post-warm-up. There were no significant differences between conditions for muscle contractile properties, MVC force or EMG, jump height, take-off velocity, contact time, and jumping TTF. Independent of group, there was a threefold increase in blood lactate (p < 0.01) from pre-warm-up to post-fatigue and a significant decrease in MVC force (p = 0.048, Δ8.1%) from post-warm-up to postfatigue. Results suggest that ankle CG increased and maintained skin temperature during recovery, decreased twitch half-relaxation times, and reduced GRF from a 50-cm drop height. However, ankle CG did not improve other performance measures, aid in recovery, or affect blood lactate clearance.

  20. Relationship between two proprioceptive measures and stiffness at the ankle.

    PubMed

    Docherty, Carrie L; Arnold, Brent L; Zinder, Steven M; Granata, Kevin; Gansneder, Bruce M

    2004-06-01

    Previous research has investigated the role of proprioception and stiffness in the control of joint stability. However, to date, no research has been done on the relationship between proprioception and stiffness. Therefore, the purpose of this study was to determine the relationship between force sense, joint reposition sense, and stiffness at the ankle. A heterogeneous sample was obtained for this study; 20 of the 40 participants had a history of ankle sprains, and 13 of the 20 had been diagnosed by a physician (two mild ankle sprains, seven moderate sprains, four severe sprains). All subjects were asymptomatic and active at the time of the study. Active joint reposition sense was measured using a custom-built ankle goniometer, force sense was measured unilaterally and contralaterally with a load cell, and ankle muscle stiffness was measured via transient oscillation using a custom-built inversion-eversion cradle. We found no significant correlations between stiffness and joint reposition sense, with values of r ranging from 0.01 to 0.21. Significant correlations were found between stiffness and force sense. Specifically, contralateral force sense reproduction was significantly correlated to stiffness in the injured or "involved" ankle (r's ranging from 0.47 to 0.65; P< or =0.008). Whether the decreased ability to appropriately sense force (increased error) sends information to the central nervous system to increase muscle stiffness in response to an unexpected loss of stability, or whether these two phenomena function independently and both change concurrently as a result of injury to the system requires further investigation.

  1. Neuromuscular problems in foot and ankle: evaluation and workup.

    PubMed

    Hunt, Kenneth J; Ryu, Jessica H

    2014-03-01

    It is essential to determine the functional goals of the patient during the workup and treatment planning stages of neuromuscular disorders involving the foot and ankle. Accurate diagnosis, and informed discussion of treatment options, must be in the context of the patient's disease, cognition, comorbidities, functional attributes, and family environment. A thorough history and physical examination aid in appropriate diagnostic workup and optimal orthopedic management of each patient. In this article, general considerations in the workup of suspected neuromuscular disorders and issues pertinent to specific congenital and acquired neuromuscular disorders affecting foot and ankle function are reviewed.

  2. Bosworth fracture-dislocation of the ankle: a case report.

    PubMed

    Yeoh, Ching Sing; Tan, Gek Meng Jeffrey

    2013-08-01

    Bosworth fracture-dislocation of the ankle is a rare injury in which the proximal fibular fragment is entrapped behind the tibia. Closed reduction is extremely difficult to achieve. Early open reduction and internal fixation enables a better outcome by minimising soft-tissue damage. We report on a 36-year-old man who underwent open reduction and internal fixation for a Bosworth fracture-dislocation of the ankle complicated by severe soft-tissue swelling and an impending risk of skin necrosis after failed closed reduction.

  3. Triceps surae contracture: implications for foot and ankle surgery.

    PubMed

    Abdulmassih, Sami; Phisitkul, Phinit; Femino, John E; Amendola, Annunziato

    2013-07-01

    Restricted ankle dorsiflexion secondary to contracture of the gastrocnemius-soleus complex is frequently encountered in patients with foot and ankle pain and is well documented in the literature. During gait, decreased dorsiflexion shifts weight-bearing pressures from the heel to the forefoot, which may result in or exacerbate one of several pathologic conditions. Modest success has been achieved with nonsurgical management of triceps surae contracture, including splinting and stretching exercises. Surgical lengthening of the gastrocnemius-soleus complex at multiple levels has been described, and early clinical results have been promising. Additional research is required to further elucidate the long-term outcomes of various lengthening techniques.

  4. 21 CFR 888.3100 - Ankle joint metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ankle joint metal/composite semi-constrained... Ankle joint metal/composite semi-constrained cemented prosthesis. (a) Identification. An ankle joint metal/composite semi-constrained cemented prosthesis is a device intended to be implanted to replace...

  5. 21 CFR 888.3100 - Ankle joint metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ankle joint metal/composite semi-constrained... Ankle joint metal/