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1

[Screw fixation of craniocervical junction].  

PubMed

In recent years an increase has been observed of the use of screw techniques for the fixation of the craniocervical junction. For clinical use two techniques have been introduced: (1) transarticular screw fixation, and (2) transpedicular screw fixation. In the former the screw is inserted through the C2 lateral mass, the fissure of the C1-C2 joint, and the C1 lateral mass. (2) in the latter the screw is inserted into the C2 pedicle and anchored in C2 vertebral body. Transarticular or pedicle screws can be easily connected to longitudinal elements such as rods or plates, and combined with lateral mass screws of the remaining cervical vertebrae or occipital screws. In comparison to sublaminar wiring or interlaminar clamping the screw techniques: (a) strengthen the stiffness of the construct and speed up fusion, (b) allow fixation in the absence or deficiency of laminae as a result of trauma or laminectomy, and (c) can selectively include only the affected segments. Increased construct stiffness is due to deep anchorage of the screw in bone providing thus a solid grip on the vertebra. Both techniques require preoperative assessment of the course of the vertebral artery using imaging methods. In about 18% of cases abnormal course of the artery precludes screw use. Pedicle screw insertion requires direct control of the medial and superior walls of C2 pedicle with dissector introduced into the vertebral canal, which requires removal of the atlantoaxial ligament. Additional control can be achieved with lateral fluoroscopy. The entry point for transarticular screw is on the lateral mass of the odontoid 2-3 mm laterally to the medial margin of C2 facet and 2-3 mm above the C1/C2 articular fissure. The screw trajectory is 0-10 degrees in horizontal plane and towards the anterior C1 tuberculum in sagittal plane. PMID:10791042

Maciejczak, A; Radek, A

1999-01-01

2

Axial loading cross screw fixation for the Austin bunionectomy.  

PubMed

The Austin procedure has become a common method of osteotomy for the correction of hallux abductovalgus when indicated. The V-type configuration is intrinsically stable but not without complications. One complication encountered is rotation and/or displacement of the capital fragment. We present the use of an axial loading screw in conjunction with a dorsally placed compression screw. The benefit to this technique lies in the orientation of the axial loading screw, because it is directed to resist the ground reactive forces while also providing a second point of fixation in a crossing screw design. In a head-to-head biomechanical comparison, we tested single dorsal screw fixation versus double screw fixation, including both the dorsal and the axial loading screws in 10 metatarsal Sawbones(®) (Pacific Research Laboratories Inc, Vashon, WA). Five metatarsals received single dorsal screw fixation and five received the dorsal screw and the additional axial loading screw. The metatarsals were analyzed on an Instron compression device for comparison; 100% of the single screw fixation osteotomies failed with compression at an average peak load of 205 N. Four of five axial loading double screw fixation osteotomies did not fail. This finding suggests that the addition of an axial loading screw providing cross screw orientation significantly increases the stability of the Austin osteotomy, ultimately decreasing the likelihood of displacement encountered in the surgical repair of hallux abductovalgus. PMID:21621434

Rigby, Ryan B; Fallat, Lawrence M; Kish, John P

2011-01-01

3

Cannulated screws for odontoid screw fixation and atlantoaxial transarticular screw fixation. Technical note.  

PubMed

Cannulated screw systems use thin Kirschner wires (K-wires) that have been drilled into the bone to direct screw trajectories accurately into small bone fragments. Use of the K-wires avoids overdrilling the pilot holes and allows fixation of adjacent bone fragments during screw insertion. Hollow tools and hollow screws are inserted into the bone over the K-wires. Cannulated screw fixation is useful in the cervical spine to stabilize odontoid fractures and to treat atlantoaxial instability. This report describes techniques for successful cannulated screw insertion and methods to minimize complications. Cannulated screws have several distinct advantages compared to noncannulated screws: 1) the K-wires guide the screw position into the bone; 2) the K-wire trajectory can be repositioned easily if the original trajectory was not ideal; 3) the K-wires allow continuous fixation of adjacent unstable bone fragments; and 4) the K-wires prevent migration of unstable bone fragments during screw insertion. Complications associated with the K-wire (breakage, repositioning, and advancement) can be minimized using precise operative techniques, a specialized tool system, and intraoperative fluoroscopic monitoring. A unique cannulated screw tool system was developed specifically for upper cervical fixation to allow percutaneous drilling using long tunneling devices, tissue sheaths, drill guides, and long K-wires. These tools allow delivery of cannulated fracture-fixation screws at a low angle to the spine through long soft-tissue trajectories. Cannulated screws have significant advantages compared to noncannulated screws for fixation of the unstable cervical spine. PMID:7490629

Dickman, C A; Foley, K T; Sonntag, V K; Smith, M M

1995-12-01

4

Additional Fixations for Sliding Hip Screws in Treating Unstable Pertrochanteric Femoral Fractures (AO Type 31-A2): Short-Term Clinical Results  

PubMed Central

Background To evaluate the utility of additional fixation methods and to suggest a method of reduction in the treatment of unstable pertrochanteric femur fractures with a sliding hip screw (SHS). Methods A retrospective study was performed on thirty patients with unstable pertrochanteric femur fractures, who were operated on with a SHS between September 2004 and September 2009 and were followed up for at least 6 months. The additional fixation devices were as follows; antirotation screw (21 cases), fixation of displaced fractures of the posteromedial bone fragment (cerclage wiring, 21 cases and screw, 2 cases) and trochanter stabilizing plate (27 cases). Clinically, the Palmer's mobility score and Jensen's social function group were used. Radiologically, alignment and displacement were observed. The tip-apex distance (TAD) and sliding of the lag screw were measured, and the position of the lag screw within the femoral head was also examined. Results The mean age at the time of surgery was 76 years (range, 56 to 89 years) and the average follow-up period was 25 months (range, 6 to 48 months). At the last follow-up, the average mobility and social function score was 6.2 (± 3.5) and 2.3 (± 1.5). Postoperatively, the alignment and displacement indices were adequate in almost all the cases. The mean amount of lag screw sliding and the mean TAD was 5.1 mm (range, 2 to 16 mm) and 6 mm (range, 3 to 11 mm) respectively. The lag screws were located in the center-center zone in 21 cases. The average period to union was 18.7 weeks without any cases of nonunion or malunion. Mechanical failure was noted in one case with breakage of the lag screw and clinical failure was noted in another case with persistent hip pain related to excessive sliding (16 mm). Conclusions With additional fixations, the unstable pertrochanteric femur fractures could be well stabilized by SHS until bone union.

Lee, Soo Ho; Cho, Hyung Lae; Ku, Jung Hoei; Choi, Jae Hyuk; Lee, Alex J

2011-01-01

5

Tricorrectional bunionectomy with AO screw fixation.  

PubMed

A 16-month preliminary study was performed on 58 patients for corrective surgery of hallux abducto valgus, with AO4 screw fixation. The procedure is a modification of the bi-plane Austin procedure, called a tricorrectional bunionectomy. The authors present the procedure with objective and subjective findings. The principles of bone healing and internal fixation using AO screw fixation are discussed. PMID:2625507

Boggs, S I; Selner, A J; Roth, I E; Bernstein, A L

1989-01-01

6

Does ischial screw fixation improve mechanical stability in revision total hip arthroplasty?  

PubMed

Ischial screw fixation, albeit technically challenging, is postulated to provide additional mechanical stability in revision total hip arthroplasty (THA). Hemipelvis specimens were prepared to simulate revision THA, and an acetabular component with supplemental screw fixation was implanted. Three configurations were tested: 2 dome screws alone, 2 dome screws plus an additional screw within the dome, and 2 dome screws plus an ischial screw. Force displacement data were acquired during mechanical testing. An increase in mechanical stability was observed in acetabular components with supplemental screw fixation into either the posterior column or ischium (P?.031) compared to isolated dome fixation. In addition, supplemental ischial screw fixation may provide a modest advantage over a screw placed posteroinferiorly within the acetabular dome during revision THA. PMID:19679432

Meneghini, R Michael; Stultz, Allison D; Watson, Jill S; Ziemba-Davis, Mary; Buckley, Christine A

2010-10-01

7

Complications of transpedicular screw fixation in the cervical spine.  

PubMed

Today, posterior stabilization of the cervical spine is most frequently performed by lateral mass screws or spinous process wiring. These techniques do not always provide sufficient stability, and anterior fusion procedures are added secondarily. Recently, transpedicular screw fixation of the cervical spine has been introduced to provide a one-stage stable posterior fixation. The aim of the present prospective study is to examine if cervical pedicle screw fixation can be done by low risk and to identify potential risk factors associated with this technique. All patients stabilized by cervical transpedicular screw fixation between 1999 and 2002 were included. Cervical disorders included multisegmental degenerative instability with cervical myelopathy in 16 patients, segmental instability caused by rheumatoid arthritis in three, trauma in five and instability caused by infection in two patients. In most cases additional decompression of the spinal cord and bone graft placement were performed. Pre-operative and post-operative CT-scans (2-mm cuts) and plain X-rays served to determine changes in alignment and the position of the screws. Clinical outcome was assessed in all cases. Ninety-four cervical pedicle screws were implanted in 26 patients, most frequently at the C3 (26 screws) and C4 levels (19 screws). Radiologically 66 screws (70%) were placed correctly (maximal breach 1 mm) whereas 20 screws (21%) were misplaced with reduction of mechanical strength, slight narrowing of the vertebral artery canal (<25%) or the lateral recess without compression of neural structures. However, these misplacements were asymptomatic in all cases. Another eight screws (9%) had a critical breach. Four of them showed a narrowing of the vertebral artery canal of more then 25%, in all cases without vascular problems. Three screws passed through the intervertebral foramen, causing temporary paresis in one case and a new sensory loss in another. In the latter patient revision surgery was performed. The screw was loosened and had to be corrected. The only statistically significant risk factor was the level of surgery: all critical breaches were seen from C3 to C5. Percutaneous application of the screws reduced the risk for misplacement, although this finding was not statistically significant. There was also a remarkable learning curve. Instrumentation with cervical transpedicular screws results in very stable fixation. However, with the use of new techniques like percutaneous screw application or computerized image guidance there remains a risk for damaging nerve roots or the vertebral artery. This technique should be reserved for highly selected patients with clear indications and to highly experienced spine surgeons. PMID:15912352

Kast, E; Mohr, K; Richter, H-P; Börm, W

2006-03-01

8

Hamstring tendon fixation using interference screws: a biomechanical study in calf tibial bone  

Microsoft Academic Search

It has recently been shown that graft fixation close to the ACL insertion site is optimal in order to increase anterior knee stability. Hamstring tendon fixation using interference screws offers this possibility and a round threaded titanium interference screw has been previously developed. The use of a round threaded biodegradable interference screw may be equivalent. In addition, to increase initial

A Weiler; RF Hoffmann; AC Stähelin; HJ Bail; CJ Siepe; NP Südkamp

1998-01-01

9

Minifragment screw fixation of oblique metacarpal fractures: a biomechanical analysis of screw types and techniques.  

PubMed

The lag screw technique has historically been a successful and accepted way to treat oblique metacarpal fractures. However, it does take additional time and involve multiple steps that can increase the risk of fracture propagation or comminution in the small hand bones of the hand. An alternate fixation technique uses bicortical interfragmentary screws. Other studies support the clinical effectiveness and ease of this technique. The purpose of this study is to biomechanically assess the strength of the bicortical interfragmentary screw versus that of the traditional lag screw. Using 48 cadaver metacarpals, oblique osteotomies were created and stabilized using one of four methods: 1.5 mm bicortical interfragmentary (IF) screw, 1.5 mm lag technique screw, 2.0 mm bicortical IF screw, or 2.0 mm lag technique screw. Biomechanical testing was performed to measure post cyclic displacement and load to failure. Data was analyzed using one-way analysis of variance (ANOVA). There was no significant difference among the fixation techniques with regard to both displacement and ultimate failure strength. There was a slight trend for a higher load to failure with the 2.0 mm IF screw and 2.0 mm lag screw compared to the 1.5 mm IF and 1.5 mm lag screws, but this was not significant. Our results support previously established clinical data that bicortical interfragmentary screw fixation is an effective treatment option for oblique metacarpal fractures. This technique has clinical importance because it is an option to appropriately stabilize the often small and difficult to control fracture fragments encountered in metacarpal fractures. PMID:18780019

Liporace, Frank A; Kinchelow, Tosca; Gupta, Salil; Kubiak, Erik N; McDonnell, Matthew

2008-12-01

10

Minifragment Screw Fixation of Oblique Metacarpal Fractures: A Biomechanical Analysis of Screw Types and Techniques  

PubMed Central

The lag screw technique has historically been a successful and accepted way to treat oblique metacarpal fractures. However, it does take additional time and involve multiple steps that can increase the risk of fracture propagation or comminution in the small hand bones of the hand. An alternate fixation technique uses bicortical interfragmentary screws. Other studies support the clinical effectiveness and ease of this technique. The purpose of this study is to biomechanically assess the strength of the bicortical interfragmentary screw versus that of the traditional lag screw. Using 48 cadaver metacarpals, oblique osteotomies were created and stabilized using one of four methods: 1.5 mm bicortical interfragmentary (IF) screw, 1.5 mm lag technique screw, 2.0 mm bicortical IF screw, or 2.0 mm lag technique screw. Biomechanical testing was performed to measure post cyclic displacement and load to failure. Data was analyzed using one-way analysis of variance (ANOVA). There was no significant difference among the fixation techniques with regard to both displacement and ultimate failure strength. There was a slight trend for a higher load to failure with the 2.0 mm IF screw and 2.0 mm lag screw compared to the 1.5 mm IF and 1.5 mm lag screws, but this was not significant. Our results support previously established clinical data that bicortical interfragmentary screw fixation is an effective treatment option for oblique metacarpal fractures. This technique has clinical importance because it is an option to appropriately stabilize the often small and difficult to control fracture fragments encountered in metacarpal fractures.

Liporace, Frank A.; Gupta, Salil; Kubiak, Erik N.; McDonnell, Matthew

2008-01-01

11

Strength comparison of allogenic bone screws, bioabsorbable screws, and stainless steel screw fixation.  

PubMed

Allogenic bone screws are new to the fixation market and have yet to be tested against current fixation materials. An in vitro comparison of the same sizes of stainless steel, bioabsorbable, and allogenic bone screws was undertaken to assess screw resistance to the forces of bending, pullout, and shear. Using aluminum plates to support the screws, forces up to 1000 Newtons were applied to six to eight samples of each type of screw. During each test, stainless steel screws withstood the maximum force that could be exerted by the testing apparatus without failing (bending, 113.9 +/- 11.8 N mean +/- SE; pullout 999.1 +/- 33.7 N; and shear, 997.5 +/- 108.8 N). In each test, compared to bioabsorbable screws, allogenic bone screws failed faster (pullout, allogenic: 12.4 +/- 1.1 seconds vs. bioabsorbable, 120.6 +/- 13.8 seconds; p = .001; bending, allogenic: 53.4 +/- 4.8 seconds vs. bioabsorbable, 201.9 +/- 11.1 seconds; p = .001; shear, allogenic 13.5 +/- 1.4 seconds vs. bioabsorbable, 43.8 +/- 0.9 seconds; p = .001) under equivalent (pullout: bioabsorbable, 385.0 +/- 18.4 N vs. allogenic, 401.0 +/- 35.9 N; p = .001) or lower (bending, allogenic: 4.7 +/- 0.2 N vs. bioabsorbable, 11.0 +/- 0.9 N; p = .675; shear, allogenic: 312.1 +/- 15.5 N vs. bioabsorbable 680.9 +/- 8.5 N; p = .001) loads, and in a highly variable fashion. Overall, the bioabsorbable screws withstood the forces of bending, pullout, and shear better than the allogenic screws, and stainless steel screws outperformed both bioabsorbable and allogenic screws. Despite these results, allogenic screws could still be useful in compliant patients who would benefit from their osteoconductive properties. PMID:11858609

Rano, James A; Savoy-Moore, Ruth T; Fallat, Lawrence M

2002-01-01

12

Self-tapping screw fixation of the Austin osteotomy.  

PubMed

The authors present an alternative method of fixation for the Austin bunionectomy using the Richards self-tapping screw. A description of the screw and method of application is included. In more than 250 osteotomies fixated by this technique, no complications inherent to the self-tapping screw have been encountered. PMID:2319102

Klein, M S; Ognibene, F A; Erali, R P; Hendrix, C L

1990-01-01

13

Thoracic pedicle screw fixation for spinal deformity.  

PubMed

Techniques to improve segmental fixation have advanced the ability to correct complex spinal deformity. The purpose of instrumentation is to correct spinal deformity or to stabilize the spine to enhance the long-term biological fusion. The ultimate goal of spinal deformity surgery is the creation of a stable, balanced, pain-free spine centered over the pelvis in the coronal and sagittal planes. The minimum number of segments should be fused. These concepts remain challenging in the setting of deformity and instability. Successful results can be obtained if the surgeon understands the technology available, its capabilities, biological limitations, and the desired solution. The authors prefer to use thoracic pedicle screws when treating patients with spinal deformity because they provide greater corrective forces for realignment. This allows shorter-segment constructs and the possibility of true derotation in correction. In this article the authors focus on the use of thoracic transpedicular screw fixation in the management of complex spinal disorders and deformity. PMID:15766224

Rosner, Michael K; Polly, David W; Kuklo, Timothy R; Ondra, Stephen L

2003-01-15

14

Treatment of Unstable Thoracolumbar Fractures through Short Segment Pedicle Screw Fixation Techniques Using Pedicle Fixation at the Level of the Fracture: A Finite Element Analysis  

PubMed Central

Objective To compare the von Mises stresses of the internal fixation devices among different short segment pedicle screw fixation techniques to treat thoracic 12 vertebral fractures, especially the mono-segment pedicle screw fixation and intermediate unilateral pedicle screw fixation techniques. Methods Finite element methods were utilised to investigate the biomechanical comparison of the four posterior short segment pedicle screw fixation techniques (S4+2: traditional short-segment 4 pedicle screw fixation [SPSF]; M4+2: mono-segment pedicle screw fixation; I6+2: intermediate bilateral pedicle screw fixation; and I5+2: intermediate unilateral pedicle screw fixation). Results The range of motion (ROM) in flexion, axial rotation, and lateral bending was the smallest in the I6+2 fixation model, followed by the I5+2 and S4+2 fixation models, but lateral bending was the largest in the M4+2 fixation model. The maximal stress of the upper pedicle screw is larger than the lower pedicle screw in S4+2 and M4+2. The largest maximal von Mises stress was observed in the upper pedicle screw in the S4+2 and M4+2 fixation models and in the lower pedicle screw in the I6+2 and I5+2 fixation models. The values of the largest maximal von Mises stress of the pedicle screws and rods during all states of motion were 263.1 MPa and 304.5 MPa in the S4+2 fixation model, 291.6 MPa and 340.5 MPa in the M4+2 fixation model, 182.9 MPa and 263.2 MPa in the I6+2 fixation model, and 269.3 MPa and 383.7 MPa in the I5+2 fixation model, respectively. Comparing the stress between different spinal loadings, the maximal von Mises stress of the implants were observed in flexion in all implanted models. Conclusion Additional bilateral pedicle screws at the level of the fracture to SPSF may result in a stiffer construct and less von Mises stress for pedicle screws and rods. The largest maximal von Mises stress of the pedicle screws during all states of motion were observed in the mono-segment pedicle screw fixation technique.

Li, Changqing; Zhou, Yue; Wang, Hongwei; Liu, Jun; Xiang, Liangbi

2014-01-01

15

Biodegradable Interference Screw Fixation Exhibits Pull-Out Force and Stiffness Similar to Titanium Screws  

Microsoft Academic Search

Recently, increased interest in biodegradable interference screws for bone-tendon-bone graft fixation has led to numerous screws becoming available. The implants are made from different polymers and have different designs, which might influence their mechanical properties. Several studies have reported a wide range of mechanical results for these screws using different biomechanical models. The aim of the present study is to

Andreas Weiler; Henning J. Windhagen; Michael J. Raschke; Andrea Laumeyer; Reinhard F. G. Hoffmann

1998-01-01

16

Intra-operative screw trimming in direct screw fixation of the odontoid process fracture — Technical note  

Microsoft Academic Search

Summary For a satisfactory direct screw fixation of fractures of the odontoid process it is necessary to use a screw of the proper total length and thread length, but such an optimal ready-made screw is not always available. The authors describe a technique of intra-operative screw trimming using a high-speed diamond drill. This adjustment is easily and quickly performed. It

T. Hasegawa; K. Yamano; Y. Hamada; T. Miyamori

1992-01-01

17

MR imaging for early complications of transpedicular screw fixation.  

PubMed

This series comprises ten patients treated with transpedicular screw fixation, who suffered early postoperative problems such as radicular pain or motor weakness. Besides plain radiographs, all patients were also evaluated with MR imaging. Three patients were reoperated for either repositioning or removal of the screws. MR images, especially T1-weighted ones, were very helpful for visualizing the problem and verifying the positions of the screws. In cases of wide areas of signal void around the screws, the neighboring axial MR images at either side, which have fewer artifacts, gave more information about the screws and the vertebrae. PMID:10333155

Colak, A; Kutlay, M; Demircan, N; Seçer, H I; Kibici, K; Ba?ekim, C

1999-01-01

18

Herbert bone screw fixation of the Austin bunionectomy.  

PubMed

This manuscript represents an alternative method of fixation for the Austin bunionectomy using the Herbert bone screw. A description of the modified Austin bunionectomy and fixation utilizing this system is presented. A discussion of potential and encountered complications is included. Two hundred and four osteotomies were fixated with the Herbert bone screw in 182 patients, with follow-up ranging from 6 months to 3 years. Early range of motion, rigid internal fixation with compression, and the elimination of pin tracks are the advantages of this method. PMID:3446706

Quinn, M R; DiStazio, J J; Kruljac, S J

1987-01-01

19

[Variations of transpedicular screw fixation and spinal dura opening].  

PubMed

The paper presents modified treatment protocols for spinal trauma and degenerative disease--transpedicular screw fixation based upon biomechanical adjustment and spinal dura opening. Both methods help to improve results of surgical treatment and decrease complication rate. PMID:23033595

Tumakaev, R F

2012-01-01

20

Fixation Strategies to Prevent Screw Cut-Out and Malreduction in Proximal Humeral Fracture Fixation  

PubMed Central

Fixation of proximal humerus fractures with precontoured, fixed angle devices has improved operative management of these difficult injuries, particularly in patients with osteoporosis. However, recent data has revealed that fixation with these constructs is not without complications, particularly screw cut-out and loss of reduction. Multiple strategies have been developed to decrease the number of complications. We offer a surgical technique combining suture augmentation of the proximal humerus with locked plate fixation utilizing short screws.

Namdari, Surena; Lipman, Adam J.; Ricchetti, Eric T.; Tjoumakaris, Fotios P.; Huffman, G. Russell

2012-01-01

21

Biomechanical Behaviour of Double Threaded Screw in Tibia Fixation  

Microsoft Academic Search

The aim of the work was assessment of stability of tibia fixation realized with the use of double threaded screw. Biomechanical\\u000a analysis of the tibia – double threaded screw system was carried our for the implant made of two biomaterials used in bone\\u000a surgery – Cr-Ni-Mo stainless steel and Ti-6Al-4V alloy. Finite element method was applied to calculate displacements, strains

Witold Walke; Jan Marciniak; Zbigniew Paszenda; Marcin Kaczmarek; Jerzy Cieplak

2008-01-01

22

Intramedullary screw fixation for midshaft fractures of the clavicle  

Microsoft Academic Search

Open intramedullary fixation of 37 fresh midshaft clavicular fractures in 35 patients was performed using a 6.5 partially\\u000a threaded cancellous screw. Mean age was 38 years (range 18–65). The screw was inserted from the medial fragment after retrograde\\u000a drilling of that fragment. Average follow-up period was 21 months (range 9–36). Radiological evidence of union was apparent\\u000a in all cases within six to

Ayman Khalil

2009-01-01

23

Modified Austin bunionectomy with single screw fixation: a comparison study.  

PubMed

The authors present a new modification of the Austin bunionectomy with single 2.7-mm. cortical screw fixation, and a comparison study with the standard osteotomy fixation using a single Kirschner wire. The results include subjective postoperative evaluation as well as objective radiographic analysis. Suggestions are made that this type of procedure is indeed a viable alternative in a large patient population suffering from hallux abducto valgus deformities. PMID:2794359

Clancy, J T; Berlin, S J; Giordano, M L; Sherman, S A

1989-01-01

24

Atlantoaxial fixation using the polyaxial screw-rod system  

PubMed Central

The aim of this study is to evaluate the first results of the atlantoaxial fixation using polyaxial screw–rod system. Twenty-eight patients followed-up 12–29 months (average 17.1 months) were included in this study. The average age was 59.5 years (range 23–89 years). The atlantoaxial fusion was employed in 20 patients for an acute injury to the upper cervical spine, in 1 patient with rheumatoid arthritis for atlantoaxial vertical instability, in 1 patient for C1–C2 osteoarthritis, in 2 patients for malunion of the fractured dens. Temporary fixation was applied in two patients for type III displaced fractures of the dens and in two patients for the atlantoaxial rotatory dislocation. Retrospectively, we evaluated operative time, intraoperative bleeding and the interval of X-ray exposure. The resulting condition was subjectively evaluated by patients. We evaluated also the placement, direction and length of the screws. Fusion or stability in the temporary fixation was evaluated on radiographs taken at 3, 6, 12 weeks and 6 and 12 months after the surgery. As concerns complications, intraoperatively we monitored injury of the nerve structures and the vertebral artery. Monitoring of postoperative complications was focused on delayed healing of the wound, breaking or loosening of screws and development of malunion. Operative time ranged from 35 to 155 min, (average 83 min). Intraoperative blood loss ranged from 50 to 1,500 ml (average 540 ml). The image intensifier was used for a period of 24 s to 2 min 36 s (average 1 min 6 s). Within the postoperative evaluation, four patients complained of paresthesia in the region innervated by the greater occipital nerve. A total of 56 screws were inserted into C1, their length ranged from 26 to 34 mm (average, 30.8 mm). All screws were positioned correctly in the C1 lateral mass. Another 56 screws were inserted into C2. Their length ranged from 28 to 36 mm (average 31.4 mm). Three screws were malpositioned: one screw perforated the spinal canal and two screws protruded into the vertebral artery canal. C1–C2 stability was achieved in all patients 12 weeks after the surgery. No clinically manifested injury of the vertebral artery or nerve structures was observed in any of these cases. As for postoperative complications, we recorded wound dehiscence in one patient. The Harms C1–C2 fixation is a very effective method of stabilizing the atlantoaxial complex. The possibility of a temporary fixation without damage to the atlantoaxial joints and of reduction after the screws and rods had been inserted is quite unique.

Vyskocil, Tomas; Sebesta, Petr; Kryl, Jan

2006-01-01

25

Accuracy and safety of free-hand pedicle screw fixation in age less than 10 years  

PubMed Central

Background: Pedicle screws are being used commonly in the treatment of various spinal disorders. However, use of pedicle screws in the pediatric population is not routinely recommended because of the risk of complications. The present study was to evaluate the safety of pedicle screws placed in children aged less than 10 years with spinal deformities and to determine the accuracy and complication (early and late) of pedicle screw placement using the postoperative computed tomography (CT) scans. Materials and Methods: Thirty one patients (11 males and 20 females) who underwent 261 pedicle screw fixations (177 in thoracic vertebrae and 84 in lumbar vertebrae) for a variety of pediatric spinal deformities at a single institution were included in the study. The average age of patients was 7 years and 10 months. These patients underwent postoperative CT scan which was assessed by two independent observers (spine surgeons) not involved in the treatment. Results: Breach rate was 5.4% (14/261 screws) for all pedicles. Of the 177 screws placed in the thoracic spine, 13 (7.3%) had breached the pedicle, that is 92.7% of the screws were accurately placed within pedicles. Seven screws (4%) had breached the medial pedicle wall, 4 screws (2.3%) had breached the lateral pedicle wall and 2 screws (1.1%) had breached the superior or inferior pedicle wall respectively. Of the 84 screws placed in the lumbar spine, 83 (98.8%) screws were accurately placed within the pedicle. Only 1 screw (1.2%) was found to be laterally displaced. In addition, the breach rate was found to be 4.2% (11/261 screws) with respect to the vertebral bodies. No neurological, vascular or visceral complications were encountered. Conclusions: The accuracy of pedicle screw placement in pedicles and vertebral bodies were 94.6% and 95.8% respectively and there was no complication related to screw placement noted until the last followup. These results suggest that free-hand pedicle screw fixation can be safely used in patients younger than 10 years to treat a variety of spinal disorders.

Seo, Hyoung Yeon; Yim, Ji Hyeon; Heo, Jung Pil; Patil, Abhishek S; Na, Seung Min; Kim, Sung Kyu; Chung, Jae Yoon

2013-01-01

26

Management of odontoid fractures with percutaneous anterior odontoid screw fixation  

PubMed Central

Minimally invasive techniques have revolutionized the management of a variety of spinal disorders. The authors of this study describe a new instrument and a percutaneous technique for anterior odontoid screw fixation, and evaluate its safety and efficacy in the treatment of patients with odontoid fractures. Ten patients (6 males and 4 females) with odontoid fractures were treated by percutaneous anterior odontoid screw fixation under fluoroscopic guidance from March 2000 to May 2002. Their mean age at presentation was 37.2 years (with a range from 21 to 55 years). Six cases were Type II and four were Type III classified by the Anderson and D’Alonzo system. The operation was successfully completed without technical difficulties, and without any soft tissue complications such as esophageal injury. No neurological deterioration occurred. Satisfactory results were achieved in all patients and all of the screws were in good placement. After a mean follow-up of 15.7 months (range 10–25 months), radiographic fusion was documented for 9 of 10 patients (90%). Neither clinical symptoms nor screw loosening or breakage occurred. Our preliminary clinical results suggest that the percutaneous anterior odontoid screw fixation procedure using a new instrument and fluoroscopy is technically feasible, safe, useful, and minimally invasive.

Wang, Xiang-Yang; Xu, Hua-Zi; Lin, Yan; Huang, Qi-Shan; Mao, Fang-Min; Ni, Wen-Fei; Wang, Sheng; Dai, Li-Yang

2007-01-01

27

Four-Screw Plate Fixation vs Conventional Fixation for Diaphyseal Fractures of the Forearm  

PubMed Central

Background: Standard treatment of diaphyseal fractures of the forearm is open reduction and fixation using dynamic compression plates (DCP) and screws. This technique uses screw placement in all 6 or more of the plate holes except the hole over the fracture line. We hypothesized that DCP with selective 4-screw bicortical placement can provide adequate fixation for these fractures. Objectives: The aim of this study was to evaluate the results of conventional 6 or more screw fixation versus 4 screw fixation for adults with diaphyseal fractures of the forearm. Patients and Methods: In this prospective study, 128 fractures of the ulna, radius or both bones of the forearm in 87 patients were treated in either one of these two groups: Open reduction and internal fixation (ORIF) with conventional DCP and screws or ORIF using DCP and selective 4- screw placement. Fractures were transverse or oblique in pattern without gross comminution. In a total of 41 patients with fractures, 28 single ulnar and 18 single radius fractures were included. Follow-up visits were done at 3-6 and 12-16 weeks and at 6 months. Outcome with respect to union an nonunion rates, union time, infection, and device failure was noted. Results: No change in alignment was noted in any patient. Union time in conventional and selective bicortical 4-screw fixation was 74.8 days and 73.6 days respectively which showed no significant difference (P = 0.064). Union rate and infection was 92.1% and 3.2% in conventional and 95.3% and 0% in the selective group respectively. Non-union was observed in 5 and 3 cases of fractures in conventional and the selective group respectively. Conclusions: For treatment of the transverse or oblique diaphyseal fractures of the forearm, fixation by a same length 3.5 mm DCP with selective 4-screw cortical fixation (2 screws on each side of the fracture site) had similar results in comparison with conventional 6 or more DCP screws. Because of lesser impact on host bone and smaller incision, the selective 4-screw insertion can be an alternative technique for treatment of these fractures.

Mehdi Nasab, Seyed Abdolhossein; Sarrafan, Nasser; Sabahi, Saeed

2012-01-01

28

Stress analysis of a centrally fractured rib fixated by an intramedullary screw.  

PubMed

The stress on an intramedullary screw rib fixation device holding together a centrally fractured human rib under in vivo force loadings was studied using finite element analysis (FEA). Validation of the FEA modelling using pullout from porcine ribs proved FEA to be suitable for assessing the structural integrity of screw/bone systems such as rib fixated by a screw. In the human rib fixation investigation, it was found that intramedullary bioresorbable Bioretec screws can fixate centrally fractured human ribs under normal breathing conditions. However, under coughing conditions, simulation showed Bioretec fixating screws to bend substantially. High stresses in the screw are mainly the result of flexion induced by the force loading, and are restricted to thin regions on the outside of the screw shaft. Stiffer screws result in less locally intense stress concentrations in bone, indicating that bone failure in the bone/screw contact regions can be averted with improvements in screw stiffness. PMID:23098197

Liovic, Petar; Sutalo, Ilija D; Marasco, Silvana F

2014-07-01

29

Addition of an anti-rotation screw to the dynamic hip screw for femoral neck fractures.  

PubMed

The authors investigated the use of an anti-rotation screw with the dynamic hip screw (DHS) during internal fixation of Garden I and II femoral neck fractures. Sixty-five patients with Garden I and II femoral neck fractures (mean age, 70 years) were treated with internal fixation at the authors' institution. In 31 patients, a 2-hole DHS was used alone (group 1), and in 34 patients, the DHS was combined with an anti-rotation screw placed in the cranial part of femoral head and neck (group 2). Patients' preinjury function and mental level were assessed using the Barthel index and the Abbreviated Mental test, respectively. The outcome measures included cost implications, operative time, and intraoperative radiation dose. The modified Harris Hip Score and a radiological assessment were performed at a mean of 11 months (range, 8-24 months) postoperatively. The use of the anti-rotation screw was associated with a longer operative time (mean, 44.54 minutes in group 1 vs 51.52 minutes in group 2; P<.0001) and more fluoroscopy screening (mean dose area product, 28.39 cGy/cm(2) in group 1 vs 44.33 cGy/cm(2) in group 2; P=.03). The additional cost of using an anti-rotation screw was £106 ($170) per case. No difference existed between the 2 groups with regard to radiological union, onset of avascular necrosis, and rate of revision surgeries. An anti-rotation screw, used with the dynamic hip screw, involves extra costs, prolongs operative time, and requires more intraoperative fluoroscopy screening but offers no advantages with regard to fracture union. PMID:23823042

Makki, Daoud; Mohamed, Ahmed M; Gadiyar, Rajeev; Patterson, Marc

2013-07-01

30

Subaxial subluxation after atlantoaxial transarticular screw fixation in rheumatoid patients  

PubMed Central

The most common cervical abnormality associated with rheumatoid arthritis (RA) is atlantoaxial subluxation, and atlantoaxial transarticular screw fixation has proved to be one of the most reliable, stable fixation techniques for treating atlantoaxial subluxation. Following C1–C2 fixation, however, subaxial subluxation reportedly can bring about neurological deterioration and require secondary operative interventions. Rheumatoid patients appear to have a higher risk, but there has been no systematic comparison between rheumatoid and non-rheumatoid patients. Contributing radiological factors to the subluxation have also not been evaluated. The objective of this study was to evaluate subaxial subluxation after atlantoaxial transarticular screw fixation in patients with and without RA and to find contributing factors. Forty-three patients who submitted to atlantoaxial transarticular screw fixation without any concomitant operation were followed up for more than 1 year. Subaxial subluxation and related radiological factors were evaluated by functional X-ray measurements. Statistical analyses showed that aggravations of subluxation of 2.5 mm or greater were more likely to occur in RA patients than in non-RA patients over an average of 4.2 years of follow-up, and postoperative subluxation occurred in the anterior direction in the upper cervical spine. X-ray evaluations revealed that such patients had a significantly smaller postoperative C2–C7 angle, and that the postoperative AA angle correlated negatively with this. Furthermore, anterior subluxation aggravation was significantly correlated with the perioperative atlantoaxial and C2–C7 angle changes, and these two changes were strongly correlated to each other. In conclusion, after atlantoaxial transarticular screw fixation, rheumatoid patients have a greater risk of developing subaxial subluxations. The increase of the atlantoaxial angel at the operation can lead to a decrease in the C2–C7 angle, followed by anterior subluxation of the upper cervical spine and possibly neurological deterioration.

Neo, Masashi; Sakamoto, Takeshi; Fujibayashi, Shunsuke; Yoshitomi, Hiroyuki; Nakamura, Takashi

2009-01-01

31

A novel screw guiding method with a screw guide template system for posterior C-2 fixation.  

PubMed

Object Accurate insertion of C-2 cervical screws is imperative; however, the procedures for C-2 screw insertion are technically demanding and challenging, especially in cases of C-2 vertebral abnormality. The purpose of this study is to report the effectiveness of the tailor-made screw guide template (SGT) system for placement of C-2 screws, including in cases with abnormalities. Methods Twenty-three patients who underwent posterior spinal fusion surgery with C-2 cervical screw insertion using the SGT system were included. The preoperative bone image on CT was analyzed using multiplanar imaging software. The trajectory and depth of the screws were designed based on these images, and transparent templates with screw guiding cylinders were created for each lamina. During the operation, after templates were engaged directly to the laminae, drilling, tapping, and screwing were performed through the templates. The authors placed 26 pedicle screws, 12 pars screws, 6 laminar screws, and 4 C1-2 transarticular screws using the SGT system. To assess the accuracy of the screw track under this system, the deviation of the screw axis from the preplanned trajectory was evaluated on postoperative CT and was classified as follows: Class 1 (accurate), a screw axis deviation less than 2 mm from the planned trajectory; Class 2 (inaccurate), 2 mm or more but less than 4 mm; and Class 3 (deviated), 4 mm or more. In addition, to assess the safety of the screw insertion, malpositioning of the screws was also evaluated using the following grading system: Grade 0 (containing), a screw is completely within the wall of the bone structure; Grade 1 (exposure), a screw perforates the wall of the bone structure but more than 50% of the screw diameter remains within the bone; Grade 2 (perforation), a screw perforates the bone structures and more than 50% of the screw diameter is outside the pedicle; and Grade 3 (penetration), a screw perforates completely outside the bone structure. Results In total, 47 (97.9%) of 48 screws were classified into Class 1 and Grade 0, whereas 1 laminar screw was classified as Class 3 and Grade 2. Mean screw deviations were 0.36 mm in the axial plane (range 0.0-3.8 mm) and 0.30 mm in the sagittal plane (range 0.0-0.8 mm). Conclusions This study demonstrates that the SGT system provided extremely accurate C-2 cervical screw insertion without configuration of reference points, high-dose radiation from intraoperative 3D navigation, or any registration or probing error evoked by changes in spinal alignment during surgery. A multistep screw placement technique and reliable screw guide cylinders were the key to accurate screw placement using the SGT system. PMID:24785974

Kaneyama, Shuichi; Sugawara, Taku; Sumi, Masatoshi; Higashiyama, Naoki; Takabatake, Masato; Mizoi, Kazuo

2014-08-01

32

Cement embolism into the venous system after pedicle screw fixation: case report, literature review, and prevention tips.  

PubMed

The strength of pedicle screws attachment to the vertebrae is an important factor affecting their motion resistance and long term performance. Low bone quality, e.g. in osteopenic patients, keeps the screw bone interface at risk for subsidence and dislocation. In such cases, bone cement could be used to augment pedicle screw fixation. But its use is not free of risk. Therefore, clinicians, especially spine surgeons, radiologists, and internists should become increasingly aware of cement migration and embolism as possible complications. Here, we present an instructive case of cement embolism into the venous system after augmented screw fixation with fortunately asymptomatic clinical course. In addition we discuss pathophysiology and prevention methods as well as therapeutic management of this potentially life-threatening complication in a comprehensive review of the literature. However, only a few case reports of cement embolism into the venous system were published after augmented screw fixation. PMID:24191184

Kerry, Ghassan; Ruedinger, Claus; Steiner, Hans-Herbert

2013-01-01

33

Coracoclavicular screw fixation for unstable distal clavicle fractures.  

PubMed

Fifteen patients with Neer type II distal clavicle fracture were treated surgically. Operative treatment included open reduction and fixation of the proximal clavicular fragment to the coracoid process using a 6.5-mm cancellous screw and repair of the coracoclavicular ligaments. Fracture union occurred at a mean of 7 weeks postoperatively without any serious complications. All patients returned to the pre-injury level of activity with no residual pain or dysfunction. PMID:16119284

Macheras, George; Kateros, Konstantinos T; Savvidou, Olga D; Sofianos, John; Fawzy, Ernest A; Papagelopoulos, Panayiotis J

2005-07-01

34

Management of odontoid fractures with percutaneous anterior odontoid screw fixation  

Microsoft Academic Search

Minimally invasive techniques have revolutionized the management of a variety of spinal disorders. The authors of this study\\u000a describe a new instrument and a percutaneous technique for anterior odontoid screw fixation, and evaluate its safety and efficacy\\u000a in the treatment of patients with odontoid fractures. Ten patients (6 males and 4 females) with odontoid fractures were treated\\u000a by percutaneous anterior

Yong-Long Chi; Xiang-Yang Wang; Hua-Zi Xu; Yan Lin; Qi-Shan Huang; Fang-Min Mao; Wen-Fei Ni; Sheng Wang; Li-Yang Dai

2007-01-01

35

Self-tapping versus standard tapped titanium screw fixation in the upper extremity.  

PubMed

Most screws used in fracture fixation necessitate a separate step for tapping of the screw hole. Titanium screw systems have been developed in which the screws can be inserted directly after a drill hole is made. These self-tapping screws thereby eliminate an operative step. A retrospective study was conducted that evaluated all wrist and hand procedures performed between January 1992 and December 1994 by 1 surgeon using screw fixation. The results of 39 cases treated with standard tapped titanium screws were compared with 28 cases treated with self-tapping titanium screws. Nearly identical union and complication rates were obtained in each group. Comparable results can be obtained with self-tapping screw fixation, which limits the number of instruments needed, eliminates an operative step, and thereby may diminish operative risk and shorten operative time. PMID:9556274

Bickley, M B; Hanel, D P

1998-03-01

36

Clinical Outcome of Modified Cervical Lateral Mass Screw Fixation Technique  

PubMed Central

Objective The purpose of this study was 1) to analyze clinically-executed cervical lateral mass screw fixation by the Kim's technique as suggested in the previous morphometric and cadaveric study and 2) to examine various complications and bicortical purchase that are important for b-one fusion. Methods A retrospective study was done on the charts, operative records, radiographs, and clinical follow up of thirty-nine patients. One hundred and seventy-eight lateral mass screws were analyzed. The spinal nerve injury, violation of the facet joint, vertebral artery injury, and the bicortical purchases were examined at each lateral mass. Results All thirty-nine patients received instrumentations with poly axial screws and rod systems, in which one hundred and seventy-eight screws in total. No vertebral artery injury or nerve root injury were observed. Sixteen facet joint violations were observed (9.0%). Bicortical purchases were achieved on one hundred and fifty-six (87.6%). Bone fusion was achieved in all patients. Conclusion The advantages of the Kim's technique are that it is performed by using given anatomical structures and that the complication rate is as low as those of other known techniques. The Kim's technique can be performed easily and safely without fluoroscopic assistance for the treatment of many cervical diseases.

Kim, Seong-Hwan; Seo, Won-Deog; Kim, Ki-Hong; Yeo, Hyung-Tae; Choi, Gi-Hwan

2012-01-01

37

Tibial tubercle osteotomy with screw fixation for total knee arthroplasty.  

PubMed

This study investigated the efficacy of tibial tubercle osteotomy (TTO) with screw fixation as part of the surgical treatment of primary complicated total knee arthroplasty (TKA) and revision TKA. From January 2000 to April 2011, 15 patients (15 knees) underwent revision TKA and 20 patients (21 knees) underwent primary TKA. The average patient age was 68.7±8.7 years. Patients underwent follow-up at the authors' institution for an average of 60.6±32.9 months. Comparison of preoperative and postoperative Knee Society Scores and Knee Society Functional Scores showed significant postoperative improvement (P<.05). Moreover, postoperative range of motion of the knee improved from 88.5°±33.8° to 104.3°±18.2° (P<.05). Radiographic assessment showed that the average period to bone union was 10.8±5 weeks (range, 5-28 weeks), the average length of the bone fragment was 59.4±5.9 mm, the average width at the proximal end was 18.9±2.9 mm, and the average thickness at the proximal end of the osteotomy was 10.3±1.2 mm. Tibial tubercle osteotomy provided wide exposure for TKA while protecting the extensor mechanism. Solid bone-to-bone fixation was achieved using TTO with 2 screws, and although the overall complication rate was 8.3%, none of the complications were associated with TTO itself. It is recommended that the bone fragment be 60 mm long, 20 mm wide, and 10 mm thick at the proximal end. Appropriate size of the osteotomized bone and solid screw fixation are essential to prevent complications during this procedure. PMID:24762842

Chinzei, Nobuaki; Ishida, Kazunari; Kuroda, Ryosuke; Matsumoto, Tomoyuki; Kubo, Seiji; Iguchi, Tetsuhiro; Chin, Takaaki; Akisue, Toshihiro; Nishida, Kotaro; Kurosaka, Masahiro; Tsumura, Nobuhiro

2014-04-01

38

The calcar screw in angular stable plate fixation of proximal humeral fractures - a case study  

PubMed Central

Background With new minimally-invasive approaches for angular stable plate fixation of proximal humeral fractures, the need for the placement of oblique inferomedial screws ('calcar screw') has increasingly been discussed. The purpose of this study was to investigate the influence of calcar screws on secondary loss of reduction and on the occurrence of complications. Methods Patients with a proximal humeral fracture who underwent angular stable plate fixation between 01/2007 and 07/2009 were included. On AP views of the shoulder, the difference in height between humeral head and the proximal end of the plate were determined postoperatively and at follow-up. Additionally, the occurrence of complications was documented. Patients with calcar screws were assigned to group C+, patients without to group C-. Results Follow-up was possible in 60 patients (C+ 6.7 ± 5.6 M/C- 5.0 ± 2.8 M). Humeral head necrosis occurred in 6 (C+, 15.4%) and 3 (C-, 14.3%) cases. Cut-out of the proximal screws was observed in 3 (C+, 7.7%) and 1 (C-, 4.8%) cases. In each group, 1 patient showed delayed union. Implant failure or lesions of the axillary nerve were not observed. In 44 patients, true AP and Neer views were available to measure the head-plate distance. There was a significant loss of reduction in group C- (2.56 ± 2.65 mm) compared to C+ (0.77 ± 1.44 mm; p = 0.01). Conclusions The placement of calcar screws in the angular stable plate fixation of proximal humeral fractures is associated with less secondary loss of reduction by providing inferomedial support. An increased risk for complications could not be shown.

2011-01-01

39

Atlantoaxial fixation using the polyaxial screw–rod system  

Microsoft Academic Search

The aim of this study is to evaluate the first results of the atlantoaxial fixation using polyaxial screw–rod system. Twenty-eight\\u000a patients followed-up 12–29 months (average 17.1 months) were included in this study. The average age was 59.5 years (range\\u000a 23–89 years). The atlantoaxial fusion was employed in 20 patients for an acute injury to the upper cervical spine, in 1 patient\\u000a with rheumatoid arthritis

Jan Stulik; Tomas Vyskocil; Petr Sebesta; Jan Kryl

2007-01-01

40

Percutaneous screw fixation of a vertebral pedicle fracture under CT-guidance: A new technique  

Microsoft Academic Search

We report on a new minimally invasive technique for the vertebral pedicle fracture after placement of a prosthetic disc. This intervention is an adaptation of CT-guided sacroiliac and acetabular fracture screw fixation. This type of procedure enables the perfect placement and measurement of the screw, as well as an extremely small incision under local anesthesia. CT guided Transpedicular fixation could

Nicolas Amoretti; Pierre-Yves Marcy; Olivier Hauger; Patrick Browaeys; Marie-eve Amoretti; Istvan Hoxorka; Pascal Boileau

41

Biomechanical analysis of anterior cervical spine plate fixation systems with unicortical and bicortical screw purchase  

Microsoft Academic Search

Anterior plate fixation with unicortical screw purchase does not involve the risk of posterior cortex penetration and possible injuries of the spinal cord. However, there are very few biomechanical data about the immediate stability of non-locking plate fixation with unicortical or bicortical screw placement. The aim of the present study was to evaluate the immediate biomechanical properties in terms of

Wolfgang Lehmann; Michael Blauth; Daniel Briem; Ulf Schmidt

2004-01-01

42

Cervical anterior transpedicular screw fixation (ATPS)—Part II. Accuracy of manual insertion and pull-out strength of ATPS  

Microsoft Academic Search

Reconstruction after multilevel decompression of the cervical spine, especially in the weakened osteoporotic, neoplastic or\\u000a infectious spine often requires circumferential stabilization and fusion. To avoid the additional posterior surgery in these\\u000a cases while increasing rigidity of anterior-only screw-plate constructs, the authors introduce the concept of anterior transpedicular\\u000a screw (ATPS) fixation. We demonstrated its morphological feasibility as well as its indications

Heiko Koller; Frank Acosta; Mark Tauber; Michael Fox; Hudelmaier Martin; Rosmarie Forstner; Peter Augat; Rainer Penzkofer; Christian Pirich; H. Kässmann; Herbert Resch; Wolfgang Hitzl

2008-01-01

43

Transpedicular screw fixation for type II Hangman's fracture: a motion preserving procedure.  

PubMed

Opinions have varied regarding the optimal treatment of an unstable Hangman's fracture. C2 pedicle screw instrumentation is a biomechanically strong fixation which although done through a simple posterior approach, is a technically demanding procedure. This prospective, non-randomized multicentre study included 15 consecutive patients with displaced type II traumatic spondylolisthesis of the axis. There were nine males and six females with a mean age of 37 years at surgery. The cause of injury was a road traffic accident in 11 patients and a fall from height in 4 patients. All patients had a single stage reduction and direct transpedicular screw fixation through the C2 pedicles. During follow-up, clinical evaluation and plain X-rays were performed at each visit; at 6-month follow-up, additional dynamic lateral flexion/extension views and a CT scan were performed. The average follow-up period was 32 months (range 25-56 months). At final follow-up, all patients were asymptomatic and regained a good functional outcome with no limitation of range of motion; all the patients showed solid union with no implant failure. There were no neurological complications. At 6-month follow-up, CT evaluation showed fusion in all patients and an adequate position of 28 screws. Two pedicle screws (6.6%) showed minimal (defined as <2 mm) intrusion; one into the spinal canal and the other into the vertebral foreamen. Transpedicular screw fixation through the C2 pedicles is a safe and effective method in treating type II traumatic spondylolisthesis of the axis resulting in good clinical and radiological outcomes. Adequate reduction was achieved and motion segments were preserved with its use. PMID:20401619

ElMiligui, Yasser; Koptan, Wael; Emran, Ihab

2010-08-01

44

Windshield-wiper loosening: a complication of in situ screw fixation of slipped capital femoral epiphysis.  

PubMed

A retrospective review of patients treated for slipped capital femoral epiphysis (SCFE) by in situ screw fixation with a cannulated titanium screw was performed. Of the 18 hips with at least 1-year follow-up, windshield-wiper loosening of the cannulated screw in the femoral head had occurred in three. In all three cases, the screw had been left protruding > 1.5 cm from the anterolateral cortex of the femur. We postulate that with hip motion the protruding screw is toggled by the anterolateral soft tissues, causing a windshield-wiper effect in the femoral head, leading to eventual screw loosening. We believe that leaving the screw protruding from the fascia lata is a potential source of screw loosening by the windshield-wiper mechanism and now routinely place the screw head within 1.5 cm of the anterolateral cortex of the femur. PMID:8376561

Maletis, G B; Bassett, G S

1993-01-01

45

Arthroscopically assisted reconstruction and percutaneous screw fixation of a Pilon tibial fracture.  

PubMed

We report a case of closed distal tibial fracture (AO 43C3), treated successfully with arthroscopically assisted minimally invasive reduction and percutaneous screw fixation. Techniques and postoperative treatment are described. PMID:12724669

Kralinger, Franz; Lutz, Martin; Wambacher, Markus; Smekal, Vinzenz; Golser, Karl

2003-01-01

46

Percutaneous Cement-Augmented Screws Fixation in the Fractures of the Aging Spine: Is It the Solution?  

PubMed Central

Introduction. Management of elderly patients with thoracolumbar fractures is still challenging due to frequent osteoporosis and risk of screws pull-out. The aim of this study was to evaluate results of a percutaneous-only procedure to treat these fragile patients using cement-augmented screws. Methods. 12 patients diagnosed with a thoracolumbar fracture associated with an important loss of bone stock were included in this prospective study. Surgical procedure included systematically a percutaneous osteosynthesis using cemented fenestrated screws. When necessary, additional anterior support was performed using a kyphoplasty procedure. Clinical and radiographic evaluations were performed using CT scan. Results. On the whole series, 15 fractures were diagnosed and 96 cemented screws were inserted. The difference between the pre- and postoperative vertebral kyphosis was statistically significant (12.9° versus 4.4°, P = 0.0006). No extrapedicular screw was reported and one patient was diagnosed with a cement-related pulmonary embolism. During follow-up period, no infectious complications, implant failures, or pull-out screws were noticed. Discussion. Aging spine is becoming an increasing public health issue. Management of these patients requires specific attention due to the augmented risk of complications. Using percutaneous-only screws fixation with cemented screw provides satisfactory results. A rigorous technique is mandatory in order to achieve best outcomes.

Pesenti, Sebastien; Peltier, Emilie; Adetchessi, Tarek; Dufour, Henry; Fuentes, Stephane

2014-01-01

47

Inferolateral Entry Point for C2 Pedicle Screw Fixation in High Cervical Lesions  

PubMed Central

Objective The purpose of this retrospective study was to evaluate the efficacy and safety of atlantoaxial stabilization using a new entry point for C2 pedicle screw fixation. Methods Data were collected from 44 patients undergoing posterior C1 lateral mass screw and C2 screw fixation. The 20 cases were approached by the Harms entry point, 21 by the inferolateral point, and three by pars screw. The new inferolateral entry point of the C2 pedicle was located about 3-5 mm medial to the lateral border of the C2 lateral mass and 5-7 mm superior to the inferior border of the C2-3 facet joint. The screw was inserted at an angle 30° to 45° toward the midline in the transverse plane and 40° to 50° cephalad in the sagittal plane. Patients received followed-up with clinical examinations, radiographs and/or CT scans. Results There were 28 males and 16 females. No neurological deterioration or vertebral artery injuries were observed. Five cases showed malpositioned screws (2.84%), with four of the screws showing cortical breaches of the transverse foramen. There were no clinical consequences for these five patients. One screw in the C1 lateral mass had a medial cortical breach. None of the screws were malpositioned in patients treated using the new entry point. There was a significant relationship between two group (p=0.036). Conclusion Posterior C1-2 screw fixation can be performed safely using the new inferolateral entry point for C2 pedicle screw fixation for the treatment of high cervical lesions.

Lee, Kwang Ho; Lee, Chul Hee; Hwang, Soo Hyun; Park, In Sung; Jung, Jin Myung

2011-01-01

48

Fixation strength of biocomposite wedge interference screw in ACL reconstruction: effect of screw length and tunnel/screw ratio. A controlled laboratory study  

PubMed Central

Background Primary stability of the graft is essential in anterior cruciate ligament surgery. An optimal method of fixation should be easy to insert and provide great resistance against pull-out forces. A controlled laboratory study was designed to test the primary stability of ACL tendinous grafts in the tibial tunnel. The correlation between resistance to traction forces and the cross-section and length of the screw was studied. Methods The tibial phase of ACL reconstruction was performed in forty porcine tibias using digital flexor tendons of the same animal. An 8 mm tunnel was drilled in each specimen and two looped tendons placed as graft. Specimens were divided in five groups according to the diameter and length of the screw used for fixation. Wedge interference screws were used. Longitudinal traction was applied to the graft with a Servohydraulic Fatigue System. Load and displacement were controlled and analyzed. Results The mean loads to failure for each group were 295,44 N (Group 1; 9 × 23 screw), 564,05 N (Group 2; 9 × 28), 614,95 N (Group 3; 9 × 35), 651,14 N (Group 4; 10 × 28) and 664,99 (Group 5; 10 × 35). No slippage of the graft was observed in groups 3, 4 and 5. There were significant differences in the load to failure among groups (ANOVA/P < 0.001). Conclusions Longer and wider interference screws provide better fixation in tibial ACL graft fixation. Short screws (23 mm) do not achieve optimal fixation and should be implanted only with special requirements.

2010-01-01

49

Monoaxial Pedicle Screws Are Superior to Polyaxial Pedicle Screws and the Two Pin External Fixator for Subcutaneous Anterior Pelvic Fixation in a Biomechanical Analysis  

PubMed Central

Purpose. Comparison of monoaxial and polyaxial screws with the use of subcutaneous anterior pelvic fixation. Methods. Four different groups each having 5 constructs were tested in distraction within the elastic range. Once that was completed, 3 components were tested in torsion within the elastic range, 2 to torsional failure and 3 in distraction until failure. Results. The pedicle screw systems showed higher stiffness (4.008 ± 0.113?Nmm monoaxial, 3.638 ± 0.108?Nmm Click-x; 3.634 ± 0.147?Nmm Pangea) than the exfix system (2.882 ± 0.054?Nmm) in distraction. In failure testing, monoaxial pedicle screw system was stronger (360?N) than exfixes (160?N) and polyaxial devices which failed if distracted greater than 4?cm (157?N Click-x or 138?N Pangea). The exfix had higher peak torque and torsional stiffness than all pedicle systems. In torsion, the yield strengths were the same for all constructs. Conclusion. The infix device constructed with polyaxial or monoaxial pedicle screws is stiffer than the 2 pin external fixator in distraction testing. In extreme cases, the use of reinforcement or monoaxial systems which do not fail even at 360?N is a better option. In torsional testing, the 2 pin external fixator is stiffer than the pedicle screw systems.

Vaidya, Rahul; Onwudiwe, Ndidi; Roth, Matthew; Sethi, Anil

2013-01-01

50

Monoaxial pedicle screws are superior to polyaxial pedicle screws and the two pin external fixator for subcutaneous anterior pelvic fixation in a biomechanical analysis.  

PubMed

Purpose. Comparison of monoaxial and polyaxial screws with the use of subcutaneous anterior pelvic fixation. Methods. Four different groups each having 5 constructs were tested in distraction within the elastic range. Once that was completed, 3 components were tested in torsion within the elastic range, 2 to torsional failure and 3 in distraction until failure. Results. The pedicle screw systems showed higher stiffness (4.008 ± 0.113?Nmm monoaxial, 3.638 ± 0.108?Nmm Click-x; 3.634 ± 0.147?Nmm Pangea) than the exfix system (2.882 ± 0.054?Nmm) in distraction. In failure testing, monoaxial pedicle screw system was stronger (360?N) than exfixes (160?N) and polyaxial devices which failed if distracted greater than 4?cm (157?N Click-x or 138?N Pangea). The exfix had higher peak torque and torsional stiffness than all pedicle systems. In torsion, the yield strengths were the same for all constructs. Conclusion. The infix device constructed with polyaxial or monoaxial pedicle screws is stiffer than the 2 pin external fixator in distraction testing. In extreme cases, the use of reinforcement or monoaxial systems which do not fail even at 360?N is a better option. In torsional testing, the 2 pin external fixator is stiffer than the pedicle screw systems. PMID:24368943

Vaidya, Rahul; Onwudiwe, Ndidi; Roth, Matthew; Sethi, Anil

2013-01-01

51

Polyaxial locking and compression screws improve construct stiffness of acetabular cup fixation: a biomechanical study.  

PubMed

Bone ingrowth into uncemented acetabular components requires intimate cup-bone contact and rigid fixation, which can be difficult to achieve in revision hip arthroplasty. This study compares polyaxial compression locking screws with non-locked and cancellous screw constructs for acetabular cup fixation. An acetabular cup modified with screw holes to provide both compression and angular stability was implanted into a bone substitute. Coronal lever out, axial torsion and push-out tests were performed with an Instron testing machine, measuring load versus displacement. Polyaxial locking compression screws significantly improved construct stiffness compared with non-locked or cancellous screws. This increased construct stiffness will likely reduce interfacial micromotion. Further research is required to determine whether this will improve bone ingrowth in vivo and reduce cup failure. PMID:24360790

Milne, Lachlan P; Kop, Alan M; Kuster, Markus S

2014-05-01

52

Guidewire Breakage: An Unusual Complication of Anterior Odontoid Cannulated Screw Fixation  

PubMed Central

The preferred treatment of a type II odontoid fracture is anterior odontoid screw fixation to preserve the cervical spine range of movement. This case report describes an unusual complication of guidewire breakage during anterior odontoid cannulated screw fixation for a 52-year-old patient who presented with a type II odontoid fracture after a motor vehicle accident. The distal segment of the guidewire was bent over the tip of the cannulated odontoid screw and broke off during guidewire withdrawal. The three months follow-up computed tomography examination of the cervical spine showed acceptable screw placement, good odontoid process alignment with incomplete fusion, and no migration of the fractured segment of the guidewire. It is recommended that the guidewire be withdrawn once the cannulated screw is passed through the fractured site into the odontoid process and a new guidewire be used in each surgical procedure instead of been reused to avoid metal stress fatigue that can result in easy breakage.

Bin-Nafisah, Sharaf; Almusrea, Khaled; Alfawareh, Mohamed

2011-01-01

53

Efficacy analysis of pedicle screw internal fixation of fractured vertebrae in the treatment of thoracolumbar fractures  

PubMed Central

The present study aimed to discuss the method and effect of posterior internal fixation of thoracolumbar fractures strengthened by the vertical stress pedicle screw fixation of fractured vertebrae. Patients with single thoracolumbar fractures were examined retrospectively. Fourteen patients (group A) had been treated with vertical stress pedicle screw fixation of a fractured vertebra and sixteen patients (group B) received traditional double-plate fixation, as a control. All patients were diagnosed with fresh fractures with a complete unilateral or bilateral pedicle and no explosion of the inferior half of the vertebral body or inferior endplate. In group A, patients received conventional posterior distraction and lumbar lordosis restoration, as well as pedicle screws in the fractured vertebra in a vertical direction to relieve stress to achieve a local stress balance. All patients were followed up postoperatively for 4–18 months (average, 12.6 months). The vertical stress pedicle screw fixation assisted in the reduction of vertebrae fracture, which reduced the postoperative Cobb’s angle loss. There was a significant difference in the change of Cobb’s angle between the two groups one year after surgery (P<0.01). Conditional application of pedicle screws in a single thoracolumbar fracture enhances the stability of the internal fixation system and is conducive to the correction of kyphosis and maintenance of the corrective effects.

HUANG, WEIJIE; LUO, TAO

2013-01-01

54

Posterior Atalntoaxial Fusion with C1 Lateral Mass Screw and C2 Pedicle Screw Supplemented with Miniplate Fixation for Interlaminar Fusion : A Preliminary Report  

PubMed Central

Objective To investigate the feasibility of C1 lateral mass screw and C2 pedicle screw with polyaxial screw and rod system supplemented with miniplate for interlaminar fusion to treat various atlantoaxial instabilities. Methods After posterior atlantoaxial fixation with lateral mass screw in the atlas and pedicle screw in the axis, we used 2 miniplates to fixate interlaminar iliac bone graft instead of sublaminar wiring. We performed this procedure in thirteen patients who had atlantoaxial instabilities and retrospectively evaluated the bone fusion rate and complications. Results By using this method, we have achieved excellent bone fusion comparing with the result of other methods without any complications related to this procedure. Conclusion C1 lateral mass screw and C2 pedicle screw with polyaxial screw and rod system supplemented with miniplate for interlaminar fusion may be an efficient alternative method to treat various atlantoaxial instabilities.

Yoon, Sang-Mok; Baek, Jin-Wook

2012-01-01

55

Simulation-based particle swarm optimization and mechanical validation of screw position and number for the fixation stability of a femoral locking compression plate.  

PubMed

Locking compression plates (LCPs) have been used to fix femoral shaft fractures. Previous studies have attempted to identify the best LCP screw positions and numbers to achieve the fixation stability. However, the determined screw positions and numbers were mainly based on the surgeons' experiences. The aim of this study was to discover the best number and positions of LCP screws to achieve acceptable fixation stability. Three-dimensional numerical models of a fractured femur with the LCP were first developed. Then, the best screw position and number of LCPs were determined by using a simulation-based particle swarm optimization algorithm. Finally, the results of the numerical study were validated by conducting biomechanical tests. The results showed that the LCP with six locking screws resulted in the necessary fixation stability, and the best combination of positions of locking screws inserted into the LCP was 1-5-6-7-8-12 (three locking screws on either side of the bone fragment with two locking screws as close as practicable to the fracture site). In addition, the numerical models and algorithms developed in this study were validated by the biomechanical tests. Both the numerical and experimental results can provide clinical suggestions to surgeons and help them to understand the biomechanics of LCP systems. PMID:24090880

Lee, Chian-Her; Shih, Kao-Shang; Hsu, Ching-Chi; Cho, Tomas

2014-01-01

56

Axial Loading Cross Screw Fixation for the Austin Bunionectomy  

Microsoft Academic Search

The Austin procedure has become a common method of osteotomy for the correction of hallux abductovalgus when indicated. The V-type configuration is intrinsically stable but not without complications. One complication encountered is rotation and\\/or displacement of the capital fragment. We present the use of an axial loading screw in conjunction with a dorsally placed compression screw. The benefit to this

Ryan B. Rigby; Lawrence M. Fallat; John P. Kish

2011-01-01

57

Outcomes of C1 and C2 posterior screw fixation for upper cervical spine fusion.  

PubMed

To achieve stable fixation of the upper cervical spine in posterior fusions, the occiput is often included. With the newer techniques, excluding fixation to the occiput will retain the occiput-cervical motion, while still allowing a stable fixation. Harms's technique has been adapted at our institution and its effectiveness for indications such as C2 complex fractures and tumors using C1 or C2 as endpoints of a posterior fixation are reviewed. Fourteen cases were identified, consisting of one os odontoideum; four acute fractures and four non-unions of the odontoid; three tumors and two complex fractures of C2 vertebral body, and one C2-C3 post-traumatic instability. One misplaced screw without clinical consequences was the only complication recorded. Screw loosening or migration was not observed at follow-up, showing a stable fixation. PMID:19387696

De Iure, F; Donthineni, R; Boriani, S

2009-06-01

58

Outcomes of C1 and C2 posterior screw fixation for upper cervical spine fusion  

PubMed Central

To achieve stable fixation of the upper cervical spine in posterior fusions, the occiput is often included. With the newer techniques, excluding fixation to the occiput will retain the occiput–cervical motion, while still allowing a stable fixation. Harms’s technique has been adapted at our institution and its effectiveness for indications such as C2 complex fractures and tumors using C1 or C2 as endpoints of a posterior fixation are reviewed. Fourteen cases were identified, consisting of one os odontoideum; four acute fractures and four non-unions of the odontoid; three tumors and two complex fractures of C2 vertebral body, and one C2–C3 post-traumatic instability. One misplaced screw without clinical consequences was the only complication recorded. Screw loosening or migration was not observed at follow-up, showing a stable fixation.

Donthineni, R.; Boriani, S.

2009-01-01

59

Lumbosacral fixation using sacroiliac buttress screws: a modification to the Jackson technique with intrasacral rods  

PubMed Central

Background The use of intrasacral rods has been previously reported for posterior lumbosacral fixation. However, problems associated with this technique include poor stability of the rod in the sacrum, difficulty in contouring the rod to fit the lateral sacral mass, and the complicated assembly procedure for the rod and pedicle screws in the thoracolumbar segments after insertion of the rod into the sacrum. Methods We used a screw with a polyaxial head instead of an intrasacral rod, which was inserted into the lateral sacral mass and assembled to the rod connected cephalad to pedicle screws. The dorsal side of the screw was stabilized by the sacral subchondral bone at the sacroiliac joint with iliac buttress coverage, and the tip of the screw was anchored by the sacral cortex. Results Three different cases were used to illustrate lumbosacral fixation using intrasacral screws as an anchor for the spinal instrumentation. Effective resistance of flexural bending moment and fusion were achieved in these patients at the lumbosacral level. Conclusions An intrasacral screw can be stabilized by subchondral bone with iliac buttress coverage at the dorsal and ventral sacral cortex. Posterior spinal fusion with this screw technique enables easier assembly of the instrumentation and presents better stabilization than that provided by the previously reported intrasacral rod technique for correction and fusion of thoracolumbar kyphoscoliosis.

2014-01-01

60

Cervical Pedicle Screw Fixation: Anatomic Feasibility of Pedicle Morphology and Radiologic Evaluation of the Anatomical Measurements  

PubMed Central

Study Design All parameters were measured manually and with a computed tomography (CT) scanner. For the manual measurements, a Vernier scale instrument was used. Purpose This study evaluates quantitatively pedicles of middle and lower cervical spine (C3 to C7) and to evaluate the possibilities of using these structures as anchors in posterior cervical fusion. Overview of Literature Pedicle screws may be an alternative fixation technique for posterior cervical instrumentation. Methods Twenty-two bony sets of adult cervical spines were studied (110 vertebrae, 220 pedicles) from C3 down to C7. Results CT measurement of cervical pedicles appeared to be accurate and valuable for preoperative planning of cervical pedicle screw instrumentation. The study showed a high correlation between the values obtained by manual and CT measurements of pedicle dimensions. The technical challenge of insertion is the obvious theoretical drawback of the use of cervical pedicle screws. Many technical factors are important to consider, namely, the point of screw entry, the pedicle dimensions, the screw direction according to the pedicle angle and orientation, the screw diameter and length, and the method of screw introduction. Conclusions Transpedicular screw fixation of the cervical spine appears to be promising. Anatomic limitations should be clear to the surgeon. Further clinical and biomechanical studies are needed to settle this technique.

2014-01-01

61

Cervical anterior transpedicular screw fixation. Part I: Study on morphological feasibility, indications, and technical prerequisites.  

PubMed

Multilevel cervical spine procedures can challenge the stability of current anterior cervical screw-and-plate systems, particularly in cases of severe three-column subaxial cervical spine injuries and multilevel plated reconstructions in osteoporotic bone. Supplemental posterior instrumentation is therefore recommended to increase primary construct rigidity and diminish early failure rates. The increasing number of successfully performed posterior cervical pedicle screw fixations have enabled more stable fixations, however most cervical pathologies are located anteriorly and preferably addressed by an anterior approach. To combine the advantages of the anterior approach with the superior biomechanical characteristics of cervical pedicle screw fixation, the authors developed a new concept of a cervical anterior transpedicular screw-and-plate system. An in vivo anatomical study was performed to explore the feasibility of anterior transpedicular screw fixation (ATPS) in the cervical spine. The morphological study was conducted based on 29 cervical spine CT scans from healthy patients and measurements were performed on the pedicle sizes, angulations, vertebral body depth, height and width at C2 to T1. Significant morphologic parameters for the new technique are discussed. These parameters include the sagittal and transverse intersection points of the pedicle axis with the anterior vertebral body wall, as well as the distances between sagittal intersection points from C2 to T1. On the basis of these results, standard spine models were reconstructed and used for the conceptual development of a preclinical release prototype of an anterior transpedicular screw-and-plate system. The morphological feasibility of the new technique is demonstrated, and its indications, biomechanical considerations, as well as surgical prerequisites are thoroughly discussed. In the future, the technique of cervical anterior transpedicular screw fixation might diminish the number of failures in the reconstruction of multilevel and three-column cervical spine instabilities, and avoid the need for supplemental posterior instrumentation. PMID:18224358

Koller, Heiko; Hempfing, Axel; Acosta, Frank; Fox, Michael; Scheiter, Armin; Tauber, Mark; Holz, Ulrich; Resch, Herbert; Hitzl, Wolfgang

2008-04-01

62

Cervical anterior transpedicular screw fixation. Part I: Study on morphological feasibility, indications, and technical prerequisites  

Microsoft Academic Search

Multilevel cervical spine procedures can challenge the stability of current anterior cervical screw-and-plate systems, particularly\\u000a in cases of severe three-column subaxial cervical spine injuries and multilevel plated reconstructions in osteoporotic bone.\\u000a Supplemental posterior instrumentation is therefore recommended to increase primary construct rigidity and diminish early\\u000a failure rates. The increasing number of successfully performed posterior cervical pedicle screw fixations have enabled

Heiko Koller; Axel Hempfing; Frank Acosta; Michael Fox; Armin Scheiter; Mark Tauber; Ulrich Holz; Herbert Resch; Wolfgang Hitzl

2008-01-01

63

Comparison of migration behavior between single and dual lag screw implants for intertrochanteric fracture fixation  

PubMed Central

Background Lag screw cut-out failure following fixation of unstable intertrochanteric fractures in osteoporotic bone remains an unsolved challenge. This study tested if resistance to cut-out failure can be improved by using a dual lag screw implant in place of a single lag screw implant. Migration behavior and cut-out resistance of a single and a dual lag screw implant were comparatively evaluated in surrogate specimens using an established laboratory model of hip screw cut-out failure. Methods Five dual lag screw implants (Endovis, Citieffe) and five single lag screw implants (DHS, Synthes) were tested in the Hip Implant Performance Simulator (HIPS) of the Legacy Biomechanics Laboratory. This model simulated osteoporotic bone, an unstable fracture, and biaxial rocking motion representative of hip loading during normal gait. All constructs were loaded up to 20,000 cycles of 1.45 kN peak magnitude under biaxial rocking motion. The migration kinematics was continuously monitored with 6-degrees of freedom motion tracking system and the number of cycles to implant cut-out was recorded. Results The dual lag screw implant exhibited significantly less migration and sustained more loading cycles in comparison to the DHS single lag screw. All DHS constructs failed before 20,000 cycles, on average at 6,638 ± 2,837 cycles either by cut-out or permanent screw bending. At failure, DHS constructs exhibited 10.8 ± 2.3° varus collapse and 15.5 ± 9.5° rotation around the lag screw axis. Four out of five dual screws constructs sustained 20,000 loading cycles. One dual screw specimens sustained cut-out by medial migration of the distal screw after 10,054 cycles. At test end, varus collapse and neck rotation in dual screws implants advanced to 3.7 ± 1.7° and 1.6 ± 1.0°, respectively. Conclusion The single and double lag screw implants demonstrated a significantly different migration resistance in surrogate specimens under gait loading simulation with the HIPS model. In this model, the double screw construct provided significantly greater resistance against varus collapse and neck rotation in comparison to a standard DHS lag screw implant.

Kouvidis, George K; Sommers, Mark B; Giannoudis, Peter V; Katonis, Pavlos G; Bottlang, Michael

2009-01-01

64

A comparative in vitro study of fixation of mandibular fractures with paraskeletal clamps or screw plates.  

PubMed

The use of porcine rib pairs as an in vitro analog for the edentulous mandible is described. Using this model, the relative degree of fixation achieved with a screw plate (Champy) and a paraskeletal clamp plate (Mennen) has been evaluated. The fractured plated ribs failed at significantly lower bending forces than the non-sectioned controls. However, no statistically significant difference in force at failure between the two different methods of plate fixation could be demonstrated. PMID:2329396

Crofts, C E; Trowbridge, A; Maung Aung, T; Brook, I M

1990-05-01

65

Effect of screw diameter, insertion technique, and bone cement augmentation of pedicular screw fixation strength.  

PubMed

This study investigated (1) the effect of screw diameter and insertion technique in lumbar vertebrae, and insertion site in the sacrum, on the axial pullout force and transverse bending stiffness of pedicle screws, and (2) the effect of bone cement augmentation using polymethylmethacrylate (PMMA) and the biodegradable composite, poly(propylene glycol-fumarate) on axial pullout force and transverse bending stiffness of pedicle screws inserted into lumbar vertebrae. The axial pullout force and transverse bending stiffness of a 6.25-mm Steffee screw and a 6-mm Kluger screw did not differ significantly in vertebral bodies of similar equivalent bone mineral density. The axial pullout force of Schanz screws was significantly increased with a 1-mm increase in screw diameter. However, there was no significant increase in transverse bending stiffness. In the sacrum, an approach through the S1 facet produced significantly higher axial pullout forces and transverse bending stiffness than the approach described by Harrington and Dickson. PMMA and a biodegradable composite bone cement poly(propylene glycol-fumarate) both increased the axial pullout force. PMMA also increased the transverse bending stiffness. PMID:8222439

Wittenberg, R H; Lee, K S; Shea, M; White, A A; Hayes, W C

1993-11-01

66

Percutaneous cannulated screw fixation of femoral neck fractures: the three point principle  

Microsoft Academic Search

Out of a total of 183 patients with displaced intracapsular fractures of the femoral neck, 40 were treated with percutaneous cannulated screw fixation according to the ‘three point principle’. These patients were reviewed retrospectively, paying special attention to mechanical failure. Thirty-five fractures healed in a good position. Four fractures (10 per cent) showed signs of recurrent instability, resulting in non-union

C. A. Bout; D. M. Cannegieter; J. W. Juttmann

1997-01-01

67

Computed tomography-guided percutaneous facet screw fixation in the lumbar spine. Technical note.  

PubMed

The authors describe a new minimally invasive technique for posterior supplementation using percutaneous translaminar facet screw (TFS) fixation with computed tomography (CT) guidance. Oblique axial images were used to determine facet screw fixation sites. After the induction of local anesthesia and conscious sedation, a guide pin was inserted and guided with a laser mounted on the CT gantry. Cannulated TFSs were placed via a percutaneous approach. From December 2002 to August 2003, 18 patients underwent CT-guided TFS. In 17 of these patients this procedure was supplementary to anterior lumbar interbody fusion, which had been performed several days earlier; in the remaining patient, CT-guided TFS fixation was undertaken as the primary therapy. Twelve patients had painful degenerative disc disease or unstable degenerative spondylolisthesis, three had infections, and three had deformities. All screws were inserted accurately and there were no complications. This new minimally invasive surgical technique may offer an alternative to pedicle screw fixation as a method of posterior supplementation. PMID:17633496

Kang, Ho Yeong; Lee, Sang-Ho; Jeon, Sang Hyeop; Shin, Song-Woo

2007-07-01

68

The biomechanics of interference screw fixation of patellar tendon anterior cruciate ligament grafts  

Microsoft Academic Search

Twenty-seven paired human cadaveric knee specimens were used to determine the effect of surgical technique and various interference screw parameters on the pullout strength of patellar tendon femoral bone blocks. The study compared the fixation strength of endoscop ically inserted and conventional \\

Charles H. Brown; Aaron T. Hecker; John A. Hipp; Elizabeth R. Myers; Wilson C. Hayes

1993-01-01

69

[Progress on cervical anterior transpedicular screw fixators for lower cervical vertebrae].  

PubMed

Compared with the traditional anterior and posterior operation,anterior transpedicular screw fixation (ATPS) has many advantages of hiomechanics, relative safety. Both problems of decompression and reconstruction can be resolved only through an anterior approach. A rather peculiar anatomic channel was used in ATPS, but no special tools was used in system supporting for anterior pedicle screw to place,so the indications of ATPS of lower cervical vertebrae is relatively narrow,it cannot replace of traditional anterior and posterior surgery. Problems of accurately inserting screws and the development of internal fixation device about ATPS is a hot spot of current research and a future direction. In recent years,many scholars have systematically studied the technique, and applied it in clinic gradually and achieved good effects. In order to improve the level of application,recent articles were analyzed retrospectively in this paper,and the studies of anatomy,biomechanical and clinical application of ATPS were reviewed. PMID:24490542

Li, Jie; Zhao, Lin-Jun; Xu, Rong-Ming; Zhang, Ming; Jiang, Wei-Yu; Qi, Feng

2013-10-01

70

Chevron bunionectomy with microplate and screw fixation: a retrospective follow-up of 26 feet.  

PubMed

The authors report the results of 21 patients (26 feet) who had Chevron osteotomy of the first metatarsal head to correct hallux valgus. Fixation was achieved by using a small plating system consisting of one L-plate (8.5 mm x 17 mm x 0.8 mm) and four screws (1.6 mm). Results showed no capital fragment displacement, avascular necrosis, or plate deformation. One case of screw loosening was noted on x-rays. This patient noted occasional irritation over the plate while wearing shoes. Symptoms did not cause the patient to seek removal of the plate and screws. The small plate system allows the surgeon to perform the osteotomy as originally described by Austin, with the added security of rigid internal fixation. PMID:8986891

Yearian, P R; Brown, T; Goldman, F

1996-01-01

71

Fixation of femoral neck fractures using divergent versus parallel cannulated screws.  

PubMed

Controversy exists regarding the optimal method of internal fixation in femoral neck fractures. Biomechanical data suggest that calcar fixation is superior to central screws placement. We propose a divergent technique for placing 3 cannulated stainless steel screws engaging the calcar femorale. Fifty two patients admitted to our institution for a femoral neck fracture were treated with the divergent screw technique, over a 7-year period. Four patients were deceased and 4 were lost to follow-up. Of the remaining 44 patients there were 10 males and 34 females, aged from 33 to 78 years (mean, 58 years). All patients were operated on by the same surgeon and were followed-up for a minimum of 2 years (mean: 33.6 months, range: 2-6 years). Twenty four patients sustained a non-displaced fracture (Garden I-II) and 20 sustained a displaced fracture (Garden III-IV) of the femoral neck. Mean Harris hip score (HHS) was 89.6 points. Avascular necrosis was evident in 4 patients (9%) with displaced fractures. Non-unions or failed internal fixations were not encountered. There was a significant difference in the HHS, in favor of the divergent group (P = 0.006), while more complications were encountered in the parallel group including 6 cases with non-union. In conclusion, parallel screw placement is not critical for an excellent clinical outcome. Our proposed fixation method using 3 screws that diverge and lie in different coronal planes (1 engaging the calcar femorale) with a free-hand technique may offer enhanced fixation. Biomechanical data along with larger clinical studies are needed to establish our proposed method. PMID:21663582

Papanastassiou, Ioannis D; Mavrogenis, Andreas F; Kokkalis, Zinon T; Nikolopoulos, Konstantinos; Skourtas, Konstantinos; Papagelopoulos, Panayiotis J

2011-01-01

72

An investigation of the effects of hydroxyapatite coatings on the fixation strength of cortical screws.  

PubMed

Hydroxyapatite (HA) are commonly applied to orthopaedic implants for acceleration of osteointegration and so overcoming the loosening problems such as in cortical screws. Electrophoretic deposition (EPD) of hydroxyapatite was applied for coating of cortical screws in this work. The effects of hydroxyapatite-coated and uncoated cortical screws on insertion and extraction torque were investigated through in vivo experiments. Three groups of screws were undertaken: first group with no coating, second group coated with HA and the third group coated with HA+interlayer, a synthetic calcium silicate compound. Five sheep were operated, and 60 cortical (20 x 3) screws from those of groups were implanted in cortical femurs to observe the effect of HA and interlayer on screws. Results show that as an alternative to plasma spray coating method, the EPD process enables to produce a quick, easy, cheap and uniform adjustable coating layer. Also from biomechanical and SEM examinations, HA coating by EPD method of cortical screws resulted in extremely improved fixation with reduced risk of loosening problem. PMID:15694605

Yildirim, O S; Aksakal, B; Celik, H; Vangolu, Y; Okur, A

2005-04-01

73

A review of tip apex distance in dynamic hip screw fixation of osteoporotic hip fractures  

PubMed Central

Fractured neck of femur is a common problem seen in elderly osteoporotic females, mostly in Western countries, among which are the extra-capsular fractures such as intertrochanteric and pertrochanteric fractures also known as peritrochanteric fractures, and commonly treated with dynamic hip screw (DHS) or compression hip screw (CHS). The DHS is based on tension band principle and allows the screw to slide within the barrel to enable compression of the fracture when the patient begins to bear weight. This principle only works in the presence of intact medial wall and so cannot be successful in a reverse oblique fracture of the proximal femur. However, it is important that the technique of screw placement is precise and should ideally be central in the femoral neck, on both AP and lateral radiographs. This is why the concept of tip apex distance (TAD) is critical to the outcome of fixation and can accurately predict failure or survival of the screw. A systematic review of articles published in PubMed/Medline, from 1991 to 2011 (twenty years), was carried out to critically analyse common practice with regards to DHS fixation of extra-capsular femoral neck fractures, and review the recommendations of previous authors, with regard to the effect of TAD in DHS fixation. Search words used include TAD, DHS, sliding hip screw, femoral neck fractures, peritrochanteric fractures, tension band principle, fracture collapse, screw cut-out, DHS failure, and failure of fixation. At the end of the review, recommendations and suggestions regarding the ideal techniques of placement of DHS screw into the femoral neck will be made in line with current published literature, in order to establish an evidence base for best practice. A total of forty eight (48) published articles were found relevant to the review topic. Most papers suggested that Tip Apex Distance (TAD) is the most important predictive factor for DHS failure, followed by lag screw position, fracture pattern and reduction, patient's age and presence of osteoporosis. Therefore, we recommend proper training of surgeons, as well as attention to detail while performing DHS for intertrochanteric neck of femur fractures.

Abdulkareem, Imran Haruna

2012-01-01

74

Efficacy of reverse triangle screw fixation in patients suffering from femoral neck fractures.  

PubMed

Although the fractures of femoral neck are not so common, their accompanying complications are more frequent and important. This research aims at studying the results of reverse triangle screw fixation in patients suffering from femoral neck fractures in two groups with perfect and imperfect position of the mentioned screw. In a cohort study, 51 patients with femoral neck fracture appointed for the so-called reverse triangle screw fixation were divided into two perfect and imperfect groups considering surgeon comment on position of the screws. The patients were followed up for 12 months and the resulted outcomes were compared. There were 34 patients in the perfect group with mean age of 48.7 +/- 18.6 (18-80) and 17 patients in the imperfect group with mean age of 50.4 +/- 15.9 (19-80) years old. Both groups were the same considering underlying causes and fraction grades. The overall frequency of nonunion and avascular necrosis was 7.8 and 3.9%, respectively. These rates were 2.9 and 0% in the perfect group and 17.6 and 12.5% in the imperfect group, respectively (p > 0.05). The mean Harris hip score and motion range of the hip at different directions in the perfect group were substantially higher than those of the imperfect one. According to present results, position of the screws determined by the surgeon after operating the reverse triangle screw fixation in femoral neck fractures may significantly affect the prognosis of patients. PMID:24199470

Sales, Jafar Ganjpour; Soleymaopour, Jafar; Sadeghpour, Alireza; Sharifi, Shabnam; Rouhani, Shahin; Goldust, Mohamad

2012-04-15

75

Acromioclavicular Joint Fixation Using an Acroplate Combined With a Coracoclavicular Screw  

PubMed Central

Background Appropriate treatment of acromioclavicular joint dislocation is controversial. Acroplate fixation is one of the most common treatment methods of acromioclavicular joint (ACJ) dislocation. Based on the risk of re-dislocation after Acroplate fixation, we assumed that combined fixation with an Acroplate and a coracoclavicular screw helps improve the outcome. Objectives The main purpose of the current study was to compare the outcome of ACJ dislocation treated with an Acroplate alone and in combination with coracoclavicular screw. Patients and Methods This study was carried out on 40 patients with ACJ dislocation types III to VI who were divided randomly into two equal groups: Acroplate group (P) and Acroplate in combination with coracoclavicular screw group (P + S). The screws were extracted 3-6 months postoperatively. The patients were followed for 1 year and Imatani’s score was calculated. Finally, the data were compared between the groups. Results The mean Imatani’s score was significantly higher in P + S group (83.4 ± 14.1) than P group (81.2 ± 10.3) (P < 0.001). The mean duration of surgery was the same in the two groups (59.8 ± 9.4 minutes in group P V.s 64.3 ± 10.9 minutes in group P + S; P = 0.169). There were no cases of re-dislocation, degenerative changes and ossification and all patients returned to their previous jobs or sporting activities. Conclusions Using a coracoclavicular screw combined with an Acroplate can improve the patients’ function after ACJ disruption without any significant increase in surgical duration. Authors recommend this technique in the fixation of ACJ dislocation.

Tavakoli Darestani, Reza; Ghaffari, Arash; Hosseinpour, Mehrdad

2013-01-01

76

Transarticular screw fixation for atlantoaxial instability - modified Magerl's technique in 38 patients  

PubMed Central

Background Symptomatic atlantoaxial instability needs stabilization of the atlantoaxial joint. Among the various techniques described in literature for the fixation of atlantoaxial joint, Magerl's technique of transarticular screw fixation remains the gold standard. Traditionally this technique combines placement of transarticular screws and posterior wiring construct. The aim of this study is to evaluate clinical and radiological outcomes in subjects of atlantoaxial instability who were operated using transarticular screws and iliac crest bone graft, without the use of sublaminar wiring (a modification of Magerl's technique). Methods We evaluated retrospectively 38 subjects with atlantoaxial instability who were operated at our institute using transarticular screw fixation. The subjects were followed up for pain, fusion rates, neurological status and radiographic outcomes. Final outcome was graded both subjectively and objectively, using the scoring system given by Grob et al. Results Instability in 34 subjects was secondary to trauma, in 3 due to rheumatoid arthritis and 1 had tuberculosis. Neurological deficit was present in 17 subjects. Most common presenting symptom was neck pain, present in 35 of the 38 subjects. Postoperatively residual neck and occipital pain was present in 8 subjects. Neurological deficit persisted in only 7 subjects. Vertebral artery injury was seen in 3 subjects. None of these subjects had any sign of neurological deficit or vertebral insufficiency. Three cases had nonunion. At the latest follow up, subjectively, 24 subjects had good result, 6 had fair and 8 had bad result. On objective grading, 24 had good result, 11 had fair and 3 had bad result. The mean follow up duration was 41 months. Conclusions Transarticular screw fixation is an excellent technique for fusion of the atlantoaxial complex. It provides highest fusion rates, and is particularly important in subjects at risk for nonunion. Omitting the posterior wiring construct that has been used along with the bone graft in the traditional Magerl' s technique achieves equally good fusion rates and is an important modification, thereby avoiding the complications of sublaminar wire passage.

2010-01-01

77

Alendronate treatment improves bone–pedicle screw interface fixation in posterior lateral spine fusion: An experimental study in a porcine model  

Microsoft Academic Search

The bone–screw interface has been indicated as the weak link in pedicle screw spine fixation. Bisphosphonate treatment may\\u000a have the effect of improving bone–screw interface fixation in spine fusion by inhibiting bone resorption. An experimental\\u000a study was conducted using a porcine model to evaluate the influence of alendronate treatment on bone–pedicle screw interface\\u000a fixation. Eleven pigs in the treatment group

Qingyun Xue; Haisheng Li; Xuenong Zou; Michel Dalstra; Martin Lind; Finn B. Christensen; Cody Bünger

2010-01-01

78

Posterior interbody fusion using a diagonal cage with unilateral transpedicular screw fixation for lumbar stenosis.  

PubMed

Few reports have described the combined use of unilateral pedicle screw fixation and interbody fusion for lumbar stenosis. We retrospectively reviewed 79 patients with lumbar stenosis. The rationale and effectiveness of unilateral pedicle screw fixation were studied from biomechanical and clinical perspectives, aiming to reduce stiffness of the implant. All patients were operated with posterior interbody fusion using a diagonal cage in combination with unilateral transpedicular screw fixation and had reached the 3-year follow-up interval after operation. The mean operating time was 115 minutes (range=95-150 min) and the mean estimated blood loss was 150 mL (range=100-200 mL). The mean duration of hospital stay was 10 days (range=7-15 days). Clinical outcomes were assessed prior to surgery and reassessed at intervals using Denis' pain and work scales. Fusion status was determined from X-rays and CT scans. At the final follow-up, the clinical results were satisfactory and patients showed significantly improved scores (p<0.01) either on the pain or the work scale. Successful fusion was achieved in all patients. There were no new postoperative radiculopathies, or instances of malpositioned or fractured hardware. Posterior interbody fusion using a diagonal cage with unilateral transpedicular fixation is an effective treatment for decompressive surgery for lumbar stenosis. PMID:21237659

Zhao, Jian; Zhang, Feng; Chen, Xiaoqing; Yao, Yu

2011-03-01

79

Evaluation of a new approach for modelling the screw-bone interface in a locking plate fixation: a corroboration study.  

PubMed

Computational modelling of the screw-bone interface in fracture fixation constructs is challenging. While incorporating screw threads would be a more realistic representation of the physics, this approach can be computationally expensive. Several studies have instead suppressed the threads and modelled the screw shaft with fixed conditions assumed at the screw-bone interface. This study assessed the sensitivity of the computational results to modelling approaches at the screw-bone interface. A new approach for modelling this interface was proposed, and it was tested on two locking screw designs in a diaphyseal bridge plating configuration. Computational models of locked plating and far cortical locking constructs were generated and compared to in vitro models described in prior literature to corroborate the outcomes. The new approach led to closer agreement between the computational and the experimental stiffness data, while the fixed approach led to overestimation of the stiffness predictions. Using the new approach, the pattern of load distribution and the magnitude of the axial forces, experienced by each screw, were compared between the locked plating and far cortical locking constructs. The computational models suggested that under more severe loading conditions, far cortical locking screws might be under higher risk of screw pull-out than the locking screws. The proposed approach for modelling the screw-bone interface can be applied to any fixation involved application of screws. PMID:23636756

Moazen, Mehran; Mak, Jonathan H; Jones, Alison C; Jin, Zhongmin; Wilcox, Ruth K; Tsiridis, Eleftherios

2013-07-01

80

USE OF RESORBABLE SCREWS FOR AUTOGENOUS ONLAY BLOCK GRAFT FIXATION: A HISTOLOGICAL ANALYSIS IN RABBITS.  

PubMed

Abstract Purpose:The aim of the present in vivo study is to histologically evaluate and compare the use of resorbable screws based on poli(L-co-D,L lactide) 70:30 for fixation of autogenous bone grafts in rabbit tibiae. Materials and Methods: as control group, titanium (Ti-6Al-4V Grade V) screws were used. For this purpose, fifteen white New Zeland male rabbits, with age of 6 months and weight between 3.8 - 4.5kg were used. From each animal, 2 total thickness bone grafts were removed from the cranial vault was stabilized with a resorbable screw while the other was stabilized with a metallic one. Animals were divided into 3 groups, according to the sacrifice period: 3, 8 and 16 weeks postoperatively. After histological processing, cuts were stained with hematoxilin and eosin and submitted for descriptive histological analysis under light microscopy. Results: it was found that the fixation system based on the polymer showed a histological behavior similar to metallic screws. For both groups the bone graft was incorporated, with the presence of bone formation between the graft and receptor site. In none of the groups were undesirable inflammatory responses or foreign body reactions observed. Conclusions: based on histological findings and on this experimental model it is possible to conclude that the internal fixation system based on the poli(L-co-D,L lactide) 70:30 polymer is effective for fixation of autogenous bone grafts, with results that are comparable to the titanium fixation system. PMID:23414521

Klüppel, Leandro E; Stabile, Glaykon Alex Vitti; Antonini, Fernando; Nascimento, Frederico Felipe; de Moraes, Márcio; Mazzonetto, Renato

2013-02-15

81

Relative stability of tension band versus two-cortex screw fixation for treating fifth metatarsal base avulsion fractures.  

PubMed

This study assesses the strength of fixating avulsion fractures of the fifth metatarsal base with a 4.0-mm partially threaded cancellous screw crossing two cortices as compared to tension banding. Our data showed statistically significant fixation strength improvement over tension banding for avulsion fractures (p < 0.02) in both polystyrene foam models and fresh, nonpreserved frozen cadaveric samples. In cadavers, the screw fixations were able to withstand more than three times the load sustained by the tension band fixations. The study utilized the Instron 8500 tensiometer to apply physiologic loads to test the constructs until failure. The displacement and load data at failure show the limitations of both fixations. By increasing the load resistance while maintaining compression, the bicortical cancellous screw fixation created greater stability at the avulsion fracture of the fifth metatarsal base as compared to tension band stabilization. PMID:10789099

Husain, Z S; DeFronzo, D J

2000-01-01

82

A Comparison of Functional Outcomes After Metallic and Bioabsorbable Interference Screw Fixations in Arthroscopic ACL Reconstructions  

PubMed Central

Introduction: Anterior Cruciate Ligament (ACL) is as one of the most frequently injured ligaments in the modern contact sports scenario. Graft fixations can be achieved during anterior cruciate ligament (ACL) reconstructions by using either bioabsorbable screws or metal screws. The objective of this study was to compare the functional outcomes after bioabsorbable and metallic interference screw fixations in arthroscopic anterior cruciate ligament reconstructions done by using hamstring grafts. Materials and Methods: This was a prospective, randomized study. Patients in Group 1 received bioabsorbable interference screws and patients in Group 2 received metallic interference screws. Arthroscopic assisted, anterior cruciate ligament reconstructions with the use of hamstring grafts which were fixed proximally with endobuttons and distally with bioabsorbable or metallic interference screws, were undertaken. Progress in functional outcomes was assessed by using Mann Whitney U- test. Functional outcomes in the two groups were compared by using independent t-test. Observation and Results: In each group, there were statistically significant improvements in functional outcomes over successive follow-ups, which were seen on basis on Mann-Whitney U-test. The comparison of functional outcomes between the two groups, done by using independent t-test, showed no statistically significant differences between the two groups at 3 months, 6 months and 1 year of follow-up. p-value <0.05 was considered to be significant in our study. Conclusion: In our prospective study of comparison of functional outcomes between bioabsorbable and metallic interference screws in arthroscopic anterior cruciate ligament reconstuctions, which were evaluated by using Tegner activity scale and Lysholm knee scoring scale for a period of 1 year, no statistically significant difference was found. However, further authentication is required by doing long term studies.

Rai, Deepak K; Kannampilly, Antony J

2014-01-01

83

Treatment of thoracolumbar vertebrate fracture by transpedicular morselized bone grafting in vertebrae for spinal fusion and pedicle screw fixation  

Microsoft Academic Search

Summary  To enhance the fusion of graft bone in thoracolumbar vertebrae and minimize the postoperative loss of correction, short-segment\\u000a pedicle screw fixation was reinforced with posterior moselizee bone grafting in vertebrae for spinal fusion in patients with\\u000a thoracrolumbar vertebrate fractures. Seventy patients with thoracrolumbar vertebrate fractures were treated by short-segment\\u000a pedicle screw fixation and were randomly divided into two groups. Fractures

Jinguo Wang; Hua Wu; Xiaolin Ding; Yutian Liu

2008-01-01

84

Retrograde nailing with subsequent screw fixation for ipsilateral femoral shaft and neck fractures  

Microsoft Academic Search

Introduction\\u000a   Although ipsilateral femoral shaft and neck fractures are difficult to treat, there is still no consensus on the optimal treatment of this complex injury. We report the results of treating the 17 fractures with a standard protocol of retrograde nailing for diaphyseal fractures and subsequent screw fixation for the femoral neck fractures.\\u000a Materials and methods\\u000a   Seventeen injuries (16 patients)

Chang-Wug Oh; Jong-Keon Oh; Byung-Chul Park; In-Ho Jeon; Hee-Soo Kyung; Shin-Yoon Kim; Il-Hyung Park; Oog-Jin Sohn; Woo-Kie Min

2006-01-01

85

Chitosan-coated Stainless Steel Screws for Fixation in Contaminated Fractures  

Microsoft Academic Search

Stainless steel screws and other internal fixation devices are used routinely to stabilize bacteria-contaminated bone fractures\\u000a from multiple injury mechanisms. In this preliminary study, we hypothesize that a chitosan coating either unloaded or loaded\\u000a with an antibiotic, gentamicin, could lessen or prevent these devices from becoming an initial nidus for infection. The questions\\u000a investigated for this hypothesis were: (1) how

Alex H. Greene; Joel D. Bumgardner; Yunzhi Yang; Jon Moseley; Warren O. Haggard

2008-01-01

86

Targeting a Safe Entry Point for C2 Pedicle Screw Fixation in Patients with Atlantoaxial Instability  

PubMed Central

Objective This investigation was conducted to evaluate a new, safe entry point for the C2 pedicle screw, determined using the anatomical landmarks of the C2 lateral mass, the lamina, and the isthmus of the pars interarticularis. Methods Fifteen patients underwent bilateral C1 lateral mass-C2 pedicle screw fixation, combined with posterior wiring. The C2 pedicle screw was inserted at the entry point determined using the following method : 4 mm lateral to and 4 mm inferior to the transitional point (from the superior end line of the lamina to the isthmus of the pars interarticularis). After a small hole was made with a high-speed drill, the taper was inserted with a 30 degree convergence in the cephalad direction. Other surgical procedures were performed according to Harm's description. Preoperatively, careful evaluation was performed with a cervical X-ray for C1-C2 alignment, magnetic resonance imaging for spinal cord and ligamentous structures, and a contrast-enhanced 3-dimensional computed tomogram (3-D CT) for bony anatomy and the course of the vertebral artery. A 3-D CT was checked postoperatively to evaluate screw placement. Results Bone fusion was achieved in all 15 patients (100%) without screw violation into the spinal canal, vertebral artery injury, or hardware failure. Occipital neuralgia developed in one patient, but this subsided after a C2 ganglion block. Conclusion C2 transpedicular screw fixation can be easily and safely performed using the entry point of the present study. However, careful preoperative radiographic evaluation, regardless of methods, is mandatory.

Chun, Hyoung-Joon

2011-01-01

87

Bisphosphonate coating on titanium screws increases mechanical fixation in rat tibia after two weeks.  

PubMed

Recently published data indicate that immobilized N-bisphosphonate enhances the pullout force and energy uptake of implanted stainless steel screws at 2 weeks in rat tibia. This study compares titanium screws with and without a bisphosphonate coating in the same animal model. The screws were first coated with an approximately 100-nm thick crosslinked fibrinogen film. Pamidronate was subsequently immobilized into this film via EDC/NHS-activated carboxyl groups within the fibrinogen matrix, and finally another N-bisphosphonate, ibandronate, was physically adsorbed. The release kinetics of immobilized (14)C-alendronate was measured in buffer up to 724 h and showed a 60% release within 8 h. Mechanical tests demonstrated a 32% (p = 0.04) and 48% (p = 0.02) larger pullout force and energy until failure after 2 weeks of implantation, compared to uncoated titanium screws. A control study with physically adsorbed pamidronate showed no effect on mechanical fixation, probably due to a too small adsorbed amount. We conclude that the fixation of titanium implants in bone can be improved by fibrinogen matrix-bound bisphosphonates. PMID:17975821

Wermelin, Karin; Aspenberg, Per; Linderbäck, Paula; Tengvall, Pentti

2008-07-01

88

Bilateral C1 laminar hooks combined with C2 pedicle screws fixation for treatment of C1-C2 instability not suitable for placement of transarticular screws.  

PubMed

The study design described here is a posterior C1-C2 fusion technique composed of bilateral C1 hooks and C2 pedicle screws. In addition, the clinical results of using this method on 13 patients with C1-C2 instability are reported. The objectives are to introduce a new technique for posterior C1-C2 fusion and to evaluate the clinical outcome of using it to treat C1-C2 instability. From October 2006 to August 2008, 13 patients (9 men and 4 women) with C1-C2 instability were included in this study: 3 had acute odontoid fractures, 4 had obsolete odontoid fractures, 4 had os odontoideum and 2 had traumatic rupture of the transverse ligament. All patients underwent posterior atlantoaxial fixation with bilateral C1 hooks and C2 pedicle screws. The mean follow-up duration was 25 months (range 13-30 months). Each patient underwent a complete cervical radiograph series, including anterior-posterior, lateral, and flexion-extension views, and a computed tomographic scan. The clinical course was evaluated according to the Frankel grading system. No clinically manifested injury of the nerve structures or the vertebral artery was observed in any of these cases. Five patients with neurological symptoms showed significant improvement in neurological function postoperatively. Bony fusion and construction stability were observed in all 13 patients (100%) on their follow-up radiographs, and no instrument failure was observed. Bilateral C1 hooks combined with C2 pedicle screws can be used as an alternative treatment method for C1-C2 dislocation, especially in cases not suitable for the use of transarticular screws. The clinical follow-up shows that this technique is a safe and effective method of treatment. PMID:20229279

Ni, Bin; Zhu, Zhuangchen; Zhou, Fengjin; Guo, Qunfeng; Yang, Jian; Liu, Jun; Wang, Fei

2010-08-01

89

Bilateral C1 laminar hooks combined with C2 pedicle screws fixation for treatment of C1-C2 instability not suitable for placement of transarticular screws  

PubMed Central

The study design described here is a posterior C1–C2 fusion technique composed of bilateral C1 hooks and C2 pedicle screws. In addition, the clinical results of using this method on 13 patients with C1–C2 instability are reported. The objectives are to introduce a new technique for posterior C1–C2 fusion and to evaluate the clinical outcome of using it to treat C1–C2 instability. From October 2006 to August 2008, 13 patients (9 men and 4 women) with C1–C2 instability were included in this study: 3 had acute odontoid fractures, 4 had obsolete odontoid fractures, 4 had os odontoideum and 2 had traumatic rupture of the transverse ligament. All patients underwent posterior atlantoaxial fixation with bilateral C1 hooks and C2 pedicle screws. The mean follow-up duration was 25 months (range 13–30 months). Each patient underwent a complete cervical radiograph series, including anterior–posterior, lateral, and flexion–extension views, and a computed tomographic scan. The clinical course was evaluated according to the Frankel grading system. No clinically manifested injury of the nerve structures or the vertebral artery was observed in any of these cases. Five patients with neurological symptoms showed significant improvement in neurological function postoperatively. Bony fusion and construction stability were observed in all 13 patients (100%) on their follow-up radiographs, and no instrument failure was observed. Bilateral C1 hooks combined with C2 pedicle screws can be used as an alternative treatment method for C1–C2 dislocation, especially in cases not suitable for the use of transarticular screws. The clinical follow-up shows that this technique is a safe and effective method of treatment.

Zhu, Zhuangchen; Zhou, Fengjin; Guo, Qunfeng; Yang, Jian; Liu, Jun; Wang, Fei

2010-01-01

90

Safety screw fixation technique in a case of coracoid base fracture with acromioclavicular dislocation and coracoid base cross-sectional size data from a computed axial tomography study.  

PubMed

Coracoid base fracture accompanied by acromioclavicular joint dislocation with intact coracoclavicular ligaments is a rare injury. Generally, an open reduction with screw fixation is the first treatment choice, as it protects the important structures around the coracoid process. This report presents a new technique of screw fixation for coracoid base fracture and provides anatomic information on cross-sectional size of the coracoid base obtained by computed tomography (CT). An axial image of the coracoid base was visualized over the neck of the scapula, and a guidewire was inserted into this circle under fluoroscopic guidance. The wire was inserted easily into the neck of scapula across the coracoid base fracture with imaging in only 1 plane. In addition, 25 measurements of the coracoid base were made in 25 subjects on axial CT images. Average length of the long and short axes at the thinnest part of the coracoid base was 13.9 ± 2.0 mm (range 10.6-17.0) and 10.5 ± 2.2 mm (6.6-15.1), respectively. This new screw fixation technique and measurement data on the coracoid base may be beneficial for safety screw fixation of coracoid base fracture. PMID:24770936

Kawasaki, Yoshiteru; Hirano, Tetsuya; Miyatake, Katsutoshi; Fujii, Koji; Takeda, Yoshitsugu

2014-07-01

91

Tibial Inlay Press-fit Fixation Versus Interference Screw in Posterior Cruciate Ligament Reconstruction  

PubMed Central

Reconstruction of the posterior cruciate ligament (PCL) by a tibial press-fit fixation of the patellar tendon with an accessory bone plug is a promising approach because no foreign materials are required. Until today, there is no data about the biomechanical properties of such press-fit fixations. The aim of this study was to compare the biomechanical qualities of a bone plug tibial inlay technique with the commonly applied interference screw of patellar tendon PCL grafts. Twenty patellar tendons including a bone block were harvested from ten human cadavers. The grafts were implanted into twenty legs of adult German country pigs. In group P, the grafts were attached in a press-fit technique with accessory bone plug. In group S, the grafts were fixed with an interference screw. Each group consisted of 10 specimens. The constructs were biomechanically analyzed in cyclic loading between 60 and 250 N for 500 cycles recording elongation. Finally, ultimate failure load and failure mode were analyzed. Ultimate failure load was 598.6±36.3 N in group P and 653.7±39.8 N in group S (not significant, P>0.05). Elongation during cyclic loading between the 1st and the 20th cycle was 3.4±0.9 mm for group P and 3.1±1 mm for group S. Between the 20th and the 500th cycle, elongation was 4.2±2.3 mm in group P and 2.5±0.9 mm in group S (not significant, P>0.05). This is the first study investigating the biomechanical properties of tibial press-fit fixation of the patellar tendon with accessory bone plug in posterior cruciate ligament reconstruction. The implant-free tibial inlay technique shows equal biomechanical characteristics compared to an interference screw fixation. Further in vivo studies are desirable to compare the biological behavior and clinical relevance of this fixation device.

Ettinger, Max; Buermann, Sarah; Calliess, Tilman; Omar, Mohamed; Krettek, Christian; Hurschler, Christof; Jagodzinski, Michael; Petri, Maximilian

2013-01-01

92

In situ screw fixation of slipped capital femoral epiphysis with a novel approach: a double-cohort controlled study  

PubMed Central

Purpose In situ fixation for mild to moderate slipped capital femoral epiphysis (SCFE) remains an acceptable treatment methodology in most centers. Satisfactory fixation results have been reported with the procedure using either the fracture table or radiolucent table, both of which allow the hip to be imaged during the procedure. The position of the pin within the center of the femoral head is important to secure adequate fixation of the capital femoral epiphysis and prevent further slippage with minimal risk for articular penetration and avascular necrosis (AVN) or chondrolysis. Methods We describe a pre-operative planning technique to determine the pin-entry point for percutaneous pinning of SCFE on a radiolucent operating table. A retrospective review of patients who underwent in situ screw fixation with the usage of a cannulated screw on a radiolucent table or fracture table over a 6-year period was conducted. Results The pin-entry point with this technique was reliable in 92% of procedures and comparable in both accuracy and complications to in situ screw fixation on a fracture table. In situ screw fixation on a regular radiolucent table was straightforward and required significantly less surgical time than on the fracture table (P = 0.01). It was also more efficient during a bilateral procedure, as it required only a single preparation and draping of the patient. Conclusion This pre-operative planning technique for deciding the starting point on the proximal femur is helpful in executing an accurate in situ screw fixation of hips with SCFE.

Pring, Maya E.; Adamczyk, Mark; Hosalkar, Harish S.; Bastrom, Tracey P.; Wallace, C. Douglas

2010-01-01

93

the Targon femoral neck hip screw versus cannulated screws for internal fixation of intracapsular fractures of the hip: a randomised controlled trial.  

PubMed

We compared a new fixation system, the Targon Femoral Neck (TFN) hip screw, with the current standard treatment of cannulated screw fixation. This was a single-centre, participant-blinded, randomised controlled trial. Patients aged 65 years and over with either a displaced or undisplaced intracapsular fracture of the hip were eligible. The primary outcome was the risk of revision surgery within one year of fixation. A total of 174 participants were included in the trial. The absolute reduction in risk of revision was of 4.7% (95% CI 14.2 to 22.5) in favour of the TFN hip screw (chi-squared test, p = 0.741), which was less than the pre-specified level of minimum clinically important difference. There were no significant differences in any of the secondary outcome measures. We found no evidence of a clinical difference in the risk of revision surgery between the TFN hip screw and cannulated screw fixation for patients with an intracapsular fracture of the hip. PMID:24788501

Griffin, X L; Parsons, N; Achten, J; Costa, M L

2014-05-01

94

Surface immobilized zoledronate improves screw fixation in rat bone: A new method for the coating of metal implants  

Microsoft Academic Search

Previous studies show that surface immobilized bisphosphonates improve the fixation of stainless steel screws in rat tibia\\u000a after 2–8 weeks of implantation. We report here about the immobilization of a potent bisphosphonate, zoledronate, to crosslinked\\u000a fibrinogen by the use of another technique, i.e. ethyl-dimethyl-aminopropylcarbodiimide (EDC)\\/imidazole immobilization. Bone\\u000a fixation of zoledronate-coated screws was compared to screws coated with crosslinked fibrinogen only and

Therese AnderssonFredrik Agholme; Fredrik Agholme; Per Aspenberg; Pentti Tengvall

2010-01-01

95

All-Arthroscopic Suprapectoral Long Head of Biceps Tendon Tenodesis With Interference Screw-Like Tendon Fixation After Modified Lasso-Loop Stitch Tendon Securing  

PubMed Central

Arthroscopic suprapectoral techniques for tenodesis of the long head of the biceps tendon (LHB) are appropriate for the treatment of proximal biceps lesions. Several types of techniques and fixation devices have been described and evaluated in biomechanical studies regarding primary stability. In this technical note, we describe an all-arthroscopic suprapectoral technique using the 6.25-mm Bio-SwiveLock device (Arthrex, Naples, FL) for an interference screw–like bony fixation after having armed the tendon with a lasso-loop stitch. Both the interference screw fixation and securing of the lasso-loop tendon have been well described and approved in biomechanical tests concerning the primary stability. One advantage of this technique performed from the glenohumeral space, in addition to the strong and secure fixation with ingrowth of the tendon in a bony canal, is the avoidance of touching the soft tissue above the bicipital groove, which results in a smooth fitting of the tendon into its natural canal and therefore avoids mechanical irritation of the stump at the rotator interval. In conclusion, the all-arthroscopic suprapectoral LHB tenodesis performed from the glenohumeral space with the modified lasso-loop stitch for securing of the tendon and the 6.25-mm Bio-SwiveLock suture anchor for interference screw–like bony tendon fixation is an appropriate technique for the treatment of LHB-associated lesions.

Patzer, Thilo; Kircher, Jorn; Krauspe, Ruediger

2012-01-01

96

Unilateral Posterior Atlantoaxial Transarticular Screw Fixation in Patients with Atlantoaxial Instability : Comparison with Bilateral Method  

PubMed Central

Objective Bilateral C1-2 transarticular screw fixation (TAF) with interspinous wiring has been the best treatment for atlantoaxial instability (AAI). However, several factors may disturb satisfactory placement of bilateral screws. This study evaluates the usefulness of unilateral TAF when bilateral TAF is not available. Methods Between January 2003 and December 2007, TAF was performed in 54 patients with AAI. Preoperative studies including cervical x-ray, three dimensional computed tomogram, CT angiogram, and magnetic resonance image were checked. The atlanto-dental interval (ADI) was measured in preoperative period, immediate postoperatively, and postoperative 1, 3 and 6 months. Results Unilateral TAF was performed in 27 patients (50%). The causes of unilateral TAF were anomalous course of vertebral artery in 20 patients (74%), severe degenerative arthritis in 3 (11%), fracture of C1 in 2, hemangioblastoma in one, and screw malposition in one. The mean ADI in unilateral group was measured as 2.63 mm in immediate postoperatively, 2.61 mm in 1 month, 2.64 mm in 3 months and 2.61 mm in 6 months postoperatively. The mean ADI of bilateral group was also measured as following; 2.76 mm in immediate postoperative, 2.71 mm in 1 month, 2.73 mm in 3 months, 2.73 mm in 6 months postoperatively. Comparison of ADI measurement showed no significant difference in both groups, and moreover fusion rate was 100% in bilateral and 96.3% in unilateral group (p=0.317). Conclusion Even though bilateral TAF is best option for AAI in biomechanical perspectives, unilateral screw fixation also can be a useful alternative in otherwise dangerous or infeasible cases through bilateral screw placement.

Hue, Yun Hee; Yi, Hyeong-Joong; Oh, Seong Hoon; Oh, Suck Jun; Ko, Yong

2009-01-01

97

Biomechanical evaluation of a new system to improve screw fixation in osteoporotic bones.  

PubMed

In this paper an experimental analysis is undertaken of the affect a new screw-to-bone fixation system has on the stiffness of fixation systems of osteoporotic fractures based on osteosynthesis plates. The proposed system, which we have named the screw locking element (SLE), is made with elements manufactured from a biocompatible polymer material known as polyetheretherketon (PEEK) which act like a lock nut, holding the end of the threaded screw shank after this has passed through both bone corticals. Seventy-two osteoporotic synbone simulated fracture models were instrumented with one of four constructs: locking compression plate with 6 locking screws (LCP), dynamic compression plate with 6 cortical screws (DCP), DCP with 2 SLEs or DCP with 6 SLEs (DCP+6SLEs). Each group of 18 simulated fracture models were further split into 3 subgroups of 6. One subgroup was tested under cyclic cantilever bending, another under cyclic compression and the third under cyclic torsion. Loss of stiffness was determined in each test every 1,000 load cycles, between 0 and 30,000 cycles. Regardless of the load type, it was seen that the DCP system had the highest stiffness loss percentages of all the tested systems. The inclusion of SLEs significantly decreased the stiffness loss of the DCP system. Unlike the cyclic compression loads, where the LCP performed slightly better, on terminating the cantilever bending and torsion load cycles no statistically significant difference was noted (Tukey test, p>0.05) between the percentage stiffness loss of the DCP+6SLEs system and the LCP system. It is concluded that the proposed SLEs enable DCPs to lower the high failure rate that these exhibit in osteoporotic fracture repairs, at significantly lower costs than those resulting from the use of LCPs. PMID:20227321

Yánez, A; Carta, J A; Garcés, G

2010-06-01

98

Multifragmentary Tibial Pilon Fractures: Midterm Results After Osteosynthesis with External Fixation and Multiple Lag Screws  

PubMed Central

Osteosynthesis of intraarticular tibial pilon fractures is preferably achieved using locking plates via a minimally invasive technique. If combined with severe soft tissue damage there is a high risk of wound-healing deficits after plate osteosynthesis. Thus our aim was to find an alternative method of treatment for those cases with combined soft tissue injuries. We report on five cases with comminuted fractures of the joint surface combined with critical soft tissue condition that were treated with lag screws and external fixation (AO) applied across the ankle joint. All five patients were followed up, undergoing clinical and radiological examination. Using this approach we achieved fracture healing of comminuted fractures without further complications. Clinical follow-up after an average of 55.6 (36–75) months revealed a mean AOFAS score of 81 (62–100). We therefore propose combined treatment using lag screws with external fixation as a practical treatment option for those fractures for which lag screws combined with a locking plate are not feasible or when there is a high risk of wound-healing deficits due to severe soft tissue damage.

Kiene, Johannes; Herzog, Jan; Jurgens, Christian; Paech, Andreas

2012-01-01

99

Radiostrontium clearance and bone formation in response to simulated internal screw fixation  

SciTech Connect

Changes in radiostrontium clearance (SrC) and bone formation (tetracycline labeling) were observed in the femurs of skeletally mature dogs following the various operative steps involved in bone screw fixation. Drilling, but not periosteal stripping, produced a small but statistically significant increase in SrC and endosteal bone formation in the distal third of the bone. Strontium clearance values equivalent to those produced by drilling alone were recorded after screw fixation at low or high torque (5 versus 20 inch pounds), as well as by the insertion of loosely fitting stainless steel implants. Bone formation (equals the percentage tetracycline-labeled trabecular bone surfaces) was increased by 30% when SrC values exceeded 3.5 ml/100 g bone/min, and the relationship was linear when SrC values ranged between 1.0 and 7.0 ml/100 g bone/min. The changes in SrC and bone formation one-week after bone screw application are primarily those associated with a response to local trauma caused by drilling.

Daum, W.J.; Simmons, D.J.; Fenster, R.; Shively, R.A.

1987-06-01

100

Lumbosacral Fixation Using the Diagonal S2 Screw for Long Fusion in Degenerative Lumbar Deformity: Technical Note Involving 13 Cases  

PubMed Central

Placing instrumentation into the ilium has been shown to increase the biomechanical stability and the fusion rates, but it has some disadvantages. The diagonal S2 screw technique is an attractive surgical procedure for degenerative lumbar deformity. Between 2008 and 2010, we carried out long fusion across the lumbosacral junction in 13 patients with a degenerative lumbar deformity using the diagonal S2 screws. In 12 of these 13 patients, the lumbosacral fusion was graded as solid fusion with obvious bridging bone (92%). One patient had a rod dislodge at one S2 screw and breakage of one S1 screw and underwent revision nine months postoperatively. So, we present alternative method of lumbopelvic fixation for long fusion in degenerative lumbar deformity using diagonal S2 screw instead of iliac screw.

Kim, Hong-Sik; Baek, Seung-Wook; Lee, Sang-Hyun

2013-01-01

101

Morphometry of the cervical vertebral pedicles as a guide for transpedicular screw fixation.  

PubMed

Anatomical measurements of the cervical pedicle in a large series of human cervical vertebrae from 48 individuals were obtained to reduce the incidence and severity of complications caused by transpedicular screw placement. The greatest pedicle length was at C-3 and the greatest pedicle width was at C-6. Pedicle width and lateral mass thickness gradually increased from C-3 to C-6. Pedicle height and interpedicular distance increased from C-3 to C-5, and decreased slightly at C-6. The lateral mass-pedicle length was greatest at C-4. The present study found right-left differences for the pedicle-spinous process distance at C-6 (p < 0.05). Pedicle width and height were smaller than those reported in earlier studies, especially at C-3 and C-4, whereas the increasing pedicle widths at C-5 and C-6 were appropriate for pedicle screw fixation. PMID:17384491

Kayalioglu, Gulgun; Erturk, Mete; Varol, Tuncay; Cezayirli, Enis

2007-03-01

102

Cervical anterior transpedicular screw fixation (ATPS)--Part II. Accuracy of manual insertion and pull-out strength of ATPS.  

PubMed

Reconstruction after multilevel decompression of the cervical spine, especially in the weakened osteoporotic, neoplastic or infectious spine often requires circumferential stabilization and fusion. To avoid the additional posterior surgery in these cases while increasing rigidity of anterior-only screw-plate constructs, the authors introduce the concept of anterior transpedicular screw (ATPS) fixation. We demonstrated its morphological feasibility as well as its indications in a previous study in Part I of our project. Consequently, the objectives of the current study were to assess the ex vivo accuracy of placing ATPS into the cervical vertebra as well as the biomechanical performance of ATPS in comparison to traditional vertebral body screws (VBS) in terms of pull-out strength (POS). Twenty-three ATPS were inserted alternately to two screws into the pedicles and vertebral bodies, respectively, of six cadaveric specimens from C3-T1. For insertion of ATPS, a manual fluoroscopically assisted technique was used. Pre- and post insertional CT-scans were used to assess accuracy of ATPS insertion in the axial and sagittal planes. A newly designed grading system and accuracy score were used to delineate accuracy of ATPS insertion. Following insertion of screws, 23 ATPS and 22 VBS were subjected to pull-out testing (POT). The bone mineral density (BMD) of each specimen was assessed prior to POT. Statistical analysis showed that the incidence of correctly placed screws and non-critical pedicles breaches in axial plane was 78.3%, and 95.7% in sagittal plane. Hence, according to our definition of "critical" pedicle breach that exposes neurovascular structures at risk, 21.7% (n = 5) of all ATPS inserted showed a critical pedicle breach in axial plane. Notably, no critical pedicle perforation occurred at the C6 to T1 levels. Pull-out testing of ATPS and VBS revealed that pull-out resistance of ATPS was 2.5-fold that of VBS. Mean POS of 23 ATPS with a mean BMD of 0.566 g/cm(2) and a mean osseus screw purchase of 27.2 mm was 467.8 N. In comparison, POS of 22 VBS screws with a mean BMD of 0.533 g/cm(2) and a mean osseus screw purchase of 16.0 mm was 181.6 N. The difference in ultimate pull-out strength between the ATPS and VBS group was significant (p < 0.000001). Also, accuracy of ATPS placement in axial plane was shown to be significantly correlated with POS. In contrast, there was no correlation between screw-length, BMD, or level of insertion and the POS of ATPS or VBS. The study demonstrated that the use of ATPS might be a new technique worthy of further investigation. The use of ATPS shows the potential to increase construct rigidity in terms of screw-plate pull-out resistance. It might diminish construct failures during anterior-only reconstructions of the highly unstable decompressed cervical spine. PMID:18224357

Koller, Heiko; Acosta, Frank; Tauber, Mark; Fox, Michael; Martin, Hudelmaier; Forstner, Rosmarie; Augat, Peter; Penzkofer, Rainer; Pirich, Christian; Kässmann, H; Resch, Herbert; Hitzl, Wolfgang

2008-04-01

103

Cervical anterior transpedicular screw fixation (ATPS)--Part II. Accuracy of manual insertion and pull-out strength of ATPS  

PubMed Central

Reconstruction after multilevel decompression of the cervical spine, especially in the weakened osteoporotic, neoplastic or infectious spine often requires circumferential stabilization and fusion. To avoid the additional posterior surgery in these cases while increasing rigidity of anterior-only screw-plate constructs, the authors introduce the concept of anterior transpedicular screw (ATPS) fixation. We demonstrated its morphological feasibility as well as its indications in a previous study in Part I of our project. Consequently, the objectives of the current study were to assess the ex vivo accuracy of placing ATPS into the cervical vertebra as well as the biomechanical performance of ATPS in comparison to traditional vertebral body screws (VBS) in terms of pull-out strength (POS). Twenty-three ATPS were inserted alternately to two screws into the pedicles and vertebral bodies, respectively, of six cadaveric specimens from C3–T1. For insertion of ATPS, a manual fluoroscopically assisted technique was used. Pre- and post insertional CT-scans were used to assess accuracy of ATPS insertion in the axial and sagittal planes. A newly designed grading system and accuracy score were used to delineate accuracy of ATPS insertion. Following insertion of screws, 23 ATPS and 22 VBS were subjected to pull-out testing (POT). The bone mineral density (BMD) of each specimen was assessed prior to POT. Statistical analysis showed that the incidence of correctly placed screws and non-critical pedicles breaches in axial plane was 78.3%, and 95.7% in sagittal plane. Hence, according to our definition of “critical” pedicle breach that exposes neurovascular structures at risk, 21.7% (n = 5) of all ATPS inserted showed a critical pedicle breach in axial plane. Notably, no critical pedicle perforation occurred at the C6 to T1 levels. Pull-out testing of ATPS and VBS revealed that pull-out resistance of ATPS was 2.5-fold that of VBS. Mean POS of 23 ATPS with a mean BMD of 0.566 g/cm2 and a mean osseus screw purchase of 27.2 mm was 467.8 N. In comparison, POS of 22 VBS screws with a mean BMD of 0.533 g/cm2 and a mean osseus screw purchase of 16.0 mm was 181.6 N. The difference in ultimate pull-out strength between the ATPS and VBS group was significant (p < 0.000001). Also, accuracy of ATPS placement in axial plane was shown to be significantly correlated with POS. In contrast, there was no correlation between screw-length, BMD, or level of insertion and the POS of ATPS or VBS. The study demonstrated that the use of ATPS might be a new technique worthy of further investigation. The use of ATPS shows the potential to increase construct rigidity in terms of screw-plate pull-out resistance. It might diminish construct failures during anterior-only reconstructions of the highly unstable decompressed cervical spine. Electronic supplementary material The online version of this article (doi:10.1007/s00586-007-0573-x) contains supplementary material, which is available to authorized users.

Acosta, Frank; Tauber, Mark; Fox, Michael; Martin, Hudelmaier; Forstner, Rosmarie; Augat, Peter; Penzkofer, Rainer; Pirich, Christian; Kassmann, H.; Resch, Herbert; Hitzl, Wolfgang

2008-01-01

104

A Mid-Term Follow-Up Result of Spinopelvic Fixation Using Iliac Screws for Lumbosacral Fusion  

PubMed Central

Objective Iliac screw fixation has been used to prevent premature loosening of sacral fixation and to provide more rigid fixation of the sacropelvic unit. We describe our technique for iliac screw placement and review our experience with this technique. Methods Thirteen consecutive patients who underwent spinopelvic fixation using iliac screws were enrolled. The indications for spinopelvic fixation included long segment fusions for spinal deformity and post-operative flat-back syndrome, symptomatic pseudoarthrosis of previous lumbosacral fusions, high-grade lumbosacral spondylolisthesis, lumbosacral tumors, and sacral fractures. Radiographic outcomes were assessed using plain radiographs, and computed tomographic scans. Clinical outcomes were assessed using the Oswestry Disability Index (ODI) and questionnaire about buttock pain. Results The median follow-up period was 33 months (range, 13-54 months). Radiographic fusion across the lumbosacral junction was obtained in all 13 patients. The average pre- and post-operative ODI scores were 40.0 and 17.5, respectively. The questionnaire for buttock pain revealed the following: 9 patients (69%) perceived improvement; 3 patients (23%) reported no change; and 1 patient (7.6%) had aggravation of pain. Two patients complained of prominence of the iliac hardware. The complications included one violation of the greater sciatic notch and one deep wound infection. Conclusion Iliac screw fixation is a safe and valuable technique that provides added structural support to S1 screws in long-segment spinal fusions. Iliac screw fixation is an extensive surgical procedure with potential complications, but high success rates can be achieved when it is performed systematically and in appropriately selected patients.

Hyun, Seung-Jae; Kim, Yongjung J.; Kim, Young-Bae

2010-01-01

105

Eighteen-month retrospective study of Austin bunionectomy using single screw fixation.  

PubMed

The authors present an 18-month follow-up of the Austin bunionectomy using a single 2.7-mm. American Society of Internal Fixation (ASIF) (Zimmer Corporation, Warsaw, IN) screw. Fifty-six feet in 41 patients were evaluated with data from clinical examination, radiographic data, and responses to a patient questionnaire. Early return to shoes, excellent range of motion, and 96% patient satisfaction were noted. Good reduction of the intermetatarsal and the hallux valgus angles were observed, and no aseptic necrosis was noted in the series. PMID:8318964

Goforth, W P; Martin, J E

1993-01-01

106

Intramedullary screw fixation in proximal fifth-metatarsal fractures in sports: clinical and biomechanical analysis  

Microsoft Academic Search

Introduction and purpose  Intramedullary screw fixation (ISF) of proximal fifth-metatarsal fractures is known as first treatment option in young, sports\\u000a active patients. No study analyzed functional and biomechanical outcome before. Hypothetically ISF leads to (1) a high bony\\u000a union rate within 12 weeks, (2) normal hindfoot eversion strength, and (3) normal gait and plantar pressure distribution.\\u000a \\u000a \\u000a \\u000a Methods  Fourteen out of 22 patients were

André Leumann; Geert Pagenstert; Peter Fuhr; Beat Hintermann; Victor Valderrabano

2008-01-01

107

Odontoid Synchondrosis Fracture Treated by C1-2 Polyaxial Screw-Rod Fixation  

PubMed Central

The synchondrosis between the dens and the body of axis normally fuses between 5 and 7 years of age. Until this age, synchondrosis fractures can occur in children. Most synchondrosis fractures are conventionally treated by external immobilization alone. We report a 10-year-old child with odontoid synchondrosis fracture who was treated by C1 lateral mass and C2 pars screw rod fixation with a successful outcome and discuss the possible reasons for occurrence of odontoid synchondrosis fracture in this older child as well as the indications for surgery in this condition.

2014-01-01

108

Fixation pull-out response measurement of bone screws and porous-surfaced posts.  

PubMed

Screws and posts are used in various implant designs to contribute to the short- and long-term fixation stability of artificial joints. This study was undertaken to measure the detailed pull-out load-displacement response of bone screws, beaded porous coated posts, and smooth-surfaced posts in both proximal tibial cancellous bone and polyurethane material under monotonic static and repetitive cyclic loadings. The effect of a number of parameters such as insertion site on the proximal tibia, rate of displacement, insertion depth, outside diameter, drill size, repetitive loading and boundary conditions were studied. Bone screws resisted significantly larger loads than posts of the same size. Smooth-surfaced posts demonstrated much larger (about twice) pull-out forces than beaded porous coated posts of the same size. The pull-out force in the proximal tibia was markedly larger at the medial region followed by the lateral region. The central region exhibited the least force. The resistance of screws and posts diminished with repetitive cyclic loads/displacements, especially when these were larger than 50% of their respective values at pull-out force evaluated under monotonic static loading conditions. The smooth-surfaced posts showed superior performance in maintaining their resistance in fatigue than did the porous coated posts and bone screws. The pull-out force was found to also depend on the pull-out material arrangement and boundary conditions. Pull-out results measured with a specific test design should not, therefore, be compared with those performed using different design configurations. PMID:7962012

Shirazi-Adl, A; Dammak, M; Zukor, D J

1994-10-01

109

Biomechanical stability of a supra-acetabular pedicle screw Internal Fixation device (INFIX) vs External Fixation and plates for vertically unstable pelvic fractures  

PubMed Central

Background We have recently developed a subcutaneous anterior pelvic fixation technique (INFIX). This internal fixator permits patients to sit, roll over in bed and lie on their sides without the cumbersome external appliances or their complications. The purpose of this study was to evaluate the biomechanical stability of this novel supraacetabular pedicle screw internal fixation construct (INFIX) and compare it to standard internal fixation and external fixation techniques in a single stance pelvic fracture model. Methods Nine synthetic pelves with a simulated anterior posterior compression type III injury were placed into three groups (External Fixator, INFIX and Internal Fixation). Displacement, total axial stiffness, and the stiffness at the pubic symphysis and SI joint were calculated. Displacement and stiffness were compared by ANOVA with a Bonferroni adjustment for multiple comparisons Results The mean displacement at the pubic symphysis was 20, 9 and 0.8?mm for external fixation, INFIX and internal fixation, respectively. Plate fixation was significantly stiffer than the INFIX and external Fixator (P?=?0.01) at the symphysis pubis. The INFIX device was significantly stiffer than external fixation (P?=?0.017) at the symphysis pubis. There was no significant difference in SI joint displacement between any of the groups. Conclusions Anterior plate fixation is stiffer than both the INFIX and external fixation in single stance pelvic fracture model. The INFIX was stiffer than external fixation for both overall axial stiffness, and stiffness at the pubic symphysis. Combined with the presumed benefit of minimizing the complications associated with external fixation, the INFIX may be a more preferable option for temporary anterior pelvic fixation in situations where external fixation may have otherwise been used.

2012-01-01

110

The anatomic variability of human cervical pedicles: considerations for transpedicular screw fixation in the middle and lower cervical spine  

Microsoft Academic Search

Transpedicular screw fixation has recently been shown to be successful in stabilizing the middle and lower cervical spine.\\u000a Controversy exists, however, over its efficacy, due to the smaller size of cervical pedicles and the proximity of significant\\u000a neurovascular structures to both lateral and medial cortical walls. To aid the spinal surgeon in the insertion of pedicle\\u000a screws, a number of

Eon K. Shin; Manohar M. Panjabi; Neal C. Chen; Jaw-Lin Wang

2000-01-01

111

Bone Cement-Augmented Short Segment Fixation with Percutaneous Screws for Thoracolumbar Burst Fractures Accompanied by Severe Osteoporosis  

PubMed Central

Objective The purpose of this study was to determine the efficacy of bone cement-augmented short segment fixation using percutaneous screws for thoracolumbar burst fractures in a background of severe osteoporosis. Methods Sixteen patients with a single-level thoracolumbar burst fracture (T11-L2) accompanying severe osteoporosis treated from January 2008 to November 2009 were prospectively analyzed. Surgical procedures included postural reduction for 3 days and bone cement augmented percutaneous screw fixation at the fracture level and at adjacent levels without bone fusion. Due to the possibility of implant failure, patients underwent implant removal 12 months after screw fixation. Imaging and clinical findings, including involved vertebral levels, local kyphosis, canal encroachment, and complications were analyzed. Results Prior to surgery, mean pain score (visual analogue scale) was 8.2 and this decreased to a mean of 2.2 at 12 months after screw fixation. None of the patients complained of pain worsening during the 6 months following implant removal. The percentage of canal compromise at the fractured level improved from a mean of 41.0% to 18.4% at 12 months after surgery. Mean kyphotic angle was improved significantly from 19.8° before surgery to 7.8 at 12 months after screw fixation. Canal compromise and kyphotic angle improvements were maintained at 6 months after implant removal. No significant neurological deterioration or complications occurred after screw removal in any patient. Conclusion Bone cement augmented short segment fixation using a percutaneous system can be an alternative to the traditional open technique for the management of selected thoracolumbar burst fractures accompanied by severe osteoporosis.

Jung, Hyun Jin; Kim, Seok Won; Ju, Chang Il; Kim, Sung Hoon

2012-01-01

112

Outcome of Pedicle Screw Fixation and Monosegmental Fusion in Patients with Fresh Thoracolumbar Fractures  

PubMed Central

Study Design Prospective clinical study. Purpose The present prospective study aims to evaluate the clinical, radiological, and functional and quality of life outcomes in patients with fresh thoracolumbar fractures managed by posterior instrumentation of the spine, using pedicle screw fixation and monosegmental fusion. Overview of Literature The goals of treatment in thoracolumbar fractures are restoring vertebral column stability and obtaining spinal canal decompression, leading to early mobilization of the patient. Methods Sixty-six patients (46 males and 20 females) of thoracolumbar fractures with neurological deficit were stabilized with pedicle screw fixation and monosegmental fusion. Clinical, radiological and functional outcomes were evaluated. Results The mean preoperative values of Sagittal index, and compression percentage of the height of the fractured vertebra were 22.75° and 46.73, respectively, improved (statistically significant) to 12.39°, and 24.91, postoperatively. The loss of correction of these values at one year follow-up was not statistically significant. The mean preoperative canal compromise (%) improved from 65.22±17.61 to 10.06±5.31 at one year follow-up. There was a mean improvement in the grade of 1.03 in neurological status from the preoperative to final follow-up at one year. Average Denis work scale index was 4.1. Average Denis pain scale index was 2.5. Average WHOQOL-BREF showed reduced quality of life in these patients. Patients of early surgery group (operated within 7 days of injury) had a greater mean improvement of neurological grade, radiological and functional outcomes than those in the late surgery group, but it was not statistically significant. Conclusions Posterior surgical instrumentation using pedicle screws with posterolateral fusion is safe, reliable and effective method in the management of fresh thoracolumbar fractures. Fusion helps to decrease the postoperative correction loss of radiological parameters. There is no correlation between radiographic corrections achieved for deformities and functional outcome and quality of life post spinal cord injury.

Rohilla, Rajesh Kumar; Kamboj, Kulbhushan; Magu, Narender Kumar; Kaur, Kiranpreet

2014-01-01

113

Screw locking elements: a means to modify the flexibility of osteoporotic fracture fixation with DCPs without compromising system strength or stability.  

PubMed

This paper analyses whether it is possible to use dynamic compression plates (DCPs) and screw locking elements (SLEs) to vary the flexibility of osteoporotic fracture fixation without compromising the strength and stability of the construct. Compression, torsion and four-point bending static strength tests were conducted. Cyclic load tests of up to 10,000 load cycles were also carried out to determine stiffness performance. Four fixation systems were mounted onto polyurethane bone models. Group 1 consists of the DCP and six cortical screws. Group 2, idem, but with the addition of two SLEs. Group 3, idem, but with the addition of six SLEs. Group 4 used the locking compression plate (LCP) and locking screws. The results indicated no significant difference (p>0.05) in the strength of groups 2-4. It was also observed that the torsional stiffness of group 3 (0.30 Nm/°) was higher than that of group 2 (0.23 Nm/°) and similar to that of group 4 (0.28 Nm/°). Compression stiffness of group 4 (124 N/mm) was higher than that of group 2 (102 N/mm), but lower than that of group 3 (150 N/mm). No notable differences were observed for structural bending stiffness. It is concluded that by using the DCP with SLEs it is possible to modify the stiffness of the fixation construct for the repair of osteoporotic fractures and, in this way, facilitate the conditions suitable on secondary bone healing. PMID:21982962

Yánez, A; Cuadrado, A; Carta, J A; Garcés, G

2012-07-01

114

Cervical Pedicle Screw Fixation Combined with Laminoplasty for Cervical Spondylotic Myelopathy with Instability  

PubMed Central

Study Design A retrospective study. Purpose To evaluate the surgical results of cervical pedicle screw (CPS) fixation combined with laminoplasty for treating cervical spondylotic myelopathy (CSM) with instability. Overview of Literature Cervical fixation and spinal cord decompression are required for CSM patients with instability. However, only a few studies have reported on CPS fixation combined with posterior decompression for unstable CSM patients. Methods Thirteen patients that underwent CPS fixation combined with laminoplasty for CSM with instability were evaluated in this study. We assessed the clinical and radiological results of the surgical procedures. The Japanese Orthopedic Association (JOA) scoring system was used to evaluate the clinical results. The percentages of sli p, difference in sli p angle between maximum flexion and maximum extension of unstable intervertebrae, and perforation rate of CPS were evaluated. Results The mean JOA scores before surgery, immediately after surgery, and at final follow-up were 9.1, 13.3, and 12.6, respectively. The mean percentages of sli p before surgery, immediately after surgery, and at final follow-up were 9.1%, 3.2%, and 3.5%, respectively; there were significant improvements immediately after surgery and at final follow-up. The difference in sli p angle between the maximum flexion and maximum extension of the unstable intervertebrae changed from 9.0° before surgery to 1.6° at the final follow-up. The perforation rate of CPS was 10.9%. Conclusions The results suggest that CPS fixation combined with laminoplasty is an effective surgical procedure for treating CSM with instability.

Uehara, Masashi; Ogihara, Nobuhide; Hirabayashi, Hiroki; Hashidate, Hiroyuki; Mukaiyama, Keijiro; Shimizu, Masayuki; Kato, Hiroyuki

2012-01-01

115

Anterior transarticular screw fixation for atlantoaxial arthrodesis: A report of two cases.  

PubMed

The sequelae of atlantoaxial instability (AAI) range from axial neck pain to life-threatening neurologic injury. Instrumentation and fusion of the C1-2 joint is often indicated in the setting of clinical or biomechanical instability. This is the first clinical report of anterior Smith-Robinson C1-2 transarticular screw (TAS) fixation for AAI. The first patient presented with ischemic brain tissue secondary to post-traumatic C1-2 segment instability from a MVC 7 years prior to presentation. The second patient presented with a 3 year history of persistent right-sided neck and upper scalp pain. Both were treated with transarticular C1-2 fusion through decortication of the atlantoaxial facet joints and TAS fixation via the anterior Smith-Robinson approach. At 16 months follow-up, the first patient maintained painless range of motion of the cervical spine and denied sensorimotor deficits. The second patient reported 90% improvement in her pre-operative symptoms of neck pain and paresthesia. Anterior Smith-Robinson C1-2 TAS fixation provides a useful alternative to the posterior Goel and Magerl techniques for C1-2 stabilization and fusion. PMID:24737928

Carrier, C S; Sama, A A; Girardi, F P; Lebl, D R

2013-07-01

116

Surface immobilized zoledronate improves screw fixation in rat bone: a new method for the coating of metal implants.  

PubMed

Previous studies show that surface immobilized bisphosphonates improve the fixation of stainless steel screws in rat tibia after 2-8 weeks of implantation. We report here about the immobilization of a potent bisphosphonate, zoledronate, to crosslinked fibrinogen by the use of another technique, i.e. ethyl-dimethyl-aminopropylcarbodiimide (EDC)/imidazole immobilization. Bone fixation of zoledronate-coated screws was compared to screws coated with crosslinked fibrinogen only and ditto with EDC/N-hydroxy-succinimide immobilized pamidronate. Fixation in rat tibia was evaluated by a pull-out test at either 2 or 6 weeks after implantation. Both bisphosphonate coatings increased the pull-out force at both time points, and zoledronate showed a significantly higher pull-out force than pamidronate. To further evaluate the new coating technique we also performed a morphometric study, focusing on the area surrounding the implant. The zoledronate coating resulted in an increased bone density around the screws compared to controls. No pronounced increase was seen around the pamidronate coated screws. Together, the results demonstrate the possibility of obtaining a significant local therapeutic effect with minute amounts of surface immobilized zoledronate. PMID:20857321

Andersson, Therese; Agholme, Fredrik; Aspenberg, Per; Tengvall, Pentti

2010-11-01

117

Cervical pedicle screw fixation in traumatic cervical subluxation after laminectomy using the pedicle axis view technique under fluoroscopy.  

PubMed

Cervical pedicle screw (CPS) fixation has recently been performed in patients in need of cervical reconstruction. We report the case of a 50-year-old man who was operated for traumatic cervical vertebra subluxation using CPS fixation, in whom laminectomy had been performed in the past. We performed CPS fixation using the pedicle axis view technique under fluoroscopy. The four pedicle screws were accurately inserted within the pedicles without perforating the bone cortex of the pedicles. A navigation system is useful for cervical spine surgery because it enables a surgeon to perform relatively safe and accurate surgery during transpedicular screw fixation. However, attachment of the stereotactic reference arc to the spinous process is impossible, and the application of a navigation system is limited in cases in which laminectomy has been performed in the past. We have been using the pedicle axis view technique under fluoroscopy and have found that if we take care of the entry point accurately, we can safely insert the pedicle screw in cases with fewer landmarks. PMID:23060373

Machino, Masaaki; Yukawa, Yasutsugu; Ito, Keigo; Nakashima, Hiroaki; Kanbara, Shunsuke; Morita, Daigo; Kato, Fumihiko

2012-01-01

118

Magnetic resonance imaging analysis of the bioabsorbable Milagro interference screw for graft fixation in anterior cruciate ligament reconstruction.  

PubMed

Ligament graft fixation with bioabsorbable interference screws is a standard procedure in cruciate ligament replacement. Previous screw designs may resorb incompletely, and can cause osteolysis and sterile cysts despite being implanted for several years. The aim of this study was to examine the in vivo degradation and biocompatibility of the new Milagro interference screw (Mitek, Norderstedt, Germany). The Milagro interference screw is made of 30% ss-TCP (TriCalcium phosphate) and 70% PLGA (Poly-lactic-co-glycolic acid). In the period between June 2005 and February 2006, 38 patients underwent graft fixation with Milagro screws in our hospital. Arthroscopic ACL reconstruction was performed using hamstring tendon grafts in all the patients. MR imaging was performed on 12 randomly selected patients out of the total of 38 at 3, 6 and 12 months after surgery. During the examination, the volume loss of the screw, tunnel enlargement, presence of osteolysis, fluid lines, edema and postoperative screw replacement by bone tissue were evaluated. There was no edema or signs of inflammation around the bone tunnels. At 3, 6 and 12 months, the tibial screws showed an average volume loss of 0, 8.1% (+/-7.9%) and 82.6% (+/-17.2%, P < 0.05), respectively. The femoral screws showed volume losses of 2.5% (+/-2.1%), 31.3% (+/-21.6%) and 92.02% (+/-6.3%, P < 0.05), respectively. The femoral tunnel enlargement was 47.4% (+/-43.8%) of the original bone tunnel volume after 12 months, and the mean tunnel volume of the tibial tunnel was -9.5% (+/-58.1%) compared to the original tunnel. Bone ingrowth was observed in all the patients. In conclusion, the resorption behaviour of the Milagro screw is closely linked to the graft healing process. The screws were rapidly resorbed after 6 months and, at 12 months, only the screw remnants were detectable. Moreover, the Milagro screw is biocompatible and osteoconductive, promoting bone ingrowth during resorption. Tunnel enlargement is not prevented in the first months but is reduced by bone ingrowth after 12 months. PMID:19697105

Frosch, K-H; Sawallich, T; Schütze, G; Losch, A; Walde, T; Balcarek, P; Konietschke, F; Stürmer, K M

2009-10-01

119

Posterior lumbar interbody fusion using one diagonal fusion cage with transpedicular screw/rod fixation.  

PubMed

Posterior lumbar interbody fusion (PLIF) using threaded cages has gained wide popularity for lumbosacral spinal disease. Our biomechanical tests showed that PLIF using a single diagonal cage with unilateral facetectomy does add a little to spinal stability and provides equal or even higher postoperative stability than PLIF using two posterior cages with bilateral facetectomy. Studies also demonstrated that cages placed using a posterior approach did not cause the same increase in spinal stiffness seen with pedicle screw instrumentation, and we concluded that cages should not be used posteriorly without other forms of fixation. On the other hand, placement of two cages using a posterior approach does have the disadvantage of risk to the bilateral nerve roots. We therefore performed a prospective study to determine whether PLIF can be accomplished by utilizing a single diagonal fusion cage with the application of supplemental transpedicular screw/rod instrumentation. Twenty-seven patients underwent a PLIF using one single fusion cage (BAK, Sulzer Spine-Tech, Minneapolis, MN, USA) inserted posterolaterally and oriented anteromedially on the symptomatic side with unilateral facetectomy and at the same level supplemental fixation with a transpedicular screw/rod system. The internal fixation systems included 12 SOCON spinal systems (Aesculap AG, Germany) and 15 TSRH spinal systems (Medtronic Sofamor Danek, USA). The inclusion criteria were grade 1 to 2 lumbar isthmic spondylolisthesis, lumbar degenerative spondylolisthesis, and recurrent lumbar disc herniations with instability. Patients had at least 1 year of low back pain and/or unilateral sciatica and a severely restricted functional ability in individuals aged 28-55 years. Patients with more than grade 2 spondylolisthesis or adjacent-level degeneration were excluded from the study. Patients were clinically assessed prior to surgery by an independent assessor; they were then reassessed at 1, 3, 6, 12, 18, and 24 months postoperatively by the same assessor and put into four categories: excellent, good, fair, and poor. Operative time, blood loss, hospital expense, and complications were also recorded. All patients achieved successful radiographic fusion at 2 years, and this was achieved at 1 year in 25 out of 27 patients. At 2 years, clinical results were excellent in 15 patients, good in 10, fair in 1, and poor in 1. Regarding complications, one patient had a postoperative motor and sensory deficit of the nerve root. Reoperation was required in one patient due to migration of pedicle screws. No implant fractures or deformities occurred in any of the patients. PLIF using diagonal insertion of a single threaded cage with supplemental transpedicular screw/rod instrumentation enables sufficient decompression and solid interbody fusion to be achieved with minimal invasion of the posterior spinal elements. It is a clinically safer, easier, and more economical means of accomplishing PLIF. PMID:12709855

Zhao, Jie; Hou, Tiesheng; Wang, Xinwei; Ma, Shengzhong

2003-04-01

120

Bioabsorbable screw divergence angle, not tunnel preparation method influences soft tissue tendon graft-bone tunnel fixation in healthy bone.  

PubMed

Bone tunnel fixation of a soft tissue tendon graft is the weak link immediately following ACL reconstruction. This biomechanical study evaluated the influence of extraction drilled or step dilated bone tunnels and bioabsorbable screw divergence on soft tissue tendon graft fixation. From an initial group of 50 available specimens, similar apparent bone mineral density porcine tibiae (1.2 +/- 0.24 g/cm2) were divided into two groups of ten specimens each. Group 1 (extraction drilled) received 9 mm diameter tunnels. Group 2 (step dilated) received 7 mm diameter tunnels that were dilated to 9 mm. Grafts were secured in tunnels using 10 mm diameter, 35 mm long tapered screws. After high resolution CT scanning to evaluate screw divergence, constructs were pretensioned on a servo hydraulic device between 10 and 50 N for 10 cycles, and isometric pretensioned at 50 N for 1 min, prior to 500 sub-maximal loading cycles (50-200 N) and load to failure testing at 20 mm/min. Wilcoxon Signed Rank tests and Mann-Whitney U-tests were used to evaluate group differences. Coefficient of determination values (r2) were calculated to further delineate statistically significant relationships. Tunnel preparation method did not display statistically significant effects on insertion torque, displacement during cyclic testing, relative stiffness during cyclic testing, load at failure, stiffness during load to failure testing or displacement during load to failure testing. Screw divergence < 15 degrees produced lower displacement and greater relative stiffness during cyclic testing and greater load at failure and stiffness during load to failure testing. Screw divergence angle displayed moderate relationships with construct displacement during cyclic testing (r2 = 0.54), stiffness during load to failure testing (r2 = 0.60), and load at failure (r2 = 0.41). Tunnel dilation does not enhance soft tissue tendon graft fixation strength in healthy bone. Bioabsorbable screw divergence of > or = 15 degrees significantly reduces soft tissue tendon graft-bone tunnel fixation. PMID:16964517

Duffee, Andrew R; Brunelli, Jeffrey A; Nyland, John; Burden, Robert; Nawab, Akbar; Caborn, David

2007-01-01

121

Maxillo Mandibular Fixation in Edentulous Scenarios: Combined MMF Screws and Gunning Splints.  

PubMed

A fracture of the maxillary or mandibular bone requires the afflicted to undergo a maxillo mandibular fixation for the establishment of pre traumatic occlusion. This process is quiet tedious and consumes a considerable period of time before any surgical procedure can commence. Such a situation can be complicated in case the individual with maxillomandibular fracture has sparse or absent dentition; for such cases a splint is fabricated or an erstwhile existing denture is used for maintaining a vertical jaw proportion. Stabilizing such splints to the jaw requires various invasive approaches that can bring into harm's way, adjacent soft tissue vital structures. We describe here an innovative technique combining the time tested method of the "gunning splint" and the advanced minimally invasive MMF screws for obtaining closed reduction in edentulous jaw fractures. PMID:24822016

Chaudhary, Zainab; Sharma, Rakesh; Krishnan, Sriram

2014-06-01

122

Austin bunionectomy using single screw fixation: five-year versus 18-month follow-up findings.  

PubMed

The authors present a follow-up of the Austin bunionectomy using a single 2.7-mm American Society of Internal Fixation (ASIF) screw. At a mean 5-year follow-up, 45 feet in 32 patients were evaluated with information from clinical examination, radiographic data, and responses to a patient questionnaire. When compared to the 18-month follow-up, good reduction of the intermetatarsal and the hallux abductus angle were maintained. Clinical findings, including the first metatarsophalangeal joint range of motion and hallux purchase power, remained acceptable, and a small number of new transfer lesions were noted. Patient satisfaction with appearance and overall satisfaction with the procedure remained excellent-to-good in 96% of the procedures. PMID:8807487

Goforth, W P; Martin, J E; Domrose, D S; Sligh, T S

1996-01-01

123

Biomechanical effects of polyaxial pedicle screw fixation on the lumbosacral segments with an anterior interbody cage support  

PubMed Central

Background Lumbosacral fusion is a relatively common procedure that is used in the management of an unstable spine. The anterior interbody cage has been involved to enhance the stability of a pedicle screw construct used at the lumbosacral junction. Biomechanical differences between polyaxial and monoaxial pedicle screws linked with various rod contours were investigated to analyze the respective effects on overall construct stiffness, cage strain, rod strain, and contact ratios at the vertebra-cage junction. Methods A synthetic model composed of two ultrahigh molecular weight polyethylene blocks was used with four titanium pedicle screws (two in each block) and two rods fixation to build the spinal construct along with an anterior interbody cage support. For each pair of the construct fixed with polyaxial or monoaxial screws, the linked rods were set at four configurations to simulate 0°, 7°, 14°, and 21° lordosis on the sagittal plane, and a compressive load of 300 N was applied. Strain gauges were attached to the posterior surface of the cage and to the central area of the left connecting rod. Also, the contact area between the block and the cage was measured using prescale Fuji super low pressure film for compression, flexion, lateral bending and torsion tests. Results Our main findings in the experiments with an anterior interbody cage support are as follows: 1) large segmental lordosis can decrease the stiffness of monoaxial pedicle screws constructs; 2) polyaxial screws rather than monoaxial screws combined with the cage fixation provide higher compression and flexion stiffness in 21° segmental lordosis; 3) polyaxial screws enhance the contact surface of the cage in 21° segmental lordosis. Conclusion Polyaxial screws system used in conjunction with anterior cage support yields higher contact ratio, compression and flexion stiffness of spinal constructs than monoaxial screws system does in the same model when the spinal segment is set at large lordotic angles. Polyaxial pedicle screw fixation performs nearly equal percentages of vertebra-cage contact among all constructs with different sagittal alignments, therefore enhances the stabilization effect of interbody cages in the lumbosacral area.

Chen, Shih-Hao; Mo Lin, Ruey; Chen, Hsiang-Ho; Tsai, Kai-Jow

2007-01-01

124

A method for the fatigue testing of pedicle screw fixation devices.  

PubMed

Spinal devices/instrumentation are used to augment the stability of a decompressed spinal segment during surgery. Like any other mechanical component, the device can fail. A standard in vitro test protocol, was developed to determine load vs number of cycles to failure curve for a pedicle screw-plate/rod type spinal device. The protocol based on the use of an 'artificial spine' model, is clinically relevant. The protocol was used to characterize the load-carrying capacities and failure modes of a specific pedicle screw-rod type fixation device to demonstrate its appropriateness. The devices (Kaneda) were tested in the quasi-static as well as fatigue bending modes. In the bending fatigue mode, the devices failed at loads significantly smaller than the corresponding quasi-static failure load magnitude (806 N). The device exhibited an endurance limit in the fatigue bending mode. The device is not likely to exhibit failure if subjected to cyclic loads which cause less than 380 N axial compression (and an accompanying bending moment relative to the device of less than 13.57 Nm). The failures observed in specimens subjected to the fatigue tests ranged from complete to partial breakage of the paraspinal rods as opposed to failure due to permanent deformation (yielding) of the rods in the quasi-static bending test specimens. The protocol developed can be used for any other screw-plate/rod type spinal instrumentation. The use of a standard protocol by researchers would enable a comparison of various devices currently available in the market. Such comparative data would be useful for the scientific community, and agencies such as the FDA and ASTM.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7798289

Goel, V K; Winterbottom, J M; Weinstein, J N

1994-11-01

125

One-stage posterior C2 and C3 pedicle screw fixation or combined anterior C2-C3 fusion for the treatment of unstable hangman's fracture  

PubMed Central

The present study aimed to evaluate the effect of using one-stage posterior C2 and C3 pedicle screw fixation or combined anterior C2-C3 fusion in the treatment of unstable hangman’s fracture. A total of 13 patients with unstable hangman’s fractures underwent C2 and C3 pedicle screw fixation, lamina interbody fusion or combined anterior C2-C3 fusion and imaging examinations to evaluate the fracture fixation and healing condition at three days and three months following surgery. Postoperative X-ray and computed tomography (CT) results showed high fracture reduction, good internal fixation position and reliable fracture fixation. The three-month postoperative CT showed good vertebral fracture healing. C2 and C3 pedicle screw fixation has a good curative effect in the treatment of unstable hangman’s fracture. The direct fixation of the fracture enables early ambulation by the patients.

LIU, JINGCHEN; LI, YE; WU, YUNTAO

2013-01-01

126

Transarticular screw fixation of C1-2 for the treatment of arthropathy-associated occipital neuralgia.  

PubMed

Two patients with occipital neuralgia due to severe arthropathy of the C1-2 facet joint were treated using atlantoaxial fusion with transarticular screws without decompression of the C-2 nerve root. Both patients experienced immediate postoperative relief of occipital neuralgia. The resultant motion elimination at C1-2 eradicated not only the movement-evoked pain, but also the paroxysms of true occipital neuralgia occurring at rest. A possible pathophysiological explanation for this improvement is presented in the context of the ignition theory of neuralgic pain. This represents the first report of C1-2 transarticular screw fixation for the treatment of arthropathy-associated occipital neuralgia. PMID:21214317

Pakzaban, Peyman

2011-02-01

127

Analysis of the Stress and Displacement Distribution of Inferior Tibiofibular Syndesmosis Injuries Repaired with Screw Fixation: A Finite Element Study  

PubMed Central

Background Studies of syndesmosis injuries have concentrated on cadaver models. However, they are unable to obtain exact data regarding the stress and displacement distribution of various tissues, and it is difficult to compare models. We investigated the biomechanical effects of inferior tibiofibular syndesmosis injuries (ITSIs) and screw fixation on the ankle using the finite element (FE) method. Methodology/Principal Findings A three-dimensional model of a healthy ankle complex was developed using computed tomography (CT) images. We established models of an ITSI and of screw fixation at the plane 2.5 cm above and parallel to the tibiotalar joint surface of the injured syndesmosis. Simulated loads were applied under three conditions: neutral position with single-foot standing and internal and external rotation of the ankle. ITSI reduced contact forces between the talus and fibula, helped periarticular ankle ligaments withstand more load-resisting movement, and increased the magnitude of displacement at the lower extreme of the tibia and fibula. ITSI fixation with a syndesmotic screw reduced contact forces in all joints, decreased the magnitude of displacement at the lower extreme of the tibia and fibula, and increased crural interosseous membrane stress. Conclusions/significance Severe syndesmosis injuries cause stress and displacement distribution of the ankle to change multidirectional ankle instability and should be treated by internal fixation. Though the transverse syndesmotic screw effectively stabilizes syndesmotic diastasis, it also changes stress distribution around the ankle and decreases the joint's range of motion (ROM). Therefore, fixation should not be performed for a long period of time because it is not physiologically suitable for the ankle joint.

Liu, Qinghua; Zhang, Kun; Zhuang, Yan; Li, Zhong; Yu, Bin; Pei, Guoxian

2013-01-01

128

[Percutaneous iliolumbar screw fixation in a patient with unstable pelvic fracture and transitional lumbar vertebrae and cadaveric illustration of the fixation].  

PubMed

Unstable pelvic ring fractures cause high rates of morbidity and mortality. Percutaneous iliosacral screws provide a safe pelvic fixation obviating large surgical exposures. The presence of transitional vertebrae may present difficulties in numbering and fluoroscopic identification of lumbar discs and vertebrae. We performed percutaneous iliolumbar screw fixation for an unstable pelvic fracture due to a traffic accident in a 20-year-old male patient with transitional lumbar vertebrae. No neurologic or vascular complications were seen and the patient returned to his preinjury work and was pain-free in the second postoperative year. In order to determine the anatomic relationship of the iliolumbar screw with the major neurovascular structures, a cadaveric study was performed on the corpse of an adult man. Following dissection, it was observed that the iliolumbar screw inserted from the lateral wall of the iliac wing passed through the iliopsoas muscle and advanced to the L(5) vertebral corpus posterior to the fourth and fifth lumbar roots and with a reasonably distant course from the common iliac veins and arteries. PMID:19881327

Ayvaz, Mehmet; Yilmaz, Güney; Akpinar, Erhan; Acaro?lu, Rifat Emre

2009-01-01

129

Proximal Femoral Nail versus Dynamic Hip Screw Fixation for Trochanteric Fractures: A Meta-Analysis of Randomized Controlled Trials  

PubMed Central

Background. The purpose of this meta-analysis was to find out whether the proximal femoral nail was better than the dynamic hip screw in the treatment of trochanteric fractures with respect to operation time, blood transfusion, hospital stay, wound complications, number of reoperation, and mortality rate. Methods. All randomized controlled trials comparing proximal femoral nail and dynamic hip screw in the treatment of trochanteric fractures were included. Articles and conference data were extracted by two authors independently. Data was analyzed using RevMan 5.1 version. Eight trials involving 1348 fractures were retrieved. Results. Compared with DHS fixation, PFN fixation had similar operation time (95% CI: ?15.28–2.40, P = 0.15). Blood loss and transfusion during perioperative time were also comparable between the two fixations (95% CI: ?301.39–28.11, P = 0.10; 95% CI: ?356.02–107.20, P = 0.29, resp.). Outcomes of hospital stay (95% CI: ?0.62–1.01, P = 0.64), wound complication (95% CI: 0.66–1.67, P = 0.82), mortality (95% CI: 0.83–1.30, P = 0.72), and reoperation (95% CI: 0.61–1.54, P = 0.90) were all similar between the two groups. Conclusion. PFN fixation shows the same effectiveness as DHS fixation in the parameters measured.

Huang, Xiao; Leung, Frankie; Xiang, Zhou; Tan, Pei-Yong; Yang, Jing; Wei, Dai-Qing; Yu, Xi

2013-01-01

130

Triple arthrodesis stabilization: a quantitative analysis of screw versus staple fixation in fresh cadaveric matched-pair specimens.  

PubMed

Qualitative analyses of midfoot stabilization in triple arthrodeses utilizing bone staple versus 4.5-mm cannulated cancellous screw fixation, with and without washers, were performed in fresh cadaveric specimens. Twenty-two trials (11 matched-pair feet) were used for direct comparison. Stiffness, defined as force/displacement, was determined at each talonavicular and calcaneocuboid joint. Ultimate load failure points of each specimen were also calculated. Trial results showed no statistically significant difference in stiffness or ultimate failure between these two forms of midfoot fixation for triple arthrodeses. PMID:9879042

Payette, C R; Sage, R A; Gonzalez, J V; Sartori, M; Patwardhan, A; Vrbos, L

1998-01-01

131

Comparison of the bioabsorbable and metal screw fixation after ACL reconstruction with a hamstring autograft in MRI and clinical outcome: a prospective randomized study  

Microsoft Academic Search

There has never been an MRI study of tunnel widening comparing bioabsorbable to metal screw fixation in autologous hamstring\\u000a anterior cruciate ligament (ACL) reconstruction. We randomized 62 patients to hamstring ACL reconstruction with either a bioabsorbable\\u000a (n = 31) or metal screw (n = 31) fixation. The evaluation methods were clinical examination, KT-1000 arthrometric measurement, the International Knee\\u000a Documentation Committee and Lysholm scores, and

Anna-Stina Moisala; Timo Järvelä; Antti Paakkala; Timo Paakkala; Pekka Kannus; Markku Järvinen

2008-01-01

132

Investigation of load transfer and optimum pin configuration in the internal fixation, by Muller screws, of fractured femoral necks  

Microsoft Academic Search

Five pairs of matching hips were tested under conditions of low-speed mechanical loading in the unfractured and artificially\\u000a fractured states, to gain an understanding of the mechanism of load transfer for various orientations of Muller cancellous\\u000a screws used in the internal fixation of the femoral neck. The results indicate that the pins' contribution to load bearing\\u000a is small in the

J. Mizrahi; R. S. Hurlin; J. K. Taylor; L. Solomon

1980-01-01

133

Alendronate treatment improves bone-pedicle screw interface fixation in posterior lateral spine fusion: An experimental study in a porcine model  

PubMed Central

The bone–screw interface has been indicated as the weak link in pedicle screw spine fixation. Bisphosphonate treatment may have the effect of improving bone–screw interface fixation in spine fusion by inhibiting bone resorption. An experimental study was conducted using a porcine model to evaluate the influence of alendronate treatment on bone–pedicle screw interface fixation. Eleven pigs in the treatment group received alendronate 10 mg/day orally for three months postoperatively. The other 11 pigs served as a control group. Posterior lateral fusion with the CD Horizon pedicle screw system was performed with autograft on the lumbar spine on all animals. Biomechanical torsion test and histomorphometric parameters of screw fixation were evaluated three months after the operation. The maximum torque and initial angular stiffness of the treatment group was higher than that of the control group, but there was no statistical significance. The bone–screw contact surface was 23.3?±?10% for the treatment group and 9.8?±?5.9% for the control group (P?screw surfaces.

Li, Haisheng; Zou, Xuenong; Dalstra, Michel; Lind, Martin; Christensen, Finn B.; Bunger, Cody

2009-01-01

134

Biomechanical effect of the extent of vertebral body fracture on the thoracolumbar spine with pedicle screw fixation: An in vitro study  

Microsoft Academic Search

A fractured vertebra does not transfer load as effectively as the intact vertebra. Patients who undergo surgery using short-segment pedicle screw instrumentation for middle-column injury may experience implant failure when vertebral body comminution is ignored. The purpose of this study was to investigate biomechanical effects of the extent of vertebral body fracture on the thoracolumbar spine after pedicle screw fixation

Xiang-Yang Wang; Li-Yang Dai; Hua-Zi Xu; Yong-Long Chi

2008-01-01

135

Pelvic Girdle Reconstruction Based on Spinal Fusion and Ischial Screw Fixation in a Case of Aneurysmal Bone Cyst  

PubMed Central

A case of lytic lesion of the pelvis in a 23-year-old woman is presented. A biopsy led to the diagnosis aneurysmal bone cyst (ABC). Due to the histologically very aggressive growth of the tumor, a low malignant osteosarcoma could not be excluded. In an initial operation the tumour, affecting the sacrum, the iliac crest and the lower lumbar spine was resected. Temporary restabilisation of the pelvic ring was achieved by a titanium plate. The histological examination of the entire tumour confirmed the diagnosis ABC. After 6 months, the MRI showed no recurrence. The observed tilt of the spine to the operated side on the sacral base prompted a second surgical procedure: a transpedicular fixation of L5 and L4 was connected via bent titanium stems to the ischium, where the fixation was achieved by two screws. This construction allowed the correction of the base angle and yielded a stable closure of the pelvic ring. The patient has now been followed for 6 years: the bone grafts have been incorporated and, in spite of radiological signs of screw loosening in the ischium, the patient is fully rehabilitated and free of symptoms. Pedicle screws in the lower spine can be recommended for fixation of a pelvic ring discontinuity.

Westphal, Florian; Carrero, Volker; Morlock, Michael; Schwieger, Karsten; Hille, Ekkehard; Delling, G.

2003-01-01

136

Biomechanical In Vitro - Stability Testing on Human Specimens of a Locking Plate System Against Conventional Screw Fixation of a Proximal First Metatarsal Lateral Displacement Osteotomy  

PubMed Central

Introduction: The aim of this study was to examine resistance to angulation and displacement of the internal fixation of a proximal first metatarsal lateral displacement osteotomy, using a locking plate system compared with a conventional crossed screw fixation. Materials and Methodology: Seven anatomical human specimens were tested. Each specimen was tested with a locking screw plate as well as a crossed cancellous srew fixation. The statistical analysis was performed by the Friedman test. The level of significance was p = 0.05. Results: We found larger stability about all three axes of movement analyzed for the PLATE than the crossed screws osteosynthesis (CSO). The Friedman test showed statistical significance at a level of p = 0.05 for all groups and both translational and rotational movements. Conclusion: The results of our study confirm that the fixation of the lateral proximal first metatarsal displacement osteotomy with a locking plate fixation is a technically simple procedure of superior stability.

Arnold, Heino; Stukenborg-Colsman, Christina; Hurschler, Christof; Seehaus, Frank; Bobrowitsch, Evgenij; Waizy, Hazibullah

2012-01-01

137

Image-Guided Computer-Assisted Spine Surgery: A Pilot Study on Pedicle Screw Fixation  

Microsoft Academic Search

As the pedicle offers a strong point of attachment to the spine, several instrumentation systems using screws that go through the pedicle into the vertebral body have been developed to provide internal stability. All pedicle screw systems share the risk of damage to adjacent neural structures as a result of improper screw placement. A computer-assisted system allowing precise preoperative planning

Lutz Nolte; Lucia Zamorano; E. Arm; H. Visarius; Zaowei Jiang; U. Berlerman; O. Schwarzenbach

1996-01-01

138

Is Loss of Fixation Following Locked Plating of Proximal Humeral Fractures Related to the Number of Screws and Their Positions in the Humeral Head?  

PubMed Central

The aim of the study was to examine the correlation between the chosen position of screws and the complications observed in patients who underwent locked plating of proximal humeral fractures. We evaluated radiographs of 367 patients treated by locked-plating for proximal humeral fractures. Radiographs were taken at one day, 6 weeks, 3 months and 6 months after surgery, and were analyzed for secondary fracture displacement, loss of fixation, cutting out of screws and necrosis of the humeral head. Secondary loss of fixation occurred in 58 cases (15.8%) and among those cutting out of screws was observed in 25 cases (6.8%). In cases of secondary loss of fixation a mean of 6.7 screws were used to fix the fracture (vs 6.6, P=0.425). There was neither significant correlation between position of screws and the occurrence of postoperative loss of fixation in Spearman correlation nor relationship from backward logistic regression analysis. Loss of fixation following locked plating of proximal humeral fractures does not relate to the number of screws and their positions in the humeral head. In consequence, anatomic fracture reduction and restoration of the humeral head-shaft angle are still important factors and should not be disregarded.

Maddah, Mohammad; Prall, Wolf C.; Geyer, Lucas; Wirth, Stefan; Mutschler, Wolf; Ockert, Ben

2014-01-01

139

Combined S-1 and S-2 sacral alar-iliac screws as a salvage technique for pelvic fixation after pseudarthrosis and lumbosacropelvic instability: combined S-1 and S-2 sacral alar-iliac screws as a salvage technique for pelvic fixation after pseudarthrosis and lumbosacropelvic instability: technical note.  

PubMed

Lumbosacropelvic pseudarthrosis after long spinal fusions for treatment of adult degenerative scoliosis remains a challenging condition. Moreover, although pelvic fixation with iliac screws is widely used in deformity surgery to provide a biomechanically strong distal anchor for long thoracolumbar constructs, there are very few options available after failed pelvic fixation with iliac screws. The authors conducted a retrospective review of the surgical charts and imaging findings of patients subjected to revision surgery for lumbosacropelvic pseudarthrosis from August 2011 to August 2012. This review identified 5 patients in whom a salvage technique combining both S-1 and S-2 sacral alar-iliac (SAI) screws had been performed. In this technical note, the authors present a detailed anatomical discussion and an appraisal of the sequential intraoperative steps of this new technique involving a combination of S-1 and S-2 SAI screws. The discussion is illustrated with a surgical case in which this technique was used to treat a patient with pseudarthrosis that had developed after fixation with classic iliac screws. In conclusion, although S-2 SAI screws have previously been reported as an interesting alternative to classic iliac wing screws, this report is the first on the use of combined S-1 and S-2 SAI screws for pelvic fixation as a salvage technique for lumbosacropelvic instability. According to the reported experience, this technique provides a biomechanically robust construct for definitive pelvic fixation during revision surgeries in the challenging scenarios of pseudarthrosis and instability of the lumbosacropelvic region. PMID:23808582

Mattei, Tobias A; Fassett, Daniel R

2013-09-01

140

Minimally Invasive Transforaminal Lumbar Interbody Fusion with Unilateral Pedicle Screw Fixation: Comparison between Primary and Revision Surgery  

PubMed Central

Minimally invasive surgery with a transforaminal lumbar interbody fusion (MIS TLIF) is an important minimally invasive fusion technique for the lumbar spine. Lumbar spine reoperation is challenging and is thought to have greater complication risks. The purpose of this study was to compare MIS TLIF with unilateral screw fixation perioperative results between primary and revision surgeries. This was a prospective study that included 46 patients who underwent MIS TLIF with unilateral pedicle screw. The patients were divided into two groups, primary and revision MIS TLIF, to compare perioperative results and complications. The two groups were similar in age, sex, and level of operation, and were not significantly different in the length of follow-up or clinical results. Although dural tears were more common with the revision group (primary 1; revision 4), operation time, blood loss, total perioperative complication, and fusion rates were not significantly different between the two groups. Both groups showed substantial improvements in VAS and ODI scores one year after surgical treatment. Revision MIS TLIF performed by an experienced surgeon does not necessarily increase the risk of perioperative complication compared with primary surgery. MIS TLIF with unilateral pedicle screw fixation is a valuable option for revision lumbar surgery.

Kang, Moo Sung; Kim, Kyung Hyun; Kuh, Sung Uk; Chin, Dong Kyu; Kim, Keun Su; Cho, Yong Eun

2014-01-01

141

Comparison between Conventional and Minimally Invasive Dynamic Hip Screws for Fixation of Intertrochanteric Fractures of the Femur  

PubMed Central

Background. Intertrochanteric fractures of the proximal femur are one of the most common fractures encountered, and dynamic hip screw with a side plate is the standard treatment. We compared a minimally invasive surgical technique with the conventional surgical technique used in the fixation of intertrochanteric fractures with the dynamic hip screw (DHS) device. Methods. Thirty patients with such fractures were treated with the conventional open technique and 30 with a new minimally invasive technique. Patients in both groups were followed up for 1 year. Results. There was less blood loss, minimal soft tissue destruction, shorter hospital stay, and early mobilization with the minimally invasive technique. Conclusion. The present study finds minimally invasive technique superior to conventional (open) DHS.

Mahmood, A.; Kalra, M.; Patralekh, M. K.

2013-01-01

142

Failure of femoral head fixation: a cadaveric analysis of lag screw cut-out with the gamma locking nail and AO dynamic hip screw  

Microsoft Academic Search

The most commonly reported failure mode of sliding hip screws in published literature is cut-out of the lag screw. This study investigates the resistance to failure of the femoral head, with lag screws used in two types of sliding hip screws, the gamma locking nail (Howmedica) and the dynamic hip screw (DHS) (Synthes). The investigation consisted of biomechanical tests under

R. C. Haynes; R. G. Pöll; A. W. Miles; R. B. Weston

1997-01-01

143

Posterior short segment pedicle screw fixation and TLIF for the treatment of unstable thoracolumbar/lumbar fracture  

PubMed Central

Background Currently, Posterior Short Segment Pedicle Screw Fixation is a popular procedure for treating unstable thoracolumbar/lumbar burst fracture. But progressive kyphosis and a high rate of hardware failure because of lack of the anterior column support remains a concern. The efficacy of different methods remains debatable and each technique has its advantages and disadvantages. Methods A consecutive series of 20 patients with isolated thoracolumbar/lumbar burst fractures were treated by posterior short segment pedicle screw fixation and transforaminal thoracolumbar/lumbar interbody fusion (TLIF) between January 2005 and December 2007. All patients were followed up for a minimum of 2 years. Demographic data, neurologic status, anterior vertebral body heights, segmental Cobb angle and treatment-related complications were evaluated. Results The mean operative time was 167 minutes (range, 150–220). Blood loss was 450 ~ 1200 ml, an average of 820 ml. All patients recovered with solid fusion of the intervertebral bone graft, without main complications like misplacement of the pedicle screw, nerve or vessel lesion or hard ware failure. The post-operative radiographs demonstrated a good fracture reduction and it was well maintained until the bone graft fusion. Neurological recovery of one to three Frankel grade was seen in 14 patients with partial neurological deficit, three grades of improvement was seen in one patient, two grades of improvement was observed in 6 patients and one grade of improvement was found in 6 patients. All the 6 patients with no paraplegia on admission remained neurological intact, and in one patient with Frankel D on admission no improvement was observed. Conclusion Posterior short-segment pedicle fixation in conjunction with TLIF seems to be a feasible option in the management of selected thoracolumbar/lumbar burst fractures, thereby addressing all the three columns through a single approach with less trauma and good results.

2014-01-01

144

Stainless steel screws coated with bisphosphonates gave stronger fixation and more surrounding bone. Histomorphometry in rats  

Microsoft Academic Search

Coating of stainless steel screws with bisphosphonate in a fibrinogen matrix leads to an enhancement of the pullout strength 2 weeks after insertion in rat tibiae. This effect then increases over time until at least 8 weeks. The pullout force reflects the mechanical properties of the bone within the threads, which acts as a screw nut. The aim of the present study

K. Wermelin; F. Suska; P. Tengvall; P. Thomsen; P. Aspenberg

2008-01-01

145

3D mapping of safe and danger zones in the maxilla and mandible for the placement of intermaxillary fixation screws.  

PubMed

Intermaxillary (IMF) screws feature several advantages over other devices used for intermaxillary fixation, but using cone beam computed tomography (CBCT) scans to determine the safe and danger zones to place these devices for all patients can be expensive. This study aimed to determine the optimal interradicular and buccopalatal/buccolingual spaces for IMF screw placement in the maxilla and mandible. The CBCT volumetric data of 193 patients was used to generate transaxial slices between the second molar on the right to the second molar on the left in both arches. The mean interradicular and buccopalatal/buccolingual distances and standard deviation values were obtained at heights of 2, 5, 8 and 11 mm from the alveolar bone crest. An IMF screw with a diameter of 1.0 mm and length of 7 mm can be placed distal to the canines (2 - 11 mm from the alveolar crest) and less than 8 mm between the molars in the maxilla. In the mandible, the safest position is distal to the first premolar (more than 5 mm) and distal to the second premolar (more than 2 mm). There was a significant difference (p<0.05) between the right and left quadrants. The colour coding 3D template showed the safe and danger zones based on the mesiodistal, buccopalatal and buccolingual distances in the maxilla and mandible.The safest sites for IMF screw insertion in the maxilla were between the canines and first premolars and between the first and second molars. In the mandible, the safest sites were between the first and second premolars and between the second premolar and first molar. However, the IMF screw should not exceed 1.0 mm in diameter and 7 mm in length. PMID:24367643

Purmal, Kathiravan; Alam, Mohammad Khursheed; Pohchi, Abdullah; Abdul Razak, Noor Hayati

2013-01-01

146

Is a Sliding Hip Screw or IM Nail the Preferred Implant for Intertrochanteric Fracture Fixation?  

PubMed Central

This study was performed to determine whether patients who sustain an intertrochanteric fracture have better outcomes when stabilized using a sliding hip screw or an intramedullary nail. A 20% sample of Part A and B entitled Medicare beneficiaries 65 years or older was used to generate a cohort of patients who sustained intertrochanteric femur fractures between 1999 and 2001. Two fracture implant groups, intramedullary nail and sliding hip screw, were identified using Current Procedural Terminology and International Classification of Diseases, 9th Revision codes. The cohort consisted of 43,659 patients. Patients treated with an intramedullary nail had higher rates of revision surgery during the first year than those treated with a sliding hip screw (7.2% intramedullary nail versus 5.5% sliding hip screw). Mortality rates at 30 days (14.2% intramedullary nail versus 15.8% sliding hip screw) and 1 year (30.7% intramedullary nail versus 32.5% sliding hip screw) were similar. Adjusted secondary outcome measures showed significant increases in the intramedullary nail group relative to the sliding hip screw group for index hospital length of stay, days of rehabilitation services in the first 6 months after discharge, and total expenditures for doctor and hospital services. Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Aros, Brian; Tosteson, Anna N. A.; Gottlieb, Daniel J.

2008-01-01

147

Pedicle versus laminar screws: what provides more suitable C2 fixation in congenital C2-3 fusion patients?  

PubMed Central

Patients with Klippel–Feil syndrome (KFS) have congenital fusions of at least 1 cervical motion segment, and often present with compensatory hypermobility or symptomatic stenosis of the cranio-vertebral junction which requires occipitocervical reconstruction and fusion. One subgroup of KFS patients in which this is particularly common is those with isolated C2–3 congenital fusion (C2–3 CF). The anatomic suitability for C2 pedicle and laminar screw placement had been analyzed in the general adult population, and guidelines for their techniques had been established. However, the feasibility and safety of the two techniques in KFS patients with congenital C2–3 fusion has not been reported. This radiographic study was performed to evaluate the feasibility of these two widely used methods in such patients. We recruited 108 patients with atlantoaxial dislocation and reconstructed CTs were performed. Among them, 53 had C2–C3 congenital fusion diagnosed as KFS and 55 had normal cervical segmentation (NCS). The maximum possible diameters and length were measured along the ideal screw trajectories. Both of mean diameters and lengths of the C2 laminar screw trajectory in the C2–3 CF group were significantly larger than that in NCS. Mean diameters of the C2 pedicle screw trajectory in this group were significantly smaller than that in NCS group, however, C2–3 CF patients had longer pedicle paths than NCS. In the C2–3 CF group, all 53 cases had suitable trajectory for C2 laminar screw, while 21 (39.6%) had a pedicle diameter less than 4.5 mm. In the NCS group, 5 cases (9.1%) had a pedicle diameter less than 4.5 mm. All 108 cases had sufficient diameters for C2 laminar screw placement. Klippel–Feil patients with C2–3 CF are good candidates for the technique of C2 laminar screw. Preoperative radiography should be carefully evaluated and the option of C2 fixation be determined with a thorough consideration in these patients.

Wang, Shenglin; Passias, Peter G.; Yan, Ming; Zhou, Haitao

2010-01-01

148

One-Stage Posterior Debridement and Transpedicular Screw Fixation for Treating Monosegmental Thoracic and Lumbar Spinal Tuberculosis in Adults  

PubMed Central

Spinal tuberculosis is still prevalent in some developing countries. The purpose of this study is to investigate the efficacy and safety of one-stage posterior debridement, autogenous bone grafting, and transpedicular screw fixation in treating monosegmental thoracic and lumbar tuberculosis in adults. 37 patients were retrospectively reviewed in this study. The data of images, operative time and blood loss volume, perioperative complications, time to achieve bony fusion, VAS score, and neurologic function preoperatively and postoperatively were collected. The mean follow-up period was 21.5 ± 3.5 months. The tuberculosis was cured after surgery in all patients, and no recurrence was observed. Bony fusion was achieved in all patients with a mean time of 5.6 ± 2.5 months. Neurological outcome did not change in one case with grade A, and increased by 1–3 grades in the other patients with nerve deficit. The average preoperative and postoperative VAS scores were 5.5 ± 2.23 and 1.5 ± 1.22, respectively; the difference was significant (P < 0.05). There were three perioperative complications (8.1%, 3/37) observed in this study. In conclusion, the procedure of one-stage posterior debridement, interbody fusion with autogenous bone grafting, and posterior fixation with pedicle screw is effective and safe for treating monosegmental thoracic and lumbar spinal tuberculosis in adults.

Liu, Zhili; Peng, Aifeng; Long, Xinhua; Yang, Dong; Huang, Shanhu

2014-01-01

149

Effects of different mandibular fracture patterns on the stability of miniplate screw fixation in angle mandibular fractures.  

PubMed

The aim of the present study was to evaluate the effects of horizontally favourable and unfavourable mandibular fracture patterns on the fixation stability of titanium plates and screws by simulating chewing forces. Favourable and unfavourable mandibular fractures on 22 sheep hemimandibles were fixed with 4-hole straight titanium plates and 2.0mm×7mm titanium screws according to the Champy technique. Hemimandibles were mounted with a fixation device in a servohydraulic testing unit for compressive testing. Displacement values under 20, 60, 100, 120, 150, 200N, maximum displacements, and maximum forces the model could resist before breakage were recorded and compared. The authors found no statistically significant differences between the groups for the displacement values in the force range 60-200N (60, 100, 120, 150 and 200N). Statistically significant differences for maximum displacement values (displacement values at the breaking forces) between the groups were found (P<0.05). There was no evidence for the need to apply different treatment modalities to mandibular fractures regardless of whether the factures are favourable or not. PMID:22178275

Pektas, Z O; Bayram, B; Balcik, C; Develi, T; Uckan, S

2012-03-01

150

One-stage posterior debridement and transpedicular screw fixation for treating monosegmental thoracic and lumbar spinal tuberculosis in adults.  

PubMed

Spinal tuberculosis is still prevalent in some developing countries. The purpose of this study is to investigate the efficacy and safety of one-stage posterior debridement, autogenous bone grafting, and transpedicular screw fixation in treating monosegmental thoracic and lumbar tuberculosis in adults. 37 patients were retrospectively reviewed in this study. The data of images, operative time and blood loss volume, perioperative complications, time to achieve bony fusion, VAS score, and neurologic function preoperatively and postoperatively were collected. The mean follow-up period was 21.5 ± 3.5 months. The tuberculosis was cured after surgery in all patients, and no recurrence was observed. Bony fusion was achieved in all patients with a mean time of 5.6 ± 2.5 months. Neurological outcome did not change in one case with grade A, and increased by 1-3 grades in the other patients with nerve deficit. The average preoperative and postoperative VAS scores were 5.5 ± 2.23 and 1.5 ± 1.22, respectively; the difference was significant (P < 0.05). There were three perioperative complications (8.1%, 3/37) observed in this study. In conclusion, the procedure of one-stage posterior debridement, interbody fusion with autogenous bone grafting, and posterior fixation with pedicle screw is effective and safe for treating monosegmental thoracic and lumbar spinal tuberculosis in adults. PMID:24701134

Liu, Zhili; Liu, Jiaming; Peng, Aifeng; Long, Xinhua; Yang, Dong; Huang, Shanhu

2014-01-01

151

Hydroxyapatite coating enhances fixation of loaded pedicle screws: a mechanical in vivo study in sheep  

Microsoft Academic Search

Loosening of the pedicle screws with subsequent non-union or loss of correction is a frequent problem in spinal instrumentation. In a clinical pilot study, coating of pedicle screws with plasma-sprayed hydroxyapatite (HA) resulted in a significant increase of removal torque. An experimental study was performed to investigate the effects of HA coating on the pull-out resistance. Thirteen sheep were operated

Bengt Sandén; Claes Olerud; Sune Larsson

2001-01-01

152

The anatomic variability of human cervical pedicles: considerations for transpedicular screw fixation in the middle and lower cervical spine.  

PubMed

Transpedicular screw fixation has recently been shown to be successful in stabilizing the middle and lower cervical spine. Controversy exists, however, over its efficacy, due to the smaller size of cervical pedicles and the proximity of significant neurovascular structures to both lateral and medial cortical walls. To aid the spinal surgeon in the insertion of pedicle screws, a number of studies have been performed to quantify the gross dimensions and angulations of the cervical pedicle. Notwithstanding these quantitative studies, there has been a conspicuous absence of research reporting the qualitative characteristics of the cervical pedicle. The purpose of our study was to provide comparative graphical data that would systematically document the anatomic variability in cervical pedicle morphology. Such information should better elucidate the complexity of the pedicle as a three-dimensional structure and provide the spinal surgeon with a more complete understanding of cervical pedicle architecture. Twenty-six human cervical vertebrae (C3-C7) from six fresh-frozen spines were secured to a thin sectioning apparatus to produce three 0.7-mm-thick pedicle slices along its axis. Radiographs taken of these pedicle slices were scanned, digitized, and traced to facilitate visual comparison. The pedicle slices were found to exhibit substantial variability in composition and shape, not only between individual spines and vertebral levels, but also within the pedicle axis. However, the lateral cortex was consistently found to be thinner than the medial cortex in all samples. These physical findings must be noted by surgeons attempting transpedicular screw fixation in the cervical spine. PMID:10766079

Shin, E K; Panjabi, M M; Chen, N C; Wang, J L

2000-02-01

153

Fixation of lapidus arthrodesis with a plantar interfragmentary screw and medial locking plate: a report of 88 cases.  

PubMed

Lapidus arthrodesis is a powerful procedure that can be used to correct pathologic features within the forefoot or midfoot. Many different methods of fixation for this procedure have been reported. The use of plating constructs has been shown to provide increased stability compared with screw-only constructs. The technique we have described consists of a plantar to dorsal retrograde lag screw across the arthrodesis site, coupled with a low-profile medial locking plate. A total of 88 consecutive patients were treated with this modification of the Lapidus procedure by 2 surgeons and were retrospectively evaluated. All patients followed an early postoperative weightbearing protocol. Patient age, gender, follow-up duration, interval to weightbearing and radiographic fusion, preoperative and postoperative intermetatarsal angle, hardware removal, preoperative and postoperative American Orthopaedic Foot and Ankle Society midfoot scores, and adjunct procedures were analyzed. The mean follow-up period was 16.76 ± 5.9 (range 12 to 36) months, and all healed fusions demonstrated radiographic union at a mean of 51 ± 19.1 (range 40 to 89) days. The patients were treated with weightbearing starting a mean of 10.90 ± 4.1 (range 5 to 28) days postoperatively. Complications included 15 patients (17%) requiring hardware removal, 2 cases (2%) of hallux varus, 6 cases (7%) of radiographic recurrent hallux valgus, and 2 patients (2%) with first metatarsocuneiform nonunion. The results of the present study have demonstrated that plantar lag screw fixation with medial locking plate augmentation for Lapidus arthrodesis allows for early weightbearing with satisfactory outcomes, improved clinical and radiographic alignment, and improved American Orthopaedic Foot and Ankle Society scores. PMID:23540755

Cottom, James M; Vora, Anand M

2013-01-01

154

Arthroscopic anterior cruciate ligament reconstruction with modified “wireless” cross-screw transfix femoral fixation  

Microsoft Academic Search

Among several graft fixation options in arthroscopic ACL reconstruction for hamstring tendons, transcondylar fixation has\\u000a been suggested to offer mechanical advantages compared to other femoral fixation systems. Blind nature of the procedure may\\u000a result in several complications including iliotibial band irritation syndrome, breakage of the bio absorbable cross-pin, stress\\u000a fracture of the femoral cortex, and more commonly intraoperative wire loop

Fereidoon M. Jaberi; Ali Haghighat; Zahra Babanezhad; Mehrad M. Jaberi

2010-01-01

155

The Retroacetabular Angle Determines the Safe Angle for Screw Placement in Posterior Acetabular Fracture Fixation  

PubMed Central

Introduction. A method for the determination of safe angles for screws placed in the posterior acetabular wall based on preoperative computed tomography (CT) is described. It defines a retroacetabular angle and determines its variation in the population. Methods. The retroacetabular angle is the angle between the retroacetabular surface and the tangent to the posterior acetabular articular surface. Screws placed through the marginal posterior wall at an angle equal to the retroacetabular angle are extraarticular. Medial screws can be placed at larger angles whose difference from the retroacetabular angle is defined as the allowance angles. CT scans of all patients with acetabular fractures treated in our institute between September 2002 to July 2007 were used to measure the retroacetabular angle and tangent. Results. Two hundred thirty one patients were included. The average (range) age was 42 (15–74) years. The average (range) retroacetabular angle was 39 (30–47) degrees. The average (range) retroacetabular tangent was 36 (30–45)?mm. Conclusions. Placing the screws at an average (range) angle of 39 (33–47) degrees of anterior inclination with the retroacetabular surface makes them extraarticular. Angles for medial screws are larger. Safe angles can be calculated preoperatively with a computer program.

Tadros, Ayman M. A.; Oxland, Thomas R.; O'Brien, Peter

2013-01-01

156

Iatrogenic injury of profunda femoris artery branches after intertrochanteric hip screw fixation for intertrochanteric femoral fracture: a case report and literature review.  

PubMed

A case of arterial rupture of the profunda femoris arterial branches, following dynamic hip screw (DHS) fixation for an intertrochanteric femoral fracture, is presented. Bleeding is controlled by coil embolization, but, later on, the patient underwent orthopedic material removal due to an infection of a large femoral hematoma. PMID:24716097

Patelis, Nikolaos; Koutsoumpelis, Andreas; Papoutsis, Konstantinos; Kouvelos, George; Vergadis, Chrysovalantis; Mourikis, Anastasios; Georgopoulos, Sotiris E

2014-01-01

157

Biomechanical comparison of unilateral and bilateral pedicle screws fixation for transforaminal lumbar interbody fusion after decompressive surgery -- a finite element analysis  

PubMed Central

Background Little is known about the biomechanical effectiveness of transforaminal lumbar interbody fusion (TLIF) cages in different positioning and various posterior implants used after decompressive surgery. The use of the various implants will induce the kinematic and mechanical changes in range of motion (ROM) and stresses at the surgical and adjacent segments. Unilateral pedicle screw with or without supplementary facet screw fixation in the minimally invasive TLIF procedure has not been ascertained to provide adequate stability without the need to expose on the contralateral side. This study used finite element (FE) models to investigate biomechanical differences in ROM and stress on the neighboring structures after TLIF cages insertion in conjunction with posterior fixation. Methods A validated finite-element (FE) model of L1-S1 was established to implant three types of cages (TLIF with a single moon-shaped cage in the anterior or middle portion of vertebral bodies, and TLIF with a left diagonally placed ogival-shaped cage) from the left L4-5 level after unilateral decompressive surgery. Further, the effects of unilateral versus bilateral pedicle screw fixation (UPSF vs. BPSF) in each TLIF cage model was compared to analyze parameters, including stresses and ROM on the neighboring annulus, cage-vertebral interface and pedicle screws. Results All the TLIF cages positioned with BPSF showed similar ROM (<5%) at surgical and adjacent levels, except TLIF with an anterior cage in flexion (61% lower) and TLIF with a left diagonal cage in left lateral bending (33% lower) at surgical level. On the other hand, the TLIF cage models with left UPSF showed varying changes of ROM and annulus stress in extension, right lateral bending and right axial rotation at surgical level. In particular, the TLIF model with a diagonal cage, UPSF, and contralateral facet screw fixation stabilize segmental motion of the surgical level mostly in extension and contralaterally axial rotation. Prominent stress shielded to the contralateral annulus, cage-vertebral interface, and pedicle screw at surgical level. A supplementary facet screw fixation shared stresses around the neighboring tissues and revealed similar ROM and stress patterns to those models with BPSF. Conclusions TLIF surgery is not favored for asymmetrical positioning of a diagonal cage and UPSF used in contralateral axial rotation or lateral bending. Supplementation of a contralateral facet screw is recommended for the TLIF construct.

2012-01-01

158

Lag Screw Fixation of Fracture of the Anterior Mandible: A New Minimal Access Technique  

Microsoft Academic Search

Objective  Purpose of this study to introduce a new minimal access technique for management of anterior mandible fracture with several\\u000a advantages over conventional methods.\\u000a \\u000a \\u000a \\u000a \\u000a Method  Four cases of undisplaced anterior mandibular fracture were selected. Tension band was achieved either by arch bar fixation\\u000a to mandible or placement of interdental wire followed by intermaxillary fixation. With a 1 cm vertical incision was placed\\u000a adjacent

Sanjay Jadwani; Snehal Bansod

2011-01-01

159

A prospective, randomised trial comparing the use of absorbable and metallic screws in the fixation of distal tibiofibular syndesmosis injuries: mid-term follow-up.  

PubMed

Our aim was to compare polylevolactic acid screws with titanium screws when used for fixation of the distal tibiofibular syndesmosis at mid-term follow-up. A total of 168 patients, with a mean age of 38.5 years (18 to 72) who were randomly allocated to receive either polylevolactic acid (n = 86) or metallic (n = 82) screws were included. The Baird scoring system was used to assess the overall satisfaction and functional recovery post-operatively. The demographic details and characteristics of the injury were similar in the two groups. The mean follow-up was 55.8 months (48 to 66). The Baird scores were similar in the two groups at the final follow-up. Patients in the polylevolactic acid group had a greater mean dorsiflexion (p = 0.011) and plantar-flexion of the injured ankles (p < 0.001). In the same group, 18 patients had a mild and eight patients had a moderate foreign body reaction. In the metallic groups eight had mild and none had a moderate foreign body reaction (p < 0.001). In total, three patients in the polylevolactic acid group and none in the metallic group had heterotopic ossification (p = 0.246). We conclude that both screws provide adequate fixation and functional recovery, but polylevolactic acid screws are associated with a higher incidence of foreign body reactions. PMID:24692626

Sun, H; Luo, C F; Zhong, B; Shi, H P; Zhang, C Q; Zeng, B F

2014-04-01

160

Arthroscopically assisted reconstruction and percutaneous screw fixation of a pilon tibial malunion.  

PubMed

We report a case of distal tibial fracture (AO 43-C3) originally treated with close reduction and ligamentotaxis, which was seen at our institution at 6 weeks with malunion of the medial malleolus. It was successfully treated with arthroscopy-assisted mobilization of the malunion with subsequent percutaneous reduction and fixation. Four months after surgery, with an American Orthopedic Foot and Ankle Society score of 100, the patient felt no pain when walking. Techniques and postoperative treatment are described. PMID:17980852

Nehme, Alexandre; Tannous, Ziad; Wehbe, Joseph; Moucharafieh, Ramzi; Mecharrafieh, Ramzi; Maalouf, Ghassan

2007-01-01

161

Fixation with C-2 laminar screws in occipitocervical or C1-2 constructs in children 5 years of age or younger: a series of 18 patients.  

PubMed

Object There are rare indications for upper cervical spine fusion in young children. Compared with nonrigid constructs, rigid instrumentation with screw fixation increases the fusion rate and reduces the need for halo fixation. Instrumentation may be technically challenging in younger children. A number of screw placement techniques have been described. Use of C-2 translaminar screws has been shown to be anatomically feasible, even in the youngest of children. However, there are few data detailing the clinical outcome. In this study, the authors describe the clinical and radiographic follow-up of 18 children 5 years of age or younger who had at least one C-2 translaminar screw as part of an occipitocervical or C1-2 fusion construct. Methods A retrospective review of all children treated with instrumented occipitocervical or C1-2 fusion between July 1, 2007, and June 30, 2013, at Riley Children's Hospital and Texas Children's Hospital was performed. All children 5 years of age or younger with incorporation of at least one C-2 translaminar screw were identified. Results Eighteen children were studied (7 boys and 11 girls). The mean age at surgery was 38.1 months (range 10-68 months). Indications for surgery included traumatic instability (6), os odontoideum (3), destructive processes (2), and congenital instability (7). A total of 24 C-2 translaminar screws were placed; 23 (95.8%) of 24 were satisfactorily placed (completely contained within the cortical walls). There was one medial cortex breach without neurological impingement. There were no complications with screw placement. Three patients required wound revisions. Two patients died as a result of their original condition (trauma, malignant tumor). The mean follow-up duration for the surviving patients was 17.5 months (range 3-60 months). Eleven (91.7%) of the 12 patients followed for 6 months or longer showed radiographic stability or completed fusion. Conclusions Use of C-2 translaminar screws provides an effective anchor for internal fixation of the upper cervical spine. In this study of children 5 years of age or younger, the authors found a high rate of radiographic fusion with a low rate of complications. PMID:24784980

Savage, Jennifer G; Fulkerson, Daniel H; Sen, Anish N; Thomas, Jonathan G; Jea, Andrew

2014-07-01

162

A cementless, elastic press-fit socket with and without screws  

PubMed Central

Background The acetabular component has remained the weakest link in hip arthroplasty regarding achievement of long-term survival. Primary fixation is a prerequisite for long-term performance. For this reason, we investigated the stability of a unique cementless titanium-coated elastic monoblock socket and the influence of supplementary screw fixation. Patient and methods During 2006–2008, we performed a randomized controlled trial on 37 patients (mean age 63 years (SD 7), 22 females) in whom we implanted a cementless press-fit socket. The socket was implanted with additional screw fixation (group A, n = 19) and without additional screw fixation (group B, n = 18). Using radiostereometric analysis with a 2-year follow-up, we determined the stability of the socket. Clinically relevant migration was defined as > 1 mm translation and > 2º rotation. Clinical scores were determined. Results The sockets without screw fixation showed a statistically significantly higher proximal translation compared to the socket with additional screw fixation. However, this higher migration was below the clinically relevant threshold. The numbers of migratory sockets were not significantly different between groups. After the 2-year follow-up, there were no clinically relevant differences between groups A and B regarding the clinical scores. 1 patient dropped out of the study. In the others, no sockets were revised. Interpretation We found that additional screw fixation is not necessary to achieve stability of the cementless press-fit elastic RM socket. We saw no postoperative benefit or clinical effect of additional screw fixation.

2012-01-01

163

Anterolateral Corrective Lumbar Corpectomy and Interbody Fusion by Using Extended Screw Fixation without Posterior Instrumentation for Posttraumatic Kyphosis  

PubMed Central

A 26-year-old paraplegic schizophrenic Japanese woman suffered from severe kyphosis and back pain derived from lumbar burst fractures caused by jumping. She had already undergone resection of the L1 and L2 spinous processes for sharp angular kyphosis, but she still had severe kyphosis and back pain at the L1 and L2. Radiographical examination revealed fused anterior columns at L1 and L2 with severe local kyphosis and a significantly decreased percutaneous distance in the back. The patient underwent anterior instrumented bony resection including an L2 vertebral osteotomy: bilateral L2-L3 facetectomy and partial posterior osteotomy of the L2 vertebrae via a posterior approach followed by an anterior corpectomy of the L2 vertebrae and insertion of a cylindrical cage. No posterior instrumentation was used owing to the presence of atrophied paraspinal soft tissues. Lumbar interbody fusion was performed with vertebral body screws extending from T12 to L4 and corresponding anterior distension and posterior compression. The procedure corrected the kyphosis by 15° and enhanced local stability. Postsurgical visual analogue scale improved from 9.0 to 2.0 and Oswestry Disability Index from 40 to 17.8, respectively. In conclusion, we have demonstrated that anterolateral interbody fusion using extended fixation can compensate for posterior corrective surgery.

Yamazaki, Atsuro; Orita, Sumihisa; Sainoh, Takeshi; Yamauchi, Kazuyo; Suzuki, Miyako; Sakuma, Yoshihiro; Kubota, Go; Oikawa, Yasuhiro; Inage, Kazuhide; Nakata, Yukio; Inoue, Gen; Aoki, Yasuchika; Toyone, Tomoaki; Nakamura, Junichi; Miyagi, Masayuki; Takahashi, Kazuhisa; Ohtori, Seiji

2013-01-01

164

Three column stabilization through posterior approach alone: transpedicular placement of distractable cage with transpedicular screw fixation.  

PubMed

The combination of anterior and posterior instrumentation provides the most stable repair for burst fractures of the thoracolumbar spine. However, the use of both approaches on a trauma patient may increase morbidity. Stabilization of three columns through only one approach can provide an effective outcome. We treated eight patients with burst fracture involving the thoracic or lumbar vertebrae by the application of anterior and posterior stabilization instruments through only the posterior approach. The desired stabilization was obtained in all patients. The advantages are the absence of the risks of the anterior approach, facilitation of the placement of anterior and posterior stabilization devices through only one approach, preserving the unity of the anterior longitudinal ligament, the effect of the anterior corpus in preventing displacement of the cage, application of compression on the pedicle screw system to both decrease the kyphosis angulation due to collapse of vertebra and to help the stabilization of the cage, repair of the dural tears at the posterior side, prevention of cage displacement by distraction and thus leaning on the endplates, and ease of performance by a neurosurgeon alone. PMID:18219186

Ayberk, Giyas; Ozveren, Mehmet Faik; Altundal, Naci; Tosun, Hakan; Seckin, Zekai; Kilicarslan, Kasim; Kaplan, Metin

2008-01-01

165

Treatment of acute thoracolumbar burst fractures with kyphoplasty and short pedicle screw fixation: Transpedicular intracorporeal grafting with calcium phosphate: A prospective study  

PubMed Central

Background: In the surgical treatment of thoracolumbar fractures, the major problem after posterior correction and transpedicular instrumentation is failure to support the anterior spinal column, leading to loss of correction and instrumentation failure with associated complaints. We conducted this prospective study to evaluate the outcome of the treatment of acute thoracolumbar burst fractures by transpedicular balloon kyphoplasty, grafting with calcium phosphate cement and short pedicle screw fixation plus fusion. Materials and Methods: Twenty-three consecutive patients of thoracolumbar (T9 to L4) burst fracture with or without neurologic deficit with an average age of 43 years, were included in this prospective study. Twenty-one from the 23 patients had single burst fracture while the remaining two patients had a burst fracture and additionally an adjacent A1-type fracture. On admission six (26%) out of 23 patients had neurological deficit (five incomplete, one complete). Bilateral transpedicular balloon kyphoplasty with liquid calcium phosphate to reduce segmental kyphosis and restore vertebral body height and short (three vertebrae) pedicle screw instrumentation with posterolateral fusion was performed. Gardner kyphosis angle, anterior and posterior vertebral body height ratio and spinal canal encroachment were calculated pre- to postoperatively. Results: All 23 patients were operated within two days after admission and were followed for at least 12 months after index surgery. Operating time and blood loss averaged 45 min and 60 cc respectively. The five patients with incomplete neurological lesions improved by at least one ASIA grade, while no neurological deterioration was observed in any case. The VAS and SF-36 (Role physical and Bodily pain domains) were significantly improved postoperatively. Overall sagittal alignment was improved from an average preoperative 16° to one degree kyphosis at final followup observation. The anterior vertebral body height ratio improved from 0.6 preoperatively to 0.9 (P<0.001) postoperatively, while posterior vertebral body height improved from 0.95 to 1 (P<0.01). Spinal canal encroachment was reduced from an average 32% preoperatively to 20% postoperatively. Cement leakage was observed in four cases (three anterior to vertebral body and one into the disc without sequalae). In the last CT evaluation, there was a continuity between calcium phosphate and cancellous vertebral body bone. Posterolateral radiological fusion was achieved within six months after index operation. There was no instrumentation failure or measurable loss of sagittal curve and vertebral height correction in any group of patients. Conclusions: Balloon kyphoplasty with calcium phosphate cement secured with posterior short fixation in the thoracolumbar spine provided excellent immediate reduction of posttraumatic segmental kyphosis and significant spinal canal clearance and restored vertebral body height in the fracture level.

Korovessis, Panagiotis; Repantis, Thomas; George, Petsinis

2007-01-01

166

Percutaneous kyphoplasty and pedicle screw fixation for the management of thoraco-lumbar burst fractures  

PubMed Central

The study design includes prospective evaluation of percutaneous osteosynthesis associated with cement kyphoplasty on 18 patients. The objective of the study is to assess the efficacy of a percutaneous method of treating burst vertebral fractures in patients without neurological deficits. Even if burst fractures are frequent, no therapeutic agreement is available at the moment. We report in this study the results at 2 years with a percutaneous approach for the treatment of burst fractures. 18 patients were included in this study. All the patients had burst vertebral fractures classified type A3 on the Magerl scale, between levels T9 and L2. The patients’ mean age was 53 years (range 22–78 years) and the neurological examination was normal. A percutaneous approach was systematically used and a kyphoplasty was performed via the transpedicular pathway associated with percutaneous short-segment pedicle screw osteosynthesis. The patients’ follow-up included CT scan analysis, measurement of vertebral height recovery and local kyphosis, and clinical pain assessments. With this surgical approach, the mean vertebral height was improved by 25% and a mean improvement of 11.28° in the local kyphotic angle was obtained. 3 months after the operation, none of the patients were taking class II analgesics. The mean duration of their hospital stay was 4.5 days (range 3–7 days) and the mean follow-up period was 26 months (range 17–30 months). No significant changes in the results obtained were observed at the end of the follow-up period. Minimally invasive methods of treating burst vertebral fractures can be performed via the percutaneous pathway. This approach gives similar vertebral height recovery and kyphosis correction rates to those obtained with open surgery. It provides a short hospital stay, however, and might therefore constitute a useful alternative to open surgical methods.

Blondel, Benjamin; Metellus, Philippe; Gaudart, Jean; Adetchessi, Tarek; Dufour, Henry

2010-01-01

167

Biomechanical comparison of anterior lumbar interbody fusion: stand-alone interbody cage versus interbody cage with pedicle screw fixation - a finite element analysis  

PubMed Central

Background Anterior lumbar interbody fusion (ALIF) followed by pedicle screw fixation (PSF) is used to restore the height of the intervertebral disc and provide stability. Recently, stand-alone interbody cage with anterior fixation has been introduced, which eliminates the need for posterior surgery. We compared the biomechanics of the stand-alone interbody cage to that of the interbody cage with additional PSF in ALIF. Methods A three-dimensional, non-linear finite element model (FEM) of the L2-5 segment was modified to simulate ALIF in L3-4. The models were tested under the following conditions: (1) intact spine, (2) destabilized spine, (3) with the interbody cage alone (type 1), (4) with the stand-alone cage with anterior fixation (SynFix-LR®; type 2), and (5) with type 1 in addition to PSF (type 3). Range of motion (ROM) and the stiffness of the operated level, ROM of the adjacent segments, load sharing distribution, facet load, and vertebral body stress were quantified with external loading. Results The implanted models had decreased ROM and increased stiffness compared to those of the destabilized spine. The type 2 had differences in ROM limitation of 8%, 10%, 4%, and 6% in flexion, extension, axial rotation, and lateral bending, respectively, compared to those of type 3. Type 2 had decreased ROM of the upper and lower adjacent segments by 3-11% and 3-6%, respectively, compared to those of type 3. The greatest reduction in facet load at the operated level was observed in type 3 (71%), followed by type 2 (31%) and type 1 (23%). An increase in facet load at the adjacent level was highest in type 3, followed by type 2 and type 1. The distribution of load sharing in type 2 (anterior:posterior, 95:5) was similar to that of the intact spine (89:11), while type 3 migrated posterior (75:25) to the normal. Type 2 reduced about 15% of the stress on the lower vertebral endplate compared to that in type 1. The stress of type 2 increased two-fold compared to the stress of type 3, especially in extension. Conclusions The stand-alone interbody cage can provide sufficient stability, reduce stress in adjacent levels, and share the loading distribution in a manner similar to an intact spine.

2013-01-01

168

Segmental correction of adolescent idiopathic scoliosis by all-screw fixation method in adolescents and young adults. minimum 5 years follow-up with SF-36 questionnaire  

PubMed Central

Background In our institution, the fixation technique in treating idiopathic scoliosis was shifted from hybrid fixation to the all-screw method beginning in 2000. We conducted this study to assess the intermediate -term outcome of all-screw method in treating adolescent idiopathic scoliosis (AIS). Methods Forty-nine consecutive patients were retrospectively included with minimum of 5-year follow-up (mean, 6.1; range, 5.1-7.3 years). The average age of surgery was 18.5 ± 5.0 years. We assessed radiographic measurements at preoperative (Preop), postoperative (PO) and final follow-up (FFU) period. Curve correction rate, correction loss rate, complications, accuracy of pedicle screws and SF-36 scores were analyzed. Results The average major curve was corrected from 58.0 ± 13.0° Preop to 16.0 ± 9.0° PO(p < 0.0001), and increased to 18.4 ± 8.6°(p = 0.12) FFU. This revealed a 72.7% correction rate and a correction loss of 2.4° (3.92%). The thoracic kyphosis decreased little at FFU (22 ± 12° to 20 ± 6°, (p = 0.25)). Apical vertebral rotation decreased from 2.1 ± 0.8 PreOP to 0.8 ± 0.8 at FFU (Nash-Moe grading, p < 0.01). Among total 831 pedicle screws, 56 (6.7%) were found to be malpositioned. Compared with 2069 age-matched Taiwanese, SF-36 scores showed inferior result in 2 variables: physical function and role physical. Conclusion Follow-up more than 5 years, the authors suggest that all-screw method is an efficient and safe method.

2012-01-01

169

Syndesmosis screws: How many, what diameter, where and should they be removed? A literature review.  

PubMed

Although screw fixation remains the most commonly used method of syndesmosis fixation, the ideal screw size, placement, and number remain controversial. In addition, there has been debate as to whether the screw should always be removed, and a number of studies have looked at radiological and functional outcomes. In addition a number of cadaveric models have been developed, but the correlation between cadaveric findings and functional outcomes remains unclear. This systematic review of the literature aims to summarise the available evidence on how many screws should be placed, of what diameter, through how many cortices, at what level, and whether they should be removed. PMID:24917210

Peek, A C; Fitzgerald, C E; Charalambides, C

2014-08-01

170

Pooled Analysis of Non-Union, Re-Operation, Infection, and Approach Related Complications after Anterior Odontoid Screw Fixation  

PubMed Central

Background Anterior odontoid screw fixation (AOSF) has been one of the most popular treatments for odontoid fractures. However, the true efficacy of AOSF remains unclear. In this study, we aimed to provide the pooled rates of non-union, reoperation, infection, and approach related complications after AOSF for odontoid fractures. Methods We searched studies that discussed complications after AOSF for type II or type III odontoid fractures. A proportion meta-analysis was done and potential sources of heterogeneity were explored by meta-regression analysis. Results Of 972 references initially identified, 63 were eligible for inclusion. 54 studies provided data regarding non-union. The pooled non-union rate was 10% (95% CI: 7%–3%). 48 citations provided re-operation information with a pooled proportion of 5% (95% CI: 3%–7%). Infection was described in 20 studies with an overall rate of 0.2% (95% CI: 0%–1.2%). The main approach related complication is postoperative dysphagia with a pooled rate of 10% (95% CI: 4%–17%). Proportions for the other approach related complications such as postoperative hoarseness (1.2%, 95% CI: 0%–3.7%), esophageal/retropharyngeal injury (0%, 95% CI: 0%–1.1%), wound hematomas (0.2%, 95% CI: 0%–1.8%), and spinal cord injury (0%, 95% CI: 0%–0.2%) were very low. Significant heterogeneities were detected when we combined the rates of non-union, re-operation, and dysphagia. Multivariate meta-regression analysis showed that old age was significantly predictive of non-union. Subgroup comparisons showed significant higher non-union rates in age ?70 than that in age ?40 and in age 40 to <50. Meta-regression analysis did not reveal any examined variables influencing the re-operation rate. Meta-regression analysis showed age had a significant effect on the dysphagia rate. Conclusions/Significances This study summarized the rates of non-union, reoperation, infection, and approach related complications after AOSF for odontoid factures. Elderly patients were more likely to experience non-union and dysphagia.

Tian, Nai-Feng; Hu, Xu-Qi; Wu, Li-Jun; Wu, Xin-Lei; Wu, Yao-Sen; Zhang, Xiao-Lei; Wang, Xiang-Yang; Chi, Yong-Long; Mao, Fang-Min

2014-01-01

171

Percutaneous Pedicle Screw Fixation of a Hangman's Fracture Using Intraoperative, Full Rotation, Three-dimensional Image (O-arm)-based Navigation: A Technical Case Report  

PubMed Central

Surgical treatment of a hangman's fractures is technically demanding, even when using the standard open procedure. In this case report, a type II hangman's fracture was treated by percutaneous posterior screw fixation, without a midline incision, using intraoperative, full rotation, three-dimensional (3D) image (O-arm)-based navigation. A 48-year-old woman was injured in a motor vehicle accident and diagnosed with a unilateral hangman's fracture associated with subluxation of the C2 vertebral body on C3. After attaching the reference arc of the 3D-imaging system to the headholder, the cervical spine was screened using an O-arm without anatomical registration. Drilling and screw fixation were performed using a guide tube while referring to the reconstructed 3D-anatomical views. The operation was successfully completed without technical difficulties or neurovascular complications. This percutaneous procedure requires less dissection of normal tissue, which may allow earlier recovery. However, further validation of this procedure for its effectiveness and safety is required.

Kanemura, Tokumi; Ishikawa, Yoshimoto

2012-01-01

172

Bilateral C1-C2 Transarticular Screw and C1 Laminar Hook Fixation and Bone Graft Fusion for Reducible Atlantoaxial Dislocation: A Seven-Year Analysis of Outcome  

PubMed Central

Background Bilateral C1-2 transarticular screw and C1 laminar hook fixation was developed on the basis of transarticular screws fixation. The modified technique has showed a better biomechanical stability than established techniques in previous study. However, long-term (minimum follow-up 7 years) outcomes of patients with reducible atlantoaxial dislocation who underwent this modified fixation technique have not still been reported. Methods A retrospective study was conducted to evaluate the outcome of 36 patients who underwent this modified technique. Myelopathy was assessed using the Ranawat myelopathy score and Myelopathy Disability Index. Pain scores were assessed using Visual Analogue Scale. Radiological imaging was assessed and the following data were extracted: the atlantodental intervals, the space available for cord, presence of spinal cord signal change on T2 weighted image, C1–C2 angle, C2–C7 angle and fusion rates. Findings All patients achieved a minimum seven-year follow up. 95% patients with neck and suboccipital pain improved after surgery; in their Visual Analogue pain scores, there was a greater than 50% improvement in their VAS scores with a drop of 5 points on the VAS (P<0.05). 92% of patients improved in the Ranawat myelopathy grade; the Myelopathy Disability Index assessment showed a preoperative mean score of 35.62 with postoperative mean 12.75(P<0.05). There was not any significant atlantoaxial instability at each follow-up time. The space available for cord increased in all patients. Postoperative sagittal kyphosis of the subaxial spine was not observed. After six months after surgery, bone grafts of all patients were fused. No complications related to surgery were found in the period of follow-up. Conclusions The long-term outcomes of this case series demonstrate that under the condition of thorough preoperative preparations, bilateral C1–C2 transarticular screw and C1 laminar hook fixation and bone graft fusion is a reliable posterior atlantoaxial fusion technique for reducible atlantoaxial dislocation.

Guo, Xiang; Ni, Bin; Xie, Ning; Lu, Xuhua; Guo, Qunfeng; Lu, Ming

2014-01-01

173

Hybrid Fixation of Tibial Eminence Fractures in Skeletally Immature Patients  

PubMed Central

Tibial eminence fractures most commonly occur in children and adolescents. When treating displaced fractures of the tibial eminence, some surgeons prefer screw fixation whereas others prefer suture fixation. The ultimate goal is to limit morbidity through early return to range of motion and activity. In this technical note, we describe 2 hybrid fixation techniques for fixing tibial eminence fractures, one for type III and the other for type IV fractures. The first technique (variation A) is used to treat type III fractures and combines use of both a bioabsorbable compression screw and suture for fixation. The second technique (variation B) is used to treat type IV fractures and combines use of both a bioabsorbable compression screw and shoulder anchor fixation. We have found that these methods provide efficient, secure, and reliable fixation using standard techniques common to arthroscopic surgery. In addition, the growth plates are spared in children and adolescents, and the need for reoperation to remove hardware is eliminated.

Gans, Itai; Babatunde, Oladapo M.; Ganley, Theodore J.

2013-01-01

174

Arterial Injury to the Profunda Femoris Artery following Internal Fixation of a Neck of Femur Fracture with a Compression Hip Screw.  

PubMed

We report the case of an 82-year-old woman who developed extensive proximal thigh swelling and persistent anaemia following internal fixation of an extracapsular neck of femur fracture with a dynamic hip screw (DHS). This was revealed to be a pseudoaneurysm of a branch of profunda femoris artery on angiography. Her case was further complicated by a concurrent pulmonary embolism (PE). She underwent endovascular coil embolisation of the pseudoaneurysm. An IVC filter was inserted and the patient was fully anticoagulated once it had been ensured that there was no active bleeding. In this case, we review the potential for anatomical variations in the blood supply to this region and discuss treatment options for a complicated patient. We recommend that a pseudoaneurysm should be part of a differential diagnosis for postoperative patients with anaemia refractory to blood transfusion so as not to miss this rare but potentially serious complication. PMID:24455367

Craxford, Simon; Gale, Michael; Lammin, Kimberly

2013-01-01

175

Pullout strength of pedicle screws with cement augmentation in severe osteoporosis: A comparative study between cannulated screws with cement injection and solid screws with cement pre-filling  

Microsoft Academic Search

BACKGROUND: Pedicle screws with PMMA cement augmentation have been shown to significantly improve the fixation strength in a severely osteoporotic spine. However, the efficacy of screw fixation for different cement augmentation techniques, namely solid screws with retrograde cement pre-filling versus cannulated screws with cement injection through perforation, remains unknown. This study aimed to determine the difference in pullout strength between

Lih-Huei Chen; Ching-Lung Tai; De-Mei Lee; Po-Liang Lai; Yen-Chen Lee; Chi-Chien Niu; Wen-Jer Chen

2011-01-01

176

Internal Fixation for Fractures  

MedlinePLUS

... implants, such as plates, screws, nails and wires. Internal fixation allows shorter hospital stays, enables patients to ... position) of broken bones. The implants used for internal fixation are made from stainless steel and titanium, ...

177

Corrective osteotomy through fracture site and internal fixation with headless screws for type I (Hahn-Steinthal) capitellar malunion.  

PubMed

A 20-year-old woman presented 6 months after an initial injury to her left elbow with pain and restricted movements. She was diagnosed with a type I malunited (Hahn-Steinthal) type of capitellum fracture through radiographic studies. Classically, the treatment has been excision of the fragment, which carries a risk of valgus instability of the elbow and late osteoarthrosis. We report a case of malunited type I capitellum fracture, for which corrective osteotomy through fracture site, open reduction and internal fixation was done 6 months following missed trauma. At 24 months follow-up the capitellum fracture had united and the patient has a stable elbow and excellent range of motion. Our case demonstrates that for type I malunited capitellum fractures corrective osteotomy through fracture site and internal fixation rather than excision of the fragment in young can result in successful union and stable elbow. PMID:23709538

Jeevannavar, Santosh Somayya; Shenoy, Keshav Someshwar; Daddimani, Ravi M

2013-01-01

178

Proximal metatarsal osteotomy for hallux valgus: an audit of radiologic outcome after single screw fixation and full postoperative weightbearing  

PubMed Central

Background Proximal metatarsal osteotomy combined with a distal soft-tissue procedure is a common treatment for moderate to severe hallux valgus. Secure stabilisation of the metatarsal osteotomy is necessary to avoid complications such as delayed union, nonunion or malunion as well as loss of correction. The aim of this study was to report our results using a single screw for stabilisation of the osteotomy. Methods We retrospectively reviewed 151 patients with severe hallux valgus who were treated by the above mentioned way with full postoperative weightbearing in a stiff soled shoe. Mean age of patients at time of surgery was 54 years, 19 patients were male and 132 female. Assessment of clinical and radiographic results was performed after 2 days and 6 weeks. Results were also correlated to the experience of the performing surgeon. Results Mean preoperative HVA (hallux valgus angle) was 36.4 degrees, and then 3.5 degrees 2 days and 13.4 degrees 6 weeks after the procedure (p < 0.001). Mean preoperative IMA (intermetarsal angle) was 16.8 degrees, and then 6.4 degrees after 2 days and 9.8 degrees after 6 weeks (p < 0.001). Mean preoperative first metatarsal length of 56.4 mm decreased to 53.6 mm after 6 weeks. Possible non-union of the osteotomy was observed in 4 patients (2.6%) after 6 weeks. Performing residents (n = 40) operated in 65 minutes and attending surgeons (n = 111) in 45 minutes, with no significant differences in radiographic measurements between both groups. Conclusions Single screw stabilisation of proximal chevron osteotomy is a reliable method for treating severe hallux valgus deformities with satisfactory results.

2013-01-01

179

Coracoid bone graft osteolysis after Latarjet procedure: A comparison study between two screws standard technique vs mini-plate fixation  

PubMed Central

Aims: One of the reason for Latarjet procedure failure may be coracoid graft osteolysis. In this study, we aimed to understand if a better compression between the coracoid process and the glenoid, using a mini-plate fixation during the Latarjet procedure, could reduce the amount of coracoid graft osteolysis. Materials and Methods: A computed tomography scan analysis of 26 prospectively followed-up patients was conducted after modified Latarjet procedure using mini-plate fixation technique to determine both the location and the amount of coracoid graft osteolysis in them. We then compared our current results with results from that of our previous study without using mini-plate fixation to determine if there is any statistical significant difference in terms of corcacoid bone graft osteolysis between the two surgical techniques. Results: The most relevant osteolysis was represented by the superficial part of the proximal coracoid, whereas the deep part of the proximal coracoid graft is least involved in osteolysis and has best bone healing. The current study showed a significant difference only for the deep part of the distal coracoid with our previous study (P < 0.01). Discussion: To our knowledge, there are no studies in literature that show the causes of coracoid bone graft osteolysis after Latarjet procedure. Conclusion: Our study suggests that there is a significant difference only for the deep part of the distal coracoid in terms of osteolysis. At clinical examination, this difference did not correspond with any clinical findings. Level of Evidence: Level 4. Clinical Relevance: Prospective case series, Treatment study.

Giacomo, Giovanni Di; Costantini, Alberto; de Gasperis, Nicola; De Vita, Andrea; Lin, Bernard K. H.; Francone, Marco; Beccaglia, Mario A. Rojas; Mastantuono, Marco

2013-01-01

180

Posterior transodontoid fixation: A new fixation (Kotil) technique  

PubMed Central

Anterior odontoid screw fixation or posterior C1-2 fusion techniques are routinely used in the treatment of Type II odontoid fractures, but these techniques may be inadequate in some types of odontoid fractures. In this new technique (Kotil technique), through a posterior bilateral approach, transarticular screw fixation was performed at the non-dominant vertebral artery (VA) side and posterior transodontoid fixation technique was performed at the dominant VA side. C1-2 complex fusion was aimed with unilateral transarticular fixation and odontoid fixation with posterior transodontoid screw fixation. Cervical spinal computed tomography (CT) of a 40-year-old male patient involved in a motor vehicle accident revealed an anteriorly dislocated Type II oblique dens fracture, not reducible by closed traction. Before the operation, the patient was found to have a dominant right VA with Doppler ultrasound. He was operated through a posterior approach. At first, transarticular screw fixation was performed at the non-dominant (left) side, and then fixation of the odontoid fracture was achieved by directing the contralateral screw (supplemental screw) medially and toward the apex. Cancellous autograft was scattered for fusion without the need for structural bone graft or wiring. Postoperative cervical spinal CT of the patient revealed that stabilization was maintained with transarticular screw fixation and reduction and fixation of the odontoid process was achieved completely by posterior transodontoid screw fixation. The patient is at the sixth month of follow-up and complete fusion has developed. With this new surgical technique, C1-2 fusion is maintained with transarticular screw fixation and odontoid process is fixed by concomitant contralateral posterior transodontoid screw (supplemental screw) fixation; thus, this technique both stabilizes the C1-2 complex and fixes the odontoid process and the corpus in atypical odontoid fractures, appearing as an alternative new technique among the previously defined C1-C2 fixation techniques in eligible cases.

Kotil, Kad?r; Koksal, Neslihan sutpideler; Kayac?, Selim

2011-01-01

181

Evaluation of femoral head vascularization in slipped capital femoral epiphysis before and after cannulated screw fixation with use of contrast-enhanced MRI: initial results.  

PubMed

In this study we used contrast-enhanced magnetic resonance imaging (MRI) to evaluate the vascularization of the femoral head in children with slipped capital femoral epiphysis (SCFE) before and after cannulated screw fixation. Eleven consecutive children with SCFE, seven boys and four girls, aged 10-15 years were included in the study. There were no preslips; four children had acute, three acute-on-chronic, and four chronic SCFE. The MRI examinations were performed in a 1.5 Tesla MR scanner with use of a coronal STIR sequence, a coronal contrast-enhanced T1-weighted spin-echo sequence, and a sagittal three-dimensional gradient-echo sequence. Morphology, signal intensities, and contrast-enhancement of the femoral head were assessed by two radiologists in consensus. Morphologic distortion of the physis, bone marrow edema within the metaphysis and epiphysis, and joint effusion were the preoperative MRI findings of SCFE in each child. In nine children, the vascularization of the femoral head before and after surgery was normal. In one child, a preoperative avascular zone in the superolateral aspect of the epiphysis revascularized completely after surgery. One child with severe SCFE developed avascular necrosis of the femoral head after open reduction of the slip. We conclude that MRI allows for accurate evaluation of the femoral head vascularization before and after surgery in children with SCFE. PMID:16625344

Staatz, G; Honnef, D; Kochs, A; Hohl, C; Schmidt, T; Röhrig, H; Günther, R W

2007-01-01

182

Transpedicular vertebral body augmentation reinforced with pedicle screw fixation in fresh traumatic A2 and A3 lumbar fractures: comparison between two devices and two bone cements.  

PubMed

This retrospective study compares efficacy and safety of balloon kyphoplasty (BK) with calcium phosphate (Group A) versus KIVA implant with PMMA (Group B) reinforced with three vertebrae pedicle screw constructs for A2 and A3 single fresh non-osteoporotic lumbar (L1-L4) fractures in 38 consecutive age- and diagnosis-matched patient populations. Extracanal leakage of both low-viscosity PMMA and calcium phosphate (CP) as well as the following roentgenographic parameters: segmental kyphosis (SKA), anterior (AVBHr) and posterior (PVBHr) vertebral body height ratio, spinal canal encroachment (SCE) clearance, and functional outcome measures: VAS and SF-36, were recorded and compared between the two groups. All patients in both groups were followed for a minimum 26 (Group A) and 25 (Group B) months. Extracanal CP and PMMA leakage was observed in four (18 %) and three (15 %) vertebrae/patients of group A and B, respectively. Hybrid fixation improved AVBHr, SKA, SCE, but PVBHr only in group B. VAS and SF-36 improved postoperatively in the patients of both groups. Short-segment construct with the novel KIVA implant restored better than BK-fractured lumbar vertebral body, but this had no impact in functional outcome. Since there was no leakage difference between PMMA and calcium phosphate and no short-term adverse related to PMMA use were observed, we advice the use of PMMA in fresh traumatic lumbar fractures. PMID:23982115

Korovessis, Panagiotis; Vardakastanis, Konstantinos; Repantis, Thomas; Vitsas, Vasilios

2014-07-01

183

Resorbable screws versus pins for optimal transplant fixation (SPOT) in anterior cruciate ligament replacement with autologous hamstring grafts: rationale and design of a randomized, controlled, patient and investigator blinded trial [ISRCTN17384369  

PubMed Central

Background Ruptures of the anterior cruciate ligament (ACL) are common injuries to the knee joint. Arthroscopic ACL replacement by autologous tendon grafts has established itself as a standard of care. Data from both experimental and observational studies suggest that surgical reconstruction does not fully restore knee stability. Persisting anterior laxity may lead to recurrent episodes of giving-way and cartilage damage. This might at least in part depend on the method of graft fixation in the bony tunnels. Whereas resorbable screws are easy to handle, pins may better preserve graft tension. The objective of this study is to determine whether pinning of ACL grafts reduces residual anterior laxity six months after surgery as compared to screw fixation. Design/ Methods SPOT is a randomised, controlled, patient and investigator blinded trial conducted at a single academic institution. Eligible patients are scheduled to arthroscopic ACL repair with triple-stranded hamstring grafts, conducted by a single, experienced surgeon. Intraoperatively, subjects willing to engage in this study will be randomised to transplant tethering with either resorbable screws or resorbable pins. No other changes apply to locally established treatment protocols. Patients and clinical investigators will remain blinded to the assigned fixation method until the six-month follow-up examination. The primary outcome is the side-to-side (repaired to healthy knee) difference in anterior translation as measured by the KT-1000 arthrometer at a defined load (89 N) six months after surgery. A sample size of 54 patients will yield a power of 80% to detect a difference of 1.0 mm ± standard deviation 1.2 mm at a two-sided alpha of 5% with a t-test for independent samples. Secondary outcomes (generic and disease-specific measures of quality of life, magnetic resonance imaging morphology of transplants and devices) will be handled in an exploratory fashion. Conclusion SPOT aims at showing a reduction in anterior knee laxity after fixing ACL grafts by pins compared to screws.

Stengel, Dirk; Matthes, Gerrit; Seifert, Julia; Tober, Volker; Mutze, Sven; Rademacher, Grit; Ekkernkamp, Axel; Bauwens, Kai; Wich, Michael; Casper, Dirk

2005-01-01

184

Orientation of the "Lisfranc screw".  

PubMed

The reduction and stabilization of diastases between the medial cuneiform and the base of second metatarsal after a Lisfranc ligament injury is a crucial objective in the open reduction and internal fixation of these injuries. To achieve this objective, a single screw is used. The present practice is to insert the screw directed from the medial cuneiform bone into the base of the second metatarsal. This technique trick describes an easier method of insertion of the screw and one that possibly provides a better fixation. PMID:22549028

Panchbhavi, Vinod K

2012-11-01

185

EFFECT OF NITROGEN AND METAL ADDITIONS ON NITROGEN FIXATION ACTIVITY IN BIOLOGICAL SOIL CRUSTS  

NASA Astrophysics Data System (ADS)

Biological soil crusts (BSCs) are diverse consortia of microorganisms that live in intimate association with soils in arid environments. Also called cryptogamic or microbiotic crusts, these communities can include cyanobacteria, algae, heterotrophic bacteria, fungi, lichens, and mosses. Together, these organisms provide many services to their surrounding ecosystems, including reduction of water runoff, promotion of water infiltration, and prevention of soil erosion. The cyanobacteria and algae also provide fixed carbon (C) to the soil through photosynthesis, and because atmospheric deposition of nitrogen (N) in arid environments is low, the major input of biologically available N comes from cyanobacteria capable of converting nitrogen gas (N2) to ammonium (NH4+). Biological soil crusts are easily destroyed by livestock grazing, motor vehicle travel, and many forms of recreational and agricultural land use. Loss of BSC cover can leave the soil vulnerable to intense erosion that can remove the nutrients necessary to sustain plant and animal life, thus accelerating the process of desertification. In order to preserve existing crusts and encourage the development of new crusts, it is crucial to understand the nutrient requirements of metabolism and growth in these microbial communities. This study investigated the affect of nitrogen and metal additions on N2-fixation activity in cyanobacterially-dominated crusts from the Colorado Plateau near Moab, Utah. Although N2-fixation has been studied in this system before, the affect of nutrient additions on N2-fixation activity has not been documented. The goal of this work was to understand how N and metal supplementation affects crust N metabolism. Three experiments were conducted to observe how N2-fixation activity changed with the addition of N, molybdenum (Mo), and vanadium (V). Molybdenum and vanadium were chosen because they are most commonly found at the active site of the enzyme nitrogenase, the molecule responsible for the biological conversion of N2 to NH4+. The Mo-dependent version of the enzyme is the most efficient, and it is used by the majority of N2-fixing organisms. Elements were added as aqueous solutions of NH4NO3, Na2MoO4, and Na3VO4 respectively. Nitrogen fixation potential was assayed using a modified acetylene reduction technique. Results from the N-addition experiment show that when N is provided, BSC organisms stop N2-fixation activity. This confirms that under natural conditions, the community is limited with respect to N. In general, crusts under Mo-addition fix at higher rates than crusts with no added Mo. This implies that crusts may also be limited with respect to Mo. However, contrary to our expectations, crusts fix at lower rates when V is added as compared to a no-V control. It is possible that this is the result of V-toxicity, or that V competes with the uptake and utilization of available Mo, thus exacerbating Mo-limitation. Experiments are currently underway to investigate how the geochemistry of the soil porewater changes as a result of these nutrient additions.

Alexander, K.; Lui, D.; Anbar, A. D.; Garcia-Pichel, F.; Hartnett, H. E.

2009-12-01

186

The effect of transpedicular screw misplacement on late spinal stability  

Microsoft Academic Search

Summary ¶ Background. In this article the authors investigated the consequences of misplaced thoracolumbar pedicle screws on late spinal stability. Method. This study consisted of 16 patients with screws in the proper position (Group A) and a further 16 patients with screw misplacement (Group B) who had previously undergone transpedicular screw fixation following thoracolumbar injury. The authors retrospectively evaluated the

S. C. Aç?kba?; F. Y. Arslan; M. R. Tuncer

2003-01-01

187

Kinetic analysis of anterior cervical discectomy and fusion supplemented with transarticular facet screws.  

PubMed

OBJECT The clinical success rates of anterior cervical discectomy and fusion (ACDF) procedures are substantially reduced as more cervical levels are included in the fusion procedure. One method that has been proposed as an adjunctive technique for multilevel ACDF is the placement of screws across the facet joints ("transfacet screws"). However, the biomechanical stability imparted by transfacet screw placement (either unilaterally or bilaterally) has not been reported. Therefore, the purpose of this study was to determine the acute stability conferred by implementation of unilateral and bilateral transfacet screws to an ACDF construct. METHODS Eight C2-T1 fresh-frozen human cadaveric spines (3 female and 5 male; mean age 50 years) were tested. Three different instrumentation variants were performed on cadaveric cervical spines across C4-7: 1) ACDF with an intervertebral spacer and standard plate/screw instrumentation; 2) ACDF with an intervertebral spacer and standard plate/screw instrumentation with unilateral facet screw placement; and 3) ACDF with an intervertebral spacer and standard plate/screw instrumentation with bilateral facet screw placement. Kinetic ranges of motion in flexion-extension, lateral bending, and axial rotation at 1.5 Nm were captured after each of these procedures and were statistically analyzed for significance. RESULTS All 3 fixation scenarios produced statistically significant reductions (p < 0.05) in all 3 bending planes compared with the intact condition. The addition of a unilateral facet screw to the ACDF construct produced significant reductions at the C4-5 and C6-7 levels in lateral bending and axial rotation but not in flexion-extension motion. Bilateral facet screw fixation did not produce any statistically significant decreases in flexion-extension motion compared with unilateral facet screw fixation. However, in lateral bending, significant reductions at the C4-5 and C5-6 levels were observed with the addition of a second facet screw. The untreated, adjacent levels (C2-3, C3-4, and C7-1) did not demonstrate significant differences in range of motion. CONCLUSIONS The data demonstrated that adjunctive unilateral facet screw fixation to an ACDF construct provides significant gains in stability and should be considered a potential option for increasing the likelihood for obtaining a successful arthrodesis for multilevel ACDF procedures. PMID:24559463

Traynelis, Vincent C; Sherman, Jonathan; Nottmeier, Eric; Singh, Vaneet; McGilvray, Kirk; Puttlitz, Christian M; Leahy, Patrick Devin

2014-05-01

188

Direct repair of defects in lumbar spondylolysis with a new pedicle screw hook fixation: clinical, functional and Ct-assessed study  

PubMed Central

Spondylolysis is a common entity, a minority of people affected by this disease need medical care, and only a few require surgery. Reconstruction of the pars interarticularis is an interesting alternative to segmental fusion; this technique has the advantage of preserving segmental motion. Most authors report good results for young patients without intervertebral disk or facet degenerative changes. Moreover Louis also showed good to excellent results with his technique carried out among people who presented a satisfactory disk height (equal to two thirds of normal height). This could extend the number of patients for whom pars interarticularis repair could be proposed. In this study, the limit of reconstruction was set at grade 3of the Pfirrmann’s classification. The fixation of the isthmus was done with a new kind of pedicle screw hook system. This stable and strong device is easy to use, allows an anatomic pars interarticularis reconstruction of spondylolysis and avoids a postoperative bracing. Twenty-three patients were assessed in this study, the mean age at operation was 34 (range 16–52 years) and the average follow-up was for 59 months (range 6–113 months). Eight patients showed moderate degenerative disk disease before the surgery and 12 patients had a grade 1 spondylolisthesis. The visual analogical scale, the Oswestry disability index (ODI) and the modified Prolo score were used for assessment of pain and clinical outcome before and after surgery. The results were from “excellent” to “good” for twenty patients (87%) and “fair” for three of them (13%). The consolidation of the isthmus was assessed at the end of the study (CT-scan); the fusion rate was observed in 91%. Among patients aged less than 30 years results are from “good”, to “excellent” in all cases and consolidation was always observed. All of them showed normal disc signal before the surgery. In the group aged more than 30 years, the results varied from “good” to “excellent’ in 73% and fusion of the defect was discovered in 82% of cases. Eight of them (73%) had moderate disk signal modification before the surgery. All people with fair results displayed moderate disk degeneration signs at MRI before surgery; but two of those three patients had a failure of defect consolidation too and it is also associated with poor results by several authors. No complication was found in this series. According to the good results reported by Louis and upto the current finding, the authors believe that pars interarticularis repair can be carried out on patients with moderate degenerative disk disease; the stage 3 of Pfirrmann’s classification seems a good limit. The Bone and joint research (B.J.R. system) is readily usable by any surgeon using pedicle screw systems and having a short learning curve. No device failure has been observed in this series.

Troussel, Serge

2007-01-01

189

Scarf osteotomy without screw fixation  

Microsoft Academic Search

The scarf osteotomy is now well recognised as reliable and effective to contribute to the correction of the majority of hallux\\u000a valgus. The challenge remains for the correction of severe deformities with metatarsus varus angle >18? and Distal Metatarsal\\u000a Articular Angle (DMAA) >15?. In order to significantly improve in 3D the metatarsal head displacements, our scarf design became more oblique,

M. Maestro

2007-01-01

190

Modified trajectory of c2 laminar screw - double bicortical purchase of the inferiorly crossing screw.  

PubMed

The crossing laminar screw fixation might be the most recently developed approach among various fixation techniques for C2. The new construct has stability comparable to transarticular or transpedicular screw fixation without risk of vertebral artery injury. Quantitative anatomical studies about C2 vertebra suggest significant variation in the thickness of C2 lamina as well as cross sectional area of junction of lamina and spinous process. We present an elderly patient who underwent an occipito-cervical stabilization incorporating crossed C2 laminar screw fixation. We preoperatively recognized that she had low profiles of C2 lamina, and thus made a modification of trajectory for the inferiorly crossing screw. We introduce a simple modification of crossing C2 laminar screw technique to improve stability in patients with low laminar profiles. PMID:19096618

Rhee, Woo-Tack; You, Seung-Hoon; Jang, Yeon-Gyu; Lee, Sang-Youl

2008-02-01

191

Orthopedic prosthesis fixation.  

PubMed

The fixation of orthopedic implants has been one of the most difficult and challenging problems. The fixation can be achieved via: (a) direct mechanical fixation using screws, pins, wires, etc.; (b) passive or interference mechanical fixation where the implants are allowed to move or merely positioned onto the tissue surfaces; (c) bone cement fixation which is actually a grouting material; (d) biological fixation by allowing tissues to grow into the interstices of pores or textured surfaces of implants; (e) direct chemical bonding between implant and tissues; or (f) any combination of the above techniques. This article is concerned with various fixation techniques including the potential use of electrical, pulsed electromagnetic field, chemical stimulation using calcium phosphates for the enhancement of tissue ingrowth, direct bonding with bone by glass-ceramics and resorbable particle impregnated bone cement to take advantages of both the immediate fixation offered by the bone cement and long term fixation due to tissue ingrowth. PMID:1449228

Park, J B

1992-01-01

192

Anatomic considerations of costotransverse screw placement in the thoracic spine  

Microsoft Academic Search

BACKGROUNDNumerous techniques have been reported to restore spinal stability and to correct spinal deformities, including rods with wires\\/hooks, and rods or plates with pedicular screws. It was thought that posterior fixation of the thoracic spine through the costotransverse joint may be another alternative.METHODSNine cadavers were obtained for study of screw fixation of the costotransverse joint for posterior thoracic instrumentation. The

Rongming Xu; Nabil A Ebraheim; Yiangjia Ou; Martin Skie; Richard A Yeasting

2000-01-01

193

Minimally Invasive Posterior Trans-muscular C1-C2 Screw Fixation Through an Anatomical Corridor to Preserve Occipitocervical Tension Band: Surgical Anatomy and Clinical Experience.  

PubMed

The C1-C2 joint is affected by multiple entities that may produce biomechanical instability. Optimal management for atlantoaxial instability has been searched by ways of different surgical techniques with different results, generating discussion between second effects of a particular treatment. Lateral dissections can place the axial neck musculature and ligaments at risk of neural denervations or vascular compromise. Either of these entities may result in significant postoperative atrophy, pain, and instability. Minimally invasive techniques for the treatment of spinal disorders allow to our patients less morbid procedures with equal or better results compared to conventional surgery. In the following paper, we review the anatomy of the atlantoaxial joint and propose a minimally invasive trans-muscular C1-C2 fusion technique using C1 lateral-mass screws and C2 pedicular screws. We describe cases with surgical, clinical, and radiographic follow-up. PMID:24265049

Díaz, Roberto; Berbeo, Miguel E; Villalobos, Luis M; Vergara, Manuel F; Osorio, Enrique

2014-01-01

194

Torsional moment to failure for carbon fibre polysulphone expandable rivets as compared with stainless steel screws for carbon fibre-reinforced epoxy fracture plate fixation.  

PubMed

A method of securing carbon fibre-reinforced epoxy bone plates with carbon fibre polysulphone expanding rivets was investigated. Six carbon fibre-reinforced epoxy bone plates were secured to rods with carbon fibre polysulphone rivets and six were secured with standard cortical stainless steel screws. These constructions were then subjected to pure torsional load to failure. The carbon fibre expandable rivets failed at a greater torsional moment. PMID:2720038

Sell, P J; Prakash, R; Hastings, G W

1989-04-01

195

A Case of Pedicle Screw Loosening Treated by Modified Transpedicular Screw Augmentation with Polymethylmethacrylate  

PubMed Central

We report a case of pedicle screw loosening treated by modified transpedicular screw augmentation technique using polymethylmethacrylate (PMMA), which used the anchoring effect of hardened PMMA. A 56-year-old man who had an L3/4/5 fusion operation 3 years ago complained of continuous low back pain after this operation. The computerized tomography showed a radiolucent halo around the pedicle screw at L5. We augmented the L5 pedicle screw with modified pedicle screw augmentation technique using PMMA and performed an L3/4/5 pedicle screw fixation without hook or operation field extension. This modified technique is a kind of transpedicular stiffness augmentation using PMMA for the dead space around the loosed screw. After filling the dead space with 1-2 cc of PMMA, we inserted a small screw. Once the PMMA hardened, we removed the small screw and inserted a thicker screw along the existing screw threading to improve the pedicle screws' pullout strength. At 10 months' follow-up, x-ray showed strong fusion of L3/4/5. The visual analogue scale (VAS) of his back pain was improved from 9 to 5. This modified transpedicular screw augmentation with PMMA using anchoring effect is a simple and effective surgical technique for pedicle screw loosening. However, clinical analyses of long-term follow-up and biomechanical studies are needed.

Kang, Suk-Hyung; Kim, Kyoung-Tae; Park, Seung Won

2011-01-01

196

Management of a rare complication after screw fixation of a pediatric tibial spine avulsion fracture: a case report with follow-up to skeletal maturity.  

PubMed

Avulsion of the tibial spine is functionally equivalent to rupture of the anterior cruciate ligament in an adolescent athlete. It therefore presents to general orthopaedists as well as a wide variety of orthopaedic subspecialty surgeons, including traumatology sports medicine, and pediatrics. Restoration of normal knee kinematics is dependent on anatomic reduction and fixation of the avulsed fragment. Because this injury is typically sustained by the skeletally immature patient, epiphyseal fixation is ideal to avoid physeal injury, which can lead to angular limb deformity. We present a case, the first report to our knowledge, of coronal plane deformity in a lower extremity after open reduction and internal fixation of a tibial spine avulsion fracture. A successful treatment plan using hemiepiphysiodesis and guided growth is used with 20-month follow-up to skeletal maturity. PMID:21804418

Fabricant, Peter D; Osbahr, Daryl C; Green, Daniel W

2011-12-01

197

Clinical application of C2 laminar screw technique  

Microsoft Academic Search

C2 laminar screws have become an increasingly used alternative method to C2 pedicle screw fixation. However, the outcome of\\u000a this technique has not been thoroughly investigated. A total of 35 cases with upper cervical spinal instability undergoing\\u000a C2 laminar screw fixation were reviewed. All cases had symptoms of atlantoaxial instability, such as craniocervical junction\\u000a pain, and were fixed with the

Weihu Ma; Leling Feng; Rongming Xu; Xiaochen Liu; Alan H. Lee; Shaohua Sun; Liujun Zhao; Yong Hu; Guanyi Liu

2010-01-01

198

Evaluation of calcium sulfate paste for augmentation of lumbar pedicle screw pullout strength  

Microsoft Academic Search

Background context: Many authors have evaluated the components responsible for ultimate pullout strength of pedicle screws. In these studies, one important variable has been the screw fixation. Because pedicle screw fixation has increased in popularity over recent years, so has the need for augmentation in difficult situations. Polymethylmethacrylate (PMMA) has been established as the gold standard in terms of strength

Michael T Rohmiller; Dugan Schwalm; R. Chris Glattes; Tarek G Elalayli; Dan M Spengler

2002-01-01

199

Polymethylmethacrylate-Augmented Screw Fixation for Stabilization of the Osteoporotic Spine : A Three-Year Follow-Up of 37 Patients  

PubMed Central

Objective The purpose of this study was to determine the efficacy, radiological findings, clinical outcomes and complications in patients with lumbar stenosis and osteoporosis after the use of polymethylmethacrylate (PMMA) augmentation of a cannulated pedicle screw. Methods Thirty-seven patients with degenerative spinal stenosis and osteoporosis (T-score < -2.5) underwent lumbar fusion using the Dream Technology Pedicle Screw (DTPS™, Dream Spine Total Solutions, Dream STS, Seoul, Korea) between 2005 and 2007. The clinical outcomes were evaluated by using the visual analog scale (VAS) and the Prolo scale. Radiologic findings were documented through computed tomography (CT) and plain films. Results Thirty-seven patients were evaluated and included, 2 males and 35 females with an average bone mineral density (BMD) of 0.47g/cm2. The average age of the patients was 68.7 (range, 57-88). The preoperative VAS for low back and leg pain (7.87 ± 0.95 and 8.82 ± 0.83) were higher as compared with postoperative VAS (2.30 ± 1.61 and 1.42 ± 0.73) with statistical significance (p = 0.006, p = 0.003). According to the Prolo scale, 11, 22, one and three patients were in excellent, good, fair and poor conditions, respectively. The average amount of the injected cement per one cannulated screw was 1.83 ± 0.11 mL. Conclusion The results show favorable outcome both clinically and radiographically for 37 patients who underwent lumbar fusion using DTPS™ and PMMA. Based on the results, the use of this surgical method can be a safe and effective option for the operation on the osteoporotic spine.

Moon, Bong Ju; Choi, Eun Young; Zhang, Ho Yeol

2009-01-01

200

The Use of MMF Screws: Surgical Technique, Indications, Contraindications, and Common Problems in Review of the Literature  

PubMed Central

Mandibulo-maxillary fixation (MMF) screws are inserted into the bony base of both jaws in the process of fracture realignment and immobilisation. The screw heads act as anchor points to fasten wire loops or rubber bands connecting the mandible to the maxilla. Traditional interdental chain-linked wiring or arch bar techniques provide the anchorage by attached cleats, hooks, or eyelets. In comparison to these tooth-borne appliances MMF screws facilitate and shorten the way to achieve intermaxillary fixation considerably. In addition, MMF screws help to reduce the hazards of glove perforation and wire stick injuries. On the downside, MMF screws are attributed with the risk of tooth root damage and a lack of versatility beyond the pure maintenance of occlusion such as stabilizing loose teeth or splinting fragments of the alveolar process. The surgical technique of MMF screws as well as the pros and cons of the clinical application are reviewed. The adequate screw placement to prevent serious tooth root injuries is still an issue to rethink and modify conceptual guidelines.

Cornelius, Carl-Peter; Ehrenfeld, Michael

2010-01-01

201

Are plasticity models required to predict relative risk of lag screw cut-out in finite element models of trochanteric fracture fixation?  

PubMed

Using a finite element model of unstable trochanteric fracture stabilized with a sliding hip screw, the benefits of two plasticity-based formulations, Drucker-Prager and crushable foam, were evaluated and compared to the commonly used linear elastic model of trabecular bone in order to predict the relative risk of lag screw cut-out for five distinct load cases. The crushable foam plasticity formulation leads to a much greater strain localization, in comparison to the other two models, with large plastic strains in a localized region. The plastic zone predicted with Drucker-Prager is relatively more diffuse. Linear elasticity associated with a minimum principal strain criterion provides the smallest volume of elements susceptible to yielding for all loading modes. The region likely to undergo plastic deformation, as predicted by the linear elastic model, is similar to that obtained from plasticity-based formulations, which indicates that this simple criterion provides an adequate estimate of the risk of cut-out. PMID:24182773

Goffin, Jérôme M; Pankaj, Pankaj; Simpson, A Hamish

2014-01-01

202

Lapidus bunionectomy: Early evaluation of crossed lag screws versus locking plate with plantar lag screw.  

PubMed

We compared outcomes of the Lapidus bunionectomy fixated with crossed lag screws versus a locking plate with a plantar lag screw. Forty patients who underwent Lapidus bunionectomy between August 2001 and May 2006 were evaluated in a combined retrospective and prospective fashion. Crossed lag screws were used in 19 of the patients, and a locking plate with a plantar lag screw was used in 21 of the patients. Other than fixation, the only interventional difference pertained to postoperative weight bearing, where those receiving the plate initiated full weight bearing on the operated foot at 4 weeks postoperative, as compared to 6 weeks for those receiving crossed screws. Overall, the mean preoperative AOFAS hallux score was 41.75 +/- 2.52, and the postoperative score was 90.48 +/- 8.41 (P < .0001). The overall mean preoperative first intermetatarsal angle was 15.3 degrees +/- 2.32 degrees , and long term the angle was 5.03 degrees +/- 2.86 degrees (P < .0001). When comparisons were made based on the method of fixation, use of an adjunct Akin osteotomy and surgery performed before 2003 were statistically significantly associated with crossed screw fixation, and the preoperative AOFAS score was statistically significantly higher in the locking plate fixation group. There were no statistically significant differences related to postoperative complications between the 2 fixation groups. In conclusion, the Lapidus bunionectomy fixated with a locking plate and a plantar lag screw allows earlier weight bearing in comparison with crossed lag screws, without a difference in complications. Level of Clinical Evidence: 2. PMID:19232969

Saxena, Amol; Nguyen, Aidan; Nelsen, Elise

2009-01-01

203

Interference screw failure in distal biceps endobutton repair: case report.  

PubMed

Endobutton (Arthrex, Naples, FL) fixation of distal biceps rupture with interference screw fixation provides for a secure repair, allowing for early motion. We present a case in which Endobutton fixation failed with a loose interference screw, rendering the distal biceps attachment incompetent. Revision surgery with an extensile approach, mobilization of the biceps, and repeat Endobutton fixation at a more distal site provided a secure fixation with an excellent clinical outcome. An understanding of the mechanism of failure might allow surgeons to perform this procedure with a lower incidence of complications. PMID:20807629

Naidu, Sanjiv H

2010-09-01

204

Morphometric evaluation of subaxial cervical spine using multi-detector computerized tomography (MD-CT) scan: the consideration for cervical pedicle screws fixation  

PubMed Central

Background Cervical pedicle screw (CPS) insertion is a technically demanding procedure. The quantitative understanding of cervical pedicle morphology, especially the narrowest part of cervical pedicle or isthmus, would minimize the risk of catastrophic damage to surrounding neurovascular structures and improve surgical outcome. The aim of this study was to investigate morphology and quantify cortical thickness of the cervical isthmus by using Multi-detector Computerized Tomography (MD-CT) scan. Methods The cervical CT scans were performed in 74 patients (37 males and 37 females) with 1-mm slice thickness and then retro-reconstructed into sagittal and coronal planes to measure various cervical parameters as follows: outer pedicle width (OPW), inner pedicle width (IPW), outer pedicle height (OPH), inner pedicle height (IPH), pedicle cortical thickness, pedicle sagittal angle (PSA), and pedicle transverse angle (PTA). Results Total numbers of 740 pedicles were measured in this present study. The mean OPW and IPW significantly increased from C3 to C7 while the mean OPH and IPH of those showed non-significant difference between any measured levels. The medial-lateral cortical thickness was significantly smaller than the superior-inferior one. PTA in the upper cervical spine was significantly wider than the lower ones. The PSA changed from upward inclination at upper cervical spine to the downward inclination at lower cervical spine. Conclusions This study has demonstrated that cervical vertebra has relatively small and narrow inner pedicle canal with thick outer pedicle cortex and also shows a variable in pedicle width and inconsistent transverse angle. To enhance the safety of CPS insertion, the entry point and trajectories should be determined individually by using preoperative MD-CT scan and the inner pedicle width should be a key parameter to determine the screw dimensions.

2014-01-01

205

Axial and Angled Pullout Strength of Bone Screws in Normal and Osteoporotic Bone Material  

Microsoft Academic Search

Orthopedic surgery often involves the use of bone screws to stabilize fractures. Screw fixation can be extremely difficult\\u000a in osteoporotic (OP) bone because of its compromised strength. Pullout strength is commonly used to measure screw fixation\\u000a strength. In this study, axial and angled screw pullouts (ranging from 0° to 40°) were performed on 0.09 g.cm-3, 0.16 g.cm-3 and 0.32 g.cm-3

P. S. D. Patel; D. E. T. Shepherd; D. W. L. Hukins

206

Biomechanical evaluation of a new composite bioresorbable screw.  

PubMed

A new bioresorbable composite cannulated screw has been developed for small bone fracture fixation. The LG ("Little Grafter") screw is manufactured from Biosteon, which is a composite of poly L-lactic acid and hydroxyapatite. This study aimed to compare interfragmentary compression generated by this new screw with conventional metal screws commonly used in scaphoid fracture fixation. Four small metallic screws were compared with the LG screw, using a bone model produced from rigid polyurethane foam. The screws included the Acutrak, Asnis III, Herbert and Herbert-Whipple screws. The mean maximum compression forces for the LG screw, the Asnis and the Acutrak were comparable (LG 32.3 N, Asnis 32.8 N, Acutrak 38.3 N), whereas those using the Herbert and the Herbert-Whipple screw were significantly lower (Herbert 21.8 N, Herbert-Whipple 19.9 N). The bioresorbable LG screw has been shown to have good compressive properties compared to commonly used small bone fragment compression screws. PMID:16361004

Bailey, C A; Kuiper, J H; Kelly, C P

2006-04-01

207

A review of locking compression plate biomechanics and their advantages as internal fixators in fracture healing  

Microsoft Academic Search

Metallic implants are often involved in the open reduction and internal fixation of fractures. Open reduction and internal fixation is commonly used in cases of trauma when the bone cannot be healed using external methods such as casting. The locking compression plate combines the conventional screw hole, which uses non-locking screws, with a locking screw hole, which uses locking head

Danielle L. Miller; Tarun Goswami

2007-01-01

208

Biomechanical comparison of anterior cervical spine locked and unlocked plate-fixation systems  

Microsoft Academic Search

Three different anterior plate-fixation systems are available for the stabilisation of the cervical spine: (1) the cervical spine locking plate (CSLP), (2) dynamic plates allowing vertical migration of the fixation screws, and (3) various types of plates that are secured with either monocortical or bicortical unlocked screws. Unicortical screw purchase does not involve the risk of posterior cortex penetration and

Wolfgang Lehmann; Daniel Briem; Michael Blauth; Ulf Schmidt

2005-01-01

209

Circumferential management of unstable thoracolumbar fractures using an anterior expandable cage, as an alternative to an iliac crest graft, combined with a posterior screw fixation: results of a series of 85 patients.  

PubMed

Object The optimal management of unstable thoracolumbar fractures remains unclear. The objective of the present study was to evaluate the results of using an expandable prosthetic vertebral body cage (EPVBC) in the management of unstable thoracolumbar fractures. Methods Eighty-five patients with unstable T7-L4 thoracolumbar fractures underwent implantation of an EPVBC via an anterior approach combined with posterior fixation. Long-term functional outcomes, including visual analog scale and Oswestry disability index scores, were evaluated. Results In a mean follow-up period of 16 months, anterior fixation led to a significant increase in vertebral body height, with an average gain of 19%. However, the vertebral regional kyphosis angle was not significantly increased by anterior fixation alone. No significant difference was found between early postoperative, 3-month, and 1-year postoperative regional kyphosis angle and vertebral body height. Postoperative impaction of the prosthetic cage in adjacent endplates was observed in 35% of the cases, without worsening at last follow-up. Complete fusion was observed at 1 year postoperatively and no cases of infections or revisions were observed in relation to the anterior approach. Conclusions The use of EPVBCs for unstable thoracolumbar fractures is safe and effective in providing long-term vertebral body height restoration and kyphosis correction, with a moderate surgical and sepsis risk. Anterior cage implantation is an alternative to iliac bone graft fusion and is a viable option in association with a posterior approach, in a single operation without additional risks. PMID:24981898

Graillon, Thomas; Rakotozanany, Patrick; Blondel, Benjamin; Adetchessi, Tarek; Dufour, Henry; Fuentes, Stéphane

2014-07-01

210

Use of the cannulated bone screw in rearfoot surgery.  

PubMed

There are many types of rigid internal fixation devices available for podiatric surgery. The cannulated screw system is an easy and effective way to decrease surgical time. These screws are being used with great success for several rearfoot procedures, such as the triple arthrodesis, Dwyer calcaneal osteotomy, and posterior malleolar ankle fractures. PMID:2507621

Chieppa, W A; Sydnor, K H; Walter, J H

1989-01-01

211

Apparatus to test insertion and removal torque of bone screws.  

PubMed

This paper describes affordable equipment for testing bone screw torque, corresponding to ASTM standard F543-00 for testing metallic medical bone screws. Correct testing of thin and long bone screws is essential due to screw failures during insertion and removal of the screws. Furthermore, insertion torque is an important factor in predicting fixation strength, screw pull-out force and effects of surface treatment of screws. The capability of the custom-built tester was determined using polytetrafluoroethylene and wood disc samples and bone screws. Bovine cortical bones allowed testing to the failure limit, i.e. the torque increased in long screws to the fracture limit. For 2.7 and 3.5 mm thick self-tapping cortical bone screws, the failure torques were 30-50 per cent higher than the minimum values required by the standard (1.0 and 2.3 N m respectively). The equipment provided reproducible results and fulfilled the ASTM standard very well. Preliminary testing with amorphous diamond coated bone screws showed good durability of the coating and on average 10-15 per cent lower torque values compared with uncoated screws. The equipment can be used to measure insertion and removal torques as described in the standard. Furthermore, it also allows testing of normal screws and bolts. PMID:14702987

Koistinen, A; Santavirta, S; Lappalainen, R

2003-01-01

212

Systemic nickel allergy after internal fixation of a bunionectomy.  

PubMed

Allergic reactions to implanted metals have been estimated to occur in 1% to 5% of orthopedic cases. Stainless steel screws, which contain 14% nickel, are commonly used for internal fixation in an array of podiatric procedures. We present a rare case of a systemic allergic reaction to nickel secondary to stainless steel screw fixation in a bunionectomy procedure. PMID:24774988

Zhubrak, Michelle; Bar-David, Tzvi

2014-01-01

213

Understanding mechanisms and factors related to implant fixation; a model study of removal torque.  

PubMed

Osseointegration is a prerequisite for achieving a stable long-term fixation and load-bearing capacity of bone anchored implants. Removal torque measurements are often used experimentally to evaluate the fixation of osseointegrated screw-shaped implants. However, a detailed understanding of the way different factors influence the result of removal torque measurements is lacking. The present study aims to identify the main factors contributing to anchorage. Individual factors important for implant fixation were identified using a model system with an experimental design in which cylindrical or screw-shaped samples were embedded in thermosetting polymers, in order to eliminate biological variation. Within the limits of the present study, it is concluded that surface topography and the mechanical properties of the medium surrounding the implant affect the maximum removal torque. In addition to displaying effects individually, these factors demonstrate interplay between them. The rotational speed was found not to influence the removal torque measurements within the investigated range. PMID:24566379

Stenlund, Patrik; Murase, Kohei; Stålhandske, Christina; Lausmaa, Jukka; Palmquist, Anders

2014-06-01

214

Accuracy and complications of transpedicular C2 screw placement without the use of spinal navigation  

Microsoft Academic Search

The objective of the study was to describe the technique, accuracy of placement and complications of transpedicular C2 screw\\u000a fixation without spinal navigation. Patients treated by C2 pedicle screw fixations were identified from the surgical log book\\u000a of the department. Clinical data were extracted retrospectively from the patients’ charts. Pedicle screw placement accuracy\\u000a was assessed on postoperative CT scans according

Christian-Andreas Mueller; Lukas Roesseler; Martin Podlogar; Attlila Kovacs; Rudolf Andreas Kristof

2010-01-01

215

Comparison of Bioabsorbable Suture Anchor Fixation on the Tibial Side for Anterior Cruciate Ligament Reconstruction Using Free Soft Tissue Graft: Experimental Laboratory Study on Porcine Bone  

PubMed Central

Purpose The use of graft tissue fixation using bioabsorbable interference screws (BISs) in anterior cruciate ligament (ACL) reconstruction offers various advantages, but limited pullout strength. Therefore, additional tibial fixation is essential for aggressive rehabilitation. We hypothesized that additional graft tissue fixation using bioabsorbable suture anchors (BSA) would provide sufficient pull-out strength. Materials and Methods Twenty four fresh frozen porcine distal femur and patellar tendon preparations were used. All specimens were divided into three groups based on additional fixation methods: A, isolated BIS; B, BIS and BSA; and C, BIS and post cortical screw. Tensile testing was carried out under an axial load. Ultimate failure load and ultimate failure load after cyclic loading were recorded. Results The ultimate failure loads after load to failure testing were 166.8 N in group A, 536.4 N in group B, and 438 N in group C; meanwhile, the ultimate failure loads after load to failure testing with cyclic loading were 140 N in group A, 466.5 N in group B, and 400 N in group C. Stiffness after load to failure testing was 16.5 N/mm in group A, 33.5 N/mm in group B, and 40 N/mm in group C. An additional BSA fixation resulted in a significantly higher ultimate failure load and stiffness than isolated BIS fixation, similar to post screw fixation. Conclusion Additional fixation using a BSA provided sufficient pullout strength for ACL reconstruction. The ultimate failure load of the BSA technique was similar to that of post cortical screws.

Na, Suk In; Lee, Jong Min; Park, Ju Yong

2014-01-01

216

Bone registration method for robot assisted surgery: pedicle screw insertion  

Microsoft Academic Search

SUMMARY A registration method that identifies bone geometry with respect to a robotic manipulator arm is presented. Although the method is generally applicable to many orthopaedic internal fixation, it was only demonstrated for the insertion of pedicle screws in vertebral bodies for spine fixation. The method relies upon obtaining an impression of the vertebral bodies. Computed Tomography scans of both

K Abdel-Malek; D P McGowan; V K Goel; D Kowalski; A Hager

1997-01-01

217

[The value of miniature compression screws in maxillofacial surgery].  

PubMed

According to the well-known principle of compression, a new kind of screw has been developed. It is a development of the miniaturized Michelet-Champy osteosynthesis device which we have used for the last 10 years in maxillofacial surgery. These traction-screws were initially elaborated for rigid stabilization after sagittal ramus osteotomies such as Obwegeser-Dal Pont. Usually, three screws are inserted at each side, via a transjugal approach. It is then possible to remove the intermaxillary fixation device at the end of the surgical procedure. However, these screws are also useful in other cases: for other kinds of mandibular osteotomies (visor osteotomy for instance), in traumatology (oblique mandibular or condylar fractures) or for fixation of onlay bone grafts on the facial structures. When iliac bone grafts, which are essentially cancellous bone are used, it is possible to use a small metallic ring to avoid penetration of the head of the screw into the graft. The screws can be inserted by a cutaneous punctiform incision when it is impossible to pass the screwdriver through the buccal incision. In all cases, this material is particularly easy to insert, allows good fixation, permits a solid interosseous compression, and is particularly well tolerated. The main drawback is the difficulty of choosing the right length of the screws because only two lengths are available at the present time. Despite this problem, these mini traction-screws seem to be useful for maxillofacial surgeons. PMID:2470321

Boutault, F; Cadenat, H; Poirot, A; Bodin, H

1989-01-01

218

Biceps tenodesis with interference screw: cyclic testing of different techniques.  

PubMed

Different surgical techniques exist for biceps tenodesis. The most secure fixation technique is with interference screws. The purpose of the study was to compare the biomechanical performance of three different interference screw biceps tenodesis fixation methods, which involve different tunnel preparation methods. Using a sheep shoulder model and metal interference screws, a bone wedge technique was compared to serial tunnel dilation and a control group. After a preload, all repairs were cyclically loaded (20-60 N) for 100 cycles followed by destructive testing. Biceps tenodesis using an interference screw--bone wedge technique showed statistically lower cyclic displacement (8.1 ± 6.4 mm) than serial dilatation with an interference screw (21.3 ± 8.4 mm) or interference screw fixation alone (18.3 ± 8.3 mm) (P = 0.02). There were no statistically significant differences in ultimate failure strength for any of the interference screw biceps tenodesis techniques tested. The tunnel preparation method chosen for interference screw fixed biceps tenodesis can have a positive effect on tenodesis performance. Using the bone wedge technique may allow a more rapid rehabilitation program applicable for the traumatic biceps tendon rupture seen in young, athletic patients with high demands. PMID:20549186

Hapa, Onur; Günay, Cüneyd; Kömürcü, Erkam; Cak?c?, Hüsamettin; Bozda?, Ergun

2010-12-01

219

The effect of soft-tissue graft fixation in anterior cruciate ligament reconstruction on graft-tunnel motion under anterior tibial loading  

Microsoft Academic Search

Purpose: To compare the motion of an anterior cruciate ligament (ACL) replacement graft within the femoral bone tunnel (graft-tunnel motion) when a soft-tissue graft is secured either by a titanium button and polyester tape (EndoButton fixation; Acufex, Smith & Nephew, Mansfield, MA) or by a biodegradable interference screw (Biointerference fixation; Endo-fix; Acufex, Smith & Nephew) An additional purpose was to

Eiichi Tsuda; Yukihisa Fukuda; John C. Loh; Richard E. Debski; Freddie H. Fu; Savio L. Y. Woo

2002-01-01

220

Biomechanical and histological evaluation of an expandable pedicle screw in osteoporotic spine in sheep  

Microsoft Academic Search

Transpedicular fixation can be challenging in the osteoporotic spine as reduced bone mineral density compromises the mechanical\\u000a stability of the pedicle screw. Here, we sought to investigate the biomechanical and histological properties of stabilization\\u000a of expandable pedicle screw (EPS) in the osteoporotic spine in sheep. EPSs and standard pedicle screws, SINO screws, were\\u000a inserted on the vertebral bodies in four

Shiyong Wan; Wei Lei; Zixiang Wu; Da Liu; Mingxuan Gao; Suochao Fu

2010-01-01

221

Slippage between screwdriver and bone screw.  

PubMed

Cortical 3.5-mm stainless steel screws with hexagonal heads and corresponding screwdrivers from two manufacturers were investigated. Measurement of dimensions and torsional testing were done to study slippage between the screw and the driver bit. There were only small differences in dimensions between the manufacturers. Ultimate torque values obtained were at the level of 2.7 N-m where reaming of the screw socket took place. Additional rotation resulted in approximately (1/2) of the maximum torque. Subsequent torque testing in the opposite direction, corresponding to removal of the screw, revealed that the torque values were equally low in that direction. Additional insertion and removal of bone screws with hexagonal sockets are hampered after only one episode of slippage. It is justified to consider new shapes of drive bits and corresponding screw head sockets, such as a fluted multiedge configuration. PMID:12439282

Behring, Jon K; Gjerdet, Nils R; Mølster, Anders

2002-11-01

222

Surgical screw segmentation for mobile C-arm CT devices  

NASA Astrophysics Data System (ADS)

Calcaneal fractures are commonly treated by open reduction and internal fixation. An anatomical reconstruction of involved joints is mandatory to prevent cartilage damage and premature arthritis. In order to avoid intraarticular screw placements, the use of mobile C-arm CT devices is required. However, for analyzing the screw placement in detail, a time-consuming human-computer interaction is necessary to navigate through 3D images and therefore to view a single screw in detail. Established interaction procedures of repeatedly positioning and rotating sectional planes are inconvenient and impede the intraoperative assessment of the screw positioning. To simplify the interaction with 3D images, we propose an automatic screw segmentation that allows for an immediate selection of relevant sectional planes. Our algorithm consists of three major steps. At first, cylindrical characteristics are determined from local gradient structures with the help of RANSAC. In a second step, a DBScan clustering algorithm is applied to group similar cylinder characteristics. Each detected cluster represents a screw, whose determined location is then refined by a cylinder-to-image registration in a third step. Our evaluation with 309 screws in 50 images shows robust and precise results. The algorithm detected 98% (303) of the screws correctly. Thirteen clusters led to falsely identified screws. The mean distance error for the screw tip was 0.8 +/- 0.8 mm and for the screw head 1.2 +/- 1 mm. The mean orientation error was 1.4 +/- 1.2 degrees.

Görres, Joseph; Brehler, Michael; Franke, Jochen; Wolf, Ivo; Vetter, Sven Y.; Grützner, Paul A.; Meinzer, Hans-Peter; Nabers, Diana

2014-03-01

223

Nonunion after primary treatment of tibia fractures with external fixation  

Microsoft Academic Search

The authors retrospectively reviewed 207 fractures of tibial diaphysis, treated primarily with external fixation without bone grafting. Forty-two fractures (20.3%) resulted in nonunion and required reoperation. Parameters analyzed for their significance for nonunion included, soft tissue damage, energy of injury, method of fracture reduction, type of external fixation frame, supplemental interfragmentary screw fixation, dynamization at the fracture site, and postoperative

N. Papaioannou; D. Mastrokalos; P. J. Papagelopoulos; M. Tyllianakis; J. Athanassopoulos; P. A. Nikiforidis

2001-01-01

224

Technique for utilization of an interference screw for split peroneus brevis tendon transfer in lateral ankle stabilization.  

PubMed

We present a technique for split peroneous brevis lateral ankle stabilization using an interference screw as the fixation device. The interference screw provided stable fixation by way of physiologic tension and restored lateral ankle instability while preserving the range of motion in the surrounding joints. PMID:24239429

Didomenico, Lawrence A; Cross, Davina J; Giagnacova, Albert

2014-01-01

225

In vitro initial fixation of porous-coated acetabular total hip components. A biomechanical comparative study.  

PubMed

Two-phase in vitro testing was performed to determine the initial mechanical stability of uncemented but fixed porous coated acetabular components. Six each of three-screw fixation, two-peg fixation, and three-spike fixation porous acetabular components were implanted into fresh and embalmed human cadaver acetabula. Measurement of prosthesis-bone displacement at a load of 100 kg did not show a significant difference among the three methods of fixation. However, torque testing showed that three-screw fixation failed at significantly higher loads (46 N-m) than two-peg fixation (32 N-m) or three-spike fixation (32 N-m). PMID:2795026

Lachiewicz, P F; Suh, P B; Gilbert, J A

1989-09-01

226

Biodegradable magnesium-based screw clinically equivalent to titanium screw in hallux valgus surgery: short term results of the first prospective, randomized, controlled clinical pilot study  

PubMed Central

Purpose Nondegradable steel-and titanium-based implants are commonly used in orthopedic surgery. Although they provide maximal stability, they are also associated with interference on imaging modalities, may induce stress shielding, and additional explantation procedures may be necessary. Alternatively, degradable polymer implants are mechanically weaker and induce foreign body reactions. Degradable magnesium-based stents are currently being investigated in clinical trials for use in cardiovascular medicine. The magnesium alloy MgYREZr demonstrates good biocompatibility and osteoconductive properties. The aim of this prospective, randomized, clinical pilot trial was to determine if magnesium-based MgYREZr screws are equivalent to standard titanium screws for fixation during chevron osteotomy in patients with a mild hallux valgus. Methods Patients (n=26) were randomly assigned to undergo osteosynthesis using either titanium or degradable magnesium-based implants of the same design. The 6 month follow-up period included clinical, laboratory, and radiographic assessments. Results No significant differences were found in terms of the American Orthopaedic Foot and Ankle Society (AOFAS) score for hallux, visual analog scale for pain assessment, or range of motion (ROM) of the first metatarsophalangeal joint (MTPJ). No foreign body reactions, osteolysis, or systemic inflammatory reactions were detected. The groups were not significantly different in terms of radiographic or laboratory results. Conclusion The radiographic and clinical results of this prospective controlled study demonstrate that degradable magnesium-based screws are equivalent to titanium screws for the treatment of mild hallux valgus deformities.

2013-01-01

227

Factors affecting the pullout strength of cancellous bone screws.  

PubMed

Screws placed into cancellous bone in orthopedic surgical applications, such as fixation of fractures of the femoral neck or the lumbar spine, can be subjected to high loads. Screw pullout is a possibility, especially if low density osteoporotic bone is encountered. The overall goal of this study was to determine how screw thread geometry, tapping, and cannulation affect the holding power of screws in cancellous bone and determine whether current designs achieve maximum purchase strength. Twelve types of commercially available cannulated and noncannulated cancellous bone screws were tested for pullout strength in rigid unicellular polyurethane foams of apparent densities and shear strengths within the range reported for human cancellous bone. The experimentally derived pullout strength was compared to a predicted shear failure force of the internal threads formed in the polyurethane foam. Screws embedded in porous materials pullout by shearing the internal threads in the porous material. Experimental pullout force was highly correlated to the predicted shear failure force (slope = 1.05, R2 = 0.947) demonstrating that it is controlled by the major diameter of the screw, the length of engagement of the thread, the shear strength of the material into which the screw is embedded, and a thread shape factor (TSF) which accounts for screw thread depth and pitch. The average TSF for cannulated screws was 17 percent lower than that of noncannulated cancellous screws, and the pullout force was correspondingly less. Increasing the TSF, a result of decreasing thread pitch or increasing thread depth, increases screw purchase strength in porous materials. Tapping was found to reduce pullout force by an average of 8 percent compared with nontapped holes (p = 0.0001). Tapping in porous materials decreases screw pullout strength because the removal of material by the tap enlarges hole volume by an average of 27 percent, in effect decreasing the depth and shear area of the internal threads in the porous material. PMID:8872262

Chapman, J R; Harrington, R M; Lee, K M; Anderson, P A; Tencer, A F; Kowalski, D

1996-08-01

228

Treatment of upper cervical spine instability with posterior fusion plus atlantoaxial pedicle screw.  

PubMed

Clinical results of posterior fusion plus pedicle screw fixation in the treatment of upper cervical spine instability were taken under consideration. 24 patients with atlantoaxial instability were treated with C1-2 pedicle screws and rods fixation under general anesthesia. There were 18 males and 6 females with mean age of 49.8 years (age range 17-69 years). The postoperative radiographs verified good position of all screws, with satisfactory atlantoaxial reduction. Follow-up for 3-45 months (average 23 months) showed no spinal cord and vertebral artery injury or interfixation failure. Atlantoaxial alignment and stability were restored without complication due to instrumentation. In conclusion, posterior atlantoaxial pedicle screw and rod fixation provide immediate three-dimensional rigid fixation of atlantoaxial joint and are more effective techniques compared with previously reported techniques. PMID:24687596

Ma, Chao; Wu, Jibin; Zhao, Meng; Dai, Weixiang; Wu, Dehui; Wang, Zhaohong; Feng, Jie; Liu, Chao; Li, Yiming; Zhao, Qinghua; Tian, Jiwei

2014-07-01

229

The acetabular component in total hip arthroplasty. Evaluation of different fixation principles.  

PubMed

Initial stability is necessary for permanent fixation of acetabular cups. Biologic reactions to submicron particles such as localized bone resorption may lead to implant failure. The aim of the study was to evaluate different fixation principles of acetabular components. Four randomized studies and one case-control study were performed to evaluate different bone cements, different cup designs, use of ceramic coating or not, different type of screws and the need of additional screw fixation or not. Radiostereometry (RSA) makes it possible to analyze small translations and rotations of implants with a high accuracy. This method is suitable for evaluation of early stability and was used in four of the studies. Clinical and radiological follow-up were performed regularly. The cements were tested in the laboratory. 30 patients (mean age 71 years, range: 63-76) received total hip arthroplasties and were randomised to fixation with Boneloc (14) or Palacos cum gentamicin (16) bone cement. The curing temperature was 23 degrees lower for the Boneloc cement but the tensile strength was reduced and the elastic modulus was lower compared to Palacos. The proximal cup migration was greater in the Boneloc group up to 12 months (p 0.04) and these cups migrated medially in contrast to a small lateral migration seen in the Palacos group (p 0.04). Radiolucencies were more pronounced in the Boneloc group at 12 months (p 0.04). 155 patients (171 hips, mean age 50 years, range: 24-64) received uncemented hip arthroplasties. 84 hips were randomised to the PCA and 87 to the Harris-Galante I designs. The 10-year survival rates were 85% for the PCA and 99% for the Harris-Galante I cups (revision as end-point). The wear and clinical results did not differ. 43 patients (mean age 60 years, range 44-68) received uncemented porous cups with a titanium mesh in pure titanium (Harris-Galante II) and were randomised to additional fixation with either biodegradable screws (23, poly-L-lactic acid, PLLA) or screws made of titanium alloy (20). Increased proximal and medial-lateral translations (p 0.02, 0.04) but less rotation around the longitudinal axis (p 0.04) were seen in the PLLA group up to 2 years. There were also more pronounced radiolucencies anteriorly in this group at 2 years. The clinical results did not differ. 23 uncemented porous cups (Harris-Galante II) with hydroxyapatite-tricalciumphosphate coating (HA/TCP) were pair-wise matched to uncoated cups. Up to 2 years, decreased rotations around the horizontal axis were recorded in the HA/TCP-coated cups. Central postoperative gaps were more frequently seen in the HA/TCP group (p < 0.01), but at 2 years radiolucencies were more pronounced in the uncoated group (p < 0.01). The wear and clinical results did not differ. 62 patients (64 hips, mean age 56 years, range: 32-75) were randomized to porous Trilogy cups with (30) and without (34) cluster holes for additional screw fixation. Up to 2 years there were no differences in migration, wear, radiographic findings or clinical results. In conclusion Boneloc cement was associated with poor fixation due to inferior mechanical properties. The PLLA screws did not provide sufficient stability. Unacceptably high failure rates were recorded for the PCA cup. HA/TCP coating improved the fixation and the interface of porous cups. HA/TCP coated porous cups can be fixed without adjunctive screw fixation. PMID:10572504

Thanner, J

1999-08-01

230

The Pull-Out Strength of Transpedicular Screws in Posterior Spinal Fusion  

Microsoft Academic Search

Finite element methods are widely used for the analysis of the failure mechanisms of spinal fixation systems and the stress\\u000a distribution patterns within vertebral bodies as an important part in clinical evaluation of spinal injuries. For the purpose\\u000a of fixation and stabilization of the spine using pedicle screws the pull-out strength of the screw is one of the most important

P. Chazistergos; G. Ferentinos; E. A. Magnissalis; S. K. Kourkoulis

231

Use of Cortical Bone Screws in Maxillofacial Surgery - A Prospective Study  

PubMed Central

Background: The aim of this study is to evaluate the various applications of cortical bone screws in oral and maxillofacial surgery. Materials & Methods: The study was conducted in a teaching hospital located in, Bangalore, India, on 20 patients. These patients were categorized into three groups depending on the applications of these screws like, for achieving intermaxillary fixation in Group-1, for treatment of simple, undisplaced fractures by “Tension wire” method in Group-2, and further application of these screws were evaluated in Group-3. Different parameters were used to evaluate the efficacy of these screws. Results: In Group-1(n=12) there was satisfactory occlusion in all the patients with minimal incidence of complications. In Group-2 (n=4) post-operative reduction and fixation was satisfactory and in Group-3 (n=4) the function of these screws was satisfactory when it was used for vestibuloplasty and also as a suspension wiring in treatment of comminuted fracture of zygoma with minimal incidence of complications. Conclusion: Use of cortical bone screws is a valid alternative for achieving intermaxillary fixation, reduction and fixation of simple, undisplaced or minimally displaced fractures through Tension wire method owing to its simplicity, economy and ease of use, and as a fixation method for apically positioned flap in vestibuloplasty procedure. How to cite the article: Satish M, Rahman NM, Reddy VS, Yuvaraj A, Muliyar S, Razak PA. Use of Cortical Bone Screws in Maxillofacial Surgery - A Prospective Study. J Int Oral Health 2014;6(2):62-7.

Satish, Madatanapalli; Rahman, NM Mujeeb; Reddy, V Sridhar; Yuvaraj, A; Muliyar, Sabir; Razak, P Abdul

2014-01-01

232

Use of cortical bone screws in maxillofacial surgery - a prospective study.  

PubMed

Background: The aim of this study is to evaluate the various applications of cortical bone screws in oral and maxillofacial surgery. Materials & Methods: The study was conducted in a teaching hospital located in, Bangalore, India, on 20 patients. These patients were categorized into three groups depending on the applications of these screws like, for achieving intermaxillary fixation in Group-1, for treatment of simple, undisplaced fractures by "Tension wire" method in Group-2, and further application of these screws were evaluated in Group-3. Different parameters were used to evaluate the efficacy of these screws. Results: In Group-1(n=12) there was satisfactory occlusion in all the patients with minimal incidence of complications. In Group-2 (n=4) post-operative reduction and fixation was satisfactory and in Group-3 (n=4) the function of these screws was satisfactory when it was used for vestibuloplasty and also as a suspension wiring in treatment of comminuted fracture of zygoma with minimal incidence of complications. Conclusion: Use of cortical bone screws is a valid alternative for achieving intermaxillary fixation, reduction and fixation of simple, undisplaced or minimally displaced fractures through Tension wire method owing to its simplicity, economy and ease of use, and as a fixation method for apically positioned flap in vestibuloplasty procedure. How to cite the article: Satish M, Rahman NM, Reddy VS, Yuvaraj A, Muliyar S, Razak PA. Use of Cortical Bone Screws in Maxillofacial Surgery - A Prospective Study. J Int Oral Health 2014;6(2):62-7. PMID:24876704

Satish, Madatanapalli; Rahman, Nm Mujeeb; Reddy, V Sridhar; Yuvaraj, A; Muliyar, Sabir; Razak, P Abdul

2014-04-01

233

Effect of bone quality on the forces generated by compression screws  

Microsoft Academic Search

Internal fixation of the fractured scaphoid bone is used to promote union between bone fragments and to decrease wrist immobilization. Headless screws are commonly used because they minimize interference with articular surfaces and reduce tissue irritation and immobilization. In the present experiment, compressive force was measured as a function of bone quality for two headless screw types, the Herbert and

K. J Faran; N Ichioka; M. A Trzeciak; S Han; J Medige; O. J Moy

1999-01-01

234

C2 laminar screw and C1-2 transarticular screw combined with C1 laminar hooks for atlantoaxial instability with unilateral vertebral artery injury.  

PubMed

Transarticular screw fixation (TASF) is technically demanding, with high risk of vertebral artery (VA) injury. How to manage intraoperative VA injury and choose optimal alternative fixation becomes a concern of spinal surgeons. In this study, the management strategy for a patient with suspected intraoperative VA injury was analyzed. A 53-year-old woman developed type II odontoid fracture and brain stem injury due to a motor vehicle accident 3 months earlier. After conservative treatments, the brain stem injury improved, but with residual ocular motility defect in the right eye. The odontoid fracture did not achieve fusion with displacement and absorption of fracture fragments. After admission, atlantoaxial fixation using bilateral C1-2 transarticular screws (TASs) combined with C1 laminar hooks was planed. The first TAS was inserted successfully. Unfortunately, suspected VA injury developed during tapping the tract for the second TAS. Considering the previous brain stem injury and that directly inserting the screw to tamponade the hemorrhage might cause VA stenosis or occlusion, we blocked the screw trajectory with bone wax. C2 laminar screw was implanted instead of intended TAS on the injured side. The management strategy for suspected VA injury should depend on intraoperative circumstances and be tailored to patients. Blocking screw trajectory with bone wax is a useful method to stop bleeding. Atlantoaxial fixation using C2 laminar screw and C1-2 TAS combined with C1 laminar hooks is an ideal alternative procedure. PMID:21331546

Guo, Qunfeng; Liu, Jun; Ni, Bin; Lu, Xuhua; Zhou, Fengjin

2011-09-01

235

Screw-locking wrench  

NASA Technical Reports Server (NTRS)

A tool comprises a first handle and a second handle, each handle extending from a gripping end portion to a working end portion, the first handle having first screw threads disposed circumferentially about an inner portion of a first through-hole at the working end portion thereof, the second handle having second screw threads disposed circumferentially about an inner portion of a second through-hole at the working end portion thereof, the first and second respective through-holes being disposed concentrically about a common axis of the working end portions. First and second screw locks preferably are disposed concentrically with the first and second respective through-holes, the first screw lock having a plurality of locking/unlocking screw threads for engaging the first screw threads of the first handle, the second screw lock having a plurality of locking/unlocking screw threads for engaging the second screw threads of the second handle. A locking clutch drive, disposed concentrically with the first and second respective through-holes, engages the first screw lock and the second screw lock. The first handle and the second handle are selectively operable at their gripping end portions by a user using a single hand to activate the first and second screw locks to lock the locking clutch drive for either clockwise rotation about the common axis, or counter-clockwise rotation about the common axis, or to release the locking clutch drive so that the handles can be rotated together about the common axis either the clockwise or counter-clockwise direction without rotation of the locking clutch drive.

Vranish, John M. (Inventor)

2007-01-01

236

Split spline screw  

NASA Technical Reports Server (NTRS)

A split spline screw type payload fastener assembly, including three identical male and female type split spline sections, is discussed. The male spline sections are formed on the head of a male type spline driver. Each of the split male type spline sections has an outwardly projecting load baring segment including a convex upper surface which is adapted to engage a complementary concave surface of a female spline receptor in the form of a hollow bolt head. Additionally, the male spline section also includes a horizontal spline releasing segment and a spline tightening segment below each load bearing segment. The spline tightening segment consists of a vertical web of constant thickness. The web has at least one flat vertical wall surface which is designed to contact a generally flat vertically extending wall surface tab of the bolt head. Mutual interlocking and unlocking of the male and female splines results upon clockwise and counter clockwise turning of the driver element.

Vranish, John M. (inventor)

1993-01-01

237

In vitro study of accuracy of cervical pedicle screw insertion using an electronic conductivity device (ATPS part III)  

PubMed Central

Reconstruction of the highly unstable, anteriorly decompressed cervical spine poses biomechanical challenges to current stabilization strategies, including circumferential instrumented fusion, to prevent failure. To avoid secondary posterior surgery, particularly in the elderly population, while increasing primary construct rigidity of anterior-only reconstructions, the authors introduced the concept of anterior transpedicular screw (ATPS) fixation and plating. We demonstrated its morphological feasibility, its superior biomechanical pull-out characteristics compared with vertebral body screws and the accuracy of inserting ATPS using a manual fluoroscopically assisted technique. Although accuracy was high, showing non-critical breaches in the axial and sagittal plane in 78 and 96%, further research was indicated refining technique and increasing accuracy. In light of first clinical case series, the authors analyzed the impact of using an electronic conductivity device (ECD, PediGuard) on the accuracy of ATPS insertion. As there exist only experiences in thoracolumbar surgery the versatility of the ECD was also assessed for posterior cervical pedicle screw fixation (pCPS). 30 ATPS and 30 pCPS were inserted alternately into the C3–T1 vertebra of five fresh-frozen specimen. Fluoroscopic assistance was only used for the entry point selection, pedicle tract preparation was done using the ECD. Preoperative CT scans were assessed for sclerosis at the pedicle entrance or core, and vertebrae with dense pedicles were excluded. Pre- and postoperative reconstructed CT scans were analyzed for pedicle screw positions according to a previously established grading system. Statistical analysis revealed an astonishingly high accuracy for the ATPS group with no critical screw position (0%) in axial or sagittal plane. In the pCPS group, 88.9% of screws inserted showed non-critical screw position, while 11.1% showed critical pedicle perforations. The usage of an ECD for posterior and anterior pedicle screw tract preparation with the exclusion of dense cortical pedicles was shown to be a successful and clinically sound concept with high-accuracy rates for ATPS and pCPS. In concert with fluoroscopic guidance and pedicle axis views, application of an ECD and exclusion of dense cortical pedicles might increase comfort and safety with the clinical use of pCPS. In addition, we presented a reasonable laboratory setting for the clinical introduction of an ATPS-plate system.

Hitzl, Wolfgang; Acosta, Frank; Tauber, Mark; Zenner, Juliane; Resch, Herbert; Yukawa, Yasutsugu; Meier, Oliver; Schmidt, Rene; Mayer, Michael

2009-01-01

238

Investigation of a hybrid method of soft tissue graft fixation for anterior cruciate ligament reconstruction.  

PubMed

To increase knee stability following anterior cruciate ligament (ACL) reconstruction, development of increasingly stronger and stiffer fixation is required. This study assessed the initial pullout force, stiffness of fixation, and failure modes for a novel hybrid fixation method combining periosteal and direct fixation using porcine femoral bone. A soft tissue graft was secured by combining both an interference screw and an EndoButton (Smith and Nephew Endoscopy, Andover, MA). The results were compared with the traditional direct fixation method using a titanium interference screw. Twenty porcine hindlimbs were divided into two groups. Specimens were loaded in line with the bone tunnel on a materials testing machine. Maximum pullout force of the hybrid fixation (588+/-37 N) was significantly greater than with an interference screw alone (516+/-37 N). The stiffness of the hybrid fixation (52.1+/-12.8 N/mm) was similar to that of screw fixation (56.5+/-10.2 N/mm). Graft pullout was predominant for screw fixation, whereas a combination of graft pullout and graft failure was seen for hybrid fixation. These results indicate that initial pullout force of soft tissue grafts can be increased by using the suggested novel hybrid fixation method. PMID:15749452

Au, Anthony G; Otto, David D; Raso, V James; Amirfazli, Alidad

2005-04-01

239

Dynesys fixation for lumbar spine degeneration  

Microsoft Academic Search

The dynamic fixation system Dynesys is utilized in the last 10 years for treatment of degenerative segmental disease of the\\u000a lumbar spine. Dynesys is a semi-rigid fixation system that allows minimal lengthening and shortening between two segmental\\u000a pedicle screws as opposed to a rigid metal bar. Thus, the system is regarded to maintain stability and near physiological\\u000a motion patterns of the

Matthias Bothmann; Erich Kast; Gerald Jens Boldt; Joachim Oberle

2008-01-01

240

Open pisiform fracture: excision or internal fixation?  

PubMed

A 53-year-old man presented with an open fracture of the pisiform after a fall on his left wrist. Treatment of the patient presented a dilemma between excision of the proximal fragment and internal fixation. The patient underwent internal fixation with a 2.5 cortical screw. At 6 months follow-up the fracture appeared fully consolidated with full functional recovery of the wrist. PMID:23307459

Agathangelidis, Filon; Boutsiadis, Achilleas; Ditsios, Konstantinos

2013-01-01

241

Medial patellofemoral ligament reconstruction: a new technique for graft fixation at the patella without implants.  

PubMed

Patellofemoral instability is a complex disorder that is often accompanied by insufficiency or tearing of the medial patellofemoral ligament. Over the past few years, several techniques using free tendon grafts for medial patellofemoral ligament reconstruction have become popular because of their reproducible effect and good outcome. Whereas most surgeons prefer femoral fixation of the graft using an interference screw, the possibilities of patellar fixation are numerous. All of the different techniques have their own advantages and pitfalls. We describe a technique in which we drill 2 blind-ending tunnels (1 cm) at the medial aspect of the patella, where the doubled graft (not the free ends) is pulled in and fixed. By using a special technique for shuttling the sutures, there is no need for an additional skin incision and no need for implants, allowing very secure graft fixation without a relevant risk of fracture. PMID:24749029

Shafizadeh, Sven; Balke, Maurice

2014-02-01

242

Medial Patellofemoral Ligament Reconstruction: A New Technique for Graft Fixation at the Patella Without Implants  

PubMed Central

Patellofemoral instability is a complex disorder that is often accompanied by insufficiency or tearing of the medial patellofemoral ligament. Over the past few years, several techniques using free tendon grafts for medial patellofemoral ligament reconstruction have become popular because of their reproducible effect and good outcome. Whereas most surgeons prefer femoral fixation of the graft using an interference screw, the possibilities of patellar fixation are numerous. All of the different techniques have their own advantages and pitfalls. We describe a technique in which we drill 2 blind-ending tunnels (1 cm) at the medial aspect of the patella, where the doubled graft (not the free ends) is pulled in and fixed. By using a special technique for shuttling the sutures, there is no need for an additional skin incision and no need for implants, allowing very secure graft fixation without a relevant risk of fracture.

Shafizadeh, Sven; Balke, Maurice

2014-01-01

243

Spinous process fixation devices for instrumented spinal fusion.  

PubMed

Lumbar spinal fusion is a well-established surgical procedure for many spinal conditions. Posterior instrumentation may be added to provide immediate stabilization and improve fusion rates. Spinous process fixation, a type of posterior fixation, offers a less-invasive option to pedicle or facet screws with quantitative evidence of similar biomechanical stabilization; however, little has been published on the use of these devices. Further, there has been confusion about the use of spinous process fixation devices versus spinous process spacers. Spinous process fixation devices provide spine surgeons with another option for instrumented fusion, offering potential advantages for select patients. Biomechanical data suggest that relative to pedicle screws, modern spinous process fixation devices provide equivalent stability with reduced clinical risk and a less-invasive surgical procedure. These devices need to be distinguished from spacers, which are non-fixation devices. PMID:24081843

Hardenbrook, Mitchell; Henn, Jeffrey S; Oppenheim, Jeffrey; Shah, Mitesh V

2013-09-01

244

Dislocation of the proximal tibiofibular joint.A new method for fixation.  

PubMed

We introduce a new method for fixation of a rare, isolated, proximal tibiofibular dislocation. One third of the biceps femoris muscle tendon was used for fixation of the dislocated proximal fibular head. The fixation was achieved by using a soft threaded interference ACL screw. PMID:10447641

Miettinen, H; Kettunen, J; Väätäinen, U

1999-01-01

245

ORV Arthroscopic Reduction and Internal Fixation of Tibial Eminence Fractures  

PubMed Central

Tibial eminence fractures are an uncommon but well-described avulsion of the anterior cruciate ligament. Treatment principles are based on the amount and pattern of fracture displacement. Management has evolved from closed reduction and immobilization to arthroscopic reduction and internal fixation followed by early rehabilitation. Various fixation methods have evolved, ranging from arthroscopic reduction and percutaneous screw fixation to arthroscopic suture repair. We present a technique for arthroscopic reduction and internal fixation using a cannulated drill bit and high-strength suture. This technique facilitates anatomic reduction with uncomplicated tunnel placement and suture passing in an effort to allow strong fixation and early rehabilitation.

Myer, Daniel M.; Purnell, Gregory J.; Caldwell, Paul E.; Pearson, Sara E.

2013-01-01

246

Fixation updates for hallux valgus correction.  

PubMed

Fixation options for hallux valgus correction vary. Although some methods are newer and more advanced, even the older techniques are successful in appropriate situations. Kirschner wires and cerclage wiring have their place in proximal phalanx and first metatarsal osteotomies. They are useful for fusion procedures, depending on patient bone quality. Advancements with staple fixation allow the surgeon to apply compression with this device. One of the most stable forms of fixation is the bone screw. By providing a stable construct with good interfragmentary compression, primary bone healing is facilitated. The more recent use of rigid locking plates has allowed for earlier weight bearing following fusion procedures. PMID:24685192

Ben-Ad, Rotem

2014-04-01

247

'Screw'--appendicitis.  

PubMed

We report a rare case of appendicitis due to screw in the appendix in a 4-year old boy. An appendicectomy was done. Foreign body appendicitis should be treated with early surgical intervention. PMID:17827638

Samujh, Ram; Mansoor, Khizer; Khan, Imran; Mannan, A

2007-08-01

248

Survey of Screw Feeders.  

National Technical Information Service (NTIS)

This report presents the results of a survey to determine the availability of screw feeders for use in areas related to coal feeding in the field of coal conversion. 15 references. (ERA citation 09:037045)

G. Sine

1983-01-01

249

Effects of Elevated CO2 and N Addition on Growth and N2 Fixation of a Legume Subshrub (Caragana microphylla Lam.) in Temperate Grassland in China  

PubMed Central

It is well demonstrated that the responses of plants to elevated atmospheric CO2 concentration are species-specific and dependent on environmental conditions. We investigated the responses of a subshrub legume species, Caragana microphylla Lam., to elevated CO2 and nitrogen (N) addition using open-top chambers in a semiarid temperate grassland in northern China for three years. Measured variables include leaf photosynthetic rate, shoot biomass, root biomass, symbiotic nitrogenase activity, and leaf N content. Symbiotic nitrogenase activity was determined by the C2H2 reduction method. Elevated CO2 enhanced photosynthesis and shoot biomass by 83% and 25%, respectively, and the enhancement of shoot biomass was significant only at a high N concentration. In addition, the photosynthetic capacity of C. microphylla did not show down-regulation under elevated CO2. Elevated CO2 had no significant effect on root biomass, symbiotic nitrogenase activity and leaf N content. Under elevated CO2, N addition stimulated photosynthesis and shoot biomass. By contrast, N addition strongly inhibited symbiotic nitrogenase activity and slightly increased leaf N content of C. microphylla under both CO2 levels, and had no significant effect on root biomass. The effect of elevated CO2 and N addition on C. microphylla did not show interannual variation, except for the effect of N addition on leaf N content. These results indicate that shoot growth of C. microphylla is more sensitive to elevated CO2 than is root growth. The stimulation of shoot growth of C. microphylla under elevated CO2 or N addition is not associated with changes in N2-fixation. Additionally, elevated CO2 and N addition interacted to affect shoot growth of C. microphylla with a stimulatory effect occurring only under combination of these two factors.

Zhang, Lin; Wu, Dongxiu; Shi, Huiqiu; Zhang, Canjuan; Zhan, Xiaoyun; Zhou, Shuangxi

2011-01-01

250

Modern posterior screw techniques in the pediatric cervical spine  

PubMed Central

Treatment of children with cervical spine disorders requiring fusion is a challenging endeavor for a variety of reasons. The size of the patients, the corresponding abnormal bony anatomy, the inherent ligamentous laxity of children, and the relative rarity of the disorders all play a part in difficulty of treatment. The benefits of modern posterior cervical instrumentation in children, defined as rigid screw-rod systems, have been shown to be many including: improved arthrodesis rates, diminished times in halo-vest immobilization, and improved reduction of deformities. The anatomy of children and the corresponding pathology seen frequently is at the upper cervical spine and craniocervical junction given the relatively large head size of children and the horizontal facets at these regions predisposing them to instability or deformity. Posterior screw fixation, while challenging, allows for a rigid base to allow for fusion in these upper cervical areas which are predisposed to pseudarthrosis with non-rigid fixation. A thorough understanding of the anatomy of the cervical spine, the morphology of the cervical spine, and the available screw options is paramount for placing posterior cervical screws in children. The purpose of this review is to discuss both the anatomical and clinical descriptions related to posterior screw placement in the cervical spine in children.

Hedequist, Daniel J

2014-01-01

251

Modern posterior screw techniques in the pediatric cervical spine.  

PubMed

Treatment of children with cervical spine disorders requiring fusion is a challenging endeavor for a variety of reasons. The size of the patients, the corresponding abnormal bony anatomy, the inherent ligamentous laxity of children, and the relative rarity of the disorders all play a part in difficulty of treatment. The benefits of modern posterior cervical instrumentation in children, defined as rigid screw-rod systems, have been shown to be many including: improved arthrodesis rates, diminished times in halo-vest immobilization, and improved reduction of deformities. The anatomy of children and the corresponding pathology seen frequently is at the upper cervical spine and craniocervical junction given the relatively large head size of children and the horizontal facets at these regions predisposing them to instability or deformity. Posterior screw fixation, while challenging, allows for a rigid base to allow for fusion in these upper cervical areas which are predisposed to pseudarthrosis with non-rigid fixation. A thorough understanding of the anatomy of the cervical spine, the morphology of the cervical spine, and the available screw options is paramount for placing posterior cervical screws in children. The purpose of this review is to discuss both the anatomical and clinical descriptions related to posterior screw placement in the cervical spine in children. PMID:24829871

Hedequist, Daniel J

2014-04-18

252

Intraoperative three-dimensional fluoroscopy assessment of iliosacral screws and lumbopelvic implants stabilizing fractures of the os sacrum  

Microsoft Academic Search

Introduction  Percutaneous iliosacral screw fixation of unstable sacrum fractures has gained popularity since its introduction in the 1990s.\\u000a The combination with lumbopelvic implants allows the application even in situations of higher instability. Both manual and\\u000a navigated screw insertion in the sacrum and vertebra bodies shows unchanged relevant malpositions. The current standard to\\u000a control the screw position is postoperative computed tomography. The

Markus Beck; Markus Kröber; Thomas Mittlmeier

2010-01-01

253

Mechanical comparison of fixation techniques for the offset V osteotomy: a saw bone study.  

PubMed

Four different techniques for the fixation of an offset V bunionectomy were tested on solid-foam saw-bone models for the purpose of determining the strongest form of fixation for the osteotomy. Twenty identical models were placed into 4 different groups. Groups varied as to the placement and caliber of fixation. Models were loaded with a servo-hydraulic testing machine until failure of fixation occurred. Video analysis was used to record the pattern of failure of the fixation. Failure occurred either distal to the first screw, through the first screw hole, between the 2 screws, through the second screw hole, or proximal to the second screw. The mean force to failure of the groups was group 1, 58.1 N; group 2, 59.3 N; group 3, 64.0 N; and group 4, 105.66 N. There was a statistical significant difference between group 4 and the other 3 groups (F(1) = 55.45, P < 0.05). There was no statistical difference between groups 1 to 3. In groups 1 to 3, 87% of the failures were through the distal screw hole, whereas the remaining 13% were through the proximal screw hole. In group 4, 60% of the failures were through the proximal screw hole and 40% were through the distal screw hole. It was concluded that, in this model, the strongest form of fixation for an offset V osteotomy was the 2.7-mm cortical screw placed distally with the proximal point of fixation being a threaded 0.062-inch Kirschner wire. PMID:14688775

Jacobson, Keith; Gough, Adam; Mendicino, Samuel S; Rockett, Matthew S

2003-01-01

254

?????????????????????????? ?????????????????????????????????????????????????? ??????????? ????????????????????? ??????????????????????????????? Effect of Screw Rotating Speed on the Properties of Poly lactic acid(PLA)\\/Organoclay Nanocomposites Prepared by a Twin Screw Extruder  

Microsoft Academic Search

This study analyzes the effect of different screw rotating speeds on the properties of nanocomposites prepared by melt compounding PLA with an organoclay in a co-rotating twin-screw extruder. Polyamide 12 was used as an additive. Two different screw rotating speeds, 65 rpm and 150 rpm, were used in this study. According to the tensile strength data, the Young's modulus and

Aniwat Hasook; Hiroki Muramatsu; Shuichi Tanoue; Yoshiyuki Iemoto; Tsunemune Unryu

255

Experimental Results of Single Screw Mechanical Tests. A Follow-Up to SAND2005-6036.  

National Technical Information Service (NTIS)

The work reported here was conducted to address issues raised regarding mechanical testing of attachment screws described in SAND2005-6036, as well as to increase the understanding of screw behavior through additional testing. Efforts were made to evaluat...

J. S. Korellis K. L. Lee S. Lee X. McFadden

2006-01-01

256

Prediction of Deformity Correction by Pedicle Screw Instrumentation in Thoracolumbar Scoliosis Surgery  

NASA Astrophysics Data System (ADS)

In segmental pedicle screw instrumentation, the relationship between the combinations of pedicle screw placements and the degree of deformity correction was investigated with a three-dimensional rigid body and spring model. The virtual thoracolumbar scoliosis (Cobb’s angle of 47 deg.) was corrected using six different combinations of pedicle-screw placements. As a result, better correction in the axial rotation was obtained with the pedicle screws placed at or close to the apical vertebra than with the screws placed close to the end vertebrae, while the correction in the frontal plane was better with the screws close to the end vertebrae than with those close to the apical vertebra. Additionally, two screws placed in the convex side above and below the apical vertebra provided better correction than two screws placed in the concave side. Effective deformity corrections of scoliosis were obtained with the proper combinations of pedicle screw placements.

Kiriyama, Yoshimori; Yamazaki, Nobutoshi; Nagura, Takeo; Matsumoto, Morio; Chiba, Kazuhiro; Toyama, Yoshiaki

257

Influence of micro- and nano-hydroxyapatite coatings on the osteointegration of metallic (Ti6Al4 V) and bioabsorbable interference screws: an in vivo study.  

PubMed

The purpose of this study is to show and compare the fixation and osteointegration capability of metallic and bioabsorbable interference screws. For this, 8 × 20-mm interference screws were implanted into the bone tunnel in the proximal tibial metaphysis of sheep. The nano- (25 nm ± 0.8) and microscale (25 ?m ± 0.5) hydroxyapatite were both dip-coated on Ti6Al4 V interference screws via an in vivo study. After the initial 12 weeks of postoperative, the pullout test, histopathology, X-ray diffraction and scanning electron microscopy examinations were performed. This multidisiplined work showed that the coated screws particularly those with nano-sized-HA coating and the bioabsorbable screws enhanced fixation and provided better stabilization, bone ingrowth and osteointegration than that of uncoated and microscale HA-coated screws. The bioabsorbable screws showed better histopathologic results. PMID:23689912

Aksakal, B; Kom, M; Tosun, H B; Demirel, M

2014-07-01

258

Avaliação do posicionamento de parafusos pediculares na coluna torácica e lombar introduzidos com base em referenciais anatômicos e radioscópicos Placement analysis of thoracic and lumbar pedicle screws inserted under anatomic and radioscopic parameters  

Microsoft Academic Search

Objective: pedicular screw technique has becoming the standard choice for spinal fixation. The goal of the study is to evaluate thoracic and lumbar pedicle screws placement to treat a variety of spinal disorders. These screws were inserted using intraoperative anatomical and fluoroscopic parameters. Methods: the retrospective analysis included 24 patients (7 men and 17 women with a

Felipe Antonio De Marco; Marcelo Italo Risso-Neto; Paulo Tadeu; Maia Cavali; Marcelo Augusto Sussi; Wagner Pasqualini; Élcio Landim; Ivan Guidolin Veiga; Mauricio Antonelli Lehoczki; Augusto Celso; Amato Filho

259

Percutaneous pedicle screw placement in the thoracic spine: A cadaveric study  

PubMed Central

Study Design: A cadaveric study to determine the accuracy of percutaneous screw placement in the thoracic spine using standard fluoroscopic guidance. Summary of Background Data: While use of percutaneous pedicle screws in the lumbar spine has increased rapidly, its acceptance in the thoracic spine has been slower. As indications for pedicle screw fixation increase in the thoracic spine so will the need to perform accurate and safe placement of percutaneous screws with or without image navigation. To date, no study has determined the accuracy of percutaneous thoracic pedicle screw placement without use of stereotactic imaging guidance. Materials and Methods: Eighty-six thoracic pedicle screw placements were performed in four cadaveric thoracic spines from T1 to T12. At each level, Ferguson anterior–posterior fluoroscopy was used to localize the pedicle and define the entry point. Screw placement was attempted unless the borders of the pedicle could not be delineated solely using intraoperative fluoroscopic guidance. The cadavers were assessed using pre- and postprocedural computed tomography (CT) scans as well as dissected and visually inspected in order to determine the medial breach rate. Results: Ninety pedicles were attempted and 86 screws were placed. CT analysis of screw placement accuracy revealed that only one screw (1.2%) breached the medial aspect of the pedicle by more than 2 mm. A total of four screws (4.7%) were found to have breached medially by visual inspection (three Grade 1 and one Grade 2). One (1.2%) lateral breach was greater than 2 mm and no screw violated the neural foramen. The correlation coefficient of pedicle screw violations and pedicle diameter was found to be 0.96. Conclusions: This cadaveric study shows that percutaneous pedicle screw placement can be performed in the thoracic spine without a significant increase in the pedicle breach rate as compared with standard open techniques. A small percentage (4.4%) of pedicles, especially high in the thoracic spine, may not be safely visualized.

Hardin, Carolyn A.; Nimjee, Shahid M.; Karikari, Isaac O.; Agrawal, Abhishek; Fessler, Richard G.; Isaacs, Robert E.

2013-01-01

260

Ankle fusion stability: a biomechanical comparison of external versus internal fixation.  

PubMed

This biomechanical study compares bimalleolar external fixation to conventional crossed-screw construct in terms of stability and compression for ankle arthrodesis. The goals of the study were to determine which construct is more stable with bending and torsional forces, and to determine which construct achieves more compression.Fourth-generation bone composite tibia and talocalcaneal models were made to 50th percentile anatomic specifications. Fourteen ankle fusion constructs were created with bimalleolar external fixators and 14 with crossed-screw constructs. Ultimate bend, torque, and compression testing were completed on the external fixator and crossed-screw constructs using a multidirectional Materials Testing Machine (MTS Systems Corp, Eden Prairie, Minnesota). Ultimate bend testing revealed a statistically significant difference (P=.0022) with the mean peak load to failure for the external fixator constructs of 973.2 N compared to 612.5 N for the crossed-screw constructs. Ultimate torque testing revealed the mean peak torque to failure for the external fixator construct was 80.2 Nm and 28.1 Nm for the crossed-screw construct, also a statistically significant difference (P=.0001). The compression testing yielded no statistically significant difference (P=.9268) between the average failure force of the external fixator construct (81.6 kg) and the crossed-screw construct (81.2 kg).With increased stiffness in both bending and torsion and comparable compressive strengths, bimalleolar external fixation is an excellent option for tibiotalar ankle arthrodesis. PMID:21469636

Hoover, Justin R; Santrock, Robert D; James, William C

2011-04-01

261

Clinical applications of drill free screws in maxillofacial surgery.  

PubMed

Drill free screws are newly designed osteosynthesis screws with specially formed tips and cutting flutes, which act like a cork-screw and can be inserted into bone without predrilling. A prospective study on 82 patients was performed in order to investigate the efficiency of mini- and micro-drill free screws (DFS) in clinical use and to find out areas in maxillofacial traumatology and orthognathic surgery, where the application of this new type of screw may be recommended. Thirty-eight Le-Fort-osteotomies, 23 central and lateral midfacial fractures and 21 fractures of the mandible were fixed using the Champy titanium micro/miniplate system and in total 518 center-drive titanium micro-DFS (1.5 mm) and 392 center-drive titanium mini-DFS (2 mm) with lengths between 4 and 7 mm. The results showed that the grip of micro- and mini-DFS was sufficient for the fixation of bone fragments in the central and lateral midface and in the mandibular area. The insertion of DFS was simple and is recommended in the area of the central midface; the insertion of the screws was difficult, but possible in the anterior mandible and in the lateral midface. The application of DFS in the mandibular angle region is not recommended. PMID:10626259

Heidemann, W; Gerlach, K L

1999-08-01

262

Helical screw viscometer  

DOEpatents

A helical screw viscometer for the measurement of the viscosity of Newtonian and non-Newtonian fluids comprising an elongated cylindrical container closed by end caps defining a circular cylindrical cavity within the container, a cylindrical rotor member having a helical screw or ribbon flight carried by the outer periphery thereof rotatably carried within the cavity whereby the fluid to be measured is confined in the cavity filling the space between the rotor and the container wall. The rotor member is supported by axle members journaled in the end caps, one axle extending through one end cap and connectable to a drive source. A pair of longitudinally spaced ports are provided through the wall of the container in communication with the cavity and a differential pressure meter is connected between the ports for measuring the pressure drop caused by the rotation of the helical screw rotor acting on the confined fluid for computing viscosity.

Aubert, J.H.; Chapman, R.N.; Kraynik, A.M.

1983-06-30

263

Blocks and Screws  

NSDL National Science Digital Library

In this lesson, each student is given a block of wood and a screw (or nail), and is asked to put the screw into the block, without any tool (like a screwdriver or hammer). Their efforts, with varying success, lead to a discussion of contrivances, using various items and strategies as make-do (contrived) tools for which they were not intended, and an exploration of many examples of contrivances or adaptive compromises and other imperfections in the living world, especially in humans. This situation may be better explained by evolution rather than the result of intelligent design.

Patterson, Tim

264

Innovation: the induction heated screw.  

National Technical Information Service (NTIS)

The Research and Development Division at EDF has developed an original technique for heating, drying or baking powder products: the induction heated Archimedes screw. Its main characteristic is simultaneous heating of the screw and the sleeve. (author). 4...

B. Paya

1993-01-01

265

Suture-endobutton fixation of ankle tibio-fibular diastasis: a cadaver study.  

PubMed

Suture-Endobutton fixation is proposed as a minimally invasive, flexible fixation of ankle tibio-fibular diastasis, which would not require routine removal. This study tested the Suture-Endobutton construct in a cadaver syndesmosis injury model and compared this against A.O. syndesmosis screw fixation. Sixteen embalmed cadaver legs were used. Phase one consisted of placing the leg in a jig, generating an external rotation torque and measuring diastasis with increasing intraosseous membrane division. Phase two then compared the Suture-Endobutton construct vs. single four-cortex 4.5 mm A.O. screw fixation. Diastasis increased significantly with increasing intraosseous membrane division (p<0.001). No significant differences were seen in the mean rate of failure between the Suture-Endobutton and A.O. screw fixation. However, the Suture-Endobutton did give a significantly more consistent performance; the distribution of standard deviations for A.O. screw fixation was 0.64 mm higher than that for the Endobutton (95% C.I. 0.46 to 0.84). These results show that Suture-Endobutton fixation at least equals the performance of screw fixation and encourages clinical trials in ankle injuries with a syndesmosis diastasis. PMID:12627622

Thornes, Brian; Walsh, Alan; Hislop, Matt; Murray, Paraic; O'Brien, Moira

2003-02-01

266

Screw implantation in the globe: the risk of delayed hardware migration from craniofacial repair.  

PubMed

Plating system modification has enabled the use of rigid fixation in younger patients having maxillofacial surgery. One of the common reported complications of the use of plates and screws in children is screw migration due to skeletal maturation. Ophthalmic complications due to maxillofacial surgery reported to date include oculomotor and abducens palsies, lacrimal damage and vision loss due to infection, retrobulbar hemorrhage, and compartment syndrome. We describe a complication unique to screw migration resulting in orbital fixation and near-globe rupture in a patient with Treacher Collins syndrome. We hope to alert our colleagues to the potential risk of screw and hardware migration and breakage, particularly in the setting of craniofacial surgery performed on a child before maturation of craniofacial osseous structures. PMID:24036744

Sadiq, Mohammad Ali A; Prabhu, Sanjay P; Fearon, Jeffrey A; Taghinia, Amir H; Dagi, Linda R

2013-09-01

267

Augmentation of implant fixation in osteoporotic bone.  

PubMed

Osteoporosis presents a dilemma for the orthopedic surgeon. Screw fixation within the bone is crucial for mechanical stabilization, maintenance of reduction, and ultimately, fracture healing. For the patient, soft bones and physiological fragility usually benefit from immediate weight bearing and mobility to avoid further disuse osteoporosis, deconditioning, and immobility. For implant companies, traditional screws, plates, and nails function for simple fractures and compliant patients. Locked plating has improved screw purchase in osteoporotic bone and has expanded fracture fixation capabilities but is not the panacea for all fractures. For orthopedic surgeons, traditional surgical augmentation for osteoporosis consisting of dual plating, augmentation with polymethyl methacrylate, joint replacement, and now locked plating are beneficial. In order to advance orthopedic care in the expanding population of elderly osteoporotic patients, modern solutions utilizing the dual properties of secure fixation and relatively flexible implants are required. Endosteal substitution, extraosteal substitution, and combined nail/plate combinations are methods of utilizing traditional implants in a nontraditional way. Nonsurgical augmentation of fracture fixation is also paramount. PMID:23054960

Jones, Clifford B

2012-12-01

268

Surface polishing positively influences ease of plate and screw removal.  

PubMed

Difficulties removing temporary fracture fixation devices due to excessive bony on-growth results in extended surgical time leading to excessive blood loss, debris contamination and potentially refracture. Commercially available locking plates and screws are manufactured for clinics with a micro-rough surface, which contributes to the excessive bony on-growth reported. We have applied polishing technology to commercially pure titanium locking compression plates (LCP) and titanium-6%aluminium-7%niobium (TAN) plates and screws to assess if it can alleviate problems with strong bony overgrowth. Samples were implanted for 6, 12 and 18 months in a bilateral sheep tibia non fracture model and assessed for screw removal torque, percentage of bone contact and tissue-material response. Both electropolishing (p=0.001) and paste polishing (p=0.010) of TAN screws significantly reduced the mean torque required for removal compared to their micro-rough counterparts. This was accompanied by a trend for a lower percentage of bone contact for polished screws. This difference in bone contact was significant for paste polished TAN screws (p<0.001 parallel but not electropolished TAN screws (p=0.066). Ex vivo, soft tissue removal was much easier (approximately five minutes) for polished constructs, which was difficult and at least four times longer for standard micro-rough constructs. We suggest that polishing of locked plate/screw systems will improve ease of removal and reduce implant related removal complications encountered due to excessive strong bony on-growth while maintaining biocompatibility and implant stability. Future studies aim to assess the potential of this technology in the next level of complication, a fracture model. PMID:20186671

Hayes, J S; Seidenglanz, U; Pearce, A I; Pearce, S G; Archer, C W; Richards, R G

2010-01-01

269

Transpedicular-Transdiscal-Transcorporal (TPDC)Fixation  

Microsoft Academic Search

\\u000a In an attempt to minimize the surgical exposure of the lumbo-sacral junction in case of a spondylolisthesis L5\\/S1, grade I-III\\u000a (IV), or L4\\/5 and to minimize the use of implants in this region, we have developed a standardized technique of a simple screw\\u000a fixation of the listhetic segment. We use cannulated 7.3 mm cancellous short thread\\/long thread titanium screws sometimes

Max Aebi

270

Stress fracture of the proximal femur after screw removal.  

PubMed

We describe a case of stress fracture of the proximal femur occurring in a patient after removal of an internal fixation device for a comminuted subtrochanteric fracture. The presenting clinical picture resembled a late postoperative infection with a positive technetium and gallium bone scan and normal radiological findings. The stress fracture occurred after removal of the fixation device when the patient started full weight-bearing. The patient was treated initially as having osteomyelitis until a second X-radiograph some weeks later demonstrated a stress fracture through one of the previous screw holes. This case illustrates well the possible complication of a insufficiency fracture subsequent to the occurrence of stress risers through screw holes in a weakened bone when submitted to normal load. The clinical presentation may sometimes resemble late postoperative infection. PMID:8775714

Velkes, S; Nerubay, J; Lokiec, F

1996-01-01

271

Intra-operative computer navigation guided cervical pedicle screw insertion in thirty-three complex cervical spine deformities  

PubMed Central

Background: Cervical pedicle screw fixation is challenging due to the small osseous morphometrics and the close proximity of neurovascular elements. Computer navigation has been reported to improve the accuracy of pedicle screw placement. There are very few studies assessing its efficacy in the presence of deformity. Also cervical pedicle screw insertion in children has not been described before. We evaluated the safety and accuracy of Iso-C 3D-navigated pedicle screws in the deformed cervical spine. Materials and Methods: Thirty-three patients including 15 children formed the study group. One hundred and forty-five cervical pedicle screws were inserted using Iso-C 3D-based computer navigation in patients undergoing cervical spine stabilization for craniovertebral junction anomalies, cervico-thoracic deformities and cervical instabilities due to trauma, post-surgery and degenerative disorders. The accuracy and containment of screw placement was assessed from postoperative computerized tomography scans. Results: One hundred and thirty (89.7%) screws were well contained inside the pedicles. Nine (6.1%) Type A and six (4.2%) Type B pedicle breaches were observed. In 136 levels, the screws were inserted in the classical description of pedicle screw application and in nine deformed vertebra, the screws were inserted in a non-classical fashion, taking purchase of the best bone stock. None of them had a critical breach. No patient had any neurovascular complications. Conclusion: Iso-C navigation improves the safety and accuracy of pedicle screw insertion and is not only successful in achieving secure pedicle fixation but also in identifying the best available bone stock for three-column bone fixation in altered anatomy. The advantages conferred by cervical pedicle screws can be extended to the pediatric population also.

Rajasekaran, S.; Kanna, P. Rishi Mugesh; Shetty, T. Ajoy Prasad

2010-01-01

272

Retrospective Comparison of Percutaneous Fixation and Volar Internal Fixation of Distal Radius Fractures  

PubMed Central

A change in the practice of a single surgeon provided an opportunity for retrospective comparison of comparable cohorts treated with percutaneous fixation (17 patients) or a volar plate and screws (23 patients) an average of 30 months after surgery. The final evaluation was performed according to the Gartland and Werley and Mayo rating systems and the DASH questionnaire. There were no significant differences on the average scores for the percutaneous and volar plating groups, respectively: Gartland and Werley, 4 vs 5; Mayo, 82 vs 83; and DASH score 13 for both cohorts. Motion, grip, and radiographical parameters were likewise comparable. Volar internal plate and screw fixation can achieve results comparable to percutaneous fixation techniques in the treatment of fractures of the distal radius.

Lozano-Calderon, Santiago A.; Doornberg, Job N.

2007-01-01

273

Femoral nailing with transverse locking screws through the femoral neck  

Microsoft Academic Search

We treated 55 patients with subtrochanteric or comminuted femoral fractures with a transverse locking femoral nail (Alta, Howmedica). This nail was positioned more cephalad than usual so that at least one fixation screw was located in the femoral neck or head. Forty-seven fractures (20 subtrochanteric and 27 diaphyseal) were available for follow-up averaging 12 months (3-35). The time to radiographic

B. H. Ziran; A. D. Wasan; M. W. Chapman

2001-01-01

274

Surgical treatment for chronic atlantoaxial rotatory fixation in children.  

PubMed

Six consecutive pediatric patients with chronic atlantoaxial rotatory fixation (AARF) underwent posterior fixation. All patients were first treated conservatively such as with a neck collar, traction, Minerva jacket, or halo-vest; however, they failed to achieve successful reduction because of the C2 facet deformity or C1-2 facet fusion. We performed C1-2 fusion using a C1 lateral mass screw and a C2 pedicle screw, a C1-2 transarticular screw, or an occipitocervical fusion using a rod and wiring system. Five patients achieved solid fusion with no torticollis or neck pain by the final follow-up. One patient had mild torticollis after surgery but no pain. Although we believe that with early diagnosis of AARF and appropriate conservative treatment we can avoid surgery, even with conservative treatment from the onset of symptoms, five patients in our series required surgery because conservative treatment did not lead to successful reduction. When conservative treatment for chronic AARF patients fails, C1-2 transarticular fixation, and C1 lateral mass screw and C2 pedicle screw fixation are reliable methods to treat these patients. PMID:23764756

Tauchi, Ryoji; Imagama, Shiro; Ito, Zenya; Ando, Kei; Muramoto, Akio; Matsui, Hiroki; Matsumoto, Tomohiro; Yukawa, Yasutsugu; Kanemura, Tokumi; Ishiguro, Naoki

2013-09-01

275

Bicondylar tibial fractures: Internal or external fixation?  

PubMed Central

Bicondylar fractures of the tibia, representing the Schatzker V and VI fractures represent a challenging problem. Any treatment protocol should aim at restoring articular congruity and the metaphyseo-diaphsyeal dissociation (MDD)—both of these are equally important to long-term outcome. Both internal and external fixations have their proponents, and each method of treatment is associated with its unique features and complications. We review the initial and definitive management of these injuries, and the advantages and disadvantages of each method of definitive fixation. We suggest the use of a protocol for definitive management, using either internal or external fixation as deemed appropriate. This protocol is based on the fracture configuration, local soft tissue status and patient condition. In a nutshell, if the fracture pattern and soft tissue status are amenable plate fixation (single or double) is performed, otherwise limited open reduction and articular surface reconstruction with screws and circular frame is performed.

Kumar, Gunasekaran; Peterson, Nicholas; Narayan, Badri

2011-01-01

276

[Time saving and effective method of temporary intraoperative reposition in mandibular fractures. Realization with the FAMI screw].  

PubMed

Open reduction and rigid fixation with maxillomandibular fixation at least intraoperatively is the method of choice for treatment of mandibular fractures. We report an effective method of internal temporary fixation which significantly facilitates fracture reduction and stabilization. The technique is used in combination with special FAMI screws and a monocortical miniplates system according to Champy, which eliminates in most cases the need for maxillomandibular fixation. Our results in 78 patients with mandibular fractures confirmed the reliability and the efficiency of the internal temporary fixation. PMID:10077962

Fangmann, R; Mischkowski, R A; Hidding, J

1999-01-01

277

Planning and insertion of pedicle screws with computer assistance.  

PubMed

Transpedicular screw fixation relies on thorough knowledge of the pedicular anatomy and a reliable intraoperative technique. To enhance the safety and accuracy of screw insertion, computer-assisted systems have been introduced. Our in vitro study investigated the potential benefits of such a system for the preoperative planning and the intraoperative visualization. In part 1, the potentially possible range of screw paths (trajectories) through lumbar pedicles was analyzed. In part 2, the accuracy of actual pedicle-hole preparation with and without preoperative planning was assessed. It was shown that, especially in the lower lumbar regions, the possible range of trajectories is considerable, with inclinations of < or = 40 degrees in the transverse plane and a range of angulation in the sagittal plane of > 20 degrees. The computer assistance in preparation of 100 pedicle holes resulted in cortex perforation in only one case. Computer assistance therefore may be used as a valuable tool to minimize the risks of transpedicular screw insertion. It furthermore may assist in determining the desired screw orientation and length and transform this planning into the intraoperative pedicle-hole preparation. PMID:9113610

Berlemann, U; Monin, D; Arm, E; Nolte, L P; Ozdoba, C

1997-04-01

278

Parallel analysis of finite element model controlled trial and retrospective case control study on percutaneous internal fixation for vertical sacral fractures  

PubMed Central

Background Although percutaneous posterior-ring tension-band metallic plate and percutaneous iliosacral screws are used to fix unstable posterior pelvic ring fractures, the biomechanical stability and compatibility of both internal fixation techniques for the treatment of Denis I, II and III type vertical sacral fractures remain unclear. Methods Using CT and MR images of the second generation of Chinese Digitized Human “male No. 23”, two groups of finite element models were developed for Denis I, II and III type vertical sacral fractures with ipsilateral superior and inferior pubic ramus fractures treated with either a percutaneous metallic plate or a percutaneous screw. Accordingly, two groups of clinical cases that were fixed using the above-mentioned two internal fixation techniques were retrospectively evaluated to compare postoperative effect and function. Parallel analysis was performed with a finite element model controlled trial and a case control study. Results The difference of the postoperative Majeed standards and outcome rates between two case groups was no statistically significant (P?>?0.05). Accordingly, the high values of the maximum displacements/stresses of the plate-fixation model group approximated those of the screw-fixation model group. However, further simulation of Denis I, II and III type fractures in each group of models found that the biomechanics of the plate-fixation models became increasingly stable and compatible, whereas the biomechanics of the screw-fixation models maintained tiny fluctuations. When treating Denis III fractures, the biomechanical effects of the pelvic ring of the plate-fixation model were better than the screw-fixation model. Conclusions Percutaneous plate and screw fixations are both appropriate for the treatment of Denis I and II type vertical sacral fractures; whereas percutaneous plate fixation appears be superior to percutaneous screw fixation for Denis III type vertical sacral fracture. Biomechanical evidence of finite element evaluations combined with clinical evidence will contribute to our ability to distinguish between indications that require plate or screw fixation for vertical sacral fractures.

2013-01-01

279

Complications of Rigid Internal Fixation  

PubMed Central

Over the past 20 years, there have been many advances in the development of bone fixation systems used in the practice of craniomaxillofacial surgery. As surgical practices have evolved, the complications of each technologic advance have changed accordingly. Interfragmentary instability of interosseous wiring has been replaced by the risk of exposure, infection, and palpability of plate and screw fixation systems. The improved rigidity of plate fixation requires anatomic alignment of fracture fragments. Failure to obtain proper alignment has led to the phenomenon known as “open internal fixation” of fracture fragments without proper reduction. The size of the plates has decreased to minimize palpability and exposure. However limitations in their application have been encountered due to the physiologic forces of the muscles of mastication and bone healing. In the pediatric population, the long-standing presence of plates in the cranial vault resulted in reports of transcranial migration and growth restriction. These findings led to the development of resorbable plating systems, which are associated with self-limited plate palpability and soft tissue inflammatory reactions. Any rigid system including these produces growth restriction in varying amounts. In this discussion, we review the reported complication rates of miniplating and microplating systems as well as absorptive plating systems in elective and traumatic craniofacial surgery.

Campbell, Chris A.; Lin, Kant Y.

2009-01-01

280

ADDITION  

NSDL National Science Digital Library

Addition can be so much fun, especially with these games. Tweet, Tweet, Addition is not a game for the birds. Keep the game Math Popper away from all sharp pins! Watch out! Addition facts are attacking the spaceships in Addition Attack In Cannon Math you can shoot people out of a cannon! It is great fun!! Dr. Brain s Robot needs help with his math facts. Can you help ...

Games, Aidan'S M.

2010-12-20

281

Additives  

NASA Technical Reports Server (NTRS)

The chemistry of lubricant additives is discussed to show what the additives are chemically and what functions they perform in the lubrication of various kinds of equipment. Current theories regarding the mode of action of lubricant additives are presented. The additive groups discussed include the following: (1) detergents and dispersants, (2) corrosion inhibitors, (3) antioxidants, (4) viscosity index improvers, (5) pour point depressants, and (6) antifouling agents.

Smalheer, C. V.

1973-01-01

282

Dynamic-locking-screw (DLS)-leads to less secondary screw perforations in proximal humerus fractures  

PubMed Central

Background Loss of reduction and screw perforation causes high failure rates in the treatment of proximal humerus fractures. The purpose of the present study was to evaluate the early postoperative complications using modern Dynamic Locking Screws (DLS 3.7) for plating of proximal humerus fractures. Methods Between 03/2009 and 12/2010, 64 patients with acute proximal humerus fractures were treated by angular stable plate fixation using DLSs in a limited multi-centre study. Follow-up examinations were performed three, six, twelve and twenty-four weeks postoperatively and any complications were carefully collected. Results 56 of 64 patients were examined at the six-month follow-up. Complications were observed in 12 patients (22%). In five cases (9%), a perforation of the DLS 3.7 occurred. Conclusions Despite the use of modern DLS 3.7, the early complications after plating of proximal humerus fractures remain high. The potential advantage of the DLS 3.7 regarding secondary screw perforation has to be confirmed by future randomized controlled trials.

2014-01-01

283

Anterior subcutaneous internal fixation for treatment of unstable pelvic fractures  

PubMed Central

Background Fractures of the pelvic ring including disruption of the posterior elements in high-energy trauma have both high morbidity and mortality rates. For some injury pattern part of the initial resuscitation includes either external fixation or plate fixation to close the pelvic ring and decrease blood loss. In certain situations – especially when associated with abdominal trauma and the need to perform laparotomies – both techniques may put the patient at risk of either pintract or deep plate infections. We describe an operative approach to percutaneously close and stabilize the pelvic ring using spinal implants as an internal fixator and report the results in a small series of patients treated with this technique during the resuscitation phase. Findings Four patients were treated by subcutaneous placement of an internal fixator. Screw fixation was carried out by minimally invasive placement of two supra-acetabular iliac screws. Afterwards, a subcutaneous transfixation rod was inserted and attached to the screws after reduction of the pelvic ring. All patients were allowed to fully weight-bear. No losses of reduction or deep infections occurred. Fracture healing was uneventful in all cases. Conclusion Minimally invasive fixation is an alternative technique to stabilize the pelvic ring. The clinical results illustrate that this technique is able to achieve good results in terms of maintenance of reduction the pelvic ring. Also, abdominal surgeries no longer put the patient at risk of infected pins or plates.

2014-01-01

284

Fixation of distal radius fractures in adults: a review.  

PubMed

In patients for whom function is a priority, anatomic reduction and stable fixation are prerequisites for good outcomes. Several therapeutic options exist, including orthopedic treatment and internal fixation with pins (intra- and extrafocal), external fixation which may or may not bridge the wrist, and different internal fixation techniques with dorsal or palmar plates using or not, locking screws. Arthroscopy may be necessary in case of articular fracture. In the presence of significant metaphyseal bone defects, filling of the comminution with phosphocalcic cements provides better graft stability. The level of evidence is too low to allow recommending one type of fixation for one type of fracture; and different fixation options to achieve stable reduction exist, each with its own specific complications. With the new generations of palmar plate, secondary displacement is becoming a thing of the past. PMID:23518070

Obert, L; Rey, P-B; Uhring, J; Gasse, N; Rochet, S; Lepage, D; Serre, A; Garbuio, P

2013-04-01

285

Comparison of Surgical Outcomes in Thoracolumbar Fractures Operated with Posterior Constructs Having Varying Fixation Length with Selective Anterior Fusion  

PubMed Central

Purpose Surgical treatment in the case of thoracolumbar burst fractures is very controversial. Posterior instrumentation is most frequently used, however, but the number of levels to be instrumented still remains a matter of debate. Materials and Methods A total of 94 patients who had a single burst fracture between T11 and L2 were selected and were managed using posterior instrumentation with anterior fusion when necessary. They were divided into three groups as follows; Group I (n = 28) included patients who were operated by intermediate segment fixation, Group II (n = 32) included patients operated by long segment fixation, and Group III (n = 34) included those operated by intermediate segment fixation with a pair of additional screws in the fractured vertebra. The mean follow-up period was twenty one months. The outcomes were analyzed in terms of kyphosis angle (KA), regional kyphosis angle (RA), sagittal index (SI), anterior height compression rate, Frankel classification, and Oswestry Disability Index questionnaire. Results In Groups II and III, the correction values of KA, RA, and SI were much better than in Group I. At the final follow up, the correction values of KA (6.3 and 12.1, respectively) and SI (6.2 and 12.0, respectively) were in Groups II and III found to be better in the latter. Conclusion The intermediate segment fixation with an additional pair of screws at the fracture level vertebra gives results that are comparable or even better than long segment fixation and gives an advantage of preserving an extra mobile segment.

Kim, Hak Sun; Lee, Seung Yup; Nanda, Ankur; Kim, Ju Young; Park, Jin Oh; Moon, Seong Hwan; Lee, Hwan Mo; Kim, Ho Joong; Wei, Huan

2009-01-01

286

Transarticular (transpedicular) metal plate fixation for stabilization of the lumbar and thoracic spine  

Microsoft Academic Search

Summary The operation of metal plate fixation of the articular column with the screws traversing the anterior vertebral arch (ventral pedicles) and anchored within the vertebral body is described in detail. The method can be recommended as easy to perform. It gives sufficiently stable fixation in cases where instability of the thoracic or lumbar spine can be expected during an

H. D. Herrmann; H. D. Herrrnann

1979-01-01

287

Addition  

NSDL National Science Digital Library

We will practice adding! Practice with Fribbit! Fribbit Addition Help the pirate add his marbles. Pirate Marble Addition Help the whale get to freedom! Save the Whale Catch the correct sum! Fish Addish Balance the sides of the equal sign. Balance Equations ...

Hoffmann, Mrs.

2011-08-09

288

Low noise lead screw positioner  

NASA Technical Reports Server (NTRS)

A very precise and low noise lead screw positioner, for positioning a retroreflector in an interferometer is described. A gas source supplies inert pressurized gas, that flows through narrow holes into the clearance space between a nut and the lead screw. The pressurized gas keeps the nut out of contact with the screw. The gas flows axially along the clearance space, into the environment. The small amount of inert gas flowing into the environment minimizes pollution. By allowing such flow into the environment, no seals are required between the end of the nut and the screw.

Perkins, Gerald S. (inventor)

1986-01-01

289

Tacks: a new technique for craniofacial fixation.  

PubMed

Biodegradable fixation in craniofacial surgery provides secure fixation while eliminating much of the concern over intracranial migration of metallic plates and screws. One limitation of present biodegradable systems, however, is the need for tapping the drill hole before screw insertion. Herein, a new method of rigid, biodegradable fixation with tacks (Macrapore, Inc., San Diego, CA) is described. The tacks are made of a 70:30 ratio of the L and DL form of polylactic acid (L,DL-PLA). Degradation times range from 18 to 36 months. Newer prototypes are nearly developed for more rapid dissolution times. From April 1999 to February 2000, tack fixation has been applied in 100 patients (51 males, 49 females aged 3 months to 61 years). Indications for operation were craniosynostosis (n = 33); craniofacial trauma or post-traumatic deformities (n = 11); cleft lip and palate (n = 13); craniofacial syndromes (n = 18); other diagnoses (n = 11). Patients underwent fronto-orbital advancement with cranial reshaping; monobloc osteotomy, open reduction-internal fixation of fractures; hypertelorbitism repair; cranioplasty; stabilization of grafts; major cranial reconstruction; zygomatic advancement; alveolar cleft repair; and iliac bone graft donor site protection. Tacks were also used for temporalis muscle and lateral canthal suspension. Follow-up ranged from 16 to 28 months. Complications occurred in 7 patients, 4 of whom had infections and during debridement had biodegradable implants removed. None of the complications appeared to be related to the use of tacks. The tacks are carried in a specially designed holder and may be placed by hand or with the light tap of a mallet on the tack driver. An automatic driver has been developed. Overall, the performance of the tacks has been excellent. They are easily handled by the nursing personnel and rapidly inserted by the surgeon. Stability appears to be excellent. At this time, it is probably preferable to employ tap and screws for orthognathic surgery or other osteotomies with substantial load bearing. PMID:11711829

Cohen, S R; Holmes, R E; Amis, P; Fitchner, H; Shusterman, E M

2001-11-01

290

Late diagnosis of perforation of the aorta by a pedicle screw.  

PubMed

Although the clinical and biomechanical advantages of pedicle screws are well documented, the accuracy of their insertion is always a concern.Injury of neurovascular structures could be devastating. Perforation of the aorta from posteriorly placed screws is fortunately rare but could end up being lethal. We present a review of the current literature along with two illustrative cases with aorta perforation from posterior pedicle screws. An 82-year-old female with a history of thoracic kyphosis and a 26-year-old female with scoliotic deformity were referred to our institution owing to back pain. Both patients had undergone correction of their deformities and posterior fixation using posterior pedicle screws and rods 5 years previously. During the diagnostic work-up, which included CT scans, we incidentally found one pedicle screw to be malpositioned, exiting the vertebral body and perforating the aorta. The patients were offered a combined orthopaedic and vascular procedure, including screw removal and endovascular stenting of the aorta. Potential complications from the presence of a screw inside the pulsatile aorta, and the complexity of revision surgery should be well considered before proceeding to such a difficult surgical procedure. Systemic postoperative follow-up imaging and safer intraoperative practices during screw placement are important. PMID:24205763

Soultanis, Konstantinos Chr; Sakellariou, Vasileios I; Starantzis, Konstantinos A; Papagelopoulos, Panayiotis J

2013-08-01

291

Modified C1 lateral mass screw insertion using a high entry point to avoid postoperative occipital neuralgia.  

PubMed

For the past decade, a screw-rod construct has been used commonly to stabilize the atlantoaxial joint, but the insertion of the screw through the C1 lateral mass (LM) can cause several complications. We evaluated whether using a higher screw entry point for C1 lateral mass (LM) fixation than in the standard procedure could prevent screw-induced occipital neuralgia. We enrolled 12 consecutive patients who underwent bilateral C1 LM fixation, with the modified screw insertion point at the junction of the C1 posterior arch and the midpoint of the posterior inferior portion of the C1 LM. We measured postoperative clinical and radiological parameters and recorded intraoperative complications, postoperative neurological deficits and the occurrence of occipital neuralgia. Postoperative plain radiographs were used to check for malpositioning of the screw or failure of the construct. Four patients underwent atlantoaxial stabilization for a transverse ligament injury or a C1 or C2 fracture, six patients for os odontoideum, and two patients for C2 metastasis. No patient experienced vertebral artery injury or cerebrospinal fluid leak, and all had minimal blood loss. No patient suffered significant occipital neuralgia, although one patient developed mild, transient unilateral neuralgia. There was also no radiographic evidence of construct failure. Twenty screws were positioned correctly through the intended entry points, but three screws were placed inferiorly (that is, below the arch), and one screw was inserted too medially. When performing C1-C2 fixation using the standard (Harms) construct, surgeons should be aware of the possible development of occipital neuralgia. A higher entry point may prevent this complication; therefore, we recommend that the screw should be inserted into the arch of C1 if it can be accommodated. PMID:23117140

Lee, Sun-Ho; Kim, Eun-Sang; Eoh, Whan

2013-01-01

292

Two cannulated hip screws for femoral neck fractures: treatment of choice or asking for trouble?  

Microsoft Academic Search

Introduction: Undisplaced intracapsular fractures are predominantly treated with a minimally invasive fixation technique, whereas the standard treatment for displaced intracapsular fractures is still a subject of discussion. The purpose of this study was to identify the determinants influencing the outcome of intracapsular femoral neck fractures, treated with two cannulated hip screws. Patients and methods: From January 1998 through December 2002

Patrick Krastman; Rob P. van den Bent; Pieta Krijnen; Inger B. Schipper

2006-01-01

293

Arthroscopic Preparation and Internal Fixation of an Unstable Osteochondritis Dissecans Lesion of the Knee  

PubMed Central

We present our arthroscopic technique for fixation of an unstable osteochondritis dissecans (OCD) lesion. This technique includes arthroscopic evaluation of cartilage and bone quality of the OCD fragment, hinging open the lesion, debridement of fibrous nonunion tissue, reducing the fragment, and obtaining multi-point compression screw fixation. This technique avoids the morbidity of an open arthrotomy and should be considered when treating an unstable OCD lesion with adequate bone for fixation.

Camp, Christopher L.; Krych, Aaron J.; Stuart, Michael J.

2013-01-01

294

Migration pattern of cementless press fit cups in the presence of stabilizing screws in total hip arthroplasty  

PubMed Central

The aim of this study was to evaluate the initial acetabular implant stability and late acetabular implant migration in press fit cups combined with screw fixation of the acetabular component in order to answer the question whether screws are necessary for the fixation of the acetabular component in cementless primary total hip arthroplasty. One hundred and seven hips were available for follow-up after primary THA using a cementless, porous-coated acetabular component. A total of 631 standardized radiographs were analyzed digitally by the "single-film-x-ray-analysis" method (EBRA). One hundred 'and one (94.4%) acetabular components did not show significant migration of more than 1 mm. Six (5.6%) implants showed migration of more than 1 mm. Statistical analysis did not reveal preoperative patterns that would identify predictors for future migration. Our findings suggest that the use of screw fixation for cementless porous- coated acetabular components for primary THA does not prevent cup migration.

2011-01-01

295

Radiographic Evaluation of Dorsal Screw Penetration After Volar Fixed-Angle Plating of the Distal Radius: A Cadaveric Study  

Microsoft Academic Search

Introduction  Extensor tendon irritation and attritional tendon ruptures are potentially serious complications after open reduction and\\u000a internal fixation of distal radius fractures. These complications are well recognized after dorsal plating of distal radii;\\u000a and these are now being reported after errant screw placement during volar fixed-angle plating. Intraoperative detection of\\u000a improper screw placement is critical, as corrective action can be taken

Steven D. Maschke; Peter J. Evans; David Schub; Richard Drake; Jeffrey N. Lawton

2007-01-01

296

The path of screw insertion for stabilization of the scapholunate joint: a cadaveric study.  

PubMed

The aim of this study was to determine the path of screw placement to avoid breaching the articular surface of both lunate and scaphoid bones at the radiocarpal and midcarpal joints. An Acutrak screw was inserted into the right scapholunate joint of ten cadavers starting immediately distal to the tip of the radial styloid and aiming for the tip of the ulnar styloid. The articular surfaces of the scaphoid and lunate bones in all ten cadavers were exposed and examined. A computed tomography (CT) scan of four wrists was performed. Eight of the ten cadavers had no perforation or destruction of the articular surfaces. Screw stabilization of the scapholunate joint can be performed without perforation or destruction of the lunate or scaphoid surfaces. We recommend that if this form of fixation is being used then the screw should be inserted commencing at the radial styloid tip and aiming for ulnar styloid tip, under radiological guidance. PMID:24641760

Flannery, O M; Murphy, L C; Dockery, P; O'Sullivan, M E

2014-01-01

297

Biomechanical and histological evaluation of an expandable pedicle screw in osteoporotic spine in sheep  

PubMed Central

Transpedicular fixation can be challenging in the osteoporotic spine as reduced bone mineral density compromises the mechanical stability of the pedicle screw. Here, we sought to investigate the biomechanical and histological properties of stabilization of expandable pedicle screw (EPS) in the osteoporotic spine in sheep. EPSs and standard pedicle screws, SINO screws, were inserted on the vertebral bodies in four female ovariectomized sheep. Pull-out and cyclic bending resistance test were performed to compare the holding strength of these pedicle screws. High-resolution micro-computed tomography (CT) was performed for three-dimensional image reconstruction. We found that the EPSs provided a 59.6% increase in the pull-out strength over the SINO screws. Moreover, the EPSs withstood a greater number of cycles or load with less displacement before loosening. Micro-CT image reconstruction showed that the tissue mineral density, bone volume fraction, bone surface/bone volume ratio, trabecular thickness, and trabecular separation were significantly better in the expandable portion of the EPSs than those in the anterior portion of the SINO screws (P < 0.05). Furthermore, the trabecular architecture in the screw–bone interface was denser in the expandable portion of the EPS than that in the anterior portion of the SINO screw. Histologically, newly formed bone tissues grew into the center of EPS and were in close contact with the EPS. Our results show that the EPS demonstrates improved biomechanical and histological properties over the standard screw in the osteoporotic spine. The EPS may be of value in treating patients with osteoporosis and warrants further clinical studies.

Wan, Shiyong; Wu, Zixiang; Liu, Da; Gao, Mingxuan; Fu, Suochao

2010-01-01

298

Occipital condyle screw placement and occipitocervical instrumentation using three-dimensional image-guided navigation.  

PubMed

Occipital condyle (OC) screws are an alternative cephalad fixation point in occipitocervical fusion. Safe placement of occipital, C1 lateral mass, and C2 pars screws have been described previously, but not OC screws. The craniocervical junction is complex, and a thorough understanding of the anatomy is needed. Three-dimensional (3D) image-guided navigation was used in six patients. There were no complications related to image-guided navigation during the placement of 12 OC screws and we found that this navigation can serve as a useful adjunct when placing an OC screw. Technical considerations of placing OC and C1 lateral mass screws are discussed with particular reference to patient positioning and the StealthStation® S7™ image-guided navigational platform (Medtronic, Minneapolis, MN, USA). The reference arc is attached to the head-clamp and faces forward. The optical camera and monitor are positioned at the head of the table for a direct, non-obstructed line-of-sight. To minimize intersegmental movement, the OC should not be drilled until all other screws have been placed. We conclude that 3D image-guided navigation is a useful adjunct that can be safely and effectively used for placement of instrumentation of the upper cervical spine including the OC. PMID:22356730

Le, Tien V; Burkett, Clint; Ramos, Edwin; Uribe, Juan S

2012-05-01

299

Biomechanical comparison of different combinations of hook and screw in one spine motion unit - an experiment in porcine model  

PubMed Central

Background The biomechanical performance of the hooks and screws in spinal posterior instrumentation is not well-characterized. Screw-bone interface failure at the uppermost and lowermost vertebrae is not uncommon. Some have advocated for the use of supplement hooks to prevent screw loosening. However, studies describing methods for combined hook and screw systems that fully address the benefits of these systems are lacking. Thus, the choice of which implant to use in a given case is often based solely on a surgeon’s experience instead of on the biomechanical features and advantages of each device. Methods We conducted a biomechanical comparison of devices instrumented with different combinations of hooks and screws. Thirty-six fresh low thoracic porcine spines were assigned to three groups (12 per group) according to the configuration used for of fixation: (1) pedicle screw; (2) lamina hook and (3) combination of pedicle screw and lamina hook. Axial pullout tests backward on transverse plane in the direction normal to the rods were performed using a material testing machine and a specially designed grip with self-aligned function. Results The pullout force for the pedicle screws group was significantly greater than for the hooks and the combination (p??0.05). Conclusions Pedicle screws achieve the maximal pullout strength for spinal posterior instrumentation.

2014-01-01

300

Multidisciplinary design optimization of lumbar transpedicular screws  

Microsoft Academic Search

Some of the complications associated with the use of transpedicular screws for spinal fusions include the large diameters of the screws and screw breakagein vivo. Recent advances in multidisciplinary design optimization techniques have provided a unique approach to incorporate the structural, biological, and manufacturing disciplines involved in the design process of spinal screws, allowing the development of smaller and safer

H. A. Serhan; C. L. Bloebaum; G. J. Bennett

1995-01-01

301

Short Segment Fixation for Thoracolumbar Burst Fracture Accompanying Osteopenia : A Comparative Study  

PubMed Central

Objective The purpose of this study was to compare the results of three types of short segment screw fixation for thoracolumbar burst fracture accompanying osteopenia. Methods The records of 70 patients who underwent short segment screw fixation for a thoracolumbar burst fracture accompanying osteopenia (-2.5< mean T score by bone mineral densitometry <-1.0) from January 2005 to January 2008 were reviewed. Patients were divided into three groups based on whether or not bone fusion and bone cement augmentation procedure 1) Group I (n=26) : short segment fixation with posterolateral bone fusion; 2) Group II (n=23) : bone cement augmented short segment fixation with posterolateral bone fusion; 3) Group III (n=21) : bone cement augmented, short segment percutaneous screw fixation without bone fusion. Clinical outcomes were assessed using a visual analogue scale and modified MacNab's criteria. Radiological findings, including kyphotic angle and vertebral height, and procedure-related complications, such as screw loosening or pull-out, were analyzed. Results No significant difference in radiographic or clinical outcomes was noted between patients managed using the three different techniques at last follow up. However, Group I showed more correction loss of kyphotic deformities and vertebral height loss at final follow-up, and Group I had higher screw loosening and implant failure rates than Group II or III. Conclusion Bone cement augmented procedure can be an efficient and safe surgical techniques in terms of achieving better outcomes with minimal complications for thoracolumbar burst fracture accompanying osteopenia.

Kim, Hyeun Sung; Ju, Chang Il; Lee, Sung Myung; Shin, Ho

2013-01-01

302

Comparison of Posterior Fixation Alone and Supplementation with Posterolateral Fusion in Thoracolumbar Burst Fractures  

PubMed Central

Objective We compared the radiological and clinical outcomes between patients who underwent posterior fixation alone and supplemented with fusion following the onset of thoracolumbar burst fractures. In addition, we also evaluated the necessity of posterolateral fusion for patients treated with posterior pedicle screw fixation. Methods From January 2007 to December 2009, 46 consecutive patients with thoracolumbar burst fracture were included in this study. On the basis of posterolateral fusion, we divided our patients into the non-fusion group and the fusion group. The radiological assessment was performed according to the Cobb's method, and results were obtained at immediately, 3, 6, 12 months after surgery. The clinical outcomes were evaluated using the modified Mcnab criteria at the final follow-up. Results The demographic data and the mean follow-up period were similar between the two groups. Patients of both groups achieved satisfactory clinical outcomes. The mean loss of kyphosis correction showed that patients of both groups experienced loss of correction with no respect to whether they underwent the posterolateral fusion. There was no significant difference in the degree of loss of correction at any time points of the follow-up between the two groups. In addition, we also compared the effect of fixed levels (i.e., short versus long segment) on loss of correction between the two groups and there was no significant difference. There were no major complications postoperatively and during follow-up period. Conclusion We suggest that posterolateral fusion may be unnecessary for patients with thoracolumbar burst fractures who underwent posterior pedicle screw fixation.

Hwang, Jong-Uk; Lee, Jong-Won; Kwon, Ki-Young; Lee, Hyun-Koo

2012-01-01

303

Free Hand Pedicle Screw Placement in the Thoracic Spine without Any Radiographic Guidance : Technical Note, a Cadaveric Study  

PubMed Central

Thoracic pedicle screw fixation techniques are still controversial for thoracic deformities because of possible complications including neurologic deficit. Methods to aid the surgeon in appropriate screw placement have included the use of intraoperative fluoroscopy and/or radiography as well as image-guided techniques. We describe our technique for free hand pedicle screw placement in the thoracic spine without any radiographic guidance and present the results of pedicle screw placement analyzed by computed tomographic scan in two human cadavers. This free hand technique of thoracic pedicle screw placement performed in a step-wise, consistent, and compulsive manner is an accurate, reliable, and safe method of insertion to treat a variety of spinal disorders, including spinal deformity.

Hyun, Seung-Jae; Kim, Yongjung J.; Cheh, Gene; Yoon, Seung Hwan

2012-01-01

304

Radiographic Evaluation of Dorsal Screw Penetration After Volar Fixed-Angle Plating of the Distal Radius: A Cadaveric Study  

PubMed Central

Introduction Extensor tendon irritation and attritional tendon ruptures are potentially serious complications after open reduction and internal fixation of distal radius fractures. These complications are well recognized after dorsal plating of distal radii; and these are now being reported after errant screw placement during volar fixed-angle plating. Intraoperative detection of improper screw placement is critical, as corrective action can be taken before completion of the operative procedure. The purpose of this study was to define the extensor tendon compartments at risk secondary to dorsal screw penetration and to compare pronation and supination fluoroscopic images with standard lateral images in demonstrating dorsal screw prominence during volar locked plating. Methods Eight fresh-frozen human cadaveric upper extremities underwent fixation with a volar, fixed-angle distal radius locked plate (Wright Medical Technology, Arlington, TN). Three fluoroscopic views (lateral, supinated, and pronated) followed by dorsal wrist dissections were compared to determine accuracy in detecting dorsal screw prominence and extensor tendon compartment violation. Subsequently, screws measuring 2, 4, 6, 8, and 10(mm longer than the measured depths were sequentially inserted into each distal locking screw, with each image deemed either "in" (completely inside the bone) or "out" (prominent screw tip dorsally-would typically be exchanged for a shorter screw intraoperatively). Results The radial most distal locking screw (position 1) violated either the first (25%) or second (75%) extensor tendon compartments. The average screw prominence required for radiographic detection was: 6.5(mm for lateral views and 2(mm for supinated views. Pronated views did not identify prominent screws. Screws occupying plate position 2 consistently entered Lister's tubercle, with 5/8 exiting the apex and 3/8 exiting the radial base. The average screw prominences for radiographic detection were: 2.75(mm-lateral views and 3.0(mm-supinated views. Although the screws entered the second dorsal compartment, they did not encroach upon either of the tendons. Screws occupying plate position 3 violated the third extensor tendon compartment in 7/8 specimens with 1/8 exiting the Ulan base of Lister's tubercle. The average screw prominences for radiographic detection were: 3.5(mm-lateral views and 2.5(mm-pronated views. Supinated views did not identify prominent hardware. Screws occupying plate position 4 all violated the IV dorsal extensor compartment-2/8 screws were noted to tent the posterior interosseous nerve. The average screw prominences required for radiographic detection were: 4.0(mm-lateral views and 2.5(mm-pronated views. The supinated views did not identify prominent screws. Conclusions Volar fixed-angle plating has shown great promise in the advancement of distal radius fracture management. We have seen in our referral practices and in the literature an increase in the number of extensor tendon complications arising from unrecognized dorsally prominent screws, pegs, or tines. Standard PA and lateral radiographs cannot adequately visualize screw position and length secondary to the complex geometry of the dorsal cortex. We believe this study supports the routine application of intraoperative, oblique pronosupination fluoroscopic imaging for enhanced confirmation of distal locking screw position and length.

Maschke, Steven D.; Evans, Peter J.; Schub, David; Drake, Richard

2007-01-01

305

Anterior retropharyngeal fixation C1-2 for stabilization of atlantoaxial instabilities: study of feasibility, technical description and preliminary results  

PubMed Central

Posterior transarticular screw fixation C1-2 with the Magerl technique is a challenging procedure for stabilization of atlantoaxial instabilities. Although its high primary stability favoured it to sublaminar wire-based techniques, the close merging of the vertebral artery (VA) and its violation during screw passage inside the axis emphasizes its potential risk. Also, posterior approach to the upper cervical spine produces extensive, as well as traumatic soft-tissue stripping. In comparison, anterior transarticular screw fixation C1-2 is an atraumatic technique, but has been neglected in the literature, even though promising results are published and lectured to date. In 2004, anterior screw fixation C1-2 was introduced in our department for the treatment of atlantoaxial instabilities. As it showed convincing results, its general anatomic feasibility was worked up. The distance between mid-sagittal line of C2 and medial border of the VA groove resembles the most important anatomic landmark in anterior transarticular screw fixation C1-2. Therefore, CT based measurements on 42 healthy specimens without pathology of the cervical spine were performed. Our data are compiled in an extended collection of anatomic landmarks relevant for anterior transarticular screw fixation C1-2. Based on anatomic findings, the technique and its feasibility in daily clinical work is depicted and discussed on our preliminary results in seven patients.

Kammermeier, Volker; Ulbricht, Dietmar; Assuncao, Allan; Karolus, Stefan; van den Berg, Boris; Holz, Ulrich

2006-01-01

306

How to minimize failures of fixation of unstable intertrochanteric fractures.  

PubMed

Sliding hip screws have improved the treatment of unstable intertrochanteric hip fractures and their success, compared with fixed devices, is in large part due to the sharing of load between the implant and the fracture fragments. In a prospective study of 100 patients with such fractures, five factors concerned with the fracture and its fixation were studied and odds ratios calculated of their relative importance in prediction of failure. The most important factor affecting the load borne by the fracture fragments was the amount of slide available within the device, and that affecting the load carried by the device was the position of the screw in the femoral head. For fractures fixed with a device allowing less than 10 mm of slide, and those with superior screw position, the risk of failure was increased by factors of 3.2 and 5.9, respectively. Anatomical reduction alone, rather than osteotomy, together with sliding hip screw fixation, has been recommended for these fractures in three prospective randomized trials. It is calculated here that to allow sufficient slide when employing this technique, it is essential to use a short barrel device when using dynamic screws of 85 mm or less. This has not been demonstrated before. PMID:8550168

Gundle, R; Gargan, M F; Simpson, A H

1995-11-01

307

Novel posterior fixation keratoprosthesis  

NASA Astrophysics Data System (ADS)

The keratoprosthesis is the last solution for corneally blind patients that cannot benefit from corneal transplants. Keratoprostheses that have been designed to be affixed anteriorly usually necessitate multi-step surgical procedures and are continuously subjected to the extrusion forces generated by the positive intraocular pressure; therefore, clinical results in patients prove inconsistent. We proposed a novel keratoprosthesis concept that utilizes posterior corneal fixation which `a priori' minimizes the risk of aqueous leakage and expulsion. This prosthesis is implanted in a single procedure thereby reducing the number of surgical complications normally associated with anterior fixation devices. In addition, its novel design makes this keratoprosthesis implantable in phakic eyes. With an average follow-up of 13 months (range 3 to 25 months), our results on 21 cases are encouraging. Half of the keratoprostheses were implanted in severe burn cases, with the remainder in cases of pseudo- pemphigus. Good visual results and cosmetic appearance were obtained in 14 of 21 eyes.

Lacombe, Emmanuel

1992-08-01

308

Computer navigation assisted fixation in neglected C2-C3 dislocation in an adult  

PubMed Central

A 49-year-old male presented with neck pain and deformity following an industrial accident sustained two months back. His neurology was normal except for a minimal weakness in left biceps (grade 4/5). Radiographs, magnetic resonance imaging and computed tomographic scan revealed fracture dislocation of C2-C3 with significant lateral translation of C2 over C3 without disc herniation. In view of unsuccessful closed reduction and absent disc herniation at the level of dislocation, a posterior only reduction, stabilisation and fusion with Iso-C 3D computer navigation-assisted cervical pedicle screw fixation with transverse rod-screw construct was performed. At 6 months followup the patient was completely relieved of his symptoms and was able to return to his previous occupation. The rare case is reported for the management by Iso-C 3D computer navigation assisted cervical pedicle screw fixation and reduction with transverse rod-screw construct at each involved level.

Rajasekaran, S; Subbiah, M; Shetty, Ajoy Prasad

2011-01-01

309

Intraoperative CT navigation for glenoid component fixation in reverse shoulder arthroplasty  

PubMed Central

CT navigation has been shown to improve component positioning in total shoulder arthroplasty. The technique can be useful in achieving strong initial fixation of the metal backed glenoid in reverse shoulder arthroplasty. We report a 61 years male patient who underwent reverse shoulder arthroplasty for rotator cuff arthropathy. CT navigation was used intraoperatively to identify best possible glenoid bone and to maximize the depth of the fixation screws that anchor the metaglene portion of the metal backed glenoid component. Satisfactory positioning of screws and component was achieved without any perforation or iatrogenic fracture in the scapula. CT navigation can help in maximizing the purchase of the fixation screws that dictate the initial stability of the glenoid component in reverse shoulder arthroplasty. The technique can be extended to improve glenoid component position [version and tilt] with the availability of appropriate software.

Gavaskar, Ashok S; Vijayraj, K; Subramanian, SD Muthukumar

2013-01-01

310

Benefit and accuracy of intraoperative 3D-imaging after pedicle screw placement: a prospective study in stabilizing thoracolumbar fractures  

PubMed Central

Internal fixation is the established dorsal standard procedure for the treatment of thoracolumbar fractures. The main problem of the procedure is the false positioning of the pedicle screws. The exact determination of pedicle screws has up to now only been possible through postoperative computed tomography. This study was intended to clarify the diagnostic value of intraoperative 3D scans after pedicle screw implantation in thoracolumbar spine surgery. The direct intraoperative consequences of the 3D scans are reported and the results of the 3D scans are compared with the postoperative computed tomography images. Intraoperative 3D scans were prospectively carried out from June 2006 to October 2008 on 95 patients with fractures of the thoracolumbar spine that have been treated with internal fixation. Screws positions were categorised intraoperatively, screws in relevant malposition were repositioned immediately. A computed tomography of the involved spinal section was carried out postoperatively for all patients. The positions of the pedicle screws were determined and compared in the axial reconstructions of both procedures. Four hundred and fourteen pedicles with enclosed screws were evaluated by the 3D scans. The time needed for carrying out the 3D scan amounts to an average of 8.2 min. Eleven screws (2.7%) in ten patients were primarily intraoperatively repositioned on the basis of the 3D scan evaluation. Two of 95 patients had to have false positions of the screws revised secondarily following evaluation of the computed tomographies. The secondary postoperative revision rate of the patients amounts to 2.1%. In relation to the number of screws, this is a revision rate of 0.5%. The postoperative computed tomographies showed 323 pedicles without cortical penetration by the screws (78.0%). Ninety-one screws penetrated the pedicle wall (22%). It was possible to postoperatively compare the position classifications of 406 pedicle screws. The CT showed 378 correct screw positions, while 28 screws were positioned falsely. On the basis of the 3D scans, 376 of 378 correct positions were correctly assessed. Twenty-one of 28 false positions could be correctly classified. The sensitivity of all 3D scans reached 91.3% and the specificity 98.2%. The position of 97.8% of the pedicle screws was correctly recognised by the intraoperative 3D scan. Nine screws were classified falsely (2.2%). The comparison of the classification results showed significantly higher error findings by the 3D scan in the spinal section T1–10 (P = 0.014). The image quality of the 3D scan correlates significantly with the width of the scanned pedicle, with the body mass index, the scanned spinal section and the extent of the fixation assembly. 3D scans showed a high accuracy in predicting pedicle screw position. Primary false placement of screws and primary neurovascular damage cannot be avoided. But intraoperative evaluation of the 3D scans resulted in a primary revision rate of 2.7% of the pedicle screws and we could lower the secondary revision rate to 0.5%.

Mittlmeier, Thomas; Gierer, Philip; Harms, Christoph; Gradl, Georg

2009-01-01

311

Flexor Tendon Problems after Volar Plate Fixation of Distal Radius Fractures  

Microsoft Academic Search

Four cases of flexor tendon problems which developed after volar plate fixation of distal radius fractures are presented.\\u000a All cases were associated with close contact of the screws or distal edge of the plate with the flexor tendons. Poor bone\\u000a stock or multiple bone fragments allowing loosening of the plate or non-locking screws cause the hardware to irritate the\\u000a flexor

Mehdi N. Adham; Margaret Porembski; Christine Adham

2009-01-01

312

Biomechanical comparison of a unique locking plate versus a standard plate for internal fixation of proximal humerus fractures in a cadaveric model  

Microsoft Academic Search

BackgroundNewer internal fixation devices with a locking mechanism between the plate and the screw have recently been released. The efficacy of these plates in the proximal humerus has yet to be fully described. There is a need to compare the biomechanical properties of efficacy of plate fixation with or without locking screws for surgery of two-part proximal humerus fractures. Multiple-plane

Stephen Walsh; Rudy Reindl; Edward Harvey; Gregory Berry; Lorne Beckman; Thomas Steffen

2006-01-01

313

Biomechanical comparison of a new stand-alone anterior lumbar interbody fusion cage with established fixation techniques - a three-dimensional finite element analysis  

PubMed Central

Background Initial promise of a stand-alone interbody fusion cage to treat chronic back pain and restore disc height has not been realized. In some instances, a posterior spinal fixation has been used to enhance stability and increase fusion rate. In this manuscript, a new stand-alone cage is compared with conventional fixation methods based on the finite element analysis, with a focus on investigating cage-bone interface mechanics and stress distribution on the adjacent tissues. Methods Three trapezoid 8° interbody fusion cage models (dual paralleled cages, a single large cage, or a two-part cage consisting of a trapezoid box and threaded cylinder) were created with or without pedicle screws fixation to investigate the relative importance of the screws on the spinal segmental response. The contact stress on the facet joint, slip displacement of the cage on the endplate, and rotational angle of the upper vertebra were measured under different loading conditions. Results Simulation results demonstrated less facet stress and slip displacement with the maximal contact on the cage-bone interface. A stand-alone two-part cage had good slip behavior under compression, flexion, extension, lateral bending and torsion, as compared with the other two interbody cages, even with the additional posterior fixation. However, the two-part cage had the lowest rotational angles under flexion and torsion, but had no differences under extension and lateral bending. Conclusion The biomechanical benefit of a stand-alone two-part fusion cage can be justified. This device provided the stability required for interbody fusion, which supports clinical trials of the cage as an alternative to circumferential fixations.

Chen, Shih-Hao; Tai, Ching-Lung; Lin, Chien-Yu; Hsieh, Pang-Hsing; Chen, Weng-Pin

2008-01-01

314

Absorbable fixation in forefoot surgery: a viable alternative to metallic hardware.  

PubMed

After 4 to 8 weeks of normal primary bone healing, rigid internal fixation is no longer required. Newer generation absorbable implants have become reliable and cost-effective alternatives to metallic hardware. Modern implants are formulated to have increased strength and smoother resorption over the course of 18 to 24 months, which decreases the possibility of local inflammation. Historically, bioresorbable screws can be time consuming to insert, but newer devices are being developed that help ease their insertion. A case of a bunionectomy is presented with double osteotomy on a 40-year-old nurse fixated with polyglycolic acid and poly-l-lactic acid copolymer screws. PMID:23827487

Nielson, David L; Young, Nathan J; Zelen, Charles M

2013-07-01

315

Technical tips: Dualplate fixation technique for comminuted proximal humerus fractures.  

PubMed

The authors report dualplate fixation technique for providing stable fixation in comminuted proximal humerus fractures. This technique has been used for proximal humerus fractures with metaphyseal comminution and provides excellent anatomical reduction and neck shaft angle (NSA). The recently locking plate is clinically more widely used due to its small size, low rigidity, high elasticity, and biomechanical properties such as fixed initial angle and rotational stability. However, in severely comminuted complex type proximal metaphyseal humerus fractures, the use of locking plate alone does not provide stable fixation, leading to complications such as varus collapse, anterior-posterior angulation, screw cutout, nonunion, malunion, and metal failure. Therefore, a more robust and enhanced fixation method, the dual plating technique using the locking compression plate (Proximal Humeral Internal Locking System and Variable Angle Locking Compression Plate) was developed. PMID:24813097

Choi, Sungwook; Kang, Hyunseong; Bang, Hyeongsig

2014-08-01

316

A biomechanical experiment and clinical study of the use of figure of eight plus circular wiring fixation for the treatment of olecranon fractures  

PubMed Central

The aim of the present study was to evaluate the stability of the figure of eight plus circular wiring fixation technique compared with four common internal fixation techniques and to provide experimental data for the selection of internal fixation techniques clinically. A total of 20 fresh cadaveric elbow joints were used as transverse, oblique and comminuted olecranon fracture models. Five techniques of internal fixation were investigated: circular wiring, figure of eight wiring, circular plus figure of eight wiring, Kirschner wire (K-wire) and screw fixation. The elbow joints were flexed at 90°. The fixation performance was tested using a high-precision displacement sensor. Displacement-load curves revealed that the strength of internal fixation was weakest when using circular wiring alone and that circular wiring plus figure of eight wiring fixation was stronger than that of figure of eight wiring or screw fixation. The difference was statistically significant (P<0.05). There were no significant differences between circular wiring plus figure of eight wiring fixation and K-wire fixation in the transverse and oblique fracture models (P>0.05). However, figure of eight plus circular wiring fixation was superior to K-wire fixation in the comminuted fracture model, with a tensile force of 67.42±2.17 vs. 58.52±2.17 N, respectively (P<0.05). All 152 patients with olecranon fractures who received circular wiring plus figure of eight wiring fixation recovered and 108 were included in the follow-up for an average of 12 months. The rate of excellent/fairly good recovery was 98.10%. Due to its reliability, simple surgery, lower invasiveness and lower cost, figure of eight plus circular wiring fixation is an ideal choice for the internal fixation of olecranon fractures, particularly comminuted fractures, compared with circular wiring, figure of eight wiring or screw fixation.

WANG, WULIAN; WU, GUANGWEN; SHEN, FUER; ZHANG, YIYUAN; LIU, XIANXIANG

2012-01-01

317

Evaluation of the syndesmotic-only fixation for Weber-C ankle fractures with syndesmotic injury  

PubMed Central

Background: With the length of the fibula restored and the syndesmosis reduced anatomically, internal fixation using a plating device may not be necessary for supra-syndesmotic fibular fractures combined with diastasis of inferior tibio-fibular joint. A retrospective observational study was performed in patients who had this injury pattern treated with syndesmosis-only fixation. Materials and Methods: 12 patients who had Weber type-C injury pattern were treated with syndesmosis only fixation. The treatment plan was followed only if the fibular length could be restored and if the syndesmosis could be anatomically reduced. Through a percutaneous or mini-open reduction and clamp stabilization of the syndesmosis, all but one patient had a single tricortical screw fixation across the syndesmosis. Patients were kept non-weight-bearing for 6 weeks, followed by screw removal at an average of 8 weeks. Outcomes were assessed using an objective ankle scoring system (Olerud and Molander scale) and by radiographic assessment of the ankle mortise. Results: At a mean follow-up of 13 months, the functional outcome score was 75. Excellent to good outcomes were noted in 83% of the patients. Ankle mortise was reduced in all cases, and all but one fibular fracture united without loss of fixation. Six patients had more than one malleolar injury, needing either screw or anchor fixations. One patient had late diastasis after removal of the syndesmotic screw and underwent revision surgery with bone grafting of the fibula. This was probably due to early screw removal, before union of the fibular fracture had occurred. Conclusion: We recommend syndesmosis-only fixation as an effective treatment option for a combination of syndesmosis disruption and Weber type-C lateral malleolar fractures.

Mohammed, R; Syed, S; Metikala, S; Ali, SA

2011-01-01

318

Efficacy of 2-mm locking miniplates in the management of mandibular fractures without maxillomandibular fixation  

PubMed Central

Background: The management of trauma has evolved greatly over the past many years. Various bone plating systems have been developed to provide stable fixation of mandibular fractures. The introduction of the locking plate/screw system has offered certain advantages over the conventional plating systems. This system does not require intimate adaptation of the miniplates to the underlying bone and has greater stability. This study evaluates the efficacy of locking miniplate/screw system in the treatment of mandibular fractures without maxillomandibular fixation. Materials and Methods: This was a prospective study analyzing 20 patients with undisplaced or minimally displaced mandibular fractures, who reported to Department of Oral and Maxillofacial Surgery, Government Dental College and Research Institute, Bangalore. The selected cases were treated by open reduction and internal fixation using the 2.0 mm locking plate/screw system. Results: Open reduction and internal fixation with the 2.0 mm locking plate/screw system were achieved in all the 20 cases with satisfactory stability of the fracture fragments. The system was found to be reliable and effective intraoperatively. Only two complications were noted in the study. Conclusion: The locking miniplate system was found to be reliable and effective in management of mandibular fractures without postoperative intermaxillary fixation, however further studies with more sample size is required.

Prabhakar, Chandan; Shetty, Jayaprasad N.; Hemavathy, O. R.; Guruprasad, Yadavalli

2011-01-01

319

New staple fixation for an Austin bunionectomy.  

PubMed

There are several methods available for the internal fixation of the Austin bunionectomy. By carefully forming a Kirschner wire into the shape of a staple, fixation of the neck osteotomy is maintained. The method is simple, fast, and reliable, and it requires no additional instrumentation. PMID:1573169

Kaye, J M

1992-01-01

320

Treatment of Palatal Fractures by Osteosynthesis with 2.0-mm Locking Plates as External Fixator  

PubMed Central

Treatment options for palatal fractures range from orthodontic braces, acrylic bars, and arch bars for maxillomandibular fixation to internal fixation, with plates and screws placed under the palate mucosa and periosteum, together with pyriform aperture or alveolar plating plus buttress reconstruction. Forty-five patients, ages 4 to 56, were treated using medium- or high-profile locking plates placed over the palatal mucosa as an external fixator for palatal fractures, together with treatment for other associated facial fractures. In open fractures, plates were placed after approximating the edges of the mucosal wounds. Plates and screws for palate fixation were removed at 12 weeks, when computed tomography scans provided evidence of fracture healing. All palatal fractures healed by 12 weeks, with no cases of mucosal necrosis, bone exposure, fistulae, or infections. This approach achieves adequate stability, reduces the risk of bone and mucosal necrosis, and promotes healing of mucosal wounds in case of open fractures.

Cienfuegos, Ricardo; Sierra, Eduardo; Ortiz, Benjamin; Fernandez, Gerardo

2010-01-01

321

An alternative method of fixation of calcaneal tuberosity fractures using the Tightrope(®) technique.  

PubMed

Calcaneal tuberosity fractures account for 1% to 3% of all calcaneal fractures. These fractures are frequently seen in the osteoporotic or diabetic elderly population. The patient's comorbidities, coupled with the usually osteoporotic bone, make fixing this fracture pattern a challenge. Numerous surgical techniques have been advocated for this fracture, including the standard lag screw fixation, tension band wiring, suture anchors, and direct suture repair. Whichever method is used, the construct must resist the massive pull of the gastrocnemius-soleus complex. We have described a method of fixing the avulsed calcaneal tuberosity using the TightRope(®) ankle syndesmosis fixation device (Arthrex(®), Naples, FL), which offers the advantages of allowing a robust and reliable fixation of a small or comminuted fragment. It is particularly advantageous in osteoporotic bone because of concern regarding the use of standard lag screw fixation, and it also may eliminate complications associated with retained hardware. PMID:24160723

Harb, Ziad; Dachepalli, Sunil; Mani, Ganapathyraman

2013-01-01

322

Treatment of thoracolumbar fracture with pedicle screws at injury level: a biomechanical study based on three-dimensional finite element analysis.  

PubMed

The aim of this study was to investigate the biomechanical mechanisms of treatment of thoracolumbar compression fracture with pedicle screws at injury level based on a three-dimensional finite element method. We constructed one three-dimensional finite element model of T11-L1 in a patient with a compression fracture of the T12 vertebral body(anterior edges of vertebral body were compressed to 1/2, and kyphosis Cobb angle was 18.6°) fixed by four pedicle screws and another model fixed by six pedicle screws at the injured vertebrae, and then assigned different forces to the two models to account for axial compression, flexion, extension, left lateral bending, and rightward axial rotation by Ansys software. After different loading forces were applied to the models, we recorded stress measurements on the vertebral pedicle screws, as well as the maximum displacement of T11. The stress distribution suggested that stress concentration was appreciable at the root of the pedicle screws under different loading modalities. Under axial compression, flexion, extension, left lateral bending, and rightward axial rotation load, the stress for the superior screw was significantly greater than the stress for the inferior screw (P < 0.05). The stress in the six pedicle screw fixation model was significantly decreased compared to the four screw interbody fusion model (P < 0.05), but the maximum displacement of T11 between two models under different loadings was not statistically different. The use of pedicle screws at injured vertebral bodies may optimize internal fixation load and reduce the incidence of broken screws. PMID:23412208

Li, Qin-liang; Li, Xiu-zhong; Liu, Yi; Zhang, Hu-sheng; Shang, Peng; Chu, Zhao-ming; Chen, Jin-chuan; Chen, Ming; Qin, Rujie

2013-10-01

323

Salvage hip arthroplasty after failed fixation of proximal femur fractures.  

PubMed

We reviewed 46 patients who underwent salvage hip arthroplasty (SHA) for revision of failed cannulated screws (CS), sliding hip screws (SHS), or intramedullary nails (IMN). The primary objective was to determine differences in operative difficulty. SHA after failed femoral neck fixation was associated with lower intra-operative demands than after failed peri-trochanteric fractures. Similarly, analysis by the index implant found that conversion arthroplasty after failed CSs was associated with lower intra-operative morbidity than failed SHSs or IMNs; differences between SHS and IMN were not as clear. Importantly, intra-operative data in cases of failed SHSs were similar regardless of the original fracture type, showing the device played a larger role than the fracture pattern. Complications and revision surgery rates were similar regardless of fracture type or fixation device. Our results suggest that operative demands and subsequent patient morbidity are more dependent on the index device than the fracture pattern during SHA. PMID:23489728

DeHaan, Alexander M; Groat, Tahnee; Priddy, Michael; Ellis, Thomas J; Duwelius, Paul J; Friess, Darin M; Mirza, Amer J

2013-05-01

324

Microplate fixation of prefabricated subperiosteal orbital floor implants.  

PubMed

Microplating and miniplating systems are widely available for repairing fractures involving the orbit, face, cranium, and mandible. These plates are superior to traditional wiring techniques because the fractured bones are held in position immediately after the plates have been screwed into position (rigid fixation). Recently, we have found the T-shaped microplate quite helpful in securing the prefabricated subperiosteal orbital floor implants commonly used to augment orbital volume in anophthalmic sockets. PMID:7746632

Jordan, D R

1995-01-01

325

Fatigue failures of austenitic stainless steel orthopedic fixation devices  

Microsoft Academic Search

Failures of four different 300-series austenitic stainless steel biomedical fixation implants were examined. The device fractures\\u000a were observed optically, and their surfaces were examined by scanning electron microscopy. Fractography identified fatigue\\u000a to be the failure mode for all four of the implants. In every instance, the fatigue cracks initiated from the attachment screw\\u000a holes at the reduced cross sections of

M. E. Stevenson; M. E. Barkey; R. C. Bradt

2002-01-01

326

Biomechanical evaluation of a new fixation device for the thoracic spine  

Microsoft Academic Search

The technology used in surgery for spinal deformity has progressed rapidly in recent years. Commonly used fixation techniques\\u000a may include monofilament wires, sublaminar wires and cables, and pedicle screws. Unfortunately, neurological complications\\u000a can occur with all of these, compromising the patients’ health and quality of life. Recently, an alternative fixation technique\\u000a using a metal clamp and polyester belt was developed

Michio Hongo; Brice Ilharreborde; Ralph E. Gay; Chunfeng Zhao; Kristin D. Zhao; Lawrence J. Berglund; Mark Zobitz; Kai-Nan An

2009-01-01

327

Cervical pedicle screw placement: feasibility and accuracy of two new insertion techniques based on morphometric data  

Microsoft Academic Search

This morphometric and experimental study was designed to assess the dimensions and axes of the subaxial cervical pedicles\\u000a and to compare the accuracy of two different techniques for subaxial cervical pedicle screw (CPS) placement using newly designed\\u000a aiming devices. Transpedicular fixation is increasingly used for stabilizing the subaxial cervical spine. Development of the\\u000a demanding technique is based on morphometric studies

M. Reinhold; F. Magerl; M. Rieger; M. Blauth

2007-01-01

328

The use of intraosseous screw for upper molar distalization: a case report.  

PubMed

The use of implants has made a major change in orthodontic treatment mechanics. They have replaced conventional unaesthetic and compliance dependent extraoral appliances with well accepted intraoral mechanics. Implants can be used in molar and canine distalization, intrusion and in extraoral force applications. In the present case report, treatment of a case using an intermaxillary fixation screw (IMF) will be presented. The treatment results will be evaluated using pretreatment, post distalization and post treatment cephalometric radiographs and dental casts. PMID:19212521

Polat-Ozsoy, Omür

2008-04-01

329

The Use of Intraosseous Screw for Upper Molar Distalization: A Case Report  

PubMed Central

The use of implants has made a major change in orthodontic treatment mechanics. They have replaced conventional unaesthetic and compliance dependent extraoral appliances with well accepted intraoral mechanics. Implants can be used in molar and canine distalization, intrusion and in extraoral force applications. In the present case report, treatment of a case using an intermaxillary fixation screw (IMF) will be presented. The treatment results will be evaluated using pretreatment, post distalization and post treatment cephalometric radiographs and dental casts.

Polat-Ozsoy, Omur

2008-01-01

330

Biomechanical evaluation of a new fixation device for the thoracic spine.  

PubMed

The technology used in surgery for spinal deformity has progressed rapidly in recent years. Commonly used fixation techniques may include monofilament wires, sublaminar wires and cables, and pedicle screws. Unfortunately, neurological complications can occur with all of these, compromising the patients' health and quality of life. Recently, an alternative fixation technique using a metal clamp and polyester belt was developed to replace hooks and sublaminar wiring in scoliosis surgery. The goal of this study was to compare the pull-out strength of this new construct with sublaminar wiring, laminar hooks and pedicle screws. Forty thoracic vertebrae from five fresh frozen human thoracic spines (T5-12) were divided into five groups (8 per group), such that BMD values, pedicle diameter, and vertebral levels were equally distributed. They were then potted in polymethylmethacrylate and anchored with metal screws and polyethylene bands. One of five fixation methods was applied to the right side of the vertebra in each group: Pedicle screw, sublaminar belt with clamp, figure-8 belt with clamp, sublaminar wire, or laminar hook. Pull-out strength was then assessed using a custom jig in a servohydraulic tester. The mean failure load of the pedicle screw group was significantly larger than that of the figure-8 clamp (P = 0.001), sublaminar belt (0.0172), and sublaminar wire groups (P = 0.04) with no significant difference in pull-out strength between the latter three constructs. The most common mode of failure was the fracture of the pedicle. BMD was significantly correlated with failure load only in the figure-8 clamp and pedicle screw constructs. Only the pedicle screw had a statistically significant higher failure load than the sublaminar clamp. The sublaminar method of applying the belt and clamp device was superior to the figure-8 method. The sublaminar belt and clamp construct compared favorably to the traditional methods of sublaminar wires and laminar hooks, and should be considered as an alternative fixation device in the thoracic spine. PMID:19404687

Hongo, Michio; Ilharreborde, Brice; Gay, Ralph E; Zhao, Chunfeng; Zhao, Kristin D; Berglund, Lawrence J; Zobitz, Mark; An, Kai-Nan

2009-08-01

331

A radiological and cadaveric study of oblique lumbar interbody fixation in patients with normal spinal anatomy.  

PubMed

The purpose of this study was to determine whether it would be feasible to use oblique lumbar interbody fixation for patients with degenerative lumbar disease who required a fusion but did not have a spondylolisthesis. A series of CT digital images from 60 patients with abdominal disease were reconstructed in three dimensions (3D) using Mimics v10.01: a digital cylinder was superimposed on the reconstructed image to simulate the position of an interbody screw. The optimal entry point of the screw and measurements of its trajectory were recorded. Next, 26 cadaveric specimens were subjected to oblique lumbar interbody fixation on the basis of the measurements derived from the imaging studies. These were then compared with measurements derived directly from the cadaveric vertebrae. Our study suggested that it is easy to insert the screws for L1/2, L2/3 and L3/4 fixation: there was no significant difference in measurements between those of the 3-D digital images and the cadaveric specimens. For L4/5 fixation, part of L5 inferior articular process had to be removed to achieve the optimal trajectory of the screw. For L5/S1 fixation, the screw heads were blocked by iliac bone: consequently, the interior oblique angle of the cadaveric specimens was less than that seen in the 3D digital images. We suggest that CT scans should be carried out pre-operatively if this procedure is to be adopted in clinical practice. This will assist in determining the feasibility of the procedure and will provide accurate information to assist introduction of the screws. PMID:23814253

Wu, A M; Tian, N F; Wu, L J; He, W; Ni, W F; Wang, X Y; Xu, H Z; Chi, Y L

2013-07-01

332

Validation of a finite element model of a unilateral external fixator in a rabbit tibia defect model.  

PubMed

In case of large segmental defects in load-bearing bones, an external fixator is used to provide mechanical stability to the defect site. The overall stiffness of the bone-fixator system is determined not only by the fixator design but also by the way the fixator is mounted to the bone. This stiffness is an important factor as it will influence the biomechanical environment to which tissue engineering scaffolds and regenerating tissues are exposed. A finite element (FE) model can be used to predict the system stiffness. The goal of this study is to develop and validate a 3D anatomical FE model of a bone-fixator system which includes a previously developed unilateral external fixator for a large segmental defect model in the rabbit tibia. It was hypothesized that the contact interfaces between bone and fixator screws play a major role for the prediction of the stiffness. In vitro mechanical testing was performed in order to measure the axial stiffness of cortical bone from mid-shaft rabbit tibiae and of the tibia-fixator system, as well as the bending stiffness of individual fixator screws, inserted in bone. ?CT-based case-specific FE models of cortical bone and SCREW-BONE specimens were created to simulate the corresponding mechanical test set-ups. The Young's modulus of rabbit cortical bone as well as appropriate screw-bone contact settings were derived from those FE models. We then used the derived settings in an FE model of the tibia-fixator system. The difference between the FE predicted and measured axial stiffness of the tibia-fixator system was reduced from 117.93% to 7.85% by applying appropriate screw-bone contact settings. In conclusion, this study shows the importance of screw-bone contact settings for an accurate fixator stiffness prediction. The validated FE model can further be used as a tool for virtual mechanical testing in the design phase of new tissue engineering scaffolds and/or novel patient-specific external fixation devices. PMID:23107490

Karunratanakul, Kavin; Kerckhofs, Greet; Lammens, Johan; Vanlauwe, Johan; Schrooten, Jan; Van Oosterwyck, Hans

2013-07-01

333

Comparison of the effects of rapid maxillary expansion caused by treatment with either a memory screw or a Hyrax screw on the dentofacial structures--transversal effects.  

PubMed

The aim of the present study was to investigate and compare the effects of conventional Hyrax screw treatment and memory screw treatment on skeletal and dentoalveolar structures. Thirty-two patients with maxillary transversal deficiency were divided into two groups. The memory-screw group included 17 patients (nine females and eight males), while the Hyrax-screw group comprised 15 patients (eight females and seven males). Mean ages of the subjects in the memory-screw and Hyrax-screw groups were 13.00 ± 1.29 and 12.58 ± 1.50 years, respectively. Plaster models and postero-anterior cephalograms were taken from the patients at the beginning of the treatment (T1) and at the end of expansion (T2) and retention periods (T3). The mean expansion period was 7.76 ± 1.04 days in the memory-screw group and 35.46 ± 9.39 days in the Hyrax-screw group. 'Shapiro-Wilk Normality test' was used to determine whether the investigated parameters were homogeneous or not. To determine the treatment changes within the group, 'paired t-test' and 'Wilcoxon signed-ranks test' were applied to the homogeneous and non-homogeneous parameters, respectively. Comparison between the groups was carried out using 'Student's t-test' for homogeneous parameters and 'Mann-Whitney U-test' for the rest. Rapid maxillary expansion was carried out successfully in both the groups. However, the use of memory screw may be advantageous because it shortens the maxillary expansion period, provides additional expansion in the retention period, and generates light forces relative to the conventional Hyrax screw. PMID:21876219

Hal?c?o?lu, Koray; Yavuz, Ibrahim

2014-04-01

334

Stability of cervical spine after one-level corpectomy using different numbers of screws and plate systems.  

PubMed

Anterior corpectomy and reconstruction using a plate with locking screws are standard procedures for the treatment of cervical spondylotic myelopathy. Although adding more screws to the construct will normally result in improved fixation stability, several issues need to be considered. Past reports have suggested that increasing the number of screws can result in the increase in spinal rigidity, decreased spine mobility, loss of bone and, possibly, screw loosening. In order to overcome this, options to have constrained, semi-constrained or hybrid screw and plate systems were later introduced. The purpose of this study is to compare the stability achieved by four and two screws using different plate systems after one-level corpectomy with placement of cage. A three-dimensional finite-element model of an intact C1-C7 segment was developed from computer tomography data sets, including the cortical bone, soft tissue and simulated corpectomy fusion at C4-C5. A spinal cage and an anterior cervical plate with different numbers of screws and plate systems were constructed to a fit one-level corpectomy of C5. Moment load of 1.0 N m was applied to the superior surface of C1, with C7 was fixed in all degrees of freedom. The kinematic stability of a two-screw plate was found to be statistically equivalent to a four-screw plate for one-level corpectomy. Thus, it can be a better option of fusion and infers comparable stability after one-level anterior cervical corpectomy, instead of a four-screw plate. PMID:24622982

Rosli, Ruwaida; Abdul Kadir, Mohammed R; Kamarul, Tunku

2014-04-01

335

Comparison of theoretical fixation stability of three devices employed in medial opening wedge high tibial osteotomy: a finite element analysis  

PubMed Central

Background Medial open wedge high tibial osteotomy is a well-established procedure for the treatment of unicompartmental osteoarthritis and symptomatic varus malalignment. We hypothesized that different fixation devices generate different fixation stability profiles for the various wedge sizes in a finite element (FE) analysis. Methods Four types of fixation were compared: 1) first and 2) second generation Puddu plates, and 3) TomoFix plate with and 4) without bone graft. Cortical and cancellous bone was modelled and five different opening wedge sizes were studied for each model. Outcome measures included: 1) stresses in bone, 2) relative displacement of the proximal and distal tibial fragments, 3) stresses in the plates, 4) stresses on the upper and lower screw surfaces in the screw channels. Results The highest load for all fixation types occurred in the plate axis. For the vast majority of the wedge sizes and fixation types the shear stress (von Mises stress) was dominating in the bone independent of fixation type. The relative displacements of the tibial fragments were low (in ?m range). With an increasing wedge size this displacement tended to increase for both Puddu plates and the TomoFix plate with bone graft. For the TomoFix plate without bone graft a rather opposite trend was observed. For all fixation types the occurring stresses at the screw-bone contact areas pulled at the screws and exceeded the allowable threshold of 1.2 MPa for at least one screw surface. Of the six screw surfaces that were studied, the TomoFix plate with bone graft showed a stress excess of one out of twelve and without bone graft, five out of twelve. With the Puddu plates, an excess stress occurred in the majority of screw surfaces. Conclusions The different fixation devices generate different fixation stability profiles for different opening wedge sizes. Based on the computational simulations, none of the studied osteosynthesis fixation types warranted an intransigent full weight bearing per se. The highest fixation stability was observed for the TomoFix plates and the lowest for the first generation Puddu plate. These findings were revealed in theoretical models and need to be validated in controlled clinical settings.

2014-01-01

336

Metallurgical examination of gun barrel screws  

SciTech Connect

The examination was conducted to determine the extent of degradation that had occurred after a series of firings; these screws prevent live rounds of ammunition from being loaded into the firing chamber. One concern is that if the screw tip fails and a live round is accidentally loaded into the chamber, a live round could be fired. Another concern is that if the blunt end of the screw begins to degrade by cracking, pieces could become small projectiles during firing. All screws used in firing 100 rounds or more exhibited some degree degradation, which progressively worsened as the number of rounds fired increased. (SEM, metallography, x-ray analysis, and microhardness were used.) Presence of cracks in these screws after 100 fired rounds is a serious concern that warrants the discontinued use of these screws. The screw could be improved by selecting an alloy more resistant to thermal and chemical degradation.

Bird, E.L.; Clift, T.L.

1996-06-01

337

Effects of Elevated CO2 and N Addition on Growth and N2 Fixation of a Legume Subshrub (Caragana microphylla Lam.) in Temperate Grassland in China  

Microsoft Academic Search

It is well demonstrated that the responses of plants to elevated atmospheric CO2 concentration are species-specific and dependent on environmental conditions. We investigated the responses of a subshrub legume species, Caragana microphylla Lam., to elevated CO2 and nitrogen (N) addition using open-top chambers in a semiarid temperate grassland in northern China for three years. Measured variables include leaf photosynthetic rate,

Lin Zhang; Dongxiu Wu; Huiqiu Shi; Canjuan Zhang; Xiaoyun Zhan; Shuangxi Zhou

2011-01-01

338

The role of the dorsal vertebral cortex in the stability of transpedicular screws. A biomechanical study in human cadaveric vertebrae.  

PubMed

The aim of this biomechanical study was to investigate the role of the dorsal vertebral cortex in transpedicular screw fixation. Moss transpedicular screws were introduced into both pedicles of each vertebra in 25 human cadaver vertebrae. The dorsal vertebral cortex and subcortical bone corresponding to the entrance site of the screw were removed on one side and preserved on the other. Biomechanical testing showed that the mean peak pull-out strength for the inserted screws, following removal of the dorsal cortex, was 956.16 N. If the dorsal cortex was preserved, the mean peak pullout strength was 1295.64 N. The mean increase was 339.48 N (26.13%; p = 0.033). The bone mineral density correlated positively with peak pull-out strength. Preservation of the dorsal vertebral cortex at the site of insertion of the screw offers a significant increase in peak pull-out strength. This may result from engagement by the final screw threads in the denser bone of the dorsal cortex and the underlying subcortical area. Every effort should be made to preserve the dorsal vertebral cortex during insertion of transpedicular screws. PMID:16645123

Karataglis, D; Kapetanos, G; Lontos, A; Christodoulou, A; Christoforides, J; Pournaras, J

2006-05-01

339

In Vitro and In Vivo Evaluations of Nano-Hydroxyapatite/Polyamide 66/Glass Fibre (n-HA/PA66/GF) as a Novel Bioactive Bone Screw  

PubMed Central

In this study, we prepared nano-hydroxyapatite/polyamide 66/glass fibre (n-HA/PA66/GF) bioactive bone screws. The microstructure, morphology and coating of the screws were characterised, and the adhesion, proliferation and viability of MC3T3-E1 cells on n-HA/PA66/GF scaffolds were determined using scanning electron microscope, CCK-8 assays and cellular immunofluorescence analysis. The results confirmed that n-HA/PA66/GF scaffolds were biocompatible and had no negative effect on MC3T3-E1 cells in vitro. To investigate the in vivo biocompatibility, internal fixation properties and osteogenesis of the bioactive screws, both n-HA/PA66/GF screws and metallic screws were used to repair intercondylar femur fractures in dogs. General photography, CT examination, micro-CT examination, histological staining and biomechanical assays were performed at 4, 8, 12 and 24 weeks after operation. The n-HA/PA66/GF screws exhibited good biocompatibility, high mechanical strength and extensive osteogenesis in the host bone. Moreover, 24 weeks after implantation, the maximum push-out load of the bioactive screws was greater than that of the metallic screws. As shown by their good cytocompatibility, excellent biomechanical strength and fast formation and ingrowth of new bone, n-HA/PA66/GF screws are thus suitable for orthopaedic clinical applications.

Su, Bao; Peng, Xiaohua; Jiang, Dianming; Wu, Jun; Qiao, Bo; Li, Weichao; Qi, Xiaotong

2013-01-01

340

Mechanical testing of a device for subcutaneous internal anterior pelvic ring fixation versus external pelvic ring fixation  

PubMed Central

Background Although useful in the emergency treatment of pelvic ring injuries, external fixation is associated with pin tract infections, the patient’s limited mobility and a restricted surgical accessibility to the lower abdomen. In this study, the mechanical stability of a subcutaneous internal anterior fixation (SIAF) system is investigated. Methods A standard external fixation and a SIAF system were tested on pairs of Polyoxymethylene testing cylinders using a universal testing machine. Each specimen was subjected to a total of 2000 consecutive cyclic loadings at 1 Hz with sinusoidal lateral compression/distraction (+/?50 N) and torque (+/? 0.5 Nm) loading alternating every 200 cycles. Translational and rotational stiffness were determined at 100, 300, 500, 700 and 900 cycles. Results There was no significant difference in translational stiffness between the SIAF and the standard external fixation when compared at 500 (p?=?.089), 700 (p?=?.081), and 900 (p?=?.266) cycles. Rotational stiffness observed for the SIAF was about 50 percent higher than the standard external fixation at 300 (p?=?.005), 500 (p?=?.020), and 900 (p?=?.005) cycles. No loosening or failure of the rod-pin/rod-screw interfaces was seen. Conclusions In comparison with the standard external fixation system, the tested device for subcutaneous internal anterior fixation (SIAF) in vitro has similar translational and superior rotational stiffness.

2014-01-01

341

Designs and Techniques That Improve the Pullout Strength of Pedicle Screws in Osteoporotic Vertebrae: Current Status  

PubMed Central

Osteoporosis is a medical condition affecting men and women of different age groups and populations. The compromised bone quality caused by this disease represents an important challenge when a surgical procedure (e.g., spinal fusion) is needed after failure of conservative treatments. Different pedicle screw designs and instrumentation techniques have been explored to enhance spinal device fixation in bone of compromised quality. These include alterations of screw thread design, optimization of pilot hole size for non-self-tapping screws, modification of the implant's trajectory, and bone cement augmentation. While the true benefits and limitations of any procedure may not be realized until they are observed in a clinical setting, axial pullout tests, due in large part to their reproducibility and ease of execution, are commonly used to estimate the device's effectiveness by quantifying the change in force required to remove the screw from the body. The objective of this investigation is to provide an overview of the different pedicle screw designs and the associated surgical techniques either currently utilized or proposed to improve pullout strength in osteoporotic patients. Mechanical comparisons as well as potential advantages and disadvantages of each consideration are provided herein.

Shea, Thomas M.; Laun, Jake; Gonzalez-Blohm, Sabrina A.; Doulgeris, James J.; Lee, William E.; Vrionis, Frank D.

2014-01-01

342

The Treatment of Intra-articular Calcaneus Fractures with Severe Soft Tissue Damage with a Hinged External Fixator or Internal Stabilization: Long-term Results  

Microsoft Academic Search

We developed a hinged external fixator for the treatment of dislocated intra-articular calcaneus fractures with severe soft tissue damage. The external fixation was performed with a known external fixator system. The screw insertion points were biomechanically tested by defining a virtual rotation axis through the center of the talus to allow early active motion in the ankle joint. Long-term follow-up

Lutz Besch; Jan Soeren Waldschmidt; Mark Daniels-Wredenhagen; Deike Varoga; Michael Mueller; Ralf-Erik Hilgert; Guenther Mathiak; Stefanie Oestern; Sebastian Lippross; Andreas Seekamp

2010-01-01

343

Computer-assisted percutaneous scaphoid fixation: concepts and evolution.  

PubMed

Background?The treatment for undisplaced scaphoid waist fractures has evolved from conventional cast immobilization to percutaneous screw insertion. Percutaneous fixation reduces some of the risks of open surgery, but can be technically demanding and carries the risk of radiation exposure. Recently, computer-assisted percutaneous scaphoid fixation (CAPSF) has been gaining interest. Materials and Methods?Conventional percutaneous scaphoid fixation is performed under fluoroscopic guidance and involves insertion of a guide wire along the length of the scaphoid to facilitate placement of a cannulated screw. Adapting computer-assisted techniques for scaphoid fixation poses several unique challenges including patient tracking and registration. Results?To date, five groups have successfully implemented systems for CAPSF. These systems have implemented wrist immobilization strategies to resolve the issue of patient tracking and have developed unique guidance techniques incorporating 2D fluoroscope, cone-beam CT, and ultrasound, to circumvent patient-based registration. Conclusions?Computer-aided percutaneous pinning of scaphoid waist fractures can significantly reduce radiation exposure and has the potential to improve the accuracy of this procedure. This article reviews the rationale for, and the evolution of, CAPSF and describes the key principles of computer-assisted technology. PMID:24436833

Smith, Erin J; Ellis, Randy E; Pichora, David R

2013-11-01

344

Technique tip: percutaneous fixation of partial incongruous Lisfranc injuries in athletes.  

PubMed

Open reduction with screw fixation is considered the standard surgical approach for injuries of the Lisfranc complex in athletes. However, multiple incisions are required, which increase the risk for postoperative complications. We present a novel percutaneous reduction and solid screw fixation technique that may be a viable option to address partial incongruous injuries of the Lisfranc complex in athletes. At our institution, no intraoperative or postoperative complications have been encountered. Screw breakage did not occur. Reduction of the second metatarsal was considered anatomic across all patients. All patients have returned to their respective sport without limitation. The percutaneous approach appears to decrease complications while the targeting-reduction guide appears to precisely reduce the injury. Consequently, outcomes have been more consistent and predictable. The authors note that this percutaneous approach is specific to partial incongruous injuries of the Lisfranc complex. When presented with more extensive injuries, the authors advocate an open approach. PMID:23631892

Bleazey, Scott T; Brigido, Stephen A; Protzman, Nicole M

2013-06-01

345

PHYSIOLOGY OF NITROGEN FIXATION BY BACILLUS POLYMYXA  

PubMed Central

Grau, F. H. (University of Wisconsin, Madison) and P. W. Wilson. Physiology of nitrogen fixation by Bacillus polymyxa. J. Bacteriol. 83:490–496. 1962.—Of 17 strains of Bacillus polymyxa tested for fixation of molecular nitrogen, 15 fixed considerable quantities (30 to 150 ?g N/ml). Two strains of the closely related B. macerans did not use N2, but possibly other members of this species may do so. Confirmation of fixation was obtained by showing incorporation of N15 into cell material. Both iron and molybdenum are specifically required for fixation; without the addition of these metals to the nitrogen-free medium, the growth rate and the total nitrogen fixed were reduced about 30 to 50%. No requirement for added molybdenum could be shown when ammonia was the nitrogen source, and the absence of iron caused only a slight decrease in growth. Washed-cell suspensions of B. polymyxa containing an active hydrogenase readily incorporated N15 into cell materials when provided with mannitol, glucose, or pyruvate but not when formate was the substrate. Hydrogen is a specific inhibitor of fixation, reducing both the rate and final amount of nitrogen fixed; it did not reduce growth on ammonia. Fixation was strictly anaerobic, 1% oxygen in the gas phase being sufficient to stop fixation. Arsenate is a powerful inhibitor of fixation of N2 by washed-cell suspensions of B. polymyxa, indicating that high-energy phosphate may be significant for this process.

Grau, F. H.; Wilson, P. W.

1962-01-01

346

Transpedicular plate fixator as effective system of spine stabilisation: biomechanical characteristics  

Microsoft Academic Search

Introduction  Zespol fixator, which was created in Poland by Ramatowski and Granowski, has an angular stable connection of screws and plate.\\u000a These properties of this plate fixator, that is effective and not an expensive system of osteosynthesis of shaft of long bone\\u000a widely used in Poland, impelled us to adapt it as a transpedicular plate fixator of spine.\\u000a \\u000a \\u000a \\u000a Aim  The aim of

Piotr Paw?owski; Maciej Araszkiewicz; Tomasz Topoli?ski; Dariusz M?tewski

2008-01-01

347

The Sheffield hybrid fixator--a clinical and biomechanical review.  

PubMed

The Sheffield hybrid fixator (SHF) was developed to complement and extend the use of current monolateral fixation systems. Unlike other hybrid designs, it relies on rings for the diaphyseal as well as the metaphyseal support. Since it is an all ring system it may be used to cross joints and perform progressive deformity and contracture correction. Unlike the Ilizarov system only one ring is required at each level and diaphyseal transfixation is avoided. Initial biomechanical testing has demonstrated similar mechanical characteristics to an all wire Ilizarov fixator, however, increased shear motion was noted due to the stiffness asymmetry between the segments controlled by wires and screws. The first 100 cases were reviewed with good patient compliance and satisfactory results. Minor component problems were identified and corrected during this period and no significant complications occurred. The device is recommended for a wide range of complex trauma and limb reconstruction uses. PMID:11812472

Farrar, M; Yang, L; Saleh, M

2001-12-01

348

A natural compound (reuterin) produced by Lactobacillus reuteri for biological-tissue fixation  

Microsoft Academic Search

The study was undertaken to examine the degree of tissue fixation by reuterin, a natural compound produced by Lactobacillus reuteri, at distinct fixation conditions (pH, temperature, and fixative concentration). Additionally, the rate of tissue fixation by reuterin was investigated using glutaraldehyde as a control. It was found by the Fourier transformed infrared spectroscopy and nuclear magnetic resonance spectroscopy that both

Hsing-Wen Sung; Chiun-Nan Chen; Hsiang-Fa Liang; Min-Hao Hong

2003-01-01

349

Mandibular osteosynthesis by miniature screwed plates via a buccal approach.  

PubMed

The modified Michelet's (1973) technique of mandibular osteosynthesis, which consists of monocortical juxta-alveolar and sub-apical osteosynthesis, without compression and without inter-maxillary fixation, is described. This technique can be used in many types of mandibular fracture, single or multiple, associated or isolated, except in the case of a fracture of the condylar neck and in the presence of pre-existing infection. Infected fractures are treated by orthopaedic methods. Materials used (plates and screws) and particulars of the method have been tested by multi-disciplinary experimentation, particularly by anatomical verification and biomechanical studies. The ideal line of osteosynthesis is described. For the author, this technique is a routine treatment of any type of mandibular fracture. PMID:274501

Champy, M; Loddé, J P; Schmitt, R; Jaeger, J H; Muster, D

1978-02-01

350

Fracture of the L-4 vertebral body after use of a stand-alone interbody fusion device in degenerative spondylolisthesis for anterior L3-4 fixation.  

PubMed

Many studies attest to the excellent results achieved using anterior lumbar interbody fusion (ALIF) for degenerative spondylolisthesis. The purpose of this report is to document a rare instance of L-4 vertebral body fracture following use of a stand-alone interbody fusion device for L3-4 ALIF. The patient, a 55-year-old man, had suffered intractable pain of the back, right buttock, and left leg for several weeks. Initial radiographs showed Grade I degenerative spondylolisthesis, with instability in the sagittal plane (upon 15° rotation) and stenosis of central and both lateral recesses at the L3-4 level. Anterior lumbar interbody fusion of the affected vertebrae was subsequently conducted using a stand-alone cage/plate system. Postoperatively, the severity of spondylolisthesis diminished, with resolution of symptoms. However, the patient returned 2 months later with both leg weakness and back pain. Plain radiographs and CT indicated device failure due to anterior fracture of the L-4 vertebral body, and the spondylolisthesis had recurred. At this point, bilateral facetectomies were performed, with reduction/fixation of L3-4 by pedicle screws. Again, degenerative spondylolisthesis improved postsurgically and symptoms eased, with eventual healing of the vertebral body fracture. This report documents a rare instance of L-4 vertebral body fracture following use of a stand-alone device for ALIF at L3-4, likely as a consequence of angular instability in degenerative spondylolisthesis. Under such conditions, additional pedicle screw fixation is advised. PMID:24725181

Kwon, Yoon-Kwang; Jang, Ju-Hee; Lee, Choon-Dae; Lee, Sang-Ho

2014-06-01

351

[Torque measurement of self-threading bone screws. Test procedure for new surgical screws].  

PubMed

Different systems of self-cutting screws are tested by a measuring instrument to test the torsional strain. Modern methods of measuring techniques are applied to get results of the torsional force and the torque by screwing into the bones. To get a self-cutting screw system several methods of biomechanical properties must be applied. A variety of quality tests, of biomechanical screws, are used, before performing the operations, that flaws may be detected. PMID:2639546

Heinl, T; Neumayer, B

1989-12-01

352

Self-reinforced bioabsorbable versus metallic fixation systems for metacarpal and phalangeal fractures: a biomechanical study.  

PubMed

Bioabsorbable fixation devices offer a useful option to treat small bone fractures of the hand if the prerequisite of reliable and stable osteofixation is met. We compared the stabilities of various bioabsorbable fixation devices with metallic fixation devices by using an oblique osteotomy model in radial to ulnar orientation. The 1.5-mm, self-reinforced, poly-L-lactide (SR-PLLA) pins provided fixation rigidity comparable with 1.5-mm K-wires in dorsal and palmar apex bending, whereas in lateral apex bending and in torsion the rigidity was equal to that of 1.25-mm K-wires. The 2.0-mm, self-reinforced, poly-L/DL-lactide (SR-P(L/DL)LA) 70/30 screws provided rigidity comparable with that of 1.5-mm K-wires in all testing modes. The bioabsorbable plate considerably enhanced the bending stabilities of the fixation system, but a single interfragmentary screw provided only limited rotational rigidity. The results show that by using ultra-high strength self-reinforced implants adequate fixation stability for hand fracture fixation can be achieved. PMID:12239683

Waris, Eero; Ashammakhi, Nureddin; Raatikainen, Timo; Törmälä, Pertti; Santavirta, Seppo; Konttinen, Yrjö T

2002-09-01

353

[Minimally invasive fixation of a sacral bilateral fracture with lumbopelvic dissociation].  

PubMed

This case report describes our technique of percutaneous sacroiliac screw fixation of a bilateral sacral fracture with spinopelvic dissociation. It is based on the description of an iliosacroiliac bony corridor delimited by the following landmarks: the sacral ala in a superior-anterior direction, the first sacral foramen on both sides in an inferior-posterior direction, and the sacral channel posteriorly. The described operating method, which uses a 6.5-mm parallel drill sleeve, allows the safe and strictly transversal positioning of a 7.3-mm screw on each side with the threads interlocking. It provides a separate and fracture-adapted compression of the screws. The interlocking SI screw threads increase the pull-out strength. Operating time and radiation dose can be reduced significantly by this method. PMID:19305963

Mendel, T; Kuhn, P; Wohlrab, D; Brehme, K

2009-06-01

354

The role of reduction and internal fixation of Lisfranc fracture-dislocations: a systematic review of the literature  

PubMed Central

A systematic review of the literature was performed in order to evaluate the role of reduction and internal fixation in the management of Lisfranc joint fracture–dislocations. Articles were extracted from the Pubmed database and the retrieved reports were included in the study only if pre-specified eligibility criteria were fulfilled. Eleven articles were eligible for the final analysis, reporting data for the management of 257 patients. Injuries of the first three metatarsal rays were treated by closed reduction and internal fixation with screws in 16.3% of the patients, open reduction and internal fixation with screws in 66.5% and open reduction and internal fixation with Kirschner wires (K-wires) in 17.1% of the patients. The preferred method for the stabilisation of the fourth and fifth metatarsal rays was K-wires. Screw-related complications were common and were reported in 16.1% of the cases. The mean American Orthopaedic Foot and Ankle Society midfoot score was 78.1 points. Post-traumatic radiographic arthritis was reported in 49.6% of the patients, but only in 7.8% of them it was severe enough to warrant an arthrodesis. We conclude that open reduction and internal fixation of the first three metatarsal rays with screws is a reliable method for the management of Lisfranc injuries. This can be complemented by K-wires application in the fourth and fifth metatarsal rays if needed.

Stavlas, Panagiotis; Roberts, Craig S.; Xypnitos, Fragiskos N.

2010-01-01

355

Computer tomography assessment of pedicle screw placement in lumbar and sacral spine: comparison between free-hand and O-arm based navigation techniques.  

PubMed

Transpedicular screw fixation has been accepted worldwide since Harrington et al. first placed pedicle screws through the isthmus. In vivo and in vitro studies indicated that pedicle screw insertion accuracy could be significantly improved with image-assisted systems compared with conventional approaches. The O-arm is a new generation intraoperative imaging system designed without compromise to address the needs of a modern OR like no other system currently available. The aim of our study was to check the accuracy of O-arm based and S7-navigated pedicle screw implants in comparison to free-hand technique described by Roy-Camille at the lumbar and sacral spine using CT scans. The material of this study was divided into two groups, free-hand group (group I) (30 patients; 152 screws) and O-arm group (37 patients; 187 screws). The patients were operated upon from January to September 2009. Screw implantation was performed during PLIF or TLIF mainly for spondylolisthesis, osteochondritis and post-laminectomy syndrome. The accuracy rate in our work was 94.1% in the free-hand group compared to 99% in the O-arm navigated group. Thus it was concluded that free-hand technique will only be safe and accurate when it is in the hands of an experienced surgeon and the accuracy of screw placement with O-arm can reach 100%. PMID:21253780

Silbermann, J; Riese, F; Allam, Y; Reichert, T; Koeppert, H; Gutberlet, M

2011-06-01

356

Fixation of zygomatic and mandibular fractures with biodegradable plates  

PubMed Central

Context: In this prospective study, 13 randomly selected patients underwent treatment for zygomatic–complex fractures (2 site fractures) and mandibular fractures using 1.5 / 2 / 2.5-mm INION CPS biodegradable plates and screws. Aims: To assess the fixation of zygomatic-complex and mandibular fractures with biodegradable copolymer osteosynthesis system. Materials and Methods: In randomly selected 13 patients, zygomatic-complex and mandibular fractures were plated using resorbable plates and screws using Champy's principle. All the cases were evaluated clinically and radiologically for the type of fracture, need for the intermaxillary fixation (IMF) and its duration, duration of surgery, fixation at operation, state of reduction at operation, state of bone union after operation, anatomic reduction, paresthesia, occlusal discrepancies, soft tissue infection, immediate and late inflammatory reactions related to biodegradation process, and any need for the removal of the plates. Statistical Analysis Used: Descriptives, Frequencies, and Chi-square test were used. Results: In our study, the age group range was 5 to 55 years. Road traffic accidents accounted for the majority of patients six, (46.2%). Postoperative occlusal discrepancies were found in seven patients as mild to moderate, which resolved with IMF for 1-8 weeks. There were minimal complications seen and only as soft tissue infection. Conclusions: Use of biodegradable osteosynthesis system is a reliable alternative method for the fixation of zygomatic-complex and mandibular fractures. The biodegradable system still needs to be refined in material quality and handling to match the stability achieved with metal system. Biodegradable plates and screws is an ideal system for pediatric fractures with favorable outcome.

Degala, Saikrishna; Shetty, Sujeeth; Ramya, S

2013-01-01

357

A comparison of stress distributions for different surgical procedures, screw dimensions and orientations for a Temporomandibular joint implant.  

PubMed

Finite element analysis is a useful analytical tool for the design of biomedical implants. The aim of this study was to investigate the behavior of temporomandibular joint implants with multiple design variables of the screws used for fixation of the implant. A commercially available implant with full mandible was analyzed using a finite element software package. The effects of different design variables such as orientation, diameter and stem length of the screws on the stress distribution in bone for two different surgical procedures were investigated. Considering the microstrain in bone as a principal factor, the acceptable ranges for screw diameter and length were determined. Parallel orientation of the screws performed better from a stress point of view when compared to the zig-zag orientation. Sufficient contact between the implant collar and mandibular condyle was shown to reduce the peak stresses which may lead to long term success. The distance between screw holes in the parallel orientation was much closer when compared to the zig-zag orientation. However, the stresses in bone near the screw hole area for the parallel orientation were within acceptable limits. PMID:21816398

Chowdhury, Amit Roy; Kashi, Ajay; Saha, Subrata

2011-09-23

358

A new adhesive technique for internal fixation in midfacial surgery  

PubMed Central

Background The current surgical therapy of midfacial fractures involves internal fixation in which bone fragments are fixed in their anatomical positions with osteosynthesis plates and corresponding screws until bone healing is complete. This often causes new fractures to fragile bones while drilling pilot holes or trying to insert screws. The adhesive fixation of osteosynthesis plates using PMMA bone cement could offer a viable alternative for fixing the plates without screws. In order to achieve the adhesive bonding of bone cement to cortical bone in the viscerocranium, an amphiphilic bone bonding agent was created, analogous to the dentin bonding agents currently on the market. Methods The adhesive bonding strengths were measured using tension tests. For this, metal plates with 2.0 mm diameter screw holes were cemented with PMMA bone cement to cortical bovine bone samples from the femur diaphysis. The bone was conditioned with an amphiphilic bone bonding agent prior to cementing. The samples were stored for 1 to 42 days at 37 degrees C, either moist or completely submerged in an isotonic NaCl-solution, and then subjected to the tension tests. Results Without the bone bonding agent, the bonding strength was close to zero (0.2 MPa). Primary stability with bone bonding agent is considered to be at ca. 8 MPa. Moist storage over 42 days resulted in decreased adhesion forces of ca. 6 MPa. Wet storage resulted in relatively constant bonding strengths of ca. 8 MPa. Conclusion A new amphiphilic bone bonding agent was developed, which builds an optimizied interlayer between the hydrophilic bone surface and the hydrophobic PMMA bone cement and thus leads to adhesive bonding between them. Our in vitro investigations demonstrated the adhesive bonding of PMMA bone cement to cortical bone, which was also stable against hydrolysis. The newly developed adhesive fixing technique could be applied clinically when the fixation of osteosynthesis plates with screws is impossible. With the detected adhesion forces of ca. 6 to 8 MPa, it is assumed that the adhesive fixation system is able to secure bone fragments from the non-load bearing midfacial regions in their orthotopic positions until fracture consolidation is complete.

Endres, Kira; Marx, Rudolf; Tinschert, Joachim; Wirtz, Dieter Christian; Stoll, Christian; Riediger, Dieter; Smeets, Ralf

2008-01-01

359

Modeling flow, melting, solid conveying and global behavior in intermeshing counter-rotating twin screw extruders  

NASA Astrophysics Data System (ADS)

Intermeshing counter-rotating twin screw extruders are widely applied in polymer processing industry, especially in compounding and PVC profile processing. However, the design of this type of machines is generally based on experiences and error-and-try. In addition, most of the investigations on intermeshing counter-rotating twin screw extruders were made on the melt conveying region. There is a lack of adequate study on a complete extrusion process to this type of machines. In this study, models were developed to simulate the extrusion processes, including solid conveying, melting and metering, evaluate the performance of intermeshing counter-rotating twin screw extruders, and optimize the design of machines and operating conditions. Experiments were carried out on a laboratory modular intermeshing counter-rotating twin screw extruder to observe solid conveying, the melting process and the global behavior of this type of machine. The solid bed is formed in the solid conveying region. The inter-screw region plays a dominant role in the melting process. Based on our observations, models were developed to describe both the solid conveying and the melting process. Based on hydrodynamic lubrication theory, a melt conveying model was developed to characterize the pumping capacity of screw elements in intermeshing counter-rotating twin screw extruders. The effect of screw channel aspect ratio (screw channel depth/width) was incorporated into the melt conveying model to improve the prediction of screw pumping capacity. Calculations were made to investigate the effect of geometrical parameter on screw pumping capacity. Models of solid conveying, the melting process and melt conveying were integrated together and a global composite model was developed to characterize the whole intermeshing counter-rotating twin screw extrusion process. The global model is intended for both flood fed and metered starved fed conditions. This is the first composite model designed for this type of machines. Simulations and experiment results were compared and it was found that they match very well. This global model was further successfully developed into user-friendly software, which is used to design, test and optimize intermeshing counter-rotating twin screw extruders.

Jiang, Qibo

360

Effect of occipitocervical fusion with screw-rod system for upper cervical spine tumor  

PubMed Central

Background Craniospinal junction tumors are rare but severe lesions. Surgical stabilization has been established to be an ideal treatment for upper cervical tumor pathology. The purpose of this study was to evaluate the effect of a screw-rod system for occipitocervical fusion. Methods A total of 24 cases with C1 and C2 cervical tumor underwent occipitocervical fusion with Vertex screw-rod internal fixation from January 2005 to December 2012. Preoperative X-ray and MRI examinations were performed on all patients before the operation, after the operation, and during last follow-up. The JOA score was used to assess neurological function pre and postoperatively. Results All the patients were followed up for 6 to 42 months with an average of 24 months. The result of X-ray showed that bony fusion was successful in 18 patients at 3 months and 6 patients at 6 months of follow-ups. There was no deterioration of spinal cord injury. The JOA Scores of neurological function increased significantly. Conclusion The screw-rod system offers strong fixation and good fusion for occipitocervical fusion. It is an effective and reliable method for reconstruction of upper cervical spine tumor.

2014-01-01

361

Solar power units with screw expanders  

Microsoft Academic Search

A low-power solar electric generator based on a screw expander which drives an ac motor is presented. The choices of flat plate or concentrating Rankine or Brayton cycle, and an oil-injected screw expander motor in the development of the unit are examined, and the effects of Mediterranean and subtropical locations on plant performance are discussed. Results of solar engine performance

J. M. Merigoux; P. Pocard

1980-01-01

362

Effects of screw eccentricity on the initial stability of the acetabular cup in artificial foam bone of different qualities.  

PubMed

Acetabular cup loosening is one of the major failure models of total hip replacement (THR), which is mostly due to insufficient initial stability of the cup. Previous studies have demonstrated that cup stability is affected by the quality of the host bone and the surgical skill when inserting screws. The purpose of this study was to determine the effects on the initial stability of the acetabular cup of eccentric screws in bone of different qualities. In this study, hemispherical cups were fixed into bone specimens constructed from artificial foam with three elastic moduli using one to three screws. The effects of two types of screw eccentricity (offset and angular) on the stability of the acetabular cup were also evaluated. The experimental results indicate that in the presence of ideal screwing, the cup was stable in bone specimens constructed from foam with the highest elastic modulus. In addition, increasing the number of ideal screws enhanced the cup stability, especially in bone specimens constructed from soft foam. Moreover, the cup stability was most affected by offset eccentric screw(s) in the hard-foam bone specimens and by angular eccentric screw(s) in the soft-foam bone specimens. The reported results indicate that the presence of screw eccentricity affects the initial stability of the acetabular cup. Surgeons should keep this in mind when performing screw insertions in THR. However, care is necessary when translating these results to the intraoperative situation due to the experiments being conducted under laboratory conditions, and hence, future studies should attempt to replicate the results reported here in vivo. PMID:19995362

Hsu, Jui-Ting; Lin, Dan-Jae

2010-01-01

363

Maxillary expansion with the memory screw: a preliminary investigation  

PubMed Central

Objective The purpose of this study was to investigate the effects of a newly developed rapid maxillary expansion screw-the memory screw-over 6 months. Methods Five subjects, aged between 11.7 and 13.75 years, were enrolled in this study. All subjects underwent placement of a maxillary expansion appliance containing superelastic nickel-titanium open-coil springs in its screw bed. The parents of the patients and/or the patients themselves were instructed to activate the expansion screw by 2 quarter-turns 3 times a day (morning, midday, and evening; 6 quarter-turns a day). The mean expansion period was 7.52 ± 1.04 days. Dentoskeletal effects of the procedure, including dentoalveolar inclination, were evaluated. Measurements of all the parameters were repeated after 6 months of retention in order to check for relapse. Results Sella-Nasion-A point (SNA) and Sella-Nasion/Gonion-Menton angles increased, and Sella-Nasion-B point (SNB) angle decreased in all the subjects during the expansion phase. However, they approximated to the initial values at the end of 6 months. On the other hand, the increments in maxillary apical base (Mxr-Mxl) and intermolar widths was quite stable. As expected, some amount of dentoalveolar tipping was observed. Conclusions The newly developed memory expansion screw offers advantages of both rapid and slow expansion procedures. It widens the midpalatal suture and expands the maxilla with relatively lighter forces and within a short time. In addition, the resultant increments in the maxillary apical base and intermolar width remained quite stable even after 6 months of retention.

Halicioglu, Koray; Kiki, Ali

2012-01-01

364

Evaluation of unilateral cage-instrumented fixation for lumbar spine  

PubMed Central

Background To investigate how unilateral cage-instrumented posterior lumbar interbody fusion (PLIF) affects the three-dimensional flexibility in degenerative disc disease by comparing the biomechanical characteristics of unilateral and bilateral cage-instrumented PLIF. Methods Twelve motion segments in sheep lumbar spine specimens were tested for flexion, extension, axial rotation, and lateral bending by nondestructive flexibility test method using a nonconstrained testing apparatus. The specimens were divided into two equal groups. Group 1 received unilateral procedures while group 2 received bilateral procedures. Laminectomy, facectomy, discectomy, cage insertion and transpedicle screw insertion were performed sequentially after testing the intact status. Changes in range of motion (ROM) and neutral zone (NZ) were compared between unilateral and bilateral cage-instrumented PLIF. Results Both ROM and NZ, unilateral cage-instrumented PLIF and bilateral cage-instrumented PLIF, transpedicle screw insertion procedure did not revealed a significant difference between flexion-extension, lateral bending and axial rotation direction except the ROM in the axial rotation. The bilateral group's ROM (-1.7 ± 0. 8) of axial rotation was decreased significantly after transpedicle screw insertion procedure in comparison with the unilateral group (-0.2 ± 0.1). In the unilateral cage-instrumented PLIF group, the transpedicle screw insertion procedure did not demonstrate a significant difference between right and left side in the lateral bending and axial rotation direction. Conclusions Based on the results of this study, unilateral cage-instrumented PLIF and bilateral cage-instrumented PLIF have similar stability after transpedicle screw fixation in the sheep spine model. The unilateral approach can substantially reduce exposure requirements. It also offers the biomechanics advantage of construction using anterior column support combined with pedicle screws just as the bilateral cage-instrumented group. The unpleasant effect of couple motion resulting from inherent asymmetry was absent in the unilateral group.

2010-01-01

365

Fixation: A Bibliography.  

ERIC Educational Resources Information Center

Fixation and regression were considered complementary by Freud. You tend to regress to a point of fixation. They are both opposed to progression. In the general area, Anna Freud has written (The Ego and the Mechanisms of Defence. London: Hogarth and the Psycho-Analytic Institute, 1937), Sears has evaluated (Survey of Objective Studies of…

Pedrini, D. T.; Pedrini, Bonnie C.

366

Retrograde intramedullary nails with distal screws locked to the nail have higher fatigue strength than locking plates in the treatment of supracondylar femoral fractures: A cadaver-based laboratory investigation.  

PubMed

We investigated a new intramedullary locking nail that allows the distal interlocking screws to be locked to the nail. We compared fixation using this new implant with fixation using either a conventional nail or a locking plate in a laboratory simulation of an osteoporotic fracture of the distal femur. A total of 15 human cadaver femora were used to simulate an AO 33-A3 fracture pattern. Paired specimens compared fixation using either a locking or non-locking retrograde nail, and using either a locking retrograde nail or a locking plate. The constructs underwent cyclical loading to simulate single-leg stance up to 125,000 cycles. Axial and torsional stiffness and displacement, cycles to failure and modes of failure were recorded for each specimen. When compared with locking plate constructs, locking nail constructs had significantly longer mean fatigue life (75,800 cycles (SD 33,900) vs 12,800 cycles (SD 6100); p = 0.007) and mean axial stiffness (220 N/mm (SD 80) vs 70 N/mm (SD 18); p = 0.005), but lower mean torsional stiffness (2.5 Nm/° (SD 0.9) vs 5.1 Nm/° (SD 1.5); p = 0.008). In addition, in the nail group the mode of failure was either cut-out of the distal screws or breakage of nails, and in the locking plate group breakage of the plate was always the mode of failure. Locking nail constructs had significantly longer mean fatigue life than non-locking nail constructs (78,900 cycles (SD 25,600) vs 52,400 cycles (SD 22,500); p = 0.04). The new locking retrograde femoral nail showed better stiffness and fatigue life than locking plates, and superior fatigue life to non-locking nails, which may be advantageous in elderly patients. PMID:24395321

Pekmezci, M; McDonald, E; Buckley, J; Kandemir, U

2014-01-01

367

Modeling flow, melting, solid conveying and global behavior in intermeshing counter-rotating twin screw extruders  

Microsoft Academic Search

Intermeshing counter-rotating twin screw extruders are widely applied in polymer processing industry, especially in compounding and PVC profile processing. However, the design of this type of machines is generally based on experiences and error-and-try. In addition, most of the investigations on intermeshing counter-rotating twin screw extruders were made on the melt conveying region. There is a lack of adequate study

Qibo Jiang

2008-01-01

368

[Experience with 208 "screw-in" type pacemaker leads with particular reference to atrial positioning (author's transl)].  

PubMed

In 190 patients, 208 "screw-in" type pacemaker leads were implanted; 147 in the right ventricle and 61 in the right atrium. There was no significant difference in the time required for atrial (54.7 +/- 19 min) or ventricular fixation (56.0 +/- 25 min). Similarly, fluoroscopy times for both atrial (6.3 +/- 4 min) and ventricular positioning (8.1 +/- 6 min) were equivalent. In the subsequent follow-up period ranging from one to 23 months, only one dislocation of a "screw-in" type atrial lead was seen, and that in a patient with "twiddler syndrome". Otherwise, in patients in whom the lead was securely implanted, no evidence of dislocation has been observed. In one patient "under-sensing" developed subsequent to repositioning for exit-block. In this patient population, the use of "screw-in" type electrodes, in particular through facilitation of atrial positioning, has substantially lessened the rate of pacemaker complications. PMID:7319450

Machraoui, A; Schött, D; Ong, T S; Straub, H; Jaedicke, W; Barmeyer, J

1981-12-01

369

Arthrodesis of the first metatarsocuneiform joint: a comparative cadaveric study of external and internal fixation.  

PubMed

Arthrodesis of the first metatarsocuneiform joint for the treatment of severe hallux abductovalgus with or without hypermobility of the first ray has gained popularity in recent years. The purpose of the current study was to compare the strength of external fixation to internal fixation for arthrodesis of the first metatarsocuneiform joint in a cadaveric model. Ten pairs of fresh frozen lower extremity cadaver specimens were used, and randomly assigned to fixation at the first metatarsocuneiform joint with crossed cannulated screws or a monorail uniplanar external fixator. Test specimens were then loaded to failure, which was defined as 3 mm or more of displacement at the arthrodesis site. Because of complications encountered during testing, 4 pairs of specimens were excluded from the final results. In the remaining 12 specimens (6 pairs of cadaver limbs), the mean maximal load to failure was 2300.02 +/- 711.86 N for the external fixator and 1666.38 +/- 1072.75 N for the internal fixation construct, and although this difference was not statistically significant (P = .2557), it was likely to have been clinically significant since approximately 27.55% more force was required to disrupt the external fixation construct in comparison with the internal fixation construct. Given these findings, further research into the mechanical and clinical properties of internal and external fixation for first metatarsocuneiform joint arthrodesis is warranted. Level of Clinical Evidence: 5. PMID:19110155

Webb, Brad; Nute, Michael; Wilson, Sean; Thomas, James; Van Gompel, Joshua; Thompson, Kevin

2009-01-01

370

Dynamic Hip Screw for the Treatment of Femoral Neck Fractures: A Prospective Study with 96 Patients  

PubMed Central

Objectives. To study the correlation between avascular necrosis and the demographics, time elapsed from fracture to surgery, quality of reduction, Garden classification, and the position of the screw following use of the dynamic hip screw (DHS) in the treatment of subcapital neck fractures. Methods. A prospective study of 96 patients with subcapital neck fractures was carried out in a faculty hospital. Patients underwent surgery with closed reduction and internal fixation with DHS. Results. There were 58% male and 42% female patients, with a mean age of 53 years (+/?14). In terms of Garden classification, 60% were Garden IV, 26% were Garden III, and 14% were Garden II. Nonunion was observed in three cases (3%) and was treated with valgus intertrochanteric osteotomy, in all cases leading to successful healing. Avascular necrosis was observed in 16% of patients. The positioning of the screw into the femoral head showed a significant correlation with necrosis. Conclusions. The incidence of necrosis in patients under the age of 50 years is twice as high as that in older patients. Displacement is a predictive factor regarding osteonecrosis and is associated with a high and anterior position of the screw in the femoral head. Level II of evidence. Study Type: therapeutic study.

Schwartsmann, Carlos Roberto; Jacobus, Lucas Senger; Spinelli, Leandro de Freitas; Boschin, Leonardo Carbonera; Goncalves, Ramiro Zilles; Yepez, Anthony Kerbes; Barreto, Rodrigo Py Goncalves; Silva, Marcelo Faria

2014-01-01

371

Dynamic hip screw for the treatment of femoral neck fractures: a prospective study with 96 patients.  

PubMed

Objectives. To study the correlation between avascular necrosis and the demographics, time elapsed from fracture to surgery, quality of reduction, Garden classification, and the position of the screw following use of the dynamic hip screw (DHS) in the treatment of subcapital neck fractures. Methods. A prospective study of 96 patients with subcapital neck fractures was carried out in a faculty hospital. Patients underwent surgery with closed reduction and internal fixation with DHS. Results. There were 58% male and 42% female patients, with a mean age of 53 years (+/-14). In terms of Garden classification, 60% were Garden IV, 26% were Garden III, and 14% were Garden II. Nonunion was observed in three cases (3%) and was treated with valgus intertrochanteric osteotomy, in all cases leading to successful healing. Avascular necrosis was observed in 16% of patients. The positioning of the screw into the femoral head showed a significant correlation with necrosis. Conclusions. The incidence of necrosis in patients under the age of 50 years is twice as high as that in older patients. Displacement is a predictive factor regarding osteonecrosis and is associated with a high and anterior position of the screw in the femoral head. Level II of evidence. Study Type: therapeutic study. PMID:24967124

Schwartsmann, Carlos Roberto; Jacobus, Lucas Senger; Spinelli, Leandro de Freitas; Boschin, Leonardo Carbonera; Gonçalves, Ramiro Zilles; Yépez, Anthony Kerbes; Barreto, Rodrigo Py Gonçalves; Silva, Marcelo Faria

2014-01-01

372

Outcome of the Dynamic Helical Hip Screw System for Intertrochanteric Hip Fractures in the Elderly Patients  

PubMed Central

Introduction: The dynamic helical hip system (DHHS; Synthes, Paoli, Pennsylvania) differs from the standard dynamic sliding hip screw (SHS) in that in preparing for its insertion, reaming of the femoral head is not performed, thereby preserving bone stock. It also requires less torque for insertion of the helical screw. The associated plate has locking options to allow locking screw fixation in the femoral shaft, thereby decreasing the chance of the plate pulling off. While biomechanical studies have shown improved resistance to cutout and increased rotational stability of the femoral head fragment when compared with traditional hip lag screws, there is limited information on clinical outcome of the implant available in the literature. Methods: We report a single surgeon series of 87 patients who were treated for their per-trochanteric hip fractures with this implant to evaluate their clinical outcome and compare it with a cohort of 344 patients who were treated with the standard SHS. All data were prospectively collected, most as part of a structured Geriatric Fracture Care Program. Results: The 2 groups were similar demographically, and medically, with similar rates of in-hospital complications and implant failure. Failure in the DHHS group was attributable to use of the implant outside its indications and repeated fall of the patient. Conclusion: This limited case series showed that the DHHS outcomes are comparable with that of the SHS. Whether there is any benefit to its use will require larger, prospective randomized controlled trials.

O'Malley, Natasha T.; Deeb, Andrew-Paul; Bingham, Karilee W.; Kates, Stephen L.

2012-01-01

373

New innovations in craniomaxillofacial fixation: the 2.0 lock system.  

PubMed

Rigid internal fixation with plates and screws is now standard for the treatment of fractures, osteotomies and reconstruction of the craniomaxillofacial skeleton. The latest innovations are self-drilling, self-tapping screws and locking miniplates. These screws offer the prospect of less instrumentation and faster application. Preclinical testing has shown them to be substantially more retentive in cancellous bone, a significant advance in cancellous block bone grafting. Locking 2.0 miniplates utilize double threaded screws which both lock to the bone and the plate creating a mini-internal fixator. This results in a more rigid construct with less distortion of the fracture or osteotomy, screws which do not loosen and less interference with bone circulation since the plate is not pressed tightly against the bone. Locking miniplates are designed for midface application in the repair of fractures, osteotomies and defects. Three configurations in a variety of shapes and lengths are available for mandibular surgery. The thinner and medium varieties are useful in transoral plating of fractures utilizing the Champy technique. The heavier, longer variety are used in unilateral edentulous fractures in the symphysis and parasymphysis as well as an aid to tumor resection and reconstruction with both free and vascularized grafts. They are not designed to replace the heavier 2.4 locking reconstruction plates designed for complex fractures or extensive reconstructions. PMID:12862364

Alpert, Brian; Gutwald, Rolf; Schmelzeisen, Rainer

2003-06-01

374

Mechanical analysis of femoral neck fracture fixation in synthetic bone  

PubMed Central

OBJECTIVE: To analyze statistically results obtained between biomechanical assays on fixation of femoral neck fracture type Pauwels III, on synthetic bone, using 7.5 mm non parallel cannulated screws and control group. METHODS: Ten synthetic bones from a national brand were used. Test group: fixation of 70(o) tilt femoral neck osteotomy was performed using three 7.5 mm non parallel cannulated screws. We analyzed the resistance of this fixation with 5 mm of displacement, and rotational deviation (phase 1) and with 10 mm offset (phase 2). Control group: the models were tested in their integrity until the femoral neck fracture occurred. RESULTS: the values of the test group in phase 1, in sample 1-5 had a mean of 517N and SD = 96N. Rotational deviations showed a mean of 3.79° e SD = 2. 03°. In phase 2, mean was 649N and SD = 94N. The values of the maximum load in the control group were: 1544N, 1110N, 1359N, 1194N, 1437N; respectively. Statistical analysis between the groups showed a statistically significant lower value in the test group. CONCLUSION: the analysis of mechanical resistance between the groups has determined statistically significant value for the test group. Level of Evidence III, Case-control Study.

Freitas, Anderson; Azevedo, Bruna Alves Soares; de Souza, Roberto Rodrigues; da Costa, Helio Ismael; Maciel, Rafael Almeida; Souto, Diogo Ranier de Macedo

2014-01-01

375

Improved extraction torque of hydroxyapatite-coated pedicle screws.  

PubMed

Loosening of the screws is a problem in instrumentation with pedicle screws. Coating with hydroxyapatite improves the holding characteristics for metal implants, but the possible effects on the anchorage of pedicle screws have not been described. In this study, seven patients were operated on with spinal instrumentation using four stainless steel pedicle screws. Hydroxyapatite-coated screws were used in either the upper or the lower of the instrumented levels. The insertion torque was measured. In four cases the screws were removed after 10-22 months and the extraction torque was measured. The mean insertion torque was found to be significantly greater in the hydroxyapatite-coated screws (107 Ncm) than in the standard screws (76 Ncm). In three cases, the extraction torque for the hydroxyapatite-coated screws exceeded the range for the torque wrench (600 Ncm), while the conventional screws were loose (< 5 Ncm). In one case, the extraction torque was 475 and 550 Ncm for the coated screws, and 5 and 25 Ncm for the conventional screws. The difference in extraction torque was significant. Hydroxyapatite coating was shown to have improved the purchase of pedicle screws very effectively. By using fully coated screws, as in the present study, extraction was extremely difficult compared to extraction of conventional stainless steel screws, which were regularly loose. By reducing the area of the screws that is coated, it may be possible to achieve an enhanced purchase while extraction will be easier when compared to fully coated screws. PMID:11189923

Sandén, B; Olerud, C; Johansson, C; Larsson, S

2000-12-01

376

External fixation of open humerus fractures.  

PubMed

Fifteen patients with open shaft of humerus fractures were treated with a monolateral external fixator. Nine patients presented with nerve palsies. Two radial nerves were disrupted and required grafting. Of the seven others, six spontaneously recovered and one brachial plexus partially improved. All fractures healed. The average duration of external fixation was 21 weeks. Four patients required additional procedures prior to healing (external fixator reapplication-2, plating and bone grafting-2). Two of these four experienced breakage of 4.5 mm external fixation pins. Eight patients developed pin tract infections, which all resolved with local care and antibiotics. Thirteen patients were contacted at an average of 63 months after injury. Eleven reported they were satisfied with their result, nine had no functional limits, and eight reported no pain. PMID:10847515

Marsh, J L; Mahoney, C R; Steinbronn, D