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1

Impact of posterior tibial nail malpositioning on iatrogenic injuries by distal medio-lateral interlocking screws. A cadaveric study on plastinated specimens.  

PubMed

In intramedullary tibial nailing, multi-planar locking makes stabilization of proximal and distal metaphyseal fractures possible. A known complication in intramedullary nailing of the tibia is iatrogenic injury to neuro-vascular structures caused by the insertion of locking screws. As shown in previous studies, the distal positioning of the nail is important, as it determines the course of the locking bolts. The goal of the present study was to display the consequences of posterior nail malpositioning with respect to the safety of the distal medio-lateral locking screws and the available options. Human cadaveric legs were plastinated according to the sequential plastination technique after intramedullary nailing of the tibia and were then cut transversely. The tibial nails were placed centrally or posteriorly. Macroscopic analysis showed a distinct drawback of posterior nail positioning, with diminished options for the placement of the locking screws and thereby a risk of damaging the anterior and posterior neuro-vascular bundles by distal medio-lateral locking screws. PMID:23409576

Wegmann, Kilian; Burkhart, Klaus Josef; Buhl, Jörg; Gausepohl, Thomas; Koebke, Jürgen; Müller, Lars Peter

2012-12-01

2

Fatigue strength of common tibial intramedullary nail distal locking screws  

PubMed Central

Background Premature failure of either the nail and/or locking screws with unstable fracture patterns may lead to angulation, shortening, malunion, and IM nail migration. Up to thirty percent of all unreamed nail locking screws can break after initial weight bearing is allowed at 8–10 weeks if union has not occurred. The primary problem this presents is hardware removal during revision surgery. The purposes of our study was to evaluate the relative fatigue resistance of distal locking screws and bolts from representative manufacturers of tibial IM nail systems, and develop a relative risk assessment of screws and materials used. Evaluations included quantitative and qualitative measures of the relative performance of these screws. Methods Fatigue tests were conducted to simulate a comminuted fracture that was treated by IM nailing assuming that all load was carried by the screws. Each screw type was tested ten times in a single screw configuration. One screw type was tested an additional ten times in a two-screw parallel configuration. Fatigue tests were performed using a servohydraulic materials testing system and custom fixturing that simulated screws placed in the distal region of an appropriately sized tibial IM nail. Fatigue loads were estimated based on a seventy-five kilogram individual at full weight bearing. The test duration was one million cycles (roughly one year), or screw fracture, whichever occurred first. Failure analysis of a representative sample of titanium alloy and stainless steel screws included scanning electron microscopy (SEM) and quantitative metallography. Results The average fatigue life of a single screw with a diameter of 4.0 mm was 1200 cycles, which would correspond roughly to half a day of full weight bearing. Single screws with a diameter of 4.5 mm or larger have approximately a 50 percent probability of withstanding a week of weight bearing, whereas a single 5.0 mm diameter screw has greater than 90 percent probability of withstanding more than a week of weight bearing. If two small diameter screws are used, our tests showed that the probability of withstanding a week of weight bearing increases from zero to about 20 percent, which is similar to having a single 4.5 mm diameter screw providing fixation. Conclusion Our results show that selecting the system that uses the largest distal locking screws would offer the best fatigue resistance for an unstable fracture pattern subjected to full weight bearing. Furthermore, using multiple screws will substantially reduce the risk of premature hardware failure. PMID:19371438

Griffin, Lanny V; Harris, Robert M; Zubak, Joseph J

2009-01-01

3

Biomechanical Comparison of Osteoporotic Distal Radius Fractures Fixed by Distal Locking Screws with Different Length  

PubMed Central

Objectives To evaluate the postoperative stability of osteoporotic distal radius fractures fixed with distal locking screws with different length. Methods A comminuted extra-articular dorsally unstable distal radius fracture, treated with volar locking plate system, was created. The 18 specimens were randomized into 3 groups based on distal locked screws with different length: Group A had unicortical screws with 50% length to the dorsal cortex. Group B had unicortical screws with 75% length to the dorsal cortex. Group C had bicortical screws. Axial compression and bending loads were imposed on the models before and after cycling testing as well as load to clinical and catastrophic failure. Results Minimum change in stiffness was observed before and after fatigue for all groups. The final stiffness to bending forces was statistically similar in all groups, but stiffness to axial compression was statistically significant different: Group A approached significance with respect to groups B and C (P?=?0.017, 0.009), whereas stiffness in group B and C was statistically similar (P?=?0.93). Load to clinical failure was significantly less for group A (456.54±78.59 N) compared with groups B (580.24±73.85 N) and C (591.07±38.40 N). Load to catastrophic failure was statistically similar between groups, but mean values for Group A were 18% less than means for Group C. Conclusions The volar locking plate system fixed with unicortical locking screws with at least 75% length not only produced early stability for osteoporotic distal radius fractures, but also avoided extensor tendon complications due to dorsal screw protrusion. PMID:25080094

Liu, Xiong; Wu, Wei-dong; Fang, Ya-feng; Zhang, Mei-chao; Huang, Wen-hua

2014-01-01

4

Olecranon anatomy: Use of a novel proximal interlocking screw for intramedullary nailing, a cadaver study  

PubMed Central

AIM: To define the optimum safe angle of use for an eccentrically aligned proximal interlocking screw (PIS) for intramedullary nailing (IMN). METHODS: Thirty-six dry cadaver ulnas were split into two equal pieces sagitally. The following points were identified for each ulna: the deepest point of the incisura olecrani (A), the point where perpendicular lines from A and the ideal IMN entry point (D) are intersected (C) and a point at 3.5 mm (2 mm safety distance from articular surface + 1.5 mm radius of PIS) posterior from point A (B). We calculated the angle of screws inserted from point D through to point B in relation to D-C and B-C. In addition, an eccentrically aligned screw was inserted at a standard 20° through the anterior cortex of the ulna in each bone and the articular surface was observed macroscopically for any damage. RESULTS: The mean A-C distance was 9.6 mm (mean ± SD, 9.600 ± 0.763 mm), A-B distance was 3.5 mm, C-D distance was 12.500 mm (12.500 ± 1.371 mm) and the mean angle was 25.9° (25.9° ± 2.0°). Lack of articular damage was confirmed macroscopically in all bones after the 20.0° eccentrically aligned screws were inserted. Intramedullary nail fixation systems have well known biological and biomechanical advantages for osteosynthesis. However, as well as these well-known advantages, IMN fixation of the ulna has some limitations. Some important limitations are related to the proximal interlocking of the ulna nail. The location of the PIS itself limits the indications for which intramedullary systems can be selected as an implant for the ulna. The new PIS design, where the PIS is aligned 20°eccentrically to the nail body, allows fixing of fractures even at the level of the olecranon without disturbing the joint. It also allows the eccentrically aligned screw to be inserted in any direction except through the proximal radio-ulnar joint. Taking into consideration our results, we now use a 20° eccentrically aligned PIS for all ulnas. In our results, the angle required to insert the PIS was less than 20° for only one bone. However, 0.7° difference corresponds to placement of the screw only 0.2 mm closer to the articular surface. As we assume 2.0 mm to be a safe distance, a placement of the screw 0.2 mm closer to the articular surface may not produce any clinical symptoms. CONCLUSION: The new PIS may give us the opportunity to interlock IMN without articular damage and confirmation by fluoroscopy if the nail is manufactured with a PIS aligned at a 20.0° fixed angle in relation to the IMN. PMID:23878781

Küçükdurmaz, Fatih; Saglam, Necdet; A??r, ?smail; Sen, Cengiz; Akp?nar, Fuat

2013-01-01

5

Fatigue strength of common tibial intramedullary nail distal locking screws  

Microsoft Academic Search

BACKGROUND: Premature failure of either the nail and\\/or locking screws with unstable fracture patterns may lead to angulation, shortening, malunion, and IM nail migration. Up to thirty percent of all unreamed nail locking screws can break after initial weight bearing is allowed at 8–10 weeks if union has not occurred. The primary problem this presents is hardware removal during revision

Lanny V. Griffin; Robert M Harris; Joseph J Zubak

2009-01-01

6

Comparison of bioabsorbable interference screws and posts for distal fixation in anterior cruciate ligament reconstruction  

Microsoft Academic Search

Comparison of the results of bioabsorbable interference screws and posts for hamstring graft distal fixation in ACL reconstructions\\u000a are presented. The results of 20 patients with bioabsorbable screws were compared to 22 patients with posts. The assessement\\u000a was based on Lysholm-Gillquist and Marshall scores and the KT-1000 device. In the study group the points gained were 38.9\\u000a in the Lysholm-Gillquist

Krzysztof Gaw?da; Jacek Walawski; Robert W?g?owski; Wojciech Krzy?anowski

2009-01-01

7

The Effects of Screw Length on Stability of Simulated Osteoporotic Distal Radius Fractures Fixed with Volar Locking Plates  

PubMed Central

Purpose Volar plating for distal radius fractures has caused extensor tendon ruptures secondary to dorsal screw prominence. This study was designed to determine the biomechanical impact of placing unicortical distal locking screws and pegs in an extra-articular fracture model. Methods Volar-locking distal radius plates were applied to 30 osteoporotic distal radius models. Radii were divided into 5 groups based on distal locking fixation: bicortical locked screws, 3 lengths of unicortical locked screws (abutting the dorsal cortex [full length], 75% length, and 50% length to dorsal cortex), and unicortical locked pegs. Distal radius osteotomy simulated a dorsally comminuted, extra-articular, fracture. Each constructs stiffness was determined under physiologic loads (axial compression, dorsal bending volar bending) before and after 1000 cycles of axial conditioning and prior to axial loading to failure (2mm of displacement) and subsequent catastrophic failure. Results Cyclic conditioning did not alter constructs stiffness. Stiffness to volar bending and dorsal bending forces were similar between groups. Final stiffness(N/mm) under axial load was statistically equivalent for all groups: bicortical screws(230), full-length unicortical screws(227), 75% length unicortical screws(226), 50% length unicortical screws(187), unicortical pegs(226). Force(N) at 2 mm displacement was significantly less for 50% length unicortical screws(311) compared to bicortical screws(460), full-length unicortical screws(464), 75% length unicortical screws(400), and unicortical pegs(356). Force(N) to catastrophic fracture was statistically equivalent between groups but mean values for pegs(749) and 50% length unicortical(702) screws were 16-21% less than means for bicortical(892), full-length unicortical(860), and 75% length(894) unicortical constructs. Discussion Locked unicortical distal screws of at least 75% length produce construct stiffness similar to bicortical fixation. Unicortical distal fixation for extra-articular distal radius fractures should be entertained to avoid extensor tendon injury since it does not appear to compromise initial fixation. Clinical Relevance Biomechanical comparison of distal fixation techniques during volar locked plating for distal radius fracture. PMID:22305729

Wall, Lindley B.; Brodt, Michael D.; Silva, Matthew J.; Boyer, Martin I.; Calfee, Ryan P.

2013-01-01

8

Comparison of bioabsorbable interference screws and posts for distal fixation in anterior cruciate ligament reconstruction  

PubMed Central

Comparison of the results of bioabsorbable interference screws and posts for hamstring graft distal fixation in ACL reconstructions are presented. The results of 20 patients with bioabsorbable screws were compared to 22 patients with posts. The assessement was based on Lysholm-Gillquist and Marshall scores and the KT-1000 device. In the study group the points gained were 38.9 in the Lysholm-Gillquist and 12.89 in the Marshall scale. The average KT-1000 difference was 2.46 mm. In the control group the points gained were 32.93 in the Lysholm-Gillquist and 11.47 in the Marshall scale. The average KT-1000 difference was 2.5 mm. There were 14 patients in the study group with interference screw problems; in 2 the implants were removed. (1) There are no differences in outcome using bioabsorbable interference screws and posts for distal fixation of hamstring ACL grafts. (2) The lack of bioabsorbtion with poly L-lactide interference screws is frequent and causes problems. PMID:18064457

Walawski, Jacek; W?g?owski, Robert; Krzy?anowski, Wojciech

2007-01-01

9

Distal tibial physeal bridge: a complication from a tension band plate and screw construct. Report of a case.  

PubMed

We report on a case of a tension band plate and screw construct (Eight Plate) used over the anterior distal tibia in an 9-year-old girl in an attempt to induce recurvatum of the ankle joint to correct a recalcitrant equinus deformity. With growth of the distal tibial physis, the epiphyseal screw was drawn through the physis into the distal tibial metaphysis, resulting in the creation of a transphyseal bony bar. Caution should be exercised when attempting temporary hemiepiphyseodesis using a plate and screw construct in small epiphyses or in an osteopenic bone. PMID:22158054

Oda, Jon E; Thacker, Mihir M

2013-05-01

10

Osteosynthesis of distal radial fractures with a volar locking screw plate system  

Microsoft Academic Search

We developed a locking screw plate system for the stabilisation of distal radial fractures, which can be inserted through a standard volar approach and in which the locking mechanism allows early post-operative mobilisation. Forty-nine patients with 50 fractures underwent surgical treatment; 66% were type C fractures. The mean follow-up was 26 months. According to the scores of Gartland and Werley

H. Drobetz; E. Kutscha-Lissberg

2003-01-01

11

Validations of Computer-Assisted Orthopaedic Surgical System for insertion of distal locking screws for intramedullary nails  

Microsoft Academic Search

The difficult part of the intramedullary (IM) nailing operation of long bone is to insert the distal locking screws. The current technique to insert these screws uses numerous fluoroscopic images and depends on skills and expertise of the surgeon. A Computer-Assisted Orthopaedic Surgical System (CAOSS) has been developed collaboratively by the University of Hull and the East Yorkshire Hospitals NHS

Sabur Malek; Roger Phillips; Amr Mohsen; Warren J. Viant; Mike Bielby; Kevin Sherman

2004-01-01

12

Titanium integration with bone, welding, and screw head destruction complicating hardware removal of the distal radius: report of 2 cases.  

PubMed

Increasingly, surgeons treat distal radius fractures with locking plate systems. Recent case reports have focused on technical insertion errors resulting in removal difficulties: poor drilling orientation or cross-threading, destruction of the screw head, and filling of the screw recess with tissue. We report 2 complications of titanium locked plate removal secondary to in vivo reactions including titanium integration with bone and mechanical binding between the titanium screw and plate. We clarify and discuss terminology relevant to implant removal, including cold-welding, galling, fretting, and anodization. Even with optimal technique, in situ reactions can complicate titanium implant removal. PMID:22652178

Van Nortwick, Sara S; Yao, Jeffrey; Ladd, Amy L

2012-07-01

13

[Evaluation of AO kit screw fixation of medial condyle and epicondyle distal humeral epiphyseal fractures in children].  

PubMed

In the Pediatric Surgery Department of the Voivodeship Hospital in Koszalin the use of screw fixation claims to be the method od choice for treating the fractures of medial epicondyle and condyles of the distal humeral bone epiphysis in children, thus challenging Kirschner's wire fixation being commonly applied in these traumas, and in consequence making it necessary to compare the results obtained after resorting to each of these methods. The accomplished comparative study covered the total of 101 persons, aged from 5 to 28 years, over the period from 1 to 15 years (mean 6 years) after trauma, treated due to the above-mentioned injuries in the years 1976-1990, at this Department (86 persons), and in the years 1980-1990 at the Pediatric Surgery Clinic of the Pomeranian Medical Academy in Szczecin (15 persons) exclusively by means of Kirschner's wire fixation. In 64 patients screw fixation was implanted, and in 37-Kirschner's wire. The studied material was divided into 4 subgroups (Tab. 1) comprising respectively: 41 persons (subgroup A) after past fracture of medial epicondyle treated by screw fixation; 26 persons (subgroup A1) with past medial epicondyle fracture treated by Kirschner's wire fixation: 23 persons with past condyle fracture treated by screw fixation (subgroup B) and 11 persons after condyle fracture treated by Kirschner's wire fixation (subgroup B1). Three control groups were set up: control group I, showed normal reference values, represented the assessments of healthy ulnar joints contrasting with the previously inflicted injury in 101 persons of the studied group. The control group II, concerning the physical examinations, incorporated 43 persons burdened neither by past trauma, nor by any other lesions of the ulnar joints, randomly selected: 23 children, 12 under the care of their parents, and 11 persons of juvenile age, registered with the pediatric surgery or rehabilitation consulting centres in Koszalin. Control group III, concerned with correct radiologic measurements included 45 persons randomly selected, aged from 5 to 27 years in whom radiograms of their ulnar joints were made on indications not involving the trauma of the joint. The clinical evaluation took into account the anamnesis data, assessment of the ulnar joint shape, appearance of the postoperative scar, innervation status within the ulnar nerve range, measurements of the length of arm, its circumference, flexion and extension movement (with analysis of the range of movement) value of the angle of the arm axis deviation in relation to forearm axis, as well as muscle power. The radiographic evaluation encompassed the measurements of angles: humeral, ulnar, physiological valgity as well as diaphysio-epiphysial one, and moreover, the evaluation of the symphysis quality, outlines of distal epiphysis of the humeral bone and its bony structure. The mentioned parameters of the clinical evaluation, two of the parameters of the radiological evaluation, and also the final point estimation of the treatment results were subjected to statistical analysis by applying the analysis of variance, with the level of significance being accepted as p = 0.05. The noted results have shown that significant findings in the clinical evaluation were primarily the measurements of both the range of movements and the angle of the arm axis deviation, in relation to the forearm axis, while in the radiological evaluation-the symphysis quality estimation and occasionally occurring absence of correlation between the result of clinical evaluation and the radiological one (Fig. 1). Moreover, the recorded results pointed to the screw fixation as being more favourable, than Kirschner's wire fixation, method of treating the mentioned injuries in children (clinical and radiological data were favouring the screw fixation in fractures of medial epicondyle-whereas in condyle fractures-first of all the clinical data). (ABSTRACT TRUNCATED) PMID:9471919

Szyma?ska, E

1997-01-01

14

Determination of the Distal Fusion Level in the Management of Thoracolumbar and Lumbar Adolescent Idiopathic Scoliosis Using Pedicle Screw Instrumentation  

PubMed Central

Study Design A retrospective study. Purpose To determine the exact distal fusion level in the management of thoracolumbar/lumbar adolescent idiopathic scoliosis (TL/L AIS) using pedicle screw instrumentation (PSI). Overview of Literature The selection of distal fusion level remains controversial in TL/L AIS. Methods Radiographic parameters of 66 TL/L AIS patients were analyzed. The patients were grouped according to the distal fusion level; L3 group (fusion to L3, n=58) and L4 group (fusion to L4, n=8). The L3 group was subdivided into L3A (L3 crosses the mid-sacral line with rotation of less than grade II, n=33) and L3B (L3 does not cross the mid-sacral line or rotation is grade II or more, n=25) based on both bending radiographs. All of the patients in the L4 group had the same location and rotation of L3 in bending films as that of patients in the L3B group. An unsatisfactory result was defined as a lowest instrumented vertebral tilt (LIVT) of more than 10° or coronal balance of more than 15 mm. Results Among the 3 groups, there was a significantly lesser correction in the TL/L curve and LIVT in the L3B group. Unsatisfactory results were obtained in 3 patients (9.1%) of the L3A group, in 15 patients (68.2%) of the L3B group, and in 1 patient (12.5%) of the L4 group with a significant difference. Conclusions In TL/L AIS treatment with PSI, the curve can be fused to L3 with favorable radiographic outcomes when L3 crosses the mid-sacral line with rotation of less than grade II in bending films. Otherwise, fusion has to be extended to L4. PMID:25558324

Kim, Sung-Soo; Kim, Jin-Hyok; Kim, Jong-Woo; Um, Kyu-Sub; Ahn, Soo-Hyung; Suk, Se-Il

2014-01-01

15

Radiation exposure to the surgeon during closed interlocking intramedullary nailing  

SciTech Connect

During interlocking intramedullary nailing of twenty-five femoral and five tibial fractures, the primary surgeon wore both a universal film badge on the collar of the lead apron and a thermoluminescent dosimeter ring on the dominant hand to quantify the radiation that he or she received. When distal interlocking was performed, the first ring was removed and a second ring was used so that a separate recording could be made for this portion of the procedure. At the conclusion of the study, all of the recorded doses of radiation were averaged. The average amount of radiation to the head and neck during the entire procedure was 7.0 millirems of deep exposure and 8.0 millirems of shallow exposure. The average dose of radiation to the dominant hand during insertion of the intramedullary nail and the proximal interlocking screw was 13.0 millirems, while the average amount during insertion of the distal interlocking nail was 12.0 millirems. Both of these averages are well within the government guidelines for allowable exposure to radiation during one-quarter (three months) of a year. Precautions that are to be observed during this procedure are recommended.

Levin, P.E.; Schoen, R.W. Jr.; Browner, B.D.

1987-06-01

16

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

17

Biomechanical analyses of static and dynamic fixation techniques of retrograde interlocking femoral nailing using nonlinear finite element methods.  

PubMed

Femoral shaft fractures can be treated using retrograde interlocking nailing systems; however, fracture nonunion still occurs. Dynamic fixation techniques, which remove either the proximal or distal locking screws, have been used to solve the problem of nonunion. In addition, a surgical rule for dynamic fixation techniques has been defined based on past clinical reports. However, the biomechanical performance of the retrograde interlocking nailing systems with either the traditional static fixation technique or the dynamic fixation techniques has not been investigated by using nonlinear numerical modeling. Three-dimensional nonlinear finite element models were developed, and the implant strength, fixation stability, and contact area of the fracture surfaces were evaluated. Three types of femoral shaft fractures (a proximal femoral shaft fracture, a middle femoral shaft fracture, and a distal femoral shaft fracture) fixed by three fixation techniques (insertion of all the locking screws, removal of the proximal locking screws, or removal of the distal locking screws) were analyzed. The results showed that the static fixation technique resulted in sufficient fixation stability and that the dynamic fixation techniques decreased the failure risk of the implant and produced a larger contact area of the fracture surfaces. The outcomes of the current study could assist orthopedic surgeons in comprehending the biomechanical performances of both static and dynamic fixation techniques. In addition, the surgeons could also select a fixation technique based on the specific patient situation using the numerical outcomes of this study. PMID:24280626

Shih, Kao-Shang; Hsu, Ching-Chi; Hsu, Tzu-Pin; Hou, Sheng-Mou; Liaw, Chen-Kun

2014-02-01

18

Distal locking stem for revision femoral loosening and peri-prosthetic fractures  

Microsoft Academic Search

Revision total hip arthroplasty in the setting of a large proximal femoral deficiency or a peri-prosthetic fracture remains\\u000a a challenging problem. We describe the development, surgical technique and the use of cementless revision stems with distal\\u000a inter-locking screws to provide immediate stability of the femoral implant. Results were assessed in a large multicentre French\\u000a study conducted with the french hip

Patrice Mertl; Remy Philippot; Philippe Rosset; Henri Migaud; Jacques Tabutin; Denis Van de Velde

2011-01-01

19

The Retrograde Tibial Nail: presentation and biomechanical evaluation of a new concept in the treatment of distal tibia fractures.  

PubMed

Displaced distal tibia fractures require stable fixation while minimizing secondary damage to the soft tissues by the surgical approach and implants. Antegrade intramedullary nailing has become an alternative to plate osteosynthesis for the treatment of distal metaphyseal fractures over the past two decades. While retrograde intramedullary nailing is a standard procedure in other long bone fractures, only few attempts have been made on retrograde nailing of tibial fractures. The main reasons are difficulties of finding an ideal entry portal and the lack of an ideal implant for retrograde insertion. The Retrograde Tibial Nail (RTN) is a prototype intramedullary implant developed by our group. The implant offers double proximal and triple distal interlocking with an end cap leading to an angle-stable screw-nail construct of the most distal interlocking screw. Its design meets the requirements of a minimally invasive surgical approach, with a stable fracture fixation by multiple locking options. The 8mm diameter curved nail, with a length of 120 mm, is introduced through an entry portal at the medial malleolus. We see possible indications for the RTN in far distal tibial shaft fractures, distal extraarticular metaphyseal tibial fractures and in distal tibia fractures with simple extension into the ankle joint when the nail is combined lag screw fixation. A biomechanical comparison of the current RTN prototype against antegrade nailing (Expert Tibial Nail, Synthes(®), ETN) was performed. Both implants were fixed with double proximal and triple distal interlocking. Seven biomechanical composite tibiae were treated with either osteosynthesis techniques. A 10mm defect osteotomy 40 mm proximal to the joint line served as an AO 43-A3 type distal tibial fracture model. The stiffness of the implant-bone constructs was measured under low and high extra-axial compression (350 and 600 N) and under torsional load (8 Nm). Results show a comparable stability during axial loading for the two implant types with slightly higher stability in the RTN group. Rotational stability was superior for the RTN. Statistical analysis proved a significant difference (p<0.05) between the ETN and RTN for rotational stability. This study suggests that retrograde tibia nailing with the RTN is a promising new concept for the treatment of distal tibia fractures. PMID:24225228

Kuhn, Sebastian; Appelmann, Philipp; Pairon, Philip; Mehler, Dorothea; Rommens, Pol M

2014-01-01

20

Prevention of malunions in the rotation of complex fractures of the distal femur treated using the Dynamic Condylar Screw (DCS): an anatomical graphic analysis using computed tomography on cadaveric specimens.  

PubMed

The AO ASIF dynamic condylar screw is a popular method for the treatment of severe distal femoral fractures. Two methods of application have been presented by the AO group, one in the AO manual and the other in the teaching video tapes. The small difference in the techniques suggested that one of these methods might present a risk of rotational malunion in cases of severe comminuted fractures. The question of determining which method was less appropriate was investigated on human cadaveric specimens using a graphic analysis of computed tomograms. We found disadvantages for both methods and propose a third method combining the advantages of the two original methods. PMID:10853762

Maier, A; Cordey, J; Regazzoni, P

2000-05-01

21

Radiation exposure to the surgeon during femoral interlocking nailing under fluoroscopic imaging.  

PubMed

Femoral interlocking nailing requires fluoroscopic assistance for insertion of the nail and distal screws. In this study, scattered radiation to the eye and hand of the operating surgeon was measured during the procedure. Thermo-luminescent dosimeter (TLD) was used to quantify the dose received by the surgeon. The mean radiation exposure time during the procedure was 3.89 minutes. The mean scattered radiation doses to the hand and eye were 0.27 mSv and 0.09 mSv per procedure respectively. These very low doses have made a surgeon very unlikely to receive more than the recommended annual dose limit set by the National Council on Radiological Protection. PMID:16381279

Muzaffar, T S Tengku; Imran, Y; Iskandar, M A; Zakaria, A

2005-07-01

22

Tibiotarsal fracture repair in a bald eagle (Haliaeetus leucocephalus) using an interlocking nail.  

PubMed

A 14-yr-old, 5.13-kg bald eagle (Haliaeetus leucocephalus) was hit by a car and presented to the Michigan State University Small Animal Clinic with an open, grade II, transverse, midshaft, Winquist-Hansen type-II-comminuted left tibiotarsal fracture. The fracture was reduced and fixation established with a 4.7-mm-diameter, 112-mm-long, four-hole veterinary intramedullary interlocking nail maintained in position by single 2-mm transcortical screws placed in the main proximal and distal fragments. The bird was weight bearing on the bandaged limb 48 hr postoperatively. Radiographs obtained 4 wk postoperatively revealed bridging callus over three of four cortices. The bird was released after 5 mo of rehabilitation. PMID:15193078

Hollamby, Simon; Dejardin, Loic M; Sikarskie, James G; Haeger, Jennifer

2004-03-01

23

Multi-modal intra-operative navigation during distal locking of intramedullary nails.  

PubMed

The interlocking of intramedullary nails is a technically demanding procedure which involves a considerable amount of X-ray acquisitions; one study lists as many as 48 to successfully complete the procedure and fix screws into 4-6mm distal holes of the nail. We propose to design an augmented radiolucent drill to assist surgeons in completing the distal locking procedure without any additional X-ray acquisitions. Using an augmented reality fluoroscope that coregisters optical and X-ray images, we exploit solely the optical images to detect the augmented radiolucent drill and estimate its tip position in real-time. Consequently, the surgeons will be able to maintain the down the beam positioning required to drill the screws into the nail holes successfully. To evaluate the accuracy of the proposed augmented drill, we perform a preclinical study involving 6 surgeons and ask them to perform distal locking on dry bone phantoms. Surgeons completed distal locking 98.3% of the time using only a single X-ray image with an average navigation time of 1.4 0.9 min per hole. PMID:25296403

Diotte, Benoit; Fallavollita, Pascal; Wang, Lejing; Weidert, Simon; Euler, Ekkehard; Thaller, Peter; Navab, Nassir

2014-10-01

24

Comparison of a New Braid Fixation System to an Interlocking Intramedullary Nail for Tibial Osteotomy Repair in an Ovine Model  

E-print Network

by placing 1or 2 lock- ing screws at either end of the nail. These screws engage the bone cortices, HIROHITO KOBAYASHI, MS, and MARK D. MARKEL, DVM, PhD, Diplomate ACVS Objectives--To compare bone healing) and polymethylmethacrylate bone cement with an interlocking intramedullary (IM) nail fixation in an ovine model. Study Design

Scharer, John E.

25

Specifications SCT Hardwired Interlock Card  

E-print Network

Specifications SCT Hardwired Interlock Card Basic characteristics: Size: 6U by 220 mm, single width signals (TTL) Function description: Hardwired interlock card provides signal conversion between RS422 signals from the card to the back plane. Reference Version Draft 1.0 Created on July 3,2000 Last modified

California at Santa Cruz, University of

26

Triply interlocked covalent organic cages  

NASA Astrophysics Data System (ADS)

Interlocked molecules comprise two or more separate components that are joined by `mechanical' rather than covalent bonds. In other words, these molecular assemblies cannot be dissociated without the cleavage of one or more chemical bonds. Although recent progress has enabled the preparation of such topologies through coordination or templating interactions, three-dimensional interlocked covalent architectures remain difficult to prepare. Here, we present a template-free one-pot synthesis of triply interlocked organic cages. These 20-component dimers consist of two tetrahedral monomeric cages each built from four nodes and six linkers. The monomers exhibit axial chirality, which is recognized by their partner cage during the template-free interlocking assembly process. The dimeric cages also include two well-defined cavities per assembly, which for one of the systems studied led to the formation of a supramolecular host-guest chain. These interlocked organic molecules may prove useful as part of a toolkit for the modular construction of complex porous solids and other supramolecular assemblies.

Hasell, Tom; Wu, Xiaofeng; Jones, James T. A.; Bacsa, John; Steiner, Alexander; Mitra, Tamoghna; Trewin, Abbie; Adams, Dave J.; Cooper, Andrew I.

2010-09-01

27

49 CFR 236.772 - Machine, interlocking.  

Code of Federal Regulations, 2011 CFR

...Transportation 4 2011-10-01 2011-10-01 false Machine, interlocking. 236.772 Section 236.772 Transportation...SYSTEMS, DEVICES, AND APPLIANCES Definitions § 236.772 Machine, interlocking. An assemblage of manually operated...

2011-10-01

28

49 CFR 236.772 - Machine, interlocking.  

Code of Federal Regulations, 2012 CFR

...Transportation 4 2012-10-01 2012-10-01 false Machine, interlocking. 236.772 Section 236.772 Transportation...SYSTEMS, DEVICES, AND APPLIANCES Definitions § 236.772 Machine, interlocking. An assemblage of manually operated...

2012-10-01

29

Intrapelvic Migration of the Lag Screw in Intramedullary Nailing  

PubMed Central

Internal fixation with intramedullary devices has gained popularity for the treatment of intertrochanteric femoral fractures, which are common injuries in the elderly. The most common complications are lag screw cut out from the femoral head and femoral fracture at the distal tip of the nail. We report here a rare complication of postoperative lag screw migration into the pelvis with no trauma. The patient was subsequently treated with lag screw removal and revision surgery with total hip arthroplasty. This case demonstrated that optimal fracture reduction and positioning of the lag screw are the most important surgical steps for decreasing the risk of medial migration of the lag screw. Furthermore, to prevent complications, careful attention should be paid to subsequent steps such as precise insertion of the set screw. PMID:25610680

Toki, Shunichi; Hamada, Daisuke; Yoshioka, Shinji; Tsutsui, Takahiko; Tamaki, Yasuaki; Sairyo, Koichi

2014-01-01

30

Comparative endurance testing of the Biomet Matthews Nail and the Dynamic Compression Screw, in simulated condylar and supracondylar femoral fractures  

Microsoft Academic Search

BACKGROUND: The dynamic compression screw is a plate and screws implant used to treat fractures of the distal femur. The Biomet Matthews Nail is a new retrograde intramedullary nail designed as an alternative surgical option to treat these fractures. The objective of this study was to assess the comparative endurance of both devices. METHOD: The dynamic compression screw (DCS) and

Laurence M O'Connor-Read; Jerome A Davidson; Benjamin M Davies; Michael G Matthews; Paul Smirthwaite

2008-01-01

31

Quantitative Shape Measurements of Distal Volcanic Ash Colleen M. Riley, William I. Rose, and Gregg J.S. Bluth  

E-print Network

Quantitative Shape Measurements of Distal Volcanic Ash Colleen M. Riley, William I. Rose, and Gregg interlocking are related to shape (Gilbert and Lane, 1994). The ability of satellite sensors to accurately

Rose, William I.

32

12 CFR 303.249 - Management official interlocks.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 false Management official interlocks. 303...Other Filings § 303.249 Management official interlocks. ...the Depository Institutions Management Interlocks Act (12 U.S.C. 3207), section 13 of the FDI Act (12 U.S.C....

2010-01-01

33

Fabrication and Evaluation of a Noncompliant Molar Distalizing Appliance: Bonded Molar Distalizer  

PubMed Central

Objective Attempts to treat class II malocclusions without extraction in non-compliant patients have led to utilization of intraoral molar distalizing appliances. The purpose of this study was to investigate dental and skeletal effects of Bonded Molar Distalizer (BMD) which is a simple molar distalizing appliance. Materials and Methods Sixteen patients (12 girls, four boys) with bilateral half-cusp class II molar relationship, erupted permanent second molars and normal or vertical growth pattern were selected for bilateral distalization of maxillary molars via BMD. The screws were activated every other day, alternately. Lateral cephalograms and study models were obtained before treatment and after 11 weeks activation of the appliance. Results Significant amounts of molar distalization, molar distal tipping and anchorage loss were observed. The mean maxillary first molar distal movement was 1.22±0.936 mm with a distal tipping of 2.97±3.74 degrees in 11 weeks. The rate of distal movement was 0.48 mm per month. Reciprocal mesial movement of the first premolars was 2.26±1.12 mm with a mesial tipping of 4.25±3.12 degrees. Maxillary incisors moved 3.55±1.46 mm and tipped 9.87±5.03 degrees mesially. Lower anterior face height (LAFH) decreased 1.28±1.36 mm. Conclusion BMD is appropriate for distalizing maxillary molars, especially in patients with critical LAFH, although significant amounts of anchorage loss occur using this appliance. PMID:22457837

Sodagar, A.; Ahmad Akhoundi, M. S.; Rafighii, A.; Arab, S.

2011-01-01

34

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

35

Comparison of Maxillary Molar Distalization with an Implant-Supported Distal Jet and a Traditional Tooth-Supported Distal Jet Appliance  

PubMed Central

Aim. To investigate and compare the efficiency of two appliances for molar distalization: the bone-anchored distal screw (DS) and the traditional tooth-supported distal jet (DJ) for molar distalization and anchorage loss. Methods. Tests (18 subjects) were treated with a DS and controls (18 subjects) were treated with a DJ. Lateral cephalograms were obtained before and at the end of molar distalization and were analysed. Shapiro Wilk test, unpaired t-test, and Wilcoxon rank-sum test were applied according to values distribution. The ? level was fixed at 0.05. Results. Maxillary first molars were successfully distalized into a Class I relationship in all patients. The mean molar distalization and treatment time were similar in both groups. The DS group exhibited a spontaneous distalization (2.1 ± 0.9?mm) of the first premolar with control of anchorage loss, distal tipping, extrusion, and skeletal changes. Conclusions. The DS is an adequate compliance-free distalizing appliance that can be used safely for the correction of Class II malocclusions. In comparison to the traditional DJ, the DS enables not only a good rate of molar distalization, but also a spontaneous distalization of the first premolars. PMID:25018770

Cozzani, Mauro; Pasini, Marco; Zallio, Francesco; Ritucci, Robert; Mutinelli, Sabrina; Mazzotta, Laura; Giuca, Maria Rita; Piras, Vincenzo

2014-01-01

36

Coastal protection using topological interlocking blocks  

NASA Astrophysics Data System (ADS)

The coastal protection systems mainly rely on the self-weight of armour blocks to ensure its stability. We propose a system of interlocking armour blocks, which form plate-shape assemblies. The shape and the position of the blocks are chosen in such a way as to impose kinematic constraints that prevent the blocks from being removed from the assembly. The topological interlocking shapes include simple convex blocks such as platonic solids, the most practical being tetrahedra, cubes and octahedra. Another class of topological interlocking blocks is so-called osteomorphic blocks, which form plate-like assemblies tolerant to random block removal (almost 25% of blocks need to be removed for the assembly to loose integrity). Both classes require peripheral constraint, which can be provided either by the weight of the blocks or post-tensioned internal cables. The interlocking assemblies provide increased stability because lifting one block involves lifting (and bending) the whole assembly. We model the effect of interlocking by introducing an equivalent additional self-weight of the armour blocks. This additional self-weight is proportional to the critical pressure needed to cause bending of the interlocking assembly when it loses stability. Using beam approximation we find an equivalent stability coefficient for interlocking. It is found to be greater than the stability coefficient of a structure with similar blocks without interlocking. In the case when the peripheral constraint is provided by the weight of the blocks and for the slope angle of 45o, the effective stability coefficient for a structure of 100 blocks is 33% higher than the one for a similar structure without interlocking. Further increase in the stability coefficient can be reached by a specially constructed peripheral constraint system, for instance by using post-tension cables.

Pasternak, Elena; Dyskin, Arcady; Pattiaratchi, Charitha; Pelinovsky, Efim

2013-04-01

37

Optimisation of screw compressors  

Microsoft Academic Search

Increasing demands for more efficient screw compressors require that compressor designs are tailored upon their duty, capacity and manufacturing capability. A suitable procedure for optimisation of the screw compressor shape, size, dimension and operating parameters is described here, which results in the most appropriate design for a given compressor application and fluid. It is based on a rack generation algorithm

N. Stosic; I. K. Smith; A. Kovacevic

2003-01-01

38

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

39

49 CFR 236.772 - Machine, interlocking.  

Code of Federal Regulations, 2013 CFR

...Definitions § 236.772 Machine, interlocking. An assemblage of manually operated levers or other devices for the control of signals, switches or other units. Cross Reference: Magnet, track, see §...

2013-10-01

40

49 CFR 236.772 - Machine, interlocking.  

Code of Federal Regulations, 2010 CFR

...Definitions § 236.772 Machine, interlocking. An assemblage of manually operated levers or other devices for the control of signals, switches or other units. Cross Reference: Magnet, track, see §...

2010-10-01

41

Interlocking egg-crate type grid assembly  

DOEpatents

Disclosed is an interlocking egg-crate hexagonal grid for supporting a nuclear fuel pin in a hexagonal array. The grid is formed from strips bent at an angle of about 120.degree. at each vertex. Over some faces of each hexagonal cell the strips are coplanar but are arranged, by stacking and interlocking, to avoid any double thickness of metal in that plane. Springs and dimples are formed in the faces of each cell to hold the fuel pin substantially centered.

Kast, Steven J. (Niskayuna, NY)

1987-01-01

42

49 CFR 236.340 - Electromechanical interlocking machine; locking between electrical and mechanical levers.  

Code of Federal Regulations, 2012 CFR

...false Electromechanical interlocking machine; locking between electrical and mechanical...340 Electromechanical interlocking machine; locking between electrical and mechanical... In electro-mechanical interlocking machine, locking between electric and...

2012-10-01

43

49 CFR 236.340 - Electromechanical interlocking machine; locking between electrical and mechanical levers.  

Code of Federal Regulations, 2010 CFR

...false Electromechanical interlocking machine; locking between electrical and mechanical...340 Electromechanical interlocking machine; locking between electrical and mechanical... In electro-mechanical interlocking machine, locking between electric and...

2010-10-01

44

49 CFR 236.340 - Electromechanical interlocking machine; locking between electrical and mechanical levers.  

Code of Federal Regulations, 2011 CFR

...false Electromechanical interlocking machine; locking between electrical and mechanical...340 Electromechanical interlocking machine; locking between electrical and mechanical... In electro-mechanical interlocking machine, locking between electric and...

2011-10-01

45

49 CFR 236.340 - Electromechanical interlocking machine; locking between electrical and mechanical levers.  

Code of Federal Regulations, 2013 CFR

...false Electromechanical interlocking machine; locking between electrical and mechanical...340 Electromechanical interlocking machine; locking between electrical and mechanical... In electro-mechanical interlocking machine, locking between electric and...

2013-10-01

46

Homogenization of interlocking masonry structures using a generalized differential  

E-print Network

1 Homogenization of interlocking masonry structures using a generalized differential expansion://navier.enpc.fr/~sulem/index.html Keywords: Micromorphic Continuum; Interlocking masonry; Wave propagation; Generalized Differential for the homogenization of masonry structures with interlocking blocks. This is done by constructing a continuum which

Paris-Sud XI, Université de

47

Predicting repeat DUI offenses with the alcohol interlock recorder  

Microsoft Academic Search

The aim of this report has been to use information contained in the alcohol ignition interlock recorder to determine whether systematic analysis of it can be used to predict which DUI offenders will recidivate during the first 2 years after the interlock is removed. The interlock record was accumulated during a 4-year intervention study in Alberta, Canada. Data from more

Paul R Marques; A. Scott Tippetts; Robert B Voas; Douglas J Beirness

2001-01-01

48

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

49

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

50

Process synchronization without long-term interlock  

Microsoft Academic Search

A technique is presented for replacing long-term interlocking of shared data by the possible repetition of unprivileged code in case a version number (associated with the shared data) has been changed by another process. Four principles of operating system architecture (which have desirable effects on the intrinsic reliability of a system) are presented; implementation of a system adhering to these

William B. Easton

1972-01-01

51

Process synchronization without long-term interlock  

Microsoft Academic Search

A technique is presented for replacing long-term interlocking of shared data by the possible repetition of unprivileged code in case a version number (associated with the shared data) has been changed by another process. Four principles of operating system architecture (which have desirable effects on the intrinsic reliability of a system) are presented; implementation of a system adhering to these

William B. Easton

1971-01-01

52

An embedded fail-safe interlocking system  

Microsoft Academic Search

The paper presents a fail-safe railway interlocking system embedded in an Area Control Center (ACC) system. The host of the system is a TANDEM NONSTOP HIMALAYA K200 computer. The fault tolerant computer aims at high safety, reliability and availability. In addition, the dispatcher management system, device supervision system, and train control system are integrated in the host computer to ensure

Bin Pei; Yinghua Ming

1997-01-01

53

Radiation safety interlocks at the NSLS  

SciTech Connect

The function of the NSLS interlock systems is to insure that no one is in an area where there is hazardous radiation, and to turn off the radiation source if a person somehow gains access to such an area. The interlock systems for the high hazard areas meet the following design requirements: (1) The system is redundant, that is no single failure can render the system unsafe. This is done by providing 2 independent systems or circuits; (2) In so far as possible, the two circuits are physically different. This minimizes the possibility of related coincident failures; (3) The design is fail safe. This means that the most likely failure modes leave the system in a safe condition. For example, the following failures are safe: Loss of power in any part of the system, any combination of shorts to ground, and any combination of open circuits; and (4) The interlock system must be testable. Redundancy sometimes makes testing difficult, but testing schemes must be worked out, since an untested interlock is undependable.

Dickinson, T.

1985-07-01

54

Distal Convoluted Tubule  

PubMed Central

The distal convoluted tubule is the nephron segment that lies immediately downstream of the macula densa. Although short in length, the distal convoluted tubule plays a critical role in sodium, potassium, and divalent cation homeostasis. Recent genetic and physiologic studies have greatly expanded our understanding of how the distal convoluted tubule regulates these processes at the molecular level. This article provides an update on the distal convoluted tubule, highlighting concepts and pathophysiology relevant to clinical practice. PMID:24855283

Ellison, David H.

2014-01-01

55

Biomechanical effects of plate area and locking screw on medial open tibial osteotomy.  

PubMed

Medial open high tibial osteotomy (HTO) has been used to treat osteoarthritis of the medial compartment of the knee. However, weaker plate strength, unstable plate/screw junction and improper surgery technique are highly related to the HTO outcomes. Two ?-shape plates were designed and eight variations (two supporting area ×  four locking stiffness) were compared by finite-element method. The computed tomography-based tibia was reconstructed and both wedge micromotion and implant stresses were chosen as the comparison indices. The construct was subjected to surgical and physiological loads. The medial-posterior region is the most loaded region and the load through the posterior leg is about four times that through the anterior leg. This indicates that the two-leg design can form a force-couple mechanism to effectively reduce the implant stresses. The use of locking screws significantly decrease the screw and hole stresses. However, the extending plate reduces the stresses of screws and holes above the wedge but makes the distal screws and holes much stressed. Wedge micromotion is affected by extending plate rather than locking screw. Three factors contribute to effective stabilisation of unstable HTO wedge: (1) intimate tibia-plate contact at medial-posterior regions, (2) sufficient rigidity at plate-screw junctions and (3) effective moment-balancing design at distal tibia-plate interfaces. PMID:24617553

Luo, Chu-An; Lin, Shang-Chih; Hwa, Su-Yang; Chen, Chun-Ming; Tseng, Ching-Shiow

2015-09-01

56

The lingual distalizer system.  

PubMed

Class II molar relationships can be corrected by several methods. In previous systems, orthodontic forces have been applied to crowns and distal movement of the first molar has mainly been by tipping and a rotation of the crowns. A new Lingual Distalizer (LD) has recently been developed to distalize the maxillary molars without the drawbacks of previous appliances. The lingual distalizer is relatively easy to insert, is well-tolerated, does not require patient co-operation and is aesthetic. It distalizes molars without loss of anchorage and moves them with bodily translation. PMID:8942092

Carano, A; Testa, M; Siciliani, G

1996-10-01

57

Thermal static bending of deployable interlocked booms  

NASA Technical Reports Server (NTRS)

Metal ribbons processed with a heat-forming treatment are enabled to form tubelike structures when deployed from a roll. Deployable booms of this have been utilized for gravity-gradient stabilization on the RAE, ATS, and Nimbus D satellites. An experimental thermal-mechanics test apparatus was developed to measure the thermal static bending and twist of booms up to 3 meters long. The apparatus was calibrated by using the correlation between calculated and observed thermal bending of a seamless tube. Thermal static bending values of 16 interlocked deployable booms were observed to be within a factor of 2.5 of the values calculated from seamless-tube theory. Out-of-Sun-plane thermal bending was caused by complex heat transfer across the interlocked seam. Significant thermal static twisting was not observed.

Staugaitis, C. L.; Predmore, R. E.

1973-01-01

58

The Screw-worm.  

E-print Network

TEXAS AGRICULTURAL EXP II,HIMEXT Srl'ATION. BULLETIN No. 12, ~*fZkRP ** SEPTEMBER, 1890. .$, y~, 'TWORM. AGRICULTURAL' AND MECHANICAL COLLEGE OF TEXAS. All Bulletins of this Station are issued free. Any one interested... to Director. ,nt Agriculturist. . . naala~ant in Chemistrv. . . LVL~L~OI' . . Assists . . Assista A ..-:-A- TEXAS AGYLICULTUliAL EXYEliIMEXT STATION. THE SCREW-WORM. - . . . .. .-. -- M. FRANCIS, D. V. M. ~ - - In the First Annual Report...

Francis, M. (Mark)

1890-01-01

59

Foreign Body Reaction After PLC Reconstruction Caused by a Broken PLLA Screw.  

PubMed

Foreign body reactions may occur in patients who receive bioabsorbable implants during orthopedic surgery for fractures and ligament repair. The authors describe a 34-year-old man who presented with a palpable tender mass on the lateral aspect of the left knee of 1 month's duration. He underwent posterior cruciate ligament and posterolateral corner reconstruction 3 years earlier. Physical examination showed a 1×1-cm soft, nontender mass without localized warmth on the lateral epicondyle of the distal femur. Magnetic resonance imaging showed a broken screw fragment surrounded by a cyst-like mass. Under general anesthesia, the surgeon excised the screw fragment and the fibrotic mass, enclosing it in the subcutaneous tissue at the lateral epicondyle, the site at which a poly-L-lactic acid bioabsorbable screw had been inserted to fix the graft for posterolateral corner reconstruction. Histologic evaluation showed a foreign body reaction to the degraded screw particles. To the authors' knowledge, this report is the first description of a patient presenting with a delayed foreign body reaction to a broken poly-L-lactic acid bioabsorbable screw at the lateral femoral epicondyle after posterolateral corner reconstruction. Because delayed foreign body reactions can occur at any site of poly-L-lactic acid bioabsorbable screw insertion, care should be taken to avoid screw protrusion during ligament reconstruction because it can lead to screw breakage and delayed foreign body reaction. [Orthopedics. 2014; 37(12):e1129-e1132.]. PMID:25437089

Kim, Tae-Kwon; Jeong, Tae-Wan; Lee, Dae-Hee

2014-12-01

60

49 CFR 1242.58 - Operating signals and interlockers, operating drawbridges, highway crossing protection (accounts...  

Code of Federal Regulations, 2012 CFR

...interlockers, operating drawbridges, highway crossing protection (accounts XX-51-59...interlockers, operating drawbridges, highway crossing protection (accounts XX-51-59...signals, interlockers, drawbridges and highway crossings are...

2012-10-01

61

49 CFR 1242.58 - Operating signals and interlockers, operating drawbridges, highway crossing protection (accounts...  

Code of Federal Regulations, 2014 CFR

...interlockers, operating drawbridges, highway crossing protection (accounts XX-51-59...interlockers, operating drawbridges, highway crossing protection (accounts XX-51-59...signals, interlockers, drawbridges and highway crossings are...

2014-10-01

62

49 CFR 1242.58 - Operating signals and interlockers, operating drawbridges, highway crossing protection (accounts...  

Code of Federal Regulations, 2011 CFR

...interlockers, operating drawbridges, highway crossing protection (accounts XX-51-59...interlockers, operating drawbridges, highway crossing protection (accounts XX-51-59...signals, interlockers, drawbridges and highway crossings are...

2011-10-01

63

49 CFR 1242.58 - Operating signals and interlockers, operating drawbridges, highway crossing protection (accounts...  

Code of Federal Regulations, 2010 CFR

...interlockers, operating drawbridges, highway crossing protection (accounts XX-51-59...interlockers, operating drawbridges, highway crossing protection (accounts XX-51-59...signals, interlockers, drawbridges and highway crossings are...

2010-10-01

64

49 CFR 1242.58 - Operating signals and interlockers, operating drawbridges, highway crossing protection (accounts...  

Code of Federal Regulations, 2013 CFR

...interlockers, operating drawbridges, highway crossing protection (accounts XX-51-59...interlockers, operating drawbridges, highway crossing protection (accounts XX-51-59...signals, interlockers, drawbridges and highway crossings are...

2013-10-01

65

Tibial cyst formation after anterior cruciate ligament reconstruction using a new bioabsorbable screw  

Microsoft Academic Search

We report a case of tibial cyst formation twelve months after anterior cruciate ligament reconstruction using hamstring graft. A composite bioabsorbable interference screw made of ‘beta tricalcium phosphate and poly l-lactide’ fixed the graft distally. The patient presented with acute symptoms of pain and swelling over the proximal tibia. Curettage of the cyst resulted in complete recovery within 3 months.

K Malhan; A Kumar; D Rees

2002-01-01

66

Screw Dislocations in Light Wavefronts  

Microsoft Academic Search

We discuss screw dislocations of a phase surface as the one type of wavefront of a monochromatic wave. The simple method for construction of the optical wavefronts with an isolated screw dislocation is reported. Laser beams with the dislocations of different orders were experimentally achieved by using diffraction on computer-synthesized gratings.

V. Yu. Bazhenov; M. S. Soskin; M. V. Vasnetsov

1992-01-01

67

Optimization Of Screw Compressor Design  

Microsoft Academic Search

Ever increasing demands for efficient screw compressors require that compressor designs are tailored upon their duty, capacity and manufacturing capability. A suitable procedure for optimisation of screw compressor shape, dimension and operating parameters is described here, which results in the most appropriate design for a given compressor duty. It is based on a rack generation algorithm for rotor profile combined

N. Stosic; Ian K Smith; A. Kovacevic

2002-01-01

68

Geometric properties of the fractured tibia stabilized by unreamed interlocking nail: development of a three-dimensional finite element model.  

PubMed

Based upon magnetic resonance scans of five human tibiae a three-dimensional finite element model using eight nodal isoparametric elements was developed to analyze the biomechanical properties of fracture fixation by an unreamed interlocking nail. Tension phenomena and bone implant translations occurring in the borderlines of the fracture zone, bone-implant interface, and the fixation site of the interlocking screws were analyzed with the help of link elements. The proximal fracture segment was fixed with a link element so as to produce exclusively translatory shifts corresponding to the vector of the load applied. Under condition of static load F = 500 N or axial torsion MT = 15 Nm the biomechanical properties of a nailed horizontal fracture (42-A3), a three fragment lesion (42-B2), and a comminuted midshaft fracture (42-C3) were evaluated. On condition of axial load maximum dislocations of 0.1549 mm are induced in the direction of the x-axis due to the asymmetric geometry of the human tibia which promotes medially directed translations. Independent from the fracture type present a homogenous tension profile was calculated for the whole tibia diaphysis with a sigmaEQV ranging from 24.18 to 121.14 MPa due to the relative low elastic modulus of the cortical bone compared to material characteristics of the implant. However, application of a torsional moment MT = 15 Nm induces significantly increased tension maxima in the nail-interlocking screw interface with a sigmaEQV = 7, 626 MPa. Maximum translatory movements ux = 12.59 mm and uy = 23.53 mm in the x and y plane indicate that these load conditions bear a high risk of an implant failure. PMID:8812073

Raunest, J; Kynast, W; Lesch, V; Kukulies, U; Hackländer, T; Schwarting, K H; Arnold, G

1996-08-01

69

46 CFR 111.70-7 - Remote control, interlock, and indicator circuits.  

Code of Federal Regulations, 2011 CFR

...interlock, and indicator circuits. 111.70-7 Section... ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Motor Circuits, Controllers, and Protection...interlock, and indicator circuits. (a) Overcurrent...

2011-10-01

70

46 CFR 111.70-7 - Remote control, interlock, and indicator circuits.  

Code of Federal Regulations, 2014 CFR

...interlock, and indicator circuits. 111.70-7 Section... ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Motor Circuits, Controllers, and Protection...interlock, and indicator circuits. (a) Overcurrent...

2014-10-01

71

46 CFR 111.70-7 - Remote control, interlock, and indicator circuits.  

Code of Federal Regulations, 2012 CFR

...interlock, and indicator circuits. 111.70-7 Section... ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Motor Circuits, Controllers, and Protection...interlock, and indicator circuits. (a) Overcurrent...

2012-10-01

72

46 CFR 111.70-7 - Remote control, interlock, and indicator circuits.  

Code of Federal Regulations, 2013 CFR

...interlock, and indicator circuits. 111.70-7 Section... ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Motor Circuits, Controllers, and Protection...interlock, and indicator circuits. (a) Overcurrent...

2013-10-01

73

46 CFR 111.70-7 - Remote control, interlock, and indicator circuits.  

Code of Federal Regulations, 2010 CFR

...interlock, and indicator circuits. 111.70-7 Section... ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Motor Circuits, Controllers, and Protection...interlock, and indicator circuits. (a) Overcurrent...

2010-10-01

74

21. Historic view looking northeast from tracks of Shell Interlocking ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

21. Historic view looking northeast from tracks of Shell Interlocking Tower after construction, 1909. Photographic copy of photograph published in Railway Age Gazette, February 4, 1910. - New York, New Haven, & Hartford Railroad, Shell Interlocking Tower, New Haven Milepost 16, approximately 100 feel east of New Rochelle Junction, New Rochelle, Westchester County, NY

75

Verifying Therapy Safety Interlock System with SPIN Motlatsi Seotsanyana1  

E-print Network

Verifying Therapy Safety Interlock System with SPIN Motlatsi Seotsanyana1 , Jaco Geldenhuys2 1 in the design and verification of the Safety Interlock System (SIS) at iThemba LABS. SIS is part of proton therapy control system (TCS) and its main task is to monitor and evaluate the safety conditions

Geldenhuys, Jaco

76

Efficiency of a pendulum appliance for molar distalization related to second and third molar eruption stage  

Microsoft Academic Search

A modified pendulum appliance, including a distal screw and special preactivated pendulum springs (built-in straightening activation and toe-in bending), was used for bilateral maxillary molar distalization in 36 adolescent patients in various stages of the molar dentition. The patients were divided into 3 groups (PG 1-3) according to the stage of eruption of their second and third molars. In PG

Gero S. M Kinzinger; Ulrike B Fritz; Franz-Günter Sander; Peter R Diedrich

2004-01-01

77

Synthesis of interlocked molecules by olefin metathesis  

NASA Astrophysics Data System (ADS)

A large body of work in the Grubbs group has focused on the development of functional-group tolerant ruthenium alkylidene catalysts that perform a number of olefin metathesis reactions. These catalysts have seen application in a wide range of fields, including classic total synthesis as well as polymer and materials chemistry. One particular family of compounds, interlocked molecules, has benefitted greatly from these advances in catalyst stability and activity. This thesis describes several elusive and challenging interlocked architectures whose syntheses have been realized through the utilization of different types of ruthenium-catalyzed olefin metathesis reactions. Ring-closing olefin metathesis has enabled the synthesis of a [c2]daisy-chain dimer with the ammonium binding site near the cap of the dimer. A deprotonated DCD possessing such a structural attribute will more forcefully seek to restore coordinating interactions upon reprotonation, enhancing its utility as a synthetic molecular actuator. Dimer functionalization facilitated incorporation into linear polymers, with a 48% size increase of an unbound, extended analogue of the polymer demonstrating slippage of the dimer units. Ongoing work is directed at further materials studies, in particular, exploring the synthesis of macroscopic networks containing the DCD units and analyzing the correlation between molecular-scale extension-contraction manipulations and resulting macro-scale changes. A "clipping" approach to a polycatenated cyclic polymer, a structure that resembles a molecular "charm bracelet", has been described. The use of ring-opening metathesis polymerization of a carbamate monomer in the presence of a chain transfer agent allowed for the synthesis of a linear polymer that was subsequently functionalized and cyclized to the corresponding cyclic analogue. This cyclic polymer was characterized through a variety of techniques, and subjected to further functionalization reactions, affording a cyclic polyammonium scaffold. Diolefin polyether fragments were coordinated and "clipped" around the ammonium sites within the polymer backbone using ring-closing olefin metathesis, giving the molecular "charm bracelet". Confirmation of the interlocked nature of the product was achieved via 1H NMR spectroscopy and two-dimensional diffusion ordered NMR spectroscopy. A simple strategy for a one-pot, multi-component synthesis of polyrotaxanes using acyclic diene metathesis polymerization was developed. The polyrotaxanes were characterized by traditional 1H NMR spectroscopy as well as size exclusion chromatography, and the interlocked topology was confirmed using two-dimension diffusion-ordered NMR spectroscopy. The dynamic, self-correcting nature of the ADMET polymerization was also explored through the equilibration of a capped polyammonium polymer in the presence of dibenzo-24-crown-8 ether and olefin metathesis catalysts. The efficiency and ease with which these mechanically interlocked macromolecules can be assembled should facilitate rapid modulation to achieve versatile polyrotaxane architectures. Flexible, switchable [c2]daisy-chain dimers (DCDs) were synthesized, where the macromer ammonium binding site was adjacent to the crown-type recognition structure and separated from the cap by an alkyl chain. A DCD of this topology is expected to have an extended structure in the bound conformation (when the ammonium was coordinated to the crown). Several different macromer candidates were designed to allow access to DCDs with flexible alkyl chains between the ammonium binding site and the cap, and a number of synthetic routes were explored in an effort to access these challenging materials. While the first generation DCD structure proved to be unstable due to a labile ester linkage, work is continuing toward the development of several cap structures in an effort to replace the ester linkage with an ether linkage, which, in the second generation model systems, has proven much more stable to the acidic and basic conditions necessary

Clark, Paul Gregory

78

Idiopathic distal radioulnar synostosis.  

PubMed

Radioulnar synostosis is rare, and exists in two forms: congenital and post-traumatic. The congenital form presents only in the proximal forearm, and the post-traumatic form may present anywhere along the radius and ulna. The only known aetiology for distal radioulnar synostosis is post-traumatic. We present a rare case of distal radioulnar synostosis with no previous history of trauma. PMID:23789710

Shoham, Yaron; Gurfinkel, Reuven; Sagi, Amiram

2014-02-01

79

Power connect safety and connection interlock  

NASA Technical Reports Server (NTRS)

A power connect safety and connection interlock system is shown for use with inverters and other DC loads (16) which include capacitor filter banks (14) at their DC inputs. A safety circuit (20) operates a spring (26) biased, solenoid (22) driven mechanical connection interference (24) which prevents mating and therefore electrical connection between the power contactor halves (11, 13) of the main power contacts (12) until the capacitor bank is safely precharged through auxiliary contacts (18). When the DC load (16) is shut down, the capacitor bank (14) is automatically discharged through a discharging power resistor (66) by a MOSFET transistor (60) through a discharging power resistor (66) only when both the main power contacts and auxiliary contacts are disconnected.

Rippel, Wally E. (Inventor)

1992-01-01

80

12. DETAIL VIEW OF INTERLOCKING RAIL CONNECTION AT FREE END ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. DETAIL VIEW OF INTERLOCKING RAIL CONNECTION AT FREE END OF MOVING LEAF - Seddon Island Scherzer Rolling Lift Bridge, Spanning Garrison Channel from Tampa to Sedden Island, Tampa, Hillsborough County, FL

81

B & P Junction Substation & Interlocking Tower. Baltimore, Baltimore ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

B & P Junction Substation & Interlocking Tower. Baltimore, Baltimore City, MD. Sec. 1201, MP 95.85. - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

82

Perryville Interlocking Tower. Perryville, Cecil Co., MD. Sec. 1201, MP ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Perryville Interlocking Tower. Perryville, Cecil Co., MD. Sec. 1201, MP 59.10. - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

83

BOWIE INTERLOCKING TOWER AND PASSENGER STATION. BOWIE, PRINCE GEORGES CO., ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

BOWIE INTERLOCKING TOWER AND PASSENGER STATION. BOWIE, PRINCE GEORGES CO., MD. Sec. 1201, MP 120.50. - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

84

Edgewood Interlocking Tower. Edgewood, Hareford Co., MD. Sec. 1201, MP ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Edgewood Interlocking Tower. Edgewood, Hareford Co., MD. Sec. 1201, MP 75.50. - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

85

Union Junction Interlocking Tower. Baltimore, Baltimore City, MD. Sec. 1201, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Union Junction Interlocking Tower. Baltimore, Baltimore City, MD. Sec. 1201, MP 95.49. - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

86

1. GENERAL VIEW LOOKING EAST, SHOWING INTERLOCKING TOWER. Lehigh ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. GENERAL VIEW LOOKING EAST, SHOWING INTERLOCKING TOWER. - Lehigh Valley Railroad, Easton Station, Corner of Canal Street & Smith Avenue at Third Street Bridge over Lehigh River, Easton, Northampton County, PA

87

41. Shell Interlocking Tower. New Rochelle, Westchester Co., NY. Sec. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

41. Shell Interlocking Tower. New Rochelle, Westchester Co., NY. Sec. 9108, MP 16.20. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York, New York County, NY

88

44. Shell Interlocking Tower. New Rochelle, Westchester Co., NY. Sec. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

44. Shell Interlocking Tower. New Rochelle, Westchester Co., NY. Sec. 9108, MP 16.20. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York, New York County, NY

89

42. Shell Interlocking Tower. New Rochelle, Westchester Co., NY. Sec. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

42. Shell Interlocking Tower. New Rochelle, Westchester Co., NY. Sec. 9108, MP 16.20. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York, New York County, NY

90

43. Shell Interlocking Tower. New Rochelle, Westchester Co., NY. Sec. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

43. Shell Interlocking Tower. New Rochelle, Westchester Co., NY. Sec. 9108, MP 16.20. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York, New York County, NY

91

Cortical screws used to rescue failed lumbar pedicle screw construct: a biomechanical analysis.  

PubMed

OBJECT Cortical trajectory screw constructs, developed as an alternative to pedicle screw fixation for the lumbar spine, have similar in vitro biomechanics. The possibility of one screw path having the ability to rescue the other in a revision scenario holds promise but has not been evaluated. The objective in this study was to investigate the biomechanical properties of traditional pedicle screws and cortical trajectory screws when each was used to rescue the other in the setting of revision. METHODS Ten fresh-frozen human lumbar spines were instrumented at L3-4, 5 with cortical trajectory screws and 5 with pedicle screws. Construct stiffness was recorded in flexion/extension, lateral bending, and axial rotation. The L-3 screw pullout strength was tested to failure for each specimen and salvaged with screws of the opposite trajectory. Mechanical stiffness was again recorded. The hybrid rescue trajectory screws at L-3 were then tested to failure. RESULTS Cortical screws, when used in a rescue construct, provided stiffness in flexion/extension and axial rotation similar to that provided by the initial pedicle screw construct prior to failure. The rescue pedicle screws provided stiffness similar to that provided by the primary cortical screw construct in flexion/extension, lateral bending, and axial rotation. In pullout testing, cortical rescue screws retained 60% of the original pedicle screw pullout strength, whereas pedicle rescue screws retained 65% of the original cortical screw pullout strength. CONCLUSIONS Cortical trajectory screws, previously studied as a primary mode of fixation, may also be used as a rescue option in the setting of a failed or compromised pedicle screw construct in the lumbar spine. Likewise, a standard pedicle screw construct may rescue a compromised cortical screw track. Cortical and pedicle screws each retain adequate construct stiffness and pullout strength when used for revision at the same level. PMID:25478820

Calvert, Graham C; Lawrence, Brandon D; Abtahi, Amir M; Bachus, Kent N; Brodke, Darrel S

2015-02-01

92

Construction and Biomechanical Properties of PolyAxial Self-Locking Anatomical Plate Based on the Geometry of Distal Tibia  

PubMed Central

In order to provide scientific and empirical evidence for the clinical application of the polyaxial self-locking anatomical plate, 80 human tibias from healthy adults were scanned by spiral CT and their three-dimensional images were reconstructed using the surface shaded display (SSD) method. Firstly, based on the geometric data of distal tibia, a polyaxial self-locking anatomical plate for distal tibia was designed and constructed. Biomechanical tests were then performed by applying axial loading, 4-point bending, and axial torsion loading on the fracture fixation models of fresh cadaver tibias. Our results showed that variation in twisting angles of lateral tibia surface was found in various segments of the distal tibia. The polyaxial self-locking anatomical plate was constructed based on the geometry of the distal tibia. Compared to the conventional anatomical locking plate, the polyaxial self-locking anatomical plate of the distal tibia provides a better fit to the geometry of the distal tibia of the domestic population, and the insertion angle of locking screws can be regulated up to 30°. Collectively, this study assesses the geometry of the distal tibia and provides variable locking screw trajectory to improve screw-plate stability through the design of a polyaxial self-locking anatomical plate. PMID:25025051

Liang, Weiguo; Ye, Weixiong; Ye, Dongping; Zhou, Ziqiang; Chen, Zhiguang; Li, Aiguo; Xie, Zong-Han; Zhang, Lihai; Xu, Jiake

2014-01-01

93

The distal biceps tendon.  

PubMed

Distal biceps tendon ruptures continue to be an important injury seen and treated by upper extremity surgeons. Since the mid-1980s, the emphasis has been placed on techniques that limit complications or improve initial tendon-to-bone fixation strength. Recently, basic science research has expanded the knowledge base regarding the biceps tendon structure, footprint anatomy, and biomechanics. Clinical data have further delineated the results of conservative and surgical management of both partial and complete tears in acute or chronic states. The current literature on the distal biceps tendon is described in detail. PMID:23474326

Schmidt, Christopher C; Jarrett, Claudius D; Brown, Brandon T

2013-04-01

94

Ankle syndesmotic fixation using two screws: risk of injury to the perforating branch of the peroneal artery.  

PubMed

Trans-syndesmotic screws are commonly used to repair syndesmosis ruptures and stabilize the ankle joint. Just as with any surgery, the neurovascular structures can be compromised, causing complications. We evaluated the position of the perforating branch of the peroneal artery to define the risk of arterial compromise during placement of 2 trans-syndesmotic screws. In 37 cadaveric specimens, 2 trans-syndesmotic screws were inserted 2 and 4 cm proximal to the ankle joint. The distances between the perforating branch of the peroneal artery and the screws and the other anatomic landmarks were measured. Significant differences were calculated between the male and female limbs, and regression analysis was used to determine the significant associations between the tibial length and screw location. The perforating branch of the peroneal artery passed through the interosseous membrane 3.42 ± 0.6 cm proximal to the tibial plafond. The artery was located up to 4 mm from the superior and inferior screws 51.4% and 10.8% of the time, respectively. A greater percentage of male specimens displayed close proximity between the artery and the superior screw, and the distance of the artery from the distal fibula was statistically significant compared with the distance in the female specimens. Regression analysis revealed that the greater the tibial length, the closer the superior screw was to the artery, with a negative correlation discovered for the inferior screw. We concluded that superior screw placement increased the risk of injuring the perforating branch of the peroneal artery injury, and the likelihood of injuring the artery with the inferior screw increased as the length of the tibia decreased. PMID:24875967

Penera, Keith; Manji, Karim; Wedel, Mathew; Shofler, David; Labovitz, Jonathan

2014-01-01

95

Design and manufacturing of interlocked composite grids  

NASA Astrophysics Data System (ADS)

Composite grid structures made from pultruded unidirectional glass or carbon ribs provide unmatched performance/cost combination of any composite panels. A new manufacturing method for an ortho-grid using slotted joint and adhesive bonding ("Interlocked Composite Grid" or ICG) has been developed. The high structural performance of the grid is derived from uni-plies and the efficient load transfer mechanism. Pultrusion is one of the cheapest, fastest and reliable manufacturing processes for composite sections. Pultruded ribs, along with the simple assembly concept, lead to the low cost structure. Also, the flexibility in assembly eliminates the size limitation and large civil composite structures can be built. Two different equivalent stiffness models, the equivalent plate stiffness matrices and the equivalent engineering constants, have been formulated. The former model, more accurate than the equivalent engineering constants, includes the effects of the slots, the internal ribs, and the skins. The latter is used for establishing simple design guidelines. The equivalent stiffness models have been verified with numerical analysis and experimental data. The simplicity and flexibility of the design of an ICG has been demonstrated by sample design problems. Also, an approximate cost estimation rule has been established. ICG beams and panels have been built and tested under static and dynamic flexural loading. Superior mechanical properties, such as high damage tolerance, resilience, and durability have been demonstrated. The failure mode has been identified.

Han, Dongyup

96

An Articulating Tool for Endoscopic Screw Delivery  

E-print Network

This paper describes the development of an articulating endoscopic screw driver that can be used to place screws in osteosynthetic plates during thoracoscopic surgery. The device is small enough to be used with a 12 mm ...

Petrzelka, Joseph Edward

97

Hindfoot Valgus following Interlocking Nail Treatment for Tibial Diaphysis Fractures: Can the Fibula Be Neglected?  

PubMed Central

Purpose. We evaluated whether intramedullary nail fixation for tibial diaphysis fractures with concomitant fibula fractures (except at the distal one-third level) managed conservatively with an associated fibula fracture resulted in ankle deformity and assessed the impact of the ankle deformity on lower extremity function. Methods. Sixty middle one-third tibial shaft fractures with associated fibular fractures, except the distal one-third level, were included in this study. All tibial shaft fractures were anatomically reduced and fixed with interlocking intramedullary nails. Fibular fractures were managed conservatively. Hindfoot alignment was assessed clinically. Tibia and fibular lengths were compared to contralateral measurements using radiographs. Functional results were evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Foot and Ankle Disability Index Score (FADI). Results. Anatomic union, defined as equal length in operative and contralateral tibias, was achieved in 60 fractures (100%). Fibular shortening was identified in 42 fractures (68%). Mean fibular shortening was 1.2?cm (range, 0.5–2?cm). Clinical exams showed increased hindfoot valgus in 42 fractures (68%). The mean KOOS was 88.4, and the mean FADI score was 90. Conclusion. Fibular fractures in the middle or proximal one-third may need to be stabilized at the time of tibial intramedullary nail fixation to prevent development of hindfoot valgus due to fibular shortening. PMID:25544899

Uzun, Metin; Kara, Adnan; Ada?, Müjdat; Karslio?lu, Bülent; Bülbül, Murat; Beksaç, Burak

2014-01-01

98

Preventing loosening of implant abutment screws.  

PubMed

A procedure for using dimples inside the abutment screw cylinder above the screws and filling the holes with elastomeric impression material will prevent the screw-retained prosthesis from loosening. A modification of the procedure can also be used for angled abutments. PMID:8709025

Cavazos, E; Bell, F A

1996-05-01

99

Preventing loosening of implant abutment screws  

Microsoft Academic Search

A procedure for using dimples inside the abutment screw cylinder above the screws and filling the holes with elastomeric impression material will prevent the screw-retained prosthesis from loosening. A modification of the procedure can also be used for angled abutments.

Edmund Cavazos; Fred A Bell

1996-01-01

100

Biomechanical comparison of inside–outside screws, cables, and regular screws, using a sawbone model  

Microsoft Academic Search

Our aim was to conduct a biomechanical comparison of the pull-out strengths of inside–outside (I\\/O) screws, cables, and bone screws to determine whether I\\/O screws provide greater pull-out resistance than cables or bone screws, and their effectiveness with the screw diameter. There is no remarkable biomechanical experimental study comparing the I\\/O technique with conventional spinal techniques. The diameter of the

Yusuf Sukru Caglar; Fuat Torun; Thomas Glenn Pait; William Hogue; Melih Bozkurt; Serdar Özgen

2005-01-01

101

A screw propelling capsule robot  

Microsoft Academic Search

This paper presents a novel approach to active capsule robot, traversing in a tubular and compliant environment containing solid-liquid mixture. One of the application fields is active capsule endoscopy intended to navigate inside the gastrointestinal tract for diagnosis and therapy. This robot is driven by a screw impeller, which converts rotation to axial motion in two ways: one is through

Huajin Liang; Yisheng Guan; Zhiguang Xiao; Chao Hu; Zhiyong Liu

2011-01-01

102

[The pendulis appliance: a palatal miniscrew supported molar distalization device].  

PubMed

The maxillary molar distalization is a valuable therapeutic option in some clinical cases. Its biomechanics is challenging and difficult to obtain. Historically, various devices have been described offering successful solutions to this problem such as the Hilgers Pendulum Appliance (1992) and variants linked to mini screws which recently have shown interesting clinical potential. This article presents a new Pendulum variant using a miniscrew, the "pendulis". It follows the original concept (titanium-molybdenum alloy distalization springs and polymethyl-methacrylate pellet) but dental support is replaced by a single palatal miniscrew (median adults, para-median in children) to which the device is fixed by means of a metal welded cap easily positioned and removable by the practitioner. This allows for better control of the oral hygiene and completely controlled extraoral activation. Fabrication steps are described and instruction of use is illustrated with clinical documentation. PMID:25158749

Nappée-Miévilly, Magali; Nappée, François-Joseph; Kerbrat, Jean-Baptiste; Goudot, Patrick

2014-09-01

103

PLC-based interlock system for superconducting magnets  

SciTech Connect

Conventional interlock systems rely heavily on hard-wired electromagnetic relays. Although this approach is well understood and has proven to be reliable, several drawbacks plague the designer as well as the repairman. If larger systems have to be implemented in relay logic, the complexity limit is soon reached; the systems become too bulky, and wiring expenses sky-rocket; moreover, the intelligence of those designs is limited in such a way that desirable features such as self-tests have to be left out. Additionally, relay interlocks are inherently inflexible: if the configuration of the system they protect has to change, a disproportional amount of time, work and money has to be invested in order to adapt the hard-wiring of the interlock system to the new requirements. Repair work is often unnecessarily delayed due to the lack of adequate documentation.

Agostini, R.C.; Barker, L.; Hodgers, J.; Reagan, D.; Walz, H.V. (Stanford Univ., CA (USA))

1989-10-01

104

46 CFR 111.91-1 - Power, control, and interlock circuits.  

Code of Federal Regulations, 2011 CFR

...CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Elevators...91-1 Power, control, and interlock circuits. Each electric power, control, and interlock circuit of an elevator or dumbwaiter must...

2011-10-01

105

46 CFR 111.91-1 - Power, control, and interlock circuits.  

Code of Federal Regulations, 2013 CFR

...CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Elevators...91-1 Power, control, and interlock circuits. Each electric power, control, and interlock circuit of an elevator or dumbwaiter must...

2013-10-01

106

46 CFR 111.91-1 - Power, control, and interlock circuits.  

Code of Federal Regulations, 2010 CFR

...CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Elevators...91-1 Power, control, and interlock circuits. Each electric power, control, and interlock circuit of an elevator or dumbwaiter must...

2010-10-01

107

46 CFR 111.91-1 - Power, control, and interlock circuits.  

Code of Federal Regulations, 2012 CFR

...CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Elevators...91-1 Power, control, and interlock circuits. Each electric power, control, and interlock circuit of an elevator or dumbwaiter must...

2012-10-01

108

46 CFR 111.91-1 - Power, control, and interlock circuits.  

Code of Federal Regulations, 2014 CFR

...CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Elevators...91-1 Power, control, and interlock circuits. Each electric power, control, and interlock circuit of an elevator or dumbwaiter must...

2014-10-01

109

Design review report for the hydrogen interlock preliminary design  

SciTech Connect

This report documents the completion of a preliminary design review for the hydrogen interlock. The hydrogen interlock, a proposed addition to the Rotary Mode Core Sampling (RMCS) system portable exhauster, is intended to support core sampling operations in waste tanks requiring flammable gas controls. The objective of this review was to validate basic design assumptions and concepts to support a path forward leading to a final design. The conclusion reached by the review committee was that the design was acceptable and efforts should continue toward a final design review.

Corbett, J.E.

1996-01-01

110

Screw-fed pump system  

DOEpatents

A pump system includes a pump that includes a first belt and a second belt that are spaced apart from each other to provide generally straight sides of a passage there between. There is an inlet at one end of the passage and an outlet at an opposite end of the passage, with a passage length that extends between the inlet and the outlet. The passage defines a gap distance in a width direction between the straight sides at the passage inlet. A hopper includes an interior space that terminates at a mouth at the passage inlet. At least one screw is located within the interior space of the hopper and includes a screw diameter in the width direction that is less than or equal to the gap distance.

Sprouse, Kenneth M

2014-11-25

111

Helical screw expander evaluation project  

NASA Technical Reports Server (NTRS)

A one MW helical rotary screw expander power system for electric power generation from geothermal brine was evaluated. The technology explored in the testing is simple, potentially very efficient, and ideally suited to wellhead installations in moderate to high enthalpy, liquid dominated field. A functional one MW geothermal electric power plant that featured a helical screw expander was produced and then tested with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing, operation on two-phase geothermal fluids. The Project also produced a computer equipped data system, an instrumentation and control van, and a 1000 kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

Mckay, R.

1982-01-01

112

Description of a system for interlocking elevated temperature mechanical tests  

SciTech Connect

Long term mechanical creep and fatigue testing at elevated temperatures requires reliable systems with safeguards to prevent destruction of equipment, loss of data and negative environmental impacts. Toward this goal, a computer controlled system has been developed and built for interlocking tests run on elevated temperature mechanical test facilities. Sensors for water flow, water pressure, water leakage, temperature, power and hydraulic status are monitored to control specimen heating equipment through solid state relays and water solenoid valves. The system is designed to work with the default interlocks present in the RF generators and mechanical tests systems. Digital hardware consists of two National Instruments 1/0 boards mounted in a Macintosh IIci computer. Software is written in National Instruments LabVIEW. Systems interlocked include two MTS closed loop servo controlled hydraulic test frames, one with an RF generator and one with both an RF generator and a quartz lamp furnace. Control for individual test systems is modularized making the addition of more systems simple. If any of the supporting utilities fail during tests, heating systems, chill water and hydraulics are powered down, minimizing specimen damage and eliminating equipment damage. The interlock control is powered by an uninterruptible power supply. Upon failure the cause is documented in an ASCII file.

Schmale, D.T.; Poulter, G.A.

1995-07-01

113

B & P Junction Substation & Interlocking Tower; Howard Street ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

B & P Junction Substation & Interlocking Tower; Howard Street Bridge. Baltimore, Baltimore City, MD. Sec. 1201, MP 95.85 - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

114

How Does Learning Intent Affect Interlocking Directorates Dynamic?  

ERIC Educational Resources Information Center

Purpose: Literature on board interlocks agrees that these inter-organizational ties are effective channels to exchange information and share knowledge. However, studies that consider the nature and the amount of knowledge that firms exchange are still relatively absent. Filling this gap, this paper aims to identify four types of mechanisms that…

Simoni, Michele; Caiazza, Rosa

2012-01-01

115

38. Shell Interlocking Circuit Breaker Gantry & Substation. New Rochelle, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

38. Shell Interlocking Circuit Breaker Gantry & Substation. New Rochelle, Westchester Co., NY. Sec. 4207, MP 19.10. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York, New York County, NY

116

39. Shell Interlocking Circuit Breaker Gantry & Substation. New Rochelle, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

39. Shell Interlocking Circuit Breaker Gantry & Substation. New Rochelle, Westchester Co., NY. Sec. 4207, MP 19.10. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York, New York County, NY

117

40. Shell Interlocking Circuit Breaker Gantry & Substation. New Rochelle, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

40. Shell Interlocking Circuit Breaker Gantry & Substation. New Rochelle, Westchester Co., NY. Sec. 4207, MP 19.10. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York, New York County, NY

118

59. Fair Street Interlocking & circuit breaker gantry. New Haven, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

59. Fair Street Interlocking & circuit breaker gantry. New Haven, New Haven Co., CT. Sec. 9108, MP 71.90. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

119

58. Fair Street Interlocking & circuit breaker gantry. New Haven, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

58. Fair Street Interlocking & circuit breaker gantry. New Haven, New Haven Co., CT. Sec. 9108, MP 71.90. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

120

60. Fair Street Interlocking & circuit breaker gantry. New Haven, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

60. Fair Street Interlocking & circuit breaker gantry. New Haven, New Haven Co., CT. Sec. 9108, MP 71.90. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

121

Axial cyclic behavior of the bone–screw interface  

Microsoft Academic Search

Screw fixation strength is investigated by using a pullout test. Despite many screw pullout studies, the effects of loading rate on the pullout behavior of pedicle screws are not known. The objective of this study was to assess the effects of loading rate on the pullout stiffness and strength of pedicle screws. Sixty pedicle screws were inserted in foam blocks

Serkan ?nceo?lu; Mike Ehlert; Atilla Akbay; Robert F. McLain

2006-01-01

122

Biomechanical evaluation of a medial knee reconstruction with comparison of bioabsorbable interference screw constructs and optimization with a cortical button.  

PubMed

Current fixation techniques in medial knee reconstructions predominantly utilize interference screws alone for soft tissue graft fixation. The use of concurrent fixation techniques as part of a hybrid fixation technique has also been suggested to strengthen soft tissue fixation, although these hybrid fixation techniques have not been biomechanically validated. The purpose was to biomechanically evaluate two distal tibial superficial MCL graft fixation techniques that consisted of an interference screw alone and in combination with a cortical button. Furthermore, the aim was to compare interference screws of different constructs. Twenty-four porcine tibias (average bone mineral density of 1.3 ± 0.2 g/cm(2); range, 1.0-1.6 g/cm(2), measured by DEXA scan) were divided into 4 groups of six specimens each. Group Ia consisted of a 7 × 23-mm poly-L-lactide (PLLA) interference screw. Group Ib utilized a PLLA interference screw in combination with a cortical button. Group IIa consisted of a 7 × 23-mm composite 70% poly(L-lactide-co-D, L-lactide) and 30% biphasic calcium phosphate (BCP) interference screw. Group IIb also utilized a composite interference screw in combination with a cortical button. The specimens were biomechanically tested with cyclic (500 cycles, 50-250 N, 1 Hz) and load-to-failure (20 mm/min) parameters. During cyclic loading, a significant increase in stiffness was seen for the PLLA hybrid 29.6 (±6.9) N/mm fixation compared to the PLLA screw-only 21.2 (±3.8) N/mm group (P < 0.05). Failure loads were 407.8 (±77.9) N for the composite screw, 445 (±72.2) N for the PLLA screw-only, 473.9 (±69.6) N for the composite hybrid fixation, and 511.0 (±78.5) N for the PLLA hybrid fixation. The PLLA screw alone was found to provide adequate fixation for a superficial MCL reconstruction, and the use of a cortical suture button combined with the PLLA screw resulted in a stiffer fixation during cyclic loading. The current reconstruction superficial MCL graft fixation technique utilizing a PLLA interference screw alone serves as an adequate recreation of the native tibial superficial MCL strength. In addition, a hybrid fixation with a cortical button which lends additional cyclic stiffness to its fixation would be advisable for use in suboptimal fixation cases. PMID:20563561

Wijdicks, Coen A; Brand, Emily J; Nuckley, David J; Johansen, Steinar; LaPrade, Robert F; Engebretsen, Lars

2010-11-01

123

Assessment of different screw augmentation techniques and screw designs in osteoporotic spines.  

PubMed

This is an experimental study on human cadaver spines. The objective of this study is to compare the pullout forces between three screw augmentation methods and two different screw designs. Surgical interventions of patients with osteoporosis increase following the epidemiological development. Biomechanically the pedicle provides the strongest screw fixation in healthy bone, whereas in osteoporosis all areas of the vertebra are affected by the disease. This explains the high screw failure rates in those patients. Therefore PMMA augmentation of screws is often mandatory. This study involved investigation of the pullout forces of augmented transpedicular screws in five human lumbar spines (L1-L4). Each spine was treated with four different methods: non-augmented unperforated (solid) screw, perforated screw with vertebroplasty augmentation, solid screw with vertebroplasty augmentation and solid screw with balloon kyphoplasty augmentation. Screws were augmented with Polymethylmethacrylate (PMMA). The pullout forces were measured for each treatment with an Instron testing device. The bone mineral density was measured for each vertebra with Micro-CT. The statistical analysis was performed with a two-sided independent student t test. Forty screws (10 per group and level) were inserted. The vertebroplasty-augmented screws showed a significant higher pullout force (mean 918.5 N, P = 0.001) than control (mean 51 N), the balloon kyphoplasty group did not improve the pullout force significantly (mean 781 N, P > 0.05). However, leakage occurred in some cases treated with perforated screws. All spines showed osteoporosis on Micro-CT. Vertebroplasty-augmented screws, augmentation of perforated screws and balloon kyphoplasty augmented screws show higher pullout resistance than non-augmented screws. Significant higher pullout forces were only reached in the vertebroplasty augmented vertebra. The perforated screw design led to epidural leakage due to the position of the perforation in the screw. The position of the most proximal perforation is critical, depending on screw design and proper insertion depth. Nevertheless, using a properly designed perforated screw will facilitate augmentation and instrumentation in osteoporotic spines. PMID:18781342

Becker, S; Chavanne, A; Spitaler, R; Kropik, K; Aigner, N; Ogon, M; Redl, H

2008-11-01

124

Complex fractures of the distal radius treated with angular stability plates  

Microsoft Academic Search

Complex fractures of the distal radius are articular lesions and comminuted at the level of the epiphysis and metaphysis.\\u000a Their treatment is difficult and in most cases surgical. Of all the different osteosynthesis methods available, internal fixation\\u000a with plate and screws is the most commonly used. In particular, angular stability plates are superior in terms of rigidity\\u000a and stability to

Marco Frattini; Giovanni Soncini; Maurizio Corradi; Bruno Panno; Silvio Tocco; Francesco Pogliacomi

2009-01-01

125

Synovial metallosis resulting from intraarticular intramedullary nailing of a distal femoral nonunion.  

PubMed

An 80-year-old man sustained a T-shaped supracondylar fracture of the femur associated with distal one-third shaft comminution. Initial failure of a 95 degrees angle blade plate was followed by insertion of an intraarticular intramedullary nail stabilized with static locking-screw fixation. A second failure of the implant was treated by extraarticular tension band condylar buttress plate osteosynthesis. Severe knee synovial metallosis was found at the time of removal of the intraarticular nail device. PMID:8377040

Johnson, E E; Marroquin, C E; Kossovsky, N

1993-01-01

126

Distal femoral osteotomy.  

PubMed

Osteotomies around the knee are well-recognized treatments for unloading the affected compartment in cases of lower limb malalignment. There are few papers in the literature describing the outcomes of distal femoral osteotomy (DFO), as compared with the studies reporting on high tibial osteotomy (HTO), probably because valgus malalignment is less common than the varus one. There is still debate as to what the correct indication is and which surgical techniques lead to the best outcomes in performing a DFO. Besides, it is still controversial whether patellofemoral arthritis should be considered as a contraindication to performing a DFO, as well as in HTO. In this article, we will summarize the indications for DFO, the surgical techniques reported in the literature, and their outcomes. PMID:25142271

Rosso, Federica; Margheritini, Fabrizio

2014-12-01

127

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

128

21 CFR 872.4880 - Intraosseous fixation screw or wire.  

Code of Federal Regulations, 2011 CFR

...false Intraosseous fixation screw or wire. 872.4880 Section...4880 Intraosseous fixation screw or wire. (a) Identification. An intraosseous fixation screw or wire is a metal device intended...be inserted into fractured jaw bone segments to prevent their...

2011-04-01

129

21 CFR 872.4880 - Intraosseous fixation screw or wire.  

Code of Federal Regulations, 2013 CFR

...false Intraosseous fixation screw or wire. 872.4880 Section...4880 Intraosseous fixation screw or wire. (a) Identification. An intraosseous fixation screw or wire is a metal device intended...be inserted into fractured jaw bone segments to prevent their...

2013-04-01

130

21 CFR 872.4880 - Intraosseous fixation screw or wire.  

Code of Federal Regulations, 2014 CFR

...false Intraosseous fixation screw or wire. 872.4880 Section...4880 Intraosseous fixation screw or wire. (a) Identification. An intraosseous fixation screw or wire is a metal device intended...be inserted into fractured jaw bone segments to prevent their...

2014-04-01

131

21 CFR 872.4880 - Intraosseous fixation screw or wire.  

Code of Federal Regulations, 2010 CFR

...false Intraosseous fixation screw or wire. 872.4880 Section...4880 Intraosseous fixation screw or wire. (a) Identification. An intraosseous fixation screw or wire is a metal device intended...be inserted into fractured jaw bone segments to prevent their...

2010-04-01

132

21 CFR 872.4880 - Intraosseous fixation screw or wire.  

Code of Federal Regulations, 2012 CFR

...false Intraosseous fixation screw or wire. 872.4880 Section...4880 Intraosseous fixation screw or wire. (a) Identification. An intraosseous fixation screw or wire is a metal device intended...be inserted into fractured jaw bone segments to prevent their...

2012-04-01

133

Reducing radiation exposure in intra-medullary nailing procedures: Intra-medullary endo-transilluminating (iMET)  

E-print Network

the bone cavity near a targeted screw hole, a portion of the light is able to penetrate through the hole was inserted into the medullary bone cavity in order to detect the distal interlocking screw holes. The light penetrates out of the bone surface, revealing the position of the screw hole, and this allows the subsequent

134

In vitro biomechanical comparison of solid and tubular interlocking nails in neonatal bovine femurs.  

PubMed

This study biomechanically evaluates solid and tubular interlocking nails in bovine neonatal femurs. Paired femurs from 40 neonatal dairy calves were obtained for mechanical testing. Intact femurs and four combinations of experimentally manipulated femurs (intact or ostectomized femurs with either a solid or tubular interlocking nail) were tested in craniocaudal and lateromedial bending, eccentric axial compression, and external torsion to evaluate composite rigidity, local/gap stiffness, and load to failure (compression and torsion only). In torsional composite rigidity, femurs with tubular interlocking nails were more complaint than intact femurs or intact femurs with solid interlocking nails (P < .001). Ostectomized femurs with solid interlocking nails were similar to intact femurs with tubular interlocking nails. Within femurs with tubular interlocking nails, ostectomized femurs were more compliant than intact femurs (P < .0001). In craniocaudal and lateromedial bending rigidity, ostectomized femurs were more complaint than intact femurs, regardless of interlocking nail type (P < .001). Within ostectomized femurs, tubular interlocking nails were more complaint than solid interlocking nails in craniocaudal bending (P < .05) and there was a similar trend in lateromedial bending (P = .06). In eccentric axial compression, local/gap stiffness was significantly greater in intact femurs compared with intact femurs with solid (48% of intact bone) or tubular (45% of intact bone) interlocking nails and ostectomized femurs with solid (18% of intact bone) or tubular (11% of intact bone) interlocking nails (P < .0001). In torsional testing, local/gap stiffness was not significantly different between intact femurs and intact femurs with interlocking nails, but was significantly lower in ostectomized femurs with solid (2% of intact bone) and tubular (0.2% of intact bone) interlocking nails (P < .0001).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7653038

Trostle, S S; Wilson, D G; Dueland, R T; Markel, M D

1995-01-01

135

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

136

Unifying Screw Geometry and Matrix Transformations  

Microsoft Academic Search

Transformation matrices are widely used in robotics for kinematic analysis and trajectory planning. Screw geome try offers better geometric insight into such analyses. In this article we unify the two approaches through the use of invariant properties of orthogonal matrices under simi larity transformations. We give a complete expression for the finite screw motion in terms of the entires of

A. E. Samuel; P. R. McAree; K. H. Hunt

1991-01-01

137

NATIONAL SYNCHROTRON LIGHT SOURCE MEDICAL PERSONNEL PROTECTION INTERLOCK  

SciTech Connect

This report is founded on reports written in April 1987 by Robert Hettel for angiography operations at the Stanford Synchrotron Research Laboratory (SSRL) and a subsequent report covering angiography operations at the National Synchrotron Light Source (NSLS); BNL Informal Report 47681, June 1992. The latter report has now been rewritten in order to accurately reflect the design and installation of a new medical safety system at the NSLS X17B2 beamline Synchrotron Medical Research Facility (SMERF). Known originally as the Angiography Personnel Protection Interlock (APPI), this system has been modified to incorporate other medical imaging research programs on the same beamline and thus the name has been changed to the more generic Medical Personnel Protection Interlock (MPPI). This report will deal almost exclusively with the human imaging (angiography, bronchography, mammography) aspects of the safety system, but will briefly explain the modular aspects of the system allowing other medical experiments to be incorporated.

BUDA,S.; GMUR,N.F.; LARSON,R.; THOMLINSON,W.

1998-11-03

138

Engineering interlocking DNA rings with weak physical interactions  

NASA Astrophysics Data System (ADS)

Catenanes are intriguing molecular assemblies for engineering unique molecular devices. The resident rings of a catenane are expected to execute unhindered rotation around each other, and to do so, they must have weak physical interactions with each other. Due to sequence programmability, DNA has become a popular material for nanoscale object engineering. However, current DNA catenanes, particularly in the single-stranded (ss) form, are synthesized through the formation of a linking duplex, which makes them less ideal as mobile elements for molecular machines. Herein we adopt a random library approach to engineer ssDNA [2] catenanes (two interlocked DNA rings) without a linking duplex. Results from DNA hybridization, double-stranded catenane synthesis and rolling circle amplification experiments signify that representative catenanes have weak physical interactions and are capable of operating as independent units. Our findings lay the foundation for exploring free-functioning interlocked DNA rings for the design of elaborate nanoscale machines based on DNA.

Wu, Zai-Sheng; Shen, Zhifa; Tram, Kha; Li, Yingfu

2014-06-01

139

Design of responsive materials using topologically interlocked elements  

NASA Astrophysics Data System (ADS)

In this work we present a novel approach to designing responsive structures by segmentation of monolithic plates into an assembly of topologically interlocked building blocks. The particular example considered is an assembly of interlocking osteomorphic blocks. The results of this study demonstrate that the constraining force, which is required to hold the blocks together, can be viewed as a design parameter that governs the bending stiffness and the load bearing capacity of the segmented structure. In the case where the constraining forces are provided laterally using an external frame, the maximum load the assembly can sustain and its stiffness increase linearly with the magnitude of the lateral load applied. Furthermore, we show that the segmented plate with integrated shape memory wires employed as tensioning cables can act as a smart structure that changes its flexural stiffness and load bearing capacity in response to external stimuli, such as heat generated by the switching on and off an electric current.

Molotnikov, A.; Gerbrand, R.; Qi, Y.; Simon, G. P.; Estrin, Y.

2015-02-01

140

Twin screw granulation: steps in granule growth.  

PubMed

The present work focuses on the study of the progression of granules in different compartments along the length of screws in a twin screw granulator (TSG). The effects of varying powder feed rate; liquid to solid ratio and viscosity of granulation liquid on properties of granules was studied. The bigger granules produced at the start of the process were found to change in terms of size, shape and strength along the screw length at all the conditions investigated. The granules became more spherical and their strength increased along the screw length. Tracer granules were also introduced in order to understand the role of kneading and conveying elements in the TSG. The kneading elements promoted consolidation and breakage while the conveying elements led to coalescence, breakage and some consolidation. The results presented here help to provide a qualitative and quantitative understanding of the twin screw granulation process. PMID:22960611

Dhenge, Ranjit M; Cartwright, James J; Hounslow, Michael J; Salman, Agba D

2012-11-15

141

Availability Analysis of the Ventilation Stack CAM Interlock System  

SciTech Connect

Ventilation Stack Continuous Air Monitor (CAM) Interlock System failure modes, failure frequencies, and system availability have been evaluated for the RPP. The evaluation concludes that CAM availability is as high as assumed in the safety analysis and that the current routine system surveillance is adequate to maintain this availability credited in the safety analysis, nor is such an arrangement predicted to significantly improve system availability.

YOUNG, J.

2000-08-09

142

Board Interlocks and the Diffusion of Strategic Actions  

E-print Network

BOARD INTERLOCKS AND THE DIFFUSION OF STRATEGIC ACTIONS A Dissertation by NAI HUA LAMB Submitted to the Office of Graduate and Professional Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of DOCTOR OF PHILOSOPHY Chair of Committee, Laszlo Tihanyi Committee Members, Michael A. Hitt R. Duane Ireland Victor Willson Head of Department, Ricky W. Griffin May 2014 Major Subject: Management Copyright 2014 Nai Hua Lamb ii...

Lamb, Nai Hua

2014-04-10

143

Distal ulna hook plate fixation for unstable distal ulna fracture associated with distal radius fracture.  

PubMed

The significance of distal ulna fractures is often undermined, which can result in inadequate treatment compared with fractures of the radius, the ulna's larger counterpart. However, little guidance exists in the current literature on how to manage distal ulna head or neck fractures and intra-articular ulna head fractures. Therefore, the purpose of this retrospective study was to evaluate the outcomes of distal ulna hook plate fixation for the treatment of an unstable distal ulna fracture associated with a distal radius fracture. Twenty-five patients with unstable distal ulna fractures who underwent stable fixation for an associated distal radius fracture were included in the study. All patients achieved satisfactory reduction and bony union. Average final motion was as follows: wrist flexion, 72° (range, 60°-85°); extension, 69° (range, 65°-80°); pronation, 77° (range, 55°-95°); supination, 82° (range, 65°-90°); ulnar deviation, 35° (range, 15°-50°); and radial deviation, 24° (range, 10°-40°). Average postoperative grip strength was 28 kg (range, 22-30 kg) and was 91% (range, 71%-100%) in the cases in which the dominant hand was injured and 80% (range, 65%-100%) in the cases in which the nondominant hand was injured. Average postoperative modified Mayo wrist score and Disabilities of the Arm, Shoulder and Hand score was 87 points (range, 65-100 points) and 14 points (range, 0-54 points), respectively. Chronic instability of the distal radioulnar joint was not encountered in any patient. Thus, the study demonstrated that distal ulna hook plate fixation for the treatment of unstable distal ulna fractures can achieve healing with good alignment, satisfactory function, and minimal transient morbidity. PMID:22955402

Lee, Sang Ki; Kim, Kap Jung; Park, Ju Sang; Choy, Won Sik

2012-09-01

144

3D Mapping of Safe and Danger Zones in the Maxilla and Mandible for the Placement of Intermaxillary Fixation Screws  

PubMed Central

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

145

Distal convoluted tubule.  

PubMed

The distal convoluted tubule (DCT) is a short nephron segment, interposed between the macula densa and collecting duct. Even though it is short, it plays a key role in regulating extracellular fluid volume and electrolyte homeostasis. DCT cells are rich in mitochondria, and possess the highest density of Na(+)/K(+)-ATPase along the nephron, where it is expressed on the highly amplified basolateral membranes. DCT cells are largely water impermeable, and reabsorb sodium and chloride across the apical membrane via electroneurtral pathways. Prominent among this is the thiazide-sensitive sodium chloride cotransporter, target of widely used diuretic drugs. These cells also play a key role in magnesium reabsorption, which occurs predominantly, via a transient receptor potential channel (TRPM6). Human genetic diseases in which DCT function is perturbed have provided critical insights into the physiological role of the DCT, and how transport is regulated. These include Familial Hyperkalemic Hypertension, the salt-wasting diseases Gitelman syndrome and EAST syndrome, and hereditary hypomagnesemias. The DCT is also established as an important target for the hormones angiotensin II and aldosterone; it also appears to respond to sympathetic-nerve stimulation and changes in plasma potassium. Here, we discuss what is currently known about DCT physiology. Early studies that determined transport rates of ions by the DCT are described, as are the channels and transporters expressed along the DCT with the advent of molecular cloning. Regulation of expression and activity of these channels and transporters is also described; particular emphasis is placed on the contribution of genetic forms of DCT dysregulation to our understanding. © 2015 American Physiological Society. Compr Physiol 5: 45-98, 2015. PMID:25589264

McCormick, James A; Ellison, David H

2015-01-01

146

Interlock systems using programmable sequence controllers and a monitoring system of the Photon Factory beamlines  

NASA Astrophysics Data System (ADS)

Fully utilizing programmable sequence controllers, interlock systems for the Photon Factory beamlines were newly designed and constructed for providing the reliable and versatile control logic that is required for beamline characteristics. The systems, accommodated with radiation safety and vacuum interlock logic as well as protection logic for various components against heat and radiation damage, are in operation on eight beamlines. A centralized monitoring system, to which all interlock systems for the beamlines are connected through optical fiber links, was constructed for simultaneously monitoring the operation status of the interlock systems. Individual operations of each interlock system are also controlled by the monitoring system. Log data collected by the monitoring system are summarized and analyzed in order to provide the necessary information for smooth and safe operation as well as for further improvements of the beamlines. The interlock and the monitoring systems are described along with operational remarks.

Satow, Yoshinori; Ito, Kenji; Kosuge, Takashi

1989-07-01

147

Complex fractures of the distal radius treated with angular stability plates.  

PubMed

Complex fractures of the distal radius are articular lesions and comminuted at the level of the epiphysis and metaphysis. Their treatment is difficult and in most cases surgical. Of all the different osteosynthesis methods available, internal fixation with plate and screws is the most commonly used. In particular, angular stability plates are superior in terms of rigidity and stability to conventional volar and dorsal plates. DVR plate has these mechanical characteristics, and its low profile has reduced frictions with surrounding soft tissues. For these reasons, this device implanted through a single volar approach, can stabilize the majority of volarly and dorsally displaced unstable distal radius fractures. In this study, 48 patients, affected by complex fractures of the distal radius treated with DVR volar plates, were assessed by the Mayo modified wrist score, the Italian version of the disability of the arm, shoulder and hand. The satisfactory results observed confirm the efficacy of this device. PMID:19711152

Frattini, Marco; Soncini, Giovanni; Corradi, Maurizio; Panno, Bruno; Tocco, Silvio; Pogliacomi, Francesco

2009-12-01

148

Outcome of unstable distal radius fractures treated with open reduction and internal fixation versus external fixation.  

PubMed

The objective of this study was to compare the clinical results of unstable distal radius fractures treated with ORIF with plate and screws compared to EF. Patients with unstable distal radius fractures treated with ORIF or EF from January 2005 to December 2010 were reviewed in terms of the Modified Mayo Wrist Score, range of motion, pain, grip strength, and radiologic parameters. Results showed that there was no difference in the Modified Mayo Wrist Score between ORIF (17 patients) and EF (11 patients) (p = 0.07). The ORIF group had better wrist flexion, wrist extension, pronation and supination compared to the EF group (p < 0.05). There were no significant differences in terms of radial and ulnar deviation, grip strength, pain and postoperative radiologic parameters (p < 0.05). Better wrist flexion, wrist extension and forearm rotation can be expected in ORIF compared to EF in the management of unstable distal radius fractures. PMID:22745080

Estrella, Emmanuel P; Panti, Paulo L

2012-01-01

149

The biomechanics of guided growth: does screw size, plate size, or screw configuration matter?  

PubMed

Guided growth with the eight-plate is a commonly used technique to correct angular limb deformities in children. However, the optimal combination of plate size, screw size, and screw configuration has not been determined. Using osteotomized femoral sawbones and a rail frame, we developed a growth model to examine the effect of these variables at 6-month, 12-month, and 18-month growth increments. The mean annual coronal plane change was 11.3°. Screw size and plate size were not associated with the rate of angular correction. Screw configuration was important, with parallel screws resulting in optimal correction at all time points compared with divergent screws (P<0.05). PMID:24322536

Schoenleber, Scott J; Iobst, Christopher A; Baitner, Avi; Standard, Shawn C

2014-03-01

150

Distal biceps tendon injuries--current treatment options.  

PubMed

Three percent of all biceps tendon ruptures occur at the distal aspect, where the tendon inserts into the radial tuberosity. Distal bicep tendon ruptures typically occur in middle-aged males after an eccentric extension load is applied to the elbow. Patients usually complain of a sudden, sharp, and painful tearing sensation in the antecubital region, with a palpable defect. The biceps squeeze and hook tests are specific maneuvers by which to diagnose distal biceps ruptures on physical examination. Magnetic resonance imaging (MRI) or ultrasound maybe be helpful to distinguish between partial and complete tears. Anatomic studies suggest there are two distinct insertions for the short and long heads of the distal biceps. The short head may be a more powerful flexor, and the long head may be a more powerful supinator. Nonoperative treatment typically results in loss of flexion and supination strength and endurance. Early anatomic re-attachment is the goal. Surgical approaches include one- or two-incision techniques, and tendon fixation methods include the use of suture anchors, bone tunnels, an endobutton, or biotenodesis screws. Biomechanical studies have shown that endobuttons have higher load-to-failure strengths, compared to the other fixation methods. However, clinical studies have demonstrated that patients do well regardless of surgical approach or fixation method. Possible complications include nerve injuries, heterotopic ossification, postoperative fracture, tendon rerupture, complex regional pain syndrome, and wound infection. Partial ruptures are significantly less common and initially can be treated conservatively. Chronic tears are more difficult to treat because of possible tendon retraction and poor tissue quality. Tendon grafts using semitendinosus, fascia lata, hamstring, Achilles (calcaneal), or flexor carpi radialis have been successfully used for length restoration in these cases. PMID:20632985

Quach, Tony; Jazayeri, Reza; Sherman, Orrin H; Rosen, Jeffrey E

2010-01-01

151

Metal artifacts from titanium and steel screws in CT, 1.5T and 3T MR images of the tibial Pilon: a quantitative assessment in 3D.  

PubMed

Radiographs are commonly used to assess articular reduction of the distal tibia (pilon) fractures postoperatively, but may reveal malreductions inaccurately. While magnetic resonance imaging (MRI) and computed tomography (CT) are potential three-dimensional (3D) alternatives they generate metal-related artifacts. This study aims to quantify the artifact size from orthopaedic screws using CT, 1.5T and 3T MRI data. Three screws were inserted into one intact human cadaver ankle specimen proximal to and along the distal articular surface, then CT, 1.5T and 3T MRI scanned. Four types of screws were investigated: titanium alloy (TA), stainless steel (SS) (Ø =3.5 mm), cannulated TA (CTA) and cannulated SS (CSS) (Ø =4.0 mm, Ø empty core =2.6 mm). 3D artifact models were reconstructed using adaptive thresholding. The artifact size was measured by calculating the perpendicular distance from the central screw axis to the boundary of the artifact in four anatomical directions with respect to the distal tibia. The artifact sizes (in the order of TA, SS, CTA and CSS) from CT were 2.0, 2.6, 1.6 and 2.0 mm; from 1.5T MRI they were 3.7, 10.9, 2.9, and 9 mm; and 3T MRI they were 4.4, 15.3, 3.8, and 11.6 mm respectively. Therefore, CT can be used as long as the screws are at a safe distance of about 2 mm from the articular surface. MRI can be used if the screws are at least 3 mm away from the articular surface except for SS and CSS. Artifacts from steel screws were too large thus obstructed the pilon from being visualised in MRI. Significant differences (P<0.05) were found in the size of artifacts between all imaging modalities, screw types and material types, except 1.5T versus 3T MRI for the SS screws (P=0.063). CTA screws near the joint surface can improve postoperative assessment in CT and MRI. MRI presents a favourable non-ionising alternative when using titanium hardware. Since these factors may influence the quality of postoperative assessment, potential improvements in operative techniques should be considered. PMID:24914417

Radzi, Shairah; Cowin, Gary; Robinson, Mark; Pratap, Jit; Volp, Andrew; Schuetz, Michael A; Schmutz, Beat

2014-06-01

152

Osteosynthesis in Fractures of the Distal Third of Humeral Diaphysis  

PubMed Central

ABSTRACT Objectives: To compare the clinical results of osteosynthesis with plate and screws versus anterograde locked intramedullary nail in fractures of the distal third of humeral diaphysis. Material and methods: 184 patients with fractures of the distal third of humeral diaphysis were included in a prospective study. 82 patients underwent open reduction and internal fixation with plate and screws (Group 1), while in 102 cases, closed reduction and osteosynthesis with locked intramedullary nail was performed (Group 2). The 2 groups were similar in terms of age and gender distribution and pattern of fractures. The function of shoulder and elbow were assessed using the Oxford Shoulder Score (OSS) and Oxford Elbow Score (OES). Operating time, duration of hospital stay, complications and moment of union were recorded. Outcomes: 6 months after surgery the average OSS was 44.42 in Group I and 40.23 in Group II, while the mean OES was 40.88 in Group I and 46.54 in Group II. The average duration of the surgical procedure was 87 min in Group1 and 43 min in the nail group (p<0.001).The mean duration of hospital stay was 2.6 days in Group 1 and 1.8 days in Group 2 (p<0.05). The rate of non-unions was 3.66% in the plate group and 2.94% in the retrograde nail group (p>0.05). Conclusions: The clinical results of the 2 methods of osteosynthesis were similar, but the operating time and the duration of hospital stay were longer after plate osteosynthesis. Shoulder function was slightly impaired in the nail group but not statistically significant. PMID:25553125

RADULESCU, Radu; BADILA, Adrian; NUTIU, Octavian; JAPIE, Ionut; TERINTE, Silvia; RADULESCU, Dragos; MANOLESCU, Robert

2014-01-01

153

Semi-Empirical Screw Compressor Chiller Model  

E-print Network

A screw chiller model which is based on a first principles, semi-empirical analysis that describes the system performance based on observations of the thermodynamic processes is developed. This model is a modified method to empirically derive...

Nelson, I. C.; Culp, C.; Graves, R. D.

154

Rotordynamics of Twin-Screw Pumps  

E-print Network

rotordynamic behavior. The work in this dissertation presents: (1) the axisymmetric structural model of the rotors (2) the proposed dynamic pressure model, (3) the screw pump rotor response, (4) the experimental validation of the dynamic pressure model...

Aboel Hassan Muhammed, Ameen

2013-02-26

155

National Synchrotron Light Source medical personnel protection interlock  

SciTech Connect

This report is founded on reports written in April 1987 by Robert Hettel for angiography operations at the Stanford Synchrotron Research Laboratory (SSRL) and a subsequent report covering angiography operations at the National Synchrotron Light Source (NSLS); BNL Informal Report 47681, June 1992. The latter report has now been rewritten in order to accurately reflect the design and installation of a new medical safety system at the NSLS X17B2 beamline Synchrotron Medical Research Facility (SMERF). Known originally as the Angiography Personnel Protection Interlock (APPI), this system has been modified to incorporate other medical imaging research programs on the same beamline and thus the name has been changed to the more generic Medical Personnel Protection Interlock (MPPI). This report will deal almost exclusively with the human imaging (angiography, bronchography, mammography) aspects of the safety system, but will briefly explain the modular aspects of the system allowing other medical experiments to be incorporated. This MPPI report is organized such that the level of detail changes from a general overview to detailed engineering drawings of the hardware system. The general overview is presented in Section 1.0, MPPI Operational Mode and Procedures. The various MPPI components are described in detail in Section 2.0. Section 3.0 presents some simplified logic diagrams and accompanying text. This section was written to allow readers to become familiar with the logic system without having to work through the entire set of detailed engineering drawings listed in the Appendix. Detailed logic specifications are given in Section 4.0. The Appendix also contains copies of the current MPPI interlock test procedures for Setup and Patient Modes.

Buda, S.; Gmuer, N.F.; Larson, R.; Thomlinson, W.

1998-11-01

156

Additional Drive Circuitry for Piezoelectric Screw Motors  

NASA Technical Reports Server (NTRS)

Modules of additional drive circuitry have been developed to enhance the functionality of a family of commercially available positioning motors (Picomotor . or equivalent) that provide linear motion controllable, in principle, to within increments .30 nm. A motor of this type includes a piezoelectric actuator that turns a screw. Unlike traditional piezoelectrically actuated mechanisms, a motor of this type does not rely on the piezoelectric transducer to hold position: the screw does not turn except when the drive signal is applied to the actuator.

Smythe, Robert; Palmer, Dean; Gursel, Yekta; Reder, Leonard; Savedra, Raymond

2004-01-01

157

Percutaneous Computer Assisted Iliosacral Screwing: Clinical Validation  

Microsoft Academic Search

\\u000a This paper describes the clinical validation of an image-guided system for the percutaneous placement of iliosacral screws.\\u000a The goals of the approach are to decrease surgical complications, with a percutaneous technique, and to increase the accuracy\\u000a and security of screw positioning thanks to a computer assisted system. Pre-operative planning is performed on CT-scan images\\u000a and a 3D model is built.

Lionel Carrat; Jerome Tonetti; Philippe Merloz; Jocelyne Troccaza

2000-01-01

158

Photovoltaic module and interlocked stack of photovoltaic modules  

DOEpatents

One embodiment relates to an arrangement of photovoltaic modules configured for transportation. The arrangement includes a plurality of photovoltaic modules, each photovoltaic module including a frame. A plurality of individual male alignment features and a plurality of individual female alignment features are included on each frame. Adjacent photovoltaic modules are interlocked by multiple individual male alignment features on a first module of the adjacent photovoltaic modules fitting into and being surrounded by corresponding individual female alignment features on a second module of the adjacent photovoltaic modules. Other embodiments, features and aspects are also disclosed.

Wares, Brian S.

2014-09-02

159

Photovoltaic module and interlocked stack of photovoltaic modules  

DOEpatents

One embodiment relates to an arrangement of photovoltaic modules configured for transportation. The arrangement includes a plurality of photovoltaic modules, each photovoltaic module including a frame having at least a top member and a bottom member. A plurality of alignment features are included on the top member of each frame, and a plurality of alignment features are included on the bottom member of each frame. Adjacent photovoltaic modules are interlocked by the alignment features on the top member of a lower module fitting together with the alignment features on the bottom member of an upper module. Other embodiments, features and aspects are also disclosed.

Wares, Brian S.

2012-09-04

160

Stable three-dimensional metallic carbon with interlocking hexagons  

PubMed Central

Design and synthesis of 3D metallic carbon that is stable under ambient conditions has been a long-standing dream. We predict the existence of such phases, T6- and T14-carbon, consisting of interlocking hexagons. Their dynamic, mechanical, and thermal stabilities are confirmed by carrying out a variety of state-of-the-art theoretical calculations. Unlike the previously studied K4 and the simple cubic high pressure metallic phases, the structures predicted in this work are stable under ambient conditions. Equally important, they may be synthesized chemically by using benzene or polyacenes molecules. PMID:24191020

Zhang, Shunhong; Wang, Qian; Chen, Xiaoshuang; Jena, Puru

2013-01-01

161

Group Distal Movement of Teeth using Micro-Screw–Implant Anchorage-A Case Report  

PubMed Central

This case report describes a case of orthodontic tooth movement of a 29-year-old female patient utilizing maxillary posterior edentulous area. Micro-implants were placed at buccal edentulous spaces and inter-radicular space for retraction of entire maxillary dentition. An overjet reduction of 8mm and good posterior occlusion were achieved. PMID:24995260

2014-01-01

162

Traumatic distal ulnar artery thrombosis.  

PubMed

This paper is about a posttraumatic distal ulnar artery thrombosis case that has occurred after a single blunt trauma. The ulnar artery thrombosis because of chronic trauma is a frequent condition (hypothenar hammer syndrome) but an ulnar artery thrombosis because of a single direct blunt trauma is rare. Our patient who has been affected by a single blunt trauma to his hand and developed ulnar artery thrombosis has been treated by resection of the thrombosed ulnar artery segment. This report shows that a single blunt trauma can cause distal ulnar artery thrombosis in the hand and it can be treated merely by thrombosed segment resection in suitable cases. PMID:25276455

Karaarslan, Ahmet A; Karaka?l?, Ahmet; Mayda, Aslan; Karc?, Tolga; Aycan, Hakan; Kobak, Senol

2014-01-01

163

Traumatic Distal Ulnar Artery Thrombosis  

PubMed Central

This paper is about a posttraumatic distal ulnar artery thrombosis case that has occurred after a single blunt trauma. The ulnar artery thrombosis because of chronic trauma is a frequent condition (hypothenar hammer syndrome) but an ulnar artery thrombosis because of a single direct blunt trauma is rare. Our patient who has been affected by a single blunt trauma to his hand and developed ulnar artery thrombosis has been treated by resection of the thrombosed ulnar artery segment. This report shows that a single blunt trauma can cause distal ulnar artery thrombosis in the hand and it can be treated merely by thrombosed segment resection in suitable cases. PMID:25276455

Karaarslan, Ahmet A.; Karaka?l?, Ahmet; Mayda, Aslan; Karc?, Tolga; Aycan, Hakan; Kobak, ?enol

2014-01-01

164

49 CFR 236.401 - Automatic block signal system and interlocking standards applicable to traffic control systems.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Automatic block signal system and interlocking...to traffic control systems...APPLIANCES Traffic Control Systems Standards § 236.401 Automatic block signal system and interlocking...to traffic control systems....

2012-10-01

165

49 CFR 236.401 - Automatic block signal system and interlocking standards applicable to traffic control systems.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Automatic block signal system and interlocking...to traffic control systems...APPLIANCES Traffic Control Systems Standards § 236.401 Automatic block signal system and interlocking...to traffic control systems....

2011-10-01

166

49 CFR 236.401 - Automatic block signal system and interlocking standards applicable to traffic control systems.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Automatic block signal system and interlocking...to traffic control systems...APPLIANCES Traffic Control Systems Standards § 236.401 Automatic block signal system and interlocking...to traffic control systems....

2013-10-01

167

Interlocking directorates and the knowledge transfer of supermarket retail techniques from North America to Britain  

Microsoft Academic Search

This paper considers the importance of interlocking directorates in knowledge transfer within the retail sector. In doing so it provides a discussion of the types of knowledge and more especially the importance of tacit knowledge. Such ideas are set against a more detailed review of the changing perspectives on the role of interlocking directorships. These discussions serve as a conceptual

Gareth Shaw; Andrew Alexander

2006-01-01

168

Design and testing of external fixator bone screws.  

PubMed

In external fixation, bone screw loosening still presents a major clinical problem. For this study, the design factors influencing the mechanics of the bone-screw interface were analysed and various experimental screws designed with the intention of maximizing the strength and stiffness of the inserted screw. Push-in, pull-out and bending tests were then carried out on the three experimental screws, and on two commercially available screws in both a synthetic material and in cadaveric bone; photoelastic tests on different screw threadforms were also performed. The results of the push-in and pull-out tests indicate that both the screw threadform and cutting head have a significant effect on the holding strength of the screw. The photoelastic tests show that most of the applied load is distributed over the first few threads closest to the load, and that the area between the thread crests is subjected to high shear stresses. PMID:2266740

Evans, M; Spencer, M; Wang, Q; White, S H; Cunningham, J L

1990-11-01

169

Robust microzip fastener: repeatable interlocking using polymeric rectangular parallelepiped arrays.  

PubMed

We report a highly repeatable and robust microzip fastener based on the van der Waals force-assisted interlocking between rectangular parallelepiped arrays. To investigate zipperlike interlocking behaviors, various line arrays were fabricated with three different spacing ratios (1, 3, and 5 of 800 nm in width) and width of parallelepipeds (400 nm, 800 nm, and 5 ?m with the spacing ratio of 1). In addition, the different rigidity of line arrays was inspected for a repeatable microzip fastener. The normal and shear locking forces were measured with variation of the material rigidity as well as geometry of the array, in good agreement with a proposed theory based on the contact area and force balance. The maximum adhesion forces as high as ?8.5 N cm(-2) in the normal direction and ?29.6 N cm(-2) in the shear direction were obtained with high stability up to 1000 cycles. High stability of our fastening system was confirmed for preventing critical failures such as buckling and fracture in practical applications. PMID:25615547

Lee, Chanseok; Kim, Sang Moon; Kim, Young Joo; Choi, Yong Whan; Suh, Kahp-Yang; Pang, Changhyun; Choi, Mansoo

2015-02-01

170

Effect of Screw Length on Bioabsorbable Interference Screw Fixation in a Tibial Bone Tunnel  

Microsoft Academic Search

Initial tibial fixation strength is the weak link after anterior cruciate ligament reconstruction with a quadrupled hamstring tendon graft fixed with bioabsorbable interference screws. The purpose of this study was to determine the biomechanical differences between 28-mm and tapered 35-mm interference screws for tibial fixation of a soft tissue graft in 16 young cadaveric tibias. Failure mode, displacement before failure,

Jeffrey B. Selby; Darren L. Johnson; Peter Hester; David N. M. Caborn

2001-01-01

171

The Turn of the Screw: Optimal Design of an Archimedes Screw  

Microsoft Academic Search

The geometry of an Archimedes screw is governed by certain external parameters (its outer radius, length, and slope) and certain internal parameters (its inner radius, number of blades, and the pitch of the blades). The external parameters are usually determined by the location of the screw and how much water is to be lifted. The internal parameters, however, are free

Chris Rorres

2000-01-01

172

Clinical application of combined fixation in the cervical spine using posterior transfacet screws and pedicle screws.  

PubMed

The aim of the present study was to describe the clinical application of combined fixation in the cervical spine using posterior transfacet and pedicle screws. Ten patients with cervical disorders requiring stabilization were treated from May 2006 to December 2008. The operative details varied depending on indication, the need for decompression, and the number of levels to be included in the spinal construct. Radiographic analysis of the fusion was performed after surgery. A total of 23 transfacet screws were inserted at or caudal to the C4/5 facet. A total of 21 pedicle screws were placed. All patients underwent operative treatment without neurovascular complications. Fusion was achieved in all patients. When performed appropriately, the method of using posterior transfacet screws in the caudal cervical joints combined with pedicle screw fixation in the cephalic cervical spine is reliable and deserves more widespread use. PMID:23232101

Liu, Guanyi; Ma, Weihu; Xu, Rongming; Godinsky, Ryan; Sun, Shaohua; Feng, Jianxiang; Zhao, Liujun; Hu, Yong; Zhou, Leijie; Liu, Jiayong

2013-04-01

173

Strut interlocking of Titanium Greenfield vena cava filters and its effect on clot capturing: An in vitro study  

Microsoft Academic Search

Purpose: To determine the influence of filter leg-interlocking on filtering efficiency of titanium Greenfield inferior vena cava filters in an in vitro model. Methods: Titanium Greenfield filters (TGF) were placed in an inferior vena cava (IVC) flow phantom with no interlocking legs, or with one or two pairs of legs interlocked. Clot emboli of varying sizes were introduced into the

Craig D. Korbin; Richard J. Van Allan; Robert T. Andrews; Michael D. Katz; George P. Teitelbaum

1994-01-01

174

THE JOURNAL OF CHEMICAL PHYSICS 135, 134705 (2011) Coalescence of 3-phenyl-propynenitrile on Cu(111) into interlocking  

E-print Network

) into interlocking pinwheel chains Miaomiao Luo,1 Wenhao Lu,1 Daeho Kim,1 Eric Chu,1 Jon Wyrick,1 Connor Holzke,1 molecule with the aromatic ring of its neighbor. Heptamers of trimers coalesce into interlocking pinwheel--tentatively attributed to sur- face stress--can generate arrays of interlocking pinwheels, each almost 5 nm across

Einstein, Theodore L.

175

THE INTERLOCK STRUCTURE OF THE POLICY-PLANNING NETWORK AND THE RIGHT TURN IN U.S. STATE POLICY  

Microsoft Academic Search

This paper examines interlocks among the governing boards of 12 leading policy- planning organizations and changes in the structure of this network between 1973 and 2000. Methods of multidimensional scaling and hierarchical clustering are used to construct topographical maps of the pattern of interlocks among policy-planning groups and their change over time. In contrast to the findings on corporate interlocking

Val Burris

176

Motivational Intervention Keyed to Interlock Use Reduces the Rate of Positive BAC Tests and Reduces Other Risk Indicators  

Microsoft Academic Search

This study examines the question of whether a structured 12 hour motivational support program known as SIP (Support for Interlock Planning), specifically keyed to the interlock, can improve the separation of drinking and driving initially, and later reduce the recidivism rate of offenders after the period of interlock controlled driving has ended. Approximately 10% of 320 first time offenders ordered

Paul Marques; Bob Voas; Scott Tippetts; Ken Blackman; Dave Timken; Craig Field

177

Outcome Assessment after Aptis Distal Radioulnar Joint (DRUJ) Implant Arthroplasty  

PubMed Central

Background: Conventional treatments after complicated injuries of the distal radioulnar joint (DRUJ) such as Darrach and Kapandji-Sauvé procedures have many drawbacks, which may eventually lead to a painful unstable distal ulna. The development of DRUJ prosthesis has significantly evolved over the past years. In this study, we assessed the outcome results of patients after DRUJ implant arthroplasty using the Aptis (Scheker) prosthesis. Methods: We identified 13 patients with 14 prosthesis during the past 10 years. Patients underwent DRUJ arthroplasty due to persistent symptoms of instability, chronic pain, and stiffness. Records and follow-up visits were reviewed to find the final post-operative symptoms, pain, range of motion, and grip strength with a mean follow-up of 12 months (range: 2-25 months). Also, patients were contacted prospectively by phone in order to administer the disabilities of the arm shoulder and hand (DASH), patient rated wrist evaluation (PRWE), and visual analogue scale (VAS), and to interview regarding satisfaction and progress in daily activities. Eleven patients out of 13 could be reached with a median follow-up time of 60 months (range: 2 to 102 months). Results: No patient required removal of the prosthesis. Only two patients underwent secondary surgeries in which both required debridement of the screw tip over the radius. The median DASH score, PRWE score, VAS, and satisfaction were 1.3, 2.5, 0, and 10, respectively. The mean range of flexion, extension, supination, and pronation was 62, 54, 51, and 64, respectively. Conclusions: Distal radioulnar joint injuries are disabling and patients usually undergo one or more salvage surgeries prior to receiving an arthroplasty. The Scheker prosthesis has shown satisfactory results with 100% survival rate in all reports. The constrained design of this prosthesis gives enough stability to prevent painful subluxation. PMID:25386579

Kachooei, Amir Reza; Chase, Samantha M; Jupiter, Jesse B

2014-01-01

178

Retrograde cartilage transplantation on the proximal and distal tibia.  

PubMed

The authors, with experience with more than 400 osteochondral autograft transplantation (OATS) cases since 1996, report a new technique of a retrograde osteochondral autograft transplantation for the treatment of isolated osteochondral lesions of the proximal and the distal tibia started in 1999. We treated 5 patients, 3 who presented with painful traumatic chondral defects in the central weight-bearing portion of the tibial plateau (1 in the medial and 2 in the lateral compartment), and 2 who presented with painful chondral lesions on the distal tibia. An anterior cruciate ligament (ACL) drill guide positioned in the center of the defect was used to accurately prepare the cartilage surface, in one case arthroscopically and in 4 cases through an open incision. A guide-wire was introduced and drilled through the tibia, and a cannulated reamer equal to the diameter of the defect was advanced. An osteochondral cylinder was harvested from the non-weight-bearing zone of the femoral trochlea at the angle that corresponded to the angle on the ACL drill guide. The autograft was inserted in a retrograde fashion from the cortical window into the tibial tunnel to be flush with the articular surface in press-fit technique. The remaining tunnel defect between the cortical window on the tibia and the distal aspect of the autograft was filled with a cancellous bony cylinder and secured with a diagonal bioabsorbable screw. A concomitant varus deformity with the lesion on the medial tibial plateau was corrected in the same surgery using a high tibial osteotomy to relieve stress on the graft. Patients were followed up for 6 to 35 months. A complete healing of the grafts was seen in control magnetic resonance images (MRIs). All patients were satisfied with the surgery. Control arthroscopies showed the osteochondral cylinders well integrated and flush with the articular surface. PMID:14716283

Ueblacker, Peter; Burkart, Andreas; Imhoff, Andreas Balthasar

2004-01-01

179

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

180

Impact of screw configuration on the particle size distribution of granules produced by twin screw granulation.  

PubMed

Twin screw granulation (TSG) has been reported by different research groups as an attractive technology for continuous wet granulation. However, in contrast to fluidized bed granulation, granules produced via this technique typically have a wide and multimodal particle size distribution (PSD), resulting in suboptimal flow properties. The aim of the current study was to evaluate the impact of granulator screw configuration on the PSD of granules produced by TSG. Experiments were performed using a 25mm co-rotating twin screw granulator, being part of the ConsiGma™-25 system (a fully continuous from-powder-to-tablet manufacturing line from GEA Pharma Systems). Besides the screw elements conventionally used for TSG (conveying and kneading elements), alternative designs of screw elements (tooth-mixing-elements (TME), screw mixing elements (SME) and cutters) were investigated using an ?-lactose monohydrate formulation granulated with distilled water. Granulation with only conveying elements resulted in wide and multimodal PSD. Using kneading elements, the width of the PSD could be partially narrowed and the liquid distribution was more homogeneous. However, still a significant fraction of oversized agglomerates was obtained. Implementing additional kneading elements or cutters in the final section of the screw configuration was not beneficial. Furthermore, granulation with only TME or SME had limited impact on the width of the PSD. Promising results were obtained by combining kneading elements with SME, as for these configurations the PSD was narrower and shifted to the size fractions suitable for tableting. PMID:25562758

Vercruysse, J; Burggraeve, A; Fonteyne, M; Cappuyns, P; Delaet, U; Van Assche, I; De Beer, T; Remon, J P; Vervaet, C

2015-02-01

181

Rotary screw compressors in the gas patch  

SciTech Connect

In 1959, Howden introduced the oil-injected rotary screw (OIS) compressor, which has, since then, methodically replaced the reciprocating (piston) compressor in applications such as air, refrigeration and fuel gas. Rotary screw compressors have been making inroads in gas recovery, a field once dominated by reciprocating compressors. Rotary screws do not require extensive maintenance, thus downtime is minimized throughout an operating year. Preventive maintenance is simple, since it consists of regular oil sample analysis which does not require system shut-down. As a result of the slide valve, OIS compressors can tune to field conditions with the greatest of ease, and without complicated process control. In addition, this method of capacity control is more efficient than unloading or use of a bypass-recirculation line. Both engineers and operators alike have found this flexibility to be a most redeeming feature. Finally, OIS compressors are capable of much larger flows then recips. 2 figs.

Jandjel, D.G.

1996-01-01

182

Screw expander for light duty diesel engines  

NASA Technical Reports Server (NTRS)

Preliminary selection and sizing of a positive displacement screw compressor-expander subsystem for a light-duty adiabatic diesel engine; development of a mathematical model to describe overall efficiencies for the screw compressor and expander; simulation of operation to establish overall efficiency for a range of design parameters and at given engine operating points; simulation to establish potential net power output at light-duty diesel operating points; analytical determination of mass moments of inertia for the rotors and inertia of the compressor-expander subsystem; and preparation of engineering layout drawings of the compressor and expander are discussed. As a result of this work, it was concluded that the screw compressor and expander designed for light-duty diesel engine applications are viable alternatives to turbo-compound systems, with acceptable efficiencies for both units, and only a moderate effect on the transient response.

1983-01-01

183

Role of Crystal Interlocking on the Strength of Brittle Rocks  

NASA Astrophysics Data System (ADS)

Results of an experimental programme on heterogeneous rock-like specimens of dental plaster confirm the pronounced role of tensile microcracks on brittle failure. Microbuckling of very small rock-columns formed amid closely located tensile cracks was observed as the key incident connecting stable phenomenon of tensile cracking to unstable phenomenon of shearing and subsequent macroscopic failure. Using the classical beam and buckling theories and considering geometry of the problem a new failure criterion is proposed. As a novel attempt, this new failure criterion relates the compressive strength of rock to three basic microstructural properties, i.e. degree of crystal interlocking, average Young modulus and average tensile strength of rock forming minerals.

Noferesti, Hossain; Rao, K. S.

2011-03-01

184

Biomechanical study of expandable pedicle screw fixation in severe osteoporotic bone comparing with conventional and cement-augmented pedicle screws.  

PubMed

Pedicle screws are widely utilized to treat the unstable thoracolumbar spine. The superior biomechanical strength of pedicle screws could increase fusion rates and provide accurate corrections of complex deformities. However, osteoporosis and revision cases of pedicle screw substantially reduce screw holding strength and cause loosening. Pedicle screw fixation becomes a challenge for spine surgeons in those scenarios. The purpose of this study was to determine if an expandable pedicle screw design could be used to improve biomechanical fixation in osteoporotic bone. Axial mechanical pull-out test was performed on the expandable, conventional and augmented pedicle screws placed in a commercial synthetic bone block which mimicked a human bone with severe osteoporosis. Results revealed that the pull-out strength and failure energy of expandable pedicle screws were similar with conventional pedicle screws augmented with bone cement by 2 ml. The pull-out strength was 5-fold greater than conventional pedicle screws and the failure energy was about 2-fold greater. Besides, the pull-out strength of expandable screw was reinforced by the expandable mechanism without cement augmentation, indicated that the risks of cement leakage from vertebral body would potentially be avoided. Comparing with the biomechanical performances of conventional screw with or without cement augmentation, the expandable screws are recommended to be applied for the osteoporotic vertebrae. PMID:24907127

Chen, Yi-Long; Chen, Wen-Chuan; Chou, Chi-Wei; Chen, Jou-Wen; Chang, Chia-Ming; Lai, Yu-Shu; Cheng, Cheng-Kung; Wang, Shih-Tien

2014-11-01

185

Distal esophageal spasm: an update.  

PubMed

Distal esophageal spasm (DES) is an esophageal motility disorder that presents clinically with chest pain and/or dysphagia and is defined manometrically as simultaneous contractions in the distal (smooth muscle) esophagus in ?20% of wet swallows (and amplitude contraction of ?30 mmHg) alternating with normal peristalsis. With the introduction of high resolution esophageal pressure topography (EPT) in 2000, the definition of DES was modified. The Chicago classification proposed that the defining criteria for DES using EPT should be the presence of at least two premature contractions (distal latency<4.5 s) in a context of normal EGJ relaxation. The etiology of DES remains insufficiently understood, but evidence links nitric oxide (NO) deficiency as a culprit resulting in a disordered neural inhibition. GERD frequently coexists in DES, and its role in the pathogenesis of symptoms needs further evaluation. There is some evidence from small series that DES can progress to achalasia. Treatment remains challenging due in part to lack of randomized placebo-controlled trials. Current treatment agents include nitrates (both short and long acting), calcium-channel blockers, anticholinergic agents, 5-phosphodiesterase inhibitors, visceral analgesics (tricyclic agents or SSRI), and esophageal dilation. Acid suppression therapy is frequently used, but clinical outcome trials to support this approach are not available. Injection of botulinum toxin in the distal esophagus may be effective, but further data regarding the development of post-injection gastroesophageal reflux need to be assessed. Heller myotomy combined with fundoplication remains an alternative for the rare refractory patient. Preliminary studies suggest that the newly developed endoscopic technique of per oral endoscopic myotomy (POEM) may also be an alternative treatment modality. PMID:23892829

Achem, Sami R; Gerson, Lauren B

2013-09-01

186

Mechanical behavior of screws in normal and osteoporotic bone  

Microsoft Academic Search

Fracture fixation in severe osteoporotic bone by means of implants that rely on screw anchorage is still a clinical problem. So far, a sufficiently accurate prediction of the holding capacity of screws as a function of local bone morphology has not been obtained. In this study the ultimate pullout loads of screws in the epi-, meta-, and diaphyseal regions of

J. Seebeck; J. Goldhahn; M. M. Morlock; E. Schneider

2005-01-01

187

Nylon screws make inexpensive coil forms  

NASA Technical Reports Server (NTRS)

Standard nylon screws act as coil form copper wire laid down in spiral thread. Completed coil may be bonded to printed-circuit board. However, it is impossible to tune coil by adjusting spacing between windings, technique sometimes used with air-core coils.

Aucoin, G.; Rosenthal, C.

1978-01-01

188

Analysis of Rotor Contact for Screw Compressor  

Microsoft Academic Search

A reliability evaluation of meshing rotor surfaces needs contact theory on a micro size area. We propose a method to evaluate whether a screw compressor rotor has enough contact fatigue strength. The method is based on analyses of three dimensional curvatures and the Hertz contact pressure. At a contact point one of the principal curvatures directs the rotor's sealing line

Hirotaka Kameya; Masakazu Aoki; Shigekazu Nozawa

2004-01-01

189

HERBERT SCREW FIXATION OF SCAPHOID FRACTURES  

Microsoft Academic Search

er eviewed the records of 431 patients who had open reduction and internal fixation of the scaphoid performed by one surgeon (TJH) over a 13-year period. The Herbert bone screw provided adequate internal fixation without the use of plaster immobilisation, promoting a rapid functional recovery. On average, patients returned to work 4.7 weeks after surgery and wrist function was significantly

S. L. FILAN; T. J. HERBERT

190

Pedicle screw placement with O-arm and stealth navigation.  

PubMed

Various navigation systems are available to aid pedicle screw placement. The O-arm replaces the need for fluoroscopy and generates a 3-dimensional volumetric dataset that can be viewed as transverse, coronal, and sagittal images of the spine, similar to computed tomography (CT) scanning. The dataset can be downloaded to the Stealth system (Medtronic Navigation, Louisville, Colorado) for real-time intraoperative navigation.The main objectives of the current study were to assess (1) accuracy of pedicle screw placement using the O-arm/Stealth system, and (2) time for draping, positioning of the O-arm, and screw placement. Of 188 screws (25 patients), 116 had adequate images for analysis. The average time for O-arm draping was 3.5 minutes. Initial O-arm positioning was 6.1 minutes, and final positioning was 4.9 minutes. Mean time for screw placement, including O-arm draping and positioning and array attachment, was 8.1 minutes per screw. Mean time for screw placement alone was 5.9 minutes per screw. Screw placements on final O-arm images were on average 3.14 mm deeper than on the snapshot navigation images. Three screws (2.6%) breached the medial cortex, and 3 screws (2.6%) were misaligned and did not follow the pilot hole trajectory.The use of the O-arm/Stealth system was associated with a low rate of pedicle screw misalignment. The time to place screws was less than previously reported with CT navigation, but longer than conventional techniques. It is important to be aware of the potential discrepancy between snapshot navigation images and actual screw placement on final O-arm images. Our findings suggest that final screw positions may be deeper than awl positions appear on navigation images. PMID:22229616

Patil, Suresh; Lindley, Emily M; Burger, Evalina L; Yoshihara, Hiroyuki; Patel, Vikas V

2012-01-01

191

30 CFR 75.819 - Motor-starter enclosures; barriers and interlocks.  

Code of Federal Regulations, 2010 CFR

...LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution High-Voltage Longwalls § 75.819 Motor-starter enclosures; barriers and interlocks. Compartment...

2010-07-01

192

18 CFR 131.31 - FERC Form No. 561, Annual report of interlocking positions.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false FERC Form No. 561, Annual report of interlocking...Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY APPROVED FORMS, FEDERAL POWER ACT AND PUBLIC UTILITY...

2013-04-01

193

18 CFR 131.31 - FERC Form No. 561, Annual report of interlocking positions.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false FERC Form No. 561, Annual report of interlocking...Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY APPROVED FORMS, FEDERAL POWER ACT AND PUBLIC UTILITY...

2014-04-01

194

18 CFR 131.31 - FERC Form No. 561, Annual report of interlocking positions.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false FERC Form No. 561, Annual report of interlocking...Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY APPROVED FORMS, FEDERAL POWER ACT AND PUBLIC UTILITY...

2012-04-01

195

18 CFR 131.31 - FERC Form No. 561, Annual report of interlocking positions.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false FERC Form No. 561, Annual report of interlocking...Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY APPROVED FORMS, FEDERAL POWER ACT AND PUBLIC UTILITY...

2011-04-01

196

Interlock recovery during the drying, calcination and vitrification phase of Am/Cm processing  

SciTech Connect

This document summarizes the results of five CIM5 [5-inch Cylindrical Induction Melter] runs designed to demonstrate power interlock recovery methods during the drying, calcination and vitrification phases of the Am/Cm melter cycle.

Snyder, T.K.

2000-01-20

197

75 FR 61820 - Model Specifications for Breath Alcohol Ignition Interlock Devices (BAIIDs)  

Federal Register 2010, 2011, 2012, 2013, 2014

...Administration [Docket No. NHTSA-2010-0033] Model Specifications for Breath Alcohol Ignition...This notice proposes revisions to the Model Specifications for Breath Alcohol Ignition Interlock Devices (BAIIDs). The Model Specifications are guidelines for the...

2010-10-06

198

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

199

Global ice-sheet system interlocked by sea level  

NASA Astrophysics Data System (ADS)

Denton and Hughes (1983, Quaternary Research20, 125-144) postulated that sea level linked a global ice-sheet system with both terrestrial and grounded marine components during late Quaternary ice ages. Summer temperature changes near Northern Hemisphere melting margins initiated sea-level fluctuations that controlled marine components in both polar hemispheres. It was further proposed that variations of this ice-sheet system amplified and transmitted Milankovitch summer half-year insolation changes between 45 and 75°N into global climatic changes. New tests of this hypothesis implicate sea level as a major control of the areal extent of grounded portions of the Antarctic Ice Sheet, thus fitting the concept of a globally interlocked ice-sheet system. But recent atmospheric modeling results ( Manabe and Broccoli, 1985, Journal of Geophysical Research90, 2167-2190) suggest that factors other than areal changes of the grounded Antarctic Ice Sheet strongly influenced Southern Hemisphere climate and terminated the last ice age simultaneously in both polar hemispheres. Atmospheric carbon dioxide linked to high-latitude oceans is the most likely candidate ( Shackleton and Pisias, 1985, Atmospheric carbon dioxide, orbital forcing, and climate. In "The Carbon Cycle and Atmospheric CO 2: Natural Variations Archean to Present" (E. T. Sundquest and W. S. Broecker, Eds.), pp. 303-318. Geophysical Monograph 32, American Geophysical Union, Washington, D.C.), but another potential influence was high-frequency climatic oscillations (2500 yr). It is postulated that variations in atmospheric carbon dioxide acted through an Antarctic ice shelf linked to the grounded ice sheet to produce and terminate Southern Hemisphere ice-age climate. It is further postulated that Milankovitch summer insolation combined with a warm high-frequency oscillation caused marked recession of Northern Hemisphere ice-sheet melting margins and the North Atlantic polar front about 14,000 14C yr B.P. This permitted renewed formation of North Atlantic Deep Water, which could well have controlled atmospheric carbon dioxide ( W. S. Broecker, D. M. Peteet, and D. Rind, 1985, Nature ( London) 315, 21-26). Combined melting and consequent sea-level rise from the three warming factors initiated irreversible collapse of the interlocked global ice-sheet system, which was at its largest but most vulnerable configuration.

Denton, George H.; Hughes, Terence J.; Karlén, Wibjörn

1986-07-01

200

Treatment of idiopathic scoliosis with CD-instrumentation: lumbar pedicle screws versus laminar hooks in 66 patients.  

PubMed

We studied whether the pedicle screw is better than laminar hooks for fixation of the lumbar spine in the treatment of idiopathic scoliosis. 66 consecutive patients with idiopathic scoliosis (King I and II) were studied retrospectively. Group S included 33 patients (25 females) treated with pedicle screws. Their mean age at operation was 17 (13-54) years. Group H included 33 patients (30 females) treated exclusively with hooks. Their mean age at operation was 16 (1140) years. The preoperative mean angles of the thoracic curve in group S was 66 (42.115) degrees, and in group H 65 (42-121) degrees. The lumbar curve averaged 46 (20-85) degrees in group H and 53 (33-86) degrees in group S. All patients were fused only posteriorly with Cotrel-Dubousset instrumentation and an autogenic bone graft. The mean follow-up time was 4 (2-7) years. Mean correction of the thoracic curve was 45% in group S and 50% in group H. The lumbar curve was corrected by 50% in group S and 51% in group H. Loss of correction of the thoracic curve occurred in 5% in group S and 6% in group H and of the lumbar curve in 3% in group S and 10% in group H (p = 0.04). Group S better maintained the correction of the lateral tilt of the uninstrumented segment adjacent to the fusion (p = 0.04). Derotation, according to Perdriolle, in the distal segment adjacent to the fusion was 6% in group S and 2% in group H. We found no difference between correction of the thoracic and lumbar curves using pedicle screws and laminar hooks in the lumbar spine. Pedicle screws better maintained the correction of the lumbar curve and the lateral tilt in the distal segment adjacent to fusion. PMID:11817877

Wimmer, C; Gluch, H; Nogler, M; Walochnik, N

2001-12-01

201

Periprosthetic bone remodelling around a prosthesis for distal femoral tumours. Measurement by dual-energy X-ray absorptiometry (DEXA).  

PubMed

We used dual-energy x-ray absorptiometry (DEXA) to evaluate the extent of periprosthetic bone remodelling around a prosthesis for distal femoral reconstruction, the Kotz modular femoral tibial replacement (KMFTR; Howmedica, Rutherford, New Jersey). A total of 23 patients was entered into the study which had four parts: 1) 17 patients were scanned three times on both the implant and contralateral legs to determine whether the precision of DEXA measurements was adequate to estimate bone loss surrounding the anchorage piece of the KMFTR; 2) in 23 patients the bone mineral density (BMD) in different regions of interest surrounding the diaphyseal anchorage was compared with that of the contralateral femur at the same location to test whether there was consistent evidence of loss of BMD adjacent to the prosthetic stem; 3) in 12 patients sequential studies were performed about one year apart to compare bone loss; and 4) bone loss was compared in ten patients with implants fixed by three screws and in 13 without screws. The mean coefficients of variation (SD/mean) for the 17 sets of repeated scans ranged from 2.9% to 7.8% at different regions of interest in the KMFTR leg and from 1.4% to 2.5% in the contralateral leg. BMD was decreased in the KMFTR leg relative to the contralateral limb and the percentage of BMD loss in general increased as the region of interest moved distally in the femur. Studies done after one year showed no consistent pattern of progressive bone loss between the two measurements. The ten patients with implants fixed by screws were found to have a mean loss of BMD of 42% in the most distal part of the femur, while the 13 without screw fixation had a mean loss of 11%. DEXA was shown to have adequate precision to evaluate loss of BMD around the KMFTR. This was evident relative to the contralateral leg in all patients and generally increased in the most distal part of the femur. In general, it stabilised between two measurements taken one year apart and was greater surrounding implants fixed by cross-locking screws. PMID:10697327

Lan, F; Wunder, J S; Griffin, A M; Davis, A M; Bell, R S; White, L M; Ichise, M; Cole, W

2000-01-01

202

An analysis of tendon injuries accompanying distal radius fractures using volar locking plates.  

PubMed

We examined 6 cases of tendon injuries that accompanied distal radius fractures using volar locking plate between April 2006 and March 2012. Male: one case, female: five cases, average age 57.0 (33~70) years old. The fracture type was A2 in one case, A3 in four cases, and C2 in one case by AO classification. The average period for operation waiting was 2.7 days. We analyzed the time of occurrence of tendon rupture (extensor pollicis longus (EPL)?flexor pollicis longus (FPL)), the existence or not of screw prominence and dorsal roof fragment, and the positioning of the plate setting. The tendon ruptures were EPL in four cases, and FPL in two cases. The average period of rupture occurrence was 86.8 (1~182) days. In four EPL tendon ruptures we recognized one marked screw prominence (16.7%), and two dorsal roof fragments (50%), both showing widespread displacement. Moreover, we recognized the malposition of the plate setting in the two cases of FPL tendon rupture (100%). The incidence of tendon ruptures accompanying distal radius fractures using volar locking plates was not low at all, therefore we should more pay attention to the prevention of this occurrence. PMID:25501757

Zenke, Yukichi; Oshige, Toshihisa; Menuki, Kunitaka; Yamanaka, Yoshiaki; Murai, Teppei; Furukawa, Kayoko; Sakai, Akinori

2014-12-01

203

Polymer mechanically interlocking structures as interconnects for microfluidic systems  

NASA Astrophysics Data System (ADS)

This paper describes peg-in-hole type mechanical interconnects made of SU-8 photopolymer, polydimethylsiloxane (PDMS) and silicon for joining microfluidic components of disparate materials to create complex microinstruments. Interconnects assemble as compliant interlocking cylinders that deform when assembled with holes that are smaller by several to several tens of microns, thus providing mechanical attachment as well as fluid interconnects between substrates. Example structures have nominal outer radii of 100-200 µm, inner radii of 50-100 µm and lengths of 200-400 µm. ANSYS mechanical simulations are employed to analyze the optimal interconnect sizing for a mechanical attachment, as well as predict disassembly forces ranging from zero to 232 mN. The interconnects are fabricated and experimentally tested with a controlled-force linear actuator to yield disassembly forces ranging from 20 to 130 mN. Pressurization tests demonstrate that SU-8 interconnects hold water pressure to 200 kPa without leaking and PDMS interconnects hold air pressure to 21 kPa and water pressure to roughly 6.9 kPa.

Jaffer, S.; Gray, B. L.

2008-03-01

204

Interlocked DNA nanostructures controlled by a reversible logic circuit  

PubMed Central

DNA nanostructures constitute attractive devices for logic computing and nanomechanics. An emerging interest is to integrate these two fields and devise intelligent DNA nanorobots. Here we report a reversible logic circuit built on the programmable assembly of a double-stranded (ds) DNA [3]pseudocatenane that serves as a rigid scaffold to position two separate branched-out head-motifs, a bimolecular i-motif and a G-quadruplex. The G-quadruplex only forms when preceded by the assembly of the i-motif. The formation of the latter, in turn, requires acidic pH and unhindered mobility of the head-motif containing dsDNA nanorings with respect to the central ring to which they are interlocked, triggered by release oligodeoxynucleotides. We employ these features to convert the structural changes into Boolean operations with fluorescence labelling. The nanostructure behaves as a reversible logic circuit consisting of tandem YES and AND gates. Such reversible logic circuits integrated into functional nanodevices may guide future intelligent DNA nanorobots to manipulate cascade reactions in biological systems. PMID:25229207

Li, Tao; Lohmann, Finn; Famulok, Michael

2014-01-01

205

Inertial interlock bonding: A new approach to sputtering target construction  

SciTech Connect

Inertial interlock bonding (IIB) was developed to provide a reliable low cost automated method for joining dissimilar metal plates at low bulk bonding temperatures for the production of sputtering targets. Joining dissimilar metals at elevated temperatures creates residual stress from the differential thermal expansion of the bimetallic plates. The IIB method of joining dissimilar metal plates alleviates the need to increase the bulk temperature of the metal plates during bonding and thereby significantly reduces the residual stress. In IIB, the heat generated by inertial friction between two dissimilar metal plates is used to simultaneously (1) soften an intercalated ring that is forged into a matching T groove and (2) melt a thin solder layer that wets the other plate creating a reliable solder bond. While finite element modeling of the process indicates that the surface temperatures during bonding approach 1000 deg. C, the bulk temperature for the assembly remains below 70 deg. C. In this way, the differential thermal residual stress remains low, while a reliable bimetallic joint is formed. Results for joining tantalum to copper alloy plates for sputtering target applications are provided.

Wickersham, C. E. Jr.; Workman, David [Cabot Corporation, 157 Concord Road, Billerica, Massachusetts 01821 (United States); Edision Welding Institute, 1250 Arthur E Adams Drive, Columbus, Ohio 43221 (United States)

2007-01-15

206

Finite element analysis of Stryker Xia pedicle screw in artificial bone samples with and without supplemental cement augmentation.  

PubMed

A validated, using in vitro biomechanical testing, finite element model was used to evaluate the affects of (1) cement augmentation and (2) an intact posterior cortex in osteoporotic bone. The presence of augmentation and/or a posterior cortical cortex increased the stabilization of the pedicle screw 2-5 fold. Placement of cement influenced failure load and toggle; with distal placement having the largest increase in failure load and decrease in cephalad-caudad toggle. The presence of posterior cortex caused a decrease in the amount of toggle, a proximal shift of the center of rotation and an increase in the maximum failure force. PMID:24980259

Pfeiffer, Ferris M; Choma, Theodore J; Kueny, Rebecca

2015-10-01

207

Strategy for salvage pedicle screw placement: A technical note  

PubMed Central

Background Salvage surgery for failed lumbar spine fusion with a loosened pedicle screw is challenging. In general, the strategy includes replacement with larger and longer pedicle screws, augmentation with polymethylmethacrylate cement or hydroxyapatite granules, and extension of fused segments. The purpose of this study is to introduce a new technique for pedicle screw replacement after failed lumbar spine fusion. Methods Five salvage operations were performed using a different trajectory (DT) pedicle screw replacement technique based on 3-dimensional radiological information. Position of the alternative pedicle screws was planned carefully on the computer screen of a computed tomography-based navigation system before the operation. To obtain sufficient initial stability, 1 of 2 techniques was chosen, depending on the patient. One technique created a completely new route, which did not interfere with the existing screw hole, and the other involved penetration of the existing screw hole. Results DT pedicle screws were replaced successfully according to the preoperative plan. In all patients, bony union were achieved at the final follow-up period without any instrument failure. Extension of the fused segments could be avoided by using the DT pedicle screw replacement technique combined with transforaminal lumbar interbody fusion. Conclusions The DT pedicle screw replacement technique is a treatment option for salvage lumbar spine surgery. Clinical relevance The current technique is a treatment option for salvage operations that can both avoid extension of a fused segment and achieve successful bony union.

Fujibayashi, Shunsuke; Takemoto, Mitsuru; Neo, Masashi; Matsuda, Shuichi

2013-01-01

208

Distal biceps and triceps ruptures.  

PubMed

Biceps and triceps tendon ruptures are rather uncommon injuries and are most commonly diagnosed clinically. Magnetic resonance imaging can help the clinician to differentiate an incomplete tear and define any degeneration of the tendon. Surgical anatomical repair is typically performed in acute complete ruptures whereas nonoperative treatment can be used for partial ruptures, as well as for patients unfit for surgery. Single incision techniques are associated with a higher rate of nerve injuries, while double incision repairs have a higher prevalence of heterotopic ossification. Although various fixation methods have been applied including bone tunnels, interference screws, suture anchors, cortical button fixation, the current evidence does not support the superiority of one method over the other. A well-planned postoperative rehabilitation programme is essential for a good final outcome. As better fixation devices are being used, more aggressive rehabilitation programmes have been applied. Epidemiology, clinical evaluation, diagnosis, surgical and conservative management of these injuries are presented in this review along with the authors' preferred technique for the anatomical repair of acute complete ruptures. PMID:23352149

Kokkalis, Zinon T; Ballas, Efstathios G; Mavrogenis, Andreas F; Soucacos, Panayotis N

2013-03-01

209

CFD ANALYSIS OF SCREW COMPRESSOR PERFORMANCE  

Microsoft Academic Search

Modern manufacturing methods enable screw compressors to be constructed to such close tolerances that full 3-D numerical calculation of the heat and fluid flow through them is required to obtain the maximum possible improvements in their design. An independent stand-alone CAD-CFD interface program has therefore been developed by the authors in order to generate a numerical grid for this purpose.

Ahmed Kovacevic; Nikola Stosic; Ian K. Smith

210

Intraoperative 3-dimensional imaging (O-arm) for assessment of pedicle screw position: Does it prevent unacceptable screw placement?  

PubMed Central

Background Pedicle screws are biomechanically superior over other spinal fixation devices. When improperly positioned, they lose this advantage and put adjacent structures at risk. Accurate placement is therefore critical. Postoperative computed tomography (CT) scans are the imaging gold standard and have shown malposition rates ranging from 2% to 41%. The O-arm (Medtronic Navigation, Louisville, Colorado) is an intraoperative CT scanner that may allow intervention for malpositioned screws while patients are still in the operating room. However, this has not yet been shown in clinical studies. The primary objective of this study was to assess the usefulness of the O-arm for evaluating pedicle screw position by answering the following question: What is the rate of intraoperative pedicle screw revision brought about by O-arm imaging information? A secondary question was also addressed: What is the rate of unacceptable thoracic and lumbar pedicle screw placement as assessed by intraoperative O-arm imaging? Methods This is a case series of consecutive patients who have undergone spine surgery for which an intraoperative 3-dimensional (3D) CT scan was used to assess pedicle screw position. The study comprised 602 pedicle screws (235 thoracic and 367 lumbar/sacral) placed in 76 patients, and intraoperative 3D (O-arm) imaging was obtained to assess screw position. Action taken at the time of surgery based on imaging information was noted. An independent review of all scans was also conducted, and all screws were graded as either optimal (no breach), acceptable (breach ?2 mm), or unacceptable (breach >2 mm). The rate of pedicle screw revision, as detected by intraoperative 3D CT scan, was determined. Results On the basis of 3D imaging information, 17 of 602 screws (2.8%) in 14 of 76 cases (18.4%) were revised at the time of surgery. On independent review of multiplanar images, 11 screws (1.8%) were found to be unacceptable, 32 (5.3%) were acceptable, and 559 (92.9%) were optimal. All unacceptable screws were revised to an optimal or acceptable position, and an additional 6 acceptable screws were revised to an optimal position. Thus, by the end of the cases, none of the 602 pedicle screws in the 76 surgical procedures was in an unacceptable position. Conclusion The new-generation intraoperative 3D imaging system (O-arm) is a useful tool that allows more accurate assessment of pedicle screw position than plain radiographs or fluoroscopy alone. It prompted intraoperative repositioning of 2.8% of pedicle screws in our series. Most importantly, it allowed identification and revision of all unacceptably placed pedicle screws without the need for reoperation.

Sembrano, Jonathan N.; Polly, David W.; Ledonio, Charles Gerald T.; Santos, Edward Rainier G.

2012-01-01

211

Comparison of Torsional Strengths of Bioabsorbable Screws for Anterior Cruciate Ligament Reconstruction  

Microsoft Academic Search

The goals of this study were to evaluate torsional strength and modes of failure in commercially available bioabsorbable interference screws and to test the effect of screw diameter on torsional strength when screws become jammed during insertion. We tested the Arthrex, BioScrew, Endo-Fix, Phantom, and Sysorb screws, all 20 mm in length. Four major modes of failure were encountered. Analysis

John J. Costi; Andrew J. Kelly; Trevor C. Hearn; David K. Martin

2001-01-01

212

Using resorbable screws for fixation of cortical onlay bone grafts: An in vivo study in rabbits  

Microsoft Academic Search

Purpose: The purpose of this study is to test bioresorbable screws as an alternative to titanium screw graft fixation. When cortical onlay grafts are used, it is necessary to rigidly immobilize them with titanium screws into the recipient site. The screws must be removed before placing implants into this site. Bioresorbable screws may be an alternative to titanium fixation, eliminating

Guillermo E. Chacon; James P. Ellis; John R. Kalmar; Edwin A. McGlumphy

2004-01-01

213

Global ice-sheet system interlocked by sea level  

SciTech Connect

Denton and Hughes postulated that sea level linked a global ice-sheet system with both terrestrial and grounded marine components during later Quaternary ice ages. Summer temperature changes near Northern Hemisphere melting margins initiated sea-level fluctuations that controlled marine components in both polar hemispheres. It was further proposed that variations of this ice-sheet system amplified and transmitted Milankovitch summer half-year insolation changes between 45 and 75/sup 0/N into global climatic changes. New tests of this hypothesis implicate sea level as a major control of the areal extent of grounded portions of the Antarctic Ice Sheet. But factors other than areal changes of the grounded Antarctic Ice Sheet may have strongly influenced Southern Hemisphere climate and terminated the last ice age simultaneously in both polar hemispheres. Atmospheric carbon dioxide linked to high-latitude oceans is the most likely candidate, but another potential influence was high-frequency climatic oscillations. It is postulated that variations in atmospheric carbon dioxide acted through an Antarctic ice shelf linked to the grounded ice sheet to produce and terminate Southern Hemisphere ice-age climate. It is further postulated that Milankovitch summer insolation combined with a warm-high frequency oscillation caused marked recession of Northern Hemisphere ice-sheet melting margins and the North Atlantic polar front about 14,000 /sup 14/C yr B.P. This permitted renewed formation of North Atlantic Deep Water, which could well have controlled atmospheric carbon dioxide. Combined melting and consequent sea-level rise from the three warming factors initiated irreversible collapse of the interlocked global ice-sheet system, which was at its largest but most vulnerable configuration.

Denton, G.H.; Hughes, T.J.; Karlen, W.

1986-01-01

214

Fracture fixation with two locking screws versus three non-locking screws  

PubMed Central

Objectives We aimed to further evaluate the biomechanical characteristics of two locking screws versus three standard bicortical screws in synthetic models of normal and osteoporotic bone. Methods Synthetic tubular bone models representing normal bone density and osteoporotic bone density were used. Artificial fracture gaps of 1 cm were created in each specimen before fixation with one of two constructs: 1) two locking screws using a five-hole locking compression plate (LCP) plate; or 2) three non-locking screws with a seven-hole LCP plate across each side of the fracture gap. The stiffness, maximum displacement, mode of failure and number of cycles to failure were recorded under progressive cyclic torsional and eccentric axial loading. Results Locking plates in normal bone survived 10% fewer cycles to failure during cyclic axial loading, but there was no significant difference in maximum displacement or failure load. Locking plates in osteoporotic bone showed less displacement (p = 0.02), but no significant difference in number of cycles to failure or failure load during cyclic axial loading (p = 0.46 and p = 0.25, respectively). Locking plates in normal bone had lower stiffness and torque during torsion testing (both p = 0.03), but there was no significant difference in rotation (angular displacement) (p = 0.84). Locking plates in osteoporotic bone showed lower torque and rotation (p = 0.008), but there was no significant difference in stiffness during torsion testing (p = 0.69). Conclusions The mechanical performance of locking plate constructs, using only two screws, is comparable to three non-locking screw constructs in osteoporotic bone. Normal bone loaded with either an axial or torsional moment showed slightly better performance with the non-locking construct. PMID:23610681

Grawe, B.; Le, T.; Williamson, S.; Archdeacon, A.; Zardiackas, L.

2012-01-01

215

Internal fixation of a capitate fracture with Herbert screws.  

PubMed

A case of an isolated, displaced fracture of the capitate is described. This rare carpal injury was treated by internal fixation with two Herbert screws. The fracture united and the patient achieved an excellent range of wrist motion. The Herbert screw is useful in the treatment of displaced fractures of the capitate since the screw maintains reduction, compresses the fracture site, and allows early wrist motion. PMID:2269778

Richards, R R; Paitich, C B; Bell, R S

1990-11-01

216

Treatment of Pelvic Ring Fractures: Percutaneous Computer Assisted Iliosacral Screwing  

Microsoft Academic Search

This paper describes the development and preliminary testing of an image-guided system for the placement of iliosacral screws\\u000a to stabilize pelvic ring fractures percutaneously, with the aim of decreasing the incidence of surgical complications and\\u000a increasing the accuracy of screw placement. Pre-operative planning of screw trajectories is performed on a 3D model of the\\u000a pelvis constructed from CT scans. During

Lionel Carrat; Jerome Tonetti; Stéphane Lavallée; Philippe Merloz; Laurence Pittet; Jean-paul Chirossel

1998-01-01

217

Abrasion of abutment screw coated with TiN  

PubMed Central

STATEMENT OF PROBLEM Screw loosening has been a common complication and still reported frequently. PURPOSE The purpose of this study was to evaluate abrasion of the implant fixture and TiN coated abutment screw after repeated delivery and removal with universal measuring microscope. MATERIAL AND METHODS Implant systems used for this study were Osstem and 3i. Seven pairs of implant fixtures, abutments and abutment screws for each system were selected and all the fixtures were perpendicularly mounted in liquid unsaturated polyesther with dental surveyor. After 20 times of repeated closing and opening test, the evaluation for the change of inner surface of implant and TiN-coated abutment screw, and weight loss were measured. Mann-Whitney test with SPSS statistical software for Window was applied to analyze the measurement of weight loss. RESULTS TiN-coated abutment screws of Osstem and 3i showed lesser loss of weight than non-coated those of Osstem and 3i (P < .05, Mann-Whitney test). CONCLUSION Conclusively, TiN coating of abutment screw showed better resistance to abrasion than titanium abutment screw. It was concluded that TiN coating of abutment screw would reduce the loss of preload with good abrasion resistance and low coefficient of friction, and help to maintain screw joint stability. PMID:21165263

Jung, Seok-Won; Son, Mee-Kyoung; Chung, Chae-Heon

2009-01-01

218

Totally Laparoscopic Distal Gastrectomy after Learning Curve Completion: Comparison with Laparoscopy-Assisted Distal Gastrectomy  

PubMed Central

Purpose The aims are to: (i) display the multidimensional learning curve of totally laparoscopic distal gastrectomy, and (ii) verify the feasibility of totally laparoscopic distal gastrectomy after learning curve completion by comparing it with laparoscopy-assisted distal gastrectomy. Materials and Methods From January 2005 to June 2012, 247 patients who underwent laparoscopy-assisted distal gastrectomy (n=136) and totally laparoscopic distal gastrectomy (n=111) for early gastric cancer were enrolled. Their clinicopathological characteristics and early surgical outcomes were analyzed. Analysis of the totally laparoscopic distal gastrectomy learning curve was conducted using the moving average method and the cumulative sum method on 180 patients who underwent totally laparoscopic distal gastrectomy. Results Our study indicated that experience with 40 and 20 totally laparoscopic distal gastrectomy cases, is required in order to achieve optimum proficiency by two surgeons. There were no remarkable differences in the clinicopathological characteristics between laparoscopy-assisted distal gastrectomy and totally laparoscopic distal gastrectomy groups. The two groups were comparable in terms of open conversion, combined resection, morbidities, reoperation rate, hospital stay and time to first flatus (P>0.05). However, totally laparoscopic distal gastrectomy had a significantly shorter mean operation time than laparoscopy-assisted distal gastrectomy (P<0.01). We also found that intra-abdominal abscess and overall complication rates were significantly higher before the learning curve than after the learning curve (P<0.05). Conclusions Experience with 20~40 cases of totally laparoscopic distal gastrectomy is required to complete the learning curve. The use of totally laparoscopic distal gastrectomy after learning curve completion is a feasible and timesaving method compared to laparoscopy-assisted distal gastrectomy. PMID:23610716

Kim, Han-Gil; Jeong, Sang-Ho; Lee, Young-Joon; Ha, Woo-Song; Choi, Sang-Kyung; Hong, Soon-Chan; Jung, Eun-Jung; Ju, Young-Tae; Jeong, Chi-Young; Park, Taejin

2013-01-01

219

Biomechanical and histomorphometric study on the bone–screw interface of bioactive ceramic-coated titanium screws  

Microsoft Academic Search

The purpose of this study was to compare the osseointegration of 4 different kinds of bioactive ceramic-coated screws with uncoated screws by biomechanical and histomorphometric analysis.Calcium pyrophosphate (CPP), apatite-wollastonite 1:3 glass ceramic (W3G), apatite-wollastonite 1:1 glass ceramic (WAG) and bioactive CaO–SiO2–B2O3 glass ceramic (CSG) coatings were prepared and coated by the dipping method. Coated and uncoated titanium screws were inserted

Jae Hyup Lee; Hyun-Seung Ryu; Dong-Soo Lee; Kug Sun Hong; Bong-Soon Chang; Choon-Ki Lee

2005-01-01

220

Pedicle screw instrumentation of thoracolumbar burst fractures: Biomechanical evaluation of screw configuration with pedicle screws at the level of the fracture  

PubMed Central

Background Posterior fixation alone may not be adequate to achieve and maintain burst fracture reduction. Adding screws in the fractured body may improve construct stiffness. This in vitro study evaluates the biomechanical effect of inserting pedicle screws in the fractured body compared with conventional short- and long-segment posterior fixation. Methods Stable and unstable L2 burst fractures were created in 8 calf spines (aged 18 weeks). Constructs were tested at 8 Nm in the intact state and then with instrumentation consisting of long- and short-segment posterior fixation with and without screws in the fractured L2 vertebral body after (1) stable burst fracture and (2) unstable burst fracture. Range of motion was recorded at L1-3 for flexion-extension, lateral bending, and axial rotation. Statistical analysis was performed with repeated-measures analysis of variance, with significance set at P < .05. The data were normalized to the intact state (100%). Results Both long- and short-segment constructs with screws in the fractured body significantly reduced motion compared with the stable and unstable burst fracture in flexion-extension and lateral bending. Fracture screws enhanced construct stability by 68% (on average) relative to conventional short-segment posterior fixation and were comparable to long-segment posterior fixation. Conclusions Screws at the fracture level improve construct stiffness. Short-segment constructs may suffice for stable burst fractures. More severe injuries may benefit from fracture screws and can be considered as an alternative treatment to long-segment constructs.

Bolesta, Michael J.; Caron, Troy; Chinthakunta, Suresh R.; Vazifeh, Pedram Niknam; Khalil, Saif

2012-01-01

221

Tactile-direction-sensitive and stretchable electronic skins based on human-skin-inspired interlocked microstructures.  

PubMed

Stretchable electronic skins with multidirectional force-sensing capabilities are of great importance in robotics, prosthetics, and rehabilitation devices. Inspired by the interlocked microstructures found in epidermal-dermal ridges in human skin, piezoresistive interlocked microdome arrays are employed for stress-direction-sensitive, stretchable electronic skins. Here we show that these arrays possess highly sensitive detection capability of various mechanical stimuli including normal, shear, stretching, bending, and twisting forces. Furthermore, the unique geometry of interlocked microdome arrays enables the differentiation of various mechanical stimuli because the arrays exhibit different levels of deformation depending on the direction of applied forces, thus providing different sensory output patterns. In addition, we show that the electronic skins attached on human skin in the arm and wrist areas are able to distinguish various mechanical stimuli applied in different directions and can selectively monitor different intensities and directions of air flows and vibrations. PMID:25389631

Park, Jonghwa; Lee, Youngoh; Hong, Jaehyung; Lee, Youngsu; Ha, Minjeong; Jung, Youngdo; Lim, Hyuneui; Kim, Sung Youb; Ko, Hyunhyub

2014-12-23

222

Arthroscopic meniscal repair with an absorbable screw: results and surgical technique  

Microsoft Academic Search

The results of a new method for arthroscopic all-inside meniscus repair using a biodegradable cannulated screw (Clearfix meniscal screw) were assessed in a medium-term follow-up prospective study. The Clearfix meniscal screw system consists of delivery cannulae, screw driver, and screw implants. After tear debridement, a screw is located on the driver and passed through the cannula to the insertion site,

Michael E. Hantes; Elias S. Kotsovolos; Dimitrios S. Mastrokalos; Joerg Ammenwerth; Hans H. Paessler

2005-01-01

223

Rotary screw compressor lubricants. [synthetic lubricant  

SciTech Connect

A method is claimed for synthetic lubricants comprising 15 to 45 weight percent of an ester of a hindered polyhydric alcohol having 3 to 8 hydroxy groups and 5 to 10 carbon atoms with one or more alkanoic acids having 4 to 18 carbon atoms blended with 85 to 55 weight percent of one or more polyether polyol having an number average molecular weight from about 400 to 5000. The blends are compounded with antioxidants, corrosion inhibitors, and metal deactivators to produce a superior lubricant for rotary screw compressors that has a long life.

Carswell, R.; Mcgraw, P.W.

1981-11-24

224

Biomechanical Performance of Variable and Fixed Angle Locked Volar Plates for the Dorsally Comminuted Distal Radius  

PubMed Central

Background The ideal treatment strategy for the dorsally comminuted distal radius fracture continues to evolve. Newer plate designs allow for variable axis screw placement while maintaining the advantages of locked technology. The purpose of this study is to compare the biomechanical properties of one variable axis plate with two traditional locked constructs. Methods Simulated fractures were created via a distal 1 cm dorsal wedge osteotomy in radius bone analogs. The analogs were of low stiffness and rigidity to create a worst-case strength condition for the subject radius plates. This fracture-gap model was fixated using one of three different locked volar distal radius plates: a variable axis plate (Stryker VariAx) or fixed axis (DePuy DVR, Smith & Nephew Peri-Loc) designs. The constructs were then tested at physiologic loading levels in axial compression and bending (dorsal and volar) modes. Construct stiffness was assessed by fracture gap motion during the different loading conditions. As a within-study control, intact bone analogs were similarly tested. Results All plated constructs were significantly less stiff than the intact control bone models in all loading modes (p<0.040). Amongst the plated constructs, the VariAx was stiffest axially (p=0.032) and the Peri-Loc was stiffest in bending (p<0.024). Conclusion In this analog bone fracture gap model, the variable axis locking technology was stiffer in axial compression than other plates, though less stiff in bending. PMID:25328471

Martineau, D; Shorez, J; Beran, C; Dass, A G; Atkinson, P

2014-01-01

225

Fatigue behavior of Ilizarov frame versus tibial interlocking nail in a comminuted tibial fracture model: a biomechanical study  

Microsoft Academic Search

BACKGROUND: Treatment options for comminuted tibial shaft fractures include plating, intramedullary nailing, and external fixation. No biomechanical comparison between an interlocking tibia nail with external fixation by an Ilizarov frame has been reported to date. In the present study, we compared the fatigue behaviour of Ilizarov frames to interlocking intramedullary nails in a comminuted tibial fracture model under a combined

Erik Hasenboehler; Wade R Smith; Laurence Laudicina; Giby C Philips; Philip F Stahel; Steven J Morgan

2006-01-01

226

Accounting Choices and Director Interlocks: A Social Network Approach to the Voluntary Expensing of Stock Option Grants  

Microsoft Academic Search

Abstract:?We adopt a social network perspective of accounting choices and argue that voluntary expensing of stock option grants by firms may be driven by social influence and learning within a network of director interlocks. We find that firms are more likely to expense stock option grants voluntarily when they have inside director interlocks with (1) other firms that do likewise,

Eugene Kang; Brian R. Tan

2008-01-01

227

Effects of Ignition Interlock Devices on DUI Recidivism: Findings from a Longitudinal Study in Hamilton County, Ohio  

Microsoft Academic Search

As demands for more effective legal remedies for drunk driving escalate, a number of states have authorized judges to use breath analyzer ignition interlock devices as an optional sanction in drunk driving cases. This research presents initial findings from a quasi-experimental study designed to evaluate the effectiveness of interlock devices as a deterrent to a repeated drunk driving arrest in

Barbara J. Morse; Delbert S. Elliott

1992-01-01

228

Tibial Fixation of Bone-Patellar Tendon-Bone Grafts in Anterior Cruciate Ligament ReconstructionA Cadaveric Study of Bovine Bone Screw and Biodegradable Interference Screw  

Microsoft Academic Search

Background: The use of interference screw fixation for bone-patellar tendon-bone grafts in anterior cruciate ligament fixation is well established. No previous study has compared bovine bone screws and biodegradable interference screws or demonstrated their efficacy for requirements associated with early rehabilitation.Hypothesis: There is no difference in tension loss and pull-out strength between bovine bone screws and biodegradable interference screws.Study Design:

Naiquan Zheng; Chad T. Price; Peter A. Indelicato; Bo Gao

2008-01-01

229

Final design review report for the RMCS Flammable Gas Detection Interlock  

SciTech Connect

This report document the completion of the formal design review for the RMCS (Rotary Mode Core Sampling) flammable gas detector interlock. This hydrogen/flammable gas interlock, a proposed addition to the RMCS system portable exhauster, in intended to support core sampling operations in waste tanks requiring flammable gas controls. The objective of this review was to approve new drawings at the 100% design completion state. The conclusion reached by the review committee was that the design was acceptable and efforts should continue toward fabrication and delivery.

Corbett, J.E., Westinghouse Hanford

1996-08-20

230

Online visual inspection of self-piercing riveting to determine the quality of the mechanical interlock  

NASA Astrophysics Data System (ADS)

Self-piercing riveting (SPR) has become a significant joining technique for the automotive applications of aluminium sheets. Quality control in this locale has progressed at an altogether more leisurely rate than other areas of mechanical joining (e.g. spotweld) and is underdeveloped. Testing the quality mechanical interlock is often achieved by destructive testing, which results in material and time wastage. The solution is online monitoring of the self-piercing riveting process to provide non-destructive testing of the mechanical interlock. Introducing sensors into the process facilitates real time data acquisition, which can be used to determine the quality of the joint.

Johnson, P.; Cullen, J. D.; Al-Shamma'a, A. I.; Shaw, A.

2007-07-01

231

Periodic Stresses in Gyroscopic Bodies, with Applications to Air Screws  

NASA Technical Reports Server (NTRS)

Report discusses periodic stresses in gyroscopic bodies with applications to air screws caused by particle mass. Report concludes that all modern air screws obey the laws found for plane groups of particles. In particular the two-bladers exert on the shaft a rhythmic gyroscopic torque; the multibladers a steady one; both easily calculable for any given conditions of motion and mass distribution.

Zahm, A F

1918-01-01

232

An integrated model for the performance calculation of Screw Machines  

Microsoft Academic Search

There is a need to develop improved analytical procedures in order to improve performance, reduce noise emission and reduce the manufacturing costs of screw compressors. Most mathematical models, used by industry for screw compressor performance estimation and optimisation, are based on quasi one dimensional calculation of the governing flow equations in a control volume. Despite being fast and accurate for

Ahmed Kovacevic; Elvedin Mujic; Nikola Stosic; Ian K. Smith

233

Performance Analysis of Oil Injected Twin Screw Compressor  

Microsoft Academic Search

Oil injected twin-screw air compressors are widely used for medium pressure applications in cryogenic industries. Conversion of these compressors for helium applications is in great demand due to their inherent advantages. A mathematical model of an oil injected twin-screw compressor has been constructed basing on the laws of perfect gas and standard thermodynamic relations to evaluate compressor efficiencies. The complete

N. Seshaiah; Subrata Kr; Ranjit Kr; Sunil Kr

2006-01-01

234

Fracture mechanisms of retrieved titanium screw thread in dental implant  

Microsoft Academic Search

Titanium and its alloy are increasingly attracting attention for use as biomaterials. However, delayed fracture of titanium dental implants has been reported, and factors affecting the acceleration of corrosion and fatigue have to be determined. The fractured surface of a retrieved titanium screw and metallurgical structures of a dental implant system were analyzed. The outer surface of the retrieved screw

Ken’ichi Yokoyama; Tetsuo Ichikawa; Hiroki Murakami; Youji Miyamoto; Kenzo Asaoka

2002-01-01

235

Scaphoid Osteosynthesis: Early Experience with the Herbert Bone Screw  

Microsoft Academic Search

The results of our first fourteen patients with fractured scaphoids treated with the Herbert bone screw have been disappointing. Six have failed to unite. The operation is technically demanding and there is a high incidence of malpositioning of the screw which correlates with failure to achieve union. This is predictable from initial radiographs and peroperative radiology is advised. The osteosynthesis

D. J. PRING; E. B. HARTLEY; D. J. WILLIAMS

1987-01-01

236

The Herbert Bone Screw: A Ten Year Perspective  

Microsoft Academic Search

It is now over ten years since the Herbert bone screw was first released in Australia. In 1984, Herbert and Fisher first published their experience with the use of this new bone screw in the management of scaphoid fractures. Since that time, there has been a growing interest in the technique and over 60 articles have appeared in the English

T. J. HERBERT; W. E. FISHER; A. W. LEICESTER

1992-01-01

237

Implant augmentation: adding bone cement to improve the treatment of osteoporotic distal femur fractures: a biomechanical study using human cadaver bones.  

PubMed

The increasing problems in the field of osteoporotic fracture fixation results in specialized implants as well as new operation methods, for example, implant augmentation with bone cement. The aim of this study was to determine the biomechanical impact of augmentation in the treatment of osteoporotic distal femur fractures.Seven pairs of osteoporotic fresh frozen distal femora were randomly assigned to either an augmented or nonaugmented group. In both groups, an Orthopaedic Trauma Association 33 A3 fractures was fixed using the locking compression plate distal femur and cannulated and perforated screws. In the augmented group, additionally, 1?mL of polymethylmethacrylate cement was injected through the screw. Prior to mechanical testing, bone mineral density (BMD) and local bone strength were determined. Mechanical testing was performed by cyclic axial loading (100?N to 750?N?+?0.05N/cycle) using a servo-hydraulic testing machine.As a result, the BMD as well as the axial stiffness did not significantly differ between the groups. The number of cycles to failure was significantly higher in the augmented group with the BMD as a significant covariate.In conclusion, cement augmentation can significantly improve implant anchorage in plating of osteoporotic distal femur fractures. PMID:25415673

Wähnert, Dirk; Hofmann-Fliri, Ladina; Richards, R Geoff; Gueorguiev, Boyko; Raschke, Michael J; Windolf, Markus

2014-11-01

238

Semiconstrained distal radioulnar joint prosthesis.  

PubMed

Distal radioulnar joint (DRUJ) problems can occur as a result of joint instability, abutment, or incongruity. The DRUJ is a weight-bearing joint; the ulnar head is frequently excised either totally or partially, and in some cases it is fused, because of degenerative, rheumatoid, or posttraumatic arthritis. Articles about these procedures report the ability to pronate and supinate, but they rarely discuss grip strength, and even less do they address lifting capacity. We report the long term results of the first 35 patients who underwent total DRUJ arthroplasty with the Aptis DRUJ prosthesis after 5 years follow-up. Surgical indications were all causes of dysfunctional DRUJ (degenerative, posttraumatic, autoimmune, congenital). We recorded data for patient demographics, range of motion (ROM), strength, and lifting capacity of the operated and of the nonoperated extremity. Pain and functional assessments were also recorded. The Aptis DRUJ prosthesis, a bipolar self-stabilizing DRUJ endoprosthesis that restores forearm function, consists of a semiconstained and modular implant designed to replace the function of the ulnar head, the sigmoid notch of the radius, and the triangular fibrocartilage ligaments. The surgical technique is presented in detail. The majority of the patients regained adequate ROM and improved their strength and lifting capacity to the operated side. Pain and activities of daily living were improved. Twelve patients experienced complications, most commonly being extensor carpi ulnaris (ECU) tendinitis, ectopic bone formation, bone resorption with stem loosening, low-grade infection, and need for ball replacement. The Aptis total DRUJ replacement prosthesis is an alternative to salvage procedures that enables a full range of motion as well as the ability to grip and lift weights encountered in daily living activities. PMID:24436788

Savvidou, Christiana; Murphy, Erin; Mailhot, Emilie; Jacob, Shushan; Scheker, Luis R

2013-02-01

239

Screw dislocations in GaN  

SciTech Connect

GaN has received much attention over the past few years because of several new applications, including light emitting diodes, blue laser diodes and high-power microwave transistors. One of the biggest problems is a high density of structural defects, mostly dislocations, due to a lack of a suitable lattice-matched substrate since bulk GaN is difficult to grow in large sizes. Transmission Electron Microscopy (TEM) has been applied to study defects in plan-view and cross-sections on samples prepared by conventional techniques such as mechanical thinning and precision ion milling. The density of dislocations close to the sample surface of a 1 mm-thick HVPE sample was in the range of 3x109 cm-2. All three types of dislocations were present in these samples, and almost 50 percent were screw dislocations. Our studies suggest that the core structure of screw dislocations in the same material might differ when the material is grown by different methods.

Liliental-Weber, Zuzanna; Jasinski, Jacek B.; Washburn, Jack; O'Keefe, Michael A.

2002-02-15

240

Performance of Screw Compressor for Small-Capacity Helium Refrigerators  

NASA Astrophysics Data System (ADS)

A helium compressor is one of the important components comprising a cryogenic refrigerator. The purpous of this investigation is to develop a new small-capacity helium screw compressor. The performance of a single-stage compressor at high compression ratio and the cooling performance of the compressor are investigated. A semi-hermetic screw compressor with new profile screw rotors, with which high performance can be obtained, is utilized in this investigation. Lubricating oil is applied to cool the compressor motor and the compressed gas. As a result, an overall isentropic efficiency of 80% is obtained when helium is compressed to a compression ratio of 19.8 with a single-stage screw compressor. At the same time, the temperature of a compressor motor and discharge gas can be maintained at low levels. Therefore, it is found that a single-stage screw compressor can compress helium to high compression ratio.

Urashin, Masayuki; Matsubara, Katsumi; Izunaga, Yasushi

241

Intraosseous screw fixation of anterior cervical graft construct after diskectomy.  

PubMed

This article describes a new technique of intraosseous screw fixation of the cervical spine, as well as a retrospective review of 27 patients who had anterior cervical interbody fusion after diskectomy and fixation with one intraosseous Herbert screw, with a minimum follow-up of 1 year. The study included 19 men and eight women. There were no neurologic complications at final follow-up evaluation. All patients had radiographic evidence of fusion. No screw breakage, back-out, or dislodgement occurred. Optimal intraoperative radiographic evaluation for accurate intraosseous screw placement is recommended. The use of intraosseous screw fixation is a useful addition to the armamentarium of the spine surgeon when fixation of anterior cervical graft after diskectomy is required. One hundred percent rate of union and prevention of complications related to the currently used anterior fixation systems are the major advantages of this method. PMID:8003829

Chang, K W; Lin, G Z; Liu, Y W; Suen, K L; Liang, P L

1994-04-01

242

Cannulated Screw Fixation of Jones Fifth Metatarsal Fractures: A Comparison of Titanium and Stainless Steel Screw Fixation  

Microsoft Academic Search

The classic Jones fracture involves the fifth metatarsal at the level of the proximal diaphyseal-metaphyseal junction. The mainstay of surgical treatment for the Jones fracture is intramedullary screw fixation. There is no consensus of the type or material of screw that should be used. The purpose of this retrospective cohort study was to test the hypothesis that there is no

J. George DeVries; Daniel J. Cuttica; Christopher F. Hyer

2011-01-01

243

Lateral Movement of Screw Dislocations During Homoepitaxial Growth and Devices Yielded Therefrom Free of the Detrimental Effects of Screw Dislocations  

NASA Technical Reports Server (NTRS)

The present invention is related to a method that enables and improves wide bandgap homoepitaxial layers to be grown on axis single crystal substrates, particularly SiC. The lateral positions of the screw dislocations in epitaxial layers are predetermined instead of random, which allows devices to be reproducibly patterned to avoid performance degrading crystal defects normally created by screw dislocations.

Neudeck, Philip G. (Inventor); Powell, J. Anthony (Inventor)

2004-01-01

244

Effect of DDGS, Moisture Content, and Screw Speed on the Physical Properties of Extrudates in Single Screw Extrusion  

Technology Transfer Automated Retrieval System (TEKTRAN)

Three isocaloric (3.5 kcal/g) ingredient blends containing 20, 30, and 40% (wb) DDGS along with soy flour, corn flour, fish meal, mineral and vitamin mix, with the net protein adjusted to 28% (wb) for all blends, were extruded in a single screw laboratory-scale extruder at screw speeds of 100, 130, ...

245

Disorders of the distal biceps brachii tendon.  

PubMed

Pathologic conditions of the distal biceps brachii tendon are of clinical interest, with partial and complete tears being the most common. However, the anatomy of the distal biceps brachii tendon makes imaging of the distal tendon somewhat difficult. An innovation in patient positioning for magnetic resonance (MR) imaging of the distal biceps tendon was recently described in which the patient lies prone with the arm overhead, the elbow flexed to 90 degrees , and the forearm supinated, so that the thumb points superiorly. The acronym FABS (f lexed elbow, abducted shoulder, forearm supinated) has been used to describe this position. The FABS position creates tension in the tendon and minimizes its obliquity and rotation, resulting in a "true" longitudinal view of the tendon. MR imaging and, to a lesser extent, ultrasonography are useful in visualizing the distal tendon and in detecting other pathologic conditions in the cubital fossa. Partial tears are usually characterized by enlargement and abnormal contour of the tendon, along with abnormal intratendinous signal intensity. In complete tears, there is discontinuity and, if the bicipital aponeurosis is also disrupted, retraction. Imaging with FABS positioning can complement conventional MR imaging, especially in the axial plane, in the assessment of the distal biceps tendon. PMID:16160108

Chew, Michael L; Giuffrè, Bruno M

2005-01-01

246

Experimental Investigation About Stamping Behaviour of 3D Warp Interlock Composite Preforms  

NASA Astrophysics Data System (ADS)

Forming of continuous fibre reinforcements and thermoplastic resin commingled prepregs can be performed at room temperature due to its similar textile structure. The "cool" forming stage is better controlled and more economical. The increase of temperature and the resin consolidation phases after the forming can be carried out under the isothermal condition thanks to a closed system. It can avoid the manufacturing defects easily experienced in the non-isothermal thermoforming, in particular the wrinkling [1]. Glass/Polypropylene commingled yarns have been woven inside different three-dimensional (3D) warp interlock fabrics and then formed using a double-curved shape stamping tool. The present study investigates the in-plane and through-thickness behaviour of the 3D warp interlock fibrous reinforcements during forming with a hemispherical punch. Experimental data allow analysing the forming behaviour in the warp and weft directions and on the influence of warp interlock architectures. The results point out that the layer to layer warp interlock preform has a better stamping behaviour, in particular no forming defects and good homogeneity in thickness.

Dufour, Clément; Wang, Peng; Boussu, François; Soulat, Damien

2014-10-01

247

Molecular self-assembly of arene-Ru based interlocked catenane metalla-cages.  

PubMed

Two interlocked trigonal prismatic metalla-cages are formed quantitatively through the self-assembly of ?-electron rich arene-Ru acceptors with a new tridentate donor. Interestingly, non-?-electron rich arene-Ru acceptors furnish simple trigonal prisms when they are combined with a tridentate donor. PMID:24888738

Mishra, Anurag; Dubey, Abhishek; Min, Jin Wook; Kim, Hyunuk; Stang, Peter J; Chi, Ki-Whan

2014-07-18

248

Control and Interlocking System for Bending Magnet Front-end at Indus-2  

SciTech Connect

We present control and interlock system developed for Indus-2 bending magnet front-end. The paper describes in detail the control of various signals associated with the front-end and the interlocking scheme implemented for the installed front-end. The number of signals associated with each front-end is {approx} 75. A control system is designed for monitoring temperature, pressure, airflow, water flow and control of vacuum gauges, fast shutter, water cooled shutter, safety shutter, pneumatic gate valves, sputter ion pump power supplies, beam position monitor etc. Two independent signals are generated for critical components that are used for software interlock and hard-wired interlock. The front-end control system is VME based and window 2000/XP workstation as an operator console. The CPU used is Motorola 68000-processor board of the VME bus having OS-9 real time operating system. One VME crate serves a cluster of 2-3 front ends. The communication between the VME and the workstation is linked over RS232 serial communication. The sputter ion power supplies are connected over isolated RS485 network. Critical protection features are implemented so that no single failure can render the system unsafe. This is implemented by providing two independent chains of protection (1) Hard wired in which relay logic is used and (2) Software. A Graphical User Interface (GUI) is developed using Lab view Version 7.0.

Kane, Sanjeev R.; Garg, Chander Kant; Nandedkar, R. V. [Synchrotron Utilization and Material Research Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India)

2007-01-19

249

Novel physically loaded and interlocked electrode developed for ionic polymer-metal composites (IPMCs)  

Microsoft Academic Search

Described is a novel fabrication process of manufacturing ionic polymeric metal composites (IPMC's) biomimetic sensors, actuators and artificial muscles equipped with physically loaded and interlocked (PLI) electrodes. The underlying principle of processing this novel PLI-IPMC's is to first physically load a conductive primary powder into the ionic polymer network forming a dispersed particulate layer. This primary layer functions as a

Mohsen Shahinpoor; Kwang J. Kim

2001-01-01

250

Internal Iliac Artery Embolization during an Endovascular Aneurysm Repair with Detachable Interlock Microcoils  

PubMed Central

Objective The purpose of this study was to evaluate the effectiveness of detachable interlock microcoils for an embolization of the internal iliac artery during an endovascular aneurysm repair (EVAR). Materials and Methods A retrospective review was conducted on 40 patients with aortic aneurysms, who had undergone an EVAR between January 2010 and March 2012. Among them, 16 patients were referred for embolization of the internal iliac artery for the prevention of type II endoleaks. Among 16 patients, 13 patients underwent embolization using detachable interlock microcoils during an EVAR. Computed tomographic angiographies and clinical examinations were performed during the follow-up period. Technical success, clinical outcome, and complications were reviewed. Results Internal iliac artery embolizations using detachable interlock microcoils were technically successful in all 13 patients, with no occurrence of procedure-related complications. Follow-up imaging was accomplished in the 13 cases. In all cases, type II endoleak was not observed with computed tomographic angiography during the median follow-up of 3 months (range, 1-27 months) and the median clinical follow-up of 12 months (range, 1-27 months). Two of 13 (15%) patients had symptoms of buttock pain, and one patient died due to underlying stomach cancer. No significant clinical symptoms such as bowel ischemia were observed. Conclusion Internal iliac artery embolization during an EVAR using detachable interlock microcoils to prevent type II endoleaks appears safe and effective, although this should be further proven in a larger population. PMID:25246822

Kim, Woo Chul; Hong, Kee Chun; Kim, Jang Yong; Cho, Soon Gu; Park, Jae Young

2014-01-01

251

Control and Interlocking System for Bending Magnet Front-end at Indus-2  

NASA Astrophysics Data System (ADS)

We present control and interlock system developed for Indus-2 bending magnet front-end. The paper describes in detail the control of various signals associated with the front-end and the interlocking scheme implemented for the installed front-end. The number of signals associated with each front-end is ˜ 75. A control system is designed for monitoring temperature, pressure, airflow, water flow and control of vacuum gauges, fast shutter, water cooled shutter, safety shutter, pneumatic gate valves, sputter ion pump power supplies, beam position monitor etc. Two independent signals are generated for critical components that are used for software interlock and hard-wired interlock. The front-end control system is VME based and window 2000/XP workstation as an operator console. The CPU used is Motorola 68000-processor board of the VME bus having OS-9 real time operating system. One VME crate serves a cluster of 2-3 front ends. The communication between the VME and the workstation is linked over RS232 serial communication. The sputter ion power supplies are connected over isolated RS485 network. Critical protection features are implemented so that no single failure can render the system unsafe. This is implemented by providing two independent chains of protection (1) Hard wired in which relay logic is used and (2) Software. A Graphical User Interface (GUI) is developed using Lab view Version 7.0.

Kane, Sanjeev R.; Garg, Chander Kant; Nandedkar, R. V.

2007-01-01

252

Use of specialized bone screws for intermaxillary fixation.  

PubMed

Fixation of the injured mandible to the maxilla is a proven method of stabilizing mandibular fractures and ensuring proper occlusion. The authors report their results with new specialized intraoral bone screws (IMF Screw System; Howmedica Leibinger, Inc., Carrollton, TX) that are designed for the purpose of achieving intermaxillary fixation (IMF). Nineteen patients were placed into rigid IMF using IMF screws alone. Indications were nondisplaced mandibular fractures; symphyseal, body, and angle fractures; midfacial fractures requiring temporary IMF; and edentulous patients with any of these fracture types and an adequate prosthesis. All procedures were performed with the patient under general anesthesia. The authors found that the operative time was markedly shorter than with standard IMF techniques, patient satisfaction was high, and there were no infections related to the screws. All 19 patients remained in stable, accurate occlusion and had adequate healing. One patient continues to have paraesthesias in the mental nerve distribution after screw removal. Although there is the potential for tooth and nerve injury when screws are placed improperly, the IMF Screw System seems to be a safe and reliable method of achieving secure mandibular fixation. PMID:10696041

Schneider, A M; David, L R; DeFranzo, A J; Marks, M W; Molnar, J A; Argenta, L C

2000-02-01

253

Salvaging the Pullout Strength of Stripped Screws in Osteoporotic Bone  

PubMed Central

Our goal was to determine whether the pullout strength of stripped screw holes in osteoporotic bone could be increased with readily available materials from the operating room. We inserted 3.5-mm stainless steel nonlocking self-tapping cortical screws bicortically into 5 osteoporotic humeri. Each screw was first stripped by rotating it 1 full turn past maximum torque. In the control group, the screw was pulled out using an MTS machine (858; MTS Inc, Eden Prairie, Minnesota). In the treatment groups, the screw was removed, the hole was augmented with 1 of the 3 materials (stainless steel wire, polysorb suture, or polyethylene terephthalate glycol plastic sheet), and the screws were replaced and then pulled out. The effect of material on pullout strength was checked for significance (P < .05) using a general linearized latent and mixed model (Stata10; StataCorp, College Station, Texas). The mean (95% confidence interval) pullout strength for the unaugmented hole was 138 N (range 88-189), whereas the holes augmented with plastic, suture, or wire had mean pullout strengths of 255 N (range 177-333), 228 N (range 149-308), and 396 N (range 244-548), respectively. Although wire augmentation resulted in pullout strength that was significantly greater than that of the unaugmented screw, it was still below that of the intact construct. PMID:24093076

Pechon, Pierre H. M.; Mears, Simon C.; Langdale, Evan R.; Belkoff, Stephen M.

2013-01-01

254

Salvaging the pullout strength of stripped screws in osteoporotic bone.  

PubMed

Our goal was to determine whether the pullout strength of stripped screw holes in osteoporotic bone could be increased with readily available materials from the operating room. We inserted 3.5-mm stainless steel nonlocking self-tapping cortical screws bicortically into 5 osteoporotic humeri. Each screw was first stripped by rotating it 1 full turn past maximum torque. In the control group, the screw was pulled out using an MTS machine (858; MTS Inc, Eden Prairie, Minnesota). In the treatment groups, the screw was removed, the hole was augmented with 1 of the 3 materials (stainless steel wire, polysorb suture, or polyethylene terephthalate glycol plastic sheet), and the screws were replaced and then pulled out. The effect of material on pullout strength was checked for significance (P < .05) using a general linearized latent and mixed model (Stata10; StataCorp, College Station, Texas). The mean (95% confidence interval) pullout strength for the unaugmented hole was 138 N (range 88-189), whereas the holes augmented with plastic, suture, or wire had mean pullout strengths of 255 N (range 177-333), 228 N (range 149-308), and 396 N (range 244-548), respectively. Although wire augmentation resulted in pullout strength that was significantly greater than that of the unaugmented screw, it was still below that of the intact construct. PMID:24093076

Pechon, Pierre H M; Mears, Simon C; Langdale, Evan R; Belkoff, Stephen M

2013-06-01

255

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. PMID:24894637

2014-01-01

256

SCREW COMPRESSOR CHARACTERISTICS FOR HELIUM REFRIGERATION SYSTEMS  

SciTech Connect

The oil injected screw compressors have practically replaced all other types of compressors in modern helium refrigeration systems due to their large displacement capacity, minimal vibration, reliability and capability of handling helium's high heat of compression.At the present state of compressor system designs for helium systems, typically two-thirds of the lost input power is due to the compression system. Therefore it is important to understand the isothermal and volumetric efficiencies of these machines to help properly design these compression systems to match the refrigeration process. This presentation summarizes separate tests that have been conducted on Sullair compressors at the Superconducting Super-Collider Laboratory (SSCL) in 1993, Howden compressors at Jefferson Lab (JLab) in 2006 and Howden compressors at the Spallation Neutron Source (SNS) in 2006. This work is part of an ongoing study at JLab to understand the theoretical basis for these efficiencies and their loss

Ganni, Venkatarao; Knudsen, Peter; Creel, Jonathan; Arenius, Dana; Casagrande, Fabio; Howell, Matt

2008-03-01

257

Screw Compressor Characteristics for Helium Refrigeration Systems  

NASA Astrophysics Data System (ADS)

The oil injected screw compressors have practically replaced all other types of compressors in modern helium refrigeration systems due to their large displacement capacity, minimal vibration, reliability and capability of handling helium's high heat of compression. At the present state of compressor system designs for helium systems, typically two-thirds of the lost input power is due to the compression system. Therefore it is important to understand the isothermal and volumetric efficiencies of these machines to help properly design these compression systems to match the refrigeration process. This presentation summarizes separate tests that have been conducted on Sullair compressors at the Superconducting Super-Collider Laboratory (SSCL) in 1993, Howden compressors at Jefferson Lab (JLab) in 2006 and Howden compressors at the Spallation Neutron Source (SNS) in 2006. This work is part of an ongoing study at JLab to understand the theoretical basis for these efficiencies and their loss mechanisms, as well as to implement practical solutions.

Ganni, V.; Knudsen, P.; Creel, J.; Arenius, D.; Casagrande, F.; Howell, M.

2008-03-01

258

Comparison of Expansive Pedicle Screw and Polymethylmethacrylate-Augmented Pedicle Screw in Osteoporotic Sheep Lumbar Vertebrae: Biomechanical and Interfacial Evaluations  

PubMed Central

Background It was reported that expansive pedicle screw (EPS) and polymethylmethacrylate-augmented pedicle screw (PMMA-PS) could be used to increase screw stability in osteoporosis. However, there are no studies comparing the two kinds of screws in vivo. Thus, we aimed to compare biomechanical and interfacial performances of EPS and PMMA-PS in osteoporotic sheep spine. Methodology/Principal Findings After successful induction of osteoporotic sheep, lumbar vertebrae in each sheep were randomly divided into three groups. The conventional pedicle screw (CPS) was inserted directly into vertebrae in CPS group; PMMA was injected prior to insertion of CPS in PMMA-PS group; and the EPS was inserted in EPS group. Sheep were killed and biomechanical tests, micro-CT analysis and histological observation were performed at both 6 and 12 weeks post-operation. At 6-week and 12-week, screw stabilities in EPS and PMMA-PS groups were significantly higher than that in CPS group, but there were no significant differences between EPS and PMMA-PS groups at two study periods. The screw stability in EPS group at 12-week was significantly higher than that at 6-week. The bone trabeculae around the expanding anterior part of EPS were more and denser than that in CPS group at 6-week and 12-week. PMMA was found without any degradation and absorption forming non-biological “screw-PMMA-bone” interface in PMMA-PS group, however, more and more bone trabeculae surrounded anterior part of EPS improving local bone quality and formed biological “screw-bone” interface. Conclusions/Significance EPS can markedly enhance screw stability with a similar effect to the traditional method of screw augmentation with PMMA in initial surgery in osteoporosis. EPS can form better biological interface between screw and bone than PMMA-PS. In addition, EPS have no risk of thermal injury, leakage and compression caused by PMMA. We propose EPS has a great application potential in augmentation of screw stability in osteoporosis in clinic. PMID:24086381

Zhang, Bo; Xie, Qing-yun; Wang, Cai-ru; Liu, Jin-biao; Liao, Dong-fa; Jiang, Kai; Lei, Wei; Pan, Xian-ming

2013-01-01

259

Pullout of a lumbar plate with varying screw lengths  

PubMed Central

Background Screw length pertains to stability in various orthopedic fixation devices. There is little or no information on the relationship between plate pullout strength and screw length in anterior lumbar interbody fusion (ALIF) plate constructs in the literature. Such a description may prove useful, especially in the treatment of osteoporotic patients where maximizing construct stability is of utmost importance. Our purpose is to describe the influence of screw length on ALIF plate stability in severely and mildly osteoporotic bone foam models. Methods Testing was performed on polyurethane foam blocks with densities of 0.08 g/cm3 and 0.16 g/cm3. Four-screw, single-level ALIF plate constructs were secured to the polyurethane foam blocks by use of sets of self-tapping cancellous bone screws that were 20, 24, 28, 32, and 36 mm in length and 6.0 mm in diameter. Plates were pulled out at 1 mm/min to failure, as defined by consistently decreasing load despite increasing displacement. Results Pullout loads in 0.08-g/cm3 foam for 20-, 24-, 28-, 32-, and 36-mm screws averaged 303, 388, 479, 586, and 708 N, respectively, increasing at a mean of 25.2 N/mm. In 0.16-g/cm3 foam, pullout loads for 20-, 24-, 28-, 32-, and 36-mm screws averaged 1004, 1335, 1569, 1907, and 2162 N, respectively, increasing at a mean of 72.2 N/mm. Conclusions The use of longer screws in ALIF plate installation is expected to increase construct stability. Stabilization from screw length in osteoporotic patients, however, is limited.

Palmer, Daniel Kyle; Rios, David; Patacxil, Wyzscx Merfil; Williams, Paul A.; Cheng, Wayne K.; ?nceo?lu, Serkan

2012-01-01

260

Torsional stability of interference screws derived from bovine bone - a biomechanical study  

Microsoft Academic Search

BACKGROUND: In the present biomechanical study, the torsional stability of different interference screws, made of bovine bone, was tested. Interference screws derived from bovine bone are a possible biological alternative to conventional metallic or bioabsorbable polymer interference screws. METHODS: In the first part of the study we compared the torsional stability of self-made 8 mm Interference screws (BC) and a

Joscha Bauer; Turgay Efe; Silke Herdrich; Leo Gotzen; Bilal Farouk El-Zayat; Jan Schmitt; Nina Timmesfeld; Markus Dietmar Schofer

2010-01-01

261

Interference screw position and hamstring graft location for anterior cruciate ligament reconstruction  

Microsoft Academic Search

Anterior cruciate ligament reconstruction with hamstring tendon graft and interference screw fixation has recently been considered. Concerns for the use of interference screws with soft tissue grafts include damage to the graft during screw insertion, decreased fixation strength, and a decrease in the bone-tendon contact area for healing within the tunnel when the screw is placed in an eccentric position.

PT Simonian; PS Sussmann; TH Baldini; HC Crockett; TL Wickiewicz

1998-01-01

262

Comparison of Cotrel-Dubousset pedicle screws and hooks in the treatment of idiopathic scoliosis  

Microsoft Academic Search

Eighty-two patients with idiopathic scoliosis were treated by Cotrel-Dubousset instrumentation between 1987 and 1991. Twenty were treated with hooks only, 47 with screws and hooks, and 15 with screws only. The methods were compared and the findings showed that screw fixation can be used in the thoracic spine without neurological complications. The screws provided immediate stability with rigid fixation, together

S. I. Suk; C. K. Lee; H. J. Min; K. H. Cho; J. H. Oh

1994-01-01

263

Manufacture of composite screw rotors for air compressors by RTM process  

Microsoft Academic Search

Screw rotors, the key parts of screw compressors, are widely used in compressing air and refrigerant due to their high productivity, compact size, low noise and easy maintenance. In general, a screw compressor unit is composed of female and male rotors of complex geometric shape. The manufacturing cost and time of the screw rotors are high because the complicated helical

Jung Do Suh; Dai Gil Lee

2001-01-01

264

2D-fluoroscopic navigated percutaneous screw fixation of pelvic ring injuries - a case series  

Microsoft Academic Search

BACKGROUND: Screw fixation of pelvic ring fractures is a common, but demanding procedure and navigation techniques were introduced to increase the precision of screw placement. The purpose of this case series was the evaluation of screw misplacement rate and functional outcome of percutaneous screw fixation of pelvic ring disruptions using a 2D navigation system. METHODS: Between August 2004 and December

Florian Gras; Ivan Marintschev; Arne Wilharm; Kajetan Klos; Thomas Mückley; Gunther O Hofmann

2010-01-01

265

Computer assisted screw insertion into real 3D rapid prototyping pelvis models  

Microsoft Academic Search

Objective. Show the use of computer navigation in exact screw positioning in the different pelvic bones.Background. Computer assisted pedicle screw insertion in the spine is an established procedure. Screw fixation is also used in highly difficult pelvic and hip surgery (arthroplasty revision surgery and tumor surgery).Design. Insert as long screws as possible with computer navigation into the different bones of

P Peters; F Langlotz; L.-P Nolte

2002-01-01

266

A novel technique for accurate Poller (blocking) screw placement.  

PubMed

Achieving good results with intramedullary nailing of oblique long bone fractures at the metaphyseal-diaphyseal junction can be difficult. There is a strong tendency for axial displacement and an association with characteristic malalignment of the short fragment. Poller or blocking screws have been shown to be effective in aiding fracture reduction. While several papers describe methods for screw placement, these are confusing to understand, difficult to follow in clinical practice and not always applicable. Here we describe a new, simple, reproducible and easy to use method for ensuring accurate Poller screw placement, in order to maximise the benefits of their use and achieve good overall results. PMID:24629702

Hannah, Andrew; Aboelmagd, Tariq; Yip, Grace; Hull, Peter

2014-06-01

267

Intersection of screw dislocations in fcc crystals during torsional deformation  

NASA Astrophysics Data System (ADS)

Dislocation reactions, including dislocation intersections during various processes in crystals, play an important and often crucial role. This is most pronounced during plastic deformation of crystalline solids, which attracts particular interest from researchers. Intersection of screw dislocations in fcc crystals during their deformation by uniaxial tension and compression was studied by A. Cottrell [1]. It was shown that the intersection of similar screw dislocations moving toward each other results in the formation of interstitial thresholds on them; in the case of intersection of opposite screw dislocations, vacancy thresholds are formed on them.

Myshlyaev, M. M.

2012-03-01

268

Biocompatibility studies of titanium-based alloy pedicle screw and rod system  

Microsoft Academic Search

Background context: Few histological studies of pedicle screw and rod systems have been done, and spinal surgery with pedicle screw and rod system is increasing.Purpose: To know the biocompatibility of pedicle screw and rod systems histologically. Study design\\/setting: Titanium-based alloy pedicle screws were removed from 20 patients. Histological studies of the tissue response to the screws were performed by light

Kazuhiro Yamaguchi; Hiroaki Konishi; Shinichiro Hara; Yoshinori Motomura

2001-01-01

269

Partial rupture of the distal biceps tendon.  

PubMed

Partial rupture of the distal biceps tendon is a relatively rare event, and various degrees of partial tendon tears have been reported. In the current study four patients with partial atraumatic distal biceps tendon tears (mean age, 59 years; range, 40-82 years) are reported. In all four patients, a common clinical pattern emerged. Pain at the insertion of the distal biceps tendon in the radius unrelated to any traumatic event was the main symptom. In all patients the diagnosis was based on magnetic resonance imaging or computed tomography imaging. In three of four patients the partial rupture of the tendon caused a significant bursalike lesion. The typical appearance was a partially ruptured biceps tendon, with contrast enhancement signaling the degree of degeneration, tenosynovitis, and soft tissue swelling extending along the tendon semicircular to the proximal radius. In three patients, conservative treatment was successful. Only one patient needed surgery, with reinsertion of the tendon resulting in total functional recovery. PMID:10818980

Dürr, H R; Stäbler, A; Pfahler, M; Matzko, M; Refior, H J

2000-05-01

270

Osteochondritis of the Distal Tibial Epiphysis  

PubMed Central

Osteochondritis of the distal tibial epiphysis is a very rare entity. 9 cases have been described in 7 articles and 8 other cases have been mentioned in textbooks. This paper describes the 10th case of osteochondritis of the distal tibial epiphysis and summarizes the clinical and radiological presentations of the 9 other cases. The etiology of this entity is well debated in the literature. We believe that it results from a vascular abnormality in the distal tibial epiphysis associated with a mechanical stress (trauma, excessive overload, etc.). Since it is a self-limited disease, the prognosis is good and the younger the patient is the better the prognosis will be. In general, this entity responds well to conservative treatment. PMID:23193412

EL Hajj, Firass; Sebaaly, Amer; Kharrat, Khalil; Ghanem, Ismat

2012-01-01

271

Wet-gas compression in twin-screw multiphase pumps  

E-print Network

Multiphase pumping with twin-screw pumps is a relatively new technology that has been proven successful in a variety of field applications. By using these pumps to add energy to the combined gas and liquid wellstream with minimal separation...

Chan, Evan

2009-05-15

272

Probabilistic model and experimental identification of screw-attachment in  

E-print Network

[cardboard-plaster-cardboard (CPC) multilayer] screwed with a metal frame on both sides, and are made of a body of plaster stickled with two sheets of cardboard on both sides. They are linked with the metal

Paris-Sud XI, Université de

273

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

274

Volar Percutaneous Screw Fixation for Scaphoid Waist Delayed Union  

Microsoft Academic Search

Volar percutaneous cannulated screw fixation of acute scaphoid waist fractures reportedly produces high rates of healing and\\u000a early return to work, but the method has not been reported for treating scaphoid waist delayed unions. We therefore report\\u000a the surgical results of percutaneous screw fixation in scaphoid waist delayed union in 12 patients. All patients were male\\u000a with an average age

Jae Kwang Kim; Jong Oh Kim; Seung Yup Lee

2010-01-01

275

Minimal Surfaces, Screw Dislocations, and Twist Grain Boundaries  

Microsoft Academic Search

Large twist-angle grain boundaries in layered structures are often described\\u000aby Scherk's first surface whereas small twist-angle grain boundaries are\\u000ausually described in terms of an array of screw dislocations. We show that\\u000athere is no essential distinction between these two descriptions and that, in\\u000aparticular, their comparative energetics depends crucially on the core\\u000astructure of their screw-dislocation topological defects.

Randall D. Kamien; T. C. Lubensky

1999-01-01

276

Tapered orthodontic miniscrews induce bone - screw cohesion following immediate loading  

Microsoft Academic Search

SUMMARY The aim of this study was to investigate the initial stability of tapered orthodontic miniscrews (T-type screws) after placement, the necessity of a healing period, and the propriety of immediate loading. Twenty male Wistar rats with a mean age of 20 weeks were divided into two groups. In the immediate- loading groups, straight orthodontic miniscrews (S-type screws) and T-type

Shinya Yano; Mituru Motoyoshi; Miwa Uemura; Akiko Ono; Noriyoshi Shimizu

2006-01-01

277

Screw dislocation driven growth of nanomaterials.  

PubMed

Nanoscience and nanotechnology impact our lives in many ways, from electronic and photonic devices to biosensors. They also hold the promise of tackling the renewable energy challenges facing us. However, one limiting scientific challenge is the effective and efficient bottom-up synthesis of nanomaterials. We can approach this core challenge in nanoscience and nanotechnology from two perspectives: (a) how to controllably grow high-quality nanomaterials with desired dimensions, morphologies, and material compositions and (b) how to produce them in a large quantity at reasonable cost. Because many chemical and physical properties of nanomaterials are size- and shape-dependent, rational syntheses of nanomaterials to achieve desirable dimensionalities and morphologies are essential to exploit their utilities. In this Account, we show that the dislocation-driven growth mechanism, where screw dislocation defects provide self-perpetuating growth steps to enable the anisotropic growth of various nanomaterials at low supersaturation, can be a powerful and versatile synthetic method for a wide variety of nanomaterials. Despite significant progress in the last two decades, nanomaterial synthesis has often remained an "art", and except for a few well-studied model systems, the growth mechanisms of many anisotropic nanostructures remain poorly understood. We strive to go beyond the empirical science ("cook-and-look") and adopt a fundamental and mechanistic perspective to the anisotropic growth of nanomaterials by first understanding the kinetics of the crystal growth process. Since most functional nanomaterials are in single-crystal form, insights from the classical crystal growth theories are crucial. We pay attention to how screw dislocations impact the growth kinetics along different crystallographic directions and how the strain energy of defected crystals influences their equilibrium shapes. Furthermore, such inquiries are supported by detailed structural investigation to identify the evidence of dislocations. The dislocation-driven growth mechanism not only can unify the various explanations behind a wide variety of exotic nanoscale morphologies but also allows the rational design of catalyst-free solution-phase syntheses that could enable the scalable and low cost production of nanomaterials necessary for large scale applications, such as solar and thermoelectric energy conversions, energy storage, and nanocomposites. In this Account, we discuss the fundamental theories of the screw dislocation driven growth of various nanostructures including one-dimensional nanowires and nanotubes, two-dimensional nanoplates, and three-dimensional hierarchical tree-like nanostructures. We then introduce the transmission electron microscopy (TEM) techniques to structurally characterize the dislocation-driven nanomaterials for future searching and identifying purposes. We summarize the guidelines for rationally designing the dislocation-driven growth and discuss specific examples to illustrate how to implement the guidelines. By highlighting our recent discoveries in the last five years, we show that dislocation growth is a general and versatile mechanism that can be used to grow a variety of nanomaterials via distinct reaction chemistry and synthetic methods. These discoveries are complemented by selected examples of anisotropic crystal growth from other researchers. The fundamental investigation and development of dislocation-driven growth of nanomaterials will create a new dimension to the rational design and synthesis of increasingly complex nanomaterials. PMID:23738750

Meng, Fei; Morin, Stephen A; Forticaux, Audrey; Jin, Song

2013-07-16

278

Cervical screw missing secondary to delayed esophageal fistula: case report.  

PubMed

Although anterior surgical approaches to the cervical spine have become popular and safe in recent years, they also have some complications. We present a case of loss of an anterior cervical plate screw by the natural tracts. The patient was a 47- year-old woman who was operated on for cervical spondylotic myelopathy at another institution. Surgical interference included two levels of anterior discectomy, iliac graft placement and fixation using plate and screws. Two years later, plate dislocation and partial migration of the upper screws were observed. After 7 years the patient complained of dysphagia and she accepted removal of the osteosynthesis. Radiographical examination showed that one of the upper screws was missing and two lower screws were broken. Esophageal perforation was found during the surgery and repaired. Further progress was favourable. Complications associated with esophageal perforation may range from massive infection and death to spontaneous recovery. Erosion of the esophageal wall due to extruded bulky constructs may lead to a persistent fistula, abscess or septic diffusion. Spontaneous perforation of the esophagus and screw loss via the gastrointestinal tract make this case interesting.. PMID:19847769

Cagli, Sedat; Isik, H Serdar; Zileli, Mehmet

2009-10-01

279

Percutaneous iliosacral screw placement using image guided techniques.  

PubMed

A computer assisted technique of iliosacral screw placement that is applicable to unstable pelvic ring fractures is proposed. The goals are to operate noninvasively with a percutaneous procedure to decrease the complications of surgical exposure and to provide greater accuracy in locating the close neurovascular structures. Preoperative computed tomographic images of the pelvis are provided and a computed tomography three-dimensional model is built. In this model, the optimal trajectories for the drilling are planned. An ultrasound based registration is performed intraoperatively. This registration is the most original part of this work. After performing the passive drilling guidance step, the surgeon places the screws. The accuracy of the ultrasound based registration is checked by comparison with a standard surface based registration at the end of the test experiment. Each screw position is verified by a computed tomographic examination. Four human anatomic specimen pelves were tested with three screw insertions for each pelvis (12 screws). All of the screws were considered to be placed correctly. The method is safe and encourages the start of clinical application. PMID:9755769

Tonetti, J; Carrat, L; Lavalleé, S; Pittet, L; Merloz, P; Chirossel, J P

1998-09-01

280

Next Generation Fast RF Interlock Module and ATCA Adapter for ILC High Availability RF Test Station Demonstration  

SciTech Connect

High availability interlocks and controls are required for the ILC (International Linear Collider) L-Band high power RF stations. A new F3 (Fast Fault Finder) VME module has been developed to process both fast and slow interlocks using FPGA logic to detect the interlock trip excursions. This combination eliminates the need for separate PLC (Programmable Logic Controller) control of slow interlocks. Modules are chained together to accommodate as many inputs as needed. In the next phase of development the F3's will be ported to the new industry standard ATCA (Advanced Telecom Computing Architecture) crate (shelf) via a specially designed VME adapter module with IPMI (Intelligent Platform Management Interface). The goal is to demonstrate auto-failover and hot-swap for future partially redundant systems.

Larsen, R

2009-10-17

281

Interlocking Cross-Laminatd Timber (ICLT) for Rural Architecture Ryan E. Smith & Jeff Cramer, ITAC, University of Utah  

E-print Network

& Jeff Cramer, ITAC, University of Utah http://itac.utah.edu Interlocking Cross - Department of Agriculture, Forest Products Laboratory University of Utah, Technology Commercialization Opportunity State of Utah, Centers of Excellence Grant Kip Apostol

Tipple, Brett

282

Pullout strength of misplaced pedicle screws in the thoracic and lumbar vertebrae - A cadaveric study  

PubMed Central

Background: The objective of this cadaveric study was to analyze the effects of iatrogenic pedicle perforations from screw misplacement on the mean pullout strength of lower thoracic and lumbar pedicle screws. We also investigated the effect of bone mineral density (BMD), diameter of pedicle screws, and the region of spine on the pullout strength of pedicle screws. Materials and Methods: Sixty fresh human cadaveric vertebrae (D10–L2) were harvested. Dual-energy X-ray absorptiometry (DEXA) scan of vertebrae was done for BMD. Titanium pedicle screws of different diameters (5.2 and 6.2 mm) were inserted in the thoracic and lumbar segments after dividing the specimens into three groups: a) standard pedicle screw (no cortical perforation); b) screw with medial cortical perforation; and c) screw with lateral cortical perforation. Finally, pullout load of pedicle screws was recorded using INSTRON Universal Testing Machine. Results: Compared with standard placement, medially misplaced screws had 9.4% greater mean pullout strength and laterally misplaced screws had 47.3% lesser mean pullout strength. The pullout strength of the 6.2 mm pedicle screws was 33% greater than that of the 5.2 mm pedicle screws. The pullout load of pedicle screws in lumbar vertebra was 13.9% greater than that in the thoracic vertebra (P = 0.105), but it was not statistically significant. There was no significant difference between pullout loads of vertebra with different BMD (P = 0.901). Conclusion: The mean pullout strength was less with lateral misplaced pedicle screws while medial misplaced pedicle screw had more pullout strength. The pullout load of 6.2 mm screws was greater than that of 5.2 mm pedicle screws. No significant correlation was found between bone mineral densities and the pullout strength of vertebra. Similarly, the pullout load of screw placed in thoracic and lumbar vertebrae was not significantly different. PMID:23798753

Saraf, Shyam K; Singh, Ravindra P; Singh, Vakil; Varma, Ashish

2013-01-01

283

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. PMID:20591177

2010-01-01

284

Solid and hollow pedicle screws affect the electrical resistance: A potential source of error with stimulus-evoked electromyography  

PubMed Central

Background: Although stimulus evoked electromyography (EMG) is commonly used to confirm the accuracy of pedicle screw placement. There are no studies to differentiate between solid screws and hollow screws to the electrical resistance of pedicle screws. We speculate that the electrical resistance of the solid and hollow pedicle screws may be different and then a potential source of error with stimulus-evoked EMG may happen. Materials and Methods: Resistance measurements were obtained from 12 pedicle screw varieties (6 screws of each manufacturer) across the screw shank based on known constant current and measured voltage. The voltage was measured 5 times at each site. Results: Resistance of all solid screws ranged from 0.084 ? to 0.151 ? (mean =0.118 ± 0.024 ?) and hollow screws ranged from 0.148 ? to 0.402 ? (mean = 0.285 ± 0.081 ?). There was a significant difference of resistance between the solid screws and hollow screws (P < 0.05). The screw with the largest diameter no matter solid screws or hollow screws had lower resistance than screws with other diameters. No matter in solid screws group or hollow screws group, there were significant differences (P < 0.05) between the 5.0 mm screws and 6.0 mm screws, 6.0 mm screws and 7.0 mm screws, 5.0 mm screws and 7.0 mm screws, 4.5 mm screws and 5.5 mm screws, 5.5 mm screws and 6.5 mm screws, 4.5 mm screws and 6.5 mm screws. The resistance of hollow screws was much larger than the solid screws in the same diameter group (P < 0.05). Conclusions: Hollow pedicle screws have the potential for high electrical resistance compared to the solid pedicle screws and therefore may affect the EMG response during stimulus-evoked EMG testing in pedicle screw fixation especially in minimally invasive percutaneous pedical screw fixation surgery. PMID:23960278

Wang, Hongwei; Liao, Xinhua; Ma, Xianguang; Li, Changqing; Han, Jianda; Zhou, Yue

2013-01-01

285

NSTX Protection And Interlock Systems For Coil And Powers Supply Systems  

SciTech Connect

NSTX at Princeton Plasma Physics Laboratory (PPPL) requires sophisticated plasma positioning control system for stable plasma operation. TF magnetic coils and PF magnetic coils provide electromagnetic fields to position and shape the plasma vertically and horizontally respectively. NSTX utilizes twenty six coil power supplies to establish and initiate electromagnetic fields through the coil system for plasma control. A power protection and interlock system is utilized to detect power system faults and protect the TF coils and PF coils against excessive electromechanical forces, overheating, and over current. Upon detecting any fault condition the power system is restricted, and it is either prevented from initializing or suppressed to de-energize coil power during pulsing. Power fault status is immediately reported to the computer system. This paper describes the design and operation of NSTX's protection and interlocking system and possible future expansion.

X. Zhao, S. Ramakrishnan, J. Lawson, C.Neumeyer, R. Marsala, H. Schneider, Engineering Operations

2009-09-24

286

Reconstruction of the anterior cruciate ligament using poly- l-lactide interference screws or titanium screws: a comparative study  

Microsoft Academic Search

In the present clinical trial, interference screws, made of poly-l-lactic acid and applied in 46 knees, were compared to titanium screws employed in 45 knees for reconstructing the anterior cruciate ligament using bone–patellar tendon–bone. An identical surgical technique was applied to both groups; and neither group disclosed apparent side effects such as synovitis caused by hydrolysis of the PLLA or

Akihiro Kotani; Yoshiaki Ishii

2001-01-01

287

An analytical investigation of high-temperature heat pump system with screw compressor and screw expander for power recovery  

Microsoft Academic Search

An analytical investigation of a high-temperature heat pump system was developed to estimate the thermal cycle and to assess the thermal fluids for their high-temperature delivery (up to 180°C) capacities without decomposition or the use of lubricant mechanisms. Then, a screw-type compressor was applied in the above conditions. Furthermore, a screw expander was also used as a replacement for the

I. Tamura; H. Taniguchi; H. Sasaki; R. Yoshida; I. Sekiguchi; M. Yokogawa

1997-01-01

288

Fixation strength of the interference screw in the femoral tunnel: The effect of screw divergence on the coronal plane.  

PubMed

Clinical studies to examine the effect of screw divergence have not been applied to the fixation of hamstring grafts. A few previous reports have addressed the correlations between the loss of pullout strength and divergence on hamstring tendon fixation in biomechanical tests. The purpose of this study was to examine the effect of interference screw divergence on the coronal plane when digital flexor tendons were fixed with an interference screw. Twenty fresh porcine hindlimb specimens were chosen. The grafts were fixed using titanium soft tissue interference screws. The hindlimbs were divided into two groups according to the insertion method of the screw. The screw was placed along the graft parallel to the long axis of the femoral tunnel in 10 specimens (parallel placement group), and the others were placed laterally at a 15° divergent angle from the bone tunnel on the coronal plane (divergence group). The cyclic-loading test was loaded for 1500cycles. Five specimens failed because of a pull-out of the tendon in divergence group. The number of specimens that failed before the completion of cycles in the divergence group was significantly greater than that in the parallel placement group. Although the residual displacement after 1500cycles for the divergence group was greater than that for the parallel placement group, no statistically significant difference was found between the groups. This study suggests that the screw placed laterally at a 15° divergent angle on the coronal plane decreases the fixation strength of the digital flexor tendons fixed with an interference screw. PMID:20199864

Ninomiya, Tadaaki; Tachibana, Yomei; Miyajima, Tsuyoshi; Yamazaki, Katsuhiko; Oda, Hiromi

2011-03-01

289

Helical Screw Expander Evaluation Project. Final report  

SciTech Connect

A functional 1-MW geothermal electric power plant that featured a helical screw expander was produced and then tested in Utah in 1978 to 1979 with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing operation on two-phase geothermal fluids. The Project also produced a computer-equipped data system, an instrumentation and control van, and a 1000-kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Additional testing was performed in Mexico in 1980 under a cooperative test program using the same test array, and machine efficiency was measured at 62% maximum with the rotors partially coated with scale, compared with approximately 54% maximum in Utah with uncoated rotors, confirming the importance of scale deposits within the machine on performance. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

McKay, R.

1982-03-01

290

Formation of tough interlocking microstructures in silicon nitride ceramics by dynamic ripening  

Microsoft Academic Search

Ceramics based on Si3N4 have been comprehensively studied and are widely used in structural applications. The development of an interlocking microstructure of elongated grains is vital to ensure that this family of ceramics have good damage tolerance. Until now this has been accomplished by heating the appropriate powder compacts to temperatures above 1,700°C for extended periods. This procedure involves a

Zhijian Shen; Zhe Zhao; Hong Peng; Mats Nygren

2002-01-01

291

Development of an interlocked nail for segmental defects in the rabbit tibia.  

PubMed

Previous animal models have been developed to study intramedullary nailing for challenging segmental defects in the tibia. In large animals, interlocked nail fixation created a stable environment suitable to study new bone growth technologies placed in the defect. To our knowledge, there are no comparable interlocked tibial defect models for the rabbit in which new technologies could be evaluated. Such a model would be helpful since the rabbit is a popular initial model for orthopedic research studies owing to its wide availability and low cost. While numerous studies have nailed the rabbit tibia, all were non-locked implants that allowed some degree of instability between the fracture fragments. In addition, the non-locked nails were constructed of stainless steel, whereas human nails are increasingly made from titanium alloy. In the current study, an interlocked titanium nail was developed for the rabbit tibia. It was implanted in cadaver tibiae and subjected to fatigue cycling in combined compression and bending at physiologic levels to 21,061 cycles. This duration is estimated to represent 12 weeks of gait by the animal. Before and after fatigue cycling, monotonic testing was performed in compression and bending at physiologic levels. The intact contralateral limbs served as controls. All limbs completed the cycling; the instrumented limbs exhibited interfragmentary cyclic strain amplitudes during fatigue (616 +/- 139 micro-strain), which was significantly greater than the control limbs (136 +/- 35 microstrain). Monotonic strain amplitudes for the test limbs in bending and compression were 4839 +/- 1028 and 542 +/- 122 microstrain, respectively; corresponding values for the control bones were 407 +/- 118 and 95 +/- 38 microstrain, respectively. These data are similar to those presented in prior studies in larger bone models. The current study presents one method for interlocked nail fixation for this complex tibial shaft fracture in a small animal. PMID:22611873

LeCronier, David J; Papakonstantinou, John S; Gheevarughese, Vineetha; Beran, Casey D; Walter, Norman E; Atkinson, Patrick J

2012-04-01

292

Influence of accessory substances, wood density and interlocked grain on the compressive properties of hardwoods  

Microsoft Academic Search

Wood samples of nine tropical hardwoods from Peru and sugar maple wood from Quebec were selected to perform moisture sorption\\u000a tests associated with parallel-to-grain and tangential compression tests using a multiple step procedure at 25°C. Cold-water\\u000a and hot-water extractives, sequential cyclohexane (CYC), acetone (ACE) and methanol (MET) extracts, ash content (ASH), wood\\u000a density and interlocked grain (IG) were evaluated on

Roger E. Hernández

2007-01-01

293

Finite element simulation of three?dimensional angle?interlock woven fabric undergoing ballistic impact  

Microsoft Academic Search

This paper presents finite element simulations of three?dimensional (3D) angle?interlock woven fabric (3DAWF) undergoing ballistic impact. A micro?structure model of the 3DAWF was established at the fiber tow level. Incorporated with commercial finite element code, ABAQUS\\/Explicit, the ballistic impact damage of the 3DAWF was simulated and compared with that in the experiment. Residual velocities of the conically cylindrical steel projectile

Limin Jin; Baozhong Sun; Bohong Gu

2011-01-01

294

Extended torsional tests of an interlocked bi-stem satellite boom  

NASA Technical Reports Server (NTRS)

The effect is reported of continued oscillations of a 1.27-cm interlocked bi-stem satellite boom. The test setup oscillated a boom continuously between set torque limits and periodically recorded its hysteresis characteristics. Results showed that repeated oscillations affected torsional characteristics and that torsional rigidity changed as a function of the number of cycles oscillated within certain torque limits. Torsional characteristics changes caused by repeated oscillations were retained.

Abercrombie, R. A.

1973-01-01

295

The Structural Engineer 88 (1) 5 January 2010 25 This paper presents a model for the strength of inclined screws  

E-print Network

, in tension or shear, and four modes which combine bending of the screw and timber. The four combined modes displacement of screw tip. Angle of inclination of the screw axis with the vertical. ax Axial displacement of screw. f h W tT RXRX lat Lateral displacement of screw at the material interface. Ratio of withdrawal

Crilly, Nathan

296

Long-term stability of angle-stable versus conventional locked intramedullary nails in distal tibia fractures  

PubMed Central

Background In the last years intramedullary nailing has become the treatment of choice for most displaced diaphyseal tibia fractures. In contrast intramedullary nailing of distal tibia fractures is accompanied by problems like decreased biomechanical stability. Nevertheless the indications for intramedullary nailing have been extended to include even more distal fractures. The purpose of this study was to compare long-term mechanical characteristics of angle-stable versus conventional locked intramedullary nails in the treatment of unstable distal tibia fractures. Therefore, the effect of time on the mechanical properties of biodegradable sleeves was assessed. Methods 8 pairs of fresh, frozen porcine tibiae were used. The expert tibial nail (Synthes) was equipped with either three conventional locking screws (CL) or the angle-stable locking system (AS), consisting of a special ASLS screw and a biodegradable sleeve. Biomechanical testing included torsional and axial loading at different time-points over 12 weeks. Results The AS group showed a significantly higher torsional stiffness at all time-points (at least 60%) compared to the CL group (p??0.05). For axial stiffness and range of motion significant differences were found in the AS group. Conclusions The angle-stable locking system (ASLS) with the biodegradable sleeve provides significantly higher long-term stability. Especially the differences determined under torsional loading in this study may have clinical relevance. The ASLS permits the potential to decrease complications like secondary loss of reduction and mal-/non-union. PMID:23425016

2013-01-01

297

Is a Magnetic-Manual Targeting Device an Appealing Alternative for Distal Locking of Tibial Intramedullary Nails?  

PubMed Central

Background In order to enable a radiation-free, accurate and simple positioning of distal locking screws, a combined magnetic and manual targeting system has been developed by Sanatmetal®. Where a low-frequency magnetic field is initially used to detect the position of the first drill hole and three more holes can be found with a mechanical template. Objectives Our cadaver study was performed to evaluate the accuracy and efficiency of this device. Materials and Methods In two runs, 30 probands (group 1: 10 students; group 2: 10 residents; group 3: 10 attendings), none of who being familiar with the device, tested the radiation-free system using 60 intact cadaver tibias. Each proband performed the surgical procedure twice in succession. Results Referring to the first attempts, 9.6, 7.2 and 7.1 minutes were the time periods required to insert the four distal screws and the relevant values for the second attempts were 8.6, 6.3 and 6.2 minutes; in both cases revealing a significant difference between group 1 and 2 and group 1 and 3. Furthermore, the mean values within each group indicated a significant decrease of the test duration. Out of the 240 drillings, only one failure (group 1) occurred, representing an accuracy of 99.58 %. Of the probands, 90 % rated the targeting device better than the free-hand technique and 77 % at least attested a high user-friendliness. Conclusions Due to our satisfactory test results, the brief training, the steep learning curve and the radiation-free technique the new device has to be considered an appealing alternative for distal locking. PMID:24396784

Negrin, Lukas L.; Vécsei, Vilmos

2013-01-01

298

In Vivo Loss of Cement-Bone Interlock Reduces Fixation Strength in Total Knee Arthroplasties  

PubMed Central

Prevention of aseptic loosening of total knee arthroplasties (TKAs) remains an important clinical challenge. Understanding how changes in morphology at the implant-bone interface with in vivo service affects implant stability and strength could lead to new approaches to mitigate loosening. Enbloc TKA retrievals and freshly-cemented TKA tibial components were used to determine if the mechanical strength of the interface depended on the amount of cement-bone interlock and the morphology of the supporting bone under the cement layer. Implants were sectioned into small specimens of the cement-interface-bone from under the tibial tray. Micro-CT scans were used to document interlock morphology and architecture of the supporting trabecular bone. Axial compression tests were used to assess mechanical behavior. Postmortem retrievals had lower contact fraction (42±55%) compared to freshly-cemented constructs (121±61%) (p=0.0008). Supporting bone architecture parameters were not different for the two groups. Increased interface contact fraction and supporting bone volume fraction (BV/TV) were positive predictors of interface strength (r2=0.72, p=0.0001). For the same supporting bone BV/TV, postmortem specimens had weaker interfaces; they were also more compliant. Cemented TKA with in vivo service experience a loss of fixation strength and increased micro-motion due to the loss of cement-bone interlock. PMID:24777486

Goodheart, Jacklyn R.; Miller, Mark A.; Mann, Kenneth A.

2014-01-01

299

Modelling the evolution of a bi-partite network Peer referral in interlocking directorates*  

PubMed Central

A central part of relational ties between social actors are constituted by shared affiliations and events. The action of joint participation reinforces personal ties between social actors as well as mutually shared values and norms that in turn perpetuate the patterns of social action that define groups. Therefore the study of bipartite networks is central to social science. Furthermore, the dynamics of these processes suggests that bipartite networks should not be considered static structures but rather be studied over time. In order to model the evolution of bipartite networks empirically we introduce a class of models and a Bayesian inference scheme that extends previous stochastic actor-oriented models for unimodal graphs. Contemporary research on interlocking directorates provides an area of research in which it seems reasonable to apply the model. Specifically, we address the question of how tie formation, i.e. director recruitment, contributes to the structural properties of the interlocking directorate network. For boards of directors on the Stockholm stock exchange we propose that a prolific mechanism in tie formation is that of peer referral. The results indicate that such a mechanism is present, generating multiple interlocks between boards. PMID:24944435

Edling, Christofer

2010-01-01

300

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

301

Distal oblique osteotomy of the first metatarsal for the correction of hallux limitus and rigidus deformity.  

PubMed

The purpose of this study was to evaluate the effectiveness of the distal oblique osteotomy of the first metatarsal (a triplanar shortening decompression osteotomy) to correct stage I and II hallux rigidus. The osteotomy cut is performed from dorsal-distal to plantar-proximal with an angle ranging from 35 degrees to 45 degrees in the sagittal plane. The capital fragment is then displaced plantarly and proximally and fixed with two screws and the metatarsal head is remodeled. From January 1993 through December 1995, a total of 26 patients (21 females and 5 males) underwent 30 distal oblique osteotomies of the first metatarsal (22 unilateral and 4 bilateral). The mean age of the patients was 54 years and the mean follow-up was 21 months. Patient satisfaction and objective clinical and radiographic measurements were evaluated. Patients' satisfaction was measured postoperatively with a modification of the University of Maryland 100-Point Painful Foot Center Scoring System. The results were: 84% good to excellent; 7% fair; and 9% poor. Radiographic measurements included: intermetatarsal angle mean: preop = 12.2 degrees, postop = 8.6 degrees; proximal articular set angle mean: preop = 11.8 degrees; postop = 10.3 degrees. There was no evidence of avascular necrosis in any of the cases. Clinical findings were: dorsiflexion of the first metatarsophalangeal joint: preop = 22 degrees, postop = 45 degrees; plantarflexion of the first metatarsophalangeal joint: preop = 15 degrees, postop = 18 degrees; hallux purchase power: preop = 2.5, postop = 2.3; pain on the second and third metatarsophalangeal joints, associated with excessive pressure on the central metatarsal heads: preop--present in 10 patients, postop--present in 12 patients; forefoot supination angle: preop = 13 degrees, postop = 7 degrees. PMID:10862386

Ronconi, P; Monachino, P; Baleanu, P M; Favilli, G

2000-01-01

302

Controlled dynamic stability as the next step in “biologic plate osteosynthesis” - a pilot prospective observational cohort study in 34 patients with distal tibia fractures  

PubMed Central

Introduction Delayed bone healing is an eminent problem in the operative treatment of distal tibia fractures. To address this problem from a biomechanical perspective, the DLS 3.7 (Dynamic Locking Screw 3.7 mm) as a new generation of locking screws has been developed. This screw enables the surgeon to control the rigidity of the plate osteosynthesis and thereby to expand clinical options in cases where the bridge plating is chosen for fracture treatment. Purpose The purpose of the present prospective study was to evaluate the safety use of the DLS 3.7 in distal tibia fractures where bridge plating osteosynthesis is recommended. Methods In a prospective non-controlled cohort study, 34 patients with acute distal tibia fractures (AO 43 A-C) were treated with an angular stable plate fixation using DLS 3.7 or LHS 3.5. Follow-up examinations were performed three, six, twelve, and twenty-four weeks postoperatively and all registered complications were carefully collected. Results A total of 34 patients were prospectively enrolled in this study with a minimum follow-up of 6 months or obvious osseous consolidation at an earlier stage. No complications directly related to the DLS 3.7 were recorded and no infections were observed. Conclusions This observational study could show that the DLS 3.7 in combination with locking compression plates provides a secure and easy application. According to the recent literature inter-fragmentary micro-motion is one evident goal to increase the reliability in fracture healing. The new DLS 3.7 with a maximum micro-motion of 0.2 mm combines the advantage of micro-motion with the well-known advantages of angular stable plate fixation. PMID:24447901

2014-01-01

303

Comparative study on stress distribution around internal tapered connection implants according to fit of cement- and screw-retained prostheses  

PubMed Central

PURPOSE The aim of this study was to compare the passivity of implant superstructures by assessing the strain development around the internal tapered connection implants with strain gauges. MATERIALS AND METHODS A polyurethane resin block in which two implants were embedded served as a measurement model. Two groups of implant restorations utilized cement-retained design and internal surface of the first group was adjusted until premature contact between the restoration and the abutment completely disappeared. In the second group, only nodules detectable to the naked eye were removed. The third group employed screw-retained design and specimens were generated by computer-aided design/computer-aided manufacturing system (n=10). Four strain gauges were fixed on the measurement model mesially and distally to the implants. The strains developed in each strain gauge were recorded during fixation of specimens. To compare the difference among groups, repeated measures 2-factor analysis was performed at a level of significance of ?=.05. RESULTS The absolute strain values were measured to analyze the magnitude of strain. The mean absolute strain value ranged from 29.53 to 412.94 µm/m at the different strain gauge locations. According to the result of overall comparison, the cement-retained prosthesis groups exhibited significant difference. No significant difference was detected between milled screw-retained prostheses group and cement-retained prosthesis groups. CONCLUSION Within the limitations of the study, it was concluded that the cement-retained designs do not always exhibit lower levels of stress than screw-retained designs. The internal adjustment of a cement-retained implant restoration is essential to achieve passive fit. PMID:24049573

Lee, Mi-Young; Heo, Seong-Joo; Park, Eun-Jin

2013-01-01

304

Endovascular aortic injury repair after thoracic pedicle screw placement.  

PubMed

Our objective was to describe the management and prevention of thoracic aortic injuries caused by a malposition of pedicle screws in corrective surgery of major spine deformities. Positioning pedicle screws in thoracic vertebras by posterior approach exposes to the risk of injury of the elements placed ahead of the thoracic spine, as the descending thoracic aorta. This complication can result in a cataclysmic bleeding, needing urgent vascular care, but it can also be totally asymptomatic, resulting in the long run in a pseudoaneurysm, justifying the systematic removal of the hardware. We report the case of a 76-year-old woman who underwent spinal correction surgery for thoraco-lumbar degenerative kypho-scoliosis. Immediately after the surgery, a thoracic aortic injury caused by the left T7 pedicle screw was diagnosed. The patient underwent a two-step surgery. The first step was realized by vascular surgeons and aimed to secure the aortic wall by short endovascular aortic grafting. During the second step, spine surgeons removed the responsible screw by posterior approach. The patient was discharged in a rehabilitation center 7 days after the second surgery. When such a complication occurs, a co-management by vascular and spine surgeons is necessary to avoid major complications. Endovascular management of this kind of vascular injuries permits to avoid an open surgery that have a great rate of morbi-mortality in frail patients. Nowadays, technologies exist to prevent this kind of event and may improve the security when positioning pedicle screws. PMID:25023930

Pesenti, S; Bartoli, M A; Blondel, B; Peltier, E; Adetchessi, T; Fuentes, S

2014-09-01

305

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. PMID:24829871

Hedequist, Daniel J

2014-01-01

306

Screw dislocations in GaN grown by different methods  

SciTech Connect

A study of screw dislocations in Hydride-Vapor-Phase-Epitaxy (HVPE) template and Molecular-Beam-Epitaxy (MBE) over-layers was performed using Transmission Electron Microscopy (TEM) in plan-view and in cross-section. It was observed that screw dislocations in the HVPE layers were decorated by small voids arranged along the screw axis. However, no voids were observed along screw dislocations in MBE overlayers. This was true both for MBE samples grown under Ga-lean and Ga-rich conditions. Dislocation core structures have been studied in these samples in the plan-view configuration. These experiments were supported by image simulation using the most recent models. A direct reconstruction of the phase and amplitude of the scattered electron wave from a focal series of high-resolution images was applied. It was shown that the core structures of screw dislocations in the studied materials were filled. The filed dislocation cores in an MBE samples were stoichiometric. However, in HVPE materials, single atomic columns show substantial differences in intensities and might indicate the possibility of higher Ga concentration in the core than in the matrix. A much lower intensity of the atomic column at the tip of the void was observed. This might suggest presence of lighter elements, such as oxygen, responsible for their formation.

Liliental-Weber, Z.; Zakharov, D.; Jasinski, J.; O'Keefe, M.A.; Morkoc, H.

2003-05-27

307

Ball screw preload loss detection using ball pass frequency  

NASA Astrophysics Data System (ADS)

A technique of determining the onset of preload loss in a ball screw feed drive system via monitoring the change of ball pass frequency is proposed. The ball pass frequency of a ball screw with preload is smaller than that of ball screw without preload due to friction caused by the preload. Results from both simulations and experiments show that the ball pass frequency can be detected using the method of Angular Velocity Vold-Kalman Filtering Order Tracking (AV VKF-OT). And AV VKF-OT provides a much better performance as compared to the traditional order tracking in terms of resolution and accuracy. Tests were conducted on ball screw feed drive systems with different preloads for the performance assessment of the ball pass frequency detection. Results show that the preload loss increases the ball pass frequency and also induces the side band around the ball pass frequency, which provides promising criteria in detecting the onset of preload loss of ball screws.

Tsai, P. C.; Cheng, C. C.; Hwang, Y. C.

2014-10-01

308

Transsacral screw safe zone size by sacral segmentation variations.  

PubMed

Variations in sacral segmentation may preclude safe placement of transsacral screws for posterior pelvis fixation. We developed a novel automated 3D technique to determine the safe zone size for transsacral screws in the upper two sacral segments in 526 adult pelvis computed tomography scans. Safe zone sizes were then compared by gender and sacral segmentation variations (number of neuroforamen and the presence/absence of lumbosacral transitional vertebrae, ±LSTV). Ten millimeters was used as the safety threshold for a large screw. 3 (0.6%), 366 (70%), and 157 (30%) sacra had 3, 4, or 5 neuroforamen, respectively. Eighty-eight (17%) were +LSTV. Safe zone size depended on gender, number of neuroforamen in -LSTV sacra and presence of LSTV (p?screw safely, 77% can do so in S2, leaving only 4% of sacra that cannot accommodate a screw safely in either upper segment. The results demonstrate a predictable pattern of safe zone size based on gender and sacral segmentation variations. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:277-282, 2015. PMID:25231682

Lee, John J; Rosenbaum, Samuel L; Martusiewicz, Alex; Holcombe, Sven A; Wang, Stewart C; Goulet, James A

2015-02-01

309

2D-fluoroscopic navigated percutaneous screw fixation of pelvic ring injuries - a case series  

PubMed Central

Background Screw fixation of pelvic ring fractures is a common, but demanding procedure and navigation techniques were introduced to increase the precision of screw placement. The purpose of this case series was the evaluation of screw misplacement rate and functional outcome of percutaneous screw fixation of pelvic ring disruptions using a 2D navigation system. Methods Between August 2004 and December 2007, 44 of 442 patients with pelvic injuries were included for closed reduction and percutaneous screw fixation of disrupted pelvic ring lesions using an optoelectronic 2D-fluoroscopic based navigation system. Operating and fluoroscopy time were measured, as well as peri- and postoperative complications documented. Screw position was assessed by postoperative CT scans. Quality of live was evaluated by SF 36-questionnaire in 40 of 44 patients at mean follow up 15.5 ± 1.2 month. Results 56 iliosacral- and 29 ramus pubic-screws were inserted (mean operation time per screw 62 ± 4 minutes, mean fluoroscopy time per screw 123 ± 12 seconds). In post-operative CT-scans the screw position was assessed and graded as follows: I. secure positioning, completely in the cancellous bone (80%); II. secure positioning, but contacting cortical bone structures (14%); III. malplaced positioning, penetrating the cortical bone (6%). The malplacements predominantly occurred in bilateral overlapping screw fixation. No wound infection or iatrogenic neurovascular damage were observed. Four re-operations were performed, two of them due to implant-misplacement and two of them due to implant-failure. Conclusion 2D-fluoroscopic navigation is a safe tool providing high accuracy of percutaneous screw placement for pelvic ring fractures, but in cases of a bilateral iliosacral screw fixation an increased risk for screw misplacement was observed. If additional ramus pubic screw fixations are performed, the retrograde inserted screws have to pass the iliopubic eminence to prevent an axial screw loosening. PMID:20609243

2010-01-01

310

Treatment of partial distal biceps tendon tears.  

PubMed

Partial rupture of the distal biceps tendon exhibits features similar to that of complete disruption, including acute antecubital pain, weakness of elbow flexion, and forearm supination, and differs only in the fact that the biceps tendon is still palpable in the partial rupture. There are 2 etiologies, first acute traumatic (such as a sudden eccentric contracture) and second, chronic degenerative tendon disease. For accurate diagnosis, a high index of suspicion must be employed. Initial investigations should include plain x-ray and a magnetic resonance scan. Partial tears <50% may be treated with nonoperative management or with surgical debridement of the surrounding synovitis. Tears >50% should be treated with division of the remaining tendon and surgical repair of the entire tendon as a single unit. Surgical endoscopy provides the ability to further quantify the extent of a distal biceps tear and to treat with debridement. This technique, however, should only be used in experienced hands. PMID:18703975

Bain, Gregory I; Johnson, Luke J; Turner, Perry C

2008-09-01

311

The Epidemiology of Distal Radius Fractures  

PubMed Central

Distal radius fractures are one of the most common types of fractures, accounting for around 25% of fractures in the pediatric population and up to 18% of all fractures in the elderly age group. Although the pediatric and elderly populations are at the greatest risk for this injury, distal radius fractures still have a significant impact on the health and well-being of young adults. Data from the past 40 years has documented a trend towards an overall increase in the prevalence of this injury. For the pediatric population, this increase can likely be attributed to a surge in sports related activities. The growth of the elderly population and a rise in the number of active elderly are directly responsible for the increase seen in this age group. Understanding the epidemiology of this fracture is an important step towards the improvement of the treatment strategies and preventative measures which target this debilitating injury. PMID:22554654

Nellans, Kate W.; Kowalski, Evan; Chung, Kevin C.

2012-01-01

312

Peristalsis in the rabbit distal colon  

PubMed Central

1. The motility of the distal colon of the rabbit has been examined by the conventional Trendelenburg method and by an isometric, isovolumic modification of this method. 2. The colon shows a range of movements, and tetrodotoxin and cold-storage have been used in an attempt to differentiate between myogenic and neurally integrated activities. 3. The observable myogenic movements are pendulum movements, `tone rings' and `tone waves'; the last of these can be weakly propulsive. The rabbit colon also shows a neurally organized and powerfully propulsive movement which corresponds to the peristaltic wave. 4. The implication of a role for nervous structures in the propulsive activity of the rabbit distal colon is at variance with the view of Lee (1960). 5. The myenteric reflex arc in the colon has been examined pharmacologically. Cholinergic neural transmission has been implicated at the ganglionic-synaptic and neuroeffector junctions, but additional noncholinergic mechanisms of chemical transmission have not been excluded. PMID:4400587

Mackenna, B. R.; McKirdy, H. C.

1972-01-01

313

Periosteal osteoid osteoma of the distal femur  

PubMed Central

Periosteal osteoid osteoma is extremely rare. The diagnosis is not always clear. We report a case of periosteal osteoid osteoma arising from the posterior surface of the right distal femur in a 21-year-old woman. After careful evaluation and excisional biopsy, histological examination confirmed the diagnosis of osteoid osteoma, showing the nidus, surrounding osteosclerosis, and catarrhal synovitis. The lesion was treated successfully with excision of the nidus. PMID:21808706

Amar, Mohammed Fahd; Almoubaker, Salma; Chbani, Badr; Chahbouni, Sanae; Marzouki, Amine; Amarti, Afaf; Boutayeb, Fawzi

2010-01-01

314

Fractures of Distal Radius: An Overview  

PubMed Central

Fractures of distal radius account for up to 20% of all fractures treated in emergency department. Initial assessment includes a history of mechanism of injury, associated injury and appropriate radiological evaluation. Treatment options include conservative management, internal fixation with pins, bridging and non-bridging external fixation, dorsal or volar plating with/without arthroscopy assistance. However, many questions regarding these fractures remain unanswered and good prospective randomized trials are needed.

Meena, Sanjay; Sharma, Pankaj; Sambharia, Abhishek Kumar; Dawar, Ashok

2014-01-01

315

Distal Embolic Protection for Renal Arterial Interventions  

SciTech Connect

Distal or embolic protection has intuitive appeal for its potential to prevent embolization of materials generated during interventional procedures. Distal protection devices (DPDs) have been most widely used in the coronary and carotid vascular beds, where they have demonstrated the ability to trap embolic materials and, in some cases, to reduce complications. Given the frequency of chronic kidney disease in patients with renal artery stenosis undergoing stent placement, it is reasonable to propose that these devices may play an important role in limiting distal embolization in the renal vasculature. Careful review of the literature reveals that atheroembolization does occur during renal arterial interventions, although it often goes undetected. Early experience with DPDs in the renal arteries in patients with suitable anatomy suggests retrieval of embolic materials in approximately 71% of cases and renal functional improvement/stabilization in 98% of cases. The combination of platelet inhibition and a DPD may provide even greater benefit. Given the critical importance of renal functional preservation, it follows that everything that can be done to prevent atheroembolism should be undertaken including the use of DPDs when anatomically feasible. The data available at this time support a beneficial role for these devices.

Dubel, Gregory J., E-mail: gdubel@lifespan.org; Murphy, Timothy P. [Brown University Medical School, Department of Diagnostic Imaging, Division of Interventional Radiology (United States)

2008-01-15

316

Forearm and distal radius fractures in children.  

PubMed

Pediatric forearm and distal radius fractures are common injuries. Resultant deformities are usually a product of indirect trauma involving angular loading combined with rotational displacement. Fractures are classified by location, completeness, angular and rotational deformity, and fragment displacement. Successful outcomes are based on restoration of adequate pronation and supination and, to a lesser degree, acceptable cosmesis. When several important concepts are kept in mind, these goals are usually met with conservative treatment by reduction and immobilization. Greenstick fractures are reduced by rotating the forearm such that the palm is directed toward the fracture apex. Complete fractures are manipulated and reduced with traction and rotation; extremities are then immobilized in well-molded plaster casts until healing, which usually takes about 6 weeks. Radiographs should be obtained between 1 and 2 weeks after initial reduction to detect early angulation. In fractures in any level in children less than 9 years of age, complete displacement, 15 degrees of angulation, and 45 degrees of malrotation are acceptable. In children 9 years of age or older, 30 degrees of malrotation is acceptable, with 10 degrees of angulation for proximal fractures and 15 degrees for more distal fractures. Complete bayonet apposition is acceptable, especially for distal radius fractures, as long as angulation does not exceed 20 degrees and 2 years of growth remains. Operative intervention is used when the fracture is open and when acceptable alignment cannot be achieved or maintained. Single-bone intramedullary fixation has proven useful. PMID:9689186

Noonan, K J; Price, C T

1998-01-01

317

Magnetic field rotation in the screw gallium flow  

NASA Astrophysics Data System (ADS)

The magnetic field induced by the nonstationary screw flow of gallium in a toroidal channel has been investigated experimentally using a gallium prototype of the sodium apparatus developed in the frame of the experimental dynamo program at the Institute of Continuous Media Mechanics, Perm, Russia. The experimental set-up is a rapidly rotating toroidal channel subjected to abrupt braking. The screw flow is initiated by inertial forces pushing liquid gallium through diverters. The regular structure of the induced magnetic field is generated about 0.1 s after the stop of the channel and persists up to 1 s. The induced field is measured by sensors placed outside the channel. The inductive effects observed are attributed to the mean screw flow. The decay laws of the induced regular magnetic field and turbulent magnetic fluctuations are studied.

Noskov, V.; Denisov, S.; Frick, P.; Khripchenko, S.; Sokoloff, D.; Stepanov, R.

2004-10-01

318

Mechanical Properties of Nanotextured Titanium Orthopedic Screws for Clinical Applications.  

PubMed

In this work, we modified the topography of commercial titanium orthopedic screws using electrochemical anodization in a 0.4?wt% hydrofluoric acid solution to produce titanium dioxide nanotube layers. The morphology of the nanotube layers were characterized using scanning electron microscopy. The mechanical properties of the nanotube layers were investigated by screwing and unscrewing an anodized screw into several different types of human bone while the torsional force applied to the screwdriver was measured using a torque screwdriver. The range of torsional force applied to the screwdriver was between 5 and [Formula: see text]. Independent assessment of the mechanical properties of the same surfaces was performed on simple anodized titanium foils using a triboindenter. Results showed that the fabricated nanotube layers can resist mechanical stresses close to those found in clinical situations. PMID:23904907

Descamps, Stephane; Awitor, Komla O; Raspal, Vincent; Johnson, Matthew B; Bokalawela, Roshan S P; Larson, Preston R; Doiron, Curtis F

2013-06-01

319

Efficiency study of oil cooling of a screw compressor  

SciTech Connect

One of the major goals of all compressor manufacturers is to build as efficient a compressor as possible. Over the last several years improvements to the design of screw compressors has made them efficiently competitive with other types of compressors, especially at large loads. The primary purpose of this research is to investigate four different methods of cooling a 250 horsepower compressor and determine their effects on the efficiency of the compressor. Two conventional methods, liquid injection and thermosyphon cooling, and two new methods, V-PLUS and Fresco oil injection, are investigated. The screw compressor used in the tests was a VRS-500 screw compressor made by the Vilter Manufacturing Corporation. 6 figs.

Tree, D.R.; McKellar, M.G.

1989-04-01

320

Mild coal gasification screw pyrolyzer development and design  

SciTech Connect

Our objective is to produce information and design recommendations needed for the development of an efficient continuous process for the mild gasification of caking bituminous coals. We have focused on the development of an externally heated pyrolyzer in which the sticky, reacting coal is conveyed by one or more screws. We have taken a multifaceted approach to forwarding the development of the externally-heated screw pyrolyzer. Small scale process experiments on a 38-mm single screw pyrolyzer have been a major part of our effort. Engineering analyses aimed at producing design and scaleup equations have also been important. Process design recommendations follow from these. We critically review our experimental data and experience, and information from the literature and equipment manufactures for the purpose of making qualitative recommendations for improving practical pyrolyzer design and operation. Benchscale experiments are used to supply needed data and test some preliminary concepts. 6 refs., 4 figs., 1 tab.

Camp, D.W.

1990-08-01

321

Hamstring anterior cruciate ligament reconstruction: a comparison of bioabsorbable interference screw and endobutton-post fixation  

Microsoft Academic Search

PurposeThe purpose of this study was to evaluate hamstring anterior cruciate ligament (ACL) reconstruction using aperture fixation with bioabsorbable interference screw (BIS) and distant fixation using EndoButton (Smith & Nephew, Andover, MA) and screw-post (ENDO).

C. Benjamin Ma; Kimberly Francis; Jeffrey Towers; Jay Irrgang; Freddie H Fu; Christopher H Harner

2004-01-01

322

Efficiency and Leakage Analysis of a Twin-Screw Multiphase Pump  

E-print Network

Multiphase twin-screw pumps have become an important alternative to produce the oil and natural gas from wells. In comparison to a conventional multiphase oil production systems, a multiphase twin screw pump provides larger boost with smaller...

Turhan, Yusuf

2014-04-01

323

Tightening force and torque of nonlocking screws in a reverse shoulder prosthesis A. Terrier a,  

E-print Network

of bone volume around each screw was measured with a micro-CT. Measurements were performed on 6 human of the screw position has been recently investigated using micro-CT reconstructions of cadaveric scapulas

Guerraoui, Rachid

324

29 CFR 1926.305 - Jacks-lever and ratchet, screw, and hydraulic.  

Code of Federal Regulations, 2010 CFR

...Jacks-lever and ratchet, screw, and hydraulic. 1926.305 Section 1926.305...Jacks—lever and ratchet, screw, and hydraulic. (a) General requirements. ...otherwise secured at once. (ii) Hydraulic jacks exposed to freezing...

2010-07-01

325

Comparison of the differences in cephalometric parameters after active orthodontic treatment applying mini-screw implants or transpalatal arches in adult patients with bialveolar dental protrusion.  

PubMed

The purpose of this study was to compare the differences in cephalometric parameters after active orthodontic treatment applying mini-screw implants (G1) or transpalatal arches (G2) as anchorage in adult patients with bialveolar dental protrusion needing extraction of four premolars. A total of 34 Chinese patients (18-33 years) with bialveolar dental protrusion were randomly assigned to G1 and G2. Sliding mechanics and en-masse retraction of anterior teeth were applied to close extraction spaces. The changes in skeletal, dental and soft tissues were analyzed in both groups on lateral cephalograms before and after active orthodontic treatment. Independent samples and paired-samples t-tests were utilized to analyze the morphological changes in both groups. ANB angle was decreased in G1 and remained unchanged in G2 (P < 0.05). Upper incisors were retracted more in G1 than in G2 (P < 0.01). Upper incisors and molars were intruded in G1, but extruded in G2 (P < 0.01). Although the upper molars were found with no significant distalization (P > 0.05), there existed molars distalization in some patients. However, the maxillary molars in G2 were mesialized (P < 0.01). The intrusion of upper molars in G1 resulted in counterclockwise rotation of the mandible and decrease of SN-MP angle (P < 0.01). Upper lip linear measurements including UL-Y and UL-E were decreased more in G1 than in G2 (P < 0.05). Mini-screw implants provide absolute anchorage in vertical and sagittal directions. Better dental, skeletal and soft tissue changes could be achieved by mini-screw implants especially in hyperdivergent patients. Skeletal anchorage should be routinely recommended in patients with bialveolar dental protrusion. PMID:19602104

Liu, Y H; Ding, W H; Liu, J; Li, Q

2009-09-01

326

Torsional stability of interference screws derived from bovine bone - a biomechanical study  

PubMed Central

Background In the present biomechanical study, the torsional stability of different interference screws, made of bovine bone, was tested. Interference screws derived from bovine bone are a possible biological alternative to conventional metallic or bioabsorbable polymer interference screws. Methods In the first part of the study we compared the torsional stability of self-made 8 mm Interference screws (BC) and a commercial 8 mm interference screw (Tutofix®). Furthermore, we compared the torsional strength of BC screws with different diameters. For screwing in, a hexagon head and an octagon head were tested. Maximum breaking torques in polymethyl methacrylate resin were recorded by means of an electronic torque screw driver. In the second part of the study the tibial part of a bone-patellar tendon-bone graft was fixed in porcine test specimens using an 8 mm BC screw and the maximum insertion torques were recorded. Each interference screw type was tested 5 times. Results There was no statistically significant difference between the different 8 mm interference screws (p = 0.121). Pairwise comparisons did not reveal statistically significant differences, either. It was demonstrated for the BC screws, that a larger screw diameter significantly leads to higher torsional stability (p = 9.779 × 10-5). Pairwise comparisons showed a significantly lower torsional stability for the 7 mm BC screw than for the 8 mm BC screw (p = 0.0079) and the 9 mm BC screw (p = 0.0079). Statistically significant differences between the 8 mm and the 9 mm BC screw could not be found (p = 0.15). During screwing into the tibial graft channel of the porcine specimens, insertion torques between 0.5 Nm and 3.2 Nm were recorded. In one case the hexagon head of a BC screw broke off during the last turn. Conclusions The BC screws show comparable torsional stability to Tutofix® interference screws. As expected the torsional strength of the screws increases significantly with the diameter. The safety and in vivo performance of products derived from xenogeneic bone should be the focus of further investigations. PMID:20433761

2010-01-01

327

Biomedical Paper Computer-Based Periaxial Rotation Measurement for  

E-print Network

and distal interlocking screws are inserted to prevent fragment rotation and bone shortening. The procedure on periaxial rotation. The periaxial rotation is defined in terms of patient-specific bone features developed. The algorithm extracts the condyle landmarks and neck axis of the healthy bone, determines its

Joskowicz, Leo

328

Distal hereditary motor neuropathy type II (distal HMN II): mapping of a locus to chromosome 12q24  

Microsoft Academic Search

The distal hereditary motor neuropathy (distal HMN) or the spinal form of Charcot-Marie-Tooth (CMT) disease is an exclusively motor disorder of the peripheral nerv- ous system. The disorder clinically resembles the her- editary motor and sensory neuropathies (HMSN) type I and type II or CMT type 1 and type 2. Distal HMN might also be related to the spinal muscular

Vincent Timmerman; Peter De Jonghe; Sandra Simokovic; Ann Löfgren; Joke Beuten; Eva Nelis; Chantal Ceuterick; Jean-Jacques Martin; Christine Van Broeckhoven

1996-01-01

329

[The biomechanics of screws, cerclage wire and cerclage cable].  

PubMed

In contrast to fracture fixation, when performing an osteotomy the surgeon is able to plan preoperatively. The resulting fixation and compression of the bone fragments are the most important points. A stable osteosynthesis should prevent dislocation of bone fragments and improve bone healing. Beside plates, cerclages can be used for tension band or diaphysis bone fixation. Moreover, cortical or cancellous screws can be used for osteotomy fixation. This work describes biomechanical principles for fixation after an osteotomy with cerclages and cortical or cancellous screws. It also summarizes the materials and geometries used, as well as their influence on the stability of the osteosynthesis. PMID:23615626

Schröder, C; Woiczinski, M; Utzschneider, S; Kraxenberger, M; Weber, P; Jansson, V

2013-05-01

330

Ballasted, screw-in lamps seen cutting costs in retrofits  

SciTech Connect

Affordable screw-in fluorescent and high-pressure sodium fixtures with built-in ballasts are now an efficient and practical retrofit that can save users up to 75% on electricity costs. Payback can be less than one year despite the high cost of the fixtures compared to incandescents. Users will also realize ongoing maintenance savings because the service life is 10 to 20 times longer. The development of miniature ballasts and electronic ballasts with solid-state technology and transistors that can be confined to a small space make the screw-in lighting devices possible. A directory lists 83 major manufacturers of lighting equipment.

Ingraham, R.

1984-09-03

331

A screw-actuated pneumatic valve for portable, disposable microfluidics.  

PubMed

This work describes a simple and inexpensive approach for controlling the pneumatic valves that were invented in Quake's group to miniaturize the whole system for portable and disposable microfluidic devices. The valves are assembled from two parts. One is the polydimethylsiloxane (PDMS) channels formed by multilayer soft lithography. The other is a polymethylmethacrylate (PMMA) frame with machine screws for pressure control. Turning the screws into the control channel inlet (filled with water and covered with a thin PDMS membrane) actuates the valve by creating pressure in the control channel. This method avoids the bulky and expensive external pressure-control facilities and can be easily integrated into portable and disposable devices. PMID:19156298

Zheng, Yizhe; Dai, Wen; Wu, Hongkai

2009-02-01

332

Virtual estimates of fastening strength for pedicle screw implantation procedures  

NASA Astrophysics Data System (ADS)

Traditional 2D images provide limited use for accurate planning of spine interventions, mainly due to the complex 3D anatomy of the spine and close proximity of nerve bundles and vascular structures that must be avoided during the procedure. Our previously developed clinician-friendly platform for spine surgery planning takes advantage of 3D pre-operative images, to enable oblique reformatting and 3D rendering of individual or multiple vertebrae, interactive templating, and placement of virtual pedicle implants. Here we extend the capabilities of the planning platform and demonstrate how the virtual templating approach not only assists with the selection of the optimal implant size and trajectory, but can also be augmented to provide surrogate estimates of the fastening strength of the implanted pedicle screws based on implant dimension and bone mineral density of the displaced bone substrate. According to the failure theories, each screw withstands a maximum holding power that is directly proportional to the screw diameter (D), the length of the in-bone segm,ent of the screw (L), and the density (i.e., bone mineral density) of the pedicle body. In this application, voxel intensity is used as a surrogate measure of the bone mineral density (BMD) of the pedicle body segment displaced by the screw. We conducted an initial assessment of the developed platform using retrospective pre- and post-operative clinical 3D CT data from four patients who underwent spine surgery, consisting of a total of 26 pedicle screws implanted in the lumbar spine. The Fastening Strength of the planned implants was directly assessed by estimating the intensity - area product across the pedicle volume displaced by the virtually implanted screw. For post-operative assessment, each vertebra was registered to its homologous counterpart in the pre-operative image using an intensity-based rigid registration followed by manual adjustment. Following registration, the Fastening Strength was computed for each displaced bone segment. According to our preliminary clinical study, a comparison between Fastening Strength, displaced bone volume and mean voxel intensity showed similar results (p < 0.1) between the virtually templated plans and the post-operative outcome following the traditional clinical approach. This study has demonstrated the feasibility of the platform in providing estimates the pedicle screw fastening strength via virtual implantation, given the intrinsic vertebral geometry and bone mineral density, enabling the selection of the optimal implant dimension adn trajectory for improved strength.

Linte, Cristian A.; Camp, Jon J.; Augustine, Kurt E.; Huddleston, Paul M.; Robb, Richard A.; Holmes, David R.

2014-03-01

333

Bioabsorbable Interference Screws for Graft Fixation in Anterior Cruciate Ligament Reconstruction  

Microsoft Academic Search

Summary: The central one third of the patellar tendon autograft is popular because the bone-tendon-bone (BTB) construct provides several graft fixation options, robust graft incorporation, and a mechanically sufficient substitute. Interference screw fixation is one method used to secure the graft. Bioabsorbable interference screws may offer advantages over metal interference screws. Bioabsorbable screws are made from poly L-lactic acid (PLLA)

David A. McGuire; F. Alan Barber; Burton F. Elrod; Lonnie E. Paulos

1999-01-01

334

The treatment of trochanteric fractures using a sliding screw-plate  

Microsoft Academic Search

Summary The authors report a retrospective study of 307 trochanteric fractures treated with a sliding screw-plate (trochanteric hip screw, THS) between January 1989 and December 1994. Mechanical failure was uncommon (3.6%); cutting-out of the screw was the main complication. The revision rate was also low (4%); the 12 cases included 5 total hip replacememts and 2 sliding-screw replacements. Whatever the

D. Jobard; P. Simon; S. R. Babin

1998-01-01

335

PROCESS GAS APPLICATIONS WHERE API 619 SCREW COMPRESSORS REPLACED RECIPROCATING AND CENTRIFUGAL COMPRESSORS  

Microsoft Academic Search

Oil-free screw compressors have been used for process gas application since the 1970s. Oil-flooded screw compressors have been used in many process related applications since the 1980s. Oil-flooded screw compressors are covered in the latest edition of API Standard 619 issued in 2004. Both oil-free and oil-flooded screw compressors have been expanding into process gas com- pression applications. It is

Takao Ohama; Yoshinori Kurioka; Takao Koga

336

Profile generation and analysis for a pp-type single-screw compressor  

Microsoft Academic Search

The precision design of the screw rotor and the gate rotor is the foundation to promoting the operational reliability of a pp-type single-screw compressor. The purpose of the present paper is to determine the mathematical model of a single-screw rotor with conical gate rotors. A simple method by gear theory to determine the profiles of a screw rotor and a

Shyue-Cheng Yang

2006-01-01

337

Compression forces generated by Mini bone screws—a comparative study done on bone model  

Microsoft Academic Search

The compressive forces generated by the AO\\/ASIF 3.0mm cannulated cancellous and 2.0mm cortical screws, Mini-Acutrak and Herbert\\/Whipple small bone cannulated screws were measured in the laboratory with the use of simulated cancellous bone and a load cell washer as a means of quantifying their fixation capabilities. The Herbert\\/Whipple screw and the Mini-Acutrak screw were found to have nearly identical compression

Deepthi Nandan Adla; C. Kitsis; A. W. Miles

2005-01-01

338

Biomechanical and Histological Evaluation of Roughened Surface Titanium Screws Fabricated by Electron Beam Melting  

PubMed Central

Background Various fabrication methods are used to improve the stability and osseointegration of screws within the host bone. The aim of this study was to investigate whether roughened surface titanium screws fabricated by electron beam melting can provide better stability and osseointegration as compared with smooth titanium screws in sheep cervical vertebrae. Methods Roughened surface titanium screws, fabricated by electron beam melting, and conventional smooth surface titanium screws were implanted into sheep for 6 or 12 weeks (groups A and B, respectively). Bone ingrowth and implant stability were assessed with three-dimensional imaging and reconstruction, as well as histological and biomechanical tests. Results No screws in either group showed signs of loosening. Fibrous tissue formation could be seen around the screws at 6 weeks, which was replaced with bone at 12 weeks. Bone volume/total volume, bone surface area/bone volume, and the trabecular number were significantly higher for a define region of interest surrounding the roughened screws than that surrounding the smooth screws at 12 weeks. Indeed, for roughened screws, trabecular number was significantly higher at 12 weeks than at 6 weeks. On mechanical testing, the maximum pullout strength was significantly higher at 12 weeks than at 6 weeks, as expected; however, no significant differences were found between smooth and roughened screws at either time point. The maximum torque to extract the roughened screws was higher than that required for the smooth screws. Conclusions Electron beam melting is a simple and effective method for producing a roughened surface on titanium screws. After 12 weeks, roughened titanium screws demonstrated a high degree of osseointegration and increased torsional resistance to extraction over smooth titanium screws. PMID:24788866

Yang, Jun; Cai, Hong; Lv, Jia; Zhang, Ke; Leng, Huijie; Wang, Zhiguo; Liu, Zhongjun

2014-01-01

339

Estimating Driver Risk Using Alcohol Biomarkers, Interlock BAC Tests and Psychometric Assessments: Initial Descriptives  

PubMed Central

Aim To identify alcohol biomarker and psychometric measures that relate to drivers’ blood alcohol concentration (BAC) patterns from ignition interlock devices (IIDs). Design, Setting, Participants, Measurements In Alberta, Canada, 534 drivers, convicted of driving under the influence of alcohol (DUI), installed IIDs and agreed to participate in a research study. IID BAC tests are an established proxy for predicting future DUI convictions. Three risk groups were defined by rates of failed BAC tests. Program entry and followup blood samples (n=302, 171) were used to measure phosphatidyl ethanol (PETH), carbohydrate deficient transferrin (%CDT), gamma glutamyltransferase (GGT) and other biomarkers. Program entry urine (n=130) was analyzed for ethyl glucuronide (ETG) and ethyl sulfate (ETS). Entry hair samples were tested for fatty acid ethyl esters (FAEE) (n=92) and ETG (n=146). Psychometric measures included the DSM-4 Diagnostic Interview Schedule Alcohol Module, Alcohol Use Disorders Identification Test (AUDIT), the Timeline Followback (TLFB), the Drinker Inventory of Consequences (DRINC), and the Temptation and Restraint Inventory (TRI). Findings Except for FAEE, all alcohol biomarkers were significantly related to the interlock BAC test profiles; higher marker levels predicted higher rates of interlock BAC test failures. PETH, the strongest with an overall ANOVA F ratio of 35.5, had significant correlations with all nine of the other alcohol biomarkers and with 16 of 19 psychometric variables. Urine ETG and ETS were strongly correlated with the IID BAC tests. Conclusions The findings suggest several alcohol biomarkers and assessments could play an important role in the prediction and control of driver alcohol risk when relicensing. PMID:19922520

Marques, Paul; Tippetts, Scott; Allen, John; Javors, Martin; Alling, Christer; Yegles, Michel; Pragst, Fritz; Wurst, Friedrich

2009-01-01

340

Ground-state kinetics of bistable redox-active donor-acceptor mechanically interlocked molecules.  

PubMed

The ability to design and confer control over the kinetics of theprocesses involved in the mechanisms of artificial molecular machines is at the heart of the challenge to create ones that can carry out useful work on their environment, just as Nature is wont to do. As one of the more promising forerunners of prototypical artificial molecular machines, chemists have developed bistable redox-active donor-acceptor mechanically interlocked molecules (MIMs) over the past couple of decades. These bistable MIMs generally come in the form of [2]rotaxanes, molecular compounds that constitute a ring mechanically interlocked around a dumbbell-shaped component, or [2]catenanes, which are composed of two mechanically interlocked rings. As a result of their interlocked nature, bistable MIMs possess the inherent propensity to express controllable intramolecular, large-amplitude, and reversible motions in response to redox stimuli. In this Account, we rationalize the kinetic behavior in the ground state for a large assortment of these types of bistable MIMs, including both rotaxanes and catenanes. These structures have proven useful in a variety of applications ranging from drug delivery to molecular electronic devices. These bistable donor-acceptor MIMs can switch between two different isomeric states. The favored isomer, known as the ground-state co-conformation (GSCC) is in equilibrium with the less favored metastable state co-conformation (MSCC). The forward (kf) and backward (kb) rate constants associated with this ground-state equilibrium are intimately connected to each other through the ground-state distribution constant, KGS. Knowing the rate constants that govern the kinetics and bring about the equilibration between the MSCC and GSCC, allows researchers to understand the operation of these bistable MIMs in a device setting and apply them toward the construction of artificial molecular machines. The three biggest influences on the ground-state rate constants arise from (i) ground-state effects, the energy required to breakup the noncovalent bonding interactions that stabilize either the GSCC or MSCC, (ii) spacer effects, where the structures overcome additional barriers, either steric or electrostatic or both, en route from one co-conformation to the other, and (iii) the physical environment of the bistable MIMs. By managing all three of these effects, chemists can vary these rate constants over many orders of magnitude. We also discuss progress toward achieving mechanostereoselective motion, a key principle in the design and realization of artificial molecular machines capable of doing work at the molecular level, by the strategic implementation of free energy barriers to intramolecular motion. PMID:24341283

Fahrenbach, Albert C; Bruns, Carson J; Li, Hao; Trabolsi, Ali; Coskun, Ali; Stoddart, J Fraser

2014-02-18

341

Magnetic-field decay of three interlocked flux rings with zero linking number  

SciTech Connect

The resistive decay of chains of three interlocked magnetic flux rings is considered. Depending on the relative orientation of the magnetic field in the three rings, the late-time decay can be either fast or slow. Thus, the qualitative degree of tangledness is less important than the actual value of the linking number or, equivalently, the net magnetic helicity. Our results do not suggest that invariants of higher order than that of the magnetic helicity need to be considered to characterize the decay of the field.

Del Sordo, Fabio; Candelaresi, Simon; Brandenburg, Axel [NORDITA, AlbaNova University Center, Roslagstullsbacken 23, SE-10691 Stockholm, Sweden and Department of Astronomy, Stockholm University, SE 10691 Stockholm (Sweden)

2010-03-15

342

Fracture of bilok interference screws on insertion during anterior cruciate ligament reconstruction  

Microsoft Academic Search

New femoral and tibial interference screws for use during anterior cruciate ligament (ACL) reconstruction have been developed using a composite of poly-L-lactic acid (PLLA) and tricalcium phosphate (TCP). The combination is described as having better incorporation than standard bioabsorbable screws with no loss of mass during incorporation and without the brittle nature associated with conventional TCP implants. However, the screw

Chadwick A Smith; T. Duncan Tennent; Sara E Pearson; William R Beach

2003-01-01

343

The roller screw, an efficient and reliable mechanical component of electro-mechanical actuators  

Microsoft Academic Search

The roller screw exists in three different designs which may be used in very different applications: the three designs are respectively known as planetary, differential planetary and recirculating roller screws. Most EMAs which are using roller screws use the planetary design because of its inherent capacity to withstand very high accelerations and speeds and its ability to handle heavy to

P. C. Lemor

1996-01-01

344

Anatomic considerations for standard and modified techniques of cervical lateral mass screw placement  

Microsoft Academic Search

Background context: Posterior screw placement techniques have been previously described. Each technique differs with respect to starting point, lateral angulation and sagittal orientation.Purpose: To examine the potential for injury to critical anatomic structures, such as nerve roots and vertebral arteries, during posterior cervical screw placement and to determine safe screw placement. Study design\\/setting: An anatomic study was conducted to determine

Andrew A Merola; B. Andrew Castro; Paul R Alongi; Sameer Mathur; Mario Brkaric; Franco Vigna; Joseph P Riina; John Gorup; Thomas R Haher

2002-01-01

345

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

346

Experimental determination of instantaneous screw axis in human motions. Error analysis  

Microsoft Academic Search

The location of the instantaneous screw axis (ISA) is essential in order to obtain useful kinematic models of the human body for applications such as prosthesis and orthoses design or even to help in disease diagnosis techniques. In this paper, dual vectors will be used to represent and operate with kinematic screws with the purpose of locating the instantaneous screw

Álvaro Page; Vicente Mata; Juan Víctor Hoyos; Rosa Porcar

2007-01-01

347

Anatomic Reconstruction of the Distal Radioulnar Ligament for Posttraumatic Distal Radioulnar Joint Instability  

PubMed Central

Background To analyze clinical outcomes after anatomical reconstruction of distal radioulnar ligaments in patients with chronic post-traumatic instability of the distal radioulnar joint. Methods Anatomical reconstruction was performed in 16 patients with subluxation or dynamic instability of distal radioulnar joint following trauma. Osteotomy was performed simultaneously in 10 patients with radial malunion. The average follow-up period was 18.9 months. For clinical outcome assessment, we performed the anteroposterior stress test, measured the range of motion and grip strength, and performed radiological examination. For assessment of the pain and function, we used the Patient Rated Wrist Evaluation, the Disabilities of the Arm, Shoulder and Hand, and the Modified Mayo Wrist Score. Results Anteroposterior stress test performed at the last follow-up showed normal in 12 patients, mild laxity in 3, and residual subluxation in one. The average Patient Rated Wrist Evaluation was 9.1 for pain and 11.2 for function. The average Disabilities of the Arm, Shoulder and Hand score was 10.5. The average Modified Mayo Wrist Score was 92.8; there were 10 excellent, 5 good, and 1 poor case. The average grip strength improved from 69.7 1b to 80.9 1b. A revision osteotomy was performed on the patient with residual subluxation in order to obtain normal alignment of the joint. Conclusions Anatomical reconstruction of the distal radioulnar ligaments is recommended to restore distal radioulnar joint stability. In addition to ligament reconstruction, realignment of the distal radioulnar joint seems critical when the instability is combined with malunion of the radius. PMID:19885049

Seo, Kyu Nam; Kang, Hong Je

2009-01-01

348

Clinical outcomes of locked plating of distal femoral fractures in a retrospective cohort  

PubMed Central

Purpose Locked plating (LP) of distal femoral fractures has become very popular. Despite technique suggestions from anecdotal and some early reports, knowledge about risk factors for failure, nonunion (NU), and revision is limited. The purpose of this study was to analyze the complications and clinical outcomes of LP treatment for distal femoral fractures. Materials and methods From two trauma centers, 243 consecutive surgically treated distal femoral fractures (AO/OTA 33) were retrospectively identified. Of these, 111 fractures in 106 patients (53.8% female) underwent locked plate fixation. They had an average age of 54 years (range 18 to 95 years): 34.2% were obese, 18.9% were smokers, and 18.9% were diabetic. Open fractures were present in 40.5% with 79.5% Gustilo type III. Fixation constructs for plate length, working length, and screw concentration were delineated. Nonunion and/or infection, and implant failure were used as outcome complication variables. Outcome was based on surgical method and addressed according to Pritchett for reduction, range of motion, and pain. Results Eighty-three (74.8%) of the fractures healed after the index procedure. Twenty (18.0%) of the patients developed a NU. Four of 20 (20%) resulted in a recalcitrant NU. Length of comminution did not correlate to NU (p?=?0.180). Closed injuries had a higher tendency to heal after the index procedure than open injuries (p?=?0.057). Closed and minimally open (Gustilo/Anderson types I and II) fractures healed at a significantly higher rate after the index procedure compared to type III open fractures (80.0% versus 61.3%, p?=?0.041). Eleven fractures (9.9%) developed hardware failure. Fewer nonunions were found in the submuscular group (10.7%) compared to open reduction (32.0%) (p?=?0.023). Fractures above total knee arthroplasties had a significantly greater rate of failed hardware (p?=?0.040) and worse clinical outcome according to Pritchett (p?=?0.040). Loss of fixation was related to pain (F?=?3.19, p?=?0.046) and a tendency to worse outcome (F?=?2.43, p?=?0.071). No relationship was found between nonunion and working length. Conclusion Despite modern fixation techniques, distal femoral fractures often result in persistent disability and worse clinical outcomes. Soft tissue management seems to be important. Submuscular plate insertion reduced the nonunion rate. Preexisting total knee arthroplasty increased the risk of hardware failure. Further studies determining factors that improve outcome are warranted. PMID:24279475

2013-01-01

349

Cellulose and the twofold screw axis: Modeling and experimental arguments  

Technology Transfer Automated Retrieval System (TEKTRAN)

Crystallography indicates that molecules in crystalline cellulose either have 2-fold screw-axis (21) symmetry or closely approximate it, leading to short distances between H4 and H1' across the glycosidic linkage. Therefore, modeling studies of cellobiose often show elevated energies for 21 structur...

350

Stability of two-fold screw axis structures for cellulose  

Technology Transfer Automated Retrieval System (TEKTRAN)

Diffraction crystallography indicates that most forms of crystalline cellulose have two-fold screw axis symmetry. Even if exact symmetry is absent, the degree of pseudo symmetry is very high. On the other hand, this symmetry leads to short contacts between H4 and H1' across the glycosidic linkage....

351

INTERIOR VIEW OF JAMES HARRIS CUTTING SCREW THREADS INTO THE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

INTERIOR VIEW OF JAMES HARRIS CUTTING SCREW THREADS INTO THE INTERIOR OF FITTINGS ON ONE IN A BANK OF TAPPING MACHINES, EACH OPERATED BY THE SAME WORKER SIMULTANEOUSLY BUT TIMED TO REQUIRE WORKER ACTION AT INTERVALS THAT DO NOT INTERFERE WITH THE OTHER MACHINES. - Stockham Pipe & Fittings Company, Tapping Room, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

352

The Use of Small Titanium Screws for Orthodontic Anchorage  

Microsoft Academic Search

The use of conventional dental implants for orthodontic anchorage is limited by their large size. The purpose of this study was to quantify the histomorphometric properties of the bone-implant interface to analyze the use of small titanium screws as an orthodontic anchorage and to establish an adequate healing period. Overall, successful rigid osseous fixation was achieved by 97% of the

T. Deguchi; T. Takano-Yamamoto; R. Kanomi; J. K. Hartsfield; W. E. Roberts; L. P. Garetto

2003-01-01

353

The Influence of Rotor Deflection upon Screw Compressor Performance  

Microsoft Academic Search

SUMMARY The compression process within screw compressors induces large pressure and temperature changes that cause the rotors to deform. To determine this effect, a 3-D numerical method has been developed to calculate flow and deformation simultaneously. This comprises a mathematical procedure to generate a numerical grid for both the solid and fluid domains, in the form of a computer program

Ahmed Kovacevic; Ian K. Smith

354

Cooling of oil injected screw compressors by oil atomisation  

Microsoft Academic Search

This paper addresses the effect of oil atomisation in an oil-injected screw compressor. A test rig was built to assess the performance of different types of atomisers. Atomisers varying from fine atomisation to coarse atomisation were tested. Experiments on the test rig show that lowering the oil droplet diameter results in a considerably higher heat transfer. Growing oil flow rate,

M. De Paepe; W. Bogaert; D. Mertens

2005-01-01

355

Retrofit 'N' Rotors for Efficient Oil-Flooded Screw Compressors  

Microsoft Academic Search

The market for twin screw compressors is highly competitive, especially in compressed air and refrigeration systems, and new designs are continually being introduced which are more efficient and cost effective than their predecessors. However, because of the high cost of development of new machines, manufacturers seek to maintain their existing designs for as long as possible. Closer study of many

N. Stosic; I. K. Smith; A. Kovacevic; K. Venumadhav

2000-01-01

356

The CFD Analysis of a Screw Compressor Suction Flow  

Microsoft Academic Search

Dynamic flow losses in the suction chamber play a very important if not the main role in the efficiency decrease in screw compressors. The design of these machines, together with the accounting of flow losses and how to reduce them, is still based only on the simple analysis. Since Computational Fluid Mechanics offers today a more accurate estimation of the

N. Stosic; A. Kovacevic; I. K. Smith

2000-01-01

357

levelling screws; the disk is then raised until the small  

E-print Network

and the operation is repeated until the zero does coin- cide with .... It is then washed several times in pure water and cried .... ing hole and thread into which the handle 5 is not screwed. .... same way as shot, except the test of strength by drop-.

358

Twin-screw extrusion of ‘Pesta’-encapsulated biocontrol agents  

Microsoft Academic Search

‘Pesta’ granules in which fungal propagules are encapsulated in a wheat gluten matrix were prepared in multipound quantities by twin-screw extrusion and fluid bed drying. Dough formulations for extrusion contained wheat flour and kaolin, or wheat flour, kaolin and rice flour, plus water and fungal inoculum. Conidial inoculum of Colletotrichum truncatum, a pathogen of the weed hemp sesbania (Sesbania exaltata),

D. J. Daigle; W. J. Connick; C. D. Boyette; M. P. Lovisa; K. S. Williams; M. Watson

1997-01-01

359

Surgical approaches to the distal radioulnar joint.  

PubMed

For the distal radioulnar joint (DRUJ) to be stable, not only do the articulating surfaces need to be congruent and well aligned but also the capsule and ligaments need to be mechanically and sensorially competent. According to recent investigations, ligaments should not be regarded as simple static structures maintaining articular alignment but as complex arrangements of collagen fibers containing mechanoreceptors, which are able to generate neural reflexes aiming at a more efficient and a more definitive muscular stabilization. By careful planning and meticulous execution of surgical incisions to approach the DRUJ, the nerve endings innervating the capsule and DRUJ ligaments may be safeguarded, thus preserving the proprioceptive function of the joint. PMID:20951897

Garcia-Elias, Marc; Hagert, Elisabet

2010-11-01

360

Distal Renal Tubular Acidosis and Calcium Nephrolithiasis  

NASA Astrophysics Data System (ADS)

Calcium stones are commonly encountered in patients with congenital distal renal tubular acidosis, a disease of renal acidification caused by mutations in either the vacuolar H+-ATPase (B1 or a4 subunit), anion exchanger-1, or carbonic anhydrase II. Based on the existing database, we present two hypotheses. First, heterozygotes with mutations in B1 subunit of H+-ATPase are not normal but may harbor biochemical abnormalities such as renal acidification defects, hypercalciuria, and hypocitraturia which can predispose them to kidney stone formation. Second, we propose at least two mechanisms by which mutant B1 subunit can impair H+-ATPase: defective pump assembly and defective pump activity.

Moe, Orson W.; Fuster, Daniel G.; Xie, Xiao-Song

2008-09-01

361

VSHOT Measurements of Distal II Dish Concentrators  

SciTech Connect

The Video Scanning Hartmann Optical Tester (VSHOT) is a laser ray-trace tool for measuring the slope error of solar concentrator mirrors. The VSHOT measurements made on two, 8.5-m diameter, Distal II dishes represent its first use on a concentrator installed and operating in the field. A number of valuable lessons were learned regarding the use of the VSHOT for outdoor testing. The two dishes were found to have overall figure-of-merit RMS slope errors from an ideal parabola of 2.99 and 3.18 milliradians. The VSHOT measurements compare well qualitatively with distant observer photographs made using a colored concentric ring target.

Jones, S.A.

1998-12-14

362

Revascularization options for terminal distal ischemia.  

PubMed

Direct arterial bypass remains the best option in patients with terminal ischemia of the hand, if there is an adequate distal target vessel. In situ bypass is the procedure of choice in patients who are candidates for arterial bypass. Venous arterialization offers an option in patients in whom there is not adequate arterial runoff in the hand. Venous arterialization should be avoided in patients with significant wounds and/or active infection. In selected patients, microvascular omental transfer can offer an option for revascularization of the ischemic hand. PMID:25455358

Pederson, William C

2015-02-01

363

Periareolar Augmentation Mastopexy with Interlocking Gore-Tex Suture, Retrospective Review of 50 Consecutive Patients  

PubMed Central

Background Periareolar Augmentation Mastopexy is one of the most challenging operations in plastic surgery. Problems with scar quality, areolar widening, and distortion are frequent problems that interfere with a predictable result. Methods A retrospective review was performed on fifty consecutive patients who underwent a periareolar augmentation mastopexy with the interlocking approach. Of the 50 patients, 30 had both preoperative and postoperative photographs and were the basis of the study. Results The age of the patients ranged from 19 to 56 years with the average age being 39 years. The postoperative follow-up averaged 9.5 months and the implants averaged 316 mL. There were no deaths, pulmonary embolism, deep vein thrombosis, or infected implants. Four patients had complications following surgery for an overall complication rate of 13%. Two patients developed an infected Gore-Tex suture. Two of these complications were treated with revision surgery. Five patients required reoperation for an overall reoperative rate of 16% (one patient was converted to a full mastopexy). Conclusions As a result of this retrospective study, we have found the interlocking approach to periareolar augmentation/mastopexy to be a safe and reliable operation. PMID:25396187

Kelly, Emma; Kelly, Michael

2014-01-01

364

The formation mechanisms of interlocked microstructures in low-carbon high-strength steel weld metals  

SciTech Connect

Microstructural features and the formation mechanisms of interlocked microstructures of acicular ferrite in a low-carbon high-strength steel weld metal were investigated by means of computer-aided three-dimensional reconstruction technique and electron backscattered diffraction analysis. Multiple nucleation on inclusions, sympathetic nucleation or repeated nucleation, hard impingement, mutual intersection, and fixed orientation relationships of acicular ferrite grains were observed. They were all responsible for the formation of interlocked microstructures in the weld metal. During the process of isothermal transformation, the pre-formed acicular ferrite laths or plates partitioned austenite grains into many small and separate regions, and the growth of later formed acicular ferrite grains was confined in these small regions. Thus, the crystallographic grain size became smaller with the increasing holding time. Highlights: Black-Right-Pointing-Pointer Acicular ferrite is formed by multiple nucleation and sympathetic nucleation. Black-Right-Pointing-Pointer Hard impingement and intersection of ferrite grains occur at later stages. Black-Right-Pointing-Pointer The pre-formed ferrite laths partition austenite grains into smaller regions. Black-Right-Pointing-Pointer The growth of later formed ferrite grains is confined in the smaller regions.

Wan, X.L.; Wang, H.H.; Cheng, L.; Wu, K.M., E-mail: wukaiming2000@yahoo.com

2012-05-15

365

Analysis of load redistribution in diaphyseal bone following staged screw removal from bone plates  

E-print Network

, overall imply on average that there is a trend towards reduced bone loading as screws are removed from 30 the plate. Similarly inconclusive results occur at lower loads. Oddly, the greatest strain in all instances appears in the most anterior gages... screws when screws 1 and 6 are removed and anterior to the first screw when screws 2, 3, and 4 are removed. The loading of the bone in the anterior regions is probably due to the complex geometry of the bone. The femoral head and anterior bend...

Nixon, Joseph Craig

1987-01-01

366

The improvement of screw compressor performance using a newly developed rotor profile  

SciTech Connect

An oil-compression phenomenon occurs at two portions of a conventional oil injected screw compressor that degrades the isothermal efficiency of the screw compressor. Hence a new screw rotor profile and lubricant have been developed in order to avoid the above oil-compression phenomena. Mycom and Fermi National Accelerator Laboratory have measured the performance of a new Mycom compound type screw compressor 2016C using the new profile rotors and the new lubricant. In the experiments, a 33% enhancement rate in the isothermal efficiency of the new screw compressor installed in Fermilab was achieved.

Kishi, Takayuki; Nishio, Toshio; Matsui, Akira; Ino, Nobumi [Mayekawa Mfg. Co. Ltd., Ibaraki (Japan)

1994-12-31

367

Covering the Screw-Access Holes of Implant Restorations in the Esthetic Zone: A Clinical Report  

PubMed Central

Screw-retained implant restorations have an advantage of predictable retention as well as retrievability, and obviate the risk of excessive sub-gingival cement commonly associated with cement retained implant restorations. Screw-retained restorations generally have screw access holes, which can compromise esthetics and weaken the porcelain around the holes. The purpose of this study is to describe the use of a separate overcasting crown design to cover the screw access hole of implant screw-retained prosthesis for improved esthetics. PMID:25628703

Saboury, Abolfazl; Gooya, Ali

2014-01-01

368

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. PMID:23112935

Halicio?lu, Koray; Kiki, Ali

2012-01-01

369

The general theory of blade screws including propellers, fans, helicopter screws, helicoidal pumps, turbo-motors, and different kinds of helicoidal blades  

NASA Technical Reports Server (NTRS)

Report presents a theory which gives a complete picture and an exact quantitative analysis of the whole phenomenon of the working of blade screws, but also unites in a continuous whole the entire scale of states of work conceivable for a blade screw. Chapter 1 is devoted to the establishment of the system of fundamental equations relating to the blade screw. Chapter 2 contains the general discussion of the 16 states of work which may establish themselves for a blade screw. The existence of the vortex ring state and the whirling phenomenon are established. All the fundamental functions which enter the blade-screw theory are submitted to a general analytical discussion. The general outline of the curve of the specific function is examined. Two limited cases of the work of the screw, the screw with a zero constructive pitch and the screw with an infinite constructive pitch, are pointed out. Chapter 3 is devoted to the study of the propulsive screw or propeller. (author)

De Bothezat, George

1920-01-01

370

Review article: aminosalicylates for distal colitis.  

PubMed

About two-thirds of patients with ulcerative colitis have an inflammatory involvement distal to the splenic flexure and therefore may be effectively treated with topical treatment. This allows the delivery of the active drug directly to the site of inflammation, limiting the systemic absorption and the potential side effects. Topical aminosalicylate therapy is the most effective approach, provided that the formulation reaches the upper extent of the disease. Suppositories should be considered the treatment of choice for proctitis and distal sigmoiditis. A 1 g Pentasa-suppository once daily induces a quicker clinical and endoscopic remission and was better tolerated than a 500-mg suppository twice daily. Enemas, foams and gel, thanks to their proximal spread, should be the treatment of choice for proctosigmoiditis and left-sided colitis. Oral aminosalicylates are less effective than topical therapies for patients with active disease; however, a combination of oral and topical aminosalicylates can be successfully tried in refractory patients. Topical aminosalicylates also play an important role in the maintenance of remission, and the combination of oral plus rectal 5-aminosalicylate is superior to the single agent. Patients who prefer not to continue on long-term rectal therapy can be treated with oral aminosalicylates. PMID:16961744

Gionchetti, P; Rizzello, F; Morselli, C; Tambasco, R; Campieri, M

2006-10-01

371

Evaluation of different screw fixation techniques and screw diameters in sagittal split ramus osteotomy: finite element analysis method.  

PubMed

Sagittal split ramus osteotomy (SSRO) is used for correction of numerous congenital or acquired deformities in facial region. Several techniques have been developed and used to maintain fixation and stabilisation following SSRO application. In this study, the effects of the insertion formations of the bicortical different sized screws to the stresses generated by forces were studied. Three-dimensional finite elements analysis (FEA) and static linear analysis methods were used to investigate difference which would occur in terms of forces effecting onto the screws and transmitted to bone between different application areas. No significant difference was found between 1·5- and 2-mm screws used in SSRO fixation. Besides, it was found that 'inverted L' application was more successful compared to the others and that was followed by 'L' and 'linear' formations which showed close rates to each other. Few studies have investigated the effect of thickness and application areas of bicortical screws. This study was performed on both advanced and regressed jaws positions. PMID:24889187

Sindel, A; Demiralp, S; Colok, G

2014-09-01

372

Cannulated screw fixation of Jones fifth metatarsal fractures: a comparison of titanium and stainless steel screw fixation.  

PubMed

The classic Jones fracture involves the fifth metatarsal at the level of the proximal diaphyseal-metaphyseal junction. The mainstay of surgical treatment for the Jones fracture is intramedullary screw fixation. There is no consensus of the type or material of screw that should be used. The purpose of this retrospective cohort study was to test the hypothesis that there is no clinical difference in the incidence of healing, or complications, when comparing stainless steel to titanium cannulated screws used in Jones fracture open-reduction internal fixation (ORIF). Data were collected on a total of 53 patients (fractures) that were fixed with either cannulated titanium screws (Ti group) or cannulated stainless steel screws (SS group). The postoperative protocol was standardized. The mean time to radiographic union was 11.7 ± 5.1 weeks in the Ti group and 13.4 ± 5.7 weeks in the SS group (P = .333). The overall union rate for the Ti group was 36/37 (97%) and 14/16 (88%) in the SS group (P = .213). Complications were rare in both groups, and the prevalence was not statistically significantly different (P > .05). There was 1 patient with an asymptomatic radiographic nonunion in the Ti group, and this patient elected not to undergo revision. There were 2 nonunions in the SS group. One was revised and went on to heal and the other is awaiting revision. Our study has demonstrated the decision to use stainless steel or titanium can be left to patient constraints, such as allergies, or physician preference without compromising the clinical result. PMID:21354005

DeVries, J George; Cuttica, Daniel J; Hyer, Christopher F

2011-01-01

373

Unraveling the genetics of distal hereditary motor neuronopathies  

Microsoft Academic Search

The hereditary motor neuronopathies (HMN [MIM 158590]) are heterogeneous group of disorders characterized by an exclusive\\u000a involvement of the motor part of the peripheral nervous system. They are usually subdivided in proximal HMN, i.e., the classical\\u000a spinal muscular atrophy syndromes and distal hereditary motor neuronopathies (distal HMN) that clinically resemble Charcot-Marie-Tooth\\u000a syndromes. In this review, we concentrate on distal HMN.

Joy Irobi; Ines Dierick; Albena Jordanova; Kristl G. Clayes; Peter De Jonghe; Vincent Timmerman

2006-01-01

374

Distalization of the patella during tibial callus distraction.  

PubMed

Consecutive distalization of the patella is described in two patients undergoing segmental transportation after high tibial corticotomy. Revision surgery with loosening and proximal reattachment of a portion of the patellar ligament bridging the callus distraction zone could re-establish the correct patellar position. Despite excellent callus formation after tibial corticotomy just below the tibial tuberositas, this procedure should be performed more distally as the fibers of the patellar tendon spread laterally and distally. PMID:9709862

Eingartner, C; Bretschneider, C; Badke, A; Weise, K

1998-01-01

375

Distal Xq duplication and functional Xq disomy  

PubMed Central

Distal Xq duplications refer to chromosomal disorders resulting from involvement of the long arm of the X chromosome (Xq). Clinical manifestations widely vary depending on the gender of the patient and on the gene content of the duplicated segment. Prevalence of Xq duplications remains unknown. About 40 cases of Xq28 functional disomy due to cytogenetically visible rearrangements, and about 50 cases of cryptic duplications encompassing the MECP2 gene have been reported. The most frequently reported distal duplications involve the Xq28 segment and yield a recognisable phenotype including distinctive facial features (premature closure of the fontanels or ridged metopic suture, broad face with full cheeks, epicanthal folds, large ears, small and open mouth, ear anomalies, pointed nose, abnormal palate and facial hypotonia), major axial hypotonia, severe developmental delay, severe feeding difficulties, abnormal genitalia and proneness to infections. Xq duplications may be caused either by an intrachromosomal duplication or an unbalanced X/Y or X/autosome translocation. In XY males, structural X disomy always results in functional disomy. In females, failure of X chromosome dosage compensation could result from a variety of mechanisms, including an unfavourable pattern of inactivation, a breakpoint separating an X segment from the X-inactivation centre in cis, or a small ring chromosome. The MECP2 gene in Xq28 is the most important dosage-sensitive gene responsible for the abnormal phenotype in duplications of distal Xq. Diagnosis is based on clinical features and is confirmed by CGH array techniques. Differential diagnoses include Prader-Willi syndrome and Alpha thalassaemia-mental retardation, X linked (ATR-X). The recurrence risk is significant if a structural rearrangement is present in one of the parent, the most frequent situation being that of an intrachromosomal duplication inherited from the mother. Prenatal diagnosis is performed by cytogenetic testing including FISH and/or DNA quantification methods. Management is multi-specialist and only symptomatic, with special attention to prevention of malnutrition and recurrent infections. Educational and rehabilitation support should be offered to all patients. Disease name Xq duplications, Xq functional disomy PMID:19232094

Sanlaville, Damien; Schluth-Bolard, Caroline; Turleau, Catherine

2009-01-01

376

Topological and Conformational Effects on Electron Transfer Dynamics in Porphyrin-[60]Fullerene Interlocked Systems  

PubMed Central

The effect of molecular topology, and conformation on the dynamics of photoinduced electron transfer (ET) processes has been studied in interlocked electron donor-acceptor systems, specifically rotaxanes with zinc(II)-tetraphenylporphyrin (ZnP) electron donor and [60]fullerene (C60) as the electron acceptor. Formation or cleavage of coordinative bonds was used to induce major topological and conformational changes in the interlocked architecture. In the first approach, the tweezers-like structure created by the two ZnP stopper groups on the thread was used as a recognition site for complexation of 1,4-diazabicyclo[2.2.2]octane (DABCO), which creates a bridge between the two ZnP moieties on the rotaxane, generating a catenane structure. The photoinduced processes in the DABCO-complexed (ZnP)2-[2]catenate-C60 system were compared with those of the (ZnP)2-rotaxane-C60 precursor and the previously reported ZnP-[2]catenate-C60. Steady-state emission and transient absorption studies showed that a similar multistep ET pathway emerged for rotaxanes and catenanes upon photoexcitation at various wavelengths, ultimately resulting in a long-lived ZnP•+/C60•? charge separated radical pair state. However, the decay kinetics of the latter states clearly reflect the topological differences between the rotaxane, the catenate, and DABCO-complexed-catenate architectures. The lifetime of the long-distance ZnP•+–[Cu(I)phen2]+–C60•? charge separated state is more than four times longer in 3 (1.03 µs) than in 1 (0.24 µs) and approaches that in catenate 2 (1.1 µs). The results clearly showed that adoption of a catenane from a rotaxane topology inhibits the charge recombination process. In a second approach, the Cu(I) ion used as template to assemble the (ZnP)2–[Cu(I)phen2]+–C60 rotaxane was removed, and structural analysis suggested a major topographical change occurred, such that charge separation between the chromophores was no longer observed upon photoexcitation in nonpolar as well as polar solvents. Only ZnP and C60 triplet excited states were observed upon laser excitation. These results highlighted the critical importance of the central Cu(I) ion for long range ET processes in these large interlocked electron donor-acceptor systems. PMID:22984324

de Miguel, Gustavo; Wolfrum, Silke

2012-01-01

377

Medical expulsive therapy for distal ureteral stones.  

PubMed

Although minimally invasive treatments for ureteral stones are efficacious, they are not free of complications and are associated with high cost. Medical expulsive therapy (MET) has recently emerged as an alternative strategy for the initial management of small distal ureteral stones. A MEDLINE search was undertaken to evaluate all currently available data on efficacy and safety of MET therapy in such patients. The specific mechanism of action on the ureteral smooth muscle and the emerging evidence of the efficacy (defined as either an increase in expulsion rate or a decrease in time to expulsion) and low-risk profile suggest that alpha-adrenergic receptor antagonists (alpha-blockers) and calcium channel antagonists should be the initial medical treatment in patients amenable to conservative therapy. NSAIDs and anticholinergics have not shown efficacy as single agents or in combination with alpha-blockers or nifedipine. Corticosteroids may provide a small additive effect when combined with either alpha-blockers or nifedipine. PMID:19405549

Tzortzis, Vassilios; Mamoulakis, Charalampos; Rioja, Jorge; Gravas, Stavros; Michel, Martin C; de la Rosette, Jean J M C H

2009-01-01

378

Comparison between Bilateral C2 Pedicle Screwing and Unilateral C2 Pedicle Screwing, Combined with Contralateral C2 Laminar Screwing, for Atlantoaxial Posterior Fixation  

PubMed Central

Study Design A retrospective study. Purpose To compare clinical and radiological outcomes between bilateral C2 pedicle screwing (C2PS) and unilateral C2PS, combined with contralateral C2 laminar screwing (LS), for posterior atlantoaxial fixation. Overview of Literature Posterior fixation with C1 lateral mass screwing (C1LMS) and C2PS (C1LMS-C2PS method) is an accepted procedure for rigid atlantoaxial stabilization. However, conventional bilateral C2PS is not always allowed in this method due to anatomical variations of C2 pedicles and/or asymmetry of the vertebral artery. Although unilateral C2PS plus contralateral LS (C2PS+LS) is an alternative in such cases, the efficacy of this procedure has not been evaluated in controlled studies (i.e., with bilateral C2PS as a control). Methods Clinical and radiological records of patients who underwent the C1LMS-C2PS method, using unilateral C2PS+LS (n=9), and those treated using conventional bilateral C2PS (n=10) were compared, with a minimum two years follow-up. Results Postoperative complications related to the unilateral C2PS+LS technique included one case of spontaneous spinous process fracture of C2. A C1 anterior arch fracture occurred after a fall in one patient, who underwent bilateral C2PS and C1 laminectomy. No significant differences were seen between the groups in reduction of neck pain after surgery or improvement of neurological status, as evaluated using the Japanese Orthopaedic Association score. A delayed union occurred in one patient each of the groups, with the final fusion rate being 100% in both groups. Conclusions Clinical and radiological outcomes of unilateral C2PS+LS were comparable with those of the bilateral C2PS fixation technique for the C1LMS-C2PS method. PMID:25558320

Hongo, Michio; Kobayashi, Takashi; Suzuki, Tetsuya; Abe, Eiji; Shimada, Yoichi

2014-01-01

379

Structure of screw dislocation core in Ta at high pressure  

SciTech Connect

The core structure and Peierls stress of the 1/2 ?111?(110) screw dislocation in Ta have been investigated theoretically using the modified Peierls–Nabarro theory that takes into account the discreteness effect of crystal. The lattice constants, the elastic properties, and the generalized-stacking-fault energy(?-surface) under the different pressures have been calculated from the electron density functional theory. The core structure of dislocation is determined by the modified Peierls equation, and the Peierls stress is evaluated from the dislocation energy that varies periodically as dislocation moves. The results show the core width and Peierls stress in Ta are weakly dependent of the pressure up to 100?GPa when the length and stress are measured separately by the Burgers vector b and shear modulus ?. This indicates that core structure is approximately scaling invariant for the screw dislocation in Ta. The scaled plasticity of Ta changes little in high pressure environment.

Wang, Shaofeng, E-mail: sfwang@cqu.edu.cn; Jiang, Na; Wang, Rui; Zhou, Ying [Institute for Structure and Function and Department of Physics, Chongqing University, Chongqing 400030 (China)

2014-03-07

380

Screw pumps provide high efficiency in transport of Orinoco bitumen  

SciTech Connect

One of the world`s largest known deposits of extra natural bitumen is located in the Orinoco River basin of eastern Venezuela. Production and transportation of an emulsion of bitumen and water is one of the major projects being directed by Petroleos de Venezuela S.A. This paper reviews the pump selection options considered in transporting this bitumen to a viable processing facility. The three pump types evaluated were centrifugal, reciprocating, or rotary screw. Performance and cost parameters are evaluated and the screw pump was determined to be the most economical, high performance choice. The paper goes on to describe the installation of the main transport lines and efficiency of these new pumps.

Brennan, J.R. [IMO Industries, Inc., Monroe, NC (United States)

1995-03-01

381

Detecting thrust bearing failure within a screw compressor  

SciTech Connect

A 3 1/2 mile ring of over 1000 superconducting magnets are needed to focus and drive the world`s highest energy particle smasher. 24 Refrigerators supply liquid helium to the magnets; 34 high pressure oil flooded screw compressors supply 285 psig helium gas to the refrigerators. The 400 h.p. screws are reliable machines that use 45 gallons of oil per minute to seal and lubricate the rotors, lubricate the bearings, and remove the heat of compression. These machines are spaced out in seven buildings over four miles. A minimum of 28 machines must be operating at all times. A contingent of operators start, stop, and monitor any machine from a distant control room. The 34 compressors have an average of 32,000 hours; 9 machines have over 40,000 hours; the highest is 55,000 hours.

Pallaver, C.

1994-05-01

382

Efficiency study of oil cooling of a screw compressor  

SciTech Connect

One of the major goals of all compressor manufacturers is to design and build as efficient a compressor as possible. In a screw compressor it appears that the way the compressor is cooled can have an effect on the compressor's efficiency. This paper presents experimental data on three different screw compressor cooling methods: Liquid Refrigerant Injection Cooling System; Thermosyphon Cooling System; and Oil Injection System. All tests were conducted on a hot gas bypass system using refrigerant R-22. The data taken shows that the Oil Injection System is slightly better than the other two. These tests should be repeated with a higher oil flow rate and ammonia as the working fluid. 10 figs.

Tree, D.R.; McKellar, M.G. (Purdue Univ., Lafayette, IN (USA). Ray W. Herrick Labs.); Fresco, A. (Brookhaven National Lab., Upton, NY (USA))

1990-01-01

383

Analysis of Eyring-Powell Fluid in Helical Screw Rheometer  

PubMed Central

This paper aims to study the flow of an incompressible, isothermal Eyring-Powell fluid in a helical screw rheometer. The complicated geometry of the helical screw rheometer is simplified by “unwrapping or flattening” the channel, lands, and the outside rotating barrel, assuming the width of the channel is larger as compared to the depth. The developed second order nonlinear differential equations are solved by using Adomian decomposition method. Analytical expressions are obtained for the velocity profiles, shear stresses, shear at wall, force exerted on fluid, volume flow rates, and average velocity. The effect of non-Newtonian parameters, pressure gradients, and flight angle on the velocity profiles is noticed with the help of graphical representation. The observation confirmed the vital role of involved parameters during the extrusion process. PMID:24707194

Siddiqui, A. M.; Haroon, T.; Zeb, M.

2014-01-01

384

Crystalline stereocomplexed polycarbonates: hydrogen-bond-driven interlocked orderly assembly of the opposite enantiomers.  

PubMed

Four novel crystalline stereocomplexed polymers are formed by mixing isotactic (R)- and (S)-polycarbonates in 1:1 mass ratio. They show the enhanced thermal stability and new crystalline behavior, significantly distinct from the component enantiomer. Two stereocomplexed CO2 -based polycarbonates from meso-3,4-epoxytetrahydrofuran and 4,4-dimethyl-3,5,8-trioxabicyclo[5.1.0]octane have high melting temperatures of up to 300?°C, about 30?°C higher than the individual enantiomers. Isotactic (R)- or (S)-poly(cyclopentene carbonate) and poly(cis-2,3-butene carbonate) are typical amorphous polymeric materials, however, upon mixing both enantiomers together, a strong interlocked interaction between polymer chains of opposite configuration occurs, affording the crystalline stereocomplexes with melting temperatures of about 200?°C and 180?°C, respectively. A DFT study suggests that the driving force forming the stereocomplex is the hydrogen-bonding between carbonate units of the opposite enantiomers. PMID:25537626

Liu, Ye; Ren, Wei-Min; Wang, Meng; Liu, Chuang; Lu, Xiao-Bing

2015-02-01

385

Disturbed basal ice seen in radio echo images coincide with zones of big interlocking ice crystals.  

NASA Astrophysics Data System (ADS)

Improvement of the depth sounding radio echo sounding (RES) over Antarctica and Greenland Ice Sheet has made it possible to map the near basal layers that have not been 'seen' earlier due to the very high demand of attenuation needed to reach through more than 3000m of ice. The RES internal reflectors show that the near basal ice at many locations has disturbed layering. At the locations where ice cores reach the bedrock both in Greenland and Antarctica studies of the ice crystal size and orientation show that the near basal ice has big and interlocking ice crystals which suggests the ice is not actively deforming. These observations challenge the often used constitutive equations like Glens flow law in ice sheet modelling. A discussion of the impact of the RES findings on ice sheet modeling and the quest to find the oldest ice in Antarctic based on the anisotropy of the basal ice will follow.

Dahl-Jensen, Dorthe; Gogineni, Sivaprasad; Panton, Christian

2014-05-01

386

Mechanical Interlocking between Porous Electrospun Polystyrene Fibers and an Epoxy Matrix.  

PubMed

An epoxy matrix filled with nonwoven mats of porous polystyrene (PS) fibers processed by an electrospinning was compression tested at quasi-static (1 × 10(-3) s(-1)) and high strain (315 s(-1)) rates. The electrospun PS fibers with a diameter between 6 and 9 ?m, accommodated spherical pores on the surface with the sizes ranging from 0.1 to 0.2 ?m. The filling epoxy matrix with 0.2 wt % PS fibers increased the compressive elastic modulus and compressive strength over those of neat epoxy resin. The microscopic observations indicated that the surface pores facilitated the resin intrusions into the fiber, enhancing the interlocking between resin and fibers, and increased the deformation energy expenditure of the polymer matrix. PMID:25485762

Demir, Mustafa M; Horzum, Nesrin; Ta?demirci, Alper; Turan, K?vanç; Güden, Mustafa

2014-12-24

387

The Community Structure of the European Network of Interlocking Directorates 2005–2010  

PubMed Central

The boards of directors at large European companies overlap with each other to a sizable extent both within and across national borders. This could have important economic, political and management consequences. In this work we study in detail the topological structure of the networks that arise from this phenomenon. Using a comprehensive information database, we reconstruct the implicit networks of shared directorates among the top 300 European firms in 2005 and 2010, and suggest a number of novel ways to explore the trans-nationality of such business elite networks. Powerful community detection heuristics indicate that geography still plays an important role: there exist clear communities and they have a distinct national character. Nonetheless, from 2005 to 2010 we observe a densification of the boards interlocks network and a larger transnational orientation in its communities. Together with central actors and assortativity analyses, we provide statistical evidence that, at the level of corporate governance, Europe is getting closer. PMID:23894318

Heemskerk, Eelke M.; Daolio, Fabio; Tomassini, Marco

2013-01-01

388

The community structure of the European network of interlocking directorates 2005-2010.  

PubMed

The boards of directors at large European companies overlap with each other to a sizable extent both within and across national borders. This could have important economic, political and management consequences. In this work we study in detail the topological structure of the networks that arise from this phenomenon. Using a comprehensive information database, we reconstruct the implicit networks of shared directorates among the top 300 European firms in 2005 and 2010, and suggest a number of novel ways to explore the trans-nationality of such business elite networks. Powerful community detection heuristics indicate that geography still plays an important role: there exist clear communities and they have a distinct national character. Nonetheless, from 2005 to 2010 we observe a densification of the boards interlocks network and a larger transnational orientation in its communities. Together with central actors and assortativity analyses, we provide statistical evidence that, at the level of corporate governance, Europe is getting closer. PMID:23894318

Heemskerk, Eelke M; Daolio, Fabio; Tomassini, Marco

2013-01-01

389

Testing the permeability and corrosion resistance of micro-mechanically interlocked joints  

NASA Astrophysics Data System (ADS)

Micro-mechanical interlocking (MMI) can be applied to create new and interesting composite materials. We have employed laser structuring to achieve MMI between stainless steel and plastic with extremely high joint strength. However, the water permeability and corrosion resistance of the joint must be examined. For many industrially relevant applications it is important to keep water away from certain parts and to prevent the sample from corroding. A thorough study of the permeability of the interconnected samples at different temperatures and after employing different laser-structuring techniques is conducted. The permeability seems to be consistent with the Hagen-Poiseuille equation independent of the laser structuring technique and is orders of magnitudes larger than the diffusion rate through the plastic. Two different types of corrosion tests have been undertaken, and we show that care must be taken in order not to degrade the corrosion resistance of the sample to an unacceptable level.

Byskov-Nielsen, Jeppe; Holm, Allan H.; Højsholt, Rune; Sá, Pedro; Balling, Peter

2011-09-01

390

Groovy as Domain-Specific Language in the Software Interlock System  

E-print Network

After over 7 years in operation the Software Interlock System (SIS) has become an indispensable and mission critical controls tool covering many operational areas from general machine protection to diagnostics. The growing number of running instances as much as the size of existing configurations have increased both the complexity and maintenance cost of running the SIS infrastructure. In response to those issues, new ways of configuring the system have been investigated aiming at simplifying the configuration process by making it faster, more user-friendly and understandable for wider audiences and domain experts alike. As one of the possible choices the Groovy scripting language has been considered as being particularly well suited for writing a custom Domain-Specific Language (DSL) due to its built-in language features like native syntax constructs, command chain expressions, hierarchical structures with builders, closures or Abstract Syntax Tree (AST) transformations. This document explains best practices...

Wozniak, J; Kruk, G

2014-01-01

391

Screw compressor bearing failure at CO No. 4  

SciTech Connect

This report is a record of a bearing failure observed on a screw compressor which is a mechanical component run continuously in an unattended mode at Fermi National Accelerator Laboratory. It records how this fault was noticed, monitored, and progressed to ultimate machine trip, within the span of one day, and how the protection systems attached to the compressor performed in monitoring the development of this equipment failure.

Pallaver, C.; Cross, T.

1995-04-01

392

Flow and pressure characteristics within a screw compressor  

Microsoft Academic Search

The angle-resolved mean and turbulence characteristics of the axial air flow inside a screw compressor with both male and female rotors have been measured, using a laser Doppler velocimeter (LDV) with high spatial and temporal resolution at different radial and axial locations for speeds of 800-1600 rpm, discharge pressures of 1-1.6 bar and discharge temperatures of 33-90°C. The velocity measurements

D. Guerrato; J. M. Nouri; N. Stosic; C. Arcoumanis

2007-01-01

393

Gear-Cutting Tool for Screw-Compressor Rotors  

Microsoft Academic Search

A built-up hob for a screw-compressor rotor is proposed. The hob is composed of cutter blades and a hob head. The blade is cut out from a tempered planar plate of high speed tool steel by wire-cut electrodischarge machining (EDM). During the wire cutting process, the wire electrode has a fixed angle to ensure both the side and the end

Katsumi Kaneko; Kazumasa Kawasaki; Hisashi Tamura

2001-01-01

394

Investigation of seals with floating rings in a screw compressor  

Microsoft Academic Search

A number of screw compressors (SC) produced in the Soviet Union for air compression to a pressure of 1.5-2.5 kg\\/cm 2 use metallic labyrinth seals. The efficiency of these seals decreases rapidly as discharge pressure increases. Replacing these labyrinth seals by better designs can substantially reduce air leakage through the end seals of the SC and can improve their efficiency.

F. L. Yuditskii; B. L. Grinpress; Yu. L. Semenov

1972-01-01

395

Tibial Lengthening: Extraarticular Calcaneotibial Screw to Prevent Ankle Equinus  

Microsoft Academic Search

Between 2003 and 2006, we used an extraarticular, cannulated, fully threaded posterior calcaneotibial screw to prevent equinus\\u000a contracture in 10 patients (four male and six female patients, 14 limbs) undergoing tibial lengthening with the intramedullary\\u000a skeletal kinetic distractor. Diagnoses were fibular hemimelia (two), mesomelic dwarfism (two), posteromedial bow (one), hemihypertrophy\\u000a (one), poliomyelitis (one), achondroplasia (one), posttraumatic limb-length discrepancy (one), and

Mohan V. Belthur; Dror Paley; Gaurav Jindal; Rolf D. Burghardt; Stacy C. Specht; John E. Herzenberg

2008-01-01

396

Steady-state simulation of screw liquid chillers  

Microsoft Academic Search

In order to predict the performance of screw liquid chillers in a wide range of configuration parameters and operating conditions, a steady-state simulation model is presented, which is suitable for non-economized and economized chillers. The model includes sub-models for key components, such as non-economized compressor, economized compressor, shell-and-tube condenser, expansion valve, and flooded evaporator. Sequential modular method and successive substitution

Long Fu; Guoliang Ding; Zujian Su; Guoquan Zhao

2002-01-01

397

Immediate loading of titanium plasma-sprayed screw-shaped implants in man: a clinical and histological report of two cases.  

PubMed

THIS STUDY REPORTS ON THE histological findings of two immediately loaded titanium plasma-sprayed (TPS) implants, retrieved for a fracture of the abutment and for psychological reasons, after 8 and 9 months of loading, respectively. The microscopical analysis showed that mature, compact, cortical bone was present around both implants, with the bone implant contact percentage about 60 to 70%. No fibrous tissue or gaps were present at the interface. No resorption was present in the peri-implant bone. On both implants a few osteoblasts were found positive at the interface for alkaline phosphatase (ALP); while no cells positive for acid phosphatase (ACP) were present. Immediate loading can, perhaps, be used in very selected cases of good bone quality, with implants that have certain macro- (screw shape) and micro-interlocks (titanium plasma-sprayed surface) characteristics. Good results have been reported also for non-TPS surface (e.g., machined surface). More data about different designs (e.g., cylinders) or coatings (e.g., hydroxyapatite) are needed before any firm conclusions about immediate loading can be reached. PMID:9203103

Piattelli, A; Paolantonio, M; Corigliano, M; Scarano, A

1997-06-01

398

Interlocking of chelae is a key factor for dominance hierarchy formation in crayfish.  

PubMed

We characterized the role of chelae during agonistic encounters of the crayfish Procambarus clarkii. Physical asymmetries in body length, body mass and chelae size were directly related to dominance hierarchy formation. More than 80% of winning crayfish had longer body and chelae lengths, and winners were usually heavier in body mass, even if their differences were less than 3% compared with losing opponents. In mismatched pairings, large crayfish with short chelae were beaten by small crayfish with large chelae. Three physical elements of body length, body mass and chelae length equally affected the outcome of agonistic bouts. Chelae restriction, in which chelae were tightly closed using rubber bands, affected the outcome of agonistic bouts between large and small crayfish. Before chelae restriction, large crayfish won in all pairings. Following chelae restriction for at least 30 days from the first encounters, the winning rate of large crayfish that were previous winners decreased significantly in the second encounters against the same opponents that were previous losers. The handicap of chelae restriction significantly prolonged the time to formation of the winner-loser relationship. Individual fights escalated during agonistic bouts between large crayfish with one chela restricted and small crayfish with intact chelae, whereas the number of fights increased but the duration of individual fights did not increase in large crayfish with both chelae restricted. Furthermore, when the chelae of both large and small crayfish were disabled, the dominance order was frequently not formed during 30 min of agonistic bouts. Preventing chelae from interlocking prevented escalation of agonistic bouts. We show that interlocking of chelae acted as a key factor for the formation of dominance hierarchy. PMID:22837457

Ueno, Ryusuke; Nagayama, Toshiki

2012-08-15

399

Fluid-structure interactions in micro-interlocked regions of the cement-bone interface.  

PubMed

Experimental tests and computational modelling were used to explore the fluid dynamics at the trabeculae-cement interlock regions found in the tibial component of total knee replacements. A cement-bone construct of the proximal tibia was created to simulate the immediate post-operative condition. Gap distributions along nine trabeculae-cement regions ranged from 0 to 50.4 ?m (mean = 12 ?m). Micro-motions ranged from 0.56 to 4.7 ?m with a 1 MPa compressive load to the cement. Fluid-structure analysis between the trabeculae and the cement used idealised models with parametric evaluation of loading direction, gap closing fraction (GCF), gap thickness, loading frequency and fluid viscosity. The highest fluid shear stresses (926 Pa) along the trabecular surface were found for conditions with very thin and large GCFs, much larger than reported physiological levels (~1-5 Pa). A second fluid-structure model was created with a provision for bone resorption using a constitutive model with resorption velocity proportional to fluid shear rate. A lower cut-off was used, below which bone resorption would not occur (50 s(-1)). Results showed that there was initially high shear rates (>1000 s(-1)) that diminished after initial trabecular resorption. Resorption continued in high shear rate regions, resulting in a final shape with bone left deep in the cement layer, and is consistent with morphology found in post-mortem retrievals. Small gaps between the trabecular surface and the cement in the immediate post-operative state produce fluid flow conditions that appear to be supra-physiologic; these may cause fluid-induced lysis of trabeculae in the micro-interlock regions. PMID:23480611

Mann, Kenneth A; Miller, Mark A

2014-01-01

400

Modelling of the Heating Process in a Thermal Screw  

NASA Astrophysics Data System (ADS)

The procedure of separating efficiently dry-stuff (proteins), fat, and water is an important process in the handling of waste products from industrial and commercial meat manufactures. One of the sub-processes in a separation facility is a thermal screw where the raw material (after proper mincing) is heated in order to melt fat, coagulate protein, and free water. This process is very energy consuming and the efficiency of the product is highly dependent on accurate temperature control of the process. A key quality parameter is the time that the product is maintained at temperatures within a certain threshold. A detailed mathematical model for the heating process in the thermal screw is developed and analysed. The model is formulated as a set of partial differential equations including the latent heat for the melting process of the fat and the boiling of water, respectively. The product is modelled by three components; water, fat and dry-stuff (bones and proteins). The melting of the fat component is captured as a plateau in the product temperature. The model effectively captures the product outlet temperature and the energy consumed. Depending on raw material composition, "soft" or "dry", the model outlines the heat injection and screw speeds necessary to obtain optimal output quality.

Zhang, Xuan; Veje, Christian T.; Lassen, Benny; Willatzen, Morten

2012-11-01

401

Sonography of tears of the distal biceps tendon.  

PubMed

OBJECTIVE. The objective of this study was to describe the sonographic appearance of tears of the distal biceps brachii tendon. CONCLUSION. Sonography can reveal complete and partial tears of the distal biceps tendon, thus providing an alternative technique to MR imaging. PMID:11000169

Miller, T T; Adler, R S

2000-10-01

402

Carcinoma in situ of the glans penis and distal urethra.  

PubMed

A case is presented of erythroplasia of Queyrat involving the distal glans penis surrounding the urethral meatus. Therapy with topical 5-fluorouracil was followed by recurrence within 14 months. Treatment by excision utilizing the Mohs technique demonstrated carcinoma in situ of over 5 cm of the distal urethra. Plastic surgical reconstruction produced a cosmetically and functionally normal penis. PMID:3700824

Bernstein, G; Forgaard, D M; Miller, J E

1986-05-01

403

Patient with Sjogren's Syndrome and Distal Renal Tubular  

Microsoft Academic Search

Distal urinary acidification abnormalities may arise from transepithelial voltage defects, permeability defects, or proton-secretory defects, but tests to de- termine the cellular mechanisms underlying secre- tory abnormalities have not previously been re- ported. A patient with Sjogren's syndrome and distal renal tubular acidosis due to a secretory defect is described, whose kidney biopsy was examined by fluorescent immunocytochemistry with an

Eric P. Cohen; Bahar Bastani; Miriam R. Cohen; Stuart Kolner; Philip Hemken; Stephen L. Gluck; P. Hemkin

1992-01-01

404

Radiographic study of distal radial physeal closure in thoroughbred horses.  

PubMed

Monthly radiography was performed to study distal radial physeal closure in ten male and ten female Thoroughbred horses. The height, thoracic circumference and metacarpus circumference were also measured. Distal radial physeal closure time was sooner in females than males, and took 701 +/- 37 and 748 +/- 55 days respectively. PMID:9335091

Vulcano, L C; Mamprim, M J; Muniz, L M; Moreira, A F; Luna, S P

1997-01-01

405

Distal Prosodic Context Affects Word Segmentation and Lexical Processing  

ERIC Educational Resources Information Center

Three experiments investigated the role of distal (i.e., nonlocal) prosody in word segmentation and lexical processing. In Experiment 1, prosodic characteristics of the initial five syllables of eight-syllable sequences were manipulated; the final portions of these sequences were lexically ambiguous (e.g., "note bookworm", "notebook worm"). Distal

Dilley, Laura C.; McAuley, J. Devin

2008-01-01

406

Architectural Properties of Distal Forelimb Muscles in Horses, Equus caballus  

E-print Network

were measured for nine distal forelimb muscles. Physiological cross-sectional area (PCSAArchitectural Properties of Distal Forelimb Muscles in Horses, Equus caballus Nicholas A.T. Brown,1. To accurately and noninvasively predict muscle and joint contact forces, a detailed model of musculoskeletal

Meyers, Ron

407

[Can steel screws be combined with titanium plates? Hard polishing technique and SEM in animal experiments].  

PubMed

To clarify the compatibility of steel and titanium, mandibular resections were performed on 24 sheep and the defects bridged with titanium plates and steel vs. titanium screws. 6, 12 and 24 weeks after osteosynthesis the implants were removed along with the surrounding bone segment and thin ground sections were prepared using the Donath method. The sections were then studied by light, fluorescence, polarization and scanning electron microscopy. The stability and easy removal are advantages of steel screws rendering them particularly suitable for temporary implantations. Moreover, they are 50-75% less expensive than titanium screws. After 3 and 6 months some minimum friction corrosion was observed at the screw/plate interface of steel screws. None of the specimens, however, showed signs of local tissue damage such as metallosis. From this it may be concluded that at least on a temporary basis a combination of steel screws and titanium plantes seems to be possible. PMID:1816958

Wächter, R; Stoll, P

1991-01-01

408

Distal Deposits from a Cometary Impact Event  

NASA Astrophysics Data System (ADS)

The Gulf of Carpentaria contains an impact ejecta layer that is circa 1500 BP in age. We have found the following components of the layer in five cores: 1) quench textured impact spherules composed of magnetite and hematite, 2) white chlorinated hydrocarbons, 3) high-Si, low- Fe, low-K glass, 4) vesiculated quartz, 6) native Fe, 7) CrFeNiCl spherules, 8) native Fe-Ni spherules and 9) fragments of high-Mg and high-Ca pyroxene. The latter three materials are possible impactor fragments. The former are candidates for impact ejecta. Some of the magnetite spherules occur in rocks bearing hematite- and silica-replaced marine microfossils. The chlorinated hydrocarbons contain quench textured magnetite spherules and have twice as much Cl as polyvinyl chloride. A small fraction of the magnetite spherules are ablated and have elongated tektite-like shapes. These materials occur in layers with stratigraphic thicknesses between 6 and 20 cm. Each layer has a strong peak in magnetic susceptibility that coincides with the maximum concentration of impact ejecta. We use the high magnetic susceptibility of hematite to model a minimum thickness of the impact ejecta layer before it was reworked by bioturbation. We find that the impact ejecta layer was originally at least 10s to 100s of micrometers thick. These thicknesses, along with the typical 100-1000 micrometer diameters of the larger ejecta fragments are consistent with a distal source crater. Using an online modeling program (http://impact.ese.ic.ac.uk/) we have ruled out tsunami transport for the ejecta layer. This is consistent with the lack of graded bedding of the layer. The grain size distribution of the ejecta layer is most consistent with a thin layer deposited from the air and reworked by bioturbation. We can match our modeled initial layer thicknesses and ejecta sizes by a cometary impactor that broke up and produced a 12 km crater at the location of our 12 km wide Tabban crater candidate. Our five cores contain a distal impact ejecta layer; possibly derived from the Tabban crater candidate between 540 and 712 km away. Now that we have constrained the thickness and mode of deposition of the impact ejecta layer, we have the tools to date it with more precision in the near future.

Abbott, D. H.; Rodriguez, L. E.; Breger, D.

2011-12-01

409

The use of distal rhynchokinesis by birds feeding in water.  

PubMed

The use of distal rhynchokinesis, which consists of the movement of the distal part of the upper jaw with respect to the cranium, is well documented in long-billed shorebirds (Scolopacidae), commonly being associated with the deep probing feeding method. However, the functional and evolutionary significance of distal rhynchokinesis and other cranial kinesis is unclear. We report for the first time the use and occurrence of distal rhynchokinesis in wild long-billed shorebirds feeding on small prey items suspended in water. We tested whether prey size in captive dunlins Calidris alpina influences the occurrence of distal rhynchokinesis during feeding and also whether its use affects foraging efficiency. We found that wild dunlin, curlew sandpiper Calidris ferruginea, sanderling Calidris alba and little stint Calidris minuta commonly use distal rhynchokinesis to strike, capture and transport small prey items. Prey size influenced the occurrence of distal rhynchokinesis during the transport phase, with this type of cranial kinesis being more frequently used with larger prey. The rhynchokinesis protraction angle (a measure of bill tip elevation) during prey strike and transport was affected by prey size, and bill gape was modulated through the use of distal rhynchokinesis in relation to prey size. Finally, the use of distal rhynchokinesis throughout intra-oral prey transport was related to shorter transport times, which improved foraging efficiency. We conclude that distal rhynchokinesis is a mechanism that could contribute to the flexible feeding behaviour of long-distance migratory shorebirds, enhancing small prey profitability and so improving foraging efficiency, and may have played a role in the evolutionary radiation of Scolopacidae (Charadrii). PMID:17951416

Estrella, Sora M; Masero, José A

2007-11-01

410

Long-term results of dorsally displaced distal radius fractures treated with the pi-plate: is hardware removal necessary?  

PubMed

The purpose of this study was to evaluate the outcome of patients treated with open reduction and internal fixation (ORIF) using dorsal plates and screws (AO/ASIF pi-plate) for dorsally displaced fractures of the distal radius. Although extensor tendon rupture is a recognized complication of all distal radial fractures, there appears to be an increased risk of this using dorsal plating. In addition, there is the added complication of extensor tendon irritation and dorsal wrist pain, which may necessitate plate removal. The low-profile pi-plates intended to overcome this problem have not done so, with quoted rates ranged from 19% to 55%.We treated 32 completely evaluated patients (13 men and 19 women) in our department between 2000 and 2004, with an average age of 46 years. They underwent ORIF of dorsally displaced fractures of the distal radius using the specially designed pi-plate. Bone graft was used in 18 patients who had significant metaphyseal defect. Clinical examination, plain radiographs, and functional assessments using the modified Mayo Wrist Score were performed at an average follow-up of 86 months (range, 56-115 months). Satisfactory reduction was achieved in all 32 fractures at the time of operative fixation with no instances of loss of fracture reduction during the study period. According to the Mayo Wrist Score, 23 patients (72%) had excellent or very good results, 7 (22%) had fair results, and 2 (6%) had poor results. Two cases (6.25%) of extensor tendon rupture were noted during the first postoperative month, and 2 other patients showed progressive weakness of index finger extension 6 months postoperatively. The remaining 28 patients had no soft tissue problems. PMID:21717990

Tyllianakis, Minos E; Panagopoulos, Andreas M; Saridis, Alkis

2011-07-01

411

Investigation of melting in a modular intermeshing co-rotating twin screw extruder  

Microsoft Academic Search

Since the first patent regarding the co-rotating twin screw extruder was published in 1869, the co-rotating twin screw extruder has evolved into a high performance extruder, having self wiping capability, modular screw configuration, starved feed zone, kneading disc block elements, and special mixing devices. For this device, flow studies began in the mid 1960's but melting studies started in the

Ho-Chul Jung

2004-01-01

412

The effect of dynamic behavior on surface roughness of ball screw under the grinding force  

Microsoft Academic Search

The dynamic behavior of a ball screw under a moving grinding force and the resulting ball screw surface roughness are investigated.\\u000a The system includes a ball screw, a headstock, a tailstock, a steady rest, a grinding wheel, and a wheel head. Equations of\\u000a motion of the system are derived through Lagrangian approach combined with global assumed mode method in this

Ting-Nung Shiau; Kuan-Hung Chen; Fu-Ching Wang; Chui-Te Chio; Wei-Chun Hsu

2011-01-01

413

Clinical degradation and biocompatibility of different bioabsorbable interference screws: A report of six cases  

Microsoft Academic Search

The clinical biocompatibility and degradation of bioabsorbable interference screws of different polymer composition is described in this report for six patients who underwent repeat arthroscopy after anterior cruciate ligament (ACL) reconstruction. Bioabsorbable interference screws were used for bone plug fixation of bone—patellar tendon—bone (BPTB) autografts. Poly (L-lactide) (PLLA) interference screws were used in one case, poly (D,L-lactide-co-glycolide) (PDLLA-co-PGA) in two

Andreas C. Stähelin; Andreas Weiler; Hansjörg Rüfenacht; Reinhard Hoffmann; Alfred Geissmann; Richard Feinstein

1997-01-01

414

Magnetic resonance imaging appearance of anterior cruciate ligament reconstruction using Calaxo screws  

Microsoft Academic Search

Bioabsorbable interference screws are commonly used to secure the graft during anterior cruciate ligament (ACL) reconstruction,\\u000a in part because they result in less image degradation on subsequent magnetic resonance imaging (MRI). However, some bioabsorbable\\u000a screws are associated with abnormalities on MRI examination not reported with metallic interference screws. We describe a\\u000a finding on knee MRI examination after ACL reconstruction using

Troy F. Storey; William J. Montgomery; Charles H. Bush; Michael Moser

2011-01-01

415

[Computerized tomography monitoring of the position of pedicle screws in scoliosis surgery].  

PubMed

With the increasing use of pedicle screws in instrumented spine surgery the neurological risk must be evaluated critically. Studies, which evaluated the accuracy of pedicle screw placement in scoliosis surgery, have not been published up to date to our knowledge. In 25 consecutive patients with idiopathic scoliosis, who underwent posterior instrumented curve correction and stabilization, the accuracy of pedicle screw placement was evaluated using axial computed tomography. There was a total of 178 screws between T5 and L4. The preoperative Cobb angle of the curve averaged 60.7 degrees, the mean rotation of the instrumented vertebrae was 19.1 degrees according to Perdriolle. 145 pedicle screws (81.5%) were placed correctly within the pedicles, of which 4 screws (4.5%) penetrated the anterior aspect of the vertebral body with a mean of 0.9 mm. 22 screws (12.4%) showed lateral penetration of the pedicle with a mean of 1.9 mm, of which one screw was placed completely lateral of the pedicle. 8 screws (4.5%) penetrated the medial wall of the pedicle by 1.3 mm on average. One screw each penetrated the cranial and caudal border of the pedicle. Statistical analysis did not reveal any significant relationships between pedicle screw misplacement and grade of vertebral rotation or site of instrumentation. Neurological complications were not noted in any of the cases. In our mind the risk of pedicle screw threaded curve correction and fusion in scoliosis surgery in the hands of an experienced spine surgeon is calculated acceptably low. PMID:9027118

Halm, H; Liljeqvist, U; Link, T; Jerosch, J; Winkelmann, W

1996-01-01

416

Hollow Mill for Extraction of Stripped Titanium Screws: An Easy, Quick, and Safe Technique  

PubMed Central

Removal of jammed titanium screws can be difficult due to the problem of stripping of the hexagonal heads of the screws. We present a technique of extraction of stripped screws with the use of a standard 4.5 mm stainless steel hollow mill in a patient of peri-implant fracture of the radius fixed with a titanium locking plate 2 years back. The technique is quick, safe, and cost effective. PMID:25013544

Gupta, Ravi; Singh, Harpreet; Singh, Amit; Garg, Sudhir

2014-01-01

417

Thoracic Aortic Stent-Graft Placement for Safe Removal of a Malpositioned Pedicle Screw  

SciTech Connect

We describe a case of percutaneous placement of a thoracic aortic stent-graft for safe removal of a malpositioned pedicle screw in a 52-year-old man. The patient had undergone posterior thoracic spinal instrumentation for pyogenic spondylitis and spinal deformity 8 months previously. Follow-up CT images showed a malpositioned pedicle screw which was abutting the thoracic aorta at the T5 level. After percutaneous stent-graft placement, the malpositioned pedicle screw was safely and successfully removed.

Hu Hongtao [Henan Tumor Hospital, Department of Radiology (China); Shin, Ji Hoon, E-mail: jhshin@amc.seoul.kr; Hwang, Jae-Yeon; Cho, Young Jun; Ko, Gi-Young; Yoon, Hyun-Ki [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology and Research Institute of Radiology (Korea, Republic of)

2010-10-15

418

Semisolid processing of engineering alloys by a twin-screw rheomoulding process  

Microsoft Academic Search

Based on the extensive experience in injection moulding of polymeric materials, a twin-screw rheomoulding process has been developed in our laboratory for near net-shape production of engineering components. The rheomoulding equipment consists of a liquid metal feeder, a twin-screw extruder with closely intermeshing, self-wiping and co-rotating screws, a shot assembly and a central control unit. The fluid flow in the

S Ji; Z Fan; Mike J Bevis

2001-01-01

419

Effect of bone mineral density and amorphous diamond coatings on insertion torque of bone screws  

Microsoft Academic Search

In this study, the potential of high-quality amorphous diamond (AD) coatings in reducing the torque and failures of bone screws was studied. Torque values were recorded for 32 stainless steel screws, 2.7 or 3.5mm in diameter and 60mm in length. Half of the screw sets were coated with the AD coating before installing in predrilled holes of human cadaveric femoral

Arto Koistinen; Seppo S. Santavirta; Heikki Kröger; Reijo Lappalainen

2005-01-01

420

Use of a locking reconstruction bone plate\\/screw system for mandibular surgery  

Microsoft Academic Search

Purpose: This study examined the use of a locking reconstruction bone plate\\/screw system for use in mandibular surgery.Patients and Methods: All patients treated with a locking reconstruction bone plate\\/screw system for fractures of the mandible or continuity defects in an 18-month period were prospectively studied. Ease of use of the locking plate\\/screw system, characteristics of the fractures\\/defects, and complications were

Alan S Herford; Edward Ellis

1998-01-01

421

Review article: problematic proctitis and distal colitis.  

PubMed

About two-thirds of patients with ulcerative colitis have an inflammatory involvement distal to the splenic flexure, and therefore may be effectively treated with topical treatment, allowing the delivery of the active drug directly to the site of inflammation and limiting systemic absorption and potential side-effects. Topical aminosalicylate therapy is the most effective approach, and most patients will benefit hugely, provided that the formulation reaches the upper extent of the disease. Therefore, the choice of topical preparation should be based on the proximal extent of the disease and on patient preference. Oral aminosalicylates are less effective than topical therapies; however, a combination of oral and topical aminosalicylates can be successful in refractory patients. Alternatives to aminosalicylates are the new glucocorticoids, budesonide and beclometasone dipropionate, either as enemas or oral formulations (only beclometasone dipropionate). A combination of oral or rectal new glucocorticoids with rectal aminosalicylates should be considered in patients refractory to either approach. When these measures fail, treatment with oral glucocorticoids is necessary. An intensive intravenous steroid regimen is also helpful for patients refractory to oral steroids. Alternative treatments include short-chain fatty acid enemas, nicotine enemas and patches, acetarsol suppositories, ciclosporin enemas and epidermal growth factor enemas. Several factors potentially having a negative impact on therapeutic response include concurrent enteric pathogens, coexistent irritable bowel syndrome, patient nonadherence to therapy, inadequate dosing and duration of therapy, and proximal progression of the disease. Surgical colectomy may be required in those rare patients refractory or intolerant to pharmacotherapy. PMID:15352902

Gionchetti, P; Rizzello, F; Morselli, C; Campieri, M

2004-10-01

422

CALAXO® Osteoconductive Interference Screw: The Value of Post-Market Surveillance  

PubMed Central

The CALAXO® osteoconductive interference screw was recalled in August 2007 due to reports of increased numbers of postoperative complications associated with screw swelling and prominence leading to the need for surgical debridement. This study reviews complications associated with CALAXO® screw use in a consecutive cohort of patients undergoing anterior cruciate ligament reconstruction surgery by the senior author at our institution. Over a 12 month period, 226 CALAXO® interference screws, either of 20mm length or 25mm length, were implanted in 112 patients, and postoperative complications were noted. The 25mm tibial screw was over 5 times (RR 5.2, 95% CI 1.8 to 15.3) more likely to be prominent than the 20mm screw (p-value = 0.002). Four surgical debridements were required in the 25mm tibial screw group; none were required in the 20mm group. We hypothesize that the inability to bury the longer screw length into the bone tunnel is associated with postoperative complications associated with the CALAXO® screw. PMID:20727309

Cox, Charles L.; Homlar, Kelly C.; Carey, James L.; Spindler, Kurt P.

2013-01-01

423

Development and Testing of a Screw Compressor Supermarket Refrigeration System: Phase II, Final Report.  

SciTech Connect

A laboratory prototype screw compressor refrigeration system was designed, fabricated and tested under various evaporator and ambient conditions. The design is based on a Dunham-Bush vertical hermetic screw compressor and other standard refrigeration components. Results indicate that a screw compressor rack with vapor injection can increase the thermodynamic efficiency of low temperature refrigeration in supermarkets by 20 to 28% compared to multiple reciprocating compressor racks. The payback period of the screw compressor refrigeration system relative to multiple reciprocating compressor systems is 1.1 to 1.5 years and the net present value savings range from 15 to 22 thousand dollars.

Borhanian, H. Hamed; Toscano, William M.; Lee, Kang P.

1987-02-01

424

A mechanical evaluation of pre-tapped and self-tapped screws in small bones.  

PubMed

The purpose of this study was to compare the holding powers of 2.7 mm pre-tapped and self-tapped screws placed closely together and tightened in small bones. Pairs of metatarsals were collected from healthy, skeletally mature Greyhounds and part of a 2.7 mm dynamic compression plate was fixed to the dorsal surface of each bone using three 2.7 mm screws. Identical screws were used throughout but only one of each pair of bones had threads pre-cut using a tap prior to insertion. All of the screws were tightened before the constructs were mounted in a materials testing machine and the centrally placed screw was loaded incrementally until failure. Load-deformation curves were plotted and yield point, ultimate load to failure, stiffness and energy prior to yield point were measured. Mean values were recorded for each parameter and Student's T-test was used to test the null hypothesis that there is no difference in holding power between pre-tapped and self-tapped screws. Significant mechanical differences were not found between pre-tapped and self-tapped screws placed closely together and tightened into small bones. Self-tapped screws can be considered for use in small animal surgery even when multiple screws are to be placed closely together in relatively small pieces of bone. PMID:18038003

Bell, J C; Ness, M G

2007-01-01

425

Accuracy of Free Hand Pedicle Screw Installation in the Thoracic and Lumbar Spine by a Young Surgeon: An Analysis of the First Consecutive 306 Screws Using Computed Tomography  

PubMed Central

Study Design A retrospective cross-sectional study. Purpose The purpose of this study is to evaluate the accuracy and safety of free-hand pedicle screw insertion performed by a young surgeon. Overview of Literature Few articles exist regarding the safety of the free-hand technique without inspection by an experienced spine surgeon. Methods The index surgeon has performed spinal surgery for 2 years by himself. He performed fluoroscopy-assisted pedicle screw installation for his first year. Since then, he has used the free-hand technique. We retrospectively reviewed the records of all consecutive patients undergoing pedicle screw installation using the free-hand technique without fluoroscopy in the thoracic or lumbar spine by the index surgeon. Incidence and extent of cortical breach by misplaced pedicle screw was determined by a review of postoperative computed tomography (CT) images. Results A total of 36 patients received 306 free-hand placed pedicle screws in the thoracic or lumbar spine. A total of 12 screws (3.9%) were identified as breaching the pedicle in 9 patients. Upper thoracic spine was the most frequent location of screw breach (10.8%). Lateral breach (2.3%) was more frequent than any other direction. Screw breach on the right side (9 patients) was more common than that on the left side (3 patients) (p<0.01). Conclusions An analysis by CT scan shows that young spine surgeons who have trained under the supervision of an experienced surgeon can safely place free-hand pedicle screws with an acceptable breach rate through repetitive confirmatory steps. PMID:24967036

Lee, Chang-Hyun; Kim, Yongjung J; Kim, Ki-Jeong; Jahng, Tae-Ahn; Kim, Hyun-Jib

2014-01-01

426

Resection Interposition Arthroplasty for Failed Distal Ulna Resections  

PubMed Central

The major complications of distal ulna resection, the Darrach procedure, are radioulnar impingement and instability. High failure rates have been reported despite published modifications of the Darrach procedure. Several surgical techniques have been developed to treat this difficult problem and to mitigate the symptoms associated with painful convergence and impingement. No technique has demonstrated clinical superiority. Recently, implant arthroplasty of the distal ulna has been endorsed as an option for the management of the symptomatic patient with a failed distal ulna resection. However, there are concerns for implant longevity, especially in young, active adults. Resection interposition arthroplasty relies on interposition of an Achilles tendon allograft between the distal radius and the resected distal ulna. Although this technique does not restore normal mechanics of the distal radioulnar joint, it can prevent painful convergence of the radius on the ulna. Achilles allograft interposition arthroplasty is a safe and highly effective alternative for failed distal ulna resections, especially for young, active patients, in whom an implant or alternative procedure may not be appropriate. PMID:24436784

Papatheodorou, Loukia K.; Rubright, James H.; Kokkalis, Zinon T.; Sotereanos, Dean G.

2013-01-01

427

Laparoscopically assisted distal gastrectomy for early gastric cancer  

Microsoft Academic Search

Background  The purpose of this study was to compare clinical outcomes between laparoscopically assisted and open distal gastrectomy for\\u000a early gastric cancer.\\u000a \\u000a \\u000a \\u000a Methods  The records of 21 patients who underwent laparoscopically assisted distal gastrectomy (LG) for preoperative diagnosis of intramucosal\\u000a gastric carcinoma between January 1996 and August 1998 were reviewed and compared with those of 31 open distal gastrectomy\\u000a patients during the

S. Shimizu; A. Uchiyama; K. Mizumoto; T. Morisaki; K. Nakamura; H. Shimura; M. Tanaka

2000-01-01

428

Increased Interfacial Strength at Microscale Silicon-Polymer Interface by Nanowires Assisted Micro-Sandglass Shaped Interlocks  

NASA Astrophysics Data System (ADS)

We present an interfacial strengthening technique for microsystem packaging, particularly at the interface of stiff and soft materials. Micro-sandglass shaped interlocks (MSIs) were first demonstrated at the interface of silicon and Nafion® and exhibited a strong interfacial strength of 1 MPa; moreover, nanowired micro-sandglass shaped interlocks (NW-MSIs) were employed to further enhance the interfacial strength, and a value of 3.4 MPa was achieved. Theoretical predictions indicated the enhancement factors include the gap shrinkage ratio, overhanging angle, contact area, and friction coefficient. The geometry of the MSIs is strongly dependent on the KOH etching time while the friction can be enhanced by the employment of nanowires on the sidewalls of MSIs. Based on the NW-MSIs, the highest interfacial strength obtained is 3.4-fold higher than that of MSIs without nanowires.

Peng, Hsien-Chih; Khoo, Hwa Seng; Tseng, Fan-Gang

2012-02-01

429

Sunlight-induced covalent marriage of two triply interlocked pd6 cages and their facile thermal separation.  

PubMed

A template-free triply interlocked Pd6 cage (2) was synthesized by two-component self-assembly of cis-blocked 90° acceptor cis-(tmen)Pd(NO3)2 (M) and 1,3,5-tris((E)-2-(pyridin-3-yl)vinyl)benzene (L). Assembly 2 was characterized by (1)H NMR and ESI-MS, and the structure was confirmed by X-ray crystallography, which revealed a parallel conformation of the olefin double bonds belonging to the adjacent cages in the solid state at a distance of 3.656 Å, thereby indicating the feasibility of [2+2] photochemical reaction. Two adjacent interlocked cages were covalently married together by intermolecular [2+2] cycloaddition in a single crystal-to-single crystal fashion upon exposure to sunlight/UV irradiation. Most surprisingly, the covalently married pair was easily separated thermally in aqueous medium under mild reaction conditions. PMID:25423470

Samanta, Dipak; Mukherjee, Partha Sarathi

2014-12-10

430

Metal-organic and supramolecular architectures based on mechanically interlocked molecules  

NASA Astrophysics Data System (ADS)

The focus of this work is on mechanically interlocked molecules (MIMs), which have unusual physicochemical and mechanical properties with potential applications in nano-scale/molecular devices and high strength materials. Rotaxanes, for example, consist of an axle-like molecule threaded through a wheel-like molecule, with bulky groups at the two ends of the axle preventing the wheel from dissociating. The position of the wheel along the axle can be switched in a controllable and reversible manner by applying external stimuli, a feature that might lead to the next generation of computers. Molecularly woven materials (MWMs), another example of molecules with mechanically interlocked features, are predicted to be unprecedentedly strong while being lightweight and flexible. With the ultimate goal of achieving control over the functioning of molecular devices in the solid state, a variety of pseudorotaxane building blocks were prepared and characterized, including a novel, rare blue-colored motif. The temperature-dependent assembly/disassembly of pseudorotaxanes was exploited for the construction of single-wavelength colorimetric temperature sensors over a 100 °C window. Pseudorotaxanes based on aromatic crown ether wheels and disubstituted 4,4'-bipyridinium axles were converted into rotaxanes upon binding to metal complexes (zinc, cadmium, mercury, copper, cobalt), and the formation of ordered crystalline arrays was studied in the solid state. The columnar organization of pseudorotaxanes by Hg2X6 2-- complexes (X = Cl, Br, I), leading to unprecedented dichroic (blue/red) rotaxane crystals, was demonstrated for the first time. From the crystal structures studied it became apparent that negatively charged metal complexes are needed for successful assembly with the positively charged pseudorotaxane units. To be able to use the more common, positively charged metal ions for rotaxane framework construction, neutral and negatively charged pseudorotaxanes were synthesized, by attaching anionic substituents (carboxylates, sulfonates) to either the wheel or the axle component. It was found that pseudorotaxane formation also enabled resolution of two sulfonated crown ether isomers, which were inseparable by conventional methods. Organic ligands for MWM precursors were designed and synthesized according to multi-step schemes. Helical metal-complexes based on these ligands were prepared and characterized. Chromatography, Nuclear Magnetic Resonance and UV-Visible spectroscopy, Mass spectrometry, Electrochemistry, Thermogravimetric Analysis and X-ray crystallography were used in identification, purification and characterization of the compounds involved.

Fernando, Isurika Rosini

431

Morphological character of cervical spine for anterior transpedicular screw fixation  

PubMed Central

Background: Anterior cervical interbody grafts/cages combined with a plate were frequently used in multilevel discectomies/corpectomies. In order to avoid additional posterior stabilization in patients who undergo anterior reconstructive surgery, an anterior cervical transpedicular screw fixation, which offers higher stability is desirable. We investigated in this study the anatomical (morphologic) characters for cervical anterior transpedicular screw fixation. Materials and Methods: Left pedicle parameters were measured on computed tomography (CT) images based on 36 cervical spine CT scans from healthy subjects. The parameters included outer pedicle width (Distance from lateral to medial pedicle surface in the coronal plane), outer pedicle height (OPH) (Distance from upper to lower pedicle surface in the sagittal plane), maximal pedicle axis length (MPAL), distance transverse insertion point (DIP), distance of the insertion point to the upper end plate (DIUP), pedicle sagittal transverse angle (PSTA) and pedicle transverse angle (PTA) at C3 to C7. Results: The values of outer pedicle width and MPAL in males were larger than in females from C3 to C7. The OPH in males was larger than in females at C3 to C6, but there was no difference at C7. The DIP and PTA were significantly greater in males than in females at C3, but there was no difference in the angle at C4-7. The PSTA was not statistically different between genders at C3, 4, 7, but this value in males was larger than females at C5, 6. The DIUP was significantly greater in males at C3, 4, 6, 7 but was non significant at C5. Conclusions: The placement of cervical anterior transpedicular screws should be individualized for each patient and based on a detailed preoperative planning. PMID:24379459

Zhou, Rong-Ping; Jiang, Jian; Zhan, Zi-Chun; Zhou, Yang; Liu, Zhi-Li; Yin, Qing-Shui

2013-01-01

432

Interference screw fixation of cervical grafts. A combined in vitro biomechanical and in vivo animal study.  

PubMed

The dislodgement of an anterior bone graft in the cervical spine is a frequent complication of attempted fusion following discectomy or corpectomy. It has been hypothesized that fixation augmented with interference screws may increase the pullout strength of the construct and decrease the rate of these complications. In vitro mechanical tests and in vivo sheep studies were conducted to compare interference screw fixation methods for enhancing the fixation between the bone graft and the adjacent vertebra. Using human cadaver cervical spines, the anterior pullout strengths of cervical bone grafts were compared using fixation with and without the addition of interference screws for the in vitro mechanical testing. The mean pullout forces for a Smith-Robinson type bone graft alone was 58.1 N (SD 11.4 N); for the graft augmented with two 3.5 mm cancellous bone screws, 153.9 N (58.9 N); and for the graft with four 3.5 mm screws, 217.1 N (SD 69.9 N). The pullout strengths of the two- and four-3.5 mm screw constructs were significantly greater than the strength of the graft alone (P < 0.05). Similarly placed 2.7 mm cortical screws of the same length provided increased pullout strength (123.7 N 38.6 N and 142.5 N 38.2 N for two- and four-screw constructs, respectively); however, in comparison to the graft alone, these differences were not statistically significant. For both screw types, the four-screw fixations were stronger than the two-screw fixations, although these differences were not statistically significant. For the in vivo portion of the study, a single-level anterior cervical discectomy and fusion were performed on 20 sheep.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8367782

Vazquez-Seoane, P; Yoo, J; Zou, D; Fay, L A; Fredrickson, B E; Handal, J C; Yuan, H A; Edwards, W T

1993-06-15

433

Evaluation of mechanical properties of three different screws for rapid maxillary expansion  

PubMed Central

Background The aim of this in vitro study was the evaluation of the mechanical properties the screws for rapid maxillary expansion (RME). Methods Three commercially available screws for RME were tested: Leone A2620; Dentaurum Hyrax; Forestadent Palatal Split Screw. All expansion screws were 10 mm in size. For the evaluation of mechanical properties, the screws for RME were adjusted using the same maxillary dental model. An Instron 3365 testing machine with a load cell of 5 kN recorded the forces released by the screws at different amounts of activation (1, 5, 10, 15 and 20 quarters of a turn). Each type of screw was tested 10 times. Comparisons between the forces released by the different types of screws at different amounts of activation were carried out by means of analysis of Kruskal-Wallis test with post-hoc test di Tukey (P?screws about 16 kg. Both the A2620 and Hyrax expanders showed significantly greater amounts of forces at all the different amounts of activations with respect to the Palatal Split screw. Conclusions All tested devices showed the capability of developing expansion forces (16-20 kg) adequate for RME. The A2620 and Hyrax expanders showed a greater level of rigidity than the Palatal Split screw. PMID:24330632

2013-01-01

434

Biomechanical impact of C2 pedicle screw length in an atlantoaxial fusion construct  

PubMed Central

Background: Posterior, atlantoaxial (AA) fusions of the cervical spine may include either standard (26 mm) or short (16 mm) C2 pedicle screws. This manuscript focused on an in vitro biomechanical comparison of standard versus short C2 pedicle screws to perform posterior C1-C2 AA fusions. Methods: Twelve human cadaveric spines underwent C1 lateral mass screw and standard C2 pedicle screw (n = 6) versus short C2 pedicle screw (n = 6) fixation. Six additional controls were not instrumented. The peak torque, peak rotational interval, and peak stiffness of the constructs were analyzed to failure levels. Results: The peak torque to construct failure was not statistically significantly different among the control spine (12.2 Nm), short pedicle fixation (15.5 Nm), or the standard pedicle fixation (11.6 Nm), P = 0.79. While the angle at the peak rotation statistically significantly differed between the control specimens (47.7° of relative motion) and the overall instrumented specimens (P < 0.001), the 20.7° of relative rotation in the short C2 pedicle screw specimens was not statistically significantly higher than the 13.7° of relative rotation in the standard C2 pedicle screw specimens (P = 0.39). Similarly, although the average stiffness was statistically significantly lower in control group (0.026 Nm/degree) versus the overall instrumented specimens (P = 0.001), the standard C2 pedicle screws (2.54 Nm/degree) did not differ from the short C2 pedicle screws Conclusions: Both standard and short C2 pedicle screws allow for equally rigid fixation of C1 lateral mass-C2 AA fusions. Usage of a short C2 pedicle screw may be an acceptable method of stabilization in carefully selected patient populations. PMID:25289157

Xu, Risheng; Bydon, Mohamad; Macki, Mohamad; Belkoff, Stephen M.; Langdale, Evan R.; McGovern, Kelly; Wolinsky, Jean-Paul; Gokalsan, Ziya L.; Bydon, Ali

2014-01-01

435

Modeling and control of a twin-screw extruder  

E-print Network

-rotating and co-rotating twin screws (Martelli, 1983). 10 2 A convex function of one variable (Reklaitis et al. , 1983). 19 3 Contour plot for a single quality attribute. 29 4 Contour plot for two quality attributes. 30 5 Contour plot i'or three quality... solution results using difi'erent starting points. If multiple solutions occur, it implies that there are local optima; however, if f(x, I I I )tf(x&)+0-X)f( f(xJ I I I I I fD x, s(I-)t)xj I X, Xx, +(I-X)x Figure 2. A convex function of one...

Richburg, Leslie Leitzy

2012-06-07

436

New Tools for Computational Geometry and Rejuvenation of Screw Theory  

NASA Astrophysics Data System (ADS)

Conformal Geometric Algebraic (CGA) provides ideal mathematical tools for construction, analysis, and integration of classical Euclidean, Inversive & Projective Geometries, with practical applications to computer science, engineering, and physics. This paper is a comprehensive introduction to a CGA tool kit. Synthetic statements in classical geometry translate directly to coordinate-free algebraic forms. Invariant and covariant methods are coordinated by conformal splits, which are readily related to the literature using methods of matrix algebra, biquaternions, and screw theory. Designs for a complete system of powerful tools for the mechanics of linked rigid bodies are presented.

Hestenes, David

437

FEM simulation of 3D angle-interlock woven composite under ballistic impact from unit cell approach  

Microsoft Academic Search

Ballistic impact damage of 3D angle-interlock woven composite (3DAWC) under a hemispherical-cylindrical steel projectile has been investigated in experimental and finite element method (FEM) based on a unit cell model. In the unit cell model, the composite was simplified into a combination of resins, weft yarns and warp yarns to define the stiffness matrix and failure evolution of the material.

Zhijiang Li; Baozhong Sun; Bohong Gu

2010-01-01

438

Definition & means of maintaining the process vacuum liquid detection interlock systems portion of the PFP safety envelope  

Microsoft Academic Search

The purpose of this document is to record the technical evaluation of the Technical Safety Requirements described in the Plutonium Finishing Plant (PFP) Safety Technical Requirements, HNF-SD-CP-OSR-010, Rev. 1, Section 3.1.1, ''Criticality Prevention System.'' This document also defines the Safety Envelope (SE) for the liquid detection interlock system in the Process Vacuum System. The SE is derived from information in

2003-01-01

439

Definition and means of maintaining the process vacuum liquid detection interlock systems portion of the PFP safety envelope  

Microsoft Academic Search

The purpose of this document is to record the technical evaluation of the Technical Safety Requirements described in the Plutonium Finishing Plant (PFP) Safety Technical Requirements, HNF-SD-CP-OSR-010, Rev. 1, Section 3.1.1, ''Criticality Prevention System.'' This document also defines the Safety Envelope (SE) for the liquid detection interlock system in the Process Vacuum System. The SE is derived from information in

2003-01-01

440

Distal Renal Tubular Acidosis in Infancy: A Bicarbonate Wasting State  

ERIC Educational Resources Information Center

Studied were three unrelated infants with distal renal tubular acidosis (a condition characterized by an inability to acidify the urine to minimal pH levels resulting in the loss of bicarbonates). (DB)

Rodriguez-Soriano, J.; And Others

1975-01-01

441

Distal Triceps Knotless Anatomic Footprint Repair: A New Technique  

PubMed Central

Distal triceps rupture is a rare injury causing significant disability. Several techniques for treating distal triceps ruptures have been described using bone tunnels or suture anchors. More recent techniques have focused on re-creating the anatomic footprint of the distal triceps tendon. However, the increasing numbers of anchors used increase the risk to the articular surface, and all earlier techniques require knot tying and bulky knots beneath the thin posterior elbow soft-tissue envelope. We describe a technique combining the use of bone tunnels and a single suture anchor to create a knotless anatomic footprint repair of the distal triceps. By using this technique, we are able to create a tension-band construct that self-reinforces the anatomic repair and is very low profile while significantly decreasing risk to the articular surface. PMID:25473618

Paci, James M.; Clark, Jonathan; Rizzi, Angelo

2014-01-01

442

Distal clavicle osteolysis following fixation with a synthetic ligament  

PubMed Central

We present a case of distal clavicle osteolysis following treatment of a chronic acromioclavicular joint dislocation with a synthetic ligament. The relevant literature is reviewed and discussed. PMID:22223960

Dearden, Paul M. C.; Ferran, Nicholas A.; Morris, Emyr W.

2011-01-01

443

Interlocking Detachable Platinum Coils, A Controlled Embolization Device: Early Clinical Experience  

SciTech Connect

Purpose: To present the early clinical experience of a new mechanically controlled-release embolization device<+>-<+>the interlocking detachable coil (IDC)-in complex embolization outside the head. Methods: IDCs were used only when conventional embolization techniques were considered too risky or unsafe. The coils consist of unfibered coiled platinum (0.012 inch), mechanically connected to a pusher wire and deployed through a Tracker 18 catheter. IDCs come in a range of diameters (2<+>-<+>8 mm) and lengths (1<+>-<+>30 cm). Results: A total of 87 IDCs were used for 27 procedures in 25 patients (mean 14.5 years) to occlude 31 arteries or vascular lesions. Control of the coil and its release were satisfactory and all coils were fully retrievable up to the point of deployment. Two IDC coils embolized inadvertently but were retrieved; there were no other complications. The IDC coils could not be satisfactorily placed in one high-flow arteriovenous (AV) fistula, and in another case there was a small residual fistula. Occlusion was produced in 29 of 31 lesions. Ancillary techniques were needed in 5 patients: temporary balloon occlusion in 2 and 0.038-inch coils in 3. Conclusion: The IDC coil is an effective device that allows controlled embolization to be performed, especially in aneurysms and in high-flow AV fistulas in children.

Reidy, John F. [Department of Radiology, 2nd Floor, Guy's Tower, Guy's Hospital, St. Thomas Street, London, SE1 9RT (United Kingdom); Qureshi, Shakeel A. [Pediatric Cardiology Department, 11th Floor, Guy's Tower, Guy's Hospital, St. Thomas Street, London, SE1 9RT (United Kingdom)

1996-03-15

444

Segmented instrumentation tube including a locking sleeve for interlocking the segments of the instrumentation tube  

DOEpatents

Segmented instrumentation tube including a locking sleeve for interlocking the segments of the instrumentation tube, so that the threaded ends of the instrumentation tube do not unthread when subjected to vibration, such an instrumentation tube being suitable for use in a nuclear reactor pressure vessel. The instrumentation tube has a first member having a threaded end portion that has a plurality of first holes circumferentially around the outside surface thereof. The instrumentation tube also has a second member having a threaded end portion that has a plurality of second holes circumferentially around the outside surface thereof. The threads of the second member are caused to threadably engage the threads of the first member for defining a threaded joint therebetween. A sleeve having an inside surface surrounds the end portion of the first member and the end portion of the second member and thus surrounds the threaded joint. The sleeve includes a plurality of first projections and second projections that outwardly extend from the inside surface to engage the first holes and the second holes, respectively. The outside surface of the sleeve is crimped or swaged at the locations of the first projections and second projections such that the first projections and the second projections engage their respective holes. In this manner, independent rotation of the first member with respect to the second member is prevented, so that the instrumentation tube will not unthread at its threaded joint.

Obermeyer, Franklin D. (Pensacola, FL)

1993-01-01

445

Segmented instrumentation tube including a locking sleeve for interlocking the segments of the instrumentation tube  

DOEpatents

Segmented instrumentation tube including a locking sleeve for interlocking the segments of the instrumentation tube, so that the threaded ends of the instrumentation tube do not unthread when subjected to vibration, such an instrumentation tube being suitable for use in a nuclear reactor pressure vessel. The instrumentation tube has a first member having a threaded end portion that has a plurality of first holes circumferentially around the outside surface thereof. The instrumentation tube also has a second member having a threaded end portion that has a plurality of second holes circumferentially around the outside surface thereof. The threads of the second member are caused to threadably engage the threads of the first member for defining a threaded joint there between. A sleeve having an inside surface surrounds the end portion of the first member and the end portion of the second member and thus surrounds the threaded joint. The sleeve includes a plurality of first projections and second projections that outwardly extend from the inside surface to engage the first holes and the second holes, respectively. The outside surface of the sleeve is crimped or swaged at the locations of the first projections and second projections such that the first projections and the second projections engage their respective holes. In this manner, independent rotation of the first member with respect to the second member is prevented, so that the instrumentation tube will not unthread at its threaded joint. 10 figures.

Obermeyer, F.D.

1993-11-16

446

Supervision Software for the Integration of the Beam Interlock System with the CERN Accelerator Complex  

E-print Network

The Accelerator complex at the European Organisation for Nuclear Research (CERN) is composed of many systems which are required to function in a valid state to ensure safe beam operation. One key component of machine protection, the Beam Interlock System (BIS), was designed to interface critical systems around the accelerator chain, provide fast and reliable transmission of beam dump requests and trigger beam extraction in case of malfunctioning of equipment systems or beam losses. Numerous upgrades of accelerator and controls components during the Long Shutdown 1 (LS1) are followed by subsequent software updates that need to be thoroughly validated before the restart of beam operation in 2015. In parallel, the ongoing deployments of the BIS hardware in the PS booster (PSB) and the future LINAC4 give rise to new requirements for the related controls and monitoring software due to their fast cycle times. This paper describes the current status and ongoing work as well as the long-term vision for the integratio...

Audrain, M; Dragu, M; Fuchsberger, K; Garnier, JC; Gorzawski, AA; Koza, M; Krol, K; Moscatelli, A; Puccio, B; Stamos, K; Zerlauth, M

2014-01-01

447

Laboratory analysis of the infiltration capacity of interlocking concrete block pavements in car parks.  

PubMed

Interlocking concrete block pavements (ICBPs) have been widely used in car parks to reduce runoff. Researches have demonstrated that clogging is the most influential factor in the reduction of the infiltration capacity of this type of permeable pavement. Nevertheless, there is no laboratory study of the infiltration performance of ICBPs that combines clogging levels with variables related with the topography of car parks such as runoff surface length (R(SL)) and surface slope (S(S)). This paper studies the infiltration behaviour of ICBP during their operational life in a car park using an improved version of the Cantabrian Fixed (CF) Infiltrometer. This laboratory device simulates direct rainfall and runoff from adjacent impervious areas over an ICBPs surface of 0.25 m(2) for different slopes (0, 3, 5, 7 and 10%) and three scenarios of clogging (surface newly built, surface clogged and surface clogged with maintenance). This paper presents the results of the tests and a statistical analysis based on three regression models (corresponding to each clogging scenario) depending on the R(SL) and S(S) variables. All models passed a confidence level of 95%, presenting high R(2) values and showing that R(SL) is a more influential variable than the S(S) for all clogging scenarios. PMID:23202575

Sañudo-Fontaneda, Luis A; Rodriguez-Hernandez, Jorge; Vega-Zamanillo, Angel; Castro-Fresno, Daniel

2013-01-01

448

A Bio-Inspired Swellable Microneedle Adhesive for Mechanical Interlocking with Tissue  

PubMed Central

Achieving significant adhesion to soft tissues while minimizing tissue damage poses a considerable clinical challenge. Chemical-based adhesives require tissue-specific reactive chemistry, typically inducing a significant inflammatory response. Staples are fraught with limitations including high-localized tissue stress and increased risk of infection, and nerve and blood vessel damage. Here, inspired by the endoparasite Pomphorhynchus laevis which swells its proboscis to attach to its host’s intestinal wall, we have developed a biphasic microneedle array that mechanically interlocks with tissue through swellable microneedle tips, achieving ~ 3.5 fold increase in adhesion strength compared to staples in skin graft fixation, and removal force of ~ 4.5 N/cm2 from intestinal mucosal tissue. Comprising a poly(styrene)-block-poly(acrylic acid) swellable tip and non-swellable polystyrene core, conical microneedles penetrate tissue with minimal insertion force and depth, yet high adhesion strength in their swollen state. Uniquely, this design provides universal soft tissue adhesion with minimal damage, less traumatic removal, reduced risk of infection and delivery of bioactive therapeutics. PMID:23591869

Yang, Seung Yun; O'Cearbhaill, Eoin D.; Sisk, Geoffroy C.; Park, Kyeng Min; Cho, Woo Kyung; Villiger, Martin; Bouma, Brett E.; Pomahac, Bohdan; Karp, Jeffrey M.

2013-01-01

449

Effect of cortical thickness and cancellous bone density on the holding strength of internal fixator screws  

Microsoft Academic Search

Internal fixators are a new class of implants designed to preserve the periosteal blood supply of the bone. In contrast to conventional plate fixation in which the screws have spherical heads and are loaded mainly by axial pullout forces, screws in internal fixators are “locked” within the plate and therefore subjected to axial as well as bending loads. In this

J. Seebeck; J. Goldhahn; H. Städele; P. Messmer; M. M. Morlock; E. Schneider

2004-01-01

450

Interference screw divergence in femoral tunnel fixation during endoscopic anterior cruciate ligament reconstruction using hamstring grafts  

Microsoft Academic Search

Purpose:To compare the divergence angles between bioabsorbable interference screws inserted into the femoral tunnel with the screwdriver placed through the anteromedial portal to those inserted with the screwdriver placed through the tibial tunnel and to examine the effect of the femoral tunnel interference screws’ divergence angles on fixation strength of hamstring grafts after anterior cruciate ligament (ACL) reconstruction using hamstring

Christopher M. Miller; James E. Tibone; Michael Hewitt; F. Daniel Kharrazi; Neal S. ElAttrache

2002-01-01

451

A new bioabsorbable interference screw: Preliminary results of a prospective, multicenter, randomized clinical trial  

Microsoft Academic Search

A randomized clinical trial was conducted to compare a bioabsorbable polyglyconate screw (Endo-Fix; Smith & Nephew, Andover, MA) to a metal screw in anterior cruciate ligament reconstruction. A total of 124 patients were operated on and 113 assessed up to 1 year postoperatively. Assessments included a history and physical examination, the IKDC evaluation, and knee arthrometry measurements. No significant differences

Karl-Peter Benedetto; Michael Fellinger; T. E. Lim; Jörg M. Passler; Jaap L. Schoen; W. Jaap Willems

2000-01-01

452

Transcutaneous migration of a tibial bioabsorbable interference screw after anterior cruciate ligament reconstruction  

Microsoft Academic Search

We present a case of a poly-L-lactic acid (PLLA) tibial bioabsorbable interference screw disengaging and migrating transcutaneously 12 months after successful anterior cruciate ligament reconstruction with quadrupled hamstrings autograft. No graft insufficiency or joint inflammatory reaction was present. The screw was removed surgically with no evidence of resorption. The graft was well incorporated into the tibial tunnel. The patient recovered

Greg Sassmannshausen; Charles F Carr

2003-01-01

453

Investigation of a Multiphase Twin-screw Pump Operating at High Gas Volume Fractions  

E-print Network

The use of twin-screw pumps for moving fluids is not new technology but its application to wet gas compression (high gas volume fraction [GVF]) is still considered relatively new. There are many advantages for using twin-screw pumps for oil field...

Kroupa, Ryan Daniel

2012-07-16

454

Calcium phosphate cement augmentation of cancellous bone screws can compensate for the absence of cortical fixation  

E-print Network

Calcium phosphate cement augmentation of cancellous bone screws can compensate for the absence Keywords: Screw fixation Pullout force Calcium phosphate cement Osteoporotic bone a b s t r a c with cement. Previous studies have shown that bone augmentation with Calcium Phosphate (CaP) cement

Guerraoui, Rachid

455

Factors associated with the stability of titanium screws placed in the posterior region for orthodontic anchorage  

Microsoft Academic Search

Recently, implant anchors such as titanium screws have been used for absolute anchorage during edgewise treatment. However, there have been few human studies reporting on the stability of implant anchors placed in the posterior region. The purpose of this study was to examine the success rates and to find the factors associated with the stability of titanium screws placed into

Shouichi Miyawaki; Isao Koyama; Masahide Inoue; Katsuaki Mishima; Toshio Sugahara; Teruko Takano-Yamamoto

2003-01-01

456

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. PMID:25050132

2014-01-01

457

Free-hand placement of iliac screws for spinopelvic fixation based on anatomical landmarks: technical note  

PubMed Central

Background The placement of iliac screws is a biomechanically sound method for the stabilization of long multi-segment lumbar constructs. Traditional techniques for the placement of iliac screws often involve either substantial iliac muscle dissection for visualization of screw trajectory based on bony landmarks, or alternatively the use of intra-operative imaging to visualize these landmarks and guide screw placement. We describe an alternative free-hand method of iliac screw placement, one that needs neither significant muscle dissection nor intra-operative imaging. Methods We performed this technique in 10 consecutive patients. Patient demographics, spinal pathology, post-operative complications, and screw hardware characteristics are described. Results We have successfully used this technique for the placement 20 iliac screws based on anatomic landmarks in 10 consecutive patients. There were no cortical breeches of the ileum and no penetrations into the acetabulum on post-operative imaging. There were no instances of hardware failure. Two patients developed deep vein thromboses after surgery, 1 had a pulmonary embolism. Conclusions Based on our limited experience to date, free-hand placement of iliac screws is both easy to perform and safe for the patient. Further study and validation using this technique is warranted. PMID:25694933

Fridley, Jared; Fahim, Daniel; Navarro, Jovany; Wolinsky, JP

2014-01-01

458

Theoretical and experimental research on the working process of screw refrigeration compressor under superfeed condition  

Microsoft Academic Search

In order to increase the refrigeration capacity and improve the coefficient of performance (COP), an economizer arrangement is used in the refrigeration system with screw refrigeration compressor. In this system, the mid-pressure refrigerant gas from the economizer is injected in the screw refrigeration compressor. So it affects the performance of the compressor. In this paper, the working process of a

Huagen Wu; Jianfeng Li; Ziwen Xing

2007-01-01

459

Mathematical modeling of the working cycle of oil injected rotary twin screw compressor  

Microsoft Academic Search

Oil injected twin-screw air and gas compressors are widely used for medium pressure applications in many industries. Low cost air compressors can be adopted for compression of helium and special gases, leading to significant cost saving. Mathematical analysis of oil injected twin-screw compressor is carried out on the basis of the laws of perfect gas and standard thermodynamic relations. Heat

N. Seshaiah; Subrata Kr. Ghosh; R. K. Sahoo; Sunil Kr. Sarangi

2007-01-01

460

Overall Energy Efficiency of Lubricant-Injected Rotary Screw Compressors and Aftercoolers  

Microsoft Academic Search

This paper shows how to analyze the overall energy efficiency of two typical equipments of compressed air system: lubricant-injected rotary screw compressors and aftercooler. Firstly, air power, a proposed effective tool of weighing energy, is introduced as the quantitative standard of energy in compressed air. Then, compression process of lubricant-injected rotary screw compressors for air production is analyzed deeply and

Yeming Zhang; Maolin Cai; Dewen Kong

2009-01-01

461

Numerical simulation of the extrusion process for food materials in a single-screw extruder  

Microsoft Academic Search

A numerical study of extrusion cooking of starch based materials in a single-screw extruder is carried out. The low moisture levels and high temperatures typically encountered in practical circumstances are considered. The starch conversion process is studied in the rheological region of the extruder which is often the last few turns of the screw, where the material is treated as

Raman V. Chiruvella; Y. Jaluria; Mukund V. Karwe

1996-01-01

462

Experimental analysis of mass transport and mixing in a single screw extruder for semolina dough  

Microsoft Academic Search

In this paper a fluid dynamics analysis of a single screw extruder for semolina dough is reported. Experimental evidence is provided of the absence of a backflow velocity component and that the screw effect on hydrated semolina consists mainly in transporting and compacting the feed semolina particles. The absence of the supposed backflow component is due to the particulate of

Fabrizio Sarghini; Silvana Cavella; Elena Torrieri; Paolo Masi

2005-01-01

463

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. PMID:24967041

2014-01-01

464

Fixation of dicapitular fractures of the mandibular condyle with a headless bone screw  

Microsoft Academic Search

The fixation of diacapitular fractures of the mandibular condyle utilising a headless cannulated bone screw (Martin HBS®) is described. An open approach was used with primary fixation of the fracture with a K-wire, over which the cannulated screw was inserted. The method and results are described.

R. A. Loukota

2007-01-01

465

The torsional strength of bones with residual screw holes from plates with unicortical and bicortical purchase  

Microsoft Academic Search

Objective. To evaluate the effect of unicortical and bicortical screw holes on residual bone strength by comparing the in vitro torsional strength of cadaveric sheep tibiae with screw holes from plates with unicortical and bicortical purchase relative to each other and to intact bone.Design. The paired tibiae were grouped randomly and torsion tested to failure as follows: Group I —

AR Remiger; T Miclau; RW Lindsey

1997-01-01

466

Histologic study of the bone adjacent to titanium bone screws used for mandibular fracture treatment  

Microsoft Academic Search

Purpose: Titanium miniplates have been widely used in mandibular fracture fixation because of their strength and excellent biocompatibility. However, the condition of the bone adjacent to titanium bone screws has not been clarified. This study histologically examined the bone-screw interface in patients treated for mandibular fractures. Patients and Materials: Specimens were obtained from 14 patients, and the undecalcified sections were

Hisanori Hirai; Akira Okumura; Masaaki Goto; Takeshi Katsuki

2001-01-01

467

Biomechanical Analysis of Distal Biceps Tendon Repair Methods  

Microsoft Academic Search

Background: The 1-incision and 2-incision techniques are commonly used methods to repair a distal biceps rupture, and they differ in the location of reinsertion of tendon into bone.Hypothesis: The native distal biceps brachii tendon inserts on the posterior-ulnar aspect of the bicipital tuberosity, which functions as a cam, increasing the tendon's moment arm during its principal action of forearm supination.

Jon Henry; Jeff Feinblatt; Christopher C. Kaeding; James Latshaw; Alan Litsky; Roman Sibel; Julie A. Step