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1

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

2

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

3

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

4

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

5

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

6

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

7

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

8

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

Microsoft Academic Search

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

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

1998-01-01

9

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

10

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

11

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

12

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

13

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

14

Outcome comparison of Lisfranc injuries treated through dorsal plate fixation versus screw fixation  

PubMed Central

OBJECTIVE: The objective of this prospective study was to test whether the treatment of Lisfranc injuries with open reduction and dorsal plate fixation would have the same or better functional outcomes as treatment with standard trans-articular screw fixation. METHODS: Sixty patients with primarily isolated Lisfranc joint injury were treated by open reduction and dorsal plate fixation or standard screw fixation. The patients were followed on average for 31 months. Evaluation was performed with patients' chief complaint, clinical examination, radiography, and AOFAS Midfoot Scale. RESULTS: Thirty two patients were treated with open reduction and dorsal plate fixation, and twenty eight patients were treated with open reduction and screw fixation. After two years follow-up, the mean AOFAS Midfoot score was 83.1 points in the dorsal plate fixation group and 78.5 points in the screw fixation group (p<0.01). Of the dorsal plate fixation group, radiographic analysis revealed anatomic reduction in twenty-nine patients (90.6%, 29/32) and nonanatomic reduction in three patients. Of the screw fixation group, radiographic analysis revealed anatomic reduction in twenty-three patients and nonanatomic reduction in five patients (82.1%, 23/28). CONCLUSIONS: Open reduction and dorsal plate fixation for a dislocated Lisfranc injury do have better short and median term outcome and a lower reoperation rate than standard screw ORIF. In our experience, we recommend using dorsal plate in ORIF on dislocated Lisfranc injuries. Level of Evidence II, Prospective Comparative Study.

Hu, Sun-jun; Chang, Shi-min; Li, Xiao-hua; Yu, Guang-rong

2014-01-01

15

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

16

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

17

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

18

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

19

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

20

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

21

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

22

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

23

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

24

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

25

Antegrade-retrograde opposing lag screws for internal fixation of simple displaced talar neck fractures.  

PubMed

The talar neck is deviated medially with reference to the long axis of the body of the talus. In addition, it deviates plantarward. The talar neck fracture line is sometimes observed to be oriented obliquely (not perpendicular to the long axis of the talar neck). This occurs when the medially deviated talar neck strikes the horizontally oriented anterior lower tibial edge. Internal fixation of a simple displaced talar neck fracture usually requires 2 lag screws. Because the fracture line is obliquely oriented, a better method for positioning the screws perpendicular to the fracture line is to place them in a reversed direction to provide maximum interfragmentary compression at the fracture site, which could increase the likelihood of absolute stability with subsequent improvement in the incidence of fracture union and a reduction of complications, such as avascular necrosis of the body of the talus. Two lag screws are used, with the first inserted from posteriorly to anteriorly (perpendicular to the fracture line) using a medial approach after medial malleolar chevron osteotomy. The second screw is inserted from anteriorly to posteriorly (perpendicular to the fracture line) using an anterolateral approach. Both screw heads should be countersunk. A series of 8 patients underwent this form of internal fixation for talar neck fracture repair, with satisfactory functional outcomes. In conclusion, the use of antegrade-retrograde opposing lag screws is a reasonable method of internal fixation for simple displaced talar neck fractures. PMID:25459087

Abdelkafy, Ashraf; Imam, Mohamed Abdelnabi; Sokkar, Sherif; Hirschmann, Michael

2015-01-01

26

Posterior Reduction and Temporary Fixation for Odontoid Fracture-a Salvage Maneuver to Anterior Screw Fixation.  

PubMed

Study Design. A prospective study.Objective. To evaluate the outcomes of posterior reduction and temporary fixation using the C1-C2 screw-rod system for odontoid fracture unsuitable for anterior screw fixation.Summary of Background Data. Anterior screw fixation has become the most widely used surgical procedure for the stabilization of odontoid fractures. However, if there is any contraindication for anterior fixation, posterior atlantoaxial fusion is preferred, eliminating the normal rotation of the atlantoaxial complex.Methods. A consecutive series of 22 patients with odontoid fracture unsuitable for anterior screw fixation were involved in this study. Posterior reduction and fixation without fusion using the C1-C2 screw-rod system was performed. Once fracture healing was obtained, instrumentation was removed. The visual analog scale (VAS) of neck pain, neck stiffness, American Spinal Injury Association (ASIA) impairment scale, patient satisfaction, and neck disability index (NDI) were recorded. The range of motion (ROM) of C1-C2 in flexion-extension and rotation was calculated.Results. The average age at internal fixation surgery was 40.2±11.3 years. The mean duration of follow up was 41.8±26.8 months. There were no complications associated with instrumentation. All patients returned to their pre-operative work. Fracture healing was observed in 21 patients and the instrumentation was removed. After removing the instrumentation, the VAS was reduced and neck stiffness were relieved (all P < 0.01). Patient satisfaction and NDI were improved (all P < 0.01). The ROM of C1-C2 was returned to 4.75°±1.62°and 25.70°±5.51°in flexion-extension and in rotation, respectively. No osteoarthritis was observed at the C1-C2 lateral mass joints.Conclusions. Posterior reduction and temporary fixation using the C1-C2 screw-rod system was an optimal salvage maneuver to anterior screw fixation for odontoid fracture. It could effectively avoid the motion loss of C1-C2 caused by posterior atlantoaxial fusion. PMID:25398034

Ni, Bin; Guo, Qunfeng; Lu, Xuhua; Xie, Ning; Wang, Liang; Guo, Xiang; Chen, Fei

2014-11-13

27

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

28

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

29

Mechanical comparison of cortical screw fixation versus locking plate fixation in first metatarsal base osteotomy.  

PubMed

The oblique closing base wedge osteotomy has been used for surgical treatment of moderate to severe hallux valgus deformities with an intermetatarsal angle typically greater than 15°. Several postoperative complications have been identified that relate to failure of the fixation construct used to fixate the osteotomy, especially when that construct has been subjected to a vertical load. We performed a mechanical analysis comparing 2 constructs used to fixate oblique osteotomies of the first metatarsal using composite first metatarsals. An oblique base osteotomy was uniformly performed on 40 composite first metatarsals. Of the 40 specimens, 20 were fixated with a locking plate construct and 18 with a cortical screw construct, consisting of an anchor and compression screw (2 specimens from the latter group were excluded because of hinge fracture). Each specimen was loaded in a materials testing machine to measure the maximum load at construct failure when a vertical force was applied to the plantar aspect of the metatarsal head. The mean load to failure for the locking plate construct was significantly greater than the cortical screw construct (190.0 ± 70 N versus 110.3 ± 20.3 N, p < .001). Our study results have demonstrated that the locking plate construct was able to withstand a significantly greater vertical load before failure than was the 2-cortical screw construct in oblique osteotomies performed at the base of composite first metatarsals. PMID:24954919

Smith, Kevin; Lidtke, Roy H; Oliver, Noah G; Maker, Jared M

2014-01-01

30

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

31

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

32

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

33

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

34

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

35

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

36

Guideline update for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 12: pedicle screw fixation as an adjunct to posterolateral fusion.  

PubMed

The utilization of pedicle screw fixation as an adjunct to posterolateral lumbar fusion (PLF) has become routine, but demonstration of a definitive benefit remains problematic. The medical evidence indicates that the addition of pedicle screw fixation to PLF increases fusion rates when assessed with dynamic radiographs. More recent evidence, since publication of the 2005 Lumbar Fusion Guidelines, suggests a stronger association between radiographic fusion and clinical outcome, although, even now, no clear correlation has been demonstrated. Although several reports suggest that clinical outcomes are improved with the addition of pedicle screw fixation, there are conflicting findings from similarly classified evidence. Furthermore, the largest contemporary, randomized, controlled study on this topic failed to demonstrate a significant clinical benefit with the use of pedicle screw fixation in patients undergoing PLF for chronic low-back pain. This absence of proof should not, however, be interpreted as proof of absence. Several limitations continue to compromise these investigations. For example, in the majority of studies the sample size is insufficient to detect small increments in clinical outcome that may be observed with pedicle screw fixation. Therefore, no definitive statement regarding the efficacy of pedicle screw fixation as a means to improve functional outcomes in patients undergoing PLF for chronic low-back pain can be made. There appears to be consistent evidence suggesting that pedicle screw fixation increases the costs and complication rate of PLF. High-risk patients, including (but not limited to) patients who smoke, patients who are undergoing revision surgery, or patients who suffer from medical conditions that may compromise fusion potential, may appreciate a greater benefit with supplemental pedicle screw fixation. It is recommended, therefore, that the use of pedicle screw fixation as a supplement to PLF be reserved for those patients in whom there is an increased risk of nonunion when treated with only PLF. PMID:24980589

Groff, Michael W; Dailey, Andrew T; Ghogawala, Zoher; Resnick, Daniel K; Watters, William C; Mummaneni, Praveen V; Choudhri, Tanvir F; Eck, Jason C; Sharan, Alok; Wang, Jeffrey C; Dhall, Sanjay S; Kaiser, Michael G

2014-07-01

37

Design and performance of spinal fixation pedicle screw system.  

PubMed

Pedicle screw-rod bilateral constructions are extensively used in spinal fixation. In this study, the common cause for failure of bilateral constructions has been determined to be the high stress concentration at the rod-setscrew interface. In order to overcome this problem, a design modification has been made by using a supplementary part (shoe) between rod and setscrew. Performance comparison of the conventional design and modified design has been done by conducting static tests. Design modification has resulted in 11%, 27%, 42% and 31% improvements in axial gripping capacity, torsional gripping capacity, flexion/extension resistance and subassembly compression strength, respectively. The most outstanding achievement has been obtained in the fatigue life, which was extended by almost three times. PMID:22888582

Demir, Teyfik; Camu?cuz, Necip

2012-01-01

38

Delayed subarachnoid hemorrhage following failed odontoid screw fixation.  

PubMed

Iatrogenic vascular injury is a rare but potentially devastating complication of cervical spine instrumentation. The authors report on a patient who developed an anterior spinal artery pseudoaneurysm associated with delayed subarachnoid hemorrhage after undergoing odontoid screw placement 14 months earlier. This 86-year-old man presented with spontaneous subarachnoid hemorrhage (Fisher Grade 4) and full motor strength on neurological examination. Imaging demonstrated pseudarthrosis of the odontoid process, extension of the odontoid screw beyond the posterior cortex of the dens, and a pseudoaneurysm arising from an adjacent branch of the anterior spinal artery. Due to the aneurysm's location and lack of active extravasation, endovascular treatment was not attempted. Posterior C1-2 fusion was performed to treat radiographic and clinical instability of the C1-2 joint. Postoperatively, the patient's motor function remained intact. Almost all cases of vascular injury related to cervical spine instrumentation are recognized at surgery. To the authors' knowledge, this is the first report of delayed vascular injury following an uncomplicated cervical fixation. This case further suggests that the risk of this phenomenon may be elevated in cases of failed fusion. PMID:21395399

Wilson, David A; Fusco, David J; Theodore, Nicholas

2011-06-01

39

Posterior pelvic ring fractures: Closed reduction and percutaneous CT-guided sacroiliac screw fixation  

Microsoft Academic Search

Purpose  To assess the midterm results of closed reduction and percutaneous fixation (CRPF) with computed tomography (CT)-guided sacroiliac\\u000a screw fixation in longitudinal posterior pelvic ring fractures.\\u000a \\u000a \\u000a \\u000a Methods  Thirteen patients with 15 fractures were treated. Eleven patients received a unilateral, two a bilateral, screw fixation.\\u000a Twenty-seven screws were implanted. Continuous on-table traction was used in six cases. Mean radiological follow-up was 13\\u000a months.

Augustinus Ludwig Jacob; Peter Messmer; Klaus-Wilhelm Stock; Norbert Suhm; Bernard Baumann; Pietro Regazzoni; Wolfgang Steinbrich

1997-01-01

40

Comparison of screw and screwless fixation in cementless total knee arthroplasty.  

PubMed

This study compared two groups of consecutive patients undergoing total knee arthroplasty (TKA) with an identical cementless tibial baseplate supplementally fixated with and without screws. In 58 TKAs, two 6.5-mm cancellous screws were used for fixation, and in 58 TKAs, screwless fixation was used. Clinical evaluation was performed using the Hospital for Special Surgery knee score, and fluoroscopically guided radiographs were evaluated for radiolucencies. In the screw fixation group, average follow-up was 82+/-6 months (range, 59-89 months) and average patient age at surgery was 63 years. For the screwless fixation group, average follow-up was 67+/-5 months (range, 48-76 months) and average patient age at surgery was 62 years. Average knee score was 97 for the screw fixation group and 98 for the screwless fixation group. This study demonstrated stability in cementless TKA both with and without screw fixation in the mid-term using the Natural-Knee II tibial component. PMID:19292215

Ferguson, Ryan P; Friederichs, Matthew G; Hofmann, Aaron A

2008-02-01

41

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

PubMed Central

Introduction. Management of elderly patients with thoracolumbar fractures is still challenging due to frequent osteoporosis and risk of screws pull-out. The aim of this study was to evaluate results of a percutaneous-only procedure to treat these fragile patients using cement-augmented screws. Methods. 12 patients diagnosed with a thoracolumbar fracture associated with an important loss of bone stock were included in this prospective study. Surgical procedure included systematically a percutaneous osteosynthesis using cemented fenestrated screws. When necessary, additional anterior support was performed using a kyphoplasty procedure. Clinical and radiographic evaluations were performed using CT scan. Results. On the whole series, 15 fractures were diagnosed and 96 cemented screws were inserted. The difference between the pre- and postoperative vertebral kyphosis was statistically significant (12.9° versus 4.4°, P = 0.0006). No extrapedicular screw was reported and one patient was diagnosed with a cement-related pulmonary embolism. During follow-up period, no infectious complications, implant failures, or pull-out screws were noticed. Discussion. Aging spine is becoming an increasing public health issue. Management of these patients requires specific attention due to the augmented risk of complications. Using percutaneous-only screws fixation with cemented screw provides satisfactory results. A rigorous technique is mandatory in order to achieve best outcomes. PMID:24696858

Pesenti, Sébastien; Peltier, Emilie; Adetchessi, Tarek; Dufour, Henry; Fuentes, Stéphane

2014-01-01

42

Proponents of fixation of an ACL graft at the joint line with an interference screw base their opinions on several  

E-print Network

anterior laxity and knee stiffness as well as joint line fixation with an interference screw in human bone of the bone were reconstructed with a double-looped tendon graft and fixed with an interference screw and 3Proponents of fixation of an ACL graft at the joint line with an interference screw base

Hull, Maury

43

Bone-screw mandible fixation: An intraoperative alternative to arch bars  

Microsoft Academic Search

Objectives: Bone-screw mandible fixation (BSMF) is evaluated as an alternative to intraoperative arch-bar maxillomandibular fixation before plating of mandibular fractures. BSMF is achieved by wire ligation of opposing bone-screws placed in the maxilla and mandible. Methods: A retrospective evaluation of 23 patients with 40 mandibular fractures who underwent mandibular fracture repairs. BSMF was used instead of arch bars to ensure

A. John Vartanian; Aijaz Alvi

2000-01-01

44

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

45

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

46

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

47

Anterior transarticular screw fixation as a conventional operation for rigid stabilization  

PubMed Central

Background: Anterior transarticular screw (ATS) fixation is a useful surgical option for atlantoaxial (AA) stabilization. This report presents a revised ATS method for AA fusion. Methods: A 79-year-old male presented with AA instability attributed both to an old odontoid fracture and severe degeneration of the lateral atlantoaxial joints (LAAJs). ATS fixation was performed through the conventional anterior cervical approach. The longest screw trajectories were planned preoperatively using multiplanar reconstruction computed tomography (CT) scans, with entry points of the screws situated at the midpoint on the inferior border of the axial body. The surgical exposure was limited to opening at the entry points alone. Our retractor of choice was the Cusco speculum; it sufficiently secured space for utilizing the required instruments for screw placement while offering sufficient protection of soft tissues. Cannulated full-threaded bicortical screws stabilized the LAAJs. Screw insertion required a significant amount of coronal angulation up to the superior articular process of the atlas under open-mouth and lateral fluoroscopy image guidance. After ATS fixation, bone grafting was performed between the posterior laminae of the axis and the atlas through a conventional posterior approach. Results: Bony fusion between the atlas and the axis was confirmed radiographically. Arthrodesis of the LAAJs occurred despite no bone grafting. Conclusions: Rigid fixation of the LAAJs was obtained by our ATS technique, indicating that it is an alternative method for AA fixation when posterior rigid internal fixation is not applicable.

Sasaki, Manabu; Matsumoto, Katsumi; Tsuruzono, Koichiro; Yoshimura, Kazuhiro; Shibano, Katsuhiko; Yonenobu, Kazuo

2014-01-01

48

Biomechanical evaluation of anatomical double-bundle coracoclavicular ligament reconstruction secured with knot fixation versus screw fixation.  

PubMed

Methods to reconstruct the coracoclavicular ligaments anatomically have been described. No clear advantage of 1 technique has been elucidated. The authors' hypothesis was that the biomechanical properties of a modified knot fixation technique would be similar to the anatomical double-bundle technique. Sixteen matched cadaveric shoulders were used for this study, and 1 additional shoulder was used in the knot fixation group only. Shoulders were randomly assigned to the anatomical double-bundle coracoclavicular ligament reconstruction technique (n=8) or a knot fixation technique (n=9). The intact coracoclavicular ligaments were tested to failure with superior displacement at a rate of 2 mm/s. Reconstruction was performed using a semitendinosus tendon allograft, and load to failure was repeated for each construct. Ultimate failure load, stiffness, and failure mode were compared using a paired t test (P<.05). No significant difference existed in load to failure between native and reconstructed ligaments or between reconstruction techniques. Stiffness decreased significantly after reconstruction in the double-bundle group (from 32.5 to 22.5 N/mm; P=.035) and in the modified knot fixation group (from 35.5 to 21.9 N/mm; P=.043). No significant difference existed in stiffness between the 2 reconstruction groups. A significant difference (P=.003) existed between failure modes between the 2 reconstruction techniques. Although less stiff than the native ligament, either technique used to reconstruct the coracoclavicular ligament can be performed to yield a load to failure similar to the intact ligament. The majority of failures in the double-bundle group were by means of the graft slipping at the screw-tendon interface at 1 of the clavicular drill holes. The modified knot fixation technique failed the majority of the time by graft elongation. PMID:23937752

Staron, Jeffrey S; Esquivel, Amanda O; Pandhi, Nikhil G; Hanna, Jason D; Lemos, Stephen E

2013-08-01

49

Cannulated Screw Fixation of Jones FracturesA Clinical and Biomechanical Study  

Microsoft Academic Search

Background: Traditional nonsurgical treatment of Jones fractures has high rates of delayed union, nonunion, and refracture. Internal fixation has become the treatment of choice in athletes and active patients.Purpose: The purpose of this study was (1) to review the short- and long-term clinical results of cannulated screw fixation of Jones fractures and (2) to perform a biomechanical evaluation of fatigue

Keri Reese; Alan Litsky; Christopher Kaeding; Angela Pedroza; Nilesh Shah

2004-01-01

50

Results of intraoral cortical bone screw fixation technique for mandibular fractures  

Microsoft Academic Search

The intraoral cortical bone screw fixation technique carries many advantages over traditional methods of intermaxillary fixation. Simplicity of the technique, reduction of operative time, and reduction of risk of transmission of human immunodeficiency virus and hepatitis make this an important technique in the armamentarium of busy facial trauma surgeons. Since 1992, 45 mandibular fractures in 29 patients treated with the

KYLE F. GORDON; J. MARK REED; VINOD K. ANAND

1995-01-01

51

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

PubMed Central

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

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

2013-01-01

52

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

53

Mechanical Evaluation of a Soft Tissue Interference Screw in Free Tendon Anterior Cruciate Ligament Graft Fixation  

Microsoft Academic Search

In this study of bioabsorbable screw fixation of free tendon grafts used in anterior cruciate ligament reconstruction, we performed load-to-failure and cyclic loading of tendon fixation in porcine bone. Bone density measurements from dual photon absorptometry scans were obtained to correlate bone density with fixation failure. The average density of porcine bone (1.42 g\\/cm2) was similar to that of young

Durgesh G. Nagarkatti; Brian P. McKeon; Brian S. Donahue; John P. Fulkerson

2001-01-01

54

Post-traumatic coxa vara in children following screw fixation of the femoral neck  

PubMed Central

Background and purpose The rare displaced fractures of the femoral neck in children need accurate reduction and rigid fixation. The implants commonly used for internal fixation in children are pins or screws. We evaluated the long-term outcome in children who sustained fractures of the proximal femur that were treated by screw fixation. Patients and methods All 22 children (mean age 12 (5–16) years) with fractures of the femoral neck that were treated with screw fixation (mean 2.4 (1–3) screws) at our department between 1990 and 2006 were evaluated. For measurement of outcome, the Harris hip score (HHS) was used and the development of post-traumatic coxa vara was assessed from the difference in the neck-shaft angle postoperatively and at the latest follow-up examination, after mean 4 (2–15) years. Results A loss of reduction was observed in 12 patients. There was a statistically significant correlation between the HHS and the changes in the neck-shaft angle. Interpretation Loss of reduction was found in more than half of the children. Screw fixation cannot be recommended for the treatment of femoral neck fractures in children due to a substantial number of post-traumatic coxa vara. PMID:20809743

2010-01-01

55

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

56

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

57

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

58

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

59

Autologous bone grafting without screw fixation for tibial defects in total knee arthroplasty  

Microsoft Academic Search

.   We evaluated 30 knees with autologous bone grafts, performed without screw fixation, for tibial defects in total knee arthroplasty\\u000a (TKA). The tibial defects were classified into three types: contained, flat peripheral, and slant peripheral. The resected\\u000a femoral condyle was fixed with a combination of bone cement and the tibial component, without using screws. The patients were\\u000a followed for an

Wataru Watanabe; Kozo Sato; Eiji Itoi

2001-01-01

60

Posterior pelvic ring fractures: Closed reduction and percutaneous CT-guided sacroiliac screw fixation  

SciTech Connect

Purpose. To assess the midterm results of closed reduction and percutaneous fixation (CRPF) with computed tomography (CT)-guided sacroiliac screw fixation in longitudinal posterior pelvic ring fractures. Methods. Thirteen patients with 15 fractures were treated. Eleven patients received a unilateral, two a bilateral, screw fixation. Twenty-seven screws were implanted. Continuous on-table traction was used in six cases. Mean radiological follow-up was 13 months. Results. Twenty-five (93%) screws were placed correctly. There was no impingement of screws on neurovascular structures. Union occurred in 12 (80%), delayed union in 2 (13%), and nonunion in 1 of 15 (7%) fractures. There was one screw breakage and two axial dislocations. Conclusion. Sacroiliac CRPF of longitudinal fractures of the posterior pelvic ring is technically simple, minimally invasive, well localized, and stable. It should be done by an interventional/surgical team. CT is an excellent guiding modality. Closed reduction may be a problem and succeeds best when performed as early as possible.

Jacob, Augustinus Ludwig [Kantonsspital-Universitaetskliniken, Institute of Diagnostic Radiology (Switzerland); Messmer, Peter [Kantonsspital-Universitaetskliniken, Department of Surgery (Switzerland); Stock, Klaus-Wilhelm [Kantonsspital-Universitaetskliniken, Institute of Diagnostic Radiology (Switzerland); Suhm, Norbert [Kantonsspital-Universitaetskliniken, Department of Surgery (Switzerland); Baumann, Bernard [Kantonsspital-Universitaetskliniken, Institute of Diagnostic Radiology (Switzerland); Regazzoni, Pietro [Kantonsspital-Universitaetskliniken, Department of Surgery (Switzerland); Steinbrich, Wolfgang [Kantonsspital-Universitaetskliniken, Institute of Diagnostic Radiology (Switzerland)

1997-07-15

61

Cannulated screw and hexapodal fixator reconstruction for compound upper tibial fractures  

PubMed Central

Objectives: The aim of the treatment of tibial plateau fractures is to obtain a pain-free and fully functional knee with closed reduction, percutaneous cannulated screw fixation and hexapodal external fixator reconstruction for high energy compound upper tibial fractures. Methods: Patients with comminuted tibial plateau fractures underwent closed reduction, percutaneous fixation with cannulated screws, and reconstruction with hexapodal external fixator. The follow-up period was 24 months. Results: The clinical and radiological results were good or excellent. The average knee flexion was 125°. Conclusion: Our results are successful in the initial stage, however, it should be pointed out that during the long term follow-up osteoarthritis may develop leading to worsening of the condition. Level of Evidence IV, Case Series. PMID:24644420

Uzun, Metin; Bilen, Fikri Erkal; Eralp, Levent

2014-01-01

62

Biplane double-supported screw fixation (F-technique): a method of screw fixation at osteoporotic fractures of the femoral neck.  

PubMed

The present work introduces a method of screw fixation of femoral neck fractures in the presence of osteoporosis, according to an original concept of the establishment of two supporting points for the implants and their biplane positioning in the femoral neck and head. The provision of two steady supporting points for the implants and the highly increased (obtuse) angle at which they are positioned allow the body weight to be transferred successfully from the head fragment onto the diaphysis, thanks to the strength of the screws, with the patient's bone quality being of least importance. The position of the screws allows them to slide under stress with a minimal risk of displacement. The method was developed in search of a solution for those patients for whom primary arthroplasty is contraindicated. The method has been analysed in relation to biomechanics and statics. For the first time, a new function is applied to a screw fixation-the implant is presented as a simple beam with an overhanging end. PMID:21966288

Filipov, Orlin

2011-10-01

63

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

Microsoft Academic Search

Ligament graft fixation with bioabsorbable interference screws is a standard procedure in cruciate ligament replacement. Previous\\u000a screw designs may resorb incompletely, and can cause osteolysis and sterile cysts despite being implanted for several years.\\u000a The aim of this study was to examine the in vivo degradation and biocompatibility of the new Milagro™ interference screw (Mitek,\\u000a Norderstedt, Germany). The Milagro™ interference screw

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

2009-01-01

64

Scaphoid fracture in the young athlete - therapeutic outcome of internal fixation using the Herbert screw  

Microsoft Academic Search

Background. A fractured scaphoid is a common disabling injury occurring in contact sports. This study was designed to evaluate the therapeutic outcome of Herbert screw fixation for scaphoid fracture in young athletes. Methods. Thirty athletes with 30 scaphoid fractures were treated. According to the Herbert classification, 10 were classified as acute fracture (group I), 6 as fibrous union (group II)

Keiichi Muramatsu; Kazuteru Doi; Noriyuki Kuwata; Fujio Kawakami; Koichiro Ihara; Shinya Kawai

2002-01-01

65

Tibial and Pretibial Cyst Formation After Anterior Cruciate Ligament Reconstruction With Bioabsorbable Interference Screw Fixation  

Microsoft Academic Search

Summary: We report a case of an osteolytic tibial enlargement in association with a pretibial cyst formation 8 months after successful anterior cruciate ligament reconstruction with autologous bone–patellar tendon–bone graft and tibial graft fixation with a bioabsorbable interference screw. No joint inflammatory reaction or graft insufficiency was detected. The patient underwent cyst excision and curettage of the tibial tunnel with

Vladimir Martinek; Niklaus F. Friederich

1999-01-01

66

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

Microsoft Academic Search

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

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

1993-01-01

67

Direct transoral reduction of anteriorly displaced type II odontoid fracture during anterior odontoid screw fixation: Review of literature  

PubMed Central

Background The anteriorly displaced type II odontoid fracture is treated either conservatively by halo-vest brace immobilization or surgically by posterior atlantoaxial fusion. Anterior odontoid screw fixation is not advised for this pattern of odontoid fracture because of the difficult trajectory for screw insertion despite its advantage of salvaging the upper cervical spine rotatory range of movement. This article presents a new transoral manipulation technique for reduction of anteriorly displaced type II odontoid fracture and review of the literature. Methods A 24-year-old man presented 2 weeks after a motor vehicle accident with anteriorly displaced type II odontoid fracture. Intraoperatively, after unsuccessful attempts to reduce the anteriorly displaced type II odontoid fracture, complete reduction of the odontoid process and proper screw placement were achieved by direct transoral manipulation with an army-navy hand retractor. Additional manual pressure on the spinous process of the cervical spine at the same time has resulted in better reduction. The patient was followed up neurologically and radiologically to assess the reduction and healing of the odontoid fracture. Results Postoperatively, the patient was neurologically intact, and his computed tomography cervical spine scan showed proper placement of the odontoid screw with adequate reduction of the odontoid process. At the 3-month follow-up, the patient was neurologically intact and had painless full range of cervical spine movement, and his computed tomography cervical spine scan showed a well-healed odontoid fracture. Conclusions Direct transoral manipulation with an army-navy hand retractor can be used to assist in reducing the anteriorly displaced type II odontoid fracture during anterior odontoid screw fixation.

Orief, Tamer; Almusrea, Khaled; Assiri, Ibrahim

2012-01-01

68

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

69

Acromioclavicular Joint Fixation Using an Acroplate Combined With a Coracoclavicular Screw  

PubMed Central

Background Appropriate treatment of acromioclavicular joint dislocation is controversial. Acroplate fixation is one of the most common treatment methods of acromioclavicular joint (ACJ) dislocation. Based on the risk of re-dislocation after Acroplate fixation, we assumed that combined fixation with an Acroplate and a coracoclavicular screw helps improve the outcome. Objectives The main purpose of the current study was to compare the outcome of ACJ dislocation treated with an Acroplate alone and in combination with coracoclavicular screw. Patients and Methods This study was carried out on 40 patients with ACJ dislocation types III to VI who were divided randomly into two equal groups: Acroplate group (P) and Acroplate in combination with coracoclavicular screw group (P + S). The screws were extracted 3-6 months postoperatively. The patients were followed for 1 year and Imatani’s score was calculated. Finally, the data were compared between the groups. Results The mean Imatani’s score was significantly higher in P + S group (83.4 ± 14.1) than P group (81.2 ± 10.3) (P < 0.001). The mean duration of surgery was the same in the two groups (59.8 ± 9.4 minutes in group P V.s 64.3 ± 10.9 minutes in group P + S; P = 0.169). There were no cases of re-dislocation, degenerative changes and ossification and all patients returned to their previous jobs or sporting activities. Conclusions Using a coracoclavicular screw combined with an Acroplate can improve the patients’ function after ACJ disruption without any significant increase in surgical duration. Authors recommend this technique in the fixation of ACJ dislocation. PMID:24396788

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

2013-01-01

70

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

PubMed Central

Background Symptomatic atlantoaxial instability needs stabilization of the atlantoaxial joint. Among the various techniques described in literature for the fixation of atlantoaxial joint, Magerl's technique of transarticular screw fixation remains the gold standard. Traditionally this technique combines placement of transarticular screws and posterior wiring construct. The aim of this study is to evaluate clinical and radiological outcomes in subjects of atlantoaxial instability who were operated using transarticular screws and iliac crest bone graft, without the use of sublaminar wiring (a modification of Magerl's technique). Methods We evaluated retrospectively 38 subjects with atlantoaxial instability who were operated at our institute using transarticular screw fixation. The subjects were followed up for pain, fusion rates, neurological status and radiographic outcomes. Final outcome was graded both subjectively and objectively, using the scoring system given by Grob et al. Results Instability in 34 subjects was secondary to trauma, in 3 due to rheumatoid arthritis and 1 had tuberculosis. Neurological deficit was present in 17 subjects. Most common presenting symptom was neck pain, present in 35 of the 38 subjects. Postoperatively residual neck and occipital pain was present in 8 subjects. Neurological deficit persisted in only 7 subjects. Vertebral artery injury was seen in 3 subjects. None of these subjects had any sign of neurological deficit or vertebral insufficiency. Three cases had nonunion. At the latest follow up, subjectively, 24 subjects had good result, 6 had fair and 8 had bad result. On objective grading, 24 had good result, 11 had fair and 3 had bad result. The mean follow up duration was 41 months. Conclusions Transarticular screw fixation is an excellent technique for fusion of the atlantoaxial complex. It provides highest fusion rates, and is particularly important in subjects at risk for nonunion. Omitting the posterior wiring construct that has been used along with the bone graft in the traditional Magerl' s technique achieves equally good fusion rates and is an important modification, thereby avoiding the complications of sublaminar wire passage. PMID:21092173

2010-01-01

71

Mid-Term Results of Computer-Assisted Cervical Pedicle Screw Fixation  

PubMed Central

Study Design A retrospective study. Purpose The present study aimed to evaluate mid-term results of cervical pedicle screw (CPS) fixation for cervical instability. Overview of Literature CPS fixation has widely used in the treatment of cervical spinal instability from various causes; however, there are few reports on mid-term surgical results of CPS fixation. Methods Record of 19 patients who underwent cervical and/or upper thoracic (C2-T1) pedicle screw fixation for cervical instability was reviewed. The mean observation period was 90.2 months. Evaluated items included Japanese Orthopaedic Association (JOA) score and C2-7 lordotic angle before surgery and at 5 years after surgery. Postoperative computerized tomography was used to determine the accuracy of screw placement. Visual analog scale (VAS) for neck pain and radiological evidence of adjacent segment degeneration (ASD) at the 5-year follow-up were also evaluated. Results Mean JOA score was significantly improved from 9.0 points before surgery to 12.8 at 5 years after surgery (p=0.001). The C2-7 lordotic angle of the neutral position improved from 6.4° to 7.8° at 5 years after surgery, but this was not significant. The major perforation rate was 5.0%. There were no clinically significant complications such as vertebral artery injury, spinal cord injury, or nerve root injury caused by any screw perforation. Mean VAS for neck pain was 49.4 at 5 years after surgery. The rate of ASD was 21.1%. Conclusions Our mid-term results showed that CPS fixation was useful for treating cervical instability. Severe complications were prevented with the assistance of a computed tomography-based navigation system. PMID:25558318

Uehara, Masashi; Mukaiyama, Keijiro; Kuraishi, Shugo; Shimizu, Masayuki; Ikegami, Shota; Futatsugi, Toshimasa; Ogihara, Nobuhide; Hashidate, Hiroyuki; Hirabayashi, Hiroki; Kato, Hiroyuki

2014-01-01

72

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

73

Clinical Outcome of Anterior Cruciate Ligament Reconstruction with Quadrupled Hamstring Tendon Graft and Bioabsorbable Interference Screw Fixation  

Microsoft Academic Search

Background: To date, there has been no publication of clinical follow-up data on patients who have undergone quadrupled hamstring tendon autograft anterior cruciate ligament reconstruction with bioabsorbable screw fixation.Purpose: To report the results of quadrupled hamstring tendon autograft anterior cruciate ligament reconstruction with bioabsorbable interference screw fixation.Study Design: Retrospective review.Methods: Sixty-five patients (66 knees) were retrospectively identified by chart review

William P. H. Charlton; Donald A. Randolph; Stephen Lemos; Clarence L. Shields

2003-01-01

74

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

PubMed Central

Reconstruction of the posterior cruciate ligament (PCL) by a tibial press-fit fixation of the patellar tendon with an accessory bone plug is a promising approach because no foreign materials are required. Until today, there is no data about the biomechanical properties of such press-fit fixations. The aim of this study was to compare the biomechanical qualities of a bone plug tibial inlay technique with the commonly applied interference screw of patellar tendon PCL grafts. Twenty patellar tendons including a bone block were harvested from ten human cadavers. The grafts were implanted into twenty legs of adult German country pigs. In group P, the grafts were attached in a press-fit technique with accessory bone plug. In group S, the grafts were fixed with an interference screw. Each group consisted of 10 specimens. The constructs were biomechanically analyzed in cyclic loading between 60 and 250 N for 500 cycles recording elongation. Finally, ultimate failure load and failure mode were analyzed. Ultimate failure load was 598.6±36.3 N in group P and 653.7±39.8 N in group S (not significant, P>0.05). Elongation during cyclic loading between the 1st and the 20th cycle was 3.4±0.9 mm for group P and 3.1±1 mm for group S. Between the 20th and the 500th cycle, elongation was 4.2±2.3 mm in group P and 2.5±0.9 mm in group S (not significant, P>0.05). This is the first study investigating the biomechanical properties of tibial press-fit fixation of the patellar tendon with accessory bone plug in posterior cruciate ligament reconstruction. The implant-free tibial inlay technique shows equal biomechanical characteristics compared to an interference screw fixation. Further in vivo studies are desirable to compare the biological behavior and clinical relevance of this fixation device. PMID:24416479

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

2013-01-01

75

Biomechanical comparison between BioScrew and titanium alloy interference screws for bone—patellar tendon—bone graft fixation in anterior cruciate ligament reconstruction  

Microsoft Academic Search

This investigation compared the maximum load at failure of BioScrew (Linvatec Corp, Largo, FL) and titanium alloy interference screw femoral fixation using a human cadaveric model that approximated the anatomical orientation and physiological strain rate of in vivo bone—patellar tendon—bone (BPTB) graft loading following anterior cruciate ligament reconstruction. Eighteen fresh-frozen human BPTB allografts (10-mm wide, 10-mm thick, 25-mm long bone

David N. M. Caborn; William P. Urban; Darren L. Johnson; John Nyland; David Pienkowski

1997-01-01

76

Effects of Lateral Mass Screw Rod Fixation to the Stability of Cervical Spine after Laminectomy  

NASA Astrophysics Data System (ADS)

There are many cases of injury in the cervical spine due to degenerative disorder, trauma or instability. This condition may produce pressure on the spinal cord or on the nerve coming from the spine. The aim of this study was, to analyze the stabilization of the cervical spine after undergoing laminectomy via computational simulation. For that purpose, a three-dimensional finite element (FE) model for the multilevel cervical spine segment (C1-C7) was developed using computed tomography (CT) data. There are various decompression techniques that can be applied to overcome the injury. Usually, decompression procedures will create an unstable spine. Therefore, in these situations, the spine is often surgically restabilized by using fusion and instrumentation. In this study, a lateral mass screw-rod fixation was created to stabilize the cervical spine after laminectomy. Material properties of the titanium alloy were assigned on the implants. The requirements moments and boundary conditions were applied on simulated implanted bone. Result showed that the bone without implant has a higher flexion and extension angle in comparison to the bone with implant under applied 1Nm moment. The bone without implant has maximum stress distribution at the vertebrae and ligaments. However, the bone with implant has maximum stress distribution at the screws and rods. Overall, the lateral mass screw-rod fixation provides stability to the cervical spine after undergoing laminectomy.

Rosli, Ruwaida; Kashani, Jamal; Kadir, Mohammed Rafiq Abdul

77

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

78

Modified lapidus arthrodesis with crossed screw fixation: early weightbearing in 136 patients.  

PubMed

Modified Lapidus arthrodesis is a versatile and powerful procedure for correcting the hallux valgus deformity typically associated with significant metatarsus primus varus or increased first ray mobility. Traditionally, patients have remained non-weightbearing until the arthrodesis has consolidated. More recently, numerous studies have evaluated the outcomes of early postoperative weightbearing using a variety of fixation constructs. The present retrospective cohort study evaluated 136 consecutive patients who had undergone modified Lapidus arthrodesis for hallux valgus deformity with conventional, crossed, solid core, screw fixation, were enrolled in an early weightbearing protocol, and were followed for 12 months. All the patients were partial weightbearing in a protective boot a mean of 12.2 (SD ± 4.36) days after surgery, with full weightbearing at 34.4 (SD ± 11.89) days. Union was achieved in 133 patients (97.8%). Of the 3 (2.2%) patients with nonunion, 2 (1.5%) remained asymptomatic. The mean time to radiographic union was 65 (SD ± 37.24) days. Significant improvement was seen in the first intermetatarsal angle and hallux abductus angle after surgery (p < .0001). Deformity correction was not compromised by early weightbearing and was well maintained over time. These results support early weightbearing with traditional crossed screw fixation for modified Lapidus arthrodesis with outcomes and complication rates comparable to those previously published. PMID:25451208

King, Christy M; Richey, Johanna; Patel, Sandeep; Collman, David R

2015-01-01

79

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

PubMed Central

Background We have recently developed a subcutaneous anterior pelvic fixation technique (INFIX). This internal fixator permits patients to sit, roll over in bed and lie on their sides without the cumbersome external appliances or their complications. The purpose of this study was to evaluate the biomechanical stability of this novel supraacetabular pedicle screw internal fixation construct (INFIX) and compare it to standard internal fixation and external fixation techniques in a single stance pelvic fracture model. Methods Nine synthetic pelves with a simulated anterior posterior compression type III injury were placed into three groups (External Fixator, INFIX and Internal Fixation). Displacement, total axial stiffness, and the stiffness at the pubic symphysis and SI joint were calculated. Displacement and stiffness were compared by ANOVA with a Bonferroni adjustment for multiple comparisons Results The mean displacement at the pubic symphysis was 20, 9 and 0.8?mm for external fixation, INFIX and internal fixation, respectively. Plate fixation was significantly stiffer than the INFIX and external Fixator (P?=?0.01) at the symphysis pubis. The INFIX device was significantly stiffer than external fixation (P?=?0.017) at the symphysis pubis. There was no significant difference in SI joint displacement between any of the groups. Conclusions Anterior plate fixation is stiffer than both the INFIX and external fixation in single stance pelvic fracture model. The INFIX was stiffer than external fixation for both overall axial stiffness, and stiffness at the pubic symphysis. Combined with the presumed benefit of minimizing the complications associated with external fixation, the INFIX may be a more preferable option for temporary anterior pelvic fixation in situations where external fixation may have otherwise been used. PMID:23017093

2012-01-01

80

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

PubMed Central

Objective Iliac screw fixation has been used to prevent premature loosening of sacral fixation and to provide more rigid fixation of the sacropelvic unit. We describe our technique for iliac screw placement and review our experience with this technique. Methods Thirteen consecutive patients who underwent spinopelvic fixation using iliac screws were enrolled. The indications for spinopelvic fixation included long segment fusions for spinal deformity and post-operative flat-back syndrome, symptomatic pseudoarthrosis of previous lumbosacral fusions, high-grade lumbosacral spondylolisthesis, lumbosacral tumors, and sacral fractures. Radiographic outcomes were assessed using plain radiographs, and computed tomographic scans. Clinical outcomes were assessed using the Oswestry Disability Index (ODI) and questionnaire about buttock pain. Results The median follow-up period was 33 months (range, 13-54 months). Radiographic fusion across the lumbosacral junction was obtained in all 13 patients. The average pre- and post-operative ODI scores were 40.0 and 17.5, respectively. The questionnaire for buttock pain revealed the following: 9 patients (69%) perceived improvement; 3 patients (23%) reported no change; and 1 patient (7.6%) had aggravation of pain. Two patients complained of prominence of the iliac hardware. The complications included one violation of the greater sciatic notch and one deep wound infection. Conclusion Iliac screw fixation is a safe and valuable technique that provides added structural support to S1 screws in long-segment spinal fusions. Iliac screw fixation is an extensive surgical procedure with potential complications, but high success rates can be achieved when it is performed systematically and in appropriately selected patients. PMID:21113363

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

2010-01-01

81

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

Microsoft Academic Search

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

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

2008-01-01

82

Experimental and Numerical Analysis of Screw Fixation in Anterior Cruciate Ligament Reconstruction  

NASA Astrophysics Data System (ADS)

This paper reports the results of an experimental and finite element analysis of tibial screw fixation in anterior cruciate ligament (ACL) reconstruction. The mechanical properties of the bone and tendon graft are obtained from experiments using porcine bone and bovine tendon. The results of the numerical study are compared with those from mechanical testing. Analysis shows that the model may be used to establish the optimum placement of the tunnel in anterior cruciate ligament reconstruction by predicting mechanical parameters such as stress, strain and displacement at regions in the tunnel wall.

Chizari, Mahmoud; Wang, Bin; Snow, Martyn; Barrett, Mel

2008-09-01

83

Application of frameless stereotaxy to pedicle screw fixation of the spine.  

PubMed

Interactive frameless stereotaxy has been successfully applied to intracranial surgery. It has contributed to the improved localization of deep-seated brain lesions and has demonstrated a potential for reducing both operative time and morbidity. However, it has not been as effectively applied to spinal surgery. The authors describe the application of frameless stereotactic techniques to spinal surgery, specifically pedicle screw fixation of the lumbosacral spine. Preoperative axial computerized tomography (CT) images of the appropriate spinal segments are obtained and loaded onto a high-speed graphics supercomputer workstation. Intraoperatively, these images can be linked to the appropriate spinal anatomy by a sonic localization digitizer device that is interfaced with the computer workstation. This permits the surgeon to place a pointing device (sonic wand) on any exposed spinal bone landmark in the operative field and obtain multiplanar reconstructed CT images projected in near-real time on the workstation screen. The images can be manipulated to assist the surgeon in determining the proper entry point for a pedicle screw as well as defining the appropriate trajectory in the axial and sagittal planes. It can also define the correct screw length and diameter for each pedicle to be instrumented. The authors applied this device to the insertion of 150 screws into the lumbosacral spines of 30 patients. One hundred forty-nine screws were assessed to be satisfactorily placed by postoperative CT and plain film radiography. In this report the authors discuss their use of this device in the clinical setting and review their preliminary results of frameless stereotaxy applied to spinal surgery. On the basis of their findings, the authors conclude that frameless stereotactic technology can be successfully applied to spinal surgery. PMID:7674014

Kalfas, I H; Kormos, D W; Murphy, M A; McKenzie, R L; Barnett, G H; Bell, G R; Steiner, C P; Trimble, M B; Weisenberger, J P

1995-10-01

84

Comparison between bovine bone and titanium interference screws for implant fixation in ACL reconstruction: a biomechanical study  

Microsoft Academic Search

Introduction  The application of interference screws for the fixation of bone-patellar tendon-bone (BPTB) grafts is a well-established technique\\u000a in anterior-cruciate ligament reconstruction. Interference screws derived from bovine compact bone are a biological alternative\\u000a to metallic or biodegradable polymer interference screws.\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods  In 60 porcine specimens, the tibial part of an anterior-cruciate ligament reconstruction was performed using a BPTB graft.\\u000a To

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

2010-01-01

85

Management of Unstable Thoracolumbar Spinal Fractures by Pedicle Screws and Rods Fixation  

PubMed Central

Background: The thoracolumbar junction is the most common area of injury to the axial skeleton. Forces along the long stiff kyphotic thoracic spine switch abruptly into the mobile lordotic lumbar spine at the thoracolumbar junction. Goals of treatment are to obtain a painless, balanced, stable spine with optimum neurological function and maximum spine mobility. The present prospective study has evaluated the effectiveness of pedicle screw instrumentation in various fractures around the TL spine to overcome the complications encountered in the conservative line of management of these fractures. Materials & Methods: Thirty cases of fractures around the TL spine were operated with posterior pedicle screw fixation one or two level above and below the fracture. The cases were followed up for a mean of 9.5 months with radiological and neurological evaluation. Results: The average age groups of the patients studied were 21 to 53 years majority were males, fall from height being the predominant mode of injury involving the T12 and L1 vertebral body. The unstable burst fractures the most common type of fracture, radiological parameters sagittal angle and index were recorded pre and post-operatively. The neurological grading was done using the ASIA score. Follow-up was done for a minimum of 5 months where sagittal angle reduction achieved was 10.75 at final follow-up from 23.5 pre-operative. The sagittal index achieved at final follow-up was 72% compared to the pre-operative mean of 53%. The neurological improvement was regarded to be fair enough for the type of injury sustained and fixation achieved. Conclusion: We found that the application of posterior instrumentation using pedicle screw and rod resulted in a reasonable correction of the deformity with a significant reduction in recumbency-associated complications; the limiting factor being the small study group and short follow-up period. PMID:24701500

B.M., Muralidhar; Hegde, Durgaprasad; Hussain, P.S.B.

2014-01-01

86

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

PubMed Central

Study Design Prospective clinical study. Purpose The present prospective study aims to evaluate the clinical, radiological, and functional and quality of life outcomes in patients with fresh thoracolumbar fractures managed by posterior instrumentation of the spine, using pedicle screw fixation and monosegmental fusion. Overview of Literature The goals of treatment in thoracolumbar fractures are restoring vertebral column stability and obtaining spinal canal decompression, leading to early mobilization of the patient. Methods Sixty-six patients (46 males and 20 females) of thoracolumbar fractures with neurological deficit were stabilized with pedicle screw fixation and monosegmental fusion. Clinical, radiological and functional outcomes were evaluated. Results The mean preoperative values of Sagittal index, and compression percentage of the height of the fractured vertebra were 22.75° and 46.73, respectively, improved (statistically significant) to 12.39°, and 24.91, postoperatively. The loss of correction of these values at one year follow-up was not statistically significant. The mean preoperative canal compromise (%) improved from 65.22±17.61 to 10.06±5.31 at one year follow-up. There was a mean improvement in the grade of 1.03 in neurological status from the preoperative to final follow-up at one year. Average Denis work scale index was 4.1. Average Denis pain scale index was 2.5. Average WHOQOL-BREF showed reduced quality of life in these patients. Patients of early surgery group (operated within 7 days of injury) had a greater mean improvement of neurological grade, radiological and functional outcomes than those in the late surgery group, but it was not statistically significant. Conclusions Posterior surgical instrumentation using pedicle screws with posterolateral fusion is safe, reliable and effective method in the management of fresh thoracolumbar fractures. Fusion helps to decrease the postoperative correction loss of radiological parameters. There is no correlation between radiographic corrections achieved for deformities and functional outcome and quality of life post spinal cord injury. PMID:24967043

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

2014-01-01

87

Fixation strength of a biodegradable interference screw and a press-fit technique in anterior cruciate ligament reconstruction with a BPTB graft  

Microsoft Academic Search

The objective of this study was to evaluate the fixation strength of a biodegradable interference screw (Arthrex, Naples, FL) compared with press fit fixation and a titanium interference screw in anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone (BPTB) graft. Porcine lower limbs were used. Ultimate failure loads of the biodegradable screw (805.2 N; range 680 to 995 N)

Stefan Rupp; Paul W. Krauss; Ekkehard W. Fritsch

1997-01-01

88

Enhanced Lapidus Arthrodesis: Crossed Screw Technique with Middle Cuneiform Fixation Further Reduces Sagittal Mobility.  

PubMed

Persistent medial column sagittal mobility can be encountered despite successful first tarsometatarsal stabilization if fixation has been limited to the first tarsometatarsal joint. The purpose of the present cadaveric research was to quantify the effect of a third point of fixation from the base of the first metatarsal to the middle cuneiform compared with the traditional isolated first tarsometatarsal fixation. Ten matched pairs of below-the-knee specimens, with a known cause of death, sex, ethnicity, and age, height, weight, and body mass index at death, were used for our examination. Portable fluoroscopy aided with the accurate placement of all points of fixation. Measurements of movement were obtained using the validated Klaue device. The 20 matched below-the-knee specimens were from 10 cadavers (2 female and 8 male donors, aged 72.8 ± 9.3 years, body mass index 21.1 ± 4.2 kg/m(2)). The sagittal plane motion of the first ray was 7.45 ± 1.82 mm before fixation. With isolated first tarsometatarsal fixation, the sagittal motion decreased to 4.41 ± 1.51 mm and decreased further to 3.12 ± 1.06 mm, with the addition of middle cuneiform fixation. Statistically significant enhancement of the stability of sagittal first ray motion was noted with the addition of the first metatarsal to middle cuneiform pin, even after simulated Lapidus fixation. Our findings suggest that first metatarsal to middle cuneiform fixation can be beneficial if excessive sagittal motion is present after standard 2-point fixation and can play a role in the prevention of recurrence and complications. PMID:25456344

Galli, Melissa M; McAlister, Jeffrey E; Berlet, Gregory C; Hyer, Christopher F

2014-11-21

89

Superior fixation of pegged trabecular metal over screw-fixed pegged porous titanium fiber mesh  

PubMed Central

Background and purpose Lasting stability of cementless implants depends on osseointegration into the implant surface, and long-term implant fixation can be predicted using radiostereometric analysis (RSA) with short-term follow-up. We hypothesized that there would be improved fixation of high-porosity trabecular metal (TM) tibial components compared to low-porosity titanium pegged porous fiber-metal (Ti) polyethylene metal backings. Methods In a prospective, parallel-group, randomized unblinded clinical trial, we compared cementless tibial components in patients aged 70 years and younger with osteoarthritis. The pre-study sample size calculation was 22 patients per group. 25 TM tibial components were fixed press-fit by 2 hexagonal pegs (TM group) and 25 Ti tibial components were fixed press-fit and by 4 supplemental screws (Ti group). Stereo radiographs for evaluation of absolute component migration (primary effect size) and single-direction absolute component migration (secondary effect size) were obtained within the first postoperative week and at 6 weeks, 6 months, 1 year, and 2 years. American Knee Society score was used for clinical assessment preoperatively, and at 1 and 2 years. Results There were no intraoperative complications, and no postoperative infections or revisions. All patients had improved function and regained full extension. All tibial components migrated initially. Most migration of the TM components (n = 24) occurred within the first 3 months after surgery whereas migration of the Ti components (n = 22) appeared to stabilize first after 1 year. The TM components migrated less than the Ti components at 1 year (p = 0.01) and 2 years (p = 0.004). Interpretation We conclude that the mechanical fixation of TM tibial components is superior to that of screw-fixed Ti tibial components. We expect long-term implant survival to be better with the TM tibial component. PMID:21434781

2011-01-01

90

Bioabsorbable polyglyconate interference screw fixation in anterior cruciate ligament reconstruction: A prospective computed tomography–controlled study  

Microsoft Academic Search

Purpose: It was the purpose of the study to evaluate a new polyglyconate bioabsorbable interference screw for graft fixation in anterior cruciate ligament (ACL) reconstruction. Type of Study: Prospective randomized. Materials and Methods: Forty patients who underwent endoscopic ACL reconstruction were included in the study and randomized intraoperatively. Group A consisted of 20 patients (6 women, 14 men; mean age,

Christian Fink; Karl P. Benedetto; Wolfgang Hackl; Christian Hoser; Martin C. Freund; Michael Rieger

2000-01-01

91

Quadrupled semitendinosus-gracilis autograft fixation in the femoral tunnel: a comparison between a metal and a bioabsorbable interference screw  

Microsoft Academic Search

Although semitendinosus-gracilis (SG) grafts for anterior cruciate ligament reconstruction have many potential benefits, effective fixation remains a challenge. This study assessed differences between the maximum pullout forces needed to detach a quadrupled SG graft from a femoral tunnel when secured by either a metal or a bioabsorbable interference screw. Sixteen paired fresh frozen quadrupled SG autografts (x, 8.4 mm; range,

DNM Caborn; M Coen; R Neef; J Nyland; DL Johnson

1998-01-01

92

Insertion torque pullout strength relationship of soft tissue tendon graft tibia tunnel fixation with a bioabsorbable interference screw  

Microsoft Academic Search

Purpose: The purpose of this study was to evaluate the relationship between insertion torque and the biomechanical characteristics of soft tissue tendon graft tibia fixation with a bioabsorbable interference screw. Type of Study: Biomechanical study. Methods: Doubled tibialis anterior allografts (n = 20, length = 100 mm, diameter = 9 mm) prepared for anterior cruciate ligament (ACL) reconstructions were divided

John Nyland; Yavuz Kocabey; David N. M Caborn

2004-01-01

93

Soft tissue fixation with a cortical button and interference screw: a novel technique in foot and ankle surgery.  

PubMed

Tendon transfers are commonly performed procedures in the foot and ankle. They have been described for multiple tendons and a myriad of pathologies. One issue with these procedures has always been inadequate fixation with several methods available to the surgeon. In this report, we describe a novel technique in foot and ankle surgery using a cortical button and an interference screw. PMID:25534315

Shinabarger, Andrew B; Manway, Jeffrey M; Nowak, Jessica; Burns, Patrick R

2015-02-01

94

The role of computed tomography for postoperative evaluation of percutaneous sacroiliac screw fixation and description of a "safe zone".  

PubMed

We sought to determine whether computed tomography (CT) is an accurate tool for evaluation of reduction, prediction of neurologic deficit, and evaluation of need for revision surgery in unstable pelvic ring injuries treated with percutaneous sacroiliac (SI) screw fixation and whether any neural foramen penetration violation is safe. Using medical records and radiographic data, we retrospectively evaluated 46 patients with 51 fractures or widenings of the SI joint that were surgically treated with percutaneous SI screw fixation, either alone or associated with anterior fixation. Using the Young and Burgess classification, there were 3 vertical shear injuries, 13 lateral compression injuries, 17 anterior-posterior injuries, 7 sacral fractures, and 6 combination or unclassifiable pelvic injuries. Satisfactory reduction was obtained in all cases. All patients had postoperative CT scans, and 23 of 51 screws had some foramen penetration with an average of 3.3 mm (range, 1.4-7.0 mm). After percutaneous screw fixation, 10 of 46 patients had postoperative neurologic deficit, 4 of which were unchanged from preoperative evaluation. Of the 6 patients with new or worsened neurologic deficit, CT showed neural foramen penetration of 2.1 and 7.0 mm in 2 patients. Both patients underwent screw revision, resulting in improved neurologic deficit. The remaining 4 patients did not have foramen penetration; their neurologic function improved, with full return at 6 weeks without screw removal. Neural foramen penetration documented with CT did not correlate with neurologic deficit unless the penetration was greater than 2.7 mm. Postoperative CT showing neural foramen penetration was the cause of revision surgery in 2 of 10 patients with postoperative neurologic deficit after percutaneous SI screw fixation. Based on these findings, we recommend postoperative CT only in those cases where there is new neurologic deficit and screw removal if foramen penetration is greater than 2.1 mm. We also describe a new "safe zone" for screw insertion encompassing the superior 2 mm of the sacral foramen with adequate pelvic reduction. PMID:25379748

Tejwani, Nirmal C; Raskolnikov, Dima; McLaurin, Toni; Takemoto, Richelle

2014-11-01

95

The effect of screw fixation type on a modular hemi-pelvic prosthesis: a 3-D finite element model.  

PubMed

In this article, a 3-D finite element (FE) model of human pelvic with a modular hemi-pelvic prosthesis was constructed to study the effect of screw fixation type on the biomechanics of the prosthesis. The results showed that the elimination of the screw far away from the pelvic arcuate line did not induce the instability and stress increase in the prosthesis. On the contrary, some stress in the sustain and acetabular parts decreased by 26.4% and 11.4%, respectively. In conclusion, the optimization of screw fixation can maintain the prosthesis stability and reduced stress concentration on some prosthesis parts. It was deduced that the optimization of the prosthesis could help surgeon reconstruct the pelvic joint function better and diminish the clinical time and cost. PMID:23244444

Hao, Zhixiu; Wan, Chao; Gao, Xiangfei; Ji, Tao; Wang, Haosen

2013-03-01

96

Polymer cable/grip-plate system with locking screws for stable fixation to promote healing of trochanteric osteotomies or fractures in revision total hip arthroplasty.  

PubMed

Multiple methods have been proposed to establish stable fixation to promote healing of trochanteric osteotomies or fractures in revision total hip arthroplasty (revTHA), from wiring techniques through cable-plate systems with or without supplemental locking screws. The purpose of this study is to report the clinical results of a single cable-plate system with locked screw fixation in revTHA. Between 2009 and 2012, 27 grip-plates (Supercable® System, Kinamed Inc., Camarillo, CA) were used in 26 patients in 27 revTHA procedures. Utilization was 12 1-hole (50 mm) grip-plates, 10 2-hole (135 mm) grip-plates, four 4-hole (190 mm) grip-plates, and one 6-hole (245 mm) grip-plate. There were 14 women and 12 men. Age averaged 63.2 years and BMI averaged 29.4 kg/m2. At average 2.5 year follow-up, grip-plate fixation was considered successful in 22 hips (81%) with five failures. Three failures consisted of 50 mm/short grip-plates used in one trochanteric slide, and two intraoperative trochanteric fractures during revTHA. The two additional failures were related to pre-revision trochanteric avulsion from bony necrosis of the proximal femur. An additional three grip-plates were removed electively for soft-tissue irritation and pain but with successful fixation and bony healing. Thus 70% of hips were free of reoperation related to the grip-plate. All other hips had successful fixation and the grip-plate was not symptomatic. In this study, the cable-grip system and isoelastic Supercables provided reliable fixation for adequate healing of difficult ETO and trochanteric fractures with an 81% rate of mechanical success with radiographic and clinical healing observed. PMID:25398403

Berend, Keith R; Willen, Jacob L; Morris, Michael J; Adams, Joanne B; Lombardi, Adolph V

2014-11-01

97

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

PubMed

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

Chaudhary, Zainab; Sharma, Rakesh; Krishnan, Sriram

2014-06-01

98

Screw fixation is superior to N-butyl-2-cyanoacrylate in onlay grafting procedure: a histomorphologic study.  

PubMed

The aim of this study is the histopathological evaluation of the efficiency of N-2-butyl cyanoacrylate in the fixation of bone block grafts on mandible. Autogenous monocortical block grafts taken from tibial bone were fixed to the outer surface of the angle of the mandible with N-2-butyl cyanoacrylate on the right side and mini screws on the left side. Postoperatively in the first and third months, six rabbits were killed and tissue samples were obtained from the grafted area. No significant difference was found between the cyanoacrylate and screw group with respect to inflammation or foreign body reaction. The level of graft necrosis was found to be significantly higher in the cyanoacrylate group than in the screw group in both the first and third month samples. Bone formation between the graft and recipient bone was evaluated and bone formation was found to be significantly higher in the screw group than in the cyanoacrylate group. No trabecular bone formation was observed between the graft and recipient bone in the cyanoacrylate group. Screw fixation was found to be superior to N-2-butyl cyanoacrylate in all parameters. PMID:22113114

Ba?, B; Ozden, B; Bekçio?lu, B; Sanal, K O; Gülbahar, M Y; Kabak, Y B

2012-04-01

99

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

PubMed Central

Background Studies of syndesmosis injuries have concentrated on cadaver models. However, they are unable to obtain exact data regarding the stress and displacement distribution of various tissues, and it is difficult to compare models. We investigated the biomechanical effects of inferior tibiofibular syndesmosis injuries (ITSIs) and screw fixation on the ankle using the finite element (FE) method. Methodology/Principal Findings A three-dimensional model of a healthy ankle complex was developed using computed tomography (CT) images. We established models of an ITSI and of screw fixation at the plane 2.5 cm above and parallel to the tibiotalar joint surface of the injured syndesmosis. Simulated loads were applied under three conditions: neutral position with single-foot standing and internal and external rotation of the ankle. ITSI reduced contact forces between the talus and fibula, helped periarticular ankle ligaments withstand more load-resisting movement, and increased the magnitude of displacement at the lower extreme of the tibia and fibula. ITSI fixation with a syndesmotic screw reduced contact forces in all joints, decreased the magnitude of displacement at the lower extreme of the tibia and fibula, and increased crural interosseous membrane stress. Conclusions/significance Severe syndesmosis injuries cause stress and displacement distribution of the ankle to change multidirectional ankle instability and should be treated by internal fixation. Though the transverse syndesmotic screw effectively stabilizes syndesmotic diastasis, it also changes stress distribution around the ankle and decreases the joint's range of motion (ROM). Therefore, fixation should not be performed for a long period of time because it is not physiologically suitable for the ankle joint. PMID:24312464

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

2013-01-01

100

A Meta-Analysis of Unilateral versus Bilateral Pedicle Screw Fixation in Minimally Invasive Lumbar Interbody Fusion  

PubMed Central

Study Design Meta-analysis. Background Bilateral pedicle screw fixation (PS) after lumbar interbody fusion is a widely accepted method of managing various spinal diseases. Recently, unilateral PS fixation has been reported as effective as bilateral PS fixation. This meta-analysis aimed to comparatively assess the efficacy and safety of unilateral PS fixation and bilateral PS fixation in the minimally invasive (MIS) lumbar interbody fusion for one-level degenerative lumbar spine disease. Methods MEDLINE/PubMed, EMBASE, BIOSIS Previews, and Cochrane Library were searched through March 30, 2014. Randomized controlled trials (RCTs) and controlled clinical trials (CCTs) on unilateral versus bilateral PS fixation in MIS lumbar interbody fusion that met the inclusion criteria and the methodological quality standard were retrieved and reviewed. Data on participant characteristics, interventions, follow-up period, and outcomes were extracted from the included studies and analyzed by Review Manager 5.2. Results Six studies (5 RCTs and 1 CCT) involving 298 patients were selected. There were no significant differences between unilateral and bilateral PS fixation procedures in fusion rate, complications, visual analogue score (VAS) for leg pain, VAS for back pain, Oswestry disability index (ODI). Both fixation procedures had similar length of hospital stay (MD?=?0.38, 95% CI?=??0.83 to 1.58; P?=?0.54). In contrast, bilateral PS fixation was associated with significantly more intra-operative blood loss (P?=?0.002) and significantly longer operation time (P?=?0.02) as compared with unilateral PS fixation. Conclusions Unilateral PS fixation appears as effective and safe as bilateral PS fixation in MIS lumbar interbody fusion but requires less operative time and causes less blood loss, thus offering a simple alternative approach for one-level lumbar degenerative disease. PMID:25375315

Liu, Zheng; Fei, Qi; Wang, Bingqiang; Lv, Pengfei; Chi, Cheng; Yang, Yong; Zhao, Fan; Lin, Jisheng; Ma, Zhao

2014-01-01

101

[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

102

Comparison of “inside-out” and “outside-in” interference screw fixation for anterior cruciate ligament surgery in a bovine knee  

Microsoft Academic Search

Despite numerous advances in graft fixation with anterior cruciate ligament (ACL) reconstruction, few studies have compared the fixation strength of interference screws placed “outside-in” and from “inside-out” techniques. To compare techniques, a bovine model was designed to fail at the femoral tunnel bone-screw interface. Twenty-four fresh bovine knees were stripped of all soft tissues except the ACL. The native ACL

James M. Bryan; Bernard R. Bach; Charles A. Bush-Joseph; Ian M. Fisher; K. Y. Hsu

1996-01-01

103

Treatment of neuromuscular scoliosis with posterior-only pedicle screw fixation  

PubMed Central

Background To determine whether posterior-only approach using pedicle screws in neuromuscular scoliosis population adequately addresses the correction of scoliosis and maintains the correction over time. Methods Between 2003 and 2006, 26 consecutive patients (7 cerebral palsy, 10 Duchenne muscular dystrophy, 5 spinal muscular atrophy and 4 others) with neuromuscular scoliosis underwent posterior pedicle screw fixation for the deformity. Preoperative, immediate postoperative and final follow-up Cobb's angle and pelvic obliquity were analyzed on radiographs. The average age of the patients was 17.5 years (range, 8–44 years) and the average follow-up was 25 months (18–52 months). Results Average Cobb's angle was 78.53° before surgery, 30.70° after surgery (60.9% correction), and 33.06° at final follow-up (57.9% correction) showing significant correction (p < 0.0001). There were 9 patients with curves more than 90° showed an average pre-operative, post operative and final follow up Cobb's angle 105.67°, 52.33° (50.47% correction) and 53.33° (49.53% correction) respectively and 17 patients with curve less than 90° showed average per operative, post operative and final follow up Cobb's angle 64.18, 19.24(70% correction) and 21.41(66.64 correction); which suggests statistically no significant difference in both groups (p = 0.1284). 7 patients underwent Posterior vertebral column resection due to the presence of a rigid curve. The average spinal-pelvic obliquity was 16.27° before surgery, 8.96° after surgery, and 9.27° at final follow-up exhibited significant correction (p < 0.0001). There was 1 poliomyelitis patient who had power grade 3 in lower limbs pre-operatively, developed grade 2 power post-operatively and gradually improved to the pre-operative stage. There was 1 case of deep wound infection and no case of pseud-arthrosis, instrument failures or mortality. Conclusion Results indicate that in patients with neuromuscular scoliosis, acceptable amounts of curve correction can be achieved and maintained with posterior-only pedicle screw instrumentation without anterior release procedure. PMID:18544164

Modi, Hitesh N; Suh, Seung-Woo; Song, Hae-Ryong; Fernandez, Harry M; Yang, Jae-Hyuk

2008-01-01

104

Titanium-alloy enhances bone-pedicle screw fixation: mechanical and histomorphometrical results of titanium-alloy versus stainless steel  

Microsoft Academic Search

Several types of pedicle screw systems have been utilized to augment lumbar spine fusion. The majority of these systems are\\u000a made of stainless steel (Ss), but titanium-alloy (Ti-alloy) devices have recently been available on the market. Ti-alloy implants\\u000a have several potential advantages over Ss ones. High bioactivity and more flexibility may improve bone ingrowth and mechanical\\u000a fixation, and the material

Finn Bjarke Christensen; Michel Dalstra; Flemming Sejling; Søren Overgaard; Cody Bünger

2000-01-01

105

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

PubMed Central

Introduction: The aim of this study was to examine resistance to angulation and displacement of the internal fixation of a proximal first metatarsal lateral displacement osteotomy, using a locking plate system compared with a conventional crossed screw fixation. Materials and Methodology: Seven anatomical human specimens were tested. Each specimen was tested with a locking screw plate as well as a crossed cancellous srew fixation. The statistical analysis was performed by the Friedman test. The level of significance was p = 0.05. Results: We found larger stability about all three axes of movement analyzed for the PLATE than the crossed screws osteosynthesis (CSO). The Friedman test showed statistical significance at a level of p = 0.05 for all groups and both translational and rotational movements. Conclusion: The results of our study confirm that the fixation of the lateral proximal first metatarsal displacement osteotomy with a locking plate fixation is a technically simple procedure of superior stability. PMID:22675409

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

2012-01-01

106

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

PubMed Central

A case of lytic lesion of the pelvis in a 23-year-old woman is presented. A biopsy led to the diagnosis aneurysmal bone cyst (ABC). Due to the histologically very aggressive growth of the tumor, a low malignant osteosarcoma could not be excluded. In an initial operation the tumour, affecting the sacrum, the iliac crest and the lower lumbar spine was resected. Temporary restabilisation of the pelvic ring was achieved by a titanium plate. The histological examination of the entire tumour confirmed the diagnosis ABC. After 6 months, the MRI showed no recurrence. The observed tilt of the spine to the operated side on the sacral base prompted a second surgical procedure: a transpedicular fixation of L5 and L4 was connected via bent titanium stems to the ischium, where the fixation was achieved by two screws. This construction allowed the correction of the base angle and yielded a stable closure of the pelvic ring. The patient has now been followed for 6 years: the bone grafts have been incorporated and, in spite of radiological signs of screw loosening in the ischium, the patient is fully rehabilitated and free of symptoms. Pedicle screws in the lower spine can be recommended for fixation of a pelvic ring discontinuity. PMID:18521384

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

2003-01-01

107

Guided bone regeneration technique in the esthetic zone: a novel approach using resorbable PLLA-PGA plates and screw fixation. A case report.  

PubMed

The use of biodegradable fixation materials or devices during maxillofacial, craniofacial, and orthopedic reconstructive surgical procedures reduces or eliminates the need to perform a second surgical procedure, which would otherwise be required to remove a nonbiodegradable device. This article presents a novel approach to augment a horizontally deficient alveolar ridge using both a resorbable plate/screw fixation system composed of a polylactic acid-polyglycolic acid (PLLA-PGA) copolymer to provide a rigid scaffolding for the bone chips and a resorbable collagen barrier (Bio-Gide, Osteohealth) to secure the graft material. For periodontal reconstructive procedures, such as guided bone regeneration, the clinical application of this technique may be advantageous and also provide a more esthetic result by minimizing the need for an additional surgical procedure. (Int J Periodontics Restorative Dent 2009;29:543-547.). PMID:19888498

Fabbri, Giacomo; Brennan, Myra; Manfredi, Massimiliano; Ban, Georgio

2009-10-01

108

Analysis of failure following anterior screw fixation of Type II odontoid fractures in geriatric patients.  

PubMed

Anterior screw fixation of Type II odontoid fractures has been recommended. Only few publications analyse the mechanism of failure in geriatric patients. We reviewed 18 male and 15 female patients aged 65 and above for parameters that influence the development of postoperative loss of correction, delayed union or non-union. Patients were stratified in two groups: 21 cases in Group A (union) and 12 patients in Group B (loss of correction, delayed union, non-union, revision surgery). Statistically significant correlation (p < 0.05) could be detected between failure to heal and: (1) degenerative changes in the atlanto-odontoid joint, (2) severity of osteoporosis in the odontoid process, (3) posterior oblique fracture type, (4) suboptimal fracture reduction, (5) suboptimal position of implant following demanding intraoperative conditions, (6) quality of fracture compression and (7) severity of fracture comminution. The overall morbidity and mortality rates were 29.0 and 8.6%, respectively. Our results indicate that these factors should be addressed regarding the selection of the operative treatment method in the geriatric patient. PMID:21728075

Osti, Michael; Philipp, Helmut; Meusburger, Berthold; Benedetto, Karl Peter

2011-11-01

109

Internal reduction established by occiput-C2 pedicle polyaxial screw stabilization in pediatric atlantoaxial rotatory fixation.  

PubMed

Atlantoaxial rotatory fixation is an uncommon disorder of childhood, which can be treated conservatively when diagnosed early. Although spontaneous correction occasionally occurs, most of the patients usually benefit from collar or traction therapies. If there is no intervention or if all external therapeutic modalities fail, the deformity may become chronic and irreducible. In such rare cases, surgical correction and stabilization are needed to prevent future head and neck deformity or facial asymmetry. In this report we describe a novel surgical technique used in a pediatric case presenting with delayed type 2 atlantoaxial rotatory fixation, in whom all external reduction methods had failed. The patient's deformity was treated by occiput-C2 pedicle polyaxial screw stabilization. This technique is effective for reducing the atlantoaxial fixation in children. PMID:16902349

Belen, Deniz; Simsek, Serkan; Yigitkanli, Kazim; Bavbek, Murad

2006-01-01

110

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

PubMed Central

Minimally invasive surgery with a transforaminal lumbar interbody fusion (MIS TLIF) is an important minimally invasive fusion technique for the lumbar spine. Lumbar spine reoperation is challenging and is thought to have greater complication risks. The purpose of this study was to compare MIS TLIF with unilateral screw fixation perioperative results between primary and revision surgeries. This was a prospective study that included 46 patients who underwent MIS TLIF with unilateral pedicle screw. The patients were divided into two groups, primary and revision MIS TLIF, to compare perioperative results and complications. The two groups were similar in age, sex, and level of operation, and were not significantly different in the length of follow-up or clinical results. Although dural tears were more common with the revision group (primary 1; revision 4), operation time, blood loss, total perioperative complication, and fusion rates were not significantly different between the two groups. Both groups showed substantial improvements in VAS and ODI scores one year after surgical treatment. Revision MIS TLIF performed by an experienced surgeon does not necessarily increase the risk of perioperative complication compared with primary surgery. MIS TLIF with unilateral pedicle screw fixation is a valuable option for revision lumbar surgery. PMID:24949483

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

2014-01-01

111

Three-dimensional image navigation system-assisted anterior cervical screw fixation for treatment of acute odontoid fracture  

PubMed Central

This study is to investigate the role of three-dimensional image navigation system for surgical treatment of odontoid fracture. A total of 21 patients were enrolled in this study. The anterior cervical hollow screw fixation was performed for treatment of acute odontoid fracture under monitoring of isocentric C-arm three-dimensional navigation system (Iso-C 3D) navigation system. The postoperative follow-up investigation duration was 13.8 ± 4.4 months. Twenty patients with odontoid fracture had bone union without intraoperative and postoperative complications. No loosening, dislocation or fracture of screw occurred. The average healing time was from 3 to 4 months. The cervical postoperative organ function evaluation of patients was scored by Smiley-Webster scoring methods. Eighteen cases were scored as excellent; 2 cases were scored as fine; 1 case was scored as good; and no case was scored as poor. Iso-C 3D image navigation system-assisted anterior cervical screw fixation is an effective approach for treatment of odontoid fracture.

Zou, Debo; Zhang, Kaining; Ren, Yanjun; Wu, Yingguang; Yang, Yun; Li, Yu

2014-01-01

112

Interference Screw Fixation of Soft Tissue Grafts in Anterior Cruciate Ligament Reconstruction: Part 1Effect of Tunnel Compaction by Serial Dilators Versus Extraction Drilling on the Initial Fixation Strength  

Microsoft Academic Search

Background:Compaction of the bone-tunnel walls by serial dilation is believed to enhance the interference screw fixation strength of the soft tissue grafts in anterior cruciate ligament (ACL) reconstruction.Hypothesis:Serial dilation enhances the fixation strength of soft tissue grafts in ACL reconstruction over extraction drilling.Study Design:Randomized experimental study.Methods:Initial fixation strength of the doubled anterior tibialis tendon grafts (fixed with a bioabsorbable interference

Janne T. Nurmi; Pekka Kannus; Harri Sievänen; Timo Järvelä; Markku Järvinen; Teppo L. N. Järvinen

2004-01-01

113

C1-C3 Lateral Mass Screw-Rod Fixation and Fusion for C2 Pathologies and Hangman's Fractures  

PubMed Central

Study Design Retrospective clinical study. Purpose We report our experience of eight patients treated with C1-C3 lateral mass rod-screw stabilization and fusion in the treatment of Hangman's fracture and other axis pathologies. Overview of Literature Different surgical approaches, both anterior and posterior, have been described for treating Hangman's fracture and other pathologies where surgery is indicated. Methods All patients who underwent surgical treatment for Hangman's fracture and axial pathology where C1-C3 lateral mass screw-rod stabilization and fusion done, following reduction of the fracture or removal of the pathology were included in this series. The recorded patient management data was retrospectively studied. Results There were 8 cases in total. All were male, with an average age of 40.75 years. Hangman's fracture occurred in 6 cases (75%), one with metastatic squamous cell carcinoma and the remaining with plasmocytoma. Among the Hangman's fractures 4 (66.66%) had no neuro-deficit. Reduction and bilateral C1-C3 lateral mass screw and rod fixation with posterior fusion by bone graft was performed in all cases. In 2 cases, a C2 body tumor was removed transorally. All patients with neuro-deficit fully recovered, except one who expired in the early post-operative period. Rest of all patients were leading a normal life till last follow up. Conclusions Although the number of cases was very small with a relatively short follow up period, C1 and C3 lateral mass screw-rod fixation followed by fusion showed promise as an effective and biomechanically sound way for the treatment of properly selected Hangman's fracture cases, and may also be suitable in other axial pathologies.

Haque, Mohammod Raziul

2014-01-01

114

Direct Pars Repair Surgery Using Two Different Surgical Methods : Pedicle Screw with Universal Hook System and Direct Pars Screw Fixation in Symptomatic Lumbar Spondylosis Patients  

PubMed Central

Objective The authors performed a retrospective study to assess the clinical and radiological outcome in symptomatic lumbar spondylolysis patients who underwent a direct pars repair surgery using two different surgical methods; pedicle screw with universal hook system (PSUH) and direct pars screw fixation (DPSF), and compared the results between two different treated groups. Methods Forty-seven consecutive patients (PSUH; 23, DPSF; 15) with symptomatic lumbar spondylolysis who underwent a direct pars repair surgery were included. The average follow-up period was 37 months in the PSUH group, and 28 months in the DPSF group. The clinical outcome was measured using visual analogue pain scale (VAS) and Oswestry disability index (ODI). The length of operation time, the amount of blood loss, the duration of hospital stay, surgical complications, and fusion status were also assessed. Results When compared to the DPSF group, the average preoperative VAS and ODI score of the PSUH group were less decreased at the last follow-up; (the PSUH group; back VAS : 4.9 vs. 3.0, leg VAS : 6.8 vs. 2.2, ODI : 50.6% vs. 24.6%, the DPSF group; back VAS : 5.7 vs. 1.1, leg VAS : 6.1 vs. 1.2, ODI : 57.4% vs. 18.2%). The average operation time was 174.9 minutes in the PSUH group, and 141.7 minutes in the DPSF group. The average blood loss during operation was 468.8 cc in the PSUH group, and 298.8 cc in the DPSF group. The average hospital stay after operation was 8.9 days in the PSUH group, and 7 days in the DPSF group. In the PSUH group, there was one case of a screw misplacement requiring revision surgery. In the DPSF group, one patient suffered from transient leg pain. The successful bone fusion rate was 78.3% in the PSUH group, and 93.3% in the DPSF group. Conclusion The present study suggests that the technique using direct pars screw would be more effective than the method using pedicle screw with lamina hook system, in terms of decreased operation time, amount of blood loss, hospital stay, and increased fusion success rate, as well as better clinical outcome. PMID:22396837

Shin, Myung-Hoon; Rathi, Nitesh Kumar; Park, Chun-Kun

2012-01-01

115

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

PubMed Central

Background Currently, Posterior Short Segment Pedicle Screw Fixation is a popular procedure for treating unstable thoracolumbar/lumbar burst fracture. But progressive kyphosis and a high rate of hardware failure because of lack of the anterior column support remains a concern. The efficacy of different methods remains debatable and each technique has its advantages and disadvantages. Methods A consecutive series of 20 patients with isolated thoracolumbar/lumbar burst fractures were treated by posterior short segment pedicle screw fixation and transforaminal thoracolumbar/lumbar interbody fusion (TLIF) between January 2005 and December 2007. All patients were followed up for a minimum of 2 years. Demographic data, neurologic status, anterior vertebral body heights, segmental Cobb angle and treatment-related complications were evaluated. Results The mean operative time was 167 minutes (range, 150–220). Blood loss was 450 ~ 1200 ml, an average of 820 ml. All patients recovered with solid fusion of the intervertebral bone graft, without main complications like misplacement of the pedicle screw, nerve or vessel lesion or hard ware failure. The post-operative radiographs demonstrated a good fracture reduction and it was well maintained until the bone graft fusion. Neurological recovery of one to three Frankel grade was seen in 14 patients with partial neurological deficit, three grades of improvement was seen in one patient, two grades of improvement was observed in 6 patients and one grade of improvement was found in 6 patients. All the 6 patients with no paraplegia on admission remained neurological intact, and in one patient with Frankel D on admission no improvement was observed. Conclusion Posterior short-segment pedicle fixation in conjunction with TLIF seems to be a feasible option in the management of selected thoracolumbar/lumbar burst fractures, thereby addressing all the three columns through a single approach with less trauma and good results. PMID:24517217

2014-01-01

116

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

117

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

118

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

Microsoft Academic Search

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

Antonio Herrera; Fernando Martínez; Daniel Iglesias; José Cegoñino; Elena Ibarz; Luis Gracia

2010-01-01

119

Initial fixation strength of bioabsorbable and titanium interference screws in anterior cruciate ligament reconstruction. Biomechanical evaluation by single cycle and cyclic loading.  

PubMed

We evaluated the initial bone-patellar tendon-bone graft fixation strength of bioabsorbable as compared with titanium interference screws in anterior cruciate ligament reconstruction using matched pairs of porcine knees. Ten pairs underwent single-cycle failure loading at a rate of 50 mm/min, and 10 pairs underwent cyclic loading at half-hertz frequency. The cyclic loading started with 100 load cycles between 50 and 150 N. We then progressively increased loads in 50-N increments after each set of 100 cycles. After 100 cycles at 850 N, the specimens were loaded to failure at a rate of 50 mm/min. In the single-cycle failure loading test, the mean ultimate failure loads (+/-SD) for the bioabsorbable (837 +/- 260 N) and titanium interference screws (863 +/- 192 N) were not significantly different, nor were the mean yield loads or the stiffness of the fixation. In the cyclic loading test, the yield loads were 605 +/- 142 N and 585 +/- 103 N for the bioabsorbable and titanium interference screws, respectively (no significant difference). Although there was no significant difference in the ultimate failure load, more bone block fractures were found in the grafts fixed with a titanium interference screw. Bioabsorbable interference screw fixation thus seems to provide a reasonable alternative to titanium screws. PMID:11476379

Kousa, P; Järvinen, T L; Kannus, P; Järvinen, M

2001-01-01

120

Posterior occipito-axial fixation applied C2 laminar screws for pediatric atlantoaxial instability caused by Down syndrome: Report of 2 cases  

PubMed Central

Background Upper cervical spine instability is one of the most critical orthopedic problems in patients with Down syndrome. However, arthrodesis of the upper cervical spine in these patients can be very difficult to achieve and has a high complication rate because of mental retardation and accompanying various medical conditions of the vital organs. Even now, surgeries in such patients, especially pediatric cases, are challenging and the optimal operative procedure remains unsettled. The purpose of this study was to report 2 cases of pediatric atlantoaxial instability due to Down syndrome in which posterior occipito-axial fixation with C2 laminar screws was performed. Methods Case 1 was a girl aged 6 years 10 months who had atlantoaxial rotatory fixation with os odontoideum. Atlantoaxial rotatory fixation was incompletely reduced by halo traction, and it was not maintained without halo-ring and -vest fixation. Posterior occipito-axial fixation with bilateral C2 laminar screws was then performed. Case 2 was a boy aged 10 years 7 months who had atlantoaxial subluxation with os odontoideum. He also had incomplete quadriplegia, so he could neither walk nor have a meal by himself. Posterior occipito-axial fixation with right C2 pedicle and left C2 laminar screws was then carried out. Results In case 1 bone union was obtained at 3 months after surgery and the patient's symptoms were resolved. In case 2 bone union was obtained at 3 months after surgery and the paralysis was improved. Conclusions/level of evidence In cases of atlantoaxial instability due to Down syndrome, symptomatic patients often present between ages 5 and 15 years and mental retardation interferes with postoperative cervical immobilization. C2 laminar screws can be safely applied for the pediatric axis and biomechanically accomplished rigid fixation. The C2 laminar screw is one of the most useful options to achieve stability of the pediatric atlantoaxial complex without the risk of vertebral artery injuries (level IV case series).

Kuroki, Hiroshi; Kubo, Shinichiro; Hamanaka, Hideaki; Chosa, Etsuo

2012-01-01

121

Lag screws for hip fracture fixation: Evaluation of migration resistance under simulated walking  

Microsoft Academic Search

Previous mechanical studies concerning cut-out of lag screws for pertrochanteric hip fractures have relied on static or dynamic uniaxial loading regimens to induce construct failure by varus collapse and superior cut-out. However, the hip is loaded in a mul- tiplanar, dynamic manner during normal gait. We designed a hip implant performance simulator (HIPS) system to evaluate lag screw cut-out under

Larry W. Ehmke; Daniel C. Fitzpatrick; James C. Krieg; Steven M. Madey; Michael Bottlang

2005-01-01

122

The Radiological Feature of Anterior Occiput-to-Axis Screw Fixation as it Guides the Screw Trajectory on 3D Printed Models: A Feasibility Study on 3D Images and 3D Printed Models.  

PubMed

Anterior occiput-to-axis screw fixation is more suitable than a posterior approach for some patients with a history of posterior surgery. The complex osseous anatomy between the occiput and the axis causes a high risk of injury to neurological and vascular structures, and it is important to have an accurate screw trajectory to guide anterior occiput-to-axis screw fixation.Thirty computed tomography (CT) scans of upper cervical spines were obtained for three-dimensional (3D) reconstruction. Cylinders (1.75?mm radius) were drawn to simulate the trajectory of an anterior occiput-to-axis screw. The imitation screw was adjusted to 4 different angles and measured, as were the values of the maximized anteroposterior width and the left-right width of the occiput (C0) to the C1 and C1 to C2 joints. Then, the 3D models were printed, and an angle guide device was used to introduce the screws into the 3D models referring to the angles calculated from the 3D images.We found the screw angle ranged from ?1 (left: 4.99?±?4.59°; right: 4.28?±?5.45°) to ?2 (left: 20.22?±?3.61°; right: 19.63?±?4.94°); on the lateral view, the screw angle ranged from ?1 (left: 13.13?±?4.93°; right: 11.82?±?5.64°) to ?2 (left: 34.86?±?6.00°; right: 35.01?±?5.77°). No statistically significant difference was found between the data of the left and right sides. On the 3D printed models, all of the anterior occiput-to-axis screws were successfully introduced, and none of them penetrated outside of the cortex; the mean ?4 was 12.00?±?4.11 (left) and 12.25?±?4.05 (right), and the mean ?4 was 23.44?±?4.21 (left) and 22.75?±?4.41 (right). No significant difference was found between ?4 and ?4 on the 3D printed models and ?3 and ?3 calculated from the 3D digital images of the left and right sides.Aided with the angle guide device, we could achieve an optimal screw trajectory for anterior occiput-to-axis screw fixation on 3D printed C0 to C2 models. PMID:25526447

Wu, Ai-Min; Wang, Sheng; Weng, Wan-Qing; Shao, Zhen-Xuan; Yang, Xin-Dong; Wang, Jian-Shun; Xu, Hua-Zi; Chi, Yong-Long

2014-12-01

123

Occiput/C1-C2 fixations using intra-laminar screw of axis - A long-term follow-up.  

PubMed

Background. The surgical management of the craniocervical junction is challenging. Rigid posterior fixation of occiput/C1-C2 can be performed using a variety of surgical techniques including C2 pedicle/pars interarticularis, transarticular and intralaminar screw fixations. Methods. Forty-one patients were treated with occipital plate/C1 lateral mass and C2 intra-laminar screw fixations for basilar invagination and congenital atlantoaxial subluxation, post-traumatic instability, tuberculous and rheumatoid arthritis-associated atlantoaxial dislocation. Out of forty-one, thirty-six patients had bilateral crossing intra-laminar screws and five had ipsilateral laminar screw fixation bilaterally. Results. Follow-up was done in thirty-nine patients from 6 months to 8 years (mean: 21 months) and solid osseous fusion could be achieved in all (100%). One patient was lost to follow-up and another patient died of a cause unrelated to surgical technique. Pre-operative and post-operative Neurosurgical Cervical Spine Scale showed improvement in all patients having features of myelopathy. There were no neurological or vascular complications. However, nine patients had posterior laminar breach, eight had anterior laminar penetrations and three had wound infections. One patient had transient bulbar palsy and one patient had hardware failure in the form of avulsion of the midline occipital plate. Conclusions. Intra-laminar screw fixation is a safe alternative to transarticular and transpedicular/pars interarticularis fixation of C2 with advantage of having no risk of injury to vertebral artery and comparable biomechanical and pull-out strength. PMID:25472926

Sinha, Sanjiv; Jagetia, Anita; Aher, Rajendra B; Butte, Manoj Kumar V

2014-12-01

124

Biomechanical analysis of screw constructs for atlantoaxial fixation in cadavers: a systematic review and meta-analysis.  

PubMed

OBJECT The unique and complex biomechanics of the atlantoaxial junction make the treatment of C1-2 instability a challenge. Several screw-based constructs have been developed for atlantoaxial fixation. The biomechanical properties of these constructs have been assessed in numerous cadaver studies. The purpose of this study was to systematically review the literature on the biomechanical stability achieved using various C1-2 screw constructs and to perform a meta-analysis of the available data. METHODS A systematic search of PubMed through July 1, 2013, was conducted using the following key words and Boolean operators: "atlanto [all fields]" AND "axial [all fields]" OR "C1-C2" AND "biomechanic." Cadaveric studies on atlantoaxial fixation using screw constructs were included. Data were collected on instability models, fixation techniques, and range of motion (ROM). Forest plots were constructed to summarize the data and compare the biomechanical stability achieved. RESULTS Fifteen articles met the inclusion criteria. An average (± SD) of 7.4 ± 1.8 cadaveric specimens were used in each study (range 5-12). The most common injury models were odontoidectomy (53.3%) and cervical ligament transection (26.7%). The most common spinal motion segments potted for motion analysis were occiput-C4 (46.7%) and occiput-C3 (33.3%). Four screw constructs (C1 lateral mass-C2 pedicle screw [C1LM-C2PS], C1-2 transarticular screw [C1-C2TA], C1 lateral mass-C2 translaminar screw [C1LM-C2TL], and C1 lateral mass-C2 pars screw [C1LM-C2 pars]) were assessed for biomechanical stability in axial rotation, flexion/extension, and lateral bending, for a total of 12 analyses. The C1LM-C2TL construct did not achieve significant lateral bending stabilization (p = 0.70). All the other analyses showed significant stabilization (p < 0.001 for each analysis). Significant heterogeneity was found among the reported stabilities achieved in the analyses (p < 0.001; I(2) > 80% for all significant analyses). The C1LM-C2 pars construct achieved significantly less axial rotation stability (average ROM 36.27° [95% CI 34.22°-38.33°]) than the 3 other constructs (p < 0.001; C1LM-C2PS average ROM 49.26° [95% CI 47.66°-50.87°], C1-C2TA average ROM 47.63° [95% CI 45.22°-50.04°], and C1LM-C2TL average ROM 53.26° [95% CI 49.91°-56.61°]) and significantly more flexion/extension stability (average ROM 13.45° [95% CI 10.53°-16.37°]) than the 3 other constructs (p < 0.001; C1LM-C2PS average ROM 9.02° [95% CI 8.25°-9.80°], C1-C2TA average ROM 7.39° [95% CI 5.60°-9.17°], and C1LM-C2TL average ROM 7.81° [95% CI 6.93°-8.69°]). The C1-C2TA (average ROM 5.49° [95% CI 3.89°-7.09°]) and C1LM-C2 pars (average ROM 4.21° [95% CI 2.19°-6.24°]) constructs achieved significantly more lateral bending stability than the other constructs (p < 0.001; C1LM-C2PS average ROM 1.51° [95% CI 1.23°-1.78°]; C1LM-C2TL average ROM -0.07° [95% CI -0.44° to 0.29°]). CONCLUSIONS Meta-analysis of the existing literature showed that all constructs provided significant stabilization in all axes of rotation, except for the C1LM-C2TL construct in lateral bending. There were significant differences in stabilization achieved in each axis of motion by the various screw constructs. These results underline the various strengths and weaknesses in biomechanical stabilization of different screw constructs. There was significant heterogeneity in the data reported across the studies. Standardized spinal motion segment configuration and injury models may provide more consistent and reliable results. PMID:25478824

Du, Jerry Y; Aichmair, Alexander; Kueper, Janina; Wright, Timothy; Lebl, Darren R

2014-12-01

125

Analysis of Orthopedic Screws for Bone Fracture Fixations with Finite Element Method  

NASA Astrophysics Data System (ADS)

In this study, the influence of the orthopedic screws engineering design such as profile shape and geometrical parameters on its biomechanical compatibility in terms of load sharing with adjacent bone tissue was investigated. The study was conducted on a set of three-dimensional finite element design models. A dimension less Stress Transfer Parameter (STP) was utilized for gauging the performances of the different screws according to its load sharing capabilities. Stress-transfer behavior was found to be linear for varying load magnitudes. The geometric properties investigated; pitch, thread length, width, major diameter and thread angle showed different influences on the three different profiles studied (triangular, trapezoidal and rectangular). The results indicated that 13 out of 32 screw designs produced were to achieve STP values greater than 0.3 of these, 6 were the rectangular profile. The best design was of the rectangular profile (Design no. 24) with an STP value of 0.4344. It was concluded that the best biomechanical properties were found in rectangular screw profiles. However, due to mix trends for the different properties, the careful combination and consideration towards pullout strength was necessary to obtain a design with the highest biocompatibility.

Shuib, Solehuddin; Ridzwan, M. I. Z.; Mohamad Ibrahim, M. N.; Tan, C. J.

126

Finite element analysis (FEA) for the Point contact fixator screw drive, plate design, overcuts  

Microsoft Academic Search

Finite Element (FE) analysis was performed to ensure that the newly designed plate for internal fixation, the Point Contact Fixator (PC-Fix), was at least as strong as existing implants used for the same clinical indications. The smaller holes of the PC-Fix allow for some reduction of the cross-sectional dimensions in comparison to a comparable Dynamic Compression Plate. The cross section

S. J. Bresina; S. Tepic

1995-01-01

127

Assessment of the endoscopic semitendinosus/gracilis autograft procedure with interference screw fixation for reconstruction of the anterior cruciate ligament.  

PubMed

The semitendinosus/gracilis autograft procedure with interference screw fixation was evaluated for clinical effectiveness of anterior cruciate ligament (ACL) reconstruction. Thirty patients underwent the procedure and were evaluated an average of 15 months postoperatively. Results revealed 22 (73%) patients had a standard knee evaluation form score of normal or nearly normal, and 24 (80%) patients returned to strenuous or moderate activity levels. Average Lysholm outcome score was 89, and bilateral KT-2000 differences were <3 mm at follow-up. Functional knee test symmetry index percentage outcome for the one-legged hop test was 92.6% for distance and 98% for time. Length of time (i.e., < or =90 days or > or =91 days) between injury and surgery was independent of outcome. These findings indicate the semitendinosus/gracilis autograft is a viable procedure for reconstruction of the ACL-deficient knee. PMID:11332962

Allen, A D; Sitler, M R; Marchetto, P; Kelly, J D; Mattacola, C G

2001-04-01

128

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

129

Delayed Union of a Sacral Fracture: Percutaneous Navigated Autologous Cancellous Bone Grafting and Screw Fixation  

Microsoft Academic Search

Delayed or non-union of a sacral fracture is a serious clinical condition that may include chronic pain, sitting discomfort, gait disturbances, neurological problems, and inability to work. It is also a difficult reconstruction problem. Late correction of the deformity is technically more demanding than the primary treatment of acute pelvic injuries. Open reduction, internal fixation (ORIF), excision of scar tissue,

R. W. Huegli; P. Messmer; A. L. Jacob; P. Regazzoni; S. Styger; T. Gross

2003-01-01

130

Analysis of initial fixation strength of press-fit fixation technique in anterior cruciate ligament reconstruction. A comparative study with titanium and bioabsorbable interference screw using porcine lower limb.  

PubMed

We performed a controlled laboratory study to evaluate the initial fixation strength of press-fit technique. Forty porcine lower limbs were used and divided into four groups according to the method of fixation; group 1 (press-fit+1.4 mm), in which the diameter difference between the bone plug and the femoral tunnel was 1.4 mm; group 2 (press-fit+1.4 mm, 30 degrees), in which the diameter difference was the same with group 1, but the tensile loading axis was 30 degrees away from the long axis of the femoral tunnel; group 3 (titanium), in which a titanium interference screw was used for fixation; group 4 (bioabsorbable), in which a bioabsorbable interference screw was used for fixation. The graft in the press-fit group was harvested with a hollow oscillating saw with inner diameter of 9.4 mm to obtain consistent and completely circular shape of the bone plug. The femoral tunnel with diameter of 8 mm was drilled at the original ACL insertion. Following the bone plug insertion into the femoral tunnel and applying a preload of 20 N, the specimen underwent 500 loading cycles between 0 and 2 mm of displacement. Thereafter the specimen was loaded to failure. There was no fixation site failure during the cyclic loading test. Significant differences in the stiffness, linear load, or failure mode among the groups were not found. The average ultimate failure load of group 1 and group 2 were not significantly different from those of group 3 and group 4. The press-fit groups demonstrated sufficient fixation strength for the rehabilitation and interference screw groups. The completely circular shape of the bone plug and increased diameter difference between the bone plug and the femoral tunnel seemed to contribute to the strong fixation. PMID:12664201

Lee, Myung Chul; Jo, Hyunchul; Bae, Tae-Soo; Jang, Jin Dae; Seong, Sang Cheol

2003-03-01

131

Four lateral mass screw fixation techniques in lower cervical spine following laminectomy: a finite element analysis study of stress distribution  

PubMed Central

Background Lateral mass screw fixation (LSF) techniques have been widely used for reconstructing and stabilizing the cervical spine; however, complications may result depending on the choice of surgeon. There are only a few reports related to LSF applications, even though fracture fixation has become a severe complication. This study establishes the three-dimensional finite element model of the lower cervical spine, and compares the stress distribution of the four LSF techniques (Magerl, Roy-Camille, Anderson, and An), following laminectomy -- to explore the risks of rupture after fixation. Method CT scans were performed on a healthy adult female volunteer, and Digital imaging and communication in medicine (Dicom) data was obtained. Mimics 10.01, Geomagic Studio 12.0, Solidworks 2012, HyperMesh 10.1 and Abaqus 6.12 software programs were used to establish the intact model of the lower cervical spines (C3-C7), a postoperative model after laminectomy, and a reconstructive model after applying the LSF techniques. A compressive preload of 74 N combined with a pure moment of 1.8 Nm was applied to the intact and reconstructive model, simulating normal flexion, extension, lateral bending, and axial rotation. The stress distribution of the four LSF techniques was compared by analyzing the maximum von Mises stress. Result The three-dimensional finite element model of the intact C3-C7 vertebrae was successfully established. This model consists of 503,911 elements and 93,390 nodes. During flexion, extension, lateral bending, and axial rotation modes, the intact model’s angular intersegmental range of motion was in good agreement with the results reported from the literature. The postoperative model after the three-segment laminectomy and the reconstructive model after applying the four LSF techniques were established based on the validated intact model. The stress distribution for the Magerl and Roy-Camille groups were more dispersive, and the maximum von Mises stress levels were lower than the other two groups in various conditions. Conclusion The LSF techniques of Magerl and Roy-Camille are safer methods for stabilizing the lower cervical spine. Therefore, these methods potentially have a lower risk of fixation fracture. PMID:25106498

2014-01-01

132

Evaluation of implant loosening following segmental pedicle screw fixation in adolescent idiopathic scoliosis: a 2 year follow-up with low-dose CT  

PubMed Central

Background The long term radiological status of screw fixation following scoliosis surgery with all pedicle screw construct is not previously studied. Aim To evaluate the incidence of loosening (implant failure) evaluated with low-dose CT two years following scoliosis surgery. Study design Retrospective study. Methods 81 consecutive patients with adolescent idiopathic scoliosis (AIS), aged 18?±?3 years at 2 years follow-up (83% were female), subjected for scoliosis corrective surgery with all pedicle screw construct (total of 1666 screws) has been examined with plain radiography and with low dose CT 6 weeks and 2 years postoperatively. Results In 26 out of 81 (32%) patients there were signs of loosening of one or more screws, a maximum 3 screws. 47 out of 1666 (2.8%) screws showed evidence of loosening. Preoperative Cobb angle was 56° among patients with loosening compared with 53° among patients with no evidence of loosening (P?=?0.288). In males there were signs of loosening in 8 out of 14 (57%) and in females 18 out of 67 (27%), (P?=?0.027). Among cases with loosening, 14% had suboptimal screw placement at the first postoperative CT compared with 11% among patients with no evidence of loosening (P?=?0.254). One patient with a loosened L4 screw had neurological deficit and subjected for revision of the construct. Out of 26 patients with evidence of loosening, 5 patients reported minor pain or discomfort, 1 patient had a minor proximal junctional kyphosis of about 15° and 3 patients showed evidence of pull-out of 3–5 mm at the upper end of the construct but no clinical complaint. With plain radiography loosening could be observed only in 11 out of 26 cases, 5 were in the lumbar region. Conclusions In a consecutive series of 81 cases with AIS who had underwent scoliosis surgery, one third showed, 2 years after the intervention, minor screw loosening. Males were more prone to develop screw loosening. In CT system that enables low-dose protocol, CT is recommended for the evaluation of evidence of screw loosening. PMID:25177357

2014-01-01

133

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

PubMed Central

Background The acetabular component has remained the weakest link in hip arthroplasty regarding achievement of long-term survival. Primary fixation is a prerequisite for long-term performance. For this reason, we investigated the stability of a unique cementless titanium-coated elastic monoblock socket and the influence of supplementary screw fixation. Patient and methods During 2006–2008, we performed a randomized controlled trial on 37 patients (mean age 63 years (SD 7), 22 females) in whom we implanted a cementless press-fit socket. The socket was implanted with additional screw fixation (group A, n = 19) and without additional screw fixation (group B, n = 18). Using radiostereometric analysis with a 2-year follow-up, we determined the stability of the socket. Clinically relevant migration was defined as > 1 mm translation and > 2º rotation. Clinical scores were determined. Results The sockets without screw fixation showed a statistically significantly higher proximal translation compared to the socket with additional screw fixation. However, this higher migration was below the clinically relevant threshold. The numbers of migratory sockets were not significantly different between groups. After the 2-year follow-up, there were no clinically relevant differences between groups A and B regarding the clinical scores. 1 patient dropped out of the study. In the others, no sockets were revised. Interpretation We found that additional screw fixation is not necessary to achieve stability of the cementless press-fit elastic RM socket. We saw no postoperative benefit or clinical effect of additional screw fixation. PMID:23083434

2012-01-01

134

Arthroscopic reduction and internal fixation of acetabular fractures.  

PubMed

Arthroscopic reduction and screw fixation of acetabular fractures have not been reported. In this case report, arthroscopic treatment for acetabular fracture is reported for two patients. A 49-year-old man diagnosed with acetabular posterior wall fracture was treated by arthroscopic reduction and fixation using two screws. A 20-year-old woman who diagnosed with anterior column fracture was fixed using a screw using the arthroscopic technique prior to open reduction and internal fixation in the iliac bone fracture. Arthroscopic reduction and fixation in some case of acetabular fracture could be good indication with additional advantages of joint debridement and loose body removal. PMID:24306124

Kim, Hyangkyoung; Baek, Ji-Hoon; Park, Sang-Min; Ha, Yong-Chan

2014-04-01

135

Metallic versus bioabsorbable interference screw for fixation of bone-patellar tendon-bone autograft in arthroscopic anterior cruciate ligament reconstructionA preliminary report  

Microsoft Academic Search

We retrospectively compared the clinical outcome and the radiographic incorporation of the bone blocks between two groups\\u000a of patients undergoing anterior cruciate ligament reconstruction using either metallic or bioabsorbable interference screws\\u000a for fixation of the bone-patellar tendon-bone autograft. Sixty-nine patients (44 male and 25 female) were available for follow-up.\\u000a There were 31 patients with a mean age of 33 years

C. Marti; A. B. Imhoff; C. Bahrs; J. Romero

1997-01-01

136

Initial Fixation Strength of Bioabsorbable and Titanium Interference Screws in Anterior Cruciate Ligament ReconstructionBiomechanical Evaluation by Single Cycle and Cyclic Loading  

Microsoft Academic Search

We evaluated the initial bone-patellar tendon-bone graft fixation strength of bioabsorbable as compared with titanium interference screws in anterior cruciate ligament reconstruction using matched pairs of porcine knees. Ten pairs underwent single-cycle failure loading at a rate of 50 mm\\/min, and 10 pairs underwent cyclic loading at half-hertz frequency. The cyclic loading started with 100 load cycles between 50 and

Petteri Kousa; Teppo L. N. Järvinen; Pekka Kannus; Markku Järvinen

2001-01-01

137

The influence of sacral morphology on the existence of secure S1 and S2 transverse bone corridors for iliosacroiliac screw fixation.  

PubMed

Sacroiliac (SI) screw fixation for unstable pelvic fractures stands out as the only minimally invasive method among all other ORIF procedures. A strictly transverse screw trajectory is needed for central or bilateral fracture patterns up to a complete iliosacroiliac fixation. However, secure screw insertion is aggravated by a narrow sacroiliac bone stock. This study investigates the influence of a highly variable sacral morphology to the existence of S1 and S2 transverse corridors. The analysis contained in this study is based on 125 CT datasets of intact human pelvises. First, sacral dysplasia was identified using the "lateral sacral triangle" method in a lateral 3-D semi-transparent pelvic view. Second, 3-D corridors for a 7.3mm screw in the upper two sacral levels were visualised using a proprietary IT workflow of custom-made programme scripts based on the Amira(®)-software. Shape-describing measurement variables were calculated as output variables. The results show a significant linear correlation between ratioT and the screw-limiting S1 isthmus height (Pearson coefficient of 0.84). A boundary ratio of 1.5 represented a positive predictive value of 96% for the existence of a transverse S1-corridor for at least one 7.3mm screw. In 100 out of 125 pelvises (80%), a sufficient S1 corridor existed, whereas in 124 specimens (99%), an S2 corridor was found. Statistics revealed significantly larger S1 and S2 corridors in males compared to females (p<0.05). However, no gender-related differences were observed for clinically relevant numbers of up to 3 screws in S1 and 1 screw in S2. The expanse of the S1 corridor is highly influenced by the dimensions of the dysplastic elevated upper sacrum, whereas the S2 corridor is not affected. Hence, in dysplastic pelvises, sacroiliac screw insertion should be recommended into the 2nd sacral segment. Our IT workflow for the automatic computation of 3-D corridors may assist in surgical pre-operative planning. Furthermore, the workflow could be implemented in computer-assisted surgery applications involving pelvic trauma. PMID:24004615

Mendel, T; Noser, H; Kuervers, J; Goehre, F; Hofmann, G O; Radetzki, F

2013-12-01

138

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

PubMed Central

Background: In the surgical treatment of thoracolumbar fractures, the major problem after posterior correction and transpedicular instrumentation is failure to support the anterior spinal column, leading to loss of correction and instrumentation failure with associated complaints. We conducted this prospective study to evaluate the outcome of the treatment of acute thoracolumbar burst fractures by transpedicular balloon kyphoplasty, grafting with calcium phosphate cement and short pedicle screw fixation plus fusion. Materials and Methods: Twenty-three consecutive patients of thoracolumbar (T9 to L4) burst fracture with or without neurologic deficit with an average age of 43 years, were included in this prospective study. Twenty-one from the 23 patients had single burst fracture while the remaining two patients had a burst fracture and additionally an adjacent A1-type fracture. On admission six (26%) out of 23 patients had neurological deficit (five incomplete, one complete). Bilateral transpedicular balloon kyphoplasty with liquid calcium phosphate to reduce segmental kyphosis and restore vertebral body height and short (three vertebrae) pedicle screw instrumentation with posterolateral fusion was performed. Gardner kyphosis angle, anterior and posterior vertebral body height ratio and spinal canal encroachment were calculated pre- to postoperatively. Results: All 23 patients were operated within two days after admission and were followed for at least 12 months after index surgery. Operating time and blood loss averaged 45 min and 60 cc respectively. The five patients with incomplete neurological lesions improved by at least one ASIA grade, while no neurological deterioration was observed in any case. The VAS and SF-36 (Role physical and Bodily pain domains) were significantly improved postoperatively. Overall sagittal alignment was improved from an average preoperative 16° to one degree kyphosis at final followup observation. The anterior vertebral body height ratio improved from 0.6 preoperatively to 0.9 (P<0.001) postoperatively, while posterior vertebral body height improved from 0.95 to 1 (P<0.01). Spinal canal encroachment was reduced from an average 32% preoperatively to 20% postoperatively. Cement leakage was observed in four cases (three anterior to vertebral body and one into the disc without sequalae). In the last CT evaluation, there was a continuity between calcium phosphate and cancellous vertebral body bone. Posterolateral radiological fusion was achieved within six months after index operation. There was no instrumentation failure or measurable loss of sagittal curve and vertebral height correction in any group of patients. Conclusions: Balloon kyphoplasty with calcium phosphate cement secured with posterior short fixation in the thoracolumbar spine provided excellent immediate reduction of posttraumatic segmental kyphosis and significant spinal canal clearance and restored vertebral body height in the fracture level. PMID:21139791

Korovessis, Panagiotis; Repantis, Thomas; George, Petsinis

2007-01-01

139

CT Morphometric Analysis to Determine the Anatomical Basis for the Use of Transpedicular Screws during Reconstruction and Fixations of Anterior Cervical Vertebrae  

PubMed Central

Background Accurate placement of pedicle screw during Anterior Transpedicular Screw fixation (ATPS) in cervical spine depends on accurate anatomical knowledge of the vertebrae. However, little is known of the morphometric characteristics of cervical vertebrae in Chinese population. Methods Three-dimensional reconstructions of CT images were performed for 80 cases. The anatomic data and screw fixation parameters for ATPS fixation were measured using the Mimics software. Findings The overall mean OPW, OPH and PAL ranged from 5.81 to 7.49 mm, 7.77 to 8.69 mm, and 33.40 to 31.13 mm separately, and SPA was 93.54 to 109.36 degrees from C3 to C6, 104.99 degrees at C7, whereas, 49.00 to 32.26 degrees from C4 to C7, 46.79 degrees at C3 (TPA). Dl/rSIP had an increasing trend away from upper endplate with mean value from 1.87 to 5.83 mm. Dl/rTIP was located at the lateral portion of the anterior cortex of vertebrae for C3 to C5 and ipsilateral for C6 to C7 with mean value from ?2.70 to ?3.00 mm, and 0.17 to 3.18 mm. The entrance points for pedicular screw insertion for C3 to C5 and C6 to C7 were recommended ?2??3 mm and 0–4 mm from the median sagittal plane, respectively, 1–4 mm and 5–6 mm from the upper endplate, with TPA being 46.79–49.00 degrees and 40.89–32.26 degrees, respectively, and SPA being 93.54–106.69 degrees and 109.36–104.99 degrees, respectively. The pedicle screw insertion diameter was recommended 3.5 mm (C3 and C4), 4.0 mm (C5 to C7), and the pedicle axial length was 21–24 mm for C3 to C7 for both genders. However, the ATPS insertion in C3 should be individualized given its relatively small anatomical dimensions. Conclusions The data provided a morphometric basis for the ATPS fixation technique in lower cervical fixation. It will help in preoperative planning and execution of this surgery. PMID:24349038

Chen, Chun; Ruan, Dike; Wu, Changfu; Wu, Weidong; Sun, Peidong; Zhang, Yuanzhi; Wu, Jigong; Lu, Sheng; Ouyang, Jun

2013-01-01

140

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

PubMed Central

Background Anterior lumbar interbody fusion (ALIF) followed by pedicle screw fixation (PSF) is used to restore the height of the intervertebral disc and provide stability. Recently, stand-alone interbody cage with anterior fixation has been introduced, which eliminates the need for posterior surgery. We compared the biomechanics of the stand-alone interbody cage to that of the interbody cage with additional PSF in ALIF. Methods A three-dimensional, non-linear finite element model (FEM) of the L2-5 segment was modified to simulate ALIF in L3-4. The models were tested under the following conditions: (1) intact spine, (2) destabilized spine, (3) with the interbody cage alone (type 1), (4) with the stand-alone cage with anterior fixation (SynFix-LR®; type 2), and (5) with type 1 in addition to PSF (type 3). Range of motion (ROM) and the stiffness of the operated level, ROM of the adjacent segments, load sharing distribution, facet load, and vertebral body stress were quantified with external loading. Results The implanted models had decreased ROM and increased stiffness compared to those of the destabilized spine. The type 2 had differences in ROM limitation of 8%, 10%, 4%, and 6% in flexion, extension, axial rotation, and lateral bending, respectively, compared to those of type 3. Type 2 had decreased ROM of the upper and lower adjacent segments by 3-11% and 3-6%, respectively, compared to those of type 3. The greatest reduction in facet load at the operated level was observed in type 3 (71%), followed by type 2 (31%) and type 1 (23%). An increase in facet load at the adjacent level was highest in type 3, followed by type 2 and type 1. The distribution of load sharing in type 2 (anterior:posterior, 95:5) was similar to that of the intact spine (89:11), while type 3 migrated posterior (75:25) to the normal. Type 2 reduced about 15% of the stress on the lower vertebral endplate compared to that in type 1. The stress of type 2 increased two-fold compared to the stress of type 3, especially in extension. Conclusions The stand-alone interbody cage can provide sufficient stability, reduce stress in adjacent levels, and share the loading distribution in a manner similar to an intact spine. PMID:23890389

2013-01-01

141

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

142

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

143

[A new design of internal fixation for scoliosis-multi-screw fixed distractor-compressor via the vertebral pedicle and its clinical application].  

PubMed

A new scoliotone, which is made up of screws, sockets, clamps, distraction rod and compression rod, was used stabilize immobilization of the spine in 10 cases. This scoliotone can produce free motion in three different levels, and has a strong power of fixation, distraction, compression and antitraction. In 10 cases when the patient's spinal curvature (cobb's angle) was less than 50 degrees, the average range of correction was 78.2% and the correction rate of kyphosis peak was 90%. When the spinal curvature was between 50 to 100 degrees, the average range of correction was 68.2%, and the correction rate of kyphosis peak was 87.7%. If the spinal curvature was more than 100 degrees, the average range of correction rate of kyphosis peak was 82%. After the operation, the patient might not be immobilized. In this paper, the biomechanical features of the vertebral arch, internal fixation and correction of kyphosis peak were discussed. PMID:1813237

Chi, Y L

1991-08-01

144

Increased rod stiffness improves the degree of deformity correction by segmental pedicle screw fixation in adolescent idiopathic scoliosis  

PubMed Central

Background There are limited reports in literature studying the impact of rod diameter and stiffness on the degree of deformity correction in patients with AIS. Aims The aims of this study were to evaluate the 3-dimentional deformity correction achieved by segmental pedicle screw fixation in patients with adolescent idiopathic scoliosis, and to find out if learning or the change to stiffer rods had any positive impact on deformity correction. Study design Retrospective study. Methods Plain radiographs and low-dose spine CTs of 116 consecutive patients (aged 15.9 ± 2.8 years) operated during the period 2005-2009 (group 1: patients operated autumn 2005-2006; group 2: 2007; group 3: 2008; group 4: 2009) were retrospectively evaluated. Results There was no statistically significant difference between the correction of the Cobb angle (P = 0.425) or lower end vertebra tilt (P = 0.298) in patients operated during the first versus the remaining periods of the study. No restoration of the sagittal kyphosis was reported in the first period compared with 5.9° in the last study period (P < 0.001). The correction of vertebral rotation was also improved from 4.2° to 7.8° (P < 0.001) for the same periods. For the whole study population, there was statistically significant correlation between the order of the operation (patient number) and the restoration of sagittal kyphosis (r = -0.344, P = 0.001), and the correction of vertebral rotation (r = 0.370, P < 0.001), but not for the Cobb angle or LEVT. However, there was no significant difference in restoration of sagittal kyphosis and the vertebral rotation in the first 17 patients compared with the last 17 patients operated with rods of 5.5 mm diameter (P = 0.621, and 0.941, respectively), indicating that rod stiffness had more impact on the deformity correction than did learning. Conclusions This study showed that rod stiffness had more impact on the deformity correction than did learning. PMID:21797999

2011-01-01

145

A Comparison Between a Retrograde Interference Screw, Suture Button, and Combined Fixation on the Tibial Side in an All-Inside Anterior Cruciate Ligament ReconstructionA Biomechanical Study in a Porcine Model  

Microsoft Academic Search

Background: Effective soft tissue graft fixation to the tibial tunnel in all-inside anterior cruciate ligament reconstructions has been reported to be a problem and may lead to retrograde pullout at ultimate load testing.Hypothesis: A combined retrograde bioabsorbable screw and cortical-cancellous suture button suspension apparatus would gain stiffness from the button and strength from the screw, thus providing for a larger

Michael P. Walsh; Coen A. Wijdicks; Josh B. Parker; Onur Hapa; Robert F. LaPrade

2009-01-01

146

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

147

The influence of injecting an epidural contrast agent into the sacral canal on the fluoroscopic visibility of bony landmarks for sacroiliac screw fixation: a feasibility study.  

PubMed

OBJECT In sacroiliac screw fixation of unstable pelvic injuries in geriatric patients, poor bone quality often obscures important bony landmarks in fluoroscopic images. The authors analyzed the feasibility of injecting a transhiatal contrast agent (CA) into the sacral canal to improve fluoroscopic visualization in the sacral epidural space. METHODS Eight fresh cadaveric whole-body specimens from human donors whose mean age at the time of death was 78 years (range 69-87 years) were used. First, to identify bony landmarks without CA enhancement, the authors acquired fluoroscopy images of the native sacral canal, using lateral, inlet, and outlet projections. Through puncture of the sacral hiatus, 8-10 ml of CA was injected into the epidural space. Fluoroscopy images were then acquired in the standard pelvic views to identify the bony landmarks. To assess the effect of the CA enhancement, visibility of the landmarks was assessed before and after CA injection. Each identified landmark was scored as 1, and summative landmark scores of up to 10 were determined for each specimen. RESULTS The cadaveric specimens were representative of bone structures in the geriatric population. In all specimens, epidural CA injection enhanced the fluoroscopic visualization of the sacral canal and of the S-1 foramina. The enhancement increased the total bony landmark score from 5.9 (range 4-8) without CA injection to 8.1 (range 6-10) after CA injection. Considering only intrasacral landmarks, the score was increased from 1.5 to 3. CONCLUSIONS Injection of a transhiatal epidural CA improves fluoroscopic imaging of the sacral canal and of the neural foramina. Hence, this technique could be applied to help the surgeon identify anatomical landmarks during sacroiliac screw fixation in geriatric patients. PMID:25431962

Mendel, Thomas; Radetzki, Florian; Schwan, Stefan; Hofmann, Gunther Olaf; Goehre, Felix

2014-11-28

148

Theoretical assessment of an intramedullary condylar component versus screw fixation for the condylar component of a hemiarthroplasty alloplastic TMJ replacement system.  

PubMed

Virtual design gives flexibility to explore constructive solutions or structures. It enables analysis that would often be impossible even if expensive real prototypes were available. Simulations using finite element models allow access to the stress and strain tensor or to the deformation tensor within an implant or a tissue which is impossible experimentally, even in vitro. This study is based on two numerical models of temporomandibular joint (TMJ) implants, comparing two bone-implant connections: an external connection performed with surgical screws (commercial model) and an internal connection carried out by penetration into the intramedullary space. The finite element models were constructed based on a cadaveric mandible and considering the five principal muscles in action. Strain distributions into the surrounding bone tissue are analysed and in both models they show significant differences at the external surface of the mandible in displacements. However, while the intramedullary fixation increases strains in the cancellous tissue, the study shows that strain distribution is mainly influenced by the number and distribution of screws in commercial solution. PMID:23684530

Ramos, A; Mesnard, M; Relvas, C; Completo, A; Simões, J A

2014-03-01

149

Internal Reduction Established by Occiput-C2 Pedicle Polyaxial Screw Stabilization in Pediatric Atlantoaxial Rotatory Fixation  

Microsoft Academic Search

Atlantoaxial rotatory fixation is an uncommon disorder of childhood, which can be treated conservatively whendiagnosed early. Although spontaneous correction occasionally occurs, most of the patients usually benefit from collar or traction therapies. If there is no intervention or if all external therapeutic modalities fail, the deformity may become chronic and irreducible. In such rare cases, surgical correction and stabilization are

Deniz Belen; Serkan Simsek; Kazim Yigitkanli; Murad Bavbek

2006-01-01

150

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

151

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

152

C1 dome-like laminotomy and posterior C1-C2 polyaxial screw-rod fixation for a patient with cervical myelopathy due to a retro-odontoid pseudotumor.  

PubMed

A 49-year-old man presented with progressive cervical myelopathy caused by a retro-odontoid mass, with associated developmental canal stenosis at C1, and C1-C2 instability. Surgery was scheduled for a dome-like laminotomy at C1, posterior C1-C2 fixation using C1 lateral mass screws and C2 pedicle screws, and structural bone grafting between C1 and C2. Prior to surgery, we produced a 3-dimensional full-scale model of the patient's cervical spine and performed a simulation of the scheduled surgery. Through the simulation, we accurately evaluated the laminotomy sites and the screw insertion points. During the actual surgery, all procedures were successful. After surgery, the patient's neurological deficits markedly improved. Successful C1-C2 fusion, adequate decompression of the spinal cord, and spontaneous regression of the retro-odontoid mass were achieved by this procedure without any apparent restriction in neck movement. PMID:19010681

Yamazaki, Masashi; Okawa, Akihiko; Mannoji, Chikato; Kadota, Ryo; Miyashita, Tomohiro; Koda, Masao

2009-01-01

153

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

154

One-stage partial vertebrectomy, titanium mesh implantation and pedicle screw fixation in the treatment of thoracolumbar burst fractures through a posterior approach  

PubMed Central

OBJECTIVE: To analyze the clinical results of a partial vertebrectomy with titanium mesh implantation and pedicle screw fixation using a posterior approach to reconstruct the spine in the treatment of thoracolumbar burst fractures. METHOD: From January 2006 to August 2008, 20 patients with severe thoracolumbar fractures were treated.For vertebral bodies associated with one injured intervertebral disk, subtotal vertebrectomy surgery and single-segment fusion were performed. For vertebral bodies with two injured adjacent intervertebral disks, partial vertebrectomy surgery and two-segment fusion were performed. RESULTS: All 20 patients were followed up for 12 to 24 months (average of 18 months). There were no complications such as wound infections, hemopneumothorax or abdominal infections in any of the patients. The neurological status of all of the patients was improved by at least one American Spinal Injury Association grade by the last follow-up. The anterior vertebral body height was an average of 50.77% before surgery, 88.51% after surgery and 87.86% at the last follow up; the sagittal Cobb angle was improved, on average, from 26.15° to 5.39° and was 5.90° at the last follow up. The percentage of spinal stenosis was improved, on average, from 26.07% to 4.93%° and was 6.15% at the last follow up. There were significant differences in the anterior vertebral body height pre- and post-surgery and in the sagittal Cobb angle and the percentage of spinal stenosis (p<0) in all patients. CONCLUSIONS: This surgical procedure is simple and can accomplish decompression, reduction, fixation and fusion of the spine in one stage. This approach could be widely used in orthopedics.

Liu, Yueju; Li, Guangbin; Dong, Tianhua; Zhang, Yingze; Li, Heng

2014-01-01

155

Influence of the volume of bone defect, bone grafting methods, and hook fixation on stress on the Kerboull-type plate and screw in total hip arthroplasty: three-dimensional finite element analysis.  

PubMed

For total hip arthroplasty or revision surgery using acetabular reinforcement cross-plates, choosing between bulk and morselized bone grafts for filling acetabular defects is challenging. We used finite element model (FEM) analysis to clarify various stresses on the cross-plate based on bone defect size, bone graft type, and presence or absence of hook fixation to the bone. We constructed 12-pattern FEMs and calculated the maximum stress generated on the Kerboull-type (KT) plate and screw. Bone defects were classified into four patterns according to the volume. Regarding the bone graft type, bulk bone grafts were considered as cortical bone, and morselized bone grafts were considered to consist of cancellous bone. Models were compared based on whether hook fixation was used and whether a gap was present behind the plate. The upper surface of the host bone was fixed, and a 1,000-N load was imposed on the horizontal axis at 71°. Larger bone defects increased the stress on the KT plate and screws. This stress increased when no bone was grafted; it was lower when bulk cortical bone grafts were used for filling than when morselized cancellous bone grafts were used. For cortical bone grafts, the increased stress on the KT plate and screws was lowered with hook removal. Attaching the hook to the bone and filling the gap behind the KT plate with an adequate bone graft reduced the stress on the KT plate and screws, particularly for large bone defects filled by bulk bone grafting. PMID:24964969

Kaku, Nobuhiro; Hara, Katsutoshi; Tabata, Tomonori; Tsumura, Hiroshi

2015-02-01

156

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

157

Heterotrophic nitrogen fixation in oligotrophic tropical marshes: changes after phosphorus addition  

Microsoft Academic Search

In order to determine the impact of nutrient enrichment on phosphorus (P) limited wetlands, we established experimental P\\u000a additions in marshes throughout northern Belize. P significantly increased macrophyte primary production, which led to the\\u000a rapid elimination of cyanobacterial mats. The replacement of cyanobacterial mats by macrophytes constrained autotrophic nitrogen\\u000a (N) fixation, increased the quantity, and changed the quality of organic

Barbora ?erná; Eliška Rejmánková; Jenise M. Snyder; Hana Šantr??ková

2009-01-01

158

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

159

Predictive Factors for a Kyphosis Recurrence Following Short-Segment Pedicle Screw Fixation Including Fractured Vertebral Body in Unstable Thoracolumbar Burst Fractures  

PubMed Central

Objective The technique of short segment pedicle screw fixation (SSPSF) has been widely used for stabilization in thoracolumbar burst fractures (TLBFs), but some studies reported high rate of kyphosis recurrence or hardware failure. This study was to evaluate the results of SSPSF including fractured level and to find the risk factors concerned with the kyphosis recurrence in TLBFs. Methods This study included 42 patients, including 25 males and 17 females, who underwent SSPSF for stabilization of TLBFs between January 2003 and December 2010. For radiologic assessments, Cobb angle (CA), vertebral wedge angle (VWA), vertebral body compression ratio (VBCR), and difference between VWA and Cobb angle (DbVC) were measured. The relationships between kyphosis recurrence and radiologic parameters or demographic features were investigated. Frankel classification and low back outcome score (LBOS) were used for assessment of clinical outcomes. Results The mean follow-up period was 38.6 months. CA, VWA, and VBCR were improved after SSPSF, and these parameters were well maintained at the final follow-up with minimal degree of correction loss. Kyphosis recurrence showed a significant increase in patients with Denis burst type A, load-sharing classification (LSC) score >6 or DbVC >6 (p<0.05). There were no patients who worsened to clinical outcome, and there was no significant correlation between kyphosis recurrence and clinical outcome in this series. Conclusion SSPSF including the fractured vertebra is an effective surgical method for restoration and maintenance of vertebral column stability in TLBFs. However, kyphosis recurrence was significantly associated with Denis burst type A fracture, LSC score >6, or DbVC >6. PMID:25368766

Kim, Gun-Woo; Hur, Hyuk; Lee, Jung-Kil; Kim, Jae-Hyoo; Kim, Soo-Han

2014-01-01

160

Strong stimulation of N2 fixation in oligotrophic Mediterranean Sea: results from dust addition in large in situ mesocosms  

NASA Astrophysics Data System (ADS)

The response of N2 fixation to contrasted (wet and dry) Saharan dust deposition was studied in the framework of the DUNE project "a DUst experiment in a low-Nutrient, low-chlorophyll Ecosystem" during which realistic simulations of dust deposition (10 g madditions were conducted in June 2008 (DUNE-1-P: simulation of a wet deposition, DUNE-1-Q: simulation of a dry deposition) and 2010 (DUNE-2-R: simulation of successive wet depositions) in the north western oligotrophic Mediterranean Sea. Here we show that wet and dry dust deposition induced a rapid (24 h or 48 h after dust additions), strong (2- to 5.3-fold) and long (4 to 6 days duration) increase in N2 fixation indicating that both wet and dry Saharan dust depositions were able to relieve efficiently the nutrient limitation(s) of N2 fixation. This means in particular that N2 fixation activity was not inhibited by the NO3- input associated with the simulated wet deposition. The contribution of N2 fixation to primary production was negligible before (on average 0.4%) and after (on average 1%) dust additions in all experiments indicating that N2 fixation was a poor contributor to the N demand for primary production. Before seedings, new production (NP) was mainly supported by NO3- as a source of N as shown by the low contribution of N2 fixation to NP (on average 3%). Despite the stimulation of N2 fixation by dust, the rates remained low, and did not allow to significantly change the contribution of N2 fixation to NP as a maximum of 10% contribution was evidenced. A comparison of the responses of N2 fixation by diazotrophs and CO2 fixation by the whole phytoplankton community suggests that those metabolic processes were limited or co-limited by different nutrients. The estimated input of new nitrogen (NO3-) from simulated wet deposition was much higher than that associated with N2 fixation. We confirm that although the biogeochemical impact of N2 fixation seems negligible in the oligotrophic waters of the western Mediterranean Sea, Saharan dust pulses by bringing new nutrients represent a key controlling factor of the magnitude of N2 fixation rate in the Mediterranean Sea and potentially in all LNLC areas impacted by dust deposition such as the tropical Atlantic and Pacific Oceans.

Ridame, C.; Guieu, C.; L'Helguen, S.

2013-06-01

161

Magnetic Resonance Imaging Analysis of Bioabsorbable Interference Screws Used for Fixation of Bone-Patellar Tendon-Bone Autografts in Endoscopic Reconstruction of the Anterior Cruciate Ligament  

Microsoft Academic Search

Background: Metal interference screws can cause problems if revision is needed and can interfere with magnetic resonance imaging. Bioabsorbable screws have been developed to prevent these problems, but the rate of resorption and integration is not well understood.Hypothesis: Poly-L-lactic acid interference screws will be resorbed 2 years after anterior cruciate ligament reconstruction.Study Design: Case series; Level of evidence, 4.Methods: The

Jon Olav Drogset; Torbjørn Grøntvedt; Gunnar Myhr

2006-01-01

162

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

163

Poly-L-lactic acid — hydroxyapatite (PLLA-HA) bioabsorbable interference screws for tibial graft fixation in anterior cruciate ligament (ACL) reconstruction surgery: MR evaluation of osteointegration and degradation features  

Microsoft Academic Search

Purpose  We evaluated with magnetic resonance imaging (MRI) the degradation and osteointegration features of a new type of bioabsorbable\\u000a interference (BioRCI) screw composed of poly-L-lactic acid and hydroxyapatite (PLLA-HA) used for tibial graft fixation in\\u000a anterior cruciate ligament (ACL) reconstruction.\\u000a \\u000a \\u000a \\u000a Materials and methods  Thirty-one patients underwent arthroscopic surgery for ACL reconstruction using doubled gracilis and semitendinosus tendons\\u000a fixed to the tibial tunnel

L. Macarini; P. Milillo; A. Mocci; R. Vinci; G. C. Ettorre

2008-01-01

164

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

165

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

166

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

PubMed Central

Spondylolysis is a common entity, a minority of people affected by this disease need medical care, and only a few require surgery. Reconstruction of the pars interarticularis is an interesting alternative to segmental fusion; this technique has the advantage of preserving segmental motion. Most authors report good results for young patients without intervertebral disk or facet degenerative changes. Moreover Louis also showed good to excellent results with his technique carried out among people who presented a satisfactory disk height (equal to two thirds of normal height). This could extend the number of patients for whom pars interarticularis repair could be proposed. In this study, the limit of reconstruction was set at grade 3of the Pfirrmann’s classification. The fixation of the isthmus was done with a new kind of pedicle screw hook system. This stable and strong device is easy to use, allows an anatomic pars interarticularis reconstruction of spondylolysis and avoids a postoperative bracing. Twenty-three patients were assessed in this study, the mean age at operation was 34 (range 16–52 years) and the average follow-up was for 59 months (range 6–113 months). Eight patients showed moderate degenerative disk disease before the surgery and 12 patients had a grade 1 spondylolisthesis. The visual analogical scale, the Oswestry disability index (ODI) and the modified Prolo score were used for assessment of pain and clinical outcome before and after surgery. The results were from “excellent” to “good” for twenty patients (87%) and “fair” for three of them (13%). The consolidation of the isthmus was assessed at the end of the study (CT-scan); the fusion rate was observed in 91%. Among patients aged less than 30 years results are from “good”, to “excellent” in all cases and consolidation was always observed. All of them showed normal disc signal before the surgery. In the group aged more than 30 years, the results varied from “good” to “excellent’ in 73% and fusion of the defect was discovered in 82% of cases. Eight of them (73%) had moderate disk signal modification before the surgery. All people with fair results displayed moderate disk degeneration signs at MRI before surgery; but two of those three patients had a failure of defect consolidation too and it is also associated with poor results by several authors. No complication was found in this series. According to the good results reported by Louis and upto the current finding, the authors believe that pars interarticularis repair can be carried out on patients with moderate degenerative disk disease; the stage 3 of Pfirrmann’s classification seems a good limit. The Bone and joint research (B.J.R. system) is readily usable by any surgeon using pedicle screw systems and having a short learning curve. No device failure has been observed in this series. PMID:17520298

Troussel, Serge

2007-01-01

167

Direct Repair Surgery with Screw Fixation for Young Patients with Lumbar Spondylolysis: Patient-Reported Outcomes and Fusion Rate in a Prospective Interventional Study.  

PubMed

Study Design. Prospective interventional studyObjectives. To thoroughly investigate the therapeutic outcomes of direct repair (DR) for young patients with lumbar spondylolysisSummary of Background Data. DR surgery with screw fixation for a pars defect of lumbar spondylolysis is considered a notable surgical option. However, prior studies do not provide clear information on the significance of DR and its outcomes in young patients with lumbar spondylolysis because most previous studies in this area were conducted with spondylolytic patients of all ages and with low-quality study designs that were retrospective design and had a small sample size and short follow-up time.Methods. A total of 47 young patients with lumbar spine spondylolysis who were surgically treated with DR surgery and followed-up for one year after surgery were enrollment in the current study. The primary outcome was degree of pain assessed by visual analogue scale (VAS), which separately recorded pain intensity and pain frequency. Secondary outcomes included (1) patient satisfaction, (2) clinical outcomes based on Oswestry disability index (ODI) score and a 12-item short form health survey (SF-12), (3) fusion rate of pars defect based on computed tomography (CT) scans, and (4) surgery-related complications.Results. The degree of lower back pain (intensity and frequency) significantly improved at final follow-up compared to preoperative level. However, six patients (13%) had no significant improvement, and pain frequency tended to worsen six months after the operation. Only 25 patients (53%) were satisfied with DR surgery. One year postoperative clinical outcomes (ODI and SF-12) significantly improved compared to preoperative levels, but the two scores also tended to decrease after six months. The union rate of the pars defect was 55% (26/47). There was no significant difference in clinical outcomes between fusion group and nonunion group of the pars defect at the final follow-up. Two patients (4%) experienced surgery-related complications.Conclusion. The authors suggest that DR surgery in young patients with lumbar spondylolysis may produce unsatisfactory outcomes at one year after surgery. PMID:25398039

Lee, Gun Woo; Lee, Sun-Mi; Suh, Bo-Gun

2014-11-13

168

Do Newer-Generation Bioabsorbable Screws Become Incorporated into Bone at Two Years After ACL Reconstruction with Patellar Tendon Graft?  

PubMed Central

Background: Bioabsorbable interference screws are used frequently for graft fixation in ACL (anterior cruciate ligament) reconstruction. The resorption properties of many available screws that are marketed as bioabsorbable are not well defined. The CALAXO (Smith & Nephew Endoscopy) and MILAGRO (DePuy Synthes) bioabsorbable screws contain polymers of poly(lactic-co-glycolic acid) (PLGA) plus additives to encourage osseointegration over time. The purpose of this study was to evaluate radiographic and magnetic resonance imaging (MRI) properties and compare patient-reported outcomes at a minimum of two years of follow-up after ACL reconstruction using CALAXO or MILAGRO bioabsorbable interference screws. Methods: A cohort of patients who underwent ACL reconstruction in which the fixation used was either CALAXO or MILAGRO screws returned for repeat radiographs for evaluation of tunnel widening, repeat MRI for evaluation of graft integrity and screw breakdown, and completion of the pain and symptom items of the KOOS (Knee injury and Osteoarthritis Outcome Score) questionnaire. Results: At a mean of three years (range, 2.5 to 4.0 years) after surgery, thirty-one patients with sixty-two CALAXO screws and thirty-six patients with seventy-two MILAGRO screws returned for repeat evaluation. Two blinded, independent reviewers found no significant differences between the two screw types when comparing radiographs for tibial or femoral tunnel widening or MRIs for graft integrity, tibial and femoral foreign body reactions, or femoral screw degradation. Both reviewers found a significant difference between the two screw types when comparing tibial screw degradation properties (p < 0.01). All analyzed CALAXO screws were rated as partially intact or degraded; the MILAGRO screws were more likely to be rated as intact. No significant differences were noted between the two screw types when comparing the two KOOS subscales. Conclusions: CALAXO screws in the tibial tunnel were more likely to be rated as degraded or partially degraded compared with MILAGRO screws at a mean of three years after implantation for ACL reconstruction. Although these newer-generation bioabsorbable screws were designed to promote osseointegration, no tunnel narrowing was noted, and in the majority of cases the remains of the screws were present at approximately three years. Level of Evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence. Peer Review: This article was reviewed by the Editor-in-Chief and one Deputy Editor, and it underwent blinded review by two or more outside experts. The Deputy Editor reviewed each revision of the article, and it underwent a final review by the Editor-in-Chief prior to publication. Final corrections and clarifications occurred during one or more exchanges between the author(s) and copyeditors. PMID:24500587

Cox, Charles L.; Spindler, Kurt P.; Leonard, James P.; Morris, Brent J.; Dunn, Warren R.; Reinke, Emily K.

2014-01-01

169

Serial Magnetic Resonance Imaging Evaluation of Operative Site After Fixation of Patellar Tendon Graft With Bioabsorbable Interference Screws in Anterior Cruciate Ligament Reconstruction  

Microsoft Academic Search

Summary: Magnetic resonance imaging (MRI) is accepted as the imaging procedure of choice for showing internal derangement of the knee. In contrast to metal implants, bioabsorbable interference screws do not produce an artifact and provide an opportunity to expand the evaluation of the postoperative anterior cruciate ligament (ACL) ligament repair. There is the potential to evaluate the implant, the graft,

Georg Lajtai; Irene Noszian; Klaus Humer; Franz Unger; Gernot Aitzetmüller; Ernst Orthner

1999-01-01

170

Arthroscopic ACL reconstruction with reverse “Y”-plasty grafts and fixation in the femur with either a bioabsorbable interference screw or an Endobutton  

Microsoft Academic Search

We propose a new reverse “Y”-plasty graft for use in anterior cruciate ligament (ACL) reconstruction that involves double tibial tunnels and a single femoral tunnel. With this technique, the hamstrings were used as autografts and fixed separately with bioabsorbable interference screws (group A) or Endobuttons (group B) in femurs. A prospective series of 63 patients underwent primary reconstruction of the

Li Wei Ping; Song Bin; Yang Rui; Song Yang; Zhang Zheng Zheng; Ding Yue

171

Biomechanical optimization of different fixation modes for a proximal femoral L-osteotomy  

PubMed Central

Background Numerous proposed surgical techniques have had minimal success in managing greater trochanter overgrowth secondary to retarded growth of the femoral capital epiphysis. For reconstruction of residual hip deformities, a novel type of proximal femur L-osteotomy was performed with satisfactory results. Although the clinical outcome was good, the biomechanical characteristics of the femur after such an osteotomy have not been clearly elucidated. Therefore, this study presents a three dimensional finite element analysis designed to understand the mechanical characteristics of the femur after the L-osteotomy. Methods A patient with left hip dysplasia was recruited as the study model for L-osteotomy. The normal right hip was used as a reference for performing the corrective surgery. Four FEA models were constructed using different numbers of fixation screws but the same osteotomy lengths together with four FEA models with the same number of fixation screws but different osteotomy lengths. The von Mises stress distributions and femoral head displacements were analyzed and compared. Results The results revealed the following: 1). The fixation devices (plate and screws) sustained most of the external loading, and the peak value of von Mises stress on the fixation screws decreased with an increasing number of screws. 2). Additional screws are more beneficial on the proximal segment than on the distal segment for improving the stability of the postoperative femur. 3). The extent of osteotomy should be limited because local stress might be concentrated in the femoral neck region with increasing length of the L-osteotomy. Conclusion Additional screw placement on the proximal segment improves stability in the postoperative femur. The cobra-type plate with additional screw holes in the proximal area might improve the effectiveness of L-osteotomies. PMID:19744345

Tai, Ching-Lung; Chen, Weng-Pin; Chen, Hsih-Hao; Lin, Chien-Yu; Lee, Mel S

2009-01-01

172

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

173

Fixin internal fixator: concept and technique.  

PubMed

This report describes the Fixin internal fixator system(a), a fracture fixation device characterised by a locking conical coupling between screw heads and titanium alloy inserts that are screwed into a stainless steel plate construct. The mechanical principles, implants, instruments and surgical technique are discussed. PMID:20585717

Petazzoni, M; Urizzi, A; Verdonck, B; Jaeger, G

2010-01-01

174

Is a single anterolateral screw-plate fixation sufficient for the treatment of spinal fractures in the thoracolumbar junction? A Biomechanical in vitro Investigation  

Microsoft Academic Search

Controversy exists about the indications, advantages and disadvantages of various surgical techniques used for anterior interbody fusion of spinal fractures in the thoracolumbar junction. The purpose of this study was to evaluate the stabilizing effect of an anterolateral and thoracoscopically implantable screw-plate system. Six human bisegmental spinal units (T12–L2) were used for the biomechanical in vitro testing procedure. Each specimen

Ulrich Schreiber; Tibor Bence; Thomas Grupp; Erwin Steinhauser; Thomas Mückley; Wolfram Mittelmeier; Rudolf Beisse

2005-01-01

175

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

PubMed

Mandibulo-maxillary fixation (MMF) screws are inserted into the bony base of both jaws in the process of fracture realignment and immobilisation. The screw heads act as anchor points to fasten wire loops or rubber bands connecting the mandible to the maxilla. Traditional interdental chain-linked wiring or arch bar techniques provide the anchorage by attached cleats, hooks, or eyelets. In comparison to these tooth-borne appliances MMF screws facilitate and shorten the way to achieve intermaxillary fixation considerably. In addition, MMF screws help to reduce the hazards of glove perforation and wire stick injuries. On the downside, MMF screws are attributed with the risk of tooth root damage and a lack of versatility beyond the pure maintenance of occlusion such as stabilizing loose teeth or splinting fragments of the alveolar process. The surgical technique of MMF screws as well as the pros and cons of the clinical application are reviewed. The adequate screw placement to prevent serious tooth root injuries is still an issue to rethink and modify conceptual guidelines. PMID:22110819

Cornelius, Carl-Peter; Ehrenfeld, Michael

2010-06-01

176

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

PubMed Central

Mandibulo-maxillary fixation (MMF) screws are inserted into the bony base of both jaws in the process of fracture realignment and immobilisation. The screw heads act as anchor points to fasten wire loops or rubber bands connecting the mandible to the maxilla. Traditional interdental chain-linked wiring or arch bar techniques provide the anchorage by attached cleats, hooks, or eyelets. In comparison to these tooth-borne appliances MMF screws facilitate and shorten the way to achieve intermaxillary fixation considerably. In addition, MMF screws help to reduce the hazards of glove perforation and wire stick injuries. On the downside, MMF screws are attributed with the risk of tooth root damage and a lack of versatility beyond the pure maintenance of occlusion such as stabilizing loose teeth or splinting fragments of the alveolar process. The surgical technique of MMF screws as well as the pros and cons of the clinical application are reviewed. The adequate screw placement to prevent serious tooth root injuries is still an issue to rethink and modify conceptual guidelines. PMID:22110819

Cornelius, Carl-Peter; Ehrenfeld, Michael

2010-01-01

177

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

178

Tibial Fixation in Anterior Cruciate Ligament Reconstruction With Bone—Patellar Tendon—Bone and Semitendinosus-Gracilis AutograftsA Comparison Between Bioabsorbable Screws and Bioabsorbable Cross-Pin Fixation  

Microsoft Academic Search

Background: Knee instability after anterior cruciate ligament reconstruction rarely manifests with activities of daily living, but it may occur in high-level sports performance, resulting in secondary injuries. Faced with these circumstances, sports orthopaedists have continued to improve on the results obtained with surgical techniques for treating knee joint injuries.Hypothesis: Transverse tibial fixation with bioabsorbable cross pins is a valid technique

Piero Volpi; Luca Marinoni; Corrado Bait; Marco Galli; Laura de Girolamo

2009-01-01

179

Biomechanical evaluation of patellar and hamstring tendon graft fixation for anterior cruciat ligament reconstruction using a poly-(D, L-lactide) interference screw  

Microsoft Academic Search

Summary  \\u000a Anterior cruciate ligament (ACL) reconstruction using autologous hamstring tendons are being performed more frequently and\\u000a satisfactory results have been reported. Advantages such as low donor site morbidity and ease of harvest as well as disadvantages\\u000a like low initial construct stiffness have been described. Recently, it has been demonstrated that graft fixation close to\\u000a the original ACL insertion sites increases

A. Weiler; R. F. G. Hoffmann; N. P. Südkamp; C. J. Siepe; N. P. Haas

1999-01-01

180

[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

181

In vitro biomechanical evaluation of fixation methods of sagittal split ramus osteotomy in mandibular setback.  

PubMed

The purpose of this study was to compare different internal fixation techniques with resorbable or titanium fixation system used in sagittal split ramus osteotomy (SSRO) for mandibular setback. Synthetic polyurethane hemimandible replicas were used. The distal segment was repositioned in a 5-mm setback position. The hemimandibles were divided into the following eight groups: resorbable miniplate (A), titanium miniplate (B), resorbable hybrid; resorbable miniplate and bicortical screw (C), titanium hybrid; titanium miniplate and bicortical screw (D), resorbable mixed hybrid; resorbable bicortical screw and titanium miniplate (E), titanium mixed hybrid; titanium bicortical screw and resorbable miniplate (F), three resorbable bicortical screws (G) and three titanium bicortical screws (H). The compression loads were applied on the incisal edge. The compression loads (N) at 5- and 10-mm displacement were analyzed (P < 0.05). Miniplate groups (A and B) were significantly weaker than the other groups (C ? H). Group (H) had greatest biomechanical stability. There was no significant difference between group (D) and group (H) at 10-mm displacement. Group (G) showed a lower load than group (H) and group (D). There was no significant difference between the hybrid and mixed hybrid groups. It was concluded that additional placement of a bicortical screw, either titanium or resorbable with a miniplate may provide significantly better stabilization. PMID:25550092

Oh, Ji-Su; Kim, Su-Gwan

2015-03-01

182

Is Supplementary Fixation Necessary in Anterior Cruciate Ligament Reconstructions?  

Microsoft Academic Search

Background: There has been concern regarding the fixation of anterior cruciate ligament reconstruction, with soft tissue grafts being strong and stiff enough to allow for early accelerated postoperative rehabilitation. Therefore, some have recommended supplementary fixation for soft tissue tibia interference screw fixation with a staple, to improve the strength and stiffness of the fixation. Unfortunately, with staple supplementation, there is

John J. Lee; Karimdad Otarodifard; Bong Jae Jun; Michelle H. McGarry; George F. Hatch; Thay Q. Lee

2011-01-01

183

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

184

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

185

A new adhesive technique for internal fixation in midfacial surgery  

Microsoft Academic Search

BACKGROUND: The current surgical therapy of midfacial fractures involves internal fixation in which bone fragments are fixed in their anatomical positions with osteosynthesis plates and corresponding screws until bone healing is complete. This often causes new fractures to fragile bones while drilling pilot holes or trying to insert screws. The adhesive fixation of osteosynthesis plates using PMMA bone cement could

Kira Endres; Rudolf Marx; Joachim Tinschert; Dieter Christian Wirtz; Christian Stoll; Dieter Riediger; Ralf Smeets

2008-01-01

186

Rigid fixation of mandibular condyle fractures.  

PubMed

This article reviews the anatomy and surgical approaches for treating fractures of the mandibular condyle with plate and screw fixation. Advantages and disadvantages of the preauricular, submandibular, intraoral, retromandibular, and rhytidectomy approaches are presented. PMID:8351124

Ellis, E; Dean, J

1993-07-01

187

Absorbable Biologically Based Internal Fixation.  

PubMed

Absorbable fixation devices have developed since first being introduced. Current products are manufactured for greater strength and stiffness and slower break down. Absorbable devices for internal fixation should not be used when fracture fragments exclusively depend on screws for bearing direct load; rather, they are preferred for maintaining adequate compression and preventing displacement when some intrinsic stability exists between bones. The main advantage of absorbable internal fixation devices is their flexibility of use. A newer generation synthesized from silk has emerged and may help to overcome current limitations and address a broader range of fixation needs. PMID:25440418

Ibrahim, Ahmed M S; Koolen, Pieter G L; Kim, Kuylhee; Perrone, Gabe S; Kaplan, David L; Lin, Samuel J

2015-01-01

188

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

PubMed Central

Purpose The use of graft tissue fixation using bioabsorbable interference screws (BISs) in anterior cruciate ligament (ACL) reconstruction offers various advantages, but limited pullout strength. Therefore, additional tibial fixation is essential for aggressive rehabilitation. We hypothesized that additional graft tissue fixation using bioabsorbable suture anchors (BSA) would provide sufficient pull-out strength. Materials and Methods Twenty four fresh frozen porcine distal femur and patellar tendon preparations were used. All specimens were divided into three groups based on additional fixation methods: A, isolated BIS; B, BIS and BSA; and C, BIS and post cortical screw. Tensile testing was carried out under an axial load. Ultimate failure load and ultimate failure load after cyclic loading were recorded. Results The ultimate failure loads after load to failure testing were 166.8 N in group A, 536.4 N in group B, and 438 N in group C; meanwhile, the ultimate failure loads after load to failure testing with cyclic loading were 140 N in group A, 466.5 N in group B, and 400 N in group C. Stiffness after load to failure testing was 16.5 N/mm in group A, 33.5 N/mm in group B, and 40 N/mm in group C. An additional BSA fixation resulted in a significantly higher ultimate failure load and stiffness than isolated BIS fixation, similar to post screw fixation. Conclusion Additional fixation using a BSA provided sufficient pullout strength for ACL reconstruction. The ultimate failure load of the BSA technique was similar to that of post cortical screws. PMID:24719145

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

2014-01-01

189

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

Microsoft Academic Search

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

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

2002-01-01

190

Double-Bundle Anterior Cruciate Ligament Reconstruction Using Hamstring Autografts and Bioabsorbable Interference Screw Fixation Prospective, Randomized, Clinical Study With 2Year Results  

Microsoft Academic Search

Results: There were no differences between the study groups preoperatively. Seventy-three patients (95%) were available at a minimum 2-year follow-up (range, 24-35 mo). The rotational stability of the knee, as evaluated by the pivot-shift test, was the best in the patients in the double-bundle group. In addition, the patients in the single-bundle groups had more graft failures than those in

Timo Järvelä; Anna-Stina Moisala; Raine Sihvonen; Sally Järvelä; Pekka Kannus; Markku Järvinen

191

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

192

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

193

Coralline hydroxyapatite granules inferior to morselized allograft around uncemented porous Ti implants: unchanged fixation by addition of concentrated autologous bone marrow aspirate.  

PubMed

We compared early fixation of titanium implants grafted with impacted allograft bone or coralline hydroxyapatite (HA) granules (Pro Osteon 200) with and without the addition of concentrated bone marrow cells (BMC). Autologous bone marrow aspirate was centrifuged to increase the BMC concentration. Four nonloaded cylindrical, porous coated titanium implants with a circumferential gap of 2.3 mm were inserted in the proximal humeri of eight dogs. Coralline HA granules +/- BMC were impacted around the two implants on one side, and allograft +/- BMC was impacted around the contra lateral implants. Observation time was 4 weeks. The implants surrounded by allograft bone had a three-fold better fixation than the HA-grafted implants. The concentration of BMC after centrifugation was increased with a factor 2.1. The addition of BMC to either of the bone graft materials had no statistically significant effects on implant fixation. The allografted implants were well osseointegrated, whereas the HA-grafted implants were largely encapsulated in fibrous tissue. The addition of concentrated autologous BMCs to the graft material had no effect on implant fixation. The HA-grafted implants were poorly anchored compared with allografted implants, suggesting that coralline HA granules should be considered a bone graft extender rather than a bone graft substitute. PMID:21793192

Baas, Jorgen; Svaneby, Dea; Jensen, Thomas Bo; Elmengaard, Brian; Bechtold, Joan; Soballe, Kjeld

2011-10-01

194

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

195

Unilateral instrumented fixation for cervical dumbbell tumors  

PubMed Central

Purpose The purpose of this study was to describe the radiological outcomes in patients with unilateral instrumented fixation for cervical dumbbell tumors. Patients and methods Fourteen consecutive individuals were included in the present study. We included Eden type II and III tumors in this cohort study and analyzed fixed segment fusion rates, screw failure with multiplanar reconstruction computed tomography (CT) scan radiographs and lateral radiographs with flexion-extension dynamic views, and immediate postoperative and last follow-up radiographs after surgery. Results The mean follow-up was 105.4 months. There were six men and eight women ranging in age from 32 to 70 years (mean age, 48 years). Twenty pedicle screws (PSs) and 11 lateral mass screws (LMSs) were used in total. There were seven patients with only PSs, four with only LMSs, and three with PSs at C2 and LMSs at C3. PS misplacement occurred in three screws of insertions including two screws with grade 1 misplacement and one screw with grade 2 misplacement, and no grade 3 misplacement occurred. All screws breached the lateral wall with no apparent superior or inferior misplacement. None of the LMSs were misplaced. Fortunately, no complication could be directly attributed to screw insertion. Radiological evidence showed that all patients achieved successful fusion with no screw loosening or breakage. However, two patients who received only LMS fixation had degenerative spondylolisthesis at the upper fusion segment at the last follow-up. Conclusions Grade 2 PS misplacement occurred in one screw of insertions. Unilateral pedicle screw fixation for cervical dumbbell tumors is a useful surgical method that can successfully fuse vertebrae with good postoperative alignment. PMID:24438086

2014-01-01

196

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

197

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

Microsoft Academic Search

To increase knee stability following anterior cruciate ligament (ACL) reconstruction, development of increasingly stronger and stiffer fixation is required. This study assessed the initial pullout force, stiffness of fixation, and failure modes for a novel hybrid fixation method combining periosteal and direct fixation using porcine femoral bone. A soft tissue graft was secured by combining both an interference screw and

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

2005-01-01

198

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

PubMed Central

Purpose Nondegradable steel-and titanium-based implants are commonly used in orthopedic surgery. Although they provide maximal stability, they are also associated with interference on imaging modalities, may induce stress shielding, and additional explantation procedures may be necessary. Alternatively, degradable polymer implants are mechanically weaker and induce foreign body reactions. Degradable magnesium-based stents are currently being investigated in clinical trials for use in cardiovascular medicine. The magnesium alloy MgYREZr demonstrates good biocompatibility and osteoconductive properties. The aim of this prospective, randomized, clinical pilot trial was to determine if magnesium-based MgYREZr screws are equivalent to standard titanium screws for fixation during chevron osteotomy in patients with a mild hallux valgus. Methods Patients (n=26) were randomly assigned to undergo osteosynthesis using either titanium or degradable magnesium-based implants of the same design. The 6 month follow-up period included clinical, laboratory, and radiographic assessments. Results No significant differences were found in terms of the American Orthopaedic Foot and Ankle Society (AOFAS) score for hallux, visual analog scale for pain assessment, or range of motion (ROM) of the first metatarsophalangeal joint (MTPJ). No foreign body reactions, osteolysis, or systemic inflammatory reactions were detected. The groups were not significantly different in terms of radiographic or laboratory results. Conclusion The radiographic and clinical results of this prospective controlled study demonstrate that degradable magnesium-based screws are equivalent to titanium screws for the treatment of mild hallux valgus deformities. PMID:23819489

2013-01-01

199

Bioabsorbable expansion bolt fixation in anterior cruciate ligament reconstruction.  

PubMed

The current study evaluated initial fixation strength of a bioabsorbable expansion bolt compared with interference screw fixation in anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft. Thirty calf tibial plateaus with adjacent patella and extensor ligaments were used. Bioabsorbable poly-L-lactide interference screws were used for graft fixation in Group I, titanium screws in Group II, and bioabsorbable poly-DL-lactide expansion bolts were used in Group III. The mean force-to-failure (+/- standard deviation) in the three groups was 487 +/- 205 N, 713 +/- 218 N, and 594 +/- 224 N, respectively. The differences between Groups I and II were significant. No statistical differences were found regarding stiffness. Graft damage was significantly less in Group III compared with screw fixation. The fixation concept of an expansion bolt shows similar fixation strength and less graft damage compared with the established interference screw fixation. Because of the total absence of torque forces in contrast to bioabsorbable screws, the risk of implant breakage is minimized. PMID:15043122

Piltz, S; Steinbauer, T; Meyer, L; Plitz, W; Andress, H J; Lob, G

2004-01-01

200

Biomechanical Analysis of Femoral Tunnel Pull-out Angles for Anterior Cruciate Ligament Reconstruction With Bioabsorbable and Metal Interference Screws  

Microsoft Academic Search

Background: Fixation strength of metal and bioabsorbable interference screws has not been evaluated while varying the anterior cruciate ligament graft tension angle.Hypothesis: There is no difference in fixation strength between 2 types of interference screws for anterior cruciate ligament graft fixation while the graft tension angle is varied relative to the femoral tunnel.Study Design: Controlled laboratory study.Methods: Forty-eight anterior cruciate

Alan L. Zhang; Yuri M. Lewicky; Richard Oka; Andrew Mahar; Robert Pedowitz

2007-01-01

201

Treatment of fractures of the condylar head with resorbable pins or titanium screws: an experimental study.  

PubMed

We aimed to compare in vivo the stability of fixation of condylar fractures in sheep using sonic bone welding and standard titanium screws. We assessed stability of the osteosynthesis and maintenance of the height of the mandibular ramus. Height decreased slightly in both groups compared with the opposite side. The volume of the condyle increased considerably in both groups mainly because callus had formed. The results showed no significant disadvantages for pin fixation compared with osteosynthesis using titanium screws. PMID:22901526

Schneider, Matthias; Loukota, Richard; Kuchta, Anne; Stadlinger, Bernd; Jung, Roland; Speckl, Katrin; Schmiedekampf, Robert; Eckelt, Uwe

2013-07-01

202

Internal fracture fixation in patients with osteoporosis.  

PubMed

Because of the decreased holding power of plate-and-screw fixation in osteoporotic bone fractures, internal fixation can have a high failure rate, ranging from 10% to 25%. Screws placed into cortical bone have better resistance to pullout than do those placed into adjacent trabecular bone. Plates should not be used to bridge unstable regions of bony comminution in osteoporotic patients. Fixation stability is optimized by securing stable bone contact across the fracture site and by placing screws both as close to and as far from the fracture as possible. Intentional shortening can improve stability and load sharing of the fracture construct. Structural bone graft or other types of fillers can be used to fill voids when comminution prevents stable contact. Load-sharing fixation devices such as the sliding hip screw, intramedullary nail, antiglide plate, and tension band constructs are better alternatives for osteoporotic metaphyseal locations. Proper planning is essential for improved fracture fixation in this high-risk patient group. PMID:12670137

Cornell, Charles N

2003-01-01

203

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

PubMed Central

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

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

2014-01-01

204

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

205

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

206

Juvenile idiopathic scoliosis treated with posterior arthrodesis and segmental pedicle screw instrumentation before the age of 9 years: a 5-year follow-up  

Microsoft Academic Search

STUDY DESIGN: Retrospective study. OBJECTIVE: To evaluate the radiological results of fusion with segmental pedicle screw fixation in juvenile idiopathic scoliosis with a minimum 5-year follow-up. SUMMARY OF BACKGROUND DATA: Progression of spinal deformity after posterior instrumentation and fusion in immature patients has been reported by several authors. Segmental pedicle screw fixation has been shown to be effective in controlling

Ahmet Y?lmaz ?arlak; Halil Atmaca; Levent Buluç; Bilgehan Tosun; Resul Musao?lu

2009-01-01

207

Open pisiform fracture: excision or internal fixation?  

PubMed Central

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

Agathangelidis, Filon; Boutsiadis, Achilleas; Ditsios, Konstantinos

2013-01-01

208

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

209

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

210

ORV Arthroscopic Reduction and Internal Fixation of Tibial Eminence Fractures.  

PubMed

Tibial eminence fractures are an uncommon but well-described avulsion of the anterior cruciate ligament. Treatment principles are based on the amount and pattern of fracture displacement. Management has evolved from closed reduction and immobilization to arthroscopic reduction and internal fixation followed by early rehabilitation. Various fixation methods have evolved, ranging from arthroscopic reduction and percutaneous screw fixation to arthroscopic suture repair. We present a technique for arthroscopic reduction and internal fixation using a cannulated drill bit and high-strength suture. This technique facilitates anatomic reduction with uncomplicated tunnel placement and suture passing in an effort to allow strong fixation and early rehabilitation. PMID:24400179

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

2013-01-01

211

ORV Arthroscopic Reduction and Internal Fixation of Tibial Eminence Fractures  

PubMed Central

Tibial eminence fractures are an uncommon but well-described avulsion of the anterior cruciate ligament. Treatment principles are based on the amount and pattern of fracture displacement. Management has evolved from closed reduction and immobilization to arthroscopic reduction and internal fixation followed by early rehabilitation. Various fixation methods have evolved, ranging from arthroscopic reduction and percutaneous screw fixation to arthroscopic suture repair. We present a technique for arthroscopic reduction and internal fixation using a cannulated drill bit and high-strength suture. This technique facilitates anatomic reduction with uncomplicated tunnel placement and suture passing in an effort to allow strong fixation and early rehabilitation. PMID:24400179

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

2013-01-01

212

A Biomechanical Comparison of Three 1.5-mm Plate and Screw Configurations and a Single 2.0-mm Plate for Internal Fixation of a Mandibular Condylar Fracture.  

PubMed

The most stable pattern of internal fixation for mandibular condyle fractures is an area of ongoing discussion. This study investigates the stability of three patterns of plate fixation using readily available, commercially pure titanium implants. Finite element models of a simulated mandibular condyle fracture were constructed. The completed models were heterogeneous in bone material properties, contained approximately 1.2 million elements and incorporated simulated jaw adducting musculature. Models were run assuming linear elasticity and isotropic material properties for bone. No human subjects were involved in this investigation. The stability of the simulated condylar fracture reduced with the different implant configurations, and the von Mises stresses of a 1.5-mm X-shaped plate, a 1.5-mm rectangular plate, and a 1.5-mm square plate (all Synthes (Synthes GmbH, Zuchwil, Switzerland) were compared. The 1.5-mm X plate was the most stable of the three 1.5-mm profile plate configurations examined and had comparable mechanical performance to a single 2.0-mm straight four-hole plate. This study does not support the use of rectangular or square plate patterns in the open reduction and internal fixation of mandibular condyle fractures. It does provide some support for the use of a 1.5-mm X plate to reduce condylar fractures in selected clinical cases. PMID:25136411

Aquilina, Peter; Parr, William C H; Chamoli, Uphar; Wroe, Stephen; Clausen, Philip

2014-09-01

213

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

214

Internal fixation of nonunions.  

PubMed

We review the two major types of internal fixation of nonunions (plating and intramedullary nailing), and analyze nonunions in different locations (upper and lower extremities). Depending on the type and the location of the nonunion, plating or intramedullary nailing may be selected. Both have advantages and disadvantages: plating requires opening the nonunion site, which entails some damage to the soft tissues, and carries with it a risk of secondary infection. With plating, it often is impossible to do a real decortication because the periosteum may be thin and poorly adherent to bone, and the quality of bone may prove insufficient to achieve good fixation with most of the screws. However, plating still is used in metaphyseal nonunions, and angular deformities may be corrected by applying a plate under tension on the convex side of the bone. Nailing can be done percutaneously in numerous cases; it has a smaller risk of infection but, should an infection be present, there is a risk that it may spread over the entire length of the medullary cavity. Nailing stimulates bone formation, but noninterlocking nails may cause shortening and rotational instability of the nonunion site. Plate fixation was popular approximately 20 years ago, but now has been largely superseded by intramedullary nailing except for proximal or distal nonunions. Dynamic locking nails are preferable. Successful treatment of nonunions often requires several consecutive surgical actions and a global strategy must be established from the beginning, taking care not to interfere with the successive steps. PMID:15021126

Rodriguez-Merchan, E Carlos; Gomez-Castresana, Fernando

2004-02-01

215

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

PubMed Central

It is well demonstrated that the responses of plants to elevated atmospheric CO2 concentration are species-specific and dependent on environmental conditions. We investigated the responses of a subshrub legume species, Caragana microphylla Lam., to elevated CO2 and nitrogen (N) addition using open-top chambers in a semiarid temperate grassland in northern China for three years. Measured variables include leaf photosynthetic rate, shoot biomass, root biomass, symbiotic nitrogenase activity, and leaf N content. Symbiotic nitrogenase activity was determined by the C2H2 reduction method. Elevated CO2 enhanced photosynthesis and shoot biomass by 83% and 25%, respectively, and the enhancement of shoot biomass was significant only at a high N concentration. In addition, the photosynthetic capacity of C. microphylla did not show down-regulation under elevated CO2. Elevated CO2 had no significant effect on root biomass, symbiotic nitrogenase activity and leaf N content. Under elevated CO2, N addition stimulated photosynthesis and shoot biomass. By contrast, N addition strongly inhibited symbiotic nitrogenase activity and slightly increased leaf N content of C. microphylla under both CO2 levels, and had no significant effect on root biomass. The effect of elevated CO2 and N addition on C. microphylla did not show interannual variation, except for the effect of N addition on leaf N content. These results indicate that shoot growth of C. microphylla is more sensitive to elevated CO2 than is root growth. The stimulation of shoot growth of C. microphylla under elevated CO2 or N addition is not associated with changes in N2-fixation. Additionally, elevated CO2 and N addition interacted to affect shoot growth of C. microphylla with a stimulatory effect occurring only under combination of these two factors. PMID:22046376

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

2011-01-01

216

SOS and UVM Pathways Have Lesion-Specific Additive and Competing Effects on Mutation Fixation at Replication-Blocking DNA Lesions  

PubMed Central

Escherichia coli cells have multiple mutagenic pathways that are induced in response to environmental and physiological stimuli. Unlike the well-investigated classical SOS response, little is known about newly recognized pathways such as the UVM (UV modulation of mutagenesis) response. In this study, we compared the contributions of the SOS and UVM pathways on mutation fixation at two representative noninstructive DNA lesions: 3,N4-ethenocytosine (?C) and abasic (AP) sites. Because both SOS and UVM responses are induced by DNA damage, and defined UVM-defective E. coli strains are not yet available, we first constructed strains in which expression of the SOS mutagenesis proteins UmuD? and UmuC (and also RecA in some cases) is uncoupled from DNA damage by being placed under the control of a heterologous lac-derived promoter. M13 single-stranded viral DNA bearing site-specific lesions was transfected into cells induced for the SOS or UVM pathway. Survival effects were determined from transfection efficiency, and mutation fixation at the lesion was analyzed by a quantitative multiplex sequence analysis procedure. Our results suggest that induction of the SOS pathway can independently elevate mutagenesis at both lesions, whereas the UVM pathway significantly elevates mutagenesis at ?C in an SOS-independent fashion and at AP sites in an SOS-dependent fashion. Although mutagenesis at ?C appears to be elevated by the induction of either the SOS or the UVM pathway, the mutational specificity profiles for ?C under SOS and UVM pathways are distinct. Interestingly, when both pathways are active, the UVM effect appears to predominate over the SOS effect on mutagenesis at ?C, but the total mutation frequency is significantly increased over that observed when each pathway is individually induced. These observations suggest that the UVM response affects mutagenesis not only at class 2 noninstructive lesions (?C) but also at classical SOS-dependent (class 1) lesions such as AP sites. Our results add new layers of complexity to inducible mutagenic phenomena: DNA damage activates multiple pathways that have lesion-specific additive as well as suppressive effects on mutation fixation, and some of these pathways are not directly regulated by the SOS genetic network. PMID:10049383

Rahman, M. Sayeedur; Humayun, M. Zafri

1999-01-01

217

SOS and UVM pathways have lesion-specific additive and competing effects on mutation fixation at replication-blocking DNA lesions.  

PubMed

Escherichia coli cells have multiple mutagenic pathways that are induced in response to environmental and physiological stimuli. Unlike the well-investigated classical SOS response, little is known about newly recognized pathways such as the UVM (UV modulation of mutagenesis) response. In this study, we compared the contributions of the SOS and UVM pathways on mutation fixation at two representative noninstructive DNA lesions: 3,N4-ethenocytosine (epsilonC) and abasic (AP) sites. Because both SOS and UVM responses are induced by DNA damage, and defined UVM-defective E. coli strains are not yet available, we first constructed strains in which expression of the SOS mutagenesis proteins UmuD' and UmuC (and also RecA in some cases) is uncoupled from DNA damage by being placed under the control of a heterologous lac-derived promoter. M13 single-stranded viral DNA bearing site-specific lesions was transfected into cells induced for the SOS or UVM pathway. Survival effects were determined from transfection efficiency, and mutation fixation at the lesion was analyzed by a quantitative multiplex sequence analysis procedure. Our results suggest that induction of the SOS pathway can independently elevate mutagenesis at both lesions, whereas the UVM pathway significantly elevates mutagenesis at epsilonC in an SOS-independent fashion and at AP sites in an SOS-dependent fashion. Although mutagenesis at epsilonC appears to be elevated by the induction of either the SOS or the UVM pathway, the mutational specificity profiles for epsilonC under SOS and UVM pathways are distinct. Interestingly, when both pathways are active, the UVM effect appears to predominate over the SOS effect on mutagenesis at epsilonC, but the total mutation frequency is significantly increased over that observed when each pathway is individually induced. These observations suggest that the UVM response affects mutagenesis not only at class 2 noninstructive lesions (epsilonC) but also at classical SOS-dependent (class 1) lesions such as AP sites. Our results add new layers of complexity to inducible mutagenic phenomena: DNA damage activates multiple pathways that have lesion-specific additive as well as suppressive effects on mutation fixation, and some of these pathways are not directly regulated by the SOS genetic network. PMID:10049383

Rahman, M S; Humayun, M Z

1999-03-01

218

Biomechanical testing of implant free wedge shaped bone block fixation for bone patellar tendon bone anterior cruciate ligament reconstruction in a bovine model  

PubMed Central

Background The use of an interference fit wedged bone plug to provide fixation in the tibial tunnel when using bone-patellar tendon-bone autograft for anterior cruciate ligament reconstruction offers many theoretic advantages including the potential to offer a more economical and biological alternative to screw fixation. This technique has not been subjected to biomechanical testing. We hypothesised that a wedged bone plug fixation technique provides equivalent tensile load to failure as titanium interference screw fixation. Methods In a controlled laboratory setting, anterior cruciate ligament reconstruction was performed in 36 bovine knees using bone-patella-bone autograft. In 20 knees tibial fixation relied upon a standard cuboid bone block and interference screw. In eight knees a wedge shaped bone block with an 11 mm by 10 mm base without a screw was used. In a further eight knees a similar wedge with a 13 mm by 10 mm base was used. Each specimen used a standard 10 mm tibial tunnel. The reconstructions were tested biomechanically in a physiological environment using an Instron machine to compare ultimate failure loads and modes of failure. Results Statistical analysis revealed no significant difference between wedge fixation and screw fixation (p = 0.16), or between individual groups (interference screw versus 11 mm versus 13 mm wedge fixation) (P = 0.35). Conclusions Tibial tunnel fixation using an impacted wedge shaped bone block in anterior cruciate ligament reconstruction has comparable ultimate tensile strength to titanium interference screw fixation. PMID:20813059

2010-01-01

219

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

220

Biological fixation of endosseous implants.  

PubMed

Primary implant stability is ensured by a mechanical fixation of implants. However, during implant healing a biological anchorage is necessary to achieve final osseointegration. Aim of this study was to investigate the histological aspects of biological fixation around titanium screws. Forty-eight titanium screws with different surfaces (smooth, plasma sprayed, sand blasted) were inserted in tibiae and femura of sheep and analyzed by light microscope and SEM 1 hour, 14 and 90 days after implantation. One hour after implantation the implant-bone gap was filled with a blood clot and host bone chips arising from burr surgical preparation or friction during implant insertion. Fourteen days after implantation new trabecular bone and enveloped bone chips were observed in the gap: no osteogenesis developed where implant threads were in contact with host bone. Ninety days after surgery all trabecular bone and most of the bone chips were substituted by a mature lamellar bone with few marrow spaces. Our results suggest that the trabecular bone and bone chips represent a three-dimensional network ensuring a biological implant fixation in all different implant surfaces 2 weeks after surgery. Host bone chips could favour the peri-implant osteogenesis. Inter-trabecular and implant-trabecular marrow spaces of both trabecular and lamellar bone may favour the peri-implant bone turnover. PMID:16233979

Franchi, M; Fini, M; Martini, D; Orsini, E; Leonardi, L; Ruggeri, A; Giavaresi, G; Ottani, V

2005-01-01

221

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

PubMed

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

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

2014-07-01

222

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

223

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

224

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

225

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

226

Femoral cement pressurisation for hip arthroplasty in previously fixated hips: An experimental study  

Microsoft Academic Search

IntroductionIt is common to use a cemented total hip replacement following failed hip screw fixation of a fractured femoral neck; this solution, however, is complicated by the presence of the holes that are left in the femur when the screws are removed. These holes can allow cement to leak out while being pressurised. The aim of this study was to

S. E. McMahon; F. Alvi; J. G. Lemon; M. E. Lovell

2010-01-01

227

Is polymethyl methacrylate a viable option for salvaging lateral mass screw failure in the subaxial cervical spine?  

PubMed

Study Design?Biomechanical analysis of lateral mass screw pullout strength. Objective?We compare the pullout strength of our bone cement-revised lateral mass screw with the standard lateral mass screw. Methods?In cadaveric cervical spines, we simulated lateral mass screw "cutouts" unilaterally from C3 to C7. We salvaged fixation in the cutout side with polymethyl methacrylate (PMMA) or Cortoss cement (Orthovita, Malvern, Pennsylvania, United States), allowed the cement to harden, and then drilled and placed lateral mass screws back into the cement-augmented lateral masses. On the contralateral side, we placed standard lateral mass screws into the native, or normal lateral, masses and then compared pullout strength of the cement-augmented side to the standard lateral mass screw. For pullout testing, each augmentation group was fixed to a servohydraulic load frame and a specially designed pullout fixture was attached to each lateral mass screw head. Results?Quick-mix PMMA-salvaged lateral mass screws required greater force to fail when compared with native lateral mass screws. Cortoss cement and PMMA standard-mix cement-augmented screws demonstrated less strength of fixation when compared with control-side lateral mass screws. Attempts at a second round of cement salvage of the same lateral masses led to more variations in load to failure, but quick-mix PMMA again demonstrated greater load to failure when compared with the nonaugmented control lateral mass screws. Conclusion?Quick-mix PMMA cement revision equips the spinal surgeon with a much needed salvage option for a failed lateral mass screw in the subaxial cervical spine. PMID:25649421

Gallizzi, Michael A; Kuhns, Craig A; Jenkins, Tyler J; Pfeiffer, Ferris M

2015-02-01

228

Polymethylmethacrylate augmentation of the pedicle screw: the cement distribution in the vertebral body  

Microsoft Academic Search

Many studies have proven that the polymethylmethacrylate (PMMA) augmentation of the pedicle screw can significantly increase\\u000a stiffness and strength of spinal fixation. Some major complications have also been reported. However, there are no reports\\u000a discussing cement distribution and its morphology in the osteoporotic vertebral body, which is critical in the analysis of\\u000a the biomechanical strength of the pedicle screw and

Ming-Hsien Hu; Hung Ta H. Wu; Ming-Chau Chang; Wing-Kuang Yu; Shih-Tien Wang; Chien-Lin Liu

229

Sterile Pretibial Abscess After Anterior Cruciate Reconstruction From Bioabsorbable Interference Screws: A Report of 2 Cases  

Microsoft Academic Search

We report 2 cases of extra-articular pretibial sterile abscesses with minimal osteolysis after anterior cruciate ligament reconstruction with poly-L-lactic acid bioabsorbable interference screw fixation. No joint involvement was evident in either case. Both patients underwent surgical exploration for incision, drainage, and excision with debridement of the biodegradable screw debris from the tibial bone tunnel. The cystic area in case 1

Benjamin T. Busfield; Lesley J. Anderson

2007-01-01

230

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

231

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

232

A biomechanical study comparing two fixation methods in depression fractures of the lateral tibial plateau in porcine bone  

PubMed Central

Background A novel method of fixation has been described for the treatment of pure depression fractures of the lateral tibial plateau. Fracture fragments are elevated through a reamed transtibial tunnel. An interference screw is then passed into the tunnel to buttress fracture fragments from beneath. This method of fixation has perceived benefits but there have been no studies to demonstrate that the technique is biomechanically sound. The aim of our study is to compare traditional parallel, subchondral screw fixation with the use of an interference screw, assessing maintenance of fracture reduction following simulated post-operative loading, and overall construct strength. Methods Depression fractures of the lateral tibial plateau were simulated in 14 porcine knees. Fracture fragments were elevated through a reamed transtibial tunnel and samples were randomly assigned to a fixation method. 7 knees underwent traditional fixation with parallel subcortical cannulated screws, the remainder were stabilized using a single interference screw passed through the transtibial tunnel. Following preloading, each tibia was cyclically loaded from 0 to 500 Newtons for 5,000 cycles using a Nene testing machine. Displacement of the depressed fracture fragments were measured pre and post loading. Samples were then loaded to failure to test ultimate strength of each construct. Results The depression displacement of the fractures fixed using cannulated screws was on average 0.76 mm, in comparison to 0.61mm in the interference screw group (p=0.514). Mechanical failure of the cannulated screw constructs occurred at a mean of 3400 N. Failure of the transtibial interference screw constructs occurred at a mean of 1700 N (p<0.01). In both groups the mechanism of ultimate failure was splitting of the tibial plateau. Conclusion These results demonstrate the increased biomechanical strength of parallel, cannulated screws for depression fractures of the tibial plateau, however the use of a transtibial interference screw may be a viable method of fixation under physiological loads. PMID:24001211

2013-01-01

233

C7 fracture treated with a pedicle screw system under navigation guidance.  

PubMed

A 51-year-old woman with traumatic fracture-subluxation of C6-C7 vertebrae was treated by pedicle screw fixation. Among several methods for surgical treatment of the cervical spine, this technique provides a more rigid anchor to prevent collapsing or instability of the spinal column, particularly at the cervicothoracic junction. However, the risk of injuring the adjacent neurovascular structures cannot be completely eliminated. The characteristics of the cervicothoracic junction, surgical approaches and pedicle screw fixation techniques are emphasised. PMID:15455171

Mahadewa, T; Mizuno, J; Inoue, T; Nakagawa, H

2004-10-01

234

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

235

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

236

Subtrochanteric femur fracture after removal of screws for femoral neck fracture in a child.  

PubMed

Displaced femoral neck fractures are rare in children and are associated with a high rate of complications. Subtrochanteric fractures after cannulated screw fixation of femoral neck fractures in adults are well recognized, and there are several reports on the topic. However, there are no reports on complications related to hardware or subtrochanteric fractures after removal of the screws in the treatment of femoral neck fractures in children. Here we report the case of a 10-year-old boy who sustained a subtrochanteric fracture after the screw removal and healing that followed a femoral neck fracture. PMID:25566556

Song, Kwang Soon; Lee, Si Wook

2015-01-01

237

Addition  

NSDL National Science Digital Library

Addition games First let\\'s practice our Fast Addition Let\\'s try to beat the Addition Machine You can help the bear while he is Catching Tens. Try to make your own picture using addition skills at the Hidden Picture Addition addition game. ...

Mchale, Ms.

2007-10-25

238

Foreign body reaction to a bioabsorbable interference screw after anterior cruciate ligament reconstruction  

PubMed Central

Bioabsorbable interference screws have been effective for graft fixation in anterior cruciate ligament (ACL) reconstruction. The overall complication rate associated with the use of these screws is low but some unique problems have been reported in the literature. We present a case of unusual tissue reaction to a bioabsorbable interference screw following ACL reconstruction. A young male underwent ACL reconstruction, during which a bioabsorbable interference screw was used for graft fixation at the tibial end. The patient presented with a pretibial swelling at 30 months after the operation. Exploration revealed chalky white remnants of the bioabsorbable screw with no evidence of infection. Histological studies confirmed a foreign body reaction against screw remnants with the presence of multinucleated giant cells. The patient had a full recovery with no compromise to graft stability. Bioabsorbable interference screws are usually inert but can initiate a tissue reaction. The presentation can be as late as 2–3 years postoperatively and may mimic an infection. Satisfactory results can be achieved by proper exploration and debridement. PMID:21686509

Umar, Muhammad; Baqai, Nadeem; Peck, Christopher

2009-01-01

239

Anterior subcutaneous internal fixation for treatment of unstable pelvic fractures  

PubMed Central

Background Fractures of the pelvic ring including disruption of the posterior elements in high-energy trauma have both high morbidity and mortality rates. For some injury pattern part of the initial resuscitation includes either external fixation or plate fixation to close the pelvic ring and decrease blood loss. In certain situations – especially when associated with abdominal trauma and the need to perform laparotomies – both techniques may put the patient at risk of either pintract or deep plate infections. We describe an operative approach to percutaneously close and stabilize the pelvic ring using spinal implants as an internal fixator and report the results in a small series of patients treated with this technique during the resuscitation phase. Findings Four patients were treated by subcutaneous placement of an internal fixator. Screw fixation was carried out by minimally invasive placement of two supra-acetabular iliac screws. Afterwards, a subcutaneous transfixation rod was inserted and attached to the screws after reduction of the pelvic ring. All patients were allowed to fully weight-bear. No losses of reduction or deep infections occurred. Fracture healing was uneventful in all cases. Conclusion Minimally invasive fixation is an alternative technique to stabilize the pelvic ring. The clinical results illustrate that this technique is able to achieve good results in terms of maintenance of reduction the pelvic ring. Also, abdominal surgeries no longer put the patient at risk of infected pins or plates. PMID:24606833

2014-01-01

240

Tacks: a new technique for craniofacial fixation.  

PubMed

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

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

2001-11-01

241

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

242

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

243

Numerical simulation research to both the external fixation surgery scheme of intertrochanteric fracture and the healing process, and its clinical application.  

PubMed

In this paper, the single arm external fixation of intertrochanteric fracture healing process after surgery was simulated to obtain a postoperative fracture healing and stress distribution in the external fixator. Firstly CT images of intertrochanteric fracture are reconstructed into the femur solid model. Then based, the external fixator is installed on the model, which lastly formed a finite element model of unilateral external fixation for intertrochanteric fracture. The calculated results show: during the beginning of the fracture healing, there is much higher stress in both screws and femur in the model with solid screws than that in the model with hollow screw. The stress of the femur in the model with hollow screw is more evenly. During the middle time of Fracture healing, stress in the femoral head significantly decreases. And the stress at fracture site gradually increased with the healing occurrence. According to the results, the authors designed hollow screws to use external fixation surgery. Surgery confirmed that the use of hollow screws in fractures treatment can satisfy the strength requirements, and can effectively reduce operative time, less patient suffering. The research for external fixation can provide a reference, and promote the use of external fixation hollow screws. PMID:24211947

Wang, Xian-Kang; Ye, Jin-Duo; Gu, Fu-Shun; Wang, Ai-guo; Zhang, Chun-Qiu; Tian, Qian-Qian; Li, Xue; Dong, Li-Min

2014-01-01

244

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

245

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

246

Additives  

NASA Technical Reports Server (NTRS)

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

Smalheer, C. V.

1973-01-01

247

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.

248

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

Microsoft Academic Search

A change in the practice of a single surgeon provided an opportunity for retrospective comparison of comparable cohorts treated\\u000a with percutaneous fixation (17 patients) or a volar plate and screws (23 patients) an average of 30 months after surgery.\\u000a The final evaluation was performed according to the Gartland and Werley and Mayo rating systems and the DASH questionnaire.\\u000a There were no

Santiago A. Lozano-Calderón; Job N. Doornberg; David Ring

2008-01-01

249

Computer-assisted periacetabular screw placement: Comparison of different fluoroscopy-based navigation procedures with conventional technique.  

PubMed

The current gold standard for operatively treated acetabular fractures is open reduction and internal fixation. Fractures with minimal displacement may be stabilised by minimally invasive methods such as percutaneous periacetabular screws. However, their placement is a demanding procedure due to the complex pelvic anatomy. The aim of this study was to evaluate the accuracy of periacetabular screw placement assessing pre-defined placement corridors and comparing different fluoroscopy-based navigation procedures and the conventional technique. For each screw an individual periacetabular placement corridor was preoperatively planned using the planning software iPlan CMF(©) 3.0 (BrainLAB). 210 screws (retrograde anterior column screws, retrograde posterior column screws, supraacetabular ilium screws) were placed in an artificial Synbone pelvis model (30 hemipelves) and in human cadaver specimen (30 hemipelves). 2D- and 3D-fluoroscopy-based navigation procedures were compared to the conventional technique. Insertion time and radiation exposure to specimen were also recorded. The achieved screw position was postoperatively assessed by an Iso-C(3D) scan. Perforations of bony cortices or articular surfaces were analysed and the screw deviation severity (difference of the operatively achieved screw position and the preoperatively planned screw position in reference to the pre-defined corridors) was determined using image fusion. Using 3D-fluoroscopy-based navigation, the screw perforation rate (7%) was significantly lower compared to 2D-fluoroscopy-based navigation (20%). For all screws, the deviation severity was significantly lower using a 3D- compared to a 2D-fluoroscopy-based navigation and the conventional technique. Analysing the posterior column screws, the screw deviation severity was significantly lower using 3D- compared to 2D-fluoroscopy-based navigation. However, for the anterior column screw, the screw deviation severity was similar regardless of the imaging method. Despite the advantages of the 3D-fluoroscopy-based navigation, this method led to significantly longer total procedure and fluoroscopic times, and the applied radiation dose was significantly higher. Percutaneous periacetabular screw placement is demanding. Especially for posterior column screws, due to a lower perforation rate and a higher accuracy in periacetabular screw placement, 3D-fluoroscopy-based navigation procedure appears to be the method of choice for image guidance in acetabular surgery. PMID:20728881

Ochs, Björn Gunnar; Gonser, Christoph; Shiozawa, Thomas; Badke, Andreas; Weise, Kuno; Rolauffs, Bernd; Stuby, Fabian Maria

2010-12-01

250

Small Joint Fusions of the Hand using the Herbert Bone Screw  

Microsoft Academic Search

The Herbert Bone Screw has a thread at both ends and was originally developed for internal fixation of fractured scaphoid bones. The two main advantages of compression and no head, make it most suitable for internal splinting of the small joints of the hand.The authors have used this device on thirty-nine joints in ten different sites of the hand, and

D. K. FAITHFULL; T. J. HERBERT

1984-01-01

251

The use of silk-based devices for fracture fixation  

NASA Astrophysics Data System (ADS)

Metallic fixation systems are currently the gold standard for fracture fixation but have problems including stress shielding, palpability and temperature sensitivity. Recently, resorbable systems have gained interest because they avoid removal and may improve bone remodelling due to the lack of stress shielding. However, their use is limited to paediatric craniofacial procedures mainly due to the laborious implantation requirements. Here we prepare and characterize a new family of resorbable screws prepared from silk fibroin for craniofacial fracture repair. In vivo assessment in rat femurs shows the screws to be self-tapping, remain fixed in the bone for 4 and 8 weeks, exhibit biocompatibility and promote bone remodelling. The silk-based devices compare favourably with current poly-lactic-co-glycolic acid fixation systems, however, silk-based devices offer numerous advantages including ease of implantation, conformal fit to the repair site, sterilization by autoclaving and minimal inflammatory response.

Perrone, Gabriel S.; Leisk, Gary G.; Lo, Tim J.; Moreau, Jodie E.; Haas, Dylan S.; Papenburg, Bernke J.; Golden, Ethan B.; Partlow, Benjamin P.; Fox, Sharon E.; Ibrahim, Ahmed M. S.; Lin, Samuel J.; Kaplan, David L.

2014-03-01

252

External fixation and limited internal fixation for complex fractures of the tibial plateau.  

PubMed

Twenty-one complex fractures of the tibial plateau in twenty patients were treated with closed reduction, interfragmental screw fixation of the articular fragments, and application of a unilateral half-pin external fixator. The average duration of external fixation was twelve weeks (range, three to twenty weeks). The fixator was left in situ until the fracture had united in all but two patients. All of the fractures healed. The complications with this technique were attributable primarily to the proximal half-pins of the external fixator. Seven patients needed antibiotics for an infection at a pin site, and two had septic arthritis that necessitated arthrotomy and débridement. The average duration of follow-up was thirty-eight months. The range of motion of nineteen of the twenty-one knees was at least a 115-degree arc. Laxity was evident in seven knees, but no patient complained of instability of the knee. Radiographs showed malalignment of more than 6 degrees in three knees compared with the normal, contralateral knee and evidence of post-traumatic osteoarthrosis in five knees. The Iowa knee score, determined for nineteen patients, averaged 87 points (range, 55 to 100 points). The SF-36 general health survey demonstrated that most patients had function close to that of age-matched controls. We concluded that external fixation with limited internal fixation is a satisfactory technique for the treatment of selected complex fractures of the tibial plateau. PMID:7744891

Marsh, J L; Smith, S T; Do, T T

1995-05-01

253

Tibial bone bridge and bone block fixation in double-bundle anterior cruciate ligament reconstruction without hardware: a technical note.  

PubMed

Current techniques for tibial graft fixation in four tunnels double bundle (DB) anterior cruciate ligament (ACL) reconstruction are by means of two interference screws or by extracortical fixation with a variety of different implants. We introduce a new alternative tibial graft fixation technique for four tunnels DB ACL reconstruction without hardware. About 3.5 to 5.5 cm bone cylinder with a diameter of 7 mm is harvested from the anteromedial (and posterolateral) tibial bone tunnel (s) with a core reamer. The anteromedial (AM) and posterolateral (PL) hamstring tendon grafts (or alternatively tendon allografts) are looped over an extracortical femoral fixation device and cut in length according to the total femorotibial bone tunnel length. The distal 3 cm of each, the AM- and PL bundle graft are armed with two strong No. 2 nonresorbable sutures and the four suture ends of each graft are tied to each other over the 2 cm wide cortical bone bridge between the tibial AM and PL bone tunnel. In addition the AM- and/or PL bone block which was harvested at the beginning of the procedure is re-impacted into the two tibial bone tunnels. A dorsal splint is used for the first two postoperative weeks and physiotherapy is started the second postoperative day. The technique is applicable for four tunnels DB ACL reconstruction in patients with good tibial bone quality. The strong fixation technique preserves important tibial bone stock and avoids the use of tibial hardware which knows disadvantages. It does increase tendon to bone contact and tendon-to-bone healing and does reduce implant costs to those of a single bundle (SB) ACL reconstruction. Revision surgery may be facilitated significantly but the technique should not be used when bony defects are present. In case of insufficient bone bridge fixation or bone blocks hardware fixation can be applied as usual. PMID:18066528

Siebold, R; Thierjung, H; Cafaltzis, K; Hoeschele, E; Tao, J; Ellert, T

2008-04-01

254

Navigated Percutaneous Screw Fixation of a Periprosthetic Acetabular Fracture  

Microsoft Academic Search

Periprosthetic fractures are severe complications of total hip arthroplasty with increasing incidence. Most fractures are localized around the femoral component of prosthesis, whereas periacetabular fractures are rare and their management is difficult. In most cases, an operative procedure with revision and exchange of the acetabular cup is necessary. The approaches are demanding and an increased risk of complications is reported.

Florian Gras; Ivan Marintschev; Kajetan Klos; Albert Fujak; Thomas Mückley; Gunther O. Hofmann

2010-01-01

255

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

PubMed Central

Objective We compared the radiological and clinical outcomes between patients who underwent posterior fixation alone and supplemented with fusion following the onset of thoracolumbar burst fractures. In addition, we also evaluated the necessity of posterolateral fusion for patients treated with posterior pedicle screw fixation. Methods From January 2007 to December 2009, 46 consecutive patients with thoracolumbar burst fracture were included in this study. On the basis of posterolateral fusion, we divided our patients into the non-fusion group and the fusion group. The radiological assessment was performed according to the Cobb's method, and results were obtained at immediately, 3, 6, 12 months after surgery. The clinical outcomes were evaluated using the modified Mcnab criteria at the final follow-up. Results The demographic data and the mean follow-up period were similar between the two groups. Patients of both groups achieved satisfactory clinical outcomes. The mean loss of kyphosis correction showed that patients of both groups experienced loss of correction with no respect to whether they underwent the posterolateral fusion. There was no significant difference in the degree of loss of correction at any time points of the follow-up between the two groups. In addition, we also compared the effect of fixed levels (i.e., short versus long segment) on loss of correction between the two groups and there was no significant difference. There were no major complications postoperatively and during follow-up period. Conclusion We suggest that posterolateral fusion may be unnecessary for patients with thoracolumbar burst fractures who underwent posterior pedicle screw fixation. PMID:23133723

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

2012-01-01

256

Bovine Bone Screws: Metrology and Effects of Chemical Processing and Ethylene Oxide Sterilization on Bone Surface and Mechanical Properties  

Microsoft Academic Search

We assess the effects of chemical processing, ethylene oxide sterilization, and threading on bone surface and mechanical properties of bovine undecalcified bone screws. In addition, we evaluate the possibility of manufacturing bone screws with predefined dimensions. Scanning electronic microscopic images show that chemical processing and ethylene oxide treatment causes collagen fiber amalgamation on the bone surface. Processed screws hold higher

D. P. Haje; J. B. Volpon; C. A. Moro

2009-01-01

257

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

258

Fixation strength of a novel bioabsorbable expansion bolt for patellar tendon bone graft fixation: an experimental study in calf tibial bone.  

PubMed

This biomechanical study compares the initial fixation strength of a novel bioabsorbable two-shell expansion bolt (EB) with that of a well-established interference-screw technique in bone-patellar tendon-bone (BPTB) reconstruction in a calf model. Thirty tibia plateaus (age 5-6 months) were assigned to three groups: In groups I and II, trapezoidal bone plugs of BPTB grafts were fixed with bioabsorbable poly-L-lactide interference screws (8 x 23 mm) or titanium interference screws (8 x 25 mm) respectively. In group III, semicircular grafts were fixed using bioabsorbable poly-D, L-lactide expansion bolts (5.8/8.7 x 10 x 35 mm). The tensile axis was parallel to the bone tunnel, and the construction was loaded until failure applying a displacement rate of 1 mm per second. In group II the mean ultimate loads to failure (713 N+/-218 N) were found to be significantly higher than those of groups I (487 N+/-205 N) and III (510 N+/-133 N). Measurement of stiffness showed 45 N/mm+/-13.3 in group I, 58 N/mm+/-17.4 in group II and 46 N/mm+/-6.9 in group III, and did not demonstrate significant differences. We found a correlation between insertion torque and wedge insertion force and ultimate loads to failure in all groups (r=0.53 in group I, r =0.54 in group II, and r =0.57 in group III). Cross-section planes of bone tunnel increased by 51%, 30% and 31% respectively, following insertion of screws or expansion of bolts (p<0.05). We conclude that ACL graft fixation by means of the presented expansion bolt demonstrates a fixation strength similar to the established bioabsorbable screw fixation, and is a reasonable alternative fixation method, especially since some of the specific pitfalls of screw fixation can be avoided. PMID:15042285

Piltz, Stefan; Strunk, Patrick; Meyer, Ludger; Plitz, Wolfgang; Lob, Guenter

2004-09-01

259

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

260

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

261

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

PubMed Central

Background The biomechanical performance of the hooks and screws in spinal posterior instrumentation is not well-characterized. Screw-bone interface failure at the uppermost and lowermost vertebrae is not uncommon. Some have advocated for the use of supplement hooks to prevent screw loosening. However, studies describing methods for combined hook and screw systems that fully address the benefits of these systems are lacking. Thus, the choice of which implant to use in a given case is often based solely on a surgeon’s experience instead of on the biomechanical features and advantages of each device. Methods We conducted a biomechanical comparison of devices instrumented with different combinations of hooks and screws. Thirty-six fresh low thoracic porcine spines were assigned to three groups (12 per group) according to the configuration used for of fixation: (1) pedicle screw; (2) lamina hook and (3) combination of pedicle screw and lamina hook. Axial pullout tests backward on transverse plane in the direction normal to the rods were performed using a material testing machine and a specially designed grip with self-aligned function. Results The pullout force for the pedicle screws group was significantly greater than for the hooks and the combination (p??0.05). Conclusions Pedicle screws achieve the maximal pullout strength for spinal posterior instrumentation. PMID:24913189

2014-01-01

262

Mechanical evaluation of cross pins used for femoral fixation of hamstring grafts in ACL reconstructions.  

PubMed

The goal of this study was to test the mechanical strength of 4 different cross pins currently available for femoral fixation by loading each cross pin to failure as received and determine the effect of 1 million cycles of fatigue loading. Additionally, the strength of resorbable pins was tested after prolonged exposure to biologic conditions. Six implants each of the Arthrotek LactoSorb (Biomet, Warsaw, Indiana), Mitek RigidFix (DePuy Mitek Inc, Raynham, Massachusetts), Arthrotek Bone Mulch Screw (Biomet), cortical allograft, and control were tested for 3-point failure without prior loading and after cyclic loading between 50 to 200 N at 10 Hz for 1 million cycles. The bioabsorbable pins were placed in sterile water at 37°C and tested after 2, 4, and 6 months for 3-point failure strength. All implants tested without antecedent loading demonstrated adequate strength for initial fixation for hamstring grafts. During fatigue testing, RigidFix implants (n=6) failed at 18,893±8365 cycles (with a central deformation of 0.48±0.11 mm prior to fracture). All of the other implants tested endured 1 million cycles of loading (50-200 N) without fracture or 1.5 mm central deformation. Neither of the bioabsorbable pins demonstrated a significant change in yield strength after prolonged exposure to water. All implants tested demonstrated adequate strength for initial fixation of hamstring grafts. The metal and bone implants far exceed the strength required to sustain mechanical fixation until biological fixation occurs; both polymeric implants demonstrated that they maintained enough mechanical strength to achieve this goal. PMID:20954667

Bellisari, Gregory E; Kaeding, Christopher C; Litsky, Alan S

2010-10-01

263

Intraoperative CT navigation for glenoid component fixation in reverse shoulder arthroplasty  

PubMed Central

CT navigation has been shown to improve component positioning in total shoulder arthroplasty. The technique can be useful in achieving strong initial fixation of the metal backed glenoid in reverse shoulder arthroplasty. We report a 61 years male patient who underwent reverse shoulder arthroplasty for rotator cuff arthropathy. CT navigation was used intraoperatively to identify best possible glenoid bone and to maximize the depth of the fixation screws that anchor the metaglene portion of the metal backed glenoid component. Satisfactory positioning of screws and component was achieved without any perforation or iatrogenic fracture in the scapula. CT navigation can help in maximizing the purchase of the fixation screws that dictate the initial stability of the glenoid component in reverse shoulder arthroplasty. The technique can be extended to improve glenoid component position [version and tilt] with the availability of appropriate software. PMID:23531710

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

2013-01-01

264

Intraoperative CT navigation for glenoid component fixation in reverse shoulder arthroplasty.  

PubMed

CT navigation has been shown to improve component positioning in total shoulder arthroplasty. The technique can be useful in achieving strong initial fixation of the metal backed glenoid in reverse shoulder arthroplasty. We report a 61 years male patient who underwent reverse shoulder arthroplasty for rotator cuff arthropathy. CT navigation was used intraoperatively to identify best possible glenoid bone and to maximize the depth of the fixation screws that anchor the metaglene portion of the metal backed glenoid component. Satisfactory positioning of screws and component was achieved without any perforation or iatrogenic fracture in the scapula. CT navigation can help in maximizing the purchase of the fixation screws that dictate the initial stability of the glenoid component in reverse shoulder arthroplasty. The technique can be extended to improve glenoid component position [version and tilt] with the availability of appropriate software. PMID:23531710

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

2013-01-01

265

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

266

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

PubMed

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

Choi, Sungwook; Kang, Hyunseong; Bang, Hyeongsig

2014-08-01

267

A new technique for retaining double crowns on implants via custom-positioned vertical screws.  

PubMed

This report describes the use of custom-positioned vertical screws (CVS) to attach primary telescopic crowns to implant abutments. In a private practice setting, 37 patients with 40 double crown-retained implant overdentures (IODs) with a clearance fit (Marburg double crowns) were followed. All primary crowns on the 120 implant abutments were retained using CVS. After a mean followup period of 3.55 ± 1.37 years (range: 1.5 to 6.3 years), one abutment screwloosening incident was reported (incidence: 0.08%). No loosening of any of the screw-retained primary crowns occurred. CVS may represent a viable fixation concept for IODs. PMID:25390875

Frisch, Eberhard; Ziebolz, Dirk; Ratka-Krüger, Petra; Rinke, Sven

2014-01-01

268

Chemical fixation of arsenic in contaminated soils  

Microsoft Academic Search

Arsenic-contaminated soils have been successfully treated using fixation methods whereby chemicals are added to prevent As mobilization. However, the chemistry of the fixation process used in the field is poorly understood. We have examined one process which succeeded in immobilizing 0. I to 0.2 weight % As in soil at a 69 a old dump site through the addition of

Remy J.-C. Hennet; S. L. Brantley

1996-01-01

269

Iso-C3D navigation assisted pedicle screw placement in deformities of the cervical and thoracic spine  

PubMed Central

Background: Pedicle screw instrumentation of the deformed cervical and thoracic spine is challenging to even the most experienced surgeon and associated with increased incidence of screw misplacement. Iso-C3D based navigation has been reported to improve the accuracy of pedicle screw placement, however, there are very few studies assessing its efficacy in the presence of deformity. We conducted a study to evaluate the accuracy of Iso-C3D based navigation in pedicle screw fixation in the deformed cervical and thoracic spine. Materials and Methods: We inserted 98 cervical pedicle screws (18 patients) and 242 thoracic pedicle screws (17 patients) using Iso-C3D based navigation for deformities of spine due to scoliosis, ankylosing spondylitis, post traumatic and degenerative disorders. Two independent observers determined and graded the accuracy of screw placement from postoperative computed tomography (CT) scans. Results: Postoperative CT scans of the cervical spine showed 90.8% perfectly placed screws with 7 (7%) grade I pedicle breaches, 2 (2%) grade II pedicle breaches and one anterior cortex penetration (< 2mm). Five lateral pedicle breaches violated the vertebral artery foramen and three medial pedicle breaches penetrated the spinal canal; however, no patient had any neurovascular complications. In the thoracic spine there were 92.2% perfectly placed screws with only six (2%) grade II pedicle breaches, eight (3%) grade I pedicle breaches and five screws (2%) penetrating the anterior or lateral cortex. No neuro-vascular complications were encountered. Conclusion: Iso-C3D based navigation improves the accuracy of pedicle screw placement in deformities of the cervical and thoracic spine. The low incidence of pedicle breach implies increased safety for the patient. PMID:20419003

Rajan, Vinod V; Kamath, Vijay; Shetty, Ajoy Prasad; Rajasekaran, S

2010-01-01

270

Influences of implant condyle geometry on bone and screw strains in a temporomandibular implant.  

PubMed

A 3D finite element model of an in vitro implanted mandible was analysed. The load point was placed on the condyle in three positions (inside the mouth, centred and outside) to simulate different contact points between the mandible condyle and the temporal bone. The strain fields in the condyle were assessed and detailed around the surgical screws. The temporomandibular implant studied here was modelled on a commercial device that uses four screws to fix it in vivo in a very similar position. The boundary conditions of the numerical model simulated a load on the incisors with a 15 mm mouth aperture. The same contact loads were applied to the two condyles. Numerical results were successfully obtained for the three different contact points: the inside contact produced lower strains on the condyle. The first screw created a critical strain distribution in the bone, just under the screw. The study shows that centred and inside contact induces lower strain distributions. This suggests that spherical condyle geometry should be applied in order to reduce the strains in fixation. As the top screw was observed to play the most critical role, the third screw is in fact unnecessary, since the lower strain distribution suggests that it will be loosened. PMID:23726645

Mesnard, M; Ramos, A; Simões, J A

2014-04-01

271

A postmortem examination of poly-L lactic acid interference screws 4 months after implantation during anterior cruciate ligament reconstruction  

Microsoft Academic Search

This is a report of a postmortem examination of an implanted bioabsorbable interference screw used for patellar tendon graft fixation during anterior cruciate ligament reconstruction. Examination was conducted 4 months after implantation. Examination included radiographic, arthroscopic, and magnetic resonance evaluations as well as histologic and mechanical pullout testing. Examination showed no evidence of tunnel widening, lytic bone changes, or inflammatory

David A McGuire; F. Alan Barber; Sara Milchgrub; Jeffrey C Wolchok

2001-01-01

272

A retrospective comparison of four plate constructs for first metatarsophalangeal joint fusion: static plate, static plate with lag screw, locked plate, and locked plate with lag screw.  

PubMed

The primary treatment for progressive first metatarsophalangeal (MTP) joint arthritis is arthrodesis. Multiple fixation types have been used to accomplish fusion including plating. There have been no published articles reporting the outcomes of these 4 plate and/or screw constructs. We present our experience with 138 first MTP joint fusions using these constructs. A retrospective comparison and radiographic chart review of 132 patients (138 feet) was performed to compare different constructs in regards to successful union and time to fusion. All operations were performed by 4 fellowship-trained foot and ankle surgeons. The radiographs were independently read by 2 authors not involved in the index procedures. Radiographic fusion was determined by bridging cortices across the joint line. The mean time to union (in days) and rate of fusion were static plate: 59, 95%, static plate with lag screw: 56, 86%, locked plate: 66, 92%, and locked plate with lag screw: 53, 96%. There was not a statistically significant difference between the groups in regards to patient age, time to weight bearing, time to fusion, or rate of fusion. We report on the results of fusion comparing 4 different plate and/or screw constructs for first MTP joint fusion. The data reveal no significant difference in time to fusion or rate of fusion between static and locked plates, with or without a lag screw. PMID:22459423

Hyer, Christopher F; Scott, Ryan T; Swiatek, Michael

2012-01-01

273

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

PubMed

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

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

2013-10-01

274

Biomechanical testing of implant free wedge shaped bone block fixation for bone patellar tendon bone anterior cruciate ligament reconstruction in a bovine model  

Microsoft Academic Search

BACKGROUND: The use of an interference fit wedged bone plug to provide fixation in the tibial tunnel when using bone-patellar tendon-bone autograft for anterior cruciate ligament reconstruction offers many theoretic advantages including the potential to offer a more economical and biological alternative to screw fixation. This technique has not been subjected to biomechanical testing. We hypothesised that a wedged bone

Charles A Willis-Owen; Trevor C Hearn; Gregory C Keene; John J Costi

2010-01-01

275

Ten-Year Magnetic Resonance Imaging Follow-Up of Bioabsorbable Poly-L-Lactic Acid Interference Screws After Anterior Cruciate Ligament Reconstruction  

Microsoft Academic Search

In a previous study bioabsorbable screws composed of poly-L-lactic acid were used for graft fixation and examined prospectively with serial magnetic resonance imaging (MRI) scans 8, 16, and 24 months after anterior cruciate ligament reconstruction. Autogenous patellar tendon graft was used in all 10 patients. Although the manufacturer’s estimated time to absorption was 2 years, only 1 of 20 screws

William H. Warden; Dianna Chooljian; Douglas W. Jackson

2008-01-01

276

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

277

Intraarticular migration of a broken biodegradable interference screw after anterior cruciate ligament reconstruction  

Microsoft Academic Search

Poly-l-lactic acid biodegradable screws have been used effectively for graft fixation in anterior cruciate ligament (ACL) reconstruction. The overall complication rate associated with the use of this implant is low, although some authors reported complications, such as osteolysis and aseptic effusion of the knee joint. We report a case of a 29-year-old female patient with a failure of a biodegradable

M. H. Baums; B. A. Zelle; W. Schultz; T. Ernstberger; H.-M. Klinger

2006-01-01

278

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

279

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

280

Plate fixation of premaxillomaxillary suture and compensatory midfacial growth changes in the rabbit.  

PubMed

It has been suggested that rigid fixation of the developing craniofacial skeleton may lead to altered craniofacial growth. However, recent experimental studies have shown that microplate fixation of slow-growing calvarial sutures resulted in regional growth disturbances but had little effect on overall craniofacial growth. The present study was designed to assess the effects of microplate fixation of the more rapidly growing facial sutures on compensatory midfacial growth in the rabbit. Twenty-two 1.5-week-old rabbits were randomly divided into 2 groups: sham controls (n = 11) and animals with bilateral premaxillomaxillary suture fixation (n = 11). Fixation was accomplished using an intraoral approach, a 6-mm straight Luhr microplate, and two 2-mm long self-tapping screws across each suture. Serial lateral head radiographs were collected at 1.5, 3.5, 6, 12, and 18 weeks of age. Results revealed that by 3.5 weeks, animals with rigid fixation showed significantly shortened premaxillary lengths (p < 0.05), class III occlusal relationships, decreased midfacial heights, and abnormal palatocranial base angles compared with sham control animals. By 12 weeks of age, "catch-up" growth was evident in most dimensions in animals with fixation compared with shams. Gross examination of the cleaned and dried skulls revealed bony bridging across the premaxillomaxillary suture and osseous fracture lines extending superiorly from the site of screw fixation. Results demonstrated that rigid fixation of a rapidly growing facial suture did not impair long-term midfacial growth in the rabbit model and suggest that compensatory changes may have occurred at fracture lines from the self-tapping screws in these animals. PMID:1298421

Mooney, M P; Losken, H W; Siegel, M I; Tsachakaloff, A; Losken, A; Janosky, J

1992-12-01

281

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

282

Compaction Drilling Does Not Increase the Initial Fixation Strength of the Hamstring Tendon Graft in Anterior Cruciate Ligament Reconstruction in a Cadaver Model  

Microsoft Academic Search

Background: Compaction of the bone tunnel walls has been proposed to increase the fixation strength of soft tissue grafts fixed with an interference screw in anterior cruciate ligament reconstructions.Hypothesis: Compaction drilling does not increase the initial fixation strength of the hamstring tendon graft in comparison with conventional extraction drilling.Study Design: Randomized experimental study.Methods: Initial fixation strength of quadrupled hamstring tendon

Janne T. Nurmi; Pekka Kannus; Harri Sievänen; Markku Järvinen; Teppo L. N. Järvinen

2003-01-01

283

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

284

CT-based 3-D visualisation of secure bone corridors and optimal trajectories for sacroiliac screws.  

PubMed

Sacroiliac screw (SI) fixation represents the only minimally invasive method to stabilise unstable injuries of the posterior pelvic ring. However, it is technically demanding. The narrow sacral proportions and a high inter-individual shape variability places adjacent neurovascular structures at potential risk. In this study a CT-based virtual analysis of the iliosacral anatomy in the human pelvis was performed to visualise and analyse 3-D bone corridors for the safe placement of SI-screws in the first sacral segment. Computer-aided calculation of 3-D transverse and general SI-corridors as a sum of all inner-bony 7.3-mm screw positions was done with custom-made software algorithms based on CT-scans of intact human pelvises. Radiomorphometric analysis of 11 CT-DICOM datasets using the software Amira 4.2. Optimal screw tracks allowing the greatest safety distance to the cortex were computed. Corridor geometry and optimal tracks were visualised; measurement data were calculated. A transverse corridor existed in 10 pelvises. In one dysmorphic pelvis, the pedicular height at the level of the 1st neural foramina came below the critical distance of 7.3mm defined by the outer screw diameter. The mean corridor volume was 45.2 cm3, with a length of 14.9cm. The oval cross-section measured 2.8 cm2. The diameter of the optimal screw pathway with the greatest safety distance was 14.2mm. A double cone-shaped general corridor for screw penetration up to the centre of the S1-body was calculated bilaterally for every pelvis. The mean volume was 120.6 cm3 for the left side and 115.8 cm3 for the right side. The iliac entry area measured 49.1 versus 46.0 cm2. Optimal screw tracks were calculated in terms of projected inlet and outlet angles. Multiple optimal screw positions existed for each pelvis. The described method allows an automated 3-D analysis with regard to secure SI-screw corridors even with a high number of CT-datasets. Corridor visualisation and calculation of optimal screw tracks trains the visual thinking of the surgeon and can improve pre-operative planning. Prospectively, the introduced method can be implemented in computer-assisted surgery applications involving pelvic trauma. PMID:23246561

Mendel, Thomas; Radetzki, Florian; Wohlrab, David; Stock, Karsten; Hofmann, Gunther Olaf; Noser, Hansrudi

2013-07-01

285

Designs and Techniques That Improve the Pullout Strength of Pedicle Screws in Osteoporotic Vertebrae: Current Status  

PubMed Central

Osteoporosis is a medical condition affecting men and women of different age groups and populations. The compromised bone quality caused by this disease represents an important challenge when a surgical procedure (e.g., spinal fusion) is needed after failure of conservative treatments. Different pedicle screw designs and instrumentation techniques have been explored to enhance spinal device fixation in bone of compromised quality. These include alterations of screw thread design, optimization of pilot hole size for non-self-tapping screws, modification of the implant's trajectory, and bone cement augmentation. While the true benefits and limitations of any procedure may not be realized until they are observed in a clinical setting, axial pullout tests, due in large part to their reproducibility and ease of execution, are commonly used to estimate the device's effectiveness by quantifying the change in force required to remove the screw from the body. The objective of this investigation is to provide an overview of the different pedicle screw designs and the associated surgical techniques either currently utilized or proposed to improve pullout strength in osteoporotic patients. Mechanical comparisons as well as potential advantages and disadvantages of each consideration are provided herein. PMID:24724097

Shea, Thomas M.; Laun, Jake; Gonzalez-Blohm, Sabrina A.; Doulgeris, James J.; Lee, William E.; Vrionis, Frank D.

2014-01-01

286

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

287

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

288

Assessment of a percutaneous iliosacral screw insertion simulator  

E-print Network

BACKGROUND: Navigational simulator use for specialized training purposes is rather uncommon in orthopaedic and trauma surgery. However, it reveals providing a valuable tool to train orthopaedic surgeons and help them to plan complex surgical procedures. PURPOSE: This work's objective was to assess educational efficiency of a path simulator under fluoroscopic guidance applied to sacroiliac joint percutaneous screw fixation. MATERIALS AND METHODS: We evaluated 23 surgeons' accuracy inserting a guide-wire in a human cadaver experiment, following a pre-established procedure. These medical trainees were defined in three prospective respects: novice or skilled; with or without theoretical knowledge; with or without surgical procedure familiarity. Analysed criteria for each tested surgeon included the number of intraoperative X-rays taken in order to achieve the surgical procedure as well as an iatrogenic index reflecting the surgeon's ability to detect any hazardous trajectory at the time of performing said procedu...

Tonetti, J; Girard, P; Dubois, M; Merloz, P; Troccaz, Jocelyne; 10.1016/j.otsr.2009.07.005

2009-01-01

289

Fixation: A Bibliography.  

ERIC Educational Resources Information Center

Fixation and regression were considered complementary by Freud. You tend to regress to a point of fixation. They are both opposed to progression. In the general area, Anna Freud has written (The Ego and the Mechanisms of Defence. London: Hogarth and the Psycho-Analytic Institute, 1937), Sears has evaluated (Survey of Objective Studies of…

Pedrini, D. T.; Pedrini, Bonnie C.

290

A novel radiographic targeting guide for percutaneous placement of transfacet screws in the cervical spine with limited fluoroscopy: A cadaveric feasibility study  

PubMed Central

Background We describe a technique for percutaneous transfacet screw placement in the cervical spine without the need for lateral-view fluoroscopy. Methods Previously established articular pillar morphometry was used to define the ideal trajectory for transfacet screw placement in the subaxial cervical spine. A unique targeting guide was developed to allow placement of Kirschner wires across the facet joint at 90° without the guidance of lateral-view fluoroscopy. Kirschner wires and cannulated screws were placed percutaneously in 7 cadaveric specimens. Placement of instrumentation was performed entirely under modified anteroposterior-view fluoroscopy. All specimens were assessed for acceptable screw placement by 2 fellowship-trained orthopaedic spine surgeons using computed tomography. Open dissection was used to confirm radiographic interpretation. Acceptable placement was defined as a screw crossing the facet joint, achieving purchase in the inferior and superior articular processes, and not violating critical structures. Malposition was defined as a violation of the transverse foramen, spinal canal, or nerve root or inadequate fixation. Results A total of 48 screws were placed. Placement of 45 screws was acceptable. The 3 instances of screw malposition included a facet fracture, a facet distraction, and a C6-7 screw contacting the C7 nerve root in a specimen with a small C7 superior articular process. Conclusions Our data show that with the appropriate radiographic technique and a targeting guide, percutaneous transfacet screws can be safely placed at C3-7 without the need for lateral-view fluoroscopy during the targeting phase. Because of the variable morphometry of the C7 lateral mass, however, care must be taken when placing a transfacet screw at C6-7. Clinical Relevance This study describes a technique that has the potential to provide a less invasive strategy for posterior instrumentation of the cervical spine. Further investigation is needed before this technique can be applied clinically.

Jackson, David M.; Karp, Jacqueline E.; O'Brien, Joseph R.; Anderson, D. Greg; Gelb, Daniel E.; Ludwig, Steven C.

2012-01-01

291

Analysis of plastic deformation in cortical bone after insertion of coated and non-coated self-tapping orthopaedic screws.  

PubMed

Insertion of internal fracture fixation devices, such as screws, mechanically weakens the bone. Diamond-like carbon has outstanding tribology properties which may decrease the amount of damage in tissue. The purpose of this study was to investigate methods for quantification of cortical bone damage after orthopaedic bone screw insertion and to evaluate the effect of surface modification on tissue damage. In total, 48 stainless steel screws were inserted into cadaver bones. Half of the screws were coated with a smooth amorphous diamond coating. Geometrical data of the bones was determined by peripheral quantitative computed tomography. Thin sections of the bone samples were prepared after screw insertion, and histomorphometric evaluation of damage was performed on images obtained using light microscopy. Micro-computed tomography and scanning electron microscopy were also used to examine tissue damage. A positive correlation was found between tissue damage and the geometric properties of the bone. The age of the cadaver significantly affected the bone mineral density, as well as the damage perimeter and diameter of the screw hole. However, the expected positive effect of surface modification was probably obscured by large variations in the results and, thus, statistically significant differences were not found in this study. This can be explained by natural variability in bone tissue, which also made automated image analysis difficult. PMID:21870370

Koistinen, A P; Korhonen, H; Kiviranta, I; Kröger, H; Lappalainen, R

2011-07-01

292

Bioabsorbable interference screws for bone-patellar tendon-bone anterior cruciate ligament reconstruction: clinical and computerized tomography results of four different models. A prospective study  

Microsoft Academic Search

We investigated the effectiveness of four bioabsorbable interference screws for bone block fixation in ACL reconstruction, and assessed their complete absorption and graft integration. We performed a prospective clinical evaluation with the IKDC form and computed tomography (CT) scans 3, 6, 9, 12, 18 and 24 months after arthroscopic ACL reconstruction with the bonepatellar tendon-bone (BPTB) technique. A total of

M. Denti; P. Randelli; D. Lo Vetere; M. Moioli; M. Tagliabue

2004-01-01

293

Causes and managements of postoperative complications after degenerative scoliosis treatments with internal fixation  

PubMed Central

Objective: To investigate the causes and managements of early postoperative complications of degenerative scoliosis (DS) treated with internal pedicle screw fixation. Methods: From Jan 2000 to Apr 2013, 325 DS patients treated with internal pedicle screw fixation in our hospital were retrospectively involved. The categories, causes, managements and outcomes of early postoperative complications were statistically analyzed. Results: Early postoperative complications occurred in 10.76% of the patients including 16 cases of lower limb numb or pain, 6 cases of decreased lower limb sensitivity and motor functions, which accounted for 62.86% of all complications, followed by incision infections (4/35, 11.43%) and rare cases of cerebrospinal fluid leakage, cardiac and renal inadequacy, urinary system and pulmonary infections. The incidence of overall complications (19.79%, p = 0.001) and nerve injuries (11.46%, p = 0.000) were significantly higher in long-segment than in short-segment fixations. Improper screw implanting, over correction of scoliosis and insufficient blood supply of the spinal cord during operation were risk factors for early postoperative complications and most of them were cured by anti-infection medication, incision dressing change, nerve nourishment, adjusting the screws and anti-osteoporosis treatments within 6 months after surgery. Only three cases with severe nerve injury did not improve until the 6 months postoperative follow-up. Conclusions: Most of the postoperative complications in our DS patients disappeared within 6 months after surgery and more than half of complications were nerve injuries.

Yang, Yong-Hong; Zheng, Jie; Lou, Shu-Liang

2014-01-01

294

To evaluate the efficacy of biodegradable plating system for fixation of maxillofacial fractures: A prospective study  

PubMed Central

Aims: The present study was undertaken to evaluate the efficacy of biodegradable plating system for fixation of maxillofacial fractures and to study the morbidity associated with the use of biodegradable plates and screws. Materials and Methods: This prospective study consisted of 10 patients with maxillofacial fractures requiring open reduction and internal fixation. Fractures with infection, comminuted and pathological fractures were excluded. All were plated with biodegradable system (Inion CPS) using standard plating principles and observed for a total period of 24 weeks. Characteristics of the fractures, ease of use of bioresorbable plate/screw system and post operative complications were assessed. Results: Of total 10 patients, eight patients were of midface fracture and two pediatric patients with mandibular fracture, with nine male and one female. The mean age was 32.8 years. Out of 20 plates and 68 screws applied to the 10 fractures sites; there were three incidences of screw breakage with no other intraoperative difficulties. Paresthesia of the infraorbital nerve was present in two patients, and recovered completely in four weeks after surgery. Fracture reduction was considered to be satisfactory in all cases. One patient developed postsurgical infection and was managed with oral antibiotics and analgesics. Conclusions: Favorable healing can be observed through the use of biodegradable plates and screws to stabilize selected midface fractures in patients of all ages, as well as mandible fractures in early childhood, however further studies with more sample size are required. PMID:24665170

Bali, Rishi K.; Sharma, Parveen; Jindal, Shalu; Gaba, Shivani

2013-01-01

295

Assessment of the RIVET fixation system for cranioplasty using the pull-out technique.  

PubMed

Cranioplasty using custom-made hydroxyapatite (HAP) ceramic implants is a common procedure to repair skull defects. However, commercially available titanium screws are only minimally stabilized due to characteristic brittleness. We developed the RIVET technique which involves fixing a bioabsorbable plate atop a HAP block using bioabsorbable screws extending beyond both layers, and evaluated fixation strength using the pull-out test and microtomography. Three experimental conditions were compared: a non-RIVET group, RIVET group, and dry skull control group. Pull-out strength significantly differed across groups (non-RIVET group, 1.33 ± 1.21 kgf; RIVET group, 4.46 ± 0.84 kgf; and control group, 6.99 ± 1.14 kgf, P < 0.01). Microtomography of the dry skull control group revealed thread grooves fitted to the screws. The non-RIVET and RIVET groups presented fewer thread grooves than the control group, and the screws did not fit perfectly to the HAP block. However, fixation in the RIVET group was more stable, as the rivet was firmly lodged into the implant. In conclusion, by melting and creating the rivet, pull-out strength can be increased and rigid stabilization of HAP can be obtained. This technique uses commercially available absorbable plate and screws, and thus can be used widely in clinical applications involving HAP blocks with different porosities and thicknesses. PMID:25555895

Sakamoto, Yoshiaki; Minabe, Toshiharu; Kato, Tatsuya; Kishi, Kazuo

2015-03-01

296

Effect of occipitocervical fusion with screw-rod system for upper cervical spine tumor  

PubMed Central

Background Craniospinal junction tumors are rare but severe lesions. Surgical stabilization has been established to be an ideal treatment for upper cervical tumor pathology. The purpose of this study was to evaluate the effect of a screw-rod system for occipitocervical fusion. Methods A total of 24 cases with C1 and C2 cervical tumor underwent occipitocervical fusion with Vertex screw-rod internal fixation from January 2005 to December 2012. Preoperative X-ray and MRI examinations were performed on all patients before the operation, after the operation, and during last follow-up. The JOA score was used to assess neurological function pre and postoperatively. Results All the patients were followed up for 6 to 42 months with an average of 24 months. The result of X-ray showed that bony fusion was successful in 18 patients at 3 months and 6 patients at 6 months of follow-ups. There was no deterioration of spinal cord injury. The JOA Scores of neurological function increased significantly. Conclusion The screw-rod system offers strong fixation and good fusion for occipitocervical fusion. It is an effective and reliable method for reconstruction of upper cervical spine tumor. PMID:24884456

2014-01-01

297

Experimental results of single screw mechanical tests: a follow-up to SAND2005-6036.  

SciTech Connect

The work reported here was conducted to address issues raised regarding mechanical testing of attachment screws described in SAND2005-6036, as well as to increase the understanding of screw behavior through additional testing. Efforts were made to evaluate fixture modifications and address issues of interest, including: fabrication of 45{sup o} test fixtures, measurement of the frictional load from the angled fixture guide, employment of electromechanical displacement transducers, development of a single-shear test, and study the affect of thread start orientation on single-shear behavior. A286 and 302HQ, No.10-32 socket-head cap screws were tested having orientations with respect to the primary loading axis of 0{sup 0}, 45{sup o}, 60{sup o}, 75{sup o} and 90{sup o} at stroke speeds 0,001 and 10 in/sec. The frictional load resulting from the angled screw fixture guide was insignificant. Load-displacement curves of A286 screws did not show a minimum value in displacement to failure (DTF) for 60{sup o} shear tests. Tests of 302HQ screws did not produce a consistent trend in DTF with load angle. The effect of displacement rate on DTF became larger as shear angle increased for both A286 and 302HQ screws.

Lee, Sandwook; Lee, Kenneth L.; Korellis, John S.; McFadden, Sam X.

2006-08-01

298

The search for the ideal fixation of palatal fractures: innovative experience with a mini-locking plate.  

PubMed

Fractures of the palate have defied conventional management, such that malrotation and disinclination of the palatal shelves occur in a significant number of patients after repair. The fractured palatal shelves of eight patients were first prealigned. To do so, one or more 205-mm ratchet clamps and two intermaxillary fixation (IMF) posts were used. Rigid fixation was then achieved by applying a 2.0-mm mini-locking titanium plate (across the palatal vault) and by applying an adaptation miniplate across the fracture line as it exited the anterior surface of the maxilla. Screws were passed directly through the mucoperiosteum, to engage the palatal shelves and to lock the locking plate into position. Lacerations in the mucoperiosteum were neither used to aid fixation nor used as portals for dissection; incisions and mucoperiosteal flaps in the palatal vault were avoided. Adjuncts, such as intraoral splints, have not been used in cases to date, and early mobilization was allowed. Reconstitution of the craniomaxillofacial buttresses was added in patients with more extensive maxillary injury. The palatal appliance and screws remained rigidly in position in the roof of the mouth, much like an external fixator, until their removal 8 to 12 weeks after the repair. No patient suffered erosion of the mucoperiosteum or other major morbidity, other than a transient fistula of the soft palate. The palatoalveolar segments remained in proper realignment and inclination, and pretraumatic occlusal patterns and the width and depth of the lower face appear to have been restored with one exception. The latter suffered a subtle posterolateral open bite that was corrected orthodontically. Prealignment of fractured palatal shelves with one or more large ratchet clamps and two IMF posts provides several points of forced reduction of the palatal shelves, along the dental arch. In addition, stabilization with mini-locking plate(s) in the palatal vault and an adaptation plate across the fracture line, as it exits the maxilla, appear to have merit, based on this preliminary report (n?=?8). Outcomes seen on computed tomography and clinical examination during this 3-year experience have been favorable. PMID:22110785

Pollock, Richard A

2008-11-01

299

Negative pressure wound therapy and external fixation device: a simple way to seal the dressing.  

PubMed

Negative pressure therapy is widely applied to treat lower limb trauma. However, sealing a negative pressure dressing in the presence of an external fixation device may be difficult and time consuming. Therefore, screws, pins, wires, etc, may preclude the vacuum, preventing the plastic drape to perfectly adhere to the foam. To maintain the vacuum, we tried to prevent air leaking around the screws putting bone wax at the junction between the pins and the plastic drape. This solution, in our hands, avoids air leakage and helps maintain vacuum in a fast and inexpensive way. PMID:24296597

Bulla, Antonio; Farace, Francesco; Uzel, André-Pierre; Casoli, Vincent

2014-07-01

300

Augmentation of unstable pertrochanteric fractures in the osteoporotic elderly patient: operative technique for 1 or 2 head screw systems.  

PubMed

The incidence of proximal femoral fractures has substantially risen in the elderly. This rise has been attributed to an increase in their life span and the underlying poor bone stock and osteoporosis. One of the main reasons for revision surgery, reported to be as high as 19%, is the cut-out of the fixation device at the apex of the femoral head. Augmentation, facilitated by injecting cement (PMMA) around the apex of the proximal screw of the fixation device is considered a useful method with regards to the increased purchase between the bone and implant interface. The aim of this study is the description of the cement Augmentation operative technique for unstable osteoporotic pertrochanteric fractures with 1-2 femoral head screw devices. PMID:25409720

Dall'Oca, C; Maluta, T; Lavini, F; Micheloni, G M; Bondi, M; Magnan, B

2014-01-01

301

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

302

Arthroscopic treatment of slipped capital femoral epiphysis screw impingement and concomitant hip pathology.  

PubMed

Impingement caused by screws used for stabilization of slipped capital femoral epiphysis can be treated arthroscopically. Although troublesome screws have traditionally been removed by open techniques, arthroscopic removal can successfully be achieved. In addition to affording the patient the benefits of minimally invasive surgery, surgeons also have the ability to arthroscopically address any concomitant hip pathology responsible for pain, including femoroacetabular impingement and labral tears. PMID:25264513

Howse, Elizabeth A; Wooster, Benjamin M; Mannava, Sandeep; Perry, Brad; Stubbs, Allston J

2014-08-01

303

Arthroscopic Treatment of Slipped Capital Femoral Epiphysis Screw Impingement and Concomitant Hip Pathology  

PubMed Central

Impingement caused by screws used for stabilization of slipped capital femoral epiphysis can be treated arthroscopically. Although troublesome screws have traditionally been removed by open techniques, arthroscopic removal can successfully be achieved. In addition to affording the patient the benefits of minimally invasive surgery, surgeons also have the ability to arthroscopically address any concomitant hip pathology responsible for pain, including femoroacetabular impingement and labral tears. PMID:25264513

Howse, Elizabeth A.; Wooster, Benjamin M.; Mannava, Sandeep; Perry, Brad; Stubbs, Allston J.

2014-01-01

304

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

305

Magnetic Resonance Imaging of Bioabsorbable Polylactic Acid Interference Screws During the First 2 Years After Anterior Cruciate Ligament Reconstruction  

Microsoft Academic Search

Summary: Bioabsorbable screws composed of poly(L-lactic acid) (PLA) were used for graft fixation and studied prospectively with serial magnetic resonance imaging (MRI) scans at 8, 16, and 24 months after autogenous patellar tendon anterior cruciate ligament (ACL) reconstruction in 10 patients. Conventional spin echo, proton density , and T2-weighted double echo sequences were obtained, as well as T2-weighted fat-saturated fast

William H. Warden; Robert Friedman; Louis M. Teresi; Douglas W. Jackson

1999-01-01

306

A Biomechanical Comparison of Initial Fixation Strength of 3 Different Methods of Anterior Cruciate Ligament Soft Tissue Graft Tibial FixationResistance to Monotonic and Cyclic Loading  

Microsoft Academic Search

Background: Tibial fixation of soft tissue grafts continues to be problematic in the early postoperative period after anterior cruciate ligament reconstruction.Hypothesis: No differences exist for resistance to slippage of soft tissue grafts fixed with CentraLoc, Intrafix, or 35-mm bioabsorbable interference screws.Study Design: Controlled laboratory study.Methods: Bovine tibia and hoof extensor tendons were divided into 3 matched groups with 12 tibia

Reed L. Bartz; Kory Mossoni; Jeffrey Tyber; John Tokish; Kenneth Gall; Patrick N. Siparsky

2007-01-01

307

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

308

Navigation of vertebro-pelvic fixations based on CT-fluoro matching  

PubMed Central

Different navigation procedures (based on 2D-, 3D-fluoroscopy or CT modalities) with their respective limitations are established in orthopedic surgery. The hypothesis is that intraoperative matching of different modalities (fluoro and CT) increases the precision of navigated screw placement and reduces the fluoroscopy time. Vertical unstable pelvic ring fractures of 12 patients were treated with vertebro-pelvic fixations (6 in the standard technique and 6 using the fluoro-CT navigation). An optimal osseous corridor could be determined by the navigation procedure increasing the overall precision of screw placement (no misplacement in the second group as compared to one malplaced pedicle screw in the standard group). The achieved screw lengths were [(mean ± SE) 78 ± 5 vs. 53 ± 4 mm, p < 0.001). Less invasive open approaches and a reduction of fluoroscopy time (time per screw in seconds: 121 vs. 62 s) were observed. CT-fluoro-matched navigation improves the intraoperative visualization of osseous structures and increases the precision of screw placement with less radiation exposure. PMID:20556440

Gras, Florian; Klos, Kajetan; Wilharm, Arne; Mückley, Thomas; Hofmann, Gunther O.

2010-01-01

309

Arthroscopic 4-Point Suture Fixation of Anterior Cruciate Ligament Tibial Avulsion Fractures  

PubMed Central

Tibial eminence avulsion fractures are rare injuries occurring mainly in adolescents and young adults. When necessary, regardless of patient age, anatomic reduction and stable internal fixation are mandatory for fracture healing and accurate restoration of normal knee biomechanics. Various arthroscopically assisted fixation methods with sutures, anchors, wires, or screws have been described but can be technically demanding, thus elongating operative times. The purpose of this article is to present a technical variation of arthroscopic suture fixation of anterior cruciate ligament avulsion fractures. Using thoracic drain needles over 2.4-mm anterior cruciate ligament tibial guidewires, we recommend the safe and easy creation of four 2.9-mm tibial tunnels at different angles and at specific points. This technique uses thoracic drain needles as suture passage cannulas and offers 4-point fixation stability, avoiding potential complications of bony bridge fracture and tunnel connection. PMID:25685674

Boutsiadis, Achilleas; Karataglis, Dimitrios; Agathangelidis, Filon; Ditsios, Konstantinos; Papadopoulos, Pericles

2014-01-01

310

The treatment of fractures with a dynamic axial fixator.  

PubMed

The results obtained with a lightweight dynamic axial fixator in the treatment of fractures are reported. The apparatus comprises a single bar with articulating ends which clamp self-tapping screws and can be locked at an angle appropriate for axial alignment. A telescopic facility allows ready conversion from rigid to dynamic fixation once periosteal callus formation has commenced. Reduction and controlled distraction or compression are achieved by means of a detachable compressor unit. We treated 288 patients with fresh fractures and 50 with ununited fractures. The success rate for fresh fractures was 94%, with average healing times ranging from 3.4 to 6.5 months. In ununited fractures also, the success rate was 94% with average healing times ranging from 4.7 to 6.5 months. Complications were minimal. The device is versatile and can be applied in an average of 15 minutes. It permits ambulatory fracture care without sacrificing a sound anatomical result. PMID:6746689

De Bastiani, G; Aldegheri, R; Renzi Brivio, L

1984-08-01

311

Biomechanical comparison of mono-segment transpedicular fixation with short-segment fixation for treatment of thoracolumbar fractures: A finite element analysis.  

PubMed

Mono-segment transpedicular fixation is a method for the treatment of certain types of thoracolumbar spinal fracture. Finite element models were constructed to evaluate the biomechanics of mono-segment transpedicular fixation of thoracolumbar fracture. Spinal motion (T10-L2) was scanned and used to establish the models. The superior half of the cortical bone of T12 was removed and the superior half of the cancellous bone of the T12 body was assigned the material properties of injured bone to mimic vertebral fracture. Transpedicular fixation of T11 and T12 was performed to produce a mono-segment fixation model; T11 and L1 were fixed to produce a short-segment fixation model. Motion differences between functional units and von Mises stress on the spine and implants were measured under axial compression, anterior bending, extensional bending, lateral bending and axial rotation. We found no significant difference between mono- and short-segment fixations in the motion of any functional unit. Stress on the T10/T11 nucleus pulposus and T10/T11 and L1/L2 annulus fibrosus increased significantly by about 75% on anterior bending, extensional bending and lateral bending. In the fracture model, stress was increased by 24% at the inferior endplate of T10 and by 43% at the superior endplate of L2. All increased stresses were reduced after fixation and lower stress was observed with mono-segment fixation. In summary, the biomechanics of mono-segment pedicle screw instrumentation was similar to that of conventional short-segment fixation. As a minimally invasive treatment, mono-segment fixation would be appropriate for the treatment of selected thoracolumbar spinal fractures. PMID:25267283

Xu, Guijun; Fu, Xin; Du, Changling; Ma, Jianxiong; Li, Zhijun; Tian, Peng; Zhang, Tao; Ma, Xinlong

2014-10-01

312

Visualization and understanding of the granulation liquid mixing and distribution during continuous twin screw granulation using NIR chemical imaging.  

PubMed

Over the last decade, there has been increased interest in the application of twin screw granulation as a continuous wet granulation technique for pharmaceutical drug formulations. However, the mixing of granulation liquid and powder material during the short residence time inside the screw chamber and the atypical particle size distribution (PSD) of granules produced by twin screw granulation is not yet fully understood. Therefore, this study aims at visualizing the granulation liquid mixing and distribution during continuous twin screw granulation using NIR chemical imaging. In first instance, the residence time of material inside the barrel was investigated as function of screw speed and moisture content followed by the visualization of the granulation liquid distribution as function of different formulation and process parameters (liquid feed rate, liquid addition method, screw configuration, moisture content and barrel filling degree). The link between moisture uniformity and granule size distributions was also studied. For residence time analysis, increased screw speed and lower moisture content resulted to a shorter mean residence time and narrower residence time distribution. Besides, the distribution of granulation liquid was more homogenous at higher moisture content and with more kneading zones on the granulator screws. After optimization of the screw configuration, a two-level full factorial experimental design was performed to evaluate the influence of moisture content, screw speed and powder feed rate on the mixing efficiency of the powder and liquid phase. From these results, it was concluded that only increasing the moisture content significantly improved the granulation liquid distribution. This study demonstrates that NIR chemical imaging is a fast and adequate measurement tool for allowing process visualization and hence for providing better process understanding of a continuous twin screw granulation system. PMID:24211658

Vercruysse, Jurgen; Toiviainen, Maunu; Fonteyne, Margot; Helkimo, Niko; Ketolainen, Jarkko; Juuti, Mikko; Delaet, Urbain; Van Assche, Ivo; Remon, Jean Paul; Vervaet, Chris; De Beer, Thomas

2014-04-01

313

Osteomyelitis After TightRope(®) Fixation of the Ankle Syndesmosis: A Case Report and Review of the Literature.  

PubMed

Fixation of ankle syndesmosis injuries using the Ankle TightRope(®) has been gaining popularity. It has been shown to produce good results, facilitate early weightbearing, reduce the need for implant removal, and allow an earlier return to work and, possibly, a more anatomic syndesmotic reduction compared with screw fixation. However, its usage has been associated with complications such as soft tissue irritation, infection and wound breakdown, suture-button subsidence, and pathologic fracture from the screw tract. We describe a case of chronic osteomyelitis and suture-button migration associated with TightRope(®) fixation and a limited contact-dynamic compression plate for ankle syndesmosis disruption and lateral malleolus fracture. PMID:25451206

Hong, Choon Chiet; Lee, Wei Ting; Tan, Ken Jin

2015-01-01

314

A computational biomechanical investigation of posterior dynamic instrumentation: combination of dynamic rod and hinged (dynamic) screw.  

PubMed

Currently, rigid fixation systems are the gold standard for degenerative disk disease treatment. Dynamic fixation systems have been proposed as alternatives for the treatment of a variety of spinal disorders. These systems address the main drawbacks of traditional rigid fixation systems, such as adjacent segment degeneration and instrumentation failure. Pedicle-screw-based dynamic stabilization (PDS) is one type of these alternative systems. The aim of this study was to simulate the biomechanical effect of a novel posterior dynamic stabilization system, which is comprised of dynamic (hinged) screws interconnected with a coiled, spring-based dynamic rod (DSDR), and compare it to semirigid (DSRR and RSRR) and rigid stabilization (RSRR) systems. A validated finite element (FE) model of L1-S1 was used to quantify the biomechanical parameters of the spine, such as range of motion, intradiskal pressure, stresses and facet loads after single-level instrumentation with different posterior stabilization systems. The results obtained from in vitro experimental intact and instrumented spines were used to validate the FE model, and the validated model was then used to compare the biomechanical effects of different fixation and stabilization constructs with intact under a hybrid loading protocol. The segmental motion at L4-L5 increased by 9.5% and 16.3% in flexion and left rotation, respectively, in DSDR with respect to the intact spine, whereas it was reduced by 6.4% and 10.9% in extension and left-bending loads, respectively. After instrumentation-induced intradiskal pressure at adjacent segments, L3-L4 and L5-S1 became less than the intact in dynamic rod constructs (DSDR and RSDR) except in the RSDR model in extension where the motion was higher than intact by 9.7% at L3-L4 and 11.3% at L5-S1. The facet loads were insignificant, not exceeding 12N in any of the instrumented cases in flexion. In extension, the facet load in DSDR case was similar to that in intact spine. The dynamic rod constructions (DSDR and RSDR) led to a lesser peak stress at screws compared with rigid rod constructions (DSRR and RSRR) in all loading cases. A dynamic construct consisting of a dynamic rod and a dynamic screw did protect the adjacent level from excessive motion. PMID:24599026

Erbulut, Deniz U; Kiapour, Ali; Oktenoglu, Tunc; Ozer, Ali F; Goel, Vijay K

2014-05-01

315

Endoscopic transforaminal decompression, interbody fusion, and percutaneous pedicle screw implantation of the lumbar spine: A case series report  

PubMed Central

Background On the basis of the experiences gained from conventional open spinal procedures, a long list of desirable objectives have emerged with the evolution of the lesser invasive spinal procedures. At the top of that list is the desire to minimize the trauma of surgery. The rest of the objectives, which include reductions of operating time, surgical blood loss, hospital stay, postoperative narcotic medication, convalescence, complication rates, and escalating health care costs, as well as the desire of elderly patients to continue rigorous physical activities, largely depend on the ability to minimize the trauma of surgery. The purpose of this study was to investigate the feasibility of the least invasive lumbar decompression, interbody fusion and percutaneous pedicle screw implantation, to minimize surgical trauma without compromising the quality of the treatment outcome, as well as to minimize risk of complications. Methods In this case series, 60 patients with diagnoses of degenerative disc disease, degenerative motion segments with stenosis, and spondylolisthesis, in whom nonoperative treatments failed, were treated with endoscopic transforaminal decompression and interbody fusion by 1 surgeon in 2 centers. The outcome measures were as follows: operating time, intraoperative blood loss, hospital stay, Visual Analogue Scale (VAS) scores for back and leg pain, scores on the Roland-Morris Disability Questionnaire, and postoperative imaging studies. A consecutive series of patients who met the treatment criteria completed VAS forms and Roland-Morris questionnaires preoperatively. Surgical procedures included arthroscopic decompression of the foramina and the discs; endplate preparation and implantation of allograft bone chips and bone morphogenetic protein 2 on absorbable collagen sponge into the disc space; and percutaneous implantation of pedicle screws. Postoperatively, the patients again completed the VAS forms and Roland-Morris questionnaires. Their charts were reviewed for office notes, operative notes, hospital stay, medications, and imaging studies. The latest X-ray and computed tomography scan films were reviewed and analyzed. Patients were followed up for a minimum of 6 months. The literature was reviewed for comparison of outcomes. Results Sixty patients met the inclusion criteria. The mean age was 52.8 years. The duration of illness averaged 5 years. Follow-up ranged from 6 to 25 months, with a mean of 12 months. Preoperative diagnoses included degenerative disc disease, degenerative motion segments with stenosis, and spondylolisthesis. The mean time in the operating room was 2 hours 54 minutes. Estimated blood loss averaged 57.6 mL. The duration of the hospital stay averaged 2.6 days. Preoperative back pain and leg pain were significantly reduced (P < .005). Forty-seven imaging studies obtained at the last visit, including X-ray and computed tomography scans, showed solid fusion in 28 patients (59.6%), stable fixation in 17 (36.2%), and osteolysis around the pedicle screws in 2 (4.2%). All patients had improvement of motor function, whereas 2 patients complained of residual numbness. In addition, 8 patients (13%) complained of residual discomfort on extension of the lumbar spine. Two patients had pedicle screw–related complications requiring surgery. A review of the literature showed that endoscopic transforaminal decompression and interbody fusion performed better than open transforaminal lumbar interbody fusion/posterior lumbar interbody fusion, minimally invasive transforaminal lumbar interbody fusion, and extreme lateral lumbar interbody fusion, with regard to most parameters studied. Conclusions The endoscopic transforaminal lumbar decompression, interbody fusion, and percutaneous pedicle screw instrumentation consistently produced satisfactory results in all demographics. It performed better than the alternative procedures for most parameters studied.

Osman, Said G.

2012-01-01

316

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

317

Position and complications of pedicle screw insertion with or without image-navigation techniques in the thoracolumbar spine: a meta-analysis of comparative studies  

PubMed Central

Abstract Computer-navigated pedicle screw insertion is applied to the thoracic and lumbar spine to attain high insertion accuracy and a low rate of screw-related complications. However, some in vivo and in vitro studies have shown that no advantages are gained with the use of navigation techniques compared to conventional techniques. Additionally, inconsistent conclusions have been drawn in various studies due to different population characteristics and methods used to assess the accuracy of screw placement. Moreover, it is not clear whether pedicle screw insertion with navigation techniques decreases the incidence of screw-related complications. Therefore, this study was sought to perform a meta-analysis of all available prospective evidence regarding pedicle screw insertion with or without navigation techniques in human thoracic and lumbar spine. We considered in vivo comparative studies that assessed the results of pedicle screw placement with or without navigation techniques. PubMed, Ovid MEDLINE and EMBASE databases were searched. Three published randomized controlled trials (RCTs) and nine retrospective comparative studies met the inclusion criteria. These studies included a total of 732 patients in whom 4,953 screws were inserted. In conclusion, accuracy of the position of grade I, II, III and IV screws and complication rate related to pedicle screw placement were significantly increased when navigation techniques were used in comparison to conventional techniques. Future research in this area should include RCTs with well-planned methodology to limit bias and report on validated, patient-based outcome measures. PMID:25013406

Tang, Jinshan; Zhu, Ziqiang; Sui, Tao; Kong, Dechao; Cao, Xiaojian

2014-01-01

318

Biomechanical evaluation of a bioabsorbable expansion bolt for hamstring graft fixation in ACL reconstruction: an experimental study in calf tibial bone  

Microsoft Academic Search

Introduction: The purpose of our study was to evaluate and compare the primary fixation strength of a novel bioabsorbable two shell expansion bolt (EB) with that of a well-established interference screw-fixation technique in hamstring reconstruction of the anterior cruciate ligament. Materials and methods: Thirty calf tibia plateaus (age 5–6 months) were assigned to three groups: In group I (n=10) triple-stranded hamstring

S. Piltz; R. Dieckmann; L. Meyer; P. Strunk; W. Plitz; G. Lob

2005-01-01

319

The effect of the combination of locking screws and non-locking screws on the torsional properties of a locking-plate construct.  

PubMed

Little is known about the torsional properties of bone-plate constructs when a combination of locking and non-locking screws have been used. Sixty cadaveric canine femurs were divided into three groups. In the first group, the plate was affixed using three non-locking screws. In the second group, only locking screws were used while a combination of one locking and two non-locking screws were used in the third group. All constructs were subjected to torsion until failure. Torque, angle of torsion, and work were all calculated at the maximum failure point, as well as at five degrees of plastic deformation, which was thought to be more representative of clinical failure. At the maximum failure point, the locking group had significantly higher torque, angle, and work values than the non-locking group. The combination group was intermediate to the two other groups, and significantly differed from the non-locking group in torque, and from the locking group in work. At five degrees of plastic deformation, the locking group required significantly higher torque and work than the non-locking group. The combination group required a significantly higher torque than the non-locking group. This study suggests that a construct composed of all locking screws will fail at a greater torque value, and sustain greater work to failure in torsion compared to a construct composed of all non-locking screws. The addition of a single locking screw to an otherwise non-locking construct will increase the torque at the offset failure point and may be of clinical value in constructs subjected to high torsional loads. PMID:19997676

Gordon, S; Moens, N M M; Runciman, J; Monteith, G

2010-01-01

320

A new bicortical tibial fixation technique in anterior cruciate ligament reconstruction with quadruple hamstring graft  

Microsoft Academic Search

We report a prospective series of 101 patients receiving a four-strand semitendinosus-gracilis autograft for anterior cruciate\\u000a ligament reconstruction using a new bicortical tibial fixation technique with bioabsorbable interference screws. Patients\\u000a (average age 32 years) were operated on between November 1997 and Mai 1998, and follow-up was at least 12 months postoperatively.\\u000a The evaluation consisted of history, clinical examination, IKDC score,

J.-U. Buelow; R. Siebold; A. Ellermann

2000-01-01

321

Navigation of vertebro-pelvic fixations based on CT-fluoro matching  

Microsoft Academic Search

Different navigation procedures (based on 2D-, 3D-fluoroscopy or CT modalities) with their respective limitations are established\\u000a in orthopedic surgery. The hypothesis is that intraoperative matching of different modalities (fluoro and CT) increases the\\u000a precision of navigated screw placement and reduces the fluoroscopy time. Vertical unstable pelvic ring fractures of 12 patients\\u000a were treated with vertebro-pelvic fixations (6 in the standard

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

2010-01-01

322

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.

323

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

324

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

PubMed Central

A 49-year-old male presented with neck pain and deformity following an industrial accident sustained two months back. His neurology was normal except for a minimal weakness in left biceps (grade 4/5). Radiographs, magnetic resonance imaging and computed tomographic scan revealed fracture dislocation of C2-C3 with significant lateral translation of C2 over C3 without disc herniation. In view of unsuccessful closed reduction and absent disc herniation at the level of dislocation, a posterior only reduction, stabilisation and fusion with Iso-C 3D computer navigation-assisted cervical pedicle screw fixation with transverse rod-screw construct was performed. At 6 months followup the patient was completely relieved of his symptoms and was able to return to his previous occupation. The rare case is reported for the management by Iso-C 3D computer navigation assisted cervical pedicle screw fixation and reduction with transverse rod-screw construct at each involved level. PMID:21886931

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

2011-01-01

325

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

326

Coronal Acetabular Fractures: The Anterior Approach in Computed Tomography-Navigated Minimally Invasive Percutaneous Fixation  

SciTech Connect

Purpose: To demonstrate the technical feasibility of the anterior approach to the coronal roof component of carefully selected acetabular fractures in computed tomography (CT)-navigated closed reduction and percutaneous fixation (CRPF).Methods: Four patients with nondisplaced or slightly displaced coronal fractures of the acetabular roof were treated with percutaneous screw fixation. Screws were implanted over guidepins placed under CT navigation. Mean clinical and radiological follow-up was 16 months.Results: All screws could be placed as intended. There were no peri- or postoperative complications. Radiological follow-up showed primary osseous union. Clinical results were excellent according to a median Merle-d'Aubigne score of 18.Conclusion: Nondisplaced or slightly displaced coronally oriented fractures of the acetabular roof can be treated by minimally invasive percutaneous CT-navigated fixation through an anterior approach that does not endanger the sciatic nerve. Early clinical results are encouraging. Close cooperation between trauma surgeons and radiologists and careful selection of cases is mandatory.

Jacob, Augustinus Ludwig [Institute of Diagnostic Radiology, University Hospital of Basel, Petersgraben 4, CH-4031 Basel (Switzerland); Suhm, Norbert [Department of Surgery, University Hospital of Basel, Petersgraben 4, CH-4031 Basel (Switzerland); Kaim, Achim [Institute of Diagnostic Radiology, University Hospital of Basel, Petersgraben 4, CH-4031 Basel (Switzerland); Regazzoni, Pietro [Department of Surgery, University Hospital of Basel, Petersgraben 4, CH-4031 Basel (Switzerland); Steinbrich, Wolfgang [Institute of Diagnostic Radiology, University Hospital of Basel, Petersgraben 4, CH-4031 Basel (Switzerland); Messmer, Peter [Department of Surgery, University Hospital of Basel, Petersgraben 4, CH-4031 Basel (Switzerland)

2000-09-15

327

The Clinical Usefulness of Ultrasound-Aided Fixation Using an Absorbable Plate System in Patients with Zygomatico-Maxillary Fracture  

PubMed Central

Background Ultrasound-aided fixation is a recently developed alternative method of treatment of zygomatico-maxillary (ZM) fracture, and it can resolve the problems of excessive torsion force and subsequent fractures of screws. We conducted this study to evaluate the clinical usefulness of ultrasound-aided fixation as compared with the conventional fixation method using a drill and an expander in patients with ZM fracture. Methods We conducted a retrospective study in 35 patients with ZM fracture who had been treated at our hospital during a period ranging from March of 2008 to December of 2010. We divided them into two groups: an ultrasound-aided fixation group, comprising 13 patients who underwent ultrasound-aided fixation (SonicWeld Rx, KLS Martin), and a conventional group, comprising 22 patients who underwent conventional fixation (Biosorb FX, Linvatec Biomaterials Ltd.). We compared such variables as sex, direction, age at operation, follow-up period, operation duration, number of fixed holes, and time to discharge between the two groups. Results The ultrasound-aided fixation reduced the operation duration by about 30 minutes as compared with that of conventional fixation. There was no significant difference in follow-up period, number of fixed holes, or time to discharge between the two groups. Furthermore, there were no complications in either group. Conclusions The ultrasound-aided fixation of fractured ZM bone using an absorbable implant system is safe and effective in promptly reducing the bone fracture and providing satisfactory cosmetic outcomes over time. PMID:23898427

Park, Jun Hyung

2013-01-01

328

The Fixation of Nitrogen.  

ERIC Educational Resources Information Center

Discusses the fixation of atmospheric nitrogen in the form of ammonia as one of the foundations of modern chemical industry. The article describes ammonia production and synthesis, purifying the hydrogen-nitrogen mix, nitric acid production, and its commericial plant. (HM)

Andrew, S. P. S.

1978-01-01

329

Update: Biological Nitrogen Fixation.  

ERIC Educational Resources Information Center

Updates knowledge on nitrogen fixation, indicating that investigation of free-living nitrogen-fixing organisms is proving useful in understanding bacterial partners and is expected to lead to development of more effective symbioses. Specific areas considered include biochemistry/genetics, synthesis control, proteins and enzymes, symbiotic systems,…

Wiseman, Alan; And Others

1985-01-01

330

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

331

External fixation of tibial fractures.  

PubMed

External fixation for definitive or initial management of tibial fractures has a long history, with pin-to-bar external fixation being the standard of care for definitive management of tibial fractures. However, the use of this method lessened because of the increased popularity of intramedullary nailing and drawbacks associated with external fixation. This method is still commonly in use in the military environment and can be used for temporary stabilization of tibial fractures, especially in the setting of periarticular injuries. These fixators also may be useful for salvage of open and/or infected fractures that are unsuitable for internal fixation. PMID:25613987

Tejwani, Nirmal; Polonet, David; Wolinsky, Philip R

2015-02-01

332

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

333

A Comparison of the Fixation Strengths Provided by Different Intraosseous Tendon Lengths during Anterior Cruciate Ligament Reconstruction: A Biomechanical Study in a Porcine Tibial Model  

PubMed Central

Background The purpose of this study was to determine the tibial fixation strength provided by different intraosseous soft tissue graft lengths within the tibial tunnel. Methods Porcine tibial bones and digital flexor tendons were used for testing. Bone mineral densities of proximal tibial medial condyles were measured, and two-strand tendon bundles of 8 mm diameter were used. An intraosseous graft length of 2 cm was used in group 1 (n = 10), and a graft length of 4 cm was used in group 2 (n = 10). Tunnels were 4 cm in length and 8 mm in diameter. Tibial fixation was performed using a suture tied around a screw post with a washer and an additionally inserted 7 × 20 mm bioabsorbable screw. After applying preconditioning loading of 10 cycles, 1,000 cycles between 70-220 N were applied at a frequency of 1 Hz. Graft slippage and total graft movement were recorded. Ultimate tensile strength was measured by pull-out testing at an Instron crosshead speed of 1,000 mm/min. Results No significant intergroup difference was found for total graft movement after cyclic loading (slippage in group 1, 1.2 mm and group 2, 1.2 mm, respectively, p = 0.917; and total graft movement in group 1, 3.3 mm and group 2, 2.7 mm, respectively, p = 0.199). However, mean ultimate tensile strength in group 2 was significantly higher than that in group 1 (group 1, 649.9 N; group 2, 938 N; p = 0.008). Conclusions In a porcine model, ultimate tensile strength was greater for a 4 cm long intraosseous flexor tendon in the tibial tunnel. However, no intergroup difference in graft slippage or total graft movement was observed. The results show that a 2 cm intraosseous graft length in the tibial tunnel is safe and has sufficient strength (> 450 N) for adequate rehabilitation after anterior cruciate ligament reconstruction. PMID:24900898

Yang, Dong-Lyul; Cheon, Sang-Ho; Oh, Chang-Wug

2014-01-01

334

Tibial Tunnel Widening After Hamstring Tendon Anterior Cruciate Ligament ReconstructionThe Effect of Supplemental Aperture Fixation With Autogenous Bone Cores  

Microsoft Academic Search

Background: Tibial tunnel widening is a common phenomenon seen with hamstring anterior cruciate ligament reconstruction. Concern exists that increased tunnel widening can lead to delayed graft incorporation, graft laxity, or difficulties in revision surgery.Hypothesis: Supplemental aperture fixation with autogenous bone cores or bioabsorbable interference screws will decrease tibial tunnel widening in hamstring anterior cruciate ligament reconstruction.Study Design: Cohort study; Level

W. Randall Schultz; Russell C. McKissick; Jesse C. DeLee

2007-01-01

335

Internal fixation versus hemiarthroplasty versus total hip arthroplasty for displaced subcapital fractures of femur — 13 year results of a prospective randomised study  

Microsoft Academic Search

In this prospective randomised trial we compare the mortality, morbidity and functional results of patients following each of the three principal methods of treatment for displaced subcapital fractures of the femur. Two hundred and ninety patients over the age of 65 years were included and randomly allocated to undergo closed reduction and internal fixation with a sliding compression screw plate

Kasetti J. Ravikumar; Gavin Marsh

2000-01-01

336

C2 Pars/Pedicle Screws in Management of Craniocervical and Upper Cervical Instability  

PubMed Central

Study Design A retrospective study. Purpose To evaluate the efficacy and the safety of craniocervical and upper cervical stabilization by using C2 pars/pedicle screw fixations. Overview of Literature The management of craniocervical and upper cervical instability has progressed over the past two decades due to good achievements in the instrumentation and the increased awareness on spinal anatomy and biomechanics. However, there is insufficient studies or solid conclusions on this topic, thus, we tried to investigate and present our findings. Methods Twenty-two patients were operated upon and were followed up from March 2008 to October 2010. One patient had craniocervical instability (post-surgical), 15 patients had atlantoaxial instability of different etiologies (trauma, tumors, inflammatory and degenerative) and 6 patients had hangman fractures. Patients' ages ranged from 18 to 52 years old. with 5 female patients and 17 male patients. Results Radiological follow ups performed immediately post-operation showed good screw positioning and complete reductions in nearly all the cases. All patients were followed up for more than one year. Sound fusions were observed among all patients. Conclusions The use of pars/pedicle screws is a very effective, sound, safe and easy surgical modality for treating craniocervical, atlantoaxial and upper cervical instabilities. Increasing studies for the biomechanics of this important region and longer periods of follow-ups are necessary to document the usefulness of this modality when treating such patients. PMID:24761197

2014-01-01

337

Fixation techniques for the anterior cruciate ligament reconstruction: early follow-up. A systematic review of level I and II therapeutic studies.  

PubMed

The purpose of our study was that to systematically review the fixation techniques for the ACL reconstruction and associated clinical outcomes at the early follow-up. Systematic search on three electronic databases (Cochrane register, Medline and Embase) of fixation devices used for primary ACL reconstruction with doubled semitendinosus and gracilis and bone-patellar tendon-bone autografts in randomized clinical trials of level I and II of evidence published from January 2001 to December 2011. Therapeutic studies collected were with a minimum 12-month follow-up, and the clinical outcomes were evaluated by at least one of International Knee Documentation Committee, Lysholm and Tegner functional scales and at least one of the following knee stability tests: arthrometric AP tibial translation, Lachman test and pivot-shift test. Nineteen articles met the inclusion criteria. At the femoral side cross-pin, metallic interference screw, bioabsorbable interference screw, and suspensory device were used in 32.3, 27.3, 24.8, 15.5 % of patients, respectively. At the tibial side fixation was achieved with metallic interference screw, bioabsorbable interference screw, screw and plastic sheath, screw post and cross-pin in 38.7, 31, 15.7, 12.8, and 1.7 % of patients, respectively. Side-to-side anterior-posterior tibial translation was 1.9 ± 0.9, 1.5 ± 0.9, 1.5 ± 0.8, 2.2 ± 0.4 mm for metallic interference screw, bioabsorbable screw, cross-pin and suspensory device, respectively. At least two-third of all the patients achieved good-to-excellent clinical outcomes. Rate of failure was 6.1, 3.3, 1.7 and 1.2 % for bioabsorbable interference screw, metallic interference screw, cross-pin and suspensory device, respectively. Clinical outcomes are good to excellent in almost two-third of the patients but several pitfalls that affect the current fixation techniques as graft tensioning such as graft-tunnel motion are still unaddressed. PMID:25269758

Speziali, Andrea; Delcogliano, Marco; Tei, Matteo; Placella, Giacomo; Bartoli, Matteo; Menghi, Amerigo; Cerulli, Giuliano

2014-12-01

338

CARBON DIOXIDE FIXATION.  

SciTech Connect

Solar carbon dioxide fixation offers the possibility of a renewable source of chemicals and fuels in the future. Its realization rests on future advances in the efficiency of solar energy collection and development of suitable catalysts for CO{sub 2} conversion. Recent achievements in the efficiency of solar energy conversion and in catalysis suggest that this approach holds a great deal of promise for contributing to future needs for fuels and chemicals.

FUJITA,E.

2000-01-12

339

Comparison between Single and Dual Femoral Fixation for Anterior Cruciate Ligament Reconstruction with a Hamstring Autograft  

PubMed Central

Purpose The purpose of this study was to evaluate dual fixation with different fixation mechanisms, determine the advantages, and compare the outcomes between single and dual femoral fixation. Materials and Methods From April 2004 to September 2007, 19 patients who received single femoral fixation and 22 patients who received dual femoral fixation were enrolled in the study. Single femoral fixation was performed using a cross-pin expansion mechanism. Dual femoral fixation was performed using a cross-pin expansion mechanism and an EndoButton CL loop suspensory mechanism. Results No significant differences were found in the incidence of cross-pin problems between the two groups (p=0.35-0.83) or in the stability assessment using a KT-2000 arthrometer and pivot shift test preoperatively (p=0.79 and 0.77, respectively) or postoperatively (p=0.89 and 0.75, respectively). In addition, no significant differences were detected between the two groups in the Lysholm, Tegner activity, or International Knee Documentation Committee knee scores preoperatively (p=0.07-0.47) or postoperatively (p=0.15-0.89). Conclusions This study showed that dual fixation with different fixation mechanisms was not advantageous over the single fixation mechanism. Outcomes using the dual femoral fixation mechanism were not superior to those using the single femoral fixation mechanism. PMID:22570828

Kim, Jin Goo; Kim, Nam Ki

2011-01-01

340

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

341

[Implant materials for the internal fixation of midfacial fractures].  

PubMed

The material used for osteosynthesis plays a crucial role in the management of facial fractures. Plates need to be flexible enough to be bent and should not be palpable through the skin, while ensuring stable fixation und adequate biocompatibility. Although stainless steel was initially the material of choice, titanium has become the standard material due to its superior biocompatibility. While the explantation of titanium plates and screws appears unnecessary in general, it should be considered in cases of dislocation, cosmetic concerns, pain and infection. Due to their limited initial stability and a potential increase in local complications, resorbable materials based on polymeric lactose are used with caution in midfacial fractures in adults. Our own retrospective study comparing the postoperative complications after fixation of lateral midfacial fractures with titanium and resorbable systems demonstrated a low complication rate for both systems (7-8%) and no statistically significant difference between the two. The appropriate material for fixation should be selected based on the localization and severity of the fracture, the experience of the surgeon as well as on the age and overall condition of the patient. PMID:22012485

Stuck, B A; Heller, T

2011-11-01

342

Minimally Invasive Spinal Arthrodesis in Osteoporotic Population Using a Cannulated and Fenestrated Augmented Screw: Technical Description and Clinical Experience  

PubMed Central

We describe a percutaneous or minimally invasive approach to apply an augmentation of pedicle fenestrated screws by injection of the PMMA bone cement through the implant and determine the safety and efficiency of this technique in a clinical series of 15 elderly osteoporotic patients. Clinical outcome and the function were assessed using respectively the Visual Analogue Scale (VAS) score and the Oswestry Disability Index (ODI). Peri- and post-operative complications were monitored during a minimum of 2 years of follow-up. Radiographic follow-up was based on plain fluoroscopic control at 3, 6 and 12 months and every year. In this approach, four steps were considered with care: optimal positioning of the screws, correct alignment of the screw heads, waiting time before the injection of cement, fluoroscopic control of the cement injection. Using these precautions, only 2 minor complications occurred. VAS scores and ODI questionnaires showed a statistically significant improvement up to 13.3 months postoperatively. No radiological complications were observed. Based on this experience, PMMA augmentation technique through the novel fenestrated screws provided an effective and long lasting fixation in osteoporotic patients. Applying this procedure through percutaneous or minimally invasive approach under fluoroscopic control seems to be safe. PMID:22970360

Lubansu, Alphonse; Rynkowski, Michal; Abeloos, Laurence; Appelboom, Geoffrey; Dewitte, Olivier

2012-01-01

343

A Prospective Randomized Study of Anterior Cruciate Ligament ReconstructionA Comparison of Patellar Tendon and Quadruple-Strand Semitendinosus\\/Gracilis Tendons Fixed With Bioabsorbable Interference Screws  

Microsoft Academic Search

Background: Debate exists regarding the optimal graft for anterior cruciate ligament reconstruction. Few studies have compared the differences in outcome after reconstruction using similar fixation methods.Hypothesis: Similar outcomes will be seen after anterior cruciate ligament reconstruction with bone-patellar tendon-bone or quadruple-strand semitendinosus\\/gracilis tendons fixed with bioabsorbable interference screws.Study Design: Randomized controlled trial; Level of evidence, 1.Methods: Ninety-nine patients were prospectively

Gregory B. Maletis; Sheri L. Cameron; Joann J. Tengan; Raoul J. Burchette

2007-01-01

344

Correlation of interference screw insertion torque with depth of placement in the tibial tunnel using a quadrupled semitendinosus-gracilis graft in anterior cruciate ligament reconstruction  

Microsoft Academic Search

Purpose: To evaluate the insertion torque of a soft-tissue interference screw in relation to depth of insertion into the tibial tunnel when used for fixation of a quadrupled semitendinosus-gracilis autograft in anterior cruciate ligament reconstruction. Type of Study: Biomechanical cadaver study. Methods: Ten quadrupled semitendinosus-gracilis grafts were harvested from fresh-frozen cadaver knees and fixed in donor proximal tibias using 10-mm

Barry B. Phillips; E. Lyle Cain; Jeffrey A. Dlabach; Frederick M. Azar

2004-01-01

345

Anatomical study of anterior column screw tunnels through virtual three-dimensional models of the pelvis.  

PubMed

We created 66 male and 74 female virtual three-dimensional models of the pelvis based on computed tomography data from 140 patients. Virtual cylindrical bolts (VCBs) were placed in the anterior column (AC), which was then resliced serially along the bolt's long axis. AC screw tunnel mainly comprises two long, narrow triangular prisms [zone III (acetabular fossa) and zone V (obturator foramen)]-forming the III/V angle-linked by a larger, shorter cylinder [zone IV (acetabular notch)]. VCBs' mean length and maximum diameter were 111.13 ± 7.33 and 7.37 ± 1.90 mm, respectively. The models' anatomical zone lengths were similar between the sexes. Zone V's narrowest diameters and the III/V angles were significantly different. VCBs >6.5 mm were accommodated in 65 of 66 male models and 31 of 74 female models. VCBs >5.0 and <6.5 mm were accommodated in one male and 30 female models. Eleven female models accommodated only VCBs >3.5 and <5.0 mm. However, to 13 female pelvic models with maximum VCB accommodation of <5 mm for the anterior column, the maximum diameter of the VCBs was 8.23 ± 1.22 mm in medial passage and 10.3 ± 1.91 mm in lateral passage, respectively. Percutaneous fixation of the AC with screws is a safe technique, even though in Chinese female patients. The narrowest diameters in zone V and the III/V angles are the key factors for application of AC screws. Female patients with a smaller interosseous space at zone V and a large III/V angle can accommodate segmental passage screws. PMID:24413847

Chen, Hua; Tang, Peifu; Yao, Yimin; She, Fei; Wang, Yan

2015-01-01

346

Melt temperature field measurement in single screw extrusion using thermocouple meshes  

NASA Astrophysics Data System (ADS)

The development and validation of a sensor for extrusion melt temperature field measurement is described. A grid of opposing thermocouple wires was constructed and held in position by a supporting frame. Wires were joined together at crossing points to form thermocouple junctions, which were computer monitored. The mesh was used to monitor melt temperature fields during single screw extrusion at the die entrance. Design and construction of the mesh is described in addition to experimental optimization of wire diameter and junction forming. Calibration of the sensor and potential measurement errors including shear heating effects are discussed. Initial results from single screw extrusion are presented for a commercial grade of low density polyethylene using five- and seven-junction thermocouple meshes. The dependence of melt temperature profile on screw speed is illustrated. At low screw speeds melt temperature profiles were flat in shape and higher than set wall temperatures. At higher screw speeds the profiles became more pointed in shape. Use of higher resolution sensors exposed more complex temperature profiles with shoulder regions.

Brown, E. C.; Kelly, A. L.; Coates, P. D.

2004-11-01

347

Fixation of the NexGen HA-TCP-coated cementless, screwless total knee arthroplasty: comparison with conventional cementless total knee arthroplasty of the same type.  

PubMed

We performed a 12-month prospective study on 59 patients (92 knees) who underwent NexGen (Zimmer Inc, Warsaw, IN) cruciate-retaining total knee arthroplasty. In the control group, uncoated components were fixed using screws, whereas the hydroxyapatite-tricalcium phosphate (HA-TCP) group underwent screwless fixation of coated components. At 12 months postoperatively, there was a radiographic clear zone around the femoral and tibial components of 56.5% and 32.6% of the knees in the control group. The HA-TCP group showed a clear zone at the medial aspect of the tibial component in only 1 knee. These results suggested that HA-TCP-coated articular components show good initial fixation without using screws. The NexGen coated knee arthroplasty may be useful for solving the problems of cementless fixation. PMID:12066275

Gejo, Ryuichi; Akizuki, Shaw; Takizawa, Tsutomu

2002-06-01

348

Intraoral epimucosal fixation for reducible maxillary fractures of the jaws; surgical considerations in comparison to current techniques.  

PubMed

Fractures of the jaw are often treated with rigid and stable internal fixation using plates or miniplates. Early surgery for jaw fractures is the optimal treatment; however, if a late treatment is begun, often the adoption of other protocols is needed. When the jaw fracture has one free bone fragment with 2 full-thickness lesions of mucoperiosteal soft tissues both on the buccal and palatal sides, the risk of resorption or necrosis is very high after elevating a mucoperiosteal flap for rigid fixation. For this reason, we developed an intraoral epimucosal fixation technique using self-locking screws and plates. Substantial advantages of this new technique, in comparison with other commonly used fixation techniques, consisted in the prevention of bone resorption or necrosis by safe and simple screw insertion procedure after manipulation of the fracture for reduction in closed surgery. Major indications for epimucosal fixation in closed surgery are the presence of jaw fractures without dislocation or reducible jaw fractures by manipulation particularly in edentulous patients. PMID:25318439

Cortese, Antonio; Savastano, Germano; Amato, Massimo; Pantaleo, Giuseppe; Claudio, Pier Paolo

2014-11-01

349

[Methods of collagenous tissue fixation in the preparation of bioprostheses].  

PubMed

The use of biological materials in construction of bioprostheses requires the application of different chemical or physical procedures of fixation increasing bioprostheses resistance to enzymatic or chemical degradation and reducing their antigenicity. Methods typically concentrate on creating additional intra- and intermolecular chemical bonds between collagen molecules. This review focuses on the various methods of stabilization of collagenous tissues including chemical fixatives and physical agents. PMID:14737970

Olczyk, Pawe?; Ku?nik-Trocha, Kornelia; Olczyk, Krystyna; Ko?ma, Ewa Maria; G?owacki, Andrzej; Wisowski, Grzegorz; Jura-Pó?torak, Agnieszka; Nawrat, Zbigniew

2003-01-01

350

Precision dosing of powders by vibratory and screw feeders: an experimental study  

Microsoft Academic Search

The addition of small amounts of very precisely dosed powdery ingredients into bulk powders and\\/or liquid mixtures is important in such industrial operations as mixing, granulation and crystallization. The general practice is to use a screw, vibration or belt feeder combined with a loss by weight device and an appropriate controller. The present work concentrates on two vibratory feeders, one

Gabriel I. Tardos; Quingyang Lu

1996-01-01

351

Definitive Bone Fixation and Reconstruction: Conversion from Temporary External Fixation to Internal Fixation Methods  

Microsoft Academic Search

\\u000a Temporary external fixation is frequently employed in the military combat theater of operations to temporize devastating extremity\\u000a injuries and facilitate transport of the wounded soldier. Multiple civilian and a few military studies have provided helpful\\u000a insight into the staged treatment of these injuries including conversion of temporary external fixation to definitive stabilization\\u000a with internal fixation. Diaphyseal fractures of the long

Craig S. Bartlett; Benjamin Geer; David L. Helfet

352

Nitrogen fixation in the Baltic proper: an empirical study  

NASA Astrophysics Data System (ADS)

Nitrogen as the limiting nutrient for primary production in the eutrophic Baltic proper has been under debate. Based on only a limited number of actual measurements, nitrogen fixation has been assumed to be the only significant internal nitrogen source. It is then assumed that about one fifth of the net nitrogen load to the Baltic proper comes from nitrogen fixation by cyanobacteria. An alternative or additional source is utilisation of dissolved organic nitrogen (DON). In the present study, we hypothesise that nitrogen fixation is the only internal source for inorganic nitrogen. This was done in order to investigate its potential to maintain net primary production during summer. If inorganic nitrogen is depleted after the spring bloom and if inorganic phosphorus still remains in significant concentrations, then a continuous decrease in phosphorus may be coupled to the net nitrogen fixation rate by cyanobacteria. The estimated phosphorus consumption is adjusted for external and internal inputs. An estimate of the assumed net annual nitrogen fixation based on the proper Redfield ratio in the surface layer down to the seasonal thermocline is calculated for a number of monitoring stations in the Baltic proper. Typical values of nitrogen fixation are in the range 10-130 ?mol m -3 day -1. A simple integration over the Baltic proper gives an internal load in the range 30-260×10 3 ton N year -1. Another result is an east-west gradient in fixation rate that may reflect the nitrogen load.

Rahm, L.; Jönsson, A.; Wulff, F.

2000-07-01

353

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

354

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

355

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

356

Pedicle Screw Instrumentation for Adolescent Idiopathic Scoliosis: The Insertion Technique, the Fusion Levels and Direct Vertebral Rotation  

PubMed Central

The pedicle is a power nucleus of the vertebra and offers a secure grip of all 3 columns. Pedicle screw instrumentation has advantages of rigid fixation with improved three-dimensional (3D) correction and it is accepted as a reliable method with a high margin of safety. Accurate placement of the pedicle screws is important to reduce possible irreversible complications. Many methods of screw insertion have been reported. The author has been using the K-wire method coupled with the intraoperative single posteroanterior and lateral radiographs, which is the most safe, accurate and fast method. Identification of the curve patterns and determining the fusion levels are very important. The ideal classification of adolescent idiopathic scoliosis should address the all patterns, predict the extent of accurate fusion and have good inter/intraobserver reliability. My classification system matches with the ideal classification system, and it is simple and easy to learn; and my classification system has only 4 structural curve patterns and each curve has 2 types. Scoliosis is a 3D deformity; the coronal and sagittal curves can be corrected with rod rotation, and rotational deformity has to be corrected with direct vertebral rotation (DVR). Rod derotation and DVR are true methods of 3D deformity correction with shorter fusion and improved correction of both the fused and unfused curves, and this is accomplished using pedicle screw fixation. The direction of DVR is very important and it should be opposite to the direction of the rotational deformity of the vertebra. A rigid rod has to be used to prevent rod bend-out during the derotation and DVR. PMID:21629468

2011-01-01

357

Early Experience With Poly L-Lactic Acid Bioabsorbable Fixation System for Paediatric Craniosynostosis Surgery. Report of 3 Cases  

Microsoft Academic Search

Summary  ¶?Objective. The authors describe early experience in the use of bioabsorbable fixation devices for cranial reconstruction of paediatric\\u000a craniosynostosis patients.\\u000a \\u000a ?Methods. Three patients, individually respectively presenting sagittal synostosis, metopic synostosis, and clover leaf skull deformity,\\u000a underwent cranial reconstruction using poly L-lactic acid (PLLA) plates and screws. The patients ranged in age from 2 to 10\\u000a months at the time of

H. Arai; K. Sato; O. Okuda; M. Miyajima; M. Hishii; H. Nakanishi; H. Ishii

2000-01-01

358

Biomechanical comparison of hamstring tendon fixation devices for anterior cruciate ligament reconstruction: part 1. Five femoral devices.  

PubMed

We conducted a study to biomechanically compare 5 femoral hamstring tendon fixation devices commonly used in anterior cruciate ligament reconstruction. Quadrupled human semitendinosus-gracilis tendon grafts were fixed into porcine femurs using 5 separate fixation devices. For each device, 10 specimens were tested (1500-cycle loading test at 50-200 N). Specimens surviving the cyclic loading then underwent a single load-to-failure (LTF) test. Failure mode, stiffness, ultimate load, and rigidity were recorded. Two of 10 Delta screw (Arthrex), 10 of 10 Bio-TransFix (Arthrex), 10 of 10 Bone Mulch screw (Arthrotek), 10 of 10 EZLoc (Arthrotek), and 10 of 10 Zip Loop (Arthrotek) devices completed the 1500-cycle loading test. Residual displacement was lowest for Bio-TransFix (4.1 mm) followed by Bone Mulch (5.2 mm), EZLoc (6.4 mm), Zip Loop (6.8 mm), and Delta (8.2 mm). Mean stiffness was significantly (P < .001) higher for Bone Mulch (218 N/mm) than for Bio-TransFix (171 N/mm), EZLoc (122 N/mm), Zip Loop (105 N/mm), or Delta (84 N/mm). Mean LTF was significantly ( P < .001) higher for Bone Mulch (867 N) than for Zip Loop (615 N), Bio-TransFix (552 N), EZLoc (476 N), or Delta (410 N). The Bone Mulch screw demonstrated superior strength in the fixation of hamstring grafts in the femur. Bio-TransFix was close behind. The Delta screw demonstrated poor displacement, stiffness, and LTF. When used as the sole femoral fixation device, a device with low LTF, decreased stiffness, and high residual displacement should be used cautiously in patients undergoing aggressive rehabilitation. PMID:25566554

Scannell, Brian P; Loeffler, Bryan J; Hoenig, Michael; Peindl, Richard D; D'Alessandro, Donald F; Connor, Patrick M; Fleischli, James E

2015-01-01

359

Eighth international congress on nitrogen fixation  

SciTech Connect

This volume contains the proceedings of the Eighth International Congress on Nitrogen Fixation held May 20--26, 1990 in Knoxville, Tennessee. The volume contains abstracts of individual presentations. Sessions were entitled Recent Advances in the Chemistry of Nitrogen Fixation, Plant-microbe Interactions, Limiting Factors of Nitrogen Fixation, Nitrogen Fixation and the Environment, Bacterial Systems, Nitrogen Fixation in Agriculture and Industry, Plant Function, and Nitrogen Fixation and Evolution.

Not Available

1990-01-01

360

Biomechanical Study in Polyurethane Mandibles of Different Metal Plates and Internal Fixation Techniques, Employed in Mandibular Angle Fractures.  

PubMed

The aim of this study was to perform a physicochemical and morphological characterization and compare the mechanical behavior of an experimental Ti-Mo alloy to the analogous metallic Ti-based fixation system, for mandibular angle fractures. Twenty-eight polyurethane mandibles were uniformly sectioned on the left angle. These were divided into 4 groups: group Eng 1P, one 2.0-mm plate and 4 screws 6 mm long; group Eng 2P, two 2.0-mm plates, the first fixed with 4 screws 6 mm long and the second with 4 screws 12 mm long. The same groups were created for the Ti-15Mo alloy. Each group was subjected to linear vertical loading at the first molar on the plated side in a mechanical testing unit. Means and standard deviations were compared with respect to statistical significance using ANOVA. The chemical composition of the Ti-15Mo alloy was close to the nominal value. The mapping of Mo and Ti showed a homogeneous distribution. SEM of the screw revealed machining debris. For the plates, only the cpTi plate undergoes a surface treatment. The metallographic analysis reveals granular microstructure, from the thermomechanical trials. A statistically significant difference was found (P < 0.05) when the comparison between both internal fixation techniques was performed. The 2P technique showed better mechanical behavior than 1P. PMID:25340696

Guastaldi, Fernando Pozzi Semeghini; Hochuli-Vieira, Eduardo; Guastaldi, Antonio Carlos

2014-10-21

361

Understanding Nitrogen Fixation  

SciTech Connect

The purpose of our program is to explore fundamental chemistry relevant to the discovery of energy efficient methods for the conversion of atmospheric nitrogen (N{sub 2}) into more value-added nitrogen-containing organic molecules. Such transformations are key for domestic energy security and the reduction of fossil fuel dependencies. With DOE support, we have synthesized families of zirconium and hafnium dinitrogen complexes with elongated and activated N-N bonds that exhibit rich N{sub 2} functionalization chemistry. Having elucidated new methods for N-H bond formation from dihydrogen, C-H bonds and Broensted acids, we have since turned our attention to N-C bond construction. These reactions are particularly important for the synthesis of amines, heterocycles and hydrazines with a range of applications in the fine and commodity chemicals industries and as fuels. One recent highlight was the discovery of a new N{sub 2} cleavage reaction upon addition of carbon monoxide which resulted in the synthesis of an important fertilizer, oxamide, from the diatomics with the two strongest bonds in chemistry. Nitrogen-carbon bonds form the backbone of many important organic molecules, especially those used in the fertilizer and pharamaceutical industries. During the past year, we have continued our work in the synthesis of hydrazines of various substitution patterns, many of which are important precursors for heterocycles. In most instances, the direct functionalization of N{sub 2} offers a more efficient synthetic route than traditional organic methods. In addition, we have also discovered a unique CO-induced N{sub 2} bond cleavage reaction that simultaneously cleaves the N-N bond of the metal dinitrogen compound and assembles new C-C bond and two new N-C bonds. Treatment of the CO-functionalized core with weak Broensted acids liberated oxamide, H{sub 2}NC(O)C(O)NH{sub 2}, an important slow release fertilizer that is of interest to replace urea in many applications. The synthesis of ammonia, NH{sub 3}, from its elements, H{sub 2} and N{sub 2}, via the venerable Haber-Bosch process is one of the most significant technological achievements of the past century. Our research program seeks to discover new transition metal reagents and catalysts to disrupt the strong N {triple_bond} N bond in N{sub 2} and create new, fundamental chemical linkages for the construction of molecules with application as fuels, fertilizers and fine chemicals. With DOE support, our group has discovered a mild method for ammonia synthesis in solution as well as new methods for the construction of nitrogen-carbon bonds directly from N{sub 2}. Ideally these achievements will evolve into more efficient nitrogen fixation schemes that circumvent the high energy demands of industrial ammonia synthesis. Industrially, atmospheric nitrogen enters the synthetic cycle by the well-established Haber-Bosch process whereby N{sub 2} is hydrogenated to ammonia at high temperature and pressure. The commercialization of this reaction represents one of the greatest technological achievements of the 20th century as Haber-Bosch ammonia is responsible for supporting approximately 50% of the world's population and serves as the source of half of the nitrogen in the human body. The extreme reaction conditions required for an economical process have significant energy consequences, consuming 1% of the world's energy supply mostly in the form of pollution-intensive coal. Moreover, industrial H{sub 2} synthesis via the water gas shift reaction and the steam reforming of methane is fossil fuel intensive and produces CO{sub 2} as a byproduct. New synthetic methods that promote this thermodynamically favored transformation ({Delta}G{sup o} = -4.1 kcal/mol) under milder conditions or completely obviate it are therefore desirable. Most nitrogen-containing organic molecules are derived from ammonia (and hence rely on the Haber-Bosch and H{sub 2} synthesis processes) and direct synthesis from atmospheric nitrogen could, in principle, be more energy-efficient. This is particularly attractive giv

Paul J. Chirik

2012-05-25

362

Anatomic Feasibility of Posterior Cervical Pedicle Screw Placement in Children: Computerized Tomographic Analysis of Children Under 10 Years Old  

PubMed Central

Objective To evaluate the anatomical feasibility of 3.5 mm screw into the cervical spine in the pediatric population and to establish useful guidelines for their placement. Methods A total of 37 cervical spine computerized tomography scans (24 boys and 13 girls) were included in this study. All patients were younger than 10 years of age at the time of evaluation for the period of 2007-2011. Results For the C1 screw placement, entry point height (EPH) was the most restrictive factor (47.3% patients were larger than 3.5 mm). All C2 lamina had a height larger than 3.5 mm and 68.8% (51/74) of C2 lamina had a width thicker than 3.5 mm. For C2 pedicle width, 55.4% (41/74) of cases were larger than 3.5 mm, while 58.1% (43/74) of pedicle heights were larger than 3.5 mm. For pedicle width of subaxial spine, 75.7% (C3), 73% (C4), 82.4% (C5), 89.2% (C6), and 98.1% (C7, 1/54) were greater than 3.5 mm. Mean lamina width of subaxial cervical spine was 3.1 (C3), 2.7 (C4), 2.9 (C5), 3.8 (C6), and 4.0 mm (C7), respectively. Only 34.6% (127/370) of subaxial (C3-7) lamina thickness were greater than 3.5 mm. Mean length of lateral mass for the lateral mass screw placement was 9.28 (C3), 9.08 (C4), 8.81 (C5), 8.98 (C6), and 10.38 mm (C7). Conclusion C1 lateral mass fixation could be limited by the morphometrics of lateral mass height. C2 trans-lamina approach is preferable to C2 pedicle screw fixation. In subaxial spines, pedicle screw placement was preferable to trans-lamina screw placement, except at C7.

Lee, HoJin; Kim, Il Sup; Kim, Moon Suk; Sung, Jae Hoon; Lee, Sang Won

2014-01-01

363

Percutaneous S2 alar iliac fixation for pelvic insufficiency fracture.  

PubMed

Pelvic insufficiency fractures are fairly common in elderly patients and can be a source of major functional impairment, particularly when they involve the ilium. Early rehabilitation with adequate pain relief has been the traditional method of treatment. The recently developed S2 alar iliac technique involves placing pelvic fixation into the ilium through a pathway from the sacral ala. The bony channel between the second dorsal sacral foramen and the anterior inferior iliac spine is used to provide rigid sacropelvic fixation for adult and pediatric spine deformities. The authors describe a new minimally invasive approach that allows percutaneous stabilization of an iliac fracture with 2 S2 alar iliac screws. A 65-year-old woman with a history of rectal carcinoma that was treated with pelvic radiation had an iliac stress fracture that progressed to nonunion. Extensive nonoperative treatment was unsuccessful, and the patient continued to have symptoms 5 years after the initial diagnosis. An open approach vs a minimally invasive technique was debated. The S2 alar iliac screws were used to stabilize the fracture through a minimally invasive approach. Most of the symptoms resolved in 2 months, with radiographic evidence of union at 6 months. To the authors' knowledge, this report is the first to describe a percutaneous approach for stabilizing iliac insufficiency fractures. This technique provides a safe surgical option for treating iliac stress fractures in some patients for whom nonoperative treatment fails while avoiding the complications and soft tissue compromise associated with open procedures. Longer follow-up and a larger series are needed to show the safety and efficacy of this technique. PMID:25361366

El Dafrawy, Mostafa H; Kebaish, Khaled M

2014-11-01

364

Bioabsorbable fixation of scaphoid fractures and non-unions; analysis of early clinical outcomes.  

PubMed

The vast majority of devices used for internal fixation of the scaphoid are metallic. This two-center study aimed to report the results of scaphoid fixation using a cannulated, bioabsorbable device made from a hydroxyapatite and poly-L-lactide composite in 29 consecutive patients. Fixation was performed for seven acute fractures and twenty-two established non-unions. Union was achieved in 72.4% of patients. Six of the acute fractures and fifteen of the non-unions united successfully. Modified Mayo Wrist Score ranged between good to excellent in all patients who successfully united, whereas patients who failed to unite ranged between poor to excellent, with one poor and two moderate scores. No adverse biocompatibility reactions were seen. Two failures with broken screws were re-explored and one of these was thought to be due to screw mal-placement. The device used is an alternative to conventional metal implants and produces comparable union rates to metallic devices in the short term. PMID:24156576

Ya'ish, F; Bailey, C A; Kelly, C P; Craigen, M A

2013-01-01

365

Retro-odontoid cystic mass treated by laminectomy and C1-C2 fixation  

PubMed Central

Retro-odontoid cysts associated with chronic atlantoaxial subluxation are extremely rare. This article describes a case of retro-odontoid cystic mass associated with chronic atlantoaxial subluxation and its management with posterior C1 and partial C2 laminectomy and C1-C2 pedicle screw fixation without resection of the retro-odontoid cyst. A 64-year-old woman experienced a sudden onset of neck pain, hand and foot paresthesia. Atlantoaxial instability associated with a retro-odontoid cystic mass was found in the imaging. The patient underwent posterior C1 and partial C2 laminectomy and C1-C2 pedicle screws fixation without resection of the retro-odontoid cyst. During the 24 months followup period, the cyst disappeared completely and the patient remained symptom free and returned to independent daily living. These findings suggest that posterior laminectomy and fixation without resection of the retro-odontoid cyst is relatively simple and safe and the results are satisfactory. PMID:25404777

Lin, Dasheng; Ding, Zhenqi; Guo, Yanjie; Lian, Kejian

2014-01-01

366

Decreased Fixation Stability of the Preferred Retinal Location in Juvenile Macular Degeneration  

PubMed Central

Macular degeneration is the main cause for diminished visual acuity in the elderly. The juvenile form of macular degeneration has equally detrimental consequences on foveal vision. To compensate for loss of foveal vision most patients with macular degeneration adopt an eccentric preferred retinal location that takes over tasks normally performed by the healthy fovea. It is unclear however, whether the preferred retinal locus also develops properties typical for foveal vision. Here, we investigated whether the fixation characteristics of the preferred retinal locus resemble those of the healthy fovea. For this purpose, we used the fixation-offset paradigm and tracked eye-position using a high spatial and temporal resolution infrared eye-tracker. The fixation-offset paradigm measures release from fixation under different fixation conditions and has been shown useful to distinguish between foveal and non-foveal fixation. We measured eye-movements in nine healthy age-matched controls and five patients with juvenile macular degeneration. In addition, we performed a simulation with the same task in a group of five healthy controls. Our results show that the preferred retinal locus does not adopt a foveal type of fixation but instead drifts further away from its original fixation and has overall increased fixation instability. Furthermore, the fixation instability is most pronounced in low frequency eye-movements representing a slow drift from fixation. We argue that the increased fixation instability cannot be attributed to fixation under an unnatural angle. Instead, diminished visual acuity in the periphery causes reduced oculomotor control and results in increased fixation instability. PMID:24937090

Bethlehem, Richard A. I.; Dumoulin, Serge O.; Dalmaijer, Edwin S.; Smit, Miranda; Berendschot, Tos T. J. M.; Nijboer, Tanja C. W.; Van der Stigchel, Stefan

2014-01-01

367

Total hip arthroplasty with acetabular fixation: an unexpected complication.  

PubMed

The incidence of vascular injuries associated with total hip arthroplasty (THA) is low. However, several vascular structures are at risk of injury within the pelvis. These include the external iliac, femoral, and obturator vessels. Both reaming of the acetabulum and drilling of the acetabular screw holes may place these structures at risk. If left untreated, injuries to these vessels may be associated with severe morbidity and mortality. In this report, an acute vascular complication that had an unusual presentation is highlighted. A 72-year-old woman presented to the emergency department following a road traffic accident in which she sustained a combined fracture of the right acetabulum and femoral head. Her treatment involved a combination of THA and pelvic open reduction and internal fixation. The immediate perioperative recovery period was uncomplicated. However, the patient developed a deep venous thrombus in her right calf 7 days after surgery. Further investigation revealed a second thrombus, occluding the right common femoral vein. Surgical exploration revealed that a screw placed during the initial surgery was pressing against the vessel and occluding it. The discrepancy in incidence between the development of deep venous thrombosis and vascular compression or injury means that the association between the 2 events is unlikely to be made. The author highlights this unusual presentation to improve early recognition and prompt management of similar cases. The importance of adequate preoperative planning and intraoperative imaging with a C-arm is also stressed. PMID:24762850

Khoriati, Al-Achraf

2014-04-01

368

Comparative biomechanical study of the Ligament Plate® and other fixation devices in ACL reconstruction  

PubMed Central

The objective of this study was to evaluate and compare the biomechanical properties of the Ligament Plate® with other femoral fixation devices. The Ligament Plate® and three different femoral fixation devices were used in fixation of 60 porcine femora and harvested porcine tendons. For each fixation device, a porcine graft-tendon complex was used for the simple load-to-failure test and the load-to-failure test after a cyclic loading test, and the maximal failure load was measured. The amount of graft elongation and failure pattern after the cyclic loading test and load-to-failure test were evaluated. In the BioScrew® group, the mean maximal failure load in the load-to-failure test and load-to-failure test after a cyclic loading test was significantly lower and significant graft elongation was noted. There were no significant differences between the other groups. The Ligament Plate® provided adequate initial fixation power suitable for early rehabilitation. PMID:18923833

Sim, Jae Ang; Kwak, Ji Hoon; Yang, Sang Hoon

2008-01-01

369

Allograft anterior tibialis tendon with bioabsorbable interference screw fixation in anterior cruciate ligament reconstruction  

Microsoft Academic Search

For a variety of reasons, bone–patellar tendon–bone and Achilles tendon allografts have been used more commonly in anterior cruciate ligament reconstruction. Soft-tissue allografts used mainly are the semitendinosus, gracilis, and occasionally the quadriceps tendons. The anterior tibialis tendon is a thick, strong tendon that can be prepared with one doubling of the graft, has a large cross-sectional area, and has

David N. M. Caborn; Jeffrey B. Selby

2002-01-01

370

Posterior interbody fusion using laminectomy bone and transpedicular screw fixation in the treatment of lumbar spondylolisthesis  

Microsoft Academic Search

BACKGROUNDLaminectomy bone is used widely in posterolateral lumbar fusion, but not interbody fusion. No prospective evaluation of interbody fusion using bone grafts from the posterior neural arch in spondylolisthesis has been found in the literature. We prospectively studied series of patients operated on for lumbar spondylolisthesis to evaluate clinical improvement and bony fusion.METHODSForty-six patients were operated on for lumbar spondylolisthesis

György I Csécsei; Álmos P Klekner; József Dobai; Attila Lajgut; Judit Sikula

2000-01-01

371

Poly( l-lactide) bone plates and screws for internal fixation of mandibular swing osteotomies  

Microsoft Academic Search

This study evaluated bone healing after mandibular swing osteotomies fixed with biodegradable poly(l-lactide) (PLLA) bone plates in four patients. A step osteotomy treated with two PLLA bone plates (n=3), and a straight osteotomy treated with one PLLA bone plate (n=1) were performed. Bone healing was uneventful in all patients; only in the patient with the straight osteotomy was callus observed.

J. Tams; F. R. rozema; R. R. M. Bos; J. L. N. Roodenburg; P. G. J. Nikkels; A. Vermey

1996-01-01

372

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

373

Southwick Osteotomy Stabilised with External Fixator  

PubMed Central

ABSTRACT Introduction: Epiphysiolysis of the femoral head is the most common accident occurring towards the end of pre-puberty and puberty growth. Case report: The author describes the experience in the treatment of chronic epiphysiolysis in two patients treated by Southwick osteotomy. The site is accessed by way of a 15-cm long lateral skin incision and the trochanteric region is reached through the layers. The osteotomy angles prepared beforehand on a thin aluminium model are used to mark the Southwick osteotomy site on the anterior and lateral sides at the level of the lesser trochanter. Before performing the trochanteric osteotomy, two Mitkovi? convergent pins type M20 are applied distally and proximally, above the planned osteotomy site. A tenotomy of the iliopsas muscle is performed, and then the previously marked bone triangle is redissected up to three quarters of the width of the femur. The distal part of the femur is rotated inwards, so that the patella is turned towards the ceiling. The osteotomised fragments of the femur are adapted, repositioned and fixated by installing an external fixator on the previously placed pins. Two more pins are placed, one proximally and one distally, with a view to adequately stabilising the femur. The patient was mobile from day two after the surgery. If, after the surgery, the lead surgeon realises that there is a requirement to make a correction of 5, 10 and 15 degrees of the valgus, varus, anteversion or retroversion deformity, the correction shall be performed without surgically opening the patient, using the fixator pins. Conclusion: After performing a Southwick osteotomy it is easier to adapt, reposition and fixate the osteotomised fragments of the femur using a fixator type M20. Adequate stability allows regaining mobility quickly, which in turn is the best prevention of chondrolysis of the hip. It is possible to make post-operative valgus, varus, anteversion and retroversion corrections of 5, 10 and 15 degrees without performing a surgery. Once the osteotomy is healed, the fixator type M20 is removed without any additional surgery. PMID:25568571

Grubor, Predrag; Mitkovic, Milorad; Grubor, Milan

2014-01-01

374

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

375

Screw-Wire Osteo-Traction: An Adjunctive or Alternative Method of Anatomical Reduction of Multisegment Midfacial Fractures? A Description of Technique and Prospective Study of 40 Patients  

PubMed Central

Stable anatomical fracture reduction and segment control before miniplate fixation can be difficult to achieve in comminuted midfacial fractures. Fracture mobilization and reduction methods include Gillies elevation, malar hook, and Dingman elevators. No single method is used universally. Disadvantages include imprecise segment alignment and poor segment stability/control. We have employed screw-wire osteo-traction (SWOT) to address this problem. A literature review revealed two published reports. The aims were to evaluate the SWOT technique effectiveness as a fracture reduction method and to examine rates of revision fixation and plate removal. We recruited 40 consecutive patients requiring open reduction and internal fixation of multisegment midfacial fractures (2009–2012) and employed miniplate osteosynthesis in all patients. SWOT was used as a default reduction method in all patients. The rates of successful fracture reduction achieved by SWOT alone or in combination and of revision fixation and plate removal, were used as outcome indices of the reduction method effectiveness. The SWOT technique achieved satisfactory anatomical reduction in 27/40 patients when used alone. Other reduction methods were also used in 13/40 patients. No patient required revision fixation and three patients required late plate removal. SWOT can be used across the midface fracture pattern in conjunction with other methods or as a sole reduction method before miniplate fixation. PMID:24436763

O'Regan, Barry; Devine, Maria; Bhopal, Sats

2013-01-01

376

Screw-wire osteo-traction: an adjunctive or alternative method of anatomical reduction of multisegment midfacial fractures? A description of technique and prospective study of 40 patients.  

PubMed

Stable anatomical fracture reduction and segment control before miniplate fixation can be difficult to achieve in comminuted midfacial fractures. Fracture mobilization and reduction methods include Gillies elevation, malar hook, and Dingman elevators. No single method is used universally. Disadvantages include imprecise segment alignment and poor segment stability/control. We have employed screw-wire osteo-traction (SWOT) to address this problem. A literature review revealed two published reports. The aims were to evaluate the SWOT technique effectiveness as a fracture reduction method and to examine rates of revision fixation and plate removal. We recruited 40 consecutive patients requiring open reduction and internal fixation of multisegment midfacial fractures (2009-2012) and employed miniplate osteosynthesis in all patients. SWOT was used as a default reduction method in all patients. The rates of successful fracture reduction achieved by SWOT alone or in combination and of revision fixation and plate removal, were used as outcome indices of the reduction method effectiveness. The SWOT technique achieved satisfactory anatomical reduction in 27/40 patients when used alone. Other reduction methods were also used in 13/40 patients. No patient required revision fixation and three patients required late plate removal. SWOT can be used across the midface fracture pattern in conjunction with other methods or as a sole reduction method before miniplate fixation. PMID:24436763

O'Regan, Barry; Devine, Maria; Bhopal, Sats

2013-12-01

377

Relative Stability of Conventional and Locked Plating Fixation in a Model of the Osteoporotic Femoral Diaphysis  

PubMed Central

Background This study investigated the stiffness and strength of bridge plating with uni-cortical and bi-cortical locking plate constructs relative to a conventional, non-locked construct in the osteoporotic femoral diaphysis. Methods Four bridge plating configurations were applied to a validated model of the osteoporotic femoral diaphysis. A non-locked conventional configuration served as baseline. Locked configurations included bi-cortical locked plating, uni-cortical locked plating and mix-mode locked plating, which combined uni and bi-cortical locking screws. For all configurations, an 11-hole plate was applied with 4.5-mm screws placed in the 1st, 3rd, and 5th plate hole. Five specimens of each configuration were dynamically loaded until failure in torsion, axial compression, and bending to determine construct stiffness, strength and failure modes. Findings In torsion and bending, locked plating constructs provided a significantly lower stiffness and strength than the conventional construct. The uni-cortical locked construct was 69% weaker (P<0.001) in torsion than the conventional construct, but its torsional strength improved 73% (P<0.001) by adding one bi-cortical locked screw. In axial compression, construct stiffness varied by less than 10% between the four groups. However, the bi-cortical and mixed-mode locked constructs provided a significant increase in strength of 12% (P = 0.001) and 11% (P=0.002), respectively, compared to the conventional construct. Interpretations Locked plating in the osteoporotic diaphysis can improve fixation strength under axial loading, but may reduce fixation strength in bending and torsion compared to conventional plating. Adding one bi-cortical locked screw to an otherwise uni-cortical construct is recommended to improve torsional strength. PMID:19070409

Fitzpatrick, Dan C.; Doornink, Josef; Madey, Steven M.; Bottlang, Michael

2009-01-01

378

Transoral endoscopic-assisted management of subcondylar fractures in 17 patients: an alternative to open reduction with rigid internal fixation and closed reduction with maxillomandibular fixation.  

PubMed

The authors evaluate the results of transoral endoscopic-assisted open reduction and miniplate fixation of subcondylar fractures. Seventeen patients were treated from August 2005 to April 2007. Inclusion criteria were: adult patients, inability to achieve adequate occlusion with closed reduction, dislocation of the condylar fragment between 10 and 45 degrees , and 2-mm inter-fragment overlapping. Regular panoramic radiographs were taken postoperatively. Transbuccal incisions were used to place the screws for fixation in 15 patients. Pure intraoral access and angulated drills and screwdrivers were used in 2 patients. The condyle was placed into the condylar fossa in all cases. No damage to the facial nerve was observed. No visible scars were present. Mean surgical time was 80.36 minutes. Transitory hyposthesia was observed in 3 cases. Adequate reduction and consolidation of the fracture was achieved in 16 patients. No condylar reabsortion was present at the end of the follow-up period. The authors consider that transoral endoscopic-assisted open reduction constitutes a valid alternative to a transcutaneous approach for the reduction and fixation of subcondylar fractures in selected cases. It provides the benefits of open reduction and internal fixation without the potential complications. Advice is given on how to achieve adequate reduction and stability of the proximal fragment. PMID:19111444

González-García, R; Sanromán, J F; Goizueta-Adame, C; Rodríguez-Campo, F J; Cho-Lee, G Y

2009-01-01

379

Molybdenum limitation of asymbiotic nitrogen fixation in tropical forest soils  

NASA Astrophysics Data System (ADS)

Nitrogen fixation, the biological conversion of di-nitrogen to plant-available ammonium, is the primary natural input of nitrogen to ecosystems, and influences plant growth and carbon exchange at local to global scales. The role of this process in tropical forests is of particular concern, as these ecosystems harbour abundant nitrogen-fixing organisms and represent one third of terrestrial primary production. Here we show that the micronutrient molybdenum, a cofactor in the nitrogen-fixing enzyme nitrogenase, limits nitrogen fixation by free-living heterotrophic bacteria in soils of lowland Panamanian forests. We measured the fixation response to long-term nutrient manipulations in intact forests, and to short-term manipulations in soil microcosms. Nitrogen fixation increased sharply in treatments of molybdenum alone, in micronutrient treatments that included molybdenum by design and in treatments with commercial phosphorus fertilizer, in which molybdenum was a `hidden' contaminant. Fixation did not respond to additions of phosphorus that were not contaminated by molybdenum. Our findings show that molybdenum alone can limit asymbiotic nitrogen fixation in tropical forests and raise new questions about the role of molybdenum and phosphorus in the tropical nitrogen cycle. We suggest that molybdenum limitation may be common in highly weathered acidic soils, and may constrain the ability of some forests to acquire new nitrogen in response to CO2 fertilization.

Barron, Alexander R.; Wurzburger, Nina; Bellenger, Jean Phillipe; Wright, S. Joseph; Kraepiel, Anne M. L.; Hedin, Lars O.

2009-01-01

380

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

381

Evaluation of Bone Fixation Implants  

E-print Network

This research investigates the effects of the human body on the mechanical, chemical, and morphological properties of the surface of internal fixation devices. Stainless steel and titanium devices that had failed were provided from the Shandong...

Perkins, Luke 1990-

2012-12-10

382

Internal fixation of osteoporotic fractures.  

PubMed

Osteoporosis leads to bone fragility and increased risk of fracture. Despite advances in diagnosis and treatment, the prevalence continues to rise. Osteoporotic fracture treatment has a unique set of difficulties related to poor bone quality and traditional approaches, and implants may not perform well. Fixation failure and repeat surgery are poorly tolerated and highly undesirable in this patient population. This review illustrates the most recent updates in internal fixation, implant design, and surgical theory regarding treatment of patients with osteoporotic fractures. PMID:25424965

Rothberg, David L; Lee, Mark A

2015-02-01

383

Feasibility of purely endoscopic intramedullary fixation of mandibular condyle fractures.  

PubMed

The investigators of this study hypothesized that fractures of the mandibular condyle can be repaired using short-segment intramedullary implants and purely endoscopic surgical technique, using a basic science, human cadaver model in an academic center. Endoscopic instrumentation was used through a transoral mucosal incision to place intramedullary implants of 2 cm in length into osteotomized mandibular condyles. The surgical maneuvers that required to insert these implants, including condyle positioning, reaming, implant insertion, and seating of the mandibular ramus, are described herein. Primary outcome was considered as successful completion of the procedure. Ten cadaveric mandibular condyles were successfully repaired with rigid intramedullary internal fixation without the use of external incisions. Both insertion of a peg-type implant and screwing a threaded implant into the condylar head were possible. The inferior portion of the implant remained exposed, and the ramus of the mandible was manipulated into position on the implant using retraction at the sigmoid notch. The results of this study suggest that purely endoscopic repair of fractures of the mandibular condyle is possible by using short-segment intramedullary titanium implants and a transoral endoscopic approach without the need for facial incisions or punctures. The biomechanical advantages of these intramedullary implants, including improved strength and resistance to mechanical failure compared with miniplates, have been recently established. The combination of improved implant design and purely endoscopic technique may allow for improved fixation and reduced surgical- and implant-related morbidity in the treatment of condylar fractures. PMID:25534058

Frake, Paul C; Goodman, Joseph F; Joshi, Arjun S

2015-01-01

384

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

385

The history of internal fixation of proximal femur fractures Ernst Pohl-the genius behind.  

PubMed

The most frequently used implants for internal fixation of proximal femoral fractures are currently the dynamic hip screw and the intramedullary hip nail. However, little has been written about one of the pioneers in this field, a German genius, the designer Ernst Pohl (1876-1962). Without his involvement the concepts of intramedullary nailing coined by Gerhard Küntscher, Richard Maatz and other surgeons could hardly have been implemented. Through his achievements Pohl has rightly merited his pre-eminent position in the history of bone surgery. This article outlines the extraordinary contribution of Ernst Pohl to the development of skeletal surgery and radiology, as well as other medical disciplines. PMID:24687268

Bartoní?ek, Jan; Rammelt, Stefan

2014-11-01

386

Photoelastic stress analysis of internal fixation techniques for femur shaft crack  

NASA Astrophysics Data System (ADS)

In this paper, a photoelastic stress analysis is carried out for a cracked femur bone with compression plate fixation. A loading rig has been designed and manufactured to apply forces in the physical directions on the 2D modal of the femur bone based on a single-leg-stance. Three femur models made of photoelastic materials had been fabricated with three configurations and loaded. A recently developed three- load to phase shifting method is adopted to extract the full-field quantitative information from the fringe patterns of the loaded models. A comparison shows that the configuration where the screws point away from each other had the best effectiveness.

Liu, Tong; Chai, Gin B.; Asundi, Anand K.; Murugiah, Arumaaran

2001-06-01

387

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

388

A minimally invasive posterior lumbar interbody fusion using percutaneous long arm pedicle screw system for degenerative lumbar disease  

PubMed Central

The aim of this study is to evaluate the therapeutic efficacy of patients with lumbar degeneration and instability treated with percutaneous pedicle screw fixation and minimally invasive lumbar interbody fusion. Twenty-one patients were selected in our hospital from November, 2012 to March, 2013. The patients with an average age 55.62 years, including 8 vertebral spondylolisthesis, 4 lumbar intervertebral disc herniation, and 9 lumbar spinal canal stenosis cases. All the patients were managed to take the lumbar MRI and radiographs. The comparison of preoperative and postoperative (3 days, 2 weeks, 3 months) VAS and ODI score were analyzed. The results indicated that VAS scores were 7.14 ± 0.79 before operation, and 5.19 ± 0.81 in 3 days after operation, 4 ± 0.84 after 2 weeks, and 2.67 ± 0.66 after 3 months. The pain was relieved, and the postoperative VAS score was lower than that before treatment (P < 0.05). ODI score was 55.8 ± 11.4 before operation, 47.38 ± 9.38 after 3 days, 41.38 ± 8.09 after 2 weeks, 35.76 ± 4.50 after 3 months. ODI score was obviously decreased (P < 0.05). In conclusion, percutaneous pedicle screw fixation combined with minimally invasive interbody fusion is a safe, effective, feasible minimally invasive spine operation, with worthy for spreading.

He, Er-Xing; Cui, Ji-Hao; Yin, Zhi-Xun; Li, Chuang; Tang, Cheng; He, Yi-Qian; Liu, Cheng-Wei

2014-01-01

389

Multiobjective optimization design of spinal pedicle screws using neural networks and genetic algorithm: mathematical models and mechanical validation.  

PubMed

Short-segment instrumentation for spine fractures is threatened by relatively high failure rates. Failure of the spinal pedicle screws including breakage and loosening may jeopardize the fixation integrity and lead to treatment failure. Two important design objectives, bending strength and pullout strength, may conflict with each other and warrant a multiobjective optimization study. In the present study using the three-dimensional finite element (FE) analytical results based on an L25 orthogonal array, bending and pullout objective functions were developed by an artificial neural network (ANN) algorithm, and the trade-off solutions known as Pareto optima were explored by a genetic algorithm (GA). The results showed that the knee solutions of the Pareto fronts with both high bending and pullout strength ranged from 92% to 94% of their maxima, respectively. In mechanical validation, the results of mathematical analyses were closely related to those of experimental tests with a correlation coefficient of -0.91 for bending and 0.93 for pullout (P < 0.01 for both). The optimal design had significantly higher fatigue life (P < 0.01) and comparable pullout strength as compared with commercial screws. Multiobjective optimization study of spinal pedicle screws using the hybrid of ANN and GA could achieve an ideal with high bending and pullout performances simultaneously. PMID:23983810

Amaritsakul, Yongyut; Chao, Ching-Kong; Lin, Jinn

2013-01-01

390

What Is the Relevance of the Tip-Apex Distance as a Predictor of Lag Screw Cut-Out?  

PubMed Central

Using a simple mathematical formulation, the relationship between the position of the lag screw tip (relevant to both intramedullary and extramedullary devices) and the concept of tip-apex distance (TAD) was derived. TAD is widely used in operating theaters as a surgical guideline in relation to the fixation of trochanteric fractures, and in clinical studies as a predictor of lag screw cut-out. In order to visualize better this concept, the locus of points having the same TAD was plotted and the dependence of TAD on the location of the lag screw tip was also reported. It was shown that TAD should be adjusted for the size of the femoral head (a variable which varies a lot according to the sex of the patient) while no correlation was found between TAD and bone morphometry indices obtained from micro-CT data (BV/TV and Tb.Th). Therefore, these results seem to suggest that TAD lacks mechanical justification and that predictors which are based on mechanical properties, such as bone density, should be investigated further. PMID:24015184

Goffin, Jérôme M.; Jenkins, Paul J.; Ramaesh, Rishikesan; Pankaj, Pankaj; Simpson, A. Hamish

2013-01-01

391

Perspectives on Marine Nitrogen Fixation  

NASA Astrophysics Data System (ADS)

The importance of nitrogen fixation in ocean biogeochemistry has only recently come to be fully appreciated. As biological nitrogen fixation was being uncovered in terrestrial ecosystems (late 1800s), some ocean surveys were mapping the large-scale distribution of important planktonic diazotrophs, such as the cyanobacterium Trichodesmium, unaware of their functional significance. Early marine N biogeochemists speculated that nitrogen fixation was largely confined to the terrestrial realm, with combined nitrogen being transferred to the ocean from land, there to be taken up by phytoplankton or denitrified. Later, A. Redfield invoked nitrogen fixation as a mechanism to prevent N limitation in the sea. Systematic studies of nitrogen fixation started rolling in the 1960s with the introduction of enriched 15N tracer methodology by R. Dugdale and his associates and, subsequently, with the introduction of a simple field assay for this activity. While results from field studies in the 1980s, largely limited to mid-latitudes and marginal tropical and subtropical seas, also indicated a relatively limited role for nitrogen fixation, several lines of geochemical evidence emerged in the late 1990s which suggested otherwise. This prompted a resurgence in field efforts examining this process which in turn provided direct evidence to support the biogeochemical significance of nitrogen fixation in the oligotrophic ocean. Research in this area continues to move rapidly. The infusion of molecular biological methods also provided new tools to explore and appreciate the real diversity of marine diazotrophs. Many current biogeochemical models incorporate nitrogen fixation as an explicit function providing input of new reactive nitrogen into marine ecosystems. However, there are still major puzzles to be solved. Two current and related conundrums are whether denitrification and nitrogen fixation are near balance in the current ocean, and how closely they are coupled. Recent experimental and modeling results suggests diazotrophs, which are not limited by nitrogen availability, may be limited by other macro and micronutrient factors in different ocean basins. Finally, atmospheric N deposition to the ocean is rapidly accelerating and will soon exceed current estimates of oceanic nitrogen fixation.

Capone, D. G.

2008-05-01

392

Juvenile idiopathic scoliosis treated with posterior arthrodesis and segmental pedicle screw instrumentation before the age of 9 years: a 5-year follow-up  

PubMed Central

Study design Retrospective study. Objective To evaluate the radiological results of fusion with segmental pedicle screw fixation in juvenile idiopathic scoliosis with a minimum 5-year follow-up. Summary of background data Progression of spinal deformity after posterior instrumentation and fusion in immature patients has been reported by several authors. Segmental pedicle screw fixation has been shown to be effective in controlling both coronal and sagittal plane deformities. However, there is no long term study of fusion with segmental pedicle screw fixation in these group of patients. Methods Seven patients with juvenile idiopathic scoliosis treated by segmental pedicle screw fixation and fusion were analyzed. The average age of the patients was 7.4 years (range 5–9 years) at the time of the operation. All the patients were followed up 5 years or more (range 5–8 years) and were all Risser V at the most recent follow up. Three dimensional reconstruction of the radiographs was obtained and 3DStudio Max software was used for combining, evaluating and modifying the technical data derived from both 2d and 3d scan data. Results The preoperative thoracic curve of 56 ± 15° was corrected to 24 ± 17° (57% correction) at the latest follow-up. The lumbar curve of 43 ± 14° was corrected to 23 ± 6° (46% correction) at the latest follow-up. The preoperative thoracic kyphosis of 37 ± 13° and the lumbar lordosis of 33 ± 13° were changed to 27 ± 13° and 42 ± 21°, respectively at the latest follow-up. None of the patients showed coronal decompensation at the latest follow-up. Four patients had no evidence of crankshaft phenomenon. In two patients slight increase in Cobb angle at the instrumented segments with a significant increase in AVR suggesting crankshaft phenomenon was seen. One patient had a curve increase in both instrumented and non instrumented segments due to incorrect strategy. Conclusion In juvenile idiopathic curves of Risser 0 patients with open triradiate cartilages, routine combined anterior fusion to prevent crankshaft may not be warranted by posterior segmental pedicle screw instrumentation. PMID:19123957

?arlak, Ahmet Y?lmaz; Atmaca, Halil; Buluç, Levent; Tosun, Bilgehan; Musao?lu, Resul

2009-01-01

393

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

394

Effects of nonlinearity in the materials used for the semi-rigid pedicle screw systems on biomechanical behaviors of the lumbar spine after surgery.  

PubMed

Recently, various types of semi-rigid pedicle screw fixation systems have been developed for the surgical treatment of the lumbar spine. They were introduced to address the adverse issues commonly found in traditional rigid spinal fusion--abnormally large motion at the adjacent level and subsequent degeneration. The semi-rigid system uses more compliant materials (nitinol or polymers) and/or changes in rod design (coiled or twisted rods) as compared to the conventional rigid straight rods made of Ti alloys (E = 114 GPa, ? = 0.32). However, biomechanical studies on the semi-rigid pedicle screw systems were usually limited to linear modeling of the implant and anatomic elements, which may not be capable of reflecting realistic post-operative motions of the spine. In this study, we evaluated the effects of nonlinearity in materials used for semi-rigid pedicle screw fixation systems to evaluate the changes in biomechanical behaviors using finite element analysis. Changes in range of motion (ROM) and center of rotation (COR) were assessed at the operated and adjacent levels. Actual load-displacement results of the semi-rigid rod from mechanical test were carried out to reflect the nonlinearity of the implant. In addition, nonlinear material properties of various spinal ligaments studies were used for the finite element modeling. The post-operative models were constructed by modifying the previously validated intact model of the L1-S1 spine. Eight different post-operative models were made to address the effects of nonlinearity-with a traditional stiffness modulus rod (with linear ligaments, case 1; with nonlinear ligaments, case 5), with a rigid rod (with linear ligaments, case 2; with nonlinear ligaments, case 6), with a soft rod (with linear ligaments, case 3; with nonlinear ligaments, case 7), and with a nonlinear rod (with linear ligaments, case 4; with nonlinear ligaments, case 8). To simulate the load on the lumbar spine in a neutral posture, follower load (400 N) was applied and then the hybrid loading condition was applied to measure the ROM and COR in the sagittal plane. The more the nonlinearity was included in the model the closer the motion behavior of the device was to that of the intact spine. Furthermore, our results showed that the nonlinearity of the semi-rigid rod was a more sensitive factor than the nonlinearity of the spinal ligaments on biomechanical behavior of the lumbar spine after surgery. Therefore, for better understanding of the surgical effectiveness of the spinal device, more realistic material properties such as nonlinearity of the device and anatomic elements should be considered. In particular, the nonlinear properties of the semi-rigid rod were considered more than the nonlinearity of spinal ligaments. PMID:21849724

Kim, Hyun; Lim, Do-Hyung; Oh, Hyun-Ju; Lee, Kwon-Yong; Lee, Sung-Jae

2011-10-01

395

Design of Fracture Fixation Plate for Necessary and Sufficient Bone Stress Shielding  

NASA Astrophysics Data System (ADS)

The objective of treating the fractured bone is to achieve painless functioning of the bone and undisturbed healing at the fracture. Internal fixation by stiff bone-plate is one of the standard methods to achieve these objectives. Recently, there is considerable interest in the usage of compliant plates to enhance bone healing with reduced stress shielding. Herein, first an analytical solution is developed to determine screw forces in the bone-plate assembly that conforms the plate and the bone under bending load. Based on the analytical calculations, an optimal fixator plate selection criterion for necessary and sufficient stress shielding is proposed. Second, effectiveness of employing a non-homogeneous stiffness graded (SG) plate rather than a homogeneous stainless steel (SS) plate for stress shielding is investigated using a finite element method. It is found that stress shielding on bone by SG plate is less compared to SS plate.

Ramakrishna, Kotlanka; Sridhar, Idapalapati; Sivashanker, Sathiamoorthy; Khong, Kok Sun; Ghista, Dhanjoo N.

396

Mandibular osteotomies for tumor extirpation: the advantages of rigid fixation.  

PubMed

Adequate exposure of intraoral tumors occupying the posterior oral cavity, base of tongue, tonsil, and superior hypopharynx for wide-field primary surgical resection is critical to precise tumor ablation. The exposure resulting from a mandibular osteotomy has greatly assisted the tumor ablation of these areas. This procedure has also been beneficial in providing exposure to the anterior skull base, pterygomaxillary, and infratemporal space, clivus, and nasopharynx. In evaluating various osteotomy sites and methods of fixation, we reviewed 26 patients treated for benign or malignant neoplasia of the head and neck requiring mandibulotomy. The osteotomy complication rate was 2 (29%) of 7 for wire osteosynthesis and 1 (5.3%) of 19 for plate osteosynthesis. All patients with osteotomy complications had received preoperative radiation therapy. The one complication in the plated group was associated with a lateral stairstep osteotomy and two screws on either side of the osteotomy. This study suggests advantages of absolute rigid internal fixation of mandibular osteotomies used for tumor ablation. It is also concluded that a midline osteotomy reapproximated with rigid internal fixation has the benefits of 1. primary bone healing by means of plating counteracting the balanced forces acting on the symphysis; 2. improved reapproximation with minimal bony loss, improving occlusion; 3. decreased incidence of osteoradionecrosis as the symphysis lies outside the usual radiation ports; 4. preservation of the neurovascular bundle; and 5. maintenance of osteotomy-site immobility in an infected field. This review helped identify surgical techniques that decrease the complications that are commonly associated with mandibular osteotomies for precise tumor ablation. PMID:1731161

Sullivan, P K; Fabian, R; Driscoll, D

1992-01-01

397

The Distribution of Fixation Durations during Reading: Effects of Stimulus Quality  

ERIC Educational Resources Information Center

Participants' eye movements were recorded as they read single sentences presented normally, presented entirely in faint text, or presented normally except for a single faint word. Fixations were longer when the entire sentence was faint than when the sentence was presented normally. In addition, fixations were much longer on a single faint word…

White, Sarah J.; Staub, Adrian

2012-01-01

398

The contribution of associative and symbiotic nitrogen fixation to the nitrogen nutrition of non-legumes  

Microsoft Academic Search

During the past 10 years estimates of N2 fixation associated with sugar cane, forage grasses, cereals and actinorhizal plants grown in soil with and without addition of inoculum have been obtained using the 15N isotope dilution technique. These experiments are reviewed in this paper with the aim of determining the proportional and absolute contribution of N2 fixation to the N

P. M. Chalk

1991-01-01

399

Comparison of Routine Fixation of Tissues with Rapid Tissue Fixation  

PubMed Central

Introduction: Conventional formalin-fixed, paraffin-embedded tissue provides superior cellular morphology and long-term storage. Problems with formalin fixation comprise delay of fixation and variations in the duration of fixation. Microwave assisted tissue fixation removes the use of noxious and potentially toxic formalin that decreases the turnaround time and creates a personnel friendly workflow. Material and Methods: The present study was conducted over a period of two years. One hundred and forty paired tissue sections were taken including both neoplastic and non-neoplastic tissues. One of the paired tissues was fixed in formalin and the other was fixed by using microwave irradiation in phosphate buffered saline. Both were then processed by conventional method. Each slide was examined and rated for the adequacy of fixation by two pathologists in a blinded fashion using 7 parameters: Cellular outline, cytoplasmic detail, nuclear detail, erythrocyte integrity, lymphocyte appearance, overall morphology and overall staining. Results: Statistical analysis showed that sections obtained from microwave fixed tissues were comparable to that of routinely fixed tissue. The p-values of all parameters were not significant except for the overall morphology for which p-value was significant owing to loss of tissue in some cases. Conclusion: Microwave irradiation substantially shortened the time from specimen reception to diagnosis (turnaround time) and allowed same-day tissue processing and diagnosis of specimens without compromising the overall quality of the histologic section. PMID:24551633

Tripathi, Meenakshi; Bansal, Rani; Gupta, Mamta; Bharat, Vinay

2013-01-01

400

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