Interfragmentary Lag Screw Research Articles

Comparison of 2 different fixation techniques of comminuted acetabular quadrilateral surface fractures using square bracket-shaped tubular plate or interfragmentary screws in addition to supra/infrapectineal plate fixation: An observational study.

The management of comminuted quadrilateral fractures remains challenging, and treatment options are constantly evolving. The purpose of the present study was to examine the outcomes of 2 different fixation techniques in the management of comminuted quadrilateral fractures. Twenty-two patients with comminuted quadrilateral acetabular fractures were surgically treated with interfragmentary lag screw (group 1) and square bracket-shaped tubular (SBST) plate technique (group 2), in addition to suprapectineal and infrapectineal pelvic reconstruction plate fixation between January 2016 and July 2019 at our clinic. 2 years follow-up control data of each group were compared in terms of radiological and functional results, and complications. According to the functional score comparison, the mean Merle d'Aubigne Postel scoring system (MAP) score was 15.2/15.6 (P = .632), and the mean Harris hip scoring (HHS) system score was 74.65/77.3 (P = .664) in groups 1 and 2, respectively. Radiological comparison was performed according to matta radiological criteria (MRC), and 2 excellent, 6 good, 2 poor, 4 excellent, 4 good, and 4 poor radiological results were observed in groups 1 and 2, respectively. intraarticular screw penetration was detected in 3 patients in group 1, while there was no articular implant penetration in group 2 (P = .001). We believe that satisfactory results can be obtained with the SBST plate technique, offering functional and clinical outcomes that are similar to those of the interfragmentary screw technique. The SBST plate technique is superior in terms of avoiding intraarticular screw penetration and related revision surgery.

Screw-only fibular construct for Weber B ankle fractures: A retrospective clinical and cost comparison to assess feasibility for resource-limited settings

IntroductionAnkle fractures are one of the most common injuries sustained worldwide, with the majority being isolated lateral malleolus fractures. The majority of the world's population live in Low and Middle Income Countries (LMIC), where implant cost may limit surgical treatment of ankle fractures. We investigate if Weber B ankle fractures could be effectively treated with a lower-cost technique using two screws between the fibula and the tibia to neutralize an interfragmentary lag screw. MethodsAfter IRB approval, consecutive patients from January 1, 2020 to December 31, 2020 with Weber-B ankle fractures were treated using AO technique (AOT) with plate osteosynthesis neutralizing an interfragmentary screw. Syndesmotic injuries, as well as injuries to the medial malleolus or foot were treated according to the surgeon's preferences. From January 1, 2021 to December 31, 2021 these injuries were treated with a screw-only technique (SOT) with two fibula pro tibia screws to neutralize an interfragmentary screw. Patient demographics including age, sex, BMI, smoking status, associated rheumatoid arthritis, and associated diabetes mellitus were recorded. The primary outcome variable was a stable radiographic mortise at six weeks post-surgery, secondary outcome variables included clinical union, infection, hardware removal, and implant cost for lateral malleolar fixation charged to the hospital. ResultsSeventeen AOT and 10 SOT constructs were included. Demographic characteristics were similar between groups. All fractures maintained a stable mortise with clinical union at 6 weeks without infection. There was a statistically significant difference in hardware removal (17.6% AOT, 50% SOT, p = 0.012). The average implant cost to the hospital of the lateral malleolar fixation was significantly less in the SOT group ($592 (SD $229)), compared to the AOT group ($1,949.97 (SD $562)), (p < 0.0001). ConclusionWe introduce proof of concept of a novel lower-cost fixation strategy for Weber B ankle fractures that maintained a stable mortise with clinical union at six weeks post-surgery. However, there was a significantly higher rate of hardware removal following fixation with a screw-only construct.

An Oblique Trans-Syndesmotic Screw to Augment Fixation of Distal Fibula Fractures: A Technique Guide

Category:Trauma; AnkleIntroduction/Purpose:A subset of patients with low, transverse fractures of the lateral malleolus are at increased risk of malreduction and late loss of reduction. In patients with poor bone quality and transverse or short oblique fractures at or distal to the tibiotalar joint, distal fixation is often inadequate with a single interfragmentary lag screw. Furthermore, these fractures are susceptible to malreduction by pre-contoured locking plates. To address this, a technique was developed to augment fixation of the distal fragment and decrease the likelihood of loss of reduction. The senior author's technique for this procedure, as well as indications for the technique and a few representative cases, are provided.Methods:This technique involves placement of an oblique tricortical or quadricortical screw from the distal fibula into the tibia in an distal-lateral to proximal-medial direction. The screw is placed either outside of or through the distal-most hole of a one-third tubular plate placed in a neutralization position. The screw trajectory is similar to that of a typical syndesmosis screw in the sagittal plane but is aimed proximally rather than parallel to the tibial plafond. The screw enters the tibia at Chaput's tubercle, just lateral to the joint. The indications for this technique are transverse and short oblique Danis-Weber B distal fibular fractures in which there is inadequate purchase between the plate and the distal fragment. While the purpose of this screw is not to stabilize the syndesmosis, it can be used with other augmentation techniques, such as trans-syndesmotic screws, in high-risk patients with osteoporosis and/or neuropathy.Results:This technique has been used for many years by the senior author. There have been no implant failures (e.g. broken screws) or major complications associated with this technique. Three representative cases demonstrate appropriate indications and outcomes for this technique. These include patients with significant neuropathy or osteoporosis who present with a particularly troublesome fracture pattern (transverse fibular fracture at or below the level of the tibiotalar joint). This screw, along with any other syndesmotic screws, is removed at 3-4 months according to the senior author's protocol.Conclusion:A distal oblique trans-syndesmotic screw can be used to supplement current fibular fracture fixation constructs. It is easy to place under fluoroscopic guidance and generally is removed after fracture union, similar to standard syndesmosis screws. The use of this screw helps prevent the malreduction that can potentially occur when treating transverse or short-oblique Weber B distal fibular fractures with a locking plate. In our series of patients at a large urban tertiary referral center, this technique has produced good outcomes with no reportable complications.

Three-Dimensional Anatomically Pre-Contoured Locking Plate for Isolated Weber B Type Fracture.

We aimed to evaluate the functional and radiographic outcomes of a three-dimensionally (3D) pre-contoured lateral locking plate fixation for isolated Weber B type fractures and to evaluate the necessity of an interfragmentary lag screw in the use of the plate. Patients who underwent surgery for isolated Weber B type fracture were divided into two groups: 41 patients treated with the 3D plate and lag screw (Group A) and 31 patients treated with the 3D plate only (Group B). The included patients were evaluated regarding the functional and radiographic outcomes. According to the McLennan and Ungersma criteria, the majority of patients showed good or fair outcomes in both groups. Comparing the two groups, Group B showed better functional outcomes (p < 0.0046), while no difference between the two groups was found in terms of the radiographic outcomes (p = 0.143). The operation time was significantly shorter in Group B (p < 0.001) and the time to bony union was within 14 months in all patients with no significant difference between the two groups (p = 0.0821). No postoperative complication was observed in both groups. In conclusion, the use of a 3D pre-contoured lateral locking plate fixation for isolated Weber B type fractures demonstrated satisfactory functional and radiographic outcomes, regardless of lag screw insertion.

Interfragmentary lag screw and locking plate combination in simple distal femoral fractures: A finite element analysis.

The aim of this study was to evaluate the strength of the locking plate and lag screw construct that is applied in two different working lengths on the simple distal femur fracture model with a finite element analysis (FEA) method. From the computerized tomography scan data of a 60-year-old healthy male, the AO/OTA 33A1-type fracture model was simulated; the fracture gap was stabilized with the models of locking plate construct with (groups C and D) or without an interfragmentary lag screw (groups A and B). Furthermore, 102-mm plate (groups A and C) and 82-mm plate working lengths (groups B and D) were tested using FEA. Two loading conditions (axial compression and torsion) were applied at the center of the femoral head. Construct stiffness, interfragmentary micromotion, and the peak von Mises stress (VMS) on the plate were assessed. Group D provided the highest axial stiffness (1347 N/mm), and group A was the weakest (439 N/mm). With the lag screw, shear micromotion remained generally low compared with that without the screw for all axial and torsional load levels and for both plate working lengths, i.e., 0.23 mm with lag screw versus 0.43 mm without lag screw (102 mm working length, 700 N). The percentage decreases of shear micromotion under axial (350/700/1400 N) and torsional loads for the 102-mm working length were >22% and 73%, respectively; while those for the 82-mm working length were >28% and 33%, respectively. The reduction of axial micromotion was observed with the lag screw for all axial load levels as well as for both plate working lengths, i.e., 0.33 mm with lag screw versus 0.87 mm without lag screw (102-mm working length, 700 N). The percentage decreases of axial micromotion under axial loading (350/700/1400 N) for 102 mm and 82 mm working lengths were >42% and 50%, respectively. The peak VMS on the plate stayed generally low with lag screw compared with without lag screw throughout all tested load levels, as well as for both plate working lengths, i.e., 124.26 MPa versus 244.39 MPa (102 mm working length, 700 N). The percentage decreases of the peak VMS under axial (350/700/1400 N) and torsional loads for the 102-mm working length were >40% and 69%, respectively, while those for the 82-mm working length were >47% and 61%, respectively. The current FEA concludes that in a simple distal femur fracture, adding a lag screw to a locking plate construct provides better torsional stability with a 102-mm plate working length and better axial stability with a 82-mm plate working length. Additionally, the strength of the materials is increased and implant failure can be minimized by using this technique.

Is initial interfragmentary compression made to last? An ovine bone in vitro study.

Interfragmentary compression, a major principle of fracture treatment, is clinically not quantified and might be lost quickly even without functional loads. We designed an experimental study hypothesizing that (1) compression can be controlled using either lag screw or compression plate, and expecting similar initial compression, (2) loss of interfragmentary compression through relaxation within one hour is reduced with neutralization locking plate next to lag screw compared to compression plate. Twelve ovine femora (N=6) and humeri (N=6) were assigned into groups: Group 1 received a 45° oblique osteotomy at mid-diaphysis and was fixated using a 3.5mm interfragmentary lag screw and locking compression plate (3.5mm LCP, DePuy Synthes) as neutralization plate. Group 2 received a transverse osteotomy and was fixated with dynamic compression using compression plate (LCP). Interfragmentary pressure and relative bone fragment displacements were recorded over one hour. Median loss of compression over one hour time (relaxation) were 0.52% in Group 1, and 0.17% in Group 2 (p>0.05). Median rotational displacements amounted to 0.46° for Group 1, and 0.31° for Group 2, and axial displacement to a median of -20μm in Group 1 and 25μm in Group 2. Ovine bone interfragmentary stress relaxation maintains compression over the first hour for lag screw with neutralization plate for an oblique fracture line or compression plate for a transverse fracture line. Measured compression forces around 100N could be overcome by physiological tension loading in bending or torsion, necessitating for instance tension band plating, additional lag screws or absolutive stability.

The Lapidus Arthrodesis: Examining the Effect of the Metatarsal Base Transfixion Screw

The modified Lapidus bunionectomy is a useful and highly powerful procedure for correcting hallux abducto valgus. Traditionally reserved for “severe” deformities, this procedure has seen a recent resurgence in the podiatric community for its unique ability to achieve tri-planar correction of this challenging deformity. Although this procedure has been extensively studied in both biomechanical labs and the clinical arenas, no clear consensus has been achieved regarding optimal fixation for this thought-provoking procedure. The current study examined the differences in strength between commercially available 5-hole locking plates with interfragmentary compression vs a crossed-screw with a third “transfixation” screw construct in a controlled setting. Ten fresh-frozen cadaveric match pair limbs (20 total limbs) were used to complete this study. Ten limbs were randomly assigned to a 3-screw construct. The other 10 contralateral limbs were assigned to a commercially available 5-hole locking plate (5 stainless steel and 5 titanium alloy) with an interfragmentary lag screw construct. The first rays were then isolated and potted into a 4-point bending device. The specimens were loaded to failure in a servohydraulic load frame at a controlled rate. Failure was defined as catastrophic or 3 mm of plantar gapping at the arthrodesis site. The mean maximal load to failure was 310.9 ± 109.4 N for the 3-screw construct. The mean maximal load to failure for the locking plate constructs was 264.1 ± 100.9 N. This difference was not statistically significant (p = .328). These results suggest that a 3-screw construct for Lapidus arthrodesis is as strong as commercially available locking plate constructs.

The Fibular Intramedullary Nail Versus Locking Plate and Lag Screw Fixation in the Management of Unstable Elderly Ankle Fractures: A Cadaveric Biomechanical Comparison.

To compare the biomechanical failure properties of the fibular intramedullary nail with locking plate and lag screw fixation in the management of unstable elderly distal fibular fractures. Twelve fresh-frozen cadaveric lower limbs (6 matched-pairs) were studied. A simulated OTA/AO 44-B fracture was created, then randomly allocated within each pair to intramedullary nail or locking plate fixation supplemented with an interfragmentary lag screw. The limbs were secured with the foot rigidly held in 20 degrees of supination, loaded to 700N and subjected to progressive external rotation until failure. The mean specimen age was 86.5 years (61-97). Mean torque to failure was greater in the intramedullary nail group, but did not reach statistical significance (23.5 N·m vs. 21.6 N·m; P = 0.463). The nail failed at a significantly greater angle of rotation compared with plate fixation (66.5 degrees vs. 53.3 degrees; P = 0.046). There was no significant difference between the groups with respect to construct stiffness (P = 0.673) or energy absorbed (P = 0.075). The locking plate specimens failed through plate and screw construct pull off at the implant-bone interface. In contrast, the intramedullary nail specimens failed at the lateral ligament complex, whereas the fracture-implant construct remained intact. Intramedullary nailing and locking plate fixation have similar biomechanical characteristics when tested to failure. The benefits of the minimally invasive surgery offered by the intramedullary nail make it an attractive implant in the management of these patients.

Necessity of Interfragmentary Lag Screws in Precontoured Lateral Locking Plate Fixation for Supination-External Rotation Lateral Malleolar Fractures

Interfragmentary lag screws, protected by a plate, have been applied for many years in the treatment of supination-external rotation (SER) ankle fractures. Recently, similar biomechanical stability was found between fixation completed with a plate and lag screw and a plate alone. The aim of this study was to determine whether interfragmentary lag screws are necessary during precontoured lateral locking plate fixation for SER lateral malleolar fractures. A prospective randomized controlled trial of 76 patients with unilateral Lauge-Hansen SER lateral malleolar fractures was conducted. The patients were randomly treated either with or without the use of interfragmentary lag screws with precontoured lateral locking plate fixation. Clinical outcomes were assessed using the Olerud-Molander Ankle Score and a visual analog scale for pain. Radiologic outcomes were assessed based on the Kellgren and Lawrence scale score, incongruity of the ankle joint, and type of fracture healing. Sixty-nine patients completed 12 months of follow-up. There was no significant difference between the 2 groups with regard to clinical outcomes at 3 and 12 months after surgery and radiologic outcomes at 12 months after surgery. All patients in both groups achieved primary bone healing. The results of this study suggest that with precontoured lateral locking plate fixation, the use of interfragmentary lag screw is not essential in the treatment SER lateral malleolar fractures. Level I, prospective randomized study.

Provisional Minifragment Plate Fixation of Acetabular Fractures-A Technical Trick.

Acetabular fractures may not always be amenable to classic clamp-assisted reductions and interfragmentary lag screw fixation. The routine clamp-assisted reductions with limited osseous territory availability can inhibit typical 3.5-mm reconstruction plate application. Provisional minifragment plate fixation of these fracture patterns with subsequent clamp removal allows for definitive plate application. The provisional minifragment plates may also be retained to theoretically augment fixation. The authors present a step-by-step technique and clinical series of 57 patients demonstrating provisional minifragment fixation of elementary (n = 8) and associated (n = 49) acetabular fractures.

Locking plate constructs benefit from interfragmentary lag screw fixation with decreased shear movements and more predictable fracture gap motion in simple fracture patterns

BackgroundA mechanical characterisation of lag screw fixation plus locking plate – although clinically widely used as either “mixed fixation concept” or absolutely stable fixation – is so far missing. This study aimed to evaluate the influence of an interfragmentary lag screw on the resulting motion at the fracture site of locking plate constructs using a simple fracture at the distal femur. MethodsHuman cadaver femora were in vitro loaded in torsion and axial bending-compression with and without lag screw fixation next to a locking plate fixation. In addition, two plate working lengths were tested. Interfragmentary movement was measured optically. FindingsAxial interfragmentary movement is reduced with lag screw (102 mm plate working length, 1000 N, mean): 0.28 mm versus 0.82 mm. With lag screw, the fracture gap stays closed with mean normal interfragmentary movement ≤0.03 mm. Fracture gap tends to open without lag screw: normal interfragmentary movement up to −0.29 mm. Reduction of shear interfragmentary movement was observed throughout all tested loads and groups. Mean true shear remains generally low with lag screw (≤0.42 mm) compared to without lag screw (≤1.46 mm). We also found that interfragmentary movement variance decreases with lag screw, especially for longer plate working length. InterpretationAn interfragmentary lag screw next to locking bridge plating reduces fragment motion in vitro for a simple fracture pattern and provides a sufficient tool to decrease detrimental shear movements. Prospective clinical trials with interfragmentary lag screw fixation should prove these findings in wide clinical use to treat simple fracture patterns.

Posterior wall acetabular fracture fixation: A mechanical analysis of fixation methods.

Stable, anatomical fixation of acetabular fractures gives the best chance of successful outcome, while penetration of the acetabular articular surface with screws is associated with poor outcomes. Spring plates are an alternative to interfragmentary lag screws when penetration is a concern. A mechanical study comparing fracture stability and construct stiffness of three fixation methods for posterior wall acetabular fractures with transverse comminutions was performed. The three fixation methods tested were a posterior wall rim plate, a posterior wall buttress plate with separate lag screws and a posterior wall plate with two spring plates. Nine samples were tested, three for each fixation method. Two-dimensional motion analysis was used to measure fracture fragment displacement and construct stiffness. After two 6000 cycle-loading protocols, to a maximum 1.5 kN, the mean fracture displacement was 0.154 mm for the rim plate model, 0.326 mm for the buttress plate and 0.254 mm for the spring plate model. Mean maximum displacement was significantly less for the rim plate fixation than the buttress plate (p = 0.015) and spring plate fixation (p = 0.02). The rim plate was the stiffest construct 10,962 N/mm, followed by the spring plate model 5637 N/mm and the buttress plate model 4882 N/mm. Based on data obtained in this study, where possible a rim plate with interfragmentary lag screws should be used for isolated posterior wall fractures as this is the stiffest and most stable construct. When this method is not possible, spring plate fixation is a safe and a superior alternative to a posterior buttress plate method.

Long-term outcome of first metatarsophalangeal joint fusion in the treatment of severe hallux rigidus.

This study was aimed to study the arthrodesis of the first metatarsophalangeal joint using an oblique interfragmentary lag screw and dorsal plate as an effective option for the treatment of hallux rigidus. Few researchers have studied the outcome of this surgical method over a long follow-up period. We performed a retrospective review of 60 patients status post arthrodesis of the first metatarsophalangeal joint. The mean age was 68.5years and average follow-up lasted for 47.3months. Patients' satisfaction and functional outcomes were evaluated with the American Orthopaedic Foot and Ankle Society Hallux Metatarsophalangeal-Interphalangeal Scale, the foot and ankle questionnaire, the Functional Foot Index, and dynamic pedobarography. Fusion rate of 93.3% was recorded; 6.7% of the cases ended up with a painless pseudarthrosis and required no additional surgery. Pedobarographic measurements demonstrated first ray weight bearing function restoration. More physiological foot plantar pressure patterns were observed. Concerning the postoperative outcomes, 71.7% of the patients were very satisfied and 18.3% were satisfied. The American Orthopaedic Foot and Ankle Society Hallux Metatarsophalangeal-Interphalangeal Scale increased post-operatively from 40.9 to 79.3. The arthrodesis of the metatarsophalangeal joint using transarticular screw and dorsal nonlocked plate is an effective method for the treatment of severe hallux rigidus with fair patient satisfaction rate and functional outcome.

Precontoured plate fixation with interfragmentary lag screw use in a middle third clavicle fracture fixation.

Middle third clavicle fractures are common injuries that need surgical fixation in a certain subset of patients. The use of pre-contoured clavicle plates facilitates intra-operative fixation and can reduce soft tissue irritation and hardware removal rates. Lag screw fixation is a well-established technique for the treatment of oblique fractures. Empirical application of this method in clavicle fracture fixation and clavicle non-union treatment has been reported previously. A recent biomechanical study supports the use of a lag screw technique in clavicle fracture fixation when possible. We report a 46 year old patient with a mid-shaft right clavicle fracture who was treated with this technique, which resulted in an excellent clinical outcome.

Surgical result of plate osteosynthesis using a locking plate system through an anterior humeral approach for distal shaft fracture of the humerus that occurred during a throwing motion.

This paper analyzed outcomes of the osteosynthesis with a locking plate system for the fractures of the humerus in throwers using the anterior humeral approach. Retrospective case series including 31 patients. Bone union was assessed through follow-up radiographs. Results of visual analogue scale (VAS) for pain, range of motion in the elbow joint, time of return to work, and the Mayo Elbow Performance Score (MEPS) were evaluated to determine functional outcomes. Direction and length of the fracture, the distal cortical length, the humeral diameter, and the total humeral length were measured as part of fracture configuration analysis. Mean patient age was 25.8 (range, 18-34) years. The follow-up average was 16.0months (range, 12-23). Delayed union was observed in one (3.1%) patient. Mean final VAS was 0.4 (range, 0-2), mean time of return to work was 18.2weeks (range, 13-36), and mean MEPS was 96.3 (range, 88-100) points. All fractures showed a spiral configuration. Mean fracture length was 79.7 (95% CI, 72.6-86.7) mm, and mean distal cortical length was 48.3 (95% CI, 37.8-58.8) mm. The results of the current study indicates that plate osteosynthesis using a locking plate system combined with interfragmentary lag screws through anterior humeral approach may be a favorable option for the surgical treatment of humeral shaft fractures in throwers.

Osteosynthesis in Forearm Transplantation Using a Novel Ulnar-Shortening Osteotomy System for Simultaneous Both Bone Fixation

Introduction: Osteosynthesis in forearm-level allotransplantation is technically challenging. Achieving adequate cortical contact simultaneously between the radius and ulna proves difficult due to differing bone morphology of donor and recipient. In addition, the large area of dissection around the osteotomy sites and use of immunosuppressants further deters osseous healing, making nonunion a significant risk. Methods: Seven distal forearm transplants were performed on cadavers using the Newclip Technics ulnar-shortening osteotomy system for both the radius and ulna. The donor bones were plated after placing two transverse 0.062 K-wires distally for DRUJ stabilization. The osteotomy cut-guides were screwed to the plates and oblique osteotomies were performed. Matching recipient osteotomies were performed using the same cut-guide system. The donor and recipient were then brought together and any discrepancies in length corrected. The osteosynthesis site is then compressed and an interfragmentary lag screw...

Interfragmentary lag screw fixation in locking plate constructs increases stiffness in simple fracture patterns

BackgroundThe aim of the current biomechanical cadaver study was to quantify the influence of an additional lag screw on construct stiffness in simple fracture models at the distal femur stabilised with a locking plate. MethodsFor biomechanical testing paired fresh frozen human femora of 5 donors (mean age: 71 (SD 9) years) were chosen. Different locking plate configurations either with or without interfragmentary lag screw were tested under torsional load (2/4Nm/deg) or axial compression forces (500/1000N). FindingsData show that plate constructs with interfragmentary lag screw reveal similar axial and torsional stiffness values compared to intact bone as opposed to bridging plate constructs that showed significantly lower stiffness for both loading conditions. InterpretationThe current biomechanical testing unveils that the insertion of a lag screw combined with a locking plate dominates over a bridging plate construct at the distal femur in terms of axial and torsional stiffness.

Comparison of Compression Screw and Perpendicular Clamp in Ulnar Shortening Osteotomy

To biomechanically quantify 2 techniques, compression screw and perpendicular clamp, for generating compression during ulnar shortening osteotomy (USO) in order to promote reliable primary bone healing. Fourteen fresh-frozen cadaveric human forearms were randomly assigned to 1 of 2 groups. Group I (n= 7) underwent USO according to the traditional AO plate fixation technique using a screw placed eccentrically in an oblong hole to generate compression at the osteotomy site. Group II (n= 7) underwent USO with a commercially available USO plating system using a clamp placed perpendicular to the osteotomy site to generate compression. Both techniques involved a 2-mm resection osteotomy performed with cutting jigs to minimize variability and an interfragmentary lag screw to augment compression. A digital pressure sensor measured contact area at the osteotomy site and average pressure in the observed contact area; these values were used to calculate force across the osteotomy site. Measurements were obtained after the following steps: reduction of osteotomy, compression screw placement (group 1 only), lag screw placement, and final construct with all clamps removed. Group II demonstrated significantly greater force than group I, and lag screw placement resulted in significantly increased force independent of fixation technique. The effect of the lag screw on force was maintained after clamp removal. Although technique of fixation did not significantly influence contact area, lag screw placement significantly increased contact area independent of fixation method. However, this effect was not maintained after clamp removal. Average pressure in the observed contact area was not significantly influenced by fixation technique or stage of fixation. Perpendicular clamp compression significantly increased force as compared with traditional compression screw technique, and lag screw placement significantly increased force in both constructs. Larger compressive forces across the osteotomy may promote primary bone union and decrease the rates of delayed union or nonunion.

Biomechanical Comparison of 4 Different Lateral Plate Constructs for Distal Fibula Fractures

Displaced lateral malleolar fractures are often treated with reduction and surgical stabilization. However, there has not been a comprehensive laboratory comparison to determine the most appropriate device for treating these patients. This study subjected a range of contemporary lateral fibular plates to a series of mechanical tests designed to reveal performance differences. Forty fresh frozen lower extremities were divided into 4 groups. A Weber B distal fibula fracture was simulated with an osteotomy and stabilized using 1 of 4 plate systems: a standard Synthes one-third tubular plate with interfragmentary lag screw, a Synthes LCP locking plate with lag screw, an Orthohelix MaxLock Extreme low-profile locking plate with lag screw, or a TriMed Sidewinder nonlocking plate. Controlled monotonic bending and cyclic torsional loading were applied and bending stiffness, torsional stiffness, and fracture site motion were quantified. Resistance to cyclic torsional loading was determined by quantifying the number of loads withstood before excessive rotation occurred. Correlation between bone mineral density and each of the mechanical measures was determined. There was no difference in angulation or bending stiffness between plates. All plates except the LCP showed greater lateral deflection than in the other bending directions. Bending stiffness was lowest in lateral distal fragment deflection for all 4 plates. There was a positive correlation between bone mineral density and bending stiffness for all plate types. There was no difference in fracture site rotation between plate types in internal or external torsion, but internal rotation of the distal fragment consistently exceeded external rotation. Torsional stiffness in external rotation exceeded stiffness in internal rotation in nearly all specimens. LCP plates performed relatively poorly under cyclic torsion. Significant differences in plate performance were not demonstrated. The effects of bone quality variability and differences in interfragmentary screw purchase resulted in data dispersion that confounded absolute ranking of plate performance. Identification of an optimal lateral fibular plating system has the potential to improve the clinical outcome of malleolar fracture fixation, particularly when patient conditions are unfavorable.

Ulnar shortening with the ulna osteotomy locking plate

Ulnar shortening for ulnocarpal unloading using a new device enabling parallel osteotomy, rotation-secured compressive shortening, lag screw placement and hybrid stabilization combined in a solely locking plate construct. Idiopathic ulnar impaction syndrome. Posttraumatic radial shortening without major tilting of the radius in the sagittal or frontal plane, rotation deformity and/or translation of the distal fragment. Advanced arthritis of the distal radioulnar joint (DRUJ), DRUJ typeIII according to Tolat, malunion of the distal radius with major tilting of the radius in the sagittal or frontal plane, rotation deformity and/or translation of the distal fragment. Mounting of the UOL plate system on the palmar surface of the ulna using standard ulnopalmar exposure. Two parallel 45° osteotomies are performed using an osteotomy guide followed by rotation secured shortening and compression. Stabilization is gained by inserting an interfragmentary lag screw perpendicular to the osteotomy site and applying locking and compression screws. Lower arm cast for 4weeks until radiological signs of bone healing become apparent. To limit negative influence of rotational forces during bone healing, patients were instructed to limit forearm rotation up to 30° in pro-/supination. Sixteen ulnar shortening osteotomies were performed in 15patients (6men, 9women, average age 49years) and evaluated retrospectively. In 10cases a trauma-related pathology was the indication for the procedure. The average follow-up time was 53weeks (range 12-93weeks). Bone union was observed at a median of 10weeks (range 6-33weeks). Overall good clinical results could be achieved with an average shortening of 3.7mm (range 2.1-16mm). In this series, there was one nonunion.