Fracture fixation with two locking screws versus three non-locking screws: A biomechanical comparison in a normal and an osteoporotic bone model

The Biomechanical Behavior of Fixation Options in Short Segment Radius and Ulna Diaphyseal Fractures

PURPOSE

Plate fixation of radius and ulna shaft fractures has evolved due to a more complete understanding of the biology and mechanics. Screw fixation across six cortices has been adopted as the standard, purported to provide the optimal biological and mechanical environment for healing; however, recent investigations have proposed that four cortices of fixation may be sufficient. These recommendations are intended for segments of optimal length; however, it is less clear how these options perform in short segment fixation. Our objective was the determine the biomechanical behavior of fixation options for short segment diaphyseal fractures of the radius and ulna.

METHODS

Synthetic epoxy-formulated bones were prepared using a five-hole straight titanium plate with 3.5 mm locking and compression screws. Consistent with the recommendation of six cortices, we defined a construct of optimal length to be one with a single compression screw in three consecutive oblong holes (series 1). Series 2, 3, and 4 were configurations for short segment fixation. Torsional load to failure was applied to all samples.

RESULTS

The mean load to failure in series 4 was 2.5% higher than series 1. The mean load to failure in series 1 was 2.7% higher than series 2. All samples failed by spiral fracture of the bone through the screw holes.

CONCLUSIONS

Our results demonstrated that short segment fixation with six or eight cortices had stability comparable to a standard length segment with six cortices of fixation. Further, the use of locking screws did not improve torsional resistance. Across all testing series, utilization of two screws in a single oblong hole did not affect the failure mechanism.

CLINICAL RELEVANCE

The current findings suggest that increasing the number of cortices from six to eight has the potential to mitigate suboptimal length in short segment diaphyseal fixation.

The Role of Proximal Locking Fixation in Volar Distal Radius Fracture Fixation

Background  Volar-locked plating has become a popular treatment option for unstable distal radius fractures. While using locking screws in the distal fragment increases the stability of the fixation, the biomechanical benefits of locking fixation in the proximal fragment have not been definitively established. Purposes  This study evaluated the initial mechanical behavior of the volar plating construct with different locking screw configurations in the proximal fragment. Materials and Methods  Sixteen Sawbones radius models were used. An unstable metaphyseal distal radius fracture was created and fixated with a volar-locked plate. Four different screw configurations in the proximal fragment were tested: all nonlocking screws, locking screw in the distal-most hole, locking screw in the proximal-most hole, and locking screws in both the proximal- and distal-most holes. Initial stiffness, displacement during harmonic loading, and load-to-failure were compared among the three groups. Results  The initial stiffness, displacement during harmonic loading, and load-to-failure did not significantly differ among the four proximal screw configurations ( p  < 0.05). Failure occurred via toggling of the screws in the configuration with all nonlocking screws and through screw breakage or locking mechanism failure in the configurations with locking screws. Conclusion  The use of locking screws in the proximal fragment did not significantly affect the initial stability of volar distal radius plating. However, failure modes differed between the nonlocking and locking configurations, consistent with known mechanical properties of locking fixation. Further mechanical studies in cadaveric models and clinical trials are warranted to determine the optimal screw configuration in volar distal radius plating. Level of Evidence  To be determined. Biomechanical study on synthetic models.

From bone to nacre - development of biomimetic materials for bone implants: a review

The field of bone repair and regeneration has undergone significant advancements, yet challenges persist in achieving optimal bone implants or scaffolds, particularly load-bearing bone implants. This review explores the current landscape of bone implants, emphasizing the complexity of bone anatomy and the emerging paradigm of biomimicry inspired by natural structures. Nature, as a master architect, offers insights into the design of biomaterials that can closely emulate the mechanical properties and hierarchical organization of bone. By drawing parallels with nacre, the mollusk shells renowned for their exceptional strength and toughness, researchers have endeavored to develop bone implants with enhanced biocompatibility and mechanical robustness. This paper surveys the literature on various nacre-inspired composites, particularly ceramic/polymer composites like calcium phosphate (CaP), which exhibit promising similarities to native bone tissue. By harnessing the principles of hierarchical organization and organic-inorganic interfaces observed in natural structures, researchers aim to overcome existing limitations in bone implant technology, paving the way for more durable, biocompatible, and functionally integrated solutions in orthopedic and dental applications.

Impacts of post-operation loading and fixation implant on the healing process of fractured tibia

Healing of tibia demonstrates a complex mechanobiological process as it is stimulated by the major factor of strains applied by body weight. The effect of screw heads and bodies as well as their pressure distribution is often overlooked. Hence, effective mechanical conditions of the healing process of tibia can be categorized into the material of the plate and screws, post-operation loadings, and screw type and pressure. In this paper, a mathematical biodegradation model was used to simulate the PGF/PLA plate-screw device over 8 weeks. The effect of different post-operation loading patterns was studied for both locking and non-locking screws. The aim was to reach the best configuration for the most achievable healing using FEA by computing the healing pattern, trend, and efficiency with the mechano-regulation theory based on deviatoric strain. The biodegradation process of the plate and screws resulted in 82% molecular weight loss and 1.05 GPa decrease in Young's modulus during 8 weeks. The healing efficiency of the cases ranged from 4.72% to 14.75% in the first week and 18.64% to 63.05% in the eighth week. Finally, an optimal case was achieved by considering the prevention of muscle erosion, bone density reduction, and nonunion, according to the obtained results.

Assessing Pain and Functional Outcomes of Percutaneous Stabilization of Metastatic Pelvic Lesions via Photodynamic Nails: A Bi-Institutional Investigation of Orthopaedic Outcomes

Background

Minimally invasive surgical interventions for metastatic invasion of the pelvis have become more prevalent and varied. Our group hypothesized that the use of percutaneous photodynamic nails (PDNs) would result in decreased pain, improved functional outcomes and level of ambulation, and decreased use of opioid pain medication.

Methods

We performed a retrospective chart review of patients with metastatic pelvic bone disease undergoing stabilization with PDNs (IlluminOss Medical) at 2 institutions. Functional outcome measures assessed include the Combined Pain and Ambulatory Function (CPAF), Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function, and PROMIS Global Health-Physical. Pain was assessed using a visual analog scale (VAS). Outcomes were assessed preoperatively and at 6 weeks, 3 months, 6 months, and 1 year following surgery.

Results

A total of 39 patients treated with PDNs were included. No cases of surgical site infection or implant failure were identified. The median pain VAS score decreased from 8 preoperatively to 0 at the 6-week time point (p < 0.0001). The median CPAF score improved from 5.5 points preoperatively to 7 points at the 3-month mark (p = 0.0132). A significant improvement in physical function was seen at 6 months in the PROMIS Physical Function (p = 0.02) and at both 6 months (p = 0.01) and 1 year (p < 0.01) for the PROMIS Global Health-Physical. The rate of patients prescribed opioid analgesia dropped from 100% preoperatively to 20% at 6 months following surgery (p < 0.001). By 6 weeks, all patients were fully weight-bearing and able to walk independently with or without assistive devices.

Conclusions

Percutaneous stabilization of metastatic periacetabular defects using PDNs is a safe and effective palliative procedure that has been shown to improve patient mobility and provide early pain relief.

Level of Evidence

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Biomechanical and clinical evaluation of minimal invasive plate osteosynthesis for two-part clavicle shaft fractures

BACKGROUND

Many surgical treatment methods exist for clavicle shaft fractures. A locking compression plate (LCP) fixation with three screws per fracture side is commonly used. For certain fractures a stabilization with 2 screws per side is potentially suitable, offering the advantage of reduced soft tissue approach, while avoiding the disadvantages of minimally-invasive nailing at the same time. This hypothesis was evaluated biomechanically and clinically.

METHODS

Four treatment procedures were investigated biomechanically using composite human clavicle specimens. A load-to-failure test was performed using a three-point cantilever test. In group 1, a simple shaft fracture was simulated and stabilized with 2 screws per fracture side (5-hole LCP). In the second group 3 screws per side (7-hole LCP) were used. In group 3, a non-reduced fracture zone was simulated and treated with 3 screws per side (7-hole LCP). In group 4, an anatomically reduced fracture zone was simulated and treated with 3 screws per side (7-hole LCP). Furthermore 27 patients treated with a short plate and 2 screws per side (similar to group 1) were assessed after a minimum follow-up of 12 months (Constant and DASH Score).

RESULTS

The maximum load-to-failure of group 1 was 367N. We observed the highest load-to-failure in group 2 with 497N and the lowest in group 3 with 90N. In group 4 a maximum load-to-failure of 298N could be evaluated. There was no significant difference in load-to-failure between the treatment of a simple clavicle fracture using 5- or 7-hole LCP (p = 0.121). However, we found a significant difference of load-to-failure between the simple and anatomically reduced fracture using a 7-hole plate (p = 0.014). The mean constant score of the surgically treated patients was 95 and the DASH score 3.0. Fracture consolidation was observed in 96.3%.

CONCLUSIONS

For certain non-fragmented and well interlocking 2-part fractures, a plate osteosynthesis fixed with only 2 screws per fracture side might offer sufficient biomechanical stability, better soft tissue preservation and comparable fusion rates compared to the operative treatment with 3 screws per side. However, the maximum load-to-failure of the 7-hole LCP was higher than of the 5-hole LCP, but this difference was not statistically significant.

TRIAL REGISTRATION

Approval from the ethics committee of the Technical University of Dresden was retrospectively obtained (EK 588122019).

Tibial Plateau Leveling Osteotomy in small and large breed dogs: a comparative retrospective study of complications and outcomes

OBJECTIVE

To compare complication rates and outcomes of small and large breed dogs that had locking plate Tibial Plateau Leveling Osteotomy (TPLO) performed due to cranial cruciate ligament disease during the same time period at a single institution and identify potential influencing factors.

MATERIAL AND METHODS

136 cases with TPLO performed at a single institution between January 2013 and December 2015 were retrospectively reviewed. Dogs were grouped by plate sizes (2.0, 2.4, 2.7, 3.5 and 3.5 broad) and by small breeds (2.0-2.7 plate sizes) and large breeds (3.5 plates). Potential influencing factors on lameness and complications were recorded from the database and measured on radiographs and statistically compared.

RESULTS

Small dogs experienced fewer complications than large dogs (10% vs. 22%) and not a single major complication. Small dogs were significantly less lame at recheck and at long-term follow-up. Progression of bone healing had an influence on the lameness grade of dogs at recheck after TPLO. Distance of the most proximal screw from the joint was identified as a risk factor for implant failure. The width of the patella ligament correlated with body weight and uniformly increased 2.4 times after TPLO.

CONCLUSIONS

TPLO in small breed dogs has a lower overall complication rate than in large breed dogs. The TPLO plate should always be placed as close to the joint as possible to reduce the risk of implant failure.

CLINICAL RELEVANCE

TPLO can be recommended as treatment for cranial cruciate ligament rupture (CCLR) in dogs of all sizes.

Retrograde tibiotalocalcaneal nailing for the treatment of acute ankle fractures in the elderly: a systematic review and meta-analysis

Introduction

Methods

Results

Conclusion

Reverse total shoulder arthroplasty baseplate stability with locking vs. non-locking peripheral screws

BACKGROUND

There are many options for glenosphere baseplate fixation commercially available, yet there is little biomechanical evidence supporting one type of fixation over another. In this study, we compared the biomechanical fixation of a reverse total shoulder glenoid baseplate secured with locking or non-locking peripheral screws.

METHODS

Both a non-augmented mini baseplate with full backing support and an augmented baseplate were testing after implantation in solid rigid polyurethane foam. Each baseplate was implanted with a 30 mm central compression screw and four peripheral screws, either locking or non-locking (15 mm anterior/posterior and 30 mm superior/inferior). A 1 Hz cyclic force of 0-750 N was applied at a 60^o angle for 5000 cycles. Throughout the test, the displacement of the baseplate was measured using a 3D Digital Image Correlation System.

FINDINGS

The amount of migration measured in the both the non-augmented and augment cases shows no significant differences between locking and non-locking cases at the final cycle count (non-augment: 5.66 +/- 2.29 μm vs. 3.71 +/- 1.23 μm; p = 0.095, augment: 15.43 +/- 8.49 μm vs. 12.46 +/- 3.24 μm; p = 0.314). Additionally, the amount of micromotion measured for both sample types shows the same lack of significant difference (non-augment: 10.79 +/- 5.22 μm vs. 10.16 +/- 7.61 μm; p = 0.388, augment: 55.03 +/- 10.13 μm vs. 54.84 +/- 10.65 μm; p = 0.968).

INTERPRETATION

The presence of locking versus non-locking peripheral screws does not make a significant difference on the overall stability of a glenoid baseplate, in both a no defect case with a non-augmented baseplate and a bone defect case with an augmented baseplate.

Biomechanical Comparison of Use of Two Screws versus Three Screws Per Fragment with Locking Plate Constructs under Cyclic Loading in Compression in a Fracture Gap Model

OBJECTIVES

 The aim of this study was to measure and compare the stiffness and cyclic fatigue of two plate-bone model constructs, with either two or three locking screws per fragment, under cyclic compression.

METHODS

 A 10-hole 3.5 mm stainless steel locking compression plate (LCP) was fixed 1 mm from a synthetic bone model in which the fracture gap was 47 mm. Two groups of 10 constructs, prepared with either two or three bicortical locking screws placed at the extremities of each fragment, were tested in a load-controlled compression test until failure.

RESULTS

 The three-screw constructs were stiffer than the two-screw constructs (196.75 ± 50.48 N/mm and 102.43 ± 22.93 N/mm, respectively) and the actuator displacements of the two-screw constructs were higher (18.02 ± 1.07 mm) than those of the three-screw constructs (14.48 ± 2.25 mm). The number of cycles to failure of the two-screw constructs was significantly lower (38,337.50 ± 2,196.98) than the that of the three-screw constructs (44,224.00 ± 1,515.24). Load at irreversible deformation was significantly lower in the two-screw constructs (140.93 ± 13.39 N) than in the three-screw constructs (184.27 ± 13.17 N). All constructs failed by plate bending at the gap between the two cylinders.

CLINICAL SIGNIFICANCE

 Omission of the third innermost locking screw during bridging osteosynthesis subjected to compression forces led to a 13.3% reduction in the number of cycles to failure and a 23.5% reduction of the load withstood by the plate before plastic deformation occurred.

Management of proximal metaphyseal curvilinear tibial fractures in 25 skeletally immature dogs (2009 to 2020)

OBJECTIVES

To describe the occurrence, management and outcome of proximal metaphyseal curvilinear tibial fractures in skeletally immature dogs.

MATERIALS AND METHODS

A multi-centre retrospective review was conducted, searching for skeletally immature dogs presenting with proximal metaphyseal curvilinear tibial fractures between January 2009 and September 2020. Signalment, fracture description and case management data were retrieved. Outcome was assessed by retrospectively evaluating follow-up radiographs, hospital records and an owner questionnaire.

RESULTS

Twenty-five dogs met the inclusion criteria. All but one fracture was a result of minimal trauma. Twenty fractures were managed with internal fixation, two with external fixation and three conservatively. All 25 fractures healed. Eight major complications occurred in seven of 25 (28%) dogs. Twelve minor complications occurred in 10 of 25 (40%) dogs. Owner questionnaire data were available for 12 of 25 dogs; 11 of 12 were reported as having full function and one of 12 as having acceptable function at the time of questioning (median 34.5 months following presentation). At final follow-up, either by clinical examination or owner questionnaire, full function was achieved in 22 of 25 patients and acceptable function in three of 25.

CLINICAL SIGNIFICANCE

This study reported a series of proximal metaphyseal tibial fractures in skeletally immature dogs. The most common fixation method was internal fixation, which frequently resulted in full limb function at final follow-up. Owners reported outcome as fully functional in all dogs that underwent surgery at first presentation and had owner follow-up available, though positive outcomes may have been affected by participation bias.

Is Bridge Plating of Comminuted Humeral Shaft Fractures Advantageous When Using Compression Plates with Three versus Two Screws per Fragment? A Biomechanical Cadaveric Study

Background

Minimally invasive plate osteosynthesis (MIPO) is one of the generally accepted surgical techniques for the treatment of humeral shaft fractures. However, despite the high bone union rate, a variety of complications are still prevailing. Moreover, the current literature lacks data comparing the anterolateral MIPO approach using dynamic compression plates accommodating different numbers of screws. The aim of this study was to analyze the biomechanical performance of comminuted humeral shaft fractures fixed with dynamic compression plates using either two or three screws per fragment.

Methods

Six pairs of fresh-frozen human cadaveric humeri from donors aged 66.8 ± 5.2 years were randomized to two paired study groups for simulation of bridge-plated comminuted shaft fracture type AO/OTA 12-C1/2/3 without interfragmentary bony support, using a dynamic compression plate positioned on the anterolateral surface and fixed with two (group 1) or three (group 2) screws per fragment. All specimens underwent nondestructive quasistatic biomechanical testing under lateral bending, anterior bending, axial bending, and torsion in internal rotation, followed by progressively increasing cyclic torsional loading in internal rotation until failure.

Results

Initial stiffness of the plated specimens in lateral bending, anterior bending, axial bending, and torsion was not significantly different between the groups (P ≥ 0.22). However, cycles to 10°, 15°, and 20° torsional deformation and cycles to construct failure were significantly higher in group 2 compared with group 1 (P ≤ 0.03).

Conclusions

From a biomechanical perspective, no significant superiority is identified in terms of primary stability when using two or three screws per fragment for bridge compression plating of comminuted humeral shaft fractures. However, three-screw configurations provide better secondary stability and maintain it with a higher resistance towards loss of reduction under dynamic loading. Therefore, the use of a third screw may be justified when such better secondary stability is required.

How Many Proximal Screws Are Needed for a Stable Proximal Humerus Fracture Fixation?

Purpose

This biomechanical study investigates the optimal number of proximal screws for stable fixation of a 2-part proximal humerus fracture model with a locking plate.

Methods

Twenty-four proximal humerus fracture models were included in the study. An unstable 2-part fracture was created and fixed by a locking plate. Cyclic loading and load-to-failure tests were used for the following 4 groups based on the number of screws used: 4-screw, 6-screw, 7-screw, and 9-screw groups. Interfragmentary gaps were measured following cyclic loading and compared. Consequently, the load to failure, maximum displacement, stiffness, and mode of failure at failure point were compared.

Results

The interfragmentary gaps for the 4-screw, 6-screw, 7-screw, and 9-screw groups were significantly reduced by 0.24 ± 0.09 mm, 0.08 ± 0.06 mm, 0.05 ± 0.01 mm, and 0.03 ± 0.01 mm following 1000 cyclic loading, respectively. The loads to failure were significantly different between the groups with the 7-screw group showing the highest load to failure. The stiffness of the 7-screw group was superior compared with the 6-screw, 9-screw, and 4-screw groups. The maximum displacement before failure showed a significant difference between the comparative groups with the 4-screw group having the lowest value. The 7-screw group had the least structural failure rate (33.3%).

Conclusion

At least 7 screws would be optimal for proximal fragment fixation of proximal humerus fractures with medial comminution to minimize secondary varus collapse or fixation failure.

Level of Evidence

Basic science study.

Wrist Arthrodesis in Rheumatoid Arthritis Using an LCP Metaphyseal Locking Plate versus an AO Wrist Fusion Plate

Objectives

Although wrist arthrodesis using a plate is an established treatment with a well-documented successful union rate for severely destroyed wrists, plate-related complications are a matter of great concern.

Methods

We retrospectively compared wrist arthrodesis using an AO wrist fusion plate in nine and a locking compression plate (LCP) metaphyseal plate in seven cases of rheumatoid arthritis.

Results

The mean follow-up was 40.6 months in the AO wrist fusion plate group and 57.2 months in the LCP metaphyseal plate group. Bone union at the arthrodesis site was achieved in all cases in both groups. Comparison of the original position of the fusion on the immediate postoperative radiographs and the position on the most recent follow-up radiographs demonstrated good stability in both groups. Plate-related complications occurred in four cases in the AO wrist fusion plate group and no cases in the LCP metaphyseal plate group. Complications included pain over the plate, wound dehiscence and infection, extensor tendon adhesion, and fracture in one case each.

Conclusion

Wrist arthrodesis using an LCP metaphyseal plate was favorable for rheumatoid arthritis patients with comparable stability to that of and a lower risk of plate-related complications than an AO wrist fusion plate.

A Biomechanical and Clinical Comparison of Midshaft Clavicle Plate Fixation: Are 2 Screws as Good as 3 on Each Side of the Fracture?

Background:

The standard of care for plating displaced midshaft clavicle fractures has been 6 cortices of purchase on each side of the fracture. The use of locking plates and screws may afford equivalent biomechanical strength with fewer cortices of purchase on each side of the fracture.

Purpose:

To compare the biomechanical and clinical performance of 3- versus 2-screw constructs for plating displaced midshaft clavicle fractures.

Study Design:

Controlled laboratory study/cohort study; Level of evidence, 3.

Methods:

Lateral fragments of simulated midshaft fractures in 10 pairs of cadaveric clavicles were randomly assigned to plate fixation with either 3 nonlocking screws or 2 locking screws. Cyclic tensile loads were applied along the long axis of the clavicle. The constructs were then loaded to failure with pullout forces applied parallel to the long axis of the screws. Additionally, clinical outcomes of patients who had midshaft clavicle fractures that were surgically repaired were retrospectively identified and compared; 21 patients were treated with 3-screw constructs and 20 with 2-screw constructs.

Results:

Biomechanically, there were no significant differences for cyclic displacement, stiffness, yield load, or ultimate load between groups. Forces required for screw pullout were considerably higher than physiologic forces experienced by a healing clavicle in vivo. Clinically, there were no significant differences in American Shoulder and Elbow Surgeons, Constant, visual analog scale, and Single Assessment Numeric Evaluation scores; complications; or mean time to union. Additionally, we found that the plates used in the 2-screw group were consistently shorter.

Conclusion:

Plate fixation of displaced midshaft clavicle fractures with 4 cortices of purchase with 2 locking screws demonstrated no significant differences biomechanically when compared with fixation with 6 cortices of purchase and 3 nonlocking screws. Clinically, there were no significant differences in outcomes or complications seen in patients receiving 2- or 3-screw constructs.

Clinical Relevance:

Clinical benefits of using the 3-screw construct for plate fixation include decreased surgical exposure, morbidity, and cost, and the use of shorter and noncontoured straight plates eliminates the extra time and technical difficulty associated with matching longer contoured plates to the complex morphology of the clavicle.

Proximal Femur Locking Plate for Sub-Trochanteric Femur Fractures: Factors Associated with Failure

Introduction:

Proximal femur locking compression plates (PF-LCP) have gained popularity since their inception due to superior biomechanical stability and durability but clinical experience has shown conflicting results including implant failure.

Objective:

To study the incidence of implant failure in patients with sub-trochanteric fractures managed with proximal femoral locking compression plate and identify potential risk factors associated with the failure.

Materials & Methods:

Fifty patients with sub-trochanteric fractures, operated upon with titanium PF-LCP were included in the study from January 2012 to December 2014. These plates were of two designs including one five 5.0 mm proximal locking screws (implant A) and other with three 6.5 mm proximal locking screws (implant B). Fractures were classified according to AO/OTA and Seinsheimer classification. Patients had regular follow-up visits for at least a year, allowing for clinical and radiological assessment of union and implant-related complications.

Results:

A total of 13 out of 50 (26%) plates failed of which 7 were implant fractures, 3 screw breakage and 3 screw cut outs. 70% of the failures occurred in elderly females. Overall implant failure was significantly more common in patients >50 years (p 0.04). Comparing the two different designs of implants used, implant A was more likely to fail at a plate screw density of 0.8 or more (p 0.02), whereas implant B was associated with significant failure when less than 4 proximal screws were used (p 0.03).

Conclusion:

This study revealed a high failure rate (26%) of this implant. Attention to the neck shaft angle difference, number of proximal screws and plate screw density may help reduce failure rates, particularly in elderly osteoporotic females.

Evaluation of outcome of proximal femur locking compression plate (PFLCP) in unstable proximal femur fractures

INTRODUCTION

Pertrochanteric fractures are most frequent factures of the proximal femur, accounts for nearly 50% of all proximal femur fractures and are most devastating and also a major cause of disability in elderly. The aim and objective of this study was to evaluate the role of proximal femoral locking compression plate in unstable proximal femur fractures.

MATERIAL AND METHOD

A total of 20 cases were included in our study (M:F - 16:4), who suffered proximal femur fracture due to various modalities and all of them were operated using proximal femoral locking compression plate. This proximal femoral fractures included unstable - intertrochanteric with subtrochanteric extension and subtrochanteric with intertrochanteric extensions as well as one case with intertrochanteric, subtrochanteric and neck of femur fracture. Patients were followed up regularly and minimum follow-up period was 12 months. Patients were given physiotherapy and partial weight bearing was started after 6 weeks postoperatively or after union was achieved. The outcome was evaluated as per Harris Hip Score and radiological union.

RESULT

Among 20 cases with average age of 55.3 ± 17.9 years, treated with PF-LCP, the average time of union 18.75 ± 3.67 weeks was achieved. We got 10 excellent, 3 good, 3 fair and 4 poor result with average Harris Hip Score of 80.2 ± 28.54 with 65% good to excellent result with average Post-operative Neck Shaft Angle of 124.150 ± 17.880 and with 45% rate of complication which included four cases of superficial infection and two cases of deep infection and late complications like four cases of non-union, deformity - three cases of coxa vara and 2 cases of coxa valga, with patients having more than one complication in them.

CONCLUSION

PF-LCP is not recommended as a definitive implant but can be used as an alternative for the treatment of unstable proximal femoral fractures when there is no option available for other routinely used implants. Despite of its complications, PF-LCP is used where all implants fail.

Age-related optimization of screw placement for reduced loosening risk in locked plating

When using locked plating for bone fracture fixation, screw loosening is reported as one of the most frequent complications and is commonly attributed to an incorrect choice of screw configuration. Choosing a patient-optimized screw configuration is not straightforward as there are many interdependent variables that affect device performance. The aim of the study was to evaluate the influence that locking screw configuration has on loosening risk and how this is influenced by bone quality. This study uses finite element models that incorporate cortical bone heterogeneity, orthotropy, and geometrical nonlinearity to examine the effect of screw configuration on variables associated with loosening and interfragmentary motion. Strain levels within the bone were used as indicators of regions that may undergo loosening. The study found that, in healthy bone under axial loading, the most important variables influencing strain levels within the bone were the size of the bridging span (working length) and the plate rigidity. Unlike healthy bone, osteoporotic bone was found to be particularly sensitive to the spacing of the screws within the plate. Using two empty screw holes between the screws closest to the fracture was found to reduce the strain levels at the first screw by 49% in osteoporotic bone (compared to only 2.4% in healthy bone). The study also found that under torsional loading the total number of screws used was the most important variable with a 59% reduction in the strain around the screws closest to the fracture when using six rather than four screws in osteoporotic bone. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1856-1864, 2016.

Evaluation of cyclic and linear mechanical resistance of prebent and manually-bent plates used for maxillary advancement in orthognathic surgery

The aim of the present study was to compare prebent and manually-bent plates used in maxillary advancement. The prebent plates were fixed in polyurethane blocks for the linear test and aluminium blocks for the cyclic test, and the manually-bent plates were fixed in polyurethane and aluminium blocks. The linear load tests were done using an Instron^® 4411 mechanical testing machine and the cyclic test with an Instron^® E3000 testing machine. The linear mechanical test showed that there was no significant difference between the plates. In the cyclic test the prebent plates reached the limit of 500000 cycles without fracturing whereas the manually-bent plate group fractured before reaching the limit of cycles (p=0.008). The decision to use prebent or manually-bent plates during operations should be influenced by the production of the bends and their consequent brittleness.

Open wedge metatarsal osteotomy versus crescentic osteotomy to correct severe hallux valgus deformity - A prospective comparative study

BACKGROUND

Different techniques of proximal osteotomies have been introduced to correct severe hallux valgus. The open wedge osteotomy is a newly introduced method for proximal osteotomy. The aim of this prospective randomized study was to compare the radiological and clinical results after operation for severe hallux valgus, comparing the open wedge osteotomy to the crescentic osteotomy which is our traditional treatment.

METHODS

Forty-five patients with severe hallux valgus (hallux valgus angle >35̊, and intermetatarsal angle >15̊) were included in this study. The treatment was proximal open wedge osteotomy and fixation with plate (Hemax), group 1, or operation with proximal crescentic osteotomy and fixation with a 3mm cannulated screw, group 2. The mean age was 52 years (19-71). Forty-one females and four males were included. Clinical and radiological follow-ups were performed 4 and 12 months after the operation.

RESULTS

In group 1 the hallux valgus angle decreased from 39.0̊ to 24.1̊ after 4 months and 27.9̊ after 12 months. In group 2 the angle decreased from 38.3̊ to 21.4̊ after 4 months and 27.0̊ after 12 months. The intermetatarsal angle in group 1 was 19.0̊ preoperatively, 11.6̊ after 4 months and 12.6̊ after 12 months. In group 2 the mean intermetatarsal angle was 18.9̊ preoperatively, 12.0̊ after 4 months and 12.6̊ after 12 months. The AOFAS score improved from 59.3 to 81.5 in group 1 and from 61.8 to 84.8 in group 2 respectively measured 12 months postoperatively. The relative length of the 1 metatarsal compared to 2 metatarsal bone was 0.88 and 0.87 preoperatively and 0.88 and 0.86 for group 1 and 2 respectively measured after 12 months.

CONCLUSION

Crescentic osteotomy and open wedge osteotomy improve AOFAS score and VAS scores on patients operated with severe hallux valgus. No significant difference was found in the two groups looking at the postoperative improvement of HVA and IMA measured 4 and 12 months postoperatively. The postoperative VAS score and AOFAS score were comparable for the two groups with no significant difference. An expected tendency to gain better length of the first metatarsal using the open wedge osteotomy compared to the crescentic osteotomy was not found. Even though the IMA and HVA reduction was only suboptimal the improvement in AOFAS score was comparable to other similar clinical trials.

Proximal femoral locking compression plate for proximal femoral fractures

PURPOSE

To review short-term outcomes of proximal femoral locking compression plate (PF-LCP) fixation for proximal femoral fractures in terms of postoperative complications and failure rates.

METHODS

Medical records of 21 men and 5 women aged 22 to 85 (mean, 49.7) years who underwent internal fixation with the PF-LCP for proximal femoral fractures were reviewed. Younger patients (mean age, 38.7 years) were more commonly involved in high-energy trauma with multiple musculoskeletal injuries, whereas older patients (mean age, 67.7 years) were more commonly involved in low-energy trauma. Fractures were classified into: multi-fragmentary pertrochanteric fractures (n=13), transtrochanteric fractures (n=6), and subtrochanteric/proximal diaphyseal fractures (n=7).

RESULTS

Patients were followed up for a mean of 14.7 months. Seven patients developed complications including loosening of locking screws (n=4), delayed union (n=2), and infection (n=1); 4 of them required additional surgeries.

CONCLUSION

The PF-LCP is appropriate for complex proximal femoral fractures with poor bone quality, revision surgeries, and multi-fragmentary subtrochanteric/proximal diaphyseal fractures. For intertrochanteric fractures, the sliding hip screw system should be used to avoid failure.

A biomechanical evaluation of locked plating for distal fibula fractures in an osteoporotic sawbone model

BACKGROUND

Supination external rotation (SER) injuries are commonly fixed with a one third tubular neutralization plate. This study investigated if a combination locked plate with additional fixation options was biomechanically superior in osteoporotic bone and comminuted fracture models.

METHODS

Using an osteoporotic and a comminuted Sawbones model, SER injuries were fixed with a lag screw for simple oblique fibula fractures, and either a one third tubular neutralization plate or a locking plate. Samples were tested in stiffness, peak torque, displacement at failure, and torsion fatigue.

RESULTS

There was no statistically significant difference in biomechanical testing for fractures treated with a lag screw and plate. For comminuted fractures, locked plating demonstrated statistically significant stiffer fixation.

CONCLUSION

A combination locked plate is biomechanically superior to a standard one third tubular plate in comminuted SER ankle fractures. There was no biomechanical superiority between locked and one third tubular plates when the fracture was amenable to a lag screw.