Locked plating of distal femur fractures leads to inconsistent and asymmetric callus formation

Comparing Intramedullary Nailing Versus Locked Plating in the Treatment of Native Distal Femur Fractures: Is One Superior to the Other?

INTRODUCTION

Distal femur fractures make up < 1% of all fractures and 3-6% of all femur fractures. In the literature, both intramedullary nailing (IMN) and locked plating (LP) have shown favorable results, but there is no consensus on a gold standard. The purpose of this systematic review is to compare outcomes of native distal femur fractures treated via IMN versus LP in an effort to determine if one is superior to the other.

METHODS

Systematic review of MEDLINE, EMBASE, and Cochrane Library databases was conducted according to PRISMA guidelines. Only articles published within the last ten years were included. Evidence and study quality were evaluated with the MQOE and Oxford Criteria.

RESULTS

Forty-six articles were included in the review. Fractures treated with IMN were found to have a 93.9% union rate, an average time to union of 19.2 weeks, an average arc of motion of 105.1 degrees, with an average of 14.4 degrees of malalignment. Fractures treated with LP were found to have a 90.2% union rate, an average time to union of 20.5 weeks, an average arc of motion of 104 degrees, with an average of 12.6 degrees of malalignment.

CONCLUSION

Compiled data comparisons revealed no differences in union rate, malalignment, time to union, average arc of motion, or complication rates requiring a return to the operating room. Until higher level randomized data is available, either IMN or LP are acceptable methods of treatment for native distal femur fractures.

Axial Micromotion Locking Plate Construct Can Promote Faster and Stronger Bone Healing in an Ovine Osteotomy Model

Fixing bone fractures with controlled axial interfragmentary micromotion improves bone healing; however, the optimal type of implant construct for this purpose is still lacking. The present study describes a novel axial micromotion locking plate (AMLP) construct that allows axial interfragmentary micromotion of 0.3 or 0.6 mm. We investigated whether the AMLP constructs enhance bone healing compared to an ordinary locking plate (LP) using an ovine osteotomy model. The stiffness of the constructs was tested under axial loading. We created a 3-mm osteotomy in the left hind leg tibia of sheep that was then stabilized with a 0.3- or 0.6-mm AMLP or LP construct (n = 6/group). Bone healing was monitored weekly by X-ray radiography starting from week 3 after surgery. At week 9, the specimens were collected and evaluated by computed tomography and torsional testing. We found that the AMLPs had a lower stiffness than the LP; in particular, the stiffness of the 0.6-mm AMLP construct was 86 and 41% lower than that of the LP construct for axial loads <200 and >200 N, respectively. In the in vivo experiments, tibial osteotomies treated with the 0.6-mm AMLP construct showed the earliest maximum callus formation (week 5) and the highest volume of bone callus (9.395 ± 1.561 cm³ at week 9). Specimens from this group also withstood a 27% greater torque until failure than those from the LP group (P = 0.0386), with 53% more energy required to induce failure (P = 0.0474). These results demonstrate that AMLP constructs promote faster and stronger bone healing than an overly rigid LP construct. Moreover, better bone healing was achieved with an axial micromotion of 0.6 mm as compared to 0.3 mm.

Infected Non-Union of the Distal Femur

The reported levels of non-union in the lateral locking plate differ widely, with some early studies showing rates of less than 6% and up to 17%-21% in more recent studies. We report a case where better results were shown by a non-union treated with distal femoral nailing with allogenic grafting.

Influence of gap distance between bone and plate on structural stiffness and parallel interfragmental movement in far-cortical locking technique - a biomechanical study

Sufficient interfragmental movement is the key to successful fracture healing in the theory of secondary bone healing. The far-cortical locking technique enables both stiffness reduction and parallel motion for ideal callus formation and fracture healing, but the influence of plate-bone gap on the performance of far-cortical locking technique remains unclear. The current study conducted a series of finite element analyses with mechanical validation to clarify this issue. Plate-bone gaps were assigned by 1, 2, 3, and 4 mm in a simulated mid-shaft fracture model fixed with locking plate and six semi-rigid locking screws. Axial compressive load to 500 N was applied to the fixation structure to evaluate the structural stiffness, pattern of interfragmental movement (parallel motion), and stresses on the screws. Results revealed the increased plate-bone gaps reduced the structural in order (315.3, 288.8, 264.9, and 243.4 N/mm). Tilting angles for determining parallel interfragmental movement (1.58°-1.85°) and stresses on semi-rigid screws for evaluating implant safety were not severely altered. Greater stresses were found on the screws adjacent to the fracture site in all simulated models. The current study suggested that 1 mm gap between the locking plate and the bone shall be ideal in view of parallel motion achieved balanced callus formation in far-cortical locking technique. Issue of reducing structural stiffness with limited plate-bone gap distance should be further investigated.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Biphasic plating improves the mechanical performance of locked plating for distal femur fractures

Internal fixation by plate osteosynthesis is the gold standard treatment for distal femur fractures. Despite improvements that preserve the biological conditions for bone healing, there are concerns standard locked plating constructs may be overly stiff. Biphasic plating is a novel concept designed to provide suitable fracture motion and increased implant strength to support early full weight-bearing. This study aims to demonstrate that the Biphasic Plate can be incorporated into a pre-contoured distal femur plate while providing adequate flexibility and increased implant strength. The mechanical performance of the Biphasic Plate (BP) was investigated in comparison to a standard locking plate for the distal femur (LCP-DF). Constructs were formed by mounting the implants on a bone substitute. The construct stiffness and strength under axial loading and the magnitude of interfragmentary movement were determined using finite element analysis. The Biphasic Plate exhibited a bi-linear stiffness response; at low loads, the BP construct was 55% more compliant and at high loads 476% stiffer than the LCP-DF. The Biphasic Plate provided more consistent interfragmentary movement over a wider loading range. At partial weight-bearing loads, the Biphasic Plate produced larger interfragmentary movements (0.18 vs. 0.04 mm). However, at loads equivalent to full weight-bearing, the maximum movements were substantially smaller than the LCP-DF construct (1.5 vs. 3.5 mm). The increased flexibility at low loads was provided without sacrificing implant strength with peak stress in the Biphasic Plate 63% lower than the LCP-DF construct. The biphasic plating concept can be successfully incorporated into anatomically contoured distal femur plates while providing adequate flexibility and increasing implant strength.

The investigation of bone fracture healing under intramembranous and endochondral ossification

After trauma, fractured bone starts healing directly through bone union or indirectly through callus formation process. Intramembranous and endochondral ossification are two commonly known mechanisms of indirect healing. The present study investigated the bone fracture healing under intramembranous and endochondral ossification by developing theoretical models in conjunction with performing a series of animal experiments. Using experimentally determined mean bone densities in sheep tibia stabilized by the Locking Compression Plate (LCP) fixation system, the research outcomes showed that intramembranous and endochondral ossification can be described by Hill Function with two unique sets of function parameters in mechanical stimuli mediated fracture healing. Two different thresholds exist within the range of mechanical simulation index which could trigger significant intramembranous and endochondral ossification, with a relatively higher bone formation rate of endochondral ossification than that of intramembranous ossification. Furthermore, the increase of flexibility of the LCP system and the use of titanium LCP could potentially promote uniform bone formation across the fracture gap, ultimately better healing outcomes.

Variable fixation promotes callus formation: an experimental study on transverse tibial osteotomies stabilized with locking plates

Background

A new locking screw technology, named variable fixation, has been developed aiming at promoting bone callus formation providing initial rigid fixation followed by progressive fracture gap dynamisation. In this study, we compared bone callus formation in osteotomies stabilized with standard locking fixation against that of osteotomies stabilized with variable fixation in an established tibia ovine model.

Methods

A 3 mm tibial transverse osteotomy gap was stabilized in three groups of six female sheep each with a locking plate and either 1) standard fixation in both segments (group LS) or 2) variable fixation in the proximal and standard fixation in the distal bone segment (group VFLS₃) or 3) variable fixation in both segments (group VFLS₆). The implantation site and fracture healing were compared between groups by means of radiologic, micro tomographic, biomechanical, and histological investigations.

Results

Compared to LS callus, VFLS₃ callus was 40% larger and about 3% denser, while VFLS₆ callus was 93% larger and its density about 7.2% lower. VFLS₃ showed 65% and VFLS₆ 163% larger amount of callus at the cis-cortex. There wasn’t a significant difference in the amount of callus at the cis and trans-cortex in groups featuring variable fixation only. Investigated biomechanical variables were not significantly different among groups and histology showed comparable good healing in all groups. Tissues adjacent to the implants did not show any alteration of the normal structure in all groups.

Conclusions

Variable fixation promoted the formation of a larger amount of bone callus, equally distributed at the cis and trans cortices. The histological and biomechanical properties of the variable fixation callus were equivalent to those of the standard fixation callus. The magnitude of variable fixation had a biological effect on the formation of bone callus. At the implantation site, the usage of variable fixation did not raise additional concerns with respect to standard fixation. The formation of a larger amount of mature callus suggests that fractures treated with variable fixation might have a higher probability to bridge the fracture gap. The conditions where its usage can be most beneficial for patients needs to be clinically defined.

Assessment of the efficacy of the far cortical locking technique in proximal humeral fractures: a comparison with the conventional bi-cortical locking technique

Background

Locking plate fixation is one of the treatment strategies for the management of proximal humeral fractures. However, stiffness after locking plate fixation is a clinical concern. The mechanical stiffness of the standard locking plate system may suppress the interfragmentary motion necessary to promote secondary bone healing by callus formation. The far cortical locking (FCL) technique was developed to address this limitation in 2005. FCL increases construct flexibility and promotes callus formation. Our study aimed to evaluate the clinical and radiological outcomes of the FCL technique when implemented in proximal humeral fracture management. Furthermore, we compared the surgical outcomes of FCL with those of the conventional bicortical locking (BCL) screw fixation technique.

Methods

Forty-five consecutive patients who had undergone locking fixation for proximal humeral fractures were included in this study. A proximal humeral locking plate (PHILOS) system with BCL screw fixation was used in the first 27 cases, and the periarticular proximal humeral locking plate with FCL screw fixation was used in the final 18 consecutive cases. Functional capacity was assessed using the constant score, American Shoulder and Elbow Surgeons (ASES) score, and range of motion. Radiographic outcomes were evaluated using the Paavolainen method of measuring the neck-shaft angle (NSA).

Results

No significant differences in clinical outcomes (ASES score, constant score, and range of motion) were found between the two groups. The union rate at 12 weeks was significantly higher in the FCL group (94.4%) than in the BCL group (66.7%, p = 0.006). No significant differences in NSA were found between the two treatment strategies. The complication rate was not significantly different between the two groups.

Conclusions

When implemented in proximal humeral fractures, the FCL technique showed satisfactory clinical and radiological outcomes as compared with the conventional BCL technique. The bone union rate at 12 weeks after surgery was significantly higher in the FCL group than in the BCL group. However, no significant difference in the final bone union rate was found between the two groups.

Biomechanical design using in-vitro finite element modeling of distal femur fracture plates made from semi-rigid materials versus traditional metals for post-operative toe-touch weight-bearing

This proof-of-concept study designs distal femur fracture plates from semi-rigid materials vs. traditional metals for toe-touch weight-bearing recommended to patients immediately after surgery. The two-fold goal was to (a) reduce stress shielding (SS) by increasing cortical bone stress thereby reducing the risk of bone absorption and plate loosening, and (b) reduce delayed healing (DH) via early callus formation by optimizing axial interfragmentary motion (AIM). Finite element analysis was used to design semi-rigid plates whose elastic moduli E ensured plates permitted AIM of 0.2 - 1 mm for early callus formation. A low hip joint force of 700 N (i.e. 100% x body weight) was applied, which corresponds to a typical 140 N toe-touch foot-to-ground force (i.e. 20% x body weight) recommended to patients after surgery. Analysis was done using 2 screw materials (steel or titanium) and types (locked or non-locked). Steel and titanium plates were also analyzed. Semi-rigid plates (vs. metal plates) had lower overall femur/plate construct stiffnesses of 508 - 1482 N/mm, higher cortical bone stresses under the plate by 2.02x - 3.27x thereby reducing SS, and lower E values of 414 - 2302 MPa to permit AIM of 0.2 - 1 mm thereby reducing DH.

A biomechanical matched-pair comparison of two different locking plates for tibial diaphyseal comminuted fracture: carbon fiber-reinforced poly-ether-ether-ketone (CF-PEEK) versus titanium plates

Background

Several methods have been proposed to reduce plate construct stiffness and promote secondary bone healing. In this study, we explored the stiffness and strength of the new carbon fiber-reinforced poly-ether-ether-ketone (CF 50) plate compared with the titanium alloy plate (Ti6Al4V).

Methods

Titanium and CF-PEEK locking plates were tested in a tibial non-osteoporotic diaphyseal comminuted fracture model to determine construct stiffness in axial compression, torsion, and bending. Subsequently, constructs were loaded until construct failure to determine construct strength.

Results

Relative to the titanium locking plate, the stiffness of the CF-PEEK locking plate was 6.8% and 30.8% lower in 200 N and 700 N axial compression, respectively (P < 0.05), 64.9% lower in torsion (P < 0.05), and 48.9% lower in bending (P < 0.05). The strength of the CF-PEEK locking plate was only 2.6% lower under axial compression, 7.8% lower in torsion, and 4.8% lower in bending than the titanium locking plate (P > 0.05).

Conclusions

The CF-PEEK locking plate significantly reduced axial, torsion, and bending stiffness compared with the titanium locking plate. Nonetheless, axial, torsional, and bending strength showed only a modest reduction. Considering its other advantages, which include radiolucency and artifact-free imaging, the CF-PEEK locking plate therefore deserves further clinical investigation.

Biomechanical evaluation of the docking nail concept in periprosthetic fracture fixation around a stemmed total knee arthroplasty

Intramedullary femoral nails provide an ideal mechanical axis for periprosthetic fracture fixation. Slotted nails allow a connection to a total knee arthroplasty (TKA) stem. This study aims to compare implant and construct stiffness, interfragmentary movement and cycles to failure between an antegrade slotted femoral nail construct docked to a TKA stem and a distal femoral locking plate in a human periprosthetic femoral fracture model. In eight pairs of fresh-frozen human femora with stalked TKA, a 10 mm transverse osteotomy gap was set simulating a Rorabeck type II, Su type I fracture. The femora were pairwise instrumented with either an antegrade slotted nail coupled to the prosthesis stem, or a locking plate. Cyclic testing with a progressively increasing physiologic loading profile was performed at 2 Hz until catastrophic construct failure. Relative movement at the osteotomy site was monitored by means of optical motion tracking. In addition, four-point bending implant stiffness, torsional implant stiffness and frictional fit of the stem-nail connection were investigated via separate non-destructive tests. Intramedullary nails exhibited significantly higher four-point bending and significantly lower torsional implant stiffness than plates, P < 0.01. Increasing difference between nail and stem diameters decreased frictional fit at the stem-nail junction. Nail constructs provided significantly higher initial axial bending stiffness and cycles to failure (200 ± 83 N/mm; 16'871 ± 5'227) compared to plate constructs (93 ± 35 N/mm; 7'562 ± 1'064), P = 0.01. Relative axial translation at osteotomy level after 2'500 cycles was significantly smaller for nail fixation (0.14 ± 0.11 mm) compared with plate fixation (0.99 ± 0.20 mm), P < 0.01. From a biomechanical perspective, the docking nail concept offers higher initial and secondary stability under dynamic axial loading versus plating in TKA periprosthetic fracture fixation.

Effects of Bone-Plate Material on the Predicted Stresses in the Tibial Shaft Comminuted Fractures: A Finite Element Analysis

PURPOSE

In this research, low modulus carbon fiber (CF)-reinforced polyetheretherketone composite plates (CF-PEEK plates) were compared with traditional metal plates using finite element analysis to establish a reference for clinical application.

MATERIAL AND METHODS

Plates of stainless steel, titanium alloy (Ti6Al4V), or CF-PEEK with different carbon fiber reinforcement ratios (CF30, CF50, and CF60) were used to fix the tibial shaft comminuted fracture. The maximum stress, the maximum displacement of fracture and the stress shielding of cortex bone were analyzed.

RESULTS

Under 200 N axial compression, the maximum displacement was measured in the CF30 plate (4.62 mm) and the minimum in the stainless steel plate (0.23 mm). The stress shielding rates of stainless steel, titanium, CF30, CF50, and CF60 plates were 59.4%, 54.4%, 23.75%, 48.75% and 66.25%. Under 700 N axial compression, the internal fixation by the CF30 plate failed. Among the other 4 plates, the maximum displacement was measured in the CF50 plate (2.52 mm) and the minimum in the stainless steel plate (0.78 mm). The stress shielding rate of plates made of stainless steel, titanium, CF50, and CF60 were 57.1%, 52.0%, 48.1%, and 67.8%.

CONCLUSIONS

CF50 plates can be safely used in the tibial shaft comminuted fracture. The micromotion in the CF50 and CF60 plate was more beneficial to callus formation and fracture healing. The stress shielding of the cortex bone under the CF50 plate was the lowest. The finite element analysis indicated that the CF-PEEK material is worthy of further study because of its biomechanical advantages.

Analysis of risk factors for revision in distal femoral fractures treated with lateral locking plate: a retrospective study in Chinese patients

BACKGROUND

To analyze the risk factors of revision operation after the treatment of distal femoral fracture with lateral locking plate (LLP).

METHODS

Retrospective analysis of the clinical data of 152 cases with distal femoral fracture treated in our hospital from March 2005 to March 2019. The SPSS 26.0 software (univariate analysis and logistic regression analysis) was used to analyze the general condition, fracture-related factors, operation-related factors, and construct characteristics of internal fixation.

RESULTS

Sixteen of 152 patients who were included in the study underwent revision surgery, with a revision rate 10.5%. Univariate analysis showed that there were significant differences in age, body mass index (BMI), fracture type, supracondylar involved or not, type of incision, quality of reduction, ratio of length of plate/fracture area (R1), the ratio of the length of the plate/fracture area above the condylar (R2), ratio of distance between proximal part of fracture and screw/working length of proximal plate (R3) between the two groups (P < 0.05). Logistic regression analysis showed that age [OR for age > 61.5 group is 4.900 (1.071-22.414)], fracture type [OR for A3 fracture is 8.572 (1.606-45.750), the OR for periprosthetic fracture after TKA is 9.073 (1.220-67.506)], poor reduction quality [OR is 7.663 (1.821-32.253)], and the ratio of the length of the plate/fracture area above the condylar were the possible risk factors (P < 0.05).

CONCLUSION

Age, fracture type (A3 and periprosthetic fracture after TKA), poor reduction quality, and the ratio of the length of the plate/fracture area above the condylar were the possible risk factors of the revision in distal femoral fractures treated with lateral locking plate. The appropriate application of the locking plate and operation strategy are the key to reduce the revision rate in distal femoral fractures.

Use of a Titanium Cage and Intramedullary Nails to Treat Distal Femoral Fracture Nonunion in a Patient with Renal Osteopathy: A Case Report

BACKGROUND Nonunion occurs to approximately 10% of people who suffer from distal femoral fracture, which can be induced by other diseases and medical interventions. CKD and subsequent renal osteopathy are regarded as risk factors for nonunion. Internal fixation is the most widely applied medical procedure to treat distal femoral fracture, the efficiency and stability of which are improved by emerging biological materials. Besides traditional screws and plate, titanium cages and intramedullary nails have been introduced lately to repair nonunion and large bone defects resulting from it, which is a huge challenge for orthopedic surgeons. To the best of our knowledge, this is the first report on a distal femoral fracture patient with renal osteopathy treated by internal fixation enhancement using a titanium cage and intramedullary nails. CASE REPORT We report the case of an 84-year-old Chinese woman with renal osteopathy who underwent 4 internal fixation operations to treat a distal femoral fracture. The first 3 surgeries used screws and a plate as internal fixation materials to treat the fracture and nonunion, but did not achieve satisfactory outcomes. In the final surgery, a titanium cage and intramedullary nail were used and the patient recovered soon. CONCLUSIONS Doctors should pay attention to patient's primary health conditions, especially renal disorders, before performing surgeries for distal femoral fracture. It is important to select the most appropriate materials and choose the most suitable surgical method in patients with poor health conditions.

Early fixation failure of locked plating in complex distal femoral fractures: Root causes analysis

BACKGROUND/PURPOSE

Orthopaedic Trauma Association (OTA) C-type distal femoral fractures can be very challenging to treat effectively. While locked plating is widely used in the complex distal femoral fracture, failure of locked plate fixation is not uncommon. First, we tried to determine the risk factor related to early failure of multiplanar OTA C-type fracture in the distal femur after fixation with lateral locked plate. Second, we tried to provide a strategy for surgeons to prevent pitfalls of early failure in the complex distal femoral fractures treated with lateral locked plating.

METHODS

We retrospectively reviewed 44 adults with OTA C-type fractures of the distal femur treated with locked plate fixation between 2010 and 2016 at Tri-Service General Hospital. Average length of follow-up was 27.6 months (range, 12-54 months). Univariate and multivariate logistic regression were used to determine the association of variables on early failure of fixation. A p-value < 0.05 in univariate and multivariate analyses were considered significant.

RESULTS

There were six patients experiencing early failure, and the early failure rate was 13.6%. The risk factors associated with early failure of complex distal femoral fracture identified by univariate analysis included sagittal oblique fracture pattern, longer working length and post-operative sagittal malalignment (odds ratio [OR] and 95% confidence intervals [CI]: 90.00 (6.85-1183.33), 0.55 (0.31-0.98) and 8.63 (1.077-69.075) respectively). The multivariate analysis showed only sagittal oblique fracture pattern was associated with early failure [OR: 52.348 (3.06-895.23)].

CONCLUSION

Sagittal oblique fracture was more likely to result in early postoperative failure. Early recognition of the fracture pattern should be considered to avoid catastrophic results.

Controversies in Fracture Healing: Early Versus Late Dynamization

Dynamization of fracture fixation constructs provides early rigidity for primary bone healing and late motion for secondary healing. A review of laboratory, animal, and clinical studies investigating the impact, and optimal timing, of dynamization is limited by lack of standardization across studies. However, in animal models, dynamization improves histologic and biomechanical properties compared with statically rigid or flexible controls. In animals, dynamization at 3 to 4 weeks showed improved histologic results. In clinical studies, it showed faster, stronger, and stiffer bone healing. Clinical success dynamizing external fixators and intramedullary nails suggests a role for late dynamization in other fixation types, such as bridge plating. [Orthopedics. 2020;43(3):e125-e133.].

Comparative analysis of the biomechanical behavior of anterograde/retrograde nailing in supracondylar femoral fractures

Supracondylar femoral fractures account for a noticeable percentage of the femoral shaft fractures, affecting two etiological groups: high energy trauma in young men, with good bone quality, and older women with osteoporotic femur. Surgical treatment of those kind of fractures remains controversial, with different surgical options such as plate and sliding barrel locking condylar plate, less invasive stabilization system (LISS) or intramedullary nailing, which has emerged as a new fixation choice in the treatment of that type of fractures. The present work performs a comparative study about the biomechanical behavior of anterograde and retrograde nailing in supracondylar femoral fractures type A, in order to determine the best choice of nailing and locking configuration. A three-dimensional finite element model of the femur was developed, modeling femoral supracondylar fracture and different nailing configurations, both for anterograde and retrograde nails. The study was focused on the immediately post-operative stage, verifying the appropriate stability of the osteosynthesis. The obtained results show a better biomechanical behavior for anterograde nails, providing a better stability from the point of view of global movements, lower stresses in screws, and less stress concentration in cortical bone. So, for the analyzed fractures and osteosyntheses types, anterograde nailing has demonstrated to be a better surgical option, being an excellent indication in supracondylar fractures of femur, with clear benefits compared to retrograde nailing, providing a better stabilization which enables for a more satisfactory fracture healing.

Radiostereometric Analysis of Stability and Inducible Micromotion After Locked Lateral Plating of Distal Femur Fractures

OBJECTIVES

To evaluate interfragmentary motion over 1 year after distal femoral fracture fixation using radiostereometric analysis (RSA). The secondary aim was to assess whether RSA data are consistent with diagnoses of nonunion.

DESIGN

Prospective cohort study.

SETTING

Level I urban trauma center.

PATIENTS

Sixteen patients between 22 and 89 years of age with distal femoral fracture (OTA/AO type 33).

INTERVENTION

All fractures were treated with a lateral locking plate, and tantalum markers were inserted into the main proximal and distal fracture fragments. RSA was performed at 2, 6, 12, 18, and 52 weeks postoperatively. Both unloaded and loaded RSA measurements were performed.

MAIN OUTCOME MEASUREMENTS

Unloaded fracture migration over time and inducible micromotion at the fracture site in the coronal plane were determined at each follow-up interval.

RESULTS

RSA precision in the coronal plane of interfragmentary motion over time and inducible micromotion were 1.2 and 0.9 mm in the coronal plane, respectively. Two cases required revision surgery for nonunion 1 year postoperatively. For cases of union, unloaded fracture migration stopped being detectable between 12 and 18 weeks, and inducible micromotion was no longer detectable by the 12-week visit. For cases of nonunion, both unloaded migration and inducible micromotion were detected throughout the study period.

CONCLUSIONS

RSA may be used to reliably assess distal femoral fracture healing. RSA revealed differences in cases of union and nonunion by 3 months and more consistently than traditional x-rays.

LEVEL OF EVIDENCE

Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

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

BACKGROUND

A 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.

METHODS

Human 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.

FINDINGS

Axial 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.

INTERPRETATION

An 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.

Clinical outcomes of treatment with locking compression plates for distal femoral fractures in a retrospective cohort

Background

Plate fixation is one of the standard surgical treatments for distal femoral fractures. There are few reports on the relationship between the screw position and bone union when fixing by the bridging plate (relative stability) method.

Methods

This retrospective study included 71 distal femoral fractures of 70 patients who were treated with the locking compression plate for distal femur (DePuy Synthes Co., Ltd, New Brunswick, CA, USA). The following measurements were evaluated and analyzed: (1) bone union rate, (2) bridge span length (distance between screws across the fracture), (3) plate span ratio (plate length/bone fracture length), (4) number of empty holes (number of screw holes not inserted around the fracture), and (5) medial fracture distance (bone fracture distance on the medial side of the distal femur). Patient demographics (age), comorbidities (smoking, diabetes, chronic steroid use, dialysis), and injury characteristics (AO type, open fracture, infection) were obtained for all participants. Univariate analysis was performed on them.

Results

Of 71 fractures, 26 fractures were simple fractures, 45 fractures were comminuted fractures, and 7 fractures resulted in non-union. Non-union rate was significantly higher in comminuted fractures with bone medial fracture distance exceeding 5 mm.

Non-union was founded in simple fractures with bone medial fracture distance exceeding 2 mm, but not significant (p = 0.06). In cases with simple fractures, one non-union case had one empty hole and one non-union case had four empty holes, whereas in cases with comminuted fractures, five non-union cases had two more empty holes.

Conclusions

We concluded that bone fragment distance between fracture fragments is more important than bridge span length of the fracture site and the number of empty holes. Smoking and medial fracture distance are prognostic risk factors of nonunion in distal femoral fractures treated with LCP as bridging plate.

Non-union in lateral locked plating for distal femoral fractures: A systematic review

INTRODUCTION

This study aims to identify patient and intra-operative factors that contribute to non-union in locked lateral plating for distal femoral fractures.

METHODS

Systematic searches of English-language articles in Ovid Medline, PubMed, Embase, Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews were undertaken in February 2018 according to the PRISMA guidelines. The search terms were (fracture or fracture*) AND (distal femur or distal femoral) AND (malunion or non-union). Eligible studies published at any time reported non-union rates and compared patient and intraoperative factors in patients who underwent locked lateral plating for traumatic distal femoral fractures. The quality of included papers was assessed using The Journal of Bone and Joint Surgery levels of evidence (Wright et al., 2003), and further appraised using the Downs and Black score (Downs and Black, 1998).

RESULTS

Eight studies investigating 1380 distal femoral fractures were found to satisfy the inclusion and exclusion criteria. These studies analysed a variety of patient and intra-operative factors that may contribute to non-union. These include high BMI, open fracture, comminution, fracture infection, stainless steel plate material, shorter working length, open reduction and internal fixation when compared with minimally invasive plate osteosynthesis, high construct rigidity scores and purely locking screw constructs.

CONCLUSION

This review has identified multiple factors which potentially contribute to non-union including stainless steel plate material, high construct rigidity scores and purely locking screw constructs. These findings may reflect that overly rigid plating constructs can contribute to non-union. However, they should be taken in the context of heterogeneity amongst included studies, with further research necessary to support these findings.

Modern Implant Options for the Treatment of Distal Femur Fractures

Distal femur fractures occur in a periarticular fracture pattern and disproportionately afflict an aging population. Although the goals of treatment have not changed, the emergence of new surgical techniques and devices has recently been developed and refined to treat this challenging fracture pattern. Treatment options include open reduction and internal fixation with periarticular locking plates, intramedullary nails, or distal femur replacement. Despite rapid adoption, these modern solutions display a concerning complication rate, specifically from nonunion and malunion. The indications for each of these treatment strategies are not well defined and are the subject of current debate. As with the use of any orthopaedic implant, the knowledge of the strengths and weaknesses of each construct is paramount to successful treatment of these fractures. Recently, as the understanding of the biomechanics of distal femur fracture healing has improved, the literature has demonstrated clinical and theoretical improvements in the outcomes after distal femur fracture repair.

A probabilistic-based approach for computational simulation of bone fracture healing

BACKGROUND AND OBJECTIVE

It is widely known that bone fracture healing is affected by mechanical factors such as fracture geometry, fixation configuration and post-operative weight bearing loading. However, there are several uncertainties associated with the magnitude of the mechanical factors affecting bone healing as it is challenging to adjust and control them in clinical practice. The current bone fracture healing investigations mainly adopt a deterministic approach for identifying the optimal mechanical conditions for a favourable bone healing outcome. However, a probabilistic approach should be used in the analysis to incorporate such uncertainties for prediction of bone healing.

METHODS

In this study we developed a probabilistic-based computational model to predict the probability of delayed healing or non-union under different fracture treatment mechanical conditions for fractures stabilised by locking plates.

RESULTS

The results show that there is a strong positive linear correlation between the mechanical stimulations (S) in the fracture gap and the magnitude of weight bearing, the bone-plate distance (BPD) and the plate working length (WL), whereas the fracture gap size has a highly negative and nonlinear correlation with S. While the results show that fracture mechanical microenvironment is more sensitive to the uncertainties in WL compared to BPD, the uncertainty associated with the magnitude of WL is very low and can be resulted from implant manufacturing tolerance. However, there is a high uncertainty associated with the magnitude of BPD as it cannot be accurately adjusted during the surgery. The results show that the tissue differentiation at the far cortex of fracture gap is more sensitive to the variation of BPD compared with that at the near cortex. The probability of delayed healing (fibrous tissue formation) at far cortex is increased from 0% to 40% when coefficient of variation (COV) of BPD rises from 0.1 to 0.9 (for average BPD = 2 mm, WL = 65 mm, fracture gap size = 3 mm and Weight bearing = 150 N). Further, both near and far cortex of fracture site are sensitive to the variation in weight bearing loading.

CONCLUSIONS

The developed probabilistic model may lead to useful guidelines that could help orthopaedic surgeons identify how reliable a specific fracture treatment strategy is.

Plate-on-plate technique for treating peri-implant fractures of distal femoral locking plate: a retrospective study of 11 patients

INTRODUCTION

In this study, we aimed to ascertain the feasibility and reliability of the plate-on-plate technique for peri-implant fractures of the distal femoral locking plate when the distal femoral fracture is still unhealed.

MATERIALS AND METHODS

From January 2007 to December 2016, we enrolled 11 patients who received treatment at our institution. All patients underwent at least 1 year of follow-up. Their medical records, imaging studies, visual analogue scores, walking ability, complications, and functional outcomes at 1 year postoperative based on the Short Form (36) Health Survey (SF-36) scores were retrospectively evaluated.

RESULTS

The average follow-up duration was 20.5 (range 15-30) months. All fractures united with satisfactory alignment, and the average time for union was 27.5 (range 16-40) weeks. The average SF-36 scores at 1 year postoperative was 79.2 (range 72-90). Regarding ambulatory status, all patients could perform unrestricted outdoor ambulation.

CONCLUSION

In our case series, the plate-on-plate technique achieved a good bone union rate and functional outcomes with low complication rates and thus may be a good alternative for managing this difficult type of fracture.

Clinical outcomes in periarticular knee fractures with flexible fixation using far cortical locking screws in locking plate: a prospective study

PURPOSE

Periarticular fractures around the knee joint are treated traditionally by locking plates which provide excellent stability but suppress callus formation. Far cortical locking (FCL) screws allow axial motion and enhance uniform callus formation. Our study aims to evaluate the outcomes of FCL screws in traditional locking plate in periarticular fractures of the knee.

METHODS

Thirty patients with periarticular fractures of the knee joint were operated with locking plate using FCL screws. All patients were evaluated clinically and radiographically using X-rays at 6, 12, 24 weeks, 1 year and with CT scan at 12-weeks follow-up.

RESULTS

The average time for complete union was 20 weeks in tibial fractures and 24 weeks in femur fractures. Average time to full weight bearing ambulation was 4.8 ± 0.93 weeks. One patient had delayed union in which union was complete after 9 months.

CONCLUSION

This study shows that FCL screws in locking plates allow uniform callus formation and fracture union with minimal complication rates.

The risk of loosening of extramedullary fracture fixation devices

Extramedullary devices that use screws, pins or wires are used extensively to treat fractures in normal and diseased bone. A common failure mode is implant loosening at the bone-screw/pin/wire interface before fracture healing occurs. This review first considers the fundamental mechanics of the bone-fixator construct with focus on interfacial strains that result in loosening. It then evaluates the time-independent and time-dependent material models of bone that have been used to simulate and predict loosening. It is shown that the recently developed time-dependent models are capable of predicting loosening due to cyclic loads in bone of varying quality.

Radiographic Healing of Far Cortical Locking Constructs in Distal Femur Fractures: A Comparative Study With Standard Locking Plates

OBJECTIVES

To investigate the radiographic healing of far cortical locking (FCL) construct fixation in distal femur fractures compared with traditional locking plate (LP) constructs.

DESIGN

A retrospective cohort of 143 consecutive patients with 146 distal femur fractures.

SETTING

Level I trauma center.

PATIENTS/PARTICIPANTS

After excluding patients with OTA/AO type B fractures, referred nonunion cases, patients younger than 16 years, and patients with less than 24 weeks of follow-up, 69 patients with 70 total fractures were included for analysis.

INTERVENTION

AP and lateral knee radiographs were blinded to type of screws and individually reviewed by 3 orthopaedic trauma surgeons.

OUTCOME MEASUREMENTS

The modified RUST (mRUST) score was our primary outcome measure. mRUST scores were assigned at 6, 12, and 24 weeks and final follow-up based on AP and lateral radiographs and compared between FCL and LP groups as a tool for evaluating fracture healing. Secondary outcomes compared between FCL and LP included union rate and postoperative complications.

RESULTS

Statistically significant differences in mRUST scores were noted between FCL and LP groups at 6 weeks (P = 0.040), 12 weeks (P = 0.034), 24 weeks (0.044), and final follow-up (P = 0.048). There was no significant difference in union or specific complication rates between the 2 groups. The union rate was 90.5% and 82.1% for the FCL and LP groups, respectively, at final follow-up.

CONCLUSIONS

To our knowledge, this is the first comparative study between FCL and LP constructs. The FCL group was noted to have significantly higher mRUST scores at all periods indicating increased callus formation, but the differences seen were small and there were no differences in healing rates or complications between the 2 groups, thus bringing the clinical benefit of FCL into question. Further prospective study designs are needed to compare FCL with LP constructs and to investigate the role of interfragmentary motion on callus formation in distal femur fractures.

LEVEL OF EVIDENCE

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

Comparison of outcomes and analysis of risk factors for non-union in locked plating of closed periprosthetic and non-periprosthetic distal femoral fractures in a retrospective cohort study

BACKGROUND

The primary aim was to compare the outcomes of locked plating of closed distal femur periprosthetic and non-periprosthetic fractures by testing the hypothesis that outcomes would be worse in the periprosthetic group. The secondary aim of this study was to identify risk factors for non-union.

METHODS

A single-center study over an 8-year period utilizing a retrospective cohort design was performed. Sixty-eight patients with periprosthetic fractures and 57 patients with non-periprosthetic fractures met inclusion criteria for the study. There was a significant difference between groups in mean age (80.1 years periprosthetic vs. 70.9 years non-periprosthetic (p < 0.001)). Statistical analysis between groups was used to assess the outcomes of time to union, incidence of non-union, post-operative functionality, incidence of complications, progression to revision surgery, and mortality. A secondary multivariable analysis was used to assess risk factors for non-union and factors positively associated with union.

RESULTS

There were no significant differences in outcomes between groups. Union rates were 83.8% (57/68) in the periprosthetic group and 78.9% (45/57) in the non-periprosthetic group (p = 0.648). Comminution was identified as a significant risk factor for non-union (p = 0.005). Use of a submuscular technique had a significant positive association with union (p = 0.006).

CONCLUSIONS

Outcomes of surgical treatment for periprosthetic and non-periprosthetic distal femur fractures are similar. There is a significant risk of non-union in locked plating of both groups.

Outcomes of distal femoral fractures treated with minimally invasive plate osteosynthesis versus open reduction internal fixation with combined locking plate and interfragmentary screws

PURPOSE

Fractures of the distal femur remain challenging to treat, and numerous fixation methods are designed to promote stability and fracture healing. Locking plate constructs have recently become the mainstream fixation method, but debate exists on whether to use locking plates alone or to augment them with interfragmentary screws. This article compares outcomes of distal femur fractures treated with a single locking plate alone versus those treated with a locking plate and interfragmentary screws.

METHODS

We retrospectively reviewed 57 patients treated for distal femur fractures from 2010 to 2013. Patients were divided into two groups: Those treated with a locking plate alone utilizing the minimally invasive plate osteosynthesis (MIPO) technique and those treated with combination of a locking plate and interfragmentary screws using an open technique. Postoperative outcomes were obtained via a manual chart review. Fracture healing and callus indices were evaluated from radiographs.

RESULTS

9 patients required revision surgery in the locking plate alone group (6 for persistent nonunion and 3 for varus deformity). Only two patients in the combination group required revisions (both for nonunion). Average time to full weight bearing was 19.54 weeks in the locking plate group versus 14.57 weeks in the combination group (p = 0.004). At the time of full weight bearing, frontal (1.15 versus 1.11, p = 0.004) and sagittal (1.22 versus 1.15, P = 0.008) callus indices were both significantly greater in the locking plate group.

CONCLUSIONS

In this study, the combination of a locking plate and interfragmentary screws achieved suitable stability and a faster time to full weight bearing than using a locking plate alone. Surgeons should consider combining a locking plate with interfragmentary screws as an effective method for fixation of distal femur fractures, particularly in cases when plate fixation alone fails to provide adequate fracture stability.

Locked Plating and Advanced Augmentation Techniques in Osteoporotic Fractures

"The incidence of osteoporotic fracture is increasing with the aging US population. Because osteoporosis leads to a decrease in bone mineral density with a decrease in both trabecular and cortical bones, osteoporotic fracture presents fixation challenges with standard plate and screw constructs. Locked plating has been developed to create a fixed-angle plate-screw construct that is more resistant to failure in osteoporotic bone. Endosteal replacement, additional plates, and cement augmentation have all been demonstrated to further supplement osteoporotic fracture fixation. Technologies on the horizon to treat osteoporotic fracture include SMV screws, hydroxyapatite-coated implants, and far cortical locking screws."

Importance of a moderate plate-to-bone distance for the functioning of the far cortical locking system

The far cortical locking (FCL) system, a novel bridge-plating technique, aims to deliver controlled and symmetric interfragmentary motion for a potential uniform callus distribution. However, clinical data for the practical use of this system are limited. The current study investigated the biomechanical effect of a locking plate/far cortical locking construct on a simulated comminuted diaphyseal fracture of the synthetic bones at different distance between the plate and the bone. Biomechanical in vitro experiments were performed using composite sawbones as bone models. A 10-mm osteotomy gap was created and bridged with FCL constructs to determine the construct stiffness, strength, and interfragmentary movement under axial compression, which comprised one of three methods: locking plates applied flush to bone, at 2 mm, or at 4 mm from the bone. The plate applied flush to the bone exhibited higher stiffness than those at 2 mm and 4 mm plate elevation. A homogeneous interfragmentary motion at the near and far cortices was observed for the plate at 2 mm, whereas a relatively large movement was observed at the far cortex for the plate applied at 4 mm. A plate-to-bone distance of 2 mm had the advantages of reducing axial stiffness and providing nearly parallel interfragmentary motion. The plate flush to the bone prohibits the dynamic function of the far cortical locking mechanism, and the 4-mm offset was too unstable for fracture healing.

Clinical effects and risk factors of far cortical locking system in the treatment of lower limb fractures

INTRODUCTION

This study aims to analyze clinical effects between far cortical locking (FCL) system and standard plating techniques in the treatment of lower limb fractures and identify potential preoperative risk factors for complications in patients treated with FCL system.

METHOD

We retrospectively analyzed 76 patients treated with FCL system (the study group) and 68 patients treated with standard plating techniques (the control group) between January 2014 and January 2017. Patients were followed up for a minimum of one year. Surgery-related complications, fixation features, fracture healing rates, the radiographic union scores, and knee functions (Kolment scores) were analyzed between the two groups in the study. Besides, we analyzed eight preoperative characteristics for surgery-related complications, including age, gender, presence of risk factors affecting bone healing, cause of injury, AO/OTA fracture classifications, facture sites, presence of open fractures, and presence of bone losses.

RESULTS

The distributions of baseline date were similar between the two groups (P＞0.05). The average number of FCL screws was 4.5 (range: 3-9) in the study group. The average time to union was 2.8 ± 0.9 months in the study group and 3.6 ± 1.0 months in the control group (P＜0.001), and average time to whole weight bearing was 2.3 ± 0.8 months and 2.8 ± 1.2 months, respectively (P = 0.004). Regarding radiographic union score, the study group scores were significantly higher than the control group scores at 1 and 3 months after surgery (P＜0.001), while it becomes insignificant between the two groups at 6 and 12 months after surgery (P = 0.19 and P = 0.15).The working lengths, fracture healing rates, complication rates, and Kolment scores were similar between the two groups (P＞0.05). In the multivariate analysis, fracture sites (OR = 5.34; 95% CI, 1.11-25.75; P = 0.03) and presence of open fractures (OR = 6.19; 95% CI, 1.05-36.38; P = 0.04) were significant associated with complications, whereas other variables were not included.

DISCUSSION

FCL system can truly accelerating bone healing and allow earlier whole weight bearing. Fracture healing rates and complication rates were similar between patients treated with FCL implants or conventional plating techniques. Patients with shaft fractures and open fractures trended to have higher complication rates.

CONCLUSIONS

FCL system is superior to standard plating technique in terms of early callus formation, but standard plating technique is not inferior to FCL system in terms of final fracture healing, surgery-related complication, and function outcome. Fracture site and presence of open fracture are the independent factors for complications in patients treated with FCL system.

Far Cortical Locking Fixation of Distal Femur Fractures is Dominated by Shear at Clinically Relevant Bridge Spans

OBJECTIVES

Far cortical locking (FCL) constructs have been shown to increase axial interfragmentary displacement while limiting shear and have been specifically recommended in the treatment of distal femur fractures. However, there is no available data regarding their mechanical behavior within the range of bridge spans typically used for comminuted distal femur fractures. This biomechanical study of distal femur locked plate fixation assessed 4 methods of diaphyseal fixation for associated axial and shear displacement at bridge spans typically used in clinical practice.

METHODS

Distal femur locking plates were used to bridge simulated fractures in femur surrogates with 4 different methods of diaphyseal fixation (bicortical locking, bicortical nonlocking, near cortical locking, and FCL). Axial and shear displacement were assessed at 5 different bridge spans for each fixation method.

RESULTS

Diaphyseal fixation type was associated with the amount of shear (P = 0.04), but not the amount of axial displacement (P = 0.39). Specifically, FCL constructs demonstrated greater shear than bicortical locking (median 4.57 vs. 2.94 mm, P = 0.02) and bicortical nonlocking (median 4.57 vs. 3.41 mm, P = 0.02) constructs.

CONCLUSIONS

Unexpectedly, FCL constructs demonstrated greater shear than bicortical locking and nonlocking constructs and similar axial displacement for all fixation methods. Bridge span had a dominant effect on displacement that interacted negatively with more flexible FCL diaphyseal fixation. Potentially interactive construct features are best studied in concert. Given the complexity of these relationships, computational modeling will likely play an integral role in future mechanotransduction research.

Low risk of nonunion with lateral locked plating of distal femoral fractures-A retrospective study of 191 consecutive patients

INTRODUCTION

The reported rate of nonunion of distal femoral fractures varies in the literature. Several risk factors for nonunion following lateral locked plating (LLP) have been described. We aimed to study the rate of nonunion, and risk factors thereof, in a Swedish population where fragility fractures are common. A secondary aim was to study risk factors for reoperation for any cause.

PATIENTS AND METHODS

We retrospectively reviewed the hospital files and radiographs of all adult patients admitted to our institution with a distal femoral fracture, from 2004 through 2013. In cases treated with LLP, medical comorbidities, fracture characteristics and implant characteristics were analysed as potential risk factors for nonunion, defined as any surgical intervention to improve healing.

RESULTS

There were 8 cases (4%, 95%CI: 1.8-8.1%) of nonunion in 191 fractures treated with LLP. Patients with nonunion were younger: 62 vs. 81 years (p = 0.009) and more commonly had open fractures: 38% vs. 9% (p = 0.034). No patient 80 years or older had a surgical intervention for nonunion. Lower age was independently associated with reoperation for any cause, but not for nonunion.

DISCUSSION

The low rate of nonunion in this study is probably due to the fact that we present data from a complete cohort from a geographic catchment area. Referral centres with a high proportion of young patients with high-energy injuries, may be better suited for studies on risk factors for nonunion, due to higher statistical power. However, results from such institutions may not be generalizable to the more common low-energy fractures.

Pitfalls and limits of locking plates

The use of locking plates relies on novel mechanical and biological concepts: the bone healing is endochondral because of the elasticity of the constructs. Preoperative planning is required to determine the fracture reduction strategy and select the implants. The type of plate and the type of screws and their position determine the mechanical properties of the construct. Failure of locking plate fixation is a new phenomenon that differs from conventional plate fixation. These are brought on by inadequate planning, which is made worse when minimally invasive surgery is performed. Often, the fracture is not reduced correctly (leading to malunion), the implant length is incorrect, or the screw type, number, location and implantation sequence are inappropriate. Together these can result in an overly rigid construct with poor healing and implant failure or the opposite, an overly flexible construct that can compromise healing. The return to weight bearing after fracture fixation must be adapted to the type of fracture and construct. While locking plates provide better bone purchase, especially in osteoporotic bone, "en bloc" pulling out of the implant is possible. Delayed fractures at the end of the plates are also possible but can be avoided by making the correct biomechanical choices during fixation. For epiphyseal fractures, there are risks of cut-out and impaction of locking screws in cancellous bone related to the fracture pathology. In the long-term, locking plates can be difficult to remove; however, specialized instrumentation can make this easier.

The effect of plate design, bridging span, and fracture healing on the performance of high tibial osteotomy plates: An experimental and finite element study

Objectives

Opening wedge high tibial osteotomy (HTO) is an established surgical procedure for the treatment of early-stage knee arthritis. Other than infection, the majority of complications are related to mechanical factors – in particular, stimulation of healing at the osteotomy site. This study used finite element (FE) analysis to investigate the effect of plate design and bridging span on interfragmentary movement (IFM) and the influence of fracture healing on plate stress and potential failure.

Materials and Methods

A 10° opening wedge HTO was created in a composite tibia. Imaging and strain gauge data were used to create and validate FE models. Models of an intact tibia and a tibia implanted with a custom HTO plate using two different bridging spans were validated against experimental data. Physiological muscle forces and different stages of osteotomy gap healing simulating up to six weeks postoperatively were then incorporated. Predictions of plate stress and IFM for the custom plate were compared against predictions for an industry standard plate (TomoFix).

Results

For both plate types, long spans increased IFM but did not substantially alter peak plate stress. The custom plate increased axial and shear IFM values by up to 24% and 47%, respectively, compared with the TomoFix. In all cases, a callus stiffness of 528 MPa was required to reduce plate stress below the fatigue strength of titanium alloy.

Conclusion

We demonstrate that larger bridging spans in opening wedge HTO increase IFM without substantially increasing plate stress. The results indicate, however, that callus healing is required to prevent fatigue failure.

Cite this article: A. R. MacLeod, G. Serrancoli, B. J. Fregly, A. D. Toms, H. S. Gill. The effect of plate design, bridging span, and fracture healing on the performance of high tibial osteotomy plates: An experimental and finite element study. Bone Joint Res 2018;7:639–649. DOI: 10.1302/2046-3758.712.BJR-2018-0035.R1.

Periprosthetic fracture fixation of the femur following total hip arthroplasty: A review of biomechanical testing - Part II

BACKGROUND

Periprosthetic femoral fracture is a severe complication of total hip arthroplasty. A previous review published in 2011 summarised the biomechanical studies regarding periprosthetic femoral fracture and its fixation techniques. Since then, there have been several commercially available fracture plates designed specifically for the treatment of these fractures. However, several clinical studies still report failure of fixation treatments used for these fractures.

METHODS

The current literature on biomechanical models of periprosthetic femoral fracture fixation since 2010 to present is reviewed. The methodologies involved in the experimental and computational studies of periprosthetic femoral fracture fixation are described and compared with particular focus on the recent developments.

FINDINGS

Several issues raised in the previous review paper have been addressed by current studies; such as validating computational results with experimental data. Current experimental studies are more sophisticated in design. Computational studies have been useful in studying fixation methods or conditions (such as bone healing) that are difficult to study in vivo or in vitro. However, a few issues still remain and are highlighted.

INTERPRETATION

The increased use of computational studies in investigating periprosthetic femoral fracture fixation techniques has proven valuable. Existing protocols for testing periprosthetic femoral fracture fixation need to be standardised in order to make more direct and conclusive comparisons between studies. A consensus on the 'optimum' treatment method for periprosthetic femoral fracture fixation needs to be achieved.

D-hole breakage of 2 angular stable locking plates for medial opening-wedge high tibial osteotomy: Analysis of results from 12 cases

An adequate stable fixation implant should be used for medial opening-wedge high tibial osteotomy (MOWHTO) to promote rapid bone healing without complications. To date, the highest fixation stability has been observed for angular stable locking plates. However, there is still little medical literature regarding breakage of these plates. The purpose of the present study was to report the results of plate breakage around D-hole with the use of both types of locking plate fixation for MOWHTO.Medical records of 12 patients who experienced plate breakage after MOWHTO with either a TomoFix or OhtoFix plate between August 2013 and August 2016 were retrospectively reviewed.A total of 12 patients (7 males and 5 females) who experienced plate breakage at the screw hole just above the osteotomy were evaluated (age, 63 ± 8 years; body mass index (BMI), 28 ± 2 kg/m; opening gap height, 12 ± 2 mm). There were 9 patients (75%) with plate breakage and loss of correction necessitating revision surgery, and 11 patients (92%) had lateral cortical hinge fractures postoperatively. Of the 9 patients with loss of correction necessitating revision surgery, 4 had a TomoFix plate and 5 had an OhtoFix plate. The only statistically significant association with broken plates lost reduction was the presence of lateral cortical hinge fractures (P = .003), but there was no significant association with age, gender, BMI, diabetes, smoking, plate type, opening gap height, and material used to fill the wedge. In addition, mean knee society score in the 12 patients was significantly higher postoperatively than preoperatively (P < .001).Since the amount of plate breakage was just over 1% and with only 12 in total, no true conclusion can be made with certainty. However, in the face of no lateral hinge or cortical disruption, there is a 99% success rate with the plate described. If the lateral hinge is disrupted, a restriction of activity or weight bearing may be needed.

Single-Incision Double-Plating Approach in the Management of Isolated, Closed Osteoporotic Distal Femoral Fractures

INTRODUCTION

Distal femoral fractures in elderly population had recorded an increase in incidence in the last 2 decades. Lateral distal femoral locking plating is considered one of the best options especially when dealing with comminuted fractures but varus collapse of the medial femoral condyle occurs frequently in patients with osteoporosis. Anatomical reduction of the fracture with stable rigid fixation using double-plating approach allows early mobilization of geriatric population and prevents varus collapse minimizing the comorbidities in such fractures.

PATIENTS AND METHODS

Between September 2014 and January 2017, a prospective study on 23 patients with comminuted osteoporotic distal femoral fractures managed through the double-plating approach through a single parapatellar approach has been conducted. Only osteoporotic geriatric patients with isolated distal femoral fractures were included. Polytraumatized, open fractures, and fracture type 33-A1, 33-A2, and 33-B were excluded. The mean age was 69.6 years (61-80). All patients have been evaluated as regard duration of procedure, time to union, EQ-5D-5L score, the need of autologous bone grafts, range of knee motion, and presence of complications.

RESULTS

The average follow-up was 14.1 months. The majority of fractures were type 33-C2 (13 patients). Average procedure time was 148 minutes (117-193 minutes). Mean EQ-5D-5 L score was 83.8 (72-82). Average time to union was 9 months (3-12 months). Four (17.4%) cases needed autologous bone graft after 6 months. No loss of reduction in any of the cases was evident, although 6 (26%) cases had screw breakage or cutout in one of the plate fixation. Two (8.7%) patient developed superficial wound infection and 1 (4.3%) developed DVT.

DISCUSSION

This study aimed at evaluation of the success of double plating of distal femoral fractures in geriatric population. different fixation methods were studied for reduction and fixation of such a fracture such as external fixation, intramedullary nails and lateral plating. the quality of fracture reduction, functional and radiological outcomes, time to union, the need for bone grafting and complication are the main debatable issues.

CONCLUSION

Single-incision double-plating approach for distal femoral osteoporotic fractures is effective and provides stable construct without reduction loss allowing early rehabilitation. Delayed union and the need for bone graft are the major drawbacks for this technique.

Is augmented LISS plating biomechanically advantageous over conventional LISS plating in unstable osteoporotic distal femoral fractures?

Treatment of complex osteoporotic distal femur fractures with the Less Invasive Stabilization System (LISS) has been associated with high complication rates. The aim of this study was to investigate the biomechanical competence of two different techniques of augmented versus conventional LISS plating. Unstable distal femoral fracture AO/OTA 33-A3 was created via osteotomies in artificial femora simulating osteoporotic bone. Three study groups, consisting of 10 specimens each, were created for fixation with either LISS plate, LISS plate with additional polylactide intramedullary graft, or LISS plate plus medial locking plate (double plating). All specimens were non-destructively tested under axial (20-150 N) and torsional (0-4 Nm) quasi-static loading. Each bone-implant construct was tested with two different working length (WL) configurations (long and short) of the LISS plate. Relative movements between the most medial superior and inferior osteotomy aspects were investigated via three-dimensional motion tracking analysis. Double plating revealed significantly smaller longitudinal and shear displacement than the other two techniques (p ≤ 0.001). In addition, LISS plus graft fixation was with significantly less longitudinal displacement in comparison to conventional LISS plating (p < 0.001). Long WL resulted in significantly higher longitudinal and shear displacement compared to short WL for LISS and LISS plus graft (p ≤ 0.032), but not for double plating (p > 0.999). In conclusion, intramedullary grafting resulted in significantly increased fracture stability under axial loading in comparison to conventional LISS plating. Although it was not efficient enough to provide comparable stability to double plating, intramedullary grafting may be considered as a useful biological alternative to the latter in a surgeon's armamentarium. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2604-2611, 2018.

ORIF With Submuscular Plating of an Intercondylar/Supracondylar Distal Femur Fracture

Fractures of the distal femur with intercondylar extension and comminution are challenging cases and demand a thorough preoperative evaluation and execution of proper surgical technique. Identification of the intra-articular fractures, including coronal fractures of the lateral condyle, is important in planning surgery and emphasizes the need for computerized tomography scans. Recent advances with anatomic, locking plates have made minimally invasive surgery easier, but joint reduction needs to be performed meticulously in an open manner, and restoration of the mechanical alignment through plate fixation is essential for a good clinical outcome. Stable fixation that allows for early range of motion and mobilization are essential for the patient's recovery. This video demonstrates open reduction and internal fixation of a high-energy supracondylar/intercondylar distal femur fracture and emphasizes minimally invasive, biologically friendly techniques.

Early Comparative Outcomes of Carbon Fiber-Reinforced Polymer Plate in the Fixation of Distal Femur Fractures

OBJECTIVE

To evaluate the early clinical results of distal femur fractures treated with carbon fiber-reinforced polyetheretherketone (CFR-PEEK) plates compared with stainless steel (SS) lateral locking plates.

DESIGN

Retrospective comparative cohort study.

SETTING

ACS Level I trauma center.

PATIENTS/PARTICIPANTS

Twenty-two patients (11 SS, 11 CFR-PEEK) with closed distal femur fractures treated by a single surgeon over a 6-year period.

MAIN OUTCOME MEASUREMENTS

Nonunion, hardware failure, reoperation, time to full weight-bearing, and time union were assessed.

RESULTS

The CFR-PEEK cohort was on average older (71 vs. 57 years, P = 0.03) and more likely to have diabetes (P = 0.02). Nonunion was diagnosed in 4/11 (36%) patients in the SS group and 1/11 (9%) patients in the CFR-PEEK group (P = 0.12). Hardware failure occurred in 2 SS patients (18%) compared with none in the CFR-PEEK group (P = 0.14). Time to full weight-bearing was similar between groups, occurring at 9.9 and 12.4 weeks in the CFR-PEEK and SS groups, respectively (P = 0.23). Time to radiographic union averaged 12.4 weeks in the SS group and 18.7 weeks in the CFR-PEEK group (P = 0.26). There were 4 reoperations in the SS group and 1 in the CFR-PEEK group (P = 0.12).

CONCLUSIONS

CFR-PEEK plates show encouraging short-term results in the treatment of distal femur fractures with a comparable nonunion, reoperation, and hardware failure rates to those treated with SS plates. This data suggest that CFR-PEEK plates may be a viable alternative to SS plates in fixation of these fractures.

LEVEL OF EVIDENCE

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

Outcomes of Locking-Plate Fixation for Hindfoot Fusion Procedures in 15 Patients

Tibiotalocalcaneal arthrodesis is a salvage procedure for various end-stage foot and ankle pathologic entities. Several factors are known to influence the union rate after these procedures, including construct rigidity. The data on locked plates as a fixation technique have been inconclusive, with variable union rates reported. One recent study suggested that locking plates can lead to high nonunion rates owing to excessive rigidity. The purpose of the present study was to retrospectively examine the outcomes of locking plate fixation. We retrospectively reviewed the cases of 15 patients (7 [46.7%] male, 8 [53.3%] female) who underwent tibiotalocalcaneal, tibiocalcaneal, or tibiotalar arthrodesis fixed with a locking plate from January 2013 to January 2014. The average age was 52.19 ± 5.8 years. The mean follow-up period was 17 ± 5.3 months. We examined the overall union rates and the effects of smoking, diabetes, and rheumatologic status on the union rate. Of the 15 cases, 11 (73.3%) did not achieve union. The mean time to failure was 10 ± 5.3 months. Age, gender, smoking, diabetes, use of augmentation screws outside the plate, and operating surgeon did not have an effect on the failure rate (p > .50). In addition, gender, smoking, and diabetes did not predict for nonunion. The high failure rate of rigid locking plate fixation reported might be attributable to the high incidence of smoking and diabetic comorbidities in our study. However, excessive construct rigidity might play an important role. Larger studies are needed to establish more reliable union rates with the use of locking plates in foot and ankle fusion.

Pre-operative planning for fracture fixation using locking plates: device configuration and other considerations

Most locked plating failures are due to inappropriate device configuration for the fracture pattern. Several studies cite screw positioning variables such as the number and spacing of screws as responsible for occurrences of locking plate breakage, screw loosening, and peri-prosthetic re-fracture. It is also widely accepted that inappropriate device stiffness can inhibit or delay healing. Careful preoperative planning is therefore critical if these failures are to be prevented. This study examines several variables which need to be considered when optimising a locking plate fixation device for fracture treatment including: material selection; screw placement; the effect of the fracture pattern; and the bone-plate offset. We demonstrate that device selection is not straight-forward as many of the variables influence one-another and an identically configured device can perform very differently depending upon the fracture pattern. Finally, we summarise the influence of some of the key parameters and the influence this can have on the fracture healing environment and the stresses within the plate in a flowchart.

Distal femur: dynamization of plating

With advances in osteosynthesis technology providing improved stability of fixation and better outcomes, surgical treatment has become the standard of care for distal femur fractures. Pre-contoured distal femoral locking plates are the most commonly used implants for fixation. However, healing problems such as delayed union, failure of fixation, and /or nonunion are not uncommon. The fixation construct being "too stiff" is a commonly quoted reason when nonunion/failure of fixation occurs on distal femur fractures fixed with a plate. A flexible fixation construct allowing controlled axial micromotion could help stimulate the bone healing. In order to achieve this goal, plating construct stiffness can be modified by several methods.

Comparison of Clinical Efficacy of Lateral and Lateral and Medial Double-plating Fixation of Distal Femoral Fractures

The present study was performed to compare the clinical efficacy of lateral plate and lateral and medial double-plating fixation of distal femoral fractures and explore the indication of lateral and medial double-plating fixation of the distal femoral fractures. From March 2006 to April 2014, 48 and 12 cases of distal femoral fractures were treated with lateral plate (single plate) and lateral and medial plates (double plates), respectively. During the surgery, after setting the lateral plate for the distal femoral fractures, if the varus stress test of the knee was positive and the lateral collateral ligament rupture was excluded, lateral and medial double-plating fixation was used for the stability of the fragments. All the patients were followed up at an average period of 15.9 months. The average operation time, the intraoperative hemorrhage and the fracture union time of the two groups were compared. One year after operation, knee function was evaluated by the Kolmert's standard. There was no significant difference in the average operation time, intraoperative hemorrhage, fracture healing time and excellent and good rates of postoperative knee function between two groups. Positive Varus stress test during operation can be an indication for lateral and medial double-plating fixation of distal femoral fractures.

Lateral locked plating for distal femur fractures by low-energy trauma: what makes a difference in healing?

PURPOSE

The objective of this study is to investigate healing outcome of lateral locked plating for distal femoral fractures caused by low-energy trauma. In addition, we sought to determine predictable factors associated with fracture healing time.

METHODS

Seventy-three patients (73 fractures) with distal femur fractures (AO/OTA type 33) caused by low-energy trauma were recruited. The mean age of patients was 69.8 years (range, 43-87 years). All fractures were stabilized by less invasive osteosynthesis with anatomical periarticular locking system. Patients were followed up for mean 17.3 months (range, 6-44 months).

RESULTS

Of the 73 fractures, 52 (71.2%) fractures showed bony union within 6 months after the index surgery while the remaining 21 (28.8%) fractures showed delayed union or received revision surgery prior to complete healing. Although overall healing rate from the initial surgery was 93.2% (68/73), which seems to be satisfactory, the rate of surgical complications was 11.0% (8/73). Of all 73 fractures, seven received further surgery including three re-osteosynthesis. On multivariable analysis, plate-screw density at the fracture site was an independent predictable factor associated with the problematic healing.

CONCLUSIONS

Our findings suggest that complications related to increased healing time and fixation construct are not infrequent and ongoing problems in managing low-energy distal femur fractures. Specifically, plate-screw density at the fracture site has a significant influence on healing time in these fractures.

Biomechanics-Hot Topics Part II

Orthopaedic surgery and biomechanics are intimately partnered topics in medicine. Biomechanical principles are used to design implants and fashion treatment protocols. Although it would seem that biomechanical principles in the design of fixation devices and fracture repair constructs have been already finalized, there are several points of controversy remaining. New technology has raised new questions, while at the same time, we still do not fully understand simple clinical principles such as time of fracture healing depending on the construct used. This review looks at several of these current controversies to better understand what work is needed in fracture care going forward.