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

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.

[Current status and progress of clinical research on distal femoral fractures]

Objective

To investigate current status and latest progress of clinical research on distal femoral fractures.

Methods

The related literature was extensively reviewed to summarize the trend of the researches and their clinical application in the treatment of distal femoral fractures.

Results

Distal femoral fractures are likely to occur in young people who suffer from high-energy damage and the elderly with osteoporosis, which is always comminuted and unstable fractures, and often involved in the articular surface and combined with serious soft tissue injury. Therefore, the treatment faces many challenges. External fixation is now used as a temporary means of controlling injury. The vast majority of patients are feasible to internal fixation, including plates system and intramedullary nail system. Different internal fixator also has its own characteristics, such as double plates can strengthen the medial support of the femur, less invasive stabilization system protects the blood supply of fractures, distal cortial locking plate is theoretically more fit for the requirements of bone healing, retrograde intramedullary nail can resist varus and valgus.

Conclusion

The treatment of distal femoral fractures should be based on the type of fracture and the characteristics of internal fixators.

[Flexible internal fixation with locking plate for distal femoral fractures]

Objective

To analyze the effectiveness of flexible internal fixation with locking plate for distal femoral fractures.

Methods

Between January 2015 and June 2016, 21 cases of distal femoral fractures were treated. There were 5 males and 16 females with an average age of 62 years (range, 32-88 years). Injury was caused by falling in 14 cases, by traffic accident in 5 cases, and by falling from height in 2 cases. The fractures located at the left side in 13 cases and the right side in 8 cases. Twenty cases were fresh closed fractures and 1 case was open fracture. According to AO/Association for the Study of Internal Fixation (AO/OTA) typing, there were 5 cases of type 33-A1, 3 of type 33-A2, 8 of type 33-A3, 2 of type 33-C2, and 3 of type 33-C3. The time from injury to operation was 3-13 days (mean, 6.5 days).

Results

All operation incisions healed primarily. Eighteen patients were followed up 12-24 months (mean, 16 months). All fractures healed, and the healing time was 8-24 weeks (mean, 16.6 weeks). The articular surface was smooth and the thigh length was recovered. No screw loosening, plate breakage, valgus or varus of the knee, stiff of the knee or non-unions occurred during follow-up. There was no significant difference in visual analogue scale (VAS) score between at 6 and 12 months after operation ( P>0.05), and the difference was significant bewteen the other time points ( P<0.05). There were significant differences in the range of motion of knee between 1 month and 3, 6, 12 months ( P<0.05); there was no significant difference between 3, 6, and 12 months ( P>0.05). There were significant differences in the Neer scores between 1, 3, 6, and 12 months after operation ( P<0.05). According to Neer score criteria, the results were excellent in 12 cases and good in 6 cases at 12 months after operation.

Conclusion

Flexible internal fixation with locking plate for distal femoral fractures can get good functional recovery.

Double plating of intra-articular multifragmentary C3-type distal femoral fractures through the anterior approach

INTRODUCTION

In this prospective case series, we report a mean of 12-month follow-up of the utilization of a dual plating of distal femoral fractures. Our technique included a lateral distal femoral locked plate with a low-contact-locked medial plate and bone graft through an extended medial parapatellar anterior approach for the fixation of C3-type distal femoral fractures.

PATIENTS AND METHODS

Sixteen patients (11 males and 5 females) presented with supracondylar femoral fracture type C3, according to Müller long-bone classification system and its revision OA/OTA classification. These were treated using dual plating through extended anterior approach and bone grafting. Our outcomes included clinical and radiological outcomes. Secondary outcomes included postoperative complications.

RESULTS

The mean time of complete radiological union in the studied population was 6.0 ± 3.5 months with a range of 3-14 months. We have not observed postoperative varus or valgus deformity in our cohort. The majority (68.75%) of the studied patients showed significant improvement in range of motion (90°-120°) during follow-up. Eleven out of sixteen patients (68.75%) had well-to-excellent functional outcome. Poor outcome was reported in only two patients (12.50%).

CONCLUSIONS

Dual plating fixation using anterior approach for type C3 distal femoral fractures is an efficient method of management. It has several advantages such as precise exposure, easy manipulation, anatomical reduction and stable fixation. However, operative indications and instructions should be strictly followed. The surgical technique must be rigorous, and the biomechanical qualities of these implants must be understood to prevent the development of major complications.

Proximal Screw Configuration Alters Peak Plate Strain Without Changing Construct Stiffness in Comminuted Supracondylar Femur Fractures

OBJECTIVES

Assess the effect of proximal screw configuration on the strain in lateral plating of a simulated comminuted supracondylar femur fracture.

METHODS

Fractures were simulated in 12 synthetic femurs by removing a 200-mm section of bone, located 60 mm from the intercondylar fossa and repaired using a 16-hole locked lateral plate instrumented with 8 uniaxial strain gauges. Three proximal screw type configurations were evaluated: (1) 4 nonlocking screws, (2) 4 locking screws, and (3) a hybrid configuration of 2 nonlocking screws flanked by a locking screw at each end of the proximal fragment. Each screw type was compared for 2 working lengths (∼90 and 160 mm). The longer working length was created by removing the proximal screw closest to the fracture gap. Testing consisted of a vertical load (500 N) applied to the head of femur. Configurations were compared using plate strain, construct stiffness, and fracture gap displacement as outcome measures.

RESULTS

Plate strain immediately above the fracture gap was reduced with nonlocking screws compared with the other screw types. Plate strains were reduced around the fracture gap with the longer working length but increased for the nonlocking construct at the location of the removed screw. Construct stiffness was not altered by screw type or working length. An increase in fracture gap displacement was only evident in shear translation with the longer working length.

CONCLUSIONS

Plate strain in lateral plating of supracondylar femur fractures is decreased using nonlocking screws proximal to the fracture. Increasing the working length reduces plate strains over the working length yet should be cautioned because of increased interfragmentary shear motion.

Working length and proximal screw constructs in plate osteosynthesis of distal femur fractures

BACKGROUND

The study purpose is to evaluate the working length, proximal screw density, and diaphyseal fixation mode and the correlation to fracture union after locking plate osteosynthesis of distal femoral fractures using bridge-plating technique.

METHODS

A four-year retrospective review was performed to identify patients undergoing operative fixation of distal femur fractures with a distal femoral locking plate using bridge-plating technique for the metadiaphyseal region. Primary variables included fracture union, secondary surgery for union, plate working length, and diaphyseal screw technique and configuration. Multiple secondary variables including plate metallurgy and coronal plane fracture alignment were also collected.

RESULTS

Ninety-six patients with distal femur fractures with a mean age 60 years met inclusion criteria. None of the clinical parameters were statistically significant indicators of union. Likewise, none of the following surgical technique parameters were associated with fracture union: plate metallurgy, the mean working length, screw density and number of proximal screws and screw cortices. However, diaphyseal screw technique did show statistical significance. Hybrid technique had a statistically significant higher chance of union when compared to locking (p=0.02). All proximal locking screw constructs were 2.9 times more likely to lead to nonunion.

CONCLUSIONS

Plating constructs with all locking screws used in the diaphysis when bridge-plating distal femur locking plates were 2.9 times more likely to incur a nonunion. However, other factors associated with more flexible fixation constructs such as increased working length, decreased proximal screw number, and decreased proximal screw density were not significantly associated with union in this study.

Any Cortical Bridging Predicts Healing of Supracondylar Femur Fractures After Treatment With Locked Plating

OBJECTIVES

To determine the accuracy and reliability of radiographic cortical bridging criteria in predicting the final healing of supracondylar femur fractures after treatment with locked plating.

DESIGN

Retrospective review.

SETTING

Two Level 1 trauma centers.

PATIENTS/PARTICIPANTS

Patients who presented with supracondylar femur fractures (OTA/AO 33A, C) and were treated with locking plate fixation between January 1, 2004, and January 1, 2011. The final study population included 82 fractures after excluding patients with open physes (n = 4), nondisplaced fractures (n = 4), early revision for technical failure (n = 4), or inadequate follow-up (n = 42).

INTERVENTION

Distal femur locking plate fixation.

MAIN OUTCOME MEASUREMENTS

Postoperative radiographs until final follow-up were assessed for cortical bridging at each cortex on anterior-posterior and lateral views. Images were analyzed independently by 3 orthopaedic traumatologists to allow for assessment of reliability. Final determination of union required both radiographic and clinical confirmation.

RESULTS

Assessment for any cortical bridging was the earliest accurate predictor of final union (95.1% accuracy at 4 months postoperatively), compared with criteria requiring bicortical bridging (93.9% accuracy at 6 months) and tricortical bridging (78% accuracy at 21 months). Any cortical bridging demonstrated a higher interobserver reliability (kappa = 0.73) relative to bicortical (kappa = 0.27) or tricortical bridging (kappa = 0.5).

CONCLUSIONS

Our results for plate fixation of supracondylar distal femur fractures mirror those previously described for intramedullary nailing of tibia shaft fractures. Any radiographic cortical bridging by 4 months postoperatively is an accurate and reliable predictor of final healing outcome after locking plate fixation of supracondylar femur fractures. Assessment for bicortical or tricortical bridging is less reliable and inaccurate during the first postoperative year.

LEVEL OF EVIDENCE

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

Comparison of 4 Methods for Dynamization of Locking Plates: Differences in the Amount and Type of Fracture Motion

BACKGROUND

Decreasing the stiffness of locked plating constructs can promote natural fracture healing by controlled dynamization of the fracture. This biomechanical study compared the effect of 4 different stiffness reduction methods on interfragmentary motion by measuring axial motion and shear motion at the fracture site.

METHODS

Distal femur locking plates were applied to bridge a metadiaphyseal fracture in femur surrogates. A locked construct with a short-bridge span served as the nondynamized control group (LOCKED). Four different methods for stiffness reduction were evaluated: replacing diaphyseal locking screws with nonlocked screws (NONLOCKED); bridge dynamization (BRIDGE) with 2 empty screw holes proximal to the fracture; screw dynamization with far cortical locking (FCL) screws; and plate dynamization with active locking plates (ACTIVE). Construct stiffness, axial motion, and shear motion at the fracture site were measured to characterize each dynamization methods.

RESULTS

Compared with LOCKED control constructs, NONLOCKED constructs had a similar stiffness (P = 0.08), axial motion (P = 0.07), and shear motion (P = 0.97). BRIDGE constructs reduced stiffness by 45% compared with LOCKED constructs (P < 0.001), but interfragmentary motion was dominated by shear. Compared with LOCKED constructs, FCL and ACTIVE constructs reduced stiffness by 62% (P < 0.001) and 75% (P < 0.001), respectively, and significantly increased axial motion, but not shear motion.

CONCLUSIONS

In a surrogate model of a distal femur fracture, replacing locked with nonlocked diaphyseal screws does not significantly decrease construct stiffness and does not enhance interfragmentary motion. A longer bridge span primarily increases shear motion, not axial motion. The use of FCL screws or active plating delivers axial dynamization without introducing shear motion.

[Titanium or steel as osteosynthesis material : Systematic literature search for clinical evidence]

BACKGROUND

The selection of the appropriate implant material, stainless steel or titanium, is still the decision of the surgeon and/or the affiliated institution. Additionally, remarkable international differences can be found between the different markets, which cannot really be explained.

OBJECTIVE

A systematic literature search was performed to verify whether there is clinical evidence for the preference of one material over the other.

MATERIAL AND METHODS

The systematic literature search was performed utilizing the internet databases PubMed, Cochrane and Web of Science. Comparative studies were included that reported on adult patients with osteosynthesis of extremities after trauma using either stainless steel or titanium implants. Information was extracted about infection rates, incidence of clinically relevant allergies, problems with implant removal and other complications.

RESULTS

A total of 18 publications were identified to be eligible and 2 referenced articles were added. In summary, there is insufficient clinical evidence that the use of titanium or steel implants has a positive or negative effect on fracture healing, shows different rates of allergies, different rates of infections or mechanical failure. No supporting evidence could be identified for the difficulties with removal of titanium implants reported by surgeons.

CONCLUSION

This systematic literature search did not provide any clinical evidence for material-related differences between titanium or stainless steel implants for fracture fixation. Based on the current clinical evidence both titanium and steel implants can be considered to be of equal value. The reported difficulties with implant removal are not reflected in the published literature.

Implant Material, Type of Fixation at the Shaft, and Position of Plate Modify Biomechanics of Distal Femur Plate Osteosynthesis

OBJECTIVES

To investigate whether (1) the type of fixation at the shaft (hybrid vs. locking), (2) the position of the plate (offset vs. contact) and (3) the implant material has a significant effect on (a) construct stiffness and (b) fatigue life in a distal femur extraarticular comminuted fracture model using the same design of distal femur periarticular locking plate.

METHODS

An extraarticular severely comminuted distal femoral fracture pattern (OTA/AO 33-A3) was simulated using artificial bone substitutes. Ten-hole distal lateral femur locking plates were used for fixation per the recommended surgical technique. At the distal metaphyseal fragment, all possible locking screws were placed. For the proximal diaphyseal fragment, different types of screws were used to create 4 different fixation constructs: (1) stainless steel hybrid (SSH), (2) stainless steel locked (SSL), (3) titanium locked (TiL), and (4) stainless steel locked with 5-mm offset at the diaphysis (SSLO). Six specimens of each construct configuration were tested. First, each specimen was nondestructively loaded axially to determine the stiffness. Then, each specimen was cyclically loaded with increasing load levels until failure.

RESULTS

Construct Stiffness: The fixation construct with a stainless steel plate and hybrid fixation (SSH) had the highest stiffness followed by the construct with a stainless steel plate and locking screws (SSL) and were not statistically different from each other. Offset placement (SSLO) and using a titanium implant (TiL) significantly reduced construct stiffness. Fatigue Failure: The stainless steel with hybrid fixation group (SSH) withstood the most number of cycles to failure and higher loads, followed by the stainless steel plate and locking screw group (SSL), stainless steel plate with locking screws and offset group (SSLO), and the titanium plate and locking screws group (TiL) consecutively. Offset placement (SSLO) as well as using a titanium implant (TiL) reduced cycles to failure.

CONCLUSIONS

Using the same plate design, the study showed that implant material, screw type, and position of the plate affect the construct stiffness and fatigue life of the fixation construct. With this knowledge, the surgeon can decide the optimal construct based on a given fracture pattern, bone strength, and reduction quality.

Absolute or relative stability in minimal invasive plate osteosynthesis of simple distal meta or diaphyseal tibia fractures?

INTRODUCTION

Minimal invasive plate osteosynthesis in simple distal meta or diaphyseal tibia fractures can be applied using absolute (lag screw and neutralisation plate; LSN) or relative stability (bridge plate; BP). The primary aim of the study was to compare time to radiological union and time to full weight bearing in the two groups (LSN vs. BP). Reduction was performed either percutaneously or by a minimally open approach (mini open). Secondary aim was to analyse the number of complications between both groups.

METHODS

Retrospective single centre review of patients with a simple distal meta or diaphyseal tibia fracture operated with a Locking Compression Plate (LCP) between 2009 and 2015 in a Level one Trauma Centre. Postoperative radiographs were assessed in a standardised manner. Time to radiological fracture union and time to full weight bearing were observed. Callus index and postoperative complications were analysed.

RESULTS

Fifty-seven patients with a minimum follow-up of 6 months were analysed. Forty-eight patients had a shaft (AO/OTA Type 42) and nine a distal tibia fracture (AO/OTA Type 43). Forty patients were treated with using the LSN concept and 17 patients with the BP concept. Median time to radiological fracture union was statistically significant shorter (p=0.04) in the LSN group with 19 weeks compared to 27 weeks in the BP-group. Time to full weight bearing was 10 weeks in both groups. A total (including implant removal) of 35 reoperations were performed in the LSN-group and 18 in the BP-group. Wound healing disorders (deep surgical site infections) were seen less the LSN group in 3/40 (7.5%) compared to the BP-group with 3/17 (17.6%). In the LSN group, there was no statistical difference in time to union or weight bearing between a percutaneous or mini open approach.

CONCLUSION

Stable osteosynthesis of simple distal meta or diaphyseal tibia fractures leads to faster radiologic fracture healing without an increase in complications or number of revisions compared to bridge plating. If a percutaneous reduction is not feasible for the insertion of a lag screw, a mini-open approach does not lead to a delay in fracture healing.

Dynamic Stabilization of Simple Fractures With Active Plates Delivers Stronger Healing Than Conventional Compression Plating

OBJECTIVES

Active plates dynamize a fracture by elastic suspension of screw holes within the plate. We hypothesized that dynamic stabilization with active plates delivers stronger healing relative to standard compression plating.

METHODS

Twelve sheep were randomized to receive either a standard compression plate (CP) or an active plate (ACTIVE) for stabilization of an anatomically reduced tibial osteotomy. In the CP group, absolute stabilization was pursued by interfragmentary compression with 6 cortical screws. In the ACTIVE group, dynamic stabilization after bony apposition was achieved with 6 elastically suspended locking screws. Fracture healing was analyzed weekly on radiographs. After sacrifice 9 weeks postsurgery, the torsional strength of healed tibiae and contralateral tibiae was measured. Finally, computed tomography was used to assess fracture patterns and healing modes.

RESULTS

Healing in both groups included periosteal callus formation. ACTIVE specimens had almost 6 times more callus area by week 9 (P < 0.001) than CP specimens. ACTIVE specimens recovered on average 64% of their native strength by week 9, and were over twice as strong as CP specimens, which recovered 24% of their native strength (P = 0.008). Microcomputed tomography demonstrated that compression plating induced a combination of primary bone healing and gap healing. Active plating consistently stimulated biological bone healing by periosteal callus formation.

CONCLUSIONS

Compared with compression plating, dynamic stabilization of simple fractures with active plates delivers significantly stronger healing.

A Concert between Biology and Biomechanics: The Influence of the Mechanical Environment on Bone Healing

In order to achieve consistent and predictable fracture healing, a broad spectrum of growth factors are required to interact with one another in a highly organized response. Critically important, the mechanical environment around the fracture site will significantly influence the way bone heals, or if it heals at all. The role of the various biological factors, the timing, and spatial relationship of their introduction, and how the mechanical environment orchestrates this activity, are all crucial aspects to consider. This review will synthesize decades of work and the acquired knowledge that has been used to develop new treatments and technologies for the regeneration and healing of bone. Moreover, it will discuss the current state of the art in experimental and clinical studies concerning the application of these mechano-biological principles to enhance bone healing, by controlling the mechanical environment under which bone regeneration takes place. This includes everything from the basic principles of fracture healing, to the influence of mechanical forces on bone regeneration, and how this knowledge has influenced current clinical practice. Finally, it will examine the efforts now being made for the integration of this research together with the findings of complementary studies in biology, tissue engineering, and regenerative medicine. By bringing together these diverse disciplines in a cohesive manner, the potential exists to enhance fracture healing and ultimately improve clinical outcomes.

Dynamic locked plating for fixation of distal femur fractures using near- cortical over-drilling: Preliminary results of a prospective observational study

INTRODUCTION

Nonunion after locked plating of distal femur fractures is not uncommon. Authors wanted to assess if "Dynamic" locked plating using near-cortex over-Drilling technique would provide a mechanical environment the promotes callus formation, thereby avoiding non-union encountered when applying locked plates with the conventional method.

METHODS

This study was conducted at an academic Level 1 Trauma Center. This is a prospective study conducted from November 2015 to November 2016. Follow-up was 10 months on average (ranging from 8 to 12 months). The study included 20 patients with 20 fractures (13 males, 7 females). The average patients' age was 41.2 years (18-64 years). According to the Müller AO classification of distal femur fractures (33A-C) there were 15 cases with extra-articular fractures (AO 33A), 5 patients with intra-articular fractures (AO 33C). Dynamic Locked plating using near-cortical over-drilling technique was done for all patients. Two blinded observers assessed callus score on 6-week radiographs using a 4-point ordinal scale. A 2-tailed t-test. Two-way mixed intra-class correlation testing was performed to determine reliability of the callus measurements by the 2 observers.

RESULTS

All patients achieved union, time to union was 13.4 weeks on average (range form 8-24 weeks). Delayed union was observed in 2 patients. The average callus score for fractures was 1.8 (SD 0.6). All fractures united in alignment except 1 fracture which united in valgus malalignment, the deformity was appreciated in the postoperative radiographs. No wound related complications, no loss of reduction, no catastrophic implant failure or screw breakage were detected.

CONCLUSION

Dynamic locked plating using near-cortex over-drilling is a simple technique that uses standard locked plates that promotes callus formation when used for fixing distal femur fractures.

Modified fixations for distal femur fractures following total knee arthroplasty: a biomechanical and clinical relevance study

PURPOSE

Distal femur fractures adjacent to total knee arthroplasty are a rare yet complex problem. Recently, extramedullary locking plate and retrograde intramedullary nail fixations have become popular options, but the complication rates associated with these procedures are 15-20 %. Modified fixations were assessed in an effort to reduce complications from unstable periprosthetic fractures.

METHODS

Using experimental and finite element methods, this study compared the construct behaviours of a locking plate, a retrograde intramedullary nail, and their modifications (a spiral-blade supplemented in an intramedullary nail or a locking plate/allograft hybrid) when subjected to various fracture types, locations, loading conditions, and bony strength. The implanted models were used to assess construct stiffness, fracture micromotion, and implant stress under different osteoporotic conditions. Finally, we collected 40 cases for radiological analysis to indicate the appropriate procedure for treating periprosthetic fractures following total knee arthroplasty.

RESULTS

Regardless of the fracture type, femoral constructs fixed with a conventional or spiral-blade supplemented intramedullary nail exhibited higher axial but lower torsional stiffness than those fixed with a locking plate. Torsional deformation occurred if the lower-positioned fracture had no medial support. The locking plate/allograft construct exhibited the highest stiffness and the least micromotion. A review of 40 clinical cases confirmed the above findings regarding the locking plate/allograft construct.

CONCLUSION

The spiral-blade supplement of retrograde intramedullary nail and locking plate/allograft modified constructs significantly stabilizes the unstable fractured gaps. The locking plate/allograft is recommended for the periprosthetic fractures with deficient bone stock and severe osteoporosis to improve alignment and healing potentials.

Stress Modulation of Fracture Fixation Implants

Stress modulation is the concept of manipulating bridge plate variables to provide a flexible fixation construct that allows callus formation through uneventful secondary bone healing. Obtaining absolute stability through the anatomic reduction of all fracture fragments comes at the expense of fracture biology, whereas intramedullary nailing, which is more advantageous for diaphyseal fractures of the lower extremity, is technically demanding and often may not be possible when stabilizing many metaphyseal fractures. Overly stiff plating constructs are associated with asymmetric callus formation, early implant failure, and fracture nonunion. Numerous surgeon-controlled variables can be manipulated to increase flexibility without sacrificing strength, including using longer plates with well-spaced screws, choosing titanium or stainless steel implants, and using locking or nonlocking screws. Axially dynamic emerging concepts, such as far cortical locking and near cortical overdrilling, provide further treatment options when bridge plating techniques are used.

Application of Far Cortical Locking Technology in Periprosthetic Femoral Fracture Fixation: A Biomechanical Study

BACKGROUND

Lack of fracture movement could be a potential cause of periprosthetic femoral fracture (PFF) fixation failures. This study aimed to test whether the use of distal far cortical locking screws reduces the overall stiffness of PFF fixations and allows an increase in fracture movement compared to standard locking screws while retaining the overall strength of the PFF fixations.

METHODS

Twelve laboratory models of Vancouver type B1 PFFs were developed. In all specimens, the proximal screw fixations were similar, whereas in 6 specimens, distal locking screws were used, and in the other six specimens, far cortical locking screws. The overall stiffness, fracture movement, and pattern of strain distribution on the plate were measured in stable and unstable fractures under anatomic 1-legged stance. Specimens with unstable fracture were loaded to failure.

RESULTS

No statistical difference was found between the stiffness and fracture movement of the two groups in stable fractures. In the unstable fractures, the overall stiffness and fracture movement of the locking group was significantly higher and lower than the far cortical group, respectively. Maximum principal strain on the plate was consistently lower in the far cortical group, and there was no significant difference between the failure loads of the 2 groups.

CONCLUSION

The results indicate that far cortical locking screws can reduce the overall effective stiffness of the locking plates and increase the fracture movement while maintaining the overall strength of the PFF fixation construct. However, in unstable fractures, alternative fixation methods, for example, long stem revision might be a better option.

Automated measurement of fracture callus in radiographs using portable software

The development of software applications that assist the radiographic evaluation of fracture healing could advance clinical diagnosis and expedite the identification of effective treatment strategies. A radiographic feature regularly used as an outcome measure for basic and clinical fracture healing research is new bone growth, or fracture callus. In this study, we developed OrthoRead, a portable software application that uses image-processing algorithms to detect and measure fracture callus in plain radiographs. OrthoRead utilizes an optimal boundary tracking algorithm to semi-automatically segment the cortical surface, and a novel iterative thresholding selection algorithm to then automatically segment the fracture callus. The software was validated in three steps. First, algorithm accuracy and sensitivity were analyzed using surrogate models with known callus size. Second, the callus area of distal femur fractures measured using OrthoRead was compared to callus area manually outlined by orthopaedic surgeons. Third, the callus area of ovine tibial fractures was measured using OrthoRead and compared to callus volume measured from micro-CT. The software had less than a 5% error in measuring surrogate callus, and was insensitive to changes in image resolution, image rotation, and the size of the analyzed region of interest. Strong positive correlations existed between OrthoRead and clinicians (R(2)  = 0.98), and between 2D callus area and 3D callus volume (R(2)  = 0.70). The average run time for OrthoRead was 3 s when using a 2.7 GHz processor. By being accurate, fast, and robust, OrthoRead can support prospective and retrospective clinical studies investigating implant efficacy, and can assist research on fracture healing mechanobiology. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1224-1233, 2016.

LCP Versus LISS in the Treatment of Open and Closed Distal Femur Fractures: Does it Make a Difference?

OBJECTIVES

We compared the postoperative complication rates between the less invasive stabilization system (LISS) plating and locking compression plate for open and closed distal femoral fracture fixation for superiority.

DESIGN

Retrospective Review.

SETTING

Multicenter.

PARTICIPANTS

Patients identified through a hospital database who were treated for supracondylar femur fractures using LISS or LCP techniques between January 2005 and July 2010.

INTERVENTION

Medical history, patient demographics, injury characteristics, presence of polytrauma, and surgical characteristics were collected for each patient.

MAIN OUTCOME MEASUREMENTS

χ and logistic regression analysis was performed to compare postoperative infection and nonunion/reoperation regarding both plating techniques.

RESULTS

Of 339 distal femoral fractures, 185 (54.6%) were repaired with a LISS plate and 154 (45.4%) were repaired with a LCP. Multivariate analysis revealed only open fractures to be a risk factor for nonunion (Odds ratio 2.42, P = 0.01) and infection (Odds ratio 3.47, P = 0.02), regardless of device used. No difference was seen between either plate type in infection, plate failure, or nonunion.

CONCLUSIONS

Postoperative infection and nonunion rates are comparable between LISS and LCP for both open and closed distal femoral fracture fixation. As no difference was detected between plates, either may be used to treat distal femur fractures. Nonunion rate was higher than expected based on previous reports.

LEVEL OF EVIDENCE

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

Dynamic Stabilization with Active Locking Plates Delivers Faster, Stronger, and More Symmetric Fracture-Healing

BACKGROUND

Axial dynamization of fractures can promote healing, and overly stiff fixation can suppress healing. A novel technology, termed active plating, provides controlled axial dynamization by the elastic suspension of locking holes within the plate. This prospective, controlled animal study evaluated the effect of active plates on fracture-healing in an established ovine osteotomy model. We hypothesized that symmetric axial dynamization with active plates stimulates circumferential callus and delivers faster and stronger healing relative to standard locking plates.

METHODS

Twelve sheep were randomly assigned to receive a standard locking plate or an active locking plate for stabilization of a 3-mm tibial osteotomy gap. The only difference between plates was that locking holes of active plates were elastically suspended, allowing up to 1.5 mm of axial motion at the fracture. Fracture-healing was analyzed weekly on radiographs. After sacrifice at nine weeks postoperatively, callus volume and distribution were assessed by computed tomography. Finally, to determine their strength, healed tibiae and contralateral tibiae were tested in torsion until failure.

RESULTS

At each follow-up, the active locking plate group had more callus (p < 0.001) than the standard locking plate group. At postoperative week 6, all active locking plate group specimens had bridging callus at the three visible cortices. In standard locking plate group specimens, only 50% of these cortices had bridged. Computed tomography demonstrated that all active locking plate group specimens and one of the six standard locking plate group specimens had developed circumferential callus. Torsion tests after plate removal demonstrated that active locking plate group specimens recovered 81% of their native strength and were 399% stronger than standard locking plate group specimens (p < 0.001), which had recovered only 17% of their native strength. All active locking plate group specimens failed by spiral fracture outside the callus zone, but standard locking plate group specimens fractured through the osteotomy gap.

CONCLUSIONS

Symmetric axial dynamization with active locking plates stimulates circumferential callus and yields faster and stronger healing than standard locking plates.

CLINICAL RELEVANCE

The stimulatory effect of controlled motion on fracture-healing by active locking plates has the potential to reduce healing complications and to shorten the time to return to function.

Motion Predicts Clinical Callus Formation: Construct-Specific Finite Element Analysis of Supracondylar Femoral Fractures

BACKGROUND

Mechanotransduction is theorized to influence fracture-healing, but optimal fracture-site motion is poorly defined. We hypothesized that three-dimensional (3-D) fracture-site motion as estimated by finite element (FE) analysis would influence callus formation for a clinical series of supracondylar femoral fractures treated with locking-plate fixation.

METHODS

Construct-specific FE modeling simulated 3-D fracture-site motion for sixty-six supracondylar femoral fractures (OTA/AO classification of 33A or 33C) treated at a single institution. Construct stiffness and directional motion through the fracture were investigated to assess the validity of construct stiffness as a surrogate measure of 3-D motion at the fracture site. Callus formation was assessed radiographically for all patients at six, twelve, and twenty-four weeks postoperatively. Univariate and multivariate linear regression analyses examined the effects of longitudinal motion, shear (transverse motion), open fracture, smoking, and diabetes on callus formation. Construct types were compared to determine whether their 3-D motion profile was associated with callus formation.

RESULTS

Shear disproportionately increased relative to longitudinal motion with increasing bridge span, which was not predicted by our assessment of construct stiffness alone. Callus formation was not associated with open fracture, smoking, or diabetes at six, twelve, or twenty-four weeks. However, callus formation was associated with 3-D fracture-site motion at twelve and twenty-four weeks. Longitudinal motion promoted callus formation at twelve and twenty-four weeks (p = 0.017 for both). Shear inhibited callus formation at twelve and twenty-four weeks (p = 0.017 and p = 0.022, respectively). Titanium constructs with a short bridge span demonstrated greater longitudinal motion with less shear than did the other constructs, and this was associated with greater callus formation (p < 0.001).

CONCLUSIONS

In this study of supracondylar femoral fractures treated with locking-plate fixation, longitudinal motion promoted callus formation, while shear inhibited callus formation. Construct stiffness was found to be a poor surrogate of fracture-site motion. Future implant design and operative fixation strategies should seek to optimize 3-D fracture-site motion rather than rely on surrogate measures such as axial stiffness.

Comparison of the Mechanical Characteristics of a Universal Small Biplane Plating Technique Without Compression Screw and Single Anatomic Plate With Compression Screw

To better understand the mechanical characteristics of biplane locked plating in small bone fixation, the present study compared the stability under cyclic cantilever loading of a 2-plate locked biplane (BPP) construct without interfragmentary compression with that of a single-plate locked construct with an additional interfragmentary screw (SPS) using surrogate bone models simulating Lapidus arthrodesis. In static ultimate plantar bending, the BPP construct failed at significantly greater load than did the SPS construct (556.2 ± 37.1 N versus 241.6 ± 6.3 N, p = .007). For cyclic failure testing in plantar bending at a 180-N starting load, the BPP construct failed at a significantly greater number of cycles (158,322 ± 50,609 versus 13,718 ± 10,471 cycles) and failure load (242.5 ± 25.0 N versus 180.0 ± 0.0 N) than the SPS construct (p = .002). For cyclic failure testing in plantar bending at a 120-N starting load, the results were not significantly different between the BPP and SPS constructs for the number of cycles (207,646 ± 45,253 versus 159,334 ± 69,430) or failure load (205.0 ± 22.4 N versus 185.0 ± 33.5 N; p = .300). For cyclic testing with 90° offset loading (i.e., medial to lateral bending) at a 120-N starting load, all 5 BPP constructs (tension side) and 2 of the 5 SPS constructs reached 250,000 cycles without failure. Overall, the present study found the BPP construct to have superior or equivalent stability in multiplanar orientations of force application in both static and fatigue testing. Thus, the concept of biplane locked plating, using 2 low profile plates and unicortical screw insertion, shows promise in small bone fixation, because it provides consistent stability in multiplanar orientations, making it universally adaptable to many clinical situations.

Management of Distal Femur Fractures in Adults: An Overview of Options

Surgical treatment of periarticular and intra-articular fractures of the distal femur pose a significant challenge to the orthopedic surgeon. The primary goal of surgical treatment remains: restoration of the articular surface to the femoral shaft, while maintaining enough stability and alignment to enable early range of motion and rehabilitation. With appropriate surgical planning, these injuries can be managed with a variety of methods and techniques, while taking into account patients' functional goals, fracture characteristics, health comorbidities, bone quality, and risk of malunion and nonunion.

Biomechanical Concepts for Fracture Fixation

Application of the correct fixation construct is critical for fracture healing and long-term stability; however, it is a complex issue with numerous significant factors. This review describes a number of common fracture types and evaluates their currently available fracture fixation constructs. In the setting of complex elbow instability, stable fixation or radial head replacement with an appropriately sized implant in conjunction with ligamentous repair is required to restore stability. For unstable sacral fractures with vertical or multiplanar instabilities, "standard" iliosacral screw fixation is not sufficient. Periprosthetic femur fractures, in particular Vancouver B1 fractures, have increased stability when using 90/90 fixation versus a single locking plate. Far cortical locking combines the concept of dynamization with locked plating to achieve superior healing of a distal femur fracture. Finally, there is no ideal construct for syndesmotic fracture stabilization; however, these fractures should be fixed using a device that allows for sufficient motion in the syndesmosis. In general, orthopaedic surgeons should select a fracture fixation construct that restores stability and promotes healing at the fracture site, while reducing the potential for fixation failure.

Reducing Fracture Risk Adjacent to a Plate With an Angulated Locked End Screw

OBJECTIVES

Locking screws often are used in the treatment of osteoporotic fractures. Studies show that locking screws can increase bone stresses at the plate end, which increases the possibility of peri-implant fracture. This study evaluates whether the technique used to insert the end screw is related to the fracture tolerance adjacent to the plate.

METHODS

Twelve groups of plate constructs were evaluated using a fibular diaphyseal surrogate with mechanical properties similar to osteoporotic bone. All inboard screws were nonlocked with only the end screw fixation differing among groups. The end screws were inserted either perpendicularly to the plate or at an angle of 30 degrees for 6- and 12-hole plates. For both orientations, the end screws were inserted nonlocked, locked, or by a locked overdrilling technique, resulting in 6 groups per plate length. The perpendicular nonlocked screws represented a control group. The constructs were tested to failure in 4-point bending to determine peak load, failure energy, and stiffness.

RESULTS

All constructs failed by peri-implant fracture along a plane through the 2 cortical holes of the end screw. Compared with the control group, an angulated locked screw at the plate end significantly increased the peak bending moment and energy required to produce a fracture for both plate lengths (6-hole, P = 0.008, P < 0.001; 12-hole, P = 0.006, P < 0.001).

CONCLUSIONS

The use of an angulated locked end screw may enhance the resistance of osteoporotic bone to peri-implant fractures caused by bending forces.

The outcome of Polyax Locked Plating System for fixation distal femoral non-implant related and periprosthetic fractures

The objective of this study was to report on the safety, efficacy and clinical outcomes of the Polyax Locked Plating System (Biomet, Warsaw, IN, USA) in the management of acute (non-implant related and periprosthetic) distal femoral fractures. We retrospectively reviewed 71 patients with 73 distal femoral fractures. Thirty-three of the included fractures occurred around previously placed implants. The average patients' age was 67 years (range 18-98). There were 7 early postoperative complications (9.5%) including one deep surgical site infection, 2 pulmonary embolisms and 4 urinary or respiratory infections. At final follow-up (mean 12, range 9-55 months) all fractures progressed to clinical and radiological union. However, major revision surgery for healing problems was required in 5 cases (6.8%) and minor in 3 cases (4.1%). The average time to healing was 6 (range 3-23) months. Angulation less than 5 degrees in any plane was observed in 66 cases (89.7%), within 5-10 degrees in 5 cases (7.3%) and within 10-15 degrees in 2 cases (2.9%). The mean pre-injury and final follow-up values of Glasgow Outcome Scale were 1.5(1-3) and 1.7(1-3) respectively. Overall 61 patients (83.53%) retained their pre-injury activity status. The Polyax Locked Plating System offers a safe and efficient fixation in distal femoral fractures.

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

BACKGROUND

The aim of the current biomechanical cadaver study was to quantify the influence of an additional lag screw on construct stiffness in simple fracture models at the distal femur stabilised with a locking plate.

METHODS

For biomechanical testing paired fresh frozen human femora of 5 donors (mean age: 71 (SD 9) years) were chosen. Different locking plate configurations either with or without interfragmentary lag screw were tested under torsional load (2/4Nm/deg) or axial compression forces (500/1000N).

FINDINGS

Data show that plate constructs with interfragmentary lag screw reveal similar axial and torsional stiffness values compared to intact bone as opposed to bridging plate constructs that showed significantly lower stiffness for both loading conditions.

INTERPRETATION

The current biomechanical testing unveils that the insertion of a lag screw combined with a locking plate dominates over a bridging plate construct at the distal femur in terms of axial and torsional stiffness.

Semi-rigid screws provide an auxiliary option to plate working length to control interfragmentary movement in locking plate fixation at the distal femur

BACKGROUND

Extent and orientation of interfragmentary movement (IFM) are crucially affecting course and quality of fracture healing. The effect of different configurations for implant fixation on successful fracture healing remain unclear. We hypothesize that screw type and configuration of locking plate fixation profoundly influences stiffness and IFM for a given load in a distal femur fracture model.

METHODS

Simple analytical models are presented to elucidate the influence of fixation configuration on construct stiffness. Models were refined with a consistent single-patient-data-set to create finite-element femur models. Locking plate fixation of a distal femoral 10mm-osteotomy (comminution model) was fitted with rigid locking screws (rLS) or semi-rigid locking screws (sLS). Systematic variations of screw placements in the proximal fragment were tested. IFM was quantitatively assessed and compared for different screw placements and screw types.

RESULTS

Different screw allocations significantly affect IFM in a locking plate construct. LS placement of the first screw proximal to the fracture (plate working length, PWL) has a significant effect on axial IFM (p < 0.001). Replacing rLS with sLS caused an increase (p < 0.001) of IFM under the plate (cis-cortex) between +8.4% and +28.1% for the tested configurations but remained constant medially (<1.1%, trans-cortex). Resultant shear movements markedly increased at fracture level (p < 0.001) to the extent that plate working length increased. The ratio of shear/axial IFM was found to enhance for longer PWL. sLS versus rLS lead to significantly smaller ratios of shear/axial IFM at the cis-cortex for PWL of ≥ 62 mm (p ≤ 0.003).

CONCLUSION

Mechanical frame conditions can be significantly influenced by type and placement of the screws in locking plate osteosynthesis of the distal femur. By varying plate working length stiffness and IFM are modulated. Moderate axial and concomitantly low shear IFM could not be achieved through changes in screw placement alone. In the present transverse osteotomy model, ratio of shear/axial IFM with simultaneous moderate axial IFM is optimized by the use of appropriate plate working length of about 42-62 mm. Fixation with sLS demonstrated significantly more axial IFM underneath the plate and may further contribute to compensation of asymmetric straining.

Dynamic Locked Plating of Distal Femur Fractures

OBJECTIVES

Nonunion after locked bridge plating of comminuted distal femur fractures is not uncommon. "Dynamic" locked plating may create an improved mechanical environment, thereby achieving higher union rates than standard locked plating constructs.

SETTING

Academic Level 1 Trauma Center.

PATIENTS/PARTICIPANTS

Twenty-eight patients with comminuted supracondylar femur fractures treated with either dynamic or standard locked plating.

INTERVENTION

Dynamic plating was achieved using an overdrilling technique of the near cortex to allow for a 0.5-mm "halo" around the screw shaft at the near cortex. Standard locked plating was done based on manufacturer's suggested technique. The patients treated with dynamic plating were matched 1:1 with those treated with standard locked plating based on OTA classification and working length.

MAIN OUTCOME MEASUREMENTS

Three blinded observers made callus measurements on 6-week radiographs using a 4-point ordinal scale. The results were analyzed using a 2-tailed t test and 2-way intraclass correlations.

RESULTS

The dynamic plating group had significantly greater callus (2.0; SD, 0.7) compared with the control group (1.3: SD, 0.8, P = 0.048) with substantial agreement amongst observers in both consistency (0.724) and absolute score (0.734). With dynamic plating group, 1 patient failed to unite, versus three in the control group (P = 0.59). The dynamic group had a mean change in coronal plane alignment of 0.5 degrees (SD, 2.6) compared with 0.6 (SD, 3.0) for the control group (P = 0.9) without fixation failure in either group.

CONCLUSIONS

Overdrilling the near cortex in metaphyseal bridge plating can be adapted to standard implants to create a dynamic construct and increase axial motion. This technique seems to be safe and leads to increased callus formation, which may decrease nonunion rates seen with standard locked plating.

LEVEL OF EVIDENCE

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

Callus massage after distraction osteogenesis using the concept of lengthening then dynamic plating

Correction of complex deformities is a challenging procedure. Long-term wearing of a fixator after correction and lengthening are inconvenient and has a high rate of complication. The goals of the surgical treatment in the presented case were: (1) correction of the deformity and lengthening of the left leg by the Taylor spatial frame (TSF, Smith and Nephew, Marl, Germany); (2) reduction in the time the patient wears the TSF by changing the fixation system to a plate (lengthening then plating-LTP) and using a locking compression plate in conjunction with the 5.0 dynamic locking screws in order to accelerate bone healing.

Periprosthetic femoral fracture fixation: a biomechanical comparison between proximal locking screws and cables

BACKGROUND

The incidence of periprosthetic femoral fractures (PFF) around a stable stem is increasing. The aim of this biomechanical study was to examine how three different methods of fixation, for Vancouver type B1 PFF, alter the stiffness and strain of a construct under various configurations, in order to gain a better insight into the optimal fixation method.

METHODS

Three different combinations of proximal screws and Dall-Miles cables were used: (A) proximal unicortical locking screws alone; (B) proximal cables and unicortical locking screws; (C) proximal cable alone, each in combination with distal bicortical locking screws, to fix a stainless steel locking compression plate to five synthetic femora with simulated Vancouver type B1 PFFs. In one synthetic femora, there was a 10-mm fracture gap, in order to simulate a comminuted injury. The other four femora had no fracture gap, to simulate a stable injury. An axial load was applied to the constructs at varying degrees of adduction, and the overall construct stiffness and surface strain were measured.

RESULTS

With regards to stiffness, in both the gap and no gap models, method of fixation A was the stiffest form of fixation. The inclusion of the fracture gap reduced the stiffness of the construct quite considerably for all methods of fixation. The strain across both the femur and the plate was considerably less for method of fixation C, compared to A and B, at the locations considered in this study.

CONCLUSION

This study highlights that the inclusion of cables appears to damage the screw fixations and does not aid in construct stability. Furthermore, the degree of fracture reduction affects the whole construct stability and the bending behaviour of the fixation.

Dynamic locking plates provide symmetric axial dynamization to stimulate fracture healing

Axial dynamization of an osteosynthesis construct can promote fracture healing. This biomechanical study evaluated a novel dynamic locking plate that derives symmetric axial dynamization by elastic suspension of locking holes within the plate. Standard locked and dynamic plating constructs were tested in a diaphyseal bridge-plating model of the femoral diaphysis to determine the amount and symmetry of interfragmentary motion under axial loading, and to assess construct stiffness under axial loading, torsion, and bending. Subsequently, constructs were loaded until failure to determine construct strength and failure modes. Finally, strength tests were repeated in osteoporotic bone surrogates. One body-weight axial loading of standard locked constructs produced asymmetric interfragmentary motion that was over three times smaller at the near cortex (0.1 ± 0.01 mm) than at the far cortex (0.32 ± 0.02 mm). Compared to standard locked constructs, dynamic plating constructs enhanced motion by 0.32 mm at the near cortex and by 0.33 mm at the far cortex and yielded a 77% lower axial stiffness (p < 0.001). Dynamic plating constructs were at least as strong as standard locked constructs under all test conditions. In conclusion, dynamic locking plates symmetrically enhance interfragmentary motion, deliver controlled axial dynamization, and are at least comparable in strength to standard locked constructs. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1218-1225, 2015.

Retrograde locked intramedullary nailing for aseptic supracondylar femoral nonunion following failed locked plating

PURPOSE

To review the outcome of retrograde locked nailing for aseptic supracondylar femoral nonunions following failed locked plating.

METHODS

Records of 20 men and 4 women aged 20 to 57 (mean, 39) years who underwent retrograde locked intramedullary nailing for aseptic supracondylar femoral nonunion following failed locked plating were reviewed. There were 20 closed and 4 open Gustilo type II or IIIA fractures secondary to motor vehicle accidents (n=21) or falls (n=3). Patients had undergone one to 3 operations. The mean time from injury to the present revision surgery was 1.3 years. No patient had a flexion contracture. The locked plate was removed and replaced with a retrograde dynamic locked nail (with or without buttress plate augmentation) followed by bone grafting.

RESULTS

17 men and 4 women were followed up for a mean of 3.4 years. The rest were lost to follow-up. The 21 patients achieved bone union after a mean of 4.3 months. The mean maximal knee flexion improved from 97.1º to 107.6º (p=0.03). Knee function was excellent in one, good in 15, and fair in 5 knees. The fair outcome was due to extension contracture, varus knee deformity, or knee pain. There were 3 malunions with varus deformity of 7º, 8º, and 9º each. No patient had deep infection causing a nonunion. All 21 patients could walk without aids.

CONCLUSION

Retrograde locked intramedullary nailing for aseptic supracondylar femoral nonunions following failed locked plating achieved a high union rate.

Radiographic features of teriparatide-induced healing of femoral fractures

Teriparatide is a drug that is used to increase bone remodeling, formation, and density for the treatment of osteoporosis. We present three cases of patients with a femoral insufficiency fracture. The patients were administered teripatatide in an attempt to treat severe osteoporosis and to enhance fracture healing. We found several radiographic features around the femoral fractures during the healing period. 1) Callus formation was found at a very early stage in the treatment. Teriparatide substantially increased the unusually abundant callus formation around the fracture site at 2 weeks. Moreover, this callus formation continued for 8 weeks and led to healing of the fracture. 2) Abundant callus formation was found circumferentially around the cortex with a ‘cloud-like’ appearance. 3) Remodeling of the teriparatide-induced callus formation was found to be part of the normal fracture healing process. After 1 year, normal remodeling was observed on plain radiographs. These findings indicate that teriparatide can be used as an adjuvant therapy in the management of femoral insufficiency fractures.

•

Radiographic features of teriparatide-induced healing of femoral fractures were assessed.

•

Teriparatide accelerated and enhanced fracture healing of femoral fractures

•

Teriparatide-induced fracture healing was followed by a normal fracture healing process.

•

Teriparatide can be used as an adjuvant therapy in the management of femoral insufficiency fractures.