HypothesisThe proximal geometry and design of trochanteric nails affects initial construct stiffness, fatigue survival, and preservation of biomechanical stability over time.Materials & MethodsEight pairs of human cadaveric femora were implanted with two different short intramedullary nails with (Intertan, (S&N)) and without (Gamma 3, (Stryker)) interlocking lag screws. Femoral osteotomies were performed to generate a pertrochanteric multifragmentary unstable fracture (OTA 31-A 2.2). The bones were tested in a cyclic testing protocol with increasing loads of 100 N every 20.000 cycles (start point 50/500 N) simulating one leg stance. The position of the femur was 10° adduction and 10° extension. Stiffness, failure load, and cycles to failure were measured.ResultsInitially, stiffness of the interlocking lag screw nail was 40 % higher (p < 0,05) than for the non-interlocking nail. During the test, the difference in stiffness gradually decreased. Load to failure (9 %, p < 0,05) and cycles to failure (13 %, p ...

Biomechanical evaluation of interlocking lag screw design in intramedullary nailing of unstable pertrochanteric fractures

In recent years, plate augmentation over a retained intramedullary (IM) nail has been shown to be an effective option for managing femur fracture nonunions because it improves the biomechanical environment of the fracture site without causing additional biological damage. In the current study, we present outcome data from 22 consecutive patients treated with plate augmentation for femoral shaft nonunion leaving the nail in situ. Between 2015 and 2018, 22 consecutive patients with femoral shaft aseptic nonunion after IM nailing were treated with plate augmentation over a retained nail at four different institutions. Nonunion was categorized based on its anatomical location and was classified according to the Weber and Cech classification. Cortical defects greater than 1.0 cm, the type of nailing procedure, and the number of previous interventions were recorded. Patients were assessed clinically and radiographically to measure the healing of nonunion sites. The time to fracture union and complications were recorded. Descriptive statistics were used when applicable. One site location was supra-isthmic, 12 were isthmic, and 9 were infra-isthmic. There were 10 cases of vascular nonunion and 12 cases of avascular nonunion. A cortical defect greater than 1.0 cm was observed in three patients. Antegrade nailing was performed in 11 patients, and retrograde nailing was performed in 11 patients. Reaming was performed in 12 patients. In eight patients, the fracture was openly reduced during the IM nailing index procedure. The average number of previous interventions before augmentation plating was 1.6 (1–4). Bone union was achieved in 19 patients after augmentation plating with an average follow-up of 23.5 months (12–51 months). Excellent and good clinical results were observed in all patients. There was no plate or screw breakage, and no patient developed infection. Augmentation plating leaving the nail in situ is an excellent option for treating femoral shaft nonunion after IM nailing, with a high union rate and few complications. We believe the technique should gradually replace exchange nailing as the standard of care for the majority of femoral shaft nonunions that occur after IM nailing.

Augmentation plating leaving the nail in situ is an excellent option for treating femoral shaft nonunion after IM nailing: a multicentre study

SUMMARY Treatment of periprosthetic distal femur fractures remains challenging due to assuring adequate distal fixation. Traditional treatment options include lateral locked plating and retrograde nailing, although recently dual implant constructs have been explored with promising results. Allowing immediate weight-bearing in this patient population has benefits with regards to rehabilitation and outcome. Recent literature has focused on nail-plate constructs, however plate-plate constructs are preferred at our institution as they do not require arthroplasty component compatibility, facilitate the coronal plane reduction, and allow for immediate weight-bearing.

Technical Trick: Dual Plate Fixation of Periprosthetic Distal Femur Fractures.

Patellar fracture morphology varies based on the mechanism of injury. Most fractures are either a result of direct impact or through an indirect eccentric extensor contraction injury. Each fracture pattern requires appropriate preoperative planning and individualization of the fixation method. Displaced fractures affect the extension apparatus, and often require surgical fixation. Surgical treatment is recommended in fractures with any of the following features: articular step-off > 2 mm, > 3 mm of fracture displacement, open fractures, and displaced fractures affecting the extensor mechanism. Meticulous handling of the soft-tissue envelope is of the utmost importance, given the patella's tenuous blood supply and limited soft-tissue envelope. Incongruent articular surface can result in detrimental long-term effects; therefore, surgical treatment is directed toward anatomic reduction and fixation. The evolution of patellar fracture fixation continues to maximize options to balance rigid fixation with low-profile fixation constructs. Improving functional outcomes, minimizing soft-tissue irritation, and limiting postoperative complications are possible by using the therapeutic principles of rigid anatomical fixation and meticulous soft-tissue handling.

Patella Fractures: Approach to Treatment.

Distal femur fractures are challenging injuries historically associated with high rates of nonunion and varus collapse with operative management. As a result, clinical and research interest in dual plating (DP) of distal femur fractures has seen a dramatic increase in recent years. The purpose of this study was to systematically review the literature regarding vascular anatomy and biomechanics of distal femur fractures treated with DP constructs. A systematic literature review of two medical databases (PubMed & Scopus) was performed to identify peer-reviewed studies on the anatomy and biomechanics regarding DP of distal femur fractures. A total of 1,001 papers were evaluated and 14 papers met inclusion criteria (6 anatomy and 8 biomechanics). Methodological quality scores were used to assess quality and potential bias in the included studies. In the biomechanical studies, DP constructs demonstrated greater axial and rotational stiffness, as well as less displacement and fewer incidences of failure compared to all other constructs. Vascular studies showed that the femoral artery crosses the mid-shaft femur approximately 16.0–18.8 cm proximal to the adductor tubercle and it is located on average 16.6–31.1 mm from the femoral shaft at this location, suggesting that medial plate application can be achieved safely in the distal femur. The methodological quality of the included studies was good for biomechanical studies (Traa score 79.1; range 53–92.5) and excellent for anatomical studies (QUACs score 81.9; range 69.0–88.5). Existing biomechanics literature suggests that DP constructs are mechanically stronger than other constructs commonly used in the treatment of distal femur fractures. Furthermore, medial distal femoral anatomy allows for safe application of DP constructs, even in a minimally invasive fashion. Dual plating should be considered for patients with distal femur fractures that have risk factors for instability, varus collapse, or nonunion.

Biomechanical and anatomical considerations for dual plating of distal femur fractures: a systematic literature review

OBJECTIVES To investigate the biomechanical properties of a lateral locked plate alone or in combination with a supplemental medial plate or an intramedullary nail (IMN). METHODS Intra-articular distal femur fractures with metaphyseal comminution (OTA/AO 33-C) were simulated with a standardized model in 28 synthetic femora and divided into 4 groups. Group I was instrumented with a 4.5-mm lateral locked distal femoral plate alone, group II with a lateral locked plate plus a low-profile precontoured 3.5-mm medial distal tibial plate, group III with a lateral locked plate plus a medial 3.5-mm reconstruction plate, and group IV with a lateral locked plate plus a retrograde IMN. Specimens were then axially loaded and cycled to failure or runout. Outcomes of interest were baseline stiffness, survivability, and cycles to failure. RESULTS Groups III and IV have a significantly higher baseline stiffness (P < 0.001) when compared with groups I and II. Furthermore, groups III and IV had a higher max load to failure (P < 0.01) when compared with groups I and II. The survivability in groups III and IV was 71% and 100%, respectively, while no specimens in group I or II survived maximum loading. There was no significant difference between group III and IV regarding stiffness, survivability, and cycles to failure. CONCLUSION When considering fixation for intra-articular distal femur fractures with metaphyseal comminution (OTA/AO 33-C), we found that supplementation of a lateral locked plate with a medial plate or an IMN to be biomechanically superior to lateral locked plating alone regarding stiffness, survivability, and cycles to failure. A low-profile precontoured plate did not add significantly to the construct stiffness in this study.

Supplementation of Lateral Locked Plating for Distal Femur Fractures: A Biomechanical Study.

Objectives The purpose of this study is to report the results of open reduction internal fixation of patella fractures (OTA 34 A-C) using cannulated lag screws and FiberWire® (Arthrex, Naples, FL, USA) with regard to union and symptomatic implant removal. Design Retrospective review of prospectively collected database. Setting Urban Level 1 trauma center and Level 2 trauma center Methods All displaced intra-articular patella fractures (OTA 34 A-C) treated with ORIF by cannulated lag screws and FiberWire® tension band/cerclage between January 1, 2009 and August 1, 2018. Three hundred and eighty seven consecutive patients were identified. Fifty fractures were included in the final analysis. Main Outcome Measurement All patients were followed to clinical and radiographic union. Nonunion was defined as lack of clinical and radiographic union, fracture displacement, and/or return to OR for revision surgery. Rate of symptomatic implant removal was recorded. Results Average age was 57.7 years (range 21–86). Average follow up was 20.6 months (range 6–98 months). Average time to clinical and radiographic union was 3.1 months (range 3–7 months). Four fractures were open. There was a 96% (48/50) rate of primary union, with one patients requiring revision surgery to achieve union, and one developing an asymptomatic radiographic nonunion. The rate of symptomatic implant removal was 8% (4/50). Only 1 of the 4 was operated for a prominent suture knot, and the remaining 3 were for prominent screw removal. Knee range of motion averaged 0.37° extension to 119° flexion (range, 0–150°). Conclusion Patella fractures can be treated with cannulated lag screws and FiberWire® with a high rate of primary union (96%) and a low rate of symptomatic implant removal (8%). The implant removal rate compares favorably with alternative constructs, with an equivalent rate of fracture union.

Brett Barrick

Papers

Supplementation of Lateral Locked Plating for Distal Femur Fractures: A Biomechanical Study.

Patella fractures treated with cannulated lag screws and fiberwire® have a high union rate and low rate of implant removal