Countersinking the Lag Screw or Blade During Cephalomedullary Nailing of Geriatric Intertrochanteric Femur Fractures: Less Collapse and Implant Prominence Without Increased Cutout Rates.

INTRODUCTION: The lag screw or helical blade of a cephalomedullary nail facilitates controlled collapse of intertrochanteric proximal femur fractures. However, excessive collapse results in decreased hip offset and symptomatic lateral implants. Countersinking the screw or helical blade past the lateral cortex may minimize subsequent prominence, but some surgeons are concerned that this will prevent collapse and result in failure through cutout. We hypothesized that patients with countersunk lag screws or helical blades do not experience higher rates of screw or blade cutout and have less implant prominence after fracture healing. METHODS: A retrospective review of 175 consecutive patients treated with cephalomedullary nails for AO/OTA 31A1-3 proximal femur fractures and a minimum 3-month follow-up and 254 patients with a 6-week follow-up at a single US level I trauma center. Patients were stratified based on countersunk versus noncountersunk lag screw or helical blade in a cephalomedullary nail. The primary outcome was the cutout rate at minimum 3 months, and the secondary outcome was radiographic collapse at minimum 6 weeks. RESULTS: Cutout rates were no different in patients with countersunk and noncountersunk screws and blades, and countersinking was associated with less collapse and less implant prominence at 6 weeks. DISCUSSION: Surgeons can countersink the lag screw or blade when treating intertrochanteric proximal femur fractures with a cephalomedullary nail without increasing failure rates and with the potential benefits of less prominent lateral implants and decreased collapse.

Supplemental medial small fragment fixation adds stability to distal femur fixation: A biomechanical study.

INTRODUCTION: Bridge plating of distal femur fractures with lateral locking plates is susceptible to varus collapse, fixation failure, and nonunion. While medial and lateral dual plating has been described in clinical series, the biomechanical effects of dual plating of distal femur fractures have yet to be clearly defined. The purpose of this study was to compare dual plating to lateral locked bridge plating alone in a cadaveric distal femur gap osteotomy model. MATERIALS AND METHODS: Gap osteotomies were created in eight matched pairs of cadaveric female distal femurs (average age: 64 yrs (standard deviation ± 4.4 yrs); age range: 57-68 yrs;) to simulate comminuted extraarticular distal femur fractures (AO/OTA 33A). Eight femurs underwent fixation with lateral locked plates alone and were matched with eight femurs treated with dual plating: lateral locked plates with supplemental medial small fragment non-locking fixation. Mechanical testing was performed on an ElectroPuls E10000 materials testing system using a 10 kN/100 Nm biaxial load cell. Specimens were subject to 25,000 cycles of cyclic loading from 100-1000 N at 2 Hz. RESULTS: Two (2/8) specimens in the lateral only group failed catastrophically prior to completion of testing. All dual plated specimens survived the testing regimen. Dual plated specimens demonstrated significantly less coronal plane displacement (median 0.2 degrees, interquartile range [IQR], 0.0-0.5 degrees) compared to 2.0 degrees (IQR 1.9-3.3, p = 0.02) in the lateral plate only group. Dual plated specimens demonstrated greater bending stiffness compared to the lateral plated group (median 29.0 kN/degree, IQR 1.5-68.2 kN/degree vs median 0.50 kN/degree, IQR 0.23-2.28 kN/degree, p = 0.03). CONCLUSION: Contemporary fixation methods with a distal femur fractures are susceptible to mechanical failure and nonunion with lateral plates alone. Dual plate fixation in a cadaveric model of distal femur fractures underwent significantly less displacement under simulated weight bearing conditions and demonstrated greater stiffness than lateral plating alone. Given the significant clinical failure rates of lateral bridge plating in distal femur fractures, supplemental fixation should be considered, and dual plating of distal femurs augments mechanical stability in a clinically relevant magnitude.