New technique for treatment of unstable distal femur fractures by locked double-plating: Case report and biomechanical evaluation

Background: A comminuted, intra-articular distal femur fracture was surgically treated by the authors with a locked, double-plating technique because fixation stability could not be initially achieved by using a standard double-plating technique. The purpose of this study was to determine biomechanically whether a locked double-plate construct would enhance fixation stability compared with a nonlocked double-plate construct. Methods: Six matched pairs of mildly osteopenic femurs were selected and all had a reproducible intra-articular fracture pattern created. Each pair underwent fixation with either a double-plating construct or a locked, double-plating construct that was randomly assigned. The instrumented femurs were then mechanically tested in several loading modes to determine fixation stability. After initial testing, specimens were cyclically loaded and retested for stability. Results: The locked, double-plating construct provided significantly greater fixation stability than the standard double-plating construct in precycling and postcycling biomechanical testing. Conclusion: The technique described is particularly applicable for severely comminuted fractures of the distal femur and fractures in osteopenic hone with poor screw purchase. It offers a simple alternative for enhancing fixation stability, which avoids the potential complications of methylmethacrylate-enhanced screw fixation.