Anterior locking plate reduces trochanteric fracture migrations during hip extension

•Two greater trochanter novel implants were compared on a stair climbing test bench.•One had an anterior locking plate to counteract stair climbing loads.•We report that stair climbing is a plausible explanation of high failure rate.•An anterior locking plate significantly reduces migrations of the bone fragment.

BackgroundGreater trochanter fractures or osteotomies fixed with lateral plates still present high rates of complications. Unblocked greater trochanter anterior movement during hip extension might be a possible cause of failure. This study aimed to determine, under stair climbing conditions, the biomechanical behaviour of a greater trochanter fragment and the impact of an anterior locking plate on its migration.MethodsEighteen femurs paired from nine fresh frozen cadaveric specimens were tested on a quasi-dynamic stair climbing cycling test bench. Left and right sides with greater trochanter fractures were randomly fixed either with an antero-lateral locking plate or with a lateral locking plate. Migrations, defined as the remaining movements of the unloaded greater trochanter fragment, were measured for all 18 femurs.FindingsDuring hip extension, multi-directional greater trochanter fragment movements occurred and showed a back-and-forth anterior rotation. The lateral locking plate failed due to greater trochanter fragment rotation around the superior axis and anterior translation. The antero-lateral locking plate significantly reduced greater trochanter anterior migration (− 0.9 mm ± 1.6) compared to the lateral locking plate (9.6 mm ± 9.5).InterpretationHip extension provides a plausible explanation for the high rate of post-operative failures of greater trochanter fixations. An antero-lateral locking plate represents an efficient surgical alternative counteracting the multi-directional greater trochanter movements occurring during hip extension.