Cyclic loading of fractured cadaveric femurs after elastomer femoroplasty: an in vitro biomechanical study

Elastomer femoroplasty is a novel and experimental approach in the prevention of hip fracture surgery. Previously, we published the results of an in vitro cadaveric experiment in which we showed a significant reduction of fracture displacement in treated femurs. The aim of the present study was to establish the failure loads and inter-fragmentary movement of fractured, elastomer femoroplasty treated femurs during cyclic loading. 16 cadaveric femurs were treated with elastomer femoroplasty and fractured in a simulated fall configuration. Each specimen underwent 10 cycles with a preload of 50 N, starting with a peak load of 250 N followed by 10 cycles of 500 N and continued with 500 N increments. The crosshead speed was 2 mm/s. The failure load, the number of completed cycles, and crosshead extensions were recorded. The mean failure load was 2709 N (SD 1094). The number of completed cycles until failure was 60 (SD 22). The mean translation during maximum loading was 5.25 mm (SD 0.9). At 1500 N (two times the bodyweight of a 75 kg individual) the extension was 3.16 mm. Preventive elastomer femoroplasty leads to the stabilization of the proximal femur after fracture. In a single leg stance configuration, cyclic loading with mean failure loads that well exceed the peak loads during normal gait is feasible.