Design of an Osseointegrated Lower Limb Prosthetic Force Limiting Connection

Osseointegration is the direct attachment of a prosthetic device to the bone in order to mimic the use, feel, and behavior of a missing natural limb. In a femoral osseointegrated fixture, the load is transferred directly into the bone using the same force path a natural leg would generate. This leads to better proprioception and sense of the foot contacting the ground. However, traumatic falls or impact loads present a serious concern for the amputee wearing an osseointegrated system. The conceptual device presented here offers a fully mechanical solution to these loading problems by releasing the prosthetic when placed under maximum allowable torsion loads and bending loads in the anteroposterior (AP) and mediolateral (ML) planes. The device is designed to bracket those forces with an upper limit set at 50% greater than the measured gait forces.