Movie: edge load wear test of hip prostheses

This short movie shows a novel wear test for artificial hip bearings. This test focuses on what may be the most severely damaging scenario that artificial hips experience in the human body. In some patients, the hip joint may partly separate under certain circumstances, and when that happens, the typically congruent contact between the ball and socket can quickly become a non-conforming contact between the ball and the socket’s edge. In that scenario, the contact between the ball and socket has the potential to cause increased wear, because the contact stress is much greater.

The test apparatus applies a horizontal load to the femoral head (the ball), which forces the head into contact with the socket’s edge. Meanwhile, the acetabular liner is reciprocated up and down at a rate of 1 cycle per second. Several aspects of the test set-up may be configured as desired, including the magnitude of the horizontal force, the orientation of the acetabular liner, and the speed of reciprocation.

This test method is yielding valuable information about the performance of artificial hip bearings under worst case conditions. The findings of several focused studies will be published in the scientific literature relevant to the field of orthopedic implants and joint arthroplasty.