180 Degrees Rotation of a Loosening Hydroxylapatite-Coated Acetabular Component – A Case Report

We present an unusual presentation of acetabular component loosening in a 58 year-old female patient. The prosthesis type was hydroxylapatite-coated total hip system. Initially, it was supposed to be severely wearing that resulting in thinning of superior portion of the polyethylene. We performed revision opera-tion for the acetabular component and found that there was complete loosening between cup and acetabulum and the prosthesis was 180 degrees of rotation around the central spike. This is an interesting phenomenon and we postulated the mechanism of loosening.