Abstract

Osteosarcomas affecting the pelvic region often require extensive resections, resulting in the loss essential structures, which are required for hip joint stability. Dual mobility (tripolar) cup prostheses were created to address the issue of joint instability and have even become very popular for hip joint reconstruction following hemipelvectomies. Despite their increased stability, dislocations will still inevitably occur and need to be managed. In these cases, a closed reduction must be executed diligently as excessive levering may cause the “bottle opener” effect and dislocation of the polyethylene liner, an event also known as intraprosthetic dislocation. To our knowledge, this is the first reported case of an intraprosthetic dislocation by the “bottle opener” effect following an attempted closed reduction of a dual mobility system in an orthopedic oncology patient. In this case report and brief review of the current literature, we want to create awareness about the possible problems of dual mobility cups in oncology patients and suggest a type of management should these problems arise.

Keywords: Osteosarcomas; Intraprosthetic dislocation