Massive Acetabular Bone Loss: The Cup-Cage Solution

Abstract

Treatment of massive contained acetabular defects is challenging. The current generation of reconstruction cages in combination with either morcellized or structural allograft bone has given promising results. However, a significant proportion will fail due to lack of biological fixation of the cage, resulting in fatigue fracture. This study examines the early results of a new technique of combining a cage with a shell of Trabecular Metal (Zimmer, Warsaw, IN), because this material has the potential to enhance biological fixation. Fourteen patients with major acetabular defects underwent revision total hip arthroplasty with a Cup-Cage construct. Clinical and radiographic outcomes were determined at minimum 2-year follow-up. Complications, reoperations, and functional status (overall satisfaction, pain, limp, and use of gait-aids) were assessed. Radiographs were analyzed for evidence of implant migration, new radiolucent lines, and bone graft resorption. Mean follow-up was 27 months (range: 1-39), excluding 1 death in less than 1 year after surgery. Outcomes were 82% excellent or good, 12% fair, and 6% poor. Average pre- and postoperative Western Ontario MacMaster scores were 64 and 33 points, respectively. Oxford hip scores were an average of 45 preoperative and 28 postoperative. Short-form-36 averaged 351 preoperative and 601 postoperative. Radiographically, all the implants were stable and none had migrated.