Massive Acetabular Bone Loss: The Cup-Cage Solution

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.