Trabecular Metal™ Cups for Acetabular Defects With 50% or Less Host Bone Contact

Acetabular component revision in the context of large contained bone defects with less than 50% host bone contact traditionally have been treated with roof reinforcement or antiprotrusio cages. Trabecular Metal cups (Zimmer, Inc, Warsaw, IN) may offer a reasonable treatment alternative. We evaluated the clinical and radiographic outcome of this mode of treatment. We prospectively followed 53 hip revision acetabular arthroplasty procedures performed with Trabecular Metal cups for contained defects with 50% or less contact with native bone. All patients were clinically and radiographically evaluated for evidence of loosening or failure. Minimum followup was 24 months (average, 45 months; range, 24-71 months). Contact with host bone ranged from 0% to 50% (average, 19%). The mean postoperative Merle d'Aubigne-Postel score was 10.6 (range, 1-12), with a mean improvement of 5.2 (range, -4-10) compared to the preoperative score. Two failed cups (4%) were revised. Two additional cups (4%) had radiographic evidence of probable loosening. Complications included four dislocations and one sciatic nerve palsy. The data suggest treatment of cavitary defects with less than 50% host bone contact using Trabecular Metal cups, without structural support by augments or structural bone grafts, is a reasonable option.