Fractures of the greater trochanter induced by osteolysis with the anatomic medullary locking prosthesis.

Pathologic fractures of the greater trochanter associated with trochanteric osteolysis are a late complication of total hip arthroplasty that have been described only in case reports. In this study of 208 consecutive total hip arthroplasties with mean 12.2-year radiographic follow-up, we reviewed the incidence, presentation, treatment, and outcome of such fractures. A radiographic review revealed 9 hips (4.3%) with trochanteric fractures resulting from osteolysis, occurring at a mean follow-up of 129 months. Five were diagnosed at the time of their radiographic appearance. Four were treated without operative fixation, using crutches and limited weight bearing for 4 to 6 weeks. Seven fractures healed in situ without major displacement. One resulted in a nonunion of the tip of the greater trochanter, and the radiographic outcome of a recent fracture was unknown. We found that the risk of sustaining a fracture was independent of the size of the osteolytic lesion; however, the risk increased significantly when the lysis eroded the cortical bone of the greater trochanter. In our experience with the extensively porous-coated AML stem (DePuy, a Johnson & Johnson Company, Warsaw, IN), conservative treatment leads to reasonable radiographic and clinical results in cases with limited initial fracture displacement.