Imaging of the total hip arthroplasty.

More than 75,000 total hip arthroplasties are done yearly in the United States. Although modern cementing techniques have improved the longevity of cemented implants, uncemented prostheses have become popular, especially in younger, more active patients. There is also a trend toward modular components. These mechanical devices will all ultimately fail if subjected to sufficient use and stresses over time, though the specific causes and modes of failure vary widely. Loosening remains the primary cause of implant failure. There is a growing awareness of the role of wear particles in periprosthetic bone resorption with or without loosening. Stress shielding, dislocation, periprosthetic and prosthetic fractures, infection, heterotopic ossification, and stress concentration are also frequently encountered clinical problems. Conventional radiographs are the mainstay in evaluating total hip arthroplasty, with computed tomography and nuclear medicine imaging playing smaller roles.