Metal-on-metal hip resurfacing: what have we learned?

Surface hip arthroplasty has many attractive features for young, active patients, particularly because of the conservative nature of this treatment and its ability to preserve femoral bone. It is more anatomic and physiologic than stem-type hip replacements, and it represents a truly minimally osteoinvasive procedure, with no penetration into the femoral intramedullary canal. In addition, the construct has increased stability because of the near-normal diameter of the femoral component compared with most conventional hip replacement components. Although the short- to midterm clinical results for metal-on-metal hybrid hip resurfacing implants are definitely superior to those of earlier generations of resurfacing implants, the results of conventional total hip replacement using contemporary designs and bearing materials have also improved. As a result, it is imperative to assess what is known about the safety and efficacy of resurfacing to refine the indications and technique to improve the overall results and durability.