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Hip resurfacing: patient and treatment options.

Hip Resurfacing: Patient Selection and Benefits By Michael A. Mont, MD, Mike S. McGrath, MD, and Michael G. Zywiel, MD Metal-on-metal total hip resurfacing arthroplasty has become an increasingly popular option over the past ten years. Multiple purported benefits of this procedure have been described. In addition, several reports have suggested that the outcomes of this procedure are improved with proper patient selection. The purpose of this presentation was to describe the reported benefits of this procedure as well as the patient-selection process. Compared with conventional total hip arthroplasty, hip resurfacing may be associated with several advantages and unique risks. One advantage is increased femoral bone stock because the neck and most of the head are retained. Also, compared with stemmed prostheses, resurfacing prostheses may be simpler to place in patients who have extra-articular deformities of or hardware attached to the proximal aspect of the femur. In addition, resurfacing may be associated with a greater hip range of motion, improved gait parameters, lower dislocation rates, and increased activity levels. Finally, in the case of failure, revision to a conventional prosthesis is straightforward, with results that are comparable with those obtained with a primary stemmed total hip arthroplasty. Risks include femoral neck fracture, loosening of the implant, and exposure to metal ions. Proper patient selection is important in hip resurfacing. Patients who have osteoarthritis and who have not responded to nonoperative treatment are indicated for this procedure. Resurfacing has also been performed on patients who have osteonecrosis, rheumatoid arthritis, and LeggCalvé-Perthes disease, and these patients have had good-toexcellent short-term results. Contraindications include insufficient bone stock in the femoral head, severe osteopenia, large cysts at the femoral head or neck, a narrow femoral neck, notching of the femoral neck, and severe obesity (body mass index >35 kg/m2), all of which are associated with an increased risk of femoral neck fracture. Another contraindication is metal hypersensitivity, which may be associated with pseudotumors in some patients. Age does not appear to be a contraindication on the basis of the results in the literature. The results associated with hip resurfacing arthroplasty are promising, and the procedures may have multiple benefits for patients who meet the selection criteria. Longer-term follow-up will be necessary to confirm these results.