Abstract
Hip resurfacing has been proposed as an alternative to traditional total hip replacement in young, active patients. Metal-on-metal resurfacing devices were introduced in the 1990's, and a number of them reached the international market. The promise of bone preservation, more normal loading, greater activity, and easier revision led many surgeons to begin implanting these devices.
Over time, lessons have been learned regarding patient selection, implant selection, and surgical technique. Several devices have been withdrawn from the market, and many surgeons have abandoned the procedure. We continue to perform this procedure in substantial numbers, approximately 350 per year. The triad of a well-designed device, implanted accurately, in the correct patient has never been more critical than with these implants.
Following FDA approval in 2006, we studied the safety and effectiveness of one hip resurfacing device at our US institution in a large, single-surgeon series. We report our early to mid–term results in 476 patients who were under the age of 50 years at the time of hip resurfacing. Their average age was 42.8 (12–49) with an average follow-up of 4.8 years (2–8.8). Males represented 76% of the patients, and 91% had osteoarthritis. The average component size was 50.8mm (44–58) in men and 45.3mm (40–50) in women.
All surgery was performed in the lateral position using an anterolateral approach. Patients were allowed 75% weight-bearing for 6 weeks, followed by avoidance of strenuous exertion (running, jumping, heavy lifting) for 12 months. Follow-up intervals were 6 weeks, 1 year, 2 years, and 5 years. Follow-up percentage was 81%.
We measured a number of outcomes scores using a validated prospective observational registry at each follow-up interval. Improvement in HOOS Function was from pre-op of 41.4 + 22.7 to 93.5 + 15.2, Physical Activity Limitation improved from 2.4 + 2.5 to 8.2 + 2.6, and SF-12 Physical Composite Score improved from 31.7 +10.3 to 49.4 + 10.2.
There were no device-related failures in this series. There were no femoral neck fractures, no femoral component loosening, no failure of acetabular ingrowth, and no metal-related complications or pseudotumors. Two male patients, one a known heroin user, and the other with septic discitis, had remote hematogenous sepsis requiring component removal, each at 38 months after resurfacing. One female fell down an escalator 32 months after resurfacing sustaining a fractured acetabulum requiring component revision. Overall survivorship was 99.4%. Aseptic survivorship in males under age 50 was 100%.
We believe that hip resurfacing continues to offer a viable alternative for younger patients who would otherwise be candidates for total hip arthroplasty.
