The outcomes of Cormet hip resurfacing compared to standard primary total hip arthroplasty

Metal-on-metal hip resurfacing has provided an alternative to standard total hip arthroplasty in younger, more active patients. However, detractors argue that many of the benefits of resurfacing can be obtained with the use of larger femoral heads. The purported advantages of the resurfacing procedure include preservation of femoral bone stock, increased range of motion, decreased dislocation rate, excellent performance in high-activity patients, and a potentially easier revision than total hip arthroplasty. The purpose of this study was to examine the outcomes of patients who had hip resurfacing and to compare them to all total hip arthroplasty procedures performed during the same time period.

In November 2007, the senior investigator (MAM), a high-volume joint arthroplasty surgeon, who had exceeded all resurfacing learning curves, transitioned to a new hip resurfacing system. The study cohort of 67 resurfacing patients (73 hips) had a mean age of 51 years (range, 21 to 84 years), consisted of 63 males and 4 females, had a mean body mass index of 28 kg/m2 (range, 20 to 47 kg/m2), and had a minimum 2-year follow-up. Revision and complication rates were determined, as well as clinical outcomes using various clinical rating systems, including Harris hip scores. These outcomes were compared to another cohort of 137 standard primary total hip arthroplasties performed during the same time period.

Survivorship in the hip resurfacing cohort was 100%, compared with 98% in the total hip arthroplasty group (p = 0.55). The three failures were comprised of one peri-prosthetic fracture treated with a femoral component revision and two cases of acetabular loosening, for which the acetabular component only was revised. Following revision, all patients were doing well at the most recent follow-up of 2 years. One patient who underwent resurfacing arthroplasty developed a right sciatic nerve palsy that was treated with nerve decompression. The patient regained full motor and sensory function and was doing well at the most recent follow-up. The mean Harris hip score in the resurfacing patients improved from 32 points (range, 18 to 45) to 97 points (range, 70 to 100), at a mean of 30 months (range, 24 to 37) follow-up.

Excellent results continue to be demonstrated with hip resurfacing systems, with equal, early survivorship when compared to total hip arthroplasty. For patients who meet the appropriate selection criteria and in the hands of an experienced, high-volume arthroplasty surgeon hip resurfacing provides excellent early results.