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Hip resurfacing preserves bone mineral density, bone stock, but disadvantages must be considered
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Although there is a high level of evidence that hip resurfacing arthroplasty preserves bone mineral density and bone stock in the proximal femur, the clinical relevance should be weighed against potential disadvantages, such as a higher revision rate for metal-on-metal bearings, according to researchers.
To determine whether bone mineral density (BMD) was preserved without significant femoral neck narrowing (FNN), the researchers randomly assigned 42 patients who needed primary hip arthroplasty for osteoarthritis to receive hip resurfacing (RHA) and 40 patients to small-diameter metal-on-metal total hip arthroplasty (MoM THA). The researchers measured BMD in the calcar with dual-energy absorptiometry (DXA) preoperatively; at 3 and 6 months; and at 1, 2, 3 and 5 years postoperatively. The researchers also measured four additional BMD regions of interest, as well as FNN after RHA.
Overall, the resurfacing procedure had a significantly longer mean time of surgery vs. THA. At 1-year follow-up after RHA, results showed BMD in the calcar increased to 106.8% and remained stable at 5 years. The researchers found a significant decrease in the corresponding region of interest in the THA to 80.5% at 1 year, which stabilized to 82.5% at 5-year follow-up.
Job L.C. van Susante
According to study results, BMD changes fluctuated between 99.9% and 104.1% in the additional regions of interest in the femoral neck and trochanter-areas. At 3 years, results showed a mean of 1.3% FNN in the RHA group, according to the researchers.
“Preservation of femoral bone stock was an important theoretical advantage at the time of the re-introduction of hip resurfacing,” Job L.C. van Susante, MD, PhD, of the department of orthopaedics at Rijnstate Hospital in Arnhem, the Netherlands, told Orthopedics Today. “Our prolonged prospective follow-up with repeated DXA clearly confirms this bone stock-preserving nature. This benefit may be clinically relevant at time of further revisions; however, it must be weighed against potential disadvantages caused by the risk of the introduction of implant specific metal-on-metal bearing problems.” – by Casey Tingle
Disclosures: van Susante reports financial support for additional DXA scans received from Wright Medical. Please see the full study for a list of all other authors’ relevant financial disclosures.
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