Similar results seen with hip resurfacing and total hip arthroplasty with large heads
Investigators attribute differences seen in other studies to patient selection bias and bearing size.
LAS VEGAS — Although previous studies have shown better results with hip resurfacing compared to total hip arthroplasty, level I research from Canadian investigators indicates no significant difference in the clinical outcome between the procedures.
“[There was] no difference in the clinical outcome based on this functional study,” Martin Lavigne, MD, MSc, said during his presentation at the American Academy of Orthopaedic Surgeons annual meeting. “There was an earlier recovery in large diameter heads and hip resurfacing compared to what the literature shows between 28-mm head total hip arthroplasty. The only remaining advantage of hip resurfacing may be bone preservation, although with the current survivorship of uncemented stems showing good 25 year results, that might not be a true advantage.”
Randomized, control trial
Lavigne noted that previous studies showing superiority with hip resurfacing may have been influenced by patient selection bias, patient perception or the use of large diameter heads in hip resurfacing.
To eliminate these potential confounding variables, Lavigne and colleagues conducted a randomized, control trial evaluating the clinical outcome and gait characteristics of 48 patients who underwent either hip resurfacing or total hip arthroplasty (THA) using a large-diameter head (more than 38 mm) and were blinded to their treatment group up to 1 year postoperatively. In addition, the investigators compared the study groups to a control group of 14 normal participants for gait analysis.
The investigators used gait speed as the primary outcome measure and also assessed the groups using hop, step, muscle strength and postural balance tests which included functional reach and quiet standing tests. They also evaluated patients using WOMAC and UCLA scores and determined patient satisfaction. Clinical data and gait analysis were assessed preoperatively and at 3-, 6- and 12-months follow-up.
Preoperatively, the investigators found no significant differences between the study groups regarding age, gender, body mass index, diagnosis and WOMAC score. Postoperatively, gait analysis revealed no significant difference between the large-diameter-head THA group and the hip resurfacing group at all follow-up time periods.
“Both groups reached control group speed at 6 months postoperatively, which is much quicker than what you see in THA, since functional deficit usually persists of up to 1 year,” Lavigne said.
Images: Lavigne, M
The study groups also demonstrated no significant differences regarding hop, muscle strength and standing tests. While the investigators discovered that the THA group showed a slight advantage in the step test, the hip-resurfacing group did slightly better on the functional reach test. In addition, they found no significant differences between the groups regarding WOMAC and UCLA sores. The groups also reported similar perception regarding how their hips felt, and investigators found no reports of thigh pain in either group.
“The postulated explanation for the better clinical outcomes after hip resurfacing compared to THA have been challenged in this study,” Lavigne said. “We believe that the better clinical outcomes of hip resurfacing compared to 28-mm THA must be due to the bias in patient selection and difference in bearing size.”
For more information:
- Martin Lavigne, MD, MSc, is an assistant clinical professor at the Université de Montreal Hopital Maisoneuve-Rosemont. He can be reached at 5345 Blvd. Assomption Ste. 55, Montreal, QC H1T 4B3, Canada; 514-254-0785; e-mail: firstname.lastname@example.org. He is part of the speakers bureau for Zimmer and receives research support from Stryker, Biomet, Zimmer, Smith & Nephew, DePuy and the Canadian Institutes of Health Research.
- Lavigne M, Therrien M, Nantel J, et al. RCT comparing clinical outcome and gait characteristics after large head THA and hip resurfacing. Paper #318. Presented at the American Academy of Orthopaedic Surgeons 76th Annual Meeting. Feb. 25-27, 2009. Las Vegas.