Ten-year survival of resurfacing matches cemented THA for men in regional database

Women have significantly poorer implant survival.

In what Scottish investigators described as one the few studies comparing hip resurfacing arthroplasty to cemented total hip arthroplasty through 10 postoperative years, survivorship and functional results in men were similar for both implants, but women had significantly higher risk of revision with resurfacing.

The 2,210 cemented total hip arthroplasties (THAs) used Exeter stems (Stryker) with several different cemented cups. All but six of the 715 hip resurfacings (HRs) were done with the Birmingham Hip Resurfacing System (Smith & Nephew), according to Robert Lawton, MSc, MRCS, an orthopaedic trainee.

“Our audit is useful as it enables us to accurately inform patients of the results of surgery in our hospitals including the risk of revision. Broadly speaking, our results are in line with those published elsewhere and by national joint registries,” Lawton told Orthopaedics Today Europe in an interview prior to the 12th EFORT Congress, where he is set to present the findings.

Audit details

The database audit used follow-up data of all cemented THAs and HRs performed at three U.K. NHS Tayside hospitals collected independently by the Tayside Arthroplasty Audit Group, which included consecutive cases performed from 2000 to 2010 by several surgeons. Resurfacings were performed by co-investigator Brian Singer, FRCS, a consultant orthopaedic surgeon at Perth Royal Infirmary, U.K., and two other consultant orthopaedic surgeons in the region trained in the procedure.

“All THAs and HRs were included regardless of the reason for surgery, not just those done just for osteoarthritis,” Lawton said, and no learning curve cases were excluded.

The goal of the analysis was to compare survivorship and Harris Hip Scores (HHSs) with each implant and investigate effects of age group (under 55 & over 55) and gender. All of the included cases were primary procedures. The end point was revision for any cause excluding infection. HHSs were recorded preoperatively and 1, 3, 5, 7 and 10 years postoperatively.

Results

HHSs for HRs were significantly better than for THA, which Lawton suggests may be due to resurfacings being done in younger patients who generally have better function to begin with.

“Our impression is that pain relief is similar but because resurfacing patients tend to be younger (average age 50 compared with 70 in the hip replacement group) they are likely to have fewer comorbidities and tend to have higher functional scores at long-term follow up.”

The THA revision rate was 2% vs. a 7% HR revision rate, overall. Lawton noted risk of revision in males was not significantly different regardless of age or procedure, but a non-significant trend towards better survival of HR than THA in males under 55 was emerging that will be interesting to follow. Women’s revision rates differed significantly by procedure, especially for those under age 55 at 0% for THA and 6.7% for HR. In women aged 55 and older, revision rates were 1.3% for THA vs. 5.9% for HR.

“Rather than being due to female gender, other published work has suggested that smaller sized femoral heads carry a higher risk of revision. Further work would be needed to see if this finding is replicated in our data,” Lawton said. “Our results are already helpful in counseling women about resurfacing risk and in selecting appropriate surgical options.” — by Susan M. Rapp

Reference:

• Lawton R, Singer B, Ridley D. A prospective comparative study of hip resurfacing and cemented total hip arthroplasty with up to 10 years follow-up. Scheduled to be presented June 2, 9:20-9:30, at the 2011 EFORT Congress. June 1-4. Copenhagen.

• Robert Lawton, MSc, MRCS, can be reached at Ninewells Hospital, Dundee DD1 9SY, U.K.; +44-1382-818479; email: r.lawton@nhs.net.
• Disclosure: Lawton has no relevant financial disclosures.

The data reported by the authors confirm that the revision rate in females younger than 55 treated with HR is higher than in females of the same age and in males treated with total hip arthroplasty. Although important information such as the type of HR implant and the accuracy of the surgical technique is not reported in the abstract, the higher revision rate with HR in this female population should be considered with caution. As fewer young female patients undergo HR in my practice as compared to males, this information does not really affect my practice.

Other reports at long term (McMinn) have shown that when the right implant and correct surgical technique are used, a lower revision rate than that reported in the abstract can be obtained in young females. Although it remains unclear why the revision rate in young females is higher than in older females and males, I will continue to perform HR in my young female patients but with more cautious patient selection. Certainly when discussing the indications with this particular patient population, comprehensive information on the data available in the literature should be provided, including all the pros and cons of each type of surgery.

– Antonio Moroni, MD
Professor, School of Sports Science
Bologna University, Italy
Disclosure: He is on the speakers bureau and is a paid consultant for Active Implants Corporation.

Reference:

• McMinn DJ, Daniel J, Ziaee H, Pradhan C. Indications and results of hip resurfacing. Int Orthop. 2011;35:231-237.