September 14, 2016
2 min read

Morbidly obese, nonobese patients experienced similar outcomes after revision THA

No differences found in incidence of complications or survivorship free of reoperation or rerevision.

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Morbidly obese patients who underwent aseptic revision total hip arthroplasty experienced similar complications, failures and clinical outcomes compared with nonobese patients, according to study results.

“Although the overall risk of complications was not different between the two groups, the type of complication was certainly different,” Tad M. Mabry, MD, assistant professor of orthopedic surgery at the Mayo Clinic in Rochester, Minn., told Orthopedics Today. “[For] patients who had aseptic revision total hip arthroplasty, the risk of dislocation was significantly higher for the morbidly obese patients, but the risk of polyethylene wear or aseptic loosening was significantly higher in the nonobese group.”

Obese vs nonobese patients

Mabry and colleagues matched 123 morbidly obese patients who underwent revision total hip arthroplasty (THA) with 123 patients with a BMI less than 30 kg/m2. Overall, 61% of patients were women. Mean follow-up was 8.4 years for morbidly obese patients and of 8.8 years for nonobese patients.

Results showed 40% of patients in the morbidly obese group and 41% of patients in the nonobese group sustained at least one complication, with the most common complication being intraoperative or postoperative femur fracture. While morbidly obese patients were more likely to sustain at least one dislocation postoperatively, researchers found they were less likely to encounter polyethylene wear or aseptic loosening compared with nonobese patients. Morbidly obese and nonobese groups had no difference in the incidence or survivorship free of reoperation, with 12% of morbidly obese patients and 18% of nonobese patients undergoing at least one reoperation, according to results. Similarly, researchers noted no differences in the incidence or survivorship free of re-revision between morbidly obese and nonobese groups (10% vs. 13%).

Multivariate analysis showed complication, reoperation or repeat revision were not predicted by morbid obesity, age of at least 60 years, sex, diabetes, rheumatoid arthritis or tobacco use. Prior to revision, researchers found Harris Hip scores were similar between groups with both groups improving significantly after surgery. While nonobese patients had significantly better scores at 2 years and 5 years compared with morbidly obese patients, results showed similar scores between groups at 10 years and 15 years.

“I think these results, in addition to other previously published studies, would indicate that surgeons who are going to perform a revision total hip in the morbidly obese population should pay close attention to hip stability and use whatever techniques they think are most appropriate to try and reduce the risk of postop dislocation,” Mabry said.

More specific indicators

According to Mabry, future research should look at whether newer surgical techniques and implants have improved patient outcomes, as well as work on identifying the role of BMI as a predictor for different outcomes.

“We probably need to look at more specific indicators because there might be certain aspects to a patient that, even though they may have the same BMI, dramatically change their risk profile. Ideally, we can then determine optimal strategies for preoperative patient optimization in order to give all patients better outcomes,” Mabry said. – by Casey Tingle

Disclosure: Mabry reports no relevant financial disclosures.