Obese patients face increased risks for infection and dislocation following revision hip surgery

Along with age and injuries, obesity is a leading risk factor for osteoarthritis (OA), a painful and disabling joint disease. While excessive weight can aggravate the toll on almost any joint, obesity has been associated with a higher prevalence of hip OA and an increase in total hip arthroplasty (THA). Whether obese hip OA patients are more prone to postsurgical complications, however, remains open to debate and investigation, since the results of existing studies conflict. What’s more, only a few short-term studies have focused on how obesity affects the outcomes of revision THA. Compared to primary THA revision surgery is a longer and more complicated procedure implying more extensive tissue damage and a greater risk of prosthetic joint infections and dislocations, as well as other long-term complications.

Researchers at Geneva University Hospitals set out to evaluate the impact of obesity on the incidence of serious complications after revision THA, over a period of up to 5 years. The team also aimed to determine whether functional improvement, pain, and satisfaction 5 years after the second hip replacement differed between obese patients and patients of healthy weight. Their results, presented in the May 2008 issue of Arthritis Care & Research (www.interscience.wiley.com/journal/arthritis), reveal a strong correlation between obesity and high rates of adverse events, as well as lower functional gains and more persistent pain, after revision THA.

This long-term study focused on all patients who underwent a revision THA, excluding re-revisions, at the university’s hospital—the only public hospital serving the urban and suburban populations of Geneva, Switzerland—between 1966 and 2006. Of the 204 subjects, 114 were women and 90 were men, with a mean age of 71.6 years. Based on height and weight data obtained just before surgery, 52 patients, 25 percent of the sample, were defined as obese, with a body mass index (BMI) of 30 or more. The standard range for a normal BMI, the ideal weight to height ratio, is between 18 and 25. To further assess the association between BMI and postoperative outcomes, patients were also examined in 4 BMI categories: less than 25; 25 to 29.9, defined as overweight; 30 to 34.9; and 35 or more.