Hip Replacement Riskier for Rheumatoid Arthritis Sufferers

Patients with rheumatoid arthritis (RA) are at higher risk than those with osteoarthritis (OA) for adverse outcomes following joint replacement surgery, according to a new study.

Researchers at the University of Toronto (Canada) identified 43,997 patients who underwent a first primary elective total hip arthroplasty (THA) or total knee arthroplasty (TKA) procedure between 2002 and 2009. Using a validated algorithm for identifying individuals with RA, they then compared the rates of complications among THA and TKA recipients with versus without RA. The relationship between arthritis type and the occurrence of specific complications was adjusted for potential confounders (age, sex, comorbidity, and provider volume).

The results showed that recipients with RA had higher age and sex-standardized rates of dislocation following THA, and higher rates of infection following TKA. After adjustment for potential confounders, a diagnosis of RA was a significant and independent predictor of dislocation following THA, with a risk almost double that of OA. Risk for infection within two years of TKA was also high, relative to recipients with OA. The study was published on November 19, 2013, in Arthritis and Rheumatism.

“Dislocation within a short time of total hip arthroplasty is a serious complication,” concluded lead author Bheeshma Ravi, MD, and colleagues of the department of orthopedic surgery. “In addition to being very painful and necessitating revision arthroplasty and/or aggressive rehabilitation following closed reduction, it is estimated that dislocations increase the hospital costs of a primary total hip arthroplasty by over 300%.”

According to the researchers, possible explanations as to why patients with RA were more likely to experience dislocation were the use of smaller implants and different surgical techniques, along with disease-related factors such as acetabular protrusion and soft tissue problems. Explanations as to why infections were more common in the RA group included the use of immunomodulatory treatments, but it was not clear why the increased risk was only for knee replacement, and not also for the hip.

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