OBJECTIVE: Most of the evidence regarding complications following total hip arthroplasty (THA) and total knee arthroplasty (TKA) are based on patients with osteoarthritis (OA); less is known about outcomes in rheumatoid arthritis (RA). Using a validated algorithm for identifying patients with RA, we undertook this study to compare the rates of complications among THA and TKA recipients between those with RA and those without RA.
METHODS: In patients who underwent a first primary elective THA or TKA between 2002 and 2009, those with RA were identified using a validated algorithm: a hospitalization with a diagnosis code for RA or 3 physician billing claims with a diagnosis code for RA, with at least 1 claim by a specialist (rheumatologist, orthopedic surgeon, or internist) in a 2-year period. Recipients with diagnostic codes suggesting an inflammatory arthritis, but not meeting RA criteria, were classified as having inflammatory arthritis. All remaining patients were deemed to have OA. Cox proportional hazards models, censored on death, were used to determine the relationship between the type of arthritis and the occurrence of specific complications, adjusting for potential confounders (age, sex, comorbidity, and provider volume).
RESULTS: We identified 43,997 eligible THA recipients (3% with RA) and 71,793 eligible TKA recipients (4% with RA). Total joint arthroplasty recipients with RA had higher age and sex-standardized rates of dislocation following THA (2.45%, compared with 1.21% for recipients with OA) and higher age and sex-standardized rates of infection following TKA (1.26%, compared with 0.84% for recipients with OA). Controlling for potential confounders, recipients with RA remained at increased risk of dislocation within 2 years of THA (adjusted hazard ratio [HR] 1.91, P = 0.001) and remained at increased risk of infection within 2 years of TKA (adjusted HR 1.47, P = 0.03) relative to recipients with OA.
CONCLUSION: Patients with RA are at higher risk of dislocation following THA and are at higher risk of infection following TKA relative to those with OA. Further research is warranted to elucidate explanations for these findings, including the roles of medication profile, implant choice, postoperative antibiotic protocol, and method of rehabilitation following joint replacement.
