Background and Objectives — 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 individuals with RA, we compared the rates of complications among THA and TKA recipients with versus without RA.
Methods — In patients with a first primary elective THA or TKA between 2002 and 2009, those with RA were identified with a validated algorithm: hospitalization with a RA diagnosis or 3 RA billing claims with at least 1 claim by a specialist (rheumatologist, orthopedic surgeon or internist) over a 2y period. Recipients with diagnostic codes suggesting an inflammatory arthritis (IA), but not meeting RA criteria, were classified as having IA. All remaining patients were deemed to have OA. Cox proportional hazards, censored on death, were used to determine the relationship between arthritis type and the occurrence of specific complications adjusting for potential confounders (age, sex, co-morbidity and provider volume).
Results — We identified 43,997 eligible THA recipients (3% RA) and 71,793 eligible TKA recipients (4% RA). TJA recipients with RA had higher age & sex-standardized rates of dislocation following THA (OA: 1.21%, RA: 2.45%) and infection following TKA (OA: 0.84%, RA: 1.26%). Controlling for potential confounders, recipients with RA remained at increased risk for dislocation within two years of THA (adjusted HR 1.91, p=0.001), and infection within two years of TKA (adjusted HR 1.47, p=0.03), relative to recipients with OA.
Conclusions — Patients with RA are at higher risk for dislocation following THA and infection following TKA relative to those with OA. Further research is warranted to elucidate explanations, including the role of medication profile, implant choice, post-operative antibiotic protocol and method of rehabilitation following joint replacement.
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