Fifteen-year trends in the number and age of patients with rheumatoid arthritis undergoing total knee and hip arthroplasty: A comparison study with osteoarthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease associated with irreversible joint destruction. Severe large joint destruction causes functional disability and pain, requiring total joint arthroplasty (TJA) in RA patients as well as those with osteoarthritis (OA), a degenerative joint disease [1]. Since newer medications, such as methotrexate and biologics, became available in Japan [2–4] and other countries [5,6], the number of RA patients undergoing TJA has declined. We recently found that age when TJA is performed has increased among RA patients [4]. Both degenerative and inflammatory processes (i.e. OA and RA changes) can lead to TJA in RA patients, and distinguishing between the two is difficult. Examining time trends in RA patients compared to OA patients may help us determine whether these findings are attributed to RA changes. We therefore aimed to investigate time trends in the number and age of RA and OA patients undergoing elective primary total knee arthroplasty (TKA) or total hip arthroplasty (THA).