Periarticular osteophyte formation protects against total knee arthroplasty in rheumatoid arthritis patients with advanced joint damage

Objective Periarticular osteophyte formation is observed during the repair of damaged joints in rheumatoid arthritis (RA); however, little is known about its clinical and functional roles. This study aimed to determine the influence of periarticular osteophyte formation on the incidence of total knee arthroplasty (TKA) (a surrogate for long-term outcomes of joint destruction) in patients with RA. Methods This retrospective longitudinal study included a total of 130 symptomatic (tender and/or swollen) knee joints in 80 patients starting biologics. Cumulative incidences of TKA were compared according to the presence or absence of osteophyte on plain anteroposterior radiograph (osteophyte (±)) and the extent of advanced joint damage as defined by Larsen’s grading system (0–II vs. III–V). Results Kaplan-Meier estimates showed a significantly lower cumulative incidence of TKA for the osteophyte (+) group ( n = 33) compared with the osteophyte (−) group ( n = 31) in the Larsen grades III–V group (38 vs. 74% at 10 years, P = 0.010), whereas no significant difference was observed between the osteophyte (+) ( n = 11) and osteophyte (−) ( n = 55) groups in the Larsen grades 0–II group (9 vs. 10% at 10 years). Multivariate Cox proportional hazards analysis revealed that older age (hazard ratio (HR), 1.04 per 1 year; 95% confidence interval (CI), 1.01–1.08) and osteophyte formation (HR, 0.39; 95% CI, 0.19–0.79) independently predicted TKA in the Larsen grades III–V group, whereas none of the assessed variables predicted TKA in the Larsen grades 0–II group. Conclusion Osteophyte formation reduces the incidence of TKA in patients with RA who have advanced joint damage. Key Points • Older age and Larsen grade were independent predictors of total knee arthroplasty (TKA) in rheumatoid arthritis (RA) patients. • Periarticular osteophyte formation reduced the incidence of TKA in RA patients with Larsen grades III–V.