Sex and Age Affect Progression to Total Knee Arthroplasty After Cartilage Surgery: A UK Biobank Cohort Study

Objective Evaluate the association of sex and age at surgery with time to total knee arthroplasty (TKA) following knee cartilage surgery in UK Biobank (UKB) participants. Design Participants with a history of knee cartilage surgery were classified into four surgical subgroups: cartilage repair, debridement, microfracture, and unicompartmental knee arthroplasty. Time from index surgery to primary TKA in each group was analysed using the Kaplan-Meier method and the sexes compared using log-rank tests. Cox proportional hazards regression evaluated associations between age at surgery, sex, and surgery type with risk of progression to TKA. Results The study included 1,967 males and 1,741 females. Log‑rank testing demonstrated significant sex‑based differences in time to TKA following debridement ( P = 0.002) and microfracture ( P = 0.003), with shorter TKA‑free survival observed in females. Cox regression showed that female sex was associated with a higher hazard of progression to TKA compared with male sex (hazard ratio [HR] = 1.19, P = 0.021). Increasing age at surgery was associated with increased risk (HR = 1.05 per year, P < 0.0001). Conclusion Female sex and older age at surgery were associated with a higher risk of progression to TKA following cartilage surgery. Sex‑specific differences in time to TKA were most evident after debridement and microfracture. These findings describe associations observed within the constraints of available UKB data.