Long-Term Outcome and Maintenance of Outdoor Walking Ability After Primary Total Knee Arthroplasty for Osteoarthritis Versus Rheumatoid Arthritis: A Retrospective Study

Objective and Aim: Ambulation is important for maintaining health. It becomes difficult when the knee joint is severely damaged by diseases such as osteoarthritis (OA) or rheumatoid arthritis (RA). We investigated the long-term results and maintenance of outdoor walking ability after total knee arthroplasty (TKA) in patients with osteoarthritis versus rheumatoid arthritis.

Methods: We retrospectively reviewed 205 patients with OA (285 knees) and 117 with RA (168 knees) who underwent primary TKA. We investigated the period during which they were able to walk outdoors for more than 10 minutes and the long-term outcomes of TKA. All TKA surgeries were performed via a medial parapatellar approach under general anesthesia by one surgeon at one institution. The mean follow-up durations in the OA and RA groups were 13.0 and 12.8 years, respectively.

Results: About 90% of participants in both the OA and RA groups were female. The mean ages at surgery in the OA and RA groups were 72.8 and 65 years, respectively. The cumulative frequencies of outdoor walking ability in the OA and RA groups were 39.3% and 44.1%, respectively, at 15 years, and 21.0% and 27.1%, respectively, at 20 years, with no significant intergroup differences (log-rank test, p=0.3017). The main cause of gait dysfunction was medical disease (55.7% and 61.4% in the OA and RA groups, respectively). The cumulative survival rate for TKA was 97% at 20 years in both groups. The preoperative risk factors for inability to walk outdoors were older age at TKA and consistently severe pain in the OA group, and older age at TKA, higher rheumatoid factor concentration, and oral corticosteroid use in the RA group.

Conclusion: There was no significant difference between the OA and RA groups in knee joint function after TKA, even in the long term. The cumulative survival rate for TKA was 97% at 20 years in both the OA and RA groups. TKA improves long-term knee function and has a similar long-term beneficial effect on outdoor walking ability in patients with OA and RA.