The impact of rheumatoid arthritis on rehabilitation outcomes after lower extremity arthroplasty

Background: Medical rehabilitation after lower extremity arthroplasty is an integral part of recovery and a critical step in returning to independent mobility. We hypothesized that rehabilitation may take longer for patients with rheumatoid arthritis (RA) versus osteoarthritis (OA) because joint pain, swelling, and deformities are generally worse among persons with RA. Objectives: To determine the impact of RA on length of rehabilitation stay and rehabilitation functional status gain after arthroplasty. Methods: We conducted a retrospective cohort analysis using a national registry of US medical rehabilitation inpatients admitted after a lower extremity arthroplasty between 1994 and 2001. Sample included 1361 patients with RA and 26,096 patients with OA. The main outcome measure was functional status gain as assessed by the functional independence measure (FIM). Our primary analytic method was linear regression. Covariates were age, gender, race/ethnicity, other comorbidity, admission FIM, and site of arthroplasty. Results: Mean length of stay for patients with RA was 11.3 +/- 7.1 days (mean +/- standard deviation) versus 10.3 +/- 6.5 days for those with OA. Mean weekly gain was 18.6 +/- 12.1 for patients with RA versus 20.6 +/- 12.0 for those with OA. After adjusting for covariates, RA was associated with longer stay (0.7 day) and lower FIM gain (2.6). Conclusions: RA was associated with longer length of rehabilitation stay and lower FIM gain in patients with lower extremity arthroplasty. Such patients may require additional monitoring to ensure sufficient rehabilitation.