Purpose: Comorbidities in patients undergoing total joint arthroplasty continue to be a challenging problem. Retrospective studies have demonstrated that co-morbidities affect outcomes of revision total knee arthroplasty (RTKA). However, the relationship between the outcomes of RTKA and co-morbidities has not been well established. This prospective randomized study was undertaken to investigate these relationships.

Method: A prospective cohort study (the North America Knee Arthroplasty Revision Study) was conducted to examine factors that predict outcomes after RTKA. 308 subjects met inclusion/exclusion criteria. Subjects were followed from the time of the index surgery for a minimum of two years to monitor outcomes and complications. Validated quality of life instruments, including SF-36, WOMAC, Knee Society Score, and an activity scale were used. The rates of improvement from 0 to 12 and 12 to 24 months were analyzed.

Results: There were 145 males and 163 females. The mean age was 68.7 years. Mean time from primary procedure to RTKA was 7.9 years. Arthroplasty failure was classified as aseptic in 82% and septic in 18% of the cases. Hypertension was seen in 62.4%, back pain in 50%, heart disease in 25.9%, diabetes mellitus in 23.9%, gastric ulcers in 17.9%, and rheumatoid arthritis in 16.6%. Less frequent co-morbidities included anemia, cancer, kidney disease, lung disease and liver disease.

Conclusion: Analyses showed that the number of reported co-morbidities was the most significant predictor of outcomes, consistently forecasting poorer functional improvement on all measures. The results indicated that ultimate treatment of co-morbidities before and after surgery may improve outcomes of RTKA. Comorbidities in patients undergoing revision TKA can be a challenging problem. This study showed that the number of reported co-morbidities was the most significant predictor of poorer outcomes.