Abstract
Purpose
Although total knee replacement (TKR) has a high reported success rate, the pain relief and functional improvement after surgery varies. We asked what is the prevalence of patients showing no clinically significant improvement 1-year after TKR, and what are the patient level factors that may predict this outcome.
Method
We reviewed primary TKR registry data that were collected from two academic hospitals: the Toronto Western Hospital (TWH) and the Henderson Hospital(HH) in Ontario. Relevant covariates including demographic data, body mass index, and comorbidity were recorded. Knee joint pain and functional status were assessed at baseline and at 1-year follow-up with the Western Ontario McMaster University Osteoarthritis Index (WOMAC) and Oxford knee score (OKS) to measure the change using the minimal clinically important difference (MCID). Logistic regression modeling was used to identify the predictors of interest.
Results
Overall, 11.7% (373/3177) of patients reported no clinically significant improvement 1-year after surgery. Logistic regression modeling showed that a greater patient age independently predicted no clinically significant improvement on the WOMAC scale 1-year after surgery (p=0.0003), while male gender independently predicted no clinically significant improvement on the OKS 1-year after surgery (p=0.008).
Conclusion
Awareness of the prevalence of patients who may show no clinically significant improvement and factors that predict this outcome will help patients and surgeons to set realistic expectations of surgery.
