Development of a prediction model to estimate the risk of walking limitations in patients with total knee arthroplasty

Objective: Early and accurate risk prediction of walking limitations after total knee arthroplasty (TKA) is important for clinical and economic reasons. However, to our knowledge, no studies have systematically integrated multiple predictors into a single, clinically practical model. Our study aimed to develop a prediction model to estimate the risk of post-TKA walking limitations. Methods: We performed a prospective cohort study of 1096 patients who underwent elective, primary TKA between July 2013 and September 2014. Candidate predictors included patient demographics, surgical factors, and pre- and early (1-mo) post-TKA functional measures. The outcome of interest was self-reported walking limitations at 6 months of post-TKA. We used multivariable proportional odds regression with bootstrap internal validation to develop the model. Results: In all, 12% of patients reported walking limitations (maximum walk time ≤ 15 min) at 6 months postsurgery. The main predictors of increasing levels of walking limitations were preoperative walking limitations (overall p < 0.001), higher levels of body mass index [interquartile range (IQR)-OR 1.3, 95% CI 1.2–1.5], lower values of 1-month post-TKA gait speed (IQR-OR 1.9, 95% CI 1.3–2.6), the presence of contralateral knee pain (OR 1.9, 95% CI 1.2–3.0), and the use of a quadstick preoperatively (OR 3.5, 95% CI 1.7–7.3). The prediction model had an optimism-corrected concordance index of 0.71. Conclusion: A small but sizable proportion of patients with TKA had persistent mobility limitations. Our prediction model may help to risk-stratify patients, and external validation is required before the model can be used in clinical practice.