Latent Class Analysis to Predict Outcomes of Early High-Intensity Physical Therapy After Total Knee Arthroplasty, Based on Longitudinal Trajectories of Walking Speed.

Abstract

To (1) classify patients who are recovering from total knee arthroplasty (TKA) based on walking speed during an early physical therapy program, and (2) assess whether walking-speed trajectory predicts performance on the timed up-and-go (TUG) test. Cohort study. We included 218 patients from a 10-day physical therapy program after TKA. A latent class mixed model was used to classify patients according to their walking-speed trajectory during the program. We assessed the change in TUG test score from pre-TKA to 6 weeks and 1 year after TKA. The association between change in TUG test score and walking-speed trajectory was assessed using multivariable regression. There were 2 groups with distinct walking-speed trajectories: a high-gain group (46%) and a low-gain group (54%). There was no significant association between change in TUG test score and walking-speed trajectory after TKA and physical therapy. Function (based on TUG test performance) improved for all patients 1 year after TKA, irrespective of walking-speed trajectory (ie, high or low gain) early in postoperative physical therapy. Although we distinguished different groups based on functional outcomes during physical therapy, the clinical relevance of classifying patients based on walking speed remains unclear, as it did not predict short- and long-term functional outcomes. <i>J Orthop Sports Phys Ther 2021;51(7):362-371. Epub 10 May 2021. doi:10.2519/jospt.2021.10299</i>.