Reliability of the Star Excursion Balance Test with End-Stage Knee Osteoarthritis Patients and Its Responsiveness Following Total Knee Arthroplasty

Background/Objectives: The Star Excursion Balance Test (SEBT) is a simple and feasible tool for assessing dynamic balance in individuals with knee osteoarthritis (KOA). It has an advantage as it replicates dynamic balance better than other static balance tools. This study aims to determine how reliable SEBT is among people with end-stage KOA, as well as how responsive it is and how well it correlates with performance-based outcome measures after TKA. Methods: Patients on the waiting list for TKA performed SEBT in the anterior, posteromedial and posteriorlateral directions twice within 7 days. The measurements were repeated 6 and 12 months after TKA. The participants completed performance-based outcome measurements (PBOMs) and the Oxford Knee Score (OKS) before and after TKA to estimate correlation. Results: In all directions, the intraclass correlation coefficient range (ICC) was 0.998-0.993, and there were no significant differences between the test and re-test mean SEBT scores. The standard error of measurement (SEM) ranged from 0.37% to 0.68%, and the minimum detectable change (MDC) ranged from 1.02% to 1.89%. The post TKA SEBT results show significant improvement, with a large effect size. There were large-to-medium correlations between SEBT and PBOMs before and after TKA, while OKS correlated only before surgery. The magnitude of change in SEBT, PBOMs and OKS did not correlate. Conclusions: SEBT is an extremely reliable tool for assessing dynamic balance in all three directions of severe KOA patients. It is sensitive enough to detect balance changes at 6 and 12 months post TKA. SEBT cannot be used to reflect the change in functional outcome improvement after TKA.