Reliability, validity, responsiveness and minimal important changes of common clinical standing balance tests in individuals with knee osteoarthritis.

Introduction: Standing balance is essential for physical functioning. Therefore, improving balance control is a key priority in the management of knee osteoarthritis (OA), underscoring the importance of accurately assessing standing balance.

Purpose: To assess reliability, construct validity and responsiveness of common clinical balance tests, including Step Test, Single-Leg Stance Test, and Functional Reach Test, in patients with knee OA.

Methods: In the initial session, 100 participants underwent balance tests and completed Persian-version of Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Timed Up and Go Test (TUG) as comparators for evaluating the construct validity of balance tests. For test-retest reliability, a subset of 70 participants repeated balance tests 1 week after initial assessment. To examine responsiveness, a subset of 90 participants underwent tests and completed WOMAC and TUG at baseline and after completing intervention. At post-intervention assessment, participants also completed global rating of change scale.

Results: Three balance tests showed excellent test-retest reliability (intra-class correlation coefficient >0.75). All balance tests were considered valid and responsive because they confirmed 100% of priori hypotheses. Minimal detectable change (MDC) values were 2.71 steps for Step Test, 7.15 seconds for Single-Leg Stance Test, and 4.90 centimeters for Functional Reach Test. Minimal important change (MIC) values were 4.5 steps for Step Test, 13.10 seconds for Single-Leg Stance Test, and 5.5 centimeters for Functional Reach Test.

Conclusion: Three tests are reliable, valid and responsive for measuring balance in patients with knee OA. The MIC values aid clinicians and researchers in assessing the clinical relevance of changes in balance for these patients.