Reliability of the Modified Four Square Step Test (mFSST) in patients with primary total knee arthroplasty

Purpose: The aim of the present study was to determine the test-retest reliability of the modified four square step test (mFSST) in patients with primary total knee arthroplasty (TKA). Methods: Twenty-eight patients with primary TKA were included in this study. Patients performed two mFSST trials on the same day. Results: The mFSST showed excellent test-retest reliability in this study. Intraclass correlation coefficient [ICC(2,1)] for FSST was 0.97. Standard error of measurement and smallest real difference at the 95% confidence level for mFSST were 0.80 and 2.24, respectively. Conclusions: The mFSST has an excellent test-retest reliability in patients with primary TKA. It is an effective and reliable tool for measuring dynamic balance and mobility in patients with primary TKA. As a clinical test, the mFSST is easy to score, quick to administer, requires little space, has no cost and needs no special equipment