Reliability and minimal detectable change of the Step Test in patients with knee osteoarthritis

Introduction
The study aim was to evaluate the test-retest reliability and minimal detectable change of the Step Test in patients with knee osteoarthritis.

Methods
The intraclass correlation coefficient was used to assess the test-retest reliability of the Step Test. The minimal detectable change with 95% confidence interval (MDC95) was calculated to determine the true change. The inclusion criteria involved a diagnosis of knee osteoarthritis and age of ≥ 40 years.

Results
Thirty-eight participants who met the inclusion criteria were investigated. Seven were male and the mean age equalled 61.23 ± 9.31 years. Three patients had radiographic findings indicative of Kellgren-Lawrence grade II, 10 of grade III, and 25 of grade IV. The Step Test presented excellent test-retest reliability. The intraclass correlation coefficient was 0.97, standard error of the mean was 0.46, and the MDC95 was 1.27.

Conclusions
The Step Test is a reliable outcome measurement for the assessment of balance in patients with knee osteoarthritis, and it showed excellent test-retest reliability in these patients. The test may assist clinicians and researchers in evaluating balance and planning rehabilitation in patients with knee osteoarthritis.