Reliability, concurrent validity and minimal detectable change of the L test in patients with total knee arthroplasty

Purpose The L test is a modified version of the timed up and go test (TUG), extending the walking distance from 6 to 20 meters and also requiring participants to make four turns in both (right/left) direction. It could be a useful measurement method in assessment of functional mobility for patients with Total Knee Arthroplasty (TKA). The aim of the study was to determine reliability, concurrent validity, and minimal detectable change (MDC) of L test in patients with TKA. Materials and methods The study included 43 patients with TKA. The Intraclass Correlation Coefficient (ICC) was used to assess the intra-rater reliability of the L test. The correlations of the L test with TUG were assessed for concurrent validity. Results Intra-rater (ICC 0.97) reliability of the L test was determined to be excellent. The SEM and MDC95 values of intra-rater reliability were 1.03 and 2.84, respectively. A high correlation was found between the L test and TUG (r: 0.75). Conclusion The L test is a valid and reliable method in the assessment of functional mobility in patients with TKA. The L test can be used to quantify changes in functional mobility level in patients with TKA. IMPLICATIONS FOR REHABILITATION The L test is a reliable and valid measurement tool that can be used to assess functional mobility in patients with TKA. Clinicians and researchers can use a greater change than 2.84 seconds for the L test as a meaningful change in patients with TKA.