Background:Total knee arthroplasty (TKA) is a very common procedure, particularly implemented for the treatment of knee osteoarthritis (OA). Patient expectations after TKA surgery now include being able to enjoy appropriate recreational activities representing ambulatory activities beyond that of just pain relief and adequate knee motion (1). Since recreational activity comprises of more complex functions and requires longer standing durations, walking for 6-meter in a straight line in the timed up and go test (TUG) does not fully reflect the functional capacity of patients with TKA, and TUG test may be limited to detect the balance and mobility capacity in TKA patients (2, 3). As such, there is a need to determine more effective and functional evaluation tools that better reflect realistic situations in order to assess ambulatory performance level for patients with TKA. However, no studies have been conducted in patients with TKA to examine the applicability of the L-test, which assesses ambulation of individuals and consists of complex mobilization activity.Objectives:The purposes of this study were to determine the test-retest reliability and the minimal detectable change (MDC) of the L-test for TKA patients.Methods:Twenty-four patients with TKA due to knee OA, operated by the same surgeon, were included in this study. Patients performed trials for L-test twice on the same day. Between the first and second trials, patients waited for an hour on sitting position to prevent fatigue. The tester recorded the performance time while the participant was asked to get up from a chair, walk 3 m in a straight line, turn right, continue walking for 7 m in a straight line, turn left, walk back along the same path and sit down in the chair at their usual walking speed. Prior to the real testing session, the L-test was demonstrated by the tester and all participants were allowed to a practice trial.Results:The L-test showed an excellent test-retest reliability (ICC2,1= 0,98) in this study. Standard error of measurement (SEM) and MDC95for L-test were 1,01 second and 2,8 second, respectively.Conclusion:This study found that the L-test is a reliable test for patients following TKA. Overall, the excellent test-retest reliability of the L-test indicates that it may be an applicable standardized method to assess TKA patients who are able to walk greater distances and have better gait in more functional situations. Clinicians and researchers can be confident that changes in L-test time above 2,8 seconds, represent a “real” clinical change in an individual patient with TKA. We, therefore, recommend the use of L-test as complementary outcome measures for balance and functional evaluation in TKA patients.References:[1]Swinkels, A., & Allain, T. J. (2013). Physical performance tests, self-reported outcomes, and accidental falls before and after total knee arthroplasty: an exploratory study. Physiotherapy theory and practice, 29(6), 432-442.[2]Deathe, A. B., & Miller, W. C. (2005). The L test of functional mobility: measurement properties of a modified version of the timed “up & go” test designed for people with lower-limb amputations. Physical therapy, 85(7), 626-635.[3]Kim, J. S., Chu, D. Y., & Jeon, H. S. (2015). Reliability and validity of the L test in participants with chronic stroke. Physiotherapy, 101(2), 161-165.Disclosure of Interests:None declared