The test-retest reliability of a one legged hop for distance in young adults with and without ACL reconstruction

This investigation was designed to determine the test-retest reliability of a functional one legged hop test for distance in individuals with and without anterior cruciate ligament (ACL) reconstruction. Twenty subjects (X = 20.85 years) with no prior history of lower extremity injury, and 13 subjects (X = 22.40 years) with ACL reconstruction participated in this study. Testing occurred on two separate days with at least 24 h between testing sessions. The subjects executed a protocol consisting of a 5-min warm-up on a stationary bike, followed by three separate trial hops. This was followed by three separate hops which were measured and recorded. The distance travelled for each hop was measured using a standard measuring tape. The same protocol was then repeated on the contralateral limb. The leg tested first was randomized with each subject. The subjects were then asked to return on the second day, wearing the same pair of athletic shoes, and repeat the identical protocol. The mean of the three hops were used in data analysis. Paired t-tests revealed no significant difference between the dominant and non-dominant legs on either pre-test or post-test in subjects with healthy knees. A significant difference was found when comparing involved to uninvolved limb on both the pre-test and post-test in patients with ACL reconstruction. There was no significant difference found from pre-test to post-test on either the dominant or non-dominant legs in healthy subjects or from the involved to uninvolved in patients with ACL reconstruction. Interclass correlation coefficients (ICC) revealed values of 0.92 and 0.96 for dominant and non-dominant legs, respectively. For individuals with ACL reconstruction, ICC values were 0.89 for both the involved and uninvolved limb. The results of this study suggest that the one legged hop test for distance is a reliable test for both young adults with healthy knees and those who have had ACL reconstruction. This test, along with others, may aid clinicians in determining whether patients are ready to return to prior level of activity.