Gravity-assisted pivot-shift test can predict the function of the reconstructed anterior cruciate ligament

Abstract

The gravity-assisted pivot-shift (GAPS) test is a newly advocated test for anterior cruciate ligament (ACL) injury. We retrospectively investigated the relationships between the result of preoperative GAPS test and the function of the reconstructed ACL using autogenous hamstring tendon grafts. Seventy-eight patients with unilateral ACL injury and a minimum of 1-year follow-up were enrolled in this study. According to the result of preoperative GAPS test, they were divided into two groups, i.e., positive test group (Group P) and negative test group (Group N). At the time of follow-up, the operated knee was examined manually and using KT-1000 arthrometer. According to these results, the function of the reconstructed ACL was classified. The proportion of the knees with a negative abnormal laxity test was less in Group P than Group N with the significant difference in Lachman test (P=0.0029) and N-test (P=0.0081). The proportion of the cases having greater than 3mm of the side-to-side difference in anterior knee laxity using KT-1000 arthrometer was greater in Group P, in spite of no statistically significant difference. Regarding the classification of the function of the reconstructed ACL, Group P was worse than Group N (P=0.0187), and all 4 knees classified as failed belonged to Group P. The knees with a preoperative positive GAPS test showed worse postoperative function of the reconstructed ACL than those with a negative test. Preoperative positive GAPS test is considered to be a predisposing factor to poor functional outcome after ACL reconstruction. It is possible that the use of hamstring tendons as a graft source should be avoided for the ACL-injured patients with a positive GAPS test.