Risk factors for anteroposterior laxity increase over time in double-bundle anterior cruciate ligament reconstruction using hamstring autografts.

Abstract

An anteroposterior (AP) laxity can increase over time after anterior cruciate ligament reconstruction (ACLR) using hamstring tendons; however, the associated risk factors remain unclear. This study aimed to investigate the risk factors of this phenomenon. Overall, 151 patients who underwent ACLR using hamstring autografts were recruited. AP laxity was evaluated using Knee Lax 3 arthrometer at 5 months, 1 and 2 years postsurgery. Patients were categorised into groups I (>1 mm increase) and C (<1 mm increase) based on whether they experienced an irreversible increase in AP laxity after 1 or 2 years compared with 5 months. Patient demographics and Knee injury and Osteoarthritis Outcome Score (KOOS) at 2 years postsurgery were compared between groups. Group I (n = 33, 21%) showed a side-to-side difference of 4.6 (3.0-7.2) mm in AP laxity preoperatively and 0.3 (-0.7 to 1.3), 1.1 (0.2-1.9) and 2.4 (1.7-3.2) mm at 5 months, 1 and 2 years postoperatively, while group C (n = 119, 79%) showed 4.3 (2.8-5.7) mm preoperatively and 1.3 (0-1.9), 0.9 (0.1-1.8) and 0.6 (-0.3 to 1.5) mm, respectively. No significant differences were observed in the overall KOOS at 2 years (n.s.). However, group I was older (36 [22-46] vs. 28 [19-39] years; p = 0.044), had longer surgical waiting periods (122 [69-341] vs. 81 [52-136] days; p = 0.041) and lower preoperative Tegner activity scale scores (6 [5-7] vs. 7 [6,7]; p = 0.002). While 33 patients (21%) experienced AP laxity increase over time, they had comparable clinical outcomes with group C. Level III.