908 EP005 – Mind the gap: adolescent females cleared for return after ACL reconstruction make big gains but fail to match the functional capacity of their maturing peers

Background Preventing re-injury when returning to play (RTP) following ACL reconstruction (ACLr) presents challenges in the female adolescent population since they must not only recover from injury, but also keep up with their maturing non-injured peers through puberty. Objective To compare the functional capacity of adolescents pre-and post-ACLr with an adolescent control (CON) group across a similar time span. Design Repeated measures group comparison of ACLr and non-injured female adolescents performing one-legged anterior and lateral hops, timed six-meter hops, crossover hops, and triple hops during two separate visits (pre- and post-operatively, or 8–12 months after visit-1). All ACLr participants were cleared for RTP prior to visit 2. Setting Human movement biomechanics laboratory Patients Twenty-nine female ACLr (ageV1= 15.0±1.4, ageV2 = 15.8 ±1.6) and 28 CON participants (ageV1 = 13.0±1.6, ageV2 =14.3±1.9) with similar activity and sports participation. Main outcomes Jump distances and times at visits 1 and 2, and rate-of-change between visits, evaluated with Welch's t-test and Cohen's d. Results CON participants jumped farther for lateral hops (p=0.004, d=0.840), cross hops (p=0.025, d=0.685) and triple hops (p<0.001, d=1.06), and faster for timed-6-meter hops (p=0.03, d=0.641) at visit 1. Both groups improved from at the same rate of change between visits. At visit 2, CON participants jumped farther for cross hops (p=0.022, d=.630) and lateral hops (p=0.009, d=0.714), and were faster for 6-meter hops (p=0.018, d=0.646). Conclusion The ACLr group increased performance in all tests at RTP, however they did not close the functional capacity gap with their peers, despite the lower age of our CON participants. This functional deficit at RTP may contribute to the high risk of re-injury in the adolescent female population. RTP goal setting must therefore be based not only on their contra-lateral limb, but also the functional capacity of their activity-matched peers.