Inter-joint Coordination Changes During Cutting Maneuver Performance In Patients Returning To Sport After ACL Reconstruction

PURPOSE: To compare sagittal-plane knee-ankle (KA) and hip-knee (HK) coordination between patients who had ACLR and matched uninjured participants during cutting maneuver performance. METHODS: 23 patients (17 M/6F; age 26±7 yr, time from surgery 9.8±2.4 mo) who had ACLR were compared to 13 uninjured participants (11 M/2F, age 27±5 yr). All participants performed five trials of 45° cutting maneuver, as quickly as possible, as part of return to sport testing. Ground reaction forces were measured to define stance phase. Hip, knee, and ankle sagittal-plane kinematic data were collected for involved limb of patients and dominant limb of uninjured participants during stance and were plotted in angle-angle plots separately for KA and HK joint couples. Vector coding was applied to derive coupling angles, each of which was interpreted as in-phase vs. anti-phase (moving in same vs. opposite directions) and proximal-dominant vs. distal-dominant (more movement in proximal than distal vs. more movement in distal than proximal joint) coordination pattern. Frequency of each coordination pattern was expressed as percent of stance phase. Cutting maneuver completion time was derived from kinematic data and compared between groups with independent samples t-test. Independent samples t-test was used to compare percent of stance spent in in-phase proximal dominant coordination pattern (the predominant pattern during stance phase of cutting maneuver) for KA and HK between patients and uninjured participants. RESULTS: Cutting maneuver completion time was not different between groups (patients 1.18±0.16 s vs. uninjured participants 1.13±0.07 s, p=0.41). Patients spent less time (24.3±8.2% of stance) in KA in-phase proximal dominant coordination pattern compared to uninjured participants (32.8±10.2%, p=0.02). No significant difference was found for HK in-phase proximal dominant coordination (patients 39.1±9.4% vs. uninjured participants 42.0±10.3%, p=0.41). CONCLUSIONS: Patients after ACLR performed the cutting maneuver with less knee-dominant KA coordination pattern compared to uninjured participants. This emergent coordination pattern appears to enable patients to compensate sufficiently in performing a cutting maneuver.