M. Kaiyala, C.D. Pollard, A. Traut, J.J. Hannigan

Oregon State University – Cascades, Bend, OR

250,000+ individuals injure their anterior cruciate ligament (ACL) in the United States each year. Individuals post-ACL surgical reconstruction (ACLR) are at elevated risk for ACL re-injury, potentially due to kinematic and kinetic asymmetries between the lower extremities. Several studies have examined biomechanical asymmetries at the hip and knee post-ACLR during landing. However, less is known about asymmetries during a sidestep cut. PURPOSE: To investigate sagittal and frontal plane kinematic and kinetic asymmetries at the hip and knee during a 45° sidestep cut in post-ACLR participants and healthy controls. METHODS: 19 recreational athletes post-ACLR who have returned to sport (RTS) and 19 healthy control participants performed a bilateral 45° sidestep cut while three-dimensional kinematics and ground reaction forces were measured. Sagittal and frontal plane kinematics and internal joint moments were examined at the hip and knee during stance phase. Paired t-tests were used to evaluate intra-group differences between limbs within the post-ACLR group and the control group (p ≤ 0.05). RESULTS: The post-ACLR group exhibited unilaterally lower peak hip extension (ACLR: -11.53° ± 9.26°; non-surgical: -16.09° ± 11.83°; p = 0.02), peak knee flexion (ACLR: 44.16° ± 10.20°; non-surgical: 48.20° ± 6.81°; p = 0.03), hip flexion excursion (ACLR: 52.84° ± 11.34°; non-surgical: 58.65° ± 9.16°; p = 0.03), knee flexion excursion (ACLR: 26.88° ± 6.55°; non-surgical: 32.12° ± 5.92°; p < 0.001), and peak knee extensor moment (ACLR: -2.61 ± 0.70 Nm/kg; non-surgical: -3.14 ± 0.43 Nm/kg; p < 0.001) in the ACLR limb compared to the non-surgical limb. No frontal plane asymmetries were observed in the ACLR group. In contrast, healthy controls exhibited a lower peak hip abductor moment in the right limb compared to the left limb (right: 1.46 ± 0.35 Nm/kg; left: 1.68 ± 0.41 Nm/kg; p = 0.02). CONCLUSION: The post-ACLR group exhibited altered sagittal plane movement in the ACLR limb that suggests avoidance, which was not demonstrated by the control group. Future research should investigate best methods to target and correct these movement asymmetries post-ACLR.

Supported by the Oregon State University – Cascades Layman Fellowship.

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