Longitudinal evaluation of stair walking biomechanics in patients with ACL Injury

Purpose: After anterior cruciate ligament (ACL) injury and reconstruction, abnormal biomechanics during daily tasks may have prominent and detrimental long-Term consequences on knee joint health. The purpose of this study was to longitudinally evaluate hip and knee joint biomechanics during stair ascent and descent in patients with acute ACL injury and at return to activity after ACL reconstruction. Methods: Twenty individuals with unilateral ACL injury (age, 20.9 ± 4.4 yr; height, 172.4 ± 7.5 cm; mass, 76.2 ± 12.2 kg) that were scheduled to undergo surgical reconstruction were compared with 20 healthy matched controls (age, 21.7 ± 3.7 yr; height, 173.7 ± 9.9 cm; mass, 76.1 ± 19.7 kg). Lower extremity biomechanics were recorded using three-dimensional motion analysis during stair ascent and descent at two testing sessions (before surgery and at approximately 6 months after surgery or when they were allowed to return to unrestricted physical activity). Time between sessions for healthy participants was matched on the basis of the ACL group. Peak sagittal and frontal plane knee and hip joint angles and moments, joint angles at initial contact, and joint excursions across stance phase were evaluated. Results: The ACL-injured limb of patients experienced smaller knee extension moments than the uninjured limb and healthy controls during stair ascent and descent (P < 0.05) before and 6 months after ACL reconstruction. During stair ascent, ACL patients experienced more extended knee joint positions and less sagittal plane knee joint excursions, coupled with greater frontal plane hip joint excursions (P < 0.05). Conclusions: Patients with ACL injury experience reductions in knee flexion angle and knee extension moments during stair walking. These alterations were observed both before and after reconstruction, suggesting that early gait retraining interventions may be beneficial in these patients.