Kinetic changes associated with extended knee landings following anterior cruciate ligament reconstruction in females

ObjectivesTo determine the relationship between knee flexion excursion symmetry and lower extremity kinematics, kinetics, and muscle, joint, and ligament forces in females 1–3 years after ACL reconstruction.DesignCross-sectional.SettingLaboratory.ParticipantsTwenty-one, college-aged females.Main outcome measuresLower extremity kinetics and kinematics, including estimated muscle, tibiofemoral, and ligament forces were assessed using 3D motion analysis and a musculoskeletal modeling approach. Participants demonstrating greater than 10% asymmetry in knee flexion excursion were classified as landing with an “extended knee”. Group and between-limb differences were compared.ResultsTen participants were classified as landing with an “extended knee” on the involved limb, while eleven exhibited a symmetric landing pattern. Participants landing with an “extended knee” demonstrated reduced knee extension moment and quadriceps force in the involved limb (p < 0.05).ConclusionsThese findings indicate that an “extended knee” landing pattern was associated with reduced knee extension moment and quadriceps muscle force in females 1–3 years after ACL reconstruction. This may represent an altered strategy that clinicians may choose to identify and address during rehabilitation.