Beyond peak torque: Longitudinal analysis of angle-specific isokinetic knee torques in collegiate athletes post-ACLR

Abstract

ObjectivesTo investigate changes in angle-specific knee extensor torque between limbs from 4 to 12 months post-anterior cruciate ligament reconstruction(ACLR) in Division I collegiate athletes at two different isokinetic velocities. DesignCase-series study. SettingLaboratory-based. ParticipantsIsokinetic knee flexion and extension assessments of 17 athletes (11 female) at 4, 8, and 12 months after ACLR with bone-patellar tendon-bone autograft were evaluated. Main outcome measuresAngle-specific curve analyses were performed using statistical parametric mapping for torque data obtained between 14 and 101° at 60°/s and 240°/s velocities. ResultsAt 60°/s, knee extensor torque of the operated limb increased between 4 and 8 months (18–101°,p < 0.001), 4 and 12 months (28–101°,p < 0.001), and 8 and 12 months post-surgery (62–70°,p = 0.002, and 79–90°,p < 0.001). Knee extensor torque was lower in the operated limb compared to the non-operated limb at 4 (47–97°,p < 0.001) and 8 months (65–90°,p < 0.001) for 60°/s, at 4 (21–89°,p < 0.001) and 8 months (50–77°,p < 0.001) for 240°/s, with no between-limb differences at 12 months post-ACLR for both velocities. ConclusionsOperated limb knee extensor torque increased throughout the majority of knee range of motion from 4 to 12 months post-ACLR at both isokinetic velocities, while non-operated limb torque only improved through a reduced arc of motion in greater knee flexion angles.