800 EP058 – Assessing knee kinematics relationship between modified drop squat and running after anterior cruciate reconstruction

Background Asymmetry in knee joint kinematics during running after anterior cruciate ligament reconstruction (ACLR) could indicate insufficient recovery of knee functions and might lead to re-injury or secondary knee osteoarthritis. We developed 'Modified Drop Squat' (MDS) exercise to assess and improve the asymmetry of knee kinematics during running after ACLR. Objective To investigate the utility of MDS exercise for detecting altered knee kinematics during running after ACLR. Design A cross-sectional observational clinical design. Setting Clinical laboratory in a hospital's physical therapy department. Patients Thirty-seven patients after ACLR (22 males, 15 females; average age of 24.5 ± 10.1 years) were included and assessed at 3 months after surgery. Interventions The patients performed MDS exercise with a quick knee flexion from standing on tiptoe to squatting down with 40 degrees of flexion on the affected leg, in addition to running with a comfortable pace. Both angular velocity of knee flexion in MDS and knee flexion angle (KFA) during running were analyzed with a video analysis. Main Outcome Measurements The deficit of the peak flexion angular velocity in MDS and the side-to-side difference (SSD) of the maximum KFA during running were calculated. Spearman9s rank correlation analysis evaluated the relationship between the two values. Results A strong correlation (r=0.82, p<0.05) was identified between the peak flexion angular velocity in MDS and the SSD of the maximum KFA during running. Conclusions Assessing the peak flexion angular velocity in MDS effectively detected asymmetry in knee joint kinematics during running after ACLR. This approach has a potential for identifying the risk of re-injuries after ACLR and might contribute to prevention re-injury or secondary knee osteoarthritis. Further research is needed to validate these findings for clinical application.