Movement Repeatability During Landing Following Anterior Cruciate Ligament Reconstruction

Abstract

As many as 200,000 anterior cruciate ligament (ACL) injuries are diagnosed annually in the United States with 94% of these patients undergoing ACL reconstruction (ACLR). While ACLR and subsequent rehabilitation allow athletes to return to sports, they have a 15 fold increased risk of secondary ACL injuries. Discrete kinematic and kinetic asymmetries have been identified as secondary injury risk factors. PURPOSE: Determine the differences in sagittal plane knee angle and moment curves as well as the vertical ground reaction force (vGRF) curves between and within the surgical (S) and non-surgical (NS) limbs during landing six months following ACLR. METHODS: Three-dimensional motion capture was used to collect bilateral kinematic and kinetic data during 5 stop-jump trials on 20 adolescent patients (Age: 15.8±1.2 years) 6 months following ACLR. Patients were excluded if they had a previous ACLR, required additional surgical intervention, or were unable to complete the jumping assessment. Bilateral knee kinematic and kinetic as well as vGRF landing (initial contact - toe-off) ensemble curves were used for analysis. A coefficient of multiple correlation (CMC) was calculated between the S and NS side for each trial and were then averaged across trials to determine the symmetry CMC. In addition, the between trial CMC was calculated for both the S and the NS side for each patient. RESULTS: The between-limb symmetry was high for each variable (knee angle: 0.96 (range: 0.87-0.99), knee moment: 0.85 (range: 0.61-0.96), and vGRF: 0.73 (range: 0.38-0.95)), however, the repeatability appeared to be subject specific. The within-limb CMC for the NS side was higher (knee angle: 0.97 (range: 0.90 - 0.99), knee moment: 0.92 (range: 0.84-0.97), vGRF: 0.88 (range: 0.74-0.95)) than the within-limb CMC for the S side (knee angle: 0.96 (range: 0.87 - 0.99), knee moment: 0.90 (range: 0.81-0.97), vGRF: 0.86 (range: 0.74-0.93)). CONCLUSIONS: The landing patterns are highly repeatable across trials for all subjects on both limbs. However, the movement pattern asymmetries appear to be subject specific based on the range of CMC values reported. A subject specific analysis of symmetry could improve the understanding of movement quality and could be used in combination with discrete symmetry analysis to better understand secondary ACL injury risk.