BILATERAL LOWER EXTREMITY ASYMMETRIES IN INDIVIDUALS POST-ACLR DURING HIGH-RISK TASKS

J.A. Ter Har1, J.J. Hannigan2, C.D. Pollard1,2 1Oregon State University, Corvallis, OR; 2Oregon State University-Cascades, Bend, OR Individuals who undergo anterior cruciate ligament reconstruction (ACLR) are approximately 15 times more likely to suffer a second anterior cruciate ligament injury, but the underlying reason for this phenomenon is unclear. Recent research has shown that individuals post-ACLR exhibit kinematic limb asymmetries during running and various hop tests. However, few studies have assessed limb asymmetry post-ACLR during a high-risk task such as cutting and drop-landing. PURPOSE: To assess kinematic asymmetry between ACLR and healthy limbs during a cutting and drop-landing task. METHODS: Subjects consisted of 12 individuals post-ACLR (seven females and five males) who were cleared by their orthopedic surgeon to return to full activity. Subjects ran down a 7-meter runway and performed a 45-degree cutting maneuver in the direction opposite to their planting limb. This task was performed for the right and left limb. Subjects then performed a drop-landing task by dropping down off a box and then immediately performing a maximal effort vertical jump. Four successful trials of each task were collected using an 8-camera 3D motion analysis system (250 Hz) and software was used to calculate joint kinematics. Paired t-tests compared kinematics between limbs for both tasks (α = 0.05). RESULTS: During the cutting task peak hip flexion was significantly greater in the non-surgical limb (p = 0.029), and a trend for greater peak knee flexion was found in the non-surgical limb (p = 0.068). Sagittal plane excursions were also greater at the hip (p \u3c 0.01), knee (p = 0.041), and ankle (p = 0.019) in the non-surgical limb. During the drop-landing task there was a trend for greater sagittal plane excursion at the knee (p= 0.08) and ankle (p= 0.055) in the non-surgical limb. Combined sagittal angle excursion of the hip, knee, and ankle were greater for the non-surgical limb during the cutting task (p \u3c 0.01) and a similar trend was seen during the DVJ task (p= 0.057). CONCLUSION: These findings support that asymmetries exist between ACLR and healthy limbs after returning to full activity, especially during a cutting task. The magnitude of the asymmetries seems to be single-limb task specific. This avoidance behavior of the surgical limb suggests that further rehabilitation is necessary in these ACLR individuals in an effort to reduce their risk of re-injury