A Comparison of core Muscles Onset Timing among Healthy Subjects and Patients after Anterior Cruciate Ligament Reconstruction during Drop Landing Task

Introduction: Most knee anterior cruciate ligament injuries happen during challenging activity like drop landing. Core muscles feedforward activity can control challenging activity and prevent injury. The aim of this study is to investigate core muscles feedforward activity in patients after anterior cruciate ligament reconstruction (ACLR) and control group. Materials and Methods: 11 males with ACLR, between 18-40 years old, with at least 6 to 24 months after surgery and 11 males as control group were enrolled in this study. Muscle activity of geluteus medius, abdominis external oblique, quadratus lumborum and erector spine in landing was recorded in both groups. Cross hop functional test and International Knee Documentation Committee (IKDC) questionnaire were evaluated and compared in both groups. Significance level was considered less than 0.05 in all analysis. Results: Score of IKDC subjective questionnaire and cross hop functional test in control group were significantly more than the score of patients (P ≤ 0.001 questionnaire, P = 0.039 functional test). Feedforward response time for gluteus medius (P = 0.028), abdominis external oblique (P = 0.030) and erector spine (P = 0.028) in control group was significantly sooner than patients with ACLR. Quadratus lumborum was not significantly different in these two groups (P = 0.191). Conclusion: Muscle activity and its pattern in these groups were different. Patient group did not have appropriate feedforward activity, they also demonstrate decrease in functional test and IKDC questionnaire. These results shows a problem and necessitate a rehabilitation program