The aim of the study was to evaluate balance during the landing phase in a control group and patients after anterior cruciate ligament reconstruction (ACLR). ACL tear is a frequent injury, particularly in athletes. It often requires proper rehabilitation, during which time the patients should be re-evaluated. We performed a jump-down assessment using a motion capture and force platform system. The tests comprised a series of time-space and dynamic parameters measurements using a motion capture

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... ystem and a force plate. We tested 28 men (22 controls and 6 patients who had undergone ACLR). The tests are conducted under jump-down conditions (0.1-, 0.2-, and 0.3-m step heights). We compared horizontal components of force during the landing phase. The division of registered three-dimensional (3D) motion was demonstrated, and the fluctuations of the estimated center of gravity (eCOG) during this motion were analyzed. Compared with the controls, patients showed statistically significant differences in fluctuations in the eCOG repositioning and horizontal components of force ratios (t-test, p<0.05). We propose a comparative assessment of balance attainment during the landing phase of a jump. We indicate the possibility of efficient detection of ACL injuries. In summary, horizontal ground reaction forces and eCOG positioning can be used to evaluate the performance of the human biomechanical system during the jump-down phase. A. Melinska et al. Balance Assessment during the Landing Phase of Jump-Down in Healthy Men and Male Patients after ACL Reconstruction -78 -