Studying the Changes of Time To Stabilization (TTS) and Center of Pressure Velocity (CoP Velocity) in Athletes with an Unilateral Isolated Anterior Cruciate Ligament (ACL) Rupture in a Six-Month Follow-Up

Anterior cruciate ligament rupture has shown vast changes in kinematics and kinetics parameters. The aim of this study is to investigate the balance changes including of the time to stabilization (TTS) and velocity of the Center of Pressure (CoP) displacement in functional activities.

The present cohort study was conducted on 58 male and female professional athletes. The subjects were divided into two healthy and ACL-deficient knee groups, each with 29 subjects. The time to stabilization (TTS) and velocity of CoP displacement parameters in both anterior-posterior and medial-lateral directions were calculated in a forward jumping test on a force platform. The test was performed three times consisted on the end of the 2nd, 4th and 6th months post injury.

The results of this study showed that although in the ACL-D group, none of the TTS and CoP velocity parameters showed a significant difference during the six months after the injury (P=0.686 for TTS, P=0.603 for CoP velocity in AP direction and P=0.185 in ML direction), there was a significant difference between the healthy and ACL-D groups. The TTS was different between groups (P=0.494 for 2nd, P=0.008 for 4th and P=0.041 for 6th month post injury). The CoP velocity in AP direction did not show difference between groups (P=0.419 for 2nd, P=0.196 for 4th and P=0.36 for 6th month after injury) but in ML direction there was a significant difference between groups in 4th month post injury (P=0.359 for 2nd, P=0.01 for 4th and P=0.331 for 6th post injury).

In a six month period after ACL injury balance parameters change without a constant trend. CoP velocity in ML direction showed more significant and clear changes in comparison within and between groups. Considering all parameters, it seems between 2nd and 4th month improvement was occurred but no improvement was seen between 4th and 6th month. It can be said that most of the changes occur in the first months after the injury.