Knee Extensor Muscles Function in Individuals with Anterior Cruciate Ligament Surgery During Landing

Identifying neuromuscular adaptations in knee muscle activity after anterior cruciate ligament reconstruction in daily tasks has clinical value. This study aimed to investigate the electromyographic activity of selected lower limb muscles in people with anterior cruciate ligament reconstruction and healthy people descending from two heights of 25 and 40 cm.

Ten males who had undergone Anterior Cruciate Ligament Reconstruction (experimental group) and ten healthy males (control group), all aged between 20 and 30, were included in the study. The electromyographic activity of the Vastus Medialis Oblique, Vastus Lateralis, Rectus Femoris, Biceps Femoris, and Gastrocnemius muscles in landing from heights of 25 cm and 40 cm was measured using a surface BTS-EMG system (2000 Hz). The signals' maximum Root Mean Square values were normalized based on Maximum Voluntary Isometric Contraction and then compared between the two groups.

At a height of 25 cm, the muscles' EMG activity, except for the RF muscle, was lower in the Anterior Cruciate Ligament Reconstruction group than in the control group. The root mean square of Vastus Medialis Oblique in the anterior cruciate ligament reconstruction and control groups were significantly different (P=0.026). The results showed that at the height of 40 cm, the Root Mean Square in the Anterior Cruciate Ligament Reconstruction group was lower than that in the control group. Also, the level of Biceps Femoris activity in the Anterior Cruciate Ligament reconstruction group and the control group was statistically significant (P=0.013).

Two years after anterior cruciate ligament surgery, there were no differences in knee muscle activity during landing from different heights. More research is needed on gender differences, graft types, functional status, and the association between muscle activity patterns and re-injury risk.