[(Neuro)muscular changes in the knee stabilizing muscles after rupture of the anterior cruciate ligament]. / (Neuro)Muskuläre Veränderungen der kniegelenksstabilisierenden Muskulatur nach Ruptur des vorderen Kreuzbandes.

Recent data indicate that the function of the knee joint may be the result of a complex synergy between bones, ligaments, muscles and proprioceptive receptors in these structures. Therefore, it was the aim of this study to investigate if muscular changes could be found more than 5 years following ACL-injury and if there are therapy-dependent differences. 35 patients with ACL-reconstruction and 25 conservatively treated patients were studied. The thigh circumference was measured and in 5 randomly selected patients of each group additionally MRI cross-sections of both limbs were made. Using an isokinetic dynamometer and an EMG device the relation of strength, electrical activity and muscle size were analyzed. Only minimal differences in thigh circumference as well as in muscular cross sections were found between the uninjured and injured limb of both groups; however, the isokinetic torque and iEMG values showed significant differences. It may be assumed that the major reason for these results is a modified muscle fiber utilization in the ACL-injured limb, caused by a changed joint receptor afferent inflow or a compensation of the central nervous system to primary alterations of the muscle fibers.