Neuromechanical characteristics in the knees of patients who had primary conservative treatment for a torn cruciate ligament and reconstruction afterward.

Background/purpose: To compare the neuromechanical characteristics and subjective outcomes for knees of patients with a cruciate ligament tear and reconstruction with those for knees of controls at three time intervals, and to determine correlations between the characteristics and subjective outcomes.

Methods: Ten participants with a cruciate ligament tear and at least a 12-week conservative treatment prior to ligament reconstruction were prospectively measured prior to and 3 months and 6 months after surgery. Ten healthy individuals were recruited as controls. Questionnaire surveys regarding the injured knee were conducted, as were bilateral measurements of root mean square electromyography (EMG), the rate of EMG rise, the median frequency in the vastus medialis of the quadriceps muscles and antagonist coactivation from the semitendinosus muscle, and force capacities, including peak torque, rate of force development, and total works of the knee extension. Correlations between the EMG variables (of the vastus medialis and semitendinosus) and the force capacities, and between the EMG variables and the knee injury and osteoarthritis outcome scores (KOOS), and between force capacities and the KOOS were assessed in the participants with a ligament reconstruction.

Results: Pre- and postoperative results of EMG variable and force capacities were lower in both knees of the experimental group participants than in the control group participants (all p < 0.05). Correlations between EMG and force capacities, and between these parameters and the KOOS were found.

Conclusion: There were bilateral neuromechanical defects in the knees of the participants who had undergone conservative treatment as well as reconstruction after a cruciate ligament tear.