Isokinetic Muscle Performance and Functional Level after Anterior Cruciate Ligament Reconstruction

ABSTRACT

The purpose of this study was to evaluate the muscle performance and functional level after as well as the necessity of postoperative rehabilitation the anterior cruciate ligament reconstruction. We prospectively examined twenty patients after primary reconstruction of ruptured anterior cruciate ligament of the knee with the isokinetic tests of the knee and ankle joints using the Isokinetic Rehabilitation and Testing System (Model No. Cybex 6000), and the modified Cincinnati scale and Lysholm scale. The results showed that the values of peak torque, total work, power, and TAE(torque acceleration energy) of the involved knee extensors and flexors were significantly low compared to the uninvolved limb. The deficiency ratios of peak torque, total work, and power between uninvolved and involved limbs in knee extension and flexion at the angular velocity of 60 degrees/sec and 180 degrees/sec were more than 10%. The knee flexors to extensors imbalances(H/Q ratios) of uninvolved and involved limbs were 55.5+/-6.1% and 71.5+/-24.1% respectively at the angular velocity of 60 degrees/sec (p<0.01). The peak torque and total work of the ankle plantarflexors in the involved limbs decreased significantly compared to the uninvolved sides (p<0.01). Average scores of modifed Cincinnati scale and Lysholm scale were 87.3+/-6.6 and 87.1+/-7.2, respectively, and these functional scales correlated well to the deficiency ratios inversely (p<0.05). These results suggest that the isokinetic testing and functional scales are effective tools for the evaluation of muscle performances and functional levels after the anterior cruciate ligment reconstructions. Postoperative rehabilitation was needed to correct the muscle imbalance that existed in the knees after 34 months of anterior cruciate ligament reconstruction.