Activation and torque deficits in ACL‐reconstructed patients 4 months post‐operative

Abstract

This study compares knee extension and flexion torques and electromyographic (EMG) activity of normal and anterior cruciate ligament (ACL)-reconstructed knees during maximal unilateral isometric and isokinetic tests performed 4-5 months after ACL reconstruction. The subjects consisted of 3 age-and activity-matched groups of 6 subjects: a healthy control group (Ctrl) and 2 groups of patients, with Kenneth-Jones technique using autologous patellar-ligament graft (KJ group) and autologous graft from the semitendinosus tendon (ST group). When compared to the Ctrl group values, each patient group had significant bilateral extension torque deficits in isometric and at slow velocity concentric conditions. In the Op leg, this deficit was associated with lower quadriceps EMG activation. In all tests, bilateral hamstring co-activation level was lower in the patient groups. Flexion torque deficits were observed in the Op leg of both patient groups and in the Nop leg of the KJ group, with minor differences in either hamstring EMG activation or quadriceps co-activation. The inter-leg difference in extension and flexion torques were significant for both patient groups, but only in the isometric strength test, and with no difference in activation. These data demonstrate bilateral knee extension and flexion torque deficits a few months after ACL reconstruction. The observed deficit in quadriceps activation emphasizes the interest to perform combined EMG and strength testings quite early during the rehabilitation period.

Isokinetic Muscle Performance After Anterior Cruciate Ligament Reconstruction: A Case-Control Study

“…These differences may be related to the injury, since control of movement during acceleration could be affected, and the ability to attain the specific isokinetic velocity at a given range of motion may also be impaired. 33 Moreover, the TAV 3D , which provides a qualitative evaluation, demonstrated that the control group was able to maintain higher torques at higher velocities. In flexor and extensor muscles, the range of motion and the distribution of the torque during the range can change in post ACLR patients.…”