Knee extension torque variability after exercise in ACL reconstructed knees.

Area of Science:

• Biomechanics
• Neuromuscular Control
• Orthopedic Rehabilitation

Background:

• Anterior cruciate ligament (ACL) reconstruction surgery is common for knee injuries.
• Post-surgical rehabilitation aims to restore normal knee function and neuromuscular control.
• Torque variability may reflect underlying neuromuscular deficits after ACL reconstruction.

Purpose of the Study:

• To compare knee extension torque variability in ACL-reconstructed (ACL-R) patients versus healthy controls.
• To assess the effect of a standardized exercise protocol on knee extension torque variability in both groups.

Main Methods:

• Maximal isometric knee extension torque was measured at 90° flexion in ACL-R patients and controls.
• Measurements were taken at baseline and after a 30-minute exercise protocol (treadmill walking and hopping).
• Knee extension torque variability was quantified using the coefficient of variation (CV) and change in CV (ΔCV).

Main Results:

• ACL-R patients demonstrated significantly greater baseline and post-exercise knee extension torque variability (CV) compared to controls.
• The increase in torque variability (ΔCV) from baseline to post-exercise was significantly larger in the ACL-R group.
• Exercise led to a significant increase in torque variability in the ACL-R group, but not in the control group.

Conclusions:

• ACL reconstruction is associated with increased knee extension torque variability.
• Exercise exacerbates torque variability in individuals with ACL-reconstructed knees.
• These findings suggest persistent neuromuscular control impairments following ACL reconstruction that are sensitive to physical exertion.