Engineering

Anterior cruciate ligament reconstruction

Surgery

Isometric exercise

Muscle stiffness

Thigh

Anterior cruciate ligament

Rehabilitation

Anatomy

Physical therapy

Sports medicine

Structural engineering

Medicine

Physical medicine and rehabilitation

Stiffness

Electromyography

BMC Musculoskeletal Disorders

Background Altered motor unit (MU) activity has been identified after anterior cruciate ligament (ACL) injury, but its effect on muscle tissue properties is unknown. The purpose of this study was to compare thigh musculature muscle stiffness between control and ACL-injured subjects. Methods Thirty ACL-injured subjects and 25 control subjects were recruited. Subjects completed a randomized protocol of isometric contractions while electromyography (EMG) signals were recorded. Three maximum voluntary isometric contractions (MVIC) determined peak force for 10 and 25% MVIC trials. Shear wave elastography was captured during each 10 and 25% MVIC trials. Results Differences in muscle stiffness were assessed between limbs and groups. 12 months post-surgery had higher stiffness for VM 0% MVIC, VL 0 and 10% MVIC, and ST 10 and 25% MVIC (all p ≤ 0.04). Conclusion Thigh musculature stiffness changed throughout rehabilitation and remained altered at 12 months after ACL reconstruction.

Thigh musculature stiffness during active muscle contraction after anterior cruciate ligament injury