Limb differences in hamstring muscle function and morphology after anterior cruciate ligament reconstruction

Area of Science:

• Orthopedics
• Sports Medicine
• Rehabilitation Science

Background:

• Anterior cruciate ligament reconstruction (ACLR) can lead to long-term neuromuscular deficits.
• Understanding inter-limb asymmetries post-ACLR is crucial for optimizing recovery and function.

Purpose of the Study:

• To compare hamstring strength, muscle volume, and neural activity between ACLR patients and healthy controls.
• To investigate the relationship between hamstring neuromuscular function and subjective knee function in ACLR patients.

Main Methods:

• A cross-sectional laboratory study involving 11 individuals with a history of ACLR and 11 matched healthy controls.
• Evaluated hamstring isokinetic torque, muscle volume, and medial/lateral hamstring electromyographic (EMG) activity during a single leg hop task.
• Calculated limb-differences (%LD) and used International Knee Documentation Committee (IKDC) scores to assess subjective knee function.

Main Results:

• Individuals with ACLR exhibited significant inter-limb differences in medial hamstring EMG, biceps femoris short head volume, and semitendinosus volume.
• Lower semimembranosus muscle volume was significantly associated with lower IKDC subjective knee function scores.

Conclusions:

• Greater inter-limb differences in medial hamstring EMG and hamstring muscle volume (semitendinosus and biceps femoris long head) are present years after ACLR.
• These neuromuscular asymmetries may negatively influence long-term knee function following ACLR.