Early Neuromuscular and Co-activation Patterns After Anterior Cruciate Ligament Reconstruction In Males: A...

Area of Science:

• Orthopedics
• Sports Medicine
• Rehabilitation Science

Background:

• Arthrogenic muscle inhibition (AMI) post-ACL reconstruction (ACLR) hinders muscle recovery.
• Early neuromuscular profiles (within 2 weeks) are poorly understood.
• Excessive hamstring co-activation may worsen knee mechanics and rehab outcomes.

Purpose of the Study:

• Compare early quadriceps activation and hamstring co-activation in ACLR patients versus healthy controls.
• Investigate bilateral neuromuscular alterations in operated and non-operated limbs post-ACLR.

Main Methods:

• Cross-sectional study of 15 ACLR patients and 15 controls, assessed ~2 weeks post-surgery.
• Surface electromyography (sEMG) measured quadriceps (VL, VM) and hamstring (BF, MH) activity during maximal voluntary isometric knee extensions.
• Co-activation Indices (CoI) calculated for agonist-antagonist muscle pairs.

Main Results:

• ACLR group showed significantly lower quadriceps activation (VL, VM) in the operated limb compared to controls.
• ACLR group exhibited significantly higher hamstring co-activation (VL-BF, VM-BF, VL-MH, VM-MH) in the operated limb.
• Increased hamstring co-activation was also observed bilaterally in the ACLR group, including the non-operated limb.

Conclusions:

• Early post-ACLR, reduced quadriceps activation and increased bilateral hamstring co-activation are present.
• These neuromuscular alterations affect both operated and non-operated limbs, suggesting a systemic response.
• Findings highlight potential targets for early intervention to improve ACLR rehabilitation.