Anatomic and non-anatomic anterior cruciate ligament posterolateral bundle augmentation affects graft function

Area of Science:

• Orthopedic surgery
• Biomechanics
• Biomedical engineering

Background:

• Posterolateral (PL) bundle injuries often accompany anterior cruciate ligament (ACL) tears.
• Surgical techniques for PL bundle reconstruction aim to restore knee stability and function.
• The optimal graft placement for PL bundle augmentation remains a subject of investigation.

Purpose of the Study:

• To compare knee laxity and graft function between anatomic and non-anatomic PL bundle augmentation.
• To evaluate the biomechanical performance of different PL augmentation techniques in a porcine model.

Main Methods:

• Twelve porcine knees were tested using a robotic system in four states: intact, deficient, anatomic PL augmentation, and non-anatomic PL augmentation.
• Measurements included anterior tibial translation (ATT), internal rotation (IR), external rotation (ER), and in situ tissue force.
• Testing was performed under simulated anterior tibial load and rotational torques at various knee flexion angles.

Main Results:

• Both anatomic and non-anatomic PL augmentation restored knee laxity (ATT, IR, ER) to intact levels across all flexion angles.
• Both techniques generally restored ACL in situ tissue force, with minor exceptions at 60° flexion.
• No significant differences in laxity or graft function were observed between anatomic and non-anatomic PL augmentation groups.

Conclusions:

• Anatomic and non-anatomic PL bundle augmentation demonstrated comparable biomechanical outcomes in the porcine knee model.
• These findings suggest that precise graft placement may not be critical for restoring knee stability and function after PL augmentation.
• Further clinical studies are warranted to validate these biomechanical findings in human patients.