Passive Laxity With Functional Stability Reveals Potential Bilateral Dynamic Compensatory Mechanisms in Patients...

Area of Science:

• Orthopedics
• Biomechanics
• Sports Medicine

Background:

• Knee stability relies on passive structures (ligaments, menisci) and active neuromuscular control.
• Assessing long-term passive tibiofemoral alignment and dynamic constraint after ACL reconstruction is crucial.

Purpose of the Study:

• To investigate the relationship between passive alignment and dynamic constraint in patients with ACL reconstruction (ACLR) over a decade post-surgery.
• To compare tibiofemoral alignment and dynamic knee function between ACLR patients and uninjured controls.

Main Methods:

• Employed computed tomography (CT) for 3D passive tibiofemoral alignment assessment.
• Utilized biplane videoradiography for dynamic 3D knee kinematics during a single-leg hop landing task.
• Measured side-to-side differences in knee kinematics to quantify dynamic constraint.

Main Results:

• ACLR patients exhibited significantly more anterior passive tibial positioning (7.5 mm) compared to controls and their contralateral limb (3.1 mm).
• Peak dynamic anterior tibial position during hopping was not significantly different between surgical and contralateral limbs in ACLR patients.
• However, ACLR surgical limbs (10.3 mm) and contralateral limbs (7.5 mm) showed greater anterior tibial positioning compared to controls when analyzed as a function of flexion angle.

Conclusions:

• Passive knee alignment remains significantly altered long after ACL reconstruction.
• While dynamic constraint is mostly recovered, a bilateral tendency for increased anterior tibial translation persists.
• Long-term ACLR outcomes suggest potential graft function deterioration compensated by neuromuscular adaptations.