Using navigation to measure rotation kinematics during ACL reconstruction.

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Biomedical Engineering

Background:

• Single-bundle anterior cruciate ligament (ACL) reconstruction often fails to fully restore normal knee rotational kinematics.
• Previous cadaveric studies suggest anatomical double-bundle reconstruction may offer superior kinematic restoration compared to single-bundle techniques.
• Objective clinical tools for assessing knee rotational laxity remain limited.

Purpose of the Study:

• To evaluate the utility of a computer-assisted navigation system for objectively measuring tibiofemoral rotational kinematics.
• To compare the rotational laxity of intact, ACL-deficient, and reconstructed knees (single-bundle and sequential double-bundle).

Main Methods:

• Utilized an optical computer-assisted navigation system to quantify tibiofemoral motion in four fresh cadaveric knees.
• Performed standard clinical laxity tests (anterior drawer, Lachman, pivot shift) on intact, ACL-excised, and sequentially reconstructed knees (anteromedial and posterolateral bundles).
• Measured tibial axial rotation and anteroposterior translation during the pivot shift test.

Main Results:

• ACL-deficient knees exhibited significant tibial rotation (27°) and translation (11 mm) during the pivot shift test.
• Anteromedial bundle reconstruction reduced rotation to 18° and translation to 7 mm.
• Sequential reconstruction of both anteromedial and posterolateral bundles further reduced rotation to 14°.

Conclusions:

• Computer-assisted navigation offers a practical and objective method for assessing the pivot shift test in clinical settings.
• This technology can differentiate the kinematic control provided by single-bundle versus two-bundle ACL reconstructions.
• Objective kinematic assessment may guide surgical decision-making for optimizing ACL reconstruction outcomes.