Four-dimensional CT as a valid approach to detect and quantify kinematic changes after selective ankle ligament...

Area of Science:

• Biomechanics
• Medical Imaging
• Orthopedic Surgery

Background:

• Ankle ligament injuries are common and can lead to chronic instability.
• Accurate assessment of ankle kinematics is crucial for effective treatment planning.
• Current diagnostic methods may not fully capture dynamic joint instability.

Purpose of the Study:

• To evaluate the capability of 4DCT in detecting kinematic alterations in the talocrural joint.
• To assess changes induced by sequential sectioning of lateral collateral ligaments.
• To determine the feasibility of using 4DCT for analyzing ankle joint motion under simulated injury conditions.

Main Methods:

• A fresh frozen cadaver leg underwent cyclic inversion movements using a custom device.
• Four scenarios were scanned using a 256-slice CT scanner: intact ligaments, and sequential sectioning of ATFL, CFL, and PTFL.
• Off-line image processing involved semi-automatic segmentation and rigid bone registration to calculate motion parameters.

Main Results:

• Progressive increases in cranio-caudal displacement (up to 3.9 mm) and flexion (up to 10°) were observed with ligament damage.
• Significant changes in the orientation (up to 20.6°) and position (up to 4.1 mm) of the axis of rotation were documented.
• The estimated effective radiation dose was minimal (0.005 mSv).

Conclusions:

• 4DCT can effectively detect kinematic changes in the ankle joint resulting from lateral collateral ligament compromise.
• The minimal radiation exposure makes 4DCT a promising tool for evaluating ankle instability.
• Further in vitro and in vivo studies are recommended to validate these findings for clinical application.