Tortuosity Angle of a Calcaneofibular Ligament on Magnetic Resonance Imaging & Stress Radiography

Category: Ankle; Sports Introduction/Purpose: A lateral ankle sprain is one of the most common musculoskeletal injuries for both athletes and non- athletes, causing chronic ankle instability. Talar tilt angle on a radiograph used for diagnosis of chronic ankle instability(CAI), however, there were no reports of instability of calcaneofibular ligament(CFL) itself through an MRI. This study aimed to determine whether measuring tortuosity angles of CFL through oblique coronal imaging of MRI in CAI. We compared CFL’s tortuosity angle with the talar tilt angle, Cumberland ankle instability tool(CAIT), and ankle strength in patients without a history of ankle sprain or not. Methods: From March 2020 to May 2022, Of the total 120 cases, the CAI group (82 patients) took CFL’s tortuosity angle in MRI and talar tilt angle inradiograph. The control group (38 patients) included those without an ankle sprain who visited this hospital due to an Achilles tendon rupture. In the control group, the talar tilt angle could not be achieved due to pain. Results: CFL’s tortuosity angle in MRI showed a significant difference of 76.5 ± 18.3º in the CAI group and 31.9 ± 5.4º in the control group(P < 0.001). The diagnostic cutoff value for CAI was more than 40º of the tortuosity angle. According to the measure of the isokinetic machine(Biodex), the CAI group shows a 22.8% deficit of the eversion strength. The tortuosity angle, talar tilt angle, and manual stress test show significantly different between both groups. However, CAIT and strength defect showed no significant results between both groups. Conclusion: CFL’s tortuosity angle through oblique coronary imaging of MRI, it’s average value was 31º degrees, and we can diagnose as CAI if CFL’s tortuosity angle is more than 40º.