3D-MRI Based Morphometrics of Subtalar Ligaments: Insights for the Assessment of Ankle Sprains.
BACKGROUND Subtalar ligament injuries occur in 10-25% of lateral ankle sprains (LAS) but remain underdiagnosed, partly because their radiological anatomy is insufficiently defined. PURPOSE This anatomo-radiological study aimed to systematically characterize the MRI appearance and anatomical morphology of the principal subtalar ligaments. STUDY DESIGN Descriptive, single-center anatomo-radiological reference study (Level IV). METHODS Seventeen patients underwent 3-Tesla 3D-MRI of the contralateral asymptomatic ankle after lateral ankle ligament repair. The inferior extensor retinaculum (IER), cervical ligament (CL), interosseous talocalcaneal ligament (ITCL), and calcaneofibular ligament (CFL) were evaluated on multiplanar reconstructions aligned with each ligament's axis. Length, width, and thickness were measured in all cases. RESULTS The mean age of the cohort was 35 ± 12.5 years; 7 women and 10 men were included, with a mean BMI of 28 ± 6.3 kg/m². All four ligaments were consistently visualized on 3D-MRI. Length, width, and thickness measured 34.6 ± 6.8, 5.6 ± 1.2, and 1.7 ± 0.2 mm for the IER; 19.0 ± 1.6, 5.3 ± 1.3, and 1.8 ± 0.5 mm for the CL; 16.9 ± 2.4, 10.0 ± 1.4, and 2.4 ± 0.9 mm for the ITCL; and 25.2 ± 4.8, 5.8 ± 2.0, and 2.8 ± 0.6 mm for the CFL. CONCLUSIONS This study provides reference identification methods and normative measurement values for 3D-MRI assessment of the IER, CL, ITCL, and CFL. These data improve the understanding of subtalar ligament morphology and may aid in the diagnosis and treatment of subtalar ligament injuries. LEVEL OF EVIDENCE Level IV (descriptive study).