MRI Assessment of the Accessory Anterolateral Talar Facet in Pediatric Patients: Morphometric Features and Associated Subtalar Pathologies.

Abstract

Objective: To assess the frequency and morphometric characteristics of AALTF on pediatric ankle MRI, its associations with the Gissane angle and subtalar abnormalities, and the incremental value of zero-echo-time (ZTE) imaging for detecting tarsal coalitions.

Materials and methods: We retrospectively reviewed ankle MRI examinations of patients aged 0-18 years performed between September 2022 and January 2026. We randomly selected one ankle from each patient with bilateral examinations. Two pediatric radiologists independently assessed AALTF. For comparative analyses, 129 AALTF-negative controls were selected by simple random sampling from 712 AALTF-negative examinations. We performed age-stratified comparisons and age- and sex-adjusted multivariable regression analysis of the Gissane angle.

Results: Among 841 patients, 129 (15.3%) had AALTF. Mean facet length was 6.36 ± 2.20 mm, and cartilage coverage was present in 62.0%. The Gissane angle was lower in patients with AALTF than in controls (109.66° ± 6.74° vs. 117.43° ± 8.21°; p < 0.001). This association remained significant after adjustment for age and sex (B =  - 8.02; 95% CI, - 9.88 to - 6.16; p < 0.001). ROC analysis yielded an AUC of 0.764 and an optimal cutoff of 112.5° (sensitivity, 68.2%; specificity, 70.5%). Bone marrow edema, subtalar degeneration, tarsal coalition, and joint effusion were more frequent in patients with AALTF. Bone marrow edema and joint effusion remained more frequent in both age strata. Conventional MRI detected all coalitions, and ZTE detected no additional lesions. Interobserver agreement and measurement reliability were excellent.

Conclusion: AALTF is relatively common on pediatric ankle MRI and is independently associated with a lower Gissane angle and several concomitant abnormalities. A Gissane angle ≤ 112.5° may prompt closer evaluation for AALTF.