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Comparative Analysis of Subtalar Ligaments Between Patients With Talocalcaneal Coalition and Control Subjects Using 3-Dimensional Magnetic Resonance Imaging

Purpose The purpose of this study was to find the differences in the subtalar ligaments between patients with talocalcaneal (TC) coalition and control subjects using 3-dimensional isotropic magnetic resonance imaging. Methods Magnetic resonance imaging of 27 ankles with TC coalition and 27 age- and sex-matched controls were retrospectively reviewed. Absence of cervical ligament, anterior capsular ligament (ACL), interosseous TC ligament (ITCL), and partial or complete absence of 3 roots of the inferior extensor retinaculum was analyzed. Thickness and width of ACL and ITCL were measured when possible. Results Absence of ACL and ITCL was significantly more frequent in TC coalition patients than in controls (59.2% vs 7.4%, P < 0.0001; 44.4% vs 7.4%, P = 0.004). Absence of cervical ligament and 3 roots of the inferior extensor retinaculum did not differ between the 2 groups. Thickness and width of ACL were significantly smaller in TC coalition patients than in control subjects (0.81 ± 0.23 vs 1.27 ± 0.41 mm, P < 0.0001; 5.26 ± 1.17 vs 7.07 ± 1.46 mm, P = 0.001). Thickness and width of ITCL did not differ between the 2 groups. In the TC coalition group, the absence of ACL and ITCL did not differ according to coalition type, patient demographics, and magnetic resonance imaging units. Conclusions Anterior capsular ligament and ITCL are frequently absent in TC coalition patients. Even when present, the ACL is attenuated in TC coalition patients compared with controls.