Retrospective Review of MRIs of the Cervical, Spring, and Interosseous Talocalcaneal Ligaments in Progressive Collapsing Foot Deformity

Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: Progressive collapsing foot deformity (PCFD) is a complex condition characterized by progressive ligamentous and osseous changes in the hindfoot, midfoot, and forefoot. While osseous changes at the subtalar and transverse tarsal joints have been well-studied, ligamentous anatomy in PFCD is less understood. This study aims to evaluate the cervical ligament, interosseous (IO) talocalcaneal ligament, and the spring ligament in patients with PCFD versus controls using magnetic resonance imaging (MRI) analysis. Methods: A retrospective review was conducted at a single academic institution, analyzing MRI (1.5+ Tesla) and weight-bearing radiographs of 39 patients (23 with PCFD and 16 normal controls). MRIs were used to measure the coronal plane orientation of the interosseous talocalcaneal, cervical, and spring ligaments relative to the subtalar joint medial facet. Radiographic data was collected from weight-bearing x-rays, including anteroposterior (AP) talonavicular coverage percentage, AP talocalcaneal angle (Kite angle), lateral talar-first metatarsal angle (Meary Angle), talar declination angle, and calcaneal pitch. Two observers measured each radiographic and MRI angle. Statistical analysis included an independent student t-test and intraclass correlation coefficient (ICC) to assess agreement and inter- and intra-observer reliability between each observer. Results: PCFD patients demonstrated significantly more horizontal ligament orientations than controls, with reduced cervical (25.5° vs. 45°, p < 0.001), spring (11.5° vs. 23.1°, p < 0.001), and interosseous talocalcaneal ligament angles (39.5° vs. 49.0°, p = 0.005). Radiographically, PCFD patients had decreased talonavicular coverage (64.5% vs. 80.9%, p < 0.001), increased Meary angle (22.2° vs. -2.3°, p < 0.001), increased talar declination (37.0° vs. 26.0°, p < 0.001), increased Kite Angle (20.7° vs 17.2°, p < 0.079) and decreased calcaneal pitch (15.5° vs. 24.6°, p < 0.001). Inter- and intra-observer reliability was excellent, with ICC values exceeding 0.94 for all measurements except the interosseous talocalcaneal ligament angle (ICC = 0.83). Conclusion: Patients with progressive collapsing foot deformity (PCFD) experience significantly more horizontal orientation of the cervical, spring, and interosseous talocalcaneal ligaments compared to controls in the non-weightbearing state. These findings may aid future research into the potential reconstruction of these ligaments to prevent progression or restore anatomy in patients with PCFD.