Distribution and Treatment Patterns of Symptomatic Tarsal Coalition in Japan: A Multicenter Retrospective Study.

BACKGROUND: Tarsal coalition is the congenital fusion of 2 or more tarsal bones, which can cause pain, restricted motion. Although calcaneonavicular (CN) coalitions have traditionally been reported to be the most common type of tarsal coalition in Western populations, recent East Asian studies have suggested the predominance of talocalcaneal (TC) and naviculocuneiform (NC) coalitions. We hypothesized that TC and NC coalitions are more prevalent than CN coalitions in symptomatic Japanese patients. METHODS: This multicenter retrospective study included patients diagnosed with symptomatic tarsal coalition at 4 specialized foot and ankle centers between 1997 and 2025. Demographic data, laterality, coalition type, and treatment modalities were analyzed. Coalitions were categorized as TC, NC, CN, cubonavicular, or cuneometatarsal. Treatments were classified as conservative management, coalition resection, or arthrodesis. RESULTS: A total of 127 coalitions were identified. TC coalitions were the most common type (56.7%), followed by NC (22.8%) and CN (16.5%) coalitions. Other coalitions, namely, cubonavicular (3.1%) and cuneometatarsal (0.8%), were less frequent. Among the TC coalitions, posterior facet involvement was the most frequent (73.6%), followed by combined middle-posterior involvement (22.2%), whereas isolated middle facet and panfacetal coalitions were rare. Bilateral involvement was observed in 18.9% of the patients. Conservative treatment was successful in 33.1% of the cases, whereas surgical treatment was performed in 66.9%, including coalition resection in 60.6%, and arthrodesis in 6.3%. CONCLUSION: In this symptomatic Japanese cohort, TC coalition was the most common type, followed by a relatively high proportion of NC and CN coalitions. Posterior facet involvement predominates among TC coalitions, whereas previous studies have reported a higher prevalence of middle facet involvement. Coalition resection was the most frequently performed surgical procedure in this cohort, whereas arthrodesis is rarely required. These findings highlight the importance of a computed tomography-based diagnosis for accurate characterization of coalition morphology in symptomatic tarsal coalitions. LEVEL OF EVIDENCE: Level IV, retrospective descriptive study.