Effect of concomitant flatfoot on surgical outcomes following isolated talocalcaneal coalition resection in adult patients: a retrospective study

PURPOSE: A greater hindfoot valgus angle is potentially associated with worse outcomes after talocalcaneal coalition (TCC) resection. However, the impact of concomitant flatfoot on TCC resection outcomes remains controversial. The aim of this study was to discuss the effect of flatfoot on the outcomes of isolated TCC resection. METHODS: A retrospective analysis was conducted on patients who underwent isolated resection for symptomatic TCC between 2016 and 2024. Patients were divided into flatfoot (FF, n = 20) and non-flatfoot groups (NF, n = 25) based on the diagnostic criteria for radiographic flatfoot on preoperative weightbearing radiographs: Meary's angle (MA) > 4°, calcaneal pitch (CP) < 18°, talonavicular coverage angle (TNCA) > 7° and Kite's angle (KA) > 40°. Preoperative and postoperative visual analogue scale (VAS) scores and American Orthopaedic Foot & Ankle Society (AOFAS) scores were used to evaluate functional outcomes, whereas flatfoot-related angles (CP, MA, TNCA and KA) were measured to assess radiographic outcomes. RESULTS: Forty-four patients (45 feet) were included in this study. The mean age at the time of surgery was 26.7 ± 6.6 years. All cases included were non-osseous coalitions. Twenty feet were in the FF group, and 25 feet were in the NF group. All patients were followed up for 50.6 ± 18.0 months. At the final follow-up, the VAS score was 1.3 ± 0.8, and the AOFAS score was 83.9 ± 9.0 in the FF group. In the NF group, the VAS score was 1.5 ± 0.9, and the AOFAS ankle-hindfoot score was 83.3 ± 6.6. Both groups demonstrated statistically significant improvements in functional outcomes (VAS and AOFAS) compared to preoperative values (p < 0.05). No significant differences in the radiographic measurements of flatfoot were noted between the two groups at the final follow-up. CONCLUSION: Isolated resection is effective for treating symptomatic TCC. Concomitant mild flatfoot did not adversely affect outcomes, suggesting that resection is a viable option for TCC patients with combined flatfoot.