Talocalcaneal Tarsal Coalition: A Novel Deltoid-Preserving, Mini-Open Procedure.

Tarsal coalition is an abnormal union of tarsal bones leading to rigid hindfoot valgus and altered biomechanics. Most symptomatic cases involve the talocalcaneal joint. Standard surgical options include resection or arthrodesis, both with limitations. We present a novel deltoid-preserving, mini-open approach designed to restore hindfoot motion while maintaining stability. A 22-year-old woman presented with severe unilateral hindfoot pain, instability, and valgus deformity. Imaging confirmed a type 3 shingled talocalcaneal coalition involving the sustentaculum tali. Nonoperative options failed, and the patient opted for surgery. A lateral mini-open approach through the sinus tarsi was used to osteotomise the coalition while preserving the superficial deltoid. A small medial approach was used to visualise the sustentaculum tali and protect the medial neurovascular structures. The sustentaculum tali fragment was secured to the calcaneum with a partially threaded screw. Postoperative rehabilitation emphasised subtalar mobility and tibialis posterior strengthening. At 17 weeks, the patient achieved pain-free gait, restoration of the medial arch, symmetrical subtalar motion, and a Manchester-Oxford Foot Questionnaire (MOXFQ) score of 0/64. Conventional talocalcaneal coalition resections often sacrifice the deltoid ligament and may fail to restore subtalar biomechanics. Arthrodesis relieves pain but increases adjacent joint degeneration risk. Our technique preserves key ligamentous stabilisers, maintains anatomical landmarks, and restores subtalar motion. Literature suggests that long-term issues after standard resections include persistent flatfoot and abnormal mechanics, highlighting the potential benefit of this approach. This novel deltoid-preserving, mini-open procedure may provide adult patients with an alternative to arthrodesis or traditional resection, offering pain relief, preservation of hindfoot motion, and improved biomechanics.