summary Tarsal Coalition is a common congenital condition caused by failure of embryonic segmentation leading to abnormal coalition 2 or more of the tarsal bones. The condition is usually asymptomatic, but may present with a flatfoot deformity or recurrent ankle sprains. Diagnosis is made with plain radiographs of the foot and ankle showing a coalition, most commonly a calcaneonavicular or talocalcaneous coalition. Treatment is usually a course of casting and NSAIDs for symptomatic patients. Surgical coalition resection or joint arthrodesis is indicated for patients with persistent symptoms who fail conservative management. Epidemiology Prevalence varies from 1%-2% Demographics age of onset calcaneonavicular usually 8-12 years old talocalcaneal usually 12-15 years old Anatomic location calcaneonavicular (most common) talocalcaneus Etiology Two types congenital most common acquired less common and caused by login to view 3 more bullets Pathophysiology embryology failure of mesenchymal segmentation leading to coalition between two or three tarsal bones login to view 1 more bullet pathoanatomy gait mechanics login to view 2 more bullets deformity login to view 4 more bullets pain generator theories login to view 4 more bullets Associated conditions nonsyndromic autosomal dominant syndromic fibular hemimelia carpal coalition FGFR-associated craniosynostosis (FGFR-1, FGFR-2, FGFR-3) Apert syndrome, Pfeiffer, Crouzon, Jackson-Weiss and Muenke Classification Anatomic classification calcaneonavicular between calcaneus and navicular bones (most common) talocalcaneal middle facet of talocalcaneal joint Pathoanatomic classification 3 types fibrous coalition (syndesmosis) cartilagenous coalition (synchondrosis) osseous coalition (synostosis) Presentation History history of prior recurrent ankle sprains Symptoms asymptomatic most coalitions are found incidentally 75% of people are asymptomatic pain location of pain login to view 2 more bullets pain worsened by activity login to view 1 more bullet calf pain login to view 1 more bullet Physical exam inspection hindfoot valgus forefoot abduction pes planus range of motion limited subtalar motion heel cord contractures arch of foot does not reconstitute upon toe-standing login to view 1 more bullet special tests reverse Coleman block test login to view 1 more bullet Imaging Radiographs recommended views required login to view 5 more bullets findings calcaneonavicular coalition login to view 2 more bullets talocalcaneal coalition login to view 7 more bullets CT scan Has been suggested as part of the preoperative workup to rule-out additional coalitions login to view 1 more bullet determine size, location and extent of coalition login to view 1 more bullet MRI may be helpful to visualize a fibrous or cartilaginous coalition STIR sequences help to differentiate inflammatory changes (e.g. tendinitis) in local structures Treatment Nonoperative observation, shoe inserts indications login to view 1 more bullet techniques login to view 1 more bullet outcomes login to view 1 more bullet immobilization with casting, analgesics indications login to view 1 more bullet techniques login to view 1 more bullet outcomes login to view 1 more bullet Operative coalition resection with interposition graft, +/- correction of associated foot deformity indications login to view 2 more bullets techniques login to view 10 more bullets outcomes login to view 5 more bullets subtalar arthrodesis indications login to view 2 more bullets technique login to view 2 more bullets triple arthrodesis (subtalar, calcaneocuboid, and talonavicular) indications login to view 2 more bullets technique login to view 1 more bullet Techniques Calcaneonavicular coalition resection approach lateral or sloppy lateral position anterolateral approach over coalition incision oblique incision just distal to subtalar joint between extensor tendons and peroneal tendons technique protect branches of superficial peroneal and sural nerves reflect fibrofatty tissues in sinus tarsi anterior and extensor digitorum brevis distally identify coalition between anterior process of calcaneus and navicular bones and confirm with fluorscopy excise bar with saw or osteotomes, which leaves defect ~1cm in size interpose fat, bone wax or portion of extensor digitorum brevis muscle into defect post-operative short-leg, non-weight bearing cast for 3-4 weeks Talocalcaneal coalition resection approach positioned supine medial approach to hindfoot incision horizontal or curved incision centered over sustentaculum tali between flexor digitorum longus and neurovascular bundle technique sustentaculum tali usually just plantar to the talocalcaneal coalition identify normal subtalar joint cartilage by dissecting out the anterior and posterior facets login to view 2 more bullets resect coalition with high speed-burr, ronguers and curettes invert and evert subtalar joint to demonstrate improvement in subtalar motion interpose fat, bone wax or portion of flexor hallucis longus tendon into defect post-operative short-leg non-weight bearing cast for three weeks Complications Incomplete resection Recurrence of the coalition Residual pain or stiffness due to malalignment or associated arthritis due to unrecognized 2nd coalition - this should be identified by a preoperative CT scan