Talocalcaneal Coalition Resection with Local Fat Grafting and Flatfoot Reconstruction.

Background: Talocalcaneal (TC) coalitions typically present in the pediatric population with medial hindfoot and/or ankle pain and absent subtalar range of motion. Coalition resection with fat interposition is well described for isolated tarsal coalitions^1,2; however, patients with concomitant rigid flatfoot may benefit from additional reconstructive procedures. To address this, we employ the surgical technique of TC resection with local fat grafting and flatfoot reconstruction.

Description: This procedure is described in 3 steps: (1) gastrocnemius recession and fat harvesting, (2) TC coalition resection with local fat interposition, and (3) peroneus brevis Z-lengthening and calcaneal lateral column lengthening osteotomy with allograft. A 3 to 4-cm posteromedial longitudinal incision is made at the distal extent of the medial head of the gastrocnemius muscle. The gastrocnemius tendon is identified, dissected free of surrounding tissue, and transected. Superficial fat is then harvested from this incision before wound closure. A 7-cm incision is made from the posterior aspect of the medial malleolus to the talonavicular joint. The neurovascular bundle and flexor tendons are dissected carefully from the surrounding tissue as a group and protected while the coalition is completely resected, and bone wax and the local fat are utilized at the resection site to prevent regrowth of the coalition. An approximately 7-cm incision is then made laterally and obliquely following the Langer lines and centered over the lateral calcaneus. The peroneal tendons are released from their sheaths, and the peroneus brevis is Z-lengthened. A calcaneal osteotomy is performed about 1.5 cm proximal to the calcaneocuboid joint and angled to avoid the anterior and middle subtalar facet joints. Two Kirschner wires are inserted retrograde across the calcaneocuboid joint, and the calcaneal osteotomy is opened. A trapezoid-shaped allograft bone wedge is impacted, and the Kirschner wires are advanced across into the calcaneus. The lengthened peroneus brevis tendon is repaired, and the wound is closed in a layered fashion.

Alternatives: First-line treatment is nonoperative with orthotics and immobilization. Surgical options include coalition resection with or without calcaneal lengthening osteotomy, arthrodesis, or arthroereisis. Following coalition resection, various grafts can be utilized, including fat autografts, bone wax, or split flexor hallucis longus tendon^3-6.

Rationale: This procedure addresses TC coalition with concomitant rigid flatfoot. Resection alone may increase subtalar motion but does not correct a flatfoot deformity. Historically, surgeons performed arthrodesis or arthroereisis, but these are rarely performed in young patients. In patients with coalitions involving >50% of the posterior facet or preexisting degenerative changes, arthrodesis may be indicated⁷.

Expected outcomes: Patients can expect improvement in pain and function^8-11. Previous investigators reported improved patient satisfaction, improved range of motion, clinical and radiographic hindfoot correction, and an improved American Orthopaedic Foot & Ankle Society hindfoot score at the time of final follow-up^8,9.

Important tips: Carefully free the neurovascular bundle from the surrounding soft tissue so that it can be carefully retracted away from the area of coalition resection.Utilize the interval between the posterior tibialis and flexor digitorum longus tendons to approach the coalition.Expose the medial wall of the coalition and perform a careful resection that avoids inadvertently diverging into the body of the talus or calcaneus.Place a smooth lamina spreader into the resected area and gently open the subtalar joint to confirm complete coalition resection.Place 2 retrograde wires across the calcaneocuboid joint before performing the osteotomy. Without this step, up to 50% of cases experience calcaneocuboid subluxation and/or rotation after the lateral column lengthening¹².To determine the size of the allograft, place a lamina spreader into the osteotomy site to measure the width.If present, rigid supination of the forefoot must be corrected with a medial cuneiform plantar-based closing osteotomy.

Acronyms and abbreviations: AOFAS = American Orthopaedic Foot & Ankle SocietyFADI = Foot and Ankle Disability IndexMRI = magnetic resonance imagingCT = computed tomographyOR = operating roomK-wire = Kirschner wire.