August 09, 2017
7 min read

A 17-year-old athlete with recurrent ankle sprains

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A 17-year-old female high school soccer player with no medical comorbidities presented to clinic with right ankle pain that progressively worsened in the past 6 months. For 4 years, she had been diagnosed by her primary care physician and athletic trainers as having recurrent ankle sprains and ankle instability. The patient had been treated with multiple rounds of orthotics, ankle bracing, tall controlled ankle motion (CAM) boots, physical therapy and NSAID, with minimal benefit. The patient reported pain particularly with cutting maneuvers during soccer and when she tried to move her ankle side-to-side.

On physical exam, the patient was 5 feet 6 inches tall and weighed 110 pounds. She had diffuse pain and swelling along the medial aspect of her foot and ankle. She could not pinpoint the exact area of her discomfort, but she had worsening pain with subtalar joint passive range of motion (ROM). Standing alignment showed the patient had a rigid flatfoot deformity with mild forefoot abduction. She had full ankle ROM with mild pain over the anterior talofibular ligament, but there was no gross ankle ligamentous instability. Radiographs of the right ankle were obtained for further evaluation (Figure 1).

radiographs of the patient’s right ankle
Preoperative AP (a) and lateral (b) radiographs of the patient’s right ankle are shown.

Images: Hsu AR

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Talocalcaneal coalition of the middle facet of the subtalar joint

Radiographs demonstrated a large medial facet talocalcaneal coalition with a dysmorphic sustentaculum tali. A CT scan of the foot was obtained to better evaluate the size, extent and location of the coalition (Figure 2). A CT scan showed a partially fibrous and osseous talocalcaneal coalition measuring approximately one-third of the width of the total subtalar joint surface. Given the lack of benefit the patient had with previous nonoperative treatments, including immobilization and analgesics, the decision was made with input from the patient and her family to proceed with talocalcaneal coalition resection and interpositional grafting.

Surgical technique

partially fibrous and osseous talocalcaneal coalition
Coronal (a), sagittal (b) and axial (c) CT scans demonstrate a partially fibrous and osseous talocalcaneal coalition that measures about one-third the width of the total subtalar joint surface.

The patient was positioned supine without a bump under the hip, which permitted the leg to externally rotate and allowed for better access to the medial aspect of the hindfoot. A stack of blankets was placed under the foot to avoid X-ray interference with the contralateral leg. Fluoroscopy was used to mark out the subtalar joint and guide the planned incision (Figure 3). A longitudinal incision was made over the subtalar joint and dissection was carried down carefully to the coalition using the interval between the flexor digitorum longus (FDL) and flexor hallucis longus (FHL). The neurovascular bundle was carefully dissected and retracted dorsal along with the FDL tendon.

The osseous aspect of the coalition was found to completely cover the medial subtalar joint, which incorporated the sustentaculum tali and blocked any view of the FHL tendon. The anterior and posterior-most aspects of the subtalar joint were dissected to help localize the margins of the coalition. Two 0.062-inch K-wires were placed in the coalition in a converging fashion to determine the borders of the resection. Lateral and axial heel views were taken to ensure saw cuts would not violate the native subtalar joint cartilage or the FHL tendon. A saw was used in combination with straight osteotomes, a high-speed burr and a rongeur to entirely remove the coalition.

The coalition was resected until the subtalar joint was confirmed to have unimpeded inversion and eversion under direct visualization, as well as fluoroscopy (Figure 4). The FHL tendon was partially encased in bone, and was therefore debrided, which left a small bony groove for the tendon to prevent later tendon subluxation or dislocation. After the coalition excision was complete, bone wax was used to cover the exposed bony surfaces located away from the native cartilage. Then, a 2-cm x 4-cm piece of BioFix Amniotic Membrane Allograft (Integra LifeSciences Corp.) was placed in the wound around the FDL and FHL tendons, as well as near the neurovascular bundle to help prevent excessive scar formation and adhesions. The wound was closed in a layered fashion and the patient was made non-weight-bearing (NWB) for 2 weeks in a splint.

technique to remove the coalition
Fluoroscopy was used to identify the native subtalar joint (a), which guided the placement of the incision along the medial aspect of the foot (b). Dissection was carried down to the coalition using the interval between the FDL and FHL tendons and carefully retracting the neurovascular bundle dorsally (c). Lateral (d) and axial (e) heel views were taken after K-wire placement was done to confirm the appropriate alignment and orientation of the planned coalition resection. A saw and straight osteotomes were used to remove the coalition followed by a high-speed burr and rongeur (f). A large amount of bone and fibrous tissue was removed to complete excision of the coalition (g).

Sutures were removed at 2 weeks followed by initiation of progressive weight-bearing in a tall CAM boot for 3 weeks. At 5 weeks postoperatively, the patient was transitioned to a lace-up ankle brace worn in athletic shoes and to physical therapy that focused on foot and ankle ROM, stretching, and body-weight strengthening exercises. Two months after surgery, the patient could return to light jogging and running in a normal athletic shoe. The patient could return to competitive soccer at 3 months postoperatively without complications, pain, recurrence or other symptoms.



Tarsal coalitions are structural anomalies between tarsal bones that are often congenital and lead to development of a rigid flatfoot. Coalitions develop due to failure of mesenchymal segmentation, which causes a coalition to form that can be composed of fibrous tissue, cartilage or bone. Calcaneonavicular coalitions are the most common type of tarsal coalition and typically present between 8 years and 12 years of age and talocalcaneal coalitions generally present in patients between 12 years and 15 years old. Patients typically present with a history of recurrent ankle sprains in combination with flattening of the medial arch, hindfoot valgus and forefoot abduction with limited subtalar motion.

Pain can be located in the area of the sinus tarsi and inferior fibula (calcaneonavicular) or just distal to the medial malleolus (talocalcaneal). The pain is thought to be generated by microfracture that occurs at the coalition interface, chondral damage or degenerative changes, or increased stress on surrounding hindfoot joints. Physical exam should focus on standing alignment, ROM and arch reconstitution upon heel rise. Tarsal coalitions block subtalar motion and these will prevent the hindfoot movement from valgus to varus on heel rise.

confirming unrestricted inversion and eversion
Direct visualization and fluoroscopy were used to confirm there was unrestricted inversion and eversion of the subtalar joint after coalition excision (a). Axial heel view confirmed there was an appropriate resection (b). The FHL tendon was freed from the surrounding coalition and debrided, and a small bony groove was left intact to prevent later tendon subluxation (c). Exposed bone (d) was covered in bone wax to prevent coalition recurrence and the FDL and FHL tendons (e) along with the neurovascular bundle were covered in a layer of BioFix Amniotic Membrane Allograft (Integra LifeSciences Corp.) to prevent adhesions around the medial structures. The wound was closed in a layered fashion (f). The patient was NWB and wore a splint for 2 weeks.

Standing anteroposterior (AP), lateral, axial heel and 45° internal oblique views (calcaneonavicular coalition) should be obtained to evaluate for the location and size of the coalition. Calcaneonavicular coalitions classically show an “anteater” sign, which indicates an elongated anterior process of the calcaneus. Talocalcaneal coalitions can show radiographic signs, such as talar beaking, a C-shaped arch formed by the medial outline of the talar dome and sustentaculum tali, and an enlarged, dysmorphic sustentaculum. CT can be helpful to determine the exact size, location and extent of the coalition, as well as rule out any additional coalitions. MRI can be helpful to better visualize a fibrous or cartilaginous coalition.

Initial management should be conservative and depends on the duration and extent of symptoms. In cases of incidental coalition discovery, medial arch support orthotics can be used. In symptomatic cases, a period of about 4 weeks of immobilization in a walking cast or tall CAM boot, combined with NSAID use, can help reduce pain. For patients with continued pain and decreased function, coalition resection with interpositional graft is recommended if the coalition involves less than 50% of the total joint surface area. Commonly used grafts include extensor digitorum brevis (calcaneonavicular coalition), split FHL tendon, fat graft and bone wax. Associated hindfoot deformities can be corrected concurrently, but this depends on the patient’s symptoms and functional needs.


Multiple series have shown good outcomes with coalition resection and interpositional grafting, with more than 75% of patients having significant pain relief and improved long-term function. Complications include incomplete coalition resection, recurrence, iatrogenic damage to the surrounding tendons and neurovascular bundle, and residual pain and stiffness due to malalignment. Subtalar fusion is indicated if the talocalcaneal coalition is more than 50% of the joint surface and a triple arthrodesis is indicated in advanced coalitions that fail resection and have diffuse degenerative changes across the hindfoot that affect the talonavicular and calcaneocuboid articulations.

In the present case, the patient had been misdiagnosed as having isolated ankle sprains and ankle instability for 4 years. Especially in patients younger than 18 years old, it is important to perform a thorough history and physical exam and obtain initial radiographs in the presence of recurrent ankle sprains to evaluate for other potential etiologies, such as tarsal coalitions. It is uncommon for young, healthy adolescent patients with ankle sprains to fail nonoperative bracing and physical therapy and require lateral ankle ligament reconstruction. Therefore, it is critical for health care providers to be aware of the etiology, presentation, work-up and treatment options for patients with tarsal coalitions because an accurate and timely diagnosis can better lead to reduced pain and improved function.

A unique aspect of this case was the size of the middle-facet talocalcaneal coalition that impeded subtalar motion. The coalition partially encased the FHL tendon, which required tendon debridement and reconstruction of a groove for the FHL tendon to help prevent later subluxation. Bone wax was used to cover the exposed bony surfaces and amniotic membrane allograft was used to prevent excessive scarring and adhesions from forming around the FDL and FHL tendons and the neurovascular bundle. Early results have shown interposition of umbilical cord plus amniotic membrane tissue after tarsal coalition resection is a viable option with no adverse reactions. Further research is required to better define the exact role and mechanism of action of amniotic membrane allografts for prevention of scar tissue formation and coalition recurrence.

Disclosure: Hsu reports he is a paid consultant for Arthrex.