Tarsal Coalition Resection

Introduction

Tarsal coalition is a congenital anomaly consisting of aberrant osseous, fibrous, or cartilaginous bridging between the tarsal bones. The reported incidence of tarsal coalitions is 1% to 13%, with bilaterality in nearly 50%. Calcaneonavicular coalition was found to be the most common type (53%), followed by talocalcaneal coalition (37%), and together they account for 90% of all tarsal coalitions ( Figs. 36.1 and 36.2 ). Only 25% of tarsal coalitions are symptomatic, and they are typically reported between the ages of 8 and 16 years when the tarsal bones ossify. Patients with calcaneonavicular coalitions begin developing symptoms around the ages of 8 to 12 years, while talocalcaneal coalitions begin around age 12 to 16 years. Coexisting multiple tarsal coalitions in the same foot have also been reported. Though the true incidence is unclear, it is noted to occur in 3.8% to 20% of patients with tarsal coalition.

Fig. 36.1, (A) X-ray and (B) computed tomography scan of the foot showing nonosseous calcaneonavicular coalition.

Fig. 36.2, Lateral X-Ray of the Foot. This shows talocalcaneal coalition as indicated by the C-sign

Table 36.1

	Features	Management
1.	i) Talocalcaneal coalition involving <50% of the posterior subtalar facet, ii) Hindfoot valgus <16 degrees, and iii) No evidence of subtalar joint degeneration	– Talocalcaneal coalition resection
2.	i) Talocalcaneal coalition involving <50% of the posterior subtalar facet, ii) Hindfoot valgus >16 degrees, and iii) No evidence of subtalar joint degeneration	– Talocalcaneal coalition resection + – Foot realignment that includes lateral column lengthening (Evans/Mosca-type calcaneal osteotomy or a medial sliding calcaneal osteotomy) and medial cuneiform opening-wedge plantarflexion osteotomy (to correct residual forefoot supination deformity if present) ± – Tendoachilles and/or peroneus brevis lengthening (if there is evidence of contracture)
3.	i) Talocalcaneal coalition involving >50% of the posterior subtalar facet, ii) Hindfoot valgus >16 degrees, and iii) Evidence of subtalar joint degeneration	– Foot realignment procedure – Extra-articular subtalar arthrodesis if previously failed resection/reconstruction

Features

Management

i)
Talocalcaneal coalition involving <50% of the posterior subtalar facet,
ii)
Hindfoot valgus <16 degrees, and
iii)
No evidence of subtalar joint degeneration

–
Talocalcaneal coalition resection

i)
Talocalcaneal coalition involving <50% of the posterior subtalar facet,
ii)
Hindfoot valgus >16 degrees, and
iii)
No evidence of subtalar joint degeneration

–
Talocalcaneal coalition resection +
–
Foot realignment that includes lateral column lengthening (Evans/Mosca-type calcaneal osteotomy or a medial sliding calcaneal osteotomy) and medial cuneiform opening-wedge plantarflexion osteotomy (to correct residual forefoot supination deformity if present)

–
Tendoachilles and/or peroneus brevis lengthening (if there is evidence of contracture)

i)
Talocalcaneal coalition involving >50% of the posterior subtalar facet,
ii)
Hindfoot valgus >16 degrees, and
iii)
Evidence of subtalar joint degeneration

–
Foot realignment procedure
–
Extra-articular subtalar arthrodesis if previously failed resection/reconstruction

Table 36.2

Preoperative Considerations
	Factor	Significance	Resolution/Outcome
1.	Age	Younger age group (skeletally immature)	Better prognosis
2.	Type of coalition	Nonossified or cartilaginous coalitions	Better prognosis
3.	Preoperative imaging (computed tomography scan)	i) Accurate identification of coalition and identification of multiple coalitions in the same foot ii) Extent of involvement of the subtalar joint, the amount of hindfoot valgus, and presence of degenerative changes in the Chopart joint	i) Appropriate and adequate resection of tarsal coalition(s) ii) Determination of treatment approach in terms of resection +/- foot realignment procedures versus arthrodesis
Intraoperative Considerations
	Factor	Significance	Resolution/Outcome
1.	Presence of multiple coalitions	Requires appropriate resection	Successful outcome if appropriately addressed
2.	Forefoot, midfoot, and hindfoot deformities	i) Incomplete reduction of talonavicular joint indicates forefoot malalignment ii) Extent of involvement of the subtalar joint, the amount of hindfoot valgus, and presence of degenerative changes in the Chopart joint	i) Peroneus brevis lengthening, abductor digiti minimi lengthening, plication of the plantar-medial talonavicular capsule, plication of the posterior tibialis tendon, release of the dorsolateral talonavicular capsule, and closing-wedge osteotomy of the medial cuneiform ii) Determination of treatment approach in terms of resection +/- foot realignment procedures versus arthrodesis
3.	Inadequate or excessive resection	Inadequate resection leads to persistence of bridging coalition, and hence patient symptoms. Excessive resection causes iatrogenic injuries to the talar head or navicular, leading to abnormal joint mechanics and early degenerative changes	Use of appropriately sized osteotomes and understanding the proper anatomy of the coalition Use of three-dimensionally navigated subtalar coalition excision technique
4.	Resection of calcaneonavicular (CN) coalition without interposition	Persistence of pain, recurrence, and development of secondary osteoarthritis of the Chopart joints	Use of an appropriate interposition material following CN coalition resection
5.	Resection of CN coalition with extensor digitorum brevis interposition	Results in bony prominence along the lateral border of the foot due to prominence of the calcaneocuboid joint, causing friction and difficulties with shoe wearing, as well as poor cosmesis	Use of fat or bone wax as interposition material
Postoperative Considerations
	Factor	Significance	Resolution/Outcome
1.	Wound infection	Delayed wound healing, persistent pain, scarring	Use of nonabsorbable sutures, which help with better wound closure and handling of swelling
2.	Persistent pain, stiffness, and discomfort	Inadequate resection and/or failure to address associated foot deformities	Adequate preoperative imaging, identification of coalition(s) and foot deformities, and appropriate preoperative planning. Use of three-dimensionally navigated subtalar coalition excision technique
3.	Injury to the surrounding tendons (tibialis posterior, flexor, extensor, and peroneal tensons) and neurovascular structures (posterior tibial neurovascular bundle, superficial peroneal nerve, and sural nerve)	Weakness, discomfort, and tingling or numbness of the foot	Understanding the proper anatomy of the coalition and the surrounding structures of the foot
4.	Recurrence of tarsal coalition	Inadequate resection	Adequate preoperative imaging, identification of coalition(s), and appropriate preoperative planning Use of three-dimensionally navigated subtalar coalition excision technique
5.	Degenerative arthritis	Abnormal joint mechanics	Arthrodesis

Symptoms of tarsal coalition include pain, spasm, limited subtalar motion, out-toeing deformities, and recurrent ankle injuries, resulting in a rigid, painful foot. Conservative management includes immobilization, activity modification, use of shoe inserts or orthotics to elevate the medial arch, physical therapy, and nonsteroidal anti-inflammatory medications.

Operative Management and Preoperative Considerations

Surgical management of tarsal coalition is indicated when a trial of nonoperative treatment proves ineffective. The goal of surgery includes pain relief and restoration of midfoot and hindfoot motion. The most common operative treatment of tarsal coalition includes resection of the coalition with or without interposition graft with muscle, fat, or bone wax. However, the presence of multiple coalitions in the same foot and associated hindfoot, midfoot, and forefoot deformities should be addressed. Other available surgical options include calcaneal-lengthening osteotomy and subtalar or triple arthrodesis.

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