Understanding the Different Types of Tarsal Coalitions

Understanding the Different Types of Tarsal Coalitions

High-Yield Executive Summary

• Tarsal coalition is an abnormal osseous, cartilaginous, or fibrous connection between two or more tarsal bones, most commonly involving the calcaneonavicular and talocalcaneal joints, leading to restricted hindfoot motion and pain.
• Clinical presentation typically occurs in adolescence with progressive flatfoot deformity, peroneal spasticity, and activity-related hindfoot pain.
• Imaging diagnosis relies on weight-bearing radiographs supplemented by CT for osseous coalitions and MRI for fibrous or cartilaginous types.
• Management hinges on symptom severity and coalition type; non-operative treatment is first-line, with surgery reserved for refractory cases or significant deformity.
• Surgical options include coalition resection with interposition grafting for isolated coalitions and arthrodesis for extensive or degenerative cases, with approach tailored to coalition location and patient factors.

Clinical Fundamentals

Relevant Anatomy and Biomechanics

The tarsal bones form a complex hindfoot and midfoot structure critical for foot flexibility and load transmission. The subtalar joint (talocalcaneal articulation) and calcaneonavicular joint allow inversion-eversion and accommodate uneven terrain. A coalition restricts these motions, altering biomechanics and increasing stress on adjacent joints.

• Calcaneonavicular coalition: Fusion between the anterior process of the calcaneus and the navicular bone, limiting subtalar and midtarsal joint motion.
• Talocalcaneal coalition: Fusion between the talus and calcaneus, often involving the middle facet, significantly restricting subtalar motion.
• Other coalitions: Less common, involving cuboid, cuneiforms, or naviculocuneiform joints.

Epidemiology

• Prevalence: Approximately 1–2% of the general population, often bilateral (50%–60%).
• Age of symptom onset: Typically adolescence (8–16 years), coinciding with ossification of coalition.
• Gender: Slight male predominance.
• Genetic predisposition: Familial clustering suggests autosomal dominant inheritance with variable penetrance.

Classification & Diagnosis

Classification Systems Dictating Management

Diagnostic Pearls and Pitfalls

• Radiographs: Weight-bearing AP, lateral, and oblique views are essential. The “C-sign” on lateral radiograph is pathognomonic for talocalcaneal coalition.
• CT scan: Gold standard for delineating osseous coalitions and preoperative planning.
• MRI: Best for detecting non-osseous (fibrous or cartilaginous) coalitions and associated bone marrow edema.
• Pitfall: Failure to obtain weight-bearing films can underestimate coalition extent and hindfoot alignment.
• Pitfall: Misinterpreting accessory ossicles or normal variants as coalitions.

The Decision-Making Algorithm

Why Specific Surgical Approaches or Implants?

• Coalition resection is preferred for isolated, well-defined coalitions without arthritis to restore motion.
• Interposition grafts (fat, muscle, or synthetic) prevent reossification post-resection.
• Arthrodesis (subtalar or triple fusion) is indicated for large osseous coalitions, failed resections, or degenerative joints to provide pain relief and stability.
• Minimally invasive techniques are emerging but require careful patient selection.

Surgical Mastery & Pearls

Step-by-Step Conceptual Overview of Calcaneonavicular Coalition Resection

1. Patient positioning: Supine with a bump under ipsilateral hip to facilitate lateral access.
2. Incision: Curvilinear over the sinus tarsi, avoiding sural nerve branches.
3. Exposure: Identify and protect the extensor digitorum brevis muscle.
4. Resection: Excise the coalition bar completely using osteotomes and curettes.
5. Interposition: Place a fat or muscle graft harvested from local tissue to prevent reossification.
6. Closure: Layered soft tissue closure with care to avoid hematoma.

Intraoperative Red Flags

• Incomplete resection leading to persistent symptoms.
• Injury to the peroneal tendons or sural nerve.
• Excessive bone removal causing instability.
• Failure to interpose graft material increasing recurrence risk.

Technical Tips

• Use intraoperative fluoroscopy to confirm complete coalition removal.
• Preserve as much normal joint cartilage as possible.
• For talocalcaneal coalitions, a medial approach with subtalar joint visualization is critical.
• Consider adjunctive procedures (e.g., gastrocnemius recession) for associated equinus contracture.

Evidence-Based Synthesis

Recent literature emphasizes the importance of early diagnosis and tailored surgical intervention. Multiple cohort studies demonstrate that coalition resection with interposition grafting yields excellent functional outcomes in calcaneonavicular coalitions, with success rates exceeding 80%. Conversely, talocalcaneal coalitions, especially osseous types, show higher failure rates with resection alone, often necessitating arthrodesis.

Randomized controlled trials are lacking, but retrospective analyses suggest that arthrodesis provides durable pain relief in advanced cases but at the cost of hindfoot motion. Emerging evidence supports the use of CT-based 3D planning to optimize resection margins and minimize recurrence.

Controversy remains regarding the timing of surgery in skeletally immature patients and the role of minimally invasive techniques, highlighting the need for individualized treatment plans.

Pro-Tip: Surgical Excellence in Tarsal Coalition Management

Mastery lies in meticulous preoperative planning with advanced imaging to define coalition morphology and extent. Intraoperatively, prioritize complete coalition excision and robust interposition to prevent recurrence. Anticipate and address associated deformities concurrently to optimize functional outcomes. Finally, maintain a low threshold for arthrodesis in cases with degenerative changes or failed prior surgery, balancing pain relief with preservation of foot biomechanics.

Last Updated on January 26, 2026 by OrthoNet AI