Chopart Injuries

Definition: Chopart joint (Midtarsal joint) injuries involve the Talonavicular (TN) and/or Calcaneocuboid (CC) joints. The Chopart joint is the boundary between the hindfoot and midfoot and is critical for foot flexibility.

Historical Note: Named after François Chopart (1743-1795), a French surgeon who described amputation through this joint.

Epidemiology:

• Rare: Less common than Lisfranc injuries.
• Mechanism: High-energy (MVA, motorcycle, fall from height). Occasionally low-energy (twisting).
• Pattern: Often associated with other foot injuries.

Anatomy:

• Talonavicular Joint: Ball-and-socket joint. Key for inversion/eversion. Keystone of medial longitudinal arch.
• Calcaneocuboid Joint: Saddle-shaped. Less mobile. Part of lateral column.
• Ligaments: Spring Ligament (plantar calcaneonavicular), Bifurcate ligament (calcaneonavicular + calcaneocuboid), Interosseous ligaments.

Biomechanics:

• Transverse Tarsal Joint: TN + CC together. Allows midfoot motion.
• Foot Flexibility: When subtalar joint is everted, TN and CC axes are parallel, allowing flexibility. When inverted, axes diverge, creating rigidity.

Injury Mechanism:

• Forced Abduction/Adduction: Forefoot forced laterally or medially on fixed hindfoot.
• Axial Load: Direct force through midfoot.
• Nutcracker: Forced plantarflexion compresses cuboid between 4th/5th metatarsals and calcaneus.

History:

• Mechanism: MVA? Fall? Twisting?
• Pain Location: Dorsal midfoot. Worse with walking.

Physical Examination:

• Swelling: Significant midfoot swelling.
• Tenderness: Over TN and/or CC joints.
• Deformity: May have visible abduction or adduction deformity.
• ROM: Painful midfoot motion.
• Neurovascular: Check pulses and sensation.
• Compartments: Monitor for foot compartment syndrome (especially with crush/high-energy).

Imaging:

1. X-ray (Foot - AP, Oblique, Lateral): Look for joint widening, subluxation, fractures.
2. Weight-Bearing X-rays: If patient can tolerate. Better for subtle instability.
3. CT Scan: Essential for surgical planning. Assess comminution, joint congruity.
4. MRI: Rarely needed acutely. For ligamentous assessment if occult injury.

Key Findings:

• TN Gap: Widening or incongruity of Talonavicular joint.
• CC Subluxation: Malalignment of Calcaneocuboid joint.
• Cuboid Compression: Loss of cuboid height (Nutcracker).
• Lateral Column Shortening: Compare to contralateral.

• NWB: 6-12 weeks (depending on fixation stability and healing).
• Cast/Boot: Initially NWB cast, then transition to boot.
• ROM: Gentle ROM when fixation secure.
• Weight-Bearing: Progress PWB to FWB at 8-12 weeks.
• Physiotherapy: After healing. Gait training. Strengthening.

• Good Reduction: Better long-term outcomes.
• Post-Traumatic Arthrosis: Common even with anatomic reduction. May need fusion.
• Lateral Column Length: Critical. Shortening leads to painful abductus.

Global epidemiology

• Chopart injuries are rare, accounting for roughly 0.2 percent of all dislocations; midfoot fracture-dislocations are around five to ten times less common than Lisfranc injuries.
• Most series report a male predominance with a peak in young to middle-aged adults; high-energy mechanisms (road traffic, fall from height, crush) dominate, though a low-energy "twisting" subset exists in athletes.
• Up to a quarter present as combined Chopart-Lisfranc patterns, which carry the worst functional scores.

Side-by-side guidance

Registry and evidence notes

• No dedicated national registry tracks Chopart injuries (they are not implant-arthroplasty procedures); the evidence base is single-centre series and small cohorts, so guidance is consensus- and principle-driven rather than registry-derived.

High- vs limited-resource practice variation

• Well-resourced settings: routine CT, dedicated foot-and-ankle plating systems, cuboid-specific plates, and staged soft-tissue management.
• Limited-resource settings: reliance on plain radiographs and intra-operative fluoroscopy, K-wire and external-fixator constructs to hold column length, and a lower threshold for primary fusion when implants or follow-up are constrained.

• Primary fusion vs ORIF: For severely comminuted, non-reconstructable Chopart joints (especially the talonavicular keystone), the threshold for primary arthrodesis versus attempted reconstruction is debated; no randomised data exist.
• Spanning (bridge) plate vs internal fixation: Whether to span the midtarsal joint with a temporary bridge plate or external fixator versus rigid internal fixation, and when to remove spanning hardware, remains practice-dependent.
• Nutcracker graft choice: Structural autograft (iliac crest), allograft, and synthetic wedges are all used to restore lateral column length; comparative outcome data are lacking.
• Closed reduction in pure dislocations: Richter's data support closed reduction only when truly anatomic; the durability of this approach versus routine open confirmation is uncertain.
• Weight-bearing protocol: Optimal duration of non-weight-bearing (6 vs 12 weeks) and timing of hardware removal are not standardised.