CavoVarus Feet Reconstruction

Courtesy: Anny Hsu, MD, Assistant Professor, New York Medical College, New York, USA

 

Overview of Cavovarus Foot Deformity

Cavovarus deformity is defined by:

• Increased Meary’s angle

• Dorsal apex angulation

• Plantarflexed first ray

• Varus hindfoot alignment

Although an elevated Meary’s angle can be seen in up to 24% of the population, clinically significant cavovarus deformity results in pain, instability, and progressive secondary pathology.

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Etiology

Neurogenic Causes (Most Common)

• Charcot–Marie–Tooth disease

• Stroke

• Poliomyelitis

• Cerebral palsy

• Friedreich’s ataxia

• Spinal cord lesions

• Spinal muscular atrophy

Congenital Causes

• Residual or relapsed clubfoot

• Arthrogryposis

Acquired / Post-Traumatic Causes

• Burns

• Compartment syndrome

• Crush injuries

• Talar fracture malunion

• Peroneal nerve injury

• Peroneal tendon insufficiency

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Clinical Presentation

Patients often adapt to the deformity and present with secondary complaints, including:

• Lateral ankle instability (“ankle giving way”)

• Peroneal tendinopathy

• Sesamoiditis

• Metatarsalgia

• Fifth metatarsal stress fractures

• Plantar calluses and ulceration

• Progressive medial compartment knee arthritis (long-term)

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Biomechanics of Cavovarus Foot

• Hyperactive peroneus longus plantarflexes the first ray

• Loss of normal tripod weight bearing

• Subtalar joint is pulled into varus, becoming rigid over time

• Hindfoot varus becomes fixed and progressive

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Clinical Examination

Key Findings

• Peek-a-boo heel sign (visible heel varus from the front)

• Apparent neutral heel may mask subtalar eversion compensation

• Weak eversion strength

• Clawing of toes in severe or neurogenic cases

Coleman Block Test

A critical test to differentiate:

• Forefoot-driven flexible hindfoot varus

• True fixed hindfoot varus

This test directly influences surgical decision-making.

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Radiographic Evaluation

Hindfoot

• Increased calcaneal pitch (lateral view)

• Decreased talar–calcaneal angle (AP view)

• Harris axial view to quantify hindfoot varus

Midfoot

• Elevated navicular height

• Increased medial–lateral forefoot imbalance

• Talonavicular joint subluxation is common

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Non-Operative Management

Initial management includes:

• Gastrocnemius stretching

• Custom orthotics:

  • Lateral hindfoot posting

  • Low medial arch

  • First-ray recess to accommodate plantarflexion

Flexible deformities may respond well; rigid deformities usually do not.

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Principles of Surgical Planning

Cavovarus correction is three-dimensional and complex. Key considerations include:

1. Flexibility of deformity (Coleman block test)

2. Presence of arthritis (CT scan if needed)

3. Equinus contracture (present in ~99%)

4. Neurologic etiology (risk of recurrence)

5. Associated ankle instability

6. Ankle alignment (standing ankle X-ray mandatory)

?? Failure to identify a neurologic cause may result in recurrence.

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Soft Tissue Procedures

Equinus Correction

• Gastrocnemius recession

• Percutaneous or open Achilles tendon lengthening

• Posterior capsular release (for severe stiffness)

Tendon Balancing

• Peroneus longus ? brevis transfer

• Posterior tibial tendon lengthening or transfer

• Jones procedure for clawed hallux

• Flexor tenotomies for severe claw toes

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Bony Procedures

Hindfoot

• Lateralizing calcaneal osteotomy (preferred)

• Dwyer closing wedge osteotomy (less favored in adults)

Forefoot

• First metatarsal dorsiflexion osteotomy

  • Maintain plantar hinge

  • Avoid shortening or rotational malalignment

Severe Deformities

• Lateral column shortening (selectively)

• Midfoot dorsal wedge osteotomy (Japas-type)

• Talar neck osteotomy for talar malunion

• Supramalleolar osteotomy for ankle varus

Arthrodesis

Indicated for rigid deformity with arthritis:

• Subtalar fusion

• Triple arthrodesis

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Operative Setup & Technical Pearls

• Supine positioning, thigh tourniquet

• Fluoroscopy essential

• Address Achilles pathology first

• Perform bony correction before tendon balancing

• Intraoperative simulated weight bearing helps avoid undercorrection

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Post-Operative Rehabilitation

• 2–3 weeks: splint

• 3 weeks: cast

• 6 weeks: boot, partial weight bearing

• 10–12 weeks: full weight bearing

• Gradual return to sport after additional therapy

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Case Discussions

Case 1: Post-Traumatic Cavovarus with Plantar Ulcer

• Percutaneous Achilles lengthening

• MIS calcaneal osteotomy

• First metatarsal dorsiflexion osteotomy

• Peroneus longus ? brevis transfer

• Lateral ligament repair

Outcome: Pain relief, ulcer resolution, restored function.

Case 2: Rigid Cavovarus with Post-Traumatic Arthritis

• Endoscopic gastrocnemius recession

• Hardware removal

• Triple arthrodesis

• First metatarsal dorsiflexion osteotomy

Outcome: Stable alignment, pain resolution.

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Key Take-Home Messages

• Cavovarus deformity requires systematic evaluation

• Always rule out neurologic causes

• Coleman block test is critical

• Address equinus and bony alignment first

• Tendon balancing fine-tunes correction

• Under-correction is more common than over-correction