High-yield overview

Lateral closing wedge osteotomy to correct hindfoot-driven cavovarus | foot-ankle | intermediate

Surgical Imaging

Imaging Gallery

Two-panel clinical photos showing pes cavovarus deformity with equinovarus foot posture and bilateral comparison — Pes cavovarus deformity — the primary indication for Dwyer calcaneal osteotomy: Panel (a) shows severe unilateral cavovarus with the patient standing on the toes due to equinus contracture, with clearly visible hindfoot varus and high medial arch (cavus). Panel (b) shows bilateral lower limb comparison demonstrating the characteristic inverted heel (calcaneal varus) and high arch of the cavovarus foot — typically seen in Charcot-Marie-Tooth disease or post-poliomyelitis sequelae. Dwyer's lateral closing-wedge osteotomy corrects the calcaneal varus component of this deformity.Credit: Open-i NIH (PMC2762173) (CC BY PMC Open Access)

Two-panel pre and post-operative clinical comparison of leg alignment in cavovarus deformity — Lower limb alignment in cavovarus foot deformity: bilateral clinical comparison photographs showing lower limb and foot alignment. Panel (a) is a vintage black-and-white image showing a child with cavovarus foot posture, with the typical toe-walking pattern and visible hindfoot varus. Panel (b) is a colour photograph of an adolescent with bilateral lower limb deformity, demonstrating the spectrum of cavovarus presentation from mild to moderate severity that informs surgical decision-making including the need for Dwyer calcaneal osteotomy.Credit: Open-i NIH (PMC2762173) (CC BY PMC Open Access)

Critical Danger Structures

Danger 1: Sural Nerve

Sural nerve and its calcaneal branches. Location: Runs posterior to the peroneal tendons in the lateral hindfoot, coursing from posterior to the lateral malleolus obliquely towards the fifth metatarsal base. Protection: Identify immediately on entering the subcutaneous layer before deepening dissection; retract posteriorly. Injury causes painful lateral heel neuroma and numbness over the lateral foot dorsum.

Danger 2: Peroneal Tendons

Peroneus longus and peroneus brevis tendons. Location: Lie in their fibro-osseous groove behind the fibula but course anteriorly as the dissection approaches the calcaneal body; they are anterior to the sural nerve in the wound. Protection: Identify and retract anteriorly with a soft retractor after periosteal elevation; do not confuse them with the nerve. Damage or destabilisation causes peroneal subluxation and eversion weakness.

Danger 3: Calcaneal Branch of Tibial Nerve

Medial calcaneal branches of the posterior tibial nerve. Location: Emerge medially and inferiorly around the calcaneal tuberosity; the most inferior branches can be encountered at the inferior margin of a low calcaneal osteotomy. Protection: Keep the osteotomy within the lateral calcaneal body and avoid extending the cut too inferiorly. Injury contributes to heel hypoaesthesia.

Danger 4: Wound Dehiscence (Neuropathic Foot)

Skin and soft-tissue compromise. Location: Lateral hindfoot skin is thin and under tension in cavovarus deformity; especially fragile in CMT and other neuropathic conditions. Protection: Atraumatic dissection, no-touch technique on skin edges, layered watertight closure; plan for longer non-weight-bearing if skin quality poor. Dehiscence leads to exposed hardware and deep infection.

Danger 5: Malunion / Under-Correction

Residual hindfoot varus from inadequate wedge resection. Location: Technical failure at the osteotomy site. Prevention: Measure the wedge pre-operatively on a long-leg hindfoot alignment view; size the wedge so the heel corrects to neutral or very mild valgus on intraoperative fluoroscopy. Under-correction is far more common than overcorrection and typically requires revision. Fix with two divergent cancellous screws or a staple and check alignment before closure.

Mnemonic

CAVECAVE Mnemonic — Structures in the Lateral Hindfoot Wound (Anterior to Posterior)

Mnemonic

PLANPLAN Mnemonic — Combined Procedures for Cavovarus Correction

Primary Indications

Absolute Indications

Symptomatic hindfoot varus in cavovarus foot confirmed as hindfoot-driven on Coleman block test
Progressive hindfoot varus causing lateral ankle instability, peroneal tendon pathology, or stress fractures of the fifth metatarsal
Hindfoot varus as part of a combined surgical correction plan for cavovarus (CMT, residual clubfoot, post-polio, idiopathic cavus)
Failed conservative management including orthotics and physiotherapy for a minimum of 3-6 months

Relative Indications

Mild to moderate hindfoot varus with flexible subtalar joint in a young patient where triple arthrodesis is to be deferred
Varus component of hindfoot in spastic diplegic or post-neurological deformity where alignment correction aids function
Adjunct to peroneal tendon reconstruction where persistent hindfoot varus is driving tendon failure

Contraindications

Fixed subtalar arthritis: Triple arthrodesis preferred to osteotomy if joint is rigid or arthritic
Forefoot-driven varus (positive Coleman block test correction): Dwyer osteotomy is not indicated; address the forefoot deformity first
Peripheral vascular disease: Lateral hindfoot skin heals poorly; seek vascular opinion before surgery
Active infection: Absolute contraindication to elective osteotomy and hardware insertion
Severe osteoporosis: Fixation may be inadequate; relative contraindication requiring modified technique

Coleman Block Test — The Key Discriminator

Principle

The Coleman block test places a 2.5–3 cm wooden block under the heel and lateral aspect of the foot so the first, second, and third metatarsal heads are unsupported and can hang freely. The examiner observes the hindfoot alignment from behind.

Interpretation

Block test corrects heel to neutral (positive test): The varus is forefoot-driven — the plantarflexed first ray is causing compensatory supination of the hindfoot. The subtalar joint is flexible. The primary procedure must address the forefoot (plantar fascia release, peroneus longus to brevis transfer, first metatarsal dorsiflexion osteotomy). A Dwyer osteotomy may be added if residual hindfoot varus persists.
Block test does NOT correct heel (negative test): The varus is hindfoot-driven — the subtalar joint itself is the primary deformer. A Dwyer calcaneal osteotomy or subtalar arthrodesis is required. This is the classical Dwyer indication.

Clinical Importance

This single test determines the surgical algorithm. Performing a Dwyer in isolation without Coleman block assessment risks under-treating a forefoot-driven deformity and a poor outcome. Examiners expect this to be the first step in any cavovarus surgical planning discussion.

Evidence Base

Osteotomy of the calcaneum for pes cavus

Level V

Dwyer FC • J Bone Joint Surg Br

Clinical Implication: Establishes the named procedure and its mechanical principle — a lateral closing wedge corrects hindfoot-driven varus. This remains the conceptual basis for the operation.

Verify on PubMed (PMID 13620710)

A simple test for hindfoot flexibility in the cavovarus foot

Level V

Coleman SS, Chesnut WJ • Clin Orthop Relat Res

Clinical Implication: The block test is the gateway investigation that decides whether a Dwyer osteotomy is even indicated. Performing a calcaneal osteotomy without it risks operating at the wrong level.

Verify on PubMed (PMID 852192)

The subtle cavus foot, the underpronator

Level V

Manoli A 2nd, Graham B • Foot Ankle Int

Clinical Implication: Provides the modern conceptual framework for cavovarus surgery — the Dwyer is one component of a combined plan, not a stand-alone fix.

Verify on PubMed (PMID 15766431)

Soft tissue surgery in Charcot-Marie-Tooth disease

Level IV

Roper BA, Tibrewal SB • J Bone Joint Surg Br

Clinical Implication: Supports addressing the soft-tissue deforming forces (plantar fascia, peroneus longus) alongside any bony correction, and reserving fusion for fixed or arthritic joints.

Verify on PubMed (PMID 2914996)

Flexible cavovarus feet in CMT treated with first ray dorsiflexion osteotomy combined with soft tissue surgery

Level IV

Leeuwesteijn AEEPM, de Visser E, Louwerens JWK • Foot Ankle Surg

Clinical Implication: Confirms that a combined, block-test-guided approach — adding the calcaneal osteotomy only for residual hindfoot varus — gives high satisfaction with low recurrence in CMT cavovarus.

Verify on PubMed (PMID 20655015)

Fixation and Healing

No high-quality randomised or comparative trials define the optimal fixation construct for the Dwyer osteotomy. In practice the closing wedge is held with one or two screws (commonly large partially-threaded cancellous screws from the posterior tuberosity into the body) or with one or two staples; a low-profile plate is an alternative for poor bone. Choice is guided by bone quality and hardware-prominence concerns rather than by Level I evidence. The osteotomy is metaphyseal cancellous bone with broad apposition and typically unites by 6 to 8 weeks.

Clinical Decision Scenarios

Use these scenarios to practise clinical reasoning and management decisions

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"A 28-year-old physiotherapist presents with progressive right foot pain, recurrent lateral ankle sprains, and lateral foot calluses. On examination she has cavus posture, clawing of all toes, and hindfoot varus. You perform the Coleman block test and the heel corrects to neutral when the lateral three metatarsals are raised on the block. What do you do next?"

PRACTICAL APPROACH

This is a forefoot-driven cavovarus deformity — the positive Coleman block test tells me the hindfoot is flexible and the varus is driven by a plantarflexed first ray. This is the key discriminating finding: because the heel corrects on the block, the primary surgical target is the forefoot, NOT the calcaneus. A Dwyer calcaneal osteotomy in isolation would be treating the wrong level of the deformity and risks poor outcome and recurrence. My assessment would first include a thorough neurological examination to identify an underlying cause. The differential for cavovarus includes Charcot-Marie-Tooth disease (most common neurological cause), residual clubfoot deformity, polio, Friedreich's ataxia, and idiopathic. I would refer for nerve conduction studies and electromyography to screen for CMT even if she reports no family history, as CMT can present subtly. Imaging should include weight-bearing AP, lateral, and hindfoot alignment views of the foot and ankle. For surgical planning in this forefoot-driven flexible cavovarus, the procedure sequence would be: (1) plantar fascia release — the apex of the deformity; (2) peroneus longus to brevis transfer — the plantarflexed first ray is driven by a hyperactive peroneus longus acting as the first ray depressor while the weakened peroneus brevis causes lateral ankle instability, so transferring it to the brevis restores balance; (3) first metatarsal dorsiflexion osteotomy — directly elevates the plantarflexed first ray; and (4) re-assess the hindfoot. If significant residual hindfoot varus persists after the forefoot procedures, I would add a Dwyer calcaneal osteotomy in the same sitting. The Coleman block tells me the Dwyer may not be required as a primary procedure, but I must reassess after the forefoot work.

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"A 19-year-old male with confirmed Charcot-Marie-Tooth disease (CMT1A) has bilateral progressive cavovarus deformity. He is symptomatic on the right with lateral ankle instability and painful callosities. The Coleman block test on the right shows the heel does NOT correct on block testing. Walk me through your surgical plan."

PRACTICAL APPROACH

This patient has hindfoot-driven cavovarus on the right confirmed by the negative Coleman block test — the heel remains in varus even when the forefoot is supported, indicating a fixed hindfoot component that requires direct bony correction. However, I must also address the forefoot component as part of a comprehensive plan, as CMT cavovarus is rarely a single-level deformity. My pre-operative workup includes weight-bearing foot and ankle radiographs, a hindfoot alignment view to quantify the varus deformity and plan wedge size, and assessment for subtalar joint arthritis on CT or MRI, which would change the plan from osteotomy to triple arthrodesis. Neurological review to document current motor and sensory status and anticipate disease progression is also essential. The surgical plan for this hindfoot-driven CMT cavovarus foot would proceed as follows: First, plantar fascia release — even in hindfoot-driven deformity, the tight plantar fascia maintains the apex of the deformity and should be released. Second, peroneus longus to brevis transfer — eliminates the plantarflexion force on the first ray and enhances ankle eversion. Third, if first ray plantarflexion is severe, a first metatarsal dorsiflexion osteotomy. Fourth, the Dwyer calcaneal osteotomy — the key procedure in this case, since the block test showed the hindfoot deformity is intrinsic to the calcaneus. For the Dwyer technique: lateral position, lateral incision posterior to peroneal tendons, sural nerve identified and protected first (posterior to peroneal tendons), peroneal tendons retracted anteriorly. Subperiosteal calcaneal exposure with Hohmann retractors on both the superior and inferior surfaces. The osteotomy is marked on fluoroscopy, starting 1.5–2 cm posterior to the subtalar posterior facet. I remove a lateral closing wedge of 7–10 mm in this degree of deformity, preserving the medial cortex as a hinge. I close the wedge and check the Harris view — targeting neutral or very mild valgus. Fixation with two divergent 6.5 mm cancellous screws. Layered closure, taking particular care with skin, as CMT patients have neuropathic thin skin. I would counsel this patient that CMT is a progressive disease and further surgery may be needed in future. I would have a frank discussion about bilateral timing — I would offer the symptomatic right side first, reassess at 6 months, and plan the left side if it remains symptomatic.

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"You have completed a Dwyer calcaneal osteotomy for cavovarus. On the intraoperative Harris heel view before placing the screws, the heel appears to be in 8° of varus. What do you do? How do you prevent and manage the most common complications of this procedure?"

PRACTICAL APPROACH

Eight degrees of residual varus on the intraoperative Harris view is a technical problem that must be corrected before fixation. The goal of the Dwyer is to shift the heel to neutral or very mild valgus — accepting 8° of varus intraoperatively means the patient will walk in varus and the procedure will fail. I have not yet placed the definitive screws, so I have options. I would open the osteotomy slightly, remove an additional 1–2 mm sliver of lateral calcaneal bone under direct vision and fluoroscopy guidance, re-compress, and re-check the Harris view. If I had placed only a provisional Kirschner wire this would be straightforward. Once the heel is at neutral or slight valgus, I fix with two divergent cancellous screws and take final confirmatory views. For complications: the most common nerve complication is sural nerve injury occurring in 5–15% of cases. The sural nerve runs POSTERIOR to the peroneal tendons in the lateral hindfoot — this is the key anatomical relationship. Prevention requires identifying the nerve first in the subcutaneous layer before any deepening of dissection, protecting it with a vascular loop throughout the procedure. Most injuries are neuropraxia resolving within 6–12 weeks. A symptomatic neuroma developing beyond 12 months is managed with desensitisation therapy first; if refractory, surgical excision with proximal burial in the peroneus brevis muscle belly. The most common technical failure is under-correction, seen in 10–20%. Prevention requires pre-operative planning of wedge size on the hindfoot alignment view and mandatory fluoroscopic Harris view confirmation before fixation. Wound complications occur in 5–10% of neuropathic patients — CMT and diabetic patients have thin fragile lateral hindfoot skin. Prevention centres on atraumatic handling, no-touch skin technique, layered closure without tension, and prolonged non-weight-bearing if skin quality is borderline. Deep infection with exposed hardware requires formal washout.