Charcot Neuroarthropathy — Foot Reconstruction

Eichenholtz Classification — Staging Determines Timing

The Eichenholtz classification is the foundation for treatment decisions in Charcot neuroarthropathy. Surgery is timed according to the stage.

Sanders Anatomic Classification — Pattern Determines Approach

Type 2 (TMT/Lisfranc) is the most common pattern and the classic exam case for Charcot reconstruction.

Surgical Indications

Absolute Indications

• Unbraceable deformity — fixed rocker-bottom or hindfoot deformity that cannot be accommodated in a CROW boot, custom AFO, or total-contact cast
• Recurrent or non-healing plantar ulcer over a bony prominence despite adequate offloading (at least 3 months of TCC or CROW boot)
• Deep infection with osteomyelitis in the Charcot foot — requires debridement with or without concurrent stabilisation
• Acute instability or fracture-dislocation threatening the soft tissues (urgent external fixation in Eichenholtz Stage I)

Relative Indications

• Patient declining prolonged non-operative offloading
• Recurrent ulceration despite brace compliance
• Progressive deformity on serial radiographs despite immobilisation
• Inability to wear any footwear due to deformity

Contraindications

Absolute (for elective reconstruction):

• Eichenholtz Stage I (active fragmentation) — catastrophic failure of fixation and worsening of deformity
• Uncontrolled infection with systemic sepsis
• Critical ischaemia (ABI less than 0.45 or absolute toe pressure less than 30 mmHg) without planned revascularisation

Relative:

• Eichenholtz Stage 0 with no instability — treat non-operatively first
• HbA1c greater than 10 percent (optimise glycaemic control before elective surgery)
• Active smoking (increases nonunion and infection risk)
• End-stage renal disease on dialysis (markedly elevated infection and wound complication rates)
• Limited ambulatory potential or non-ambulatory patient (amputation may be more appropriate)

Evidence — Non-Operative vs Surgical Management

Total-Contact Casting

• TCC is the gold-standard non-operative treatment for acute Charcot (Eichenholtz 0 to I) and for offloading plantar ulcers
• A Cochrane review found TCC more effective than removable cast walkers for healing neuropathic plantar ulcers
• TCC for acute Charcot: cast changes every 1 to 2 weeks, continue for 8 to 12 weeks, until the foot cools clinically
• Long-term: transition to CROW boot or custom AFO once the foot is quiescent

Exostectomy

• Simple resection of a plantar bony prominence without arthrodesis
• Indicated for an isolated plantar prominence with a non-healing ulcer in a braceable foot
• Advantage: quick procedure, preserves joint mobility, lower morbidity than arthrodesis
• Recurrence rate: 30 to 50 percent at 2 to 3 years if the underlying deformity is not corrected — the prominence reforms because the deformity persists

Arthrodesis with Deformity Correction

• The definitive procedure for unbraceable Charcot deformity
• Midfoot (TMT) arthrodesis: corrects rocker-bottom, eliminates plantar prominence, provides a stable plantigrade foot
• Hindfoot (tibiotalocalcaneal) arthrodesis: corrects valgus or varus hindfoot deformity
• Ankle arthrodesis: for Charcot ankle destruction
• Fusion rates reported from 60 to 90 percent depending on the site, fixation method, and Eichenholtz stage at surgery

Key Evidence

Midfoot (Tarsometatarsal) Anatomy — The Charcot Battlefield

The Lisfranc (TMT) Complex

The tarsometatarsal joint complex is the most common site of Charcot collapse (Sanders Type 2). Understanding its anatomy is essential for planning the dorsal approach and selecting fixation points.

Key bony elements:

• Medial column: first metatarsal, medial cuneiform, navicular — relatively rigid, supports the medial arch
• Middle column: second metatarsal (keystone), intermediate cuneiform — recessed 1 to 2 mm proximal to the base of the first and third metatarsals, stabilised by the Lisfranc ligament
• Lateral column: third through fifth metatarsals, lateral cuneiform, cuboid — more mobile, accommodates uneven ground

Lisfranc ligament: the primary stabiliser of the second TMT joint. Runs from the plantar aspect of the medial cuneiform to the base of the second metatarsal. In Charcot collapse, this ligament is destroyed and the medial column drops, producing the rocker-bottom deformity.

Dorsal anatomy relevant to the surgical approach:

• Extensor hallucis longus (EHL) and extensor digitorum longus (EDL) tendons run superficially on the dorsal midfoot — retract medially or laterally depending on exposure needs
• Dorsalis pedis artery and deep peroneal nerve run between EHL and EDL on the dorsal midfoot — identify and protect
• The dorsal TMT joint capsules are directly beneath the tendons and neurovascular bundle

Tarsal Bone Anatomy — Midtarsal (Sanders Type 3)

• Talonavicular joint: the most mobile joint in the foot, key to midtarsal motion. Charcot destruction here produces lateral column collapse and forefoot abduction
• Naviculocuneiform joint: connects the navicular to the three cuneiforms. Charcot involvement here collapses the medial arch
• Calcaneocuboid joint: the lateral column fulcrum. Destruction produces valgus hindfoot with abduction of the forefoot

Hindfoot Anatomy — Sanders Type 4

• Subtalar joint: articulation between talus and calcaneus. Charcot destruction produces progressive hindfoot valgus or varus depending on the pattern of collapse
• Talocrural (ankle) joint: Charcot ankle destroys the tibiotalar articulation, producing instability, progressive valgus, and collapse of the talar dome
• Posterior tibial tendon: inserts on the navicular tuberosity. Often attenuated or ruptured in hindfoot Charcot — contributes to progressive flatfoot deformity

Blood Supply of the Tarsus

• Dorsalis pedis artery: supplies the dorsal midfoot. Ligated or damaged during dorsal approach — plan dissection to preserve where possible
• Medial plantar artery: supplies the plantar midfoot and heel. At risk during extensive medial column dissection
• Perforating branches: connect dorsal and plantar systems. Essential for wound healing — avoid devascularising bone fragments during deformity correction

Deformity Patterns and Their Biomechanical Consequences

Rocker-Bottom Midfoot (Sanders Type 2)

The medial column collapses through the first and second TMT joints. The navicular and medial cuneiform drop plantarly. The cuboid and lateral column may also sublux. The net effect is a convex plantar midfoot prominence directly beneath the plantar fat pad, which ulcerates under the body weight of the insensate patient.

Biomechanical consequence: loss of the longitudinal arch, transfer of load from the heel to the midfoot prominence, ulceration, and eventual skin breakdown with risk of osteomyelitis.

Lateral Column Collapse (Sanders Type 3)

Collapse through the talonavicular and calcaneocuboid joints produces forefoot abduction relative to the hindfoot. The patient presents with a flatfoot deformity, lateral foot pain, and difficulty fitting shoes.

Hindfoot Valgus (Sanders Type 4)

Subtalar and ankle Charcot produces progressive hindfoot valgus, talar dome collapse, and fibular impingement on the lateral malleolus. Medial malleolar ulceration is common.

Pre-operative Preparation

Medical Optimisation

• Glycaemic control: HbA1c below 8 to 9 percent is the practical target before elective Charcot reconstruction
• Vascular assessment: ABI, toe pressures, or formal angiography. Revascularise before elective surgery if ABI less than 0.45 or toe pressure less than 30 to 40 mmHg
• Nutrition: albumin above 3.0 g/dL, pre-albumin above 15 mg/dL. Optimise nutrition in malnourished patients
• Smoking cessation: mandatory before elective reconstruction
• Infection screen: if an active ulcer is present, obtain deep wound cultures and MRI to rule out osteomyelitis before planning definitive fusion. If osteomyelitis is confirmed, a staged approach (debridement first, fusion after clearance) is required

Imaging

• Weight-bearing radiographs of both feet (AP, lateral, oblique) — essential for deformity measurement and pre-operative planning
• CT scan — detailed assessment of fragmentation pattern, bone stock, and joint involvement for hardware planning
• MRI — differentiate Charcot from osteomyelitis (both show marrow oedema); identify abscess, sinus tracts, and the extent of bone infection if present
• Bone scan — less specific than MRI but useful if MRI is contraindicated or unavailable; a labelled white-cell scan can distinguish Charcot from infection

Positioning and Anaesthesia

Patient position: Supine with a sandbag under the ipsilateral buttock to internally rotate the leg and bring the dorsum of the foot into the surgical field. Place a bump under the knee to relax the popliteal structures if a posterior approach is needed for tibial nail insertion.

Tourniquet: thigh tourniquet inflated to 250 to 300 mmHg. In diabetic patients with vascular disease, limit tourniquet time to less than 90 to 120 minutes if possible.

Anaesthesia: general or spinal anaesthesia. Regional block (popliteal sciatic and saphenous) provides post-operative analgesia and reduces opioid requirements.

Fluoroscopy: C-arm positioned from the contralateral side for lateral views and from the foot end for AP views. Essential for confirming hardware position, deformity correction, and plantar prominence removal.

Approach Selection

The approach depends on the Sanders pattern and the joints to be fused.

Dorsal Approach to Midfoot (TMT/Lisfranc) — Step-by-Step

Step 1: Skin Incision

Mark the planned incision with the foot in the position of deformity. For a midfoot Charcot reconstruction, use a longitudinal dorsal incision over the second TMT joint, centred on the apex of the deformity. Extend proximally to the naviculocuneiform joint and distally to the second metatarsal base as needed.

In cases requiring extensive exposure (multiple TMT joints), two separate dorsal incisions (one over the first TMT, one over the second to fourth TMT) may be used to avoid a single long incision with problematic wound edges.

Step 2: Deep Dissection and Joint Exposure

Deepen through subcutaneous tissue to the extensor retinaculum. Identify and protect the EHL and EDL tendons. Locate the dorsalis pedis artery and deep peroneal nerve running between EHL and EDL — retract these with vessel loops.

Retract EHL medially and EDL laterally. Incise the dorsal joint capsules of the TMT joints longitudinally. Clear soft tissue and Charcot debris from the joint surfaces using curettes and rongeurs.

Step 3: Deformity Assessment and Bone Resection

Before any resection, place a K-wire into the medial cuneiform and another into the talus. Check alignment under fluoroscopy to understand the deformity apex and the amount of correction needed.

Resect the Charcot debris and sclerotic bone from the TMT joint surfaces using an oscillating saw and osteotomes. The goal is to create bleeding cancellous bone surfaces that will fuse. Remove enough bone to allow realignment of the medial column — typically 5 to 15 mm of resection at the apex.

The critical manoeuvre: correct the dorsal angulation at the TMT joints by bringing the forefoot into a plantigrade position relative to the hindfoot. Confirm under fluoroscopy that the plantar midfoot prominence has been eliminated.

Step 4: Temporary Reduction and Fluoroscopic Check

Reduce the TMT joints anatomically. Hold the reduction with temporary K-wires placed from dorsal to plantar across each TMT joint. Check under fluoroscopy in AP, lateral, and oblique views:

• AP: TMT joints aligned, medial column restored, no residual subluxation
• Lateral: plantigrade foot, no plantar prominence, Meary angle corrected
• Oblique: second TMT joint reduced (keystone restored)

Step 5: Definitive Fixation

Remove the temporary K-wires sequentially and place definitive fixation.

Dorsal plate fixation: Apply pre-contoured medial and dorsal plates across the TMT joints. The first TMT joint receives a medial plate along the medial cuneiform to the first metatarsal. The second and third TMT joints receive dorsal plates from dorsal to plantar across the cuneiforms and metatarsal bases.

Screw supplementation: Add large-diameter (4.0 to 6.5 mm) partially threaded cannulated screws across each TMT joint from dorsal to plantar or medial to lateral, depending on the trajectory. Lag screw technique compresses the arthrodesis surfaces.

Bolt fixation: For the medial column, a medial bolt from the first metatarsal head through the medial cuneiform and into the navicular provides powerful compression across the entire medial column arthrodesis. This is particularly useful when the Charcot zone extends to the naviculocuneiform joint.

Step 6: Bone Grafting

Fill the arthrodesis bed with autograft bone (iliac crest harvest or local calcaneal graft). In extensive defects, supplement with allograft cancellous chips or BMP-2 on an absorbable collagen sponge. Graft into all resection gaps and between joint surfaces.

Step 7: Wound Closure and Immobilisation

Release the tourniquet, achieve haemostasis, and close the wound in layers. Apply a well-padded below-knee posterior splint or cast with the foot in neutral dorsiflexion and slight hindfoot valgus.

Exostectomy — Simpler Alternative

Indications

• Isolated plantar bony prominence with a non-healing ulcer in a foot that is otherwise braceable
• Medically unfit patient for a long arthrodesis procedure
• Bridge procedure in Eichenholtz Stage II before definitive arthrodesis can be planned

Technique

1. Approach via a plantar incision directly over the ulcer or prominence. Excise the ulcer en bloc with the underlying bony prominence.
2. Resect the plantar bony prominence flush with the surrounding plantar cortex using a rongeur or oscillating saw.
3. Check fluoroscopically that no residual plantar prominence remains.
4. Obtain deep cultures of the resected bone — if osteomyelitis is found, extend the debridement and consider subsequent arthrodesis.
5. Close the wound over a drain. Apply TCC.

Hindfoot Reconstruction — Tibiotalocalcaneal (TTC) Arthrodesis

Indications

• Sanders Type 4 (hindfoot Charcot) with ankle or subtalar destruction
• Combined ankle and subtalar Charcot producing valgus collapse and instability
• Salvage after failed midfoot arthrodesis that has progressed to hindfoot involvement

Technique Overview

• Approach: Lateral trans-fibular approach for nail insertion. The fibula is osteotomised and the proximal fragment is removed (fibular subtraction) to access the ankle and subtalar joint. A posterolateral incision is used for nail entry point at the calcaneal tuber.
• Joint preparation: Resect the tibial plafond, talar dome, and subtalar joint surfaces to bleeding bone. Correct the hindfoot alignment to neutral or slight valgus.
• Fixation: Insert a retrograde tibiotalocalcaneal intramedullary nail from the calcaneal tuber, across the subtalar joint, through the talar body, and into the tibial medullary canal. The nail spans from calcaneus to tibia — the ultimate superconstruct. Add anterior locking screws from the nail into the talar neck and calcaneus for rotational control.
• Bone graft: Fill the resection defects with autograft and allograft.

Intramedullary Beaming — Midfoot Supplement

Concept

In addition to plate and screw fixation, intramedullary beaming (smooth or threaded K-wires or small-diameter nails placed along the metatarsal medullary canals from dorsal to plantar) provides axial load-sharing that protects the plate-and-screw construct from bending failure. Beams are placed into the first, second, and sometimes third metatarsals through the dorsal plate exposure, crossing the TMT arthrodesis site and seating into the cuneiform or tarsal bones.

Advantages

• Protects the plate-and-screw construct from cyclic loading in the osteopenic Charcot foot
• Low profile — does not add hardware prominence
• Can be removed in clinic once fusion is confirmed (6 to 12 months)

Post-operative Protocol

Immediate Post-operative Phase (Weeks 0 to 2)

• Immobilisation: Non-weight-bearing below-knee cast or rigid posterior splint. Elevate for 48 to 72 hours to reduce swelling.
• Wound inspection: At 5 to 7 days (wound check), then weekly for the first 6 weeks. Inspect all incisions and any previous ulcer sites. Insensate patients require careful visual inspection rather than relying on pain.
• Analgesia: Multimodal — paracetamol, NSAIDs (if renal function permits), and short-course opioids. Gabapentin or pregabalin may help neuropathic pain.
• Antibiotics: If a pre-operative ulcer was present, continue targeted antibiotics based on intraoperative cultures for 4 to 6 weeks.

Protected Weight-bearing Phase (Weeks 2 to 8 to 12)

• Weeks 2 to 6: Strict non-weight-bearing in below-knee cast. Cast changes every 2 weeks with wound inspection.
• Weeks 6 to 8: If early radiographs suggest consolidation, transition to a CROW boot or total-contact cast with touch-down weight-bearing (less than 15 kg) only.
• Weeks 8 to 12: Progressive weight-bearing in a CROW boot as tolerated, guided by serial radiographs showing progressive consolidation.

Transition to Footwear (Weeks 12 to 16 Plus)

• Weeks 12 to 16: If fusion is confirmed radiographically (bridging trabeculae on three views, no hardware loosening), transition to a diabetic shoe with custom-moulded insole.
• Long-term: Custom-moulded orthotics or CROW boot indefinitely in many patients. The fused Charcot foot remains at risk of ulceration from abnormal pressure distribution.
• Hardware removal: Consider removal of prominent dorsal plates or plantar-sided hardware at 9 to 12 months once fusion is solid, to reduce the risk of hardware-related ulceration.

Total-Contact Casting — The Non-Operative Gold Standard

Indications

• Acute Charcot (Eichenholtz Stage 0 to I) — initial management
• Plantar ulcer offloading
• Post-operative protection after exostectomy
• Protected weight-bearing after Charcot arthrodesis (in later phases)

Technique

1. Apply a thin layer of stockinette over the foot and lower leg (do not fold back over the toes — keep toes visible for monitoring)
2. Place felt padding over bony prominences (malleoli, tibial crest, heel) — avoid the ulcerated area
3. Wrap the foot and leg in two layers of cast padding, moulding the plantar surface to the corrected foot shape
4. Apply plaster of Paris (or fibreglass) in a below-knee configuration. Mould the cast against the plantar surface to redistribute pressure away from the ulcer or prominence
5. Cast changes every 1 to 2 weeks for inspection

Complications of TCC

• New pressure ulceration from cast (inspect skin at every change)
• Ankle equinus contracture from prolonged immobilisation
• Patient non-compliance (difficult for obese patients or those with limited hand function)

Special Case: Charcot with Active Osteomyelitis

Management Principles

• Osteomyelitis and Charcot can coexist and are difficult to distinguish on MRI alone (both show marrow oedema)
• If osteomyelitis is confirmed by deep bone biopsy or positive labelled white-cell scan, the primary pathology is infection, not Charcot
• Treatment: aggressive surgical debridement of infected bone, culture-directed antibiotics for 6 to 8 weeks, and delayed reconstruction after infection clearance
• Definitive arthrodesis should not be performed through infected bone — the fusion will fail
• If the foot is unstable after debridement, temporary external fixation provides stability while infection is controlled

Special Case: Charcot with Critical Ischaemia

Management Principles

• ABI less than 0.45 or toe pressure less than 30 to 40 mmHg indicates critical limb ischaemia
• Revascularisation (angioplasty or bypass) must be performed before elective Charcot reconstruction
• Post-revascularisation, allow a 2 to 4 week period for reperfusion before proceeding with fusion
• In patients who cannot be revascularised, amputation may be the most appropriate option — reconstruction in an ischaemic foot carries catastrophic wound complication rates

Special Case: Bilateral Charcot Foot

Management Principles

• Up to 25 percent of patients with Charcot foot develop contralateral involvement
• If one foot has already been reconstructed and the contralateral side develops active Charcot, immobilise the new Charcot foot in TCC while the reconstructed side is protected in a CROW boot
• Bilateral reconstruction is possible but staged — allow one side to fuse and resume weight-bearing before operating the other side
• Bilateral non-weight-bearing creates nursing and mobility challenges — plan for inpatient rehabilitation or extended physiotherapy input