Conservative Management

1. The Offloading Principle

The pathophysiology cascade in Part II is self-sustaining only as long as the foot is mechanically loaded. Mechanical loading produces continuing microtrauma, DAMPs, cytokines, RANKL upregulation, osteoclast activation, more bone resorption. Removing the load breaks the loop — the molecular drivers fall, oedema resolves, fragmentation stops, and the foot transitions from Stage I to Stage II.

The clinical goals of offloading are:

• Stop further deformity — arrest fragmentation.
• Resolve inflammation — \(\Delta T < 2\,^\circ\text{C}\) sustained.
• Permit consolidation — allow Eichenholtz II/III.
• Preserve plantar skin — prevent ulceration over bony prominence.
• Maintain ambulation — even if limited, complete bedrest is rarely realistic.

The hierarchy of offloading devices (in descending order of compliance with the offloading goal):

1. Total contact cast (TCC) — non-removable; gold standard for active CN.
2. Instant TCC — a Walker boot rendered non-removable with cohesive bandage.
3. Removable cast walker / Walker boot (e.g., Bledsoe, Aircast) — less compliant.
4. CROW boot — custom moulded ankle-foot orthosis (transition to chronic).
5. Custom shoe + insole — for healed Stage III foot.
6. Wheelchair / non-weight-bearing — rarely realistic but cited for severe ankle Charcot.

Compliance is the dominant determinant of outcome. A removable boot left off “just to walk to the bathroom” is the single commonest cause of failed conservative management. The case for non-removable casting is ultimately about behaviour, not biomechanics.

2. Total Contact Cast — The Standard of Care

The total contact cast (TCC) was developed by Paul Brand in the 1950s for leprosy patients with neuropathic ulcers, refined for diabetic neuropathic ulcers (Mueller et al., Diabetes Care 1989), and is now the international standard for active Charcot.

Why TCC works:

• Non-removable — eliminates patient non-compliance.
• Total contact — the cast is moulded intimately to the foot, distributing load over the entire plantar surface, not just the metatarsal heads or midfoot apex.
• Pressure redistribution — peak plantar pressure at the affected midfoot is reduced by ~80–90% (Lavery et al., Diabetes Care 1996; from ~200 to ~30 N·cm⁻²).
• Shaft loading — some force transferred up the cast wall to the proximal tibia.
• Limb immobilisation — reduces shear and torque, the most damaging components.

Evidence: in healing of neuropathic ulcers, TCC heals 80–90% within 6 weeks, compared with ~65% for removable boot and ~58% for half-shoe (Armstrong et al., Diabetes Care 2001). For Charcot, the comparable end-point is resolution of \(\Delta T\) and transition from Stage I to II, which TCC achieves in ~60–90% within 8–12 weeks(median total casting duration ~3–6 months for the entire course).

3. TCC Technique

A safe TCC requires careful technique. Practical sequence (Mueller and Sinacore; Cavanagh and Bus, Diabetes Metab Res Rev 2008):

1. Inspect the foot — pulses, skin breakdown, ulcer measurement, callus.
2. Wound care — if ulcer present, debride, dress with non-adherent saline gauze.
3. Stockinette & toe-cap — cotton stockinette over the foot and lower leg; foam toe-cap over toes.
4. Padding — bony prominences (malleoli, heel, tibial crest, anterior tibialis tendon, navicular tuberosity) padded with adhesive felt; minimal padding elsewhere — the cast must be intimate.
5. Plaster inner layer — one or two rolls of plaster carefully moulded to the contours of the foot, especially under the longitudinal arch.
6. Fibreglass outer layer — two to three rolls for strength and durability; allows shower with a cast cover.
7. Walking heel / cast shoe — rocker-bottom rubber heel placed at midfoot to allow ambulation while reducing forefoot/midfoot push-off pressure.
8. Cast cure — 24–48 h before full weight-bearing.

Cardinal hazard: iatrogenic ulceration from a poorly padded cast or a missed edge. The TCC must be changed at the first complaint of focal pain, foul smell, drainage, or cast looseness (foot oedema fluctuates substantially in the first weeks). Patients should be told: “If anything feels different, come in.”

Contraindications: gangrene, active infection requiring frequent inspection, deep ulcer with abscess, severe limb-threatening ischaemia (relative). Patients with these are managed first for the contraindicating problem, then converted to TCC.

4. Monitoring & The Cast Cycle

Casting is not a fire-and-forget intervention. Standard cadence:

• Week 1–2 — review at 1 week; cast may be loose due to oedema resolution; replace if so.
• Week 2–6 — cast change every 2 weeks. Foot oedema continues to fluctuate.
• After week 6 — cast change every 2–4 weeks; assess skin, temperature, radiographs at each change.
• Decision points — at each change: \(\Delta T\), oedema, radiographs, ulcer status.

The exit criteria from active casting:

1. \(\Delta T < 2\,^\circ\text{C}\) sustained for at least 1–2 weeks.
2. Radiographic transition from Stage I to Stage II (coalescence; periosteal new bone, no further fragmentation).
3. Resolution of soft-tissue swelling.
4. No new ulceration.

Typical total duration of casting: 3–6 months for midfoot CN (sometimes longer); 6–12 months for hindfoot/ankle CN (Brodsky 2–3A), which has higher instability and slower resolution.

5. CROW Boot & Walker Boots

Once the foot has cooled and entered Stage II, transition from TCC to a CROW boot (Charcot Restraint Orthotic Walker) is the standard pathway. CROW is a custom-moulded, bivalved, total-contact ankle-foot orthosis with a rocker-bottom sole. It:

• Is custom-moulded, intimately fitted (like TCC).
• Is removable (unlike TCC) for skin inspection, hygiene, dressing changes.
• Distributes pressure over the entire plantar surface and onto the proximal calf shell.
• Has a rocker-bottom sole that moves push-off forces away from the metatarsal heads or midfoot apex.
• Reduces peak plantar pressure ~70% versus standard footwear.

CROWs are typically worn for 6–12 months beyond TCC, spanning Stage II and into early Stage III. They are constructed from a plaster cast or 3D-scanned mould of the patient’s foot, with polypropylene shell, plastazote / pelite inner lining, and rocker outsole.

Removable cast walkers (RCWs)— commercial Walker boots such as Aircast, Bledsoe, DH Pressure Relief Walker — are alternatives where TCC is not available. They offer similar pressure redistribution when worn; the central problem is compliance. The “instant TCC” technique — rendering an RCW non-removable with a layer of cohesive bandage or cast tape (Katz et al., Diabetes Care 2005) — bridges the compliance gap and is supported by IWGDF when full TCC is not available.

Patient education for CROW use: wear during all weight-bearing, including overnight bathroom trips; remove only for inspection and hygiene; monitor skin daily; report any redness, warmth, or new pain immediately.

6. Custom Footwear & Insoles — The Lifelong Phase

Once Stage III is established and the foot is stable in a CROW, the long-term goal is to move into definitive accommodative footwear that the patient will wear for the rest of life. Components:

• Extra-depth, custom-moulded shoe — soft upper, removable footbed.
• Custom multi-density insole — plastazote/pelite inner, cushion middle, semi-rigid base; moulded to the deformed plantar contour to redistribute pressure away from any rocker-bottom apex.
• Rocker outsole — reduces forefoot push-off pressure.
• Rigid shank — prevents midfoot dorsiflexion through the unstable region.
• Steel/carbon-fibre footplate if needed for severe deformity.
• Heel modifications — medial flare, SACH heel for hindfoot/ankle CN.

The Medicare Therapeutic Shoe Bill in the US (and equivalent programmes elsewhere) covers one pair of extra-depth diabetic shoes plus three pairs of custom insoles per year for at-risk diabetics, including all CN patients. The single biggest predictor of footwear effectiveness is wear-time: instrumented insole studies (Bus et al., Diabetes Care 2013) show median daily wear of only ~30% of waking hours despite prescription, with ulcer recurrence concentrated in the low-wear group.

For ulcer-prone Stage III feet (especially Brodsky type 1 with marked rocker-bottom prominence), prescription ankle-foot orthoses (AFO) or even continued CROW use may be lifelong. The goal is “ulcer-free, hospitalisation-free, and ambulatory”, the “remission” concept articulated by Armstrong, Boulton & Bus (NEJM 2017).

7. Bisphosphonates & Anti-Resorptive Therapy

Given the central role of RANKL-driven osteoclastic resorption (Part II), anti-resorptive pharmacotherapy is biologically appealing. Trials to date, however, have not demonstrated improvement in clinically meaningful outcomes (deformity, ulceration, amputation).

Current consensus (IWGDF 2023; Frykberg et al., J Foot Ankle Surg 2008): bisphosphonates are not standard of care for acute Charcot and should not be used routinely. They may be considered in selected recalcitrant cases that fail to cool with adequate casting alone, after clear discussion of the lack of clinical-outcome evidence.

Denosumab — the monoclonal anti-RANKL antibody — is mechanistically more directly targeted than bisphosphonates. Pilot studies (Busch-Westbroek et al., Diabetes Care 2018) showed faster cooling and consolidation; the ongoing BoneCharcot RCT is testing whether this translates to outcome benefit. Until results are in, denosumab remains experimental in CN.

Other agents: calcitonin (one small RCT showed marker effect; no clinical benefit confirmed), teriparatide (PTH 1-34; theoretically counterproductive in active resorption but useful in consolidation; no good Charcot data), and bone-morphogenetic protein-2 (BMP-2) as adjunct to surgical reconstruction. See Pharmacology for the broader anti-resorptive landscape.

8. Adjuncts — LIPUS, BMP, Hyperbaric, EBM

• Low-intensity pulsed ultrasound (LIPUS) — daily 20-minute home device, FDA-cleared for fracture healing. Some evidence for accelerated CN consolidation in case series; no definitive RCT.
• Bone-morphogenetic protein-2 (rhBMP-2) — off-label adjunct in surgical arthrodesis of CN; small case series suggest improved fusion rates in compromised hosts; cost-effective only in highest-risk reconstructions.
• Pulsed electromagnetic fields (PEMF) — FDA-cleared for non-union; limited CN-specific data.
• Hyperbaric oxygen (HBO) — for refractory ulcers in CN feet, especially with concurrent ischaemia or osteomyelitis; selective use, NICE/IWGDF reserves it for non-healing ischaemic / infected wounds.
• Negative-pressure wound therapy (NPWT) — for healing of post-operative wounds and chronic ulcers; not directly disease-modifying.
• Electrical bone-growth stimulators — useful in arthrodesis non-union of CN feet.

These adjuncts share a feature: weak evidence, biologically plausible, widely used in selected centres. They are not substitutes for offloading; they are aimed at the margins of recalcitrant or post-operative cases. The IWGDF 2023 guidance is, broadly, to consider them on a case-by-case basis but not to expect them to substitute for casting and footwear discipline.

9. Outcomes & Predictors of Failure

Conservative management of Charcot, properly applied, achieves:

• Resolution of acute disease in 80–90% of patients within 6–12 months.
• Avoidance of surgery in ~70–80% of patients.
• Limb salvage in >90% (vs ~50–70% if Charcot is missed and superimposed osteomyelitis develops).
• Stable, ambulatory Stage III in 70–85% of survivors at 5 years, with appropriate footwear discipline.

Predictors of conservative failure (Pinzur et al., Foot Ankle Int 2003; Sayner and Rosenblum, JFAS 2005):

• Brodsky type 2–3A (hindfoot/ankle) — less stable; instability often persists despite casting.
• Severe deformity at presentation — rocker-bottom established before casting begins.
• Ulceration with probable osteomyelitis.
• Poor compliance with offloading — failure to wear cast/CROW consistently.
• Persistent hyperaemia — \(\Delta T > 2\,^\circ\text{C}\) despite 6+ months of casting.
• Severe peripheral arterial disease.
• Concurrent neuropathic complications — ESRD, transplant.

Patients with these features — especially Brodsky 3A ankle CN with progressive instability, recurrent ulceration over rocker-bottom apex, or non-resolving hyperaemia despite proper casting — are candidates for the surgical reconstructive options of Part VII. Conservative management is the standard of care, but it is not the answer to every Charcot foot.