Dwyer Calcaneal Osteotomy

Indication. Symptomatic hindfoot varus in a cavovarus foot that has failed conservative management (orthotics and physiotherapy for a minimum of 3–6 months) AND is confirmed as hindfoot-driven on the Coleman block test. The deformity is most often part of a combined cavovarus correction in Charcot-Marie-Tooth disease, residual clubfoot, post-polio sequelae or idiopathic cavus — it is rarely a stand-alone operation. Assess the whole foot, not just the heel. Before committing to a calcaneal cut, decide whether the varus is hindfoot-driven or forefoot-driven, and plan the combined procedure list accordingly:

The Coleman block test — the single test that decides the algorithm. Place a 2.5–3 cm wooden block under the heel and the lateral aspect of the foot so the first, second and third metatarsal heads hang free, and observe the hindfoot from behind.

Consent specifically for lateral foot numbness or a painful sural nerve neuroma (5–15%), wound dehiscence (5–10% in neuropathic patients), residual or recurrent varus needing revision (10–20%), and the progressive nature of underlying neurological disease (particularly CMT), which may require further surgery. Setup. Lateral decubitus, operative foot uppermost (prone is an alternative), beanbag or axillary roll, contralateral leg padded. C-arm available for lateral and axial (Harris) heel views and confirmed working before skin preparation. Thigh tourniquet to 250–300 mmHg after exsanguination (typical tourniquet time under 45 minutes for the osteotomy alone). Mark the peroneal tendons, the sural nerve course and the intended incision before skin prep.

The goal is to remove a lateral closing wedge of bone from the calcaneal tuberosity through a lateral approach, protecting the sural nerve and the peroneal tendons, so that the heel shifts from varus towards neutral or very mild valgus. The exposure — the lateral calcaneal approach with identification of the sural nerve and peroneal tendons — is laid out as the first steps below and is the heart of the operation.

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Rehabilitation | Phase | Timing | Immobilisation & weight-bearing | Therapy & milestones | |-------|--------|---------------------------------|----------------------| | 1 | 0–2 weeks | Below-knee backslab in slight equinus for 48 h, then neutral non-weight-bearing cast; strict NWB, elevate | Wound check and suture removal at 14 days; upper-limb and core work while NWB | | 2 | 2–6 weeks | Continue strict NWB in a below-knee cast; serial radiographs every 2 weeks for callus | Monitor for sural nerve symptoms and wound healing, especially in neuropathic patients | | 3 | 6–10 weeks | If radiographic healing confirmed, partial then full weight-bearing in a CAM walker boot | Ankle and subtalar ROM, peroneal strengthening (especially if PL-to-PB transfer also performed), gait re-education | | 4 | 10 weeks–6 months | Wean boot to supportive footwear; custom orthotics if needed | Return to running at 4–5 months; return to sport at 4–6 months | Bone healing is seen radiographically at 6–8 weeks. Most patients return to light activities at 10–12 weeks and to sport at 4–6 months; full functional recovery, including strength, can take up to 12 months when combined with tendon transfers. In CMT, monitor long-term for disease progression that may require further surgery. Complications

Pathoanatomy — why a plantarflexed first ray drives the hindfoot. The foot is a tripod of the heel and the first and fifth metatarsal heads. When the first ray is plantarflexed (by overaction of peroneus longus against a weak tibialis anterior, compounded by a weak peroneus brevis), the forefoot pronates and the hindfoot must supinate into varus to keep all three tripod points on the ground. This is the Manoli and Graham paradigm — the "subtle cavus foot" or "underpronator" — and it explains why a Dwyer done in isolation for a forefoot-driven deformity fails: the correction is lost once the foot bears weight again. Addressing all the deforming forces, not a single bone cut, is the modern principle of cavovarus surgery.

Etiologies of cavovarus. Cavovarus is a neurological deformity until proven otherwise. The common causes to name in the viva are Charcot-Marie-Tooth disease (the most common neurological cause), residual clubfoot deformity, post-polio sequelae, Friedreich's ataxia, spinal dysraphism and idiopathic cavus. Always examine neurologically and arrange nerve conduction studies even when no family history is volunteered. Fixation and healing. No high-quality randomised or comparative trials define the optimal fixation construct. In practice the closing wedge is held with one or two large partially-threaded cancellous screws (commonly 6.5–7.0 mm from the posterior tuberosity into the body) or with staples; a low-profile plate is an alternative for poor bone. Choice is guided by bone quality and hardware-prominence concerns rather than Level I evidence. The osteotomy is metaphyseal cancellous bone with broad apposition and typically unites by 6 to 8 weeks.