Scarf and Akin Osteotomy for Hallux Valgus

Indication. Symptomatic, moderate hallux valgus — a painful bunion limiting function — with HVA 20–40° and IMA 13–20° and a congruent metatarsophalangeal joint on weight-bearing radiographs, that has failed conservative management (at least six months of wide toe-box footwear, orthotics with a bunion pad, activity modification and NSAIDs). The congruent joint is critical: a subluxed, incongruent MTPJ needs realignment, not an osteotomy alone. Relative indications include younger, higher-demand patients (typically under 60) wanting length preservation, transfer metatarsalgia where the scarf's length-preserving geometry helps (versus the shortening chevron), and revision after a failed distal osteotomy when bone stock and TMT stability allow. Contraindications. Severe deformity (IMA over 20° or HVA over 40° — favour a Lapidus), TMT joint hypermobility (translation over 9mm — favour a Lapidus), an incongruent or subluxed MTPJ, active infection or soft-tissue compromise, peripheral vascular disease, severe osteoporosis (fixation failure), and inflammatory arthropathy with MTPJ arthritis (arthrodesis preferred). Where the scarf sits in the ladder. Procedure choice is driven by deformity severity and TMT stability, not by a presumed large advantage of one cut over another — the level-I RCT evidence shows scarf and chevron correct mild-to-moderate deformity equivalently:

Pre-operative assessment. Weight-bearing AP and lateral foot radiographs are mandatory — measure the HVA, IMA, DMAA, assess MTPJ congruency and sesamoid position, and compare first metatarsal length. Test TMT stability clinically: passive dorsoplantar translation over 9mm suggests hypermobility and pushes toward a Lapidus. Consent specifically for dorsomedial numbness or a tender neuroma (15–20%), recurrence (8–12% at five years), hallux varus from over-correction (2–5%), transfer metatarsalgia, hardware irritation (10–15%), stiffness, and the 12–16-week return to normal footwear. Setup. Supine with a bump under the ipsilateral hip to bring the first metatarsal into the horizontal plane, thigh tourniquet, regional or general anaesthesia. Mark landmarks and check the contralateral foot for symmetry before inflation.

The goal: correct the deformity through a medial exposure of the first metatarsal, perform the Z-shaped scarf osteotomy to close the intermetatarsal angle while preserving metatarsal length, add a stepwise lateral soft-tissue release and (when indicated) an Akin osteotomy of the proximal phalanx, and stabilise the correction with two headless compression screws. The exposure — the medial incision, protection of the dorsomedial cutaneous nerve, subperiosteal capsular elevation and the stepwise lateral release — is laid out as the first steps below and is the heart of the operation.

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Rehabilitation | Phase | Timing | Weight bearing | Therapy | |-------|--------|----------------|---------| | 1 | 0–2 weeks | Heel weight bearing in a postoperative shoe, crutches for balance | Elevation and ice; bulky dressing kept clean and dry | | 2 | 2–6 weeks | Progress to forefoot weight bearing in the postoperative shoe; wean crutches | Sutures out at 2 weeks; gentle active and passive MTPJ range of motion | | 3 | 6–12 weeks | Transition to a supportive wide-toe-box shoe at 6 weeks | Progressive MTPJ range and strengthening (toe curls, marble pickup) | | 4 | 3–6 months | Normal footwear as comfort allows | Return to impact activity at 12–16 weeks once union is confirmed; fashion footwear at 4–6 months | Radiographs at 2 weeks (alignment and hardware), 6 weeks (healing progression) and 12 weeks (union). Most patients return to sedentary work at 2–4 weeks, light duty at 6–8 weeks, and normal footwear by 12–16 weeks. Give VTE prophylaxis by risk (aspirin 100mg daily for two weeks if low risk; LMWH if high risk). Avoid NSAIDs for the first 12 weeks where bone healing is the concern. Complications

Additional complications - Dorsomedial cutaneous nerve injury (15–20%, usually a transient neuropraxia): identify and protect the nerve, retract gently, avoid retractor pressure. Most resolve over 3–6 months; a small permanent numb area is usually well tolerated; desensitisation if bothersome.

• Stiffness / reduced MTPJ range of motion (10–15%, usually a mild loss under 10°): start protected range-of-motion exercises from two weeks, avoid over-correction, preserve the capsule for anatomic closure. Physiotherapy; manipulation under anaesthesia if severe and within 12 weeks.
• Infection (under 2%): peri-operative cefazolin 2g IV within 60 minutes, sterile technique, minimise tourniquet time. Superficial cellulitis: oral antibiotics. Deep infection: operative debridement, retain stable hardware within four weeks, remove loose hardware or infection beyond four weeks, with six weeks of IV antibiotics.

Pathoanatomy. Hallux valgus is a progressive triplanar deformity of the first ray. The primary deforming force is the adductor hallucis, which attaches to the lateral sesamoid and the proximal phalanx base and pulls the hallux laterally. As the deformity progresses the abductor hallucis is displaced plantarly and loses its mechanical advantage, the extensor hallucis longus bowstrings laterally over the medial eminence (adding valgus and pronation), and the lateral head of flexor hallucis brevis further biases the hallux into valgus. The first MTPJ capsule becomes attenuated medially and contracted laterally — which is why a lateral release and a medially imbricated capsular repair are part of the correction. First metatarsal anatomy relevant to the scarf. The shaft has an oval cross-section with a thicker plantar cortex (the weight-bearing surface) and a thinner dorsal cortex; the head–shaft junction is the transition zone where the distal limb exits to avoid entering the joint. The metatarsal head blood supply enters via a nutrient artery at the mid-diaphysis medially and plantar metaphyseal branches at the neck — which is why subperiosteal, non-circumferential dissection is essential. Deformity measurement — what the angles tell you. The scarf's place in the ladder is defined by three weight-bearing radiographic angles and joint congruency:

Key evidence. The level-I randomised trial of Deenik (2007) showed the scarf and chevron gave equivalent HVA and IMA correction and AOFAS outcomes in mild-to-moderate deformity, with three partial metatarsal head necroses in the chevron group and four grade-1 CRPS cases in the scarf group. The 14-year follow-up of that cohort (Jeuken, 2016) found high radiographic recurrence in both groups but only one re-operation across the entire cohort and no clinical difference — an essential point for counselling patients about durability. The systematic review and meta-analysis of Smith (2012, 1351 participants) found the scarf gave a small, statistically significant additional 0.88° of IMA correction over the chevron, but only a weak recommendation was justified given the low-quality evidence. Together these underpin the message that procedure choice should be driven by deformity severity and TMT stability, not by a presumed large advantage of the scarf over the chevron.