Hallux Valgus

The deformity. Hallux valgus is lateral deviation of the hallux at the first metatarsophalangeal (MTP) joint together with medial deviation of the first metatarsal, which is metatarsus primus varus. The metatarsal head becomes prominent medially, and that prominence is the bunion; the joint subluxes progressively as the deformity advances. It is a bony malalignment, a contracture of the lateral soft tissues and an attenuation of the medial capsule and ligaments, all at once.

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Who. Pooled prevalence is 23% in adults aged 18-65 and 35.7% in those over 65, and it rises progressively with age. There is a 90% female predominance, and the pooled prevalence in the Nix meta-analysis was 30% in women against 13% in men. The worldwide picture is in the Evidence Base; the regional figures are on the map below.

Intrinsic risk factors. The deformity is familial in 60-70%, inherited as an autosomal dominant trait with incomplete penetrance. Female sex predisposes through a hormonal influence on ligament laxity, and foot shape contributes: pes planus, pronation, first ray hypermobility and a long first metatarsal. Neuromuscular disease (cerebral palsy, Charcot-Marie-Tooth disease, stroke) produces it through muscle imbalance.

Extrinsic risk factors. Inflammatory arthritis (rheumatoid, psoriatic), the hypermobility syndromes (Ehlers-Danlos, Marfan) and obesity, which increases forefoot loading. Footwear belongs on this list with a caveat that examiners like to test: high heels and a narrow toe box exacerbate symptoms in a predisposed foot but do not cause the deformity. Genetic and biomechanical factors are primary, and societies with barefoot populations have a similar prevalence.

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The first ray. The first metatarsal is thicker and shorter than the lesser metatarsals. It articulates proximally with the medial cuneiform at the tarsometatarsal (TMT) joint and distally with the proximal phalanx at the MTP joint, and beneath its head lie the medial (tibial) and lateral (fibular) sesamoids within the flexor hallucis brevis tendon. The first metatarsal and hallux carry 50% of forefoot load during gait.

The soft tissues. The medial capsule attenuates as the deformity progresses. Adductor hallucis pulls the proximal phalanx laterally; abductor hallucis is the medial stabiliser. The plantar plate forms the sesamoid sling and acts as a windlass.

Blood supply. The first metatarsal head is fed by the dorsal metatarsal artery, entering dorsomedially, the plantar metatarsal artery, entering plantarly, and a nutrient artery at mid-shaft. Extensive soft tissue stripping, especially combined dorsal and plantar dissection, can devascularise the head. Limit the dissection and preserve the periosteum.

The vicious cycle. Hypermobility of the first TMT joint allows progressive varus drift of the metatarsal, and each step then worsens the deformity:

1. First TMT hypermobility or pes planus produces metatarsus primus varus
2. Adductor hallucis pulls the hallux laterally and the medial capsule stretches
3. The sesamoids stay tethered to the lesser metatarsals while the first metatarsal drifts medially, so they sublux relative to the head
4. Each step increases the valgus force, and abductor hallucis becomes a plantarflexor

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The deformity is described in three ways, and each answers a different question. The weight-bearing angles grade it and choose the osteotomy; the Manchester scale grades what the patient sees; joint congruity decides whether the soft tissues need releasing.

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Radiographic (HVA/IMA)Clinical (Manchester Scale)Joint Congruity

Radiographic Classification (Gold Standard)

Everything is measured on a weight-bearing AP foot radiograph.

Normal

HVA

Under 15°

IMA

Under 9°

DMAA

Under 10°

Sesamoid Subluxation

Grade 0-1

Mild

HVA

15-25°

IMA

9-13°

DMAA

10-15°

Sesamoid Subluxation

Grade 1-2

Moderate

HVA

25-40°

IMA

13-20°

DMAA

15-25°

Sesamoid Subluxation

Grade 2-3

Severe

HVA

Over 40°

IMA

Over 20°

DMAA

Over 25°

Sesamoid Subluxation

Grade 3-4

Severity	HVA	IMA	DMAA	Sesamoid Subluxation
Normal	Under 15°	Under 9°	Under 10°	Grade 0-1
Mild	15-25°	9-13°	10-15°	Grade 1-2
Moderate	25-40°	13-20°	15-25°	Grade 2-3
Severe	Over 40°	Over 20°	Over 25°	Grade 3-4

The measurements. The hallux valgus angle (HVA) lies between the axes of the first metatarsal and the proximal phalanx, and the intermetatarsal angle (IMA) between the axes of the first and second metatarsals. The distal metatarsal articular angle (DMAA) is the angle of the first metatarsal articular surface to the metatarsal axis. Sesamoid position is graded from 1, normal, to 4, complete lateral subluxation.

Why the IMA matters most. It is the angles, not the size of the bunion or the medial eminence, that drive the choice between a distal, a diaphyseal and a basal or fusion procedure, and the IMA is the primary determinant. An IMA under 13 degrees can be corrected distally with a chevron; 13-20 degrees typically needs a mid-shaft scarf rather than a distal cut; over 20 degrees needs a proximal osteotomy or a Lapidus.

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Manchester Scale (Clinical Assessment)

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A patient-reported visual grading. It is simple and reproducible, it correlates with patient satisfaction, and it is used in research and outcome assessment; clinically it helps to separate the foot that needs conservative care from the one that needs an operation.

1

Clinical Appearance

No visible deformity

Patient Symptoms

Asymptomatic

Treatment

Observation

2

Clinical Appearance

Mild bunion, toes straight

Patient Symptoms

Shoe pressure, mild pain

Treatment

Conservative or distal osteotomy

3

Clinical Appearance

Moderate bunion, overlapping toes

Patient Symptoms

Significant pain, difficulty with shoes

Treatment

Scarf or proximal osteotomy

4

Clinical Appearance

Severe deformity, fixed subluxation

Patient Symptoms

Disabling pain, cannot wear shoes

Treatment

Lapidus or MTP fusion

Grade	Clinical Appearance	Patient Symptoms	Treatment
1	No visible deformity	Asymptomatic	Observation
2	Mild bunion, toes straight	Shoe pressure, mild pain	Conservative or distal osteotomy
3	Moderate bunion, overlapping toes	Significant pain, difficulty with shoes	Scarf or proximal osteotomy
4	Severe deformity, fixed subluxation	Disabling pain, cannot wear shoes	Lapidus or MTP fusion

Joint Congruity Classification

Congruent. On the weight-bearing AP radiograph the articular surfaces stay parallel under valgus stress. The deformity lies at the metatarsal level, as metatarsus primus varus, and a lateral soft tissue release is usually not required: an osteotomy alone may suffice.

Incongruent. The joint is subluxed and the articular surfaces have lost their parallelism, so the deformity involves both bone and soft tissue. A lateral capsular release with adductor hallucis tenotomy is always performed alongside the osteotomy, to prevent recurrence.

History. Ask where it hurts, because the answer separates the medial bunion from MTP joint pain, from the interphalangeal joint and from the lesser toes, where pain means transfer. Then establish what the deformity costs the patient: shoe wear, walking distance and sport, how fast it is progressing and what has already been tried, the heel height and toe box of their usual shoes, and the standing and walking demands of their work. Inflammatory arthritis and neuromuscular disease are the past history that matters.

Examination. Look for the bunion prominence, callus and lesser toe deformity. Feel for medial tenderness, first TMT mobility and MTP crepitus. Move the MTP joint (normal dorsiflexion is 70-80°) and check the alignment of the interphalangeal joint. Watch the gait for pronation and hallux push-off, use the Coleman block test if there is a pes planus, and record sensation and pulses, which matter most in the diabetic foot.

First ray mobility test. Hypermobility changes the operation, so test for it:

1. Grasp the second to fifth metatarsal heads with one hand, dorsal and plantar, to stabilise them
2. With the other hand, dorsiflex and plantarflex the first metatarsal head, and compare with the other foot
3. Grade it: 5-8mm of motion is normal; over 10mm is hypermobile; under 5mm is stiff, from arthritis or compensation

Why hypermobility matters. If the first TMT joint is hypermobile, an osteotomy alone will fail, because the instability at the TMT joint will pull the deformity back. The Lapidus procedure fuses the joint and addresses the pathology at its source, which is why hypermobility is an indication for Lapidus over osteotomy.

Sesamoids. Tenderness on palpation suggests sesamoiditis or arthritis. Their position is graded on the radiograph. They should reduce under a manual varus stress on the hallux; if they stay fixed, the lateral soft tissue contracture is severe.

Differential diagnosis. Not every painful medial forefoot is a simple bunion, and several of the alternatives change management:

Radiographs. Weight-bearing AP, lateral and oblique views. The AP is where the deformity is measured, and the list of what to read from it is the pre-operative plan:

• HVA
• IMA
• DMAA
• Sesamoid position, grade 1-4
• Joint congruity
• Arthritis at the MTP and TMT joints

The lateral. Compare the length of the first metatarsal with the second: normal is equal or 1-2mm longer. Look for metatarsus elevatus, which signals a risk of transfer metatarsalgia, and for pes planus and midfoot arthritis.

Why weight-bearing. Angles measured on non-weight-bearing films underestimate the deformity: the IMA and HVA both fall by 20-30% when the foot is unloaded. Always plan surgery on weight-bearing films.

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MRI is selective, not routine: suspected AVN, sesamoid pathology (bipartite versus fracture), a plantar plate tear, or assessment of MTP arthritis.

CT is rare: complex revision cases, assessment of TMT arthritis before a Lapidus, and evaluation of a postoperative nonunion.

Footwear. A wide toe box to accommodate the bunion, a low heel (under 2cm) to reduce forefoot pressure, soft uppers to minimise friction, and no pointed toes or constrictive shoes.

Orthoses and padding. Bunion pads over the medial eminence, toe spacers to separate the hallux from the second toe, metatarsal pads if there is transfer metatarsalgia, and custom orthotics for pes planus and pronation control. These measures provide symptomatic relief and may delay surgery. They do not correct the deformity or prevent its progression, and surgery is the only corrective treatment; set realistic expectations.

Adjuncts. NSAIDs for acute flares, paracetamol for background pain, and topical NSAIDs for localised bunion tenderness. Physiotherapy stretches adductor hallucis, and gastrocnemius if the heel cord is tight, and strengthens the intrinsic foot muscles and abductor hallucis; the evidence that it corrects the deformity is limited, but it may reduce symptoms. A corticosteroid injection into the MTP joint for synovitis gives temporary relief over 3-6 months; repeated injections risk cartilage damage, and it is not curative.

These are adjuncts, chosen for the symptom in front of you, not a course to work through: analgesia for pain, therapy for a tight heel cord or weak intrinsics, injection for genuine synovitis. None of them changes the deformity, because hallux valgus is a structural malalignment and no conservative measure realigns the first ray. Say that plainly when consenting, because a patient who believes the splint or the exercises will straighten the toe will judge the whole treatment a failure.

Indications for surgery.

1. Pain refractory to conservative measures, after a minimum of 3-6 months
2. Functional limitation affecting daily activities or employment
3. Progressive deformity with difficulty wearing any shoes
4. Secondary pathology: transfer metatarsalgia, lesser toe deformity, intractable plantar keratosis

Not an indication. Cosmetic concern alone, which carries a high complication risk and patient dissatisfaction; an asymptomatic deformity, however severe it looks on the radiograph; and unrealistic expectations for shoe wear.

Algorithm

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Symptoms first, severity second. A painless deformity, however ugly, is managed with footwear advice and observation. A symptomatic foot gets its conservative trial of a wide toe box, orthoses, activity modification and analgesia, and only the foot that stays painful, limits shoe wear or progresses moves to surgery. The operation is then chosen on the weight-bearing angles and joint congruity, and the IMA is the deciding number:

Mild deformity: chevron. HVA 15-25 degrees, IMA under 13 degrees and a congruent joint. Weight-bearing films confirm the IMA, and congruity decides whether a lateral release is added. A distal V-shaped cut is translated laterally to correct the IMA. After heel weight-bearing in a postoperative shoe for 6 weeks the patient progresses to regular shoes at 6 weeks and full activity at 3 months. Its virtues are a fast recovery, inherent stability and minimal shortening, and it suits the mild to moderate deformity with good bone quality.

Moderate deformity: scarf. HVA 25-40 degrees, IMA 13-20 degrees, often an incongruent joint that needs a lateral release. Most patients with a moderate deformity fail conservative care. A mid-shaft Z-cut is translated laterally. After heel weight-bearing in a postoperative shoe for 6 weeks, full weight-bearing begins at 6 weeks, regular shoes at 6-8 weeks and sport at 3-4 months. It is the workhorse: the most versatile procedure, correcting both HVA and IMA with stable fixation.

Severe deformity or hypermobility: Lapidus. HVA over 40 degrees, IMA over 20 degrees, or first TMT hypermobility of over 10mm. Consider it too for recurrence after a previous osteotomy, and get a CT if TMT arthritis is suspected. The TMT joint is fused. It addresses hypermobility, corrects the IMA powerfully and has the lowest recurrence; the price is the risk of nonunion, a longer recovery and the stiffness of a fusion.

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Lateral soft tissue release. Added when the MTP joint is incongruent, with subluxation on the radiograph: adductor hallucis tenotomy and lateral capsular release through a separate incision in the first web space, so that the hallux can reduce to neutral and the correction holds. The steps are in the chevron technique.

Akin osteotomy. Added for hallux valgus interphalangeus, where the distal phalanx itself deviates. A medial closing wedge is taken from the proximal phalanx and fixed with a staple or screw to straighten the hallux. Both adjuncts optimise the correction, and neither is a substitute for the osteotomy that realigns the metatarsal.

Juvenile and adolescent hallux valgus. Hallux valgus in the skeletally immature is a distinct problem and a classic exam trap. It is more often familial, frequently bilateral and congruent, and characteristically has a high DMAA: the deformity lies in the orientation of the distal metatarsal articular surface rather than at a subluxed joint. The cardinal rule is to delay surgery until skeletal maturity wherever possible. Operating across an open physis risks growth disturbance and, more importantly, recurrence rates are far higher in juveniles than in adults, so conservative measures and reassurance are first-line and surgery is reserved for genuinely painful, functionally limiting deformity.

When surgery is required, the plan must correct the DMAA, with a distal medial closing-wedge or biplanar osteotomy such as a Reverdin-type cut or a biplanar chevron, rather than simply reducing the IMA: correcting the IMA on a congruent joint with a high DMAA creates an incongruent joint and drives recurrence. Address true first-ray hypermobility on its merits, but be cautious about TMT fusion before the physis has closed.

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Chevron OsteotomyScarf OsteotomyLapidus ProcedureMTP Fusion

Chevron (Distal Metatarsal) Osteotomy

For the mild to moderate deformity with an IMA under 13 degrees and a congruent joint. The V-shape is inherently stable, it shortens little, and recovery is fast.

Surgical Steps

Step 1Positioning and Preparation

Supine with a thigh tourniquet and the lower leg draped free, under ankle block or general anaesthesia.

Step 2Medial Incision

A 4-5cm longitudinal incision over the medial MTP joint, centred on the metatarsal head, deepened to the capsule. The medial dorsal cutaneous nerve runs just dorsal to the incision: identify it and protect it.

Step 3Capsulotomy

A longitudinal capsulotomy preserving dorsal and plantar flaps exposes the metatarsal head and medial eminence. Measure the depth of the osteotomy, aiming for a 60-70° V.

Step 4Medial Eminence Resection

Resect the medial prominence with a sagittal saw flush with the medial metatarsal shaft, avoiding over-resection, and smooth the edges with a rongeur.

Step 5Chevron Osteotomy

Place the apex at the centre of the metatarsal head on the plantar view, with equal dorsal and plantar arms at 60-70°. Complete the cut with the sagittal saw and irrigate to prevent thermal necrosis.

Step 6Lateral Translation

Translate the distal fragment laterally by 3-5mm, aiming for an IMA under 9 degrees, and check sesamoid reduction under fluoroscopy. The V interlocks and gives the osteotomy its stability, but translation should be limited to 50% of the metatarsal width, which is that 3-5mm: over-translation risks fracture of the metatarsal head and AVN.

Step 7Fixation

A temporary 1.6mm K-wire from the medial eminence into the metatarsal shaft, then a 2.0-2.7mm cannulated or solid screw perpendicular to the osteotomy. Check stability and that the fragment has not rotated.

Step 8Lateral Release (if needed)

If the joint is incongruent, a separate 1cm incision in the first web space. Divide the adductor hallucis tendon (identified by pulling the hallux medially), release the lateral capsule with a beaver blade, and confirm that the hallux reduces to neutral.

Step 9Closure

Close the medial capsule with 2-0 absorbable suture, plicating it slightly to tighten. Skin with 3-0 nylon, interrupted or subcuticular, and a soft bandage holding the toe in neutral alignment.

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Scarf (Mid-Shaft Metatarsal) Osteotomy

For the moderate to severe deformity with an IMA of 13-20 degrees, and versatile enough for most cases. It corrects the HVA and the IMA, takes stable fixation, and lets the surgeon adjust length.

Surgical Steps

Step 1Positioning

Supine with a thigh tourniquet, standard sterile preparation and draping.

Step 2Medial Incision

A 6-7cm longitudinal incision over the medial first metatarsal, from the base to the MTP joint. Identify the medial dorsal cutaneous nerve and retract it.

Step 3Capsulotomy and Exposure

A longitudinal capsular incision preserving the flaps, then expose the entire first metatarsal shaft from base to head and mark the planned osteotomy with methylene blue.

Step 4Scarf Osteotomy Cuts

The horizontal limb is a longitudinal cut in the sagittal plane from the proximal to the distal metaphysis, avoiding the TMT and MTP joints. A perpendicular proximal vertical limb at the proximal end and a perpendicular distal vertical limb at the distal end complete the Z: three cuts.

Step 5Fragment Translation

Translate the distal (plantar) fragment laterally to correct the IMA, typically by 5-8mm. Length can be shortened or lengthened by translating anteriorly or posteriorly, and any pronation is corrected by plantar rotation. Confirm alignment and sesamoid reduction on fluoroscopy.

Step 6Fixation

Two 2.7-3.5mm cortical or cannulated screws perpendicular to the osteotomy, one proximal and one distal, with lag technique if possible. There should be no motion at the osteotomy.

Step 7Medial Eminence Resection

Resect the medial prominence with the sagittal saw after the osteotomy, which prevents over-resection, and smooth the sharp edges.

Step 8Lateral Release

If needed, adductor tenotomy and lateral capsular release through a separate incision, as for the chevron.

Step 9Closure

Close the capsule with slight medial plication, skin with 3-0 nylon, and a soft bandage with the hallux in neutral.

Troughing Risk with Scarf

Troughing is fracture of the plantar cortex during the saw cuts, and it leaves the osteotomy unstable. The plantar cortex must remain intact: use the oscillating saw carefully and check the cortex before completing the cuts. If troughing occurs, add a plantar screw or change to a Lapidus.

Lapidus (First TMT Arthrodesis)

For the severe deformity with an IMA over 20 degrees, first TMT hypermobility, recurrent deformity and TMT arthritis. It addresses the instability at its source and corrects the IMA powerfully.

Surgical Steps

Step 1Positioning

Supine with a thigh tourniquet, the C-arm positioned for AP and lateral views of the foot.

Step 2Medial Incision

A 5-6cm longitudinal incision over the first TMT joint, between the base of the first metatarsal and the medial cuneiform. Identify extensor hallucis longus and retract it dorsally.

Step 3Joint Exposure

Incise the capsule and elevate it dorsally and plantarly to expose the joint, preserving the dorsal and plantar ligaments to the second metatarsal so as not to destabilise it. Mark the joint line with a K-wire under fluoroscopy.

Step 4Joint Preparation

Remove the cartilage from the metatarsal base and the cuneiform with curved osteotomes or a rongeur, preserving the subchondral bone but leaving a raw bleeding surface, then fenestrate it with multiple 1.5mm drill holes to promote fusion.

Step 5Reduction and Alignment

Adduct the first metatarsal to correct the IMA, aiming for under 9 degrees. Maintain length, and plantarflex slightly to match the second metatarsal so as to prevent metatarsus elevatus. Check on AP and lateral fluoroscopy.

Step 6Fixation

A low-profile medial locking plate of 4-6 holes spanning the joint, with 3.5mm cortical or locking screws, 2-3 in the metatarsal and 2-3 in the cuneiform. Crossed 2.7-3.5mm lag screws are the alternative if the bone quality is good. Compress the fusion site; there should be no motion.

Step 7Lateral Release and Eminence Resection

Adductor tenotomy through a separate incision if needed, and resection of the medial prominence of the metatarsal base if it is prominent.

Step 8Closure

Close the capsule over the plate, skin with 3-0 nylon, and a below-knee splint or boot with the toe in neutral.

First MTP Joint Arthrodesis

For severe MTP arthritis (hallux rigidus with valgus), failed previous surgery, the severe deformity in a low-demand elderly patient, and neuromuscular disease. It eliminates pain at the cost of MTP motion, so the position of the fusion decides the result.

The position. 10-15 degrees of valgus and 15-20 degrees of dorsiflexion relative to the floor, which lets the toe clear in the swing phase.

Surgical Steps

Step 1Positioning

Supine with a thigh tourniquet, standard foot preparation and draping.

Step 2Dorsomedial Incision

A 5cm dorsomedial incision over the MTP joint, protecting the dorsomedial cutaneous nerve, which runs parallel, and exposing the joint capsule.

Step 3Joint Resection

Remove the cartilage from the metatarsal head and the base of the proximal phalanx with perpendicular sagittal saw cuts, creating flat, congruent surfaces, and fenestrate the subchondral bone with a 1.5mm drill.

Step 4Alignment

Set the hallux in 10-15 degrees of valgus, aligned with the second toe, and 15-20 degrees of dorsiflexion, about 1cm above the floor when standing, with neutral rotation so that the toenail points up. Check clinically and on fluoroscopy.

Step 5Fixation

A dorsal contoured locking plate of 6-8 holes spanning the joint with 2.7-3.5mm locking screws. Crossed lag screws are the alternative, less rigid and with a higher nonunion risk. Ensure apposition at the fusion site.

Step 6Closure

Close the capsule over the plate, skin with 3-0 nylon, and a below-knee splint or boot.

MTP Fusion Position Critical

Malpositioning is the most common cause of patient dissatisfaction. Too much dorsiflexion and the patient stubs the toe; too little and push-off is difficult. Too much valgus crowds the second toe; too little loads the lateral border of the foot. Aim for 15 degrees of dorsiflexion and 10 degrees of valgus.

Minimally invasive (percutaneous) surgery. Percutaneous surgery has become a mainstream alternative to open osteotomy, and examiners increasingly ask about it. The dominant modern technique is the MICA (minimally invasive chevron-Akin): through tiny stab incisions a high-torque, low-speed burr makes an extra-articular distal metatarsal osteotomy, the capital fragment is translated laterally and held with percutaneous screws, and a percutaneous Akin addresses the phalangeal component. The technique has evolved through generations: early first- and second-generation techniques were unfixed or held with a buried K-wire and had higher recurrence, whereas the current third- and fourth-generation, screw-fixed techniques are stable and reproducible.

The advantages are small scars, less soft-tissue stripping, less stiffness and good early pain scores, with RCT and meta-analysis data showing radiographic correction and patient outcomes broadly comparable to open chevron or scarf. The caveats are a genuine learning curve, thermal necrosis if the burr is not irrigated and cooled, hardware-related symptoms, and the same recurrence drivers as open surgery: under-correction of the IMA and unaddressed hypermobility. Minimally invasive surgery does not abolish the algorithm; gross first-ray hypermobility or a very high IMA still points toward a Lapidus.

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Transfer metatarsalgia. Shortening the first ray by more than 3mm, or leaving it elevated, transfers load to the lesser metatarsal heads. It is the hallmark complication of bunion surgery, and the guard against it is at the osteotomy: keep the length and do not elevate the ray.

Stiffness, pain and hardware. Stiffness can follow overcorrection or adhesions as well as arthritis and an aggressive rehabilitation. Persistent pain despite a good correction occurs in 5-10%. Fixation can fail by nonunion or malunion, and hardware can irritate.

Nonunion after Lapidus. The rate of 5-10% is higher than for the osteotomies because this is a fusion; smoking, poor bone quality, inadequate fixation and non-compliance with weight-bearing restrictions raise it. Suspect it when there is pain, persistent motion at the TMT joint or no bridging bone at 12 weeks, and confirm it with a CT. An asymptomatic nonunion is observed; a symptomatic one is managed with prolonged immobilisation, bone graft (autograft from the calcaneus or iliac crest) and revision fixation. The 5-10% figure is a broad one: the Waehner meta-analysis in the Evidence Base found the rate fixation-dependent, 0.7% with plantar plating, 1.4% with dorsomedial plating and 5.3% with screws alone, and plantar plating on the tension side supported earlier weight-bearing with the lowest nonunion.

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Predictors of a poor outcome. Dissatisfaction is associated with:

• Unrealistic expectations, the cosmetic-surgery mentality
• Undercorrection of the IMA, which leads to recurrence
• Overcorrection, which leads to hallux varus and transfer metatarsalgia
• A pre-existing lesser toe deformity that was not addressed at surgery
• Poor bone quality, from osteoporosis or metabolic bone disease
• Smoking, through nonunion and wound complications

Procedure-specific outcomes. The Clemente meta-analysis in the Evidence Base is worth reading beside this table: on pooled data the distal chevron corrected the IMA marginally better than the scarf, so the scarf's versatility is a reason to choose it, and a claim of greater correction is not.

Global Epidemiology

Hallux valgus is among the most common forefoot deformities worldwide, with a consistent female predominance and a strong rise in prevalence with age. Regional differences (highest in Oceania and Asia, lowest reported in Africa) reflect both true variation and heterogeneity in diagnostic criteria.

Guidelines & Consensus, Side by Side

There is no single high-level international clinical guideline that mandates a specific osteotomy; major bodies converge on principles rather than a named procedure, reflecting the Cochrane finding that no technique is uniformly superior.

Registry & Procedure-Volume Evidence

Global Practice Variation

Peri-operative Standards (Globally Accepted)

• Antibiotic prophylaxis: single pre-operative dose of a first-generation cephalosporin (e.g. cefazolin) at induction for clean forefoot surgery
• VTE prophylaxis: routine pharmacological prophylaxis not indicated for isolated forefoot osteotomy in low-risk patients; risk-stratify and consider it for prolonged immobilisation/non-weight-bearing regimens (e.g. Lapidus)
• Surgical-site infection target under 2% for clean elective foot surgery