High Yield Overview

HALLUX VALGUS CORRECTION - COMPREHENSIVE DECISION-MAKING GUIDE (CHEVRON, SCARF, LAPIDUS)

Varies by procedure: Medial longitudinal for Chevron/Scarf, dorsomedial over TMT for Lapidus, all protect dorsomedial cutaneous nerve | advanced

Critical Danger Structures - 5 Key Zones

Danger 1: Dorsomedial Cutaneous Nerve

LOCATION: Variable anatomy, multiple branches, 2-5mm dorsal to typical medial incision line

PROTECTION: Sharp dissection with early identification, vessel loops for retraction, gentle handling only, avoid cautery near nerve

Danger 2: Medial Plantar Digital Nerve

LOCATION: 8-10mm plantar to MTP joint line at medial eminence, travels with plantar vessels

PROTECTION: Limit eminence resection to 3-4mm, stay in line with shaft, avoid extending plantarly with saw

Danger 3: Lateral Digital Neurovascular Bundle

LOCATION: 5mm lateral to lateral MTP capsule, runs between flexor and extensor tendons to hallux

PROTECTION: Incremental lateral release under direct vision, palpate dorsalis pedis pulse, release only if sesamoids unreduced

Danger 4: Dorsalis Pedis Artery (Lapidus)

LOCATION: 15-20mm lateral to TMT joint between EHL and EHB tendons, gives deep plantar branch

PROTECTION: Stay medial with TMT incision, identify EHL as landmark, subperiosteal dissection only, palpate pulse before/after

Danger 5: Metatarsal Head Blood Supply

LOCATION: Dorsal metaphyseal vessels enter dorsally, nutrient artery midshaft, plantar periosteal supply critical

PROTECTION: Minimal soft tissue stripping (Scarf higher risk), keep osteotomy apex at dome (Chevron), limit translation to 50-70% width

Mnemonic

CHEVRONCHEVRON - Indications and Technique

Mnemonic

SCARF SAFESCARF SAFE - Avoiding Troughing Complication

Procedure Selection Framework

Primary Decision: Measure Deformity Severity

Weight-bearing AP radiographs MANDATORY:

Critical Yield Data

Decision Tree

MILD DEFORMITY (IMA less than 13°, HVA less than 30°):

CHEVRON first choice
Congruent joint required
Good bone quality
Older, lower demand patients
Sesamoid grade 1-2

MODERATE-SEVERE DEFORMITY (IMA 13-18°, HVA 30-40°):

SCARF first choice
Most versatile - translation, rotation, shortening, plantarflexion
Allows up to 70% translation (vs 50% Chevron)
Any age, activity level
Sesamoid grade 2-3

SEVERE DEFORMITY (IMA greater than 18-20°):

LAPIDUS required
Corrects at apex of deformity (TMT)
Eliminates TMT mobility
Definitive correction
Lowest recurrence rate (less than 5%)

TMT Hypermobility Assessment - CRITICAL

Clinical Test:

Stabilize hindfoot and midfoot with one hand
Grasp 1st metatarsal head with other hand
Dorsally and plantarly translate 1st MT
Measure excursion

Interpretation:

Normal: less than 5mm translation
Borderline: 5-9mm
ABNORMAL: greater than 9mm = LAPIDUS INDICATION regardless of IMA

Rationale: Hypermobility allows 1st MT to drift into varus postoperatively - distal osteotomies (Chevron/Scarf) will fail from recurrent instability. Lapidus fuses TMT eliminating mobility.

Additional Lapidus Indications

Metatarsus primus varus (structural deformity at TMT level)
Revision surgery after failed Chevron/Scarf
Young active patients wanting definitive correction
MTP joint varus (lateral joint space widening)
TMT arthritis (relative indication - already degenerative)

Sesamoid Position Grading

Grade 1: Normal position under metatarsal head Grade 2: Less than 50% lateral subluxation Grade 3: Greater than 50% lateral subluxation - lateral release likely needed Grade 4: Complete lateral subluxation - lateral release required

Exam Pearl

Examiner Expects: "My decision algorithm: First measure IMA on weight-bearing AP - this drives procedure selection. IMA less than 13° = Chevron if congruent joint and good bone. IMA 13-18° = Scarf for versatility. IMA greater than 18° = Lapidus. Then I assess TMT hypermobility clinically - greater than 9mm translation is absolute Lapidus indication regardless of IMA. Finally consider patient factors - revision, young active, or metatarsus primus varus favor Lapidus. Sesamoid position determines if lateral release needed."

Positioning and Preparation

Patient Position: Supine with foot at end of table, small bump under ipsilateral hip for external rotation, ankle block or general anesthesia, ankle or thigh tourniquet (250mmHg)

Surgical Approach: Varies by procedure: Medial longitudinal for Chevron/Scarf, dorsomedial over TMT for Lapidus, all protect dorsomedial cutaneous nerve

Incision: Medial longitudinal for Chevron (3-4cm) and Scarf (6-8cm), dorsomedial for Lapidus (4-5cm)

Operative Technique

Step 1: Decision-Making Framework - CRITICAL FIRST STEP

Decision-Making Framework - CRITICAL FIRST STEP: PROCEDURE SELECTION based on: (1) SEVERITY: Measure HVA (hallux valgus angle) and IMA (intermetatarsal angle) on weight-bearing AP X-ray. (2) TMT MOBILITY: Assess 1st TMT hypermobility clinically (greater than 9mm dorsoplantar translation abnormal) and consider on lateral stress X-ray. (3) DEFORMITY LOCATION: Metatarsus primus varus vs MTP joint pathology. (4) PATIENT FACTORS: Age, activity, bone quality, expectations. CHEVRON: Mild (HVA 15-30°, IMA 10-13°), congruent joint, good bone. SCARF: Moderate-severe (HVA 30-40°, IMA 13-18°), need multi-planar correction. LAPIDUS: Severe IMA greater than 18-20°, TMT hypermobility greater than 9mm, metatarsus primus varus, revision, young active patient.

Exam Pearl

Technical Tip: EXAM KEY: 'Decision tree: MILD deformity (IMA less than 13°) = Chevron. MODERATE-SEVERE (IMA 13-18°) = Scarf. SEVERE (IMA greater than 18°) OR hypermobile TMT = Lapidus. TMT hypermobility test: stabilize midfoot, dorsoplantarly translate 1st MT - greater than 9mm abnormal. Lapidus corrects at APEX of deformity (TMT), Chevron/Scarf correct distally.'

Dangers at this step

Wrong procedure for severity (Chevron for severe = undercorrection/recurrence)
Missing TMT hypermobility (distal procedure fails, recurrence)
Not assessing bone quality (osteoporosis affects fixation choice)

Step 2: Preoperative Planning & Marking

Preoperative Planning & Marking: Weight-bearing radiographs MANDATORY: AP, lateral, oblique. Measure: HVA (normal less than 15°), IMA (normal less than 9°), DMAA (distal metatarsal articular angle, normal less than 10°), DASA (distal articular set angle of phalanx). Assess: sesamoid position (grade 1-4 lateral subluxation), joint congruency, TMT arthritis, lesser metatarsal lengths. Clinical: ROM, severity of bunion, lesser toe deformities, neurovascular status. Mark anatomy: first MTP joint line, metatarsal shaft (Scarf), TMT joint (Lapidus), dorsomedial nerve course.

Exam Pearl

Technical Tip: EXAM KEY: 'Weight-bearing X-rays essential - non-weight bearing underestimates deformity. Key measurements: HVA, IMA, DMAA. Sesamoid grading: 1 (normal under MT head), 2 (less than 50% subluxed), 3 (greater than 50% subluxed), 4 (completely lateral to ridge). Grade 3-4 need lateral release. Assess lesser MTs - if short, risk transfer metatarsalgia.'

Dangers at this step

Non-weight bearing films = underestimate deformity
Missing high DMAA (may need rotational correction)
Not assessing TMT joint (may have arthritis)

Step 3: Surgical Approach & Nerve Protection

Surgical Approach & Nerve Protection: CHEVRON/SCARF: Medial longitudinal incision 3-4cm (Chevron) or 6-8cm (Scarf) from mid-proximal phalanx to mid-metatarsal, 2-3mm dorsal to joint line. LAPIDUS: Dorsomedial 4-5cm over TMT joint, staying medial to EHL. ALL approaches: Sharp dissection, identify dorsomedial cutaneous nerve early (variable anatomy, often multiple branches), protect with vessel loops, gentle retraction only. Avoid cautery near nerve. Develop plane to capsule.

Exam Pearl

Technical Tip: EXAM KEY: 'DORSOMEDIAL CUTANEOUS NERVE most at risk across all procedures - 5-10% injury rate. I identify EARLY with sharp dissection, protect with vessel loops, NO excessive traction or cautery. LONGITUDINAL incisions protect nerves better than transverse. Medial approach (Chevron/Scarf) keeps lateral neurovascular bundle safe.'

Dangers at this step

Nerve injury - painful neuroma requiring revision
Aggressive cautery - nerve injury
Inadequate exposure - technical difficulty

Step 4: Capsulotomy & Joint Exposure

Capsulotomy & Joint Exposure: CHEVRON: Inverted-L capsulotomy 3-4cm exposing metatarsal head/neck. SCARF: Extended inverted-L or linear capsulotomy entire metatarsal shaft length 6-8cm. LAPIDUS: T-shaped capsulotomy at TMT joint exposing dorsally and medially. ALL: Preserve capsular tissue for closure (soft tissue balance). Expose medial eminence. SCARF: Identify plantar cortex as guide for osteotomy orientation. LAPIDUS: Confirm TMT joint level with fluoroscopy if uncertain.

Exam Pearl

Technical Tip: EXAM KEY: 'Capsulotomy extent matches procedure: Chevron needs 3-4cm (head/neck only), Scarf needs 6-8cm (entire shaft for Z-osteotomy), Lapidus 4-5cm at TMT. I preserve capsule for later imbrication - addresses soft tissue laxity, maintains correction. For Scarf: plantar cortex identification CRITICAL for parallel horizontal cut.'

Dangers at this step

Excessive stripping - AVN risk (especially Scarf 1-2%)
Inadequate exposure for Scarf - cannot perform full Z
Wrong joint level for Lapidus (intercuneiform instead of TMT)

Step 5: Medial Eminence Resection

Medial Eminence Resection: ALL procedures: Remove medial eminence with sagittal saw in line with medial metatarsal shaft border. Typical resection 3-4mm. CRITICAL: Avoid over-resection which destabilizes sesamoids and increases hallux varus risk. Smooth edges with rongeur. Palpate plantarly to ensure no plantar prominence. Save bone as local graft if needed (especially Lapidus).

Exam Pearl

Technical Tip: EXAM KEY: 'Eminence resection 3-4mm in line with shaft - NOT more. Over-resection destabilizes sesamoid complex, increases varus risk significantly. I smooth edges and check no plantar step-off. For Lapidus, I save this bone as local graft option for TMT fusion.'

Dangers at this step

Over-resection - sesamoid instability, hallux varus
Plantar extension - medial plantar nerve injury
Thermal injury from saw - avascular necrosis

Step 6: Osteotomy Performance - PROCEDURE-SPECIFIC

Osteotomy Performance - PROCEDURE-SPECIFIC: CHEVRON: 60° V-shaped osteotomy through metatarsal head, apex at DOME (critical for stability), arms 8-10mm each, microsagittal saw. Translate capital fragment laterally 3-4mm (max 50% width), slight plantarflexion if needed. SCARF: Z-shaped three cuts - (1) Horizontal 2:1 dorsal:plantar ratio PARALLEL to plantar cortex 25-30mm length, (2) Proximal vertical exits dorsally 60°, (3) Distal vertical exits plantarly 60°. Translate laterally 5-8mm (up to 70% width), can rotate/shorten/plantarflex. LAPIDUS: Remove cartilage from TMT joint with flat cuts 2-3mm each surface maintaining parallel surfaces, curette to bleeding bone, minimize resection to preserve length.

Exam Pearl

Technical Tip: EXAM KEY: 'CHEVRON: V-apex at DOME = inherent stability. SCARF: 2:1 dorsal:plantar ratio CRITICAL - prevents troughing (most common error). Horizontal cut MUST be PARALLEL to plantar cortex. LAPIDUS: Flat parallel cuts with minimal bone removal less than 5mm total - excessive shortening = transfer metatarsalgia. SCARF allows most versatility (translate, rotate, shorten, plantarflex).'

Dangers at this step

CHEVRON: Apex too dorsal/plantar = instability, translation greater than 50% = AVN risk
SCARF: Non-parallel horizontal cut = TROUGHING/dorsiflexion malunion (5-10%), excessive translation greater than 70% = instability
LAPIDUS: Excessive resection greater than 5mm = shortening/transfer metatarsalgia, non-parallel surfaces = malunion

Step 7: Reduction & Provisional Fixation

Reduction & Provisional Fixation: CHEVRON/SCARF: Translate capital fragment laterally per plan. Impaction for stability. Check: sesamoid reduction, appropriate IMA correction, no rotational deformity, metatarsal length appropriate. Hold with K-wires or clamps. LAPIDUS: Reduce TMT joint bringing 1st MT lateral to correct IMA to less than 10°. CRITICAL: Avoid DORSIFLEXION (most common Lapidus error) - maintain neutral or slight plantarflexion. Check lateral fluoroscopy. Provisional K-wires maintain position.

Exam Pearl

Technical Tip: EXAM KEY: 'SESAMOID REDUCTION is critical endpoint for all - if sesamoids not reduced under MT head, need lateral release OR more correction. For LAPIDUS: DORSIFLEXION malunion is #1 error - MUST check lateral fluoroscopy, aim neutral or slight plantarflexion. Cuneiform is wider dorsally = naturally pushes into dorsiflexion if not careful.'

Dangers at this step

Unreduced sesamoids = high recurrence risk ALL procedures
LAPIDUS dorsiflexion = transfer metatarsalgia (most common error)
Overcorrection = hallux varus risk
Loss of reduction during definitive fixation

Step 8: Definitive Fixation - PROCEDURE-SPECIFIC

Definitive Fixation - PROCEDURE-SPECIFIC: CHEVRON: Single 2.0-2.5mm headless compression screw perpendicular to osteotomy. Lag technique for compression. Headless preferred (no removal needed). SCARF: TWO 2.5-3.0mm headless screws perpendicular to osteotomy - proximal first (control), then distal. Must be perpendicular for compression. LAPIDUS: Dorsomedial locking plate (gold standard, 5% nonunion) with 3+3 locking screws PLUS supplemental lag screw dorsal-to-plantar for compression. Plate provides angular stability, screw provides compression.

Exam Pearl

Technical Tip: EXAM KEY: 'CHEVRON: Single screw adequate - V-shape inherently stable. SCARF: TWO screws needed - longer osteotomy, prevent rotation. Both perpendicular to osteotomy for compression. LAPIDUS: Dorsomedial locking PLATE current gold standard (5% nonunion vs 10-15% screws alone). Supplemental lag screw adds compression. Headless screws avoid prominence/removal for all.'

Dangers at this step

Screws not perpendicular = loss of compression/correction
SCARF: Single screw = rotation/instability
LAPIDUS: Screws only without plate = higher nonunion (10-15%)
Screw prominence if not headless
Joint penetration
Fracture during insertion

Step 9: Fluoroscopic Confirmation & Assessment

Fluoroscopic Confirmation & Assessment: Mandatory intraoperative imaging: AP view - confirm IMA correction (less than 10° goal), sesamoid reduction, hardware position, osteotomy alignment. Lateral view - CRITICAL for Lapidus to rule out dorsiflexion, confirm 1st MT aligns with lesser rays, hardware position. Oblique view - overall alignment, no joint penetration. If ANY malposition: correct NOW before proceeding.

Exam Pearl

Technical Tip: EXAM KEY: 'Fluoroscopy MANDATORY for all procedures. Three views: AP (IMA correction, sesamoids), LATERAL (CRITICAL for Lapidus dorsiflexion check), oblique (overall). Cannot correct after closure - MUST confirm position before proceeding. For Lapidus: lateral view non-negotiable - dorsiflexion malunion devastating.'

Dangers at this step

Missing malposition before closure - revision needed
Lapidus: Missing dorsiflexion on lateral = transfer metatarsalgia
Accepting suboptimal correction - recurrence risk

Step 10: Lateral Soft Tissue Release (if indicated)

Lateral Soft Tissue Release (if indicated): Perform if sesamoids NOT reduced after bony correction. Through same medial incision if possible, or separate dorsal incision in 1st-2nd interspace. Release: lateral capsule sharply, adductor hallucis tendon from lateral base of proximal phalanx/lateral sesamoid. CRITICAL: PROTECT lateral digital neurovascular bundle 5mm lateral to capsule. Palpate for dorsalis pedis pulse. Gradual release, check sesamoid position incrementally.

Exam Pearl

Technical Tip: EXAM KEY: 'Lateral release if sesamoids unreduced - especially Grade 3-4 subluxation. I release lateral capsule and adductor hallucis. DANGER: Lateral digital neurovascular bundle is 5mm lateral to capsule - injury causes numbness, pain. I release incrementally, check sesamoid position after each cut. Aggressive release = varus risk.'

Dangers at this step

Lateral digital nerve injury (5mm from capsule) - permanent numbness
Vascular injury - hallux ischemia
Excessive release - hallux varus/instability
Incomplete release - persistent sesamoid subluxation

Step 11: Akin Osteotomy (adjunct if needed)

Akin Osteotomy (adjunct if needed): Add Akin if: (1) Residual HVA greater than 15° after metatarsal correction, (2) DASA greater than 10° (interphalangeal valgus), (3) To fine-tune final alignment. Medial-based closing wedge 2-3mm at proximal phalanx base. Remove small dorsomedial wedge with sagittal saw. Close wedge, fix with single 2.0mm screw or staple. Avoid overcorrection causing interphalangeal varus.

Exam Pearl

Technical Tip: EXAM KEY: 'Akin is common adjunct to Chevron/Scarf - adds 5-10° correction if needed. Medial closing wedge at phalanx base. Indications: residual HVA greater than 15°, high DASA/interphalangeal valgus. Careful not to overcorrect - interphalangeal varus cosmetically poor. Fix with screw or staple. Rarely needed with Lapidus as TMT correction usually sufficient.'

Dangers at this step

Overcorrection - interphalangeal varus deformity
IP joint stiffness from fixation
Inadequate fixation - loss of correction
Phalanx fracture

Step 12: Capsular Repair & Soft Tissue Balance

Capsular Repair & Soft Tissue Balance: Medial capsule REEFING (imbrication) critical for soft tissue balance. Overlap medial capsule - 'pants-over-vest' or 'vest-over-pants' technique. Balance tension: adequate to maintain correction but not causing stiffness. Absorbable sutures (2-0 Vicryl). This addresses medial laxity and helps maintain alignment. For Lapidus: repair capsule over TMT fusion if tissue sufficient.

Exam Pearl

Technical Tip: EXAM KEY: 'Medial capsule imbrication as important as bony correction - addresses soft tissue laxity. I overlap capsule with balanced tension. Too loose = recurrence from medial instability. Too tight = stiffness, overcorrection. This soft tissue component maintains long-term correction.'

Dangers at this step

Overtightening - stiffness (especially Chevron/Scarf), overcorrection
Inadequate reefing - recurrence from medial laxity
Loss of correction if capsule not balanced

Step 13: Wound Closure

Wound Closure: Subcutaneous layer with absorbable sutures (3-0 or 4-0 Vicryl). Skin: subcuticular with absorbable (4-0 Monocryl) or interrupted non-absorbable (4-0 nylon). Handle skin edges gently - compromised vascularity common in chronic bunions. Steri-strips for wound support.

Exam Pearl

Technical Tip: EXAM KEY: 'Gentle tissue handling during closure - bunion skin often has compromised vascularity. I use subcuticular absorbable for better cosmesis or interrupted nylon if tension concerns. Steri-strips support wound. Wound complications 5-10% across all procedures, higher in smokers/diabetics.'

Dangers at this step

Wound dehiscence (5-10% risk, higher in revision)
Skin necrosis from tension or poor vascularity
Hematoma from inadequate hemostasis
Infection (1-2% primary, higher revision)

Step 14: Dressing & Immobilization

Dressing & Immobilization: BUNION DRESSING: Gauze fluffed between 1st-2nd toes (prevents drift back to valgus), hallux maintained in corrected position with gauze padding around foot, compression wrap (not too tight - vascular compromise). CHEVRON/SCARF: Stiff-soled postoperative shoe for 6 weeks - heel and midfoot weight-bearing, NO forefoot loading. LAPIDUS: Below-knee cast or CAM boot NON-weight bearing 6 weeks, then protected weight-bearing boot 6 more weeks.

Exam Pearl

Technical Tip: EXAM KEY: 'Bunion dressing maintains correction: gauze between toes prevents valgus drift, compression controls swelling. CHEVRON/SCARF: heel WB in postop shoe 6 weeks protects osteotomy. LAPIDUS: NWB 6 weeks MANDATORY (fusion), then protected WB 6 weeks. Lapidus has LONGEST recovery - counsel patients preoperatively.'

Dangers at this step

Dressing too tight - vascular compromise, compartment syndrome (rare)
Inadequate immobilization - loss of correction, hardware failure
Early full weight-bearing - nonunion (Lapidus), fracture (Chevron/Scarf)

Step 15: Postoperative Protocol - PROCEDURE-SPECIFIC

Postoperative Protocol - PROCEDURE-SPECIFIC: CHEVRON/SCARF: Bunion dressing 2 weeks. Sutures 10-14 days. Heel WB in stiff shoe 6 weeks, NO forefoot loading. ROM exercises start 2-3 weeks. Transition supportive shoes 6-8 weeks. Normal shoes 8-12 weeks. X-ray 6 weeks confirms union. Full activity 3-4 months. LAPIDUS: NWB cast/boot 6 weeks. X-ray at 6 weeks - if healing, transition to WB boot 6 more weeks. Supportive shoes 12 weeks. Full activity 4-6 months. Union takes 3-4 months. Serial X-rays 6wks, 12wks, 6mo.

Exam Pearl

Technical Tip: EXAM KEY: 'Recovery timeline critical for patient counseling: CHEVRON/SCARF: 6 weeks protected WB, 8-12 weeks normal shoes, 3-4 months full activity. LAPIDUS: 6 weeks NWB, 12 weeks protected WB, 4-6 months full activity. Lapidus TWICE as long recovery - discuss preoperatively. All need X-ray at 6 weeks minimum to confirm healing.'

Dangers at this step

Early weight-bearing - hardware failure, loss of correction, nonunion (Lapidus)
Inadequate follow-up - missing complications
Patient non-compliance - poor outcomes

Post-operative Care

CHEVRON/SCARF: Bunion dressing 2 weeks, heel WB stiff shoe 6 weeks (NO forefoot), ROM start 2-3 weeks, regular shoes 8-12 weeks, full activity 3-4 months. LAPIDUS: NWB cast/boot 6 weeks, X-ray at 6 weeks, transition WB boot additional 6 weeks if healing, regular shoes 12 weeks, full activity 4-6 months. All: sutures 10-14 days, X-ray 6 weeks minimum, avoid high heels 6 months. Smoking cessation MANDATORY especially Lapidus.

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 45-year-old active female presents with painful hallux valgus. X-ray shows HVA 35°, IMA 16°. How do you decide between Chevron, Scarf, and Lapidus procedures?"

EXCEPTIONAL ANSWER

This is moderate-to-severe deformity best suited for Scarf osteotomy. My decision-making involves three key assessments: First, SEVERITY on weight-bearing radiographs - her IMA 16° and HVA 35° exceed Chevron indications (IMA less than 13°, HVA less than 30°) but are within Scarf range (IMA 13-18°, HVA 30-40°). Lapidus typically reserved for IMA greater than 18°. Second, I assess TMT STABILITY clinically - stabilize her midfoot and dorsoplantarly translate the 1st metatarsal. If greater than 9mm translation, this indicates hypermobility requiring Lapidus regardless of IMA. Normal is less than 5mm. Third, PATIENT FACTORS - at 45 and active, she's suitable for any procedure, but Scarf offers versatility with multiplanar correction and faster recovery than Lapidus (6 weeks vs 12 weeks protected weight-bearing). I also assess sesamoid position - Grade 3-4 subluxation would require lateral release. I measure DMAA to determine if rotational correction needed. For this patient, Scarf is ideal - provides adequate correction power, allows translation up to 70% width versus Chevron's 50%, and preserves TMT motion with shorter recovery than Lapidus.

VIVA SCENARIOStandard

EXAMINER

"You perform a Lapidus procedure and at 3 months the patient has severe 2nd metatarsal pain. X-ray shows the fusion is healing but the 1st MT appears elevated on lateral view. What happened and how do you manage this?"

EXCEPTIONAL ANSWER

This is dorsiflexion malunion of the Lapidus - the most common and devastating technical error. The patient has developed transfer metatarsalgia from 1st MT elevation causing overload of the 2nd/3rd metatarsals. What happened: During reduction, the 1st MT was inadvertently positioned in dorsiflexion rather than neutral/slight plantarflexion. The cuneiform has a trapezoid shape - wider dorsally than plantarly - which naturally creates a dorsiflexion tendency if not carefully controlled. This likely occurred from: inadequate attention to lateral fluoroscopy intraoperatively, plantar gapping during reduction, or failure to use a dorsal-to-plantar lag screw for plantarflexion compression. Management depends on severity: First, confirm with lateral weight-bearing X-ray comparing 1st MT to lesser rays - measure 1st MT declination angle. Conservative trial: metatarsal pads under 2nd/3rd MTs, rocker-bottom shoes, activity modification for 3-6 months. If conservative fails and symptoms persist: surgical correction with plantar-closing wedge osteotomy of 1st MT to plantarflex it OR Weil osteotomies of 2nd/3rd MTs to shorten/decompress them. Prevention is critical: MUST use lateral fluoroscopy intraoperatively, aim for neutral or 5-10° plantarflexion, ensure no plantar gapping, use supplemental lag screw dorsal-to-plantar for compression, and align 1st MT with lesser rays before final fixation.

VIVA SCENARIOStandard

EXAMINER

"You are performing a Scarf osteotomy. At the 6-week follow-up X-ray, you notice the capital fragment has 'sunk' dorsally creating a trough appearance. What is this complication, why does it occur, and how do you prevent it?"

EXCEPTIONAL ANSWER

This is 'troughing' - a dorsiflexion malunion specific to Scarf osteotomy where the capital fragment migrates dorsally into the shaft creating a characteristic 'trough' appearance. It occurs in 5-10% of Scarf procedures and causes transfer metatarsalgia from 1st MT elevation. The mechanism: Scarf is a Z-shaped osteotomy with horizontal and two vertical cuts. If the horizontal cut is NOT parallel to the plantar cortex, the geometry allows the capital fragment to rotate dorsally under load. Contributing factors: non-parallel horizontal cut orientation, inadequate impaction leaving gaps, insufficient fixation (single screw instead of two), excessive dorsal translation during reduction. Prevention requires five technical points: First, identify the plantar cortex BEFORE starting the osteotomy and use it as your reference - the horizontal cut MUST be parallel to this cortex. Second, maintain 2:1 dorsal:plantar ratio which keeps the cut in the dorsal two-thirds of bone providing mechanical support. Third, impaction of the capital fragment onto the shaft after translation to ensure good bone contact. Fourth, TWO screws perpendicular to the osteotomy - proximal screw first for control, then distal screw. Perpendicular orientation critical for compression. Single screw inadequate for rotational control. Fifth, intraoperative lateral fluoroscopy confirms no dorsiflexion before closure. The parallel horizontal cut is the single most important technical factor - if this is wrong, all other steps cannot prevent troughing.

Hallux Valgus Correction (Chevron/Scarf/Lapidus) - Exam Day Summary

High-Yield Exam Summary

References

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Barg A, Harmer JR, Presson AP, et al. Unfavorable outcomes following surgical treatment of hallux valgus deformity: a systematic literature review. J Bone Joint Surg Am. 2018;100(18):1563-1573. doi:10.2106/JBJS.17.00975
Coetzee JC. Scarf osteotomy for hallux valgus repair: the dark side. Foot Ankle Int. 2003;24(1):29-33. doi:10.1177/107110070302400105
Lapidus PW. The author's bunion operation from 1931 to 1959. Clin Orthop Relat Res. 1960;16:119-135.
Cottom JM, Vora AM. Fixation of Lapidus arthrodesis with a plantar interfragmentary screw and medial locking plate: a report on 109 patients. J Foot Ankle Surg. 2013;52(4):465-469. doi:10.1053/j.jfas.2013.02.016
Austin DW, Leventen EO. A new osteotomy for hallux valgus: a horizontally directed "V" displacement osteotomy of the metatarsal head for hallux valgus and primus varus. Clin Orthop Relat Res. 1981;(157):25-30.
Weil LS. Scarf osteotomy for correction of hallux valgus. Historical perspective, surgical technique, and results. Foot Ankle Clin. 2000;5(3):559-580.
Ray RG, Ching RP, Christensen JC, Hansen ST Jr. Biomechanical analysis of the first metatarsocuneiform arthrodesis. J Foot Ankle Surg. 1998;37(5):376-385. doi:10.1016/s1067-2516(98)80043-0
Hyer CF, Scott RT, Swiatek M. A retrospective comparison of four plate constructs for first metatarsal-cuneiform arthrodesis: static plate, static plate with lag screw, locked plate, and locked plate with lag screw. J Foot Ankle Surg. 2012;51(3):285-287. doi:10.1053/j.jfas.2012.02.008

Hallux Valgus Correction - Comprehensive Decision-Making Guide (Chevron, Scarf, Lapidus)