import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Dorsomedial cutaneous nerve** Location: Subcutaneous, 2-3mm dorsal to medial incision line over 1st MTPJ Protection: Identify early during superficial dissection, retract dorsally with skin flap, avoid prolonged retractor pressure **Medial plantar proper digital nerve** Location: Deep to medial capsule, plantar aspect of metatarsal head Protection: Subperiosteal dissection, capsular layer maintained, avoid aggressive plantar stripping **Lateral sesamoid blood supply** Location: Plantar metatarsal head within sesamoid complex Protection: Measured lateral release (stepwise testing), preserve plantar soft tissue attachments, avoid excessive lateral dissection **First dorsal metatarsal artery** Location: Dorsal to 1st intermetatarsal space, exits between metatarsal bases Protection: Limit proximal dissection, stay subperiosteal, avoid deep retractor placement dorsally at base **Metatarsal head vascular supply** Location: Enters metatarsal neck plantarly, metaphyseal branches Protection: Subperiosteal dissection preserves periosteum with vessels, avoid circumferential stripping, maintain plantar soft tissue bridge ## Indications ### Absolute Indications - Moderate to severe hallux valgus with HVA 20-40°, IMA 13-20° - Symptomatic bunion with pain limiting function after failed conservative management (minimum 6 months orthotics, footwear modification, analgesia) - Congruent MTPJ on weight-bearing radiographs (critical - subluxed joint requires different approach) ### Relative Indications - Younger patients (age <60 years) with higher functional demands - Patients requiring cosmetic improvement with functional symptoms - Combined first-second intermetatarsal angle widening with stable TMT joint - Transfer metatarsalgia requiring metatarsal length preservation (versus Chevron which shortens) - Revision surgery after failed distal osteotomy (Chevron, Mitchell) ### Contraindications - Severe deformity with IMA >20° or HVA >40° (consider Lapidus) - TMT joint hypermobility >9mm translation (Lapidus preferred) - Incongruent MTPJ (subluxed joint) - requires realignment, not osteotomy alone - Active infection or soft tissue compromise - Peripheral vascular disease (assess pulses, consider vascular studies) - Severe osteoporosis or bone quality concerns (risk of fixation failure) - Inflammatory arthropathy with severe MTPJ arthritis (arthrodesis preferred) ### Exam Key Points - **Conservative management prerequisites**: 6 months trial of wide toe box footwear, orthotics with bunion pad, activity modification, NSAIDs - **Radiographic assessment**: weight-bearing AP and lateral foot radiographs mandatory - assess HVA, IMA, DMAA, MTPJ congruency, sesamoid position, first metatarsal length - **TMT stability testing**: clinical examination with TMT joint translation - passive dorsoplantar motion >9mm suggests hypermobility - **Patient selection**: motivated patients with realistic expectations, understand recovery time 12-16 weeks to normal footwear ## Surgical Anatomy ### First Metatarsal - **Shaft morphology**: Oval cross-section with thicker plantar cortex (weight-bearing surface) and thinner dorsal cortex - **Metaphyseal flare**: Head-shaft junction is transition zone - distal scarf limb exits here to avoid intra-articular violation - **Blood supply**: Dominant nutrient artery enters mid-diaphysis medially, metaphyseal branches enter plantarly at neck - subperiosteal dissection critical to preserve - **Sesamoid articulation**: Plantar surface has medial and lateral facets - lateral sesamoid position correlates with deformity severity ### First MTPJ Joint - **Capsule structure**: Thickened medially (becomes attenuated with chronic valgus), tight laterally (requires release), plantar plate with sesamoids - **Ligaments**: Collateral ligaments (medial stretched, lateral contracted), transverse metatarsal ligament (connects to second metatarsal, may require release) - **Congruency assessment**: Joint surfaces parallel on weight-bearing radiographs indicates congruent joint - prerequisite for osteotomy success ### Neurovascular Structures - **Dorsomedial cutaneous nerve**: Superficial branch of superficial peroneal nerve, crosses dorsomedial aspect of foot at MTPJ level, 15-20% injury rate if not protected - **Medial plantar proper digital nerve**: Branch of medial plantar nerve, runs plantar to metatarsal head deep to capsule, supplies medial hallux sensation - **First dorsal metatarsal artery**: Branch from dorsalis pedis, courses in first intermetatarsal space dorsally, at risk with deep dorsal dissection - **Lateral sesamoid blood supply**: Lateral plantar artery branches, disrupted by aggressive lateral release, AVN risk if over-released ### Soft Tissue Deforming Forces - **Adductor hallucis**: Attaches to lateral sesamoid and proximal phalanx base, primary deforming force pulling hallux laterally - **Abductor hallucis**: Displaced plantarly with chronic deformity, loses mechanical advantage as deforming force - **Extensor hallucis longus**: Bowstrings laterally over prominent medial eminence, contributes to valgus and pronation - **Flexor hallucis brevis**: Two heads with sesamoids, lateral head pulls hallux into valgus, medial head weakened ## Operative Technique ### Step 1: Patient positioning and marking Patient positioning and marking: Supine with bump under ipsilateral hip, thigh tourniquet applied but not inflated. Mark medial eminence, metatarsal shaft, osteotomy site (mid-diaphysis), check contralateral for symmetry goals. EXAM KEY: Proper positioning allows ankle rotation for fluoroscopy without leg holder interference. **Technical Tip**: Mark skin before tourniquet inflation while tissue landmarks palpable. Contralateral comparison essential for length and position goals. Bump under hip brings first metatarsal to horizontal plane for easier saw cuts. - Inadequate positioning causing intraoperative fluoroscopy difficulty - Failure to mark contralateral foot reference losing symmetry goals ### Step 2: Inflate tourniquet and prep Inflate tourniquet and prep: Inflate thigh tourniquet to 100mmHg above systolic (typically 250-300mmHg). Prep entire foot and ankle. Drape foot free. EXAM KEY: Tourniquet allows bloodless field for accurate osteotomy cuts and hardware placement. **Technical Tip**: Document tourniquet time - deflate at 90-120 minutes if procedure prolonged to prevent nerve injury. Exsanguination with Esmarch optional (some surgeons prefer gravity drainage only to reduce pain). - Tourniquet nerve palsy if excessive pressure or prolonged inflation >120 minutes - Skin prep solution pooling under tourniquet causing chemical burn ### Step 3: Medial incision and superficial dissection Medial incision and superficial dissection: 3-4cm medial longitudinal incision centred over mid-shaft 1st metatarsal, extending from proximal third to metatarsal head. Identify and protect dorsomedial cutaneous nerve (2-3mm dorsal to incision). Deepen through subcutaneous tissue. EXAM KEY: Nerve injury causes dorsal numbness - most common complaint. **Technical Tip**: Incision placed directly medial (not dorsomedial) to avoid nerve and allow capsular closure without tension. Skin incision slightly longer than bone work required to prevent wound edge tension. - Dorsomedial cutaneous nerve injury (15-20% incidence, usually transient neuropraxia) - Skin necrosis from excessive tension or devascularization ### Step 4: Capsular incision and periosteal elevation Capsular incision and periosteal elevation: Longitudinal capsular incision along medial metatarsal shaft. Elevate capsule and periosteum as continuous layer. Expose medial eminence and metatarsal shaft from head to base. Insert Hohmann retractors dorsally and plantarly. EXAM KEY: Subperiosteal dissection protects vascular supply to metatarsal head. **Technical Tip**: Keep periosteal flap intact for closure - improves healing and reduces adhesions. Tag capsule with sutures for later anatomic repair. Avoid circumferential stripping (AVN risk). - Metatarsal head AVN if periosteum stripped circumferentially - Plantar neurovascular injury if periosteal elevation extends too far plantarly ### Step 5: Lateral release assessment and execution Lateral release assessment and execution: Assess MTPJ congruency and lateral deviation. If passive correction inadequate, perform lateral release through same medial incision (inside-out technique) or small lateral stab incision. Release: (1) lateral capsule, (2) adductor hallucis from lateral sesamoid, (3) transverse metatarsal ligament if tight. EXAM KEY: Adequate lateral release essential to prevent undercorrection. **Technical Tip**: Test correction after each release step - over-release causes hallux varus (2-5% incidence). Preserve lateral sesamoid blood supply by releasing adductor tendon from fibular sesamoid insertion, not sesamoid itself. - Lateral sesamoid AVN if blood supply disrupted during release - Hallux varus from over-release (difficult revision problem) - Incomplete release causing undercorrection (8-12% recurrence) ### Step 6: Scarf osteotomy planning and marking Scarf osteotomy planning and marking: Mark osteotomy on bone with sterile marker or electrocautery: (1) Horizontal cut through mid-diaphysis (parallel to ground), (2) Proximal limb 60° angle directed dorsal-proximal (exits 10-12mm distal to TMT joint), (3) Distal limb 60° angle directed plantar-distal (exits at junction of metatarsal head and shaft). EXAM KEY: Z-shaped cut provides large surface area (30-35mm) and intrinsic stability. **Technical Tip**: Confirm distances with ruler before cutting - proximal exit must not violate TMT joint (causes instability), distal exit must be proximal to sesamoids (intra-articular violation). Use fluoroscopy to verify TMT distance. - TMT joint violation if proximal limb placed too proximally (causes instability) - Intra-articular MTPJ violation if distal limb placed too distally - Sesamoid injury if distal cut extends into plantar surface ### Step 7: Execute scarf osteotomy cuts Execute scarf osteotomy cuts: Use sagittal saw with fine blade (0.4-0.6mm). First cut: horizontal longitudinal cut in sagittal plane, mid-diaphysis, dorsal cortex to plantar cortex (do NOT penetrate plantar cortex completely - leave 2-3mm hinge). Second cut: proximal limb 60° angle. Third cut: distal limb 60° angle. Complete plantar cortex cut gently with osteotome. EXAM KEY: Incomplete plantar cortex cuts prevent propagation fracture and troughing. **Technical Tip**: Irrigate copiously during cutting to prevent thermal necrosis (bone death >47°C). Keep saw perpendicular to avoid oblique cuts causing instability. Smooth saw motion without excessive pressure. - Propagation fracture if cuts extend uncontrolled (especially plantar cortex) - Thermal necrosis from inadequate irrigation (nonunion risk) - Oblique cuts creating unstable geometry and difficult fixation ### Step 8: Mobilize osteotomy fragments Mobilize osteotomy fragments: Use small osteotome to gently mobilize capital fragment. Avoid excessive force or levering. If tight, complete cuts under direct vision with saw. EXAM KEY: Gentle mobilization prevents comminution and maintains cortical contact. **Technical Tip**: Do not lever or pry - this causes troughing (dorsal fragment translates into plantar fragment creating shortening and transfer metatarsalgia). If fragments do not mobilize easily, cuts are incomplete. - Troughing from excessive force during mobilization (5-10% if technique suboptimal) - Comminution of fragments making stable fixation impossible - Inadvertent complete fracture through plantar cortex losing hinge stability ### Step 9: Translate capital fragment laterally Translate capital fragment laterally: Displace metatarsal head fragment laterally 3-5mm (typically 50-75% metatarsal width for moderate deformity). Use ruler to measure translation. Maintain parallel alignment of fragments. EXAM KEY: Lateral translation corrects IMA by 1.5° per millimeter translated. **Technical Tip**: Over-translation (>5mm) causes troughing and metatarsal shortening. Under-translation leaves residual deformity. Check clinically and fluoroscopically. Calculate required translation: (current IMA - desired IMA of 8°) / 1.5 = mm translation needed. - Over-translation (>5mm) causing troughing, shortening, transfer metatarsalgia - Under-translation causing residual deformity and recurrence - Loss of parallel alignment causing step-off deformity and hardware prominence ### Step 10: Rotational and sagittal plane correction (if required) Rotational and sagittal plane correction (if required): If DMAA elevated (>10°), rotate capital fragment medially (pivot point at distal plantar corner). If transfer metatarsalgia present, plantarflex capital fragment 2-3mm. EXAM KEY: Rotation corrects pronation and DMAA. Plantarflexion unloads lesser metatarsals. **Technical Tip**: Rotation and translation are independent corrections. Excessive rotation creates MTPJ incongruity (joint surfaces no longer parallel). Check sesamoid position fluoroscopically - should be centred under metatarsal head. - Excessive rotation creating MTPJ incongruity and early arthritis - Inadequate rotation leaving residual DMAA and hallux pronation - Plantarflexion causing first ray overload and plantar keratosis ### Step 11: Provisional fixation and correction check Provisional fixation and correction check: Hold reduction with pointed reduction forceps or 1.6mm K-wire. Check alignment clinically: (1) hallux alignment straight, (2) no rotation, (3) length compared to contralateral. Fluoroscopy: (1) sesamoids centred under metatarsal head, (2) IMA <9°, (3) HVA <15°, (4) DMAA <10°. EXAM KEY: This is correction confirmation before definitive fixation. **Technical Tip**: If alignment unsatisfactory, remove provisional fixation and adjust translation/rotation. Easier now than revision surgery. Take AP, lateral, and oblique fluoroscopy views to assess 3D alignment. - Inadequate reduction assessment missing residual deformity - Fragment displacement during provisional fixation (use gentle technique) - Accepting suboptimal correction requiring early revision ### Step 12: Definitive fixation with compression screws Definitive fixation with compression screws: Two headless compression screws required for stability. First screw: 2.0-2.7mm headless screw (depending on bone size), proximal fragment into distal fragment, angled 15-20° from horizontal to engage thick dorsal cortex of capital fragment. Second screw: distal to first, parallel orientation. Lag technique for compression. EXAM KEY: Compression at osteotomy site essential for healing. **Technical Tip**: Pre-drill both fragments to prevent fragment displacement during screw insertion. Measure screw length to avoid plantar prominence (plantar cortex penetration causes painful keratosis). Countersink to avoid dorsal irritation. - Screw malposition causing fragment displacement or loss of correction - Plantar screw prominence causing painful plantar keratosis - Dorsal screw prominence causing extensor tendon irritation - Inadequate compression causing delayed union or nonunion ### Step 13: Medial eminence resection Medial eminence resection: Resect medial eminence with sagittal saw. Cut line from dorsal to plantar, parallel to medial shaft cortex. Avoid excessive resection (weakens fixation construct, causes flat-top deformity). Smooth with rongeur/rasp. EXAM KEY: Conservative resection sufficient after lateral translation. **Technical Tip**: Preserve medial cortex of metatarsal shaft - provides screw purchase and prevents stress fracture. Fluoroscopy confirms adequate but not excessive resection. Residual small prominence acceptable (remodels with time). - Excessive resection weakening fixation and causing flat-top deformity - Inadequate resection leaving symptomatic prominence - Damage to medial screw during eminence resection ### Step 14: Akin osteotomy assessment Akin osteotomy assessment: Assess hallux alignment after scarf correction and provisional capsule closure. If hallux valgus interphalangeus present (HVI angle >10°) or residual hallux valgus despite corrected IMA, perform Akin osteotomy. EXAM KEY: Akin addresses phalangeal component of deformity that scarf cannot correct. **Technical Tip**: Akin particularly indicated if DMAA elevated or HVI present preoperatively. Not always necessary - decision based on clinical alignment after scarf. Approximately 30-40% of cases require Akin addition. - Performing unnecessary Akin causing hallux varus or stiffness - Missing indication for Akin leaving residual deformity ### Step 15: Akin osteotomy execution (if indicated) Akin osteotomy execution (if indicated): Separate medial incision over proximal phalanx base (2cm longitudinal). Elevate periosteum circumferentially. Medial-based closing wedge osteotomy at base of proximal phalanx (apex lateral). Remove 2-3mm wedge. Close osteotomy with pointed clamp, creates varus correction. Fix with single headless screw (lag technique) or staple. EXAM KEY: Closing wedge more stable than opening wedge. **Technical Tip**: Wedge size determines correction - typically 2-3mm wedge adequate for 8-10° correction. Avoid hinge fracture by keeping lateral cortex intact initially, then carefully greenstick. Compression essential for healing. - Hinge fracture creating unstable osteotomy - Excessive wedge resection causing hallux varus - Inadequate fixation causing displacement or nonunion - Extensor hallucis longus laceration during periosteal elevation dorsally ### Step 16: Capsular repair and closure Capsular repair and closure: Repair medial capsule with 2-0 absorbable sutures in vest-over-pants technique (overlapping imbrication). Avoid excessive tension. Close subcutaneous layer with 3-0 absorbable suture. Skin closure with 3-0 or 4-0 nylon or monocryl subcuticular. Apply sterile dressing and post-operative shoe. EXAM KEY: Capsular imbrication provides additional stability. **Technical Tip**: Capsular repair should be performed without tension after lateral release and bony realignment. Excessive tension indicates incomplete lateral release or over-correction. Test MTPJ range of motion before final skin closure. - Skin closure under tension causing wound dehiscence or necrosis - Inadequate capsular repair losing medial restraint - Excessive capsular tightening causing stiffness ## Complications ### Additional Complications - **Dorsomedial cutaneous nerve injury**: 15-20% incidence (usually transient neuropraxia). Prevention: identify and protect nerve during superficial dissection, gentle retraction, avoid skin retractor pressure over nerve course. Management: transient neuropraxia resolves 3-6 months with reassurance, permanent numbness usually small area and well tolerated, desensitization techniques if bothersome. - **Stiffness/reduced MTPJ ROM**: 10-15% incidence (usually mild <10° loss). Prevention: early protected ROM exercises from 2 weeks, avoid overcorrection creating joint tension, preserve capsule for anatomic closure, address intra-articular pathology if present. Management: physiotherapy with passive ROM exercises, manipulation under anaesthesia if severe and within 12 weeks, arthrofibrosis requiring late MUA or arthroscopic adhesiolysis rarely needed. - **Infection**: <2% incidence. Prevention: perioperative antibiotics (cefazolin 2g IV within 60 minutes), sterile technique, minimize tourniquet time, atraumatic tissue handling. Management: superficial infection with cellulitis: oral antibiotics; deep infection: operative debridement, hardware retention if stable and within 4 weeks, hardware removal if loose or infection >4 weeks postop, IV antibiotics 6 weeks. ## Postoperative Management ### Immediate Postoperative (0-2 weeks) - **Weight bearing**: Heel weight bearing in postoperative shoe, crutches for balance - **Elevation**: Foot elevated above heart level majority of time to reduce swelling - **Ice**: 20 minutes every 2-3 hours for first 48-72 hours - **Dressing**: Bulky dressing maintained for 2 weeks, kept clean and dry - **Analgesia**: Multimodal - paracetamol, NSAIDs (controversial first 6 weeks due to bone healing concerns), opioids short-term if needed - **VTE prophylaxis**: Risk assessment, aspirin 100mg daily for 2 weeks if low risk, LMWH if high risk factors ### Early Rehabilitation (2-6 weeks) - **Wound care**: Suture removal at 2 weeks, wound check for healing - **Weight bearing**: Progress to forefoot weight bearing in postoperative shoe, wean crutches as tolerated - **Exercises**: Active and passive MTPJ ROM exercises, start gentle (5-10° initially, increase gradually) - **Swelling management**: Compression stocking, continued elevation when resting - **Radiographs**: First postoperative radiographs at 2 weeks to assess alignment and hardware position ### Intermediate Phase (6-12 weeks) - **Weight bearing**: Transition to supportive athletic shoe at 6 weeks (wide toe box, rigid sole initially) - **Radiographs**: 6-week radiographs to assess healing progression - **Exercises**: Progressive MTPJ ROM, strengthening exercises (toe curls, marble pickup) - **Activity**: Return to sedentary work at 2-4 weeks, light duty work at 6-8 weeks, avoid impact activities until 12 weeks - **Footwear**: Gradual transition to normal shoes 8-12 weeks based on swelling and comfort ### Advanced Rehabilitation (3-6 months) - **Radiographs**: 12-week radiographs to confirm union - **Activity progression**: Return to impact activities (running, jumping) at 12-16 weeks if radiographic union confirmed - **Footwear**: Return to fashion footwear (including heels) at 4-6 months, gradual progressive wear - **Final assessment**: 6-month clinical and radiographic assessment of final alignment and function ### Long-term Follow-up - **Monitoring**: Annual follow-up first 2 years to detect early recurrence - **Patient education**: Appropriate footwear selection (wide toe box, adequate depth), avoid excessive heel heights (>5cm), maintain healthy weight - **Complication surveillance**: Monitor for late complications (recurrence, arthritis, hardware symptoms) ## References 1. Barouk LS. Scarf osteotomy for hallux valgus correction. Local anatomy, surgical technique, and combination with other forefoot procedures. Foot Ankle Clin. 2000;5(3):525-558. PMID: 11232396. *Classic description of scarf technique by original developer, details anatomy and triplanar correction capabilities.* 2. Crevoisier X, Mouhsine E, Ortolano V, Udin B, Dutoit M. The scarf osteotomy for the treatment of hallux valgus deformity: a review of 84 cases. Foot Ankle Int. 2001;22(12):970-976. PMID: 11783925. *Mid-term outcomes demonstrating 8-12% recurrence rate and complication profile.* 3. Duke C. Scarf osteotomy for correction of hallux valgus: A review and analysis of the literature. Foot Ankle Surg. 2009;15(1):1-8. PMID: 19410169. *Systematic review of scarf outcomes, complications, and comparison to other techniques.* 4. Kristen KH, Berger C, Stelzig S, Thalhammer G, Posch M, Engel A. The SCARF osteotomy for the correction of hallux valgus deformities. Foot Ankle Int. 2002;23(3):221-229. PMID: 11934064. *Large series establishing safety profile and defining technical pearls for troughing prevention.* 5. Smith SE, Landorf KB, Butterworth PA, Menz HB. Scarf versus Chevron osteotomy for the correction of 1-2 intermetatarsal angle in hallux valgus: a systematic review and meta-analysis. J Foot Ankle Surg. 2012;51(4):437-444. PMID: 22459093. *Meta-analysis comparing scarf to chevron, demonstrating superior IMA correction with scarf for moderate deformity.* 6. Coetzee JC, Rippstein P. Surgical strategies: scarf osteotomy for hallux valgus. Foot Ankle Int. 2007;28(4):529-535. PMID: 17475154. *Technical guide detailing osteotomy geometry, fixation options, and complication avoidance strategies.* 7. Jones S, Al Hussainy HA, Ali F, Betts RP, Flowers MJ. Scarf osteotomy for hallux valgus. A prospective clinical and pedobarographic study. J Bone Joint Surg Br. 2004;86(6):830-836. PMID: 15330023. *Prospective study with pedobarographic analysis demonstrating pressure redistribution and functional outcomes.* 8. Deenik A, Pilot P, Brandt SE, van Mameren H, van Draijer W, de Bie R. Scarf versus Chevron osteotomy in hallux valgus: a randomized controlled trial in 96 patients. Foot Ankle Int. 2007;28(5):537-541. PMID: 17559758. *Level 1 evidence RCT comparing scarf to chevron, demonstrating equivalent outcomes for mild-moderate deformity.* 9. Bai LB, Lee KB, Seo CY, Song EK, Yoon TR. Distal chevron osteotomy with distal soft tissue procedure for moderate to severe hallux valgus deformity. Foot Ankle Int. 2010;31(8):683-688. PMID: 20727316. *Comparison study helping define indications - moderate deformity suitable for either scarf or modified chevron.* 10. Wagner P, Wagner E. Is the Scarf osteotomy better than the Lapidus procedure for treatment of hallux valgus? A systematic review. J Orthop Surg Res. 2020;15(1):137. PMID: 32272937. *Recent systematic review comparing scarf to Lapidus, defining selection criteria based on deformity severity and TMT stability.*

Scarf and Akin Osteotomy for Hallux Valgus

Scarf and Akin Osteotomy for Hallux Valgus