import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Wraps around fibular neck 10-20mm distal to fibular head.** At highest risk with lateral closing wedge or fibular osteotomy. Medial approach avoids directly but posterolateral retractors can stretch it. **Protection: Flex knee to relax nerve, avoid posterolateral retraction, palpate fibular neck before osteotomy.** **Lies 5-10mm posterior to proximal tibia at osteotomy level.** Risk with posterior saw penetration or aggressive osteotome placement. **Protection: Use Hohmann retractor posteriorly, stop saw 10mm from posterior cortex, tactile awareness during osteotomy.** **Crosses anteromedial tibia 10-30mm below joint line** - directly in surgical field. Injury causes anteromedial knee numbness. **Protection: Full-thickness flap elevation, protect with retractor, warn patient of numbness risk preoperatively.** **MCL deep fibers attach to proximal tibia at osteotomy level.** Pes anserinus lies superficially. **Protection: Release superficial MCL subperiosteally, identify pes anserinus, preserve/repair at closure.** ### Ideal Patient Selection **Absolute Indications:** - Isolated medial compartment OA (Ahlback Grade 1-3) - Constitutional varus malalignment greater than 5 degrees - Age less than 60-65 years (physiological age matters) - Active lifestyle incompatible with arthroplasty restrictions - Good knee range of motion (at least 0-120 degrees) - Intact ACL (or plan concurrent reconstruction) **Relative Indications:** - Medial meniscectomy with early OA changes - Post-traumatic varus deformity - Combined with cartilage procedures (microfracture, OATS, ACI) **Contraindications:** - Lateral compartment arthritis (bone-on-bone) - Patellofemoral arthritis (relative - depends on severity) - Fixed flexion deformity greater than 15 degrees - Inflammatory arthritis (RA) - Grade 4 medial OA with significant bone loss - Ligamentous instability (unless addressed) - BMI greater than 35-40 (relative) - Heavy manual labour with high failure risk ### Essential Imaging **Weight-Bearing Long Leg Films:** - Standing anteroposterior from hip to ankle - Measure mechanical axis deviation (MAD) - Calculate correction angle using Miniaci method - Assess joint line convergence angle **Lateral Radiograph:** - Measure posterior tibial slope (normal 5-10 degrees) - Opening wedge increases slope 2-3 degrees - Consider closing wedge if slope greater than 12 degrees **MRI Knee:** - Confirm lateral compartment integrity - Assess ACL status - Evaluate meniscal pathology - Grade cartilage defects ### Calculation Methods **Miniaci Method:** 1. Draw mechanical axis from femoral head centre to ankle centre 2. Mark Fujisawa point (62% from medial tibial plateau) 3. Draw corrected mechanical axis through Fujisawa point 4. Measure angle at osteotomy level **Digital Planning:** - PreOp software, TraumaCad, or similar - Allows simulation of opening wedge - Calculate gap height at medial cortex **Rule of Thumb:** - 1mm opening at medial cortex = approximately 1 degree correction - 10mm gap = approximately 10 degrees correction ### Informed Consent Points **Expected Outcomes:** - 80-90% good/excellent results at 10 years - Pain relief and improved function - Delays TKA by 10-15 years average - Return to recreational sport typically possible **Common Risks:** - Numbness anteromedial knee (infrapatellar nerve): 20-30% - Hardware prominence requiring removal: 10-20% - Under/overcorrection requiring revision: 5-10% - Delayed union: 2-5% - Infection: 1-2% **Rare but Serious Risks:** - DVT/PE: 1-2% - Lateral hinge fracture: 5-20% (impacts healing) - Non-union: 1-5% - Compartment syndrome: less than 1% - Peroneal nerve palsy: less than 1% - Conversion to TKA earlier than expected **Rehabilitation:** - Touch weight-bearing 6 weeks - Progressive loading 6-12 weeks - Full activities 4-6 months - Sports return 6-12 months ### Essential Equipment Checklist **Patient Positioning:** - Supine on radiolucent table - Knee flexed 20-30 degrees over bolster - Thigh tourniquet (optional - improves visualisation) - Ensure full C-arm access - test before draping **Instrumentation:** - HTO-specific instrument set (Synthes Tomofix, Arthrex, or similar) - Oscillating saw with narrow blade - Graduated osteotomes (set of increasing widths) - K-wires 2.0mm for guide placement - Depth gauge - Calibrated spreaders or lamina spreaders **Implants:** - Tomofix medial HTO plate (or equivalent locking plate) - Locking screws 4.5mm or 5.0mm - Cortical screws if needed - Bone graft options (if gap greater than 10mm): - Iliac crest autograft - Allograft wedge - Synthetic bone substitute (beta-TCP, hydroxyapatite) **Fluoroscopy:** - C-arm with surgeon driving capability - Alignment rod (long metal rod or diathermy cord) - Screen positioned for easy viewing ### Step 1: Positioning and Preparation Position patient supine with knee flexed 20-30 degrees over sandbag or bolster. This relaxes the posterior structures. Apply thigh tourniquet but don't inflate unless necessary. Position C-arm from opposite side ensuring clear AP and lateral views of proximal tibia. Mark joint line, tibial tubercle, and planned incision under fluoroscopy. **Technical Tip**: Before draping, confirm C-arm can obtain true AP (tibial spines equidistant from tibial margins) and lateral views. Poor imaging wastes time and increases error risk. ### Step 2: Incision and Superficial Dissection Make 6-8cm longitudinal incision starting at joint line, centred between tibial tubercle and posteromedial tibial border. Curve slightly posteriorly distally. Incise fascia in line with skin. Identify pes anserinus (sartorius, gracilis, semitendinosus) - these lie superficial to MCL. The infrapatellar branch of saphenous nerve crosses this field. Elevate full-thickness fasciocutaneous flaps to protect it. Warn patients preoperatively that anteromedial knee numbness occurs in 20-30%. ### Step 3: Deep Dissection and MCL Release Release pes anserinus from tibial insertion with electrocautery or sharply - tag with suture for later repair. Identify superficial MCL fibres running obliquely across proximal tibia. Release MCL subperiosteally from tibia using elevator or electrocautery - this allows osteotomy opening without MCL strain. **Technical Tip**: The MCL must be released to allow osteotomy opening. If not released, opening the wedge will stretch and potentially rupture the MCL, causing postoperative instability. ### Step 4: Exposure of Proximal Medial Tibia Strip periosteum from anteromedial and posteromedial tibia from joint line to 5cm below. Place Hohmann retractor posteriorly directly on bone - this protects popliteal vessels which lie 5-10mm behind posterior tibial cortex. Place anterior retractor protecting patellar tendon and tibial tubercle. The popliteal artery lies directly behind the posterior tibial cortex at this level. ALWAYS place a Hohmann retractor on bone posteriorly before any saw or osteotome use. ### Step 5: Guide Wire Placement Under fluoroscopy, insert first guide wire from medial cortex (below planned osteotomy) directed toward the lateral hinge point. The target is: - AP plane: aimed at fibular head/tip - Obliquity: ascending 10-15 degrees proximally - Endpoint: 10mm from lateral cortex (leave bone bridge for hinge) Confirm wire position on AP and lateral - wire should be 35-40mm below joint line medially. **Technical Tip**: The guide wire defines the hinge point. Too proximal risks intra-articular fracture. Too distal limits correction. Aim for wire to exit 10mm below joint line at lateral cortex. ### Step 6: Second Guide Wire for Biplanar Cut Insert second guide wire parallel to first but directed anterosuperiorly toward tibial tubercle. This ascending limb creates the biplanar osteotomy which: 1. Protects tibial tubercle attachment 2. Prevents patellar tendon impingement 3. Increases construct stability The two wires should diverge by 100-110 degrees anteriorly. ### Step 7: Horizontal Osteotomy Using oscillating saw with narrow blade, cut between the two guide wires: - Start at posteromedial cortex - Progress anteriorly staying parallel to main wire - Stop 10mm from lateral cortex (preserve hinge) - Copious irrigation during sawing to prevent thermal necrosis - Complete posterior cortex cut with osteotome if needed Do NOT penetrate the lateral cortex. The lateral hinge provides stability and maintains blood supply. Complete lateral hinge fracture increases non-union risk 4-fold and may require supplementary fixation. ### Step 8: Ascending Limb (Biplanar Cut) Complete the ascending limb from main osteotomy toward tibial tubercle: - 45-degree angle from horizontal cut - Exits proximal to tubercle insertion - Creates L-shaped osteotomy pattern - Preserves patellar tendon attachment **Technical Tip**: The biplanar technique creates a larger surface area for healing and protects the extensor mechanism. It has become standard over simple transverse cuts. ### Step 9: Controlled Osteotomy Opening Using thin osteotomes, gradually open the osteotomy: 1. Insert thin osteotome at posteromedial corner 2. Gently lever to initiate opening 3. Insert second osteotome anteriorly 4. Stack progressively wider osteotomes 5. Advance slowly - feel for hinge maintaining integrity 6. Open to calculated distance (measured with depth gauge) Open SLOWLY and GRADUALLY. Rapid forced opening fractures the lateral hinge. If significant resistance encountered, check for incomplete posterior cut and extend with osteotome. ### Step 10: Alignment Verification With osteotomy held open at planned correction, verify alignment: **Cable Method:** 1. Hold alignment rod from hip (ASIS for proxy) to ankle centre 2. Check rod passes through Fujisawa point (62% tibial plateau) 3. Adjust opening until rod position correct **Grid Method:** 1. Place alignment grid on tibial plateau under fluoro 2. Measure mechanical axis position as percentage Target: mechanical axis through 62-66% of tibial plateau from medial side. **Technical Tip**: Better to slightly overcorrect (65%) than undercorrect. Undercorrection is commonest cause of early failure. The knee will look slightly valgus on table - this is correct. ### Step 11: Plate Application - Tomofix Apply medial locking plate (Tomofix or similar): 1. Position plate on anteromedial tibial surface 2. Proximal end should not impinge on MCL 3. Check plate position on AP and lateral fluoro 4. Insert proximal locking screws (2-4 screws) 5. Insert distal locking screws (2-4 screws) 6. Screws should be bicortical where possible **Technical Tip**: The Tomofix plate has a spacer portion that maintains correction angle. Some systems use separate wedge inserts. Ensure screws don't penetrate the joint - check on lateral view. ### Step 12: Gap Management Assess osteotomy gap: **Gap less than 7mm**: Can leave empty - will heal with haematoma **Gap 7-10mm**: Consider bone graft or substitute **Gap greater than 10mm**: Bone graft strongly recommended - Iliac crest autograft (gold standard) - Structural allograft wedge - Synthetic wedge (beta-TCP, hydroxyapatite) Pack graft into osteotomy gap ensuring posterior and lateral defect filled. ### Step 13: Final Checks and Closure Complete surgical checklist: - [ ] Alignment confirmed (Fujisawa point) - [ ] Plate position confirmed on AP and lateral - [ ] No screw penetration of joint - [ ] Osteotomy gap filled if indicated - [ ] Lateral hinge intact or only partial crack - [ ] Tourniquet down, haemostasis achieved Closure: 1. Repair pes anserinus if released (2-0 absorbable) 2. Close fascia over plate 3. Subcutaneous 2-0 absorbable 4. Skin staples or subcuticular Dressing and wool/crepe or knee immobiliser. If complete lateral hinge fracture occurs during opening: 1. STOP opening immediately 2. Assess fracture pattern on fluoroscopy 3. Options: - Small crack (partial hinge intact): proceed with standard fixation - Complete fracture: requires supplementary lateral plate or screws - Unstable: consider closing wedge conversion or staged procedure Recognition: Sudden "give" during opening, instability on manipulation, fracture line visible on fluoro **Fracture Classification (Takeuchi):** - **Type 1**: Fracture extends into tibial plateau (worst prognosis) - **Type 2**: Fracture below tibial plateau, above fibular head - **Type 3**: Fracture into proximal tibiofibular joint **Management by Type:** - Type 1: May need revision to lateral plateau screw fixation - Type 2: Additional lateral locking plate advised - Type 3: Often stable if hinge partially intact - standard fixation may suffice ### Immediate Post-operative (Days 0-7) - Knee immobiliser or hinged brace - Touch weight-bearing only with crutches - Gentle ROM exercises 0-90 degrees - DVT prophylaxis: LMWH for 2-4 weeks - Check X-ray before discharge ### Early Rehabilitation (Weeks 2-6) - Continue touch weight-bearing - Progress ROM to 0-120 degrees - Quadriceps strengthening (isometric, SLR) - Stationary cycling when ROM allows - X-ray at 6 weeks to assess healing ### Progressive Loading (Weeks 6-12) - If radiographic consolidation: progress to 50% weight-bearing week 6-8 - Full weight-bearing by week 8-12 - Proprioception and balance exercises - Pool therapy - Repeat X-ray at 12 weeks ### Return to Activity (Months 3-12) - Low-impact sport from 4-6 months (swimming, cycling) - Running from 6 months if healed - Contact/cutting sport from 9-12 months - Hardware removal if symptomatic (after 12-18 months) ### Follow-up Schedule - 2 weeks: wound check - 6 weeks: X-ray, progress weight-bearing - 12 weeks: X-ray, typically full weight-bearing - 6 months: functional assessment - 12 months: final assessment, long leg films - Annual review if symptoms recur 1. Lobenhoffer P, Agneskirchner JD. Improvements in surgical technique of valgus high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc. 2003;11(3):132-138. 2. Fujisawa Y, Masuhara K, Shiomi S. The effect of high tibial osteotomy on osteoarthritis of the knee: an arthroscopic study of 54 knee joints. Orthop Clin North Am. 1979;10(3):585-608. 3. Takeuchi R, Ishikawa H, Aratake M, et al. Medial opening wedge high tibial osteotomy with early full weight bearing. Arthroscopy. 2009;25(1):46-53. 4. Spahn G, Kirschbaum S, Kahl E. Factors that influence high tibial osteotomy results in patients with medial gonarthritis: a score to predict the results. Osteoarthritis Cartilage. 2006;14(2):190-195. 5. Noyes FR, Barber-Westin SD, Hewett TE. High tibial osteotomy and ligament reconstruction for varus angulated anterior cruciate ligament-deficient knees. Am J Sports Med. 2000;28(3):282-296. 6. Amendola A, Panarella L. High tibial osteotomy for the treatment of unicompartmental arthritis of the knee. Orthop Clin North Am. 2005;36(4):497-504. 7. Staubli AE, De Simoni C, Babst R, Lobenhoffer P. TomoFix: a new LCP-concept for open wedge osteotomy of the medial proximal tibia - early results in 92 cases. Injury. 2003;34(Suppl 2):B55-B62. 8. Miller BS, Downie B, McDonough EB, Wojtys EM. Complications after medial opening wedge high tibial osteotomy. Arthroscopy. 2009;25(6):639-646. 9. Bonasia DE, Dettoni F, Sito G, et al. Medial opening wedge high tibial osteotomy for medial compartment overload/arthritis in the varus knee: prognostic factors. Am J Sports Med. 2014;42(3):690-698. 10. Woodacre T, Ricketts M, Evans JT, et al. Complications associated with opening wedge high tibial osteotomy - a review of the literature and of 15 years of experience. Knee. 2016;23(2):276-282.

High Tibial Osteotomy (HTO) - Medial Opening Wedge

High Tibial Osteotomy (HTO) - Medial Opening Wedge