import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' ### Ideal Candidate (FRCS Key Criteria) - **Age**: Less than 60-65 years (biological age matters) - **Activity level**: High demand, wishes to return to sport - **BMI**: Less than 30 (higher BMI = higher failure rates) - **Arthritis**: Isolated medial compartment (Ahlbäck grade 1-2) - **Alignment**: Varus malalignment with mechanical axis through medial compartment - **ROM**: Flexion greater than 90°, full extension (no fixed flexion deformity) - **Stability**: Intact or reconstructable ligaments - **Meniscus**: Present medial meniscus (ideally) or concomitant MAT ### Specific Indications - Symptomatic medial compartment OA with varus alignment - Post-traumatic medial OA in young patient - Varus thrust gait from ACL deficiency - Combined with ACL reconstruction for chronic varus thrust - Cartilage restoration procedures requiring realignment **Examiner Question**: "What is the ideal patient for a medial opening wedge high tibial osteotomy?" **Model Answer**: "The ideal HTO candidate is a **young, active patient (under 60)** with isolated **medial compartment OA (Ahlbäck grade 1-2)** and **varus malalignment**. Key criteria include: BMI less than 30 (higher BMI has higher failure rates), ROM greater than 90° flexion with full extension (no fixed flexion deformity), stable or reconstructable ligaments, and an intact medial meniscus (or suitable for MAT). The mechanical axis should pass through the medial compartment. This patient typically wants to return to high-impact activities or sport, which makes them unsuitable for arthroplasty at this age. HTO preserves the native joint, allows full activity, and maintains future options for TKA if needed." - **Lateral or patellofemoral OA** - absolute contraindication; shifting load will worsen other compartments - **Inflammatory arthritis** - HTO does not address systemic disease; contraindicated - **Overcorrection expectation** - HTO improves, not eliminates symptoms; set realistic goals - **Ignoring lifestyle** - patient unwilling to comply with 3-4 month recovery is poor candidate ### Absolute Contraindications - Inflammatory arthritis (RA, seronegative) - Lateral or patellofemoral compartment OA - Fixed flexion deformity greater than 10-15° - Flexion less than 90° - Varus greater than 15° (relative - may need staged procedure) - Ligamentous instability not addressed - Obesity BMI greater than 35 - Smoker (relative - high nonunion risk) ### Relative Contraindications - Age greater than 65 years - BMI 30-35 - Prior lateral meniscectomy (accelerates lateral compartment degeneration) - Patellofemoral symptoms - Bone loss or prior proximal tibial surgery - Osteoporosis (weak fixation) **Examiner Question**: "A 58-year-old patient with medial compartment OA has had a previous lateral meniscectomy. Can you still offer HTO?" **Model Answer**: "Previous lateral meniscectomy is a **relative contraindication** to HTO that requires careful consideration. The concern is that shifting load to the lateral compartment (which has lost its meniscus) will accelerate lateral compartment degeneration. However, it is not an absolute contraindication. My approach would be: (1) **Careful imaging assessment** of the lateral compartment - if there is already established lateral OA, HTO is contraindicated. (2) **Counsel the patient** that long-term outcomes may be inferior compared to a patient with an intact lateral meniscus - studies show higher failure rates. (3) **Consider alternative options** such as UKA or TKA. (4) If proceeding, I would be **more conservative with correction** (target 60-62% rather than 66%) to avoid overloading the vulnerable lateral compartment. The patient must understand the increased risk of needing further surgery." - **Missing lateral compartment OA** - always obtain Rosenberg view; shifting load causes rapid lateral degeneration - **Ignoring smoking status** - nonunion rate significantly higher; insist on cessation - **Underestimating flexion contracture** - HTO cannot correct fixed flexion deformity; will worsen gait - **Ligament instability** - must address ACL/PCL before or with HTO; otherwise correction will fail ### Imaging Protocol 1. **Long leg standing radiographs** (hip-knee-ankle films) - Measure mechanical axis deviation (MAD) - Calculate hip-knee-ankle angle (HKA) - Assess medial proximal tibial angle (MPTA - normal 87°) 2. **Weight-bearing AP/lateral knee** - Ahlbäck grade of medial compartment - Lateral compartment status - Posterior tibial slope (aim to preserve) 3. **Rosenberg view** (45° PA weight-bearing) - Posterior condyle cartilage assessment 4. **Patellofemoral views** - Rule out significant PFJ arthritis ### Correction Calculation **Miniaci Method** (most common): 1. Draw mechanical axis (hip center to ankle center) 2. Mark Fujisawa point (62-66% across tibial width from medial) 3. Draw lines from center of femoral head and ankle center to this point 4. Intersection at tibial osteotomy site = correction angle **Rule of thumb**: 1mm opening ≈ 1° correction - Typical correction: 8-12mm opening - Calculate: if MAD is 15mm medial, need ~12-15mm opening ### Slope Considerations - Aim to preserve native posterior tibial slope - Anterior opening increases slope (flexion instability, increased ACL stress) - Posterior opening decreases slope (extension restriction) - For ACL deficiency: may intentionally increase slope 3-5° to improve stability **Examiner Question**: "Explain the Fujisawa point and why we target 62-66% across the tibial width." **Model Answer**: "The **Fujisawa point** is the optimal target for mechanical axis realignment in HTO, located at **62-66% across the tibial plateau width** measured from the medial edge - this is **just lateral to the tibial spine**. The rationale is biomechanical load transfer: we shift the mechanical axis from the diseased medial compartment to the healthy lateral compartment. Targeting 62-66% creates approximately **3-5° of mechanical valgus**, which unloads the medial compartment while avoiding excessive lateral compartment loading. Studies by Fujisawa showed that patients corrected to this point had the best long-term outcomes. **Undercorrection** (targeting 50% or tibial spine) leaves persistent medial overload and early failure. **Overcorrection** (greater than 70%) causes lateral compartment overload and cosmetically unacceptable valgus. The 62-66% range provides the optimal balance." - **Non-weight-bearing films** - underestimate varus; must use standing long-leg radiographs - **Targeting 50% (tibial spine)** - undercorrection leads to early failure - **Ignoring posterior slope** - unintentional slope change affects ACL stress and knee kinematics - **Forgetting Rosenberg view** - misses posterior condyle OA which is a contraindication ### Essential Equipment - **Osteotomy plates**: TomoFix (Synthes), Puddu plate, Aesculap, or equivalent - **Calibrated osteotomes**: Graduated sizes for controlled opening - **Oscillating saw**: Fine blade for precision - **Guide wires**: 2.0-2.4mm K-wires for osteotomy guidance - **Alignment rod/cable**: For intraoperative mechanical axis check - **Bone grafts** (if gap greater than 10mm): - Autograft: iliac crest, distal femur - Allograft: structural or cancellous chips - Synthetic: wedges, TCP, bone substitute ### Plate Selection - **Locking plates** preferred (TomoFix most studied) - Proximal 4 locking screws - Distal 4 screws (locking or cortical) - Spacer block sizes available (7-17.5mm) ### Fluoroscopy Setup - C-arm from contralateral side - True AP and lateral views essential - Radiolucent table/leg holder **Examiner Question**: "When do you use bone graft in opening wedge HTO and what are your options?" **Model Answer**: "Bone grafting is indicated for **gaps greater than 10mm** to promote healing and prevent nonunion. For smaller gaps (7-10mm), the evidence suggests stable fixation with locking plates allows healing without graft. **Autograft options** include iliac crest (gold standard for healing but donor site morbidity) or local bone from the distal femur during concurrent procedures. **Allograft options** include structural wedges or cancellous chips - good healing rates with no donor site morbidity. **Synthetic options** include tri-calcium phosphate (TCP) wedges and bone substitutes - avoid in smokers or metabolically compromised patients. My preference for large gaps (greater than 12mm) is **iliac crest autograft** for optimal healing. For 10-12mm gaps in healthy patients, I would use **allograft chips** or **TCP wedge** with good outcomes." - **No bone graft for large gaps** - greater than 10mm gaps without graft have higher nonunion rates - **Non-locking plate** - conventional plates have higher failure rates; use locking plates (TomoFix standard) - **Missing calibrated osteotomes** - forced opening without graduated wedges causes hinge fracture - **Poor fluoroscopy positioning** - cannot confirm alignment or hinge integrity without true AP/lateral views **Lateral tibial cortex**. Must preserve 5-10mm of intact cortex as the hinge. Hinge fracture is the most common complication (10-30%) - leads to instability and loss of correction. **Infrapatellar branch**. Crosses operative field 2-3cm below joint line posteriorly. Injury causes numbness over anteromedial knee/proximal tibia. Often unavoidable but warn patient. **Posterior to proximal tibia**. Located 1-2cm posterior to posterior tibial cortex. Risk with posterior cortex penetration or aggressive posterior retraction. Catastrophic if injured. **Tibial tubercle insertion**. Must protect during osteotomy and plate insertion. Biplanar cut with ascending limb behind tubercle prevents patella baja. **Superficial MCL insertion**. Releases with osteotomy opening - may need to protect/repair. Deep MCL should be preserved for stability. ### Surface Anatomy - **Tibial tubercle**: Palpable prominence, patellar tendon insertion - **Medial tibial plateau**: Palpable joint line - **Pes anserinus**: Insertion 5-7cm below joint line on anteromedial tibia (sartorius, gracilis, semitendinosus) - **Gerdy's tubercle**: Lateral tibial tubercle, ITB insertion ### Key Anatomical Relationships | Structure | Location | Clinical Relevance | |-----------|----------|-------------------| | Osteotomy level | 4-5cm below joint line | Above tibial tubercle, below weight-bearing zone | | Lateral hinge | 1cm from lateral cortex | Must preserve for stability | | Saphenous nerve | Posterior to pes anserinus | Risk of injury with posterior dissection | | Popliteal vessels | 1-2cm behind posterior cortex | Never penetrate posterior cortex | | Superficial MCL | Broad insertion 5-7cm below joint | Releases with opening - self-heals | ### Osteotomy Plane - **Horizontal cut**: Parallel to tibial plateau slope, from medial cortex toward fibular head - **Ascending cut**: Behind tibial tubercle, 135° angle anteriorly - **Depth**: Stop 10mm from lateral cortex (preserve hinge) - **Direction**: Aim at superior aspect of fibular head **Patient Position**: Supine on radiolucent table. Sandbag under ipsilateral hip if needed for neutral rotation. Thigh tourniquet. Leg holder or bolster allowing full knee flexion/extension. **C-arm Position**: From contralateral side for true AP and lateral views. **Prep and Drape**: Entire lower limb from tourniquet to foot. Allow knee flexion during procedure. **Alignment Check**: Before incision, verify anatomical landmarks and planned correction on long leg films. ### Step 1: Incision and Exposure Longitudinal or oblique incision on anteromedial tibia, extending from joint line to 6-8cm distally. Identify and protect the pes anserinus tendons posteriorly. Incise periosteum and reflect anterior to tibial tubercle and posterior to pes anserinus. **Technical Pearl**: "Anteromedial incision, midway between tibial tubercle and posteromedial border. I identify pes anserinus (remember: SGS - Sartorius, Gracilis, Semitendinosus from anterior to posterior) and keep my dissection anterior to these structures." - Protect infrapatellar branch of saphenous nerve (runs with saphenous vein posteriorly) - Stay subperiosteal to protect soft tissue - Identify MCL for later reference ### Step 2: Guide Wire Placement Place first guide wire from medial cortex, 4-5cm below joint line, aiming toward the tip of the fibular head. Wire should be parallel to the tibial slope (posterior tilt). Confirm position on AP and lateral fluoroscopy - wire should stop 10mm from lateral cortex. **Technical Pearl**: "My guide wire starts 4-5cm below the joint line on the medial cortex and aims at the fibular head tip. I check AP and lateral fluoro to confirm it's parallel to the joint slope and stops 10mm from the lateral cortex - this is my HINGE." - Wire too proximal risks intra-articular fracture - Wire too distal creates stress riser - Anterior trajectory increases posterior slope - Must preserve 10mm lateral cortex for stable hinge ### Step 3: Biplanar Osteotomy Cut Perform the biplanar osteotomy using oscillating saw: 1. **Horizontal cut**: Along guide wire plane, stop 10mm from lateral cortex 2. **Ascending cut**: Behind tibial tubercle at 135° angle to horizontal cut, protecting patellar tendon Complete the osteotomy with thin osteotomes, working carefully toward the hinge. **Technical Pearl**: "I make a biplanar cut - horizontal along my guide wire stopping 1cm from lateral cortex, then an ascending cut behind the tibial tubercle. This ascending cut protects the patellar tendon and prevents patella baja. I complete the cut with thin osteotomes, never forcing the hinge." - NEVER breach posterior cortex (popliteal vessels) - Keep saw blade cool with irrigation - Use thin, sharp osteotomes for final cut - Do not force opening - will fracture hinge ### Step 4: Gradual Opening Gradually open the osteotomy using calibrated wedge osteotomes. Insert sequentially larger sizes until reaching the planned correction. Monitor for hinge integrity - feel for sudden give indicating fracture. **Technical Pearl**: "I open gradually with sequential wedges - 5mm, then 8mm, then 10mm, up to my planned opening. I feel for the hinge constantly - any sudden give means fracture. Slow controlled opening over 5 minutes allows viscoelastic stress relaxation." - Rapid forced opening = hinge fracture - Allow 1-2 minutes between sequential wedge sizes - If hinge fractures, need alternative fixation strategy ### Step 5: Alignment Verification Insert alignment rod or cable from hip center (ASIS) through knee to ankle center (midpoint between malleoli). Verify rod passes through Fujisawa point (62-66% across tibial width). Adjust opening as needed. **Technical Pearl**: "I check alignment with a rod from the hip center (I use the ASIS as proxy) to the ankle center. The rod should pass through the Fujisawa point - 62-66% across the tibial plateau, which is just lateral to center. This ensures I've transferred load to the healthy lateral compartment." - Undercorrection = continued medial overload, early failure - Overcorrection = lateral compartment overload and cosmetic concerns - Document alignment on fluoroscopy ### Step 6: Plate Fixation Apply medial opening wedge locking plate (TomoFix or similar). Secure with proximal and distal locking screws. Insert bone graft if gap exceeds 10mm - autograft, allograft, or synthetic. Confirm final alignment and hardware position on fluoroscopy. **Technical Pearl**: "I use a TomoFix locking plate with spacer block sized to my opening. Four proximal locking screws, four distal screws. For gaps greater than 10mm, I fill with either iliac crest autograft or allograft chips to promote healing. Final fluoro confirms alignment and screw lengths." - Avoid screws into joint - Check lateral screw lengths (bicortical distally) - Ensure plate does not impinge patellar tendon - Confirm hinge integrity maintained ### Step 7: Closure and Post-op Care Release tourniquet and achieve hemostasis. Close pes anserinus fascia over plate for soft tissue coverage. Layered closure with absorbable deep sutures. Skin closure of choice. Apply compressive dressing and hinged knee brace locked in extension. **Technical Pearl**: "I close the pes anserinus fascia over the plate for soft tissue coverage - this reduces hardware prominence. Hinged brace for 6 weeks. Protected weight bearing until radiographic healing confirmed at 6-8 weeks." - **Not covering plate with soft tissue** - exposed hardware causes skin irritation and prominence requiring removal - **Full weight bearing too early** - before radiographic healing leads to loss of correction or hardware failure - **Missing DVT prophylaxis** - prolonged immobilisation increases VTE risk; follow local protocol - **Ignoring wound complications** - early infection requires aggressive treatment to save the osteotomy ### Immediate Post-op (0-2 weeks) - Hinged knee brace locked in extension - Ice, elevation, analgesia - DVT prophylaxis (LMWH or aspirin per protocol) - Toe-touch weight bearing with crutches/frame - Gentle ROM exercises in brace (0-90°) ### Early Rehabilitation (2-6 weeks) - Progressive ROM (target full ROM by 6 weeks) - Continued protected weight bearing - Quadriceps strengthening (straight leg raise, quads sets) - Stationary bike (when ROM permits) - X-ray at 6 weeks to assess healing ### Late Rehabilitation (6-12 weeks) - Progress to full weight bearing when radiographic healing confirmed - Wean from brace - Progressive strengthening (closed chain exercises) - Proprioception and balance training - Walking program progression ### Return to Activity - Return to sedentary work: 2-4 weeks - Return to physical work: 3-4 months - Return to recreational sport: 6-9 months - Return to competitive sport: 9-12 months 1. 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. 2. Lobenhoffer P, Agneskirchner JD. Improvements in surgical technique of valgus high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc. 2003;11(3):132-138. 3. Staubli AE, De Simoni C, Babst R, Lobenhoffer P. TomoFix: a new LCP-concept for open wedge osteotomy of the medial proximal tibia. Injury. 2003;34 Suppl 2:B55-62. 4. Spahn G, Hofmann GO, von Engelhardt LV, et al. The impact of a high tibial valgus osteotomy and target mechanical axis realignment on the treatment of knee osteoarthritis: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2013;21(1):96-112. 5. Brinkman JM, Lobenhoffer P, Agneskirchner JD, et al. Osteotomies around the knee: patient selection, stability of fixation and bone healing in high tibial osteotomies. J Bone Joint Surg Br. 2008;90(12):1548-1557. 6. Schröter S, Nakayama H, Ihle C, et al. Factors influencing accuracy in high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc. 2019;27(7):2090-2097. 7. Kim JH, Kim HJ, Lee DH. Survival of opening versus closing wedge high tibial osteotomy: a meta-analysis. Sci Rep. 2017;7(1):7296. 8. Amendola A, Bonasia DE. Results of high tibial osteotomy: review of the literature. Int Orthop. 2010;34(2):155-160. 9. Coventry MB, Ilstrup DM, Wallrichs SL. Proximal tibial osteotomy. A critical long-term study of eighty-seven cases. J Bone Joint Surg Am. 1993;75(2):196-201. 10. Floerkemeier S, Staubli AE, Schroeter S, et al. Outcome after high tibial open-wedge osteotomy: a retrospective evaluation of 533 patients. Knee Surg Sports Traumatol Arthrosc. 2013;21(1):170-180.

Medial Opening Wedge High Tibial Osteotomy

Medial Opening Wedge High Tibial Osteotomy