import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: HTO - popliteal artery and vein lie 1-2cm posterior to posterior tibial cortex at level of osteotomy **Protection Strategy**: Confirm all screw lengths on lateral fluoroscopy before insertion. Use depth gauge for every screw. Never breach posterior cortex. Keep osteotomy cuts anterior to posterior cortex safe zone. **Location**: Wraps around fibular neck 2-3cm distal and lateral to knee joint line, stays within 1-2cm of posterolateral joint margin **Protection Strategy**: Limit lateral dissection in HTO. For closing wedge requiring fibular osteotomy, identify and protect nerve. Avoid excessive valgus correction >15mm causing stretch injury. **Location**: Courses posteromedially 5-10cm from midline, runs posterior to pes anserinus insertion in superficial subcutaneous plane **Protection Strategy**: Identify early during medial approach to HTO. Gentle retraction only. Avoid aggressive cautery. Split or elevate pes anserinus as flap to protect neurovascular bundle. **Location**: Inserts on anterior tibial tubercle, forms anterior boundary of HTO dissection, at risk during opening if ascending cut not performed **Protection Strategy**: Use biplanar technique with ascending cut posterior to tubercle. This allows opening without stretching tendon. Maintain 1cm bone thickness for TTO to prevent avulsion. **Location**: DFO - inserts on lateral femoral epicondyle, retracts posteriorly during lateral approach to distal femur **Protection Strategy**: Identify LCL during exposure and retract gently posteriorly. Subperiosteal dissection anterior to LCL between vastus lateralis and ligament. Avoid deep posterior dissection. ## Indications ### High Tibial Osteotomy (HTO) - **Primary indication**: Medial compartment osteoarthritis or chondral defect with varus malalignment - **Patient selection**: Young active patients <60-65 years - **Deformity**: Varus malalignment with mechanical axis passing through medial compartment - **Joint status**: Isolated medial compartment disease, intact lateral compartment - **Range of motion**: >90° flexion required - **Stability**: Intact or reconstructable ligaments (ACL/PCL) - **Activity level**: Desire to maintain or return to impact activities - **Failed conservative management**: Physiotherapy, injections, bracing, weight loss ### Distal Femoral Osteotomy (DFO) - **Primary indication**: Lateral compartment osteoarthritis or chondral defect with valgus malalignment - **Patient selection**: Young active patients <60 years (less common than HTO) - **Deformity**: Valgus malalignment with mechanical axis passing through lateral compartment - **Joint status**: Isolated lateral compartment disease, intact medial compartment - **Extra-articular deformity**: Femoral-based valgus deformity - **Combined with HTO**: For double-level osteotomy in severe deformity ### Tibial Tubercle Osteotomy (TTO) - **Primary indication**: Patellofemoral osteoarthritis or chondrosis with patellar maltracking or overload - **Patient selection**: Young patients <50-55 years - **Pathology**: Isolated patellofemoral compartment disease - **Maltracking**: Lateral patellar tilt, subluxation (J-sign), alta or baja - **Chondral damage**: Focal lateral or distal patellar lesions - **Failed conservative management**: Physiotherapy, bracing, activity modification ## Contraindications ### Absolute Contraindications - Inflammatory arthritis (rheumatoid, psoriatic) - systemic disease continues - Severe tricompartmental osteoarthritis - osteotomy ineffective - Active infection - local or systemic - Severe peripheral vascular disease - healing concerns - Patient unable to comply with protected weight-bearing protocol ### Relative Contraindications - Age >65 years - consider arthroplasty instead - Obesity (BMI >35) - increased failure rate, delayed healing - Current smoker - doubles non-union risk - Flexion contracture >15° - limits functional improvement - Ligamentous instability - address concurrently or contraindication - Significant patellofemoral arthritis (for HTO/DFO) - may worsen symptoms - Unrealistic patient expectations ## Preoperative Planning - CRITICAL for Success ### Long Leg Standing Radiographs - **Technique**: Full weight-bearing, hip-knee-ankle on single 51-inch cassette - **Patient position**: Feet shoulder-width apart, knees straight, patella forward - **Image quality**: Must visualize center of femoral head, knee joint, ankle joint ### Mechanical Axis Measurement 1. **Draw mechanical axis**: Line from center of femoral head to center of talus 2. **Measure MAD** (Mechanical Axis Deviation): Distance (mm) from mechanical axis to center of knee - Varus: Axis passes medial to knee center (positive MAD) - Valgus: Axis passes lateral to knee center (negative MAD) 3. **Calculate percentage**: Where axis crosses tibial plateau (0% = medial edge, 100% = lateral edge) - Normal: 50% (axis through knee center) - Varus OA: Typically 20-30% (medial overload) - Valgus OA: Typically 70-80% (lateral overload) ### Target Correction - **HTO for varus**: Fujisawa point 62-66% lateral tibial plateau width - Corresponds to 3-5° valgus mechanical axis - Slight overcorrection unloads medial compartment - **DFO for valgus**: Target 55-60% medial (slight varus) - Unloads lateral compartment - **Undercorrection = early failure** - **Excessive overcorrection = opposite compartment overload** ### Correction Angle Calculation Methods **Miniaci Method**: Trigonometric calculation based on tibial plateau width and desired shift of mechanical axis **Dugdale Method**: Geometric method using mechanical axis shift **Digital Planning Software**: TraumaCad, Orthoview - most accurate, allows templating ### Additional Imaging - **CT scan**: If intra-articular deformity suspected - **MRI**: Assess cartilage status, meniscus, ligaments, bone marrow edema - **Stress X-rays**: Evaluate correctability of deformity ## Regional Anatomy - Proximal Tibia (HTO) ### Bony Landmarks - **Medial tibial plateau**: Articular surface, joint line palpable - **Tibial tubercle**: Anterior prominence, patellar tendon insertion - **Pes anserinus insertion**: Posteromedial, 4-6cm below joint line - **Fibular head**: Lateral, common peroneal nerve wraps around neck - **Posterior tibial cortex**: 1-2cm anterior to popliteal vessels ### Osteotomy Safe Zone - **Starting point**: 4-5cm below joint line (medial cortex) - **Direction**: Aimed toward fibular head (proximal-lateral) - **Endpoint**: 1cm from lateral cortex (CRITICAL - this is the hinge) - **Slope**: 5-10° posterior angulation (matches native posterior tibial slope) - **Biplanar cuts**: Horizontal + ascending (prevents patella baja) ### Soft Tissue Anatomy - **Pes anserinus**: Gracilis, semitendinosus, sartorius - insert posteromedially - **MCL superficial fibers**: Just deep to pes, must preserve - **Saphenous nerve and vein**: Posteromedial 5-10cm from midline - **Patellar tendon**: Anterior boundary, inserts on tibial tubercle - **Popliteal vessels**: Posterior to tibia, 1-2cm behind posterior cortex ## Regional Anatomy - Distal Femur (DFO) ### Bony Landmarks - **Lateral femoral condyle**: Palpable prominence - **Lateral epicondyle**: LCL insertion - **Distal femoral metaphysis**: Osteotomy site 6-7cm above joint line - **Medial cortex**: Hinge location for opening wedge DFO ### Osteotomy Safe Zone - **Starting point**: 6-7cm above joint line (lateral cortex) - **Direction**: Aimed medially toward opposite cortex - **Endpoint**: 1cm from medial cortex (hinge) - **Frontal plane**: Perpendicular to mechanical axis ### Soft Tissue Anatomy - **Iliotibial band**: Overlies lateral femur, incise in line with fibers - **Vastus lateralis**: Anterior boundary, elevate off intermuscular septum - **Lateral collateral ligament**: Inserts on lateral epicondyle, retracts posteriorly - **Common peroneal nerve**: Deep posterior, usually safe if stay anterior - **Superior lateral genicular vessels**: Cross proximal to osteotomy site ## Regional Anatomy - Tibial Tubercle (TTO) ### Bony Landmarks - **Tibial tubercle**: Anterior prominence of proximal tibia - **Patellar tendon insertion**: Broad insertion on tubercle - **Anterior tibial cortex**: 1cm thick bone beneath tubercle minimum - **Tibial articular surface**: Risk of propagation if osteotomy too shallow ### Osteotomy Design - **Length**: 5-6cm distal from proximal extent of tubercle - **Thickness**: Maintain minimum 1cm bone thickness beneath patellar tendon - **Direction**: - Anteriorization: Decreases patellofemoral contact force - Medialization: Corrects lateral maltracking - Combined anteromedial (Fulkerson): Most common - **Fixation**: Screws from anterior into posterior cortex ### Soft Tissue Anatomy - **Patellar tendon**: Broad insertion on tubercle, risk of avulsion if <1cm bone - **Anterior compartment**: Deep to incision, risk of bleeding/compartment syndrome - **Infrapatellar branch saphenous nerve**: Crosses tubercle, numbness common - **Pes anserinus**: Medial to tubercle ## Opening Wedge vs Closing Wedge HTO ## TTO Variations ### Anteriorization (Maquet) - **Indication**: Patellofemoral overload, diffuse chondrosis - **Mechanism**: Decreases patellofemoral contact force by increasing moment arm - **Transfer distance**: 10-15mm anterior - **Fixation**: Bone graft or cage to support elevation, screws or wire fixation ### Medialization - **Indication**: Lateral patellar maltracking, tilt, subluxation - **Mechanism**: Medializes Q-angle, corrects lateral vector - **Transfer distance**: 5-10mm medial - **Risk**: Excessive medialization causes medial overload ### Anteromedial Transfer (Fulkerson) - **Indication**: Combined lateral maltracking AND overload/chondrosis - **Mechanism**: Combines benefits of anteriorization and medialization - **Technique**: Oblique osteotomy cut from distal-posterior to proximal-anterior - **Transfer**: 10-15mm anterior, 5-10mm medial - **Most common TTO technique currently** ### Distalization - **Indication**: Patella alta with instability - **Mechanism**: Lowers patella into trochlea, improves engagement - **Transfer distance**: Variable, to normalize Insall-Salvati ratio (0.8-1.2) - **Risk**: Increases patellofemoral contact force ## Combination Procedures ### HTO + ACL Reconstruction - **Indication**: Varus malalignment contributing to ACL insufficiency or graft failure - **Timing**: Can perform simultaneously or staged - **Sequence**: Typically HTO first, then ACL reconstruction - **Consideration**: HTO may improve ACL graft kinematics ### HTO + Meniscus Transplant - **Indication**: Varus malalignment with medial meniscus deficiency - **Rationale**: Correct alignment to protect transplanted meniscus - **Timing**: Simultaneous or staged - **Sequence**: HTO first to optimize mechanical environment for transplant ### HTO + Cartilage Restoration (ACI, OATS) - **Indication**: Focal chondral defect with malalignment - **Rationale**: Unload compartment with cartilage procedure - **Evidence**: Better outcomes for cartilage procedures with corrected alignment - **Sequence**: Typically HTO first or simultaneous ### Double-Level Osteotomy (HTO + DFO) - **Indication**: Severe deformity >20° with contribution from tibia AND femur - **Rationale**: Address deformity at source (divide correction between joints) - **Complexity**: Higher complication risk, longer rehabilitation - **Alternative**: Consider arthroplasty in many cases ## High Tibial Osteotomy Outcomes ### Survival Rates - **5 years**: 90-95% survival (delay in TKA) - **10 years**: 70-80% survival - **15 years**: 60-70% survival - **20 years**: 50-60% survival - **Definition of failure**: Progression to TKA or persistent symptoms ### Prognostic Factors for Success - **Age <55 years**: Better outcomes, longer survival - **Preoperative Kellgren-Lawrence grade 2-3**: Better than grade 4 - **Accurate correction to target (Fujisawa 62-66%)**: Critical for success - **Normal BMI**: Obesity associated with higher failure rate - **Non-smoker**: Smoking doubles non-union risk - **Concurrent meniscus treatment**: Improves outcomes if addressed - **Ligamentous stability**: ACL/PCL instability worsens outcomes ## Distal Femoral Osteotomy Outcomes ### Survival Rates - **5 years**: 85-90% survival - **10 years**: 70-75% survival - **Less data than HTO** due to lower frequency of procedure ## Tibial Tubercle Osteotomy Outcomes ### Clinical Results - **Good-excellent results**: 70-80% at 5 years for patellofemoral symptoms - **Pain improvement**: 60-70% significant reduction in anterior knee pain - **Failure rate**: 20-30% persistent symptoms or progression to patellofemoral arthroplasty - **Best outcomes**: Isolated lateral facet lesions with maltracking ## Complications Data ### Meta-Analysis of HTO Complications - **Lateral hinge fracture**: 10-25% (most common, types I-III) - **Delayed union/non-union**: 5-10% (higher with large gaps, smoking) - **Infection**: 1-3% (hardware and dead space increase risk) - **Neurovascular injury**: <1% (popliteal vessels, common peroneal nerve) - **Loss of correction**: 5-8% (fixation failure, inadequate initial correction) - **Symptomatic hardware**: 15-25% (often requires removal) - **Compartment syndrome**: <1% (higher with TTO) ## Cost-Effectiveness ### Economic Analysis - **HTO delays TKA by average 10-15 years** in successful cases - **Cost per QALY**: Favorable compared to TKA in patients <55 years - **Consideration**: Maintains bone stock, allows higher activity level during "bridge" period - **Eventual TKA**: Most patients eventually require arthroplasty but at older age ## Step 1: Preoperative Planning - Mechanical Axis and Correction Angle **CRITICAL PLANNING STEP**: Standing LONG LEG RADIOGRAPHS (hip-knee-ankle) with patient weight-bearing required. Measure current mechanical axis line (center of femoral head to center of ankle). Document mechanical axis deviation (MAD) - how many mm medial or lateral of knee center. Determine percentage of tibial plateau width where axis passes. **TARGET CORRECTION**: - HTO for varus: Fujisawa point 62-66% lateral (3-5° valgus) - DFO for valgus: 55-60% medial (slight varus) **Calculate CORRECTION ANGLE using**: - Miniaci method: Trigonometric calculation - Dugdale method: Geometric approach - Digital planning software (TraumaCad, Orthoview): Most accurate Consider wedge SIZE: opening wedge HTO typically 8-15mm gap, closing wedge removes 8-15mm. Plan screw trajectory and plate position. Templating with digital software ideal. **Technical Tip**: EXAM KEY: 'Planning on LONG LEG STANDING films is CRITICAL. I calculate mechanical axis currently (varus measures MAD medial to knee center), and TARGET axis (Fujisawa point 62-66% lateral for HTO = 3-5° valgus mechanical axis). This determines correction angle. I use Miniaci or digital planning. Undercorrection fails quickly; overcorrection overloads opposite compartment. Goal: neutral to slight overcorrection.' - Undercorrection = persistent overload, early failure (MOST COMMON planning error) - Overcorrection = overload opposite compartment, poor outcomes - Incorrect mechanical axis measurement (ensure full weight-bearing films) - Inadequate planning = intraoperative guessing ## Step 2: Patient Positioning and Fluoroscopy Setup Position supine with bump under ipsilateral hip (internal rotation exposes medial tibia for HTO or lateral femur for DFO). Radiolucent triangle bolster at distal thigh allows knee flexion. Prep and drape entire limb from groin to toes with leg free. Test C-arm imaging: obtain PERFECT AP and LATERAL views of proximal tibia (HTO) or distal femur (DFO) - must see joint line and osteotomy site clearly. Ensure ability to obtain full-length hip-to-ankle AP view intraoperatively for final alignment check. Mark anatomic landmarks on skin: joint line, pes anserinus, patellar tendon, tibial tubercle, fibular head. **Technical Tip**: EXAM KEY: 'Perfect imaging is essential for accuracy. I test C-arm positioning before incision - need clear AP and lateral of osteotomy site AND ability to get full hip-to-ankle view for final alignment check. Bump under hip rotates limb internally exposing medial tibia. I mark key landmarks before draping to guide incision placement.' - Inadequate fluoroscopy setup = inability to confirm correction intraoperatively - Poor AP/lateral views = malpositioned osteotomy or hardware - Unable to obtain full-length view = unknown final alignment ## Step 3: Surgical Approach and Exposure - HTO **FOR OPENING WEDGE HTO (most common)**: Longitudinal or oblique incision 6-8cm over anteromedial proximal tibia, starting at joint line and extending distally. Identify and protect SAPHENOUS NERVE and vein (posterior to pes anserinus). Identify PES ANSERINUS (gracilis, semitendinosus, sartorius) - elevate as flap or split. Expose medial proximal tibia from posteromedial corner to anterior (protect patellar tendon insertion anteriorly). Subperiosteal elevation. Palpate POSTERIOR BORDER of tibia to ensure complete medial exposure. **FOR CLOSING WEDGE HTO (less common)**: Similar approach but may need fibular osteotomy first for lateral closing. **Technical Tip**: EXAM KEY: 'For OPENING WEDGE HTO, I use anteromedial approach. I identify and protect saphenous nerve posteriorly. Pes anserinus identified - can elevate as flap or split through. COMPLETE medial exposure from posteromedial corner to anterior, staying subperiosteal. I palpate posterior border to confirm exposure - important for guide wire trajectory.' - Saphenous nerve injury (posterior to pes, 5-10cm from midline) - MCL injury (deep fibers insert on tibia) - Patellar tendon injury (anterior boundary) - Inadequate exposure = malpositioned osteotomy ## Step 4: Surgical Approach and Exposure - DFO **FOR DISTAL FEMORAL OSTEOTOMY**: Lateral longitudinal incision 8-10cm over distal lateral femoral metaphysis, from lateral epicondyle extending proximally. Incise fascia lata and iliotibial band in line with fibers. Identify and protect LATERAL COLLATERAL LIGAMENT (LCL) - typically retracts posteriorly. Elevate vastus lateralis off lateral intermuscular septum (anterior) and identify posterior border. Subperiosteal exposure of lateral distal femur. Stay anterior to LCL and posterior to vastus. Expose adequately for plate placement. **Technical Tip**: EXAM KEY: 'For DFO lateral approach, I incise through IT band over distal femur. Identify and protect LCL posteriorly. Subperiosteal elevation between vastus lateralis anteriorly and LCL/posterior structures. Need adequate exposure for distal femoral locking plate placement.' - LCL injury (causes valgus instability) - Common peroneal nerve (deeper, posterior - usually not at risk unless dissect posteriorly) - Vastus lateralis denervation from aggressive dissection - Inadequate anterior or posterior exposure ## Step 5: Guide Wire Placement and Osteotomy Planning - HTO **CRITICAL STEP FOR HTO**: Place guide wire on MEDIAL cortex 4-5cm below JOINT LINE (measured on fluoroscopy), angled toward FIBULAR HEAD (lateral and proximal), stopping 1cm from LATERAL CORTEX (this will be the hinge). Wire trajectory is 5-10° posterior-to-anterior angulation (matches posterior tibial slope). Confirm wire position on BOTH AP (toward fibular head, 1cm from lateral cortex) and LATERAL (parallel to joint, respecting slope). Wire serves as guide for osteotomy cut. This wire position is CRITICAL for proper hinge location and avoiding complications. **Technical Tip**: EXAM KEY: 'Guide wire is CRITICAL - determines osteotomy trajectory. I place wire 4-5cm below joint line on medial cortex, aim toward fibular head, stop 1cm from lateral cortex. That lateral cortex is my HINGE - must preserve or get hinge fracture. I confirm on AP (toward fibular head) and lateral (parallel to joint, respects slope). Wire typically 5-10° posterior slope matching native.' - Wire too close to joint line (<3.5cm) = intra-articular fracture - Wire too distal (>6cm) = stress riser, fracture risk - Wire violates lateral cortex = NO hinge, unstable osteotomy - Wire not parallel to joint = alters tibial slope - Wire too anterior or posterior = non-anatomic ## Step 6: Osteotomy Cut - Biplanar Technique HTO **BIPLANAR OPENING WEDGE TECHNIQUE**: Using oscillating saw along guide wire, make HORIZONTAL cut from medial cortex toward lateral, stopping 1cm from lateral cortex (preserve hinge). Cut depth approximately 75-80% of tibial width. **Second cut**: ASCENDING cut posterior and proximal behind patellar tendon insertion (anterior to horizontal cut level) - this protects patellar tendon during opening and prevents patella baja. The ascending cut angles 15-20° posterior. Use multiple osteotomes to complete cut but DO NOT breach lateral cortex hinge. Check mobility before full completion. **Technical Tip**: EXAM KEY: 'BIPLANAR cut: HORIZONTAL along wire to 1cm from lateral cortex, then ASCENDING cut behind patellar tendon. The ascending cut is KEY - protects patellar tendon during opening and prevents patella BAJA (common complication of HTO). I use saw for cortical cuts, then multiple osteotomes to complete, checking mobility progressively but preserving hinge.' - Lateral hinge fracture (MOST COMMON complication HTO, 10-25%) - Patellar tendon injury (ascending cut prevents this) - Intra-articular fracture (wire/cut too proximal) - Posterior cortex fracture (aggressive osteotome use) - Incomplete cut (prevents opening) ## Step 7: Osteotomy Cut - DFO Technique **FOR DISTAL FEMORAL OSTEOTOMY**: Place guide wire on LATERAL cortex 6-7cm PROXIMAL to joint line, angled toward medial cortex, stopping 1cm from medial cortex (hinge). Confirm on AP and lateral fluoroscopy. **For OPENING WEDGE DFO (more common now)**: Saw cut along wire to 1cm from medial cortex. Progressive osteotome completion preserving medial hinge. **For CLOSING WEDGE DFO**: Mark wedge based on planned correction angle, make two saw cuts converging laterally, remove bone wedge, close osteotomy. **Technical Tip**: EXAM KEY: 'For DFO, guide wire 6-7cm ABOVE joint line on lateral cortex, aimed toward medial, stop 1cm from medial cortex (that's the hinge). Opening wedge DFO now more common than closing. Principles same as HTO but on femur: preserve hinge, adequate fixation with locking plate, gradual opening.' - Medial hinge fracture in DFO - Supracondylar fracture into joint - Neurovascular injury (femoral vessels medially, avoid deep dissection) - Inadequate fixation in distal femoral bone (osteoporotic) ## Step 8: Gradual Osteotomy Opening and Alignment Correction Insert calibrated SPREADER into osteotomy cut. GRADUALLY open in 1-2mm increments - slow opening protects hinge from fracture. Open to PRE-CALCULATED correction. **Intraoperative alignment check methods**: 1. **CABLE TEST**: Sterile cable from center of femoral head to center of ankle, should pass through Fujisawa point (62-66% lateral) - use C-arm to verify 2. **INTRAOPERATIVE LONG LEG X-RAY** if available 3. Clinical assessment with limb alignment Adjust opening if needed for perfect correction. For CLOSING WEDGE: close osteotomy after wedge removal, align, check correction same methods. **Technical Tip**: EXAM KEY: 'I open GRADUALLY with calibrated spreaders - 1-2mm increments. Too rapid opening FRACTURES hinge. Open to calculated correction then CHECK alignment. CABLE TEST: sterile cable from hip center to ankle center, use C-arm to verify passes through Fujisawa point (62-66% for HTO). Intraop long leg film is gold standard but not always available. Fine-tune opening if needed.' - Rapid opening = hinge fracture (COMMON) - Undercorrection = failure to offload compartment - Overcorrection = overload opposite compartment, stiffness - No intraoperative alignment check = unknown final correction ## Step 9: Bone Graft or Substitute for Opening Wedge For OPENING WEDGE gaps >10mm: Consider bone graft or substitute to promote healing and support correction. **Options**: 1. **AUTOGRAFT from iliac crest** (gold standard, best biology, donor site morbidity) 2. Local bone from tibial or femoral cuts if available 3. **ALLOGRAFT cancellous chips** (no donor morbidity, osteoconductive) 4. **BONE SUBSTITUTE** (calcium phosphate, hydroxyapatite - osteoconductive but slower incorporation) Wedges <10mm often heal without graft. Place graft to support medial opening (HTO) or lateral opening (DFO), behind and beneath plate. **Technical Tip**: EXAM KEY: 'For gaps >10mm I use bone graft or substitute. ALLOGRAFT cancellous chips are my preference - no donor morbidity, reliable healing. Autograft iliac crest is gold standard but donor site pain. Synthetic substitutes work but slower. Wedges <8-10mm often heal without graft. Graft supports correction and promotes faster healing, reduces non-union risk (5-10% without graft in large gaps).' - Large gap without graft = delayed union or non-union (5-10%) - Graft collapse = loss of correction - Iliac crest donor site morbidity (pain, hematoma, infection) if autograft ## Step 10: Internal Fixation - Locking Plate Application **HTO**: Apply medial proximal tibial LOCKING PLATE (Tomofix, Puddu, numerous brands available). Plate contours to medial tibia. Secure plate to tibia first with proximal locking screws (typically 3-4 screws in proximal metaphyseal segment above osteotomy) and distal screws (3-4 screws in diaphysis below osteotomy). Locking screws provide angular stability - critical in metaphyseal bone. Confirm screw lengths don't penetrate posterior cortex (risk to popliteal vessels) or lateral cortex (hinge damage). **DFO**: Apply lateral distal femoral LOCKING PLATE. Proximal screws in femoral shaft, distal screws in distal metaphyseal fragment. Similar principles. Confirm alignment and fixation on fluoroscopy. **Technical Tip**: EXAM KEY: 'LOCKING PLATES essential for angular stability in metaphyseal bone. For HTO, medial plate with 3-4 screws proximal and distal to osteotomy. Check screws on LATERAL fluoroscopy - must not penetrate posterior cortex (popliteal vessels risk). Locking technology allows better purchase in osteoporotic or metaphyseal bone compared to conventional plates.' - Screws too long penetrating posterior cortex (HTO - popliteal vessels 1-2cm posterior) - Screws violating lateral hinge (causes fracture) - Screws into joint (proximal screws must be below joint line) - Inadequate fixation (too few screws, non-locking in poor bone) - Plate malposition (not contoured, proud, irritation) - Loss of correction due to fixation failure ## Step 11: Tibial Tubercle Osteotomy (TTO) - Anteriorization or Medialization **FOR PATELLOFEMORAL OVERLOAD/MALTRACKING**: TTO ANTERIORIZATION (Fulkerson osteotomy): Anterior approach or anterolateral approach to tibial tubercle. Mark tibial tubercle and patellar tendon insertion. Create oblique osteotomy of tubercle starting distally and angling anteriorly and medially (anteromedial transfer). Osteotomy 5-6cm long, maintaining 1cm bone thickness beneath tubercle. Transfer tubercle anteriorly 10-15mm (decreases patellofemoral contact forces) and/or medially 5-10mm (corrects lateral maltracking). Fix with 3-4 cortical screws from anterior tubercle into tibia. TTO DISTALIZATION less common, for patella alta. Ensure no posterior cortex violation (popliteal vessels). **Technical Tip**: EXAM KEY: 'TTO for patellofemoral pathology. FULKERSON anteromedial transfer: tubercle osteotomy angled anteriorly and medially. ANTERIORIZATION decreases patellofemoral contact force (treats chondrosis/arthritis). MEDIALIZATION corrects LATERAL maltracking (J-sign, subluxation). Typically combined anteromedial. 5-6cm osteotomy length, maintain 1cm bone thickness, fix with screws. Transfer 10-15mm anterior and/or 5-10mm medial.' - Fracture propagation into tibial articular surface - Patellar tendon avulsion (inadequate bone thickness, <1cm) - Compartment syndrome (anterior compartment swelling from bleeding) - Hardware irritation (screws prominent anteriorly) - Insufficient correction (inadequate transfer) - Excessive medialization (medial overload) ## Step 12: Final Alignment Check and ROM Assessment **CRITICAL STEP**: Final intraoperative alignment verification. **Options**: 1. **CABLE TEST with C-arm** - cable from hip to ankle, document mechanical axis passing through target (Fujisawa 62-66% for HTO, 55-60% for DFO) 2. **INTRAOPERATIVE LONG LEG STANDING X-RAY** if available (most accurate) 3. Clinical assessment - limb appears aligned, varus/valgus stress test neutral Cycle knee through FULL ROM - smooth? No impingement? Hardware not limiting ROM? Test stability - osteotomy site stable? Check neurovascular status. Document final fluoroscopic images of alignment and hardware position. **Technical Tip**: EXAM KEY: 'FINAL ALIGNMENT CHECK is essential - I've opened/corrected to plan but must VERIFY. Cable test with C-arm or intraop long leg film confirms mechanical axis at target. Cycle knee through ROM - should be smooth, no impingement. Test stability - osteotomy doesn't move. Any concerns, address before closure. Undercorrection is failure; overcorrection causes problems. Must get it right NOW.' - Undercorrection not recognized (early failure) - Overcorrection not recognized (opposite compartment overload) - Loss of correction during final steps - ROM limitation not recognized - Neurovascular injury not identified ## Step 13: Closure and Post-Operative Protocol Release tourniquet if used. Achieve meticulous hemostasis - minimize hematoma risk. **For HTO**: Close pes anserinus fascia over plate (soft tissue coverage). **For DFO**: Close vastus lateralis and IT band. **For TTO**: Close anterior compartment fascia (watch for compartment tightness). Subcutaneous closure, skin closure. Drain optional (remove 24-48 hours if used). Apply compressive dressing. HINGED KNEE BRACE for protection and to allow ROM exercises. **Post-op**: Elevation and ice. X-rays to document correction and hardware position. DVT prophylaxis. Pain control. **Technical Tip**: EXAM KEY: 'Meticulous hemostasis important - hematoma delays healing. I close pes fascia over plate for HTO (soft tissue coverage). Hinged brace allows protected ROM while preventing varus/valgus stress. Post-op X-rays document correction and hardware. For TTO, monitor for compartment syndrome in first 24 hours (anterior compartment at risk).' - Hematoma (delayed healing, infection risk) - Wound complications (especially over plate/hardware) - Compartment syndrome (especially TTO - anterior compartment) - Hardware irritation (prominent plate/screws) - DVT/PE risk ## Step 14: Rehabilitation - Protected Weight Bearing Protocol **PHASE 1 (0-6 weeks)**: NWB or TOUCH weight-bearing (TWB) with crutches to protect osteotomy healing. Hinged brace for ambulation. ROM exercises in brace - goal 0-90° by 2 weeks, full ROM by 6 weeks. Quad sets, ankle pumps, gentle isometrics. NO varus/valgus stress. X-rays at 6 weeks to assess healing. **PHASE 2 (6-12 weeks)**: If X-ray shows healing progressing (callus formation), advance to PWB (50% then 75%). Wean crutches as tolerated. Continue ROM and strengthening. **PHASE 3 (3-6 months)**: FWB by 10-12 weeks if healed. Wean brace. Progressive strengthening, balance, proprioception. Stationary bike, swimming. X-rays at 3 months confirm healing. **Technical Tip**: EXAM KEY: 'Protected weight-bearing 6-12 weeks until HEALING CONFIRMED on X-ray - looking for bridging callus, no gap widening. Opening wedge heals slower than closing (larger bone void). ROM encouraged early - helps cartilage and prevents stiffness. FWB when healed, typically 10-12 weeks. Return to impact activities 6-9 months, sport 9-12 months. Brace protects osteotomy from varus/valgus stress during healing.' - Early weight-bearing = loss of correction, non-union (5-10%) - Delayed union or non-union (5-10% overall, higher in large gaps without graft, smokers) - Stiffness from inadequate ROM exercises - Return to sport too early = fixation failure or re-injury ## Step 15: Hardware Removal and Long-term Outcomes **HARDWARE REMOVAL**: Typically elective after 12-18 months once fully healed and remodeled. Indications: hardware irritation (common with medial HTO plates - superficial position), patient request, pre-planned removal. Can often leave hardware if asymptomatic. **LONG-TERM OUTCOMES**: HTO for medial compartment OA: 70-80% survival at 10 years, 60-70% at 15 years. Best outcomes: younger patients (<55), corrected to target alignment, minimal baseline arthritis, addressed concurrent pathology. DFO: similar 70-75% at 10 years. TTO: 70-80% good results for patellofemoral symptoms. **FAILURE**: Gradual loss of correction, progression of arthritis, requires TKA eventually. Osteotomy DELAYS but doesn't prevent arthroplasty - buys 10-15 years in ideal patients. **Technical Tip**: EXAM KEY: 'Hardware removal is common 12-18 months after HTO - plate is superficial, can be prominent. Outcomes: 70-80% survival at 10 years. HTO/DFO is BRIDGE procedure in young patients - delays TKA by 10-15 years in best cases. Not curative but protective. Best outcomes: young <55, mild-moderate arthritis, accurate correction to target, addressed instability/meniscus. Failure from undercorrection, progression of arthritis, or overcorrection damage to opposite compartment. Eventual TKA typically easier after prior osteotomy.' - Hardware failure requiring early removal (infection, loosening) - Difficulty with removal after full incorporation - Eventual need for TKA (osteotomy delays but doesn't prevent) - TKA after osteotomy may be more complex (altered anatomy, hardware) **PHASE 1 (0-6 weeks)**: NWB or TWB with crutches, hinged knee brace for ambulation, ROM exercises 0-90° by 2 weeks goal (full by 6 weeks), quad sets and gentle isometrics, NO varus/valgus stress, elevation and ice, DVT prophylaxis, X-rays at 6 weeks for healing assessment. **PHASE 2 (6-12 weeks)**: If healing on X-ray (callus formation, no gap widening), progressive PWB 50-75-100%, wean crutches as tolerated, continue ROM to full, progressive strengthening (closed chain preferred), stationary bike when 90° flexion. **PHASE 3 (3-6 months)**: FWB by 10-12 weeks if healed on X-ray, wean brace by 3-4 months, advanced strengthening and balance, swimming and elliptical, functional activities, X-ray at 3 months confirms healing. **PHASE 4 (6-12 months)**: Return to impact activities 6-9 months (jogging, sports), full return to sport 9-12 months when strength >90%, full ROM, no pain/effusion. Hardware removal optional 12-18 months if symptomatic. Annual X-rays first 3-5 years to monitor alignment and arthritis progression. ## References 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. (Original description of Fujisawa point as target for HTO correction) 2. **Miniaci A, Ballmer FT, Ballmer PM, Jakob RP.** Proximal tibial osteotomy: a new fixation device. *Clin Orthop Relat Res.* 1989;246:250-259. (Miniaci method for calculating correction angle in HTO planning) 3. **Smith JO, Wilson AJ, Thomas NP.** Osteotomy around the knee: evolution, principles and results. *Knee Surg Sports Traumatol Arthrosc.* 2013;21(1):3-22. (Comprehensive review of knee osteotomy techniques, indications, and outcomes) 4. **Takeuchi R, Ishikawa H, Kumagai K, et al.** Fractures around the lateral cortical hinge after a medial opening-wedge high tibial osteotomy: a new classification of lateral hinge fracture. *Arthroscopy.* 2012;28(1):85-94. (Classification of lateral hinge fractures - types I-III with management implications) 5. **Van den Bempt M, Van Genechten W, Claes T, Claes S.** How to get realistic expectations in high tibial osteotomy for medial compartment osteoarthritis: a systematic review of patient selection criteria. *Knee Surg Sports Traumatol Arthrosc.* 2020;28(12):3849-3857. (Evidence-based patient selection criteria and prognostic factors for HTO success) 6. **Elson DW, Petheram TG, Dawson MJ.** High reliability in digital planning of medial opening wedge high tibial osteotomy, using Miniaci's method. *Knee Surg Sports Traumatol Arthrosc.* 2015;23(7):2041-2048. (Digital planning methods for HTO with high accuracy and reliability) 7. **Putman S, Boureau F, Girard J, Migaud H, Pasquier G.** Patellar height after opening-wedge high tibial osteotomy: comparison between biplanar osteotomy and single-cut osteotomy. *Orthop Traumatol Surg Res.* 2013;99(8):887-894. (Evidence supporting biplanar technique to prevent patella baja complication) 8. **Lobenhoffer P, Agneskirchner JD.** Improvements in surgical technique of valgus high tibial osteotomy. *Knee Surg Sports Traumatol Arthrosc.* 2003;11(3):132-138. (Technical refinements in opening wedge HTO including TomoFix plate application) 9. **Saithna A, Kundra R, Getgood A, Spalding T.** Opening wedge distal femoral varus osteotomy for lateral compartment osteoarthritis in the valgus knee. *Knee.* 2014;21(1):172-175. (Technique and outcomes for DFO in lateral compartment OA with valgus malalignment) 10. **Fulkerson JP, Becker GJ, Meaney JA, Miranda M, Folcik MA.** Anteromedial tibial tubercle transfer without bone graft. *Am J Sports Med.* 1990;18(5):490-496. (Original description of Fulkerson osteotomy for patellofemoral disorders - anteromedial transfer technique)

Comprehensive Knee Osteotomy: HTO, DFO, and TTO

Comprehensive Knee Osteotomy: HTO, DFO, and TTO