import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: 10-15mm posterior to posterior tibial cortex, even closer with posterior bone loss **Protection**: Maintain knee flexion when working posteriorly, use retractors to protect posterior structures, gentle cement removal technique, avoid aggressive posterior osteotome use **Risk**: 0.1-0.3% injury rate (3-10x higher than primary), devastating if unrecognized **Location**: Around fibular neck, at risk with lateral exposure and valgus correction **Protection**: Gradual deformity correction, avoid forced lengthening, identify nerve if severe valgus, warn patient pre-operatively **Risk**: 2-5% palsy rate (4-10x higher than primary), especially with hinged prostheses **Location**: Anterior insertion at tibial tubercle, vulnerable during patella eversion **Protection**: NEVER force eversion, adequate medial/lateral releases, perform quadriceps snip or TTO if difficult, maintain 15mm patellar composite **Risk**: 1-3% avulsion rate, catastrophic complication with 50-70% residual extensor lag **Location**: MCL femoral origin 3-4mm proximal/posterior to medial epicondyle, LCL at lateral epicondyle **Protection**: Careful soft tissue handling with scar tissue, avoid overzealous releases, assess integrity and match constraint **Risk**: Iatrogenic injury requires increased constraint, impacts stability and outcomes **Location**: Posterior to femoral condyles and tibial plateau **Protection**: Gentle cement removal, controlled flexion during exposure, retractor placement under direct vision **Risk**: Disruption causes instability, bleeding, and potential vascular injury ## Indications for Revision TKR **Aseptic Loosening (28% of revisions per AOANJRR)** - Progressive pain with weight-bearing activity - Radiographic evidence of progressive radiolucency (>2mm at component-bone or component-cement interface) - Component subsidence or migration - Knee Society Score typically <60 points **Instability (22% of revisions)** - Flexion instability: tight extension gap, loose flexion gap - Extension instability: loose extension gap, tight flexion gap - Mid-flexion instability: femoral component undersized or malrotated - Global instability: inadequate constraint for ligamentous insufficiency **Infection (21% of revisions)** - Acute post-operative infection <3 weeks: DAIR considered - Chronic infection >3 weeks: two-stage revision gold standard - Elevated ESR/CRP, positive aspiration (>3000 WBC, >80% PMN) - Two-stage success rate 70-80%, DAIR 40-50% in revision setting **Polyethylene Wear and Osteolysis (12%)** - Visible wear on radiographs - Osteolytic lesions expanding - Backside wear with mobile-bearing designs - Address before catastrophic bone loss **Periprosthetic Fracture (8%)** - Supracondylar femur fracture (most common) - Tibial plateau fracture - Patellar fracture - Lewis and Rorabeck Type III requires revision with loose implant **Other Indications (9%)** - Component malposition causing pain, stiffness, or instability - Arthrofibrosis refractory to conservative management - Unexplained pain after exclusion of infection and malalignment ## Pre-operative Planning **Imaging Assessment** - Weight-bearing AP and lateral knee radiographs - Merchant view for patellofemoral assessment - Full-length hip-knee-ankle radiographs for alignment - **CT scan with metal artifact reduction**: invaluable for assessing 3D bone loss, component rotation, planning reconstruction - Consider SPECT-CT for painful TKR without obvious cause - MRI if extensor mechanism concern (tendon integrity) **Laboratory Investigation** - ESR and CRP mandatory to exclude infection - If elevated: knee aspiration (cell count, differential, culture) - Consider alpha-defensin or PJI biomarkers if high suspicion - Optimization: HbA1c <7.0%, albumin >3.5g/dL, vitamin D >30ng/mL **AORI Classification Assessment** - Type 1: Intact metaphyseal bone (minor defects) - Type 2A: Damaged metaphyseal bone, contained defect one side - Type 2B: Uncontained defect one condyle - Type 2C: Uncontained defects both condyles - Type 3: Severe metaphyseal damage affecting collateral attachments **Templating and Implant Planning** - Template component sizes (typically upsize 1-2 from primary) - Plan augment requirements (5mm, 10mm, 15mm wedges/blocks) - Determine stem lengths (typically 100-150mm press-fit) - Consider need for cones (Type 2C/3 defects) - Assess constraint requirements based on ligamentous integrity - Have backup implants available (increased constraint, hinges) **Australian Context**: AOANJRR data shows cumulative revision rate 9.2% at 15 years for primary TKR, with infection (28%), aseptic loosening (28%), and instability (22%) as leading causes requiring revision. Re-revision rate after first revision is 12% at 5 years, 18% at 10 years. ## Positioning and Preparation **Patient Position** - Supine on radiolucent table - Lateral thigh support prevents external rotation - Foot support allows full knee flexion - Consider bump under hip if fixed flexion contracture **Tourniquet Considerations** - Applied at 280-300mmHg thigh level - **Consider deferring inflation** given longer operative time (2-4 hours) - Alternative: lower pressure (250mmHg) with intermittent deflation - Have electrocautery ready for meticulous hemostasis - Tranexamic acid 1-2g IV reduces blood loss by 30-50% **Skin Incision Selection** - Use previous midline incision if possible (preserves blood supply) - If multiple scars: choose most lateral (preserves medial blood supply) - Extend proximally or distally as needed for exposure - Excise old scars if wide, non-viable, or adherent - Consider plastic surgery if skin compromise (multiple previous incisions, radiation) ## Arthrotomy and Exposure **Standard Medial Parapatellar Approach** - Incise through previous arthrotomy scar - Expect dense scar tissue and adhesions - Sharp dissection to recreate medial and lateral gutters - Identify and protect patellar tendon insertion throughout - Extend proximally into quadriceps tendon if needed **Assessment for Extensile Approach** - Attempt patella subluxation with knee flexion and tibial external rotation - **DO NOT force eversion** - risk of patellar tendon avulsion - If excessive tension on patella tendon, perform extensile approach **Quadriceps Snip (Most Common)** - 45° oblique incision from superolateral patella into vastus lateralis - Extends standard arthrotomy proximally and laterally - Allows patella eversion without tension - Repair side-to-side with strong interrupted sutures - Full weight-bearing allowed post-operatively **Tibial Tubercle Osteotomy (TTO)** - Reserve for severe patella baja or multiple previous surgeries - Osteotomize tubercle 5-6cm long with oscillating saw - Reflect medially with patellar tendon attached - Fixate with 2 screws at completion - Protected weight-bearing 6 weeks, brace recommended Patellar tendon avulsion is the most catastrophic complication in revision TKR with extremely poor outcomes. Never force patella eversion. Perform quadriceps snip or TTO liberally if difficult exposure. Maintain 15mm patellar composite thickness. Protect blood supply to patella and tendons with careful handling. ## Systematic Component Removal **Polyethylene Insert Removal First** - Facilitates access and joint mobility - Inspect wear pattern (gives clues to malposition, instability) - Eccentric wear suggests component malrotation - Posterior wear suggests flexion instability **Femoral Component Removal** - Usually easier to remove first - Insert thin flexible osteotomes at component-cement interface - Work circumferentially around component - Gigli saw technique for cement-bone interface if needed - Apply longitudinal extraction force with removal device - **Goal**: preserve bone stock, minimize bone loss **Tibial Component Removal** - May be more difficult with stems and keels - Osteotomes at component-cement interface - **Avoid leveraging against bone** - causes fracture - Work around keel or stem carefully - Be prepared for intra-operative tibial plateau fracture (5-10% incidence) - Manage fracture with longer stem extension (150-200mm) **Complete Cement Removal - Critical Step** - Use combination of tools: thin osteotomes, curettes, high-speed burr, ultrasonic cement removal - Posterior femoral cement most difficult to access - Use right-angle curettes, headlight, retractors for visualization - **Complete removal essential** for new component seating - Remove incrementally to avoid excessive bone loss - Pulse lavage to clear all debris **Technical Tip**: Gigli saw technique for cement removal: pass 0.035" guidewire posterior to femur using curved awl, thread Gigli saw over wire, oscillate saw at cement-bone interface preserving bone stock. Especially useful for well-fixed posterior cement. ## AORI Bone Defect Classification and Assessment **Systematic Evaluation After Cement Removal** - Inspect all six surfaces (distal femur, posterior femur, medial femur, lateral femur) - Tibia: medial plateau, lateral plateau, central region - Palpate bone quality and bleeding - Measure defect depth and location - Photograph defects for documentation **AORI Type 1 Defects** - Intact metaphyseal bone with minor surface damage - Cancellous bone exposed but structural integrity maintained - **Reconstruction**: Cement fill alone, no augmentation required - Both femur and tibia can proceed with standard technique **AORI Type 2A Defects** - Damaged metaphyseal bone, contained defect (one surface) - Cortical rim intact providing containment - **Reconstruction**: Cement fill or small augments (5mm), bone graft can incorporate **AORI Type 2B Defects** - Uncontained defect involving one femoral condyle or one tibial plateau - Cortical rim deficient, cannot contain cement - **Reconstruction**: Metal wedge augments (5-15mm) cemented to component **AORI Type 2C Defects** - Uncontained defects both condyles, more extensive metaphyseal loss - Collateral ligament attachments still intact - **Reconstruction**: Large metal augments, trabecular metal cones **AORI Type 3 Defects** - Massive metaphyseal defect affecting collateral ligament attachments - Severe bone loss compromising stability - **Reconstruction**: Trabecular metal cones, metaphyseal sleeves, hinged prosthesis, tumor prosthesis for extreme cases **Ligamentous Integrity Assessment** - Critical after bone reconstruction for constraint decision - MCL: valgus stress in extension and 30° flexion - LCL: varus stress in extension and 30° flexion - Grade laxity (1+, 2+, 3+) - Document findings to guide constraint selection ## Reconstruction Principles **Joint Line Restoration** - Critical for kinematics and patellofemoral tracking - Anatomic joint line: 30mm from medial epicondyle to joint line - Use lesser trochanter as reference (medial epicondyle 30mm superior) - **Target**: restore within 5mm of anatomic position - Proximal migration causes patella baja, flexion instability, anterior knee pain - Distal migration causes impingement, mid-flexion instability **Tibial Preparation and Reconstruction** - Prepare tibia first with minimal resection (3-5mm) - Cut perpendicular to mechanical axis (extramedullary or intramedullary guide) - Resect to viable bleeding bone **Type 2A/2B Tibial Defects - Metal Augments** - 5-15mm metal wedge or block augments - Position augment, mark, prepare surface - **Cement augment to component NOT to bone** - Trial construct to verify fit and stability **Type 2C/3 Tibial Defects - Trabecular Metal Cones** - Size cone to fill metaphyseal defect (25-55mm diameter) - Ream metaphyseal cavity to match cone size - Impact cone press-fit into defect (biological fixation) - Cement tibial component to superior surface of cone - Cone provides structural support and osseointegration **Tibial Stem Principles** - 100-150mm press-fit stems bypass defects - **Rule**: bypass defect by 4-5 cortical diameters (minimum 100mm) - Press-fit preferred over cemented (Australian practice) - Offset stems available for difficult anatomy - Ensure proper alignment before impaction **Femoral Preparation and Reconstruction** - Minimal resection to viable bone (5-7mm cuts) - Re-establish distal femoral cut perpendicular to mechanical axis (5-7° valgus) - **Femoral rotation critical**: use multiple landmarks - Transepicondylar axis (most reliable) - Whiteside's line (AP axis) - Posterior condyles with 3° external rotation - Restore rotation for patella tracking and flexion gap balance **Femoral Defect Reconstruction** - Type 2A/2B: metal wedge augments for asymmetric bone loss - Posterior augments for posterior condyle defects - Distal augments for condylar defects - Type 2C/3: trabecular metal cones same principles as tibia - Cement augments to component, trial to verify fit **Trial Assessment** - Insert trial tibial and femoral components with augments and stems - Assess flexion and extension gaps (should be balanced 1-2mm laxity) - Check varus/valgus stability in extension and 30-90° flexion - Verify no lift-off medially or laterally - Test range of motion (target 0-110° minimum) - Assess patellar tracking (should centralize without lateral tilt) **Augment Technique Pearls**: Always cement augments to component, NOT directly to bone. Trial fit augment-component construct together. Remove excess cement before polymerization. Modular augments allow precise defect filling without over-resection. ## Constraint Selection - Critical Decision **Posterior-Stabilized (PS) Design** - **Indications**: Intact MCL and LCL (Grade 0-1+ laxity) - AORI Type 1, 2A, 2B defects - Cam-post mechanism provides AP stability - Lowest constraint - preserves bone stock - Lowest interface stress and loosening risk **Constrained Condylar Knee (CCK)** - **Indications**: MCL OR LCL deficient (Grade 2+ laxity one side) - AORI Type 2C defects with ligamentous insufficiency - Larger post and deeper femoral box - Provides varus-valgus stability - Still allows rotation - Most common constraint level in revision **Rotating Hinge** - **Indications**: Both MCL AND LCL deficient (Grade 2-3+ both sides) - AORI Type 3 defects with massive bone loss - Severe instability patterns - Fixed flexion contracture >30° with ligamentous insufficiency - Provides varus-valgus and AP stability - Allows 5-7° rotation - Highest interface stress - requires long stems (150-200mm) - Higher loosening risk long-term **Fixed Hinge (Rarely Used)** - Complete constraint, no rotation - Reserved for tumor reconstructions, salvage situations - Very high loosening rates - Not recommended for standard revision Over-constraining increases interface stress and accelerates loosening. Under-constraining causes recurrent instability. Carefully assess ligamentous integrity after bone reconstruction. Match constraint to bone loss and soft tissue envelope. When in doubt, trial next level of constraint and reassess stability. ## Final Component Implantation **Hybrid Fixation Technique - Australian Standard** - **Metaphyseal components**: cemented - **Stems**: press-fit (uncemented) - Augments: cemented to component - Cones: press-fit to bone, cement component to cone **Tibial Component Cementation** - Assemble augment-component-stem construct on back table - Cement augments to tibial component (allow to set) - Pulse lavage tibial surface and metaphyseal bone - Dry thoroughly - Inject cement into tibial surface and augment-bone interfaces - Insert assembled construct with press-fit stem - Maintain reduction with sustained pressure - Remove all excess cement (especially posterior) - Polymerization time: 7-10 minutes (longer than primary due to increased cement volume) **Femoral Component Cementation** - Same principles as tibia - Cement augments to femoral component first - Pulse lavage, dry bone surfaces - Inject cement, insert assembled construct - Verify rotation and position - Remove excess cement from posterior condyles, intercondylar notch - Maintain reduction during polymerization **Patellar Management** - Assess existing patellar component and bone stock - If loose: revise to all-poly button maintaining 15mm composite thickness - If absent and adequate bone (>15mm): consider selective resurfacing - If severe bone loss (<12mm): trabecular metal patellar component OR leave unresurfaced - Unresurfaced patella: denervate rim, remove osteophytes **Final Polyethylene Insertion and Reduction** - Polyethylene thickness typically 12-15mm (thicker than primary 9-11mm) - Thicker poly compensates for bone loss and ligamentous laxity - Lock insert onto tibial tray, verify secure locking mechanism - Reduce knee with controlled force - Verify stability throughout ROM - Check patellar tracking, no lateral tilt or subluxation - Verify 0-110° minimum ROM **Hemostasis and Tranexamic Acid** - Deflate tourniquet if used - Meticulous hemostasis with electrocautery - Tranexamic acid 1-2g IV (reduces transfusion rate by 40-50%) - Consider topical tranexamic acid in joint (additional 1-2g in 50ml saline, 5 min dwell time) - Inspect all gutters for bleeding - Expected blood loss 500-800ml (higher than primary 300-500ml) ## Wound Closure **Arthrotomy Closure - Critical for Extensor Mechanism** - Strong absorbable suture: 0 or 1 Vicryl - Interrupted or figure-of-eight technique - Robust closure essential for extensor mechanism continuity **Quadriceps Snip Repair** - Repair side-to-side with strong interrupted sutures - 0 or 1 Vicryl or Ethibond - Ensure no gaps in vastus lateralis - Full weight-bearing allowed **Tibial Tubercle Osteotomy Repair** - Reduce tubercle to anatomic position - Fixate with 2 x 4.5mm cortical screws - Assess stability by flexing knee - Protected weight-bearing 6 weeks - Hinged brace recommended **Subcutaneous and Skin Closure** - 2-0 Vicryl to subcutaneous tissue - Minimize dead space - 3-0 Monocryl subcuticular or staples to skin - Sterile dressing, consider negative pressure wound therapy if high-risk **Drains (Controversial)** - Some surgeons use deep drain (hemovac) - Remove at 24-48 hours - Others avoid drains (tranexamic acid sufficient) - No clear evidence of benefit **Cement Technique Pearls**: (1) Pulse lavage and dry surfaces thoroughly, (2) Inject cement into bone surfaces AND interfaces, (3) Insert component before cement becomes doughy, (4) Maintain reduction with sustained pressure for entire polymerization time (7-10 minutes), (5) Remove ALL excess cement before hardening, especially posterior regions. ## Post-operative Protocol and Rehabilitation **Immediate Post-operative Care (0-48 Hours)** - Multimodal analgesia: regional block (adductor canal block preferred over femoral to preserve quadriceps) plus oral paracetamol, NSAIDs if not contraindicated, oxycodone for breakthrough pain - VTE prophylaxis: LMWH (enoxaparin 40mg SC daily) or DOAC (rivaroxaban 10mg daily or apixaban 2.5mg BD) for **35 days** - critical in revision given higher risk - Mechanical prophylaxis: TED stockings and pneumatic compression devices for 5-7 days - Cryotherapy for swelling and pain control - Drain removal at 24-48 hours if used (expect higher output than primary) - Wound inspection at 48 hours **Weight-Bearing and Mobility (Day 0-1 Onwards)** - **Standard revision**: immediate weight-bearing as tolerated from day 0-1 - **Tibial tubercle osteotomy**: protected weight-bearing with hinged brace for 6 weeks, then progress - **Periprosthetic fracture**: depends on fixation stability, may need protected weight-bearing - Early mobilization with physiotherapy twice daily - Expect slower progress than primary TKR - No evidence for CPM benefit **Inpatient Phase (Typically 5-7 Days)** - Longer hospital stay than primary (3-5 days) - Intensive physiotherapy twice daily - Gait re-education with walking aids - Stairs practice before discharge - Pain control optimization - Discharge when mobile safely and pain controlled **Outpatient Rehabilitation (3-6 Months)** - More intensive and prolonged than primary - Emphasis on ROM restoration (realistic goal 0-110° not 0-120°) - Quadriceps and hamstring strengthening critical - Gait re-education and balance training - Functional activities practice - Pool therapy beneficial (once wound healed 3-4 weeks) **Follow-up Schedule** - Wound review at 2 weeks (remove staples/sutures) - Surgeon review at 6 weeks: clinical assessment, radiographs (AP, lateral, Merchant), assess alignment, component position, healing of TTO if performed - Then 3 months, 6 months, 12 months - Annual or biennial follow-up lifelong (higher re-revision rates than primary) **Return to Activities Timeline** - Sedentary work: 8-12 weeks (longer than primary 6 weeks) - Active manual labor: 4-6 months - Driving (if right knee): when safe control 6-8 weeks - Low-impact activities: 6-9 months (swimming, cycling, walking) - **Avoid high-impact activities**: running, jumping sports accelerate wear and loosening **Expected Outcomes and Patient Counseling** - Pain relief: 70-80% achieve good pain relief (vs 85-90% primary) - ROM: typically 0-110° (vs 0-120° primary) - Oxford Knee Score: 28-32 (vs 38-42 primary) - Patient satisfaction: 70-80% (vs 85-90% primary) - Ongoing pain without loosening: 15-25% (vs 10-20% primary) - Re-revision risk: 12% at 5 years, 18% at 10 years - **Realistic expectations essential** for satisfactory outcome - Functional outcomes inferior to primary TKR ## References 1. **Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Hip, Knee & Shoulder Arthroplasty: 2023 Annual Report.** Adelaide: AOA; 2023. Available from: https://aoanjrr.sahmri.com/annual-reports-2023 2. **Engh GA, Ammeen DJ. Classification and preoperative radiographic evaluation: knee.** Orthop Clin North Am. 1998;29(2):205-17. doi: 10.1016/s0030-5898(05)70319-9. PMID: 9553565. 3. **Hossain F, Patel S, Haddad FS. Midterm assessment of causes and results of revision total knee arthroplasty.** Clin Orthop Relat Res. 2010;468(5):1221-8. doi: 10.1007/s11999-009-1204-0. PMID: 20058112. 4. **Lonner JH, Lotke PA, Kim J, Nelson C. Impaction grafting and wire mesh for uncontained defects in revision knee arthroplasty.** Clin Orthop Relat Res. 2002;(404):145-51. doi: 10.1097/00003086-200211000-00025. PMID: 12439252. 5. **Mabry TM, Hanssen AD. The role of stems and augments for bone loss in revision knee arthroplasty.** J Arthroplasty. 2007;22(4 Suppl 1):56-60. doi: 10.1016/j.arth.2007.02.008. PMID: 17570280. 6. **Parvizi J, Gehrke T, Chen AF. Proceedings of the International Consensus on Periprosthetic Joint Infection.** Bone Joint J. 2013;95-B(11):1450-2. doi: 10.1302/0301-620X.95B11.33135. PMID: 24151261. 7. **Radnay CS, Scuderi GR. Management of bone loss: augments, cones, offset stems.** Clin Orthop Relat Res. 2006;446:83-92. doi: 10.1097/01.blo.0000214424.90360.d5. PMID: 16672876. 8. **Qiu YY, Yan CH, Chiu KY, Ng FY. Review article: Bone defect classifications in revision total knee arthroplasty.** J Orthop Surg (Hong Kong). 2011;19(2):238-43. doi: 10.1177/230949901101900223. PMID: 21857054. 9. **Sheth NP, Bonadio MB, Demange MK. Bone loss in revision total knee arthroplasty: evaluation and management.** J Am Acad Orthop Surg. 2017;25(5):348-357. doi: 10.5435/JAAOS-D-15-00660. PMID: 28355137. 10. **Whiteside LA. Cementless reconstruction of massive tibial bone loss in revision total knee arthroplasty.** Clin Orthop Relat Res. 1994;(309):175-82. PMID: 7994955.

Revision Total Knee Replacement (rTKR)

Revision Total Knee Replacement (rTKR)