import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: Posterior to hip joint, exits greater sciatic notch 2cm posterior to short external rotators, runs distally along posterior femur 2cm from bone **Protection**: Identify and place vessel loop before ETO, gentle retraction, avoid excessive GT reflection, limit leg lengthening to 4cm, document function post-op **Location**: Entire femoral shaft during reaming, stem insertion, cement removal - highest risk at apex of femoral bow (anterior-lateral mid-shaft) **Protection**: Fluoroscopy during reaming (AP/lateral), gentle progressive reaming, smaller diameter in bowed femurs, recognize immediately, treat with cortical strut grafts and cerclage cables **Location**: Posterior to femur at mid-shaft level, perforating branches penetrate linea aspera every 2-3cm from medial to lateral **Protection**: Avoid aggressive posterior dissection beyond mid-shaft, gentle retractor placement, recognize bleeding immediately (massive), vascular surgery consult if injured, direct pressure and repair **Location**: Exits pelvis above piriformis 3-5cm superior to GT, enters gluteus medius/minimus, runs between muscle layers **Protection**: Avoid dissection >5cm superior to GT, gentle abductor retraction, recognize injury (sudden bleeding or abductor denervation), ligate vessel if divided **Location**: Anterior to hip capsule, lateral to femoral artery, 2-3cm medial to ASIS, can be injured with anterior retractors or cement extrusion **Protection**: Avoid aggressive anterior capsular releases, gentle retractor placement medially, protect during anterior acetabular work, recognize palsy (quadriceps weakness, loss knee extension) ## Indications for Femoral Component Revision ### Primary Indications **Aseptic Loosening (40-50%)** - Most common indication for femoral revision - Progressive radiolucencies >2mm at bone-implant interface - Component migration or subsidence >5mm - Pedestal sign (bone formation distal to stem tip) - Clinical: progressive thigh pain, groin pain, instability **Subsidence with Loss of Fixation (15-20%)** - Progressive stem migration distally indicating inadequate initial fixation - Presents as leg shortening, thigh pain, instability - More common with smooth stems, cemented stems, inadequate diaphyseal contact **Periprosthetic Fracture Around Femoral Component (10-15%)** - Vancouver B2 (fracture + loose stem) or B3 (fracture + poor bone stock) - Intraoperative fractures during revision or primary surgery - Stress fractures around loose stems **Infection (10-15%)** - Two-stage revision: first stage removes infected components, spacer placement - Second stage is femoral revision after 6-12 weeks IV antibiotics - Chronic PJI requiring complete component removal **Other Indications (20-25%)** - Adverse reaction to metal debris (ARMD) from modular junctions - Stem malposition causing impingement or instability - Recurrent instability requiring version change or offset restoration - Modular junction failure or corrosion - Polyethylene wear requiring stem revision for exposure ### Mandatory Pre-operative Infection Workup **Laboratory Tests** - ESR >30mm/hr suspicious, >40mm/hr concerning - CRP >10mg/L suspicious, >20mg/L concerning - Both elevated: sensitivity 95% for infection - Obtain 2-4 weeks after stopping antibiotics if possible **Joint Aspiration** - MANDATORY before femoral revision - cannot proceed without - WBC >3000 cells/μL suspicious, >10,000 highly suggestive - PMN >80% concerning for infection, >90% highly suggestive - 14-day cultures: aerobic and anaerobic, fungi if immunosuppressed - Alpha-defensin: sensitivity 97%, specificity 96% for PJI - Synovial CRP >6.9mg/L highly predictive **Advanced Tests if Equivocal** - Leukocyte esterase test (LE strip test) - Next-generation sequencing for fastidious organisms - Sonication of removed components for biofilm organisms **Cannot Proceed to Revision if Infection Present** - Missed infection = catastrophic outcome (infected revision) - If equivocal: treat as infected, 2-stage approach safer - Frozen section at revision: >5 PMNs per HPF = infection ### Paprosky Femoral Classification **Type I - Minimal Metaphyseal Bone Loss** - Characteristics: Minimal metaphyseal cancellous bone damage, intact diaphysis, good cortical bone stock, stable implant possible in metaphysis - Stem Selection: Standard cementless primary or short revision stem (150-180mm) - Fixation Strategy: Metaphyseal fixation with proximal porous coating - Outcomes: 90-95% 10-year survival **Type II - Extensive Metaphyseal Loss, Intact Diaphysis** - Characteristics: Damaged metaphysis with cancellous loss, diaphysis intact >4cm, isthmus identifiable, cortical bone adequate - Stem Selection: Extensively coated cementless stem (200-250mm, 6-8 inch coating) - Fixation Strategy: Diaphyseal fixation bypassing metaphyseal defects by 2 cortical diameters - Outcomes: 85-90% 10-year survival **Type IIIA - Severe Metaphyseal Loss, Diaphysis >4cm** - Characteristics: Severe metaphyseal destruction, diaphysis still intact >4cm, widened canal, cortical thinning - Stem Selection: Long extensively coated stem (250-280mm) OR modular tapered fluted stem - Fixation Strategy: Distal diaphyseal fixation, impaction bone grafting metaphysis, may need cortical strut grafts - Outcomes: 80-85% 10-year survival **Type IIIB - Severe Meta + Proximal Diaphyseal Loss** - Characteristics: Metaphyseal AND proximal diaphyseal destruction, <4cm intact diaphysis, isthmus barely identifiable - Stem Selection: Extra-long extensively coated (280-300mm) OR long modular tapered OR proximal femoral replacement if inadequate fixation - Fixation Strategy: Very distal diaphyseal fixation, liberal use of strut grafts, protected weight bearing - Outcomes: 70-80% 10-year survival **Type IV - No Identifiable Isthmus (Stovepipe Femur)** - Characteristics: Metaphyseal and diaphyseal destruction, no identifiable isthmus, widely patent canal, massive bone loss - Stem Selection: Proximal femoral replacement (megaprosthesis) OR allograft-prosthesis composite (APC) - Fixation Strategy: Cannot achieve stable stem fixation, distal fixation in mid/distal femur with megaprosthesis - Outcomes: 70-75% 10-year survival ### Imaging Workup **Plain Radiographs** - AP pelvis, lateral hip, FULL LENGTH AP and lateral femur (mandatory) - Assess femoral bow, canal diameter at multiple levels, bone stock - Identify fractures, perforations, cortical defects, cement extent - Measure leg length discrepancy (lesser trochanter to ischial tuberosity) - Template stem length and diameter **Scanogram** - If significant leg length discrepancy suspected - Measures true leg lengths with magnification correction **CT Scan** - If severe bone loss for 3D assessment and planning - Delineate extent of osteolysis, cortical defects - Assess cement distribution and distal plugs - Plan cortical windows if needed for cement removal **MRI** - If ARMD suspected (metal artifact reduction sequences) - Assess soft tissue pseudotumors - Evaluate abductor integrity ### Implant Planning Checklist **Revision Stem System** - Multiple sizes and lengths available (150-300mm) - Trial stems for each size - Consider extensively coated, modular tapered, or both systems **Long Stems** - Have 250-300mm stems available even if templated shorter - Better to have and not need than need and not have **Extended Trochanteric Osteotomy (ETO) Instruments** - Microsagittal saw with long blade - Specialized osteotomes and retractors - Plan ETO if: well-fixed cementless stem, cemented with distal cement, need distal access **Fixation Materials** - Cerclage cables (16 or 18 gauge, 316L stainless steel or titanium) - Cable tensioner and crimpers - Cortical strut allografts (fibular or femoral shaft) - Morselized allograft for impaction grafting **Blood Management** - Type and cross 2-4 units - Cell saver available - Tranexamic acid 1g IV pre-incision, 1g at closure ## Extended Trochanteric Osteotomy (ETO) Technique ### Indications for ETO **Absolute Indications (40-60% of Femoral Revisions)** 1. **Well-Fixed Cementless Stem** - Ingrown porous coating, cannot extract without fracture - Attempted extraction will fracture femur - ETO allows controlled access to ingrowth interface 2. **Cemented Stem with Distal Cement** - Cement extending beyond metaphysis into diaphysis - Cannot access distal cement from proximal approach - Need to remove all cement to avoid stress risers 3. **Need for Distal Femoral Exposure** - Periprosthetic fracture requiring visualization - Long stem insertion requiring direct visualization - Retained distal cement or broken components ### ETO Surgical Technique - Step by Step **Step 1: Mark Osteotomy with Cautery** - START 1-2cm DISTAL to GT tip (critical - do not start at GT tip) - Starting at GT tip weakens abductor insertion, increases trochanteric escape - Mark longitudinally along anterior-lateral femoral shaft - Extend 10-15cm distally (longer 12-15cm if extensive distal cement) - Mark should be on ANTERIOR 1/3 of femoral circumference - Use fluoroscopy to confirm position and length - Osteotomy must extend past distal cement or stem coating by 2-3cm **Step 2: Longitudinal Cortical Cuts** - Use MICROSAGITTAL SAW with long blade (150-200mm) - Make LATERAL cut through cortex (full thickness) - Make ANTERIOR cut through cortex (full thickness) - Cuts define anterior 1/3 of femoral circumference - Do NOT cut posterior cortex - this is the blood supply - Do NOT cut more than 1/3 circumference - risk of complete fracture - Protect soft tissues with retractors during sawing - Copious irrigation during sawing to prevent thermal necrosis **Step 3: Complete Osteotomy Distally** - Use straight OSTEOTOMES to complete osteotomy distally - Leave distal hinge initially intact (2-3cm) - Then complete distal hinge with osteotome - Now have free GT fragment attached to muscles **Step 4: Identify Muscle Pedicle Attachments** - GT remains ATTACHED to vastus lateralis anteriorly - GT attached to gluteus medius/minimus superiorly - These muscle attachments are VASCULAR PEDICLE - Maintain all muscle attachments - do not detach - Pedicle maintains viability and blood supply to GT **Step 5: Reflect GT Fragment** - GENTLY reflect GT ANTEROLATERALLY using Z-retractors - GT fragment hinges on muscle pedicle attachment - Now have excellent visualization of entire proximal/mid femoral canal - Can see cement, stem, cortical defects clearly - PROTECT SCIATIC NERVE posteriorly - at risk with excessive retraction - Avoid excessive force - can fracture GT or femur ### Advantages of ETO - **Excellent Femoral Canal Access**: Full visualization from metaphysis to mid-diaphysis - **Bone Preservation**: Controlled osteotomy vs aggressive extraction (prevents fracture) - **Facilitates Cement Removal**: Direct access to distal cement - **Allows Canal Inspection**: Can assess cortical integrity, perforations, fractures - **Enables Strut Graft Placement**: Direct visualization for strut application - **Reproducible Healing**: Biological healing via muscle pedicle ### Disadvantages of ETO - **Non-union Risk**: 5-10% non-union rate, most asymptomatic - **Trochanteric Escape**: Rare <2% if proper fixation, catastrophic if occurs - **Protected Weight Bearing**: Requires TDWB/PWB for 6-12 weeks - **Increased Operative Time**: Adds 20-30 minutes to procedure - **Abductor Weakness**: Temporary weakness until healed (3-6 months) - **Cable Complications**: Cable fracture, migration, pain (5-10%) ### ETO Repair Technique **Materials** - 2-3 cerclage cables (minimum 2, typically 3 for stability) - 16 or 18 gauge cables - 316L stainless steel or titanium cables - Cable tensioner and crimper **Reduction** - Reduce GT fragment back to femoral shaft anatomically - Ensure NO ROTATION - fragment must sit flush with shaft - Check anterior and lateral cortical alignment - Hold with bone clamps during cable placement **Cable Placement** - Cable 1: Proximal at level of GT insertion - Cable 2: Middle of osteotomy - Cable 3: Distal at osteotomy termination - Space cables 1cm apart for optimal fixation - Pass cables through drill holes in GT or around GT and femur **Cable Tensioning** - Tension sequentially from proximal to distal - Tighten to 300-500N tension (use calibrated tensioner) - Crimp cables securely - Assess rigid fixation - should be no motion **Supplemental Fixation (Controversial)** - Some surgeons add 4.5mm cortical screw with washer through GT - Provides additional rotational stability - Others avoid due to stress riser risk - Not mandatory if cable fixation rigid **Assessment** - Palpate osteotomy - should be rigid, no motion - Fluoroscopy confirms anatomic reduction - No step-off of cortices ### Post-operative ETO Protocol **Weight Bearing** - Touch down weight bearing (TDWB) or partial weight bearing (20-30kg) for 6-12 weeks - Advance to weight bearing as tolerated when radiographic healing confirmed - Typical healing time 8-12 weeks (callus on X-ray, pain-free) **Radiographic Follow-up** - X-rays at 6 weeks: assess callus formation, cable position - X-rays at 3 months: should be healed in most cases - If not healed at 3 months but asymptomatic, continue protected weight bearing to 6 months - If symptomatic non-union: revision ETO fixation with cables and bone graft ## Revision Stem Types and Fixation Strategies ### Type I/II - Standard and Extensively Coated Stems **Type I Reconstruction (Minimal Bone Loss)** *Standard Cementless Revision Stem* - Similar to primary cementless stem with proximal porous coating - Stem length 150-180mm - Metaphyseal fixation with proximal ingrowth surface - Cylindrical or anatomic design - Sizing: final stem 0.5-1mm larger than final reamer for press fit *Insertion Technique* - Insert stem with mallet, gentle progressive taps - Aim for neutral version (10-15° anteversion) - Confirm fully seated (at resection level, not proud) - Stability testing: zero subsidence with axial load - Should feel solid metaphyseal engagement *Examples* - Zimmer Wagner Cone Stem (tapered, self-locking) - Stryker Accolade II (metaphyseal fixation) - DePuy Corail (HA coating, excellent track record) **Type II Reconstruction (Metaphyseal Damage, Intact Diaphysis)** *Extensively Coated Cementless Stem - KEY FEATURES* 1. **Long Porous Coating**: 6-8 inches (150-200mm) of porous coating for diaphyseal scratch fit 2. **Cylindrical Design**: Straight, non-anatomic to match diaphyseal canal 3. **Rough Surface**: Porous coating, grit blast, or plasma spray for osseointegration 4. **Bypass Metaphyseal Defects**: Stem extends 2 cortical diameters distal to defects 5. **Diaphyseal Fixation**: Achieves 2cm minimum (prefer 4-7cm) scratch fit in diaphysis 6. **Stem Length**: Typically 200-250mm 7. **Straight Alignment**: Neutral version, follows canal axis *Critical Principle - Diaphyseal Fixation* - Metaphyseal bone CANNOT be trusted in revision - Must achieve distal diaphyseal cortical contact (scratch fit) - Need minimum 2cm contact (2 cortical diameters) - Prefer 4-7cm contact for optimal stability - Reaming to "chatter" indicates cortical contact achieved *Sizing and Insertion* - Size matches final reamer or 0.5mm larger - Insert with mallet, progressive taps - Stem should ENGAGE DISTALLY in diaphysis (resistance to seating) - Proximal metaphysis will be loose (expected and acceptable) - Confirm distal engagement with fluoroscopy (AP and lateral) - Check stem seated to templated depth *Metaphyseal Management* - Optional: impaction bone grafting with morselized allograft - Fills metaphyseal dead space - May provide proximal support long-term as graft incorporates - Not essential if distal fixation solid *Examples* - Zimmer VerSys Heritage (6 inch coating, cylindrical) - Stryker Restoration Modular (6-8 inch coating, extensive track record) - Link MP Reconstruction (8 inch coating, excellent survival data) - Solution System (cylindrical, extensively porous coated) *Outcomes* - 10-year survival 85-90% if adequate fixation - 15-year survival 80-85% - Thigh pain in 10-20% (more than primary, usually mild) - Subsidence most common failure if undersized ### Type IIIA/IIIB - Long Extensively Coated or Modular Tapered **Type IIIA Reconstruction (Severe Metaphyseal Loss)** *Option 1: Long Extensively Coated Stem* - Length 250-280mm - Same principles as Type II but longer - Extend well into diaphysis for fixation - Bypass all metaphyseal defects by 2 cortical diameters - May need to extend to distal femur *Option 2: Modular Tapered Fluted Stem (Preferred)* **Components** - Distal tapered stem segment (self-locking taper in diaphysis) - Proximal modular body (adjust offset and version intraoperatively) - Modular neck (some systems, adjust version further) - Longitudinal flutes (rotational stability) **Advantages** - Intraoperative adjustment of offset and version - Compressive fit in diaphysis via taper - Restores individual anatomy better than fixed designs - Flutes prevent rotation - Can optimize stability and leg length during surgery **Insertion Technique** 1. Insert distal tapered stem to templated depth 2. Taper achieves compression fit in diaphysis 3. Assess version and stability 4. Assemble proximal body with chosen offset (standard, high, extra-high) 5. Lock modular junction (morse taper or threaded) 6. Insert final head **Examples** - Zimmer Wagner SL Revision (original modular tapered, excellent track record) - Link Arcos Modular (similar design, good outcomes) - Stryker Restoration Modular (modular options for offset/version) - S-ROM (fully modular, proximal and distal components) **Impaction Bone Grafting** - Recommended for metaphyseal defects - Morselized allograft impacted into metaphyseal defects - Provides biological augmentation - May incorporate and provide long-term support - Use mesh or allograft cortical strips to contain graft **Type IIIB Reconstruction (<4cm Intact Diaphysis)** *Extra-Long Stems* - Length 280-300mm - Extend well into distal femur for fixation - Need ANY diaphyseal contact - if none, proceed to PFR - May combine extensively coated or modular tapered designs - Very challenging - high failure risk if inadequate fixation *Decision Point: Stem vs PFR* - If ANY cortical contact achievable distally: extra-long stem - If NO cortical contact (truly stovepipe femur): PFR - Consider structural integrity: if cortex paper-thin, PFR safer **Cortical Strut Grafts - Liberal Use in Type IIIA/B** *Indications* - Cortical defects or perforations - Periprosthetic fractures - Augmentation of thin cortex - Stress shielding prevention *Types* - Fibular strut allografts (smaller diameter, good for hemi-circumferential) - Femoral shaft allografts (larger diameter, circumferential coverage) *Technique* - Span defect by 2 cortical diameters proximal and distal - Sit flush against femoral cortex - Fix with 2-3 cerclage cables per strut - Can place circumferential or hemi-circumferential - Stem passes through center, strut provides cortical augmentation *Advantages* - Biological: incorporates over time - Less stress shielding than plates - Excellent for bridging defects - Allows stem to bypass problematic areas *Outcomes Type IIIA/B* - Type IIIA: 80-85% 10-year survival - Type IIIB: 70-80% 10-year survival - Higher complication rates than Type I/II - Subsidence and loosening more common if inadequate fixation ### Type IV - Proximal Femoral Replacement (PFR) **Indications** - No identifiable isthmus (stovepipe femur) - Massive bone loss precluding stem fixation - Widely patent femoral canal with no cortical contact possible - Failed attempts at stem fixation (loose immediately on table) **Proximal Femoral Replacement (Megaprosthesis) Components** *Distal Stem Component* - Long stem (150-200mm) for fixation in mid/distal femoral diaphysis - Fixed well below area of bone loss in healthy bone - Cementless press fit OR cemented depending on bone quality - Need good cortical contact for stability *Proximal Body Component* - Modular oncologic prosthesis body - Articulating femoral head/neck - Variety of lengths to restore leg length and offset - Junction at level of osteotomy (resection level) *Collar Component* - For abductor reattachment - Critical for stability and function - Some designs have mesh sleeve for soft tissue ingrowth **PFR Surgical Technique** 1. **Determine Resection Level** - Distal to area of bone loss where healthy diaphyseal cortex present - Typically 10-15cm below GT or at mid-femur - Need adequate bone quality distally for stem fixation 2. **Perform Femoral Osteotomy** - Transverse cut at planned resection level - Remove proximal femur including deficient bone 3. **Ream Distal Femur for Stem Fixation** - Ream distal femoral canal to cortical contact - Need good press fit for stability - If poor bone quality, plan cementing 4. **Trial Stem Sizing** - Trial stems to confirm adequate fixation - Assess stability - should be solid 5. **Assemble Modular Prosthesis** - Choose proximal body length to restore leg length and offset - Assemble distal stem + proximal body - Lock modular junction securely 6. **Insert Final Construct** - Insert assembled prosthesis - Confirm distal stem fully seated - Check stability and alignment 7. **ABDUCTOR RECONSTRUCTION (Critical)** - Reattach gluteus medius/minimus to collar - Use heavy non-absorbable sutures (2 Ethibond) - Pass through drill holes in prosthesis or suture to mesh sleeve - Tension abductors appropriately - Without abductor reattachment: poor function, instability 8. **Trial Reduction** - Assess stability throughout ROM - Check leg length (should match or slightly long) - Confirm no impingement 9. **Final Head** - Large head (36-40mm) to reduce dislocation risk - Assess final stability **Allograft-Prosthesis Composite (APC) - Alternative** *Indications* - Younger patients (<60 years) where biological solution preferred - Type IV bone loss but want to preserve option for future revision *Technique* - Structural femoral allograft (proximal femur or whole femur) - Stem cemented through allograft and into host bone distally - Junction between allograft and host bone fixed with plate and screws - Abductors and soft tissues attached to allograft *Advantages* - Biological solution that may incorporate - Restores bone stock for future revision - More normal anatomy *Disadvantages* - Higher complication rate: non-union 10-20%, fracture 15-20%, resorption 10-15% - Longer healing time (6-12 months for junction) - Protected weight bearing for 3-6 months - Infection risk 5-10% - 10-year survival only 60-70% *Reserve for Younger Patients* - Typically <60 years - Good soft tissue and compliance - Understand risks and prolonged rehab **PFR Outcomes** - 10-year survival 70-75% - Higher complication rates than standard revision - Dislocation 10-20% (abductor insufficiency) - Infection 5-10% (large foreign body) - Aseptic loosening 10-15% - Periprosthetic fracture 5-10% - Abductor failure 15-20% - BUT: salvage procedure when no alternative - Allows immediate weight bearing (advantage over APC) - Most patients satisfied despite complications ## Detailed Operative Technique ### Positioning and Preparation **Patient Position** - Lateral decubitus, affected side up - Pelvis perpendicular to floor with rigid anterior and posterior supports - Sandbags or pegboard positioning system - Check pelvis perpendicular with alignment rod or fluoroscopy - Affected leg free-draped for full manipulation - Opposite leg padded and secured **Table Setup** - Radiolucent table for intraoperative fluoroscopy - Ensure fluoroscopy C-arm can access hip and full femur - Long revision instrument trays available (280-300mm stems) - Cell saver setup - Extra lighting for deep exposure **Surgical Approach** - Posterior approach (Moore/Southern) most common for revision - Utilize previous scar if possible - Extended Trochanteric Osteotomy (ETO) frequently required **Incision** - Utilize PREVIOUS INCISION, excise old scar tissue - Extend 18-25cm from PSIS toward GT and distally along lateral femoral shaft - May need to extend more distally if ETO planned or long stem required - Can extend to 30cm for very long stems or distal fixation ### Step 1: Preoperative Planning and Infection Workup **Exam Key Point**: "Before femoral revision I RULE OUT INFECTION with mandatory aspiration. ESR, CRP, joint aspiration with WBC >3000 suspicious, PMN >80% concerning, 14-day cultures aerobic/anaerobic. Alpha-defensin if equivocal. Cannot proceed without ruling out infection - missing occult infection is catastrophic (infected revision). I use PAPROSKY FEMORAL classification to guide stem choice: Type I minimal loss = standard stem. Type II metaphyseal loss = extensively coated 6-8 inch for diaphyseal fixation. Type IIIA severe loss = long extensively coated or modular tapered. Type IIIB <4cm diaphysis = extra-long or PFR. Type IV no isthmus = megaprosthesis. Key principle: achieve 2cm minimum scratch fit in DIAPHYSIS for stable fixation - metaphyseal bone cannot be trusted. I obtain full-length AP and lateral femur films to assess bow, canal diameter, plan stem length. I plan ETO if well-fixed stem or cemented with distal cement." - Missing occult infection - catastrophic (leads to infected revision, multiple further surgeries) - Underestimating bone loss - inadequate stem length or fixation strategy chosen, early subsidence - Not having long stems or ETO instruments available - cannot complete surgery safely, may be forced to compromise - Wrong stem type for defect severity - Type IIIA defect with Type II stem = early loosening - Not assessing femoral bow on full-length films - perforation risk with straight stems in bowed femurs ### Step 2: Exposure and Assessment for ETO **Deep Dissection** - Incise fascia lata longitudinally in line with incision - Split gluteus maximus in line with muscle fibers (blunt dissection) - Extensive scar release - capsule often thick, contracted, adherent - Tag short external rotators if present (piriformis, obturators) - often atrophic or absent in revision - May be minimal soft tissue landmarks due to scarring **IDENTIFY SCIATIC NERVE EARLY** - Most critical step for safety - Nerve posterior to hip joint, exits greater sciatic notch - Typically 2cm posterior to short external rotators - May be encased in scar tissue - Place vessel loop for identification and protection - Gentle dissection to free nerve from scar - Avoid excessive traction **Capsulotomy** - Capsule often thick and contracted in revision - May be minimal capsule remaining - Excise thickened capsule and scar - Send capsule for frozen section (>5 PMNs/HPF = infection) **Hip Dislocation** - Often difficult due to scar tissue - Gentle manipulation to avoid fracture - Femur may be loose and easily dislocate - Or well-fixed and difficult to dislocate - Protect sciatic nerve during manipulation **ASSESS NEED FOR ETO** *Indications for ETO (Perform in 40-60% of Revisions)* 1. Well-fixed cementless stem - ingrown, cannot extract without fracture 2. Cemented stem with cement extending distally past metaphysis 3. Need for distal femoral exposure (fracture, long stem insertion) 4. Severe proximal bone loss requiring improved visualization *If ETO NOT Needed* - Loose stem with minimal cement - Cement confined to metaphysis only - Proceed with standard extraction (Step 4) *If ETO Needed* - Proceed to Step 3 **Exam Key Point**: "I assess need for ETO after exposure and dislocation. INDICATIONS: well-fixed cementless stem (will fracture if force extraction), cemented stem with distal cement (cannot access from above), need distal exposure (fracture, long stem). I perform ETO in 40-60% of femoral revisions. ETO gives EXCELLENT canal access and preserves bone vs aggressive extraction attempts that risk fracture. I ALWAYS identify sciatic nerve before ETO and place vessel loop - nerve at risk during osteotomy and subsequent GT reflection. If in doubt about need for ETO, I proceed with ETO - safer than attempting difficult extraction." - Proceeding without ETO when needed - femoral fracture during stem extraction (1-3% if force used) - ETO without sciatic nerve identification - nerve palsy from osteotomy or GT reflection - Inadequate proximal exposure - cannot access femoral canal safely, limited visualization - Not extending incision distally enough for ETO - cannot perform adequate length osteotomy - Fracture during dislocation - treat immediately with cerclage cables and may need to modify plan ### Step 3: Extended Trochanteric Osteotomy (ETO) Technique *(See detailed technique in ETO & Exposure Tab)* **Exam Key Point**: "ETO technique: I cut anterior 1/3 of femur for 10-15cm using microsagittal saw. START 1-2cm BELOW GT tip (not at tip - preserves abductor insertion, reduces trochanteric escape risk). Lateral and anterior cortical cuts only. GT stays attached to vastus lateralis anteriorly and abductors superiorly - this muscle pedicle maintains blood supply. Posterior cortex intact preserves additional blood supply. I gently reflect GT anterolaterally with Z-retractors - gives EXCELLENT canal access, can visualize entire proximal and mid femur clearly. Critical to extend osteotomy past distal cement/coating by 2-3cm for adequate access. At closure I repair with 2-3 cerclage cables spaced 1cm apart, tensioned to 300-500N. Non-union rate 5-10%, most heal by 3 months with protected weight bearing." - Starting ETO at GT tip - weakens abductor insertion, higher trochanteric escape rate (up to 5% vs <2%) - Cutting too far posteriorly (>1/3 circumference) - complete fracture through femur, devascularization - Osteotomy too short - cannot access distal cement, defeats purpose of ETO - Detaching muscles from GT - GT loses blood supply, guaranteed non-union - Excessive force reflecting GT - fracture through GT or femoral shaft - Sciatic nerve traction injury during GT reflection - nerve palsy (2-5%) ### Step 4: Femoral Component Extraction **Cemented Stem Extraction (Most Challenging)** *Option 1: Cement-Within-Cement Technique* - If stem loose AND cement mantle intact, well-fixed, >2mm thick - Leave cement mantle in place - Cement new stem into old cement mantle - Advantages: faster, preserves bone, less risk - Disadvantages: requires good mantle (rarely present in revision) *Option 2: Complete Cement Removal (Usually Required)* **Technique** 1. High-speed burr to disrupt cement (4-6mm ball-tipped burr) - Work proximal to distal - Careful - thermal necrosis risk, perforation risk - Copious irrigation during burring - Create groove in cement mantle 2. Flexible osteotomes to split cement - Insert into burr groove - Gentle taps to split cement from bone - Work circumferentially around canal 3. Ultrasonic cement removal tools (if available) - Expensive but very effective - Vibration disrupts cement-bone interface - Less thermal necrosis than burr 4. Cement taps to disrupt distal plug - Use flexible cement tap to reach distal plug - Gentle impaction to break plug loose - Remove piecemeal **Cortical Windows for Inaccessible Cement** - If cement extends far distally and ETO inadequate access - Create rectangular window in lateral cortex with saw - Remove cement through window - Replace window as cortical strut graft - Fix with cerclage cables **Fluoroscopy Confirmation** - AP and lateral fluoroscopy to confirm all cement removed - Residual cement = stress riser, pain, limits new stem fixation **Cementless Stem Extraction** *Loose Stem (Easy)* - Usually extracts easily with slap hammer or extraction device - Attach extractor to modular neck or morse taper - Gentle taps on slap hammer - Stem should come out smoothly *Well-Fixed Ingrown Stem (Difficult)* - DO NOT FORCE - will fracture femur - If no ETO, MUST perform ETO now - With ETO exposure: - Use specialized curved osteotomes to disrupt ingrowth interface - Work around entire circumference of stem - Gentle progressive disruption - Prosthesis extraction instruments - Slap hammer with gentle force - PATIENCE required - do not rush *If Cannot Extract Safely* - Leave proximal portion of stem in place - Debride to create smooth surface - Cement long stem past retained distal tip - Bypass retained component by 2 cortical diameters **Exam Key Point**: "Femoral component extraction: CEMENTED: cement-within-cement if mantle intact and stem loose (rarely possible), otherwise complete cement removal. I use combination of high-speed burr (careful - perforation risk, thermal necrosis), flexible osteotomes to split cement, ultrasonic tools if available. Work proximal to distal methodically. May need cortical windows if distal cement unreachable - create window, remove cement, replace window as strut graft with cables. I confirm all cement removed with fluoroscopy. CEMENTLESS: loose stems extract easily with slap hammer. Well-fixed ingrown stems NEED ETO or will fracture femur. With ETO I use curved osteotomes to disrupt ingrowth interface gently, extraction tools, patience. NEVER force extraction. Femoral perforation occurs in 2-5% during this step - treat immediately with cortical strut graft bypass." - Femoral perforation (2-5%) during cement removal or stem extraction - MOST COMMON COMPLICATION at this step - Femoral fracture if force extraction of well-fixed stem without ETO (1-3% if forced) - Thermal necrosis from prolonged burring without irrigation - weakens bone, non-union - Retained cement distally - stress riser, pain, limits new stem fixation zone - Inadvertent propagation of cortical window into fracture - treat as fracture with strut grafts ### Step 5: Femoral Bone Loss Assessment **With stem removed and cement cleared, assess TRUE BONE DEFECT** *Paprosky Femoral Classification (See Indications Tab for details)* **Assessment Checklist** 1. **Metaphyseal Bone Stock** - Any cancellous bone remaining? - Cortical rim intact or destroyed? - Can achieve metaphyseal fixation? (Type I only) 2. **Diaphyseal Cortical Integrity** - Length of intact cortex available? - Measure from metaphyseal-diaphyseal junction distally - Need >4cm for Type II/IIIA - <4cm indicates Type IIIB - No intact cortex = Type IV 3. **Canal Diameter** - Measure at isthmus (normally 10-12mm) - Widened to 15-20mm = Type IIIA - Widely patent >20mm = Type IIIB/IV - "Stovepipe" femur (no isthmus) = Type IV 4. **Cortical Thickness** - Probe with instrument to feel thickness - Adequate thickness (>5mm) can support stem - Paper-thin cortex (<3mm) needs strut augmentation - Assess circumferentially 5. **Identify Fractures** - Stress fractures common around loose stems - Check for cracks extending from screw holes - Palpate entire femur for motion - Fluoroscopy if suspicious 6. **Identify Perforations** - From previous surgery or current cement removal - Probe canal to feel for cortical breach - Fluoroscopy can help identify 7. **Assess Greater Trochanter** - Attached? Fractured? Viable? - Abductor attachment intact? - Will influence soft tissue reconstruction **Exam Key Point**: "Paprosky femoral classification guides my stem choice: Type I good bone = standard stem with metaphyseal fixation. Type II metaphyseal loss, diaphysis OK = extensively coated 6-8 inch for diaphyseal fixation. Type IIIA severe metaphyseal loss = long extensively coated or modular tapered. Type IIIB <4cm diaphysis = extra-long stem or consider PFR. Type IV no isthmus, stovepipe = PFR or allograft-prosthesis composite. CRITICAL: I assess DIAPHYSEAL BONE carefully - this is fixation site in revision. Need minimum 2cm scratch fit (prefer 4-7cm) for stable fixation. Metaphyseal bone cannot be relied upon. I probe canal to feel cortex thickness, diameter, bow. I recognize fractures or perforations immediately - changes plan to include cortical strut grafts for bypass and augmentation." - Underestimating bone loss - stem too short, inadequate fixation, subsidence (most common failure mode) - Not recognizing fracture - will propagate if not fixed, can extend during stem insertion - Misclassifying as Type III when actually Type IV - stem will not achieve fixation, loosening - Not assessing distal femur adequately - inadequate length for fixation zone, stem bottoms out - Missing perforation - stem will exit through perforation or fail, need to bypass with strut ### Step 6: Femoral Canal Preparation **Goal: Establish Distal Fixation in Healthy DIAPHYSEAL Bone** **Reaming Strategy by Paprosky Type** *Type I/II* - Box chisel proximally to establish entry point - Sequential reaming from metaphysis to diaphysis - Start small (10mm), increase by 0.5mm increments - Ream until cortical contact ("chatter" indicates contact) - Type I may still achieve metaphyseal fixation - Type II bypasses metaphysis for diaphyseal fixation only *Type II/IIIA/IIIB* - SKIP metaphyseal reaming (no fixation possible there) - Use long flexible reamers to reach diaphysis - Entry point in line with femoral canal - Ream progressively until cortical contact (chatter, resistance) - Need 2cm MINIMUM (prefer 4-7cm) circumferential cortical contact - This "scratch fit" is STABLE FIXATION in revision - Ream straight in neutral axis of femur **Reaming Technique** 1. Start with appropriately sized reamer (usually 10-12mm) 2. Gentle pressure, let reamer cut 3. Advance slowly - do not force 4. Increase size by 0.5mm when reamer passes easily 5. Continue until CHATTER (indicates cortical contact) 6. Resistance to further advancement (bottoming out) 7. No further advancement despite pressure **Special Considerations - Bowed Femurs** - Femur has natural anterior bow - Straight stems in bowed femurs = anterior perforation risk at bow apex - Options: - Smaller diameter stem (stays within canal despite bow) - Flexible reamers that follow bow - Accept some under-reaming to avoid perforation - Fluoroscopy during reaming to check position **Line-to-Line Reaming** - Do NOT over-ream - Final reamer = stem size or stem 0.5mm oversized - Press fit achieved by stem taper or diaphyseal engaging portion - Over-reaming weakens cortex and reduces press fit **Depth Measurement** - Check depth with ruler or depth gauge - Compare to preoperative template - Confirm with fluoroscopy AP and lateral **Clear Debris** - Copious irrigation and suction after each reamer pass - Remove reaming debris - Remove fat emboli (reduce fat embolism syndrome risk) **Type IV - No Reaming** - Canal widely patent, no cortical contact possible - Reaming futile - will not achieve fixation - SKIP reaming - Plan for cemented long stem (rarely used) OR - Proximal femoral replacement (PFR) - usual choice **Exam Key Point**: "Femoral canal preparation: I ream to DIAPHYSEAL cortical contact - chatter and resistance indicates cortex reached. Need 2cm MINIMUM scratch fit (prefer 4-7cm) for stable fixation in revision. For Type I/II I may achieve some metaphyseal fixation. For Type II/III I must achieve DIAPHYSEAL fixation only - metaphyseal bone cannot be trusted, I bypass defects by 2 cortical diameters. I ream line-to-line progressive (0.5mm increments), straight alignment, gentle technique. In bowed femurs I use smaller diameter or flexible reamers to avoid anterior perforation at bow apex. Fluoroscopy confirms depth and position AP/lateral. Type IV widely patent canal - no cortical contact possible, cannot ream to fit, needs PFR instead." - Perforation during reaming (2-5%) - especially bowed femurs, thin cortex, eccentric reaming - Inadequate distal cortical contact - subsidence, early loosening (most common failure mode) - Over-reaming - weakens cortex, reduces press fit, increases fracture risk - Reaming eccentrically - varus or valgus stem position, abnormal stress distribution - Not bypassing metaphyseal defects adequately - stress riser at defect edge, fracture risk - Fat embolism from aggressive reaming - hypoxia, confusion, petechiae (rare but serious) ### Steps 7-15: See Stem Selection Tab for Type-Specific Reconstruction Details *(Remaining steps include Type I/II reconstruction, Type IIIA/B reconstruction, Type IV PFR, trial reduction, ETO repair, closure, complications, imaging, and outcomes - see other tabs for complete details)* ## Complications - Recognition, Prevention, and Management ### Additional Complications **Leg Length Discrepancy (10-15%)** - Common in revision due to bone loss, soft tissue laxity - Aim within 1cm equality - Some lengthening (1-2cm) acceptable for stability if nerve not tight - Excessive lengthening (>4cm) increases sciatic nerve palsy risk (2-5%) - Management: If noticed intraoperatively, adjust before closure. Post-operative: shoe lift if <2cm, may need revision if >3cm and symptomatic **Chronic Thigh Pain (10-20%)** - More common with extensively coated stems than primary THR (2-5%) - Causes: distal stem tip stress transfer, inadequate proximal load transfer, micromotion - Usually mild and improves over 1-2 years as osseointegration occurs - Management: NSAIDs, activity modification, reassurance. If severe and persistent: re-revision (rarely needed) **DVT/PE (2-3%)** - Higher risk than primary due to longer surgery, more blood loss, revision status - Prevention: DVT prophylaxis with LMWH or DOAC for 4-6 weeks, early mobilization, compression stockings - Recognition: leg swelling, pain, positive Homan's sign (DVT), dyspnea, chest pain, hypoxia (PE) - Management: Imaging (duplex ultrasound for DVT, CT angiography for PE), anticoagulation **Blood Loss and Transfusion (30-50% transfusion rate)** - Average blood loss 500-1000mL, can be higher with extensive surgery - Prevention: Tranexamic acid 1g IV pre-incision + 1g at closure, cell saver, minimize operative time, meticulous hemostasis - Management: Transfusion if Hb <70 or symptomatic (chest pain, SOB, tachycardia) **Heterotopic Ossification (5-10% with prophylaxis)** - Ectopic bone formation around hip - Risk factors: revision surgery, extensive dissection, male gender, previous HO - Prevention: Indomethacin 75mg PO daily for 6 weeks OR single-dose radiation 700 cGy within 24 hours post-op - Management: If mild (Brooker I-II), observe. If severe (Brooker III-IV) with restricted ROM: excision after maturation (12-18 months) **Abductor Insufficiency and Trendelenburg Gait (5-10%)** - Causes: Superior gluteal nerve injury, abductor detachment or non-healing, GT non-union or escape - Recognition: Trendelenburg gait (pelvis drops on opposite side during swing), abductor weakness - Prevention: Protect superior gluteal nerve (avoid dissection >5cm above GT), repair abductors securely, ensure ETO healing - Management: Physical therapy for abductor strengthening, cane use. If severe: abductor reconstruction (repair, advancement, allograft augmentation) ## References 1. Paprosky WG, Greidanus NV, Antoniou J. Minimum 10-year-results of extensively porous-coated stems in revision hip arthroplasty. Clin Orthop Relat Res. 1999;369:230-242. *Landmark study establishing Paprosky femoral classification and extensively coated stem outcomes - 90-95% 10-year survival with adequate diaphyseal fixation.* 2. Della Valle CJ, Paprosky WG. The femur in revision total hip arthroplasty evaluation and classification. Clin Orthop Relat Res. 2004;420:55-62. *Definitive review of Paprosky femoral classification system - essential for exam preparation and surgical planning.* 3. Younger TI, Bradford MS, Magnus RE, Paprosky WG. Extended proximal femoral osteotomy: a new technique for femoral revision arthroplasty. J Arthroplasty. 1995;10(3):329-338. *Original description of extended trochanteric osteotomy technique - anterior 1/3 circumference, muscle pedicle preservation, excellent canal access.* 4. Lakstein D, Backstein D, Safir O, et al. Revision total hip arthroplasty with a porous-coated modular stem: 5 to 10 years follow-up. Clin Orthop Relat Res. 2010;468:1310-1315. *Modular tapered stem outcomes in revision THA - 85-90% 10-year survival, excellent for complex reconstructions with offset/version control.* 5. Wagner H, Wagner M. Cone prosthesis for the hip joint. Arch Orthop Trauma Surg. 2000;120:88-95. *Original Wagner cone (modular tapered) stem design and technique - self-locking taper achieves diaphyseal fixation, proven track record.* 6. Miner TM, Momberger NG, Chong D, Paprosky WL. The extended trochanteric osteotomy in revision hip arthroplasty: a critical review of 166 cases at mean 3-year, 9-month follow-up. J Arthroplasty. 2001;16(8 Suppl 1):188-194. *Large series ETO outcomes - non-union 5-10% (most asymptomatic), trochanteric escape <2%, excellent access for cement removal and stem extraction.* 7. Mumme T, Müller-Rath R, Andereya S, et al. Uncemented femoral revision arthroplasty using a modular tapered, fluted titanium stem: 5- to 16-year results of 163 cases. Acta Orthop. 2007;78(4):454-460. *Long-term modular tapered stem outcomes - 83% survival at 10 years, subsidence main failure mode if inadequate diaphyseal fixation.* 8. Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Hip, Knee & Shoulder Arthroplasty: 2023 Annual Report. Adelaide: AOA; 2023. *Australian registry data: femoral revision 10-year survival 86.3% overall, extensively coated stems superior to cemented, Type I/II better outcomes than Type III/IV.* 9. Haddad FS, Masri BA, Garbuz DS, Duncan CP. The prevention of periprosthetic fractures in total hip and knee arthroplasty. Orthop Clin North Am. 1999;30(2):191-207. *Prevention strategies for periprosthetic fractures - ETO for well-fixed stems, cortical strut grafts for defects, appropriate stem sizing critical.* 10. Springer BD, Berry DJ, Lewallen DG. Treatment of periprosthetic femoral fractures following total hip arthroplasty with femoral component revision. J Bone Joint Surg Am. 2003;85-A(11):2156-2162. *Management of Vancouver B fractures in revision setting - B1 ORIF preserve stem, B2 revision to longer stem + ORIF, B3 long stem or PFR + strut grafts.*

Revision Total Hip Replacement - Femoral Component

Revision Total Hip Replacement - Femoral Component