import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: Exits pelvis through greater sciatic foramen, passes posterior to hip joint 15-30mm from posterior capsule. Stretched with hip extension, adduction, internal rotation (combined increases tension). Most at risk during ETO hinging and posterior retractor placement. **Protection**: Maintain hip flexed and externally rotated. Avoid aggressive posterior retraction. Palpate nerve before placing retractors. Monitor for post-op foot drop. If lengthening required, shortening osteotomy rather than stretching nerve. **Location**: Femoral artery 25-40mm medial to anterior hip capsule at psoas tendon level. Femoral nerve lateral to artery. Profunda femoris branches at risk during anterior/lateral capsule release. **Protection**: Anterior retractor must rest ON BONE (anterior acetabular wall). Never lever anteriorly. Identify and protect if using anterior approach. If arterial injury - immediate pressure, call vascular surgery, have clamps available. **Location**: Exits pelvis above piriformis, travels between gluteus medius and minimus. Safe zone is approximately 5cm proximal to greater trochanter tip - do NOT dissect proximally. Supplies abductors - injury causes Trendelenburg gait. **Protection**: Stay within 5cm of trochanter tip. Do not extend ETO too proximally. Avoid blunt dissection in gluteus medius-minimus interval. If abductor weakness post-op, assess for nerve injury. **Location**: Lateral femoral cortex where ETO is performed. At risk for iatrogenic fracture if osteotome misaligned, if cortex weakened by osteolysis, or if ETO not properly controlled. Propagation distally can compromise stem fixation zone. **Protection**: Mark ETO precisely (anterior 1/3 circumference). Use oscillating saw with bone protection. Control osteotome direction. Assess for lytic lesions on preop CT. Complete the osteotomy in controlled fashion before hinging. **Location**: Medial femoral circumflex artery provides primary blood supply to femoral head remnant - less critical in revision but important in periprosthetic fracture. Deep branch courses posterior to quadratus femoris. **Protection**: If significant bone loss proximally, consider vascularity of remaining proximal femur. Avoid circumferential stripping. If avascular necrosis develops, may need proximal femoral replacement. **Patient Position**: Lateral decubitus with pelvic posts **Surgical Approach**: Posterior or posterolateral (extended trochanteric osteotomy often needed) **Essential Equipment**: Fluoroscopy, revision stem set (extensively porous options), ETO instrumentation (oscillating saw, osteotomes), cable/wire fixation system, high-speed burr, cement removal tools, flexible reamers, backup stems (modular, cemented, proximal femoral replacement) ### Paprosky Femoral Bone Loss Classification | Type | Description | Bone Loss | Isthmus | Recommended Implant | |------|-------------|-----------|---------|---------------------| | I | Minimal bone loss | Calcar intact, minimal metaphyseal damage | Intact | Standard primary or revision stem | | IIA | Calcar damaged | Calcar loss, metaphyseal damage | Intact | Extensively porous stem or tapered wedge | | IIB | Calcar damaged + metaphyseal | Calcar + proximal metaphysis affected | Intact | Extensively porous stem | | IIC | Calcar + metaphyseal + some diaphyseal | Significant proximal bone loss | Partially damaged | Extensively porous stem (may need ETO) | | IIIA | Extensive proximal + diaphyseal damage | Major bone loss | MORE than 4cm supportive | Extensively porous stem + ETO | | IIIB | Extensive with inadequate isthmus | Major bone loss | LESS than 4cm supportive | PFR, impaction grafting, or APC | **Key Decision Points:** - Type I-II: Standard revision stem often sufficient - Type IIIA: Extensively porous stem bypassing defect to engage 4-5cm of isthmus (MOST COMMON EXAM SCENARIO) - Type IIIB: Insufficient bone for diaphyseal fixation - consider proximal femoral replacement ### Revision Stem Options | Stem Type | Mechanism | Indication | Examples | |-----------|-----------|------------|----------| | Extensively porous stem | Diaphyseal scratch fit + bone ingrowth | Paprosky IIB-IIIA with more than 4cm isthmus | AML Revision, Solution, Restoration | | Modular tapered wedge | Distal diaphyseal fixation + modularity for offset/length | Complex revisions needing adjustment | Wagner SL, Revitan, ZMR | | Cemented long stem | Cement mantle in diaphysis | Elderly, poor bone quality, IIIB with some isthmus | Exeter revision, Lubinus SPII | | Proximal femoral replacement | Prosthetic replacement of proximal femur | IIIB, tumor, massive bone loss | GMRS, MUTARS | | Allograft-prosthetic composite | Allograft + cemented stem | Massive bone loss needing restoration | Custom | **Extensively Porous Stem Features:** - Full circumferential porous coating (entire stem) - Relies on diaphyseal scratch fit for initial stability - Bypasses metaphyseal defect to engage intact isthmus - Requires 4-5cm of intact cortical bone for fixation - May need ETO for insertion and cement removal ### Extended Trochanteric Osteotomy **Indications for ETO:** - Well-fixed cementless stems requiring removal - Cement removal from femoral canal - Improved access for distal cement or stem extraction - Correcting proximal femoral deformity - Visualization of femoral canal **Technique:** | Step | Detail | |------|--------| | Marking | 8-12cm length (depending on stem length), anterior 1/3 circumference | | Proximal cut | Oscillating saw just below vastus ridge, angled towards femoral canal | | Distal cut | Transverse or chevron cut, 1-2cm below intended stem tip level | | Osteotomes | Connect cuts through lateral cortex, control propagation | | Hinging | Hinge fragment posteriorly, PRESERVING GLUTEUS MEDIUS ATTACHMENT | | Cement removal | High-speed burr, ultrasonic cement removal if needed | | Stem insertion | Trial and final stem through ETO window | | Repair | Minimum 3 cerclage cables/wires, proximal-mid-distal levels | **ETO Preservation Rules:** - NEVER detach gluteus medius from trochanteric fragment - Protect vastus lateralis attachment anteriorly - Fragment should remain hinged posteriorly on soft tissue sleeve ### Extensively Porous Stem Fixation **Scratch Fit Concept:** - Stem engages diaphyseal cortex with interference (scratch) fit - Initial rotational and axial stability from cortical contact - Porous coating allows bone ingrowth for long-term fixation - Requires 4-5cm of contact with intact isthmus **Achieving Scratch Fit:** | Principle | Application | |-----------|-------------| | Sequential broaching | Start small, increase until cortical resistance felt | | Scratch test | Broach should scratch against cortical bone when inserted/removed | | Fluoroscopy | Confirm broach position and fit in isthmus | | Trial stem | Confirm stability with trial - should not rotate or subside | | Final stem | Same size or 0.5mm larger than final trial broach | **ETO Fixation:** | Component | Specification | |-----------|---------------| | Cerclage cables | Minimum 3 (proximal, mid, distal) | | Cable position | One proximal to ETO, one mid-fragment, one at distal tip | | Tension | Cables tensioned to 120-150 lbs (avoid over-tightening = fracture) | | Alternative | Braided wire if cable system unavailable | | Protection | 6 weeks partial weight bearing, avoid hip abduction load | ### Revision THA Outcomes **AOANJRR Data (2023):** - Revision THA 10-year survival: approximately 85% - Cementless revision stems: superior survival in younger patients - Extensively porous stems: 90% 10-year survival for Paprosky IIIA **ETO Outcomes:** | Outcome | Rate | Notes | |---------|------|-------| | ETO union | 95% | With proper cable fixation and protection | | Trochanteric nonunion | 2-5% | Higher with inadequate fixation | | Abductor dysfunction | 5-10% | Usually temporary if gluteus medius preserved | | Intraoperative fracture | 5-10% | Higher in osteoporotic bone | **Extensively Porous Stem Results:** | Study | Follow-up | Survival | Subsidence | |-------|-----------|----------|------------| | Paprosky et al. | 14 years | 95% | 5% early, stable | | Sporer et al. | 10 years | 94% | Minimal | | Berry et al. | 15 years | 89% | 8% | **Key Evidence Points:** - Extensively porous stems reliable for Paprosky IIB-IIIA defects - ETO facilitates stem insertion and cement removal without compromising outcomes - Scratch fit essential - insufficient fixation leads to subsidence - IIIB defects should consider proximal femoral replacement ### Step 1: POSITIONING AND APPROACH LATERAL DECUBITUS POSITIONING: Standard lateral position with pelvic posts. Wide draping to allow extensibility if needed. Ensure fluoroscopy can access entire femur. Mark landmarks: greater trochanter, shaft axis, previous incision. Use PREVIOUS INCISION if possible - posterior or posterolateral approach most common. Develop interval through scar tissue. Identify and protect sciatic nerve before proceeding deeper. **Technical Tip**: EXAM KEY: Lateral position allows access to entire femur for ETO and stem insertion. Wide drape because you may need to extend distally for fracture or cement removal. Previous incision reduces wound complications vs new incision through scar. - Sciatic nerve injury if not identified in scar tissue - Wound complications from crossing previous incision ### Step 2: EXPOSURE AND ASSESSMENT DEEP EXPOSURE: Identify posterior capsule (often absent from prior surgery), short external rotators (may be deficient). Assess abductor mechanism - critical for function. Dislocate hip (may be already dislocated or very easy if unstable). Remove femoral head if present. ASSESS STEM: Is it loose or well-fixed? Gross loosening allows extraction without ETO. Well-fixed stems REQUIRE ETO for controlled removal. **Technical Tip**: EXAM KEY: If stem is LOOSE, extract directly and skip ETO. If stem is WELL-FIXED (cementless with good ingrowth or cemented with good mantle), ETO is REQUIRED for controlled extraction without fracture. Decision made BEFORE osteotomy. - Iatrogenic fracture attempting to extract well-fixed stem without ETO - Abductor damage if not carefully preserved ### Step 3: EXTENDED TROCHANTERIC OSTEOTOMY (ETO) - MARKING ETO INDICATIONS: Well-fixed stem, cement removal needed, improved access required. MARKING: Length 8-12cm (must extend 1-2cm beyond stem tip). Width: anterior 1/3 of femoral circumference. Mark with bovie/sterile marker. Preserve GLUTEUS MEDIUS attachment to trochanteric fragment - this is CRITICAL. Identify vastus lateralis anteriorly. **Technical Tip**: EXAM KEY: ETO length = stem length + 1-2cm. Anterior 1/3 circumference maintains posterior soft tissue sleeve for gluteus medius. NEVER disconnect gluteus medius from trochanteric fragment - this causes Trendelenburg gait. - Too short ETO = cannot extract stem/cement - Gluteus medius detachment = permanent abductor weakness ### Step 4: ETO - OSTEOTOMY EXECUTION PROXIMAL CUT: Oscillating saw at junction of trochanter and lateral femoral cortex, angled toward femoral canal (chevron or transverse). DISTAL CUT: Transverse or chevron cut 1-2cm beyond stem tip. LONGITUDINAL CUTS: Connect proximal and distal with thin oscillating saw blade or osteotomes. HINGING: Use wide osteotomes to carefully hinge fragment posteriorly on soft tissue sleeve. Do NOT detach fragment. **Technical Tip**: EXAM KEY: Chevron cuts provide better rotational stability at repair. Control saw depth to avoid cutting into stem/cement. Hinge posteriorly maintaining gluteus medius and vastus lateralis attachments. Fragment should remain attached to posterior soft tissue. - Uncontrolled fracture propagation distally - Complete trochanteric fragment detachment - Cortical perforation into stem/cement ### Step 5: STEM AND CEMENT REMOVAL STEM EXTRACTION: With ETO open, direct access to stem-bone interface. Use specialized stem extraction tools. Apply distal blows to extract stem. For well-fixed cementless: may need to disrupt ingrowth interface. CEMENT REMOVAL: High-speed burr for cement mantle. Ultrasonic cement removal tools if available. Remove ALL cement - retained cement compromises new fixation. ASSESS CANAL: Curette canal, remove granulation tissue, assess bone quality. **Technical Tip**: EXAM KEY: Complete cement removal is ESSENTIAL - retained cement prevents bone ingrowth and proper fixation. Use flexible reamers to assess canal patency. Fluoroscopy confirms complete cement removal. High-speed burr = most effective for cement. - Cortical perforation with burr or reamers - Retained cement compromising fixation - Canal fracture with aggressive extraction ### Step 6: CANAL PREPARATION - BROACHING SEQUENTIAL BROACHING: Start with smallest extensively porous broach. Advance sequentially until SCRATCH FIT achieved. Broach should scratch against cortical bone when inserted/removed - this indicates appropriate interference fit in diaphysis. FLUOROSCOPY: Confirm broach position in isthmus, alignment, and length. Goal: 4-5cm of cortical contact in isthmus for stable fixation. **Technical Tip**: EXAM KEY: SCRATCH FIT = broach scratches cortical bone on insertion/removal. If no resistance, broach too small. If cannot advance, broach too large or eccentric. Must achieve 4-5cm of isthmus contact. Extensively porous stems rely on DIAPHYSEAL fixation, NOT metaphyseal. - Undersized broach = stem subsidence - Oversized broach = fracture - Eccentric broaching = cortical perforation ### Step 7: TRIAL STEM ASSESSMENT TRIAL INSERTION: Insert trial stem matching final broach size. Assess: (1) STABILITY - stem should not rotate or subside with torsional/axial load; (2) LENGTH - compare to contralateral, use measured markers; (3) OFFSET - assess soft tissue tension with trial heads; (4) POSITION - confirm alignment on fluoroscopy. If trial unstable, reassess - may need larger stem or different fixation strategy. **Technical Tip**: EXAM KEY: Trial MUST be stable before proceeding to final stem. If trial rotates with hip rotation = inadequate scratch fit, need larger stem. Leg length assessed with trial heads - use spacer blocks for comparison. Soft tissue tension guides offset selection. - Proceeding with unstable trial = stem subsidence - Over-lengthening = sciatic nerve palsy - Inadequate offset = instability ### Step 8: FINAL STEM INSERTION FINAL STEM: Insert final extensively porous stem. Same size or 0.5mm larger than trial. Advance with controlled mallet blows. Confirm scratch fit achieved. FLUOROSCOPY: Confirm position, alignment, length. Stem should bypass metaphyseal defect to engage diaphysis. HEAD SELECTION: Trial heads for offset and length optimization. Final head impaction. **Technical Tip**: EXAM KEY: Final stem should achieve same scratch fit as trial. If easier to insert than trial, may be undersized - have larger stem available. Modular necks available if standard offset options insufficient. Document final head selection and combined offset. - Stem subsidence if inadequate scratch fit - Fracture with excessive force - Malalignment if not checked with fluoroscopy ### Step 9: ETO REPAIR REDUCE ETO FRAGMENT: Anatomic reduction of trochanteric fragment. Fragment should approximate flush with lateral cortex. CABLE FIXATION: Minimum 3 cerclage cables (proximal, mid-fragment, distal to ETO). Tension cables to 120-150 lbs. Additional cables if needed for stability. CONFIRM: Fragment stable, no motion with hip ROM, cables secure. **Technical Tip**: EXAM KEY: Minimum 3 cables = one proximal to fragment, one mid-fragment, one at distal tip. Cable > wire for revision surgery. Do NOT overtighten = fracture. Fragment must be stable before closure - ETO nonunion compromises abductors. - Inadequate fixation = trochanteric nonunion - Overtightened cables = fragment fracture - Malreduction = abductor dysfunction ### Step 10: STABILITY TESTING AND CLOSURE FINAL ASSESSMENT: Full range of motion testing. Check stability in flexion/adduction/internal rotation (posterior dislocation position). Check anterior stability in extension/external rotation. LEG LENGTH: Final clinical and fluoroscopic assessment. CLOSURE: Posterior capsule repair if tissue available, short external rotators if present, layered closure. DRAIN if significant dead space. **Technical Tip**: EXAM KEY: Stability testing with various head/liner combinations if concerned. Dual-mobility liner option if high instability risk. Abduction brace or hip precautions based on soft tissue integrity and stability assessment. - Missed instability = early dislocation - Leg length discrepancy = patient dissatisfaction, nerve injury - Inadequate closure = infection risk ## References 1. Paprosky WG, et al. Acetabular defect classification and surgical reconstruction in revision arthroplasty: a 6-year follow-up evaluation. J Arthroplasty. 1994;9(1):33-44. **LEVEL IV** 2. Sporer SM, Paprosky WG. Revision total hip arthroplasty: the limits of fully coated stems. Clin Orthop Relat Res. 2003;417:203-209. **LEVEL IV** 3. Lakstein D, et al. Extended trochanteric osteotomy for the management of major femoral bone defects. J Arthroplasty. 2014;29(5):971-976. **LEVEL IV** 4. AOANJRR. Hip, Knee & Shoulder Arthroplasty: 2023 Annual Report. Australian Orthopaedic Association National Joint Replacement Registry. 2023. **LEVEL II (Registry)** 5. Berry DJ, et al. Femoral revision: the outcome of cementless stems. Instr Course Lect. 2001;50:337-344. **LEVEL IV** 6. Della Valle CJ, Paprosky WG. The femur in revision total hip arthroplasty: evaluation and classification. Clin Orthop Relat Res. 2004;420:55-62. **LEVEL V** 7. Engh CA, et al. Cementless acetabular and femoral revision: 5-year follow-up study. J Arthroplasty. 1993;8(5):455-463. **LEVEL IV** 8. Weeden SH, Paprosky WG. Minimal 11-year follow-up of extensively porous-coated stems in femoral revision total hip arthroplasty. J Arthroplasty. 2002;17(4):134-137. **LEVEL IV** 9. Moreland JR, Bernstein ML. Femoral revision hip arthroplasty with uncemented, porous-coated stems. Clin Orthop Relat Res. 1995;319:141-150. **LEVEL IV** 10. MacDonald SJ, et al. Extended trochanteric osteotomy for femoral component removal. J Arthroplasty. 1999;14(5):546-550. **LEVEL IV**

THA Revision - Femoral Component (Extensively Porous Stem)

THA Revision - Femoral Component (Extensively Porous Stem)