REVISION TOTAL HIP ARTHROPLASTY
Complex Reconstruction | Bone Loss Management | Registry Data Critical
PAPROSKY ACETABULAR DEFECTS
Critical Must-Knows
- Aseptic loosening is the most common indication for revision THA (60-70%)
- Paprosky classification guides acetabular reconstruction strategy
- Component removal must preserve bone stock - avoid excessive reaming
- Infection must be ruled out - ESR, CRP, aspiration with culture in all cases
- AOANJRR data: Cemented stems have lower revision rate than uncemented in revision setting
Examiner's Pearls
- "Type IIIB acetabular defects require structural support (cage, triflange, or reconstruction ring)
- "Extended trochanteric osteotomy (ETO) provides excellent femoral stem exposure with low complication rate
- "Re-revision risk increases with each subsequent surgery - counsel patients accordingly
- "Australian registry shows higher failure rates for cementless acetabular components in revision
Clinical Imaging
Imaging Gallery
Critical Revision THA Exam Points
Indications
Aseptic loosening most common. Must exclude infection with CRP, ESR, aspiration. Recognize periprosthetic fracture, instability, liner wear, and osteolysis patterns.
Bone Defect Assessment
Paprosky classification drives treatment. Type I-II use hemispherical cups. Type IIIA needs augments. Type IIIB requires structural support with cage or custom implant.
Component Removal
Preserve bone stock at all costs. Use extended trochanteric osteotomy for well-fixed stems. Avoid aggressive reaming of acetabulum. Plan extraction before incision.
Reconstruction Principles
Restore hip center and offset. Achieve biologic fixation when possible. Use modular components. Address leg length discrepancy. Consider constrained liners for instability.
Quick Decision Guide: Revision THA Approach
| Clinical Scenario | Defect Type | Treatment Strategy | Key Pearl |
|---|---|---|---|
| Loosening, minimal bone loss, rim intact | Paprosky I-II acetabular, Cortical type femoral | Standard hemispherical cup, cementless stem | Prepare for one size larger cup |
| Superior migration under 3cm, posterior column intact | Paprosky IIIA acetabular | Jumbo cup with superior augment or bone graft | Superior dome augment restores hip center |
| Superior migration over 3cm, medial wall deficient | Paprosky IIIB acetabular | Cup-cage construct or custom triflange | Requires pelvic discontinuity assessment |
| Well-fixed stem needs removal, cortical thinning | Paprosky III femoral | Extended trochanteric osteotomy + long stem | ETO allows controlled extraction with bone preservation |
PAPROSKYPAPROSKY Acetabular Defect Classification
Memory Hook:PAPROSKY guides acetabular reconstruction from simple cups (Type I) to complex cages (Type IIIB) based on rim integrity and migration!
FAILSAFEIndications for Revision THA
Memory Hook:FAILSAFE captures all revision THA indications - aseptic loosening leads, but infection must be excluded in every case!
PREPAREDPreoperative Planning for Revision THA
Memory Hook:Be PREPARED for revision THA - planning prevents poor performance in complex bone loss scenarios!
Overview and Epidemiology
Why Revision THA Matters
Revision THA is one of the most technically demanding procedures in adult reconstruction. With increasing primary THA volumes and aging populations, revision burden is projected to increase by 137% by 2030. Australian registry data (AOANJRR) shows 18% cumulative revision rate at 15 years for primary THA, with aseptic loosening remaining the leading indication. Re-revision rates are significantly higher at 35% at 10 years, emphasizing the importance of getting the first revision right.
Demographics
- Age: Mean 65-70 years at revision (younger than primary)
- Gender: Slightly more common in males
- Time to revision: Median 10-12 years from primary
- Registry trend: Increasing revision volume despite improving implant survival
Impact
- Complication rate: 2-3x higher than primary THA
- Operative time: 2-4 hours (vs 1-1.5 hours for primary)
- Blood loss: Average 600-800ml (higher with bone loss)
- Hospital stay: 5-7 days vs 2-3 days for primary
Indications for Revision THA
Aseptic Loosening (60-70% of Revisions)
| Component | Radiographic Signs | Clinical Presentation | Threshold for Revision |
|---|---|---|---|
| Acetabular cup | Radiolucent lines over 2mm, cup migration, screw breakage | Groin pain with activity, start-up pain | Symptomatic loosening with function limitation |
| Femoral stem | Subsidence over 5mm, progressive radiolucency, cement mantle fracture | Thigh pain with weight-bearing, limp | Painful subsidence or osteolysis threatening bone stock |
| Both components | Dual loosening with osteolysis | Severe hip pain, reduced function | Symptomatic with deteriorating bone stock |
Key Investigation: Rule out infection with CRP, ESR, hip aspiration if inflammatory markers elevated.
Anatomy and Biomechanics
Hip Anatomy Relevant to Revision THA
Acetabular Anatomy
- Anterior column: Iliopubic - supports anterior rim and dome
- Posterior column: Ilioischial - supports posterior wall and dome
- Quadrilateral surface: Medial wall between columns
- Teardrop: Radiographic landmark for medial wall integrity
- Kohler's line: Assess medial cup migration
Femoral Anatomy
- Metaphysis: Proximal fit region for standard stems
- Diaphysis: Distal fixation zone for revision stems
- Isthmus: Narrowest point, critical for canal-filling stems
- Cortical thickness: Determines perforation risk during revision
- Canal geometry: Champagne-flute vs stovepipe shapes
Biomechanical Principles in Revision
Hip Center Restoration Critical
Anatomic hip center should be restored whenever possible:
- Superior migration increases joint reaction forces by 30-50%
- Increases abductor moment arm demands
- Leads to Trendelenburg gait and instability
- AAOS guideline: Restore center within 2cm of anatomic position
Accepting superior center trades short-term stability for long-term abductor insufficiency.
| Biomechanical Concept | Implication for Revision | Technical Solution |
|---|---|---|
| Load transfer acetabulum | Bone loss reduces load-bearing area | Maximize host bone contact, use augments to restore rim support |
| Load transfer femur | Metaphyseal deficiency prevents proximal fixation | Bypass defect, achieve distal diaphyseal fixation over 4cm |
| Offset restoration | Insufficient offset causes impingement and instability | Use modular stems, adjust neck length, plan templating |
| Leg length equality | Excessive lengthening causes nerve injury | Limit to under 4cm, accept slight shortness if needed |
Classification Systems
Paprosky Acetabular Defect Classification
| Type | Bone Loss Pattern | Rim Integrity | Treatment |
|---|---|---|---|
| Type I | Minimal bone loss, intact hemisphere | Rim intact, supportive | Standard hemispherical uncemented cup |
| Type IIA | Superior or medial bone loss, distorted hemisphere | Rim partially supportive | Hemispherical cup with medial graft or superior augment |
| Type IIB | Superior migration under 3cm, teardrop intact | Rim supportive | Hemispherical cup, possibly oversized (jumbo) |
| Type IIC | Medial wall deficiency, migration into pelvis | Rim intact | Hemispherical cup with medial augment or mesh |
| Type IIIA | Superior migration under 3cm, teardrop obscured | Rim partially supportive (over 50%) | Jumbo cup with superior augment or graft, cages if needed |
| Type IIIB | Superior migration over 3cm, medial wall deficient | Rim minimally supportive (under 50%) | Cup-cage construct, custom triflange, reconstruction ring |
IIIA vs IIIB Distinction
Key differentiator: Amount of supportive rim available. Type IIIA has over 50% host bone contact potential with jumbo cup. Type IIIB has under 50% contact, necessitating structural support. Migration over 3cm superior and medial wall deficiency = IIIB.
Clinical Assessment
History
- Pain characteristics: Groin (acetabular), thigh (femoral), start-up vs activity
- Functional limitation: Walking distance, stairs, ADLs
- Previous surgeries: Number, approaches, complications, implant types
- Infection symptoms: Prolonged wound drainage, fevers, systemic illness
- Instability: Number of dislocations, mechanism, closed reduction success
Examination
- Gait: Trendelenburg (abductor insufficiency), antalgic, limb length
- Scars: Previous incisions, quality, sinuses
- Range of motion: Terminal flexion pain (loosening), restricted arc
- Abductor strength: Assess gluteus medius integrity
- Leg length discrepancy: Measure from ASIS to medial malleolus
- Neurovascular: Baseline documentation (femoral pulse, sciatic function)
Red Flags for Infection
Any of these warrant aspiration before revision:
- Wound drainage persisting over 6 weeks from primary surgery
- Recurrent atraumatic dislocations (infection destabilizes soft tissues)
- Early failure (under 5 years) without mechanical explanation
- Constitutional symptoms (fevers, night sweats, weight loss)
- Elevated inflammatory markers (CRP over 10, ESR over 30)
Missing occult infection and proceeding with aseptic revision leads to catastrophic outcomes.
Functional Assessment Tools
Outcome Measures
100-point scale: pain (44), function (47), ROM (5), deformity (4). Score under 70 = poor, 70-79 = fair, 80-89 = good, 90-100 = excellent.
Western Ontario and McMaster Universities Osteoarthritis Index. 24 items covering pain, stiffness, function. Sensitive to change in revision.
12-item patient questionnaire. Score 0-48 (48 = best). Quick, validated for revision populations.
Investigations
Imaging Protocol
Radiographic Workup
AP pelvis and lateral hip. Assess Paprosky classification, measure migration, evaluate bone loss. Full-length femur (AP) including knee to assess femoral canal and plan stem length.
45-degree obturator and iliac obliques. Assess posterior and anterior column integrity. Essential for detecting pelvic discontinuity. Iliac oblique shows anterior column, obturator shows posterior column.
3D reconstruction of pelvis and femur. Measure precise bone loss volumes. Plan custom implants (triflange). Gold standard for pelvic discontinuity detection. Essential for preoperative planning in Paprosky IIIB.
Metal artifact reduction sequences (MARS) for pseudotumor in metal-on-metal bearings. Assess soft tissue (abductor tears). Not routinely needed for standard aseptic loosening.
Laboratory Investigations
| Test | Normal Value | Interpretation | Action |
|---|---|---|---|
| C-Reactive Protein (CRP) | Under 10 mg/L | Elevated in infection but also loosening, metallosis | If over 10: Aspiration recommended |
| Erythrocyte Sedimentation Rate (ESR) | Under 30 mm/hr | Less specific than CRP, elevated in many conditions | If over 30: Aspiration recommended |
| Hip Aspiration | WBC under 3000, PMN under 80% | Gold standard for infection diagnosis pre-revision | Send cell count, culture, consider alpha-defensin |
| Synovial Alpha-Defensin | Negative | Biomarker with high sensitivity/specificity for PJI | Adjunct when CRP/ESR equivocal, not first-line |
MSIS Criteria for PJI Diagnosis: Two positive cultures OR one of: sinus tract, elevated synovial WBC (over 3000), elevated synovial PMN (over 80%), positive alpha-defensin, or positive histology.
Templating and Preoperative Planning
Acetabular Templating
- Measure superior migration: Distance from teardrop to cup dome
- Assess medial wall: Kohler's line, teardrop integrity
- Classify defect: Paprosky I-IIIB based on rim integrity
- Plan implant: Hemispherical vs jumbo vs cage vs triflange
- Estimate size: Usually 2-4mm larger than primary cup
Femoral Templating
- Stem removal strategy: ETO if well-fixed, extraction if loose
- Canal diameter: Measure at isthmus and 4cm distal to stem
- Select stem type: Standard, extensively coated, modular tapered
- Plan length: Bypass defects by 2x diameter, minimum 4cm contact
- Restore offset: Template leg length and femoral offset
Management Algorithm
Decision Pathway by Paprosky Classification
Acetabular Reconstruction Strategy
Bone loss: Minimal, rim intact, hemisphere preserved. Treatment: Standard hemispherical uncemented cup. Ream to bleeding bone, under-ream 1-2mm for press-fit. Supplemental screws optional. Expected outcome: 85-90% survival at 10 years.
Bone loss: Superior or medial deficiency, distorted hemisphere, rim partially supportive. Treatment: Hemispherical cup (may be oversized) with medial bone graft (Type IIA) or superior support (Type IIB). Screws for supplemental fixation. Expected outcome: 80-85% survival at 10 years.
Bone loss: Superior migration under 3cm, teardrop obscured, over 50% rim supportive. Treatment: Jumbo cup (62-66mm) with superior metal augments or structural allograft. Multiple screws. Restore anatomic hip center. Expected outcome: 75-85% survival at 10 years.
Bone loss: Superior migration over 3cm, medial wall deficient, under 50% rim supportive. Treatment: Cup-cage construct (uncemented cup + Burch-Schneider cage) OR custom triflange (3D-planned flanges to ilium/ischium/pubis). If pelvic discontinuity: Column plating first. Expected outcome: 70-80% survival at 10 years.
Key Decision Point: Host bone contact potential determines implant selection. Over 50% contact = hemispherical cup achievable. Under 50% = structural support needed.
Surgical Technique
Surgical Approach Selection
| Approach | Advantages | Disadvantages | Best Use |
|---|---|---|---|
| Posterior (most common) | Extensile, excellent visualization, can extend distally | Abductor detachment risk if extends too superior | Most revision cases, especially femoral-sided work |
| Anterolateral (Watson-Jones) | Gluteus medius preserved, lower dislocation if primary was AL | Limited distal extension, abductor damage possible | Acetabular-only revisions, preserve abductors |
| Direct lateral (Hardinge) | Stable construct, good acetabular exposure | Abductor disruption, Trendelenburg risk | Isolated acetabular revisions with stable stem |
| Use previous incision | Avoids additional scars, preserves blood supply | May not be optimal for revision exposure | Default unless primary approach precludes adequate exposure |
Key Principle: Extensile exposure is critical. Do not hesitate to extend incision distally for femoral access or proximally for acetabular exposure. Poor visualization leads to complications.
Complications
| Complication | Incidence | Risk Factors | Management |
|---|---|---|---|
| Dislocation | 10-15% (vs 2-5% primary) | Abductor insufficiency, malposition, bone loss limiting constraint | Closed reduction, abduction brace. If recurrent: component revision to correct position or constrained liner |
| Infection | 2-10% (higher with bone loss) | Previous infection, wound issues, comorbidities, operative time over 3 hours | Acute (under 3 weeks): Debridement, liner exchange, antibiotics. Chronic: Two-stage revision with spacer |
| Aseptic loosening | 5-15% at 10 years (higher for cementless cups in revision) | Inadequate fixation, bone quality poor, infection | Re-revision with increased bone loss. AOANJRR shows cemented cups have lower revision rate in revision setting |
| Periprosthetic fracture | 3-5% | Osteoporosis, cortical perforation, ETO, forceful impaction | Intraoperative: Cable fixation, extend stem. Postoperative: ORIF if stem stable, revision if loose |
| Nerve injury | 1-3% (sciatic most common) | Leg lengthening over 4cm, posterior approach, retractor placement | Most are neurapraxia - observation for 6-12 months. EMG at 6 weeks if no recovery. Surgical exploration rarely indicated |
| Trochanteric nonunion (if ETO) | 5-7% | Inadequate fixation, patient noncompliance, infection | If asymptomatic: Observation. If symptomatic: Revision cable fixation, bone grafting, protected weight-bearing |
Preventing Catastrophic Complications
Key strategies:
- Exclude infection preoperatively - CRP, ESR, aspiration if any suspicion
- Avoid leg lengthening over 4cm - increases sciatic nerve stretch injury risk exponentially
- Plan component removal - ETO for well-fixed stems prevents perforation
- Restore hip center - superior migration increases dislocation and abductor insufficiency
- Obtain stable initial fixation - inadequate fixation leads to early loosening
Postoperative Care and Rehabilitation
Immediate Postoperative Period (Days 0-7)
DVT prophylaxis: Chemical (LMWH or rivaroxaban) + mechanical (sequential compression). Continue for 35 days. Pain management: Multimodal analgesia - paracetamol, NSAIDs if no contraindication, opioids as needed. Drain removal: When output under 30ml per 8 hours, typically 24-48 hours.
Weight-bearing status: Depends on fixation and bone quality.
- Standard revision (good fixation): Touch weight-bearing to partial weight-bearing
- Structural graft or cage: Touch weight-bearing for 6-12 weeks
- ETO: Partial weight-bearing for 6-12 weeks until union Mobilize with physiotherapy: Walker or crutches. Hip precautions if posterior approach.
Wound check: Monitor for drainage, erythema, dehiscence. Functional goals: Independent transfers, toilet, short distances with walking aid. Discharge criteria: Pain controlled, mobilizing safely, home supports arranged.
Hip Precautions (Posterior Approach): Avoid flexion over 90 degrees, adduction past midline, internal rotation for 6 weeks. Reduces dislocation risk from 15% to under 5%.
Outcomes and Prognosis
| Defect Type | Implant Strategy | Survival at 10 Years | Notes |
|---|---|---|---|
| Paprosky I-II acetabular | Hemispherical uncemented cup | 85-90% | Outcomes approach primary THA if good bone stock |
| Paprosky IIIA acetabular | Jumbo cup + augments | 75-85% | Augments provide better longevity than structural graft alone |
| Paprosky IIIB acetabular | Cup-cage or triflange | 70-80% | Custom triflange showing promising results in severe defects |
| Paprosky I-II femoral | Proximally coated stem | 90-95% | Excellent outcomes with modern cementless stems |
| Paprosky III-IV femoral | Modular tapered long stem | 85-90% | Bypassing defect with distal fixation highly successful |
Prognostic Factors
Good Prognosis
- Aseptic indication (no infection)
- Minimal bone loss (Paprosky I-II)
- Good bone quality (healthy host)
- First revision (not re-revision)
- Younger patient with good bone stock
Poor Prognosis
- Previous infection (even if eradicated)
- Severe bone loss (Paprosky IIIB, IV)
- Multiple prior revisions (re-revision)
- Medical comorbidities (uncontrolled diabetes, immunosuppression)
- Abductor deficiency (increases instability)
Australian Registry Insights
AOANJRR findings:
- Cemented acetabular components have lower revision rate than cementless in revision setting (contrary to primary THA)
- Re-revision rate 35% at 10 years highlights difficulty of revision surgery
- Infection accounts for higher proportion of re-revisions (20%) compared to primary revisions (10%)
- Modular femoral stems have higher revision rate than monoblock stems in revision setting
These registry findings should guide implant selection and patient counseling.
Evidence Base and Key Trials
Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR)
- 18% cumulative revision rate at 15 years for primary THA
- 35% re-revision rate at 10 years after first revision
- Aseptic loosening accounts for 60-70% of revision indications
- Cemented acetabular components have lower revision rate than cementless in revision setting
- Infection accounts for 20% of re-revisions vs 10% of primary revisions
Extended Trochanteric Osteotomy in Revision THA: Systematic Review
- Systematic review of 1,486 revision THAs with ETO
- Nonunion rate 5-7% with cable fixation
- Reoperation rate for ETO complications under 5%
- ETO facilitates safe removal of well-fixed stems and cement
- No difference in outcomes between ETO and standard femoral exposure when properly performed
Jumbo Cups for Revision THA: Long-term Results
- 170 hips revised with jumbo acetabular components (over 62mm)
- 92% survivorship at mean 11-year follow-up
- Paprosky Type IIA-IIB defects had best outcomes
- Host bone contact over 50% critical for success
- Screw fixation improved stability in deficient bone
Custom Triflange Acetabular Components in Complex Revision THA
- 128 hips with severe bone loss (Paprosky IIIB) treated with custom triflange
- 88% survivorship at 5 years
- Complication rate 18% (infection, dislocation, aseptic loosening)
- Significant functional improvement in all patients
- Superior outcomes compared to historical cages and antiprotrusio devices
Infection After Revision THA: Risk Factors and Prevention
- Meta-analysis: infection rate 2-10% after revision THA
- Risk factors: previous infection, obesity, diabetes, prolonged operative time
- Two-stage revision achieves 85-90% infection control
- Single-stage revision in selected cases achieves 80-85% success
- Extended antibiotic prophylaxis (24-48 hours) reduces infection vs single dose
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Aseptic Loosening with Bone Loss (approximately 3 minutes)
"A 68-year-old woman presents with progressive groin pain 12 years after primary THA. Radiographs show superior migration of the acetabular component by 2.5cm, with obscured teardrop. The femoral stem is well-fixed. CRP is 8, ESR is 25. How would you assess and manage this patient?"
Scenario 2: Femoral Component Removal with ETO (approximately 4 minutes)
"You are planning revision THA for a 72-year-old man with aseptic loosening of the acetabular component. The femoral stem is well-fixed and extensively porous-coated. Walk me through your approach to femoral component removal and reconstruction."
Scenario 3: Type IIIB Defect with Pelvic Discontinuity (approximately 3 minutes)
"Intraoperatively during revision THA, after removing a loose acetabular component, you discover severe superior and medial bone loss with independent motion between anterior and posterior columns. How do you proceed?"
MCQ Practice Points
Classification Question
Q: A 65-year-old patient has acetabular component loosening with superior migration of 3.5cm and medial wall deficiency. What Paprosky classification is this? A: Paprosky Type IIIB. Type IIIB is defined by superior migration over 3cm and typically includes medial wall deficiency. This differs from Type IIIA which has migration under 3cm. Type IIIB requires structural support (cage or triflange) whereas Type IIIA can often be managed with jumbo cup and augments.
Surgical Technique Question
Q: What is the minimum length an Extended Trochanteric Osteotomy should extend distal to the tip of a well-fixed femoral stem? A: The ETO should extend at least to the tip of the stem, and preferably 1-2cm beyond to allow adequate access for stem extraction. The total length is typically 10-15cm. The new revision stem must bypass the osteotomy by at least 2x the stem diameter distally to prevent stress concentration.
Evidence Question
Q: According to AOANJRR data, what is the approximate re-revision rate at 10 years after first revision THA? A: 35% at 10 years. This highlights that revision THA has significantly worse outcomes than primary THA (18% revision rate at 15 years). Re-revision risk increases with each subsequent surgery, emphasizing importance of getting the first revision right and counseling patients appropriately.
Complications Question
Q: What is the most common nerve injured during revision THA and what is the primary risk factor? A: Sciatic nerve is most commonly injured (1-3% incidence). Primary risk factor is leg lengthening over 4cm, which causes traction injury to the nerve. Risk increases exponentially with lengthening beyond 4cm. Other risk factors include posterior approach and prolonged retractor placement.
Management Question
Q: What is the threshold for host bone contact with a hemispherical cup below which structural support (cage) is typically required? A: Under 50% host bone contact typically requires structural support with a cage, reconstruction ring, or custom triflange. This corresponds to Paprosky Type IIIB defects. Over 50-70% contact (Type IIIA) can usually be managed with jumbo cup and augments alone.
Australian Context Question
Q: According to AOANJRR, do cemented or cementless acetabular components have better survival in the revision THA setting? A: Cemented acetabular components have lower revision rates than cementless in the revision setting according to AOANJRR data. This is contrary to primary THA where cementless cups perform better. The finding suggests biological fixation is more difficult to achieve in deficient bone, and cement may provide more reliable initial stability.
Australian Context and Medicolegal Considerations
AOANJRR Data
- 18% cumulative revision rate at 15 years for primary THA
- 35% re-revision rate at 10 years after first revision
- Aseptic loosening remains leading cause (60-70%)
- Cemented cups have lower revision rate than cementless in revision setting
- Modular femoral stems have higher revision rate than monoblock in revision
- Registry participation mandatory for all arthroplasty surgeons
Australian Guidelines
- ACSQHC Surgical Site Infection Prevention: Extended antibiotic prophylaxis (24 hours) for revision arthroplasty
- PBS coverage: Bone graft substitutes covered for revision procedures
- Consent requirements: Must document infection risk, dislocation risk, re-revision risk, nerve injury risk
Hospital Systems Considerations
Revision THA Pathway in Australian Public Hospitals
Symptomatic loosening typically triaged as Category 2 (target treatment within 90 days). Severe pain or bone loss threatening viability may warrant Category 1 (urgent, within 30 days).
Mandatory: CRP, ESR, radiographs (AP pelvis, lateral hip, full femur), hip aspiration if inflammatory markers elevated. CT scan if complex bone loss. Cardiac and anesthesia clearance.
Length of stay: Average 5-7 days vs 2-3 for primary. Blood cross-match 2-4 units. DVT prophylaxis 35 days. Physiotherapy daily. Occupational therapy for home modifications.
Supports: Arrange home modifications, community physiotherapy, walking aids. Follow-up at 6 weeks, 3 months, 12 months, then annually. Registry reporting.
Medicolegal Considerations in Revision THA
Key documentation requirements:
- Informed consent must include: Higher complication rates than primary (dislocation 10-15%, infection 5-10%, nerve injury 1-3%), re-revision risk 35% at 10 years, prolonged recovery 6-12 months, leg length discrepancy possibility
- Preoperative infection workup: Document CRP, ESR results. If aspiration performed, document indication and results. Failure to exclude infection before aseptic revision is major litigation risk
- Component selection rationale: Document why specific implant chosen (e.g., "Paprosky IIIA defect - jumbo cup with superior augment selected to restore hip center")
- Intraoperative complications: If perforation, fracture, or nerve injury occurs, document immediately and inform patient postoperatively
Common litigation issues:
- Unrecognized infection revised as aseptic (catastrophic outcome)
- Sciatic nerve injury from excessive leg lengthening (document leg length measured intraoperatively)
- Recurrent dislocation (document component position optimization and abductor repair)
- Early re-revision (document bone quality and fixation achieved)
Comprehensive documentation and realistic patient expectations are essential medicolegal protection.
REVISION THA
High-Yield Exam Summary
Key Classifications
- •Paprosky Acetabular: Type I (intact rim), Type II (distorted, superior/medial loss), Type IIIA (migration under 3cm, over 50% rim), Type IIIB (migration over 3cm, under 50% rim)
- •Paprosky Femoral: Type I (minimal loss), Type II (metaphyseal loss, diaphysis intact), Type IIIA (diaphysis over 4cm intact), Type IIIB (diaphysis damaged), Type IV (extensive loss)
- •Vancouver Fracture: A (trochanteric, stem stable), B1 (around stem, stable), B2 (around stem, loose), B3 (loose with poor bone), C (distal to stem)
- •Pelvic discontinuity = independent column motion, requires plating + cage/triflange
Surgical Approach
- •Type I-II acetabular: Hemispherical uncemented cup, ream to bleeding bone, under-ream 1-2mm
- •Type IIIA acetabular: Jumbo cup (over 62mm) + superior augments or structural graft, restore hip center
- •Type IIIB acetabular: Cup-cage construct or custom triflange, requires structural support
- •ETO for well-fixed femoral stem: 10-15cm distal to tip, anterior 1/3, posterior hinge, minimum 3 cables, bypass 2x diameter
Critical Steps
- •ALWAYS exclude infection: CRP/ESR, aspiration if elevated or suspicious
- •Plan component removal before incision: ETO for well-fixed stems prevents perforation
- •Restore anatomic hip center: Superior migration leads to abductor insufficiency
- •Achieve stable initial fixation: Inadequate fixation = early loosening
- •Minimum 4cm diaphyseal contact for femoral stems, bypass defects by 2x diameter
Surgical Pearls
- •Jumbo cups need over 50% host bone contact for success without cage
- •Metal augments have lower resorption than structural allograft
- •ETO union rate over 90% with cable fixation, nonunion risk 5-7%
- •Constrained liners for recurrent instability have 5-8% failure at 5 years
- •Leg lengthening over 4cm increases sciatic nerve injury risk exponentially
Complications
- •Dislocation 10-15% (vs 2-5% primary) - malposition, abductor insufficiency
- •Infection 2-10% (higher with bone loss, operative time over 3 hours)
- •Nerve injury 1-3% (sciatic from lengthening over 4cm)
- •Re-revision 35% at 10 years (counsel patients about high failure rate)
- •ETO nonunion 5-7% (protected weight-bearing 6-12 weeks)