High Yield Overview

REVISION TOTAL HIP REPLACEMENT

Complex arthroplasty procedure addressing failed primary hip replacement through component extraction, bone defect management, and reconstruction. Requires comprehensive preoperative assessment, infection exclusion, bone stock classification (Paprosky), and tailored reconstruction strategy based on defect pattern. | advanced

Critical Danger Structures - Know Location and Protection

Sciatic Nerve

Location: Exits pelvis inferior to piriformis, runs posterior to hip joint 2-3cm medial to greater trochanter tip, may be scarred to posterior tissues in revision, altered position if leg length changed previously.

Protection: Identify early at inferior border piriformis if anatomy recognizable, protect throughout with retractors under direct vision, keep hip flexed to relax nerve, gentle dissection through scar tissue, avoid overlengthening >4cm (nerve cannot stretch >6%), palpate after final reduction to ensure no tension.

Superior Gluteal Neurovascular Bundle

Location: Exits greater sciatic notch superior to piriformis, runs 25-40mm proximal to greater trochanter tip between gluteus medius and minimus layers, at risk during proximal gluteus dissection and retractor placement.

Protection: Limit superior dissection to <4cm above trochanter tip, place superior Hohmann retractors under direct vision above acetabular rim (not into gluteal muscle), avoid aggressive superior retraction, use self-retaining retractors with care.

Femoral Neurovascular Bundle

Location: Runs 30-50mm medial and anterior to acetabulum along iliopsoas muscle, femoral nerve lateral and artery/vein medial, at risk during anterior capsular release, anterior acetabular dissection, or anterior retractor placement.

Protection: Place anterior retractors carefully under direct vision over anterior acetabular rim (not deep to iliopsoas), avoid aggressive anterior dissection, gentle capsular release, be aware of distorted anatomy from bone loss or superior migration.

External Iliac Vessels (Intrapelvic)

Location: Run along pelvic brim 20-30mm from anterosuperior acetabular rim, 15-20mm from posterosuperior rim (intrapelvic surface), closer if bone loss present with superior/medial migration.

Protection: Acetabular screw safe zones - posteroinferior (3-5 o'clock right hip, 7-9 o'clock left hip) below transverse acetabular ligament, posterosuperior (10-11 o'clock right hip, 1-2 o'clock left hip) directed posteriorly. Avoid anterosuperior quadrant. Limit screw length to 20-25mm. Direct osteotomes along component rim during extraction (not through intrapelvic cortex).

Obturator Neurovascular Bundle

Location: Runs through obturator foramen 10-20mm inferior and medial to acetabulum, emerges into medial thigh, at risk during medial wall perforation or inferomedial screw placement.

Protection: Avoid screws directed inferiorly or medially (especially if medial wall deficient), recognize medial wall perforation during reaming (sudden loss of resistance), use acetabular protrusio rings carefully, ensure screws in safe zones only.

Mnemonic

REVISEREVISE - Revision THR Preoperative Assessment

Mnemonic

DEFECTSDEFECTS - Acetabular Bone Defect Management

Primary Indications

Aseptic Loosening (30-40% of Revisions)

Progressive pain with activity (start pain, groin pain, thigh pain)
Radiographic loosening criteria: progressive radiolucent lines >2mm, component migration >5mm, subsidence, osteolysis, change in position on serial radiographs
Symptomatic with functional limitation despite conservative management
Risk of impending fracture from progressive bone loss

Periprosthetic Joint Infection (15-20%)

MSIS (Musculoskeletal Infection Society) criteria for diagnosis
Major criteria: 2 positive cultures of same organism, sinus tract communicating with joint
Minor criteria: elevated ESR (>30mm/hr) or CRP (>10mg/L), elevated synovial WBC (>3000) or PMN (>80%), positive alpha-defensin, single positive culture
Definite infection: 1 major criterion OR 4/6 minor criteria

Recurrent Dislocation (20-25%)

≥2 dislocations despite closed reduction and conservative management
Chronic instability with inability to maintain reduction
Failed conservative measures: abduction brace, activity modification, physiotherapy
Identifiable cause requiring surgical correction: component malposition, impingement, soft tissue deficiency

Periprosthetic Fracture (10-15%)

Vancouver B2 femoral fractures - fracture around stem with stem loose
Vancouver B3 - fracture with poor bone stock
Acetabular fractures with component displacement or column involvement
Cannot achieve stable fixation without component revision

Osteolysis and Wear (10-15%)

Progressive bone loss from polyethylene or metal wear debris
Expanding osteolytic lesions threatening component stability
Risk of impending pathologic fracture
Symptomatic metallosis (metal-on-metal failures)

Preoperative Assessment

Infection Workup (Mandatory)

Serum inflammatory markers: ESR, CRP (elevated in 90% of infections)
Hip aspiration if ESR >30 or CRP >10 or any clinical suspicion
Synovial fluid analysis: cell count/differential (WBC >3000 or PMN >80% highly suggestive), culture and sensitivity (hold antibiotics minimum 2 weeks before aspiration)
Alpha-defensin or leukocyte esterase test if available (high specificity for infection)
False negative aspiration 10-15% - if high clinical suspicion proceed with intraoperative frozen section

Imaging Protocol

AP pelvis, lateral hip (both hips for comparison)
Judet views (obturator oblique, iliac oblique) for acetabular bone stock assessment
Full-length femur AP/lateral (assess femoral bone loss, stem position, distal canal anatomy)
CT scan with 3D reconstruction for severe bone loss (allows defect quantification, custom implant planning, surgical approach planning)
Metal artifact reduction sequences (MARS) MRI if soft tissue assessment needed

Bone Stock Classification

Paprosky acetabular: Type I (minimal, intact rim), IIA (superior loss, columns intact), IIB (superior/lateral loss), IIC (medial wall deficiency), IIIA (severe loss 2-3cm migration, Kohler intact), IIIB (Kohler violated, pelvic discontinuity possible)
Paprosky femoral: Type I (minimal metaphyseal loss), II (extensive metaphyseal loss, diaphysis >4cm intact), IIIA (metadiaphyseal loss, >4cm isthmus), IIIB (<4cm isthmus), IV (massive loss, widened canal)
Classification guides implant selection and predicts outcomes

Templating

Use revision-specific templates (extensively coated stems, jumbo cups, modular systems)
Plan femoral stem type: fully-coated for diaphyseal fixation (Type II/III), modular for bone loss (Type III/IV), tumor prosthesis for massive defects (Type IV)
Plan acetabular reconstruction: standard cup (Type I/IIA), jumbo cup (Type IIB), augments (Type IIC/IIIA), cage/triflange (Type IIIB)
Ensure implants available including extended sizes and backup options

Medical Optimization

Anemia correction: iron supplementation, EPO if Hb <120g/L (reduces transfusion requirements)
Nutritional optimization: albumin >35g/L, lymphocytes >1.5 (wound healing and infection resistance)
Glycemic control: HbA1c <7% in diabetics (reduces infection risk)
Smoking cessation: minimum 6 weeks preoperatively (improves bone healing and reduces infection)
VTE risk assessment: previous VTE, thrombophilia, malignancy (may need extended prophylaxis)
Cardiac/respiratory optimization: longer procedure with higher physiological stress than primary

Complications - Recognition, Prevention, Management

Major Complications in Revision Total Hip Replacement

Clinical Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 68-year-old woman presents with progressive groin pain 8 years after primary THR. Radiographs show progressive acetabular radiolucent lines and superior migration of the cup by 3cm. How do you assess and manage this case?"

EXCEPTIONAL ANSWER

This presentation suggests aseptic acetabular loosening, but infection must be excluded before proceeding with revision. My systematic assessment would include: 1) History - timing of pain onset, character (mechanical start pain suggests loosening vs constant pain with night symptoms suggests infection), functional limitation, risk factors for infection (previous wound issues, dental procedures, immunosuppression); 2) Examination - tenderness, range of motion (restriction suggests stiffness or heterotopic ossification), leg length discrepancy, neurovascular status, scars from previous surgery; 3) Infection workup MANDATORY - serum ESR and CRP (proceed with aspiration if ESR >30 or CRP >10 or any clinical suspicion), hip aspiration for cell count/differential (WBC >3000 or PMN >80% highly suggestive per MSIS criteria) and culture; 4) Imaging - AP pelvis and lateral hip (both hips for comparison to assess migration distance accurately), Judet views (assess acetabular columns and posterior wall), review serial radiographs (progressive radiolucent lines >2mm, progressive superior migration >5mm confirm loosening); 5) Bone stock assessment - 3cm superior migration suggests Paprosky Type IIIA defect (severe superior bone loss but Kohler line likely intact given the migration distance), assess for ischial lysis (suggests Type IIIA), medial wall integrity (Kohler line on AP pelvis); 6) CT scan with 3D reconstruction helpful for surgical planning (quantify bone loss, plan augment size/position, assess for pelvic discontinuity). If infection excluded (normal inflammatory markers and negative aspiration, or aspiration shows <3000 WBC and PMN <80%), proceed with revision planning. Surgical approach: posterior approach using previous scar, extended length incision for adequate exposure, plan for potential extensile exposure if needed. Acetabular reconstruction for Paprosky Type IIIA: Option 1 - jumbo cup with superior metal augment (tantalum/titanium wedge fixed to ilium with screws, cup contacts augment superiorly and remaining host bone anteroinferiorly), Option 2 - Trabecular Metal augments (highly porous tantalum contoured to fill superior defect, fixed with multiple screws, cup fixed to augment and host bone - allows biological fixation). Femoral side assessment: review radiographs for femoral loosening signs (radiolucent lines, subsidence), likely well-fixed femoral component given isolated acetabular loosening. If femoral component stable - leave in situ (isolated acetabular revision), if loose - revise both components. Postoperative: WBAT if standard uncemented reconstruction, hip precautions 12 weeks, VTE prophylaxis 35 days, close surveillance for infection and loosening. Expected outcomes: Paprosky Type IIIA acetabular reconstruction with augments has 85-90% survival at 10 years.

VIVA SCENARIOStandard

EXAMINER

"You are performing a revision THR for aseptic femoral loosening. The cemented femoral stem is well-fixed and you are having difficulty extracting it. The canal is narrow distally. What are your options and how do you proceed?"

EXCEPTIONAL ANSWER

Well-fixed cemented femoral stem extraction is challenging and carries high risk of femoral fracture if forced (uncontrolled fracture rate 20-30% with aggressive extraction vs <5% with controlled technique). My systematic approach: 1) Assess the situation - review preoperative radiographs for cement mantle extent (measure from lesser trochanter to distal cement plug), canal geometry (narrow distal canal limits extraction options), cortical thickness (thin osteoporotic cortices at higher fracture risk), previous surgery (prior fracture, plates, bone loss); 2) Decision point - attempt conventional extraction vs proceed directly to extended trochanteric osteotomy (ETO). Given well-fixed stem and narrow distal canal, ETO is strongly favored to avoid uncontrolled fracture. My preferred option: Extended Trochanteric Osteotomy - Technique: Mark osteotomy on lateral femur from proximal (vastus ridge) to 1-2cm past stem tip using cautery, width 1/3 femoral circumference (thinner fragments risk fracture, thicker difficult to reflect), perforate lateral cortex at multiple levels with 3.2mm drill creating stress risers for controlled fracture, complete longitudinal cuts anteriorly and posteriorly with oscillating saw, create controlled anterior fracture by gentle levering, reflect anteriorly as bone-muscle flap preserving vastus lateralis attachments (blood supply critical for healing). After ETO: stem extraction becomes straightforward (wide exposure allows sequential osteotomes at stem-cement interface working from proximal to distal, gentle extraction force with device, stem mobilizes easily), cement removal much easier (wide exposure, direct visualization, less perforation risk). Cement removal after stem extraction: proximal cement removal with osteotomes creating radial splits (fracture into fragments, remove with rongeurs/curettes), distal cement plug removal (drill through plug creating access, reverse cement hooks and curettes working proximally), high-speed burr for adherent cement (irrigate continuously to prevent thermal necrosis, avoid aggressive burring which perforates cortex), copious pulsed lavage irrigation, inspect with headlight and fiberoptic light confirming complete removal. Reconstruction after cement removal: classify femoral bone defects (Paprosky system - likely Type II given metaphyseal bone loss from cement removal), reconstruct with extensively coated cylindrical stem 8-10 inches achieving 4-6cm diaphyseal fixation, ETO fragment fixation with 3-4 cerclage cables placed 1-2cm apart (or plate if comminuted). Alternative if elect NOT to perform ETO (less favored): Cortical windowing - create rectangular windows in proximal femur to access stem, insert osteotomes at stem-cement interface, technically demanding with higher fracture risk, only suitable if surgeon very experienced and bone quality good. If stem not mobilizing after reasonable effort - STOP and convert to ETO rather than forcing. Third option (applicable in specific circumstances): Cement-in-cement technique - leave distal cement plug if unable to remove completely, drill through plug and ream, insert new cemented stem (cement-to-cement bond less favorable than cement-to-bone but acceptable in elderly low-demand patient, requires polished tapered cemented stem). Postoperative protocol if ETO performed: TDWB (touch-down 10-20kg) for 6 weeks allowing ETO healing, advance WBAT at 6 weeks if radiographic union evidence (bridging callus), full weight-bearing at 12 weeks once solid union. Expected outcomes: ETO union rate >95% if rigid fixation and soft tissue attachments preserved, extensively coated stem survival 90-95% at 10 years for Paprosky Type II defects.

VIVA SCENARIOStandard

EXAMINER

"Describe your management approach for a Paprosky Type IIIB acetabular defect in a 72-year-old patient with severe superior and medial migration, violation of Kohler's line, and suspected pelvic discontinuity."

EXCEPTIONAL ANSWER

Paprosky Type IIIB acetabular defect represents the most severe bone loss pattern - severe superior/medial migration, Kohler line violated indicating medial wall absent, and possible pelvic discontinuity (disruption of pelvic ring). This is a complex reconstruction requiring advanced techniques. My systematic approach: 1) Preoperative assessment - confirm Paprosky Type IIIB classification (radiographic criteria: severe bone loss >3cm migration, Kohler line violated on AP pelvis, possible step at ilioischial line suggesting discontinuity), CT scan with 3D reconstruction ESSENTIAL (quantifies bone loss, assesses discontinuity, allows custom implant planning if triflange considered), assess for discontinuity specifically (stress radiographs showing independent movement of superior/inferior hemipelvis, CT showing gap at anterior/posterior columns); 2) Surgical exposure - posterior approach using previous scar, extended length incision, may require trochanteric slide osteotomy for superior acetabular access, expose entire acetabulum circumferentially to assess defect pattern; 3) Confirm pelvic discontinuity intraoperatively - palpate for motion between superior and inferior hemipelvis (manual stress test - positive if motion detected), visualize gap at anterior or posterior column if present; 4) Reconstruction strategy for Type IIIB with discontinuity - two main options based on patient factors, surgeon experience, and available implants: OPTION 1 - Cup-Cage Construct (my preference for this 72-year-old patient, proven track record): Technique: First restore pelvic ring integrity if discontinuity confirmed - posterior column plate fixation if accessible (provides compression across discontinuity), insert antiprotrusio cage spanning from ilium to ischium (structural support not relying on bone ingrowth), fix cage to pelvis with multiple screws (iliac screws 2-3 with bicortical purchase, ischial screws 1-2, pubic screws if possible), cage provides immediate structural support bridging discontinuity, fill cavitary defects with particulate bone graft (morselized allograft behind cage), cement polyethylene cup within cage in correct orientation (40° abduction, 15° anteversion - cage position often not perfect so cemented cup allows orientation control), use dual mobility bearing within cemented cup (reduces dislocation risk in complex reconstruction - dislocation rate 5-10% with standard bearing vs 1-3% with dual mobility). Advantages: immediate structural support not relying on biology (suitable for elderly patient), restores hip center to near-anatomic position, cage spans discontinuity providing pelvic ring stability, proven outcomes (80-85% survival at 10 years). Disadvantages: cement fixation not biological (relies on cage remaining stable, cage screws can loosen over time), potential for cage failure or cement loosening long-term. OPTION 2 - Custom Triflange Implant (alternative, requires 6-8 week lead time for manufacture): Technique: preoperative CT scan with 3D reconstruction, patient-specific implant designed and manufactured (flanges shaped to match ilium/ischium/pubis anatomy), fix triflange to pelvis at three locations with multiple screws (iliac, ischial, pubic flanges), highly porous surface allows biological ingrowth, liner inserts into triflange component. Advantages: biological fixation (superior long-term stability in younger patients), restores anatomy better than cage. Disadvantages: 6-8 week manufacturing time (requires staged procedure if infection or urgent revision), expensive, long-term data limited (5-year survival 85-90%, 10-year data pending). For this 72-year-old patient, I favor cup-cage construct (immediate structural solution, suitable for age/activity level, proven track record). 5) Femoral side - assess femoral component stability separately (review radiographs, intraoperative assessment), if loose revise with appropriate technique based on bone loss, if well-fixed consider leaving in situ (isolated acetabular revision reduces surgical trauma); 6) Postoperative protocol - TDWB (touch-down 10-20kg) for 6-12 weeks to protect cage-bone interface and allow bone graft incorporation, advance to WBAT once pain settling and radiographic stability confirmed, hip precautions 12 weeks (extended due to high dislocation risk and soft tissue deficiency), dual mobility bearing reduces dislocation risk significantly, VTE prophylaxis 35 days (higher risk with longer operative time typically 4-5 hours for Type IIIB reconstruction), close surveillance for infection (longer operative time, bone graft, complex reconstruction all increase infection risk to 5-10%); 7) Outcomes and counseling - set realistic expectations with patient: Type IIIB reconstruction has guarded outcomes (80-85% survival at 10 years, inferior to less severe defects), pain relief typically good (70-80% achieve good pain relief) but not excellent, functional improvement significant but not to normal, re-revision risk higher (15-20% at 10 years), major complications higher (infection 5-10%, dislocation 5-10% even with dual mobility, cage/screw loosening 5-10%), but represents salvage option restoring function vs failed arthroplasty alternatives (resection arthroplasty poor function, arthrodesis rarely suitable for hip, amputation last resort). Despite challenges, cup-cage reconstruction can achieve stable pain-free hip in majority of patients.