High Yield Overview

REVISION TOTAL HIP REPLACEMENT - FEMORAL COMPONENT

Posterior approach (Moore/Southern) most common. Extended Trochanteric Osteotomy (ETO) frequently required for access to well-fixed cementless stems or cemented stems with distal cement. | advanced

Critical Danger Structures - 5 Specific Anatomical Zones

Danger 1: Sciatic Nerve

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

Danger 2: Femoral Shaft Perforation

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

Danger 3: Profunda Femoris Artery

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

Danger 4: Superior Gluteal Neurovascular Bundle

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

Danger 5: Femoral Nerve

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)

Mnemonic

PAIDPAPROSKY Femoral Classification

Mnemonic

CABLESETO Repair CABLE Fixation

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

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 68-year-old woman presents with progressive right hip pain 8 years after primary cementless THR. X-rays show progressive radiolucencies around the femoral stem with 7mm subsidence. Walk me through your management from initial workup to revision surgery."

EXCEPTIONAL ANSWER

This is aseptic femoral component loosening until proven otherwise. My initial workup: (1) RULE OUT INFECTION - mandatory. Serum ESR, CRP. Joint aspiration with cell count (WBC >3000 suspicious, PMN >80% concerning) and 14-day aerobic/anaerobic cultures. Alpha-defensin if equivocal. Cannot proceed to revision without excluding infection - missed infection is catastrophic. (2) IMAGING: AP pelvis, lateral hip, FULL LENGTH AP and lateral femur. Assess: subsidence (7mm significant), radiolucencies (progressive >2mm indicates loosening), Paprosky femoral bone loss classification (determine stem type needed), femoral bow, canal diameter, distal fixation zones. CT if severe bone loss for 3D assessment. (3) CLASSIFY bone loss: appears Paprosky Type II (metaphyseal damage, subsidence indicates metaphyseal bone unreliable, but diaphyseal cortex likely intact). If Type II confirmed: plan extensively coated stem 200-250mm for diaphyseal fixation. If Type IIIA/B: longer stem or modular tapered. (4) OPERATIVE PLANNING: Posterior approach, lateral position. Assess need for ETO - likely yes given cementless stem may be well-fixed despite subsidence. Have ETO instruments, long stems 200-300mm, cerclage cables, cortical strut grafts available. Blood: type and cross 2-4 units, cell saver. (5) SURGERY: Exposure via previous incision, identify sciatic nerve early. Assess stem fixation - if well-fixed, perform ETO (start 1-2cm below GT, anterior 1/3, 10-15cm length, muscle pedicle intact). Extract stem using curved osteotomes to disrupt ingrowth, gentle extraction. (6) BONE LOSS ASSESSMENT: confirm Paprosky type. Appears Type II. (7) CANAL PREPARATION: ream to diaphyseal cortical contact (chatter), achieve minimum 2cm (prefer 4-7cm) scratch fit. (8) STEM INSERTION: extensively coated cementless stem 200-250mm, sized 0.5mm larger than final reamer. Insert with mallet, confirms distal diaphyseal engagement (resistance), proximal loose (expected). Fluoroscopy confirms depth and position. (9) TRIAL REDUCTION: assess stability (posterior and anterior stability tests), leg length (aim within 1cm), offset. (10) ETO REPAIR: reduce GT anatomically, fix with 2-3 cerclage cables 1cm apart, tension 300-500N. (11) CLOSURE: layered, drain. (12) POST-OP: TDWB 6-12 weeks until ETO healed. DVT prophylaxis 4-6 weeks. Hip precautions 12 weeks. X-rays at 6 weeks (ETO healing), 3 months, 6 months, annually. Monitor for subsidence, loosening. Expected outcome: 85-90% 10-year survival with Type II defect if adequate diaphyseal fixation achieved.

VIVA SCENARIOStandard

EXAMINER

"You are performing femoral revision for a loose cemented stem with cement extending 15cm down the femoral canal. Describe your Extended Trochanteric Osteotomy technique in detail, including the key steps, anatomical landmarks, and how you would repair it."

EXCEPTIONAL ANSWER

Extended Trochanteric Osteotomy is indicated here for access to distal cement. Detailed technique: (1) EXPOSURE: Posterior approach, lateral position. Previous incision extended 18-25cm from PSIS to GT and distally along lateral femoral shaft. Split gluteus maximus, extensive scar release. CRITICAL: Identify sciatic nerve early and place vessel loop - nerve at risk during ETO and GT reflection. (2) MARK OSTEOTOMY with cautery: START 1-2cm DISTAL to GT tip (do NOT start at GT tip - weakens abductor insertion, increases trochanteric escape risk from 2% to 5%). Mark extends 12-15cm distally along anterior-lateral femoral shaft (longer osteotomy needed for extensive distal cement - must extend 2-3cm past distal cement for access). Mark indicates ANTERIOR 1/3 of femoral circumference only. Fluoroscopy confirms appropriate position and length before cutting. (3) 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 circumference. Do NOT cut posterior cortex - this preserves blood supply via periosteum. Do NOT cut more than 1/3 circumference - risk complete fracture. Copious irrigation during sawing prevents thermal necrosis. (4) COMPLETE OSTEOTOMY distally: Use straight osteotomes to complete osteotomy distally, initially leaving 2-3cm distal hinge intact. Then complete distal hinge with osteotome. (5) MUSCLE PEDICLE PRESERVATION: GT fragment remains ATTACHED to vastus lateralis anteriorly and gluteus medius/minimus superiorly. These muscle attachments form VASCULAR PEDICLE that maintains blood supply to GT - essential for healing. Do NOT detach muscles - will cause non-union. (6) GT REFLECTION: GENTLY reflect GT fragment ANTEROLATERALLY using Z-retractors. GT hinges on muscle pedicle. Now have excellent visualization of entire proximal and mid femoral canal - can see cement clearly. Protect sciatic nerve posteriorly during reflection - avoid excessive force (nerve palsy risk). (7) CEMENT REMOVAL: With excellent access, remove cement using high-speed burr, osteotomes, ultrasonic tools. Work proximal to distal methodically. Fluoroscopy confirms all cement removed. (8) PROCEED with femoral revision per bone loss classification. After stem insertion and trial reduction stable, repair ETO: (9) ETO REPAIR: Reduce GT fragment back to femoral shaft anatomically. Ensure NO ROTATION - fragment must sit flush with lateral cortex (check anterior and lateral cortical alignment). Hold with bone clamps. Place 2-3 CERCLAGE CABLES: Cable 1 proximal (at GT), Cable 2 middle osteotomy, Cable 3 distal osteotomy. Space cables 1cm apart. Use 16 or 18 gauge cables (316L stainless steel or titanium). Pass cables through drill holes in GT or around GT and femur. Tension sequentially from proximal to distal using calibrated tensioner to 300-500N. Crimp cables securely. Assess fixation - should be rigid, no motion on palpation. Fluoroscopy confirms anatomic reduction, no step-off. Some surgeons add 4.5mm cortical screw with washer through GT for supplemental fixation (I do not routinely - cable fixation adequate if done properly). (10) POST-OP PROTOCOL: TDWB or PWB (20-30kg) for 6-12 weeks until ETO healed. X-rays at 6 weeks assess callus formation. Typical healing 8-12 weeks. Advance to WBAT when callus present and pain-free. Non-union rate 5-10%, most asymptomatic. If symptomatic non-union: revision fixation with new cables and bone graft.

VIVA SCENARIOStandard

EXAMINER

"You have classified a femoral defect as Paprosky Type IIIB with only 3cm of intact diaphyseal bone distally. Discuss your options for femoral reconstruction, the principles of fixation for each option, and which you would choose and why."

EXCEPTIONAL ANSWER

Paprosky Type IIIB is severe metaphyseal AND proximal diaphyseal bone loss with <4cm intact diaphysis. This is very challenging - limited distal fixation zone. Three main options: (1) EXTRA-LONG EXTENSIVELY COATED STEM (280-300mm): Principles: Bypass all proximal bone loss and achieve distal diaphyseal fixation in the limited 3cm of healthy cortex. Need minimum 2cm scratch fit (3cm available is marginal but possible). Stem length 280-300mm to reach healthy distal bone. Extensively porous coated (6-8 inches distally) for osseointegration. Cylindrical design to match diaphyseal canal. Sizing: match final reamer or 0.5mm larger for press fit. Technique: Ream carefully to distal cortical contact (chatter) in the 3cm zone. Insert long stem with mallet, confirm distal engagement. May need cortical strut grafts for proximal augmentation and stress shielding reduction. Outcomes: 70-80% 10-year survival if adequate fixation achieved. Risk: subsidence if inadequate distal fixation (only 3cm contact is marginal). (2) LONG MODULAR TAPERED STEM: Principles: Distal tapered segment achieves compression fit in diaphysis via taper and longitudinal flutes. Proximal modular body allows offset/version adjustment. Advantage over extensively coated: compressive taper fixation may be more stable with limited contact zone. Can optimize proximal offset and version intraoperatively. Technique: Insert distal tapered stem to depth in the 3cm diaphyseal zone. Taper self-locks with progressive compression. Assess stability. Assemble proximal body with appropriate offset. Outcomes: Similar 70-80% 10-year survival. Advantage: intraoperative modularity. Disadvantage: modular junction corrosion/fretting (rare). (3) PROXIMAL FEMORAL REPLACEMENT (Megaprosthesis): Principles: If truly inadequate fixation possible with stems (3cm is very marginal), PFR is salvage option. Resect at level of healthy bone distally (where 3cm zone is). Long distal stem (150-200mm) in healthy mid/distal femur. Modular proximal body with articulating head. Abductor reattachment to collar. Advantages: Immediate stability (not dependent on osseointegration), immediate weight bearing. Disadvantages: Higher complications (dislocation 10-20%, infection 5-10%, loosening, fracture), 70-75% 10-year survival, loss of proximal femur permanently (no future stem revision possible), expensive. MY CHOICE and RATIONALE: With 3cm intact diaphysis, I would attempt LONG MODULAR TAPERED STEM first (option 2). Rationale: (1) 3cm is marginal but above the minimum 2cm threshold - tapered compression fit may achieve stability in this limited zone better than cylindrical extensively coated stem. (2) Modular components allow me to optimize offset, version, and leg length intraoperatively for best stability and function. (3) Preserves proximal femur biologically - can incorporate and remodel. (4) Avoids high complication rate of PFR if stem fixation achievable. (5) If stem loose on table (cannot achieve stable fixation), I can convert to PFR same surgery. TECHNIQUE: Ream carefully to the 3cm distal zone to cortical contact. Trial tapered stem - assess stability on table. If stable and good compression fit: proceed. If unstable or inadequate fixation: convert to PFR. Use CORTICAL STRUT GRAFTS liberally to augment proximal femur and reduce stress shielding. Protected weight bearing (TDWB/PWB) for 6-12 weeks to allow osseointegration before full loading. Close follow-up: X-rays 6 weeks, 3 months (look for early subsidence), 6 months, annually. If early subsidence >5mm: re-revision to PFR. Counsel patient pre-operatively on risks: this is very challenging reconstruction, higher failure risk than Type I/II, may need PFR if stem cannot achieve fixation, close monitoring required. 70-80% 10-year survival expected, but with 3cm contact on lower end of that range.