High Yield Overview

TOTAL HIP ARTHROPLASTY - REVISION WITH EXTENDED TROCHANTERIC OSTEOTOMY

Posterior (Moore/Southern) approach with Extended Trochanteric Osteotomy extension distally along femoral shaft | advanced

Critical Danger Structures

Danger 1: Sciatic Nerve

Location: 2-3cm posterior to posterior acetabulum, travels distally posterior to femur in posterior compartment

Protection: Early identification during posterior approach, gentle retraction with blunt retractor, avoid posterior osteotomy extension beyond linea aspera, release short external rotators sharply off bone rather than avulsion (nerve just posterior), ensure ETO cuts don't propagate posteriorly

Injury: Foot drop (common peroneal), sensory loss posterior leg and lateral foot, rare complete palsy. Incidence 0.5-2% with ETO (higher than primary 0.1-0.3%). Manage with immediate tension release, EMG at 3 weeks, AFO for foot drop, most partial recovery 12-18 months

Danger 2: Lateral Circumflex Femoral Artery Perforators

Location: Main pedicle 8-10cm distal to greater trochanter, pierce deep surface of vastus lateralis emerging through posterior 1/3 of muscle from deep to superficial. Multiple perforators along length

Protection: Preserve posterior 1/3 vastus lateralis attachment to ETO fragment - elevate only anterior 2/3 vastus off lateral femur. This maintains vascular pedicle essential for ETO union. Do NOT completely strip vastus from fragment

Injury: ETO fragment devascularization leading to non-union (increases from 5-10% to 20-30%), delayed union, fragment necrosis. Requires revision ORIF with plate, bone graft, BMP if symptomatic non-union develops

Danger 3: Femoral Vessels (Superficial and Deep)

Location: Anterior to femur along medial aspect in Hunter's canal. Femoral artery 2-3cm medial to anterior femoral cortex at mid-shaft level

Protection: Limit osteotomy to lateral 1/3 circumference, place finger anteriorly during cement removal to monitor cortex integrity, avoid anterior cortex perforation during burring/reaming, ensure saw cuts perpendicular not angled anteriorly

Injury: Catastrophic hemorrhage requiring immediate vascular surgery, potential limb loss. Anterior perforation occurs 30% of cases with blind cement removal (ETO reduces to <5%). Manage with immediate vascular surgery consult, repair vs ligation depending on vessel

Danger 4: Perforating Branches of Profunda Femoris

Location: Penetrate posterior femur at linea aspera, multiple branches along length of femur posteriorly

Protection: Keep posterior osteotomy cut anterior to linea aspera (anatomic landmark - palpable posterior ridge), limit osteotomy width to 1/3 circumference anterolaterally, avoid posterior extension

Injury: Venous bleeding from accompanying veins, can be brisk but usually controllable. Manage with direct pressure, bipolar cautery, bone wax if bone bleeding. Rarely requires ligation

Danger 5: Superior Gluteal Neurovascular Bundle

Location: Exits pelvis through greater sciatic notch superior to piriformis, travels between gluteus medius and minimus to supply these muscles. 3-5cm superior to acetabular dome

Protection: Limit proximal dissection, avoid excessive superior retraction of abductors, identify and protect during proximal ETO cut at GT level, ensure proximal cable placement below lesser trochanter (not at GT level where nerve courses)

Injury: Abductor denervation causing Trendelenburg gait, weakness, superior gluteal artery bleeding. Incidence <1% with ETO. Manage bleeding with direct pressure/cautery. Nerve injury irreversible - requires long-term gait aids

Mnemonic

CUBE 3-3-3ETO GEOMETRY - 'CUBE 3-3-3' Rule

Mnemonic

VAST PEDICLEETO BLOOD SUPPLY - 'VAST PEDICLE' Concept

Indications for Extended Trochanteric Osteotomy

Primary Indications (Strong Evidence)

1. Well-Fixed Cemented Femoral Stem Requiring Removal

MOST COMMON indication (60% of ETO cases)
Stem well-bonded to cement mantle, cannot be extracted safely
Long cement mantle extending into diaphysis
Removal required for: aseptic loosening of acetabulum with well-fixed femoral component, infection requiring complete removal, stem malposition, periprosthetic fracture around stem
Alternative (cortical windows) has 30% anterior perforation rate with blind cement removal
ETO provides DIRECT visualization of cement-bone interface for safe removal

2. Well-Fixed Uncemented Stem Requiring Removal

Extensively porous coated stem with circumferential bone ingrowth
Cannot be extracted with standard techniques (osteotomes, slap hammer)
Risk of fracture during extraction attempts
Common scenarios: modular stem with taper corrosion, head/neck taper fracture, stem malposition, acetabular revision with need for stem version correction
Hydroxyapatite coated stems particularly difficult to extract (strong bone bonding)

3. Periprosthetic Femoral Fracture Around Stem (Vancouver Classification)

Vancouver B1: Fracture around well-fixed stem with adequate bone stock
- Need to access fracture site for reduction and fixation
- ETO allows fracture visualization, reduction, cable/plate fixation, maintain stem
Vancouver B2: Fracture around loose stem
- Need stem removal and revision
- ETO allows safe stem extraction and fracture management
- Can revise to longer stem bypassing fracture
Vancouver C fractures: may use ETO if fracture pattern extends proximally

4. Proximal Femoral Deformity Limiting Canal Access

Previous fracture malunion with canal deformity
Paget's disease with bowing and sclerosis
Previous osteotomy (valgus, varus, derotational)
Developmental dysplasia with abnormal anatomy
Severe osteoarthritis with protrusio and medial bone loss
ETO allows visualization of anatomy and controlled reaming despite deformity

5. Severe Proximal Femoral Osteolysis

Extensive cysts and bone loss requiring thorough debridement
Polyethylene wear debris-induced osteolysis
Need access for curettage, grafting
ETO provides complete visualization of proximal femur for debridement and grafting

Secondary/Relative Indications

6. Retained Cement Restrictor or Distal Plug

Cement restrictor at isthmus level
Cannot advance instruments past restrictor
Risk of perforation attempting blind removal
ETO allows direct visualization and removal

7. Broken Cerclage Wires/Cables from Previous Surgery

Retained metalwork embedded in bone
Cannot advance reamers safely
Need removal before revision stem insertion

8. Severe Anterior Femoral Bow

Risk of anterior perforation during reaming
ETO allows visualization and controlled reaming following anatomy

9. Removal of Long Distally-Fixed Stem

Extensively coated stem with distal fixation only (proximal loosening)
Cannot extract without risk of fracture
ETO allows proximal access while maintaining distal fixation initially

Contraindications to ETO

Absolute Contraindications

Active uncontrolled infection with significant soft tissue loss (risk of fragment contamination)
Severe osteoporosis with impending fracture (fragment will not hold cables)
Prior ETO at same site with non-union (revision requires different technique - plate fixation)
Trochanteric area destroyed by tumor or infection (no fragment to mobilize)

Relative Contraindications

Mild osteoporosis (manage with more cables, possibly plate augmentation)
Patient non-compliance anticipated (unable to follow protected WB protocol)
Smoking (3× non-union risk - counsel cessation, consider plate augmentation)
Previous radiation therapy to femur (impaired healing - consider plate, BMP)
Morbid obesity (difficulty with protected WB, higher complication rate)

ETO vs Alternative Techniques

Technique	Advantages	Disadvantages	Indications
Extended Trochanteric Osteotomy	Direct visualization, complete cement removal, controlled osteotomy, 90% union	Complex, longer surgery, protected WB 6-8w, risk non-union 5-10%	Well-fixed cemented stem, extensive cement mantle, complex anatomy
Cortical Windows	Faster, simpler, full WB immediately	Blind cement removal (30% perforation), incomplete removal, risk fracture propagation	Short cement mantle, proximal cement only, good bone stock
Femoral Osteotomy (Complete)	Complete exposure	Non-union 20-30%, requires plate fixation, long protected WB	Severe deformity, tumor resection
In Situ Stem Retention	No osteotomy needed	Cannot address cement, limited options	Well-fixed stem, isolated acetabular revision

Preoperative Planning - Essential Steps

Clinical Assessment

History

Original indication for THA (primary OA, DDH, AVN, trauma, inflammatory arthritis)
Previous surgeries and approaches (posterior, anterior, lateral - determines scar, soft tissue)
Time since index THA (early vs late failure, bone stock implications)
Symptoms: pain location and character, instability/dislocations, functional limitation
Medical comorbidities: diabetes (infection risk), smoking (non-union risk 3×), cardiac (DVT prophylaxis), renal (medication dosing)
Medications: anticoagulation (timing of cessation), steroids (healing impairment)
Patient expectations and compliance (ability to follow protected WB protocol CRITICAL)

Physical Examination

Gait: Trendelenburg (abductor deficiency), antalgic (pain), leg length discrepancy
Scars: location, quality, previous approach identification
Hip ROM: flexion, extension, rotation (stiffness suggests heterotopic ossification)
Abductor strength: hip abduction against resistance (gluteus medius/minimus function)
Neurovascular: sciatic nerve function (foot dorsiflexion, plantar flexion, sensation), femoral pulse, distal pulses
Leg lengths: measure true (ASIS to medial malleolus) and apparent lengths

Radiographic Assessment - FULL-LENGTH FILMS MANDATORY

Standard AP Pelvis (True AP)

Assess acetabular component: position, wear, loosening (radiolucent lines, migration)
Femoral stem position: varus/valgus, subsidence, loosening zones (Gruen zones)
Heterotopic ossification: Brooker classification (may need excision if severe)
Bone stock: proximal femur quality, greater trochanter integrity
Previous fractures, deformities

Full-Length AP Femur (Hip to Knee on Single Cassette)

CRITICAL for ETO planning
Measure stem length precisely (from shoulder to tip)
Calculate ETO length: stem length + 4-5cm distal extension
Identify stem tip location (mark on radiograph)
Assess distal bone stock: canal diameter, cortical thickness (Paprosky classification)
Anterior bow of femur: may need lateral view to assess
Previous hardware: cables, plates, screws

Lateral Hip/Femur

Assess stem version (anteversion/retroversion)
Anterior bow magnitude (affects reaming trajectory)
Cement mantle anterior and posterior extent
Anterior cortex integrity (weakened areas risk perforation)

Additional Imaging (Selective)

CT Scan with 3D Reconstruction

Complex anatomy: DDH, previous fracture, deformity
Assess bone stock in 3D: Paprosky classification verification
Cement mantle extent and distribution
Surgical approach planning (anatomy visualization)
Not routine but helpful in complex cases

MRI

Suspected infection: fluid collections, abscesses
Soft tissue assessment: abductor integrity, trochanteric bursa
Osteolysis extent: better than X-ray for cystic lesions
Contraindicated with some metal implants

Bone Scan (Tc-99m)

Differentiate aseptic loosening (uptake at bone-implant interface) from infection
Usually superseded by aspiration

Labeled WBC Scan (Indium-111 or Tc-99m HMPAO)

Infection diagnosis when aspiration equivocal
High specificity for infection

Laboratory Assessment

Infection Workup - MANDATORY in All Revisions

ESR (Erythrocyte Sedimentation Rate): elevated >30mm/hr suggests infection (sensitivity 80%, specificity 60%)
CRP (C-Reactive Protein): elevated >10mg/L suggests infection (sensitivity 90%, specificity 70%)
Both elevated: 95% sensitivity for infection combined
Hip Aspiration if ANY concern: WBC count >3000 cells/μL or PMN >80% diagnostic of infection
Culture and sensitivities: guide antibiotic selection if infection confirmed
Alpha-defensin, synovial fluid CRP: newer markers with high accuracy

General Medical Clearance

CBC: anemia (transfusion planning), WBC (infection, bone marrow function)
BMP: renal function (medication dosing, IV contrast if CT planned)
Coagulation studies: PT/INR if anticoagulated, PTT baseline
Urinalysis: UTI source control before surgery
Chest X-ray: cardiac size, pulmonary disease assessment
ECG: cardiac risk stratification
Cardiology clearance if indicated (Goldman criteria)

Templating - Systematic Digital Planning

Acetabular Templating (if revising acetabulum)

Determine component size and position
Bone grafting needs (superior, medial, posterior defects)
Augments, jumbo cups, trabecular metal
Not focus of ETO but plan comprehensively

Femoral Templating for ETO

Step 1: Measure Existing Stem

Length from shoulder to tip (typically 120-180mm)
Proximal diameter (metaphyseal fill)
Distal diameter and extent of porous coating or cement

Step 2: Calculate ETO Length

Formula: ETO length = Stem tip location + 4-5cm distal extension
Example: 140mm stem, ETO must extend to 180-190mm from lesser trochanter
Typical ETO total length: 8-12cm depending on stem
Mark this on radiograph with pen

Step 3: Assess Distal Bone Stock (Paprosky Femoral Classification)

Type I: Minimal metaphyseal and diaphyseal bone loss, intact diaphysis
- Standard revision stem suitable
Type II: Moderate metaphyseal bone loss, intact diaphysis
- Extensively coated or calcar-loading stem
Type IIIA: Severe metaphyseal loss, good diaphysis (>4cm fixation available)
- Extensively porous coated cylindrical stem (Wagner, Solution, Restoration)
- Need 4cm scratch fit for 90% success rate
Type IIIB: Poor diaphysis (<4cm fixation available), extensive bone loss
- Modular tapered fluted stem (Reclaim, Arcos, MP)
- May need megaprosthesis or allograft-prosthetic composite (APC)
Type IV: Extensive metaphyseal and diaphyseal damage, widened canal
- APC, megaprosthesis, custom implant

Step 4: Select Revision Stem Type

Extensively Porous Coated Cylindrical (Wagner, Solution, Restoration)
- For Paprosky IIIA with good distal canal
- Requires 4cm minimum scratch fit (distal fixation)
- Cylindrical shape, distal taper, full circumferential coating
- Stems available 180-300mm length
- Diameter 13-20mm typically
Modular Tapered Fluted (Reclaim, Arcos, Restoration Modular, MP)
- For Paprosky IIIB or complex anatomy
- Allows version adjustment (separate metaphyseal and diaphyseal components)
- Tapered geometry wedges in canal (metaphyseal and diaphyseal fixation)
- Flutes provide rotational stability
- Bypass ETO by 10cm (2 cortical diameters)
- Lengths 180-400mm available (proximal body + distal stem lengths added)

Step 5: Template New Stem

Overlay template on full-length femur radiograph (magnification calibrated)
Stem should:
- Bypass ETO distal extent by 10cm minimum (2 cortical diameters)
- Achieve 4cm scratch fit distally (for extensively coated) OR wedge in canal (for tapered)
- Restore offset and leg length
- Provide version control (template in slight anteversion 10-15°)
Mark stem tip location on radiograph
Confirm distal fixation zone adequate (cortical thickness >5mm ideal, canal diameter appropriate)

Step 6: Plan Bone Grafting Needs

Proximal femoral defects (cavitary from osteolysis): morselized cancellous allograft, impaction grafting
Cortical defects: structural cortical strut allografts around femur (reinforcement)
ETO site itself: typically heals without graft if anatomic reduction and cable compression achieved

Step 7: Implant and Instrument Checklist

Revision femoral stems: multiple sizes of chosen system, one size up and down
Cerclage cables: minimum 5-7 cables (18-gauge stainless steel or titanium), cable passer instruments, cable tensioner system, crimping tools
Cable plate (optional): Dall-Miles plate or equivalent if high-risk case (osteoporosis, infection, previous ETO)
Cement removal equipment:
- Ultrasonic cement removal system (OSCAR) with sterile probes OR
- High-speed burr with long thin carbide bits (7-10 inch length), irrigation system
- Curved osteotomes for cement fragmentation
Specialized extraction instruments:
- Explant system or equivalent (stem extractors)
- Moreland slap hammer with adapters for modular neck tapers
- Gigli saw (for stem sectioning if needed)
Reaming equipment: Flexible reamers 8-20mm, straight reamers, conical reamers (depending on stem system)
Bone graft (if needed): Morselized cancellous allograft, cortical strut allografts, bone graft extenders (if using impaction grafting)
Osteotomy equipment: Oscillating saw with thin blade, curved osteotomes (various sizes), bone clamps (reduction and holding)
Trials: Complete trial set for chosen stem system, trial heads (various sizes and offsets)
Acetabular components: If revising acetabulum, complete revision cup system, liners, augments, screws, etc.

Patient Preparation and Consent

Informed Consent - Specific to ETO

Procedure explanation: ETO technique, why needed (direct visualization for safe cement removal)
Extended surgery time: 3-4 hours typical (longer than standard revision)
Blood loss: 800-1200mL average (may need transfusion - type and cross 4 units)
Complications specific to ETO:
- Non-union 5-10% (may need revision surgery with plate and bone graft)
- Trochanteric escape 2-5% (fragment migration, abductor weakness)
- Intraoperative fracture 5-10% (may need extended fixation)
- Sciatic nerve injury 0.5-2% (foot drop, sensory loss, usually partial recovery)
- Infection 2-5% (may need two-stage revision)
- Dislocation 5-10% (higher than primary)
- Subsidence 5-10% (stem settling in first 6 months)
- Chronic pain 10-15% (multifactorial)
Protected weight-bearing protocol 6-8 weeks (CRITICAL - patient must understand and commit)
- Toe-touch or 20kg partial weight-bearing with walker
- Hip precautions (avoid flexion >90°, adduction, internal rotation)
- X-rays at 2w, 6w, 12w to assess union
- Cannot return to full activities until union confirmed
Alternative options discussed: cortical windows (higher perforation risk), in situ stem retention (if acetabulum only issue)
Risks vs benefits: ETO allows safe cement removal but requires compliance with protected WB

Preoperative Optimization

Smoking cessation: at least 4 weeks preop (reduces non-union risk from 15-30% back toward 5-10%)
Nutritional optimization: albumin >3.5g/dL, protein supplementation if deficient
Diabetes control: HbA1c <7% ideal (reduces infection risk)
Anemia correction: Hgb >12g/dL ideal, iron supplementation or ESA if needed
Weight optimization: BMI <40 (obesity increases complications)
Skin optimization: no rashes, infections, breakdown at surgical site
Dental clearance: no active dental infections (bacteremia risk)
Medical optimization: cardiac, pulmonary, renal clearance as needed

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"Describe the blood supply to the ETO fragment and how you preserve it during the procedure. What happens if you violate this blood supply?"

EXCEPTIONAL ANSWER

The blood supply to the ETO fragment comes primarily from perforating branches of the lateral circumflex femoral artery and secondarily from the superior gluteal artery. The lateral circumflex femoral artery sends multiple perforating branches that pierce through the deep surface of the vastus lateralis muscle along the posterior one-third of the muscle, with the main pedicle located 8-10 centimeters distal to the greater trochanter tip. These perforators emerge from deep to superficial through the muscle substance and provide blood supply to the lateral femoral cortex. The superior gluteal artery provides branches to the gluteus medius and minimus muscles which remain attached to the greater trochanter portion of the ETO fragment, serving as a secondary blood supply source. To preserve this critical blood supply, I elevate only the anterior two-thirds of the vastus lateralis muscle off the lateral femur during exposure, leaving the posterior one-third attached to the bone and periosteum. This posterior third contains the perforating vessels and acts as the vascular pedicle. Additionally, I maintain the posterior soft tissue hinge during the osteotomy by making the posterior cut only partial thickness, not full thickness like the anterior cut. The periosteum posteriorly also contributes to blood supply. Complete vastus lateralis stripping or detachment of the posterior soft tissue hinge devascularizes the fragment, increasing non-union rate from the normal 5-10% to 20-30%. A devascularized fragment may develop delayed union or non-union requiring revision surgery with plate fixation, bone grafting, and potentially BMP augmentation. The fragment may also undergo avascular necrosis in severe cases. This vascular preservation technique is absolutely essential for achieving the greater than 90% union rate reported in the literature.

VIVA SCENARIOStandard

EXAMINER

"A 68-year-old smoker presents 8 weeks after ETO with persistent lateral thigh pain and a positive Trendelenburg test. X-rays show no bridging callus at the osteotomy site and a 2mm lucency is visible. How would you manage this patient?"

EXCEPTIONAL ANSWER

This clinical scenario suggests ETO non-union at 8 weeks in a high-risk patient due to smoking. First, I would complete a thorough assessment to confirm the diagnosis and identify contributing factors. Clinically, I would examine for tenderness directly over the ETO site, assess hip abductor strength which is likely reduced causing the positive Trendelenburg, and evaluate overall function with a Harris Hip Score or WOMAC. The X-ray findings of no callus and persistent lucency at 8 weeks are concerning for non-union, though union can occasionally take up to 12 weeks. I would order a CT scan with 3D reconstruction which provides definitive assessment of bone healing - it will show whether there are any bridging trabeculae that X-ray missed, or confirm complete non-union with a gap at the osteotomy interface. I would check inflammatory markers ESR and CRP to rule out infection as a cause of delayed union, and if elevated, perform a hip aspiration for culture and cell count. Review of the patient's compliance with protected weight-bearing is essential - non-compliance leads to non-union. Most importantly, I would counsel strongly about smoking cessation as smoking increases non-union risk threefold. For management, if this is truly non-union (confirmed on CT) with symptoms of pain and weakness, and the patient is 8 weeks out which is early, I would initially try conservative management: strict smoking cessation, continue protected weight-bearing for an additional 4-6 weeks, optimize nutrition with high protein diet and calcium/vitamin D supplementation, and repeat imaging at 12 weeks. Some delayed unions will go on to heal with extended protected weight-bearing. However, if the CT shows complete non-union with a significant gap, or if conservative management fails by 12-16 weeks with persistent symptoms, surgical intervention is warranted. Surgical management would involve revision ORIF of the ETO: I would use a lateral compression plate (8-10 hole plate long enough to span the osteotomy with at least 3 bicortical screws proximal and 3 distal), remove the existing cables and replace with new cables augmenting the plate, add bone graft (either autograft from iliac crest or cancellous allograft chips) at the non-union site for biologic stimulus, and consider BMP-7 (OP-1) which is off-label but has some evidence for difficult non-unions. Postoperatively, protected weight-bearing would continue for an additional 8-12 weeks until union confirmed on X-ray and CT. Success rate of revision surgery for ETO non-union is 80-90% with plate fixation and bone graft. Throughout management, I would also address the underlying femoral stem - ensure it remains well-fixed without subsidence, as a loose stem would require revision not just ETO repair.

VIVA SCENARIOStandard

EXAMINER

"You are planning an ETO for a well-fixed cemented femoral stem that is 150mm long. Walk me through your preoperative planning for the ETO geometry and stem selection. What specific measurements do you need and what stem would you choose for a Paprosky Type IIIA femoral defect?"

EXCEPTIONAL ANSWER

Preoperative planning for ETO requires systematic assessment of multiple factors to ensure safe execution and optimal outcomes. First, I would obtain full-length AP and lateral radiographs of the femur from hip to knee on a single cassette, which is absolutely essential for ETO planning. On these films, I would measure the existing stem length precisely from the shoulder to the tip, which you've stated is 150mm. I would identify the stem tip location and mark it on the radiograph. For ETO geometry, the critical principle is that the osteotomy must extend 4-5cm beyond the stem tip to prevent fracture propagation during stem extraction. Therefore, with a 150mm stem, the ETO distal extent must reach approximately 195-200mm from the lesser trochanter reference point (150mm plus 4-5cm equals 190-200mm). This typically results in a total ETO length of 10-12cm from the greater trochanter tip distally. The ETO width must be one-third of the femoral circumference, approximately 3-4cm, creating a rectangular window on the anterolateral femur. I would mark three cuts on the radiograph: anterior vertical cut starting at the anterolateral corner of the greater trochanter extending 10-12cm distally, distal horizontal cut connecting anterior to posterior at the 195-200mm level, and posterior vertical-oblique cut creating a hinge posteriorly (this cut is partial thickness, not full thickness like the anterior cut). The posterior cut must stay anterior to the linea aspera to avoid perforating vessels. Next, I would assess the bone stock using the Paprosky femoral classification. For a Type IIIA defect, there is severe metaphyseal bone loss but the diaphysis is intact with greater than 4cm of good bone available for distal fixation. I would measure the canal diameter in the diaphysis where fixation will be achieved, typically 4-7cm distal to the lesser trochanter. For a Paprosky Type IIIA defect, my stem of choice would be an extensively porous coated cylindrical stem such as a Wagner SL Revision Stem, Zimmer Solution, or Stryker Restoration. These stems rely on distal diaphyseal fixation with a scratch fit technique. The stem must be long enough to bypass the ETO by 2 cortical diameters, which is approximately 10cm. With the ETO extending to 195-200mm from the lesser trochanter, the stem must extend at least to 295-300mm (200mm plus 10cm bypass), so I would select a stem in the 200-220mm length range typically. The diameter would be chosen to be 0.5-1mm undersized relative to the reamed canal diameter to achieve press-fit - typically 13-16mm diameter stems are used. I would template the stem on the full-length radiograph with calibrated magnification to confirm that: one, it bypasses the ETO by 10cm minimum; two, achieves 4cm minimum scratch fit in the diaphysis (essential for 90% success rate); three, restores offset and leg length; and four, provides appropriate version. I would also plan for cerclage cables - I need minimum 3 but would prepare 5-7 cables available: one proximal to the osteotomy around intact femur below lesser trochanter, 2-3 cables across the osteotomy spaced 2-3cm apart, one distal to the osteotomy, and extras in case of cable breakage or need for fracture fixation. Finally, I would ensure cement removal equipment is available: either an ultrasonic cement removal system like OSCAR which is preferred, or high-speed burr with long thin carbide bits 7-10 inches in length, plus curved osteotomes for cement fragmentation. This systematic preoperative planning is critical for ETO success - inadequate planning leads to intraoperative complications such as fracture propagation if the ETO is too short, or subsidence if the stem selection is inappropriate for the bone stock.