High-yield overview

Posterior or posterolateral (extended trochanteric osteotomy often needed) | advanced

Critical Danger Structures

Sciatic Nerve

Location: Exits pelvis through greater sciatic foramen, passes posterior to hip joint 15-30mm from posterior capsule. Stretched with hip extension, adduction, internal rotation (combined increases tension). Most at risk during ETO hinging and posterior retractor placement. Protection: Maintain hip flexed and externally rotated. Avoid aggressive posterior retraction. Palpate nerve before placing retractors. Monitor for post-op foot drop. If lengthening required, shortening osteotomy rather than stretching nerve.

Femoral Nerve & Vessels

Location: Femoral artery 25-40mm medial to anterior hip capsule at psoas tendon level. Femoral nerve lateral to artery. Profunda femoris branches at risk during anterior/lateral capsule release. Protection: Anterior retractor must rest ON BONE (anterior acetabular wall). Never lever anteriorly. Identify and protect if using anterior approach. If arterial injury - immediate pressure, call vascular surgery, have clamps available.

Superior Gluteal Nerve & Artery

Location: Exits pelvis above piriformis, travels between gluteus medius and minimus. Safe zone is approximately 5cm proximal to greater trochanter tip - do NOT dissect proximally. Supplies abductors - injury causes Trendelenburg gait. Protection: Stay within 5cm of trochanter tip. Do not extend ETO too proximally. Avoid blunt dissection in gluteus medius-minimus interval. If abductor weakness post-op, assess for nerve injury.

Femoral Cortex (ETO Site)

Location: Lateral femoral cortex where ETO is performed. At risk for iatrogenic fracture if osteotome misaligned, if cortex weakened by osteolysis, or if ETO not properly controlled. Propagation distally can compromise stem fixation zone. Protection: Mark ETO precisely (anterior 1/3 circumference). Use oscillating saw with bone protection. Control osteotome direction. Assess for lytic lesions on preop CT. Complete the osteotomy in controlled fashion before hinging.

Femoral Perfusion (Medial Circumflex)

Location: Medial femoral circumflex artery provides primary blood supply to femoral head remnant - less critical in revision but important in periprosthetic fracture. Deep branch courses posterior to quadratus femoris. Protection: If significant bone loss proximally, consider vascularity of remaining proximal femur. Avoid circumferential stripping. If avascular necrosis develops, may need proximal femoral replacement.

Mnemonic

PAPROSKYPAPROSKY - Femoral Bone Loss Classification

Mnemonic

ETOETO - Extended Trochanteric Osteotomy Steps

Positioning and Preparation

Patient Position: Lateral decubitus with pelvic posts

Surgical Approach: Posterior or posterolateral (extended trochanteric osteotomy often needed)

Essential Equipment: Fluoroscopy, revision stem set (extensively porous options), ETO instrumentation (oscillating saw, osteotomes), cable/wire fixation system, high-speed burr, cement removal tools, flexible reamers, backup stems (modular, cemented, proximal femoral replacement)

Paprosky Femoral Bone Loss Classification

The Paprosky femoral classification has FIVE types (I, II, IIIA, IIIB, IV), defined by the extent of metaphyseal and diaphyseal bone loss and - critically - by how much supportive diaphyseal isthmus remains for fixation. Beware fabricated "IIA/IIB/IIC" subtypes - the femoral system does NOT use these (the lettered subtype only exists within Type III).

Type	Metaphysis	Diaphysis / Isthmus	Recommended Reconstruction
I	Minimal cancellous loss, intact	Fully intact, supportive	Primary-style or short cementless stem; cemented also feasible
II	Extensive metaphyseal loss, non-supportive	Minimal diaphyseal loss, intact supportive isthmus	Extensively porous cylindrical stem (or cemented), metaphyseal not relied upon
IIIA	Extensive metadiaphyseal loss	MORE than 4cm of intact supportive isthmus	Cylindrical extensively porous stem; modular tapered fluted stem also reliable (ETO often required)
IIIB	Extensive metadiaphyseal loss	LESS than 4cm of supportive isthmus	Modular tapered fluted titanium stem preferred; impaction grafting an alternative
IV	Extensive metadiaphyseal loss	Non-supportive, widened/ectatic isthmus (thin cortices)	Cylindrical stems fail - impaction grafting, allograft-prosthetic composite, or proximal femoral replacement

Key Decision Points:

Type I-II: intact supportive isthmus - cementless diaphyseal fixation reliable
Type IIIA: cylindrical extensively porous stem bypassing the defect to engage at least 4-5cm of isthmus (MOST COMMON EXAM SCENARIO for this stem); contemporary practice increasingly favours modular tapered fluted stems for the same defect
Type IIIB: with under 4cm of isthmus, cylindrical stems are less predictable - a modular tapered fluted stem achieves rotational stability over a shorter segment of host bone
Type IV: no supportive host diaphysis - reconstruct bone stock (graft/APC) or replace the proximal femur

Operative Technique

Step 1: POSITIONING AND APPROACH

LATERAL DECUBITUS POSITIONING: Standard lateral position with pelvic posts. Wide draping to allow extensibility if needed. Ensure fluoroscopy can access entire femur. Mark landmarks: greater trochanter, shaft axis, previous incision. Use PREVIOUS INCISION if possible - posterior or posterolateral approach most common. Develop interval through scar tissue. Identify and protect sciatic nerve before proceeding deeper.

Clinical Pearl

Technical Tip: EXAM KEY: Lateral position allows access to entire femur for ETO and stem insertion. Wide drape because you may need to extend distally for fracture or cement removal. Previous incision reduces wound complications vs new incision through scar.

Dangers at this step

Sciatic nerve injury if not identified in scar tissue
Wound complications from crossing previous incision

Step 2: EXPOSURE AND ASSESSMENT

DEEP EXPOSURE: Identify posterior capsule (often absent from prior surgery), short external rotators (may be deficient). Assess abductor mechanism - critical for function. Dislocate hip (may be already dislocated or very easy if unstable). Remove femoral head if present. ASSESS STEM: Is it loose or well-fixed? Gross loosening allows extraction without ETO. Well-fixed stems REQUIRE ETO for controlled removal.

Clinical Pearl

Technical Tip: EXAM KEY: If stem is LOOSE, extract directly and skip ETO. If stem is WELL-FIXED (cementless with good ingrowth or cemented with good mantle), ETO is REQUIRED for controlled extraction without fracture. Decision made BEFORE osteotomy.

Dangers at this step

Iatrogenic fracture attempting to extract well-fixed stem without ETO
Abductor damage if not carefully preserved

Step 3: EXTENDED TROCHANTERIC OSTEOTOMY (ETO) - MARKING

ETO INDICATIONS: Well-fixed stem, distal cement removal, or improved access required. MARKING: Length approximately one-third of the femur (commonly 12-14cm from greater trochanter tip), ending 2cm or more proximal to the segment where the new stem must engage host bone. Width: roughly one-third of the femoral circumference (lateral/anterolateral fragment). Mark with diathermy/sterile marker. PRESERVE the abductor-vastus lateralis sleeve on the fragment - this is CRITICAL for union and abductor function.

Clinical Pearl

Technical Tip: EXAM KEY: ETO length is about one-third of the femur and must end proximal to the host-bone segment the new stem will engage. The lateral/anterolateral fragment carries abductors and vastus lateralis as a single muscle-bone sleeve. NEVER strip that sleeve - doing so risks Trendelenburg gait and nonunion. Round the distal corner to avoid a stress riser.

Dangers at this step

Too short ETO = cannot extract stem/cement; too long (into the stem-engagement zone) = no host bone for fixation
Stripping the abductor-vastus sleeve = devascularised fragment, nonunion and permanent abductor weakness

Step 4: ETO - OSTEOTOMY EXECUTION

LONGITUDINAL CUT: Oscillating or pencil-tip saw along the lateral cortex (roughly one-third of the circumference). DISTAL CORNER: Round the distal transverse corner - drill multiple holes and connect them - rather than a sharp transverse cut, to reduce the stress riser and prevent fracture propagation. Control depth to avoid cutting into the stem or cement. HINGING: Use wide osteotomes to lever the fragment FORWARD on its anterior muscle hinge; it opens like a book. Keep the abductor-vastus sleeve intact - do NOT detach or strip the fragment.

Clinical Pearl

Technical Tip: EXAM KEY: Rounding the distal corner (drill holes then connect) is the key step that prevents an uncontrolled spiral fracture. Control saw depth to avoid the stem/cement. The fragment hinges FORWARD, carrying the abductors and vastus lateralis as one perfused sleeve - this preserves union potential and abductor power.

Dangers at this step

Uncontrolled fracture propagation distally (sharp distal corner / no relief holes)
Devascularisation by stripping the muscle sleeve off the fragment
Cortical perforation into stem/cement

Step 5: STEM AND CEMENT REMOVAL

STEM EXTRACTION: With ETO open, direct access to stem-bone interface. Use specialized stem extraction tools. Apply distal blows to extract stem. For well-fixed cementless: may need to disrupt ingrowth interface. CEMENT REMOVAL: High-speed burr for cement mantle. Ultrasonic cement removal tools if available. Remove ALL cement - retained cement compromises new fixation. ASSESS CANAL: Curette canal, remove granulation tissue, assess bone quality.

Clinical Pearl

Technical Tip: EXAM KEY: Complete cement removal is ESSENTIAL - retained cement prevents bone ingrowth and proper fixation. Use flexible reamers to assess canal patency. Fluoroscopy confirms complete cement removal. High-speed burr = most effective for cement.

Dangers at this step

Cortical perforation with burr or reamers
Retained cement compromising fixation
Canal fracture with aggressive extraction

Step 6: CANAL PREPARATION - BROACHING

SEQUENTIAL BROACHING: Start with smallest extensively porous broach. Advance sequentially until SCRATCH FIT achieved. Broach should scratch against cortical bone when inserted/removed - this indicates appropriate interference fit in diaphysis. FLUOROSCOPY: Confirm broach position in isthmus, alignment, and length. Goal: 4-5cm of cortical contact in isthmus for stable fixation.

Clinical Pearl

Technical Tip: EXAM KEY: SCRATCH FIT = broach scratches cortical bone on insertion/removal. If no resistance, broach too small. If cannot advance, broach too large or eccentric. Must achieve 4-5cm of isthmus contact. Extensively porous stems rely on DIAPHYSEAL fixation, NOT metaphyseal.

Dangers at this step

Undersized broach = stem subsidence
Oversized broach = fracture
Eccentric broaching = cortical perforation

Step 7: TRIAL STEM ASSESSMENT

TRIAL INSERTION: Insert trial stem matching final broach size. Assess: (1) STABILITY - stem should not rotate or subside with torsional/axial load; (2) LENGTH - compare to contralateral, use measured markers; (3) OFFSET - assess soft tissue tension with trial heads; (4) POSITION - confirm alignment on fluoroscopy. If trial unstable, reassess - may need larger stem or different fixation strategy.

Clinical Pearl

Technical Tip: EXAM KEY: Trial MUST be stable before proceeding to final stem. If trial rotates with hip rotation = inadequate scratch fit, need larger stem. Leg length assessed with trial heads - use spacer blocks for comparison. Soft tissue tension guides offset selection.

Dangers at this step

Proceeding with unstable trial = stem subsidence
Over-lengthening = sciatic nerve palsy
Inadequate offset = instability

Step 8: FINAL STEM INSERTION

FINAL STEM: Insert final extensively porous stem. Same size or 0.5mm larger than trial. Advance with controlled mallet blows. Confirm scratch fit achieved. FLUOROSCOPY: Confirm position, alignment, length. Stem should bypass metaphyseal defect to engage diaphysis. HEAD SELECTION: Trial heads for offset and length optimization. Final head impaction.

Clinical Pearl

Technical Tip: EXAM KEY: Final stem should achieve same scratch fit as trial. If easier to insert than trial, may be undersized - have larger stem available. Modular necks available if standard offset options insufficient. Document final head selection and combined offset.

Dangers at this step

Stem subsidence if inadequate scratch fit
Fracture with excessive force
Malalignment if not checked with fluoroscopy

Step 9: ETO REPAIR

REDUCE ETO FRAGMENT: Anatomic reduction of the osteotomy fragment flush with the lateral cortex. CABLE FIXATION: Typically 2-3 cerclage cables (proximal, mid-fragment, and over host diaphysis distal to the osteotomy corner). Tension to manufacturer specification. Use a cable-grip plate if the fragment is osteopenic, comminuted or prone to migration. CONFIRM: Fragment stable, no motion with hip ROM, cables secure.

Clinical Pearl

Technical Tip: EXAM KEY: Place cables over host diaphysis distal to the rounded osteotomy corner to avoid a stress riser. Cables are generally preferred over monofilament wire in revision. Do NOT overtighten (notch/fracture, cut-through). Fragment must be stable before closure - ETO nonunion compromises the abductors. The largest series report about 98% union and roughly 2% nonunion.

Dangers at this step

Inadequate fixation = trochanteric nonunion
Overtightened cables = fragment fracture
Malreduction = abductor dysfunction

Step 10: STABILITY TESTING AND CLOSURE

FINAL ASSESSMENT: Full range of motion testing. Check stability in flexion/adduction/internal rotation (posterior dislocation position). Check anterior stability in extension/external rotation. LEG LENGTH: Final clinical and fluoroscopic assessment. CLOSURE: Posterior capsule repair if tissue available, short external rotators if present, layered closure. DRAIN if significant dead space.

Clinical Pearl

Technical Tip: EXAM KEY: Stability testing with various head/liner combinations if concerned. Dual-mobility liner option if high instability risk. Abduction brace or hip precautions based on soft tissue integrity and stability assessment.

Dangers at this step

Missed instability = early dislocation
Leg length discrepancy = patient dissatisfaction, nerve injury
Inadequate closure = infection risk

Complications

Complications: Recognition, Prevention, and Management

Key Evidence

Minimal 11-year follow-up of extensively porous-coated stems in femoral revision total hip arthroplasty

Level IV

Weeden SH, Paprosky WG • The Journal of Arthroplasty

Clinical Implication: Cylindrical extensively porous-coated stems give durable, mostly bone-ingrown fixation in femoral revision when an adequate supportive isthmus is present, but reliability falls as bone loss increases.

Verify on PubMed (PMID 12068424)

Revision total hip arthroplasty: the limits of fully coated stems

Level IV

Sporer SM, Paprosky WG • Clinical Orthopaedics and Related Research

Clinical Implication: Defines the LIMITS of cylindrical fully-coated stems: once the isthmus is non-supportive (canal over 19mm, Type IIIB-wide or Type IV), switch to a modular tapered stem, impaction grafting or proximal femoral replacement.

Verify on PubMed (PMID 14646718)

The femur in revision total hip arthroplasty: evaluation and classification

Level V

Della Valle CJ, Paprosky WG • Clinical Orthopaedics and Related Research

Clinical Implication: The Paprosky femoral classification is the standard framework for selecting implant and fixation type; accurate preoperative typing ensures the correct stems and instruments are available.

Verify on PubMed (PMID 15057079)

Extended Trochanteric Osteotomy in Revision Total Hip Arthroplasty: Contemporary Outcomes of 612 Hips

Level IV

Abdel MP, Wyles CC, Viste A, Perry KI, Trousdale RT, Berry DJ • The Journal of Bone and Joint Surgery (American)

Clinical Implication: In experienced hands the ETO is a safe, high-union (about 98%) tool for femoral exposure and implant removal; fragment fracture rather than nonunion is the dominant complication to anticipate.

Verify on PubMed (PMID 33252587)

Outcomes and Risk Factors of Extended Trochanteric Osteotomy in Aseptic Revision Total Hip Arthroplasty: A Systematic Review

Level III

Malahias MA, Gkiatas I, Selemon NA, De Filippis R, Gu A, Greenberg A, Sculco PK • The Journal of Arthroplasty

Clinical Implication: Pooled data confirm a high ETO union rate and low subsidence; cable-plate fixation is favoured, supporting routine use of a well-conducted ETO to avoid uncontrolled intraoperative fracture.

Verify on PubMed (PMID 32800436)

Clinical Decision Scenarios

Use these scenarios to practise clinical reasoning and management decisions

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"A 68-year-old woman presents with progressive right hip pain 12 years after cemented THA. X-rays show femoral stem loosening with circumferential radiolucencies and proximal metaphyseal bone loss. CT shows the isthmus is intact with 6cm of diaphyseal bone available. How would you classify this and plan management?"

PRACTICAL APPROACH

This patient has aseptic loosening of her cemented femoral stem with a PAPROSKY TYPE IIIA femoral defect - characterized by severe proximal metaphyseal bone loss but MORE than 4cm of supportive diaphyseal isthmus remaining (6cm in this case). This is the ideal indication for an EXTENSIVELY POROUS COATED stem. PREOPERATIVE PLANNING: Full workup to exclude infection - inflammatory markers (CRP, ESR), aspiration if any concern. CT scan for detailed bone loss assessment - confirms 6cm isthmus intact. Template for stem size - extensively porous stems are available in various lengths and diameters. Plan for extended trochanteric osteotomy (ETO) as distal cement removal will be required and a well-fixed cement mantle typically requires ETO access. OPERATIVE PLAN: Lateral decubitus, posterior approach through previous incision. Perform ETO (about one-third of femoral length, lateral fragment preserving the abductor-vastus sleeve, rounded distal corner). Remove stem and ALL cement using high-speed burr and ultrasonic tools. Sequential broaching/reaming until SCRATCH FIT achieved in the diaphysis - goal is at least 4-5cm of cortical contact in the intact isthmus. This scratch fit provides initial axial and rotational stability while the circumferential porous coating allows bone ingrowth for long-term fixation. A modular tapered fluted stem is an equally valid contemporary choice for the same defect. Trial to confirm stability, length, and offset. Insert final stem with modular head. Repair ETO with cerclage cables (commonly 2-3) or a cable-plate. Post-operatively: protected weight bearing for about 6 weeks to allow ETO healing and ingrowth.

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"During femoral revision, you are preparing to perform an extended trochanteric osteotomy. Describe your technique in detail, including length, position, execution, and repair."

PRACTICAL APPROACH

The EXTENDED TROCHANTERIC OSTEOTOMY (ETO) is essential for controlled access in femoral revision surgery. INDICATIONS: Well-fixed cementless or cemented stem, distal cement removal required, correcting proximal femoral deformity. TECHNIQUE - MARKING: Length is about one-third of the femur (commonly 12-14cm from the greater trochanter tip), ending 2cm or more proximal to the host-bone segment the new stem must engage. The fragment is a LATERAL/ANTEROLATERAL segment (roughly one-third of the circumference) carrying the greater trochanter, abductors and vastus lateralis as a single muscle-bone sleeve. Mark with diathermy or sterile marker. EXECUTION: Make the LONGITUDINAL CUT along the lateral cortex with an oscillating or pencil-tip saw. ROUND the distal transverse corner - drill several holes and connect them - to reduce the stress riser and prevent uncontrolled fracture propagation. Control depth to avoid cutting into the stem or cement. HINGING: Use wide osteotomes to lever the fragment FORWARD on its anterior soft-tissue/muscle hinge; it opens like a book to expose the canal. NEVER strip the abductor-vastus sleeve off the fragment - this maintains both perfusion (for union) and abductor function. REPAIR: After stem insertion, reduce the fragment anatomically and secure it with cerclage CABLES (preferred over monofilament wire in revision), commonly 2-3, placed over host diaphysis distal to the rounded corner; add a cable-grip plate for osteopenic or comminuted fragments. Tension to the manufacturer specification - do not overtighten (notch/fracture, cut-through). Confirm stability with hip ROM before closure. POST-OP: Protected weight bearing about 6 weeks, avoid active/resisted abduction during early healing. Large series report about 93-98% union.

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"A 72-year-old man undergoes revision THA with an extensively porous stem. At 6 weeks post-operatively, he reports progressive thigh pain and X-rays show 8mm of stem subsidence compared to immediate post-op films. How do you evaluate and manage this?"

PRACTICAL APPROACH

Stem subsidence of 8mm at 6 weeks is a concerning finding that requires systematic evaluation. ASSESSMENT: (1) HISTORY: Distinguish progressive pain (concerning for ongoing instability) from stable symptoms. Ask about weight bearing compliance, falls, or trauma. (2) CLINICAL EXAM: Trendelenburg sign (abductor function), limb length comparison, hip ROM, signs of infection (warmth, erythema, effusion). (3) RADIOGRAPHIC: Compare to immediate post-op - document exact subsidence. Assess stem position (varus/valgus), cortical contact in isthmus, ETO healing. Look for fracture or periprosthetic lucency. (4) LABORATORY: CRP, ESR to exclude infection. INTERPRETATION: Subsidence occurs because of inadequate initial scratch fit - stem did not achieve sufficient interference with diaphyseal cortex. Can be due to undersized stem, bone quality issues, or technical factors. MANAGEMENT ALGORITHM: STABLE SUBSIDENCE (less than 10mm, not progressing, minimal symptoms): Many extensively porous stems stabilize after initial settling. Serial X-rays at 6, 12, 24 weeks. If no further migration and symptoms improving, observe - bone ingrowth may still occur. PROGRESSIVE SUBSIDENCE (continuing to migrate, worsening symptoms): Indicates stem will not stabilize. Revision options: (1) Larger extensively porous stem if adequate isthmus remains, (2) Modular tapered wedge stem for more distal fixation, (3) Cemented stem in poor bone stock, (4) Proximal femoral replacement if massive bone loss. This patient with 8mm subsidence needs close follow-up - repeat X-ray in 2-4 weeks. If stable, continue observation. If progressing, plan revision.