High-yield overview

Salvage arthroplasty | intermediate complexity

Critical Danger Structures

Sciatic Nerve (Posterior Approach)

Location: 10-20mm posterior to posterior hip capsule, exits pelvis beneath piriformis

Protection: Early identification before capsular dissection, maintain gentle retraction, avoid excessive internal rotation during femoral preparation

Femoral Neurovascular Bundle (Anterior Approach)

Location: 15-25mm medial to anterior hip capsule, travels beneath iliopsoas

Protection: Medial Hohmann retractor placement under direct vision, avoid aggressive medial retraction during acetabular preparation

Superior Gluteal Nerve (Posterior Approach)

Location: Exits sciatic notch 5cm superior to piriformis insertion, courses between gluteus medius and minimus

Protection: Limit proximal dissection to less than 5cm above greater trochanter, avoid detaching anterior third of gluteus medius

Lateral Femoral Cutaneous Nerve (Anterior Approach)

Location: 1-3cm medial to ASIS, superficial to sartorius origin

Protection: Incision planned 2-3cm lateral to ASIS, identify and preserve during fascia lata incision

Perforating Vessels (Femoral Preparation)

Location: First perforator 5-7cm distal to lesser trochanter, subsequent perforators every 3-4cm

Protection: Controlled reaming speeds, cautery/bone wax for bleeding, avoid aggressive fenestration near perforators

Mnemonic

HARDWAREHardware Assessment Required: Document Wound, Assess Re-operation Exposure

Mnemonic

STEM-FITStem Fixation In Trauma - component selection strategy

Primary Indications

Nonunion/Malunion

Femoral neck nonunion following cannulated screw fixation (greater than 6 months post-injury)
Intertrochanteric nonunion after DHS/cephalomedullary nail with persistent pain and functional limitation
Malunion with varus deformity causing mechanical symptoms and secondary acetabular wear

Avascular Necrosis

Segmental collapse of femoral head following fracture fixation (Ficat Stage 3-4)
Subchondral insufficiency fracture with progressive pain despite conservative management
Combined femoral head AVN and acetabular cartilage loss requiring dual-component arthroplasty

Hardware Failure

Implant cut-out with femoral head penetration requiring salvage arthroplasty
Plate/screw breakage with loss of fixation and progressive deformity
Subsidence of cephalomedullary nail with persistent proximal thigh pain

Post-Traumatic Arthritis

Progressive joint space narrowing following periarticular hip fracture
Intra-articular malunion causing impingement and accelerated cartilage wear
Combined bone loss (acetabular and femoral) requiring reconstruction

Contraindications

Absolute

Active sepsis (elevated inflammatory markers, positive cultures)
Medical instability precluding elective arthroplasty
Irreversible sciatic nerve palsy with non-functional limb

Relative

Recent infection (less than 6 weeks post-treatment)
Severe osteoporosis (T-score less than -4.0) with poor bone quality
Significant abductor deficiency without reconstructable soft tissues
Patient factors: poor compliance, active substance abuse, untreated psychiatric illness

Pre-operative Planning

Imaging Assessment

AP pelvis and cross-table lateral: Assess bone stock, hardware position, leg length discrepancy
Judet views: Acetabular columns, wall defects if acetabular component needed
Full-length femur AP/lateral: Entire nail if present, distal locking screws, femoral bow
CT scan: Complex bone loss, 3D reconstruction for templating, hardware assessment

Templating Strategy

Magnification correction: Calibrate with known implant size or marker
Account for bone loss: Medial calcar defects, greater trochanter position, acetabular floor
Component selection: Long-stem revision components, dual mobility cup, constraint options
Offset/length restoration: Compare to contralateral hip, document planned leg length change

Hardware Inventory

Extraction instruments: Screw extractors, conical extractors, plate removal set
Nail removal tools: Universal extraction device, slap hammer, femoral hooks
Fenestration equipment: High-speed burr, trephines (8-12mm), cerclage cables
Revision implants: Modular stems, extended offset options, dual mobility bearings

Patient Positioning

Lateral Decubitus (Posterior Approach)

Well-padded lateral positioning device
Dependent leg flexed 90-90 degrees
Operative leg draped free
Anterior and posterior pelvic posts to prevent rotation
Check prominence of hardware beneath skin

Supine (Anterior Approach)

Bump beneath ipsilateral buttock (10-15 degrees tilt)
Standard table or fracture table with traction capability
Prepare from iliac crest to knee
Image intensifier available if needed for hardware removal

Detailed Operative Steps

Step 1: Incision and Superficial Dissection

Incorporate previous surgical scars where possible to preserve blood supply

Clinical Pearl

Technical Tip: Plan incision to avoid parallel scars less than 6cm apart. If previous anterior incision exists and using posterior approach, ensure adequate skin bridge (minimum 8cm) or use same incision with skin bridge technique.

Skin Necrosis Risk

Parallel incisions less than 6cm apart compromise perfusion
Undermining skin flaps increases devascularization
Revision incisions should follow previous if within 45 degrees of ideal line

Step 2: Deep Dissection to Joint Capsule

Posterior approach: Split gluteus maximus in line with fibers, identify short external rotators

Anterior approach: Develop TFL/rectus interval, protect ascending branch LFCA

Clinical Pearl

Technical Tip: Palpate greater trochanter to assess position - may be displaced superiorly (shortening) or detached. Plan fixation strategy before proceeding if trochanteric osteotomy needed.

Nerve Identification

Posterior: Identify sciatic nerve before capsular dissection - may be tethered in scar
Anterior: Identify femoral nerve lateral to artery, decompress iliopsoas if tense
Place marking suture around nerve if anatomy distorted

Step 3: Capsular Exposure and Hardware Visualization

Tag short external rotators before release, expose posterior capsule and hardware

Clinical Pearl

Technical Tip: Hardware often visible through attenuated capsule. Assess implant integrity before removal - bent/broken screws require alternative extraction techniques.

Unexpected Hardware

Fluoroscopy available if hardware configuration unclear
Additional incisions may be needed for proximal nail screws
Prepare for extended operative time if complex extraction required

Step 4: Hardware Removal - Screws/DHS

Cannulated screws: Remove guide wires first, then unscrew under fluoroscopy if threads stripped

DHS: Remove lag screw first, then plate screws from distal to proximal, extract plate

Clinical Pearl

Technical Tip: If screw head stripped, use conical extraction device. Drill 2-3mm hole adjacent to screw, apply extractor, gentle counter-clockwise torque. If fails, window femur and push screw out.

Screw Extraction Complications

Screw breakage leaves fragment in situ - may need to fenestrate around fragment
Over-torquing causes femoral fracture - assess bone quality before aggressive extraction
Bone loss around screws creates defects requiring grafting

Step 5: Hardware Removal - Cephalomedullary Nail

Identify proximal locking screws, remove before extracting nail body

If nail extractable via proximal entry: Attach universal extraction device, gentle slap-hammer technique

If nail incarcerated: Plan lateral femoral window 5-7cm distal to tip, push nail proximally

Clinical Pearl

Technical Tip: Make femoral window 3x nail diameter, use trephines to preserve bone stock. Save cortical window as structural graft for acetabular/calcar defects.

Fenestration Risks

Perforating vessels at posterior femur - controlled cautery, bone wax
Create stress riser requiring long-stem bypass
Preserve anterior cortex to maintain femoral bow and rotation

Step 6: Femoral Head Removal

If head attached: capsulotomy, dislocate hip (posterior: flex, adduct, internal rotate)

If head necrotic: may fragment during dislocation, remove piecemeal

Clinical Pearl

Technical Tip: If unable to dislocate due to scarring, perform extended capsulectomy. Release gluteus minimus attachment to anterior capsule, divide capsule circumferentially. Trochanteric osteotomy if still cannot dislocate safely.

Dislocation Complications

Avoid excessive force - proximal femur fracture risk in osteoporotic bone
Sciatic nerve palsy from forceful internal rotation
Femoral neck fracture during dislocation may alter stem selection

Step 7: Acetabular Assessment and Preparation

Assess native acetabulum: cartilage wear, subchondral cysts, protrusion

If previous hemiarthroplasty: Remove femoral head component, assess acetabular bone loss

Clinical Pearl

Technical Tip: Use hemisphere reamers 2mm larger than templated cup size. Ream until subchondral bleeding (dot sign). If medial wall deficient, use bulk allograft or augments to restore floor level.

Acetabular Preparation Dangers

Intrapelvic protrusion risk if medial wall thin - assess wall thickness before reaming
Superior gluteal vessels at anterosuperior quadrant
Obturator vessels at inferomedial quadrant
Sciatic nerve 10mm posterior to posterior wall

Step 8: Acetabular Component Insertion

Standard uncemented cup if good bone stock (press-fit, 1-2mm underream)

Dual mobility cup preferred in conversion cases (reduces dislocation risk from 15-20% to less than 5%)

Clinical Pearl

Technical Tip: Target 40 degrees abduction, 15-20 degrees anteversion. Use transverse acetabular ligament (TAL) as landmark - points to native floor. Dual mobility outer metal shell impacted to line-to-line fit.

Cup Malposition

Excessive anteversion (greater than 25 degrees) causes posterior instability in flexion
Insufficient anteversion (less than 10 degrees) risks posterior dislocation in extension
Vertical cup (greater than 45 degrees abduction) increases edge-loading and wear

Step 9: Femoral Bone Stock Assessment

Assess defects using Paprosky classification:

Type I: Minimal metaphyseal bone loss, intact diaphysis
Type II: Extensive metaphyseal loss, intact diaphysis (most common in conversion)
Type III: Metaphyseal and proximal diaphyseal loss
Type IV: Extensive diaphyseal loss

Clinical Pearl

Technical Tip: Measure distances: calcar height, greater trochanter position, canal diameter at isthmus. Compare to templating. Most conversions require Type II reconstruction with calcar-replacing stem.

Step 10: Femoral Canal Preparation

Screw hole management: Graft holes less than 8mm with morselized bone. Large defects (greater than 10mm) require structural graft or impaction technique.

Reaming strategy: Hand reamers initially to assess canal, powered reamers if good bone. Under-ream 0.5-1mm for press-fit stems.

Clinical Pearl

Technical Tip: Start with flexible reamers to follow canal. If encountering obstruction (retained screw fragment, heterotopic bone), use rigid straight reamers or hand instruments. Verify reamer depth - should pass 2cm beyond planned stem tip.

Reaming Complications

Cortical perforation from eccentric reaming or canal deformity
Femoral fracture in osteoporotic bone - use hand reamers if T-score less than -3.0
Thermal necrosis from high-speed reaming - irrigate continuously

Step 11: Femoral Component Selection

Primary stem possible if:

Intact medial calcar (Dorr Type A or B bone)
Minimal metaphyseal bone loss
Good proximal bone quality
Screw holes bypassed by 2 cortical diameters

Revision stem required if:

Calcar deficient (requires calcar-replacing design)
Multiple screw holes (requires long stem to bypass stress risers)
Canal capacious (requires modular taper-fit or cemented stem)
Proximal femur fracture during procedure

Clinical Pearl

Technical Tip: Calcar-replacing stems (e.g., Corail revision, Wagner SL Revision) restore medial offset and bypass calcar defects. Long stems (150-200mm) achieve fixation 2 cortical diameters below lowest defect. Modular components allow independent version/offset adjustment.

Step 12: Stem Insertion and Fixation

Cementless technique: Broach sequentially, confirm rotational stability with trials, final component 1 size larger than last broach

Cemented technique: Pulse-lavage, dry canal, retrograde cement gun, pressurization, stem insertion before cement hardening

Clinical Pearl

Technical Tip: Restore femoral anteversion (10-15 degrees) using lesser trochanter as guide. Correct version prevents impingement and reduces dislocation risk. If uncertain, aim for combined anteversion 25-40 degrees (acetabular + femoral).

Stem Insertion Complications

Intraoperative fracture (20-30% in revision cases) - manage with cerclage cables, may need longer stem
Stem subsidence if inadequate distal fit - verify scratch-fit at trial stage
Leg length discrepancy - measure from heel to ASIS, compare to contralateral side

Step 13: Greater Trochanter Management

If trochanteric osteotomy performed: reduce fragment, tension-band wire or cable-plate fixation

If trochanter fragmented/detached: advance and reattach with sutures to stem, cables around prosthesis

Clinical Pearl

Technical Tip: Use dual cables (proximal and distal) for trochanteric fixation. Pre-drill holes in trochanter fragment before passing cables. Tension with hip in extension to restore abductor tension. Verify fragment position on fluoroscopy before final tensioning.

Trochanteric Nonunion Risk

Occurs in 10-20% of cases despite fixation
Higher risk if abductors weak pre-operatively
Requires abduction brace for 6 weeks post-op if fixation tenuous

Step 14: Trial Reduction and Stability Assessment

Reduce trial components, assess stability through range of motion

Posterior approach stability testing:

Flexion 90 degrees, adduction, internal rotation (posterior dislocation)
Extension, adduction, external rotation (anterior dislocation)

Anterior approach stability testing:

Extension, external rotation (posterior dislocation)
Flexion 90 degrees, internal rotation (anterior dislocation)

Clinical Pearl

Technical Tip: Instability management algorithm: (1) Optimize cup position, (2) Increase head size (32mm to 36mm), (3) Increase offset if soft tissue tension inadequate, (4) Convert to dual mobility if still unstable, (5) Consider constrained liner as last resort.

Instability Red Flags

Soft tissue tension inadequate (no resistance to distraction) - increase offset/leg length
Impingement at extremes of motion - adjust version or increase head size
Inability to reduce despite component adjustment - assess for bone block or soft tissue interposition

Step 15: Final Component Implantation

Remove trials, clean and dry implant beds, insert final components

Reduce hip with stable maneuver, verify seating with gentle traction

Clinical Pearl

Technical Tip: For dual mobility construct, ensure inner polyethylene head fully seated on femoral taper before reduction. Audible "click" confirms seating. Outer metal shell should rotate freely around inner head after reduction.

Step 16: Wound Closure and Soft Tissue Repair

Posterior approach: Repair short external rotators to greater trochanter (piriformis, obturator), capsular closure if tissue adequate

Anterior approach: Repair capsule if preserved, close TFL fascia, subcutaneous layer

Clinical Pearl

Technical Tip: Enhanced soft tissue repair reduces dislocation risk. Posterior approach: perform capsular-rotator repair with heavy non-absorbable sutures (No. 2 FiberWire) through bone tunnels in trochanter. Anterior approach: repair indirect head of rectus femoris to preserve anterior capsule.

Closure Considerations

Drain placement controversial - consider if large dead space or concern for hematoma
Layered closure with absorbable sutures to deep fascia, interrupted dermal sutures to skin
Wound edge approximation without tension - accept slightly wider scar if tension present

Step 17: Intra-operative Imaging Confirmation

AP pelvis and cross-table lateral radiographs on operating table

Assess: component position, leg length (lesser trochanter height), no fractures

Clinical Pearl

Technical Tip: Measure leg length using anatomic landmarks: from sacral ala to lesser trochanter (medial edge). Compare to pre-operative templating. Accept 5-10mm lengthening for stability but warn patient. Shortening greater than 5mm usually not tolerated.

Step 18: Post-operative Instructions to Team

Document: approach used, component sizes, bearing surface, fixation method, intra-operative complications

Post-op orders: hip precautions (posterior vs anterior), weight-bearing status, DVT prophylaxis, rehabilitation protocol

Clinical Pearl

Technical Tip: Weight-bearing restrictions based on bone quality and fixation: (1) Cementless with good bone = weight-bearing as tolerated, (2) Cemented or poor bone = toe-touch for 6 weeks, (3) Trochanteric osteotomy = abduction brace and partial weight-bearing for 6 weeks.

Complications and Management

Major Complications: Recognition, Prevention, and Management

Clinical Decision Scenarios

Use these scenarios to practise clinical reasoning and management decisions

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"A 72-year-old woman presents 18 months after cannulated screw fixation of a displaced femoral neck fracture. She has persistent groin pain, limited function, and radiographs show segmental collapse of the femoral head with screws in situ. How would you manage this patient?"

PRACTICAL APPROACH

This patient has failed internal fixation with AVN and segmental collapse requiring salvage arthroplasty. I would approach this systematically through assessment, planning, and surgical strategy. **Assessment**: Complete history including infection risk factors, medical optimization status, functional demands. Examination for leg length discrepancy, abductor strength, neurovascular status. Investigations: AP pelvis and lateral hip radiographs to assess bone stock, screw position, acetabular cartilage. Inflammatory markers (ESR, CRP) to exclude infection. Consider CT if complex bone loss or retained hardware concerns. **Pre-operative Planning**: Templating on calibrated radiographs accounting for calcar bone loss. Plan conversion to total hip arthroplasty with hardware removal. Component selection: likely require revision-type femoral component (calcar-replacing stem) given segmental collapse and medial calcar deficiency from screws. Dual mobility cup to reduce dislocation risk. Prepare hardware extraction instruments. **Surgical Approach**: Posterior approach provides excellent exposure for hardware removal and component insertion. Systematic hardware removal: remove screws sequentially, preserve bone stock during extraction. Assess femoral bone defects (Paprosky classification) - likely Type II with metaphyseal loss. Acetabular preparation: likely needs total hip replacement (THR) given cartilage damage from abnormal loading. Insert dual mobility cup (40° abduction, 15° anteversion). Femoral preparation: graft screw holes, use calcar-replacing long stem (150-200mm) bypassing defects. Restore offset and leg length per templating. **Post-operative**: Extended DVT prophylaxis 35 days, posterior hip precautions 6 weeks, weight-bearing as tolerated if good bone quality. Monitor for complications: dislocation (reduced with dual mobility), infection (higher risk in conversion), nerve injury.

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"You are planning a conversion THA for a 68-year-old man with failed DHS fixation of an intertrochanteric fracture. Radiographs show the lag screw has cut out superiorly with varus collapse. Walk me through your pre-operative planning and surgical strategy."

PRACTICAL APPROACH

This represents a challenging conversion with likely significant bone loss from the fracture, malunion, and hardware failure. My approach would focus on comprehensive planning for hardware removal and reconstruction. **Pre-operative Assessment**: Full-length AP and lateral femur radiographs to assess entire DHS plate, distal screws, degree of varus collapse, greater trochanter position. Judet views to assess acetabulum - often develops superior wear from altered mechanics. CT scan with 3D reconstruction to define bone loss, particularly medial calcar and greater trochanter. Measure leg length discrepancy (likely shortened on affected side). Template for component sizes accounting for defects. **Hardware Considerations**: DHS removal requires specific strategy: (1) Remove lag screw first - may be intrapelvic if cut-out, fluoroscopy to localize, (2) Remove side plate screws from distal to proximal, (3) Extract plate - may be adherent to lateral femur, need elevator. Prepare lag screw extraction set, conical extractors for stripped screws, high-speed burr if screw needs windowing. **Bone Stock Assessment**: Varus malunion creates specific defects: (1) Medial calcar deficiency - requires calcar-replacing stem, (2) Greater trochanter displacement - may need advancement and cable fixation, (3) Lag screw hole in femoral head/neck - bone loss in typical reaming path, (4) Lateral plate screw holes - stress risers requiring bypass. Likely Paprosky Type II or III femoral deficiency. **Component Selection**: Acetabulum: likely needs resurfacing given superior wear, standard uncemented cup if good bone. Consider dual mobility for instability risk. Femur: revision-type stem essential - calcar-replacing design (Wagner SL Revision, Corail Revision), length 150-200mm to bypass plate screw holes, modular junction allows offset/version adjustment. If very poor bone, cemented stem option. Prepare for cerclage cables if intraoperative fracture. **Surgical Technique**: Posterior or lateral approach. Extended exposure likely needed. Remove hardware systematically. If lag screw intrapelvic, remove after acetabular exposure - may aid in acetabular visualization. Femoral preparation: graft screw holes with morselized bone, ream carefully to avoid perforation through varus malunion. Extended trochanteric osteotomy if cannot deliver femur for reaming. Restore anatomy: correct varus, restore offset (increased head-neck offset to restore abductor moment arm), equalize leg length.

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"During a conversion THA for failed femoral neck fracture fixation, you encounter a cephalomedullary nail that will not extract via the proximal entry point. How do you proceed?"

PRACTICAL APPROACH

An incarcerated cephalomedullary nail requires a systematic approach to safe removal without causing iatrogenic femoral fracture or excessive bone loss. **Immediate Assessment**: Stop extraction attempts to avoid proximal femur fracture. Obtain intraoperative AP and lateral fluoroscopy to assess: (1) Nail position - confirm fully within canal, not perforated, (2) Distal locking screws - ensure all removed (common cause of incarceration), (3) Proximal locking screws - verify removed or can be disengaged, (4) Bone quality - assess cortical thickness for fenestration planning. **Problem Solving Algorithm**: First, ensure all locking screws removed - often distal screws missed. Second, verify extraction device engaged properly - should thread 3-4 turns into proximal nail. Third, attempt gentle slap-hammer technique with hip flexed to relax soft tissues. If still incarcerated, nail likely bone-ingrown or jammed from malunion - plan controlled femoral fenestration. **Femoral Fenestration Technique**: Create lateral cortical window to push nail proximally. Location: 5-7cm distal to nail tip (avoid perforating vessels at posterior femur), mark with fluoroscopy. Window size: 3x nail diameter (typically 30-35mm long, 10-12mm wide). Use trephines to preserve cortical bone as structural graft. Create longitudinal cut with oscillating saw, complete with osteotomes. Protect soft tissues with retractors. Insert femoral hook or curved osteotome through window to push nail proximally while assistant extracts from proximal entry. **Salvage of Cortical Window**: Save cortical bone segment - useful as structural graft for acetabular or calcar defects. Can morselized if not needed structurally. Measure window size for stem planning - requires bypassing by 2 cortical diameters. **Altered Surgical Plan**: Window creates stress riser requiring longer stem. Calculate required length: window location plus 2 cortical diameters (typically 14-16cm). Example: if window at 12cm from greater trochanter, need stem at least 26-28cm total length. Consider cable prophylaxis around window site. May need extended proximal coating or cemented stem if cortices thin. If window large (greater than 5cm) or comminuted, consider extended trochanteric osteotomy instead - provides better exposure and more reliable healing. **Intraoperative Decision Points**: If nail still difficult after window, extend window proximally (becomes extended trochanteric osteotomy) rather than create multiple windows. If cortical bone very thin (less than 3mm), prophylactic cables before broaching. If unexpected perforation during fenestration, convert to longer stem and cable fixation. **Post-operative Modifications**: Protected weight-bearing (toe-touch 6 weeks) if cortices thin or window large. Consider brace if mechanical stability concerns. Close monitoring of window site for fracture on 6-week and 12-week radiographs.