High Yield Overview

REVERSE TSA REVISION

Deltopectoral or superolateral approach | High complexity revision arthroplasty

Critical Danger Structures

Axillary Nerve

Location: Courses 5-7cm inferior to acromion, anteroinferior to subscapularis, exits quadrangular space

Protection: Careful subscapularis mobilization, avoid inferior dissection beyond 5cm from coracoid, palpate during inferior retraction

Musculocutaneous Nerve

Location: Enters conjoint tendon 3-8cm distal to coracoid tip (variable)

Protection: Limit medial retractor penetration depth to <2cm, avoid aggressive medial soft tissue stripping, visualize conjoint tendon

Suprascapular Nerve

Location: Scapular notch (superior) and spinoglenoid notch (posterior-superior)

Protection: Avoid over-medialization of baseplate screws, careful with superior screw placement, limit posterior dissection

Brachial Plexus Cords

Location: Medial to coracoid process and conjoint tendon (2-3cm medial to operative field)

Protection: Controlled medial retraction, avoid overzealous soft tissue release medially, identify anatomical landmarks

Cephalic Vein

Location: Deltopectoral interval, variable anatomy with tributaries

Protection: Preserve or carefully ligate (risk of venous congestion if disrupted), retract laterally with deltoid preferred

Mnemonic

REVISEREVISE - Indications for Reverse TSA Revision

Mnemonic

GLENOIDGLENOID - Bone Loss Management Strategy

Assessment and Decision Making

Imaging Requirements

AP, scapular Y, axillary views: Implant position, bone loss, subluxation
CT scan with metal artifact reduction: Essential for bone stock assessment
- Sirveaux classification of glenoid defects
- Nerot-Sirveaux modification for central vs peripheral loss
- Screw trajectory planning for revision fixation
Consider advanced imaging:
- Labeled WBC scan if infection suspected
- CRP/ESR - elevated suggests infection (threshold >10 CRP)
- Aspiration with culture hold 48-72 hours minimum

Failure Mode Classification

Implant Inventory Planning

Previous operative notes (implant type, sizes, cementing)
Revision stem options (long stem, metaphyseal engaging)
Baseplate options (standard, augmented, custom)
Glenosphere options (various sizes, lateralization options)
Bone graft availability (allograft vs autograft iliac crest)
Subscapularis reconstruction materials if deficient

Step-by-Step Technique

Step 1: Patient Positioning

Beach chair position at 30-40 degrees, head supported in neutral, entire scapula free to manipulate

Exam Pearl

Positioning Pearl: Ensure ability to extend arm off side of table for humeral exposure - inadequate setup leads to difficult humeral component extraction and increased fracture risk

Positioning Dangers

Inadequate scapular mobility prevents proper glenoid visualization
Hypotension with steep beach chair (reduce angle if unstable)

Step 2: Incision and Approach

Use previous deltopectoral incision, extend if needed proximally toward clavicle or distally 1-2cm beyond deltoid insertion

Exam Pearl

Incision Strategy: If multiple previous incisions present, use most lateral to preserve medial skin bridge blood supply - parallel incisions <3cm apart risk skin necrosis

Skin Dangers

Thin scarred skin prone to necrosis - handle gently, minimal undermining
Previous infection history - consider plastic surgery consultation for flap coverage

Step 3: Deltopectoral Interval Development

Identify cephalic vein, develop interval, preserve vein with lateral retraction (or ligate if necessary), divide clavipectoral fascia

Exam Pearl

Revision Tip: Dense scar tissue obliterates normal planes - identify coracoid tip first as landmark, work from known to unknown anatomy to protect musculocutaneous nerve

Interval Dangers

Axillary nerve vulnerable if dissection extends >5cm below coracoid tip
Cephalic vein disruption causes deltoid venous congestion

Step 4: Subscapularis Assessment

Identify subscapularis remnant or previous repair - often scarred to anterior capsule and humeral component

Exam Pearl

Critical Decision: If subscapularis quality poor (<50% thickness), consider leaving detached and converting to latissimus dorsi transfer at completion for external rotation strength

Subscapularis Dangers

Axillary nerve exits at inferior border - palpate and protect during inferior mobilization
Aggressive mobilization causes denervation even if nerve not transected

Step 5: Capsulotomy and Joint Exposure

Release anterior capsule from glenoid rim, inferior capsule from humeral neck - extensive release needed for component extraction

Exam Pearl

Exposure Pearl: Circumferential capsular release around humeral component essential - incomplete release causes iatrogenic fracture during extraction attempts

Capsular Release Dangers

Inferior release beyond 5cm from coracoid risks axillary nerve
Posterior-superior release risks suprascapular nerve at spinoglenoid notch

Step 6: Component Dislocation Strategy

If glenosphere removable: dislocate first then remove sphere. If glenosphere locked: may need to remove humeral tray first, then dislocate

Exam Pearl

Dislocation Technique: External rotation and extension - if unable to dislocate, STOP and remove glenosphere first rather than forcing (fracture risk)

Dislocation Dangers

Forced dislocation causes humeral shaft fracture (especially osteoporotic bone)
Glenoid rim fracture if levering against glenosphere

Step 7: Humeral Component Removal (if needed)

Remove humeral polyethylene liner, dislocate (or remove glenosphere first), use extraction device on taper or cement if cemented

Exam Pearl

Extraction Pearl: If well-fixed uncemented stem, create humeral window using oscillating saw 2cm distal to lesser tuberosity - preserve bone stock for revision stem fixation

Humeral Removal Dangers

Humeral shaft fracture during extraction (incidence 3-5% in revision)
Radial nerve injury with distal extension of dissection (posterior spiral groove)

Step 8: Extended Humeral Exposure if Needed

For well-fixed stem: humeral window (rectangular cortical window) or extended trochanteric osteotomy allows stem extraction without fracture

Exam Pearl

Window Technique: Make window 2cm wide, length = 2x stem length, 2cm distal to lesser tuberosity starting point - secure with cerclage wires at closure

Osteotomy Dangers

Window too proximal weakens metaphysis - stay 2cm below lesser tuberosity minimum
Incomplete osteotomy causes fracture propagation during stem extraction

Step 9: Glenoid Exposure

Retract humerus posteriorly and inferiorly, release soft tissue adhesions around baseplate, expose baseplate edge circumferentially

Exam Pearl

Glenoid Visualization: Use bent Hohmann retractors: one inferior, one posterior, one superior - creates triangulated exposure essential for baseplate removal

Glenoid Exposure Dangers

Superior retractor risks suprascapular nerve at scapular notch
Aggressive posterior retraction risks spinoglenoid notch injury

Step 10: Baseplate and Screw Removal

Remove glenosphere (if not already done), remove locking screws sequentially, extract baseplate using dedicated removal tools or osteotomes carefully

Exam Pearl

Removal Sequence: Remove peripheral screws first (superior, inferior, posterior), then central compression screw last - maintain some fixation during dissection to prevent spinning

Baseplate Removal Dangers

Screw breakage leaves retained hardware - may need to drill out or leave if well-buried
Glenoid vault fracture if baseplate levered aggressively

Step 11: Bone Stock Assessment

Remove fibrous tissue and sclerotic bone, assess remaining bone stock with CT correlation, classify defect (Sirveaux or Nerot-Sirveaux)

Exam Pearl

Assessment Pearl: Use curette to assess bone quality - if curette penetrates easily, insufficient bone stock for screw purchase, requires grafting or augmentation strategy

Assessment Dangers

Over-resection of sclerotic bone causes unnecessary bone loss
Failure to recognize defect extent leads to inadequate reconstruction

Step 12: Minor Defect Management

For peripheral defects <5mm: use larger diameter baseplate (covers defect), or use augmented baseplate with built-in wedge

Exam Pearl

Augment Strategy: Place augment on defect side to restore glenoid anatomy - typically inferior for wear pattern, provides structural support and corrects version

Augment Dangers

Augment overhang risks impingement and instability
Inadequate augment seating causes micromotion and early loosening

Step 13: Major Defect Management (BIO-RSA)

For central or major defects >5mm: prepare graft (autograft iliac crest or structural allograft), place under baseplate, fix with screws through baseplate

Exam Pearl

BIO-RSA Technique: Graft must be >10mm thick, shaped to fill defect, central screw penetrates graft into native bone - incorporation occurs at 6-12 months, delay full activity

Grafting Dangers

Graft resorption if inadequate vascularity (>20% volume loss expected)
Baseplate subsidence if graft not compressed adequately during fixation

Step 14: Severe Bone Loss - Custom Implants

For massive defects with glenoid vault compromise: patient-specific custom baseplate with scapular body engagement (coracoid, spine, scapular pillar)

Exam Pearl

Custom Implant Pearl: Requires preoperative CT-based planning, 6-8 week manufacturing time - interim surgery with graft compaction and delayed reconstruction alternative approach

Custom Implant Dangers

Scapular fracture during insertion if fit too tight
Limited screw trajectory options - may compromise nerve safety margins

Step 15: Baseplate Positioning

Position baseplate with 10-15 degrees inferior tilt, neutral or slight anteversion, flush with inferior glenoid rim - avoid superior placement

Exam Pearl

Positioning Pearl: Inferior tilt critical to prevent scapular notching - use glenoid vault as reference (perpendicular to vault = neutral, then tilt inferiorly)

Positioning Dangers

Superior tilt causes scapular notching and accelerated loosening
Excessive retroversion limits external rotation and causes posterior instability

Step 16: Screw Fixation Strategy

Central compression screw first (into vault), then peripheral locking screws - aim for bicortical purchase, divergent trajectories for maximum fixation

Exam Pearl

Screw Pearl: Superior screw directed toward coracoid base (strong bone), inferior screws toward scapular pillar, posterior screw toward spine - avoid convergence

Screw Dangers

Anterior screws risk brachial plexus (stay lateral to coracoid base)
Superior-medial screws risk suprascapular nerve at scapular notch
Over-torquing causes screw breakage or bone fracture

Step 17: Glenosphere Attachment

Select appropriate glenosphere size (36mm standard, 42mm for lateralization), ensure proper locking mechanism engagement, check stability manually

Exam Pearl

Lateralization Pearl: Lateralized glenosphere (+10mm) improves deltoid moment arm and reduces scapular notching but increases shear forces on baseplate - use selectively for instability cases

Glenosphere Dangers

Incomplete locking causes dissociation (check for gap between sphere and baseplate)
Oversized sphere limits motion and causes impingement on acromion

Step 18: Humeral Component Revision

If humeral loosening present: remove old stem, ream to fit new revision stem (2mm larger diameter or 20mm longer minimum), cement if poor bone quality

Exam Pearl

Humeral Revision Pearl: Long stem revision (120-150mm) bypasses stress risers from previous screw holes and cement - ensure 2 cortical diameters below any defect

Humeral Revision Dangers

Underfilling humeral canal risks subsidence and instability
Oversizing during reaming causes fracture (especially revision osteopenic bone)

Step 19: Trial Reduction Testing

Insert trial components, reduce, test stability in full range: forward flexion, abduction, rotation - should be stable to 90 degrees flexion and 30 degrees external rotation

Exam Pearl

Stability Assessment: "Shuck test" - apply inferior traction force; <1cm translation acceptable, >1cm indicates inadequate tensioning - consider thicker polyethylene or more lateralized glenosphere

Trialing Dangers

Forced reduction during trialing causes iatrogenic fracture
Instability recognized but not addressed leads to early revision for dislocation

Step 20: Final Component Implantation

After confirming satisfactory trial, implant final baseplate with glenosphere and humeral stem with chosen polyethylene thickness

Exam Pearl

Final Implantation Pearl: Do not alter plan during final implantation - if instability concern, return to trials and reassess all variables (glenosphere size/lateralization, polyethylene thickness, humeral version)

Final Implant Dangers

Cross-threading of locking screws or glenosphere causes inadequate fixation
Soft tissue interposition prevents seating - must be clear before final impaction

Step 21: Subscapularis Management

If subscapularis quality adequate: repair to lesser tuberosity with transosseous sutures or suture anchors. If deficient: consider leaving unrepaired or tendon transfer

Exam Pearl

Repair Pearl: Reverse TSA function deltoid-dependent, subscapularis repair less critical than anatomic TSA - some surgeons leave unrepaired intentionally in revision setting to preserve external rotation

Subscapularis Dangers

Over-tensioned repair limits external rotation and causes stiffness
Axillary nerve injury during inferior suture passage (most common nerve injury in shoulder arthroplasty)

Step 22: Final Stability Check

Test stability through full passive range of motion on table - should achieve 140+ degrees flexion, 40+ degrees external rotation without dislocation

Exam Pearl

Final Check Pearl: If unstable, most common error is inadequate soft tissue tensioning - thicker polyethylene liner solves most instability issues (8mm, 10mm, 12mm options)

Final Check Dangers

Unrecognized instability leads to early dislocation (20% of revision complications)
Overstuffing joint causes stiffness and potential stress fracture

Complications - Recognition and Management

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 72-year-old presents 3 years after reverse TSA with recurrent anterior dislocations (3 episodes). X-rays show well-fixed components in satisfactory position. How do you assess and manage this patient?"

EXCEPTIONAL ANSWER

This is a recurrent instability scenario requiring systematic assessment and likely revision surgery. Initial evaluation includes detailed history (trauma vs atraumatic, arm position during dislocations), physical examination (soft tissue envelope, deltoid function, external rotation strength suggesting subscapularis status), and advanced imaging. I would obtain CT scan with metal artifact reduction to assess component positioning precisely (baseplate tilt, humeral version, glenosphere size and lateralization), and MRI if possible to evaluate subscapularis integrity. Management options include nonoperative trial with activity modification and strengthening if first occurrence, but with 3 dislocations surgical revision indicated. Revision strategy includes: increase polyethylene liner thickness (from 6mm to 9-12mm increases soft tissue tension), consider lateralized glenosphere if deltoid tensioning inadequate, assess and correct any component malpositioning (excessive baseplate superior tilt causes anterior instability, excessive humeral retroversion causes anterior instability), repair subscapularis if deficient tissue present. Intraoperatively perform comprehensive soft tissue release and trial reduction testing to confirm stability before final implantation. Postoperatively, more prolonged immobilization (8 weeks vs standard 6 weeks) and protected rehabilitation essential to allow soft tissue healing.

VIVA SCENARIOStandard

EXAMINER

"You are called to review a 68-year-old 2 years after reverse TSA with progressive pain and grinding sensation. X-rays show a 3mm radiolucent line around the baseplate with superior screw breakage. What is your diagnosis and management plan?"

EXCEPTIONAL ANSWER

This presentation indicates symptomatic baseplate loosening requiring revision surgery. The radiolucent line >2mm and screw breakage are radiographic criteria for loosening, combined with progressive pain and mechanical symptoms (grinding). Preoperative workup must exclude infection as cause of loosening - obtain inflammatory markers (ESR, CRP), if elevated perform joint aspiration with extended culture hold (48-72 hours minimum), consider labeled WBC scan if aspiration equivocal. CT scan with metal artifact reduction essential to assess glenoid bone stock remaining and plan reconstruction strategy. Surgical plan involves deltopectoral approach (extensile, familiar anatomy), meticulous baseplate removal (sequential screw removal peripheral to central, dedicated extraction tools), thorough debridement of fibrous membrane and sclerotic bone, assessment of bone loss pattern and severity (Nerot-Sirveaux classification). Reconstruction strategy depends on defect: peripheral defects <5mm use larger baseplate or augmented baseplate; central defects 5-10mm consider BIO-RSA technique (structural graft under baseplate fixed with screws through baseplate into native bone); massive defects >10mm may require custom implant with scapular body engagement. Graft source preference autograft iliac crest (best biology) or structural allograft femoral head (adequate structural support). Revision baseplate positioning with 10-15 degrees inferior tilt critical, divergent screw trajectories for maximum fixation, bicortical purchase mandatory. Postoperatively, protected weightbearing of upper extremity for 12 weeks minimum to allow graft incorporation if BIO-RSA performed.

VIVA SCENARIOStandard

EXAMINER

"During revision reverse TSA for instability, you have trialed multiple polyethylene liner thicknesses and still have 1.5cm inferior subluxation with arm traction. Baseplate and humeral component positions appear appropriate. What are your next steps and considerations?"

EXCEPTIONAL ANSWER

This represents persistent instability despite adequate soft tissue tensioning attempts, requiring systematic problem-solving. First, I would verify component positioning is truly appropriate: baseplate should have 10-15 degrees inferior tilt (superior tilt causes instability), version should be neutral to slight anteversion (excessive retroversion causes anterior instability, excessive anteversion causes posterior instability), humeral component version should be 20-30 degrees retroversion (excessive retroversion exacerbates instability). Check glenosphere size and lateralization options - if using standard 36mm sphere, consider upsizing to 42mm sphere or adding lateralization (+4mm or +10mm) which improves deltoid moment arm and soft tissue tensioning. Re-assess subscapularis integrity - if tissue present but not repaired, perform repair to lesser tuberosity with transosseous sutures (improves anterior stability significantly). Consider deltoid deficiency as cause - if deltoid muscle quality poor or denervated (previous axillary nerve injury), may explain inadequate tensioning despite appropriate components. If all optimization attempts fail, options include: accept marginal stability and plan for prolonged immobilization (10-12 weeks) with aggressive activity restrictions long-term, consider constrained liner option (glenosphere with deep capture design), or rarely consider conversion to fusion or hemiarthroplasty with fascial interposition in severe cases. Critical to discuss with patient intraoperatively if under regional anesthesia (awake) or postoperatively regarding compromised expectations and potential for recurrent instability despite best efforts.