High Yield Overview

REVISION SHOULDER ARTHROPLASTY TO REVERSE

Extended deltopectoral approach | Intermediate complexity

Critical Danger Structures - 5 Key Zones

1. Axillary Nerve

Location: Exits quadrilateral space 5-7cm inferior to lateral acromion, travels around surgical neck

Protection: Stay superior during inferior capsular release, palpate nerve before inferior screw insertion, limit retraction

2. Musculocutaneous Nerve

Location: Enters coracobrachialis muscle 3-8cm distal to coracoid tip, lateral to conjoined tendon

Protection: Avoid aggressive lateral retraction, identify before subscapularis release, protect during humeral exposure

3. Brachial Plexus & Axillary Vessels

Location: Medial to coracoid, deep to pectoralis minor, typically 2-3cm from deltopectoral interval

Protection: Gentle medial retraction only, avoid deep medial dissection, recognize if inadvertent exposure occurs

4. Lateral Cutaneous Nerves

Location: Superficial in deltopectoral fat, proximal and distal branches crossing interval

Protection: Careful subcutaneous dissection, preserve cephalic vein branches, avoid excessive cautery superficially

5. Suprascapular Nerve & Artery

Location: Pass through suprascapular notch posteriorly, 2-3cm from glenoid rim, at risk with posterior baseplate screws

Protection: Limit posterior-superior screw trajectory to 20mm depth, angle screws away from notch, use drill guides

Mnemonic

REVERSE - Indications for Revision to Reverse TSA

Mnemonic

BASEPLATE - Glenoid Component Fixation Principles

Imaging Assessment

CT Scan Analysis (Essential)

Exam Pearl

High-yield: 3D CT reconstruction mandatory for revision cases - assess glenoid bone stock, version, wear patterns, screw trajectories, and plan bone grafting needs.

Key measurements on CT:

Glenoid bone loss volume (Favard classification: E0-E4)
Anterior-posterior dimension (minimum 20mm for standard baseplate)
Superior-inferior height (minimum 25mm)
Version (excessive retroversion necessitates correction)
Scapular anatomy for screw planning

Favard Classification of Glenoid Bone Loss:

E0: Intact bone stock
E1: Centered erosion, minor defect
E2: Superior defect, biconcave pattern
E3: Superior + posterior defect, >25mm loss
E4: Severe global bone loss, <50% intact

Radiographic Evaluation

AP and axillary views assess:

Component loosening (radiolucent lines, component migration)
Tuberosity position and healing
Humeral bone stock and cortical integrity
Acromion morphology and prior fracture
Heterotopic ossification extent

Previous Operative Reports

Critical information:

Original implant manufacturer and model (order extraction instruments)
Fixation method (cemented vs press-fit)
Complications during index procedure
Soft tissue state (subscapularis repair, cuff integrity)

Planning Checklist

Obtain manufacturer-specific extraction tools for humeral component
Have bone graft available (allograft femoral head or distal tibia)
Arrange longer operative time (90-150 minutes typical)
Extended revision instrumentation set (extended stems, augments, bone graft screws)
Cross-match blood products (revision carries higher bleeding risk)

Patient Assessment

Indications for revision to reverse:

Failed anatomic TSA with irreparable rotator cuff tear
Failed hemiarthroplasty with pain and dysfunction
Severe glenoid component loosening with bone loss
Proximal humerus fracture sequelae (tuberosity nonunion, malunion)
Recurrent instability not amenable to revision anatomic TSA

Relative contraindications:

Active infection (requires two-stage with spacer)
Severe glenoid bone loss without grafting option (E4 with <40% stock)
Deltoid dysfunction or axillary nerve palsy
Neuropathic arthropathy
Medical comorbidities prohibiting major surgery

Complications Management

Revision Reverse TSA Complications - Recognition, Prevention, Management

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 68-year-old presents 4 years post-anatomic TSA with progressive pain and weakness. Radiographs show superior glenoid erosion and component loosening. How would you approach this patient?"

EXCEPTIONAL ANSWER

This case represents failed anatomic TSA likely secondary to rotator cuff insufficiency causing superior migration and eccentric glenoid wear - the classic indication for revision to reverse TSA. **Initial Assessment:** I would obtain a thorough history focusing on pain characteristics, functional limitations, and any trauma. Examination should assess active and passive ROM, strength (particularly overhead), and rotator cuff integrity via lag signs and clinical tests. **Imaging Workup:** Standard radiographs (AP, scapular Y, axillary) assess component position, loosening signs, migration patterns, and bone stock. CT scan with 3D reconstruction is essential to quantify glenoid bone loss (Favard classification), assess version, plan screw trajectories, and evaluate humeral bone stock. If infection suspected, obtain ESR/CRP and consider aspiration. **Surgical Planning:** Based on CT showing Favard E2 or E3 bone loss (superior defect), I would plan revision to reverse TSA. Preoperative planning includes ordering manufacturer extraction tools for the humeral component, arranging structural bone graft (femoral head allograft), and having extended revision instrumentation available including augmented baseplates or BIO-RSA options for superior defects. **Surgical Approach:** Extended deltopectoral approach provides excellent visualization for component removal and reconstruction. Key steps include careful humeral component extraction (preserving bone stock), complete glenoid component removal (thin osteotomes peripherally), assessment of bone defect, bone grafting as needed, baseplate fixation with 10-15° inferior tilt and divergent screws, and humeral component reconstruction with appropriate version and joint tension.

VIVA SCENARIOStandard

EXAMINER

"During revision of a failed hemiarthroplasty to reverse TSA, you encounter a well-fixed cemented humeral stem that will not extract easily. What are your options and how would you proceed?"

EXCEPTIONAL ANSWER

This is a common challenging scenario in revision shoulder arthroplasty requiring systematic approach to component removal while preserving bone stock. **Initial Extraction Attempts:** I would first ensure adequate exposure through extended deltopectoral approach with complete soft tissue releases (subscapularis, anterior and inferior capsule carefully protecting axillary nerve). Using manufacturer-specific extraction tools if available, I would attempt gentle extraction through slap hammer technique with progressive small taps rather than large impacts. If the stem has a modular head, I would remove this first to improve access. **Cement Interface Work:** Using thin curved osteotomes, I would work around the proximal cement-bone interface attempting to break the bond. Slot-cutting burr can create a longitudinal trough along the anterior stem to allow instrument access. Ultrasonic cement removal systems (Sontec) can fragment cement without thermal damage but may be slow. **Extended Humeral Osteotomy Decision:** If the above fails and significant force would risk fracture, I would proceed to extended humeral osteotomy which is my definitive technique for well-fixed components. **Extended Osteotomy Technique:** I would plan an anterior longitudinal osteotomy in the proximal third of the humerus, typically 8-10cm length. Using an oscillating saw, I create the anterior window while preserving lateral and posterior cortical continuity (maintains structural integrity). I carefully mark the osteotomy edges with methylene blue or skin marker for anatomic reduction. Through this window, I can directly visualize the cement-bone interface, use curved osteotomes to mobilize the stem, and extract it safely. After extraction and cement removal, I reconstruct the osteotomy with cerclage cables or wires, ensuring stable fixation before proceeding with reverse reconstruction. **Alternative Considerations:** If bone quality is very poor or fracture occurs, I may need to use a longer revision stem that bypasses the compromised bone by at least two humeral shaft diameters. Structural bone graft may be needed for large defects.

VIVA SCENARIOStandard

EXAMINER

"Discuss the glenoid bone grafting options when you encounter severe glenoid bone loss during revision to reverse TSA. What are the indications, techniques, and outcomes for each approach?"

EXCEPTIONAL ANSWER

Severe glenoid bone loss is a common and challenging scenario in revision shoulder arthroplasty. The Favard classification helps guide management - E0/E1 minimal loss proceeds without grafting, E2/E3 often requires grafting, and E4 may be ungraftable. **Indications for Bone Grafting:** I would consider grafting when there is insufficient bone stock for stable baseplate fixation - specifically anterior-posterior diameter less than 20mm, superior bone loss preventing peripheral rim contact, or central cavitary defects greater than 10mm deep. The goal is to restore glenoid anatomy and provide adequate bone for baseplate and screw purchase. **Structural Allograft Technique:** My preferred approach for superior or eccentric defects is structural bone graft using femoral head or distal tibia allograft. I shape the graft to match the defect contour using the trial baseplate as a template. The graft is fixed with 3.5mm or 4.0mm screws achieving compression at the host-graft interface. I then ream the graft flush with native bone to create a uniform surface. The baseplate is fixed with screws engaging both native bone and the graft, distributing forces across the reconstruction. This technique has shown 85-90% graft incorporation rates and good clinical outcomes. **BIO-RSA (Bony-Increased Offset Reverse):** For superior glenoid bone loss, the BIO-RSA is an excellent alternative to bone grafting. This uses an augmented baseplate with a metallic wedge (typically 5-10mm) on the superior aspect, which restores the anatomic glenoid surface without requiring bone graft. Advantages include single-stage surgery, no graft-related complications, and correction of version simultaneously. The augment is typically placed superiorly and allows standard baseplate positioning with inferior tilt. Studies show equivalent outcomes to standard reverse TSA with appropriate indications. **Impaction Bone Grafting:** For contained central defects, I use particulate cancellous allograft or autograft from the humeral head. The graft is impacted into the defect creating a stable bed for central peg purchase. This is suitable for smaller contained defects but not for peripheral rim deficiency. **Salvage Options for E4 Loss:** When bone stock is severely deficient (less than 40% remaining), options are limited. Techniques include double-baseplate constructs, custom implants, or conversion to shoulder arthrodesis/resection arthroplasty as salvage procedures.