Anatomic vs Reverse | Glenoid Component Selection | Outcomes and Complications
- Rotator cuff integrity determines anatomic vs reverse TSA selection
- Glenoid version greater than 15° retroversion may require bone grafting or augmented component
- Reverse TSA relies on deltoid function - deltoid must be intact
- Subscapularis repair critical for anatomic TSA stability and outcomes
- Periprosthetic infection is devastating - 1-2% incidence, requires staged revision
- “Walch classification of glenoid morphology guides component selection (A1, A2, B1, B2, C)
- “Lateralized glenoid designs reduce scapular notching in reverse TSA
- “Metal-backed glenoid components have higher failure rates - all-polyethylene preferred
- “Deltopectoral approach is standard - preserves axillary nerve, allows subscapularis repair
Clinical Imaging
Imaging Atlas
Rotator cuff integrity is KEY. Anatomic TSA requires intact cuff (especially subscapularis and supraspinatus). Reverse TSA for cuff deficiency, massive tears, or cuff tear arthropathy. Preoperative imaging must assess cuff.
Retroversion greater than 15° requires correction. Options include eccentric reaming (up to 10° safe), bone grafting, or augmented components. Excessive reaming risks glenoid fracture or medialization.
Lesser tuberosity osteotomy vs tenotomy. Osteotomy allows bone-to-bone healing, lower failure rate. Repair integrity critical for anatomic TSA - failure leads to instability and poor outcomes.
Semiconstrained design. Medialized center of rotation increases deltoid tension and moment arm. Lateralization reduces scapular notching. Must have functioning deltoid - axillary nerve palsy is contraindication.
| Patient Scenario | Cuff Status | Preferred Implant | Key Pearl |
|---|---|---|---|
| Age under 65, active, primary OA | Intact rotator cuff | Anatomic TSA | Best function and longevity if cuff intact |
| Age over 70, cuff tear arthropathy | Massive irreparable cuff tear | Reverse TSA | 90% good outcomes for CTA, deltoid-powered |
| Young patient, glenoid bone loss | Intact cuff, eccentric glenoid wear | Hemiarthroplasty | Preserves glenoid bone stock, may convert to TSA later |
| Glenoid retroversion greater than 20° | Intact cuff, B2 or C glenoid | Anatomic TSA with bone graft or augment | Excessive reaming risks fracture - correct with graft |
CUFF FAILIndications for Reverse TSA
Hook:When the CUFF FAILs, reverse the shoulder - deltoid takes over!
ABCDWalch Glenoid Classification (for Anatomic TSA)
Hook:A is Anatomic (centered), B is Backward (posterior), C is Crazy retroverted!
SCALDDeltopectoral Approach Layers
Hook:SCALD the shoulder open - Skin to Deep capsule!
Overview and Epidemiology
Total shoulder arthroplasty is the definitive treatment for end-stage glenohumeral arthritis with intact rotator cuff (anatomic) or cuff deficiency (reverse). The decision between anatomic and reverse TSA is critical and based on rotator cuff integrity. Reverse TSA has revolutionized treatment of cuff tear arthropathy and proximal humerus fractures in the elderly; reverse TSA utilisation rose 191% in the USA between 2011 and 2017 (Wagner et al 2020). Glenoid component selection and fixation remain the weak link - glenoid loosening is the most common long-term failure mode.
- Glenohumeral osteoarthritis (primary or secondary)
- Cuff tear arthropathy (reverse TSA)
- Inflammatory arthritis (RA, severe joint destruction)
- Osteonecrosis of humeral head (AVN)
- Acute proximal humerus fracture (reverse, over 70 years old)
- Failed prior surgery (hemiarthroplasty, fixation)
- 63,845 reverse TSAs performed in the USA in 2017 (National Inpatient Sample)
- 103.7% rise in primary shoulder arthroplasty 2011-2017, driven by reverse TSA (191.3% increase)
- Reverse TSA now exceeds anatomic in most registries; AOANJRR reports reverse as the majority of primary shoulder replacements
- Female predominance for primary glenohumeral OA
- Age: mean approximately 70 years
- 10-year survival: design-dependent (see registry and outcomes sections)
Anatomy and Biomechanics
Subscapularis is the anterior dynamic stabilizer - failure after anatomic TSA leads to instability and poor outcomes. Axillary nerve at risk during inferior capsular release (average 7mm from glenoid rim at 6 o'clock). Musculocutaneous nerve enters coracobrachialis 5-8cm distal to coracoid - avoid aggressive medial retraction.
Glenohumeral Joint Anatomy
Glenoid: Pear-shaped, 39mm height, 29mm width (5:4 ratio). Native version 2-10° retroversion. Humeral head 45-55mm diameter, 130° head-shaft angle. Offset center of rotation in anatomic design restores normal kinematics.
Subscapularis: Anterior stability, resists posterior subluxation. Supraspinatus: Superior stabilizer, deltoid synergist. Infraspinatus/teres minor: Posterior stability, external rotation. Massive tears lead to superior migration and CTA.
| Feature | Anatomic TSA | Reverse TSA |
|---|---|---|
| Center of rotation | Lateral, anatomic position | Medialized to glenoid face |
| Motion source | Rotator cuff muscles | Deltoid muscle (cuff-independent) |
| Stability mechanism | Concavity-compression, cuff balance | Semiconstrained design, inherent stability |
| Indications | Intact cuff, concentric OA | Cuff deficiency, CTA, fracture sequelae |
| Range of motion | Near-normal if cuff intact | Limited external rotation, good elevation |
Classification Systems
Walch Glenoid Morphology Classification
| Type | Morphology | Version | Treatment Strategy |
|---|---|---|---|
| A1 | Minor central erosion, concentric | Normal (under 10°) | Standard all-polyethylene component |
| A2 | Major central erosion, deep concentric wear | Normal | May need augmented or thicker component |
| B1 | Posterior subluxation, asymmetric wear | 10-15° retroversion | Eccentric reaming (up to 10° safe) |
| B2 | Biconcave glenoid, severe posterior wear | 15-25° retroversion | Bone graft or augmented component |
| C | Dysplastic, severe retroversion | Over 25° retroversion | Bone graft mandatory or reverse TSA |
Maximum 10° correction with eccentric reaming without unacceptable medialization or glenoid fracture risk. For retroversion greater than 15° (B2 or C), consider bone grafting (autograft or allograft), augmented components, or reverse TSA if cuff-deficient.
Clinical Assessment
History and Examination
- Pain: Location, severity, night pain, functional limitations
- Function: Activities of daily living (ADLs) affected, work limitations
- Prior treatment: PT, injections, prior surgery
- Expectations: Activity demands, occupation, goals
- Medical comorbidities: Diabetes, smoking, immunosuppression
- Active vs passive ROM: Pseudoparalysis suggests cuff tear
- Rotator cuff strength: Lag signs, drop arm, external rotation weakness
- Instability testing: Load and shift, sulcus sign
- AC joint: Tenderness, crossbody adduction pain
- Neurovascular: Axillary nerve (deltoid sensation), radial pulse
Differential Diagnosis of the Painful Stiff/Weak Shoulder
| Condition | Distinguishing Features | Key Imaging | Implication for TSA |
|---|---|---|---|
| Primary glenohumeral OA | Gradual pain/stiffness, intact cuff, posterior joint-line tenderness | Joint-space loss, inferior osteophyte, posterior glenoid wear (Walch) | Classic indication for anatomic TSA if cuff intact |
| Cuff tear arthropathy | Weakness/pseudoparalysis, superior migration, anterosuperior escape | Acromiohumeral distance under 7mm, acetabularised acromion | Indication for reverse TSA, not anatomic |
| Inflammatory arthritis (RA) | Polyarticular, morning stiffness, serology positive, soft-tissue thinning | Symmetric/central erosion, osteopenia, frequent cuff attrition | Often reverse TSA if cuff deficient; bone quality affects fixation |
| Avascular necrosis of humeral head | Steroid/alcohol/sickle history, preserved joint space early | Crescent sign, subchondral collapse, intact glenoid early | Hemiarthroplasty or anatomic TSA depending on glenoid involvement |
| Adhesive capsulitis (frozen shoulder) | Global loss of active AND passive ROM, especially external rotation; normal radiographs | Plain films normal; no arthritis | Not a TSA indication - treat non-operatively |
| Septic arthritis / infection | Acute, systemic signs, raised CRP/ESR, exquisite pain | Effusion, rapid erosion; aspirate positive | Absolute contraindication until eradicated |
Investigations
Imaging Protocol
Preoperative Imaging Workup
True AP, scapular Y, axillary lateral. Assess glenohumeral OA, superior migration (acromiohumeral distance less than 7mm suggests massive cuff tear), glenoid version and wear pattern, bone stock. Obtain contralateral shoulder for comparison.
Assess glenoid version, bone stock, wear pattern (Walch classification). Plan component positioning, identify need for bone graft or augmented component. Measure retroversion (normal 2-10°, B2 glenoid 15-25°, C glenoid over 25°).
Evaluate rotator cuff integrity, fatty infiltration (Goutallier classification). Stage 3-4 fatty infiltration suggests irreparable cuff tear - consider reverse TSA. Assess subscapularis integrity - critical for anatomic TSA.
Absolute: Active infection, deltoid paralysis (axillary nerve palsy for reverse TSA), Charcot arthropathy. Relative: Young age (under 50 for anatomic), high activity demands, uncorrectable glenoid bone loss, severe osteoporosis, noncompliant patient.
Management Algorithm
Anatomic TSA Pathway
Indications: Age under 75, intact rotator cuff (no fatty infiltration), concentric or correctable glenoid wear (Walch A or B1), good bone stock, realistic expectations. Goal: Restore anatomy, preserve cuff function, maximize longevity.
| Walch Type | Version | Treatment | Key Point |
|---|---|---|---|
| A1-A2 (concentric) | Normal (under 10°) | Standard anatomic TSA | Best candidate, excellent outcomes |
| B1 (posterior wear) | 10-15° retroversion | Eccentric reaming (up to 10°) | Safe correction without bone graft |
| B2 (biconcave) | 15-25° retroversion | Bone graft or augmented component | Requires version correction |
Anatomic TSA requires intact subscapularis for anterior stability. Lesser tuberosity osteotomy preferred over tenotomy (lower failure rate). Protect repair for 6 weeks postoperatively.
Surgical Technique
Patient Positioning
Setup Checklist
Beach chair position (30-45° upright) on specialized shoulder positioning system. Head secured in neutral alignment with padded headrest. Contralateral shoulder padded to prevent pressure injury.
- Ulnar nerve: Pad medial elbow, avoid direct pressure
- Brachial plexus: Avoid excessive head rotation or lateral flexion
- Pressure points: Sacrum, heels, occiput all padded
- Position arm: Adducted and internally rotated on mobile arm positioner
- Landmarks exposed: Sternoclavicular joint medially, AC joint, deltoid insertion laterally
- Free drape operative arm to allow full ROM for trial reduction
- C-arm access: Position for AP and axillary views (if needed)
Beach chair preferred for TSA - easier anatomic orientation, better access to glenoid, allows intraoperative ROM assessment. Lateral decubitus used for arthroscopy or if surgeon preference, but glenoid exposure more difficult.
Deltopectoral Approach
Surgical Approach Steps
Landmarks: From coracoid to deltoid insertion (approximately 15cm). Incision in Langer lines (cosmetic). Identify cephalic vein in deltopectoral interval through subcutaneous tissue.
Deltopectoral interval is internervous plane. Retract cephalic vein laterally with deltoid (protects vein from thrombosis). Blunt dissection of areolar tissue. Superior extent: coracoid. Inferior extent: pectoralis major insertion.
Incise clavipectoral fascia lateral to conjoint tendon. Divide superior 1-2cm of pectoralis major tendon if needed for exposure. Tag with suture for later repair.
Palpate bicipital groove - long head biceps tendon landmark for rotator interval. Perform tenotomy or tenodesis (surgeon preference). Tenotomy faster, tenodesis reduces cramping but adds time.
Axillary nerve: Crosses inferior capsule 5-10mm from glenoid rim at 6 o'clock position. At risk during inferior capsular release - stay on bone, retract with Fukuda or similar retractor. Musculocutaneous nerve: Enters coracobrachialis 5-8cm distal to coracoid tip - avoid aggressive medial retraction. Cephalic vein: Thrombosis if damaged - retract laterally with deltoid.
Reverse Total Shoulder Arthroplasty Technique
Reverse TSA Indications
- Cuff tear arthropathy (massive tear with OA)
- Irreparable massive rotator cuff tear with pseudoparalysis
- Failed rotator cuff repair with persistent dysfunction
- Proximal humerus fracture (3-4 part, over 70 years old)
- Failed prior arthroplasty (anatomic TSA with cuff failure)
- Fracture sequelae (nonunion, AVN, malunion with cuff deficiency)
- Inflammatory arthritis (RA) with cuff deficiency
- Tumor resection requiring proximal humerus reconstruction
- Severe glenoid bone loss (Walch C unsuitable for anatomic)
Reverse TSA Biomechanics
| Feature | Effect | Clinical Benefit |
|---|---|---|
| Medialized center of rotation | Increases deltoid tension and moment arm | Compensates for absent cuff, improves elevation |
| Semiconstrained design | Inherent stability without cuff | Allows function despite massive cuff tear |
| Large glenosphere (36-42mm) | Increases contact arc, reduces notching | Better ROM, lower impingement |
| Lateralized glenosphere or humeral offset | Moves COR laterally, reduces notching | Improves external rotation, reduces scapular impingement |
Deltoid paralysis (axillary nerve injury) is absolute contraindication - reverse TSA relies entirely on deltoid function. Active infection, Charcot arthropathy also absolute contraindications. Relative: glenoid bone loss requiring bone grafting, young active patient (under 65), intact cuff (anatomic TSA preferred).
Complications
| Complication | Incidence | Risk Factors | Management |
|---|---|---|---|
| Glenoid loosening (anatomic TSA) | 10-25% at 10 years | Eccentric loading, excessive retroversion, poor cementation | Observation if asymptomatic, revision to reverse TSA if symptomatic |
| Periprosthetic infection | 1-2% (up to 5% in revision) | Diabetes, immunosuppression, prior surgery, long OR time | I&D and component retention if acute (under 4 weeks), staged revision if chronic |
| Instability (anatomic TSA) | 2-5% | Subscapularis failure, component malposition, cuff deficiency | Revision subscapularis repair, liner exchange, convert to reverse TSA |
| Scapular notching (reverse TSA) | 30-60% | Medialized glenosphere, small glenosphere, inferior position | Prevention: lateralization, larger glenosphere, inferior tilt. Observation if asymptomatic. |
| Nerve injury (axillary nerve) | 1-3% | Excessive retraction, inferior capsular release, traction | Observation, EMG at 6 weeks, consider nerve exploration if no recovery at 3-6 months |
| Periprosthetic fracture | 1-2% (higher in osteoporotic bone) | Osteoporosis, trauma, loose component, press-fit stems | ORIF if stable component, revision to longer stem if loose, cerclage if intraoperative |
| Acromial fracture (reverse TSA) | 2-4% | Excessive deltoid tension, osteoporosis, trauma | Observation if nondisplaced, ORIF if displaced with functional deficit |
| Subscapularis failure (anatomic TSA) | 5-10% (higher with tenotomy) | Poor repair, excessive tension, osteoporotic bone, early mobilization | Revision repair if acute, latissimus transfer or convert to reverse if chronic |
Acute (under 4 weeks): I&D with component retention, exchange of modular parts, long-term suppressive antibiotics. Success rate 50-70%. Chronic (over 4 weeks): Two-stage revision gold standard - component removal, antibiotic spacer (6-12 weeks), reimplantation. Success rate 80-90%. Culture-negative infection: Consider biofilm formation, extended culture time, treat empirically.
Postoperative Care and Rehabilitation
Anatomic TSA Rehabilitation Timeline
Pain control: Interscalene block (wear off 12-24 hours), multimodal analgesia (opioids, acetaminophen, NSAIDs). Immobilization: Sling with arm in neutral rotation. Passive ROM: Begin pendulum exercises day 1 if pain controlled. DVT prophylaxis: Chemical (enoxaparin or aspirin) and mechanical (SCDs).
Sling: Continuous for 4-6 weeks (remove for exercises only). Passive ROM only: Forward elevation to 90°, external rotation to 30° in scapular plane. No active ROM (protects subscapularis repair). No lifting, pushing, pulling. PT 2-3 times per week for passive stretching.
Wean sling at 6 weeks if subscapularis healing confirmed (exam, imaging if concern). Begin active-assisted ROM: Pulleys, cane exercises. Isometric strengthening: Gentle scapular stabilizers. Goals: Forward elevation 120-140°, external rotation 40-50°, internal rotation to L5.
Progressive resistance: Therabands, light weights (1-5 lbs). Functional activities: ADLs, light work tasks. Full ROM: Forward elevation 140-160°, external rotation 50-60°, internal rotation to L3. Return to activities: Golf at 4-6 months, swimming at 3-4 months, avoid contact sports.
Active internal rotation prohibited for 6 weeks after anatomic TSA to protect subscapularis repair. Failure to protect leads to 5-10% repair failure rate and anterior instability. Patient education essential - no lifting, pushing, reaching behind back. Sling compliance improves healing.
- No restrictions on elbow/hand immediately
- Lifting: No lifting over 5 lbs for 12 weeks
- Driving: At 6-8 weeks if off narcotics and adequate ROM
- Return to work: Sedentary at 4-6 weeks, manual labor 3-6 months
- Contact sports: Avoid permanently (risk of dislocation or fracture)
- 2 weeks: Wound check, remove sutures/staples, assess ROM
- 6 weeks: Radiographs (AP, axillary, scapular Y), progress to active ROM
- 12 weeks: Clinical and radiographic assessment, full ROM expected
- 6 months, 1 year, 2 years: Long-term surveillance for loosening, wear
- Annual thereafter if asymptomatic
Outcomes and Prognosis
Outcome Measures and Functional Results
| Outcome | Anatomic TSA | Reverse TSA |
|---|---|---|
| Pain relief | Excellent (90-95% significant improvement) | Excellent (90-95% significant improvement) |
| Forward elevation | 140-160° (near-normal if cuff intact) | 120-140° (deltoid-dependent) |
| External rotation | 40-60° (requires intact posterior cuff) | 20-40° (limited by absent cuff) |
| Patient satisfaction | 90-95% | 90-95% |
| 10-year survival | 70-90% (glenoid loosening main failure) | 85-95% (more durable glenoid fixation) |
Anatomic TSA: Unrecognized rotator cuff tear (leads to early failure), subscapularis failure (instability), glenoid loosening (excessive retroversion or eccentric loading). Reverse TSA: Deltoid dysfunction (axillary nerve injury), infection, scapular notching with pain, acromial fracture. Both: Periprosthetic infection, nerve injury, patient noncompliance with rehab.
Registry Data and Long-Term Survival
- Reverse TSA is now the most commonly implanted primary shoulder arthroplasty in Australia
- Reverse TSA carries a lower cumulative revision rate than anatomic TSA at comparable follow-up
- Common revision indications: instability/dislocation, infection, and glenoid component loosening
- Glenoid fixation: cemented all-polyethylene components outperform metal-backed designs
- ASES score: Improve from 30-40 preop to 75-85 postop
- Constant score: Improve from 20-30 to 60-70
- Pain VAS: Improve from 7-8/10 to 1-2/10
- ROM: Forward elevation improve 50-80°, external rotation variable
- Return to sport: 70-80% return to golf/swimming, avoid contact sports
Evidence Base and Key Trials
Walch Classification: Morphologic Study of the Glenoid in Primary Glenohumeral OA
- Serial CT analysis of 113 osteoarthritic shoulders defined three glenoid types: A, B and C
- Type A (centred head, symmetric erosion) 59 percent; Type B (posterior subluxation, asymmetric/posterior wear) 32 percent; Type C (retroversion over 25 degrees, dysplastic) 9 percent
- Posterior subluxation of the humeral head drives asymmetric load and posterior glenoid wear in Type B
- Classification discriminates dysplastic retroversion (Type C) from acquired posterior erosion (Type B)
Grammont Reverse Prosthesis: Design, Rationale and Biomechanics
- Grammont design innovations: large neckless glenosphere and a 155-degree humeral cup medialising and lowering the centre of rotation
- Medialisation minimises torque on the glenoid component and recruits more deltoid fibres as abductors
- Lowering the humerus restores and increases deltoid tension, allowing the deltoid to compensate for a deficient cuff
- External and internal rotation are often not restored; scapular notching and polyethylene wear from cup-on-neck impingement are key concerns
Neer Award 2005: Grammont Reverse Prosthesis in CTA, Fracture Sequelae and Revision
- 45 reverse prostheses (21 cuff tear arthropathy, 5 fracture sequelae, 19 failed arthroplasty), mean follow-up 40 months
- Active elevation improved from 55 to 121 degrees and Constant score from 17 to 58; active external rotation essentially unchanged (7 to 11 degrees)
- Complications far higher in revision than primary CTA (47 percent vs 5 percent); 22 percent required further surgery
- Scapular notching in 68 percent; teres minor atrophy/fatty infiltration predicted poorer external rotation and function
Scapular Notching in Reverse Shoulder Arthroplasty (Multicentre)
- 337 reverse shoulder arthroplasties; scapular notching present in 62 percent at mean 47 months
- Notching frequency and extent correlated with length of follow-up
- More notching with cuff tear arthropathy, grade 3-4 infraspinatus fatty infiltration, narrowed acromiohumeral distance and superiorly oriented glenoids
- Anterosuperior approach and high/superiorly tilted baseplate positioning increased notching; notching correlated with humeral and glenoid radiolucent lines
Subscapularis Integrity After Lesser Tuberosity Osteotomy vs Tenotomy/Peel
- 60 TSAs compared (32 subscapularis takedown without LTO, 28 lesser tuberosity osteotomy) with ultrasound, radiographs and validated scores
- All LTO tendons were sonographically normal; 4 non-LTO tendons were abnormal (3 attenuated, 1 ruptured)
- Patients with an abnormal subscapularis on ultrasound had significantly worse WOOS and DASH scores and reduced belly-press strength
- After adjusting for follow-up, WOOS favoured LTO (91.5 vs 82.1) though not clinically significant
Incidence and Future Projections of Shoulder Arthroplasty (USA)
- National Inpatient Sample 2011-2017: primary shoulder arthroplasty rose 103.7 percent
- Reverse TSA increased 191.3 percent, with 63,845 reverse procedures performed in 2017
- Shoulder arthroplasty growth outpaces both total hip and total knee arthroplasty
- Projections estimate 174,810 (linear) to 350,558 (Poisson) shoulder arthroplasties annually by 2025
Anatomic Shoulder Arthroplasty in Patients Aged 50 or Younger (Minimum 15-Year Follow-up)
- Long-term Mayo Clinic series of Neer hemiarthroplasty and TSA in patients aged 50 or younger, minimum 15-year follow-up
- Estimated TSA survival 97 percent at 10 years and 84 percent at 20 years (hemiarthroplasty 82 percent and 75 percent respectively)
- Glenoid periprosthetic lucency seen in 76 percent of TSAs; glenoid erosion in 72 percent of hemiarthroplasties
- Marked durable pain relief and improved motion, but high rates of unsatisfactory result ratings in this young cohort
AOANJRR National Joint Replacement Registry: Shoulder Arthroplasty
- Reverse TSA is now the most commonly performed primary shoulder arthroplasty in Australia
- Lower cumulative revision rate for reverse TSA than for anatomic TSA at comparable follow-up
- Leading revision causes include instability/dislocation, infection, and glenoid component loosening
- Cross-linked and cemented glenoid components and stemmed designs tracked for differential revision risk
Exam Viva Scenarios
Practise clinical reasoning and management decisions out loud
“A 72-year-old retired teacher presents with 2-year history of progressive right shoulder pain and weakness. Unable to lift arm above shoulder height. Examination: forward elevation 70° active, 110° passive. Positive lag signs for supraspinatus and infraspinatus. XR shows superior migration of humeral head with acromiohumeral distance 4mm, glenohumeral joint space narrowing. MRI shows massive retracted rotator cuff tear with stage 3 Goutallier fatty infiltration of supraspinatus and infraspinatus. What is your diagnosis and management?”
“You are planning an anatomic TSA for a 65-year-old with primary glenohumeral OA. Preoperative CT shows Walch B2 glenoid morphology with 18° of retroversion and biconcave wear pattern. MRI confirms intact rotator cuff. Walk me through your approach to managing this glenoid morphology.”
“A 68-year-old presents 6 months after anatomic TSA with 3 weeks of increasing shoulder pain, swelling, and low-grade fever. Wound healed primarily. Exam shows warmth, effusion, painful ROM. ESR 65, CRP 45. Aspiration grows coagulase-negative Staph. How do you manage this patient?”
MCQ Practice Points
Q: What is the Walch classification system for glenoid morphology in primary glenohumeral osteoarthritis? A: Walch classification assesses glenoid wear pattern and version to guide component selection. A1: Minor concentric erosion, normal version (best candidate for standard component). A2: Major concentric erosion (may need thicker component). B1: Posterior subluxation with asymmetric wear, 10-15° retroversion (eccentric reaming up to 10° safe). B2: Biconcave glenoid with severe posterior wear, 15-25° retroversion (requires bone graft or augmented component). C: Dysplastic with over 25° retroversion (bone graft mandatory or consider reverse TSA).
Q: What are the key biomechanical principles of reverse total shoulder arthroplasty? A: Reverse TSA creates a semiconstrained ball-and-socket design with inverted anatomy (glenosphere on glenoid, concave cup on humerus). Medialized center of rotation increases deltoid tension and moment arm, allowing elevation despite absent rotator cuff. Deltoid becomes prime mover replacing cuff function. Design is inherently stable without requiring cuff balance. Lateralization (lateralized glenosphere or humeral offset) reduces scapular notching and improves external rotation. Functioning deltoid (axillary nerve intact) is essential - deltoid paralysis is absolute contraindication.
Q: What is the preferred glenoid component design for anatomic TSA and why? A: All-polyethylene cemented glenoid components are gold standard with 70-90% survivorship at 10-20 years. Metal-backed glenoid components have significantly higher failure rates due to polyethylene dissociation, increased wear from thin polyethylene, and osteolysis - they are no longer recommended. Cemented fixation with keel or pegged designs provides durable fixation. Keel designs easier to insert, pegged designs may offer better cement interdigitation. Pressurization of cement into cancellous bone is critical for fixation strength.
Q: Compare lesser tuberosity osteotomy versus subscapularis tenotomy for anatomic TSA. A: Lesser tuberosity osteotomy: Preserves subscapularis insertion on bone fragment, allows bone-to-bone healing (6-8 weeks), lower failure rate (under 5%), better strength restoration. More technically demanding, risk of fracture or nonunion. Subscapularis tenotomy: 5mm medial to insertion, faster, easier exposure and repair. Tendon-to-bone healing (variable), higher failure rate (5-10%), longer protection (12 weeks). Subscapularis failure leads to anterior instability and poor outcomes after anatomic TSA, making secure repair critical.
Q: What is the most common long-term complication of anatomic TSA and how is it managed? A: Glenoid loosening occurs in 10-25% of patients at 10 years (radiographic), with 5-10% requiring revision. Caused by eccentric loading, excessive retroversion, poor cementation, or component malposition. Presents with recurrent pain and functional decline. Management: Observation if asymptomatic with stable component, revision to new glenoid component if symptomatic and bone stock adequate, conversion to reverse TSA if bone loss or rotator cuff failure develops. Prevention through proper version correction, cemented all-polyethylene components, and balanced soft tissues.
Q: What are the key findings from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) regarding shoulder arthroplasty? A: AOANJRR data show that reverse TSA is now the most commonly implanted primary shoulder arthroplasty in Australia and carries a lower cumulative revision rate than anatomic TSA at comparable follow-up. The leading revision indications are instability/dislocation, infection and glenoid component loosening. Cemented all-polyethylene glenoid components have lower revision rates than metal-backed designs in anatomic TSA. Registry data are observational and guide implant selection and patient counselling.
Guidelines, Registries & Global Practice
Global Epidemiology
- USA: primary shoulder arthroplasty rose 103.7% from 2011-2017; reverse TSA rose 191.3% with 63,845 reverse procedures in 2017 (Wagner et al 2020)
- Shoulder arthroplasty is growing faster than hip or knee arthroplasty
- Projected 174,810-350,558 annual procedures in the USA by 2025
- Reverse TSA is now the most common shoulder replacement in most national registries (AOANJRR, NJR, AJRR)
- Ageing populations with cuff tear arthropathy and proximal humeral fractures
- Broadening reverse TSA indications (massive cuff tear, fracture, revision, tumour)
- Improved implant longevity and surgeon familiarity
- Shift away from hemiarthroplasty for glenohumeral OA and acute fracture
Guideline and Registry Positions
| Body / Source | Position on TSA | Evidence basis |
|---|---|---|
| AAOS (American Academy of Orthopaedic Surgeons) | Supports anatomic TSA for end-stage glenohumeral OA with intact cuff and reverse TSA for cuff-deficient/CTA patterns; emphasises individualised indication | Clinical practice guideline / appropriate-use criteria (moderate to limited evidence) |
| NICE / BOA (UK) | Shoulder replacement recommended for severe, refractory glenohumeral arthritis; cuff status determines anatomic vs reverse; registry submission encouraged | Guideline plus National Joint Registry (NJR) surveillance |
| AO Foundation | Reverse TSA favoured for displaced 3-4 part proximal humeral fractures in older patients over ORIF/hemiarthroplasty where cuff/tuberosity healing is unreliable | Expert consensus and comparative cohort data |
| EFORT / European societies | Endorse reverse TSA as standard for CTA and increasingly for fracture; highlight scapular notching and baseplate position as key technical issues | Consensus statements and registry data |
| Registries (AOANJRR / NJR / AJRR) | Track reverse versus anatomic revision risk; consistently favour all-polyethylene cemented glenoids over metal-backed in anatomic TSA | Population-level observational registry data |
National joint registries (AOANJRR, England/Wales NJR, American AJRR) consistently show: (1) reverse TSA is now the most commonly implanted shoulder arthroplasty; (2) metal-backed glenoid components have higher revision rates than cemented all-polyethylene designs in anatomic TSA; and (3) leading revision causes are instability/dislocation, infection and glenoid loosening. Registry data are observational and complement, rather than replace, randomised evidence.
Practice Variation
- Fracture management: higher reverse TSA use for elderly proximal humeral fractures in North America/Europe than in some Asian and lower-resource settings
- Glenoid fixation: near-universal cemented all-polyethylene in anatomic TSA; uncemented/hybrid use varies by region and implant availability
- Augments vs bone graft for B2/B3 glenoids varies with access to patient-specific instrumentation and augmented components
- Quantified risks to discuss: infection (1-2%), nerve injury (1-3%), instability (2-5% anatomic), glenoid loosening (radiographic 10-25% at 10 years anatomic), revision (single-digit percent at 10 years)
- Document: rotator cuff integrity (MRI), glenoid morphology (Walch on CT), and component-selection rationale
- Australian context: TGA-approved implants; AOANJRR submission supports device surveillance; counsel on funding pathway (public vs private gap)
Key documentation requirements: Preoperative imaging assessment (XR, CT with version measurement, MRI for cuff assessment), informed consent with specific complications discussed (infection, nerve injury, loosening, instability, limited ROM especially external rotation in reverse), component selection rationale (anatomic vs reverse, glenoid design, version correction strategy), intraoperative findings (cuff integrity, bone quality, component positioning), postoperative instructions (sling compliance, ROM restrictions, PT protocol). Common litigation issues: Unrecognized rotator cuff tear leading to early anatomic TSA failure (failure to obtain MRI preoperatively), nerve injury from excessive retraction, infection from inadequate prophylaxis or contamination, subscapularis failure from inadequate repair or early mobilization, wrong implant selection (anatomic when reverse indicated). Protective measures: Thorough preoperative assessment with appropriate imaging, detailed consent process, meticulous surgical technique with nerve protection, careful component selection based on cuff integrity and glenoid morphology, clear postoperative instructions and compliance monitoring.
Key Decision Points
- Rotator cuff integrity determines anatomic (intact cuff) vs reverse TSA (cuff deficiency)
- Walch B2/C glenoid (retroversion over 15°) requires bone graft or augmented component
- Deltoid must be intact for reverse TSA - axillary nerve palsy is absolute contraindication
- All-polyethylene cemented glenoid is gold standard (metal-backed abandoned)
Walch Glenoid Classification
- A1 = minor concentric erosion, normal version (best candidate)
- A2 = major concentric erosion (thicker component)
- B1 = posterior subluxation 10-15° retroversion (eccentric reaming safe)
- B2 = biconcave 15-25° retroversion (bone graft or augment needed)
- C = dysplastic over 25° retroversion (graft mandatory or reverse TSA)
Surgical Approach Pearls
- Deltopectoral approach: retract cephalic vein laterally with deltoid
- Axillary nerve 5-10mm from glenoid rim at 6 o'clock - protect during capsular release
- Lesser tuberosity osteotomy has lower failure rate (under 5%) vs tenotomy (5-10%)
- Eccentric reaming safe to 10° correction - beyond requires bone graft or augment
Reverse TSA Specifics
- Semiconstrained design with medialized center of rotation - deltoid powered
- Lateralized glenosphere reduces scapular notching (30-60% incidence)
- External rotation limited 20-40° due to absent posterior cuff - counsel preop
- Earlier mobilization safe than anatomic (no cuff repair to protect)
Complications and Management
- Glenoid loosening (10-25% at 10 years anatomic) - observation vs revision to reverse
- Periprosthetic infection (1-2%): acute (under 4 weeks) = I&D, chronic = staged revision
- Subscapularis failure (5-10%) leads to instability - lesser tuberosity osteotomy preferred
- Scapular notching (30-60% reverse TSA) usually asymptomatic - prevent with lateralization
Key Evidence and Outcomes
- 10-year survival: 70-90% anatomic TSA, 85-95% reverse TSA
- 90-95% patient satisfaction and pain relief for both types
- Reverse TSA is now the most common shoulder arthroplasty (AOANJRR registry data)
- Scapular notching linked to high baseplate position/superior tilt; place glenosphere low (Levigne/Walch multicentre)