Rotator Cuff Arthropathy

Imaging Gallery

Click to expand

Click to expand

Click to expand

Relevant Anatomy

• Coracoacromial Arch: Becomes the new weight-bearing roof of the shoulder. Do NOT violate the CA ligament in CTA surgery (it is the only restraint against escape).
• Glenoid: Can become eroded superiorly ("E2 type wear").
• Subscapularis: Often intact in early stages but if torn, leads to anterior escape.
• Teres Minor: Critical for external rotation. If absent or fatty infiltrated (Hornblower's), a standard Reverse TSA will still result in an arm that cannot externally rotate (Latissimus Dorsi transfer may be added).
• Neurovascular Relations:
  • Axillary Nerve: Runs 5cm distal to the acromion. Travels through the quadrangular space with the posterior circumflex humeral artery.
  • Suprascapular Nerve: Travels through the suprascapular notch (under the transverse ligament) and spinoglenoid notch. Risk of injury during posterior glenoid retraction.
  • Cephalic Vein: The primary landmark for the deltopectoral approach. Preserving it reduces venous congestion.

Imaging Gallery

Click to expand

Click to expand

Click to expand

Reverse Total Shoulder Arthroplasty (rTSA) The workhorse for CTA.

Biomechanics of Grammont Style Reverse

1. Medialization: Moves center of rotation medially. Increases the lever arm of the deltoid (recruits more fibers).
2. Distalization: Moves center of rotation distally. Retensions the deltoid.
3. Constraint: Semi-constrained design provides stability (replaces the cuff's function).

Indications

• CTA with pseudoparalysis.
• Massive unrepairable cuff tear.
• Failed Hemiarthroplasty/Total Arthroplasty.
• Proximal Humerus Malunion/Nonunion.

Contraindications

• Deltoid Paralysis (Axillary nerve injury).
• Active Infection.
• Glenoid Bone Deficiency (unable to hold baseplate screws).

Scapular Notching (Sirveaux Classification) Notching is a unique complication of Reverse TSA where the humeral cup abrades the inferior scapular neck during adduction.

• Grade 1: Defect involving pillar only.
• Grade 2: Defect contacting lower screw.
• Grade 3: Defect extending over lower screw.
• Grade 4: Defect extending to central peg (Threatening fixation).
• Prevention:
  • Lateralization: This is the most effective method.
    • Glenoid Side: Bony-metallic (BIO-RSA) or Metallic lateralization.
    • Humeral Side: Onlay stems or curved stems.
  • Inferior Overhang: Placing the glenosphere inferiorly prevents impingement in adduction.
  • Neck-Shaft Angle:
    • 155 degrees (Grammont original): High rate of notching.
    • 135 degrees (Modern): Reduces notching but increases shear force on the baseplate.

Acromial Stress Fracture

• Pathology: The deltoid is significantly tensioned. In elderly osteopenic patients, this stress can fracture the acromion or scapular spine.
• Diagnosis: Sudden onset pain after doing well for 3 months. X-ray might miss it (requires scapular views/CT).
• Consequence: Catastrophic. The deltoid origin becomes unstable. The "Reverse" stops working.
• Treatment: Conservative (High rate of non-union). ORIF has high failure rate.

Infection (Periprosthetic Joint Infection - PJI)

• Pathogen: Cutibacterium acnes (C. acnes) is the causative organism in over 60% of shoulder PJIs.
  • Biology: Gram-positive, anaerobic, slow-growing bacillus. Commensal on skin, specifically in sebaceous glands (which are dense in the shoulder region).
• Risk Factors: Male gender (more hair/sebum), younger age, prior surgery, topical steroids.
• Presentation: rarely presents with acute sepsis (fever/redness). Typical presentation is aggressive "stiffness" or unexplained "pain" after a period of doing well.
• Diagnosis:
  • Markers: ESR/CRP are often normal in C. acnes infection.
  • Aspiration: Dry taps are common.
  • Cultures: Must be held for minimum 14 days (up to 21 days).
  • Frozen Section: Over 50 PMNs per HPF is suggestive.
• Management:
  • DAIR (Debridement): Poor success rate for C. acnes. Only considered for acute hematogenous spread.
  • Two-Stage Revision: The Gold Standard.
    • Stage 1: Removal of all implants, thorough debridement, placement of antibiotic spacer (high dose Vancomycin/Gentamicin).
    • Antibiotics: 6 weeks of targeted therapy (often includes Rifampin for biofilm).
    • Stage 2: Reimplantation after antibiotic holiday and negative rescreen.

Neurological Injury

• Axillary Nerve: Most at risk during the inferior capsular release or from traction.
• Presentation: Deltid paralysis.
• Prognosis: Most are neurapraxias that resolve.
• Prevention: Identify the nerve. Keep the arm adducted while releasing inferiorly.

• Elevation: Restore active elevation reliably (over 130 degrees).
• Rotation: External rotation is often not restored (0-10 degrees) unless Teres Minor is intact or Lat Dorsi transfer is done.
• Function: Patients can feed themselves and reach top of head, but reaching up back (IR) is limited.

• Trends: The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) reports a massive shift towards Reverse TSA.
  • In 2008, Reverse accounted for under 5% of shoulder replacements.
  • In 2023, Reverse accounts for over 80% of all shoulder arthroplasty for OA (including CTA and Primary OA).
• Reason: The revision rate for Hemiarthroplasty for OA is significantly higher than Reverse TSA. Hemiarthroplasty for cuff deficiency has largely been abandoned in Australia.
• Revision Rates (AOANJRR):
  • Primary Reverse TSA for OA: ~5-6% at 10 years.
  • Common reasons for revision: Infection (most common reason for early revision), Instability, Fracture.
  • Prosthesis Selection: In Australia, uncemented (fixation by screw) metal backed glenoids are the standard for Reverse (unlike Anatomic where cemented poly is standard). The Registry shows no difference between cemented and uncemented humeral stems for Reverse.
• Interactive Data: The "Lifetime Risk of Revision" for a 70 year old male receiving a Reverse TSA is approx 5-8%, meaning it will likely last their lifetime.
• Practice Points:
  • "Try Hemi first" is NO LONGER valid advice for the exam. The evidence (and registry) supports primary Reverse TSA.
  • Metal-backed glenoids in Anatomic TSA had high failure rates in Australia and are largely discouraged, but metal-backed baseplates are the standard for Reverse TSA.

Surgeon Volume and Outcomes

• There is a clear "Volume-Outcome" relationship demonstrated in the AOANJRR. Surgeons performing fewer than 10 shoulder arthroplasties per year have significantly higher revision rates.
• Implication: Shoulder arthroplasty is becoming a subspecialty operation.

Cost-Effectiveness

• Reverse TSA is more expensive than Hemiarthroplasty (implants cost ~2-3x).
• However, when factoring in the high revision rate of Hemi for CTA (conversion to Reverse), primary Reverse TSA is the most cost-effective strategy over a 10-year horizon.

Regional Practice Variations

• Stemless Reverse: Increasing usage in Europe, but slower uptake in Australia pending long-term registry data.
• Computer Navigation / PSI: High uptake in Australia (over 30% of cases). The registry is monitoring whether this reduces the outlier rate for glenoid placement (and thus loosening/notching).