Background
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In 1983, Charles Neer, Craig, and Fukuda described cuff tear arthropathy as a distinct clinical entity.
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It represents a form of degenerative arthritis associated with long-standing, massive rotator cuff tears.
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Loss of rotator cuff function results in superior migration of the humeral head.
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Progressive superior migration leads to:
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Superior glenoid erosion
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Acromial wear
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Conventional anatomic total shoulder arthroplasty fails in this setting due to early glenoid component loosening.
Clinical Features of Cuff Tear Arthropathy
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Chronic shoulder pain associated with weakness.
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Markedly reduced active range of motion with near-normal passive motion.
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Crepitus during shoulder movement.
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Pseudoparalysis, particularly of forward elevation.
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Occasionally, large subdeltoid effusions.
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Forward elevation is significantly limited.
Radiographic Features
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Superior migration of the humeral head.
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Formation of an acromiohumeral pseudoarticulation.
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Loss of normal glenohumeral joint space.
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Erosion of the superior glenoid and the undersurface of the acromion.
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Variable patterns of degenerative change.
Historical Treatment Approaches
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Hemiarthroplasty was the standard treatment before the development of reverse total shoulder arthroplasty.
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It provided reliable pain relief.
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It failed to restore active forward elevation.
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It did not correct the altered biomechanics of a cuff-deficient shoulder.
Indications for Reverse Total Shoulder Arthroplasty
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Nonfunctional or irreparable rotator cuff.
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Cuff tear arthropathy.
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Pseudoparalysis due to massive rotator cuff tear without established arthritis.
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Multiple failed rotator cuff repairs with associated instability.
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Three- or four-part proximal humeral fractures in elderly patients.
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Proximal humeral nonunions and tuberosity malunions.
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Failed shoulder arthroplasty associated with rotator cuff insufficiency.
Ideal Patient Selection
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Intact and functioning deltoid muscle.
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Adequate glenoid bone stock to permit secure baseplate fixation.
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Absence of active infection.
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No severe neurologic disorders such as Parkinson disease, Charcot joint, or syringomyelia.
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Functional demands compatible with implant longevity.
Contraindications
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Absent or nonfunctional deltoid muscle.
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Severe glenoid bone loss precluding stable baseplate fixation.
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Active infection.
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Relative contraindication: limited surgeon experience with the procedure.
Age Considerations
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Historically avoided in patients younger than seventy years.
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Current practice accepts use in selected younger patients with end-stage pathology.
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Outcomes are influenced more by indication than by age alone.
Biomechanics of Reverse Total Shoulder Arthroplasty
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Reverses the normal ball-and-socket configuration of the shoulder.
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Medializes and distalizes the center of rotation.
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Converts the shoulder into a deltoid-powered joint.
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Prevents superior migration of the humerus during deltoid contraction.
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Creates a semiconstrained fulcrum to allow shoulder elevation.
Glenoid Fixation Considerations
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High shear stresses are transmitted across the glenoid baseplate.
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Accurate baseplate positioning is essential.
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The inferior screw experiences the highest shear forces.
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Optimal fixation is achieved by engaging dense cortical bone in:
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The coracoid base
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The inferior scapular pillar
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The scapular spine
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Lateralized Center of Rotation
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Increases the bending moment at the glenoid–implant interface.
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Still allows secure fixation when properly implanted.
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Reduces the incidence of scapular notching.
Glenoid Wear Patterns
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Glenoid wear is common in cuff-deficient shoulders.
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Recognized patterns include:
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Posterior wear
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Superior wear
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Global wear
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Anterior wear
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These patterns influence surgical technique and screw trajectory.
Management of Glenoid Deficiency
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Use of alternative center-line screw placement along the scapular spine.
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Bone grafting when required.
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Use of larger glenospheres.
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Availability of augmented glenoid components.
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Clinical outcomes are comparable to those achieved in patients with normal glenoid bone stock.
Overall Outcomes of Reverse Total Shoulder Arthroplasty
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Clinical results vary depending on indication.
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Posttraumatic and revision cases show inferior outcomes.
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Absence or fatty infiltration of the teres minor muscle negatively affects results.
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Good to excellent outcomes are reported in approximately sixty-seven to eighty-two percent of patients.
Functional Outcomes
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Significant improvement in pain scores.
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Average postoperative forward elevation ranges from one hundred to one hundred thirty-eight degrees.
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Many patients return to medium- and high-demand daily activities.
Implant Survivorship
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Approximately ninety percent at ten years.
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Approximately eighty-seven percent at fifteen years.
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Glenoid component survivorship is approximately eighty-four percent.
Reverse Total Shoulder Arthroplasty for Cuff Tear Arthropathy
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Provides excellent pain relief in most patients.
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Marked improvement in active forward elevation.
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High incidence of scapular notching.
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Scapular notching typically does not correlate with implant loosening.
Comparative Outcomes
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Reverse total shoulder arthroplasty is superior to hemiarthroplasty for cuff tear arthropathy.
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Primary reverse total shoulder arthroplasty performs better than revision procedures.
Rotator Cuff Dysfunction Without Arthritis
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Represents an expanded indication.
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Demonstrates good mid- to long-term functional improvement.
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Associated with higher complication rates, approximately twenty percent.
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Implant survivorship is approximately ninety percent at four years.
Proximal Humeral Fractures in the Elderly
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Particularly useful for comminuted three- and four-part fractures.
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Average postoperative forward elevation is approximately one hundred degrees.
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High incidence of scapular notching.
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Meta-analyses demonstrate superiority over hemiarthroplasty.
Rheumatoid Arthritis with Rotator Cuff Tear
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Improves pain and shoulder function.
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Scapular notching occurs in approximately one-quarter of patients.
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Low rates of component loosening.
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Increased risk of intraoperative and postoperative fractures.
Salvage and Revision Arthroplasty
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Inferior outcomes compared with primary reverse total shoulder arthroplasty.
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Useful following failed arthroplasty or infection.
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Patient satisfaction remains high, approximately ninety percent.
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Risk of loss of motion if preoperative forward elevation exceeds ninety degrees.
Complications
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Scapular notching.
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Instability.
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Infection.
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Periprosthetic fracture.
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Glenoid component loosening.
Surgical Approach
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Proximal humeral exposure is similar to standard shoulder arthroplasty.
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The deltopectoral approach is preferred due to versatility and extensile exposure.
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A superior approach may be used but is less adaptable.
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Adequate exposure of both the humerus and glenoid is mandatory.
Key Differences in Humeral Preparation
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A larger humeral head cut is often required due to superior subluxation.
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Proximal humeral migration is common in cuff-deficient shoulders.
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Bone resection must restore appropriate deltoid tension without overlengthening.
Humeral Stem Version
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Retroversion between twenty and thirty degrees is commonly used.
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Thirty degrees of retroversion is preferred by many surgeons.
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Increased retroversion reduces the risk of instability in adduction and extension.
Humeral Stem Fixation
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Early designs used cemented stems.
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Modern uncemented and short stems demonstrate favorable outcomes.
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Stem choice depends on bone quality, fracture pattern, and surgeon preference.
Glenoid Preparation and Baseplate Placement
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Complete debridement of the glenoid vault until all four borders are visible.
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Identification of the true glenoid center.
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Starting point shifted one to two millimeters inferiorly to reduce scapular notching.
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Inferior edge of the baseplate should be flush with the inferior glenoid.
Guide Pin Placement and Reaming
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Guide pin inserted with ten to fifteen degrees of inferior tilt.
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Inferior tilt reduces scapular notching and improves longevity.
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Reaming continues until the “smiley face” sign is achieved:
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Bleeding cancellous bone inferiorly
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Sclerotic bone superiorly
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Glenosphere and Final Assembly
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Morse taper must be thoroughly dried.
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Glenosphere is securely impacted and stability confirmed.
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Humeral components are trialed to assess stability, motion, and deltoid tension.
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Slight increase in deltoid tension is acceptable.
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Overlengthening must be avoided to prevent wound problems and acromial or scapular spine fractures.
Subscapularis Management
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The role of subscapularis repair remains controversial.
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Some studies show no clear relationship between repair and outcome.
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Repair may improve stability in medialized designs.
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Likely less critical in lateralized reverse total shoulder arthroplasty designs.
Key Surgical Pearls
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Inferior baseplate placement and inferior tilt are essential to minimize scapular notching.
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Avoid excessive deltoid lengthening.
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Glenoid fixation quality is the primary determinant of long-term implant survival.
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Thorough trialing is critical before final implantation.
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