The reverse shoulder prosthesis was developed to address issues encountered while treating end stage glenohumeral arthritis in the setting of rotator cuff deficiency. Indications have since expanded to address multiple pathologies of the shoulder.
17 Reverse Total Shoulder Arthroplasty
I. Indications 1
Cuff tear arthropathy (Hamada classification; ▶ Fig. 17.1 ):
Degenerative changes associated with massive rotator cuff tears
Attempting anatomic replacement in the setting of massive rotator cuff tears leads to failure.
Rocking horse phenomenon (▶ Fig. 17.2 ):
Loss of centralization of the humeral head results in eccentric wear and early failure.
Massive rotator cuff tear with minimal to no arthritis:
Anterior superior escape
There may be improvement in range of motion (ROM) but may not return to full.
Failed rotator cuff repair
Proximal humeral fractures
Revision of anatomic shoulder arthroplasty/hemiarthroplasty
Instability or chronic dislocations
In the United States and Australia more than 50% of reverse arthroplasties are done for arthritis and fracture. In the UK, the majority are done for cuff tear arthropathy including massive rotator cuff tears. 4
II. Contraindications 1
Axillary nerve injury/damage
Glenoid vault deficiency precluding baseplate fixation.
Traumatic versus atraumatic
Degree of pain and dysfunction (perceived weakness, instability)
Functional demands and expectations
Ambulation status (use of assistive devices)
Neck pain, alternative origins of pain.
Passive, active motion
Evaluate rotator cuff, scapulothoracic motion, lag signs
Painless weakness is likely neurologic in origin 5
Hornblower’s sign: Indicates torn teres minor and will likely need tendon transfer to regain full motion.
Grashey and axillary at minimum (▶ Fig. 17.3 ).
Computed tomography (CT):
Evaluate glenoid version, humeral and glenoid bone stock, alignment, and rotator cuff atrophy.
Magnetic resonance imaging (MRI):
Evaluate glenoid version, humeral and glenoid bone stock, alignment, and rotator cuff atrophy
Typically CT or MRI is used. Both modalities are usually not necessary.
Subscapular repair based on implant selection.
Split the deltoid
Exposure, glenosphere tilt, axillary nerve injury
Can lead to improved stability as not violating the subscapularis if intact. 6
Medialized center of rotation (COR) (at the glenoid–component interface)
Decreased shear force on the glenoid–component interface
Encroachment on the glenoid → scapular notching
Less mechanical advantage
Laxity of intact rotator cuff.
Still medial to the anatomic COR, just less so than the Grammont style
More than a hemisphere
Address the issues associated with medialized components
Less scapular notching
Improved soft tissue tensioning → Increased compressive forces → Decreased instability
More force across the glenoid–component interface.
Neck shaft angle (NSA) (▶ Fig. 17.6 ):
More horizontal NSA:
Decreased scapular notching
Increased contact stress → Increased wear
iImproved adduction, external rotation, and extension. 7
Avoid superior tilt
Inferior positioning can decrease scapular notching
Use glenoid center line as reference
Use larger glenosphere for instability.