What is a Reverse Total Shoulder Arthroplasty?
A reverse total shoulder arthroplasty (RTSA) is a shoulder replacement that inverts the normal anatomy by placing a metal ball (glenosphere) on the glenoid socket and a cup-shaped component on the humerus, allowing the deltoid muscle to power shoulder movement when the rotator cuff is deficient or absent. 1
Anatomical Design
The key distinguishing feature of RTSA compared to conventional total shoulder arthroplasty is the reversal of the ball-and-socket relationship:
Normal anatomy preservation in conventional arthroplasty: A standard total shoulder replacement maintains the natural configuration with a ball on the humeral head and a socket on the glenoid, requiring an intact rotator cuff for stabilization and active motion 1
Reversed anatomy in RTSA: The glenoid component consists of a round metal ball (glenosphere) attached to a baseplate on the glenoid surface, while the humeral component has a cup-shaped articular margin secured by a metal stem 2
Biomechanical advantage: This construct moves the center of rotation medially and distally, which allows the deltoid muscle to serve as the main stabilizer of the joint and compensate for rotator cuff deficiency 2, 1
Additional benefit: The more medial and distal center of rotation decreases the risk of glenoid loosening compared to conventional arthroplasty 2
Primary Clinical Indications
RTSA was originally introduced in 1987 as a treatment option for patients with deficient rotator cuffs 2:
Massive, unrepairable rotator cuff tears with pseudoparalysis: RTSA is recommended for patients who have failed other treatments and demonstrate preserved deltoid contraction but loss of active elevation 1, 3
Rotator cuff tear arthropathy: This combination of massive rotator cuff tear and glenohumeral arthritis is a primary indication 1, 4
Failed conventional arthroplasty: RTSA serves as a salvage procedure for patients with failed total shoulder arthroplasties 2
Proximal humerus fractures: RTSA has replaced hemiarthroplasty as the implant of choice for displaced three- and four-part proximal humerus fractures in elderly patients 5
Absolute Contraindications
Severely impaired deltoid function is an absolute contraindication to RTSA, as the deltoid must power shoulder motion in the absence of rotator cuff function. 1, 3
Additional contraindications include:
Isolated supraspinatus tear: RTSA is not indicated when only the supraspinatus is torn 3
Full active shoulder elevation preserved: The presence of full active shoulder elevation with a massive rotator cuff tear and arthritis is a contraindication 3
Young age concerns: Age is a significant consideration, with potential risks of increased prosthetic loosening and decreased survivorship in patients under 50 years 1, 6
Common Complications
The complication profile differs from conventional arthroplasty:
Scapular notching: This is the most common complication specific to RTSA 1, 6, and its presence on postoperative radiographs has been associated with poor clinical outcomes 2
Comparison to conventional arthroplasty: While glenoid loosening is the most common complication of regular total shoulder replacement (14.3% of cases), RTSA has different failure patterns 1
Other complications: Include dislocation, periprosthetic fractures, glenoid baseplate failure, and acromial fractures 6
Acromion and scapular spine fractures: These are more common with RTSA than conventional arthroplasty and are thought to be related to intraoperative complications or chronic stress 2