Metallic Lateralized-Offset Glenoid Reverse Shoulder Arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Arthroplasty

Background:

• Metallic lateralized-offset reverse shoulder arthroplasty (RSA) utilizes an augmented baseplate and short stem for improved humeral lateralization.
• Lateralization of the center of rotation reduces scapular notching and enhances prosthetic stability and range of motion.
• Metallic increased-offset RSA (MIO-RSA) corrects deformities without graft resorption, unlike bony increased-offset RSA (BIO-RSA).

Purpose of the Study:

• To describe the technique and rationale for metallic lateralized-offset reverse shoulder arthroplasty (MIO-RSA).
• To highlight the advantages of MIO-RSA over traditional methods like BIO-RSA.
• To present the expected outcomes and critical surgical tips for MIO-RSA.

Main Methods:

• The procedure involves a deltopectoral approach, humeral head resection, glenoid preparation, and implantation of a lateralized augmented baseplate and eccentric glenosphere.
• Humeral preparation includes metaphyseal compaction for stem alignment and insertion of a definitive short stem with an asymmetric polyethylene.
• Key steps include subscapularis tenotomy, capsular release, osteotomy, and final implant assembly with stability and range of motion assessment.

Main Results:

• Studies show MIO-RSA achieves excellent clinical results, including improved shoulder function, pain relief, and muscle strength.
• Bipolar metallic lateralized RSA demonstrates no instability or signs of scapular notching.
• MIO-RSA shows higher rates of complete baseplate seating compared to BIO-RSA, with fewer complications related to bone graft resorption.

Conclusions:

• MIO-RSA is an effective strategy for achieving lateralization and correcting multiplanar defects in reverse shoulder arthroplasty.
• This technique offers a viable alternative to BIO-RSA, especially when bone grafting is not feasible or desirable.
• MIO-RSA provides excellent clinical outcomes, stability, and range of motion, reducing complications associated with other methods.