Reverse Shoulder Arthroplasty Humeral Lateralisation: A Systematic Review

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Medical Device Design

Background:

• Reverse shoulder arthroplasty (RSA) innovations focus on optimizing humeral component design.
• Previous research explored glenoid variations, but humeral inclination and tray design effects remain less studied.
• Lateralizing the humeral center of rotation (COR) is a key design modification in RSA.

Purpose of the Study:

• To systematically compare the clinical outcomes of lateralized versus medialized humeral components in RSA.
• To evaluate the impact of humeral inclination and onlay/inlay tray designs on RSA results.
• To identify if lateralized humeral designs offer advantages over standard medialized designs.

Main Methods:

• Systematic literature search across medical databases using specific keywords.
• Inclusion of nine studies comparing lateralized to medialized humeral components in adult RSA patients.
• Meta-analysis of data from 562 patients to assess outcomes like scapular notching and range of motion.

Main Results:

• Lateralized humeral components showed a significantly reduced risk of scapular notching compared to medialized components.
• A statistically significant improvement in external rotation range of motion was observed in the lateralized group.
• No apparent downside was noted in patient-reported outcome measures or complication rates for lateralized designs.

Conclusions:

• Lateralized humeral components in RSA appear superior to medialized designs due to reduced scapular notching and improved range of motion.
• The benefits are achieved without negatively impacting patient-reported outcomes or complication rates.
• Further large-scale randomized controlled trials (RCTs) with long-term follow-up are recommended to confirm clinical significance.