Humeral offset as a predictor of outcomes after reverse shoulder arthroplasty

Area of Science:

• Orthopedic surgery
• Biomechanics
• Arthroplasty

Background:

• Reverse shoulder arthroplasty (RSA) is a common procedure for shoulder joint issues.
• The Grammont-style RSA typically medializes and distalizes the center of rotation.
• Lateralized designs are increasingly used, but their impact is debated.

Purpose of the Study:

• To investigate the relationship between changes in humeral offset (HO) and outcomes after RSA.
• To determine if lateralized HO correlates with improved range of motion (ROM), patient-reported outcomes (PROs), and fewer complications.

Main Methods:

• Retrospective review of 104 patients (109 shoulders) who underwent primary RSA.
• Measurement of preoperative and postoperative humeral offset (HO) using Grashey radiographs.
• Analysis of range of motion (ROM), Subjective Shoulder Value (SSV), ASES scores, and complication rates.

Main Results:

• RSA significantly improved forward elevation, external rotation, SSV, and ASES scores.
• Postoperative HO was medialized in 63 shoulders and lateralized in 46.
• Lateralized HO showed significantly greater improvement in external rotation (ER) compared to medialized HO.

Conclusions:

• RSA improves ROM and PROs irrespective of HO.
• Restoring or lateralizing HO may be beneficial for enhancing ER and reducing complications post-RSA.