Humeral component retroversion in the Comprehensive Reverse Shoulder System arthroplasty: rotations, clinical...

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Musculoskeletal Research

Background:

• Humeral retroversion is a key factor influencing shoulder rotation after reverse total shoulder arthroplasty (rTSA).
• Previous studies suggest a link between increased retroversion and altered rotation, but randomized trials are lacking.
• Optimal humeral retroversion for maximizing rotational mobility in rTSA remains undetermined.

Purpose of the Study:

• To determine the optimal humeral retroversion (0°-30°) for achieving the best rotational mobility in rTSA.
• To analyze shoulder mobility, clinical functional scores, and quality of life after lateralized rTSA implantation.
• To compare outcomes between 0° and 30° humeral retroversion in rTSA patients.

Main Methods:

• A single-blinded randomized controlled trial involving patients undergoing rTSA with either 0° (intervention) or 30° (control) humeral retroversion.
• Consecutive enrollment at a single institution from 2019-2022 with a 2-year follow-up.
• Assessment of range of motion (ER1, ER2, functional IR, IR2, anterior elevation, abduction) and functional outcomes (Constant-Murley, ASES, SST, SF-12).

Main Results:

• At 24 months, 30° retroversion showed significantly improved mean ER1 (50° vs. 38°, P=.012).
• 0° retroversion demonstrated significantly better Simple Shoulder Test (SST) scores (P=.042) and SF-12 Physical Component Summary (PCS) scores (P=.039).
• No significant differences were observed in ER2, functional ER, IR2, anterior elevation, abduction, Constant-Murley, or ASES scores between groups.

Conclusions:

• Humeral retroversion at 30° enhances external rotation (ER1) in lateralized rTSA.
• Humeral retroversion at 0° leads to superior Simple Shoulder Test (SST) and SF-12 PCS scores.
• The choice of humeral retroversion impacts specific functional outcomes and quality of life in rTSA patients.