This cadaveric study used macroscopic, MRI, and histologic analysis of 6 shoulders to map exactly where the middle deltoid attaches to the lateral acromion. The goal was to determine whether a vertical lateral acromioplasty, done to lower a high critical shoulder angle, would strip the deltoid origin.
The CSA links acromial shape to cuff disease. A CSA above 35 degrees produces a more vertical deltoid pull, forcing the cuff to work harder against proximal humeral migration, which is thought to drive degenerative tears.
Lateral acromioplasty aims to normalize that angle by shaving the lateral acromion. This paper shows the catch: the middle deltoid takes origin from the full height of the lateral wall, so a true vertical resection strips the whole origin.
The practical implication is technique choice. An oblique undersurface bevel lowers the CSA while leaving part of the deltoid attached, whereas a vertical cut sacrifices the entire origin.
When you read or write up acromioplasty outcomes, specify vertical resection versus oblique beveling. The two are not interchangeable, and reassuring MRI data showing no deltoid retraction may reflect the superior collagen band and postoperative scar rather than a preserved lateral attachment.
This cadaveric study used macroscopic, MRI, and histologic analysis of 6 shoulders to map exactly where the middle deltoid attaches to the lateral acromion. The goal was to determine whether a vertical lateral acromioplasty, done to lower a high critical shoulder angle, would strip the deltoid origin.
The CSA links acromial shape to cuff disease. A CSA above 35 degrees produces a more vertical deltoid pull, forcing the cuff to work harder against proximal humeral migration, which is thought to drive degenerative tears.
Lateral acromioplasty aims to normalize that angle by shaving the lateral acromion. This paper shows the catch: the middle deltoid takes origin from the full height of the lateral wall, so a true vertical resection strips the whole origin.
The practical implication is technique choice. An oblique undersurface bevel lowers the CSA while leaving part of the deltoid attached, whereas a vertical cut sacrifices the entire origin.
When you read or write up acromioplasty outcomes, specify vertical resection versus oblique beveling. The two are not interchangeable, and reassuring MRI data showing no deltoid retraction may reflect the superior collagen band and postoperative scar rather than a preserved lateral attachment.