Cadaveric study testing whether arthroscopic acromioplasty can surgically reduce the critical shoulder angle (CSA), a radiographic parameter linking acromial shape to rotator cuff disease. Ten shoulders had CSA measured natively, after standard anterolateral acromioplasty, and after adding a 5-mm lateral acromion resection. The deltoid origin was dissected afterward to check for damage.
The CSA gives you a single AP-radiograph number that predicts shoulder pathology: above 35 points toward rotator cuff tears, below 30 toward glenohumeral osteoarthritis, with 30 to 35 as the sweet spot.
This paper is the proof-of-concept that you can actually move that number surgically. A standard anterolateral acromioplasty barely touches it (1.4°), so the meaningful correction comes from a dedicated 5-mm lateral acromion resection.
The practical rule: reserve lateral resection for a CSA truly above 35. Two specimens starting near 32° were pushed below 30°, trading cuff-tear risk for osteoarthritis risk. Because the major anterolateral deltoid fibers originate from the superior acromion, working from the undersurface preserves the deltoid origin, which is the safety limit on how aggressive you can be.
Remember this is cadaveric and biomechanical. Whether lowering the CSA actually reduces cuff tears or retears has not been shown clinically.
Cadaveric study testing whether arthroscopic acromioplasty can surgically reduce the critical shoulder angle (CSA), a radiographic parameter linking acromial shape to rotator cuff disease. Ten shoulders had CSA measured natively, after standard anterolateral acromioplasty, and after adding a 5-mm lateral acromion resection. The deltoid origin was dissected afterward to check for damage.
The CSA gives you a single AP-radiograph number that predicts shoulder pathology: above 35 points toward rotator cuff tears, below 30 toward glenohumeral osteoarthritis, with 30 to 35 as the sweet spot.
This paper is the proof-of-concept that you can actually move that number surgically. A standard anterolateral acromioplasty barely touches it (1.4°), so the meaningful correction comes from a dedicated 5-mm lateral acromion resection.
The practical rule: reserve lateral resection for a CSA truly above 35. Two specimens starting near 32° were pushed below 30°, trading cuff-tear risk for osteoarthritis risk. Because the major anterolateral deltoid fibers originate from the superior acromion, working from the undersurface preserves the deltoid origin, which is the safety limit on how aggressive you can be.
Remember this is cadaveric and biomechanical. Whether lowering the CSA actually reduces cuff tears or retears has not been shown clinically.