Prospective comparative study of arthroscopic rotator cuff repair in patients with a Critical Shoulder Angle above 35 degrees. One group also had lateral acromioplasty to reduce the CSA into the 30 to 35 degree range; the other did not. It also introduces a geometric formula from three radiographic measurements to predict how much acromion to resect.
When you see a failed or high-risk cuff repair, check the CSA on a true AP film: above 35 degrees means a mechanically unfavorable shoulder where the cuff works harder to center the humeral head.
This study says you can act on that number, but selectively. In small and medium tears, reducing the CSA into the 30 to 35 degree range with lateral acromioplasty lowered retears and nudged up Constant Scores. In large and massive tears it did nothing, so do not expect a bony procedure to rescue a large tear with poor tissue.
Weigh the benefit honestly: the Constant Score gain was about 3 points, below the MCID, so the strongest signal is the lower retear rate, not a dramatic functional jump. Two measurement pitfalls matter. The CSA is only reliable on a true AP view, since small positioning errors shift it by more than 2 degrees, and this whole topic remains debated because outcome data are inconsistent.
Prospective comparative study of arthroscopic rotator cuff repair in patients with a Critical Shoulder Angle above 35 degrees. One group also had lateral acromioplasty to reduce the CSA into the 30 to 35 degree range; the other did not. It also introduces a geometric formula from three radiographic measurements to predict how much acromion to resect.
When you see a failed or high-risk cuff repair, check the CSA on a true AP film: above 35 degrees means a mechanically unfavorable shoulder where the cuff works harder to center the humeral head.
This study says you can act on that number, but selectively. In small and medium tears, reducing the CSA into the 30 to 35 degree range with lateral acromioplasty lowered retears and nudged up Constant Scores. In large and massive tears it did nothing, so do not expect a bony procedure to rescue a large tear with poor tissue.
Weigh the benefit honestly: the Constant Score gain was about 3 points, below the MCID, so the strongest signal is the lower retear rate, not a dramatic functional jump. Two measurement pitfalls matter. The CSA is only reliable on a true AP view, since small positioning errors shift it by more than 2 degrees, and this whole topic remains debated because outcome data are inconsistent.