This cadaveric study of 420 scapulas from the Hamann-Todd Collection asked a foundational question: is acromial shape (Bigliani type I/II/III) a fixed anatomic trait or an acquired product of aging? Using outlet radiographs, direct measurement, and visual inspection across five age decades, the study separated native acromial morphology from age-related spur formation and AC joint degeneration.
When you see a hooked acromion on an outlet view, you are looking at that patient's native skeletal architecture — not the cumulative damage of decades of overhead use. This paper is why we treat Bigliani morphology as an independent predisposing factor for impingement and rotator cuff disease, not simply a marker of a degenerated shoulder.
Clinically, this separates two distinct problems: the patient's fixed anatomy (morphologic type, present since skeletal maturity) and their acquired pathology (spurs, AC arthritis. Both age-dependent and far more common after age 50). When you are planning an acromioplasty, you are addressing the native undersurface architecture, not just cleaning up spurs.
The spur-direction finding matters for imaging interpretation. Anterior acromial spurs travel anteromedially along the coracoacromial ligament footprint. They project forward and medially, not downward. A true type III hook on outlet view represents the acromion's actual cortical contour, confirmed here by specimens photographed with visible hooks but no spur formation at all.
For os acromiale: when you find one, image the contralateral shoulder. Bilateral involvement occurred in 41% of affected individuals in this series.
This cadaveric study of 420 scapulas from the Hamann-Todd Collection asked a foundational question: is acromial shape (Bigliani type I/II/III) a fixed anatomic trait or an acquired product of aging? Using outlet radiographs, direct measurement, and visual inspection across five age decades, the study separated native acromial morphology from age-related spur formation and AC joint degeneration.
When you see a hooked acromion on an outlet view, you are looking at that patient's native skeletal architecture — not the cumulative damage of decades of overhead use. This paper is why we treat Bigliani morphology as an independent predisposing factor for impingement and rotator cuff disease, not simply a marker of a degenerated shoulder.
Clinically, this separates two distinct problems: the patient's fixed anatomy (morphologic type, present since skeletal maturity) and their acquired pathology (spurs, AC arthritis. Both age-dependent and far more common after age 50). When you are planning an acromioplasty, you are addressing the native undersurface architecture, not just cleaning up spurs.
The spur-direction finding matters for imaging interpretation. Anterior acromial spurs travel anteromedially along the coracoacromial ligament footprint. They project forward and medially, not downward. A true type III hook on outlet view represents the acromion's actual cortical contour, confirmed here by specimens photographed with visible hooks but no spur formation at all.
For os acromiale: when you find one, image the contralateral shoulder. Bilateral involvement occurred in 41% of affected individuals in this series.