Acromion Classifications

Acromion morphology: Bigliani Classification

Type 1: Flat, 17%

Type 2: Curved, 43%

Type 3: Hooked, 40%

Acromion morphology based on sagittal oblique MRI: Epstein Classification

Epstien R E et al, Radiology,187: 479-481, 1993

Type 1- flat

Type 2- smoothly curved

Type 3- hooked

Os Acromiale Types: Liberson

Lieberson F, JBJS 19:683-689, 1937

Incidence 1.4%

Type 1: non-union between meso and meta acromion (typical os acromiale)

Type 2: non-union between pre and meso acromion

Type 3: non-union between pre and meso as well as meta acromion

Type 4: non-union between pre and meso acromion, meso and meta acromion as well as meta and basi acromion

Types of scapular notch: Rengachary

Rengachary et al, Neurosurgery, 5:447-451, 1979

Type 1: No notch, 8%

Type 2: blunted ‘V’ shape, 31%

Type 3: symmetrical ‘U’ shape, 48%

Type 4: small , narrow ‘V’ shape, 3%

Type 5: Type 3 but with ossified medial part of ligament, 6%

Type 6: Completely ossified bony foramen, 4%