Scapular hypoplasia is a congenital abnormality of the scapula due to improper ossification of the scapula, with the abnormal morphology predisposing to secondary osteoarthritis. In this case, the diminutive glenoid bone stock and pronounced glenoid retroversion are out of proportion to the (still severe) osteoarthritis, representing a combination of congenital malformation and degenerative change.

Early diagnosis may be particularly beneficial for symptomatic patients, as shoulder arthroplasty for treatment of late-stage secondary degenerative disease is often technically difficult ^1,3.