Scapular hypoplasia - dentate glenoid

Case contributed by Brian Gilcrease-Garcia
Diagnosis certain

Presentation

Chronic right shoulder pain.

Patient Data

Age: 60 years
Gender: Female

Profound hypoplasia of the scapular neck and glenoid. Note the "dentate" undulating morphology of the glenoid surface (best seen on internal rotation view). There is irregular joint space narrowing, subchondral cyst formation, and remodeling of the humeral head, consistent with glenohumeral osteoarthritis. Glenohumeral alignment is maintained.

CT confirms severe scapular neck/glenoid hypoplasia with "dentate" morphology of the glenoid:

  • diminished glenoid bone stock (less than 2 cm at the base of the coracoid process), particularly of posterior inferior glenoid
  • marked (approximately 30 degrees) of glenoid retroversion
  • non-uniform glenohumeral cartilage loss, humeral head and glenoid osteophytosis, and subchondral cyst formation indicate severe osteoarthritis

Case Discussion

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.

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