Hatchet sign (ankylosing spondylitis)

Last revised by Daniel J Bell on 18 Dec 2021

The hatchet sign refers to the limited erosion of the lateral aspect of the humeral head that produces a hatchet-shaped deformity. This finding is typically associated with ankylosing spondylitis.

In the absence of osteoporosis and the presence of sclerosis, this sign helps to differentiate it from rheumatoid arthritis.

Confusingly, the similar term "hatchet head" shoulder has been used by orthopedic surgeons for multiple epiphyseal dysplasia 3,5.

Differential diagnosis

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Cases and figures

  • Case 1
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