Also called the metacarpal sign, shortening of the 4th and 5th metacarpals is present when a line drawn at a tangent to their heads intersects the 3rd metacarpal. The commonest causes are
idiopathic, post-traumatic, Turner’s syndrome, pseudohypoparathyroidism, pseudopseudohypoparathyroidism and basal cell naevus syndrome. In this case an old fracture of the 5th metacarpal suggests the cause may be previous trauma.
1. Dahnert W. Radiology Review Manual, 5th edition. Lippincott, Williams and Wilkins 2003
2. Weissleder R. et al Primer of Diagnostic Imaging, 3rd edition, Mosby 2003