Shortening of the fourth/fifth metacarpals is seen in a variety of apparently disparate conditions.
Common causes 2:
- post-infective (e.g. osteomyelitis, yaws, tuberculosis dactylitis)
- post-traumatic (acute and chronic/healed)
- Turner syndrome
Uncommon causes 2:
- basal cell naevus syndrome (Gorlin syndrome)
- hereditary multiple exostosis syndrome 5
- juvenile idiopathic arthritis
- sickle cell disease with secondary infarction
- Langer-Giedion syndrome
Isolated shortening of the 5th metacarpals has been recently described in a familial variant of type 1 diabetes mellitus 3.
Hand x-rays readily identify the abnormality and can be assessed by drawing a line along the heads of the 4th and 5th metacarpals. If this line intersects the head of the 3rd metacarpal then shortening is deemed to be present.
Thus, shortened 4th metacarpal is the key to this finding. It is known as the metacarpal sign. It is important to note that a positive sign can be seen in up to 10% of normal individuals 4.
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