Double-arc sign

Last revised by Dr Daniel J Bell on 12 Jul 2022

The double-arc sign, also known as the McKee double-arc sign, is a radiographic indication of a coronal shear fracture of the distal humerus, which involves the capitellum and extends beyond the lateral trochlear ridge to include a part of the trochlea 1,2.

The double-arc sign is characterized on a lateral radiograph of the elbow by two separately visible arcs representing the displaced capitellum and the trochlea 1,2.

History and etymology

Michael McKee is a Canadian orthopedic surgeon who first published about the double-arc sign in 1996 when he was a Fellow at Massachusetts General Hospital 2.

See also

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Cases and figures

  • Case 1
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  • Case 1
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