Gilula three carpal arcs

Last revised by Nico Behnke on 27 Aug 2023

Gilula three carpal arcs are used in the assessment of normal alignment of the carpus on PA wrist radiographs. They entail:

  • first arc: is a smooth curve outlining the proximal convexities of the scaphoid, lunate and triquetrum

  • second arc: traces the distal concave surfaces of the same bones

  • third arc: follows the main proximal curvatures of the capitate and hamate


  • carpal bones have smooth and rounded edges to varying degrees, lines joining these convexities form arcs, when major convexities are used in drawing

  • there should be no step-offs in the contour of the arcs, except for two normal variants 4

    • a triquetrum that is shorter in the proximal-distal dimension than the lunate creates a step-off in the first arc but there is still a normal second arc

    • "bi-lobed" appearance of second carpal arc in lunate type II morphology because of a proximally prominent hamate

  • disrupted arc may indicate a ligamentous injury or fracture at the site of the broken arc

History and etymology

The concept of three radiographic arcs was first proposed by Louis A Gilula (1942-2014) in 1979 3,5

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Cases and figures

  • Figure 1: Gilula carpal arcs
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  • Figure 2: Gilula's arcs
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  • Figure 3: disrupted carpal arcs of Gilula
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