Carpal arcs

Gilula three carpal arcs refer to the carpal alignment described on posteroanterior or anteroposterior wrist radiographs and are used to assess normal alignment of the carpus:

• 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

Alignment

• 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
  • a triquetrum that is shorter 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
• 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 .

Siehe auch:

• perilunäre Luxation
• perilunäre Luxationsfraktur
• karpale Luxationen
• perilunäre Instabilität

und weiter:

• Scapholunäre Dissoziation