Lunate

Study entry

Parts

Half-moon-shaped bone of the proximal row, between the scaphoid and the triquetrum.

Joints

Radius (and articular disc), scaphoid, triquetrum, capitate and hamate.

Clinical

The carpal bone that dislocates most often, generally forward, and it may compress the median nerve in the carpal tunnel.

Source: cap. 3, «Huesos de la mano» y cuadro clínico

Clinical correlation

Fractures and dislocations of the carpus; dislocation of the lunate

Anterior dislocation of the lunate is rare but serious: it comes from a fall on the wrist in extension. The lunate is pushed from the floor of the carpal tunnel toward the palmar surface and may compress the median nerve (carpal tunnel syndrome). Because it is poorly vascularized, it may become necrotic, and is sometimes removed. In severe osteoarthritis of the carpus, the bones may need to be fused (arthrodesis). In a child, fracture-separation of the distal epiphysis of the radius is common: the lateral radiograph shows the epiphysis displaced backward; put back in place, growth is usually normal.

Related clinical cases

• Fractures and dislocations of the carpus; dislocation of the lunate

Other structures in this region

• Clavicle
• Scapula
• Humerus
• Radius
• Ulna
• Scaphoid
• Triquetrum
• Pisiform