[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) › Lunate [Skeletal system](https://durgical.com/en/anatomy/system/skeletal-system/) · [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) # Lunate The lunate is the moon-shaped wrist bone in the centre of the first row; it sits between the radius and the capitate and can dislocate in falls. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=upper_limb&select=lunate&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The half-moon-shaped wrist bone in the centre, next to the radius. ## What it does One of the eight carpal bones that let the wrist bend and carry load to the forearm. ## Key points - On the lateral view the radius, lunate and capitate line up like stacked cups; in perilunate dislocation the capitate leaves the lunate's cup, in lunate dislocation the lunate tips palmarward (spilled teacup sign) - A lunate dislocated into the carpal tunnel can compress the median nerve (acute carpal tunnel syndrome) - Kienböck disease is associated with negative ulnar variance; it is staged on X-ray and MRI (Lichtman) from bone oedema to collapse and arthritis ## Key facts **Joints with** Radius, scaphoid, triquetrum, capitate (hamate); TFCC **Landmarks** Half-moon shape; most often dislocated carpal ## Relations **Above** Lunate fossa of the distal [radius](https://durgical.com/en/anatomy/radius/) laterally and the [TFCC](https://durgical.com/en/anatomy/triangular-fibrocartilage-complex/) medially **Below** Head of the [capitate](https://durgical.com/en/anatomy/capitate/) in its concave distal surface; in many wrists also a small facet for the [hamate](https://durgical.com/en/anatomy/hamate/) **Lateral** [Scaphoid](https://durgical.com/en/anatomy/scaphoid/), joined by the [scapholunate ligament](https://durgical.com/en/anatomy/scapholunate-interosseous-ligament/) **Medial** [Triquetrum](https://durgical.com/en/anatomy/triquetrum/), joined by the [lunotriquetral ligament](https://durgical.com/en/anatomy/lunotriquetral-ligament/) **In front** [Palmar wrist ligaments](https://durgical.com/en/anatomy/palmar-radiocarpal-ligaments/); between them in front of the capitolunate joint lies a weak area (space of Poirier); further in front, the floor of the [carpal tunnel](https://durgical.com/en/anatomy/carpal-tunnel/) with the [median nerve](https://durgical.com/en/anatomy/median-nerve/) and flexor tendons **Behind** [Dorsal radiocarpal ligament](https://durgical.com/en/anatomy/dorsal-radiocarpal-ligament/) and dorsal [wrist capsule](https://durgical.com/en/anatomy/wrist-joint-capsule/) ## How to find it Felt on the back of the wrist just distal to Lister's tubercle, in line with the third metacarpal; it stands out when the wrist is flexed. Tenderness here is typical of Kienböck disease and of scapholunate injuries. ## On imaging Lateral view: radius, lunate and capitate should be collinear; dorsal tilt of the lunate is DISI and palmar tilt is VISI. PA view: three smooth carpal arcs (Gilula arcs) along the proximal row's upper and lower surfaces and the proximal capitate and hamate; a broken arc or a triangular lunate suggests dislocation. MRI shows early Kienböck changes before X-rays do. ## Common problems - Kienböck disease: the lunate slowly loses its blood supply and collapses. - Dislocation in a severe wrist injury (perilunate dislocation), an emergency. - Drifts out of line when the scapholunate ligament tears. ## How it is diagnosed X-rays, then MRI to see the blood supply. A dislocation is seen on the side X-ray. ## Treatment - Splint and activity change in early Kienböck disease. - Surgery to unload or revascularize the lunate in later stages. - Urgent reduction and repair for a dislocation. ## Clinical notes - Perilunate injuries progress from the radial to the ulnar side (Mayfield stages): scapholunate tear, capitolunate dislocation, lunotriquetral tear and finally lunate dislocation - Perilunate dislocations are often missed on the first X-rays because the PA view can look almost normal - A lunotriquetral ligament tear lets the lunate tilt palmarward with the triquetrum (VISI) and causes ulnar-sided wrist pain ## Anatomical variants - Some lunates have a separate medial facet that articulates with the hamate (type II lunate), linked to arthritis at the tip of the hamate - Lunotriquetral coalition, the most common carpal coalition, usually painless and found by chance ## Development Ossifies around age 3–4, the fourth carpal bone to appear. ## Related conditions - [Scaphoid fracture](https://durgical.com/en/conditions/scaphoid-fracture/) - [Ganglion cyst](https://durgical.com/en/conditions/ganglion-cyst/) ## Test yourself Think of the answer, then tap the question to see it. ## On a lateral wrist X-ray, how does lunate dislocation differ from perilunate dislocation? In lunate dislocation the lunate tips palmarward (spilled teacup sign); in perilunate dislocation the capitate leaves the lunate's cup. ## Which nerve can a lunate dislocated into the carpal tunnel compress? The median nerve, causing acute carpal tunnel syndrome. ## What is Kienböck disease, and which ulnar variance is it linked to? Loss of blood supply and collapse of the lunate; it is associated with negative ulnar variance. ## In what order do perilunate injuries progress (Mayfield stages)? Radial to ulnar: scapholunate tear, capitolunate dislocation, lunotriquetral tear and finally lunate dislocation. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/lunate/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** os lunatum TA2 1252 **Official Spanish (DeCS)** Hueso semilunar **English (TA2)** Lunate ## Related - [Dorsal intercarpal ligament](https://durgical.com/en/anatomy/dorsal-intercarpal-ligament/) - [Dorsal radiocarpal ligament](https://durgical.com/en/anatomy/dorsal-radiocarpal-ligament/) - [Extensor tendons](https://durgical.com/en/anatomy/extensor-digitorum-tendons/) - [FDP tendons](https://durgical.com/en/anatomy/flexor-digitorum-profundus-tendons/) - [Lunotriquetral ligament](https://durgical.com/en/anatomy/lunotriquetral-ligament/) - [Midcarpal ligaments](https://durgical.com/en/anatomy/midcarpal-and-intercarpal-ligaments/) - [Scapholunate ligament](https://durgical.com/en/anatomy/scapholunate-interosseous-ligament/) - [TFCC](https://durgical.com/en/anatomy/triangular-fibrocartilage-complex/) Sources: Terminologia Anatomica (TA2); [Anatomy, Shoulder and Upper Limb, Hand Carpal Bones](https://www.ncbi.nlm.nih.gov/books/NBK535382/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/lunate/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/lunate/