Kienbock's Disease

Kienbock’s disease is term coined after the person who described the condition for the first time in 1910. It is avascular necrosis of the lunate bone in the wrist joint. Also known as lunatomalacia, it is mainly seen in the age group of 20-40 yrs. The cause and pathogenesis of this disease is not clear. Involvement of lunate bone is thought to be due to its vulnerable blood supply and its relative fixed position in wrist. History of trauma can be elicited but not always present. It is said to occur due to injury to the anterior carpal ligament. It is seen to be associated with negative or minus ulnar variant, that is, lower end of ulna is shorter than radius. This may facilitate trauma to the bone by impingement of lunate upon the corner of the radius, the triangular cartilage being softer and more compressible than the bone. Plain X rays are initially normal. Later on as the necrosis progresses, there is increase in the bone density which progress to collapse and fragmentation of the bone. MRI shows low signal intensity on T1W sequences which can be either focal or diffuse. Bone scintigraphy is the modality of choice to diagnose the disease as it detects the pathology in very early stages.