Kienbock's disease.

Kienbock's disease (lunate malacia) is an unusual but not rare cause of wrist pain. It is manifested by avascular necrosis and subsequent disintegration of the lunate. Despite recognition of this disease entity for the past 70 years, its cause is still debated. Most investigators relate it to a stress fracture that leads to devascularization of the major segment of the lunate if the lunate is supplied by one volar vessel. The classification of Kienbock's disease is based on its roentgenologic appearance. Stage 1 consists of small fracture lines. Stage 2 is rarification along the fracture line, usually on the volar pole. Stage 3 shows sclerosis of the bone dorsal to the fracture site. Stage 4 shows sclerosis of the bone dorsal to the fracture site, and collapse and secondary fracture with loss of architectural integrity of the lunate. Stage 5 shows secondary arthritic changes of the radius. Treatment is categorized into two general types. The first is an attempt to allow revascularization of the lunate be relieving the compression forces. This is accomplished by lengthening the ulna and/or shortening the radius, with capitate-hamate fusion; or by shortening the capitate and fusing the capitate and hamate. These procedures are performed in the early stages of Kienbock's disease. The second type of treatment, used in more advanced cases, includes excision of the lunate: replacement of the lunate by prosthesis, with or without capitate shortening and/or capitate-hamate fusion; and various types of intercarpal fusion.