Kienbock' Disease is an isolated disorder of the lunate resulting from vascular compromise to the bone. The symptoms include wrist pain, limited range and motion, and decreased grip strength.

Kienbock's Disease presents in various forms. The changes in the lunate may be very localized or diffuse. With progression, the lunate may fracture into two pieces or crumble into granules or produce an osteochondral fracture from one surface.

The cartilage is not primarily involved in the pathogenesis and remains relatively healthy. Bone death occurs over time. Often, a symptomatic wrist will demonstrate normal X-rays with the diagnosis evident only on MRI. The degree of loading of the wrist appears to be important and changes in the lunate are cumulative.

Additional fault plates may form in other areas of the lunate. This phenomenon is probably present in most of our carpul bones, but time and avoidance of similar overload injuries preclude development of multiple plates. Areas in the lunate reach a critical state in which either a small section or most of the bone becomes relatively walled off by multiple fault plates and further normal injuries can no longer heal effectively because the capillary blood supply is inadequate. Causing the bone to die, providing a significant area further limiting vascular access.

Changing one or more of the aetiological factors can halt progression and the necrosis areas walled off by fault plates can probably heal. Collapsed areas, however, remained deformed.

Most cases of Kienbock's disease develop, then, as a result of a long process of insult which is multifactorial in etiology, producing overload within the substance of the bone. In the susceptible lunate, miniplanes of injury result in relatively avascular fault plates, gradually sectioning off areas in the lunate. Healing in these small areas cannot occur quickly enough if the abnormal loads and demand continue, ultimately resulting in areas of cell death.