Kienbock's disease is the loss of blood supply to the lunate bone in the wrist. This causes painful loss of motion and decreased grip strength. Without enough blood, the bone starts to break down and even collapse.
The cause of this problem isn't known. Many theories exist such as one bone in the forearm being longer than the other and putting increased load on the lunate. Some think it's caused by the type of blood supply to the wrist, others suggest the shape of the lunate as the cause.
The disease affects men and women of all backgrounds. This condition has been reported in housewives, police officers, students, office workers, and even the unemployed. Even though it was first seen in 1910, not much is known about this problem.