Mr Jeremy Read
Hand & Wrist Surgeon
Private Secretary 07565 446713
NHS Secretary 01923 217155
The blood supply for the lunate arrises from the transvers carpal arches, these are in turn derived from the Radial, Ulnar, Anterior and Posterior interossious arteries. Most lunates recieve a blood supple both from the front (volar) and back (dorsal) surface. However a smaller proportion ~20% have only a supply from the volar surface. There have also been descriptions of the internal linking of these vessels that form I, Y and X patterns which can also influence how likely the bone is to have problems with blood supply.
Probably one of the most commonly sites associations with Kienbock's in ulnar negative variance, this is were the relative length of the ulna is shorter than the radius. Some studies have shown that this anatomical varient is associated with a higher incidence of Kienbock's disease, though other studies have not consistently confirmed this association.
There is also some indication that lunate shape may increase the risk of avascular problems, and there is also an association between lunate shape and ulnar length. With ulnar negative variance the lunate tends to be more pointed rather than the rectangular or square shape associated with neutral or positive ulnar variance. The more pointed (type I) lunate is felt to be more prone to fatigue and stress fracture due to the increased angle of the trabeculae (internal scaffold) within the bone.
Whilst fracture and dislocations of the lunate can lead to a transient change in the vascularity of the lunate there is no consistent association between trauma and Kienbock's avascular necrosis
There are associations between Kienbock's and Scleroderma, Sickle Cell Anaemia, SLE and steroid use. None of these have been shown to cause Kienbock's however.