Lunate avascular necrosis develops because of compromise to the blood supply to the lunate bone. Although a microfracture may be noted, a post-traumatic or overuse etiology is unusual; rather, the development of kienbock's disease is typically idiopathic (without a cause).
Xrays are helpful in staging the severity of the involvement of the lunate, and are taken into consideration along with the length of the ulna bone, in order to select a surgical option to help take away pain and restore functional motion.
Options include those that indirectly try to divert force away from the lunate--allowing it to heal itself and revascularize (radial shortening procedure or capitate shortening in conjunction with Capitohamate partial fusion), those that remove the lunate bone if it is felt that it has no chance to heal or if arthritis has developed (proximal row carpectomy), and those that attempt to introduce a bone graft with a blood supply into the lunate bone (vascularized bone graft). The challenge is selecting the appropriate option for the appropriate patient, since favorable results AND unfavorable results are reported for each.
In general, advanced stages of disease require removal of the bone--proximal row carpectomy, and earlier stages may do well with either a shortening of the radius bone, capitate shortening, or a vascularized bone graft. If wrist arthritis had developed, then the only option is wrist replacement or wrist fusion.
The length of the ulna bone helps in the selection process, since if the radius is shortened in a wrist in which the ulna is not short to begin with, pain on the outside of the wrist may result. In such cases, surgical procedures aimed at either revascularizing the lunate or directing force away from the lunate (without increasing th length of the ulna) are options. Directing force away from the lunate without increasing the length of the ulna requires either Capitate shortening or Closing wedge radial osteotomy. Once Stage 3B exists----when the lunate has framentation AND there is carpal height loss (such that the radioscaphoid angle is greater than 60 degrees), the results of osteotomy appear to fall off. A full assessment of the lunate may require both an MR scan as well as a CT scan.
Occasionally, avascular changes can be transient and not even visible on xray. In cases of Stage 1 disease where only the MRI is abnormal, and in cases where symptoms are relatively recent, there may be a role for temporary pinning---which has been efficacious in cases of "adolescent Kienbocks" The thinking here is that the lunate may revascularize with a less invasive and reversible (ie pin removal) treatment. I have attached an article from the Journal of Hand Surgery below which addresses this option, which arguably burns no bridges in such early cases!
Xrays are helpful in staging the severity of the involvement of the lunate, and are taken into consideration along with the length of the ulna bone, in order to select a surgical option to help take away pain and restore functional motion.
Options include those that indirectly try to divert force away from the lunate--allowing it to heal itself and revascularize (radial shortening procedure or capitate shortening in conjunction with Capitohamate partial fusion), those that remove the lunate bone if it is felt that it has no chance to heal or if arthritis has developed (proximal row carpectomy), and those that attempt to introduce a bone graft with a blood supply into the lunate bone (vascularized bone graft). The challenge is selecting the appropriate option for the appropriate patient, since favorable results AND unfavorable results are reported for each.
In general, advanced stages of disease require removal of the bone--proximal row carpectomy, and earlier stages may do well with either a shortening of the radius bone, capitate shortening, or a vascularized bone graft. If wrist arthritis had developed, then the only option is wrist replacement or wrist fusion.
The length of the ulna bone helps in the selection process, since if the radius is shortened in a wrist in which the ulna is not short to begin with, pain on the outside of the wrist may result. In such cases, surgical procedures aimed at either revascularizing the lunate or directing force away from the lunate (without increasing th length of the ulna) are options. Directing force away from the lunate without increasing the length of the ulna requires either Capitate shortening or Closing wedge radial osteotomy. Once Stage 3B exists----when the lunate has framentation AND there is carpal height loss (such that the radioscaphoid angle is greater than 60 degrees), the results of osteotomy appear to fall off. A full assessment of the lunate may require both an MR scan as well as a CT scan.
Occasionally, avascular changes can be transient and not even visible on xray. In cases of Stage 1 disease where only the MRI is abnormal, and in cases where symptoms are relatively recent, there may be a role for temporary pinning---which has been efficacious in cases of "adolescent Kienbocks" The thinking here is that the lunate may revascularize with a less invasive and reversible (ie pin removal) treatment. I have attached an article from the Journal of Hand Surgery below which addresses this option, which arguably burns no bridges in such early cases!
