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Kienbocks Wrist

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Posted by on Wednesday, September 8, 2010, 3:16
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Kienbock’s disease, properly spelled Kienböck’s, is also known as Avascular Necrosis of the Lunate, or Lunatomalacia. It was first described by Viennese radiologist Dr. Robert Kienbock in 1910. Kienbock’s disease is a condition in which one of the small bones of the wrist loses its blood supply and dies, causing pain and stiffness with wrist motion. In the late stages of the disease, the bone collapses, shifting the position of other bones in the wrist. This shifting eventually leads to degenerative changes and osteoarthritis in the joint. While the exact cause of this uncommon disease isn’t known, a number of treatment options are available.

kienbocks Wrist Disease
kienbocks Wrist Disease

Stage 3 of Kienbocks Disease showing collapse and possible fragmentation of the lunate bone

Cause

Doctors have not determined exactly what causes Kienbock’s disease. A number of factors seem to be involved. Usually the patient has injured the wrist. The injury may be a single incident, such as a sprain, or a repetitive trauma. But the injury alone does not seem to cause the disease.

The way that blood vessels supply the lunate is thought to play a role in Kienbock’s disease. Some bones in the body simply have fewer blood vessels that bring in blood. The lunate is one of those bones. A bone with a limited blood supply may be more at risk of developing the disease after an injury. The reduced blood supply might be the result of a previous injury to the blood vessels.

It is believed that a difference in the lengths of the arm bones (the radius and ulna), known as Ulnar Variation –generally this is a negative ulnar variance, which means the ulna is shorter than the radius by a few millimeters– is a predisposing factor. Because the bones are asymmetrical, greater “load” or stress is put on the lunate making it more susceptible to this condition. Especially in people with ulnar variance, it is possible to have this condition in both wrists (bilaterally).

A second predisposing factor would be a variation in the blood supply to the lunate itself. Normally there are multiple vessels supplying blood to the lunate, and an injury to one of them would be inconsequential, but some people were born with only one vessel to the lunate. An injury to that vessel could lead to Avascular Necrosis, which is to say, Kienbock’s Disease.

Symptoms

A painful and sometime swollen wrist
Pain or difficulty in turning the hand upward
Tenderness directly over the wrist bone
Wrist stiffness
4 stages of progression:

Stage 1: Symptoms similar to that of wrist sprain.

Stage 2: The lunate bone begins to harden. The patient may complain of persistent pain, swelling and tenderness.

Stage 3: The dead bone begins to collapse and break into small pieces The patient will complain of intense pain.

Stage 4: The surfaces of the adjoining bones are affected which often results in arthritis.

Treatment

Treatment is not well-defined, because the cause is not well known. Kienbocks is very difficult to diagnose as the initial symptoms are so similar to a sprained wrist. Even x-rays appear normal at the beginning but the primary goal of treatment should be to help relieve pressure on the lunate and assist blood flow.

Medical therapy: Treatment is primarily directed by the level of symptoms. The primary methods of non-operative treatment are immobilization and anti-inflammatory medications. Because our best understanding of the disease is that it is related to loss of blood supply to the lunate, and because we know some patients can be cured if we can just avoid trauma and collapse, this is our first choice in the earlier stages. Younger patients tend to have a better ability to re-establish blood flow to various areas, so in a very young patient, we almost always start with this approach, especially if the disease is early, in hopes of allowing revascularization of the lunate and prevention of disease progression.

Surgical therapy: Surgery is reserved for more advanced disease. Although there is no cure, there are several surgical options for treating the more advanced stages of Kienböck’s disease. The right procedure for you will depend on several factors, including disease progression, your personal activity levels and goals. The two most important pieces of information are the stage of your disease and the presence or absence of ulnar variance (the length of the ulna to the length of the radius). Possible surgical procedures include:
Excision of dead lunate
Joint-leveling procedures (shortening the longer bone or lengthening the shorter bone)
Intercarpal fusions (remove some of the wrist bone joints and make them grow together into one or more bigger bones)
Revascularization (returning the blood supply to the bone)

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