Kienbocks
Wrist Disease
Introduction
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.
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. Our 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)
