It is also known as avascular necrosis of the lunate or osteocronosis of the lunate.
If blood supply is cut off to body tissue, oxygen and nutrients cannot reach the tissue, and it will die. This is necrosis.
Kienbock's most commonly affects people aged from 20 to 40 years of age, and it occurs in men more often than in women. It rarely happens in both wrists.
Kienbock's disease causes pain the wrist.
Common signs and symptoms are:
- Swelling, pain, and stiffness in the wrist
- Clicking or clunking in the wrist
- Weakening of grip strength
- Tenderness directly over the lunate bone
- Difficulty or pain when turning the hand upward
The carpal bones consist of eight wrist bones that connect the hand to the forearm. These are the bones that make flexible positioning of the hand possible.
The lunate bone is crucial for proper movement and support of the joint. Damage to this bone can lead to stiffness and pain and eventually arthritis of the wrist.
In the early stages, the patient might experience pain and swelling, similar to a wrist sprain, but, unlike a sprain, the symptoms will persist and get worse.
The progression of Kienbock's disease varies between patients, but it tends to develop slowly and subtly over a number of years. In time, the mechanics of the wrist become affected, leading to abnormal stress and wear inside the wrist.
There are four stages.
Stage 2: X-rays show that the bone is unusually dense. When bone loses its blood supply, it hardens.
Stage 3: The bone starts to fragment and collapse.
Stage 4: The lunate has completely collapsed, and nearby bones have also become damaged and arthritic. Not all patients reach this stage.
There is no evidence that Kienbock's disease is inherited, but genetic factors may play a role.
Kienbock's disease does not appear to have a single cause, but it probably stems from multiple factors:
In Kienbock's disease, a disrupted blood supply causes the lunate bone to collapse.
- Problems with arterial blood supply. Most people have two blood vessels supplying blood to the lunate bone, but some have just one.
- Blood does not drain away properly through the veins.
- Trauma may affect blood supply, for example, a single blow to the wrist.
- There may be skeletal variations, for example, an abnormally shaped lunate bone.
Another cause could be that the ulna, the long bone in the forearm, is shorter than normal. If the ulna and radial bones are different lengths, this may put extra pressure on the lunate in certain wrist motions. This extra stress could lead to Kienbock's disease.
One study found that 9.4 percent of patients with cerebral palsy also had Kienbock's disease.
There is no evidence to confirm that certain jobs increase the risk of developing Kienbock's disease.
Most people who have Kienbock's disease live with the condition for months or years until the until the symptoms become problematic, and they seek help. Patients normally approach the doctor with wrist pain.
The doctor will ask about symptoms, medical history, previous trauma, and how long the person has had the symptoms. They will also examine the hand and wrist.
Kienbock's disease may be difficult to diagnose accurately in the early stages, because the signs and symptoms resemble those of many other conditions, such as wrist sprain and any cause of arthritis.
During Stage 1, an x-ray will show an apparently normal lunate bone, but an MRI scan can help to assess the blood supply to the lunate.
Treatment usually depends on how early on the disease is diagnosed.
A physical therapist can advise on less painful ways to use the wrist.
The following non-surgical options can help:
- Resting the wrist: During the early stages, it might be possible to splint and cast the wrist for several months. Resting the wrist increases the chance of restoring blood flow to the lunate bone.
- Anti-inflammatory drugs: Ibuprofen, aspirin, and other painkillers may help manage swelling and pain during the early stages.
- Cortisone injections: These may help with symptoms.
If over-the-counter (OTC) anti-inflammatory medications start to become less effective, the doctor may recommend surgery.
A physical therapist can teach the patient how to use the wrist in a way that is less painful and slows down the progression of the disease.
Several different surgical procedures are available for patients with Kienbock's disease.
The options depend on several factors, including the stage of disease, the person's activity level, and their personal goals.
Revascularization involves restoring or increasing the blood supply to the lunate bone.
The surgeon removes a portion of bone with all its attached blood vessels from another bone and inserts it into the lunate bone. This is possible during stages 1 and 2, before the bone deteriorates too far.
An external fixator may be used to hold the bones stay in place while they heal. An external fixator is a metal device which is attached to the outside of the wrists, with pins that insert into the bone.
Joint leveling is an option when the two bones of the forearm, the radius and the ulna, have different lengths.
Bone grafts may be applied to lengthen the bone, or a section of bone is removed to shorten it. Joint leveling may stop the disease from progressing by reducing the forces that compress the lunate bone.
Proximal row carpectomy
Proximal row carpectomy (PRC) involves the removal of the lunate bone and the two bones on either side of it. It is an option if the bone is broken into pieces or severely collapsed.
This is a straightforward procedure, but it may increase the risk of arthritis if the bones do not match.
Fusion can be partial or complete. Partial fusion involves fusing some of the wrist bones together, effectively making one solid bone. This can reduce symptoms of pain and maintain some wrist motion.
If the patient has severe arthritis of the wrist, the doctor may recommend fusing all the bones to reduce pain and improve wrist function. Wrist motion will be lost, but the patient will still be able to rotate their forearm.
When the bones are fused, the result will be permanent.
The lunate bone is replaced with a prosthetic replica made of a special, durable, pyrolytic carbon material, while preserving the normal anatomy of the other bones.
This is a relatively new procedure, so the long-term results are not yet known.
Some patients may undergo several different procedures during their lifetime.
Untreated, a person with Kienbock's disease will see progressive deterioration of the wrist, loss of wrist function and increasing pain.