What is it?
This is a rare condition in which the blood supply to part or all of the lunate bone in the wrist is lost. This leads to a process of avascular necrosis (bone death) that may affect part or all of the lunate bone. This can in the longer term cause arthritis of the wrist joint. It is seen most often in men between the ages of 20-40 years.
What causes it?
The cause for this condition is unknown. There are however a number of theories. These include variations in the blood supply to the bone, variations in the shape of the bone, the degree of branching of the blood vessels inside the bone and a short ulna bone in the wrist that then leads to an abnormally high load being transferred to the lunate.
What are the signs and symptoms?
Pain over the back of the wrist on exertion is generally the first symptom. This can gradually progress to swelling of the wrist joint, stiffness and eventually pain at rest. The pain can travel up the forearm.
How is it diagnosed?
A detailed history and examination followed by an X-ray is often all that is required to make the diagnosis. In more subtle cases an MRI scan may be required to diagnose the problem.
How is it treated?
The treatment is dependent on the stage of the disease when the patient first presents. However all the treatments fall into 3 groups. The first of these is aimed at re-introducing a blood supply to the bone with the use of a bone graft from either the radius bone in the wrist or metacarpal bone in the hand. The second group of treatments aims to reduce the load that the lunate bone is subjected to. This may be achieved by shortening either the radius or the capitate bone. The final group of operations is referred to as 'salvage' surgery and this is appropriate when arthritis has already set in. In this group of operations, pain relief is normally achieved at the expense of movement. The treatments available for the various stages of the disease process are outlined below:
Stage 1: at this stage the symptoms are often mild and the X-rays are normal. The disease is diagnosed with the help of an MRI scan. At this stage a period of immobilisation in a cast can improve the symptoms. The mainstay of treatment at this stage tends to be splintage and pain relieving medication.
Stage 2: At this stage the areas of dead bone appear white (sclerotic) on the X-rays. The pain is more consistent and swelling is often present. At this stage if the ulna bone is abnormally short, the radius bone in the forearm is shortened to ensure that the two bones are level. This is to offload the lunate. If the radius and ulna bones are the same size then a bone graft along with it's blood supply (vascularised bone graft) can be implanted into the lunate.
Stage 3: Here the lunate has collapsed and the patient is now also suffering with stiffness and swelling alongside the pain. There is still chance that the lunate can be saved with a bone graft or by offloading the bone with a shortening of the radius at this stage. However if the lunate has collapsed to the point where it has now adopted an abnormal position in the wrist, the lunate normally needs to be removed , either on its own or alongside the other two bones in the first row (the scaphoid and triquetrum). Removing the lunate alone will require a fusion of the scaphoid and capitate bones to prevent the capitate falling into the gap left by removing the lunate.
Stage 4: Here arthritis has developed in the wrist joint and there is pain at rest with severe restriction in movement. The options for treatment at this stage are either a wrist fusion or a wrist replacement. A wrist replacement will maintain some movement but is often not appropriate for this very young group of patients. This is because the replacement joint will often wear out in a number of years meaning repeated surgery would be necessary. A wrist fusion in which the wrist joint is permanently stiffened is a reliable operation for pain relief but will afford no movement at the wrist joint. There is the intermediate option of a denervation procedure. In this operation the nerves to the wrist joint are disconnected meaning that you would no longer experience pain coming from the centre of the wrist joint. This would not relieve all the pain from the wrist and the benefits are often short-lived.
What does the operation involve?
The nature of the operation will depend on the stage of the disease and will be discussed in detail during your consultation.
Irrespective of the nature of the operation, you are likely to spend some time in a cast or splint. The period for which this is used depends on the operation type.
Return to work
This again is dependent on the operation and the nature of your work. This will be discussed with you during your consultation.
Driving is only really possible once you are out of cast and even then it can take a couple of weeks out of cast before you can drive comfortably.