Diagnostic Radiology/Musculoskeletal Imaging/Joint Disorders/Osteochondroses

The osteochondroses are a motley group of entities that were initially lumped together due to morphological similarity. They often occur in children are associated with apparent fragmentation of bone in an epiphysis or apophysis. With the perspective of time, we can now divide these entities into one of three rough groups: post-traumatic, osteonecrosis and normal variants of ossification.

Kienböck's Disease

Definition: Avascular necrosis of the lunate bone, one of the bones in the most proximal carpal row. It is also known as lunatomalacia.

Etiology: Idiopathic or secondary to repetitive trauma. Has been associated in the past past with negative ulnar variance, however this has been recently questioned. The condition was first described in 1910 by a Viennese radiologist, Dr. Robert Kienböck.

Clinical Findings:

Many people with Kienböck’s disease believe they have a sprained wrist at first, usually after some form of trauma to the wrist, such as a fall. This type of trauma can disrupt the blood flow to the lunate. In most people, two vessels supply blood to the lunate, but in some people there is only one source. This puts them at greater risk for developing the disease. As the disease progresses, other signs and symptoms are noted, including:

• A painful and sometimes swollen wrist
• Limited range of motion in the affected wrist (stiffness)
• Decreased grip strength in the hand
• Tenderness directly over the bone (on the top of the hand at about the middle of the wrist)
• Pain or difficulty in turning the hand upward

Stages of Disease:

Kienböck’s disease follows a specific progressive pattern through four stages.

Stage 1:	Symptoms similar to those of a wrist sprain. X-rays may be normal or show a line indicating a possible fracture. Magnetic resonance imaging (MRI) may also be helpful in making the diagnosis in this early stage.
Stage 2:	Radiographs may demonstrate lunate sclerosis. Either an MRI or a computed tomography (CT) scan may be used to assess the condition of the bone. Recurrent pain, swelling and wrist tenderness are common.
Stage 3:	The avascular bone begins to collapse. The surrounding bones may begin to shift position. Patients experience increasing pain, weakness in gripping, and limited motion.
Stage 4:	The surfaces of adjoining bones are affected, resulting in arthritis of the wrist.

Treatment:

In its early stages, Kienböck’s disease may be difficult to diagnose because the symptoms are so similar to those of a sprained wrist and radiographic findings are often negative. Splinting or casting the wrist for two to three weeks is often attempted initially, as well as anti-inflammatory medications such as aspirin or ibuprofen for pain relief.

Surgical options include bone grafting, bone leveling, proximal row carpectomy and eventually fusion procedures, but none are curative.

References:

1. Chung KC, Spilson MS, Kim MH. Is negative ulnar variance a risk factor for Kienbock's disease? A meta-analysis. Ann Plast Surg. 2001 Nov;47(5):494-9.
2. The Kienböck Disease Information Center