Kienbock’s Disease, also known as avascular necrosis of the lunate, is a condition in which the lunate bone—a central carpal bone in the wrist—loses its blood supply, resulting in the death of the bone. The lunate plays a critical role in wrist movement and stability, working together with adjacent bones in the proximal carpal row to form a flexible joint with the forearm. Damage to the lunate can lead to pain, stiffness, and eventually arthritis of the wrist. This disease most commonly affects men between the ages of 20 and 40 and rarely occurs in both wrists.

Causes

There is likely no single cause for the avascular necrosis of the lunate. Instead, its development may involve multiple factors related to blood supply, drainage, and inherent skeletal variations. Certain anatomical differences, such as a shorter ulna relative to the radius or an unusual shape of the lunate itself, may predispose an individual to the condition. Additionally, trauma—whether a single incident or repeated micro-injuries—may contribute in some cases. The disease is also more frequently seen in individuals with systemic conditions that affect blood flow, including lupus, sickle cell anemia, and cerebral palsy.

Signs and Symptoms

Patients typically present with wrist pain, often accompanied by tenderness directly over the lunate bone. As the condition progresses, the wrist may exhibit reduced range of motion and stiffness, with swelling sometimes present in the early stages. Initially, X-rays might appear normal despite symptoms, requiring more sensitive imaging techniques—such as Magnetic Resonance Imaging (MRI) or CT scans—to assess the blood supply and structure of the lunate. The disease is generally classified into four stages:

• Stage 1: The lunate loses its blood supply and becomes painful, although X-rays appear normal.
• Stage 2: The bone becomes denser on X-ray as it hardens from the lack of blood supply.
• Stage 3: The lunate begins to collapse and fragment.
• Stage 4: The lunate is severely collapsed, and degenerative changes occur in the surrounding bones, leading to arthritis.

Not every case advances through all these stages to severe arthritis, and the progression can be slow, occurring over many years.

Treatment

Treatment options are tailored to the severity and stage of the disease. In the early stages, conservative management—such as observation or immobilization—may be sufficient to alleviate symptoms. For more advanced cases, surgical interventions are often considered to reduce the stress on the lunate. These procedures may involve altering the biomechanics of the wrist by lengthening or shortening the forearm bones, fusing certain joints, or attempting to restore blood supply to the lunate through revascularization techniques that include a bone graft with an attached blood vessel. In cases where the joint relationship has significantly deteriorated, complete wrist fusion might be the preferred option. While hand therapy cannot reverse the disease, it plays an important role in relieving pain and improving function. Treatment outcomes vary widely and may require multiple approaches over several months to achieve the best possible result.