Keinbock Disease: Avascular Necrosis (AVN) or Osteonecrosis of the Lunate
Tampa, Saint Petersburg and Clearwater, Fl
Avascular Necrosis (AVN) of the lunate is also known as Keinbock disease. The lunate is a carpal bone in the wrist. Avascular Necrosis (AVN) is also sometimes referred to as aseptic necrosis, osteonecrosis, bone infarction and ischemic necrosis.
AVN occurs when the blood supply to a portion of bone is disrupted, and that section of bone dies, or becomes necrotic. AVN may occur commonly in the hip, shoulder, knee, or ankle. When it occurs in the wrist it may affect any bone, however most common are the carpal bones the scaphoid and lunate. When the lunate is involved it is referred to as Keinbock disease, after the Austrian radiologist who described it in 1910.
Keinbock disease occurs in men and women, yet with different patterns.
Men are typically young adults who receptively load their dominant hand. The repetitive stress is felt to be accumulated trauma which precipitates the AVN. Trauma is a known associated causative event for AVN. Women, are predominately afflicted in middle age, and it is found equally in both extremities. There is an association as well with negative ulnar variance on x-rays in 75% of cases.
Trauma has a high correlation with osteonecrosis or avascular necrosis. There are many theories to explain the association with other frequently noted disease states, yet the other descriptive term for the condition, ischemic necrosis may be very relevant in explaining Keinbock disease. The majority of lunates receive blood supply from multiple vessels. However, 30% receive blood supply from a single blood vessel. This may explain why trauma or another factor may more readily disrupt a single vessels blood supply, resulting in bone infarction or ischemic necrosis. Ischemia and avascular are synonymous terms for loss of blood supply. Without blood supply the bone will become necrotic or die.
Diagnosis and Treatment
The diagnosis of Keinbock disease is made on x-ray, bone scan or MRI. Different stages have been proposed based on x-ray progression. If the necrotic region of the bone that was without vasculature collapses, secondary arthritis may develop. The secondary arthritis of AVN is often what results in significant functional limitations. The joint loss that occurs as the result of the arthritis, is often what leads to surgical treatment in AVN. In other joints such as the shoulder, hip, and knee severe cases can result in joint replacement. These joints carry a better prognosis than replacing wrist or ankle bones, yet most patients desire conservative options.
Avascular necrosis has been treated with microfracturing the bone, to release bone marrow stem cells. This has been done in many different regions with success. This is a surgical procedure. A more conservative measure, directly injecting the patients stem cells (obtained from either bone marrow or adipose (fat) tissue) has also been used successfully in many reports.
Avascular necrosis (AVN) is a difficult condition, however if vascular supply can be returned bone may repair and regenerate. Minimizing secondary arthritis is important to protect the joint integrity.
Dennis M. Lox, MD, serves patients in the greater Tampa Bay area, including, Clearwater, St. Petersburg, Tampa, New Port Richey, Sarasota, Orlando and Spring Hill. He has been pleased to accommodate the needs of patients throughout Florida, the United States, the Western Hemisphere, and Europe, as well. Located in the 33765 and 33765 areas, our offices can be reached at (727) 462-5582 (Clearwater) and (727) 817-1909 (New Port Richey). Call to schedule your visit today.