Risk Factors for Avascular Necrosis (AVN)
AVASCULAR NECROSIS (AVN) DEFINITION
AVN is a condition in which the blood supply to a region of bone is disrupted (avascular), rendering the bone without oxygen and nutrition, thus it dies (necrosis).
- Avascular Necrosis (AVN)
- Ischemic Necrosis
- Aseptic Necrosis
- Bone infarction (ischemic event)
- Bone infraction (non-displaced fracture)
The most frequent bones affected are the hip, shoulder, knee, wrist (lunate and scaphoid), and ankle/foot (talus,navicular, metatarsals)
AVN may be stable after the area of necrosis develops. It may progress, or the zone of necrosis may collapse and degenerate the joint. This may develop into a secondary arthritis. Prevention of this course is paramount to preventing joint replacement surgery.
- Corticosteroids (cortisone)
- Alcohol excess
- Rheumatoid Arthritis
- Sickle Cell Disease
- Gaucher’s (a genetic fat storage disorder)
- Caisson’s (decompression sickness or the bends)
- Prolonged exposure to great pressure (commercial or military divers)
- Trauma that disrupts the blood supply, such as a fracture will have significant ischemia.
- Lesser trauma may have a transitory ischemic effect, resulting in lesser degrees of osteonecrosis.
The exact mechanism of other risk factors have basis in theory. Proposed mechanisms in steroids and alcohol use are fatty infiltration of bone, which may impair blood flow resulting in ischemia.
AVN MECHANISM FOR REPAIR: STEM CELLS
Normal tissue that becomes ischemic or necrotic may have some ability to repair. This is dependent upon the extent of ischemia or necrosis.
Our own bodies stem cells initiate this repair, by the process of angiogenesis, and the formation of new bone growth. Both of these processes are under stem cell control for healing and reparative effect. A natural problem occurs when the zone of ischemia prevents the migration of stem cells, or adjacent stem cells are of insufficient numbers to overcome the area of necrosis. This problem may be countered by injecting the patients own stem cells directly into the area of ischemic necrosis. This process has been utilized for many different joints in an attempt to create healing and prevent secondary arthritis.
Dennis M. Lox, M.D., 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 Call to schedule your visit today.