Avascular Necrosis (AVN)
This is a condition affecting the Hip, Knee or Shoulder that can cause pain and joint damage. It occurs when an area of the joint loses its blood supply and some of the supportive bone in the joint undergoes bone death. Initially, there can be inflammation and swelling in the bone that causes pain. Later, as the body attempts to heal the dead bone, some of the bone may become soft and collapse and flatten beneath the overlying cartilage. The joint cartilage is no longer smooth. The joint becomes painful when the roughened, irregular surfaces move across each other.
Certain factors such as heavy alcohol use, sickle cell anemia, scuba diving, bone marrow storage diseases, and prolonged high steroid doses can all predispose one to having AVN. However, about fifty percent of cases are ‘idiopathic’ – meaning no identifiable cause is present.
The hip is affected most often, followed by the shoulder and knee.
Diagnosis can be made by plain x-rays, but often MRI scan is required to find it in earlier stages.
Treatment of early AVN, before there is any collapse of the joint surface, is with a ‘venting procedure’. This is also termed a ‘core decompression’ of the involved bone.
This entails a brief procedure under anesthesia during which a drill hole tunnel is placed into the involved area of the bone. The tunnel reaches the involved area by a pathway that avoids damage to the joint surfaces. Pain relief occurs by the tunnel relieving the pressure that has built up in the affected area. By relieving this pressure, further bone death is prevented.
In advanced AVN, when the bone surface has collapsed, then conservative treatment involves unloading the joint with walker, crutches or cane and modifying ones activities. Anti-inflammatories, Tylenol, pain medications may also help.
When the pain and dysfunction is too great then some form of arthroplasty is recommended for the joint. Often the most durable solution is a Total Joint Replacement.