Osteonecrosis often referred to as avascular necrosis (AVN) occurs when the blood flow to a region of bone becomes impaired (ischemia or avascular), this results in bone cell death (necrosis).
Any bone may be affected. It most commonly occurs in the hip. The knee and ankle are also frequently involved in the leg. While hip osteonecrosis can involve more than one joint, suspicion for knee osteonecrosis (AVN) must be considered when symptoms progress or knee pain arises. Trauma is the leading cause of AVN. Systemic related avascular necrosis can be seen in excessive corticosteroid use (cortisone) and alcohol use. Why some of these patients develop AVN while others exposed to corticosteroids or alcohol don not develop AVN is not understood.
Other potential risk factors include:
Sickle cell disease
The amount of bone cell death and location around the knee, will manifest in various ways. If the area of necrosis is islands of osteonecrosis not in proximity to the knee joint its course may be stable. If a larger zone of necrosis abuts the knee joint or is in the femoral condylar or tibial plateau it may collapse, leading to rapid knee joint degeneration.
This secondary arthritis is a frequent reason total knee replacement is recommended in osteonecrosis.
Conservation treatment options have included rest and non- weight bearing. These are often a wait and see approach. Patients are becoming more proactive with Regenerative Medicine procedures Platelet Rich Plasma (PRP) and Stem Cell Therapy for AVN.
The use of Regenerative Medicine, PRP and stem cells encompass using the patient’s own blood platelets and stem cells in an attempt to heal or stabilize the area of osteonecrosis.
The development of osteonecrosis or avascular necrosis in an athlete’s knee can signal the end of a sports career. Recommendations for total knee replacement as well, may derail a sports career. For these reasons Platelet Rich Plasma (PRP) and Stem Cell Therapy are viable treatment options for osteonecrosis (AVN) in some circumstances.