Some info on Avascular Necrosis/Osteonecrosis
Other risk factors for osteonecrosis include radiation therapy, chemotherapy, and organ transplantation (particularly kidney transplantation).
Osteonecrosis is also associated with a number of medical conditions, including
Cancer (chemo and radiation)
Blood disorders such as
Sickle cell disease,
Factor V Leiden
Gaucher’s disease, and
Caisson disease- Decompression sickness (DCS; also known as divers’ disease, the bends or caisson disease) describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurisation.
Also called Dysbaric
Bone Marrow Edema
osteomyelitis Inflammation of bone caused by infection
Homocysteine is an amino acid produced by the body.
Elevated homocysteine levels are linked to high concentrations of endothelial asymmetric dimethylarginine (ADMA); a chemical found in blood plasma. ADMA interferes with the synthesization of Nitric Oxide from L-Arginine.
Nitric Oxide is important in our bodies because it increases blood flow.
It also can occur in pregnancy
It is important for Osteonecrosis (Avascular Necrosis) sufferers to have their homocysteine levels checked because high homocysteine levels cause narrowing of the arteries and can lead to excessive blood clotting.
Vitamins B6, B12 and Folic acid are commonly taken to lower homocysteine levels.
To read about homocysteine click link
Plasminogen Activator Inhibitor-1 (PAI-1)
Who Is Likely to Develop Osteonecrosis?
Although osteonecrosis affects both men and women, it mainly affects men. However, in cases related to SLE, the disease mostly affects women.
It can occur in people of any age, from children to the elderly. However, it is more common in people in their thirties, forties, and fifties.
Although the pathophysiology of AVN is not fully understood, the final common pathway is interruption of blood flow to the bone.
AVN affects bones with a single terminal blood supply, such as the femoral head, carpals, talus, and humerus. These bones have limited collateral circulation. Interruption of the vascular supply and resultant necrosis of marrow, medullary bone, and cortex are theorized to be caused by the mechanisms listed below.
However, individual patients usually have more than one risk factor; this indicates that the pathogenesis of AVN is likely multifactorial.
* Vascular occlusion: This is characterized by the interruption of the extraosseous blood supply via factors such as direct trauma (eg, fracture, dislocation), nontraumatic stress, and stress fracture.
* Altered lipid metabolism: Animal studies have led to the hypothesis that increased levels of serum lipids leads to lipid deposition in the femoral head, causing femoral hypertension and ischemia.
Lipid-level–lowering drugs in animals reverse this process. Corticosteroid administration was associated with fat emboli in the femoral heads of rabbits.
* Intravascular coagulation: Disorders of the coagulation system have been implicated in the pathogenesis of AVN. Typically, it is a secondary event triggered by a familial thrombophilia, hypercholesterolemia, allograft organ rejection, other disorders (eg, infection, malignancy), or pregnancy.
* Healing process: Necrotic bone triggers a process of repair that includes osteoclasts, osteoblasts, histiocytes, and vascular elements. Osteoblasts build new bone on top of the dead bone, leading to a thick scar that prevents revascularization of the necrotic bone, with resultant abnormal joint remodeling and joint dysfunction.
* Primary cell death: Osteocyte death without other features of AVN has been seen in renal transplant patients, as well as in patients receiving steroids and those who consume significant amounts of alcohol.
* Mechanical stress: Animal studies have shown an association between increased weight bearing and an increased incidence of AVN of the femoral head.
The frequency of AVN depends on the site involved. The most common site is the hip; other locations include the carpals, talus, femur, metatarsal, mandible, and humerus. In the United States, approximately 15,000 new cases of AVN are reported each year. AVN accounts for more than 10% of total hip replacement surgeries performed in the United States. Most recently, 380 cases of osteonecrosis of the jaw associated with bisphosphonate use have been reported. Most patients with osteonecrosis of the jaw also had an ongoing malignancy and/or had undergone a recent dental procedure.
In most countries, the incidence and prevalence of AVN are unknown. A Japanese survey estimated that 2500-3300 cases of AVN of the hip occur each year; of these, 34.7% were due to corticosteroid use, 21.8% to alcohol abuse, and 37.1% to idiopathic mechanisms.
Data on mortality rates associated with AVN are not available. Most data involve AVN of the hip. Mortality rates are very low and vary based on the operative procedure used to treat AVN.
Morbidity rates are high and depend on the underlying cause. Morbidity rates associated with AVN of the hip are high; the prevalence of long-term disability is significant. Despite advances in orthopedic procedures, most patients with advanced AVN require more than one hemiarthroplasty or total hip replacement during their lifetime.
AVN has no racial predilection except for cases associated with sickle cell disease and hemoglobin S and SC disease, which predominantly occur in people of African and Mediterranean descent.
With the exception of AVN associated with systemic lupus erythematosus, AVN is more common in men, with an overall male-to-female ratio of 8:1.
AVN is a disease of middle age that most often occurs during the fourth or fifth decade of life and is bilateral in 55% of cases.
Surgical options include:
Bone grafts, which involve removing healthy bone from one part of the body and using it to replace the damaged bone
Osteotomy, a procedure that involves cutting the bone and changing its alignment to relieve stress on the bone or joint
Total joint replacement, which involves removing the damaged joint and replacing it with a synthetic joint
Core decompression, a procedure that involves removing part of the inside of the bone to relieve pressure and allow new blood vessels to form
Vascularized bone graft, a procedure that uses the patient’s own tissue to rebuild diseased or damaged hip joints; the surgeon first removes the bone with the poor blood supply from the hip and then replaces it with the blood-vessel-rich bone from another site, such as the fibula, the smaller bone located in the lower leg.
Knee brace/ crutches
Limited weight bearing
Stem Cell injections