Medical Definition of Avascular necrosis
Avascular necrosis: A condition in which poor blood supply to an area of bone leads to bone death. Abbreviated AVN. Also known as aseptic necrosis and osteonecrosis.
avascular necrosis Death of a tissue, especially bone, as a result of deprivation of its blood supply. Avascular necrosis of bone is often referred to as osteonecrosis.
Medical Definition of avascular
: having few or no blood vessels the lens is a very avascular structure avascular necrosis
The death of cells, tissues, or organs. Necrosis may be caused by insufficient blood supply, pathogenic microorganisms, physical agents such as trauma.
Necrosis affecting only the outer layers of bone or any tissue.
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Related to coagulation necrosis: coagulative, liquefaction necrosis, Necrotic tissue
necrosis [nĕ-kro´sis, ne-kro´sis] (Gr.)
the morphological changes indicative of cell death caused by enzymatic degradation.
aseptic necrosis necrosis without infection or inflammation.
central necrosis necrosis affecting the central portion of an affected bone, cell, or lobule of the liver.
Glossary of terms used in Avascular Necrosis –Osteonecrosis
Acetabulum – In the pelvis the hip socket is called the acetabulum and forms a deep cup that surrounds the ball or femoral head of the upper thigh bone.
Acute pain – Pain that is rapid to develop, and for a shorter duration than Chronic pain.
Ref – Wikipedia
Analgesic – A member of a group of drugs to give relief from pain.
Arthroplasty – Surgical repair of joint., also referred to as joint replacement. The affected bone is removed and replaced with an artificial joint. This treatment may be needed in the late stages of AVN, or when a joint has collapsed.
Articular cartilage – White smooth tissue that covers the ends of bones in joints. It enables bones in a joint to glide over one another with very little friction, allowing easy movement. See Cartilage
Aseptic Necrosis – Another name for Avascular Necrosis or Osteonecrosis.
Asymptomatic – A disease is considered Asymptomatic if a patent is a carrier for a disease or infection but experiences no symptoms. A condition might be considered Asymptomatic if it fails to show the noticeable symptoms of which it is usually associated. The term clinically silent is also used.
Atherosclerosis – Condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol.
Ref – Wikipedia
Avascular – Having few or no blood cells.
Ref – Encyclopaedia Britannica
Bone Marrow Edema – Only cited since 1988 after the introduction of MRI scans – is bruising of the bone or additional fluid (water) content in the bone marrow. This condition often accompanies avascular necrosis. On the MRI image it is shown as light areas of the bone which should be seen as dark.
Bone Infarct – Bone Infarct is another name for osteonecrosis . It’s a more descriptive term for what has happened, a blockage of blood circulation leading to the death of part of the bone.
Bilaterally – avascular necrosis in both sides -in both hips, or both knees etc.
BRONJ – Biphosphonate-Related OsteoNecrosis of the Jaw (BRONJ). This usually only occurs in people receiving high dose intravenous biphosphonate injections for bone cancers, and is often associated with a dental operation. If taking biphosphonates it is important to inform your dentist and to take extra care with dental hygiene.
Cartilage – Flexible tissue between the joint bones. It is not as hard and rigid as bone, but is stiffer and less flexible than muscle.
Caisson disease – Name given to a variety of symptoms suffered by a person exposed to a reduction in the pressure surrounding their body. Typically it occurs when a person subjected to great atmospheric pressure suddenly has that pressure removed – as when a scuba diver returns rapidly to the surface after a long submerged period. Also known as Barotrauma.
Chronic pain – This is pain that has lasted for a long time, the distinction between acute and chronic pain has traditionally been determined as Acute pain lasts for 30 days while Chronic pain last much longer.
Condyle – Smooth surface area at the end of a bone forming part of a joint with another bone.
Corticosteroid – Corticosteroids, more often known as steroids, are an anti-inflammatory medicine prescribed for a wide range of conditions.
Diabetes – A group of diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced. This high blood sugar produces the classical symptoms of frequent urination, increased thirst and increased hunger.
Diaphysis – Shaft of the bone.
Distal – The more (or most) distant of two (or more) things. For example, the distal end of the femur (the thigh bone) is the end down by the knee; the end more distant from the torso.
Ellipsoidal – Joint that can move in two planes, example wrist and ankle.
Endothelial NOS (eNOS), also known as nitric oxide synthase 3 (NOS3) or constitutive NOS (cNOS), is an enzyme that in humans is encoded by the NOS3 gene located in the 7q35-7q36 region of chromosome 7. This enzyme is one of three isoforms that synthesize nitric oxide (NO), a small gaseous and lipophilic molecule that participates in several biological processes. The other isoforms include neuronal nitric oxide synthase (nNOS), which is constitutively expressed in specific neurons of the brain and inducible nitric oxide synthase (iNOS), whose expression is typically induced in inflammatory diseases. eNOS is primarily responsible for the generation of NO in the vascular endothelium, a monolayer of flat cells lining the interior surface of blood vessels, at the interface between circulating blood in the lumen and the remainder of the vessel wall. NO produced by eNOS in the vascular endothelium plays crucial roles in regulating vascular tone, cellular proliferation, leukocyte adhesion, and platelet aggregation. Therefore, a functional eNOS is essential for a healthy cardiovascular system.
Epiphysis – Ends of the bone.
Factor V (pronounced factor five) is a protein of the coagulation system, rarely referred to as proaccelerin or labile factor. In contrast to most other coagulation factors, it is not enzymatically active but functions as a cofactor. Deficiency leads to predisposition for hemorrhage, while some mutations (most notably factor V Leiden) predispose for thrombosis.
Factor VIII (FVIII) is an essential blood-clotting protein, also known as anti-hemophilic factor (AHF). In humans, factor VIII is encoded by the F8 gene. Defects in this gene result in hemophilia A, a recessive X-linked coagulation disorder
Femoral head – The ball at the upper end of the thigh bone that sits inside the hip socket or acetabulum.
Gaucher’s disease – A disease in which a fatty substance accumulates in cells and certain organs. Symptoms may include enlarged spleen and liver, liver malfunction, skeletal disorders and bone lesions that may be painful, severe neurologic complications, swelling of lymph nodes and (occasionally) adjacent joints, distended abdomen, a brownish tint to the skin, anemia, low blood platelets and yellow fatty deposits on the white of the eye. Persons affected most seriously may also be more susceptible to infection.
Gout – Condition usually characterized by recurrent attacks of acute inflammatory arthritis – a red, tender, hot, swollen joint. The joint at the base of the big toe is the most commonly affected (approximately 50% of cases). It is caused by elevated levels of uric acid in the blood which crystallizes, and the crystals are deposited in joints, tendons, and surrounding tissues.
Idiopathic – An adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause.
In Greek; Idios translates to one’s own and Pathic translates to suffering or disease; so together becomes “a disease of it’s own” or “it comes from nothing” and medical jargon for “we don’t know what the cause is”.
Infarct – Bone infarct is another name for AVN. It’s a more descriptive term for what has happened, a blockage of blood circulation leading to the death of part of the bone.
Ischemic – Restriction in blood supply to tissue, causing a shortage of oxygen and glucose needed to keep tissue alive.
Legg Perthes disease – Avascular Necrosis in young children and can lead to Osteoarthritis in adults, also known as Calve Perthes or Perthes Disease
Lesions – Any abnormality in the tissue of an organism, for AVN we mean the bone structure at the joint site has started to break away. Usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.
Ligaments – Fibrous tissue that connects bones to other bones.
Medial Condyle – Inner side of the lower extremity of the femur (thigh), see Condyle.
MRI – Magnetic Resonance Imaging, is a medical imaging technique used in radiology to visualise internal structures of the body in detail. MRI makes the use of the property of nuclear magnetic resonance (NMR) to image nuclei of atoms inside the body.
MRI provides good contrast images between the different soft tissues inside the body, which makes it especially useful in imaging the brain, muscles, heart and cancers; compared with other medical imaging techniques such as computed tomography (CT) or X-rays. Unlike CT scans or traditional X-rays, MRI does not use ionizing radiation.
MTHFR is an enzyme that adds a methyl group to folic acid to make it usable by the body. The MTHFR gene produces this enzyme that is necessary for properly using vitamin B9. This enzyme is also important for converting homocysteine into methionine, which the body needs for proper metabolism and muscle growth and which is needed for glutathione creation . The process of methylation also involves the enzyme from the MTHFR gene, so those with a mutation may have trouble effectively eliminating toxins from the body.
Multifocal – Having many focal points. With regard to avascular necrosis AVN it means that it has affected many different joints in the body,. For example the hips, shoulders, knees and jaw.
Multilateral – Having many focal points. With regard to avascular necrosis AVN it means that it has affected many different joints in the body,. For example the hips, shoulders, knees and jaw.
Necrosis – Death of living tissue.
Oedema – also known as edema – Bone marrow oedema occurs when excess fluid build up in the bone marrow and causes swelling. Caused by the bodies reaction to a trauma or other condition. Symptoms are pain and/or swelling at the bone site.
Osteoarthritis – degradation of a joint from partial loss of cartilage and damage to the bone joint surface.
Osteonecrosis – Another name for Avascular Necrosis.
Osteoradionecrosis ORN – Another name for Avascular Necrosis caused by radiotherapy.
Osteopenia – Condition where bone mineral density is lower than normal. It is considered by many doctors to be a precursor to osteoporosis. However, not every person diagnosed with osteopenia will develop osteoporosis.
Osteophytes – Commonly referred to as bone spurs, they are bony projections that form along the joint margins.
Osteoporosis – Condition of fragile bones.
Osteotomy – Osteotomy surgery involves cutting and re-aligning the bone (usually shin bone/tibia) in order to re-distribute the weight going through the knee. Re-alignement can be achieved by either taking a slice of bone out of the tibia (shin bone) or femur (thigh bone) close to the knee joint (closing wedge) or opening a gap in the bone (opening wedge).
A hip osteotomy is a surgical procedure in which the bones of the hip joint are cut, reoriented, and fixed in a new position. Healthy cartilage is placed in the weight-bearing area of the joint, followed by reconstruction of the joint in a more normal position.
Perthes disease – Avascular Necrosis (AVN) in young children and can lead to Osteoarthritis in adults also known as Legg Calve Perthes or Calve Perthes Disease.
Sacrum – Large triangular bone at the base of the spine and at the upper and back part of the pelvic cavity.
Sagittal – Imaginary line, used in MRI scans.
Sclerosis – Osteosclerosis, condition where bone density is significantly increased.
Sickle cell disease Sickle cell disease is a group of disorders that affects haemoglobin, the molecule in red blood cells that delivers oxygen to cells throughout the body. People with this disorder have atypical haemoglobin molecules called haemoglobin S, which can distort red blood cells into a sickle, or crescent, shape.
Signs and symptoms of sickle cell disease usually begin in early childhood. Characteristic features of this disorder include a low number of red blood cells (anaemia), repeated infections, and periodic episodes of pain. The severity of symptoms varies from person to person. Some people have mild symptoms, while others are frequently hospitalised for more serious complications.
SPONK – SPontaneous OsteoNecrosis of the Knee, a type of AVN or osteonecrosis specifically of the knee, either femur or tibia, and spontaneous means it occurred without an obvious cause
Subchondral – Below the cartilage.
Systemic lupus erythematosus – (SLE), often known just as lupus, is an autoimmune disease where your immune system produces antibodies that attack your body’s own tissues, causing inflammation. Lupus usually affects your skin and joints, but it may also involve your heart or kidneys, when the effects can be severe. SLE isn’t the same as discoid lupus, which only affects the skin.
Synovial – Synovial tissue is found around the tendons (bands of fibre that connect muscle to bone), and can form bursa (fluid filled cushioning pouches or sacs found in spaces between tendons, ligaments and bones) found in the area of joints.
Synovial fluid is the clear, viscid, lubricating fluid secreted by synovial membranes.
Ref – Synovial Sarcoma Survivors Network
Trabecular – The inner part of the bone. The spongy bone, as it is frequently called, is highly vascular and is responsible for blood cell production. The trabecula bone contains the red bone marrow that is responsible for this blood cell production.
Ref – Trabeclularbone.org
UKR – Unicompartmental Knee Replacement, or partial knee replacement.
Vertebrae – The Vertebral Column (Spinal Column) supports the head and encloses the spinal cord.
The spinal column is comprised of 26 individual bones, these bones are referred to as vertebrae. The spinal column is divided into five (5) different areas containing groups of vertebrae, and are grouped as follows:
Seven (7) Cervical vertebrae in the neck.
Twelve (12) Thoracic vertebrae in the upper back corresponding to each pair of ribs.
Five (5) Lumbar vertebrae in the lower back.
Five (5) Sacral vertebrae which are fused together to form 1 bone called the sacrum.
Four (4) Coccygeal vertebrae that are fused together to form the coccyx or tailbone.
X-Ray – A form of radiation that can pass through solid and semi-solid substances. In carefully controlled doses, they can be used to capture images of the body’s internal structures.X-ray is a safe and painless procedure often used to produce images of the inside of the body.
It is a very effective way of looking at fractured bones, such as a broken arm or wrist.
An X-ray can also be used to examine organs and identify problems. For example, an X-ray will show up an infection in your lungs, such as pneumonia.
X-rays are also often used during therapeutic procedures, such as a coronary angioplasty, to help the surgeon guide equipment to the area being treated.
AVN is not always seen on an Xray