| Avascular necrosis is a condition that results from poor blood supply to a particular area of bone, causing bone death.
Avascular necrosis can result from trauma and damage to the blood vessels that supply oxygen to the bone. Other causes include an obstruction (embolism) of air or fat that blocks the blood flow through the blood vessels, abnormally thick blood (hypercoagulable state), and inflammation of the blood vessel walls (vasculitis).
Avascular necrosis represents the final common pathway of several diseases and conditions that damage bone, such as femoral neck fracture (hip AVN), dislocation of the lunate (lunate AVN), scaphoid fracture (scaphoid AVN), talar neck fracture (AVN of the dome of the talus), pancreatitis, Cushing's syndrome, Gaucher disease, sickle cell disease, systemic lupus erythematosus, alcoholism, steroid usage, and radiation exposure. These conditions result in impaired blood supply to the bone tissue, which ultimately causes death (necrosis) of the bone.
The condition also sometimes occurs in areas of segmental fracture. The hip is the most common site of avascular necrosis and often affects both femoral heads (i.e., it is bilateral).Risk: Avascular necrosis is most common in young men. The male to female ratio is 8 to 1. Affected individuals are usually younger than 50. Incidence and Prevalence: In the case of femoral neck fracture, the incidence of avascular necrosis can be as high as 40% (Marx 647). |
Source: Medical Disability Advisor
| History: Individuals may report stiffness, joint pain after healing a fracture, or joint pain without associated trauma. Pain may be worse at night and after activity. Physical exam: Pain is evident with active and passive motion. Individual typically has limited range of motion, muscle disuse atrophy, and weakness around the joint. Tests: Bone scans and MRI are used to locate and evaluate early signs of avascular necrosis. Routine joint x-rays reveal bony changes in later stages of the disease. |
Source: Medical Disability Advisor
| The treatment of avascular necrosis is critically dependent on the stage of the condition at diagnosis and on which joint is involved. Early avascular necrosis (before x-ray changes are evident) can be treated with a surgical procedure called core decompression. The procedure involves removing a core of bone from the involved area and, in some cases, grafting new bone into the area. The purpose of the bone graft is to promote formation of new blood supply to preserve the bone.
Later stages of avascular necrosis (when x-ray changes have occurred) inevitably progress to a seriously damaged bone and/or joint that requires arthroplasty or joint replacement surgery. |
Source: Medical Disability Advisor
| Overall, early diagnosis and treatment of avascular necrosis may lead to a favorable outcome. The amount of bone involved and the presence or absence of joint surface collapse greatly affect outcome.
The core decompression procedure is frequently successful (improvement in blood supply and prevention of progressive bone destruction) in the very early stages of the disease, but for more advanced stages, the outcome is much less predictable.
Joint replacement surgery is successful in a high percentage of cases. |
Source: Medical Disability Advisor
| The underlying cause of avascular necrosis (i.e., trauma, damage to blood vessels, poor circulation, abnormally thick blood, and inflammation of blood vessel walls) can complicate treatment. Avascular necrosis can also cause fracture and osteoarthritis. A late-stage complication of the disorder is a flattening of (collapse) the femoral head, the upper part of the thighbone (femur) that forms the ball portion of the hip joint. Collapse of the femoral head is followed by narrowed joint space and osteoarthritic changes in the opposing bones of the joint. |
Source: Medical Disability Advisor
| Individuals may have limited use of the affected extremity. For example, in avascular necrosis of the hip, crutches, a brace, walker, or wheelchair may be required. Frequent rest periods and modification of tasks to relieve stress on affected joints is an important treatment component. Individuals with a total hip replacement should avoid heavy work. |
Source: Medical Disability Advisor
| If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case. Regarding diagnosis:
- If symptomatic, does individual have pain after healing of fracture, stiffness, or joint pain without associated trauma?
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Is pain worse at night and after activity?
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Is pain evident with active and passive motion? Does individual have limited range of motion, muscle disuse atrophy, and weakness around joint?
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Were signs of avascular necrosis seen on x-ray, bone scan, or MRI?
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If diagnosis is uncertain, were other conditions with similar symptoms, such as osteoporosis, osteoarthritis, Paget's disease of the bone, and stress fracture, ruled out?
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Would individual benefit from consultation with specialist (orthopedic surgeon)?
Regarding treatment:
- Was treatment appropriate for stage of avascular necrosis (core decompression, bone graft or joint replacement)? Was joint replacement required?
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Was physical rehabilitation recommended? Was individual compliant with rehabilitation recommendations? If not, are there barriers to participation that could be addressed (insurance limits, transportation, lack of motivation)?
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If systemic disease such as SLE or pancreatitis is associated with development of avascular necrosis, was it addressed in treatment plan?
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Was treatment initiated in early or advanced stage of avascular necrosis?
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What type of surgical intervention was performed? Has adequate time elapsed for recovery from surgical procedure?
Regarding prognosis:
- Was avascular necrosis diagnosed and treated early?
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If surgery was necessary, was it successful?
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Did individual have any other conditions (circulatory disturbances, immune suppression) or complications (fractures, bone compression, or osteoarthritis) that may have impacted recovery?
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Source: Medical Disability Advisor
| Marx, J. A., et al., eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 5th ed. St. Louis: Mosby, Inc., 2002. |
Source: Medical Disability Advisor
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