AVASCULAR NECROSIS (AVN)
WHAT IS IT?
Avascular necrosis refers to a condition in which cellular death occurs within the bone due to compromised blood flow. As the disease progresses, it leads to deformation of bone and eventual collapse and fracture. The condition can often arise following trauma (such as fracture or dislocation), especially when such trauma occurs to a bone or joint that already has poor blood supply. Bones that are at highest risk for AVN due to their naturally poor blood supply include the talus of the ankle, scaphoid of the wrist and femoral head of the hip.
In addition to trauma, the disease is also associated with following risk factors:
In addition to trauma, the disease is also associated with following risk factors:
- Long term corticosteroid use
- Excessive alcohol intake
- Biphosphonate use (for increased bone density)
- Kidney organ transplant
- Diabetes
- HIV/AIDS
- Systemic lupus erythematosus
- Sickle cell anemia
Symptoms
AVN often presents as slowly progressing, vague pain in and around the hip. Pain may be localized to the groin, thigh or buttock. It often begins as only being painful while bearing weight on the affected limb, but as the disease progresses, patients will become symptomatic at rest as well.
how is it treated?
Unfortunately, conservative management such as activity modification or physical therapy is ineffective in treating this disease. Without appropriate medical intervention, the disease will progress until complete destruction of the bone occurs. Depending on how far the disease has progressed, there are different surgical options.
For early stage AVN (prior to femoral head collapse), the following procedures may be indicated:
Another treatment option that provides promising results is hyperbaric oxygen therapy (HBOT). This treatment requires the patient to lay in a pressurized chamber of 2.4 atmospheres (sea level is equal to 1 atmosphere of pressure) while breathing in 100% oxygen. This saturates the plasma with oxygen and increases the partial pressure of oxygen within the blood stream, which causes a high pressure gradient for oxygen to be transported into the body's tissues. In doing so, areas of the body with poor blood flow now have a higher oxygen uptake. It is believed that with this higher uptake, healing is accelerated and new blood vessel growth is promoted. Below are some articles regarding the efficacy of HBOT in the treatment of AVN in the hip.
For early stage AVN (prior to femoral head collapse), the following procedures may be indicated:
- Core Decompression- Performed arthroscopically by drilling into the necrotic zone to decrease intramedullary pressure. It is believed that reducing the pressure within the damaged bone will prevent further ischemia and progressive joint destruction.
- Bone Grafting- Often performed with core decompression. A vascularized segment of bone (usually from the fibula) that is well vascularized is inserted in the necrotic zone to stimulate re-growth and vascularization.
Another treatment option that provides promising results is hyperbaric oxygen therapy (HBOT). This treatment requires the patient to lay in a pressurized chamber of 2.4 atmospheres (sea level is equal to 1 atmosphere of pressure) while breathing in 100% oxygen. This saturates the plasma with oxygen and increases the partial pressure of oxygen within the blood stream, which causes a high pressure gradient for oxygen to be transported into the body's tissues. In doing so, areas of the body with poor blood flow now have a higher oxygen uptake. It is believed that with this higher uptake, healing is accelerated and new blood vessel growth is promoted. Below are some articles regarding the efficacy of HBOT in the treatment of AVN in the hip.
hbo_femoral_head_necrosis.pdf | |
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hyperbaric-oxygen-for-stage-i-and-ii-femoral-head-osteonecrosis.pdf | |
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