Osteonecrosis Jillian Oviedo

Osteonecrosis (ON) i.e. Avascular Necrosis translates to bone death, which results from loss of blood supply to the afflicted bone(s), whether temporary or permanent. The bone tissue collapses and dies due to the resulting lack of nutrients and inability to rid of waste. It usually involves the epiphysis of long bones, and it commonly affects the femoral and humeral heads, femoral condyles, and sometimes the jaw, and carpals. It is especially common in the hip. The result is bone destruction, pain, and loss of joint function.

1. Osteonecrosis of the hip (http://www.ijoonline.com/articles/2015/49/1/images/IndianJOrthop_2015_49_1_28_143911_f5.JPG)

Prevalence

Osteonecrosis is relatively rare with fewer than 200,000 cases in the United States per year. Anyone can develop it, but it is most common in adults ranging from 30 to 60 years old, a relatively young age which can potentiate significant long-term consequences. It is chronic and can last for up to a lifetime since it is not known to affect life expectancy significantly. However, the exact prevalence of osteonecrosis in unknown. It is the cause of approximately 10% of hip replacements.

https://cdn.tutsplus.com/photo/uploads/legacy/363_oldgeneration/pt-seniors-46.jpg

Causes

No one has ever discerned what exactly causes the osteonecrosis, but common risk factors include:

  • Excessive consumption of alcohol, smoking, and basically just these lifestyle choices that can compromise the durability and structure of bones.
  • High dosage of steroid medications for a prolonged time, though it is only a link and the relationship between corticosteroids and osteonecrosis has not been discerned. Though it is not completely understood, the steroids could affect the way the body breaks down fatty substances which could lead to their accumulation in the blood vessels and compromising blood flow to the bone.
  • Serious trauma such as severe joint injuries which can sometimes result in compromisation of blood flow to the afflicted bone
  • Having diseases such as HIV infection, blood disorders (sickle cell anemia), lupus, arthritis, cancer, decompression disease. Steroid medications are used in some diseases, such as lupus, to decrease swelling and pain associated with inflammation, and this prolonged steroid exposure can help develop osteonecrosis. Blood diseases and come with inflammation and blood clots can damage the arteries and block blood flow to the bone.
  • Osteonecrosis of the mandible has been linked, but not proven to cause, to biophosphate consumption used to clean the bowel such as in constipation.

Patients usually come in with more than one risk factor, which adds to why it is so difficult to find out what exactly causes ON.

Blood vessels in a long bone (http://cancerhelpessentiahealth.org/Cancer_Types/adult_all_201024E2_01.html)

SYmptoms

When osteonecrosis starts and as well in its early states, it can be asymptomatic. But, with the progression of the disease patients have felt intense pain when they place pressure on the affected bone. The time between the first symptoms and the bone collapsation may be several months to more than a year. As bone damage worsens, patients may feel the following symptoms:

  • Pain in a joint that increases over time
  • Pain even at rest
  • Limited movement and motion
  • Limping (if it is occurring below the hips)

Progression

Even in the early stages of ON, x-rays appear normal, so diagnoses are usually made with an MRI. Eventually when the disease gets worse, we can see the affected bone on the x-ray. It is not actually the dead bone that can be seen, rather it is the healing of the living bone to the necrosis area. In the advanced stages, the dead bone beings to fail to work due to a series of microfractures of the bone and it will eventually reach the other side of the joint. In that case, major joint reconstruction is needed. Many patients do not go to the doctor's until the advanced stages, mainly because they do not know they have osteonecrosis.

Progression of necrotic femoral head (http://orthoinfo.aaos.org/topic.cfm?topic=a00216)
(http://nonf.org/nofbrochure/nonf-brochure.htm)

The x-rays show the progression of osteonecrosis on the femoral head. (A) shows no detectable changes to the head. (B) shows that the surface of the bone is still intact but there are some changes. (C) shows the surface of the femoral head beginning to collapse as ON progresses. (D) shows that the joint integrity is destroyed.

Normal femur anatomy (prohealthsys.com)

Treatments

Clinical treatment will be aimed at the underlying cause for the patient's osteonecrosis if it is known. For example, if problems with blood clotting is the cause the treatment in part will consist of clot-dissolving medicine.

Nonsurgical treatments can relieve the pain in the short-term but the disease is not curable. Some include:

  • Medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce pain and swelling. Blood thinners for problems with blood clotting may also be prescribed by the health care provider. If a patient is taking steroid medications for another disease, they may also have to start using cholesterol-lowering drugs to reduce the fatty substances in the blood vessels.
  • Taking weight off of the joint by limiting activity or using crutches. It could slow bone damage and allot healing time, and avoid surgery if paired with NSAIDs.
  • Range of motion exercises, which are exercises to see how far you can move your joints in different directions and improve joint function.

In most cases, surgical treatment is necessary, even with the nonsurgical treatments. Certain types of surgery are needed depending on where the osteonecrosis is and which bone it affects. Surgeries include:

  • Total joint replacement. This surgery replaces the joint with a prosthetic, manmade one.
  • Core decompression, which lowers the pressure inside the bone to increase blood flow and new blood vessels to form.
  • Bone graft, which takes healthy bone from another body part to replace the diseased bone
  • Osteotomy. This surgery cuts and reshapes the bone to change the alignment with the aim of reducing stress on the dysfunctional joint or bone.
Prosthetic hip joint (http://www.joshihospitalpvtltd.com/Joint_Replacement.html)

Bibliography

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