Osteomyelitis

Definition
Osteomyelitis is a serious infection in a bone, which can be acute (sudden and severe) or become chronic (long term).

Causes/associated factors
Osteomyelitis is an uncommon condition that develops when bacteria or, infrequently, fungi enter a bone. The bacteria most often responsible for osteomyelitis include Staphylococcus aureus, Streptococcus, E. coli, Haemophilus influenzae and Pseudomonas. They travel to the bone either from a nearby infection or trauma site, or through the bloodstream from an infection elsewhere in the body. Osteomyelitis can occur at any age, but it's diagnosed more frequently in children.
Children are more likely to develop osteomyelitis from organisms carried in the blood to the long bones of the arms or legs. Adolescents and adults are more likely to develop osteomyelitis from a nearby site of infection or trauma, such as a wound, open fracture or surgery. Diabetes increases the risk of developing this type of osteomyelitis, especially in the feet. Diabetic neuropathy (a diabetes complication that affects the nervous system) causes loss of sensation in the feet and legs, which may allow an injury to go unnoticed. Poor circulation and a weakened immune response may allow an infection to develop and spread to the bones of the feet.

After age 45, adults are more likely to develop osteomyelitis in the bones of the back (the vertebrae). In these cases, the bacteria are carried through the bloodstream from distant infection sites, such as the lungs, urinary tract or skin.

Children who develop osteomyelitis are usually in good health before the infection. At any age, the risk for osteomyelitis increases if you:

have a weak immune system (such as those who have diabetes, HIV, AIDS or sickle cell disease)
have poor circulation (such as peripheral vascular disease)
use intravenous (IV) drugs
have an artificial joint (such as a hip or knee replacement)
have a urinary catheter or an IV line
Chronic osteomyelitis is characterized by a long illness that doesn't respond well to treatment or by recurrent episodes of infection. Prompt, appropriate treatment of acute osteomyelitis decreases the risk of developing chronic osteomyelitis.


Signs/symptoms
The symptoms of osteomyelitis may vary with age and source of infection. In infants, the infection may be severe by the time symptoms appear. Young children may have acute symptoms, but those who are already taking antibiotics for another infection (such as a respiratory or skin infection) may initially have few or mild symptoms. For older children and adults, symptoms may also appear mild at first. If osteomyelitis develops after trauma, the symptoms may be attributed to the injury rather than a developing bone infection.
Initial symptoms often include:

fever and chills (more common in children)
a general feeling of discomfort
pain over the affected bone
limping or reluctance to use the affected limb
localized swelling, warmth, redness and tenderness

Diagnosis
The doctor will ask questions about your medical history and do a physical exam. Blood tests and cultures may be done. You may also need one or more of the following tests:
X-rays of the affected bone (Evidence of bone destruction appears about two weeks after the infection begins.)
bone scans
magnetic resonance imaging (MRI, an imaging technique based on computer analysis of the body's response to magnetic fields)
computed tomography (CT scan -- a computer-generated, cross-sectional picture of internal body parts)
ultrasound (using sound waves to create an image of internal body parts)
needle or surgical biopsy (taking a sample of the tissue, bone or discharge for further evaluation)

Treatment
Prompt treatment of osteomyelitis helps prevent bone destruction. Therefore, treatment will begin immediately, sometimes even before test results arrive. Bone tissue is difficult to treat and requires intravenous antibiotics, which are often given for at least four to six weeks. In-home intravenous antibiotic therapy may be possible, depending on the type of antibiotic and your individual situation. It's sometimes possible to switch to oral antibiotics if the infection is responding well to the treatment, especially for children. Long-term oral antibiotic treatment is sometimes prescribed to treat chronic osteomyelitis.
Depending on the extent of the infection, the doctor may recommend surgical removal of the infected bone or tissue. After surgery, bedrest and restricted use of the affected area is typically recommended.


Complications
Acute osteomyelitis can lead to:
infection of the adjacent joint (septic arthritis)
infection in adjacent tissues, such as cellulitis (infection of the skin and surrounding tissue), brain abscess or pneumonia (a lung infection)
bacteremia (generalized infection)
death of large areas of bone, which often requires surgical removal of the affected areas
loosening of an artificial joint (in the case of a joint replacement)
for children, uneven limb development
Chronic infection in a weight-bearing bone, such as in the leg, can lead to loss of function. In extreme cases, amputation may be recommended, especially for those who have diabetes or impaired circulation.

With proper treatment, osteomyelitis is considered arrested rather than cured because the infection can recur, even years after a successful treatment. Bacteria lie dormant in the area of infection and can reactivate after a trauma or weakening of the immune system.


Pregnancy-specific information
Pregnancy is not a risk factor for osteomyelitis.

Senior-specific information
The risk of developing osteomyelitis (particularly in the spine) increases with age. Any disease that causes impaired circulation or feeling, such as atherosclerosis (hardening of the arteries) or diabetes, may contribute to the development of osteomyelitis in older adults.

Prevention
Seek prompt medical attention for any wound or sore that appears infected. If you have diabetes, be sure to take good care of your feet and check daily for possible sores. Pay careful attention to the symptoms of osteomyelitis, especially if you are at high risk for infection.