Osteomyelitis

Cause

In case of osteomyelitis, pieces of bone tissue can die and get loose (sequesters). Around the affected bone parts, the infection can spread and cause abscesses. Osteomyelitis can occur in two ways:

• By bacteria that reach the bone via the bloodstream. Then there is an infection elsewhere in the body, that spreads via blood circulation.
• By bacteria that reach the bone through an open wound. For example, in case of an open fracture, after bone surgery, leg ulcers, bed sores or a diabetic foot.

There is an acute and a chronic form of osteomyelitis. The acute form is usually the result of an infection with the bacterium Staphylococcus aureus. This bacterium normally lives on the skin without doing any harm, but can enter blood circulation and infect bone tissue due to a wound, fracture, joint replacement or injection into a blood vessel with a contaminated needle. Acute osteomyelitis can also be caused by mycobacteria or (rarely) by the Escherichia coli bacterium. After infection with the bacterium, it usually takes four to ten days before the first symptoms occur.
Chronic osteomyelitis can also be caused by tuberculosis or in rare cases by a fungal infection. Acute osteomyelitis sometimes changes into the chronic form.
Young children and the elderly are at increased risk of developing this condition. Also in case of a reduced immune system, there is a higher risk, for example when using medicines that suppress the immune system (such as corticosteroids and chemotherapy). Drug users who use used needles are also more at risk of infection.

Symptoms

The most common symptom of osteomyelitis is pain in the infected bone. When moving or straining, the pain increases. The pain also increases upon touching the inflamed area. Other signs and symptoms are fever, redness, swelling and heat in the area above the affected bone. In case of chronic osteomyelitis, a fistula usually arises outwards. This is a channel between two body cavities, or between the skin and a body cavity. Along the fistula, pus can pass through.

Diagnosis

When osteomyelitis is assumed, the doctor may order an X-ray, scintigraphy or MRI scan in order to find the affected bone. If pus is formed, a sample from the bone (puncture) can be taken with a fine needle, so that the cause can be determined.

Treatment

As soon as the causative bacterium has been determined, treatment of osteomyelitis includes intravenous administration with an effective antibiotic for this bacterium. If, due to the osteomyelitis, tissue has died, surgery is often required to remove the dead tissue. Also drainage of abscesses is often necessary. Strings of beads with antibiotics are sometimes left in the wound in order to be able to locally administer a high concentration of this medication for a long time.

Prognosis

The prognosis for people with osteomyelitis is usually good, only if they receive timely and appropriate treatment. However, chronic osteomyelitis sometimes develops. Weeks, months or even years later, an abscess can be formed in the bone again.

Considerations

• For each child with a high fever, that doesn’t want to move a leg or arm anymore, the possibility of osteomyelitis should be considered. The external symptoms, such as redness and swelling, usually come later.
• People who have an artificial joint or metal parts attached to a bone, should take preventive antibiotics before each operation, even in dental intervention. This is because they are at increased risk of infection with bacteria that are normally found in the mouth and in other parts of the body.

Facts

• Osteomyelitis was discovered in ancient times and did already occur with the mummies of ancient Egypt. The disease has also been described by the Greek doctor Hippocrates.
• The term ‘osteomyelitis’ is derived from the Greek words osteon (bone) and muelos (marrow). The suffix -itis indicates that it is an inflammation.
• The prevalence of osteomyelitis is unknown.