What Is Osteomyelitis?

Osteomyelitis (pronounced: os-tee-oh-my-uh-lie-tus) is a bone infection often caused by bacteria called Staphylococcus aureus (pronounced: sta-fuh-low-kah-kus are-ee-us). Depending on how the bone becomes infected and the age of the person, other types of bacteria can cause it, too. In kids and teens, osteomyelitis usually affects the long bones of the arms and legs.
Bacteria can infect bones in a number of ways. Bacteria can travel into the bone through the bloodstream from other infected areas in the body. This is called hematogenous (pronounced: heh-meh-tah-gen-us) (hema refers to the blood) osteomyelitis, and is the most common way that people get bone infections.
Another way is by direct infection, when bacteria enter the body's tissues through a wound and travel to the bone (like after an injury). Open fractures — breaks in the bone with the skin also open — are the injuries that most often develop osteomyelitis.
A bone also can become infected when the blood supply to that area of the bone is disrupted. This can happen in older people with atherosclerosis (pronounced: ath-uh-row-skluh-row-sis), which is a narrowing of the blood vessels, or in association with diabetes. Most infections of this kind occur in the toes or feet.


Signs and symptoms of osteomyelitis include:

• Fever or chills
• Irritability or lethargy in young children
• Pain in the area of the infection
• Swelling, warmth and redness over the area of the infection

Sometimes osteomyelitis causes no signs and symptoms or has signs and symptoms that are difficult to distinguish from other problems.

Causes Of osteomyelitis

Most cases of osteomyelitis are caused by staphylococcus bacteria, a type of germ commonly found on the skin or in the nose of even healthy individuals.
Germs can enter a bone in a variety of ways, including:

• Via the bloodstream. Germs in other parts of your body — for example, from pneumonia or a urinary tract infection — can travel through your bloodstream to a weakened spot in a bone. In children, osteomyelitis most commonly occurs in the softer areas, called growth plates, at either end of the long bones of the arms and legs.
• From a nearby infection. Severe puncture wounds can carry germs deep inside your body. If such an injury becomes infected, the germs can spread into a nearby bone.
• Direct contamination. This may occur if you have broken a bone so severely that part of it is sticking out through your skin. Direct contamination also can occur during surgeries to replace joints or repair fractures.

How is osteomyelitis diagnosed?

The diagnosis of osteomyelitis begins with a complete medical history and physical examination. During the medical history, the doctor may ask questions about recent infections elsewhere in the body, past medical history, medication usage, and family medical history.
The physical examination will look for areas of tenderness, redness, swelling, decreased or painful range of motion, and open sores.
Your doctor may then order various tests to help diagnose osteomyelitis. Several blood tests can be used to help determine if you have an infection in your body. These include a complete blood count (CBC), the erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and blood cultures. None of these is specific for osteomyelitis but rather they can suggest that there may be some infection in the body.
Imaging studies may be obtained of the involved bones. These can include plain radiographs (X-rays), bone scans, computed tomography (CT) scans, magnetic resonance imaging (MRIs), and ultrasounds. These imaging studies can help identify changes in the bones that occur with osteomyelitis.
After an area of bone is identified with possible osteomyelitis, a biopsy of the bone may be obtained to help determine precisely which bacteria are involved, and the culture of this can indicate the best choice for antibiotic treatment.

What is the treatment for osteomyelitis?

In many cases, osteomyelitis can be effectively treated with antibiotics and pain medications. If a biopsy is obtained, this can help guide the choice of the best antibiotic. In some cases, the affected area will be immobilized with a brace to reduce the pain and speed the treatment.
Sometimes, surgery may be necessary. If there is an area of localized bacteria (abscess), this may need to be opened, washed out, and drained. If there is damaged soft tissue or bone, this may need to be removed. If bone needs to be removed, it may need to be replaced with bone graft or stabilized during surgery.

What is the prognosis for osteomyelitis?

With early diagnosis and appropriate treatment, the prognosis for osteomyelitis is good. If there is a long delay in diagnosis or treatment, there can be severe damage to the bone or surrounding soft tissues that can lead to permanent deficits. Commonly, patients can make a full recovery without longstanding complications.

REFERENCES:
Christian, S., Kraas, J., Conway, W.F. "Musculoskeletal Infections." Semin Roentgenol 42 (2007): 92-101.
Hartwig, N.G. "How to Treat Acute Musculoskeletal Infections in Children." Adv Exp Med Biol 582 (2006): 191-200.
Sia, I.G., Baebari, E.F. "Infection and Musculoskeletal Conditions: Osteomyelitis." Best Pract Res Clin Rheumatol 20 (2006): 1065-1081.