Osteomyelitis and Septic Arthritis

What is osteomyelitis?
Osteomyelitis is an infection of a bone usually caused by bacteria and treatable with antibiotics. However, if an abscess has formed in the bone prior to or during treatment, surgery will be necessary. If the symptoms have been present for some time before treatment is started, an abscess may form and blood supply to the bone may be compromised. Therefore, osteomyelitis can be one the most difficult conditions an orthopaedic surgeon will manage.

How does osteomyelitis develop?
There are a number of factors that contribute to the development of osteomyelitis. Bacteria may spread to the bloodstream after simple events like brushing our teeth or through other sites such as infected bug bites; sinus, tonsil, or ear infections; or urinary tract infections. There is also some evidence that minor trauma may contribute to the localization of bacteria to certain places. The status of the immune system and the nutritional status of the child are other important factors that may contribute to a predisposition to infection.

What are some of the clinical findings associated with osteomyelitis?
The onset of the disease may be gradual or relatively sudden. Fever and pain are prominent symptoms that osteomyelitis has developed. Pain is usually sufficiently severe that a child will stop walking or stop using an arm or hand.

How is a child evaluated for osteomyelitis?

• Evaluation of a child who is ill and having pain is difficult. We try to find the area of the body that is causing the pain.
• Plain x-rays will not show an abnormality for 10-14 days. The x-rays that are made in evaluating a child for possible infection are often made to look for other problems such as fractures.
• Blood tests are done to look for evidence of inflammation and to culture the blood to look for any identifiable bacteria.
• Bone scans are tests done to identify abnormal areas of bone early in the infection.
• Aspiration of the bone is done to obtain specimens for bacterial culture and to determine if an abscess has formed.

What is the treatment for osteomyelitis?
If the evidence suggests that the child has osteomyelitis and does not have an abscess in the bone, antibiotics will be started. If the pain and fever decrease and the laboratory tests begin to return to normal, the antibiotics will be continued. If there is persistent fever and pain or if the lab tests are not returning to normal, then an abscess may have formed. Abscesses require surgical drainage in order for the infection to resolve. If the blood supply to the bone has been lost, the difficulty in management is compounded. Your physician will discuss the pertinent issues with you.

How long will my child be on antibiotics?
There is no set time for treatment with antibiotics. As one would imagine there are different degrees of severity, different bacteria, and different conditions of the patient that affect this judgment. In general, antibiotics are used until the patient’s temperature and the laboratory studies have returned to normal.

What is a septic arthritis?
Septic arthritis is an infection in the joint itself. Any joint can be affected, but the most commonly involved joints are the large joints such as the hip and knee. The causes of septic arthritis and the predisposing conditions are similar to those causing osteomyelitis. The difference is that most joint infections require surgery to prevent the joint from being damaged by the infection. This is considered a surgical emergency because the infection in the joint will cause the cartilage to die if it is not treated rapidly. The joint will usually be aspirated with a needle before any surgery. If the removed fluid has bacteria in it, then the joint will need to be opened surgically.