What is osteomyelitis?

Osteomyelitis is infection of the bone, usually by a pus-forming bacteria. All bacterial osteomyelitis starts as acute infection. If untreated or unsuccessfully treated after 6 weeks, by definition, it becomes chronic osteomyelitis.

What causes osteomyelitis?

Osteomyelitis is caused by bacteria, which enters the bone by injury (as by a sharp object or open fracture) or by the blood stream ( which is the more common mode of entry in children). In the discussion that follows, we will confine ourselves to infection from the blood stream - the hematogenous type.

The responsible bacteria differs in different age groups. In the neonate, the bacteria is usually Hemophilus influenzae. In older infants and children, it is often Staphylococcus aureus. The site of infection could be anywhere in the body, but most commonly in the metaphysis of long bones. The metaphysis of the long bone is that part of the body next to the growth area (or the epiphysis at either end of the long bone). So osteomyelitis tends to occur near the joints of the limbs.

What are the symptoms?

The child presents with acute pain near a major joint of the limb , associated with high fever. The typical patient looks sick. Blood tests often show elevated white blood cell count as well as high sedimentation rate and C-reactive protein. The high sedimentation rate and C-reactive protein indicates the body response to acute inflammation, and follow-up tests are good indicators of the progression of the disease and response to treatment. Blood culture is done to identify the responsible bacteria. Local aspiration of the site is also sometimes useful to identify the bacteria involved. X-rays are usually normal in the first 5 to 7days, until the periosteum (covering of the bone) is elevated by swelling or pus formation, when X-ray changes occur.

In cases where the diagnosis is in doubt, a radionuclide bone scan (Technetium) is helpful to clinch the diagnosis.

What does your doctor do about it?

When a diagnosis of osteomyelitis is made, the child should be admitted to the hospital and started on intravenous antibiotics immediately. A response, indicated by settling of the spiking fever and decrease in local pain and tenderness, should be obtained in 24 to 48 hours. If there is no response after this time, serious consideration should be given to surgically explore and decompress the osteomyelitis.

Intravenous antibiotics are given for about 3 weeks, followed by oral antibiotics for another 3 weeks. The intravenous line can be maintained by a PIC line, and the patient can be sent home after he has been stabilized with the PIC line to finish up his course of I.V. antibiotics.

What of the future?

If treated early and successfully, most patients respond well with no long term problems. If treated late, or if the patient is somehow immunologically deficient, long term problems of chronicity can be quite troublesome.