Osteomyelitis

Osteomyelitis is infection in the bone.

Incidence; Causes and Development; Contributing Risk Factors

Osteomyelitis can occur in anyone, but different types of bacteria typically affect different age groups.  In children, the ends of the long bones in the arms and legs are usually involved; in adults it is more often the spine, feet or pelvis.

Osteomyelitis is usually caused when bacteria from an existing infection travel through the bloodstream into the bone, causing further infection there.  Existing infections might be an open wound over the bone, pneumonia, or UTI.  Another cause of osteomyelitis is a fractured bone that punctures the skin and is exposed to bacteria.  Surgery or injection around a bone can also expose the bone to infectious bacteria.

Acute osteomyelitis is generally of rapid onset, accompanied by the usual symptoms of pain, fever, and stiffness.  The cause is usually obvious, for example an injury that breaks the skin, surgery, or other skin wounds.

Chronic osteomyelitis is of slower onset and often results from a previous infection despite multiple courses of antibiotics.

Risk of osteomyelitis is increased by peripheral vascular disease, peripheral neuropathy, diabetes, a weakened immune system, cancer, chronic steroid use, sickle cell disease, HIV, hemodialysis, intravenous drug use, and old age.

Signs and Symptoms

Signs and symptoms of osteomyelitis are vary greatly and include:

• Fever or chills
• Pain and tenderness in the affected area
• Swelling, warmth and redness in the affected area
• Inability to use or bear weight with the affected limb
• Stiffness
• Nausea
• (In young children:) Irritability or lethargy
• (In people with diabetes, peripheral neuropathy, or peripheral vascular disease:) An area of skin breakdown that is worsening or not healing.  This may be their only symptom.
• Discharge at the site of infection

Diagnosis and Tests

Osteomyelitis is sometimes asymptomatic, or has symptoms common to many other conditions.  Diagnosis begins with a complete medical history and physical examination.  The physical examination will look for areas of tenderness, redness, swelling, decreased or painful range of motion, and open sores.

Blood tests will indicate whether your body is fighting an infection.  Diagnostic laboratory testing includes a complete blood count (CBC), the erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and blood cultures.  If an infection is indicated then its location needs to be narrowed down.

X-rays, bone scans, CT scans, MRIs, and ultrasound are imaging techniques that can help identify the site of bone changes caused by osteomyelitis.  Unless the infection has already been present for several weeks, X-rays may not be detailed enough to detect the bone damage.

Once a likely site of infection has been identified, a bone biopsy will identify the specific bacteria that are present.  A culture of this sample should indicate the best choice of antibiotic treatment.

Treatment and Prevention

Hospitalization is usually necessary.  Osteomyelitis can usually be treated with antibiotics and pain medications over the course of 4 to 8 weeks.

Surgery may be necessary if an abscess needs to be drained.  Damaged soft tissue, bone and foreign objects need to be removed, and blood flow restored.  To prevent a serious infection from spreading to other parts of the body, amputation of the affected limb may be necessary as a last resort.

Prognosis; Complications

Patients generally make a full recovery without complications.

Delaying diagnosis or treatment can result in severe damage to the bone or surrounding soft tissues, leading to permanent disability and higher risk of reoccurrence.