Osteomyelitis is an infection of the bone. It is a rare but serious condition. Bones can become infected in many ways: Infection in one part of the body may spread through the bloodstream into the bone, or an open fracture or surgery may expose the bone to infection. Around 80 percent of cases develop because of an open wound. Symptoms include deep pain and muscle spasms in the inflammation area as well as fever. Bone infections commonly affect the long bones in the leg and upper arm, the spine, and the pelvis. In the past, it was difficult to treat osteomyelitis. But now, aggressive treatment can often save the infected bone and stem the spread of infection. Osteomyelitis is estimated to affect 2 out of every 10,000 people in the United States at some time.
What causes osteomyelitis?
Many organisms, most commonly Staphylococcus aureus, travel through the bloodstream and can cause a bone infection. An infection may begin in one area of the body and spread to the bones via the blood stream.
Organisms that invade a severe injury, deep cut, or wound can also cause infections in nearby bones. Bacteria can enter your system at a surgical site, such as the site of a hip replacement or bone fracture repair. When your bone breaks, bacteria can invade the bone, leading to osteomyelitis.
The most common cause of bone infections is S. aureus bacteria. These bacteria commonly appear on the skin but don’t always cause health problems. However, the bacteria can overpower an immune system that’s weakened by disease and illness. These bacteria can also cause infections in injured areas.
Signs and symptoms of osteomyelitis can vary greatly. In children, osteomyelitis most often occurs more quickly. Osteomyelitis in children is most likely caused by bacteria that travel through the bloodstream and eventually spread to the bone.
In adults, the symptoms and signs often develop more gradually and include fever, chills, irritability, swelling or redness over the infected bone, drainage of pus, stiffness, and nausea. In people with diabetes, peripheral neuropathy, or peripheral vascular disease, there may be no pain or fever. The only sign may be an area of skin breakdown that is worsening or not healing. In osteomyelitis of the spine (vertebral osteomyelitis) or the spinal discs (discitis), the only symptom may be back pain.
How is osteomyelitis diagnosed?
Your doctor may use several methods to diagnose your condition if you have any symptoms of a bone infection. They will perform a physical exam to check for swelling, pain, and discoloration. Your doctor may also order lab and diagnostic tests to determine the exact location and extent of the infection. It’s likely your doctor will order a blood test to check for the organisms causing the infection. Other tests to check for the bacteria are throat swabs, urine cultures, and stool analyses. The stool culture is an example of a stool analysis.
Another possible test is a bone scan, which reveals the cellular and metabolic activity in your bones. It uses a type of radioactive substance to highlight the bone tissue. If the bone scan doesn’t provide enough information, you may need an MRI scan. In some cases, a bone biopsy may be necessary. However, a simple bone X-ray may be enough for your doctor to determine the treatment that’s right for you.
Figuring out if a person has osteomyelitis is the first step in treatment. Doctors rely on X-rays, blood tests, MRI, and bone scans to get a picture of what's going on. A bone biopsy is necessary to confirm a diagnosis of osteomyelitis. This also helps determine the type of organism, typically bacteria, causing the infection so the right medication can be prescribed.
Most cases of osteomyelitis are treatable. Chronic infections of the bone, however, may take longer to treat and heal, especially if they require surgery. Treatment should be aggressive because an amputation can become necessary in some severe cases. The outlook for this condition is good if the infection is treated on time.