Osteomyelitis

Overview

Osteomyelitis is an infection in a bone. Infections can reach a bone by traveling through the bloodstream or spreading from nearby tissue. Infections can also begin in the bone itself if an injury exposes the bone to germs.

Smokers and people with chronic health conditions, such as diabetes or kidney failure, are more at risk of developing osteomyelitis. People who have diabetes may develop osteomyelitis in their feet if they have foot ulcers.

Although once considered incurable, osteomyelitis can now be successfully treated. Most people need surgery to remove areas of the bone that have died. After surgery, strong intravenous antibiotics are typically needed.

Symptoms

Signs and symptoms of osteomyelitis include:

• Fever
• Swelling, warmth and redness over the area of the infection
• Pain in the area of the infection
• Fatigue

Sometimes osteomyelitis causes no signs and symptoms or the signs and symptoms are hard to distinguish from other problems. This may be especially true for infants, older adults and people whose immune systems are compromised.

When to see a doctor

See your doctor if you experience worsening bone pain along with fever. If you're at risk of infection because of a medical condition or recent surgery or injury, see your doctor right away if you notice signs and symptoms of an infection.

Causes

Most cases of osteomyelitis are caused by staphylococcus bacteria, types of germs commonly found on the skin or in the nose of even healthy individuals.

Germs can enter a bone in a variety of ways, including:

• The bloodstream. Germs in other parts of your body — for example, in the lungs from pneumonia or in the bladder from a urinary tract infection — can travel through your bloodstream to a weakened spot in a bone.
• Injuries. Severe puncture wounds can carry germs deep inside your body. If such an injury becomes infected, the germs can spread into a nearby bone. Germs can also enter the body if you have broken a bone so severely that part of it is sticking out through your skin.
• Surgery. Direct contamination with germs can occur during surgeries to replace joints or repair fractures.

Risk factors

Your bones are normally resistant to infection, but this protection lessens as you get older. Other factors that can make your bones more vulnerable to osteomyelitis may include:

Recent injury or orthopedic surgery

A severe bone fracture or a deep puncture wound gives bacteria a route to enter your bone or nearby tissue. A deep puncture wound, such as an animal bite or a nail piercing through a shoe, can also provide a pathway for infection.

Surgery to repair broken bones or replace worn joints also can accidentally open a path for germs to enter a bone. Implanted orthopedic hardware is a risk factor for infection.

Circulation disorders

When blood vessels are damaged or blocked, your body has trouble distributing the infection-fighting cells needed to keep a small infection from growing larger. What begins as a small cut can progress to a deep ulcer that may expose deep tissue and bone to infection.

Diseases that impair blood circulation include:

• Poorly controlled diabetes
• Peripheral artery disease, often related to smoking
• Sickle cell disease

Problems requiring intravenous lines or catheters

There are a number of conditions that require the use of medical tubing to connect the outside world with your internal organs. However, this tubing can also serve as a way for germs to get into your body, increasing your risk of an infection in general, which can lead to osteomyelitis.

Examples of when this type of tubing might be used include:

• Dialysis machine tubing
• Urinary catheters
• Long-term intravenous tubing, sometimes called central lines

Conditions that impair the immune system

If your immune system is affected by a medical condition or medication, you have a greater risk of osteomyelitis. Factors that may suppress your immune system include:

• Cancer treatment
• Poorly controlled diabetes
• Needing to take corticosteroids or drugs called tumor necrosis factor inhibitors

Illicit drugs

People who inject illegal drugs are more likely to develop osteomyelitis because they may use nonsterile needles and are less likely to sterilize their skin before injections.

Complications

Osteomyelitis complications may include:

• Bone death (osteonecrosis). An infection in your bone can impede blood circulation within the bone, leading to bone death. Areas where bone has died need to be surgically removed for antibiotics to be effective.
• Septic arthritis. Sometimes, infection within bones can spread into a nearby joint.
• Impaired growth. Normal growth in bones or joints in children may be affected if osteomyelitis occurs in the softer areas, called growth plates, at either end of the long bones of the arms and legs.
• Skin cancer. If your osteomyelitis has resulted in an open sore that is draining pus, the surrounding skin is at higher risk of developing squamous cell cancer.

Prevention

If you've been told that you have an increased risk of infection, talk to your doctor about ways to prevent infections from occurring. Reducing your risk of infection will also help your risk of developing osteomyelitis.

In general, take precautions to avoid cuts, scrapes and animal scratches or bites, which give germs easy access to your body. If you or your child has a minor injury, clean the area immediately and apply a clean bandage. Check wounds frequently for signs of infection.

Diagnosis

Your doctor may feel the area around the affected bone for any tenderness, swelling or warmth. If you have a foot ulcer, your doctor may use a dull probe to determine the proximity of the underlying bone.

Your doctor may order a combination of tests and procedures to diagnose osteomyelitis and to determine which germ is causing the infection. Tests may include:

Blood tests

Blood tests may reveal elevated levels of white blood cells and other factors that may indicate that your body is fighting an infection. If osteomyelitis is caused by an infection in the blood, tests may reveal which germs are to blame.

No blood test can tell your doctor whether you do or don't have osteomyelitis. However, blood tests can give clues to help your doctor decide what additional tests and procedures you may need.

Imaging tests

• X-rays. X-rays can reveal damage to your bone. However, damage may not be visible until osteomyelitis has been present for several weeks. More-detailed imaging tests may be necessary if your osteomyelitis has developed more recently.
• Magnetic resonance imaging (MRI). Using radio waves and a strong magnetic field, MRI scans can produce exceptionally detailed images of bones and the soft tissues that surround them.
• Computerized tomography (CT). A CT scan combines X-ray images taken from many different angles, creating detailed cross-sectional views of a person's internal structures. CT scans are usually done only if someone can't have an MRI.

Bone biopsy

A bone biopsy can reveal what type of germ has infected your bone. Knowing the type of germ allows your doctor to choose an antibiotic that works particularly well for that type of infection.

An open biopsy requires anesthesia and surgery to access the bone. In some situations, a surgeon inserts a long needle through your skin and into your bone to take a biopsy. This procedure requires local anesthetics to numb the area where the needle is inserted. X-ray or other imaging scans may be used for guidance.

Treatment

The most common treatments for osteomyelitis are surgery to remove portions of bone that are infected or dead, followed by intravenous antibiotics given in the hospital.

Surgery

Depending on the severity of the infection, osteomyelitis surgery may include one or more of the following procedures:

• Drain the infected area. Opening up the area around your infected bone allows your surgeon to drain any pus or fluid that has accumulated in response to the infection.
• Remove diseased bone and tissue. In a procedure called debridement, the surgeon removes as much of the diseased bone as possible and takes a small margin of healthy bone to ensure that all the infected areas have been removed. Surrounding tissue that shows signs of infection also may be removed.

• Restore blood flow to the bone. Your surgeon may fill any empty space left by the debridement procedure with a piece of bone or other tissue, such as skin or muscle, from another part of your body.

  Sometimes temporary fillers are placed in the pocket until you're healthy enough to undergo a bone graft or tissue graft. The graft helps your body repair damaged blood vessels and form new bone.

• Remove any foreign objects. In some cases, foreign objects, such as surgical plates or screws placed during a previous surgery, may have to be removed.
• Amputate the limb. As a last resort, surgeons may amputate the affected limb to stop the infection from spreading further.

Medications

A bone biopsy will reveal what type of germ is causing your infection so your doctor can choose an antibiotic that works well against that type of infection. The antibiotics are usually administered through a vein in your arm for about six weeks. An additional course of oral antibiotics may be needed for more-serious infections.

If you smoke, quitting smoking can help speed healing. It's also important to take steps to manage any chronic conditions you may have, such as keeping your blood sugar controlled if you have diabetes.

Preparing for an appointment

While you might first discuss your signs and symptoms with your family doctor, you may be referred to a doctor specializing in infectious diseases or to an orthopedic surgeon.

Here's some information to help you get ready for your appointment, and what to expect from your doctor.

What you can do

• Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance, such as restrict your diet.
• Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
• Make a list of all medications, vitamins or supplements that you're taking.
• Write down questions to ask your doctor.

For osteomyelitis, some basic questions to ask your doctor include:

• What's the most likely cause of my symptoms?
• What kinds of tests do I need? Do these tests require any special preparation?
• What treatments are available, and which do you recommend?
• Will surgery be necessary?
• What types of side effects can I expect from treatment?
• How long will it take for me to get better?
• I have other health conditions. How can I best manage these conditions together?
• Is there a generic alternative to the medicine you're prescribing?
• Are there any brochures or other printed material that I can take home with me? What websites do you recommend visiting?

What to expect from your doctor

Your doctor is likely to ask you a number of questions, such as:

• When did you first begin experiencing symptoms?
• Do you have a fever or chills?
• Does anything make your symptoms better or worse?
• Have you had any cuts, scrapes or other injuries lately?
• Have you had any surgery recently?
• Have you ever had a joint replaced? Or have you had surgical correction of a broken bone?
• Do you have diabetes? Do you have any foot ulcers?