Bone, Joint, and Muscle Infections

People can develop infections in their bones, joints, or muscles. Sometimes called "deep" infections, the technical names for these conditions are:

• Osteomyelitis (bone infection)
• Septic arthritis (joint infection)
• Pyomyositis (muscle infection)

Deep infections are most commonly found in the joints and at the ends of long bones where they meet to form joints. These include the hip, knee, and ankle joints of the leg, and the shoulder, elbow, and wrist joints of the arm.

The large muscle groups of the thigh, groin, and pelvis are the most common locations for deep muscle infections.

The reason infections occur in these areas is due to the way blood flows to these locations. There is a strong blood flow to the ends of bone near growth centers (called growth plates), the lining of the joints, and the large muscle groups. This allows bacteria to easily find their way to these areas.

The blood supply to the spine, pelvis, and heel is similar to that of the long bones, and infections often develop in these areas, as well.

What causes these types of infections?

Infections are usually caused by bacteria that are present in our normal living environment. The most common bacteria causing bone, joint, or muscle infections is Staphylococcus aureus (aka "Staph" infection).

Bacteria can get into the body in a variety of ways. They circulate through the bloodstream until they reach a bone, joint, or muscle. Bacteria then leave the bloodstream and multiply in the bone, joint, or muscle tissues.

What are the symptoms of infection?

People who have infections of their bones, joints, or muscles often have the following:

• Fever
• Pain
• Limited movement of the infected area

Many people who have bone, joint, or muscle infections have had recent injuries. The symptoms of infection are often masked by those of the injury. 

How are infections diagnosed?

Make sure to tell your doctor the circumstances surrounding the symptoms, such as when the symptoms began, and whether there was a prior infection or injury.

After discussing your symptoms and medical history, your doctor will examine the painful area. He or she may ask you to move the affected area to see whether movement increases the pain.

Tests

Other tests that may help your doctor confirm a diagnosis and plan treatment include:

• Blood tests and tissue cultures. Tests on your blood, as well as fluid and/or tissue from the infected area, can help identify the bacteria or other organism causing the infection. This information about the infection helps your doctor determine the most effective ways to treat it.
• Imaging tests. Tests, such as x-rays, magnetic resonance imaging (MRI) scans, and ultrasound, provide your doctor with pictures of the bones, muscles, and soft tissues in the affected area. Your doctor will look for swelling around bones and muscles, or fluid within the joints that are infected. This information helps your doctor when making the decision whether to treat the infection with antibiotics alone or to perform surgery to help resolve it.

How are infections treated without surgery?

Antibiotics are often used to treat infections. Different types of antibiotics include:

• Intravenous. At first, you will need to stay at the hospital to receive antibiotics through their veins (intravenous or IV). How long you will stay in the hospital will depend on how severe the infection is. 
• Oral. For many people, the antibiotic is eventually changed to a form that can be taken by mouth (oral) and given at home.
• PICC line. Some people can continue to receive an antibiotic by vein at home through a special intravenous device called a PICC (pronounced "pick") line. Peripherally introduced central catheter (PICC).

The amount of time on antibiotics that is needed to resolve an infection varies but, in general, is four to six weeks for a bone infection and three to four weeks for joint or muscle infections.

It is very important to take all of the antibiotics you're given, in exactly the way they are prescribed.

How are infections treatment with surgery?

In mild infections, antibiotics alone may resolve the condition. Many people, however, will need surgery to remove infected material (pus) from the area of infection. This will reduce pressure and inflammation and improve blood flow, which will make it easier for the antibiotics to reach the infected area. For most people, one surgical procedure is enough, but more severe infections may require two or more surgeries to help resolve the infection.

What is the typical outcome of these types of infections?

Most people will completely recover from deep infections after proper treatment. They are not likely to develop the same infection again. 

In general, you'll do better when the infection is recognized early. There is a greater chance for full recovery when the infection is quickly recognized and treated. The later the diagnosis is made, the more likely it is that the infection will cause greater damage to the bones, muscles, and other tissues that are involved.