Pediatric Injuries

Bone, Joint, and Muscle Infection in Children

Anatomy

A child's long bones do not grow from the center outward. Instead, growth occurs in the growth plates—areas of developing cartilage located near the ends of long bones. The growth plate regulates growth and helps determine the length and shape of the mature bone. Only when a child is fully grown do the growth plates harden (ossify) into solid bone. In fact, because muscles and bones develop at different rates of speed, a child's bones may actually be weaker than the ligaments that connect them.

Description

Children can develop "deep" infections in their bones (osteomyelitis), joints (septic arthritis), or muscles (pyomyositis). Deep infections most often occur in the joints and at the ends of long bones, where the bones meet to form joints (hip, knee, ankle, shoulder, elbow, and wrist). The most common locations for deep muscle infections are the large muscle groups of the thigh, groin and pelvis.

Symptoms and Signs

Children who have infections of their bones, joints, or muscles often have fever, pain, and limited movement of the infected area. For example, your child may limp or refuse to walk if the infection involves the legs or back. Infants may seem irritable and lethargic, and may refuse to eat, or vomit.

Many children who have bone, joint or muscle infections have had recent injuries. The symptoms of infection are often masked by those of the injury. Because parents assume the injury will get better over time, it may take them longer to notice the infection. If symptoms are not quickly improving at home, it is very important to bring your child to the doctor immediately.

Causes and Risk

Infections are usually caused by bacteria that are normally present in our living environment. One of the most common of these is Staphylococcus aureus, or Staph. In a child, there is a strong blood flow to the ends of bone near the growth plates, lining of the joints, spine, pelvis, heel, and large muscle groups, making it easier for bacteria to enter these areas and then multiply.

Infections pose special risks to young children because they spread quickly through a child's circulatory system and bone structure. Damage to bones and joints caused by infection can harm a child's growth and lead to physical dysfunction. Children under the age of three are easily infected because their immune systems are not fully developed and they tend to fall down frequently, opening the skin to infection.

Infection of child's hip joint is a surgical emergency.

Diagnosis

Your child's physician will conduct a thorough examination to determine the problem. Be sure to communicate all the surrounding circumstances, such as when the symptoms began, and whether there was a prior infection or injury.

Additional tests may be needed to help your doctor confirm a diagnosis and plan an appropriate treatment for your child.

• Blood tests and tissue cultures—By accurately identifying the bacteria or other organism causing the infection, your doctor is better able to determine the most effective ways to treat it.
• Imaging tests—X-rays, magnetic resonance imaging (MRI) scans, and ultrasound provide an accurate view of bones, muscles and soft tissues in the affected area, including swelling around bones and muscles, or fluid within the infected joints. This information helps your doctor when determining whether the infection should be treated with antibiotics alone, or if surgery will be required.

Nonsurgical Treatment

Antibiotics are the most commonly prescribed nonsurgical treatment for infection of the bones, joints or muscles in children. These may be administered in various ways.

• Intravenous—If antibiotics administered through the veins (intravenous or IV) are required, your child will remain in the hospital to receive treatment. The length of the hospital stay will depend on the severity of the infection, however, for most children it is 1 to 2 weeks.
• Oral—For many children the antibiotic is eventually changed to a form, which can be taken by mouth (oral) and given at home.
• PICC line—Some children can continue to receive an antibiotic intravenously at home through a special device called a peripherally introduced central catheter, or PICC line.

The amount of time required for antibiotics to resolve an infection varies from child to child. Generally, 4 to 6 weeks is needed for a bone infection, and 3 to 4 weeks for a joint or muscle infection. It is always extremely important to be sure your child takes all of the antibiotics, exactly as prescribed. If you have any questions regarding this, be sure to contact your physician.

Surgery

If the infection is mild, antibiotics alone may resolve the condition. Many children, however, require surgery to remove infected material (pus) from the area of infection. This reduces pressure and inflammation and improves blood flow, making it easier for the antibiotics to reach the infected area. Usually, one procedure is enough, but more severe infections may require two or more surgeries to resolve the infection.

Outcomes

After proper treatment, most children completely recover from deep infections and are unlikely to develop the same infection again. In most cases, children have no further problems and return to all of their activities.

When the infection is recognized and treated early, children generally do better and there is a greater chance for full recovery. 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 involved.

Problems that can occur in children who have serious and prolonged infections include: blood clots, growth arrests, deformed bones, fractures through bone that is weakened from infection, bone death (necrosis), and joint stiffness. However, these problems are rare.

Methicillin Resistant Staphylococcus Aureus (MRSA)

In many communities, deep infections are more frequently caused by a particular type of bacteria known as MRSA—a bacteria that is more resistant to antibiotics that previously worked well to treat these infections. Currently, there are several antibiotics that work very well against MRSA and are also tolerated by children.