- Osteomyelitis (bone infection)
- Septic arthritis (joint infection)
- Pyomyositis (muscle infection)
This article covers the most common types of deep infections in children and includes the ways doctors identify and treat them.
Infections are usually caused by bacteria that are present in our normal living environment. The most common bacteria causing bone, joint, or muscle infections in children is Staphylococcus aureus (often referred to as “Staph” infections).
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.
Deep infections most often occur 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.
Infections pose special risks to young children for a number of reasons:
- Children under the age of three are easily infected. Their immune systems are not fully developed and they tend to fall down a lot, opening the skin to infection.
- Infections spread quickly through a young child’s circulation system and bone structure.
- Damage to bones and joints caused by infection can harm a child’s growth and lead to physical dysfunction. Infection of child’s hip joint is a surgical emergency.
Symptoms and Signs
Children who have infections of their bones, joints, or muscles often have the following:
- Limited movement of the infected area — your child may limp or refuse to walk if the infection involves the legs or back
- Infants may be irritable and lethargic, 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.
It is important to bring your child to a doctor immediately if symptoms are not quickly resolving at home.
Medical History and Physical Examination
Make sure to tell your child’s doctor the circumstances surrounding the symptoms, such as when the symptoms began, and whether there was a prior infection or injury.
After discussing your child’s symptoms and medical history, your doctor will examine the painful area. He or she may ask your child to move the affected area to see whether movement increases the pain.
Other tests that may help your doctor confirm a diagnosis and plan your child’s treatment include:
- Blood tests and tissue cultures. Tests on your child’s 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 child’s 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.
Prescribing antibiotics is the mainstay of treatment for infections.
- Intravenous. At first, your child will need to stay at the hospital to receive antibiotics through the veins (intravenous or IV). How long your child will stay in the hospital will depend on how severe the infection is. Most children with bone, joint, or muscle infections are in the hospital for 1 to 2 weeks.
- Oral. For many children, the antibiotic is eventually changed to a form that can be taken by mouth (oral) and given at home.
- PICC line. Some children can continue to receive an antibiotic by vein at home through a special intravenous device called a PICC (pronounced “pick”) line. This is a peripherally introduced central catheter (PICC).
The amount of time on antibiotics that is needed to resolve an infection varies from child to child but, in general, is 4 to 6 weeks for a bone infection and 3 to 4 weeks for joint or muscle infections.
It is very important to have your child take all of the antibiotics he or she is given, in exactly the way they are prescribed.
In mild infections, antibiotics alone may resolve the condition. Many children, 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 children, one surgical procedure is enough, but more severe infections may require two or more surgeries to help resolve the infection.
Most children will completely recover from deep infections after proper treatment. They are not likely to develop the same infection again. In most cases, children have no further problems and return to all of their activities.
In general, children 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.
Some problems can occur in children who have serious and prolonged infections. These include blood clots, growth arrests, deformed bones, fractures through bone that is weakened from infection, bone death (called necrosis), and joint stiffness. However, these problems are rare.
Methicillin Resistant Staphylococcus Aureus (MRSA)
In many communities, deep infections are more frequently being caused by a particular type of bacteria known as MRSA. This bacteria is more able to resist antibiotics that previously worked well to treat these infections.
Currently, there are several antibiotics that work very well against MRSA and are tolerated very well by the children who are treated.