Diseases & Conditions
Bone, Joint, and Muscle Infections in Children
Children can develop infections in their bones, joints, or muscles. These are often called "deep" infections. The medical names for these conditions are:
- Osteomyelitis, an infection in a bone
- Septic arthritis, an infection in a joint
- Pyomyositis, an infection in a muscle
- Abscess, a separate pocket of infection that contains pus, usually found in the soft tissues
This article describes the most common deep infections in children. It also explains how doctors identify and treat them.
Causes of Deep Infections
Deep infections are usually caused by bacteria found in our normal living environment. The bacterium that most often causes bone, joint, or muscle infections in children is Staphylococcus aureus. These infections are often called Staph infections.
Bacteria can enter the body in several ways. They may then travel through the bloodstream until they reach a bone, joint, or muscle. The bacteria can leave the bloodstream and multiply in these tissues. Children are especially at risk for this type of infection.
Description
Deep infections most often develop inside joints and at the ends of long bones. Long bones meet at their ends to form joints. Common locations include:
- The hip, knee, and ankle joints in the leg
- The shoulder, elbow, and wrist joints in the arm
Deep muscle infections most often occur in the large muscle groups of the thigh, groin, and pelvis.
These infections occur in part because of the way blood flows through these areas. Blood flow is slow at the ends of bones near the growth centers, called growth plates. The blood vessels in these areas are also delicate. These features allow bacteria in the bloodstream to leave the blood vessels more easily.
The bacteria can then enter nearby bone tissue. From there, they may spread into nearby joints and muscles and cause deep infections.
The blood supply to the spine, pelvis, and heels is similar to the blood supply at the ends of long bones. For this reason, infections often develop in these areas as well.
Infections pose special risks to young children for several reasons:
- Children younger than 3 years are easily infected. Their immune systems are not fully developed. They also tend to fall often, which may break the skin and allow bacteria to enter.
- Infections can spread quickly through a young child's circulatory system and bone structure.
- An infection can damage a child's bones and joints. This damage may affect growth and cause a limb to become shorter or develop an angular deformity. Infection can also damage the cartilage inside a joint. These problems may cause permanent physical dysfunction.
- An infection inside a joint is a surgical emergency.
Symptoms and Signs of a Deep Infection
Children who have infections of their bones, joints, or muscles often have:
- Fever
- Pain
- Red or warm skin over the affected area
- Limited movement of the infected area
- If the infection affects the legs or back, the child may limp or refuse to walk
Infants may:
- Be irritable and lethargic
- Refuse to eat
- Vomit
Many children who have bone, joint, or muscle infections have had a recent injury. The symptoms of the injury may hide the symptoms of the infection. Parents may expect the injury to improve with time. As a result, it may take longer for them to notice the infection.
Bring your child to a doctor right away if the symptoms do not quickly improve at home.
Diagnosing a Deep Infection
Medical History and Physical Examination
Tell your child's doctor about the events surrounding the symptoms. Explain when the symptoms began. Also tell the doctor whether your child had an earlier infection or injury.
After discussing your child's symptoms and medical history, the doctor will examine the painful area. The doctor may ask your child to move the affected area to learn whether movement makes the pain worse.
Tests
Several tests can help the doctor confirm a diagnosis and plan treatment:
Blood Tests and Tissue Cultures
Doctors may test your child’s blood. They may also test fluid or tissue taken from the infected area. These tests can help identify the bacterium or other organism causing the infection.
This information helps the doctor choose the most effective treatment. Final culture results may take several days.
Imaging Tests
Imaging tests give the doctor pictures of the bones, muscles, joints, and other soft tissues in the affected area. These tests may include:
- X-rays
- Magnetic resonance imaging (MRI) scans
- Ultrasound
The doctor will look for swelling around the bones or muscles. The doctor will also look for fluid inside infected joints.
The results help the doctor decide whether to treat the infection with antibiotics alone or perform surgery as well.
Aspiration
The doctor may use a needle to remove fluid from a joint or pocket of infection. This procedure is called aspiration.
The doctor may use X-ray, ultrasound, or another type of imaging to guide the needle. Aspiration is often performed with sedation medication. This helps your child feel less pain or allows your child to sleep during the procedure.
Treatment of Deep Infections
Antibiotic Treatment
Antibiotics are the mainstay of treatment for deep infections.
Intravenous Antibiotics
At first, your child will need to stay in the hospital. Antibiotics will be given through a vein. This is called intravenous, or IV, treatment.
The length of the hospital stay depends on how severe the infection is. Most children with bone, joint, or muscle infections remain in the hospital for about 1 week.
Oral Antibiotics
Culture testing helps the doctor find the specific antibiotics that will work against the infection. For many children, the doctor will later change the medicine to an antibiotic that can be taken by mouth. This is called oral treatment, and it can be given at home.
PICC Line
Sometimes oral antibiotics do not control the infection well enough. The child may then need intravenous antibiotics for a longer time.
A special IV line called a PICC line may be used. PICC is pronounced "pick." A PICC line allows a child to keep receiving the needed IV antibiotics while at home.
The length of antibiotic treatment varies. In general, treatment lasts:
- 4 to 6 weeks for a bone infection
- 3 to 4 weeks for joint or muscle infections
It is very important for your child to take every dose of antibiotics. Give the medicine exactly as prescribed.
If antibiotics are not taken correctly, the infection may return. In some cases, the bacteria may also become resistant to the antibiotic that was used before.
Surgical Treatment
Antibiotics alone may clear a mild infection. A more serious infection may require surgery to remove infected material, including pus. This procedure is called irrigation and debridement.
For most children, one operation is enough. A more severe infection may require two or more operations to clear the infection.
Outcome
Most children recover fully from deep infections after proper treatment. They are unlikely to develop the same infection again. Most children have no further problems and return to all their usual activities.
In general, children have better outcomes when the infection is found early. A full recovery is more likely when doctors quickly identify and treat the infection.
A later diagnosis increases the risk of damage. The infection may cause more harm to the affected bones, muscles, and other tissues.
Children with serious or long-lasting infections may develop certain problems. These include:
- Blood clots: Blood clots are otherwise rare in children, but they have occurred in children with MRSA infections.
- Growth arrest and deformity: Growth arrest is a condition that causes a bone to grow abnormally. It may occur if an infection injures the growth plate. The abnormal growth may later cause a deformity.
- Fractures: An infection can weaken a bone. A fracture may occur in the weakened bone.
- Avascular necrosis: Bone death, called avascular necrosis, may occur. This complication is rare
Methicillin Resistant Staphylococcus Aureus (MRSA)
In many communities, a certain type of bacterium is causing deep infections more often. It is called methicillin-resistant Staphylococcus aureus, or MRSA.
MRSA is more resistant to commonly used antibiotics. However, several antibiotics currently work very well against MRSA. Children also tend to tolerate these medicines very well.
Culture testing will help your child’s treatment team identify a MRSA infection. It will also show which antibiotics are most likely to treat the infection successfully.
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