Common Causes of Leg Pain in Children
Leg Pains in Children
There are a number of causes of leg pains in children. These range from overuse syndromes, to fractures and other injuries, to more worrisome problems like tumors and infections.
Since leg pains are common in children, this article will hopefully shed some light on the more common causes. Learn about these, alongside the red flags that might need further evaluation by a specialist.
Perhaps the most common cause of leg pains in children are injuries. These include:
- Contusions (bruises)
- Sprains (injury to a ligament),
The above tend to be related to specific injuries and are usually easy to diagnose based on the history, physical examination, and/or radiographs (x-rays). The pain in generally short-lived and easily treated.
Bruises and sprains are treated with ice, elevation, and anti-inflammatory medications. More severe sprains of the knee or ankle may require greater intervention such as casting or physical therapy. They may also require evaluation by a specialist.
The most common cause of chronic leg pains is often referred to as “growing pains.” In actuality, it has nothing to do with growth, but is really an overuse syndrome.
It typically affects children between the ages of 3 and 10 years, and it is almost always in both legs. They are running around so much that their muscles ache at the end of the day. It never interferes with play and other activities, tends to occur towards the end of the day and in the evenings, improves with leg massages, and resolves in early adolescence.
- Osgood-Schlatter's disease is also an overuse syndrome. It is a result of excess stress on the upper growth plate of the tibia, just below the knee in adolescents, and can result in swelling over the tibial tubercle (lump where the patellar ligament attaches).
- They often develop pain with jumping, running, and particularly with kneeling.
- The condition is benign and most often is treated with stretching and anti-inflammatory medications. It disappears when the growth plates close.
This is a vascular abnormality involving the blood supply to the femoral head.
- It occurs between the ages of 3 and 12 years and can occur bilaterally. However, when it is bilateral, it occurs at different times.
- Children often present with a painless limp. On radiographs, the femoral head looks more dense and may eventually collapse (flatten).
- Perthes disease tends to occur more commonly in boys than in girls.
- When it occurs in younger children, the prognosis for the hip recovery is better. In older children, the hip may become permanently deformed and eventually result in arthritis.
- The treatment varies, depending on the amount of femoral head involvement, and can range from simple observation to physical therapy to casts and surgery.
Transient or Toxic Synovitis
This is a self-limited condition thought to be a viral infection of the hip joint. The child limps and complains of some discomfort, but has no significant fever or other signs of infection.
Anti-inflammatory medications like ibuprofen significantly improve the pain and limp. Blood tests will show limited inflammation but no evidence of systemic infection. It usually resolves within 7-10 days.
Juvenile Inflammatory Arthritis (JIA)
- This can present with pain in the knees or ankles.
- Swelling of the joint greater than 6 weeks with no underlying cause has a high likelihood of being JIA.
- Some children present with only one joint involve, others may present with multiple joints, and some with systemic symptoms and a rash.
- Other than elevation of inflammatory markers such as an erythrocye sedimentation rate (ESR), most lab studies will be normal.
- Children with an unexplained joint swelling need evaluation by a pediatric rheumatologist. Since JIA can also result in inflammation of the iris and loss of site, these children will usually be evaluated by a pediatric ophthalmologist.
Joint and Bone Infections
Infections of bones and joints are most common in younger children. They may cause acute or chronic leg pain. In children, bone and joint infections are most often spread through the blood stream.
Infections that occur in joints (septic arthritis) are considered emergencies because they can destroy the joint surface very quickly.
- When infection occurs in the hip joint, the child often will refuse to walk and will hold the hip flexed and abducted (out to the side).
- When it occurs in the knee joint, the knee will be bent about 20 degrees and will be swollen.
Children with joint infections will often but not always have a fever. Blood tests usually reveal an elevated white blood cell count. These children will usually require emergent surgery and then antibiotics to prevent permanent damage to the surface of the joint.
Infection in the bone (osteomyelitis) can be more subtle, and the child may limp and have a fever but may not refuse to walk altogether. Thus, diagnosis may be delayed. Eventually, changes may be seen on an xray, although an MRI may show changes earlier.
Treatment for bone infections is usually intravenous antibiotics followed by oral antibiotics, often for 6 weeks or more. If an abscess is present in the bone, surgery may be required.
Thankfully, bone tumors are very rare in children.
There are different types of tumors (which simply means "bump" in Latin). Tumors can be benign (won't spread to other areas and won't cause loss of life) or malignant (they often spread and usually are life threatening).
- Benign tumors include such things as fibrous dysplasia, simple bone cysts, osteoid osteomas, and non-ossifying fibromas or fibrous cortical defects. These are often noted on x-ray when it is taken for an injury or fracture.
- Malignant tumors tend to be more symptomatic. They often affect the child's activity level. In addition, they may wake up with pain in the middle of the night. Fever and weight loss may also be associated. This may cause swelling, fracture of the bone, and severe pain. It is really important to remember that malignant tumors and infections generally don't occur bilaterally (on both sides).
As you can tell, most of the causes of leg pains in children are benign. However, the red flags are:
- Night pain consistently in only one leg
- Worsening pain
- Fevers and/or weight loss
- Self-limitation of activities
These red flags require immediate evaluation and you should consult your pediatrician right away.