Hip Pain Symptoms in Children

Hip pain is surprisingly common in kids, and most often, it is caused by injuries. These injuries—while fairly easy to detect in older children and adolescents—are much harder to detect when infants, toddlers, or preschoolers get hurt. These younger children may not be able to explain that they were injured, and may take a while before complaining of hip pain, may not want to walk, or may develop a limp.

Some Causes of Hip Pain in Kids

• Injuries - Fractures and muscle strains and sprains near the hip joint are usually obvious except in young children.
• Legg-Calve-Perthes disease and slipped capital femoral epiphysis (see below)
• Transient synovitis - The word "synovia" refers to joint, and "itis" - inflammation, therefore synovitis translates to inflammation of the joint. Transient synovitis in children is a very common cause of hip pain in preschool and younger school-age children, in which children often have symptoms of limping, hip pain, refusal to walk, but no fever or other symptoms. Although it often follows a viral infection, the actual cause is unknown, and the symptoms go away in a few days without any treatment.
• Septic arthritis - One of the more uncommon yet serious causes of hip pain in children is septic (infection-related) arthritis. Septic hip disease in children refers to an infection in the hip joint which can cause hip pain which often comes on suddenly, a refusal to walk, and often a fever and other symptoms which suggest an infection. The most common bacterial cause of septic arthritis of the hips in kids is a bacteria called Group B streptococcus.
• Osteomyelitis (bone infections) - In addition to septic arthritis, infections of the bones and muscles near the hip joint can cause hip pain. Since children's bones have a larger blood supply than those of adults, bacteria present in the blood (such as Staph aureus) can spread more easily to bones of children than adults.
• Other causes - Additional causes of hip pain in kids may include juvenile rheumatoid arthritis, bone cysts, and cancers such as osteosarcoma and Ewings sarcoma.

Hip pain in older children may also include some of the causes of hip pain in adults.

Legg-Calvé-Perthes Disease

Legg-Calvé-Perthes disease, sometimes called just Perthes disease, typically occurs in children between the ages of four and eight years old and is more common in boys, especially those who are very active and who are short for their age. These children often have a painless limp, but then develop other symptoms, including hip pain and decreased the range of motion or stiffness of the hip joint. They may also have pain in their groin or knee.

Legg-Calvé-Perthes disease is a form of osteonecrosis or avascular necrosis of the femoral head, which is the top of the leg bone that fits into the hip joint, and which can usually be seen on a routine X-ray. It occurs when the blood flow to the hip joint and surrounding bone is temporarily interrupted for some still unknown reason.

Treatment may include physical therapy for mild cases, restriction of vigorous activities, and surgery for more severe cases.

Slipped Capital Femoral Epiphysis

Slipped capital femoral epiphysis usually affects boys between the ages of 10 and 16, typically those who are overweight. It occurs when the neck of the femur slips along the growth plate away from the femoral head that is still in the hip joint. This can usually be seen on an X-ray, which is the typical way to diagnosis this condition.

Symptoms of slipped capital femoral epiphysis can include knee, groin, thigh, or hip pain, hip stiffness, limping, and as it gets worse, a child may not be able to walk at all.

Slipped capital femoral epiphysis is treated with surgery, which holds the femur in place and keeps it from slipping anymore.

Tests for Hip Pain

When a child has hip pain, even though there are many benign causes that are not harmful, others can be much more serious, especially if they are not diagnosed quickly.

To help aid in the diagnosis, tests can include:

• Hip (pelvis) X-rays
• Complete blood count (CBC) with differential
• Erythrocyte sedimentation rate (ESR)
• C-reactive protein (CRP)
• Rheumatoid panel (rheumatoid factor, ANA)
• Blood culture

Other tests for hip pain might include an ultrasound, magnetic resonance imaging (MRI) or computed tomography (CT) of the hip or a bone scan. Studies are ongoing looking at ways to accurately diagnose hip pain in children without unnecessary radiation exposure.

When septic arthritis is suspected, hip aspiration may also be done to see if the doctor can get pus from the infection out of the hip joint with a needle.