A hip problem can be hard to deal with, both for the child who has the problem and to the parent or caregiver. A child who has a hip problem may feel pain in the hip, groin, thigh, or knee. A child in pain may limp or be unable or unwilling to stand, walk, or move the affected leg. A baby in pain may cry, be fussy, and have other signs of pain. Hip problems may be present at birth (congenital) or may develop from injury, overuse, inflammation, infection, or tumor growth.
To better understand hip problems, it may be helpful to know how the hip works. It is the largest ball-and-socket joint in the body. The thighbone (femur) fits tightly into a cup-shaped socket (acetabulum) in the pelvis. The hip joint is tighter and more stable than the shoulder joint but it does not move as freely. The hip joint is held together by muscles in the buttock, groin, and spine; tendons; ligaments; and a joint capsule. Several fluid-filled sacs (bursae) cushion and lubricate the hip joint and let the tendons and muscles glide and move smoothly. The largest nerve in the body (sciatic nerve) passes through the pelvis into the leg.
Hip problems may develop from overuse, infection, or a problem that was present from birth (congenital). Oddly enough, a child who has a hip problem often feels pain in the knee or thigh instead of the hip. Hip problems that affect children include:
- An inflammatory reaction, such as transient or toxic synovitis. This generally occurs after the child has had a cold or other upper respiratory infection. This is the most common cause of hip pain in children.
- A slipped capital femoral epiphysis. This occurs when the upper end of the thighbone (head of the femur) slips at the growth plate (epiphysis) and does not fit in the hip socket correctly.
- Legg-Calve-Perthes disease. This condition is caused by decreased blood flow to the head of the femur which affects the bone as seen on the X-ray and an MRI of a child with this problem.
- An inward twisting of the thighbone (femoral anteversion). This condition causes the knees and feet to turn inward. The child will have a "pigeon-toed" appearance and may have a clumsy walk.
- Developmental dysplasia of the hip (DDH). This condition is caused by a problem in the development of the hip joint. The top of the femur does not fit correctly into the hip socket (acetabulum) so the femur can partially or completely slip out of the socket.
- Juvenile idiopathic arthritis (JIA). This condition causes inflamed, swollen joints that are often stiff and painful.
- Infection in the joint (septic arthritis), the bursa (septic bursitis), or the hip or pelvic bone (osteomyelitis).
- In rare cases, cancer of the bone, such as osteosarcoma.
Treatment for a hip problem depends on the location, type, and severity of the problem as well as the child's age, general health, and activity level. Treatment may include first aid measures; application of a brace, cast, harness, or traction; physical therapy; medicines; or surgery.
Check your child's symptoms to decide if and when your child should see a doctor.