The hip joint is a ball and socket joint capable of six different motions. The uppermost part of the thigh bone, or femoral head, fits nicely into a cup called the acetabulum. When it does not due to muscle imbalances, abnormalities occur. Also, blood vessels supplying the hip enter the joint from the surface of the femur, making them vulnerable to hip damage.
Prevalence of Pediatric Hip Pathology
Hip pathology in the pediatric population is not very common. According to Dr. Donald Kucharzyk of the Orthopaedic, Pediatric, and Spine Institute in Indiana, the incidence of hip instability occurs in every 2.7 per 1,000 births, whereas the incidence of hip dislocation occurs in every one per 1,000 births. Another hip abnormality known as transent synovitis, accounts for 0.4 to 0.9 percent of all annual pediatric admissions according to the same source.
Pediatric hip problems fall into four main categories: developmental dysplasia; transient synovitis; Legg-Calve-Perthes disease; and slipped capital femoral epiphysis.
Developmental Dysplasia of the Hip
Developmental dysplasia of the hip, or DDH, usually occurs just after the birth process. Hip dislocations are most common just after the delivery, although some do occur in utero. One-fifth of children born with DDH have a positive family history for this disease and ligamentous laxity in their hips. Females are nine times more likely to acquire this abnormality than males. Also, infants who were born in the breech position with their hips flexed and knees extended tend to be more prone to DDH. Signs of dislocation of the hip, occurring when the hip simultaneously straightens or extends and crosses the midline, or adducts, are checked for after birth, to promote normal development. Treatment for this condition immediately after birth involves placing the hip out to the side or abduction and forward or flexion. For infants, this means swaddling them with double diapers until they are three weeks old after which a Pavlik harness is used until the baby is six months old. After that, surgery is indicated to reduce the child's dislocated hip.
Transient Synovitis
A condition known as transient synovitis is another hip problem seen in children. The child will suddenly experience pain, begin to limp and develop hip movement limitations bringing the hip out to the side and turning inward. Possible causes for this disease include a systemic viral syndrome, trauma or an allergy, producing inflammation of the synovium or joint lining of the hip. This condition predominantly affects children, ages three to eight. Treatment for transient synovitis is very conservative. The child is ordered to bed rest and to avoid weight bearing on the hip until the pain subsides. For most children, bed rest lasts less than one week, followed by limited activities for one to two additional weeks. Your physician might also prescribe an anti-inflammatory to control pain.
Legg-Calve-Perthes Disease
Legg-Calve-Perthes disease is another condition affecting the pediatric hip. This disease is identified by death of tissue at the top of the hip bone due to lack of blood supply to the area, or avascular necrosis. There is perceived flattening of head of hip joint on X-ray. The cause for this is undetermined. This condition mainly affects males, two to 12years of age. They often experience uneven bone growth, are short for their age and walk with a painless limp. They might complain of intermittent pain in the anterior thigh and might also develop hip movement limitations bringing the hip out to the side and turning inward. Legg-Calve-Perthes disease is local and self-healing. Surgical and non-surgical techniques may be used to reduce the symptoms and presentation of this condition. Non-surgical treatment involves intermittent bed rest or stretching exercises into abduction to maintain mobility of the hip. A brace or surgery is warranted if X-rays indicate need to reduce displacement of the head of the hip.
Slipped Capital Femoral Epiphysis
A slipped capital femoral epiphysis is most commonly seen in adolescents. This condition is characterized by a twisting of the femur bone as the head of the bone, the capital femoral epiphysis or growth plate, remains in the hip socket but the underlying portion of the bone, or neck of the femur, "slips" and rotates forward. This results in an abnormal inward positioning of the leg while the hip may be rotated outward. This pathology is thought to be caused by an endocrine, growth rate disorder. Goals of treatment are to prevent further slippage of the femur bone. A surgical procedure to close the growth plate or capital femoral epiphysis, is performed. Degeneration of the articular cartilage of the hip and avascular necrosis of the head of the hip are complications of this surgical procedure.
References
- "Nelson Textbook of Pediatrics;"17th Edition; R. Behrman, MD, R. Kliegman, MD, and H. Jenson, MD; 2004
- Pediatric Orthopedics, P.C.: Developmental Dysplasia of the Hip, DDH
