Questions & answers for clinical insights

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QUESTIONS

& ANSWERS FOR CLINICAL

INSIGHTS (Questions

1. Describe why the name changedfiom congenital dislocated hip (CDH) to developmental dysplasia of the hip (DDH). DDH is actually a spectrum of anatomic abnormalities of the hip, which includes hip instability, malformation, subluxation, and dislocation. The name CDH was misleading and has led to several problems. The term congenital implied that the condition was present at birth; therefore some providers assumed that if the hips were stable in the neonatal period they would continue to develop normally and that there was no need for ongoing evaluation. It is now well documented that dislocation or dysplasia of the hip has occurred after a normal newborn examination (Aronsson, Goldberg, Kling, & Roy, 1994). The term congenital was also confusing and misleading to parents, attorneys, and jurors, thus leading to many law suits against primary cam physicians (Staheli, 1992). Developmental implies something that occurs over time, including both the prenatal and neonatal periods; and dysplasiameans an abnormality of development and encompasses a wide spectrum of hip problems (Aronsson et al., 1994). Embryologically, “The hip joint begins to develop at 8 weeks’ gestation when a cleft occurs between the acetabulum and the femoral head, and development is usually complete by 11weeks.As a result, the hip is always located early in the embryologic stage because it forms from the pelvis. Hip dysplasia or dislocation may occur in utero, perinatally, or subsequently with development. Moving from the fetal position of hip flexion to one of extension as occurs

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after birth increasesthe susceptibility of dislocation” (Aronsson et al., 1994) 2. How is thediagnosisof DDH madein theneubomand in otheragegroups? Diagnosis of developmental hip dysplasia in the newborn is made primarily by physical examination. Both the Barlow and Ortolani techniques should be used to examine the hips, one at a time. The infant should be supine and, ideally, quiet and relaxed so that the muscles around the hips are relaxed. No force should be used. For the Ortolani maneuver, the examiner places the middle and index fingers over the greater trochanter with the thumb along the medial thigh. The leg is positioned in neutral rotation with 90 degreesof hip flexion and is gently abducted while the leg is lifted anteriorly. The clunk felt on abduction is the head of the femur sliding over the posterior rim of the acetabulum into the socket and is called the sign of entry. Barlow’s maneuver involves gently adducting the leg while gentle pressure directed posteriorly is placed on the knee. A clunk is palpable as the femoral head slides over the posterior rim of the acetabulum and out of the socket and is called the sign of exit. Other signs to look for during the examination include asymmetric thigh folds, a short leg appearance, a prominent greater trochanter or limitation of abduction or adduction. Between 3 and 12 months the Ortolani and Barlow maneuvers become less useful in making the J PEDIATR HEALTH C~~~.(19961

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diagnosis because there is lessligamentous and capsular laxity. Limitation of hip abduction is the best physical sign in this age group. Once a child is walking, physical signs include a typical limp, often toe-walking, and a positive Trendelenburg test on the affected side. Bilateral dislocation causesa waddling gait and increased lumbar lordosis (Aronsson et al., 1994). Bilateral hip dislocation is more difficult to diagnose; therefore any infant with less than 60 degrees of abduction bilaterally deserves an imaging study. 3. What imagingstudiesayeuseful? Routine radiographs are not useful in the newborn period because much of the neonatal pelvis and femoral head are cartilaginous. Additionally, the infant’s hip may be spontaneously reduced when positioned for the radiograph. In 1980 use of ultrasonography to diagnose DDH was studied, and in 1992Bialik et al. recommended that ultrasonography be a compulsory examination for all newborns. However, subsequent studies have shown that the use of newborn screening by ultrasonography results in a high false positive rate and a high treatment rate (Aronsson et al., 1994). Ultrasonography is alsodependent on the skill and experience of the examiner. In today’s health care climate such unnecessarycostswould be strongly discouraged. A study recently published in Pediatricsdesigned to assess the effect of ultrasound screeningon

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primary diagnosis, management, and prevalence of late cases of DDH concluded “the effect of ultrasound screening in reducing the prevalence of late DDH was at best marginal despite a considerable increase in diagnostic and therapeutic efforts” (Rosendahl, Markestad, & Lie, 1994). All newborns should have a hip examination. If the examination is normal, it should be repeated at each well baby visit through age 1 year. If a newborn has a positive Ortolani or Barlow test, the infant has DDH, ultrasonography is unnecessary and appropriate orthopedic referral should be made. If the examination is questionable or there are associated risk factors, ultrasonography is recommended for infants from 1 to 4 months of age, and an anteroposterior pelvis radiograph if the infant is older than 4 months of age. Some experts recommend an anteroposterior radiograph at 4 months of age even with a previous normal ultrasonogram, if risk factors are present (Aronsson et al., 1994).

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4. What is the goal of early detection and treatment, and how long should Jean befollowed?

REFERENCES Aronsson,

D.D., Goldberg,

M.J., Kling,

Roy, D.R. (1994). Developmental

T.F., & dyspla-

sia of the hip. Pediatrics, 94,201-208,

“The goal of treatment is to safely obtain and maintain a concentric reduction of the hip to provide an environment for normal bony development” (Aronsson et al., 1994). The earlier DDH is treated, the shorter the course of treatment necessary. An additional goal of treatment is to prevent avascular necrosis, the most serious complication in management of DDH. A recent study followed children whose DDH had been treated with a Pavlik harness and normal radiography at 5 years of age. Repeat radiography at 12year follow up showed changes in the acetabuhun in 17%. This emphasizes the need for follow up of these children until skeletal maturity is obtained (Aronsson et al., 1994).

Rosendahl,

K., Markestad,

T., & Lie, R.T.

(1994). Pediatrics, 94,47-52. Staheli,

L.T. (1992). Fundamentals

orthopedics. New York: Raven

ofpediatric Press.

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