Developmental dysplasia of the hip (DDH) includes several conditions associated with impaired growth and development of the hip. Clinical screening aims to identify infants with neonatal hip instability who are at increased risk of hip displacement to allow early treatment with abduction splinting. However, the effectiveness of such screening is unknown. The diagnosis of abnormality is frequently unclear, and some conditions are thought to resolve spontaneously. Abduction splinting also can have adverse outcomes and be difficult for families to manage. Elbourne and colleagues studied the role of ultrasonography in DDH screening.
More than 600 infants in the United Kingdom and Ireland were recruited between December 1994 and January 1998. Eligible infants had hip instability diagnosed before 43 days of age. Infants were assigned to ultrasonography or control groups; the groups were similar in age, rates of unilateral/bilateral hip dysplasia, degree of clinical suspicion, and perceived severity of hip dysplasia. Infants assigned to ultrasonography had static and dynamic views taken at about two weeks of age. Immediate splinting was recommended for infants with significant displacement or instability. Infants with minor abnormalities were monitored and splinted if the abnormality persisted until eight weeks of age. The infants were then managed at the discretion of clinicians, but all underwent plain radiography of the hips and pelvis at 12 to 14 months of age. The infants were clinically followed until two years of age.
Data were available for 258 of the 314 infants (82 percent) screened by ultrasonography and for 276 of the 315 infants (88 percent) in the control group. The groups were well matched, and adherence to the study protocol was good. Fewer infants in the ultrasonography group were treated with splints before two years of age than infants in the control group (117 [37 percent] versus 150 [48 percent]). Surgical treatment was performed in 21 ultrasonographically screened infants (7 percent) compared with 25 infants (8 percent) in the control group. The groups had similar figures for out-patient hospital attendance and admission. Subluxation, dislocation, avascular necrosis, or acetabular dysplasia was radiographically identified in 21 children at age two years.
The authors conclude that adding ultrasonographic examination to clinical screening results in reduced use of splinting and is not associated with increased rates of abnormal hip development or surgical treatment. Although screening with ultrasonography is associated with higher initial costs, the overall costs over the two years were similar between the two screening methods. The authors stress that much more research should be done to determine the optimal method of screening for DDH. In particular, the benefits and harms of abduction splinting need to be clarified.
editor's note: Although this study demonstrates that ultrasonography can help physicians avoid unnecessary splinting in many children with clinically suspicious hips, the many unknowns leave no room for complacency about screening for hip disorders. It remains an inexact science, and sometimes parental concern (or comments from a grandmother) can be more diagnostic than clinical testing.—A.D.W.