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Contralateral Hip Dysplasia More Common Than Thought, Often not Recognized

Approximately one to two children out of 1000 are born with development dysplasia of the hip (DDH), where the hip joint - most commonly the left hip - is not properly formed. Doctors have noticed that many children with DDH also have a subtle dysplasia on the contralateral (other) hip, often not diagnosed right away and as late as the teen-age years. The question, however, is if the dysplasia in the other hip was there since birth and simply not noticed or that the hip developed that way as the child matured.

The authors of this study sought to find out how common contralateral hip dysplasia is and to see if it was a developmental issue or if the children were born with it.

Researchers reviewed the files of 43 children: 18 with bilateral (both) hip dysplasia, eight of whom were diagnosed at initial evaluation and 10 after repeat evaluations. Therefore, only 19 percent were diagnosed initially. The remaining 25 patients were not found to have bilateral hip dysplasia at any point during the examinations.

Follow-up examinations were done from early childhood to adolescence. X-rays were taken, as were measurements of hip angles. The authors wrote, "of those patients who had no evidence of contralateral hip dysplasia even after careful repeated examination, we identified 10 patients who had mild, or borderline, dysplasia at maturity." They also noted that these findings indicate physicians should be prudent in evaluating contralateral hip dysplasia because of the unknown consequences of mild hip dysplasia.

They conclude that the results of their small study find the incidence of contralateral hip dysplasia is not as rare as once thought but is not being recognized.

References: Frederick S. Song, et al. The Incidence of Occult Dysplasia of the Contralateral Hip in Children with Unilateral Hip Dysplasia. In Journal of Pediatric Orthopedics. March 2008. Vol. 28. No. 2. Pp. 173-176.

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