Hip dysplasia is a known risk factor for premature osteoarthritis. It is often debated whether developmental dysplasia of the hip (DDH) in infancy and hip dysplasia in adolescence or adulthood (Adult Dysplasia – AD) are the same thing, or whether adult dysplasia develops after infancy.
A recent study conducted at Boston Children’s Hospital explored the characteristics of patients diagnosed in adulthood to see if they were different from DDH in infants.
421 patients undergoing periacetabular osteotomy (PAO) for adult dysplasia received a questionnaire regarding birth and family history; 311 patients completed the survey. One third of the patients having PAO surgery had been diagnosed as infants and 209 patients were diagnosed after maturity. Statistically significant differences were found between the two groups. The group diagnosed as adolescents or adults were more likely to be male and more likely to have bilateral hip dysplasia. The older group was also less likely to have a history of breech position in the womb. Patients with the infant form of DDH were also more likely to have a positive family history.
This study showed that the infants with hip dysplasia were more likely to have the risk factors that are commonly associated with hip dysplasia: Family history, girls, and breech birth. While this study seems to show a difference between the two groups, it is also possible that those without the risk factors were more likely to go undiagnosed because of lower levels of concern at time of birth. Also, it is more difficult to detect bilateral hip dysplasia because there is asymmetry when only one side is affected. It is possible that these two groups are both related to infantile dysplasia but there was a greater likelihood of failure to diagnose during infancy for those without a family history, breech birth, unilateral dysplasia or female gender.
Comments: We still don’t know if adolescent hip dysplasia is caused by a mild form of hip dysplasia that was present at birth or whether it develops later in life like teeth that become crooked during adolescence. Studies from Norway have noted that comprehensive screening during infancy only identifies 8% of all cases of hip dysplasia when adults are included. The International Hip Dysplasia Institute is encouraging continued research into better understanding of the causes of hip dysplasia because it is becoming apparent that examination at birth does not identify most cases of hip dysplasia.
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