What causes developmental dysplasia of the hip (DDH)?

Updated: Feb 26, 2018
  • Author: Junichi Tamai, MD; Chief Editor: William L Jaffe, MD  more...
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Answer

The etiology of hip dysplasia is not clear, but this condition does appear to be related to a number of different factors. [9] One such factor is racial background: In Native Americans and Laplanders, the prevalence of hip dysplasia is much higher (nearly 25-50 cases per 1000 persons) than in other races, and the prevalence is very low in southern Chinese and black populations. [10, 11, 12, 8] An underlying genetic disposition also appears to exist, in that the frequency of hip dysplasia is 10 times higher in children whose parents had DDH than in those whose parents did not. [13]

Other factors possibly related to DDH include intrauterine positioning and sex, and some of these are interrelated. Female sex, being the first-born child, and breech positioning are all associated with an increased prevalence of DDH. An estimated 80% of persons with DDH are female, [14] and the rate of breech positioning in children with DDH is approximately 20% (compared with 2-4% in the general population). [15, 16] The prevalence of DDH in females born in breech position has been estimated to be as high as 1 case in 15 persons in some studies. [17]

Other musculoskeletal disorders of intrauterine malpositioning or crowding, such as metatarsus adductus and torticollis, have been reported to be associated with DDH. [18, 19] Oligohydramnios is also reported to be associated with an increased prevalence of DDH. [20] The left hip is more commonly associated with DDH than the right hip, possibly because of the common intrauterine position of the left hip against the mother's sacrum, which forces it into an adducted position. [20] Children in cultures in which the mother swaddles the baby, forcing the infant's hips to be adducted, also have a higher rate of hip dysplasia. [21]

Hip dysplasia can be associated with underlying neuromuscular disorders, such as cerebral palsy, myelomeningocele, arthrogryposis, and Larsen syndrome, though such cases are not usually considered DDH.


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