Congenital hip dislocation


Hip dysplasia is considered to be a multifactorial condition. That means that several factors are involved in causing the condition to manifest.

Some studies suggest a hormonal link. Specifically the hormone relaxin has been indicated.
A genetic factor is indicated by the trait running in families and increased occurrence in some ethnic populations (e.g. native Americans, Lapps / Sami people). A locus has been described on chromosome 13. Beukes familial dysplasia, on the other hand, was found to map to an 11-cM region on chromosome 4q35. With nonpenetrant carriers not affected.

As an acquired condition it has often been linked to traditions of swaddling infants or use of a cradle board which locks the hip joint in an "abducted" position for extended periods. Modern swaddling techniques allow some room for leg movement.
Further risk factors include breech birth and firstborns. In breech position the femoral head tends to get pushed out of the socket. A narrow uterus also facilitates hip joint dislocation during fetal development and birth.

Most countries have standard newborn exams that include a hip joint exam screening for early detection of hip dysplasia. It can often be detected by a "click" or more precisely "clunk" in the hip (although not all clicks indicate hip dysplasia). Two maneuvers commonly employed for diagnosis in neonatal exams are the Ortolani maneuver and the Barlow maneuver.

The condition can be confirmed by ultrasound and X-ray. Ultrasound imaging yields better results defining the anatomy until the cartilage is ossified. When the infant is around 3 months old a clear roentgenographic image can be achieved. Unfortunately the time the joint gives a good x-ray image is also the point at which nonsurgical treatment methods cease to give good results. In x-ray imaging dislocation may be indicated if the Shenton's line (an arc drawn from the medial femoral neck through the superior margin of the obturator foramen) does not result in a smooth arc.




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