Hip dysplasia
| Hip dysplasia | |
|---|---|
| Synonyms | developmental dysplasia of the hip (DDH), congenital dysplasia of the hip (CDH) |
 |
|
| Congenital dislocation of the left hip in an elderly person. Closed arrow marks the acetabulum, open arrow the femoral head. | |
| Classification and external resources | |
| ICD-10 | Q65 |
| ICD-9-CM | 754.3 |
| OMIM | 142700 |
| DiseasesDB | 3056 |
| MedlinePlus | 000971 |
| eMedicine | orthoped/456 |
| MeSH | D006618 |
Hip dysplasia is a congenital or developmental deformation or misalignment of the hip joint. It does not typically produce symptoms in children less than a year old.
Screening all babies for the condition by physical examination is recommended. About 7.5% of hip replacements are done to treat problems which have arisen from hip dysplasia.
Hip instability which is of meaningful importance occurs in one to two percent of babies born at term.
Hip dysplasia can range from barely detectable to severely malformed or dislocated. The congenital form, teratologic or non-reducible dislocation occurs as part of more complex conditions.
The condition can be bilateral or unilateral:
If the joint is fully dislocated a false acetabulum often forms (often higher up on the pelvis) opposite the dislocated femoral head position.
In acetabular dysplasia the acetabulum (socket) is too shallow or deformed. The center-edge angle is measured as described by Wiberg. Two forms of femoral dysplasia are coxa vara, in which the femur head grows at too narrow an angle to the shaft, and coxa valga, in which the angle is too wide.
A rare type, the "Beukes familial hip dysplasia" is found among Afrikaners that are members of the Beukes family. The femur head is flat and irregular. People develop osteoarthritis at an early age.
Hip dysplasia is considered to be a multifactorial condition. That means that several factors are involved in causing the condition to manifest. Its cause is unknown but it is common in cases of a large fetus or a fetus in a breech position.
Some studies suggest a hormonal link. Specifically, the hormone relaxin has been indicated.
A genetic factor is indicated since the trait runs in families and there is an 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.
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Wikipedia