Information Statement

"CDH" Should be "DDH"

This Information Statement was developed as an educational tool based on the opinion of the authors. It is not a product of a systematic review. Readers are encouraged to consider the information presented and reach their own conclusions.

"CDH" is the abbreviation for a condition involving dislocation, subluxation, or poor acetabular formation of the hip joint which is believed to be present at birth in form of susceptibility. "C" stands for "congenital" even though the hip is apparently normal at birth. "D" stands for "dislocation," "dysplasia," or "disease," according to what the speaker is thinking, but it is most commonly taken to mean "dislocation," even though the hip may be in joint. This lack of precision in terminology is tolerated by experienced physicians who mentally redefine "CDH" according to the context in which it is used, but the use of this abbreviation is confusing and misleading to patients, attorneys, and juries.

In the classification of nomenclature endorsed by the Pediatric Orthopaedic Society of North America the terminology is changed to Developmental Dysplasia of the Hip, thus "DDH." "Dysplasia" is an abnormality of development according to standard medical dictionaries. It encompasses the variations of the condition and is therefore preferred. "Developmental" is taken in the literal sense of organ growth and differentiation which includes the embryonic, fetal, and infantile periods. Developmental dysplasia includes these cases which are clearly congenital as well as cases not detected until later.

"Displacement" was originally suggested by Klisic, who coined DDH. It implies subluxation or dislocation, but semantically does not include isolated acetabular dysplasia. The anticipated revision of the International Classification of Diseases (ICD-10) has a "congenital" section which groups various hip abnormalities. The DDH terminology can be more easily adapted to ICD-10 if "Dysplasia" is the term used. "Developmental Displacement" will undoubtedly be used by some when dislocation or subluxation are clearly present, but this minor ambiguity of the term DDH should not create the same problems as the term CDH has.

The American Academy of Orthopaedic Surgeons (AAOS) believes the term Developmental Dysplasia of the Hip (DDH) should be used instead of Congenital Dislocation (or Dysplasia or Disease) of the Hip (CDH) and that its fellows should be encouraged to use the new term instead of the old term.

It is not possible to characterize an entire classification with a three letter acronym. When using the term DDH, we will still need to define when the disorder was discovered and the anatomical variants present. By changing from CDH to DDH the acronym will no longer falsely characterize a diagnosis in instances when the condition being described is neither congenital nor dislocated.

© December 1991 American Academy of Orthopaedic Surgeons

This material may not be modified without the express written permission of the American Academy of Orthopaedic Surgeons^®.

Information Statement 1002

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