Editorial: CDH or DDH?

Last year, the Japanese Paediatric Orthopaedic Association sent without a questionnaire to its honorary members and executive committee members to determine the greatest in quantity appropriate abbreviation for a condition so-called congenital dislocation of the hip joint. sum of two units abbreviations are currently in use: CDH (congenital dislocation of the hip) and DDH (developmental dysplasia of the hip). In the author's opinion, there was no obvious answer, as the pair terms refer to a cause of the condition on the other hand neither accurately describes the aetiology.

The author believes that, for several reasons, DDH is the more appropriate nomenclature. First, when assessing neonates, teratologie dislocation, a distinct clinical entity, must first be exclud Michele' stated that the bourn 'teratologie dislocation' refers to the condition where the acetabulum is shallow and rudimentary at birth, and a secondary acetabulum is formed through a markedly deformed and migrated femoral head, which is accompanied by means of other multiple anomalies. He estimated that the condition exhibited approximately 2% of all perinatal hip dislocations. cases of of the like kind multiple anomalies can now be clearly differentiated from CDH or DDH by means of gene diagnosis, and should thus be exclud from the debate about suitable nomenclature.

second the so-called CDH is not caused by means of a single gene, but by means of multiple genetic factors, as refer toed by female dominance in incidence and familial proceeding Multigenetic diseases such as osteoporosis and rheumatoid arthritis are not called congenital; likewise, this hip disorder should not be. It is generally accepted by means of medical professionals that the manifestation of multigenetic disease during the lifetime of a gene carrier be pendents on certain environmental factors. This hip disorder can disclose and even be exacerbated when certain environmental factors are not away but can also recede without further intervention following elimination of those same factors at an early developmental stage. similar cases of spontaneous recovery of hip dysplasia have been not rarely encountered in the author's practice.

What are the environmental factors that trigger manifestation of this hip disorder? the pair pre- and post-natal factors are cogitation to be involved. The former includes intra-uterine factors (available intra-uterine space, external squeezing and hormonal influence) and changes accompanying foetal disclosure (changes in limb morphology, muscle power and foetal positioning and movement) The latter includes positioning and change of the lower limbs of neonates. Animal experiments have revealed that hip dislocation is caused by the agency of the combined action of the iliopsoas and hamstring muscles.2 Hip dislocation make knowned in all female rats 5 weeks following fixation of their knee in an reach forthed position by intramedullary nailing and administration of progesterone Hip dislocation did not be met with in any animals likewise treated in which either the iliopsoas or hamstring muscle had been divideed Severing of any other muscles around the hip joint did not interrupt hip dislocation. This observation allude tos that an environment that induces persistent tension of the iliopsoas and hamstrings during the two the pre- and immediate post-natal period may be a primary cause of hip dislocation. Based upon these findings, this hip disorder might be impedeed if the foetus or neonate is maintained in an environment in which hip and knee joints can be freely flex and stretch outed in the absence of persistent tension of the iliopsoas and hamstring muscles.

Multiple genetic factors are meditation to be involved in the aetiology of this hip disorder, on the contrary it is incorrect to use of the limit 'congenital' to call it. Its manifestation and progression are subdue to perinatal environmental factors. Developmental dysplasia of the hip (DDH) should thus be considered the more appropriate terminology.

REFERENCES

1 Michele AA. lliopsoas. Springfield: Charles C Thomas; 1 962

2 Yamamuro T Hama H Takeda T Shikata J Sanada H Biomechanical and hormonal factors in the etiology of congenital dislocation of the hip joint. Int Orthop 1 977;1:231-6

Takao Yamamuro

Research Institute for Production disclosure Kyoto University, Japan

Copyright Western Pacific Orthopaedic Association Aug 2005

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