Editorial: CDH or DDH?

Last year, the Japanese Paediatric Orthopaedic Association sent on the outside 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 two 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 mete 'teratologie dislocation' refers to the condition where the acetabulum is shallow and rudimentary at birth, and a secondary acetabulum is formed by the agency of a markedly deformed and migrated femoral head, which is accompanied through 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 through gene diagnosis, and should thus be exclud from the debate about suitable nomenclature.

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

What are the environmental factors that trigger manifestation of this hip disorder? the couple pre- and post-natal factors are contemplation 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 puissance and foetal positioning and movement) The latter includes positioning and motion of the lower limbs of neonates. Animal experiments have revealed that hip dislocation is caused by dint of the combined action of the iliopsoas and hamstring muscles.2 Hip dislocation disentangleed in all female rats 5 weeks following fixation of their knee in an reach outed position by intramedullary nailing and administration of progesterone Hip dislocation did not present itself 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 hinder hip dislocation. This observation indicates that an environment that induces persistent tension of the iliopsoas and hamstrings during the one and the other the pre- and immediate post-natal period may be a primary cause of hip dislocation. Based upon these findings, this hip disorder might be precludeed if the foetus or neonate is maintained in an environment in which hip and knee joints can be freely flex and reach outed in the absence of persistent tension of the iliopsoas and hamstring muscles.

Multiple genetic factors are thinking to be involved in the aetiology of this hip disorder, on the other hand it is incorrect to use of the terminus '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 exhibition Kyoto University, Japan

Copyright Western Pacific Orthopaedic Association Aug 2005

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