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DISLOCATED HIPS IN THE INFANT‐A SOLVED PROBLEM?

SEVERAL years have passed since a campaign was mounted to detect instability of the hip joints in newborn babies. This was inspired by the proposition that, providing splinting in abduction was applied early enough, it would prevent dislocation or subluxation from developing in the future. The time is now appropriate to take stock of the integrity of this assumption. 25 patients over six months of age presented with untreated dislocations or subluxations at the Hospital for Sick Children during the year ending in December 1970, in contrast to 48 during 1962. Whilst this is a commendable improvement, it nevertheless falls short of the aspirations of the abolitionists. Only two explanations are possible-either the proposition is wrong or our methods of examination are faulty. The proposition is probably well founded, for in closed communities such as Malmo, where all the babies are delivered in one place, established dislocation has been virtually eliminated. The same applies in Edinburgh, where intensive propaganda, coupled with the segregation of primiparae and those in whom there is a possibility of obstetric difficulty to one hospital, has been equally successful. Furthermore, these centres have in common members of the permanent staff experienced in the assessment of infants’ hip joints. We must, therefore, consider further our techniques of examination and their application in practice. Methods of eliciting the jerk or clunk sign are too well known to need repetition. Hart’s Test and Barlow’s modification of Ortolani’s Test have been well summarized recently.1 In this country the latter is positive in about 2 per cent of babies examined within 48 hours of birth, and in about 75 per cent of these the hip reverts to clinical normality during the first weeks of life. Obstetric or paediatric House Physicians are therefore unlikely to detect the sign sufficiently often during their six month‘s appointment to become familiar with it. Those practicing midwifery in the home are even less likely to be rewarded. It is not surprising that initial enthusiasm becomes tainted with disillusion when this manoeuvre is repeatedly unprofitable. Before long, examination becomes a routine exercise dutifully performed in the interests of completing the case notes. This attitude is reinforced by the knowledge that, even if the sign is overlooked, three out of four unstable hips will correct themselves without treatment. Regardless of the care (not to say dedication) with which the sign is sought, there are two features which may prejudice success. Firstly, extensive hypotonia and joint laxity (a ‘prime factor’ in aetiology) may allow the hip to dislocate or reduce so readily that a jerk is difficult to detect. Secondly, it is more difficult to demonstrate the jerk of reduction (the hip being habitually dislocated but reducible) than that of dislocation (the hip being habitually in the socket but unstable). The first group is less common, but obviously is of far greater importance. Indeed, one may justifiably question the need to treat the second group, although surveillance (including a radiograph later) is necessary. Finally, it cannot be too strongly emphasised that a truly dislocated-in contrast to an unstable hip joint-will not reduce and so cannot provide a positive jerk sign, however young the baby. It is essential, therefore, that we also seek limitation of abduction in flexion (Hart’s sign) and, in unilateral dislocations, shortening. This is particularly important when there are predisposing factors, i.e., familial, breech presentation and joint laxity. In such patients the radiograph will be abnormal, showing obvious displacement at the femoral head; if it does not, the signs are due to pelvic obliquity, reflected in the radiograph as a spurious acetabular dysplasia. In the very young with unstable hips, radiographs are