Hip dysplasia tests fail to recognise first-born female babies more at risk
Researchers at the University of Liverpool have reported that the NHS newborn physical examination practised in England and Wales can miss abnormalities of the hip.
As a medical negligence solicitor specialising in late diagnosis of Developmental Diagnosis of the Hip (DDH) claims, this comes as no surprise. Neither will it, I suspect, surprise paediatric orthopaedic surgeons around the country, who are left to perform complex corrective surgeries on young children after DDH was missed at birth.
The newborn physical examination involves performing the Barlow and Ortolani tests, which gently manipulate/manoeuvre the hips to check for instability. The research quotes that of 1,000 babies born, there were nine with dislocated hip(s) and, of these, the tests picked up four and missed five.
The results suggest a sensitivity rate of less than 50 per cent. However, the test results do not consider that:
- Tests undertaken in this study were carried out by experts in hip disease. These tests are usually carried out by midwives or other nurses less trained in picking up hip abnormalities.
- The only abnormalities considered in the study were dislocated hips. Most cases of hip dysplasia are not cases of dislocation, but of partial dislocation (subluxation) or 'instability'.
It goes without saying that the sensitivity rate of the Barlow and Ortolani tests in the real world is likely significantly less than that suggested in the recent study. Most previous studies put the sensitivity figure at around 25 per cent – meaning only one in four cases are picked up using the newborn infant physical examination.
One possible explanation for this is the ambiguity of what the examiner is trying to find. There was a time when hearing a click during the examination was a cause for concern – however, it is now known that a simple 'click' is of little or no clinical significance. A 'clunk' sound is significant, but how easy is it to distinguish? The examiner will look for any limitation of abduction – which can be useful diagnostically, but what if both hips appear slightly limited?
This would probably give the examiner some reassurance because there would be a degree of symmetry, but it could be a sign of bilateral hip dysplasia. Further, at what angle does a limitation of abduction begin? A very small number of cases might show obvious limitation and an ultrasound can be arranged, but most abnormal findings will be more nuanced. With all of these difficulties, together with a newborn patient unlikely to lie still, it is easy to see why so many abnormalities are missed. These points really hammer home just how important it is that, if the NHS is to continue to rely on the Barlow and Ortolani tests, they are undertaken by experienced and specialist practitioners who know what they are looking for.
In addition to the mandatory Barlow and Ortolani tests, the NHS seeks to identify those babies at an increased risk of having hip dysplasia by performing hip ultrasounds if there is a direct relative (parent or sibling) with hip dysplasia, or where the baby was breech at 36 weeks or later.
The problem with identifying these 'risk factors' is that they are not the most significant indicators of hip dysplasia. The two most significant red flags are:
- Female baby, and
- First born.
Clearly, performing ultrasounds using these red flags would mean well over the half of all newborns being scanned. But what is the problem with that? The NHS says costs – which is understandable, but how many corrective surgeries and hip replacement surgeries will be required in later life by failing to scan?
I have several cases where a negligently missed DDH diagnosis has resulted in a first hip replacement at 30 years old or earlier. This means probably four hip replacements during the patient's life, it means reliance on a wheelchair, it means round-the-clock care in old age, it means aids and equipment and modifications to accommodation, and it means umpteen therapies (occupational, physio, psycho, and others). In summary, it means a great cost to the NHS, and a greatly reduced quality of life for the patient.
The other reason the NHS argues against universal hip screening is the increased risk of false positives – because there would be human error in reading the ultrasound and normal hips might be misinterpreted as abnormal. This, says the NHS, would result in overtreatment of patients. Again, what does the risk benefit analysis say? Would there be false positive cases? Of course there would, but surely they can be minimised. Borderline abnormalities can be kept under review rather than rushing to apply a harness. And if a baby wears a harness for a few weeks unnecessarily, it's a price worth paying.
It is also worth pointing out that as AI has more and more of a role to play in radiology, the risk of human error diminishes.
The recent published study tells us what most knew already. Perhaps it is time to review how DDH is screened by the NHS, and to seriously consider scanning all newborn hips.