When a child is born, it is standard procedure to examine the newborn for a potentially disabling hip issue termed as developmental dysplasia before departing the maternity hospital. This check is repeated at the six-week examination. Yet, this routine clinical inspection has been brought into question by a collective of Irish medics due to its suggested low diagnostic accuracy, drawing attention to the possibility of implementing universal ultrasound screening.
At present, ultrasound screening is allocated routinely only to infants known to have risk factors in Ireland. However, in other European countries such as Germany and Austria, all newborns receive this screening. Paediatrician Prof Alfred Nicholson, who currently holds positions as vice-president for academic matters and medicine school head at the RCSI Medical University of Bahrain, oversaw a recent British Medical Journal article addressing these concerns. The article underlines the gravity of missing developmental dysplasia of the hip (DDH), which can necessitate surgical intervention and result in lifelong disability, potentially leading to substandard outcomes for the child.
Leading medics note that DDH remains one of the primary drivers for medical legal action against doctors in the field of general practice and paediatrics in the UK, US and Australia due to late diagnosis. Later detection of DDH involves corrective surgery during early life and dramatically enhances the possibility of premature osteoarthritis in those aged 50-60, putting hip replacement surgeries on the cards, warns Nicholson. A universal ultrasound screening, despite its risk of overtreatment, has been positively received in countries where it is common practice.
Most parents probably do not understand the reliability or lack thereof in spotting DDH during the newborn and six-week examinations. Therefore, it becomes essential to raise awareness about this condition.
To understand developmental dysplasia of the hip, it is important to know that it is the most frequent joint issue detected in newborns. The hip, similar to the shoulder, is one of the two ball-and-socket joints in our body that can cause complexities, particularly for infants where the spherical head of the thigh bone (femur) sits within the hip’s cup-shaped socket (acetabulum).
Prof John Murphy, a consultant neonatologist, explains that “congenital dislocation of the hip” was initially used to define the condition that affects the stability of hip bones in newborns. However, this perception was debunked since the condition does not necessarily show at birth. In some instances, a shallow or improperly deepened socket leads to an unstable hip, allowing the growing thigh bone to displace as the infant grows.
In Professor Murphy’s workplace, the National Maternity Hospital in Dublin, they find that a hip dislocation presents itself in five out of every 1,000 newborns, during clinical examinations and girls are three times more susceptible than boys.
Contrary to what one might expect, it occurs silently and painlessly, says Professor Murphy, who also directs the National Clinical Programme for Paediatrics and Neonatology. The lack of pain often leads to delayed diagnosis until a baby displays difficulty in crawling or a toddler limping. This delay consequently results in the need for corrective surgeries, hence the importance of early detection.
So, how can it be identified in newborns?
Upon birth, along with other routine medical checks, a baby’s hips are examined by a paediatrician or a specially-educated midwife at the maternity hospital. If an infant is considered at risk due to certain factors, an ultrasound is conducted between four to six weeks of birth, regardless of the physical examination’s outcome.
Risk factors include babies born in the breech position, with an increased likelihood of being affected by five times. If a sibling or parent previously had the condition, the newborn’s risk triples. Persistent breech presentation at 36 weeks, even if the baby adjusts before birth, is also deemed risky.
Approximately 20% of newborns are categorised as “at risk” and are subsequently referred to the universal selective hip ultrasound programme. This involves all 19 maternity hospitals and units across the nation, and this ultrasound screening is generally performed when the infant is between four and six weeks old.
In 2022, Holles Street saw 10,952 specific hip ultrasound procedures, accounting for 19.5% of the infants born that year. A further 3% of those initially classified as standard exhibited various levels of hip dysplasia. According to Professor Nicholson, the nation’s selective screening strategy remains efficient for high-risk instances. However, he emphasises that most late DDH diagnoses lack these risk factors.
Parents often wonder whether their newborns will undergo further hip examinations even when initially given a clean bill of health and without known risk factors. The answer is affirmative. The evaluations are often undertaken by GPs during the six-week-old check-up where they routinely inspect the infant’s hips, explains GP and BMJ article co-author Dr. Sarah Taaffe. She mentions that despite their experience, diagnosing DDH remains a challenge due to the exam’s low diagnostic accuracy at this age.
Additionally, public health professionals are crucial in identifying late DDH cases, a fact reiterated by both Dr. Taaffe and Professor Murphy. They caution parents to be vigilant during baby checks at three months and seven-nine months. A previous study observed that 66% of 84 late cases of DDH were originally reported by public health providers. All identified instances in a maternity hospital, by a GP or public health personnel, are then forwarded to a paediatric orthopaedic surgeon.
What about newborns diagnosed with DDH? Confirmatory ultrasound scans are usually the first step upon detection during a clinical check-up. If the ultrasound merely reveals dislocation risk, repeat ultrasounds may be scheduled for monitoring purposes, safe in the knowledge that ultrasounds, unlike X-rays, are radiation-free.
For infants under six months with validated DDH, the routine treatment plan involves the application of a Pavlik harness. Named after Czech surgeon Arnold Pavlik (1902-1965), this device holds the legs apart, allowing the hips to naturally correct their alignment. Typically, the harness is worn for roughly two to three months.
Professor Murphy explains that repositioning the bone head into the socket can be quite an uphill task in older infants. At this point, a procedure referred to as a “closed reduction” may be necessary, needing to be performed in an operating theatre under anaesthetic. In more challenging situations, an ‘open reduction’ might be necessitated to surgically reinsert the ball into the socket. The necessity for surgical intervention, maybe even more than once, increases the later the diagnosis of the hip issue is established.
Indeed, the number of infants needing surgical intervention for Developmental Dysplasia of the Hip (DDH) is roughly estimated to be around 0.4-0.6 per 1,000 infants, although determining the exact figures remains a challenge.
Moreover, in cases where diagnosis may have been overlooked, what should a parent be on the watch for? As weeks progress post-birth, Professor Murphy explains that an infant’s hips will start to tighten. You could notice some restriction of movement in one leg compared to the other as you change the baby’s nappy. At times, one leg may appear shorter, showing it has been dislocated upwards.
If concerns arise, getting an ultrasound scan is a simple procedure, your local maternity hospital should be able to perform this up to the infant reaching three months old. Any requirement for an X-ray beyond this point would likely be handled in a children’s hospital.
Signs to look out for including limping while walking or a leg drag while crawling, these are definite red flags.
The question of whether universal ultrasound screening should be realized is a valid one. There are pros and cons to it, Prof Murphy admits. It certainly would be more involving than selective screening given that it would require ultrasound screening for the over 60,000 newborns annually. Besides, babies can’t be screened before discharge from maternity hospitals because the hips’ immaturity would cause inaccurate readings. As such, screening would have to be scheduled for between four to six weeks post birth.
Furthermore, potential false positives and unnecessary over-treatment might be the downside if ultrasound screening becomes universal. This will need to be considered against the advantages of early diagnosis and management of undetected DDH cases.
Professor Murphy and his peers are keen for the National Screening Advisory Committee to deliberate on a proposed idea. They’re particularly interested in a balanced standpoint and highlight that there is no global screening process in place, not in the UK, Australia, or the USA. Yet, Murphy notes that universal screening would be the optimal route in a utopian scenario.
An independent board, the committee was set up in 2019 with the responsibility of providing guidance to the Health Minister. If they see merit in the proposal, the task would be handed over to the Health Information and Quality Authority. They would then evaluate the desirability and feasibility of such a service and advise the Health Minister accordingly.