When people approach me to ask about writing for DFTB I usually suggest that they write about what they know. That is certainly my approach and why I started to write the Normal Neonate series a year ago. The littlest Tagg has just had her year’s check up with the maternal and child health nurse. She thought that tiny Tagg had uneven buttock creases and wanted her assessed for DDH. But how sensitive is this sign?
What is DDH?
DDH or developmental dysplasia of the hip has replaced the term congenital dislocation of the hip and represents a spectrum of disease ranging from hip dislocation (around 1 per 1000) to more mild forms of dysplasia (40 per 1000) only detectable on ultrasound.
Why is it important to make the diagnosis?
If DDH is picked up early it can be treated in a non-operative manner with a Pavlik harness device. Firmly rooting the femoral head in the acetabulum of a normal joint encourages normal joint formation and re-modelling. By the time three months has passed more invasive treatments might be required. However we do need to consider the natural history of the disease. A Norwegian study that followed up 170 children with ultrasonographically abnormal but clinically normal hips found no real difference in radiographs obtained between six and eight years later. The real concern is that a delay in diagnosis leads to limb shortening, an abnormal gait, and long-term consequences such as an increased rate of osteoarthritis and back pain in adulthood.
In 2011 Roposch et al. attempted to establish a global consensus for the diagnostic criteria for DDH. 467 healthcare professionals came up with 212 criteria – clearly not practical in the real world. These were then sent to 261 orthopaedic surgeons and they whittled these down to 37. Around a third of these were related to history and risk factors, a third related to physical exam and a third related to imaging.
Some patients are more at risk than others and so the diagnosis is more likely. Risk factors include:
- Female gender
- First born child
- First degree relative or family history of DDH
- Birth weight >4000g
- Oligohydramnios during pregnancy
- Caesarean birth
- Breech presentation
So there are some genetic factors that lead to anatomical variants (acetabular dysplasia, anteversion of the femoral neck) coupled with in utero factors that put the hip at greater risk of posterior displacement.
I remember, as a medical student, being somewhat confused by the fancy yoga moves the paediatricians seemed to be putting the babies through – the Ortolani and Barlow’s tests. In Barlow’s manoeuvre the hip can be dislocated posteriorly with hip ADduction and posterior pressure. Ortolani demonstrated that ABduction and anterior pressure would relocate the hip. He felt that this ‘scatto’ or hip clicking was much more sensitive than traditional radiography at picking up DDH. But are they really any good?
The current gold standard, ultrasonography, was introduced in the 1980s by Graf as a non-invasive form of imaging that did not require exposure to ionizing radiation. Baronciani et al tried to compare clinician diagnosis with ultrasound diagnosis in an undifferentiated cohort of children. Each of the 4648 kids had a number of clinical examinations in the days after birth and then they were all followed up with ultrasound by a month of age. 5.1% (233 of the 3648) had a positive Ortolani-Barlow test. The universal screening picked up a type IIa DDH in 44.8% of the subjects. When these were followed up with repeat ultrasound at 2 1/2 months the vast majority of these (83.1%) had normalized, 16% were conformed as type IIa, and 0.9% were worse. So, Ortolani-Barlow – not a great test for picking up DDH – in that a normal test doesn’t rule it out.
Who were Ortolani and Barlow?
Marino Ortolani (b. 25 July 1904 – d. 1983) was an Italian paediatrician who described his eponymous test in 1937. The Barlow manoeuvre is named after an English orthopaedic surgeon, Thomas Barlow (b. 25 Sept 1915 – d.25 May 1975) who first described his test in 1962. The original papers are listed in the references below.
And what about those asymmetric buttock creases?
Going by the classic joint examination mantra of look-feel-move we should inspect the lower limbs before we even lay on hands. An apparent difference in femur lengths (because the hip is subluxed) may manifest as asymmetric buttock (not skin) creases or a positive Galeazzi sign. When you lay an infant on their back with the feet flat on the table and ankle to buttocks, both legs should be the same length. An apparent discrepancy is a positive Galeazzi sign.
Asymmetric gluteal folds or adductor folds are seen in 30-71% of normal infants. In one series of 187 children referred with asymmetric thigh creases alone (in the absence of any other signs) only one child required intervention.
With that (lack) of sensitivity there has to be a better way…
Ultrasound of hip
Ultrasound is the most effective test in infants below the age of six months of age. The ossification centre of the femoral head only appears between 4 and 7 months so it is much more reliable. A static (in Graf’s ‘standard’ plane) and dynamic visualization of the joint combined is most likely to pick up DDH.
After six months x-rays are a much more reliable method of looking for enlocation of the femoral head. Rather than just plagiarizing a text book I would point you to Frank Gaillard and Yuranga Weerakkody’s Radiopaedia post on developmental dysplasia of the hip.
If the traditional screening tests, the Ortolani and Barlow manoeuvres are so unreliable, should universal screening via ultrasound be instituted? We’ve seen that the vast majority of cases normalize by three months without intervention so does this mean more children will be treated unnecessarily? Wright and Eastwood examined the impact of a screening program in Paediatric Orthopaedics earlier this year. It is unclear as to whether a screening program actually improves outcomes as there is no gold standard definition of DDH and rates of immobilization or surgery are just surrogate endpoints. We don’t know what would have happened if nature had been allowed to take its course.
Perhaps, rather than being used as a universal screening tool, ultrasound should be used in a selected high risk population. Unfortunately a number of studies have found that patients who present late had an absence of traditional risk factors such as those listed above. Universal clinical screening was introduced in the UK in 1969 and seems to have had no impact on the rates of late presentations of DDH according to Goodward et al.
So what is the bottom line? Clinical examination is unreliable with asymmetric skin creases being present in a large percentage of the population. In the absence of any other clinical signs AND no risk factors, the diagnosis of DDH is highly unlikely.
Seringe R, Bonnet JC, Katti E. Pathogeny and natural history of congenital dislocation of the hip. Orthopaedics & Traumatology: Surgery & Research. 2014 Feb 28;100(1):59-67.
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Roposch A, Liu LQ, Hefti F, Clarke NM, Wedge JH. Standardized diagnostic criteria for developmental dysplasia of the hip in early infancy. Clinical Orthopaedics and Related Research®. 2011 Dec 1;469(12):3451-61.
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