The Conundrum of Developmental Dysplasia of the Hip

I know I’m old.

I know I’m old because the bits of me that used to be supple and strong are now weak and stiff, and the bits of me that used to be stiff are now flaccid.

I also know I’m old because I’m now regaling medical students with stories, usually starting with the words, “Back in my day …”

Back in my day, we didn’t have the internet and had to to go to the library to get actual books!

Back in my day, we couldn’t go on-line, we had to stand in lines …

Back in my day, we were taught about congenital dysplasia of the hip, and learning the nuances of the Barlow and Ortolani manoeuvres was one of the most important skills a young paediatric house officer could possess.

While age has made me go soft and stiff in all the wrong places, it does give the benefit of hindsight.  And with hindsight and further research, it turns out that my view of Congenital Hip Dysplasia was all wrong.

It’s not that hip dysplasia isn’t really important – it is.  A child with moderate to severe hip dysplasia is destined for a lot of physio and possibly surgery to try and help them walk and run and play normally.

It’s more that congenital dysplasia of the hip isn’t necessarily congenital, and the tests we were taught to perform to diagnose it really aren’t that helpful after all.

Developmental dysplasia of the hip (DDH), as explained in layman’s terms on the Kids Health Info website, is “an abnormal development of the hip joint. In children with DDH, the ball at the top of the thigh bone (called the head of the femur bone) is not stable within the socket (called the acetabulum). The ligaments of the hip joint that hold it together may also be loose. Sometimes, the hips can dislocate early in life and this may not be noticed until your child starts to walk.”[1]

More formally, the condition and its definition are more nuanced.  As per eMedicine: “The definition of DDH is not universally agreed upon. Typically, the term DDH is used in referring to patients who are born with dislocation or instability of the hip, which may then result in hip dysplasia. More broadly, DDH may be defined simply as abnormal growth of the hip … This condition may occur at any time, from conception to skeletal maturity.”[2]

Although there are some inconsistencies in the literature regarding incidence of DDH, it is generally accepted that approximately 1 in 100 infants will be identified as having some hip instability at birth, and 1 – 2 in 1000 infants will be born with a dislocated hip.[3]

There are a number of generally accepted risk factors associated with developmental dysplasia of the hip[4](although their validity is controversial[5]):

  • Breech Presentation
  • Family History of developmental dysplasia of the hip (especially if in parent or sibling)
  • Female Baby (developmental dysplasia of the hip is four times more likely to occur in a female infant)
  • Large Baby > 4kg
  • Overdue > 42 weeks
  • Oligohydramnios
  • Associated with Plagiocephaly, Torticollis and foot deformities
  • First born baby or multiple pregnancies

Of these risk factors, the most significant are breech presentation and family history[6].

Traditionally, all newborns are screened for DDH a number of times throughout their first year of life using the Barlow and Ortolani manoeuvres.

In the Barlow manoeuvre, “gentle backward pressure is applied to the head of each femur in turn, and a subluxable hip is suspected on the basis of palpable partial or complete displacement”.

In the Ortolani manoeuvre: “the examiner applies gentle forward pressure to each femoral head in turn, in an attempt to move a posteriorly dislocated femoral head forwards into the acetabulum. Palpable movement suggests that the hip is dislocated or subluxed, but reducible.”[7]

In older infants, the Galeazzi test may be performed: “Hips are flexed to 90° and placed in neutral adduction/abduction, with knees in flexion. In this position, the vertical level of the knees can be assessed for asymmetry.”[8]

Limited hip abduction is also a test used to attempt to elicit developmental dysplasia of the hip[9].  Asymmetrical gluteal and thigh skinfolds have also been considered signs of developmental dysplasia of the hip[10].  (A video demonstrating Barlow, Ortolani and Galeazzi signs is here: https://youtu.be/iKfoovi5gvI)

All this is well and good, but the effectiveness of clinical hip screening programmes internationally have been disputed in the published literature[11].  The U.S. Preventive Services Task Force gives screening for developmental dysplasia of the hip an “I” rating (insufficient evidence to recommend for or against screening) while the American Academy of Family Physicians endorses this “I” rating[12].  This is partly because the tests and manoeuvres for developmental dysplasia of the hip have very limited capacity to correctly detect a positive finding, and/or have a limited impact on significant clinical outcomes.

For example, the Ortolani test has a sensitivity[13]of 0.6 and the Barlow manoeuvre has a positive predictive value of just 0.22[14].  The Barlow and Ortolani manoeuvres fail “to identify two thirds of the hips which subsequently need surgical treatment and has made little or no difference to the number coming to surgery.”[15]

Hip abduction “is a relatively insensitive and nonspecific marker of DDH in early infancy but becomes more accurate after 3 to 6 months of age and with more severely affected hips.”[16]  Also, “physical examination findings sometimes linked to DDH include asymmetrical gluteal and thigh skinfolds, and leg-length discrepancy. No studies from the past 40 years were identified that assessed the value of these findings in diagnosing DDH.”[17]

So if clinical screening is next to useless, what about universal screening for DDH with ultrasound? Well, a Cochrane review showed that universal ultrasonography (versus clinical examination alone) resulted in a higher rate of detected developmental dysplasia of the hip and a higher rate of treatment, but it did not reduce the rate of missed (late-diagnosed) developmental dysplasia of the hip or the need for surgery.[18]

Why?  I’m not going to pretend to be an expert, but I think the key is that DDH isn’t fixed and stable, but is actually a dynamic condition in which the hip abnormality may improve or deteriorate with growth[19].  Paton wrote, “The term Congenital Dislocation of the Hip (CDH) was superseded by the new name of Developmental Dislocation of the Hip (DDH) in 1989. This was in recognition of the fact that not all cases of pathological hip conditions associated with DDH were present at birth.”

So, to screen or not to screen?  A generally accepted view is that screening with physical examination, compared with no screening or universal ultrasonography screening, would result in fewer adults having osteoarthritis of the hip at 60 years of age.[20] However, there is no published statistical difference in outcome measures of developmental dysplasia of the hip when comparing the various combinations of screening utilising clinical examination and ultrasonography.[21]

What does it mean medico-legally?  Some commentators believe it’s a very important point. Paton again, “If some hip joint conditions that are stable at birth deteriorate and are diagnosed at a later date as an irreducible hip dislocation, they cannot be considered to be ‘missed’ cases following negative neonatal clinical hip screening by a competent screener.”[22]

Lomax writes, “Medico-legally, if a clinical screening test is undertaken by an individual who has been properly trained and assessed as competent in the clinical test and a late irreducible dislocation occurs, this should not be considered negligent due to the poor sensitivity and positive predictive value of the tests.”[23]

For mine, I think the key is to remain vigilant.  It may not make a massive difference to the eventual outcome, but given that Barlow, Ortolani and Galeazzi tests are easy to learn and very cheap to do, I think we should continue to perform them.  Having said that, we should remain vigilant and not ignore an infant who has limited hip abduction or a limp at any age.

I think that’s sage advice no matter how young or old you are!

Summary points:

  • Developmental dysplasia of the hip refers to patients who are born with dislocation or instability of the hip or more broadly as an abnormal growth of the hip
  • DDH is a dynamic condition which may occur at any time from conception to skeletal maturity
  • The most significant risk factors for DDH are breech presentation and family history
  • The most common tests for diagnosis of DDH are Barlow, Ortolani and Galeazzi signs
  • However, the tests and manoeuvres for developmental dysplasia of the hip have very limited capacity to correctly detect a positive finding, and/or have a limited impact on significant clinical outcomes
  • Universal ultrasonography resulted in a higher rate of detection and reatment, but no reduction in missed (late-diagnosed) DDH or surgery
  • Consensus is that screening with physical examination, compared with no screening or universal ultrasonography screening, would result in fewer adults having osteoarthritis of the hip at 60 years of age.
  • However, there’s no published statistical difference in outcome measures of DDH comparing various combinations of screening utilising clinical examination and ultrasonography.

References

[1]Kids Health Info, “Developmental dysplasia of the hip (DDH)” Royal Children’s Hospital, Melbourne, 2018. https://www.rch.org.au/kidsinfo/fact_sheets/Developmental_dysplasia_of_the_hip_DDH_treatment_and_hospital_stay/ (Accessed 12/4/2018)

[2]eMedicine, “Background / Developmental Dysplasia of the Hip” https://emedicine.medscape.com/article/1248135-overview Updated: Feb 26, 2018 Accessed: 12 Apr 2018

[3]”Screening, Assessment and Management of Developmental Dysplasia of the Hip. Clinical Practice Guideline: Resource Manual 5/05/2011″ Hunter New England Local Health District – Children, Young People & Families, NSW Health http://www.hnekidshealth.nsw.gov.au/client_images/1287736.pdf Accessed 12/4/2018

[4]ibid

[5]Paton RW. Screening in Developmental Dysplasia of the Hip (DDH). Surgeon 2017 Oct;15(5):290-96.

[6]”Screening, Assessment and Management of Developmental Dysplasia of the Hip”, 2011.

[7]Payne, J. “Developmental Dysplasia of the Hip” Patient https://patient.info/doctor/developmental-dysplasia-of-the-hip-pro Updated: 23 Sep 2016 Accessed 12/4/2018

[8]”Screening, Assessment and Management of Developmental Dysplasia of the Hip”, 2011.

[9]ibid

[10]Shipman SA, Helfand M, Moyer VA, Yawn BP. Screening for developmental dysplasia of the hip: a systematic literature review for the US Preventive Services Task Force. Pediatrics 2006 Mar;117(3):e557-76

[11]Paton RW. Screening in Developmental Dysplasia of the Hip (DDH). Surgeon 2017 Oct;15(5):290-96.

[12]Jackson JC, Runge MM, Nye NS. Common questions about developmental dysplasia of the hip. Am Fam Physician 2014 Dec 15;90(12):843-50

[13]Sensitivity is the probability of being test positive when the condition is present, or the ability of a test to correctly classify an individual as ′diseased′.  The positive predictive value is the percentage of patients with a positive test who actually have the disease ~ Parikh R, Mathai A, Parikh S, Chandra Sekhar G, Thomas R. Understanding and using sensitivity, specificity and predictive values. Indian J Ophthalmol 2008 Jan-Feb;56(1):45-50

[14]Paton, 2017

[15]Robinson R. Effective screening in child health. BMJ: British Medical Journal 1998;316(7124):1.

[16]Shipman et al, 2006

[17]ibid

[18]Shorter D, Hong T, Osborn DA. Cochrane Review: Screening programmes for developmental dysplasia of the hip in newborn infants. Evid Based Child Health 2013 Jan;8(1):11-54.

[19]Paton, 2017

[20]Jackson et al, 2014

[21]Paton, 2017

[22]ibid

[23]Lomax A. Examination of the newborn: an evidence-based guide (2ndEd). John Wiley & Sons; 2015 Aug 17: p146

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For good number twos, lift your shoes, say some moos

What I’m about to tell you will change your life, forever.

In my job, I help people overcome some of life’s greatest challenges. When I was a medical student, fuelled by my strong sense of idealism and too many episodes of ER, I thought those challenges would be thumping on someone’s chest to save them from the clutches of death, or removing a gangrenous appendix with just a butter knife and some twine, or delivering a baby whilst upside down in some plane wreckage. You know, something heroic.

But from my first day as an intern, I learnt something … nothing is as life changing as a good poo.

You might be thinking something smells a little funny here … “one moment you’re talking about delivering babies and the next minute you’re talking about delivering Mr Hankey. How is that suddenly heroic?”

Sure, talking to people about their time on the porcelain throne isn’t particularly glamorous but the daily download, exorcising a demon, pressing towards the bowl … it’s vital. Not enjoying a regular Trump dump leads to stagnation in the literal and economic sense – chronic constipation costs the US over $18 billion dollars in additional health care costs, not to mention lost productivity.

So how does one regularly clean the pipes to ensure the health of our bowels and our budgets? Well, we’ve all heard that “fibre is your friend”, and that remains true, though most people don’t realise that fibre works better when you drink lots of water with it. So more veggies, and more water.

Though the main push of this particular post is a look at the production side of the Captain’s log. This was inspired by a blog I came across as I click-grazed across the internet the other night – http://www.evidentlycochrane.net/feet-up-constipation/

So apparently if you want your bowels to move efficiently, assume the crash position … “Lean forwards and rest elbows on knees, almost like the crash position on an aeroplane. The anal sphincter should relax …” Yep, the anal sphincter would definitely relax if one were really sitting in the crash position on an aeroplane, though I dare say it’s not the position that’s the key variable!

But, ok, the author of the blog does have a point – sitting with our hips flexed naturally reduces the otherwise convoluted path of our sigmoid colon to an efficiently straight rectal super-highway. One way to do that is to squat, but if you’re old, inflexible, or like me, no longer have a great sense of balance (or you’re trying to defecate whilst drunk) then squatting is probably not a good idea – you and your poo are likely to end up on the floor.

The alternative is the ‘crash position’, leaning forward slightly with your elbows on your thighs and putting your feet up on a small stool (the ‘stool stool’ and she called it!).

The other thing to do, although perhaps not in a public toilet or at a dinner party, is to moo. As the author said: “Leaning on the elbows and making a “moo” (or other) sound reduces the urge to strain” … Well, it works for cows I guess.

So, the bottom line: you need to lift your shoe and moo on the loo to poo.

See … life changing!

Ritalin may not help children with ADHD?

A few days ago, the media had a frenzy over a new study about the use of Ritalin (methylphenidate – a stimulant medication) for Attention Deficit Hyperactivity Disorder (ADHD) (http://goo.gl/Ht9GKF).

ADHD is always good for a headline grab because it is so polarizing. It’s like the new HIV – everyone’s got an opinion on ADHD, and most of them are facile or just plain ignorant. That doesn’t stop the armchair experts from sharing their opinions, and this new Cochrane review into the studies of Ritalin for ADHD just gives them another chance to vent their fatuous spleens.

Like a couple of the comments posted at the end of The Australian article. One suggested that ADHD was a disease invented so they could find another drug to treat it, and suggested that mobile phone games were the problem. Another thought he was rather humorous when he trotted out the tired old chestnut that it’s all the parents fault: “ADHD has been nicnamed {sic} ‘Absent Dad At Home’ syndrome!”  Sorry, but no one’s laughing. 

We need to take a step back from the uneducated and unwarranted opinion of the self-titled experts, and look at what the study actually said. To do that, lets have a look at what the study was, what it looked at, and what the results were. We’ll then compare the results with some of the other options available for treating ADHD, so we can make an informed decision about how to best manage ADHD.

First, what study are we talking about? The study in question is a Cochrane Review lead by Storebo, titled “Methylphenidate for children and adolescents with attention deficit hyperactivity disorder (ADHD)” [1]. (You can read the official press release here: http://www.cochrane.org/news/researchers-urge-caution-prescribing-commonly-used-drug-treat-adhd or the abstract here: http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD009885.pub2/abstract)

Cochrane reviews are scientific works that pool the best research on a particular topic and combine it into a mega-study, to get the best results available for a particular topic. First, all the papers written about the topic in question are found. The poorest quality studies are discarded, leaving studies that are suitable quality and are fairly uniform in how they did their research, so that the results from each study can be combined into one uniform result.

This process of meta-analysis increases the statistical power of the results enormously. The Cochrane Collaboration has been at the forefront of meta-analysis and has developed specific rules about the quality of evidence it accepts for its reviews, making a Cochrane review as trustworthy as medical research can be.

So what did the meta-analysis of methylphenidate for children with ADHD actually show? In short,

  • A strong improvement in the Teacher-Rated Symptoms score,
  • A strong improvement in the Teacher-Rated Behaviour score,
  • Small-to-moderate improvement in the ADHD rating scale,
  • Small increase in minor side effects such as poorer sleep and appetite, and
  • No increase in serious harm from methylphenidate.

So … that sounds pretty positive overall. Why the big hullabaloo? Why are these experts supposedly urging caution?

The concerns the researchers had was with the quality of the studies. Overall, the research that’s been done thus far has been deemed low quality by Cochrane’s standards. So they were cautious about suggesting that the results were reliable given the quality of the studies they had to work with. And that’s fair enough. Better quality studies are required to confirm the findings of the current Cochrane review, and this should be done as a matter of priority.

Unfortunately, the reviewer’s cautious approach to the research has been misinterpreted as a concern about the drug itself.

There are two important points here: 1. Accepting the limitations of the quality of the research it’s based on, the review still found a moderate effect of methylphenidate, and 2. Other “treatments” for ADHD have been proven in separate meta-analyses to be wholly ineffective.

There’s a little bit of statistical interpretation required here, but the Standardised Mean Difference (SMD, or sometimes called Cohens d) for the Teacher-Rated Symptoms score and Teacher-Rated Behaviour score was -0.77 and -0.87 respectively. The negative value here doesn’t mean that it’s bad; it’s just the arbitrary direction the reviewers chose to show improvement favouring Ritalin. Then there’s the SMD itself. The SMD takes into account the variability of the results overall, using a specific formula to take that into account.

The SMD used here doesn’t equate to the other value the reviewers used for the side effect statistics, which they expressed as a relative risk. So you can’t look at the numbers given and directly equate the power of the improvements with the chance of side effects of the medication.

However, it’s been said that an SMD of 0.2 is a small effect size, 0.5 is moderate, and 0.8 is large [2], so the effect of Ritalin given by the study was actually a strong effect. In comparison, the relative risk of minor adverse effects given by the review was 1.29, or a 29% increased risk, which is relatively small.

Then there’s the important consideration of the effects of other treatments for ADHD. The effect of Ritalin maybe backed by low quality evidence, but there’s no evidence of any effect for the other so-called ‘treatments’ for ADHD. As per the review by Sonuga-Barke (2013), there is a tiny amount of evidence for supplementation with omega-3 and 6 fatty acids, but none for:

  1. Elimination diets (including those for ‘antigenic’ foods, specific provoking foods, general elimination diets and ‘oligoantigenic’ diets)
  2. Food colouring (including certified food colours, Fein-gold diets and tartarazine)
  3. Cognitive training (including working memory specific, and attention specific training)
  4. Neurofeedback, and
  5. Behavioural intervention [3]

So no matter how inane or facile the arm-chair experts may be, there is no evidence that Ritalin for ADHD is harmful. There is a small risk of minor effects such as reduced appetite and sleep, but there is evidence (albeit low quality evidence) that it has a strong positive effect. In comparison, there’s no evidence of improvement from any other treatment that’s been adequately studied.

No drug is perfect, and that includes Ritalin. But it’s certainly not the devil in pill form either. It’s time to stop demonizing it, and ignorantly criticizing those children and their families who need it.

References

[1]       Storebo OJ, Ramstad E, Krogh HB, et al. Methylphenidate for children and adolescents with attention deficit hyperactivity disorder (ADHD). The Cochrane database of systematic reviews 2015 Nov 25;11:CD009885.
[2]       Faraone SV. Interpreting estimates of treatment effects: implications for managed care. P & T : a peer-reviewed journal for formulary management 2008 Dec;33(12):700-11.
[3]       Sonuga-Barke EJ, Brandeis D, Cortese S, et al. Nonpharmacological interventions for ADHD: systematic review and meta-analyses of randomized controlled trials of dietary and psychological treatments. The American journal of psychiatry 2013 Mar 1;170(3):275-89.