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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