No system is perfect, but this study from a more tightly controlled setting suggests we need some tweaks in our screening practices.
Source: Talbot C, Adam J, Paton R. Late presentation of developmental dysplasia
of the hip: A 15-year observational study. Bone Joint J. 2017;99-B(9):1250-1255; doi:10.1302/0301-620X.99B9.BJJ-2016-1325.R1. See AAP Grand Rounds commentary by Dr. William Hennrikus (subscription required).
Developmental dysplasia of the hip (DDH) is the focus of screening examinations in the newborn period. Early identification can prevent need for more complicated treatment, such as casting or surgical correction, that may be necessary when DDH is diagnosed after 3-6 months of age. The current study from the United Kingdom looked at over 64,000 live births in a 15-year period. Screening for DDH in this setting was fairly regimented, with recommendations for 2 evaluations, soon after birth and at 6-8 weeks of age. Sonography was performed if an infant had abnormal screening exam or if risk factors (breech delivery or family history of DDH) were present. This was a prospective observational study, with the data being analyzed retrospectively, so not as tight a clinical design as we would see with case-control or interventional studies. The authors' stated study aim was to look at factors associated with late presentations of DDH.
One of the first things I think about with such a large number of study participants over many years is how many subjects did not have the intended screening exams. I would expect a number of infants to slip through the cracks, no clinical system is that good! I was disappointed to see that the authors didn't quite tell us that information. They did exclude infants who were too ill for the Ortolani and Barlow examination maneuvers, such as infants in intensive care, as well as infants with underlying conditions that would predispose to hip dislocation, but they don't tell us how many of the 64,000+ babies this represented.
Those issues aside, the bulk of the study focused on the 31 infants who were found to have irreducible hip dislocations at the first visit to the pediatric orthopedist. Eighteen of these were designated as "late presenting," defined as diagnosis after 3 months of age. Two of the 18 were due to scheduling mishaps, leaving 16 babies as the focus of this study.
Here's where an observational study can be of help to the front-line practitioner. All 16 late presenting irreducible DDH patients had normal exams at birth and "no recorded abnormality" at the 6-8 week exam. Of course that latter designation might mean they weren't examined for DDH at that time, rather than being examined and having normal findings. The authors note that the 6-8 week time frame is the gray zone of 2 - 10 weeks of age where the findings of irreducibility haven't yet developed. Also, the Ortolani and Barlow maneuvers aren't particularly sensitive, which is a bad thing for a screening test. One suggestion from this study is for providers to continue evaluating for DDH beyond 6-8 weeks, though this aspect wasn't really addressed specifically in this study.
Another help to primary care providers are the specific findings of these late presenters. A discrepancy in leg length and limited abduction were the 2 most common reasons for referral; other reasons included limp, toe walking, delayed walking, "coordination problems," and abnormal skin crease. As you can see from this list, many (in fact most) of these children were not identified until after a year of age. Also, 2 of the infants had a risk factor of a close family member with DDH that should have triggered earlier evaluation, but they were either not asked about family history or did not know about the family member's diagnosis.
So, although this is "just" an observational study and not a sexy meta-analysis or randomized controlled trial, the large sample size and relatively uniform management features help translate the findings into useful information that frontline healthcare providers can apply immediately! This also might be a good time to re-read theAAP's 2016 guidelines on this topic, which recommends "periodic" screening.