This study determined the opinions of British paediatric orthopaedic surgeons about a set of 37 criteria which have been identified as the most relevant features for diagnosing DDH in the first 8 weeks of life [5]. Because all 37 criteria cannot be equally important, we wanted to delineate those identified as most and least important by British specialist surgeons and determine to what degree their opinions differ compared to specialists from other countries.
We note the potential limitations of this study. As clinical experience and exposure accumulate the symptoms and signs associated with a diagnosis are “chunked” together and not taken in isolation. By asking experts to rank individual criteria we have established the opinions of surgeons and this may not reflect their normal practice. However, individual criteria are important as they can act as a trigger to activate the relevant knowledge.
Surveys are an effective means of evaluating physicians’ attitudes [13] and evidence suggests that physicians act as they indicate in surveys [14]. The response rate of this survey was 68 %, however, this is reasonable considering that the mean response rate of surveys involving physicians is 54 % [15].
Members of BSCOS rated historically well-established diagnostic criteria such as the Ortolani test highest and controversial ones such as hip click lowest despite this being a common reason for referral. The opinions of British surgeons were consistent with an international group of paediatric orthopaedic surgeons – the top ten ranking criteria were identical with the exception that breech presentation was not included in the top-ten of the BSCOS panellists. The pattern of importance ratings was almost identical between BSCOS and EPOS (Fig. 1).
The fact that criteria related to the clinical examination were among the highest ranking in this study reflects other studies from the UK about the diagnosis of DDH in early infancy. Clarke et al. [16] based triage decisions of infants not older than 3 days on Ortolani, Barlow and Galeazzi tests. Talbot et al. [17] and Price et al. [18], examining the same age group, used Ortolani and Barlow tests but placed no emphasis on the Galeazzi test. Limited hip abduction was not reported as a diagnostic criterion in either of these 3 large studies. However, limited abduction ≥20° ranked third amongst BSCOS members. In fact, 3 criteria relating to hip abduction ranked top ten in our study; asymmetry in abduction ≥20°, abduction limited to 45° and any asymmetry in abduction. In contrast, a study of infants aged 3 to 10 months highlights the lack of reliability when relying on clinical examination alone, with 46 % of infants without DDH exhibiting a limit to hip abduction [19]. Of note, members of EPOS placed less value on the criterion hip abduction.
In terms of risk factors, members of BSCOS ranked highest family history and breech presentation (Table 2). This is in keeping with current practice: 3 recent studies on screening in DDH [16–18] utilized these 2 criteria to select at-risk patients prompting specialist referrals. In a study of 64 670 births, Talbot et al. [17] evaluated the incidence of DDH in patients with these 2 risk factors; the incidence was 3.2 % with a family history of DDH and 2.5 % with a breech presentation. Price et al. [20] examined, amongst others, the risk factors oligohydramnios and foot deformity but did not comment on their associations with DDH, suggesting that they had little value in predicting DDH. This is consistent with our survey these 2 criteria are among the lowest ranking.
While our study showed that members of BSCOS regarded ultrasound criteria as important in general, it also confirmed the ongoing controversy [2, 21] about the nature of ultrasound criteria. Three recent studies about hip screening showed that the ultrasound criteria by which surgeons defined DDH varied in the UK. While one study [16] utilized criteria based on dynamic ultrasound, another study [17] relied on the α angle in combination with dynamic criteria, and a third study [18] relied solely on the α angle. Our survey reflected this controversy – a dislocatable hip seen on dynamic ultrasound and an α angle <45° ranked among the top ten criteria, similar to the opinions of members of EPOS, but also the femoral head coverage as measured by ultrasound was rated highly (Table 2).
In quantifying how consistent members of BSCOS were in rating the 37 criteria we used the ICC. It provides a measure of the extent to which any single member identified at random would compare to any other randomly selected member. Coefficients for judgments on individual patients should reach values of 0.70 to 0.80 [22]. The best value that members of BSCOS reached was 0.52, indicating acceptable agreement about clinical examination criteria. Similar patterns were seen in an international study where paediatric orthopaedic surgeons were most consistent about clinical examination criteria [6]. In contrast, for criteria relating to patient history, ultrasound and radiography, large variations in the opinions of UK surgeons were seen. Members of BSCOS were least consistent about the ultrasonographic criteria; this may be related to the inconsistent evidence in terms of the use of this diagnostic modality. It also reflects current practice in the UK: 3 recent studies about hip screening employed different ultrasonographic criteria in defining DDH [16–18].
