We have been delighted to learn so much by virtue of the evidence elucidated (and recommendations made) by our co-authors. Conversely, in a few areas where we thought the subject might have advanced, we have been reassured that we are at least up to date. In setting out the state of the evidence for our subspecialty, we hope to have also provided a resource for discussion and a basis for future research.

In the introduction, we sketched out the evidence-based approach to topic areas: ‘A clearly defined relevant question is required, followed serially by (i) identification of the studies/evidence by a thorough search of the literature, (ii) a critical appraisal of available evidence and its applicability to the clinical situation, and (iii) a balanced conclusion to the clinical problem and particular patient’ [1]. We have encouraged a pragmatic approach, not as exhaustive as a formal systematic review [2], to help practicing surgeons derive evidence-based answers to important clinical questions [3]. As in an earlier text, the Evidence for orthopaedics [4], we advocated appraisal of the literature with assignation of levels of evidence and, for each Chapter a focussed summary ‘Grades of recommendation’ table. The importance and practicalities of assignation of levels of evidence [5] were broached in Chap. 2 on critical appraisal [6].

The subject matter is diverse and, as with most multi-author texts, there is heterogeneity of approach and depth. Authors vary in their perceptions and experience of evidence-based medicine, and modes of analysis of the literature. For some topic areas, a major problem is formulating the right question(s) [7]. As put eloquently in Think like a freak [8]: ‘Before spending all your time and resources, it’s incredibly important to properly define the problem-or, better yet, re define the problem.’ Depending on the material to be addressed (but especially if the topic area is broad), a rapid scoping review, ‘mapping the existing literature or evidence base’ [9] may be a useful antecedent to defining the parameters of a more formal subsequent review (eg question based on PICO format: population, intervention, comparison, outcomes). In addition to the PICO formula, it is worth recognising that advice for resource-rich environments may differ substantially from that for resource-poor ones ie that the study setting can be important too [10].

Since the early 2000s, the reporting of levels of evidence linked to paediatric orthopaedic studies has yet to be associated with an increase in the proportionate quality of evidence per se [11]. An analysis of data from the Journal of Paediatric Orthopaedics 2009–2013 was interpreted as reflecting a trend in overall improvement in methodology, though this was largely as a result of the increase of self assignation of level of evidence, rather than a demonstrable change in proportions of higher level studies performed [12].