Wednesday, 14 March 2018

Paediatric Orthopaedic Problems of the Legs Pt 1 - Greater love hath no colleague than to give guidance rather than a guideline

Last month, the paediatric orthopaedic surgeons at Sheffield Children's Hospital sent out a call for the Primary Care community to ask them questions about common presentations. Unsurprisingly many of the questions were regarding things to do with growing legs.  Although there seems to be a guideline for everything, there is none for such problems.  While it would be possible to make such a guideline, referral pathways vary and guidelines do not always apply to every child.

It is a common concern: Are my child's legs normal?  Much of the time, children’s legs seem to be a 'funny shape'.  The vast majority of the time, these legs are normal.  This is the problem with paediatrics though: for everything that is normal or benign, there is an evil twin.  A relatively rare problem that is neither normal nor benign.  These complex problems usually have a considerable overlap with the simple ones and so can be difficult to spot.

To break with convention, we've put together some guidance which should apply across all the common presentations of growing legs.  That way, clinicians have a framework that allows them to make an assessment, rather than a rigid decision tool that tells people what to do and what not to do.  How refreshing!

The first thing to cover, is what is normal in growing legs.  As a general rule, things start to point out, then in and then straighten up as a child grows into their adult body.  

Fig 1. From birth, children's knees will tend to go into varus and then valgus before becoming a normal adult shape.  Bandy legs (also called bow legs) are therefore expected in a child under the age of three and knock knees are considered normal until roughly 8 years old.  Genu valgum may persist into adolescence without any need for intervention.

The other simple rule of thumb is that normal legs are symmetrical, function normally and are not associated with any other abnormality.  This applies to pretty much every scenario - Genu valgum, genu varus, in-toeing, flat feet, hypermobility, "growing pains" and tiptoe walking.

In general terms, the following presentations are normal unless there is reason to think otherwise (see red flags above):
  • Bow legs (genu varus), in a child up to the age of 2 years
  • Knock knees (genu valgum), in a child up to the age of 3 years or up to the age of 10 if resolving
  • In-toeing gait (also called pigeon toe) up to the age of about 9
  • Flat feet on weight bearing
  • Tip toe walking in toddlers
  • Hypermobility

The lovely thing about all of them is that the history and examination required is usually brief.  It is rare to need to refer or investigate.  What's wrong with  this child's legs?  Usually nothing, but more on that in the next GPpaedsTips post.

Many thanks to the paediatric orthopaedic team at Sheffield Children's Hospital for taking the time to answer questions and to turn their expertise into guidance.  At a time when Primary Care Guidelines are often written by Secondary Care clinicians, I find it most refreshing that someone is willing to give their time to share insights and provide general guidance which facilitates rather than dictates management in Primary Care.

Edward Snelson
The Hitchcock of Free Open Access Medical Education

Disclaimer:  All of the above is based on a standard number of legs.  For any variation on two legs, discuss with your local orthopaedic surgeon or possibly a vet.


  1. Great post as usual Ed.
    I wonder whether the degree of bowing is important when considering nirmality. I am thinking particularly about Vit D deficient kids with early rickets. In my experience, they do have quite pronounced bowing which is much more apparent when they start toddling.

    1. In the past I've always been told that in the absence of red flags (see above) or other signs of rickets (wrists, forehead, fractures etc) then rickets is unlikely. It makes sense that there is a limit on that. We don't see enough rickets in the UK to be able to say how often it causes severe bowing without other signs, pain or loss of function.