I’m working on a variety of learning materials to teach clinical gait analysis at the moment. Our masters programme in clinical gait analysis should start in 8 months time. One thing I find really depressing is how little of our clinical reasoning for individual patients is based on biomechanics. Most of the interpretation we do is essentially learned and largely subjective pattern recognition. We don’t really understand the data in a way that approaches science.

There are numerous reasons for this but one of the issues is that the biomechanics of walking is not being developed at the right level. On the one hand we have a group of researchers, coalescing under the Dynamic Walking Group, who are developing extremely simple and often non-physiological models to explore very basic principles. On the other hand are researchers typified by (but not restricted to) the OpenSim project who are developing really complex computer models. Neither group, as far as I can see is having a significant impact on the clinical understanding of gait or affecting how we manage our patient’s conditions.

To my mind the simple models are just too simple – how do you use a model without muscles to understand the consequences of a spastic gasttrocnemius? Equally the complex models are too complex- it’s impractical to perform a full CMC analysis for every patient. Even if we did we wouldn’t know which results are robust indications of the biomechanics of the patient and which are consequences of modelling assumptions and parameters.

What we really need is models that are neither too simple nor too complex – borrowing from modern astrophysics we need them to inhabit the Goldilocks zone – Goldilocks biomechanics.