Custom made vs sham foot orthotics for achilles tendinopathy

I recently reviewed a study that showed foot orthotics reduced the load in the Achilles tendon but lamented by reflecting on comments that this was not a clinical trial, but a lab based study. Nothing wrong with that, but without field or clinical based studies we do not know if those lab based effects can be translated to the field or clinic. Previous studies on this had mixed results with one showing quite dramatic positive effects of foot orthotics, but lacked a control group and others had the potential for too much bias. Now we have a properly controlled study on this:

Effectiveness of customised foot orthoses for Achilles tendinopathy: a randomised controlled trial
Shannon E Munteanu, Lisa A Scott, Daniel R Bonanno, Karl B Landorf, Tania Pizzari, Jill L Cook, Hylton B Menz
Br J Sports Med doi:10.1136/bjsports-2014-093845
Aim To evaluate the effectiveness of customised foot orthoses in chronic mid-portion Achilles tendinopathy.
Methods This was a participant-blinded, parallel-group randomised controlled trial at a single centre (La Trobe University, Melbourne, Australia). One hundred and forty participants aged 18–55 years with mid-portion Achilles tendinopathy were randomised to receive eccentric calf muscle exercises with either customised foot orthoses (intervention group) or sham foot orthoses (control group). Allocation to intervention was concealed. The Victorian Institute of Sports Assessment-Achilles (VISA-A) questionnaire was completed at baseline, then at 1, 3, 6 and 12 months, with 3 months being the primary end point. Differences between groups were analysed using intention to treat with analysis of covariance.
Results After randomisation into the customised foot orthoses group (n=67) or sham foot orthoses group (n=73), there was 70.7% follow-up of participants at 3 months. There were no significant differences between groups at any time point. At 3 months, the mean (SD) VISA-A score was 82.1 (16.3) and 79.2 (20.0) points for the customised and sham foot orthosis groups, respectively (adjusted mean difference (95% CI)=2.6 (−2.9 to 8.0), p=0.353). There were no clinically meaningful differences between groups in any of the secondary outcome measures.
Conclusions Customised foot orthoses, prescribed according to the protocol in this study, are no more effective than sham foot orthoses for reducing symptoms and improving function in people with mid-portion Achilles tendinopathy undergoing an eccentric calf muscle exercise programme.

This study ticked so many boxes that I have whinged about in so many studies not doing (a priori sample size calculation; proper randomization; blinding; intention to treat analysis; between groups analysis; prior registration of primary end point; etc). Nothing jumps out at me as a problem (and, no they not just getting a free pass as the authors are friends of mine!). The only issue that I might have is that there was a high drop out rate and the data was analysed using the intention to treat analysis which is what you are supposed to do. Given that the drop out rate was the same for both groups and there was apparently a similarity between the characteristics of the drop outs between the two groups, this may not be an issue. I am sure some will make an issue of this!

As with any foot orthotic study (and I have commented on this many times before), I ask myself, “are the foot orthotics that are used in the study typically and commonly used by experienced clinicians in clinical practice?“. In a lot of studies, they fail on that. That was a real strength of this study, the custom made foot orthotics that were used in this study were much closer to the type and prescription protocol that is used in clinical practice than almost all other studies that have looked at this, but did it go far enough? There will be many clinicians who do not agree as to if this was the most appropriate foot orthotic protocol for Achilles tendinopathy, but that just reflects the dilemma in researching foot orthotics. There are so many different types of foot orthotics and each type has many different design features that theoretically will have different kinematic and kinetic effects. Getting a good consensus on this is going to be difficult, if not impossible. For example, many will argue that the “posting to vertical” which was done in the study is something that is historical and that many experienced clinicians do not really do that any more (I don’t). If the study did or did not do that, would the result have been different? Many clinicians will also argue that to give everyone with Achilles tendinopathy a foot orthotic in clinical practice is bad practice and the only ones that should get a foot orthotic are those who have a treatment direction test (eg the lunge I mentioned here) that theoretically indicates the potential for a foot orthotic to help. Should they be the only ones who get a foot orthotic? Would the results of such a study be different to the one above if that was done?

Neither the custom made foot orthotic or the sham foot orthotic used in the study had the design features of the device that was used in the study on foot orthotics that showed a reduction in load in the achilles tendon in the lab. Is that an issue? Would they have got a different result if they used foot orthotics with those design features?

Too many questions and no answers!

What exactly did the study show? We have to be slaves to the data …. it showed eccentric loading works, but the addition of custom made foot orthotics with the design features and prescription protocol that was used in the study did not add any additional benefit over a sham ineffective type foot orthotics. The interpretation and spin of this finding will depend on preconceived biases, and that is already happening in social media. I just wish those commenting would actually read the study before they comment.

As always, I go where the evidence takes me until convinced otherwise …. and foot orthotic studies are ‘too hard’! 🙂

Munteanu, S., Munteanu, L., Landorf, K., Bonanno, D., Pizzari, T., Cook, J., & Menz, H. (2013). Effectiveness of customised foot orthoses for the treatment of Achilles tendinopathy: Preliminary findings of a randomised controlled trial Journal of Science and Medicine in Sport, 16 DOI: 10.1016/j.jsams.2013.10.065

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