Yeah that is an inconvenient study. I beleive the man himself referred to it as "a beautiful truth killed by an ugly fact" or some such.
The study is here for them as have not read it.
which commented their orthotic increased the intermetatarsal angle; and therefore increased the progression of the hallux valgus, as well as unilateral hallux valgus the orthoses did not halt the development in HV in the normal foot.
I will point out, as Simon did to me some years ago when we discussed this, that the study did not show that the orthotic increased the IM angle. It showed that the group with orthotics had a slightly higher IM angle than those who did'nt. Post hoc ergo propter hoc and all that. However.
What are your views on this and do you know of any other papers that contradict/concur with these findings?
I think its fascinating how hard we all find it to accept this data. We have a somewhat shaky deductive hypothesis, that "overpronation
causes HAV". We have data in hand that THESE orthotics in THIS study did'nt. It causes a real mental wrench to try to look at the data without bias.
It states that the children had a biomechanical examination as described by root orien and Weed (1971) and were prescribed orthotics to prevent excessive pronation of the sub talar joint. It further states that these orthotic "wedge the forefoot and hindfoot."
Now the inclusion criteria for the study was an MPJ of 14.5 degrees. No mention of foot function in the inclusion criteria. Yet they were all assessed and all ended up with insoles to limit "excessive pronation". This in itself is something worthy of discussion, that with that assessment protocol EVERYBODY needed an orthotic to "prevent excessive pronation". However I digress.
The question I would ask is this. I don't think anyone would claim to fully understand the link between Pronation and 1st ray / mpj pathology and HAV. However we DO know that the more pronated a foot, the more the 1st met has to dorsiflex to accomodate it. And we know that dorsiflexing the 1st met tends to increase internal plantarflexion moments which in turn can lead to FNHL. So there an argument that limiting pronation can reduce forces in the 1st MPJ. Fair enough?
But how are they limiting pronation? By using an orthotic with a rearfoot AND FOREFOOT wedge. And what will a forefoot wedge do to the 1st ray?
If we're trying to control pronation to reduce dorsiflexion moments on the 1st met there are probably better ways to do it than by dorsiflexing the 1st met. It might control the pronation but thats something of a pyrrhic victory.
For this reason I'm generally really quite reluctant to use forefoot varus wedging on children (barring sports insoles). Apart from the immediate risk of blockade to the windlass I'd be worried about causing a supinatus!
It might not be anything to do with that, but its a thought.