8 year old boy functional hallux abduction

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Hi all

I have seen a young lad of 8 who's parents where worried about intoeing. Upon examination he has slightly equinus ankles and tight hamstrings, lateral STJ axis, but no other biomechanical variation. He has a narrow rectus foot type with average arch height and normal joint RoMs and stiffness. I open chain the foot is quite normal in shape and posture.

When he walks with shoes on he toes in left about 10dgs and right about 15dgs. However with shoes off he does not toe in but instead severely adducts (i.e. toward the body centre line) the hallux of both feet. The right adducts about 70dgs and the left about 35dgs.

In gait unshod he tends to slightly supinate thru most of stance phase, has an early heel lift and often tends to walk on toes slightly. I mobilised the ankles and released the hamstrings to give good RoMs in magnitude and quality, plus I fitted felt valgus (lateral wedge) forefoot posts and heel lifts adhered to the bare feet but this made no difference.
I thought that he might be reaching for the ground with the hallux as the foot supinated in some weird attempt to stabilise the foot.

I could imagine that if he had a rectus narrow foot and pronated then the adducting action might be to resist pronation but the foot tends to supinate in stance phase??

Maybe this is an habitual thing and leaving the foot laterally posted might result in the hallux not adducting after a while.

Any suggestions on this one would be greatly appreciated.

regards Dave Smith

 

What is his birth and developmental history?

How were his reflexes, change in active/passive tone?
What was hip ROM and adductor ROM?

It makes me nervous when kids have a number of tight muscles.

 

Cylie

Nothing remarkable admitted to and as I say his feet look perfectly normal in every other respect except the adducting hallux in gait. There is no metatarsus adductus and in fact the 1st ray is rectus with a met aduction angle of I would guess around 7dgs (not measured)

Reflexes and all RoMs normal unless mentioned above and no detectable neurological changes. Tight hamstrings and ankle RoM is quite usual on young boys I find and not in itself a cause for concern. They were only slightly tight and after mobs and releases were good. Thanks for your reply did you have anything in mind as to the reason for the adducting hallux?

Regards Dave

 

OOps! I just noticed I put hallux abduction on the title, can this be changed to Adduction?

 

Maybe this is an habitual thing and leaving the foot laterally posted might result in the hallux not adducting after a while.

I would probably agree with that and in the mean time, perhaps taping the hallux to the second toe.

I would rule out a tight abductor hallucis tendon and I would take radiographs to ascertain that the medial sesmoid is not medially displaced. This would be rare in a child just as spasm of the abductor hallucis muscle would be rare.

Still, I have only seen hallux adduction/varus as a complication from bunion correction creating weakening of the lateral side of the first MPJ.

Steven

 

Steven

I understand your thinking and I had considered those type of things briefly, (except for x ray for sesamoid displacement). However, it appears that the hallux adduction is some kind of effort to stabilise the foot in terms of moments about the STJ and I make this assumption because the feet toe in when the hallux is restricted from adduction when in shoes. If there were some muscle spasm or displaced sesamoid or hip rotator tightness then this would still be apparent or unchanged with or without shoes on??

Cheers Dave

 

David,

Perhaps your patient has congenital primary hallux adduction due to medial insertion of the tendon rather than a medial plantar insertion thus allowing for more adduction.

http://www.ocpm.edu/hallux/HV chapter 22-Hallux Varus.pdf

Steven

 

Steven

Thanks for the paper, I'll have to get further investigations done in line with your suggestion and re- evaluate the clinical picture. Perhaps I'll post a video of the toe action. Interesting that there appears to be no literature that describes this particular problem exactly.

Regards Dave

 

Based on what you have said I think what Steven about insertion may definitely worth considering.

That being said, I don't usually find that healthy 8 year olds get ankle equinus or tight hamstring without some neurological component but then our "tight" ranges may be on different scales. I have had some kids with mild CP that due to the the tightness at the gastrocs and hams, and some mild tightness in the adductors actually try and stablise the foot by adducting the hallux.

Sounds interesting, photo's would help if you do get a chance.

 

OK I'll run with that thought: Are you are saying that the tight adductor (of the hip) and gastroc - hammies chain cause destabilisation of the STJ ?
And so you propose that adduction. i.e. medial displacement toward the body centre line of the hallux, will stabilize the STJ. So, the hallux will produce a relative supination moment about the STJ - ergo - the foot (assuming stj) instability means excessive pronation moments cause by the aforementioned tightness.

But wouldn't the action of the tension in the Achilles tendon tend to produce supination moments?

But what if the STJ axis being laterally rotated means that the posterior projection of the STJ axis is actually medial to the calc bisection, then this might cause the tension in the Ach ten to produce a pronation moment at heel strike that requires some opposing action?? However the hallux adduction occurs later in the stance cycle and at this point the GRF acting of the mid and forefoot would produce a supination moment anyway and negate the need to adduct the hallux, Hmm!:dizzy:

Cylie, I'll get that video asap. thanks for our continued input

Cheers Dave

 

Woah, this is why I like developmental paeds and not crash hot on biomechanics.

Now, I agree that kids get tight with grow but this is why we have normal ranges, there is a tight and long normal range. As long they are normal then all good but to me, that is then still normal. If there are more than 2 muscles tight in a child then to me, there are warnings to look closer. Ensure child wasn't prem, wasn't a complicated delivery, no NICU stays, no low birth weight, no early hospitalisations etc.

Out of interest, do you measure the ranges and with what measurement? What is the FPI?

Also, is there any tibial torsion, femoral antetorsion/anteversion? The toe may just be gripping on for dear life as everything else is going through the lateral border of the foot and leg. I am not sure we can translate the well known adult relationship of tight achilles, leads to a more pronated foot type to kids as in my experience with toe walking kids who all have tight achilles, their foot types are really similar to kids without tight achilles.

All sounds fascinating.