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Is there any difference in the treatment of structural/functional hallux limitus? If so why? I am thinking in terms of orthosis

 

They are a continuum. In my opinion, a functional limitus has a very good chance of becoming a structural limitus. So, yes I probably would give them the same orthotic, because the stresses that cause them are the same. With the structural I might be more aggressive in recommending rocker tip shoes in addition to the orhtoic.

Eric

 

Functional HL (fnHL) has the excellent capacity for immediate functional improvement (ROM /QOM) with the appropriate functional orthosis.

Structural HL (StHL) has an intrinsic osseous (or injured) limitation for functional improvement due to anatomical or degenerative presentation.

See: http://lermagazine.com/article/functional-hallux-limitus-diagnosis-and-treatment

As such, the orthoses design parameters will be significantly different.

Attempting to force a StHL to increase ROM with orthoses design appropriate for FnHL will most likely cause significant pain and not be sustainable.

 

How, and why, would you make the orthotic differently for structural vs functional? Why would an orthotic for functional hallux limiitus cause pain in a structural hallux limitus?

Eric

 

Hi Paul

With respect I'd disagree, at least without qualifying the statement.

I achieve a lot of pain relief in cases where there is structural joint change with measures that are aimed at improving motion at the mtpj with a big overlap with FnHL.

The 1st mtpj ROM that is required for normal walking will vary between individuals. The amount of restriction present even in moderate OA changes may not limit the joint more than is required for normal walking for that individual.

However if there are components to the restriction which are 'functional', this will cause an increase in compressive forces within the joint and across the dorsal joint margins that will exacerbate any OA changes and pain.

Any measure that makes movement easier within the required range for walking, without taking it past the point of structural limitation will reduce this and therefore pain.

Obviously the closer the joint progresses to hallux rigidus the more likely the pain will remain or be aggravated by design changes to promote movement as you've stated.

I'm sure this can be summed up more eloquently than I've put it!
Ian

 

Yep increasing the quality of the movement available ie making it easier to move

 

I believe the forces that cause pain in functional hallux limitus are the same as the forces in strulctural hallux limitus. Joint compression is probably the biggest one. Joint compression comes from tension in the plantar fascia. Tension in the fascia is also what causes the "functional" limitation of motion and it also causes the joint compression. The reason that an orthotic increaes range of motion in functihonal hallux limitus is that it reduces the plantar flexion moment caused by tension in the fascia. The orthotic doesn't increase the range of motion available, it decreases the forces that limit the motion so that the motion can occur. The reduction in compression forces will decrease tissue stress within the 1st MPJ in both structural and functional hallux limitus. This how an orthosis made to reduce the forces can relieve pain in both structural and functional hallux limitus. We need to pay attention to the forces and not the motion.

Eric