Hyperextended Interphalangeal Joint

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Hi all,

I have an 11 year old patient who has a very hyperextended interphalangeal joint (IPJ) of both halluces. I have had him in arch supports for about three years yet the deformity is getting worse. So I am now making him orthoses.

As far as I am concerned, a hyperextended IPJ is a bony change due to a lack of windlass function - functional hallux limitus (FHL).

Examination reveals:
- compliant medial column with significant medial arch lowering
- FPI +9 bilaterally, tight gastrocs (lunge 24 degrees bilaterally)
- Supination Resistance high force (bilateral 3/4)
- Medially deviated STJ axis
- The hallux is quite short and in particular the proximal phalanx. The relative 1st metatarsal length is normal.

Functional hallux limitus is specifically supported with:
- Jack's test (bilateral delayed and high force: 3/4)
- Modified FHL test shows windlass initiated with dorsally-directed pressure at the base or proximal shalft of the first metatasrsal.

However, pressure mat results suggest there is no FHL. This interpretation is based on Van Gheluwe et al 2006 paper which basically calculates a ratio of 1st met head pressure to hallux pressure.

This has sent me into a spin, I can understand why there is a bony deformity suggestive of abnormal windlass function yet the pressure mat result refutes this.

At this point, I am making a MOSI type of orthosis - I'm relatively new to these but I think a low arch contour with significant supination moment at the rearfoot is required, with a bit of a heel lift and forefoot valgus extension and padding under the proximal phalanx to dorsiflex the 1st MPJ ... see, I still want to believe there's a FHL.

Can anyone shed some light on this for me?

Rebecca

 

Hi Rebecca I´m wondering if the Hyperexteded - or the ski jump effect as I describe to patient, won´t the requirement of moment in the 1st be much less as the foot will roll over the toe not flex the 1st MTP joint. kind of a mini rocker sole for the Hallux.

I would also assume that the mini toe rocker would also mean a change in 1st met head pressure as well.

Does that make Sense. Just an idea

 

I guess if you want to see if I'm talking out my hat again ( I would be interested as well) You could get a foot relatively mobile IPJ 1st, tape the 1st MTPJ in an a similar to your patient. Get them to walk on the f-scan of yours and then take the tape off to see the changes in 1st Met head pressure. I guess you would have to limit 1st MTP joint motion as well - might be a bit more tricky than I thought.

Id do it but no in-shoe pressure testing at my place.

 

You have a lot of data that is screaming Functional hallux limitus (FnHL) and one piece of data that is saying that you don't have FnHL. How else would you get hperextension of the IPJ (I call it ski tip toe) if not for walking with limited motion of MPJ? No history of injury?

So, no you are left with having to make a choice of what data to accept. But, before you do that, you could look at shoe impressions to see if you have that deep hole under the hallux. If you saw that you could discard the pressure data as not representative of how he walks most of the time. What's a MOSI. I would still design my orthotic to reduce tension in the windlass (Supinate STJ, shift load away from 1st ray.)

Eric

 

Hi Mike,

I'm not entirely sure what you're saying, but just because the hyperextension of the IPJ makes it easy to roll off the hallux, doesn't mean its a good thing. The more the IPJ is required to hyperextend, the worse the deformity gets. Better to fix things at the 1st MPJ wouldn't you say so it doesn't get worse (or slow it down at least).

Yep OK.

That's what the MOSI does, with the other bits and pieces I described.
http://www.podiatry-arena.com/podiatry-forum/showthread.php?t=10117

Rebecca

 

I agree try and slow it down. I was looking at a reason for the f-scan not showing a FnHL when clearly your dealing with one. Does that make more sense.

 

Oh I'm with you now. Thanks Mike.

Rebecca