How do you do lateral wedging for medial knee osteoarthritis

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Yesterday's question on lateral wedging for medial meniscus tear brought to the thread with all the discussion and research on lateral wedging for medial knee OA. I have also heard Paynie talk about this at a conference.

I am just curious, of those who use lateral wedging for medial knee OA, how do you actually do it?

 

Ive found lateral wedging quite effective for medial knee OA, as long as this is the patients only complaint.

Extended wedge's give the best result --extending to the base of the met heads. I usually use medium density EVA at about 10mm at the lateral aspect and grind to zero to the medial side.

Ive also used thick felt, and fromthotic additions(2x 5 degree extended wedges sandwiched together)

A basic rearfoot wedge (not extended), ive found dont work.

 

Which is what we showed here:
Rana S. Hinman, Kelly Ann Bowles, Craig Payne, Kim L. Bennell: Effect of length on laterally-wedged insoles in knee osteoarthritis. Arthritis Care & Research Volume 59 Issue 1, Pages 144 - 147;

ie size does matter !!

 

Craig:

It would be great to get a copy of this paper since I don't subscribe to this journal.:drinks

 

Hi
I have been using laterally wedged orthosis for medial compartment syndrome for a long time. In a full-length orthotic the lateral wedge extends from the hind foot to the apex of the orthoses. In a 3/4 orthotic, once again it is from the hind foot to the anterior lip of the 3/4 device. In severe cases (grade 3 or 4 ) I use a 10mm EVA 65 shore hardness, and in a case that is not as severe I use a 5mm EVA 65 shore density. Patient compliance is of utmost importance! The patient has to "wear in" the new orthotics. Good luck. Vernon Lever

 

What the wedge has to do to be effective is reduce the external adduction moment at the knee. To do that, the subtalar joint probably has to be at end range of pronation and the wedge has to have a sufficient lever arm to the subtalar joint axis (I think the range of eversion available and the position of the STJ axis will probably go some way to explaining the subject specific responses to lateral wedging).

The study quoted above that showed a greater systematic response to full length wedges was probably because of the greater lever arm to the subtalar joint axis that a full length wedge has. Having said that, those with just a heel wedge, may work well if the axis is in a more medial position (they will still have a suffficent lever arm) -- this may go some way to explain the subject specific responses and the variable results with different length wedges reported in the literature.

I have also been asked the question several times, if it is a lever arm issue to the STJ axis, then why does the wedge need to be under the rearfoot and not just under the forefoot? I do not know, but I can't see why not - I have just not done it.

How to practically apply a lateral wedge? There is probably a zillion ways:
- use a full length EVA wedge strip (a couple of suppliers have them)
- make your own lateral wedge out of EVA -- just need to do some grinding to smooth one edge
- glue an EVA strip on plantar lateral side of a prefab orthotic or shoe insole and grind the medial edge of the strip smooth
- use a lateral Kirby skive on a custom made device (but this is not full length, but one small study did show it helped)
- 2 running shoe companies are investigating laterally wedged shoes for this population.
- etc etc

 

Becareful and make sure the knee isn't varus or valgus. At my lab i've see most mild cases of OA in medial compartment sucessful with postings but anything more severe would sometimes require a OA custom knee brace and extremely severe cases go into KAFO.

 

I will very often take the patient's insole from their shoe and run a 5mm wedge from heel to sulcus. I either glue it down or use electric tape as duct tape is messy. Obviously, the shoe must be in good repair and if it is a runner, it must not have a medial motional control post.

This will be a good indicator as to how they will do. I have had many patients over the years say this works great as it is, and they did not wish to have anything more than this modified insole.

Best regards

Freeman Churchill, Certified Pedorthist (Canada)

 

PS I did not mention I use EVA with density used based on patient's weight, heavier = firmer

 

I'd imagine that wedge is needed under the heel because the damage could occur at heel contact. Reducing frontal plane moments at the knee in gait as well as in static stance.

Cheers,

Eric

 

I'd have to disagree with the medial motion control post in medial knee degeneration. Shifting the center of pressure more medial will increase the external knee adduction moment and to some extent negate the effect of the lateral wedge.

Regards,

Eric