Medial arch blister with new orthoses

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I have a young female patient who has developed medial arch blisters with wearing her new orthoses. There is no irritation of the plantar fascia. I have only seen it one or two times in 16 years. She has the typical very flat, medially deviated STJ axis. From my view I have just not achieved sufficient control for her foot & she pronates through the device still leading to medial arch irritation (the prescription was for 4 degree inverted pour, minimal arch fill, 4mm medial skive, 16mm heel cup, cushioned covers. I could repress the device with greater control but what other adjustments might be helpful? Adding a PPT type arch cookie would soften the edge but I think I need to increase the control. Are there better ways of doing this? In the past I would add increased medial rearfoot & forefoot posting to shift weight more laterally. Any other suggestions?

 

Check that device is not slipping in footwear; particularly if it is not full length cover.


Other option is to check whether the high-point of the MLA in the device corresponds with the location of the foot's MLA hinge point (aka transverse axis in the midfoot about which, midfoot dorsi-flex and plantarflex occur).

Otherwise remove post.



Get comfort and tolerance right first. Then worry about effect on signs and symptoms later.



Ron
Physiotherapist (Masters) & Podiatrist

 

Hi mark.

Have you analysed static and dynamic function with the orthotics in/on? Is the patient still pronating at the stj? If so, I would try adding extra skiving by beveling in 6.4mm poron from the inferior medial cup extending to the talonavicular area distally. This will hopefully increase the stj supination moment and reduce the corrsponding shearing and compression forces acting on the medial arch as the shell presses in during late midstance phase.

Also as ron said if the pinnacle of the arch profile is greater that the MLA in neutral static stance, consider reducing the peak profile of the arch to aid comfort/conformity.

I find adding a 3mm neolon top cover helps too.

Scott

 

Check your planal dominance.

 

Mark have you given any thought to the bias of her shoes? I'm sometimes horrified to see a well devised pair of orthoses put into a shoe with too much pronation control, lacking an adequate shank or characteristics that do not support the prescription of the devices and it is a factor in how the orthoses will perform. What type of shoes is she wearing the orthoses in?

 

Thanks to Atlas, FootDoctor, Robert & David. The control thorugh the STJ I think is inadequate & that is where I'll initially adjust. I'm seeing her next week so I will check the other areas suggested. The shoe may be an issue as well as it is an anti-pronation shoe with a failry narrow base so I will be adjusting the overall shape of the ortho - but in saying that, she would possibly be better of getting new shoes to fit the ortho than the other way round.

 

Mark:

I see this type of problem probably once or twice a month in my practice (currently about 80-100 pairs of orthoses a month). Here is the best solution:

1. Put the orthosis on the ground and then have the patient stand on top of the orthosis, marking where along the medial edge of the medial longitudinal arch (MLA) of the orthosis that the blister/irritation occurred.

2. Peel back the topcover and lower the medial edge and MLA of orthosis in the area of the blister.

3. Have the patient walk in the adjusted orthosis to see if this reduces the "hot spot" from the orthosis. If not then proceed to any of the following solutions that may also help:

A. Grind the medial rearfoot post and medial anterior edge of the orthosis to evert the orthosis slightly and lower the MLA height of the orthosis.

B. Add a heel lift under the orthosis or put patient into shoe with higher heel-height differential.

C. Add extra medial heel skive by adding medial heel cup padding under the topcover or by repressing orthosis with extra medial heel skive.

Hope this helps.

 

Thanks Kevin for your reponse.

 

Kevin, how do you lower the area under the blister? Do you grind out a semi-circular area or maybe spot heat with a heat gun & depress the area?

 

Either. I usually heat gun it. Also, try using a top-cover with lower friction.

 

Is the blister at the medial edge of the device where the foot hangs over the edge? A wider device can help this. Yes, it is harder to fit into shoes, but if the foot is that wide then the shoe will be deformed by the foot as well as the orthosis. I agree with the other advice.

A comment about increasing control. If you are getting a blister at a point where the orthotic applies force to the foot to "increase control" (increase supination moment from ground reaction force) then the problem is either too much "control" or too much control in the wrong location. You should be aware of what you mean by control and how the orthotic achieves this. Increasing force medial to the STJ axis will increase supination moment. Sometimes increased force in the medial arch will increase supination moment without causing harm, but there is a point where you can cause pain/ bllisters in the arch.

Other times, you can get increased supination moment from the muscles when the foot stands on a high arched orthotic. This patient has shown you, with blisters, that she is not going to use her muscles to increase supination. There is more than one way to supinate a subtalar joint. Be aware of how your devcie achieving control.

Regards,

Eric Fuller

 

Mark:

I rarely spot heat orthoses due to the fact that spot heating may deform other parts of the orthosis where I don't want the plate to be deformed. I will use a grinder to flatten out the curve on the area of the orthosis that corresponds to blister formation or plantar irritation.

This is one of the beauties of orthosis shell materials such as polypropylene. Polypropylene orthoses are thick enough so that they can generally be ground through enough to resolve most area of plantar foot orthosis irritation. Laminate materials, such as graphite shells, are not easily grindable and are too thin to allow this sort of modification. This orthosis modification of grinding the high spot on an orthosis generally takes me less than a minute to do on a grinder.

 

Hi Kevin

I have a similar pt, male body builder, who continually presents with blister formation on the medial aspect of both arches, distally. And only when he is on the treadmill. Walking and daily wear does not cause blister formation.
I initially thought that on dynamic gait analysis, enough STJ control was not being achieved and modified the orthotics by adding a full medial wedge post plus a poron 'valgus' pad in between the polyprop plate and cover material. To little avail. Again, blister formation.
I have thought to add a medial flange, extending the medial side but will first try and grind away the area corresponding to the blister at the MLA and decrease the medial rearfoot posts.
Do you think adding a fore-foot medial wedge extending from the fore-foot post will help control pronation?

regards

Brandon Maggen

 

Brandon:

The first thing that comes to mind about your patient's treadmill-related blisters is that the patient probably has the belt of the treadmill inclined causing a change in pressure distribution of the orthosis reaction force more anteriorly on the plate. Ask the patient to walk with the belt of the treadmill level, instead of inclined, or add a heel lift to the orthosis for when he is walking on the treadmill.

When confronted by seemingly puzzling problems like the one you present above, I always first look for the simplest and most common-sense solution to the problem.

 

Hi Kevin

In the usual manner in problem-solving, that which is most obvious is often that which is thought last.
I will ask him to level out the treadmill and see if that makes a difference.

Thank you for your advice

Brandon Maggen

 

In addition to David's statements, there are often correlations with medial column blistering and shoes that possess too much midfoot twist characteristics. Classic examples are those placing rigid devices into department store core models like the New Balance 608 and any Easy Spirit.

 

I can think of a yet simpler explanation!

You say he has no problem in walking and daily wear. Is the treadmill the only time he runs?

I generally use different orthotics for sport, I tend to have less height in the arch and use a forefoot varus extention (not a forefoot varus wedge) much as you suggest.

Regards
Robert