AFO selection

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Hi

Can someone shine some light on where the anterior edge of a posterior leaf spring AFO should end...? Additionally under what criteria would you use this type of AFO over other types of AFO's -> solid, plantarflexion stop, hinged,dorsiflexion assist, ossur, etc.

Cheers

Cam

 

On the topic of AFO's

...I was recently informed by a third party insurer that podiatrists were not allowed to prescribe custom, pre-fabricated or even modified prefabricated AFO's.

Considering there are item codes for AFO released by the A.Pod.A (vic) I was a little confused??

 

Thats just not true. There is nothing stopping Podiatrists doing just that. It just a matter of that insurer not reimbursing for them.

 

I think the billing was the issue....but it hasnt stopped me from using them

 

I think the orthotists have a better grasp of this due to their training and experience. Having said that, some of us dabble in AFO's...and my gut feeling would be that the sole section needs to be longer (pending material thickness and shoe depth) if you want high mechanical advantage in what it is trying to do to sagittal plane movement/forces.

I use a carbon fibre 1mm sole sheet, and off course this can extend most of the way (distal to metheads). To minimize the stiff shank effect, the carbon fibre needs to be more flexible distally.

The other option is to combine an orthotic with the AFO impact above the STJ. Here I would imagine working toward your typical orthotic prescription fundamentals.

Ron
Physiotherapist (Masters) & Podiatrist





BTW Brevis, long time no see. Don't know if that name suits you though.

 

Camo,

This may help: http://www.richiebrace.com/treatment.htm

Ian

 

Cam a traditional posterior leaf spring uses a full length footplate. Unlike gauntlet AFO's they do not restrict the motion of the subtalar joint or limit dorsiflexion, in fact it enhances it, especially the hinged variety. They are more often utilized for functional weakness and due to neurological defect. It is also more wise to use such devices in bilateral applications as locking both subtalar joints in a gauntlet may provide less than satisfactory ambulation and provoke falls.

On the other hand gauntlet and Richie type braces are more specific for subtalar joint dysfunction such as PTTD, although there is quite a lot of overlap in the devices. The gauntlet's tend to immobilize the subtalar joint and in my experience often require shoe mods such as a rocker sole to enhance ambulation.

The leaf spring is also less costly. Often another factor in choice. I find the old school orthopedists favor these devices. Look around there are some really good new materials being used for this variety of AFO that are strong, lightweight and more durable than poly.

 

An instructer I had at BCIT once that told me something at the time that sort of summed it up .... of AFO's:.....(My silly question was of use and the goal of what to use and when but I needed to ask.)

She said:

"THINK" "What is the pathology?. "Think about the active (still functioning muscles/fibres with appopriate reflex) and inactive (those without). Think about whether or not there is tone. How much? When? Think about sensory deficits. Think about gait pattern (if there is one to speak of) and what what forces you need to apply and where. What is the goal of what you are doing? Is it pallitave? rehabilitative? limited use? full time with work?
Are there balance issues?" Are there social limitations?

So she then just says:

"Learn the materials, thier limits, and then play with them. Once you know what forces you want to apply and where then use the materials needed and you can begin to play a lot more."

At least that's what she said.

And I think a lot of what she said was right.

The reality you might seek however, is really in discussing what materials you in your lab are comfortable working with for initial fabrication.
And what processes you use to fabricate those materials..(ie plaster mold rectification or digital?)

It is a simple thing to make an afo to be sure. Depends on what you want and how long you want it to last. Sometimes function takes precedence over longevity. Prefab afo's are a good example. But they are useful as a diagnostic tool on initial visit. When you ask yourself if fit matters just put on an off the shelf one and wear it for two weeks.

Tailoring to the goal of the patient is critical if long term use is to even have a hope. Working WITH the patient and the family will mean they use it beyond two years..repetetive cycles will dictate the life of what you make. Fitting afo's you will see those who walk 200, 1200 or 7000 steps per day and they and everyone in between will demand different things. And thier families, doctors and therapists.

I have learned a lot over the years by listening.

 

Cam

Can you explain what you mean by the anterior edge? Do you mean how far around the circumference of the posterior shank/calf should it extend. If so then the lab you use to fabricate the device will set that parameter, if you use an of the self product them that parameter is already set, you do not need top worry about it.

Or do you mean where should the anterior or distal edge of the plantar foot plate end relative to the foot.

The answer then is, what are you trying to achieve with the AFO. Orthotics, all mechanical orthotics, are levers, a system of levers or one lever. How you design the the device depends on what function you wish to achieve. Function = Transformation = (Input - intervention/force - change - output).

A leaf spring AFO usually is intended to hold the foot in some fixed position of dorsiflexion relative to maximum plantarflexion. It does not give much stiffness against moments tending to cause frontal plane rotation of the STJ. It does not allow a range of plantarflexion below the fixed position except when a force is applied that overcomes the stiffness of the device and when the shoe is in place on the foot it does not allow a dorsiflexion range for the same reason. So varying the stiffness defines how much plantarflexion and dorsiflexion can be allowed relative to the force applied and this would be defined by the strength of the plantarflexor and /or dorsiflexor groups or if either of these kinematic parameters was required for optimal gait progression for that person of interest.

You may decide you need a dorsiflexion RoM that does not require much applied force in which case you'll need a hinged device, you might need a device that activelt dorsiflexes the ankle and so you need a dorsiflexion assiss device (self explanatory really eh! ) You might want a device that helps extend the knee (GRAFO) in which case a rear leaf spring AFO will be counter productive since it might flex the knee some time. And so on and so forth almost ad infinitum.

As in all biomechanical interventions, you need to understand the Bio bit (anatomy and physiology) and the mechanical bit (mechanics = levers moments forces etc) and how to apply on to the other. Then using logical reasoning you can confidently come to a useful conclusion about how and why to design and use an orthosis of any kind what so ever and you will not require a neatly boxed hit and miss, dubious, vascillating, untrustworthy paradigm guidance education system to get you to that point.

Dave

 

:good:

I was going to add my thoughts - then I read the above.

It says it all

Robin (orthotist)

 

Cheers but David and Todd's are excellent too - it's all so simple and there's so much to know just to find out what you don't know eh Camo? As Todd points out, Its all those humany idiosyncratic bits that get in the way of the technology and mechanics that make each person unique.

Dave

 

Camo,

Just as an additional, can you tell us the problem you are trying to treat or are you just after general information

From an orthoses selection point of view, different manufacturing companies have different ideas about different types of AFOs but call them the same.

Product knowledge is key here and I know a reasonable amount about UK products available.

If you give me an idea about what you want to acheive, perhaps I can point you in the right direction

Regards

Robin

 

Great point made there.

The more I learn the more questions I have.

 

Thanks for asking that Robin.
I'm curious as well.

 

Thanks for the responses - the post was made in April 2009 and I am struggling to remember why I intially posted. I have tinkered alot with AFO' since then and have a better understanding of design, materials,etc and desired outcomes.

Cheers once again.

 

Then also consider this:
http://www.walkaide.com/en-US/Pages/default.aspx

when deciding what would be best in a given situation.
I have provided 24 of these so far. As opposed to an afo the patients that I have provided it to have asked for it by name. They all prefer it over any afo they had previously been given.