AFO hindfoot posting

AFO hindfoot posting

Don Freeman

8/31/1998

To O and P Community,
Here are the responses received from the following questions
regarding AFO hindfoot posting.

 1) Our department is interested in research articles on AFO
 hindfoot extrinsic posting for pediatric and adult patients.

 2)There is some controversy in our department on what is happening
 biomechanically at the ankle and knee with a
 medial,lateral, or full hindfoot post.

 I believe I recently saw a posting (a month or two ago) on this
 subject. If anyone has this information could you please
 send me a copy?
 Any information on this subject would be very helpful.
Don Freeman,CP
Shriners Hospital for Children, Portland, Oregon
==============================================
Don,

I certainly hope that you will share with us any information that you
receive on this subject. I have been using a plastic extrinsic hindfoot
post on virtually all of my pediatric AFOs over the past 11 years. I've
never seen any research on it. My reason for using it is based on my
own experience. Of course my reason for doing most of what I do is
based on experience, not true research. I find it frustrating when I
come up against a CO, PT, or DR who has a different reality than mine,
each based on their experiences. And none of us have scientific
evidence to back it up with. Many are very dogmatic about their
preference. I'm not convinced that I am right but I am also not
convinced that they are right. I know that I get good results if I
follow my own rules. If I try to do it their way, I have a stronger
likelihood of less than optimal results. But that may be just that I
don't follow their rules as well as they do.

Concerning hindfoot posting, answers to these questions may affect your
outcome.

1. Do you cast freeform or on a footboard and what slope?

2. What kind and shape of shoe does the patient wear?

3. Do you carve a Carlson Modification into the cast or similar
modification? And how much under what conditions?

4. Do you either flatten the bottom of the cast or carve a wedge(medial
or lateral) into the bottom of the cast?

5. Do you use rigid or flexible materials for the orthosis?

6. Do you believe that the hindfoot should be locked up in the frontal
plane? Or should a small amount of motion be allowed to give a more
natural pronation(not my words:)?

7. Does the patient have a flail foot, muscular/ligamentous tightness,
rigid foot, spasticity, ruptured tendons, I'm sure I'm missing some?

IMO, studies should address most if not all and more of these issues.
I'd like to see more studies in our field that will answer questions
like these rather than attempting to sell products or ideas.

Harold Anderson, CO

===========================================================
1) Our department is interested in “research articles” on
AFO hindfoot
>extrinsic posting for pediatric and adult patients.

As far as I know there isn't really anything. I could be wrong and most
prob are...;-)
>
>2)There is some controversy in our department on what is happening
>biomechanically at the ankle and knee with a
>medial,lateral, or full hindfoot post.

Extrinsic posting on an AFO is something which needs very serious
thought and I feel can only be done during manufacture and must be
considered before casting, so the orthotist can positon the hind
foot/forefoot in the correct postion to allow the posting to be added.
This may call for a 2 stage casting. Fist a slipper cast in sub-talor
neutral then cast in the normal leaving the slipper cast in situ. This
can be done extrinsically or intrinsically

Then when the posting is added it will bring the the base of the AFO
into 90 degrees alignment with the Tibia so a good stable base will be
achieved during intial contact. If you add posting as an after thought
during fine tuning, you don't have any effect over the sub-talor postion
or ankle, but you would certainly induce unwanted forces at the Knee jt.
In otherwords the ankle is locked into the positon that the orthotist
casted the patient in and therefore any posting will have a distal
effect on the next avaliable body segment (The knee joint)

I usually fit extrinsic firm EVA posting so I can fine tune it if
required. I also ternd to add more than I need so you can gradually
remove material till the correct tibila angle is achieved in the M/L
plane.

I hope that makes sense.

Chris Drake The Moods of The People are
                                   not Dictated by Government
<Email Address Redacted> (Richard Benson, 1996)

==========================================================
I'm not clear that I fuly understand your question. However if it is -what
effect does an extrinsic hindfoot post have on the ground reaction forces(GRF)
as they effect the leg? Then one can appreciate that any type of orthosis,
regardless of design, will change the GRF's as they cross each joint of the
lower extremity.

Therefore, a medial rearfoot post will create an externally generated varus
moment at the knee it's impact will allways be at the most proximal end of the
orthosis. No impact can be felt by joints encompassed by the orthoses, ie
subtalar jt. By moving the post the direction of force at that proximal end
will change.

I don't know of any articles however these texts may help Gait Analysis in
Cerebral Palsey- Gage and Gait Analysis-Perry. Also might check with Roy
Davis PHD at Newington Child. Hsp.

Hope this helps...Regards Tom DiBello CO


---------------------
Don Freeman,CP
Shriners Hospital for Children, Portland,Oregon
<Email Address Redacted>