The Introduction here has been consistent with all the discussions on orthotic types: With all patients, as I hear their complaints, and watch them walk and/or run, I am immediately designing the perfect orthosis in my mind. I categorize these patients by what correction I will need to achieve stability. These are A) need to achieve vertical (typically your Gold Standard), B) need to achieve less of an everted heel (discussed in the post entitled "When to Varus?"), C) need to achieve markedly less everted heel, D) need to achieve an inverted heel position (discussed in 3 previous posts), E) need to achieve less of an inverted heel position (discussed in post "When to we Valgus?"), and F) need to achieve markedly less inverted heel position (discussed in post "When do we Really Valgus?). Of course, the demands of the right foot may be totally different from the left foot. Yet, beginning to master these 6 basic orthotic devices will dramatically improve your orthotic practice. This is the final one of the 6 Types that I will discuss.
To Summarize:
Type A: Gold Standard (for most getting the heel vertical by setting the heel vertical)
Type B: Designed to make an everted heel less everted
Type C: Designed to make an everted heel markedly less everted
Type D: Designed when the heel should be inverted
Type E: Designed to make an inverted heel less inverted
Type F: Designed to make an inverted heel markedly less inverted
So, where do we begin our discussion of type C? We are needing feet that stand very pronated and with everted heels.
I think most of us would agree that this child has very pronated feet with everted heels. You can quantify the degree of eversion by measuring RCSP, and you can measure one aspect of your correction by measuring this everted position with the patient standing on their custom orthotic devices. I will attempt to place this flat footed child within 2 degrees of verticality which will alleviate so much of their symptoms and alignment issues. You can do a quick test after measuring the RCSP, by having the patient supinate their feet by rolling laterally, and then measuring again. Someone with normal static measurements who is functioning 10 degrees everted in maximum subtalar joint pronation, may be able to invert the heel close to 20 degrees.
We have so many ways of correcting towards more varus positioning. For example, if I measured one of these heels at 10 degrees everted in RCSP and NCSP had them Vertical to Inverted some, my goal would be to get them closer to verticality. We know we are dealing with pronatory forces, or more correctly moments, in a patient without a structural reason to remain everted (like someone with a NCSP 3 everted). So, how do we take a 10 degree everted heel and improve it. There are the 4 classic ways and I have used 3 or 4 of these techaniques in the same Rx. Remember to measure RCSP standing and then on the device you made. The 4 varus corrections are:
- Setting the heel vertical (with the image technique of choice) and then applying a 1/8 to 1/4 inch varus forefoot and rearfoot posting.
- Setting the heel 3-7 degrees inverted in the original Rx
- Using 4-6 mm Medial Kirby Skives
- Using Inverted Technique where 5 degrees correction equals 1 degree heel correction
One of my general rules is to never correct more than 7 degrees as your first orthotic correction. In the average size foot, each degree is 1/16 inch change. So changing the foot 7 degrees is 7/16 inch change (yes, almost half an inch).
Let us say you are going to be bold and attempt to change this patient's flat pronated everted foot 7 degrees (from 10 everted to 3 everted). 2-3 degrees everted is considered by a lot of the world as normal. How do we do this practically? Of course, these would be my top 5 choices, although I will list the Inverted Technique last.
- Have the lab set the heel 4 inverted, and add a 4 mm medial Kirby Skive.
- Have the lab set the heel 3 inverted, and add 1/4 inch varus extrinsic posting both in the heel and the forefoot.
- Have the lab use 20 degree Inverted Technique with 4 mm medial Kirby Skive
- Have the lab use 15 degree Inverted Technique with 2 mm medial Kirby Skive and 1/8 inch varus extrinsic rear foot and fore foot posting
- Have the lab use 35 degree Inverted Technique
So much of this work is personal preference. These all should give you 7 degrees or close. You have to measure RCSP again and then stand them on their orthotic and remeasure. And, should very talk about shoes. The old saying is that "orthotics are only as good as the shoes they are in". This can be so very true. If you want to get 3 degrees out of the shoe, have the patient use the Brooks Beast or Ariel. But, they need to stay with those shoes.