This is the part 6 of a series that should be read in order.
Key Points:
- Discusses thoughts on adding more varus to an Original Orthosis
- Importance of evaluating OCSP in orthotic therapy
- Why FF Varus support helps pronation control better than FF Valgus support
- What are P2 modifications and what do you expect to gain from them?
- Review of highly corrective P3 to P6 orthoses
Let us look at 2 different orthotic approaches all centered around originally achieving subtalar neutral.
RCSP 4 degrees everted
NCSP 3 degrees inverted
OCSP 1 degree inverted B1 device
FF Varus 7 degrees inverted
This was simply originally corrected with B1 orthoses with 5 degrees of FF Varus balancing (my personal limit with the original Root Balancing technique of FF Varus for fear of blocking the first metatarsal plantar flexion). When the patient both complained of arch pain, and still looked like the overall pronation was not completely controlled, then a 2 degree varus extrinsic rearfoot and forefoot post was added to the original device. New OCSP was 3 degree Inverted or subtalar joint neutral. Both the original orthotic device, and the modified more varus canted device, are stable orthoses. It has to be something that tips you off that you need more correction. In this case, the arch discomfort was resolved with better control of the orthotic device in actually raising the orthosis in the arch with more canting. If I am dealing with chronic pain, I prefer to attempt subtalar neutral (accomplished at least in my stance measurements).
RCSP 5 degrees everted
NCSP 2 degrees inverted
OCSP 6 degrees everted (B1 device)
FF Valgus 8 degrees everted
Here balancing of the FF Valgus deformity actually placed a pronatory torque on the foot, and the OCSP became more everted. Remember balancing the forefoot to rearfoot can indirectly place the heel more inverted or everted from RCSP, but not guaranteed where the heel will end up due to other factors like material flexibility, width, first ray cuts, metatarsal pads, cushioning in various places, etc. That is why the OCSP is so crucial in our modern view of what our orthoses are doing. This patient did feel more stable with the B1 device, but the posterior tibial symptoms (which I believed was pronatory motion and position caused) did not improve. The patient is now functioning 8 everted away from NCSP with this first device, and this was confirmed somewhat with no change noted in the pronatory gait. A second device was then prescribed using P2 modifications.The FF/RF correction was maintained, but a 4 mm medial Kirby skive with a 3 degree extrinsic rearfoot and forefoot varus posting. The new OCSP was now heel vertical, now only 2 degrees from neutral. This 4-5 degree correction is a typical response from a P2 device. Here symptoms could improve in the posterior tibial tendon (as you get near 2 degrees of neutral you are doing really well).
So now you eagerly ask, what are P3 to P6 devices, and how much correction is typically seen with them? P3 is a 25 degree inverted device with high heel cups (21 mm) and a wide frame. This will give you 5-6 degrees of correction. You can always decrease the inversion and add a medial heel skive of 2-3 mm for similar corrections. Therefore, I have found a 25 degree Inverted to be equivalent to a 15 degree Inverted with 2-3 mm of medial skive. This principle works for when higher amounts of inversion are needed. You can also combine the 3 techniques mentioned previously: 3 mm Kirby, 3 degrees varus rearfoot and forefoot canting, and 2 degree inverted pour, if you desire to stay away from the inverted technique.
P4 is a 35 degree Inverted device or 25 degree with 2-3 mm medial Kirby skive. Here you are attempting 7-8 overall degrees of correction, which is also my personal highest starting point in orthotic corrections that I will give to a patient. After making thousands of these P4 devices, not only do they accomplish what I am proposing, but they are very comfortable when the patient needs this correction. I have talked to many skilled clinicians that can accomplish the 7-8 degrees of correction with 15 degrees of Inversion, 3 mm medial Kirby skive, and 2 degrees of varus extrinsic forefoot and rearfoot posting.
P5 is a 35 degree inverted device with a 4 mm medial Kirby skive. This is a powerful device providing 10 degrees of pronatory change. P6 is a 45 degree inverted device with 4 mm medial Kirby. This will give 12-13 degrees of pronatory change. More correction if needed can be accomplished by adding an additional 2-3 degrees of straight canting with extrinsic rearfoot and forefoot varus wedging. If you add varus wedging also to the shoes they wear, or go with boots at times, you can get corrections over 20 degrees of varus canting in severe adult acquired flatfeet. P6 is my personal highest recommended Inverted Orthoses and this will be discussed in several future posts..
If you and your lab have never used the Inverted technique, consider the options above with less inversion than by that technique, but place Kirby skives and extrinsic wedges. Just remember to measure the change you made and see if it was what you wanted, and you will continue to improve in your designing an orthosis that should get you there. Then, measure again when these orthoses are dispensed.
In summary, these P orthoses tend to give the following heel corrections, and are very predictable.
P1 3-4 degrees of heel inversion
P2 4-5 degrees of heel inversion
P3 5-6 degrees of heel inversion
P4 7-8 degrees of heel inversion
P5 9-10 degrees of heel inversion
P6 12-13 degrees of heel inversion
Review of all the Orthotic Types Being Presented
Corrective Orthotic Devices
↓
- Balancing (B): (B1 and B2)
- Pronators (P): BP, P1, P2, P3, P4, P5, and P6
- Supinators (S): BS, S1, S2, S3
- M/L Instability (M): BML, ML1, ML2, ML3, ML4, ML5, and ML6
- Shock Absorption (C): BC, C1/C2, C3/C4/C5, C6, and C7
- Sagittal Plane (H): BH, H1, H2, and H3
