This is part 11 of a series that should be read in order.
Key Points:
- Review of Supination Orthoses
- Emphasis on avoiding MPP
- Emphasis that Heel Verticality is not always the Orthotic Goal to achieve
- Supinators need both static and dynamic evaluations
In the last post, I summarized the supination orthoses in terms of correction as:
BS 1 degree change (mild correction of supination tendencies)
In cases where you can balance out high degrees of an everted forefoot deformity, this change could be up to 4 degrees.
S1 2-3 degree change (moderate correction of supination tendencies)
S2 3-4 degree change (moderate+ correction of supination tendencies)
S3 4-6 degree change (severe correction of supination tendencies)
BS is my typical cast preparation with a lower than normal medial arch (therefore the medial arch fill will be more than standard 3 mm) and a Denton Modification (aka lateral frame fill). Since I use Root Neutral Suspension Casts, my B (Balanced) orthoses are B1 with balancing of the forefoot deformities. I have to assume one important point. That this forefoot balancing is not going to influence my control of supination. However, you know that balancing various degrees of Everted Forefoot Deformities is going to have various degrees of supination correction. At some point, the industry will be able to say what the ratio of correction is for forefoot everted deformities (say 5 degrees vs. 10 degrees vs 15 degrees). If you assume 1 degree of supination correction per 5 degrees of forefoot valgus support, then BS can give up to 4 degrees of supination support with high degrees of forefoot valgus/plantarflexed first rays.
S1 is your standard device (B) with all (at least 4) the anti-supination bells and whistles. These include: higher lateral heel cup (typically 18 mm or more), lateral flange, zero motion rearfoot post, Denton modification, narrower orthosis than normal, and lower medial arch than normal.
S2 is S1 plus ⅛ inch valgus wedge to sulcus, Feehery cuboid support, ⅛ inch support sub 4 and 5 metatarsal heads, and setting the cast correction not at vertical, but at 2 degrees everted.
S3 is S2 with a 3 mm lateral heel Kirby skive and a 3/16 inch total valgus wedge to the sulcus.
Now, let us look at another example of a patient needing Supination orthoses.
Example 2
RCSP 5 degrees Inverted
NCSP 8 degrees Inverted
MPP 2 degrees Inverted
FF/RF 7 degrees Valgus
Your biomechanical assessment is High Degree of Rearfoot Varus with only partial compensation (as Rearfoot Varus attempts to get the heel to vertical in full compensation)
For this patient, 3 orthoses were made for teaching purposes:
First Device was B1 (Classic Root) where the Forefoot Valgus was balanced to heel 3 inverted (attempting to avoid MPP of 2 degrees inverted)
OCSP for B1 Balancing was 3 degrees Inverted
However, Dynamic Supination Still Seen in Gait
Next device was an S3
OCSP for S3 was Vertical Heel (therefore damaging as the pronatory force created subluxed the STJ 2 degrees past MPP
And the final device was S1
OCSP for S1 3 degrees Inverted (a perfect compromise)
No dynamic supination seen in Gait or felt by patient
S1 device makes sense since we are trying to change the orthosis from 5 inverted to 3 inverted (supinated from MPP) and S1 typically gives you this 2 degree change.
This is such a good case. I will also use it when discussing the role of measuring subtalar joint inversion and eversion. This is our next very important measurement which has a role in so many situations. In this patient, there was 18 degrees of total range with 12 inversion and 6 eversion. You can estimate the eversion range by looking at the NCSP and the MPP difference. So, we have a rigid foot (less than 30 degrees of subtalar ROM), quite inverted, and unable to get the heel to sit vertically (at least it should not). The patient had 4 issues adding to their tendency to supinate: forefoot valgus, tibial varum (with some genu varum), weak peroneals, and an intoed gait. The initial B1 produced an eversion force to balance the 7 degrees of forefoot valgus (in actuality only 4 degrees were balanced as I wanted to hold the heel 3 degrees inverted). The heel only changed 2 degrees in the valgus direction from RCSP 5 Inverted to OCSP 3 Inverted. This is an acceptable position since it was 1 degree inverted from MPP, but dynamically the patient still supinated at heel strike. I then threw almost every anti-supination modality I knew at it including: 2 degree everted intrinsic support (not the 3 degrees inverted in B1), extrinsic ⅛ inch valgus wedge to the sulcus, and a lateral Kirby skive. This terribly subluxed the subtalar joint (never good) with the new OCSP at heel verticality. Using all the measurements to my advantage, it was pathologic to evert the more than the 2 degree Inverted MPP.
The difference in anti-supination force is huge going from B1 and some forefoot valgus support to S3. When I changed back to an S1 device (standard device with all the bells and whistles for supination support), but no eversion canting, the OCSP remained at 3 Inverted, but with no dynamic supination seen or felt. My goal was accomplished.
Better look at the Valgus Wedge to sulcus (A). Also flat 0 motion Rearfoot Post helps supination tendencies, and narrowing both the post by ¼ width medially and the medial aspect of the plaster from normal (or a first ray cut out)
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
