This is part 9 of a series that should be read in order.
Key Points:
- We need Pronation and Supination of the Subtalar Joint, but at the right time
- Contact Phase Supination can be very hard to see, but the lack of pronation may be your clue
- The importance role of MPP (Maximally Pronated Position) when lateral wedging is needed
In gait, our feet both pronate and supinate. We need contact phase pronation to become a mobile adapter to the ground by adding laxity to the joints. We also need the foot to pronate across the subtalar joint to smoothly continue the internal rotation of the entire lower extremity. With subtalar joint closed kinetic change motion comes talar adduction and internal rotation along with calcaneal eversion (among other things). It is during midstance that the foot needs to begin supinating, because with that supination comes talar external rotation along with lower limb external rotation. In this way, we walk smoothly with this pronation and supination inherently linked at the right time to the synchronicity of the lower extremity, which is linked to the synchronicity of the upper extremity.
Therefore, contact phase pronation is a must, and contact phase supination is a must-be-fixed. Now! Shoes alone can bring on contact phase supination in someone with normal biomechanics, or on the edge for lateral instability. Some orthotic devices alone can bring on contact phase supination. Shoes and orthotic combinations can also produce contact phase supination. Where abnormal pronation produces medial instability, contact phase supination produces lateral instability. It takes a trained eye to see it, at least someone who is looking for it. Runner’s shoe store personnel can usually not see it, since they are only trained to see pronation. However, many do see the difference between pronation patients and those who have no pronation. This is why supination tendencies have been called “underpronation” which dictates not placing the client in shoes for pronators. A start! This patient does not pronate, which they can see, the arch is not collapsing, the fibular area is moving lateral, and there can be more shock waves up the calves. Yet, no actual heel inversion at heel strike is seen in general unless it is quite severe and your eye gets accustomed to looking for it. In B1 Orthoses (Root Balanced with Forefoot Valgus), the eversion correction of these Everted Forefoot Deformities can definitely reduce, or completely eliminate supination issues. If a B1 orthosis has Forefoot Varus correction (Inverted Forefoot Deformities), the supination can be made worse. In B2 orthoses (shape based), you can not balance deformities to help you, but there are other modifications that you can use. Therefore, BS stands for your Balanced Orthosis with some supination controlling modifications. BS is my typical cast preparation with a lower than normal medial arch and a Denton Modification (aka lateral frame fill).
Now, there are 3 versions (that I know of) of more lateral support. But, before I discuss them, let’s discuss briefly why you must know where MPP is and avoid it. You can not jam up the subtalar joint laterally by using any anti-supination modality. I remember my early days in an orthopedic clinic. I was given all the patients (pre- and post-surgery) with medial knee joint line pain with a Rx for a lateral valgus heel wedging. Pretty easy, right? Well, no, a lateral wedge that robbed the subtalar joint of any remaining eversion by jamming up the subtalar joint in its maximally pronated position, would do a variety of bad things mechanically thus producing various pain syndromes. Yet, the same lateral wedge that robbed the subtalar joint of any remaining eversion by jamming up the subtalar joint, would force the tibia to evert and open up the medial knee joint line. Knee wins maybe, rest of body not so much. The patient’s symptoms were much better almost 90% of the time at the knee at the cost of hurting other structures. A valgus wedge opened up the medial knee joint, and made the knee more unstable due to the pronated foot the wedge produced. I experimented some, over the years, and found that about 50% of these patients also improved with varus wedges with pronators that made their knee more stable. The moral is: if your treatment involves the subtalar joint, know MPP, and try to avoid it. Since my general rule for all patients is to make them more stable, avoiding MPP is a must.
These 3 orthoses for supination control are S1, S2, and S3 in our classification. Next week I will begin the discussion of these 3 devices with examples.
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
