This is the part 5 of a series that should be read in order.
Key Points:
- Example of the use of RCSP and NCSP
- 1/16 inch cant equals 1 degree change on average
- B1 and B2 devices max out their correction to 4-5 degrees of change in general
- Heel Stability achieved by Heel verticality and STJ Neutrality
- OCSP is RCSP standing on the Orthosis
- 4 Orthotic Methods of Achieving 3-4 more degrees of Pronation Control
- What is the difference between P1 and P2 Orthoses?
Let’s continue to discuss Pronation Orthosis. For the next few weeks, I will give you a different example for how the use of RCSP and NCSP helps define these patients, of course along with your dynamic evaluation of the severity of pronation seen.
Example1: RCSP 4 degrees everted
NCSP 3 degrees inverted
In this example, there is a 7 degree difference between RCSP and NCSP. The patient then is standing (and it is implied “will walk”) 7 degrees on the pronated side of neutral. This pronated gait leads to symptoms when matched with an overuse, repetitive motion activity like too many hours standing at work, too many miles on a bike, or too many steps walked or run. Can we use B1 orthosis for this situation? If our cast or image captures some degrees of forefoot varus, we can. This is called B1P. If our cast captures forefoot valgus, our balancing will not directly help a patient that pronates too much. Will B2 devices work? Although you can not use a B2 device to balance out forefoot varus for pronation control, you can easily use B2 devices for increased pronatory control by adding a good medial arch and some varus canting as several modifications. Remember there is 1 degree change per 1/16 inch canting on average, so this foot would require about ¼ inch varus canting to get them close to heel verticality.
What balancing prescription sets the patient at heel vertical, and what balancing prescription sets the patient at subtalar neutral? Both our uses of B1 and B2 are limited to a 4-5 degree change in RCSP in general. I rarely found greater change than this, but please let me know if you have seen more from something your lab does. We use another measurement called OCSP, which is Orthosis Calcaneal Stance Position, where we repeat the RCSP with the patient on top of their orthosis and then check for change. In these instances, we typically design an orthosis centering the heel at verticality. And since heel verticality is not subtalar joint neutral, yet a stable position, many will stop the correction if this is achieved. Yet, many problems will not improve well unless subtalar neutral is attained. I have emphasized this, as I have seen this over and over in my years of practice. The debate will go on about this, but I think that for now, we have to know how to get to this 3 degrees inverted position called subtalar joint neutrality. When your treatment plateaus without complete symptom-relief, or the patient continues to feel overly pronated, your first correction can be changed. Here, and in the subsequent posts, I will discuss these changes under P1, P2, P3, P4, P5, and P6.
P1 is your B orthotic device with 3-4 degrees of extra pronation correction.This is accomplished many ways within the industry. P2 is a combination of these variables to obtain 5-6 degrees of pronation correction. What methods are utilized for 3-4 degrees of additional heel correction?
- 4 mm medial heel (Kirby) skive
- 4 degree intrinsic varus cant (called “pour”)
- 4 degrees extrinsic varus rearfoot and forefoot posting
- 15 Degree Inverted Orthotic Technique
What is typically combined to get 5-6 degrees of pronation correction? The above are typically combined: A&B, A&C, A&D, and C&D. These are your typical P2 devices with the common changes from B. The medial heel cup is usually higher. The width of the frame is usually wider. The thickness of the frame is usually firmer. The extrinsic rearfoot post typically has 0-2 degrees of pronatory motion, and I typically flat post (0 degrees).
As you begin to change from your Gold Standard (B) inserts to P inserts, not only can RCSP and NCSP help you, but also OCSP. OCSP, just mentioned above, stands for orthotic calcaneal stance position and was popularized by Dr Kevin Kirby. You first bisect the heel and measure RCSP with the patient standing. You then stand them up on their orthoses, and repeat the same measurement. In summary, the 4 measurements/techniques to learn first, if you are new to this game, are heel bisection, RCSP, OCSP (when there is an orthotic to stand upon), and NCSP.
Review of all the Orthotic Types Being Presented
Corrective Orthotic Devices
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- 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
Foot with laterally deviated subtalar joint axis by K.Kirby
