Fun with Numbers: RCSP, OCSP, MPP | KevinRoot Medical

Fun with Numbers: RCSP, OCSP, MPP

  • Fun with Numbers: RCSP, OCSP, MPP



    I love taking measurements! I measure everything I can, and I have done this for years! I want to talk about one of the students from my class at Samuel Merritt University's College of Podiatric Medicine. These are 2nd year students and they are learning about the importance of measurements in understanding biomechanical problems and solutions. This photo was of the 4 students in our rotation and the measurements of  RCSP, OCSP, and MPP. Three very important measurements that are taken all the time, and this class was during dispense of their custom made functional foot orthotic devices. 

    Let us only look today at Anhanh being measured by Brittany. The students in the class take all the measurements and all the casts for the orthoses, and I make the devices on their Rx. It is a great learning experience for them. We will talk about other students/patients in the future, but today I want you to understand the lingo.

    The first thing the student had their heels bisected in prone position. Then the student was stood up and the RCSP (Relaxed Calcaneal Stance Position or Resting Calcaneal Position was measured. Our first measurement was:


    (R).  9 degrees Everted             

    (L).   6 degrees Everted

    This is a patient with everted heels right more pronated than left. Also, a difference in RCSP means that they have a functional short right side, or a combination long right side with 3/16th inch functional shortening for compensation. Remember each 1 degree difference right to left is 1/16th difference in functional leg difference. 

    Now, we place their new orthotic devices under the heels and measure OCSP or Orthotic Calcaneal Stance Position (I believed first coined by Dr Kevin Kirby). I had built in varus corrections to both sides of this student and wanted to see what I had accomplished. 

    RCSP                             OCSP

    (R) 9 everted                4 everted

    (L) 6 everted                3 everted

    Therefore, my orthotic devices changed the heel eversion for the better 5 degrees on the right and 3 degrees better on the left. This was not what their Rx asked for exactly, as it the case in life with bell shaped curves, but improvement was undeniable. 

    Our 3rd classic measurement was MPP. This means finding the subtalar joint (when standing) maximally pronated position. It is a great reference point for our measurements as we do not want to hold a patient in their maximally pronated position. This is a stable position at the end point of the subtalar joint range of motion. But, it means that the subtalar joint can not adapt to the ground when further pronation is needed. It signifies that the eversion required has be created in the ankle, knee and/or hip, and these are injury related motions. More ankle and knee valgus torque!!!

    MPP measurement that I used I learned in school, but Dr Kevin Kirby created a version that also is useful. You are not having the patient stand on their orthoses.

    RCSP                        OCSP                      MPP

    (R). 9 everted          4 everted               14 everted

    (L)  6 everted          3 everted                 6 everted

    When we compare RCSP to MPP, the right side was more pronated but far away from being maximally pronated. The left side however was functioning at their MPP, until the orthoses place them 3 degrees inverted from their MPP. This is the general rule with MPP: keep the foot 2-3 degrees on the inverted side of MPP for less lower extremity problems and more surface adaptability. 

    I hope this case gives you a good idea of the practice of these 3 measurements. 

    Teacher's Paradise working with Students that want to Learn!!!!

  • Great post- thanks Dr. Blake!

  • Rich-I'm trying to remember if I've had a patient that was 9 degrees everted and NOT maximally pronated. An 9* everted RCSP is usually beyond the "tipping point" where the foot will automatically fully evert the calcaneus/ pronate the STJ to the end of the ROM, due to its inherant instability. Plus, this pair of feet are quite asymetrical in their measurements; is there an actual leg length present?

    I see the other students had similar RCSP & MPP numbers. Yes, I can usually get another degree or two of eversion while checking a pt's RCSP and if they're also maximally pronated by applying a very large force medially against the fibula and I feel like I'm really stretching the T-C joint capsule and deep ligaments when I'm doing this max pronation test.

    Interesting study, Rich! You went to Riordon, right? -Mark

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