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Like your other question, I can't believe that this is still being taught. We stopped doing that kind of stuff last century.
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Hi Kona,
You seem to be working from very old material:rolleyes:
Where are you located? -
im a second year pod student in the states, and i have no idea whats out dated or not. its brand new to me, and its kicking my-----.
all i know is i have to master this way of learning. like, now.
so, how can i calculate rcsp ? is there an equation for it, like there is for stjnp?
some people can visualize it by the numbers. like "oh! if i calculate NCSP to be a 2 varus, my forefoot is off the floor 6 varus, and my maximally pronated stance is 5 degrees everted, OF COURSE my RCSP is 4 everted! duh! "
but i can't , so if anyone learned this the old school way and can show me a method that will get me thru an exam, please, help :bang: becuase i can do the math, but when it comes to that last part its hit or miss for me. -
I work in a biomechanics only practice in Brisbane, where our standard procedure is to take quite detailed biomech assessments. :hammer:
The only way that we calculate RCSP is through measuring it (using heel & tibial bisection lines & a protractor) with the patient in relaxed stance. I don't know of any way of calculating it with a standard equation... :confused:
From what I see in analysing the various biomechanical measurements that I take on a daily basis, there are many individual factors (eg. hypermobility/STJ axis location/injury status/etc) that will influence the relationship between RCSP, NCSP, relaxed/neutral tibial angle etc. There is no single equation that will explain everything... if only it was that easy, but we are working with biological (and therefore highly variable) structures.
You might like to have a look at some of Kevin Kirby's papers including subjects on "Tissue Stress Theory" and "Thinking Like An Engineer" for a more up to date perspective on podiatric biomechanics.
Regards
Donna ;) -
thanks donna--i wish i had time to read articles, but my exam is tommorow..
i cant believe there is not a way to calculate RCSP on paper using theoretical values. dont you examine the patient , get thier numbers, and compare by calculation as well? -
Is this a wind up?
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Here is what I did when I was a podiatry student (1979-1983) before the internet became the preferred source of finding examination information for podiatry students:
1. Attended all the classes I could.
2. Took notes during the lecture.
3. Asked questions during the lecture if I didn't understand the material.
4. Asked questions of the professor after the lecture if I didn't understand the material.
5. Asked questions of fellow students who may have understood things better than I did.
6. Studied my notes and the reading assignments well before the examinations.
I know this may seem old-fashioned, but it worked quite well me. You might want to give it a try sometime. -
thanks for the advice-
ive attended all the lectures, asked questions, did all of that. just wondering if there was a way to calculate RCSP that was more straight forward, thats all..
unfortunately students who do get it, and clinicians who teach, sometimes get things so intuitively that they don't explain things well --in a way a dummy can understand it, lol
so i came here as a last resort..didn't mean to offend anyone.
cheers,
kona -
Contrary to what you may have been taught, there is no current method by which to accurately calculate the relaxed calcaneal stance position (RCSP) unless some very gross assumptions are made that are not accurate. I would try to get one of your smarter classmates to help you with your question since we don't know what you are being taught by your professors.
By the way, which podiatry school do you attend and who is your biomechanics professor? -
hello Kona,
my uni's biomechanics class was like that too. no matter how many times i had it explained to me or how many problems i did there was always one that thru me off.
do you have old problems? do as many as you can before the exam.
unfortunately i dont think there is a calculation that you can plug and chug for the rcsp. that why you examine the patient, lol
usually it depends on the ff to the floor. ive been told to use your hand on exams, with one hand being yr ncsp (total reafoot) and the other being how far the ff is off the ground. the point is you want the ff to the floor.
use the ncsp you calculate plus that to determine where it should be, but it depends on each situation.
you can send me a message and ill try to explain it better
good luck!:eek: -
These biomechanics questions from the US podiatry students reminds me of the time when I took my recertification examination for the American Board of Podiatric Orthopedics and Primary Podiatric Medicine a few years ago. In the exam there were a number of "biomechanics questions" that appeared to be written by the some of the biomechanics professors in the States who hadn't read anything new on biomechanics for the past 20 years.
Both Larry Huppin, DPM, who had been a student of mine and a Biomechanics Fellow after Eric Fuller and I did the program, spoke about this test after we took it. We both felt that we probably flunked the biomechanics section of the test since we had tried to forget all the "stuff" (this is the nicest word I can think of to describe it) we were taught about biomechanics as students in podiatry school.
All I can say is we have a long way to go as a profession since I don't think that most podiatry students are being taught current information on biomechanics....for reasons I won't even start to speculate on. -
I find it frightening that this is still being taught. Makes me feel like the revolution just passed certain corners by. To quote Bill Hicks: "While some are shouting "revolution, revolution" others are still waiting for evolution "we want our opposable thumbs".
I'd heard there were problems with biomechanics education in the States, I didn't think it was this bad. -
There seem to be problems at many of the schools.....probably relics of another generation?! There is only so much that a few of us who teach the newer ideas can do. :craig::bang: :eek: -
You should talk to your dean about how people who have published recently (The last 15years:rolleyes:) in podiatric publications on the subject of biomechanics believe that what you are being taught is outdated and inaccurate. I would be quite amused to be in on that discussion. It would be a pleasure to help drag podiatric biomechanics into the current century.
To help you out in your class, try drawing stick diagrams. Draw a vertical line to represent the leg. ( if there is tibial varum draw the line that number of degrees off of vertical. ) Then draw a heel bisection line in various positions that you have numbers for. e.g.calcaneal eversion. (One of the major problems students had with these problems is that they did not understand the definitions of the lines.) Calcaneal eversion is eversion of the calcaneus relative to the leg and not to the ground. So, if you know the relation of the leg to the ground and you know the STJ is in its maximally pronated position, and the amount of eversion available, then you can calculate the relationship of the calcaneus to the ground.
You cannot calculate RCSP from the numbers that you listed unless you know where the STJ is within its available range of motion. Or you are given a rule that tells you where the STJ is within its range of motion. This rule does not apply to the real world.
The one major real wordl concept that can be learned from these excercises is the concept of a partially compensated varus (forefoot or rearfoot). A foot that does not have the range of motoin to get the medial forefoot to the ground will tend to have high pressures under the lateral forefoot in stance and early phases of gait.
Entire semesters were used to essentially teach the above point. Much time wasted.
"when the STJ goes to end range of pronation, what exactly does that mean? is that equal to the NCSP or?"
Take a non weight bearing leg draw a line on the leg and heel and move the STJ through its range of motion. Sometimes, the abstract book concept is learned better when you apply things in the real world. The end of the range of motion is a very important concept clinically and something you should be able to have someone locally teach you. It's also relevant surgically as there are surgical plugs that alter the location of the end or the range of motion. You should read Kevin Kirby's paper on the roational equilibrium about the STJ axis. In it there is a nice picture showing the real anatomical cause of the end of range of motion.
Regards,
Eric -
Hi Craig,
So what do you teach instead? Are you saying the RSCP is irrelevent? Do you measure subtalar joint motion? In the UK all the orthotic labs ask for the NCSP,RCSP, forefoot deviation, 1st ray position etc. on their prescription forms. Do you do it differently? -
You need to come to a Boot Camp... -
I can't help but feel the trailblazers who have advanced the knowledge have left a good portion of the profession behind! There seems to be a big gap.
Lawrence correctly cited in another thread that what we tend to think of as "rootian biomechanics" is not entirely based in the teaching of Root. Who knows, perhaps that is the reason the "Rootian biomechanics" has become bastardized with something else, driven by lab-which-shall-not-be-named-which-rhymes-with-hanger. To make it accessible to the paying masses of podiatrists.
Perhaps its merely a dark mood brought on by a week long cluster headache but I sometimes feel the future of biomechanics is not so bright. And I wonder if that is by accident or dark design. For every colleague I meet who trys to grasp biomechanics (at whatever stage in their journey they are) I meet so many more who just can't be bothered.
Enough conspiracy theory.
Robert -
I did the Boot camp - liked the 1st day.
How do you know the ROM is "adequate" without assessing it? Maybe its inadequate and that's the source of their pain.
Measurement of STJ ROM by measuring heel bisection was shown to be reliable in 1 study I believe - forget the ref - about 6/7 yrs ago in JAPMA. I think they used a caliper to aid the bisection marking. However that's of course only one study. Maybe there is a better way of assessing the ROM other than by heel bisection and observing frontal plane movement?
Simon, Kevin why havent you produce a version of your "talus tracker" for the mass market?????? -
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You could ask the labs what they do with the numbers. Does it change how they make the piece of plastic? If they do change how they make the orthotic based on RCSP and NCSP do they have any studies to back up that it improves the othotic. Heck, do they even have any clinical experience where they've given someone an orthotic made one way and then give them an orhtotic made a different way?
Cheers,
Eric Fuller -
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What's your assessment method Craig?
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you notate it as "adequate" or "inadequate"?
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:D Got any data on your reliabilty? :D:boxing:
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Regards,
Stanley -
Or indeed why meaure it?:rolleyes:
I did my undergrad project on intra and inter reliability of measuring RSCP. Been done far better by others using experianced clinicians, my sample group was final year students. The range was 17 degrees for inter-tester!
Regards
Robert -
Recently an osteopath colleague of mine added a rearfoot post of 20 degrees varus to an orthotic.He said he tested this with applied kinesiology and the patient 'strengthened' up. In my opinion in put her calc into an extremely inverted position, likely to cause lateral instability. He didn't actually measure anything...but it didn't look good when the patient stood on the orthoses. -
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I want to understand this, and wonder if I am being a bit dense/stuck in the 20th century. As force has magnitude and direction, isn't excessive movement an issue ? Do you measure/observe the change your posting is making to the forces by dynamic pressure scan/video/eyeballing/ before you issue an orthotic?
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Force causes movement, not the other way around. Force starts something moving, changes its direction and stops it moving. (See Newtons First Law...)
Excessive movement is not an issue -> its the forces behind it which may (or may not) be pathological.
Ian -
Hi Ian
Yes, movement is a visible sign of the effect of the force.
So how do you apply this therapeutically...are you basically countering one force with another in order to reduce tissue stress, and do you quantify the forces required to do this i.e. how do you translate that into posting/balancing/raises etc. Is it by eyeballing/experience/guesswork/measurement? -
Just as an aside, measuring IS eyeballing and guesswork. You eyeball and palpate to draw your calc / calf bisections then eyeball the goniometer against your eyeballed lines. But don't let the accuracy of the goniometer fool you, its only as good as the accuracy of you're lines and they are based on eyeballing and palpation. Which has been shown to be unrepeatable.
Its not measurement OR observation. Measurement is based on observation.
We now return you to your debate.
Robert -
Some inevitable familiarities cropping up between this and the 'do you measure...' thread.
Therapeutically I try to ascertain how much force I need the orthoses to exert in order to bring about a therapeutic effect (reduce the pathological force within the injured structure).
So taking tibialis posterior tendinopathy as an example, rather than 'measuring' a RCSP of 4 degrees everted and giving a 4 degree varus rearfoot post (in the belief that will 'correct/balance' the foot??) instead the two main things of consideration here (in my opinion) would be the supination resistance test (how much force is required to supinate the foot) and the transverse plane location of the STJ axis (in order to know the available 'area' where the ORF will have a supinatory effect). The posting is dictated by how hard the foot is to supinate. Harder it is -> higher the post.
So to answer your question, its a bit of guess-timation based on experience and good clinical reasoning.
Ian -
That's a very useful answer..........it's easy to get bogged down in the arguments but at the end of the day it's how we apply it to clinical practice that is important.
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Just for a laugh. Once you have decided that a supination resistance test says high force required and the location of the axis is medial and youve decided to use a medial wedge, how do you decide how much?
L -
I don't want to be nitpicky, but I have seen these phrases bantered about on Podiatry Arena for some time and want to make a clarification. To say that "force causes movement, not the other way around" is not exactly correct. A change in force acting on an object will produce an acceleration of that object, unless there is an equal and opposite force also acting simultaneously on that object. The movement of an object can certainly produce force if the movement of the object is decelerated by another object.
In addition, since excessive movement implies increased strains on tissues, which, by definition, will also include increased tensile stress on the viscoelastic tissues that restrain that movement, then excessive movement, or lack of movement, may certainly be one criteria we use when evaluating what the possible cause of an injury is.
I would rather rephrase your last sentence as: "Excessive motion is not always the cause of injury but rather the internal forces, moments and stresses that result from that excessive motion that are the cause of injury."
Hope this makes sense so that the others following along understand these ideas with improved clarity.
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