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I am a student about to take my exams and one of our practice questions asks "assuming foot has a normal midtarsal joint locking position, explain what is happening at the midtarsal joint at point x" x on my graph is STJ neutral. I know that MTJO and LTJO become fully pronated and locked (osseous locking mechanism) but please can anyone tell me what happens with regard to the windlass mechanism?
Re: what happens with regard to Windlass mechanism when STJ is in neutral and MTJO/LTJO are both fully pronated
Quote:
Originally Posted by karenlee
Hi all
I am a student about to take my exams and one of our practice questions asks "assuming foot has a normal midtarsal joint locking position, explain what is happening at the midtarsal joint at point x" x on my graph is STJ neutral. I know that MTJO and LTJO become fully pronated and locked (osseous locking mechanism) but please can anyone tell me what happens with regard to the windlass mechanism?
thank you in anticipation
Karen Who is teaching you this re MTJ locking and the 2 axis theory - it wrong outdated and well just wrong.
I understand that your about to take you exams , but I would ask your teachers (maybe after the exam ) why they are teaching you stuff that is outdated and wrong, the MTJ does not lock, it does not have an oblique and longitudinal axis.
SUMMARY
In the present study we have estimated the temporal elongation of the plantar aponeurosis (PA) during normal walking using a
subject-specific multi-segment rigid-body model of the foot. As previous studies have suggested that muscular forces at the ankle
can pre-load the PA prior to heel-strike, the main purpose of the current study was to test, through modelling, whether there is
any tension present in the PA during early stance phase. Reflective markers were attached to bony landmarks to track the
kinematics of the calcaneus, metatarsus and toes during barefoot walking. Ultrasonography measurements were performed on
three subjects to determine both the location of the origin of the PA on the plantar aspect of the calcaneus, and the radii of the
metatarsal heads. Starting with the foot in a neutral, unloaded position, inverse kinematics allowed calculation of the tension in
the five slips of the PA during the whole duration of the stance phase. The results show that the PA experienced tension
significantly above rest during early stance phase in all subjects (P<0.01), thus providing support for the PA-preloading
hypothesis. The amount of preloading and the maximum elongation of the slips of the PA decreased from medial to lateral. The
mean maximum tension exerted by the PA was 1.5 BW (body weight) over the three subjects.
Re: what happens with regard to Windlass mechanism when STJ is in neutral and MTJO/LTJO are both fully pronated
I haven't read of those papers, to be honest we only started discussing windlass mechanism last week for a whole 20 minutes!! So I guess at this stage I'm just trying to read what I need to get my through exams as I have 4 exams coming up in May - One of them being on gait analysis and this question just happened to be on practice paper and it was only question that I didnt really understand at all.
Re: what happens with regard to Windlass mechanism when STJ is in neutral and MTJO/LTJO are both fully pronated
Ah, c'mon Mike! You want the poor girl to tell her lecturers they've got it all wrong a month before the finals? Thats just cruel. They hate it when someone corrects the questions.
Its been a while since I did "old School" biomechanics but I would guess that the answer they want is that the windlass mechanism plantarflexes the 1st met, supinating the sub talar joint and that we will will find the MTJ fully locked and pronated at the point the sub talar joint is in neutral, the foot returning to a rigid lever for propulsion.
Personnaly, if a student ever said that to me I'd give them up as a bad job, beat them to death with a goniometer and feed the body into my grinder. But I dimly remember that from my training days as being the official version.
Re: What happens with regard to Windlass mechanism when STJ is in neutral and MTJO/LTJO are both fully pronated
This reminds me of a quote. I believe that it was Craig Payne that repeated it at a lecture. It was a professor on the first day of class saying to his students "Half of what I'm going to teach you is wrong. The problem is, I don't know which half is wrong."
When I was in podiatry college we had an education committe who took questions that we felt were bad to the professor, with literature evidence, and a proposed mechanism for dealing with the correction. For example, accept all answers as correct. If this one comes up on the exam, post it and we'll help you out. In real life you can ignore the question as there is no such thing as a locking mechanism.
Re: What happens with regard to Windlass mechanism when STJ is in neutral and MTJO/LTJO are both fully pronated
This reminds me somewhat of when I took my orthopedic board recertification exam and I talked to Larry Huppin, DPM, who also was in the room taking it with me about 10 years ago. We both walked out of the test thinking that we had flunked the biomechanics section of the exam since the test was written using old Root biomechanics ideas from two decades prior. Both Larry had been lecturing on STJ axis location/rotational equilibrium ideas for the past 5-15 years before the test, and, of course, these newer concepts weren't included on the test. I had to forget all the new stuff just to answer the test questions the way I thought they wanted the exam questions answered.
These types of experiences makes me realize how much things have changed in a positive direction for podiatric biomechanics over the past 25 years. It is pretty amazing how far we have come when I think about it.....midtarsal joint locking, longitudinal midtarsal joint, oblique midtarsal joint, balancing all orthoses with heel vertical, rigid forefoot valgus, flexible forefoot valgus, no forefoot extensions, eight biophysical criteria for normalcy, first ray hypermobility......hopefully all things of the past.......
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
What happens with regard to Windlass mechanism when STJ is in neutral and MTJO/LTJO are both fully pronated
They hate it when someone corrects the questions. 
Linear Mode
