Kevin and Colleagues,



Agree, and Bart is correct on the free-body analysis. We non-podiatrists need to stick together...:-)



To add to Bart, and start to getting what needs to be done to get quantified results/answers (moving a step up from qualified best guest-estimates) is using a finite element analysis on the soft and hard tissues of foot and and leg, and then drive this with GRF. Not the resultant, but with all GRFs activing/recorded on the full plantar surface, and this during standing, walking, and other activities such as running (well, I suggest starting with walking). In-shoe and/or floor mat pressure/force systems do provide vGRFs on full surface of plantar foot, ideally in-shoe, since we (North-America and Europe) spend most time walking with footwear. I do not exclude here barefoot walking (and standing).



Do not get or quote me wrong on the phrase qualified best guest-estimates, this is where hypotheses come from (information and deductions based on this information), then verfiy, confirmed and/or denied from quantified results.



Second best, is to use bone embedded markers, and correlate sync bone displacement (rotation & translation) with GRF acting per the bones. This is achieveable with use of fluroscopy. When doing the bone pin studies in Sweden, we used fluroscope to monitor insertion (drilling) of the pins in the bones. With force and motion quantified, then inverse-dynamics and/or with other wonderfull long eqautions can be used to caluclate moments, inertia, moments of inertia, power, energy (will stop here). Fluroscopy was not used in the actually walking trials, set-up of tube was limited (physical) to the table were subjects were lying when inserting the pins.

 

I must admit that I am at a disadvantge on French-Canadian vs Belgium, since Belgium is one of leaders. Nonetheless, I like underdogs, and underdogs do at times reveal surprises when back is against the wall (tried to find analogy with feet, but not succeeded, yet, apologies). But again, maybe Belgium is better, simply because Frech-Canadian was best, Belgium copied and improved on.



Still waitng from Bart on his literal translation in Flemish on "Flow of Force"...:-).

 

Cheers (Santé in French-Canadian, what about other languages? Flemish for example....)



Norman



P.S. Hypothesis, based on experience information, we will solve any equations related to free-body analysis. Nothing better than reproducing the study.



	-----Original Message----- 

	From: A group for the academic discussion of current issues in podiatry on behalf of Kevin Kirby 

	Sent: Wed 9/22/2004 12:22 AM 

	To: [log in to unmask] 

	Cc: 

	Subject: Re: GRF on Forefoot, What Moves?

	

	

	Bart, Norman and Colleagues:

	 

	Bart wrote:

	 

	<<This is not a simple problem Kevin. What you ask is a free body

	analysis of a 4-segment model, but not a common one, because the

	interaction at the hinges is complicated by an extra  joint moment

	that is affected by the varying angle between the *two* adjacent

	segments. It is therefore certain that the inertia moments of the

	segments will influence the  angular acceleration of the segment, an

	thus also the relative angular acceleration between the segments. So

	no answers are readily available on your questions. One first has to

	solve the free body equations !

	And honestly, I am not in the mood to solve it tonight.

	But I 'll put it on the podiatric gold list. When I finish the hallux

	limitus paper I am working on now, it may get a chance, especially if

	you can convince me with a few excellent brews at the bar in Boston.>>

	 

	 I'd be happy to discuss this problem over a few beers with you in Boston, Bart. I'll be sure that we'll be able to find Norman there at the bar trying to return back to his previous gravitational acceleration capabilities.  If Norman joins in, we'll need to see if we can find some good French-Canadian beer and then determine if it meets the high standards of the beers from Belgium.  Then, after the taste tests are done, we will really be able to solve this difficult free body analysis.  Can't wait. ;-)

	 

	Sincerely,

	 

	Kevin

	 

	****************************************************************************

	Kevin A. Kirby, DPM

	Adjunct Associate Professor

	Department of Applied Biomechanics

	California School of Podiatric Medicine at Samuel Merritt College

	 

	Private Practice:

	107 Scripps Drive, Suite 200

	Sacramento, CA  95825  USA

	 

	Voice:  (916) 925-8111     Fax:  (916) 925-8136

	***************************************************************************



----------------------------------------------------------------- This message was distributed by the Podiatry JISCmail list server 



All opinions and assertions contained in this message are those of the original author. The listowner(s) and the JISCmail service take no responsibility for the content. 



to leave the Podiatry email list send a message containing the text leave podiatry to [log in to unmask] 



Please visit http://www.jiscmail.ac.uk for any further information -----------------------------------------------------------------