The greater your biomechancial knowledge the less you know about how foot orthotics work?

As the others have said, we don't have evidence that we have changed the position of the STJ. We know that we are trying to, but we don't know that we have. Even if we have changed the position of the STJ, we may not have changed it enough to significantly move the STJ axis. What I mean is that moving the axis in one individual may be a lot less than variation across individuals. So, if someone has a medially positioned STJ axis we may not be able to move it far enough so that the patient functions as someone with an average axis position.

As Kevin said, moment are probably more important than position. You can reduce stress by changing moments, without changing the position of the foot.


Regarding bone axes and motion axes I'd recomend you read:

1: Acta Orthop Scand Suppl. 1983;204:1-269. EJ van Langelaan

This was a paper Kevin pointed out to me when I was a third year student. It changed my life in that it helped me question what I was being taught about biomechanics. It also describes axes of motion for individual bones with STJ motion. I think it is still a good read.


Eric

 

thanks Eric

I´ll try and track that down unless you have a copy of the paper you could email me or place a link here.

 

It's a big lad, hence it was published as a supplement. I don't think that I have copy of this anymore, but it should be read by anyone with an interest in the biomechanics of the foot. To an extent The Nester's work is carrying this baton forward..

"Nestor 1: [eating a hot dog for the first time] There's no dog in this.
Cowboy: Uh-uh.
Nestor 1: Hydrolyzed vegetable protein, soybean meal, niacin, dextrose, and sodium nitrate flavoring.
Cowboy: Yup, that's what we call "meat" back home"

Battle beyond the stars.

OK, so he uses an "e" rather than an "o" but so did Shaun Ryder, and he turned out OK. You know the score Chris. :drinks

 

Eric:

That was 25 years ago Eric!! I guess I don't remember that incident specifically but I do know that I still have my original copy of the paper (Van Langelaan EJ: A kinematical analysis of the tarsal joints. Acta Orthop. Scand., 54:Suppl. 204, 135-229, 1983). However, this paper is not just a good read, it is a great read!

In fact, this single paper (more like a book in length) probably did more to change my thinking regarding the biomechanics of the subtalar joint and midtarsal joint during my Biomechanics Fellowship than any other paper I have ever read. I just happened to find it one day while exploring the CCPM library during my Fellowship. What a find that was! Maybe somebody with a library service can see if they can get a pdf copy of this paper for all to read. Really, this paper, is still very fresh and exciting, even though it is over a quarter century old!

 

I was looking for stuff for a paper writing contest sponsored by Langer on the function of the MTJ. This was at the very beginning of the availability of computer search for papers. The CCPM library had just gotten a program that had CD's that were searchable for journal articles. I probably would have never found the paper and would have written a pretty boring paper and would never have co-won the contest. It was interesting to be co-winner. There was another paper that repeated the current beliefs and my paper that questioned the current beliefs using what was written in Van Langelaan's paper. I'm grateful to the folks at Langer for not suppressing a dissident paper. Boy I am feeling old. A time before medlline....

Eric