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Spatial orientation of the subtalar joint axis is different in subjects with and without Achilles tendon disorders
Claudia A Reule, Wilfried W Alt, Heinz Lohrer, Harald Hochwald
Br J Sports Med doi:10.1136/bjsm.2010.080119

 

Only a quick scan so far, really interesting methodology. This jumped out: "Standard textbook descriptions of the subtalar axis should possibly be revised"

D'ya think?

Or as they say in blighty: "no sh!t, Sherlock".

 

Haven't read it yet, but scanned the references. My first thoughts: Where's the love for Kirby??

 

At least he got one in there.

 

My bad - you're right. Didn't see it on my first cursory glance

 

Actually, they have two of my papers referenced, one I authored, and the other, I was one of the coauthors.

Kirby KA: Subtalar joint axis location and rotational equilibrium theory of foot function. JAPMA, 91:465-488, 2001.

Lewis GS, Cohen TL, Seisler AR, Kirby KA, Sheehan FT, Piazza SJ: In vivo tests of an improved method for functional location of the subtalar joint axis. J Biomechanics, 42:146-151, 2009.

Not really too sure about how accurate their STJ spatial location measurement method was unless they were careful to apply a constant plantar load to the forefoot while they put the STJ through a range of motion. In the device we designed and used in the Lewis et al study, we had a custom jig that applied a constant dorsiflexion moment at the ankle joint to "lock" the talus within the ankle joint to minimize ankle joint motion. I don't see any mention of this in their article.

It is nice to see that other researchers now realize that there is a "a wide interindividual variability of the spatial orientation of the subtalar joint axis".

Here is what I wrote in my original article on STJ axis location from 24 years ago.

 

Kevin- you may recall this was presented at iFab last year... Good to see it published.
Ian... Can you send me a copy also?
Ta

 

Craig:

I thought it looked familiar...I'm also glad to see it published since it may now possibly wake up the rest of the international biomechanics community to the fact that they can no longer assume, for kinetics studies, that the inversion-eversion axis of the foot is a longitudinal bisection of the foot.

 

It also assumes that there is no movement occurring in the ankle mortice. While maximally dorsiflexing the ankle might reduce this, I'm not convinced it is eliminated. But good work, none-the-less. All they need to do now, is make the jig small enough to be worn for dynamic studies.... Perhaps if they read the STJ axis locator paper they could have their ultrasonic wizardry fixed to a similar jig to the one we developed, Kevin?

 

it is a good study actually

 

In vivo determination of the Achilles tendon moment arm in three-dimensions.
Hashizume S, Iwanuma S, Akagi R, Kanehisa H, Kawakami Y, Yanai T.
J Biomech. 2012 Jan 10;45(2):409-13.

 

Is Calcaneal Inclination Higher in Patients with Insertional Achilles Tendinosis?A Case-controlled, Cross-sectional Study
Naohiro Shibuya, Jakob C. Thorud, Monica R. Agarwal, Daniel C. Jupiter
Jnl Foot Ank Surg (Article in Press)