L4-5 versus L5-S1 and the subtalar joint hypothesis

I have never heard this mentioned before so if you choose to pursue or reference the following I would appreciate the credit :).

Subtalar joint high axis creates greater transverse plane (rotation ) to frontal plane (sidebend) calcaneal motion.

Subtalar joint low axis creates greater frontal plane (sidebend) to transverse plane (rotation) calcaneal motion.

L5-S1 articulation has greater frontal plane (sidebend) to transverse plane (rotation) motion.

L4-L5 articulation has greater transverse plane (rotation) to frontal plane (sidebend) motion.


because L4-L5 has greater capacity to tolerate rotation versus L5-S1:

Subtalar joint high axis tolerated better at L4-L5 versus L5-S1 theoretically creating greater harm at L5-S1.


L5-S1 has greater capacity to tolerate sidebend versus L4-L5.

Subtalar joint low axis tolerated better at L5-S1 theoretically creating greater harm at L4-L5.


Following video is nontechnical overview of motion preference via facet joints in the spine.  Not focused on lumbar region by itself.


SI joint pain and the subtalar joint. Hypothesis 2

Motion in a joint moves perpendicular to the axis.  For example reference the following image.

Image result for joints move perpendicular to axis hinge


Image result for subtalar joint axis



The subtalar and sacroiliac (SI) joint share a very interesting property.  The axis appears to be similar with the  subtalar joint highly utilized in the frontal and transverse planes.






Image result for sacroiliac joint axis

The sacroiliac joint also is highly utilized in the frontal and transverse planes as evidenced by an oblique axis anterior to posterior like the subtalar joint.





Therefore given a “normal” subtalar joint, without ‘energy leaks up the kinetic chain’, a 1:1 ratio of frontal to transverse plane motion would reach the SI joint asking for a similar response.  Everything in this scenario would be happier than the following.

Image result for pes planus








The axis of the subtalar joint in the above picture has changed from “normal”.  The axis now has allowed for greater frontal plane motion than transverse.  Let’s say this ratio is now 2:1 frontal plane to transverse plane.  A subtalar joint with a 2:1 ratio now communicates to the sacroiliac joint (SI) joint asking for a 2:1 ratio of frontal to transverse plane.  The sacroiliac joint does not have much motion to give ~4 degrees.  Therefore it will begin to steal motion from above or below itself while being abused by moving contrary to it’s 1:1 axis.  Therefore we now have SI dysfunction from the subtalar joint.


SI joint pain and the sub talar joint. One hypothesis.

Let’s consider two positions of the calcaneus acting at the subtalar joint.

Image result for rearfoot varus

The image on the left demonstrates the calcaneus medially under the tibia creating a ‘longer leg’ by supinating the foot and lifting the tibia vertically.  The subtalar joint is stiff with this foot type and does not wiggle side to side and twist very well, but it could loosen up with the right stimulus.


The image on the right demonstrates the calcaneus laterally under the tibia creating a ‘shorter leg’ by allowing the tibia to drop down and in.  The subtalar joint is usually not the problem with this foot type and often times the calcaneus is able to wiggle side to side and twist very well.




From the foot types above we now have 1. a longer leg, and 2. a shorter leg.  This leg length discrepancy creates compensations from the ground up causing SI dysfunction on the ‘shorter side’.  I like this idea but not as much as the future post that will pose another hypothesis.

A link to a video I watched on youtube provided me with the idea of subtalar joint dysfunction, leading to leg length, leading to SI dysfunction.


The bullied bunion.

A bunion is when the big toe travels laterally toward the rest of the toes.


The purpose of this post is to help clarify one simple idea.  The big toe is a ‘reactive’ joint.  Meaning the big toe is responding to the stimulus that is being placed upon it.

If we approach the problem of a bunion knowing that it is not the fault of the big toe, then any intervention addressing the big toe without pursuing ‘why’ becomes limited in its efficacy.

Understanding how the foot works becomes paramount in addressing this problem.  Knowing that the rear foot and the mid foot function creates a healthy or harmful environment for the big toe is necessary to sleuth out the ‘villain’.

Searching GOOGLE for ‘bunion surgery’ I was surprised to see a Physician reviewed article stating “Wearing shoes that are too small or too narrow in the toe area is the most common cause of bunions.”  I wholeheartedly believe that this statement is not true and dangerous in not pursuing a true cause for this condition.

I have seen many surgical corrections or ‘bunionectomy’ procedures that guess what… begin to develop another bunion!  I would implore you to seek out a movement professional who understands biomechanics and the foot in order to help solve the real reason why the big toe is being bullied.

Foot Orthotic Paradigm shift

I have embraced the paradigm concerning foot orthotics that the aim or intervention goal is to ‘bring the ground up’ to accommodate the dysfunctional foot.  In other words change the ground to accommodate the foot.  This has presented me with difficulties when addressing a rigid foot type such as an uncompensated rear foot varus.

When changing this paradigm to ‘consider modifying the orthotic to change the foot before it hits the ground, options seem to present themselves.  In other words change the foot to accommodate the ground.  Here is an example.

If I have a foot type where the subtalar joint does not evert, how can I change ‘the ground’ to make the subtalar joint evert?Image result for rear foot varus


I do know that when you see an everted subtalar joint in stance then the problem is with the forefoot.  Therefore the forefoot can create and influence frontal plane load on the rearfoot during stance.

So If I have a subtalar joint that will not evert, what if I create a forefoot varus?  Depending on the degree of post I introduce under the forefoot I should be able to introduce a rectus position to the calcaneus and provide a stimulus of eversion when transitioning from heel strike -> to foot flat -> to midstance.

No I can attack those pesky IT-Band issues with greater efficacy!  Hooray!

Changing the paradigm of ‘bringing the ground up’ to ‘changing the foot type’ opens up possibilities in fabrication of orthotics.  Subtalar eversion would then require me to create a forefoot varus by essentially looking from the ground up as though I were creating a forefoot valgus.  Probably why the body adapts by creating plantarflexed first ray’s in the presence of a rearfoot varus.

This post is truly ‘thinking out loud’.  I ultimately believe creating dysfunction to address dysfunction is not the right way, yet I do feel that continuing to creatively problem solve and entertain ‘out of the box’ thinking is important.