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.

Therefore:

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.