Introduction to 3-D Foot/Ankle Complex

PLEASE SIGN UP FOR MY NEWSLETTER "MOVEMENT MATTERS" AS WELL!!!


Since I started this blog, I have wanted to write about the miracle of the Foot/Ankle Complex but hesitated every time as it is such a complex part of the body that deserves a lot of attention. I will admit that I spent over a year of intense study on the foot and ankle and still am at the beginning stages of understanding the comnplexity of the foot. However, there is a simplicity to the foot that makes it very understandable and approachable.

In this post, I will go into the SIMPLE SIDE of the 3-D Functional  Anatomy of the Foot and Ankle as well as the Chain Reaction Biomechanics.

Recently, I was able to give a presentation to group of private trainers in Washington, DC. The questions from the lecture demonstrated that these trainers were intelligent but also cared enough about their clients to want to learn about the complex foot.

3 RESPONSIBILITIES OF THE FOOT:


• The foot is an  shock absorber that allows for tri-planar eccentric loading for the rest of the body.
• The foot is stable propeller that allows the body to concentrically unload in all three planes

• The stability and mobility (MOSTABILITY) of the foot also provides a base of support for the body in balance.

SIMPLE SIDE FUNCTIONAL ANATOMY:

The ankle is composed of the articulations of the tibia/fibula and the superior aspect of the talus. The ankle joint is a UNIAXIAL joint with motion predominantly in the SAGITAL PLANE causing PLANTARFLEXION AND DORSIFLEXION with some motion in the TRANSVERSE PLANE AND FRONTAL PLANE due to the orientation of the lateral and medial malleoli. The picture below does not show the transverse or frontal plane motion but it is there in function. For instance, if a client or patient has had any degree of ankle sprains in the past, assesing the relatively small motion in those two planes could lead you to an lack of ROM that another part of the body may have to compensate for like the knee or hip.  

 
 
 

 

 

The FOOT can be broken up into three parts:

 

1. REARFOOT

2. MIDFOOT

3. FOREFOOT 

REARFOOT:

When we discuss the rearfoot, we will be referring to the SUBTALAR JOINT which is composed of the superior aspect of the CALCANEUS and the inferior facets of the TALUS.

FOREFOOT/MIDFOOT:

For all intensive purposes, the midtarsal joint is made up of two joints:

Talonavicular joint (Longitudinal axis)

Calcaneocuboid joint (Oblique axis)

It is interesting to note in the picture below, how that when we pronate the axes do not cross and actually separate from the netural position, but when we go into supination the axes cross more. This will be explained more in the Chain Reaction Biomechanics section below.

CHAIN REACTION BIOMECHANICS OF THE FOOT IN GAIT


“When the foot hits the ground, everything changes…

In gait, when the front foot makes contact with the ground, the first thing we should get is CALCANEAL EVERSION. As the calaneus goes through eversion, the talus that is sitting on top, drops down and inward. This creates PRONATION of the Subtalar Joint (STJ)


In function, when our STJ is pronating or going through eversion, our MTJ is unlocked or “wiggly-wiggly” to allow for proper shock absorption of the foot. Proximally, as the subtalar joint goes through eversion, we realize that is a “torque converter” as it transforms frontal plane motion in the foot/ankle to transverse plane motion of INTERNAL ROTATION of the tibia.
The opposite is true for the supination. As we go through inversion, our MTJ locks as the STJ goes through inversion to create a rigid lever that can propel us through the late stance phase in gait. The opposite reaction will occur proximally with the tibia going through EXTERNAL ROTATION..



FUNCTIONAL MUSCLE FUNCTION

As the foot goes through pronation, the body is able to take advantage of the various real bone and relative joint motion, to begin loading the musculature of the body to ECCENTRICALLY LOAD the lower extremities so that as we can create the proper neuromuscular stimulation for the CONCENTRIC UNLOAD that will effect the entire kinetic chain from the bottom to top.

If we are aware of the origins and insertions of the muscles of the lower extremities especially the ones that cross joints, we can fully understand the Chain Reaction Load/Explode sequence.

FUNCTIONAL IMPLICATIONS:
As we understand the tri-planar Chain Reaction of the body, we can tailor our approach to rehab, post-rehab and training and conditioning.


As a strategy, we realize that a Dual Approach of using:

• Bottom Up (Ground Reaction Forces)

• Top Down (Body Reaction Forces)

Appreciating what the foot does to the body, and what the body does to the foot, allows us to create situations and environments for our clients to be more successful.

Even though the foot and ankle are complex, the simplicity of the foot/ankle mechanism is easy to understand.

Functionally the foot is a:
1. Shock absorber

2. Rigid Lever Propeller

3. Mobile/Stable base of support

CONCLUSION:

As we work our way through the foot, we see that it can be very complex. Bones, ligaments, tendons, muscles, nerves, etc make the foot/ankle complex a challenging part of the body to work with but the simple side of function allows us to start to understand it. Whenever I do an assessment, I can always anchor to the Principles of Function as well as the 3 basic responsiblities of the foot and ankle. Whenever, I do that, I find that the comnplex foot really does become simple. It simnply reacts to bottom-up or top-down drivers but appreciates when we pay it the attention it deserves.

As always, if there are any questions, please do not hesitate to contact me at will@3doptimalperformance.com.

Happy Monday!

Will

As always, I want to thank Gary Gray, PT and David Tiberio, PT, PhD from the Gray Institute as well as Michael Kane MPT and Michael Hansen MPT for their guidance with the FOOT AND ANKLE!