Is the “normal foot” normal ?

IF one foot is not normal, the other one cannot be “normal” either.  This is a blog post about symmetry, sort of.

This article just sort of seemed silly to us.

Imagine having a stone in one shoe and walking around in that shoe. Obviously you are gonna alter weight bearing in that shoe to avoid the pain and pressure of the stone. That means that the normal gait cycle of that foot/leg will be distorted somehow, the timed events of the gait cycle will be distorted and even likely the duration of the stance phase, heck, even plantar pressures will be changed.  Thus, the apparently “normal” foot on the opposite side will have an altered loading response and challenge because it will be receiving anything but normal biomechanics from the “stoned” shoe/foot.  Adaptation and compensation will have to occur, and not just in the “normal” foot, the entire body. 

Take another example, a sprained ankle. The brain will abbreviate the painful stance phase and abrupty depart the foot and thus create premature loading on the healthy foot, likely into mid-midstance which is usually met by midfoot strike and catching the body load with the quad thanks to abrupt knee flexion rather than early midstance with glute control during the loading response.  

Thus, if one foot is abnormal, there is just no way the so-called “normal” foot will be unaffected.  As this study suggests, the normal foot will have altered pedobarographic measurements.  Maybe we are missing the point here, but we suppose the words “relatively normal” or an “expected normal” should have been used. Yes, we may be splitting hairs here and discussing a relatively moot point, but our purpose was to just describe that since the two limbs are attached to the same body, if one side is not normal, a compensation has to occur in the other limb.  There is no other option.  We talk more about this concept in podcast 75 which will launch next week.

Shawn and Ivo, the gait guys

The contralateral foot in children with unilateral clubfoot, is the unaffected side normal?

http://www.gaitposture.com/article/S0966-6362(14)00523-2/abstract

Highlights

  • Pedobarographic measurements of unilateral unaffected clubfoot are not same as normal controls.
  • The unaffected foot should not be referred to as normal, nor should it be used as a control.
  • Timings of initiation of stance differ significantly between normal and unaffected clubfeet.
  • Unaffected clubfoot accumulates differences from normal feet due to maturation of gait with age.

Abstract

“Significant differences were identified between the unaffected side and normal controls for the pressure distribution, order of initial contact and foot contact time. These differences evolved and changed with age. The pedobarographic measurements of patients with clubfoot are not normal for the unaffected foot. As such the unaffected foot should not be referred to as normal, nor should it be used as a control.”

The Abductor Heel Twist: Look carefully, it is here in this video.

This should be a simple “piece it together” video case study for you all by this point. This young lad came into our office with left insertional achilles pain of two weeks duration after starting some middle distance running.

What do you see here ? It is evident on both the right and the left, but it is a little more obvious on the left and can be seen on the left when he is walking back toward the camera as well.  You should see rearfoot eversion, it is excessive, and a small rearfoot adductor twist. Meaning, the heel pivots medially towards the midline of his body.  Some sources (Michaud) call this an Abductory Twist, but the reference there is typically the forefoot.  Regardless, to help our patients, we sometimes refer to this is “cigarette butt” foot. It is like stepping on a lit cigarette to put it out via twisting/grinding it into the ground. 

So, now that you can see this, what causes it? 

The answer is broad but in this case he had a loss of ankle dorsiflexion range.  The ankle mortise clearly did not have enough of ankle rocker range during midstance so as that limitation was met, the heel raised up prematurely during the moments when the opposite leg is in full swing imparting an external rotation on the stance limb (hence the external foot spin (adducting heel/abducting foot……depending on your visual reference)). There is a bit more to it than that, but that will suffice for now because it is not the central focus of our lesson today.

What can cause this ? As we said, a broad range of things:

  • hallux limitus
  • flexion contracture of the knee (swelling, pain, joint replacement etc)
  • short calf-achilles complex
  • weak tib anterior and extensor toe muscles
  • Foot Baller’s ankle
  • limited/impaired hip extension
  • weak glute (minimizing hip extension range)
  • sway back (lower crossed syndrome-type biomechanics)
  • short quadriceps (similarly impairing hip extension)
  • flip flop excessive use (or any other motor strategy that imparts more flexor compartment dominance (read: calf-achilles, FDL)
  • excessive pronation
  • impaired foot tripod mechanics
  • etc

The point is that anything impairing TIMELY (the key word is timely) forward sagittal gait mechanics can, and very likely will, impair ankle rocker.  Even the wrong shoe choice can do this (ie. someone who suddenly drops from a 12 mm heel ramped shoe into a 0-4mm ramped heel shoe and who thus may not have earned the length of the calf-achilles complex as of yet).

The abductor-adductor twist phenomenon is not a normal visual gait observation. It is a softly seen, but screaming loud, pathologic gait motor pattern that must be recognized.  But, more importantly, the source of the problem must be found, confirmed and resolved.  In this fella’s case, he has some weakness of the tib anterior and extensor toe muscles that has lead to compensatory tightness of the calf complex. There was no impairment of the glutes or hip extension, as this was just 2 weeks old or so, but if left unaddressed much longer the CNS would have likely begun to dump out of hip extension and gluteal function to protect……another compensation pattern. Remember, ankle rocker and hip extension have a close eye on each other during gait.

Clinical pearl for the true gait geeks…… if you see someone with a vertically bouncy forefoot-type gait (you know, those people that bounce up and down the hallway at work or school) you can usually suspect impaired ankle rocker and if you look closely, you will usually see a quick abductor-adductor twist.

Shawn and Ivo

the gait guys

Podcast 73: Cross Fit and Squatting. Knees out ?

Podcast 73: Femoral and Tibial Torsions and Squatting: Know your Squatting Truths and Myths

*Show sponsor: www.newbalancechicago.com

Lems Shoes.  www.lemsshoes.comMention GAIT15 at check out for a 15% discount through August 31st, 2014.

A. Link to our server: http://traffic.libsyn.com/thegaitguys/pod_74f.mp3

Direct Download: 

http://thegaitguys.libsyn.com/podcast-73-cross-fit-squatting-knees-b. out

iTunes link:

https://itunes.apple.com/us/podcast/the-gait-guys-podcast/id559864138

C. Gait Guys online /download store (National Shoe Fit Certification and more !) :

http://store.payloadz.com/results/results.aspx?m=80204

D. other web based Gait Guys lectures:

www.onlinece.com   type in Dr. Waerlop or Dr. Allen,  ”Biomechanics”

______________

Today’s Show notes:

1. Bioengineers create functional 3D brain-like tissue   http://www.nih.gov/news/health/aug2014/nibib-11.htm

2.  A Novel Shear Reduction Insole Effect on the Thermal Response to Walking Stress, Balance, and Gait
 
3.  Hi Shawn and Ivo, There is a lively debate in the Crossfit community about “knees out” during squatting. I have attached a blog post. It might be a good blog post or podcast segment. 
 
4. Shoe Finder ?
 
5.  Michael wrote: “I know this is too broad a topic for facebook, but I was wondering what your general recommendation would be for someone with flat feet and exaggerated, constant over-pronation. I’ve tried strengthening my calves and ankles, but have seen no noticeable reduction in the automatic “rolling in” of my feet whenever walking or standing. I can consciously correct the over-pronation, of course, but as soon as I stop tensing my arch muscle, everything flops back down.”

How do you measure tibial torsion anyway?

With all the talk on the Crossfit blog about the knees out debate, we though we would shed some light on measuring torsions, beginning with tibial torsion, since this does not seem to have been taken account of in the discussion and we feel it is germane. 

Yo may have seen some of our other posts in tibial torsion here or here; this post will serve to help you measure it. 

Looking at the top left picture: we can see that the axis of the tibial plateau and the transmalleolar axis (an imaginary line drawn through the medial and lateral malleolus) are parallel at birth (net angle zero) and progress to 22 degrees at skeletal maturity, resulting from the outward rotation of the tibia of about 1-1.5 degrees per year. This results in a normal external tibial version of about 17-18 degrees (you subtract 5 degrees for the talar neck angle, talked about in the link above). Note that this is the normal or ideal angle we would expect (hope?) to see. Go 2 standard deviations in either direction and we have external and internal tibial torsions.

You can go about taking this measurement in may ways; we will outline 2 of them. 

  1. In the upper left picture, we see an individual who has their knee flexed to 90 degrees over the side of a table while seated. This represents the tibial plateau angle. You the use a protractor to measure the angle between the tibial plateau and an imaginary line drawn through the medial and lateral malleoli. This is the transmalleolar angle. You then subtract 5 degrees from this number (remember the talar neck angle?) to get the angle of tibial version (or torsion).
  2. In the lower left and right pictures, we have the patient supine with the knees pointed upward and tibial plateau flat on the table. Then, working from inferiorly, use a goniometer to measure the angle of the transmalleolar axis. Again, we subtract 5 degrees for the talar neck.

We would encourage you to read up on torsions. This post, which we wrote over a year ago, is probably one of the most important ones on tibial torsions. 

Torsions. Important stuff, especially when you are talking about the axis of the knees in activities like a squat. Remember, the knee is a hinge between 2 multiaxial joints (hip and ankle) and will often take the brunt of the (patho)mechanics, as it has fewer degrees of freedom of movement. If you have external tibial torsion and you push your knees (angle your feet) out further, you are moving the knees outside the saggital plane. You have better have a very competent medial tripod! If you have internal tibial torsion, angling the feet out may be a good idea. Know your (or your patients/clients/athletes) anatomy!

The Gait Guys. Bald, Good Looking and Twisted. Here to help you navigate your way through better biomechanics. 

Podcast 72: Neuroplasticity, EVA Shoe Foam, and Shoe Trends

Maximalist shoes and the death of Minimalism ? Could this be true ?

*Show sponsor: www.newbalancechicago.com

Lems Shoes.  www.lemsshoes.comMention GAIT15 at check out for a 15% discount through August 31st, 2014.

A. Link to our server: 

http://traffic.libsyn.com/thegaitguys/pod_73f.mp3

Direct Download: 

http://thegaitguys.libsyn.com/podcast-72

B. iTunes link:

https://itunes.apple.com/us/podcast/the-gait-guys-podcast/id559864138

C. Gait Guys online /download store (National Shoe Fit Certification and more !) :

http://store.payloadz.com/results/results.aspx?m=80204

D. other web based Gait Guys lectures:

www.onlinece.com   type in Dr. Waerlop or Dr. Allen,  ”Biomechanics”

______________

Today’s Show notes:

1. Neuroplasticity: Your Brain’s Amazing Ability to Form New Habits
new link (does not have the old photo ivo mentioned that he loved)
 
2. Last week we pounded the sand on EVA foam and maximalist shoes. There was alot of attention, emails and good social media discussion on the topic.  
LETS REVIEW IT
file:///Users/admin/Downloads/p142_Heel_shoe_interactions_and_EVA_foam_f_web_150dpi.pdf
 
3. Then there just last week there was an article in LER on “the death of minimalist shoes” ? 
READ THIS: 
The rise and fall of minimalist footwear | Lower Extremity Review Magazine
http://lermagazine.com/cover_story/the-rise-and-fall-of-minimalist-footwear
 

4.  Physical Therapy as Effective as Surgery for Meniscal Tear

Kathleen Louden

March 20, 2013
Torn Meniscus? Thinking about surgery? Think again…


5. Cast study: the broken foot tripod

Podcast 72: Neuroplasticity, EVA Shoe Foam, and Shoe Trends

Maximalist shoes and the death of Minimalism ? Could this be true ?

*Show sponsor: www.newbalancechicago.com

Lems Shoes.  www.lemsshoes.comMention GAIT15 at check out for a 15% discount through August 31st, 2014.

A. Link to our server: 

http://traffic.libsyn.com/thegaitguys/pod_73f.mp3

Direct Download: 

http://thegaitguys.libsyn.com/podcast-72

B. iTunes link:

https://itunes.apple.com/us/podcast/the-gait-guys-podcast/id559864138

C. Gait Guys online /download store (National Shoe Fit Certification and more !) :

http://store.payloadz.com/results/results.aspx?m=80204

D. other web based Gait Guys lectures:

www.onlinece.com   type in Dr. Waerlop or Dr. Allen,  ”Biomechanics”

______________

Today’s Show notes:

1. Neuroplasticity: Your Brain’s Amazing Ability to Form New Habits
new link (does not have the old photo ivo mentioned that he loved)
 
2. Last week we pounded the sand on EVA foam and maximalist shoes. There was alot of attention, emails and good social media discussion on the topic.  
LETS REVIEW IT
file:///Users/admin/Downloads/p142_Heel_shoe_interactions_and_EVA_foam_f_web_150dpi.pdf
 
3. Then there just last week there was an article in LER on “the death of minimalist shoes” ? 
READ THIS: 
The rise and fall of minimalist footwear | Lower Extremity Review Magazine
http://lermagazine.com/cover_story/the-rise-and-fall-of-minimalist-footwear
 

4.  Physical Therapy as Effective as Surgery for Meniscal Tear

Kathleen Louden

March 20, 2013
Torn Meniscus? Thinking about surgery? Think again…


5. Cast study: the broken foot tripod

Proprioceptive afferent inputs can control the timing and pattern of locomotion. When disease is present, or when injury has compromised the neuro-biomechanical linkages, slow postural responses can trump what timely responses are necessary to ensure for smooth locomotion.
 
When many people think of balance and locomotion, the cerebellum is often a top topic for it is important for movement control and plays a particularly crucial role. Thus, a most characteristic sign of cerebellar damage is walking ataxia. It is not known how the cerebellum normally contributes to walking, although recent work suggests that it plays a role in the generation of appropriate patterns of limb movements, dynamic regulation of balance, and adaptation of posture and locomotion through practice. (1)
Reflex pathways exist which regulate the timing of the transition from stance to swing, and control the magnitude of ongoing motoneuronal activity. During locomotion there is a closely regulated feedback from the various sensory receptors in the skin, joints, muscles, tendons, ligaments and other tissues, this is referred to as afferent feedback. When there is damage to these sensory “organs”, or the pathways into, or out of, the central nervous system locomotion becomes difficult.  We can see this in the video case above. This is a case of Chronic Inflammatory Demyelinating Polyradiculopathy (CIDP). It is an immunne-mediated inflammatory disorder of the peripheral nervous system whereby the myelin sheath of neurons is slowly eroded and as a result, the affected nerves and pathways fail to respond well rendering numbness, paresthesias, pain and progressive muscle weakness along with loss of deep tendon refexes. Obviously this will render locomotion fatiguing and difficult. Falls are not uncommon as you can see in the video.
 
Timing and coordination is everything in gait. When a portion of the system is compromised from injury or neurologic deficit, locomotion becomes strained.  There is an intricate balance between the extensor and flexor muscles.  We found this quote by Lam and Pearson particularly relevant to today’s discussion and video.

“Proprioceptive feedback from extensor muscles during the stance phase ensures that the leg does not go into swing when loaded and that the magnitude of extensor activity is adequate for support. Proprioceptive feedback from flexor muscles towards the end of the stance phase facilitates the initiation of the swing phase of walking. Evidence that muscle afferent feedback also contributes to the magnitude and duration of flexor activity during the swing phase has been demonstrated recently. The regulation of the magnitude and duration of extensor and flexor activity during locomotion is mediated by monosynaptic, disynaptic, and polysynaptic muscle afferent pathways in the spinal cord. In addition to allowing for rapid adaptation in motor output during walking, afferent feedback from muscle proprioceptors is also involved in longer-term adaptations in response to changes in the biomechanical or neuromuscular properties of the walking system.” (2)

Gait and any form of locomotion are highly complicated with many pieces necessary to achieve clean, smooth, coordinated motion.  Failure in only one piece of the puzzle can result in profound unhinging of the entire system because of the entangled nature of the feedback loops.  
Nothing dramatic today gang, just some thoughts that came to us after seeing this client and doing some reading to keep up on things.  We thought this would be a nice follow up to Monday’ blog post on proprioception.
Shawn and Ivo
the gait guys
References:
1. Neuroscientist. 2004 Jun;10(3):247-59.

Cerebellar control of balance and locomotion.

2. Adv Exp Med Biol. 2002;508:343-55.

The role of proprioceptive feedback in the regulation and adaptation of locomotor activity. Lam T1, Pearson KG.

Proprioception trumps Biomechanics

As I sit here on a rare Friday afternoon, not working (OK, I am writing this, so sort of working) and looking out at the lake (picture above), while on a family camping trip, I think about a walk on the rocks this morning with my kids. I was watching my very skilled 7 year old jump from rock to rock while my 3 1/2 year old, that thinks he is seven, tried to follow his older brother.

I had my foot on a rock which lowered the front of my foot in plantar flexion and stood on that leg. I noticed that my balance was not as great as it was when my foot was in dorsiflexion. This made me think about pronation and supination. Yes, it is not uncommon for me to think about such things, especially when I have some spare time. That is one of the things about being a foot and gait nerd; these sorts of things are always on our minds.

So, why was my balance off? Did I need more proprioceptive work? Were my foot intrinsics having issues? No, it was something much more mundane.

Pronation consists of dorsiflexion, eversion and abduction. This places the foot in a  “mobile adaptor” posture, reminiscent of our hunter/gatherer ancestors, who needed to adapt to uneven surfaces while walking over terra firma barefoot. Supination, on the other hand (which is the position my foot was in), consists of plantarflexion, inversion and adduction. It places the foot (particularly the midtarsals) in a locked position for propulsion (think of the foot position during toe off).

So why when my foot was plantar flexed and adducted while standing on this rock so much more unstable in this supposedly more stable, supinated position? I would encourage you, at this point, to try this so you can see what I mean. When I placed my foot in dorsiflexion on the rock, I was much more stable. A most interesting conundrum for a biomechanist.

Experimenting for a few minutes, alternating plantar flexion and dorsi flexion, gave me the answer. When we are walking on the flats, our foot is (usually) not pushed to the extremes of dorsiflexion; with the front of the foot up on a rock, it is much more so. This “extra” upward force on the front of the foot, provides much more sensory input (and thus proprioception) from the ball of the feet. Take a look at the sensory homunculus and you can see how much brain real estate is dedicated to your foot, especially the front portion. With this information, we are able to apply more  force through the posterior compartment of the leg,which is stronger than my anterior compartment (as it is with most folks).

When the front of your foot is in plantar flexion (ie, your heel is on the rock), we have less sensory input to the balls of the feet, and rely more on the anterior compartment (weaker in many folks, including myself) to counterbalance the weight of our body.

Mystery solved: proprioception trumps biomechanics; more proof that the brain is smarter than we are.

The Gait Guys. Solving the worlds great gait questions, one at a time.

Did you see this in our recent blog post here ? a reader made us look closer. Did you catch it ?
The clients right foot appears to have a dropped 1st met head. (we hate this term, because it is not accurate and is a sloppy clinical description). In this still photo it appears plantarflexed.  But in this video, consider the descended 1st met head as due to the disuse or weakness of the EHL muscle (extensor hallucis longus) of the 1st toe. Or, is this in fact a compensated forefoot varus ? Sure looks like it. But with all that anterior compartment weakness (as we discussed in the previous blog post link above) it could just be a mirage. In the photo above, in a normal foot the rearfoot plane (greenline) should parallel the forefoot line (orange line). In this case, in this actively postured foot (thus some inaccuracy here, we are merely making a teaching point from the photo) the upslope of the orange line suggests a forefoot varus. This would be true if the first Metatarsal head also was on this line, but you can see that it has its own idea. This represents, in theory (regarding this photo), a compensated forefoot varus. But remember, this client is  holding the foot actively in this posture. A true hands on assessment is needed to truly define a Forefoot varus, and whether it is anatomic, flexible, rigid or in many cases, just a learned functional posturing from weakness of the flexor/extensor pairing of the 1st metatarsal complex or from other weaknesses of the other forefoot evertors.  It gets complicated as you can see.

As always, knowledge of the anatomy and functional anatomy allows for observation, and observation leads to understanding, which leads to answers and then remedy implementation. Our thoughts, knowing the case, is that this is a functional appearance illusion of a compensated forefoot varus due to the EHL, EDL and tibialis anterior weakness (anterior compartment) and how they play together with the flexors. One must be sure to assess the EHL when examining the foot. Test all of the muscles one by one.  We have been talking about toe extensors for a long time, they can be a paramount steering wheel for the forefoot and arch posture. Podcast 71 talks about this Forefoot varus, and you should care.
In a 2009 study by Reynard et al they concluded: 

  • “The activity of extensor digitorum longus muscle during the swing phase of gait is important to balance the foot in the frontal plane. The activation of that muscle should be included in rehabilitation programs.” (1)

here is the video again.

Have a burning desire to learn more about forefoot varus, here are 25 blog post links from our last few years. And/or you can take our National Shoe Fit program (downloadable links below).

Knowing what you are seeing during your exam and gait analysis can only truly come from coupling your observations with a clinical exam.  Anything less is speculation and guess work.  It is gambling, and this is not Vegas baby, this is someone’s health.

Shawn and Ivo, The Gait Guys

________________

National Shoe Fit Certification Program:

Gait Guys online /download store (National Shoe Fit Certification and more !) :

http://store.payloadz.com/results/results.aspx?m=80204

1. Foot (Edinb). 2009 Jun;19(2):69-74. Epub 2008 Dec 31. Foot varus in stroke patients: muscular activity of extensor digitorum longus during the swing phase of gait.  Reynard F, Dériaz O, Bergeau J.

Other web based Gait Guys lectures:

www.onlinece.com   type in Dr. Waerlop or Dr. Allen,  ”Biomechanics”Reference

Podcast 71: Forefoot Varus, Big Toe Problems & Charlie Horses”

*Show sponsor: www.newbalancechicago.com

Lems Shoes.  www.lemsshoes.comMention GAIT15 at check out for a 15% discount through August 31st, 2014.

A. Link to our server: 

Direct Download: 

http://traffic.libsyn.com/thegaitguys/pod_72final.mp3

Permalink: http://thegaitguys.libsyn.com/podcast-71

B. iTunes link:

https://itunes.apple.com/us/podcast/the-gait-guys-podcast/id559864138

C. Gait Guys online /download store (National Shoe Fit Certification and more !) :

http://store.payloadz.com/results/results.aspx?m=80204

D. other web based Gait Guys lectures:

www.onlinece.com   type in Dr. Waerlop or Dr. Allen,  ”Biomechanics”

______________

Today’s Show notes:

1. American College of Cardiology. Running out your healthy heart. How much exercise is too much ?

Running for 7 minutes a day cuts risk of death by 30%, study says
http://wgntv.com/2014/07/29/running-for-7-minutes-a-day-cuts-risk-of-death-by-30-study-says/
 
2. The history of “Charlie Horses”
 
3. A runner with strange shin bruises.  
from : Joy 

Hi, I’m a great follower of your blog – fascinating stuff! I was wondering if I could ask you a quick question as nobody I’ve spoken to has been able to help:

I’ve been getting bruises that appear on my shin during running. They don’t hurt, I’m just wary of ignoring what could be a warning sign. Have you ever come across this before? (It’s mainly the spot where I had a tibial stress fracture last year, but I also get a few other apparently spontaneous bruises on my lower legs.)

4. Is that a forefoot varus or are you just happy to see me ?
Functional vs Anatomic vs. Compensated forefoot varus foot postures. A loose discussion.
5. A reader’s pet peeve about shoe store “gait analysis”.
6. Thoughts on pronation and the like.
7. Case study:  First toe fusion and implications long and short term.
“I had a patient today with an MTP fusion of his great toe after adverse complications from a bunionectomy.  Do you have any recommendations for gait training when great toe dorsiflexion is no longer an option?  He is currently compensating by externally rotating his foot and overpronating.  I’m thinking through it and  I know he has to gain the motion elsewhere to help normalize his gait as much as possible, so possibly gaining ankle dorsiflexion and hip extension.  Just wondering if you have any tips to share or articles to point me to for further ideas.  Continuing my research now.  I’m a relatively new grad and this is my first patient I’m seeing with this fusion. Many thanks