Get your foot in High Gear!

image source: Foot Orthoses and Other Conservative Forms of Foot Care. Michaud 1997; Williams an Wilkins: with permission

When it comes to gait, getting the 1st ray to the ground is the name of the game. When weight travels through the medial forefoot and we are able to push off the 1st ray complex, that is called "high gear push off". This was 1st discussed F Bojsen-Møller in this excellent paper (1), that just happens to be a free full text! Craig Payne, The Running Research Junkie has offered and excellent commentary on the topic here as well.

High Gear Push Off can happen when 3 conditions are met: 

1. we have a intact visual, vestibular and kinesthetic systems that ensure we can remain upright in the gravitational plane.
2. we have an intact calcanocuboid locking mechanism
3. we have adequate skill, endurance and strength of our extensor hallucis brevis

The 1st condition is more global and ensures that our cerebellum and vestibular apparatus are playing nice together to create balance, of the literal sort, We seek to keep our visual axes parallel and our center of gravity over our foot. Remember that the BODY will move itself AROUND the visual axes. If the axes are off, the brain will tilt the head and the body will move AROUND the head to accommodate. We have talked about that in these posts here on the blog. 

The 2nd condition, the calcaneo-cuboid locking mechanism, works in the coronal plane and relies on a functioning peroneal group, where the peroneus longus and brevis wrap around the lateral malleolus, cuboid and tail of the 5th metatarsal, crossing the foot diagonally to insert on the base of the 1st metatarsal. When working properly, its actions will be to plantar flex and everting the forefoot, lowering the 1st ray complex down and assisting the shift of the center of gravity more medial for the weight to pass through the medial foot and out through the hallux (ideally). 

The 3rd condition, the ability to descend the 1st ray, relies on the actions of the peroneus, appropriate supination of the forefoot and ability of the extensor hallucis brevis to do its job.  Because the tendon travels behind the axis of rotation of the 1st metatarsal phalangeal joint, in addition to providing extension of the proximal phalynx of the hallux, it can also provide a downward moment on the distal 1st metatarsal (when properly coupled to and temporally sequenced with the flexor hallicus brevis and longus). If the axis of motion for the 1st metatarsal phalangeal joint moves posteriorly, to behind (rather than under) the joint, the plantar pressures increase at MTP’s 4-5 and decrease at the medial mid foot, moving you into low gear push off.  If moved even further posteriorly, the plantar pressures, and contact time in the mid foot and hind foot (2). For more on the extensor hallucis brevis, see our post here.

As you can see, high gear is desirable over low gear push off, but sometimes circumstances or biomechanics do not permit. High gear push off ensures the forefoot is dorsiflexed and everted with respect to the rearfoot and the calcaneocuboid and talonavicular joint axes are perpendicular to one another, giving us a rigid lever to push off of as the center of gravity moves medially across the foot. In low gear push off, the foot is inverted and plantarflexed and the stress falls on the lesser metatarsals and lateral stabilizing complex of the ankle, moving the center of gravity laterally, in addition to the calcaneocuboid and subtalar joint axes being more parallel,  creating a less rigid lever for push off and decreased mechanical efficiency.

1. Calcaneocuboid joint and stability of the longitudinal arch of the foot at high and low gear push off. J Anat. 1979 Aug; 129(Pt 1): 165–176.  link to free full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1233091/

2. van der Zwaard BC1, Vanwanseele B, Holtkamp F, van der Horst HE, Elders PJ, Menz HB Variation in the location of the shoe sole flexion point influences plantar loading patterns during gait. J Foot Ankle Res. 2014 Mar 19;7(1):20.

Too much extensor tone: The banana toe.

Too much extensor tone.
We are often talking about the subtle balanced relationship of the long and short toe flexors and extensors. We often discuss that hammer toes are too much long flexor and short extensor tone (with too little in the short flexor and long extensor).
Here we see the opposite. We see too much long extensor tone (note the upward banana-shaped orientation of the big toe). When this foot is on the ground, the pad and distal 1/2 of the big toe does not even touch the ground, standing or in gait. IF you look closely at the blown up pic, you can sort of see (sorry, should have taken more pics) the increased callus development in the contact area of the short flexor attachment (FHB, flexor hallucis brevis).

This relationship is the opposite of the above with hammer toes. Too much long extensor, too much short flexor, and not enough long flexor and short extensor. These clients need more homework for long flexor and short extensor. This is one of the reasons why we developed the exercise below in the youtube link.

One way to correct an dysfunctional Extensor Hallucis Brevis

The Extensor Hallicus Brevis, or EHB  (beautifully pictured above causing the  extension (dorsiflexion) of the proximal big to is an important muscle for descending the distal aspect of the 1st ray complex (1st metatarsal and medial cunieform) as well as extending the 1st metatarsophalangeal joint.

Since this muscle is frequently dysfunctional, and is one of THE muscles than can lower the head of the 1st metatarsal, along with the peroneus longus and most likely the tibialis posterior (through its attachment to the 1st or medial cunieform), needling can often assist in normalizing function and works especially well, when coupled with an appropriate rehab program. Here is one way to needle it effectively. 

The Banana Toe: The Force has to go somewhere. It’s a Jedi Gait Rule.

* note: there are 4 photos to today’s blog post. Be sure you click through all 4.

When you toe off, you have to toe off from somewhere in the foot unless you like an apropulsive hip flexion gait, where  you just lift you foot off the ground from foot flat, kind of like a true neurologic “foot drop” gait client would.  But, if you are lucky enough not to have a true foot drop, you are going to push off somewhere in the foot.  You can do it off the lateral foot (low gear toe off) and lesser toes, or you can do it off the big toe (high gear) the way we were built to do it. 

The above pictures show a nasty dorsal crown of osteophytes that is limiting hallux (big toe) extension/dorsiflexion. This is true hallus rigidus and hallux limitus. When this client attempts to toe off, the joint cannot normally partake in the activity, there is no Windlass effect, no posturing up over the sesamoids for mechanical advantage etc.   

In this scenario, there are two places you can put it, up into the next proximal joint(s) meaning the met-cuneiform joint or further down into the interphalangeal joint. In other words. the loads go proximal or distal to the limited joint, and they eventually play out there, over and over and over gain. The former option would basically mean you are pronating/dorsiflexing through the midfoot which is never good (can you say Saddle exostosis ! ouch !) or the latter option is to dorsiflex through the interphalangeal joint  and over time that toe begins to attenuate plantar ligamentous structures and extend beyond its normal limits resulting in the “Chiquita” toe (a upward bent toe resembling a banana shape). This will disable the long flexor of the great toe (FHL: flexor hallucis longus).and inhibit mechanical advantage of the extensor digitorum brevis.  If you struggle with the “how and why” behind this sentence in terms of restoration attempts, you need to watch my video here. It will offer you deeper insights.

Will this toe become painful ? yes, in time it is quite possible.  Is there much you can do? Sure, a rocker bottomed shoe will help take the load at toe off instead of forcing it into this toe or the midfoot.  Will an orthotic  help ? Well, this is a loaded question. If you are putting the forces into the midfoot choice as described above, the orthotic will block that motion and you will likely default option into the toe presentation above. So you are merely just moving loading forces around. It can be helpful, but you are quite possibly “robbing Peter to pay Paul” as they say.  The video I asked you to watch can be helpful but it will force that metatarsophalangeal joint into extension, a range it does not have, so it is not a remedy and not recommended.  Perhaps some awareness and slight increase in FHL(long toe flexor) use can be attained however.  These are tricky cases, simple in theory, but execution can be fussy and requires patient awareness and education. We like the rocker bottomed shoe as a nice easy solution and some increased FHL use awareness.  Help them find a little more FHL use by putting a pencil under the crease of the toe and help them to drive the tip of the toe down just a little out of that banana extension posture. It can help them control the overloading of the dorsal aspect of the interphalangeal joint.

As always, lets carry this forward into gait thoughts.  How is  hip extension going to be in this client ? How is glute strength ? Hip joint range ? Hip extension motor patterning ? Will the client go into anterior pelvic tilt to borrow the last range of hip extension ? Will the hamstrings have to accommodate ? Lots of yummy biomechanical and neurological mental gymnastics here. Bottom line answer to all the above ?  “ it depends, they will have to accommodate and compensate”.  And as the Jedi Gait Rule goes, “the Force as to go somewhere”.

Shawn Allen, one of the gait guys

When the big guy heads medially….Game Changer

Lately we have been seeing a lot of bunions (hallux valgus). While doing some research on intermetatarsal angles (that’s for another post) we came across the nifty diagram you see above. 

Regardless of the cause, as the 1st metatarsal moves medially, there are biomechanical consequences. Lets look at each in turn. 

• the EHB (extensor hallucis brevis) axis shifts medially. this muscle, normally an extensor of the proximal phalanyx, now becomes more of an abductor of the hallux. It’s secondary action of assisting the descent of the head of the 1st metatarsal no longer happens and it actually moves the base of the proximal phalanyx posteriorly, altering the axis of centration of the joint, contributing to a lack of dorsiflexion of the joint and a hallux limitus
• Abductor hallucis becomes more of a flexor, as it moves to the plantar surface of the foot. Remember, a large percentage of people already have this muscle inserting more on the plantar surface of the foot (along with the medial aspect of the flexor hallucis brevis), so in these folks, it moves even more laterally, distorting the proximal phalanx along its long axis (ie medially) see this post here for more info
• Flexor hallucis brevis moves more laterally. Remember this muscle houses the sesamoid bones before inserting onto the base of the proximal phalannx; the medial blending with the abductor hallucis and the lateral with the adductor hallucis. Because the sesamoid bones have moved laterally, they no longer afford this muscle the mechanical advantage they did previously and the axis of motion of the 1st metatarsal phalangeal joint moves dorsally and posterior, contributing to limited dorsiflexion of that joint and a resultant hallux limitis. The lateral movement of the sesamoids also tips the long axis of the 1st metatarsal and proximal phalanyx into eversion. In addition, the metatarsal head is exposed and is subject to the ground reactive forces normally tranmittted through the sesamoids; often leading to metatarsalgia. 
• Adductor hallucis: this muscle now has a greater mechanical advantage  and because the head of the 1st ray is not anchored, acts to abduct the hallux to a greater degree. The now everted position of the hallux contributes to this as well

As you can see, there is more to the whole than the sum of the parts. Bunions have many biomechanical consequences, and these are only a small part of the big picture. Take you time, learn your anatomy and examine everything that has a foot!

See you in the shoe isle…

Ivo and Shawn

pictures from: http://www.orthobullets.com/foot-and-ankle/7008/hallux-valgus and http://www.stepbystepfootcare.com/faqs/nakedfeet/

Welcome to Rewind Friday, Folks. Today we review the importance of the great toe extensor. Enjoy!

Gait Topic: The Mighty EHB (The Short extensor of the big toe, do not dismiss it !)

Look at this beautiful muscle in a foot that has not yet been exposed to hard planar surfaces and shoes that limit or alter motion! (2 pics above, toggle back and forth)

The Extensor Hallicus Brevis, or EHB as we fondly call it (beautifully pictured above causing the  extension (dorsiflexion) of the child’s proximal big toe) is an important muscle for descending the distal aspect of the 1st ray complex (1st metatarsal and medial cunieform) as well as extending the 1st metatarsophalangeal joint. It is in part responsible for affixing the medial tripod of the foot to the ground.  Its motion is generally triplanar, with the position being 45 degrees from the saggital (midline) plane and 45 degrees from the frontal (coronal) plane, angled medially, which places it almost parallel with the transverse plane. With pronation, it is believed to favor adduction (reference). Did you ever watch our video from 2 years ago ? If not, here it is, you will see good EHB demo and function in this video. click here

It arises from the anterior calcaneus and inserts on the dorsal aspect of the proximal phalynx. It is that quarter dollar sized fleshy protruding, mass on the lateral aspect of the dorsal foot.  The EHB is the upper part of that mass. It is innervated by the lateral portion of one of the terminal branches of the deep peronel nerve (S1, S2), which happens to be the same as the extensor digitorum brevis (EDB), which is why some sources believe it is actually the medial part of that muscle. It appears to fire from loading response to nearly toe off, just like the EDB; another reason it may phylogenetically represent an extension of the same muscle.

*The EDB and EHB are quite frequently damaged during inversion sprains but few seem to ever look to assess it, largely out of ignorance. We had a young runner this past year who had clearly torn just the EHB and could not engage it at all. He was being treated for lateral ankle ligament injury when clearly the problem was the EHB, the lateral ligamentous system had healed fine and this residual was his chief problem.  Thankfully we got the case on film so we will present this one soon for you !  In chronic cases we have been known to take xrays on a non-standard tangential view (local radiographic clinics hate us, but learn alot from our creativity) to demonstrate small bony avulsion fragments proving its damage in unresolving chronic ankle sprains not to mention small myositis ossificans deposits within the muscle mass proper.

Because the tendon travels behind the axis of rotation of the 1st metatarsal phalangeal joint, in addition to providing extension of the proximal phalynx of the hallux (as seen in the child above), it can also provide a downward moment on the distal 1st metatarsal (when properly coupled to and temporally sequenced with the flexor hallicus brevis and longus), assisting in formation of the foot tripod we have all come to love (the head of the 1st met, the head of the 5th met and the calcaneus).

Wow, all that from a little muscle on the dorsum of the foot.

The Gait Guys. Definitive Foot Geeks. We are the kind of people your podiatrist warned you about…

Lebron James and his funky toes. We have the scoop as to what is going on.

http://bleacherreport.com/articles/1757693-everybody-look-at-lebron-james-toes

This is what happens when you get too much short extensor tone and/or strength in the digits of the foot.  Now this is his trailing foot and he has moved into toe off so he should be activating his toe extensors and the tibialis anterior (ie. the anterior compartment) to create clearance for that foot so that he doesn’t catch the toes on the swing through phase of gait.  In this case we do not see alot of ankle dorsiflexion (which we should see at this point) so we are  seeing a compensation of perhaps increased short extensor (of the toes) activity.  

We also see what appears to be a drifting of the big toe (the hallux) underneath the 2nd toe. This often happens when a bunion or hallux valgus is present.  Now we do not see a bunion present here but the viewing angle is not optimal however it does appear that there is a slight drift of the hallux big toe towards the lesser toes . We are not sure if we would qualify this as hallux valgus, and if so it is mild, but none the less we see a slight lateral drift. What is interesting is that despite the obvious activity of the lesser toes short extensor muscle (EDB) we do not see a simultaneous activity of the short extensor of the hallux (EHB, extensor hallucis brevis). Does he need to do our exercise ? See video link here ! 

And so, when the lesser toes are in extension as we see here and the big toe is not moving into extension, and when that is simultaneously combined with even a little hallux valgus tendency, the big toe will drift underneath the lesser toes as we see here, even appearing to push the 2nd toe further into extension.  

As for his little toe, well, Dr. Allen  has one just like it so perhaps he missed his calling in the NBA. Some folks just do not have as plantarward orientation of the 5th toe and so it migrates upward (dorsally) a little. This can be from birth but it can also come from trauma. But in time because the toe is not more plantar oriented, the dorsal muscles (the extensors) become more dominant and the toe just starts to take on this kind of appearance and orientation. It will reduce significantly when the foot is on the ground and the extensors are turned off, but it looks more shocking during the swing phase because of the extensor dominance in that phase.

This kind of presentation if left unchecked can lead to hammer toes, plantar fat pad migration distally exposing the metatarsal heads to more plantar forces without protection and a host of other problems.  Lebron needs to do our Shuffle Walk Exercise to get more ankle rocker (dorsiflexion) and also work to increase his long toe extensors (EDL) and lumbricals.  This will flatten his toes and improve mechanical leverage.  Remember, if you gait better foot function with increased ankle dorsiflexion you will get more hip extension and more glute function.  But does the big fella really need to jump any higher? We are sure he would accept being faster though … .  who wouldn’t ?

Fee for today’s long distance consult: …  Lebron, lets say 10,000$ and we will call it even.  Sound good ?  But a lifetime of prettier, stronger and more functional toes……priceless. Have  your people contact our people.  (Ok, we don’t have people, but we do have an email address here on our blog !).

Shawn and Ivo, The Gait Guys.  Even helping the elite, little by little.

EHB: Extensor Hallucis Brevis

Did you know that the EHB (extensor hallucis brevis) the topic of today’s video tutorial, originates off of the forepart of the medial aspect of calcaneus & lateral talocalcaneal ligament. It is just above the bulk origin of the EDB (extensor digitorum brevis). It is frequently torn/strained in ankle inversion sprains and frequently goes undiagnosed. It can be torn/avulsed from the bone if the inversion sprain is focused below the lateral ankle joint. This occurs mostly when the foot is more plantarflexed before the inversion event. A foot cannot afford to have an impaired big toe ! Don’t miss this one !

Big Toe Exercise: Regaining Control of the Extensor Hallucis Brevis.

Exercise Anyone?

Here Dr Ivo briefly talks about the 1st part of the famous “Extensor Hallucis Brevis” or “EHB” exercise (Part 1) with a patient. More of this to follow after we launch the shoe program (yes, we know, it has been a long time coming. We would have had it out earlier had our site not been hacked). We plan on a foot muscle testing and Exercise DVD this winter.

Special thanks to our patient or letting us use the footage, and his wife to film the clip!

Ivo and Shawn