Exploring the Links Between Human Movement, Biomechanics & Gait
and what have we been saying about loss of ankle rocker and achilles tendon problems for years now?
Here is a FREE, FULL TEXT article talking all about it
“A more limited ankle Dorsi Flexion ROM as measured in Non Weight Bearing with the knee bent increases the risk of developing Achilles Tendinopathy among military recruits taking part in intensive physical training.”
J Foot Ankle Res. 2014 Nov 18;7(1):48. doi: 10.1186/s13047-014-0048-3. eCollection 2014.Limited ankle dorsiflexion increases the risk for mid-portion Achilles tendinopathy in infantry recruits: a prospective cohort study.Rabin A1, Kozol Z, Finestone AS.
Wow! Can you figure out why this person at the distal end of her first metatarsal under her medial sesamoid.
She recently underwent surgery for a broken fibula (distal with plate fixation) and microfracrure of the medial malleolus. You are looking at her full range of dorsiflexion which is improved from approximately 20° plantarflexion. She is now at just under 5°.
She has just begun weight-bearing and developed pain over the medial sesamoid.
The three rockers, depicted above from Thomas Michauds book, or necessary for normal gait. This patient clearly has a loss of ankle rocker. Because of this loss her foot will cantilever forward and put pressure on the head of the first metatarsal. This is resulting in excessive forefoot rocker. Her other option would have been to pronate through the midfoot. Hers is relatively rigid so, as Dr. Allen likes to say, the “buck was passed to the next joint. ”
There needs to be harmony in the foot in that includes each rocker working independently and with in its normal range. Ankle rocker should be at least 10° with 15° been preferable and for footlocker at least 50° with 65 been preferable.
If you need to know more about rockers, click here.
The motion needs to occur somewhere…Make sure you look at the whole picture
Since the knee was bent, perhaps we should be looking at the soleus? And the talo crural articulation?
“A more limited ankle Dorsi Flexion Range Of Motion as measured in Non Weight Bearing with the knee bent increases the risk of developing Achilles Tendonitis among military recruits taking part in intensive physical training.”
J Foot Ankle Res. 2014 Nov 18;7(1):48. doi: 10.1186/s13047-014-0048-3. eCollection 2014. Limited ankle dorsiflexion increases the risk for mid-portion Achilles tendinopathy in infantry recruits: a prospective cohort study. Rabin A1, Kozol Z1, Finestone AS2.
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.
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…
Being a gait geek offers you a unique perspective in many situations.
Perhaps you have been with us for some time now and would like to check your gait acumen. If you are new, or these terms are foreign to you; search here on our blog through hundreds of posts to become more comfortable with some of the vocabulary.
Watch this video a few times (we slowed it down for you) and write down what you see.
Did you see all of these in this brief video?
bilateral loss of hip extension
bilateral loss of ankle rocker
less ankle rocker on right
bilateral increased progression angle
dip in right pelvis at right heel strike
arm swing increased on R
The Gait Guys. Increasing your gait competency each and every day.
special thanks to NL for allowing us to use this video footage.
Today we have a neuroscience piece on “turning”, in a matter of speaking. So why, when blindfolded, can’t we walk straight?
These “Turning” field studies appear in Chris McManus’ book, Right Hand, Left Hand, The Origins of Asymmetry in Brains, Bodies, Atoms and Cultures (Phoenix, 2002).
NPR Story Produced by Jessica Goldstein, Maggie Starbard.
2. neuroscience 2 at the end of the show.
The myth of the 8 hour sleep
3. Blog reader asks: Any shoe recommendations for an uncompensated forefoot varus?
4. and another from the Blog: Hi The Gait Guys, what can I do to regain medial tripod? I have a forefoot varus and when I am standing it compensates and my rearfoot everts and gets valgus. I have been having some pain lately and it is annoying me a lot. Please help. Thank you.
5. FACEBOOK readers asks:
Bringing the Foot Back To Life: Restoring the Extensor Hallucis Brevis Muscle.