Development of the arch: Functional implications | Lower Extremity Review Magazine

A nice, referenced piece from one of our fav’s, Dr Michaud.

“Although early research suggested a limited connection between arch height and lower extremity function, more recent research confirms that arch height does indeed affect function. Information obtained from measurements that accurately identify the height of the medial longitudinal arch may lead to more effective treatment protocols. By identifying specific injuries associated with low and high arches, it may also be possible to prevent these injuries.”

Development of the arch: Functional implications | Lower Extremity Review Magazine

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…

Remember this kiddo?

We have been following the natural development of this little guy for some time now. For a review, please see here (1 year ago) and here (2 years ago) for our previous posts on him.

In the top 2 shots, the legs are neutral. The 3rd and 4th shots are full internal rotation of the left and right hips respectively. The last 2 shots are full external rotation of the hips.

Well, what do you think now?

We remember that this child has external tibial torsion and pes planus. As seen in the supine photo, when the knees face forward, the feet have an increased progression angle (they turn out). We are born with some degree / or little to none, tibial torsion and the in-toeing of infants is due to the angle of the talar neck (30 degrees) and femoral anteversion (the angle of the neck of the femur and the distal end is 35 degrees).  The lower limbs rotate outward at a rate of approximately 1.5 degrees per year to reach a final angle of 22 degrees….. that is of course if the normal de rotation that a child’s lower limbs go through occurs timely and completely.

He still has a pronounced valgus angle at the the knees (need a review on Q angles? click here). We remember that the Q angle is negative at birth (ie genu varum) progresses to a maximal angulation of 10-15 degrees at about 3.5 years, then settles down to 5-7 degrees by the time they have stopped growing. He is almost 4 and it ihas lessend since the last check to 15 degrees.

His internal rotation of the hips should be about 40 degrees, which it appears to be. External rotation should match; his is a little more limited than internal rotation, L > R. Remember that the femoral neck angle will be reducing at the rate of about 1.5 degrees per year from 35 degrees to about 12 in the adult (ie, they are becoming less anteverted).

At the same time, the tibia is externally rotating (normal tibial version) from 0 to about 22 degrees. He has fairly normal external tibial version on the right and still has some persistent internal tibial version on the left. Picture the hips rotating in and the lower leg rotating out. In this little fellow, his tibia is outpacing the hips. Nothing to worry about, but we do need to keep and eye on it.

What do we tell his folks?

  • He is developing normally and has improved significantly since his original presentation to the office
  • Having the child walk barefoot has been a good thing and has provided some intrinsic strength to the feet
  • He needs to continue to walk barefoot and when not, wear shoes with little torsional rigidity, to encourage additional intrinsic strength to the feet
  • He should limit “W” sitting, as this will tend to increase the genu valgus present
  • We gave him 1 leg balancing “games” and encouraged agility activities, like balance beam, hopping, skipping and jumping on each leg individually

We are the Gait Guys, promoting gait and foot literacy, each and every post.

Yes, we are all twisted; Part 3

 

In the last 2 posts we discussed the differences between torsions and versions, as well as talar version and torsion, 1 of the 3 major versional events that occur during normal development (missed out? Click here and here to re read them).

In this post we discuss tibial versions and torsions.

The tibia and femur are more prone to torsional defects, as they are longer lamellar (layered) bones as opposed to the cancellous bone that makes up the talus. These often present as an “in toeing” or “out toeing” of the foot with respect to the leg; changing the progression angle of gait (click here for more on progression angles).

Tibial versions and torsions can be measured by the “thigh foot angle” (the angulation of the foot to the thigh with the leg bent 90 degrees: above right) or the “transmalleolar angle” (the angle that a line drawn between the medial and lateral malleoli of the ankle makes with the tibial plateau: above left). 

At a gestational age of 5 months, the fetus has approximately 20° of internal tibial torsion. As the fetus matures, The tibia then rotates externally, and most newborns have an average of 0- 4° of internal tibial torsion. At birth, there should be little to no torsion of the tibia; the proximal and distal portions of the bone have little angular difference (see above: top). Postnatally, the tibia should twist outward (externally) a total of 15 degrees until adult values are reached between ages 8 and 10 years of 23° of external tibial torsion (range, 0° to 40°). 

Sometimes the rotation at birth is excessive. This is called a torsion. Five in 10,000 children born will have rotational deformities of the legs. The most common cause is position and pressure (on the lower legs) in the uterus (an unstretched uterus in a first pregnancy causes greater pressuremaking the first-born child more prone to rotational deformities. Growth of the  unborn child accelerates during the last 10 weeks and the compression from the uterus thus increases. As you would guess, premature infants have less rotational deformities than full-term infants. This is probably due to decreased pressure in the uterus. Twins take up more space in the uterus and are more likely to have rotational deformities. 

Of interesting note, there is a 2:1 preponderance of left sided deformities believed to be due to most babies being carried on their backs on the left side of the mother in utero, causing the left leg to overlie the right in an externally rotated and abducted position.

Normal ranges of versions and torsions are highly variable (see chart above: right). Ranges less than the values are considered internal tibial torsion and greater external tibial torsion.

Internal tibial torsion (ITT) usually corrects 1 to 2 years after physiological bowing of the tibia (ie tibial varum) resolves. External tibial torsion (TT) is less common in infancy than ITT but is more likely to persist in later childhood and NOT resolve with growth because the natural progression of development is toward increasing external torsion.

Males and females seem to be affected equally, with about two thirds of patients are affected bilaterally and the differences in normal tibial version values are often expected to be cultural, lifestyle and posture related.

 The ability to compensate for a tibial torsion depends on the amount of inversion and eversion present in the foot and on the amount of rotation possible at the hip. Internal torsion causes the foot to adduct, and the patient tries to compensate by everting the foot and/or by externally rotating at the hip. Similarly, persons with external tibial torsion invert at the foot and internally rotate at the hip. Both can decrease walking agility and speed if severe. With an external tibial torsion deformity of 30 degrees , the capacities of soleus, posterior gluteus medius, and gluteus maximus to extend both the hip and knee were all reduced by over 10%.

Well, that was probably more than you wanted to know about tibial torsions, and we could go on for many more pages and perhaps cure any insomnia you may have. Take a while to digest this, as it is important to gait, shoe selection, and rehabilitation. Torsions are an acquired taste and we hope we have whetted your appetite! Tomorrow we talk about compensations!

 

Ivo and Shawn; two twisted guys!

 

 

 

 

All material copyright 2013 The Gait Guys/ The Homunculus Group. All rights reserved.  Ask before you lift our stuff, Lee is watching……

Yes, we are all twisted: Part 1

Developmentally speaking, that is.  Version and Torsion are the words we need to know. There are 3 normal versional changes that take place in the lower extremity development from infant to adult: rotation of the talar head/neck, tibial rotation, and femoral rotation  (see above). 

So, what is the difference between a torsion and version?

A version is a normal variation in the “twistedness” of a limb (longitudinally speaking) between its proximal and distal portions, representing a normal range of development (see femur above) .  An example is the head and neck of the femur has an angle of 8-12 degrees with respect the femoral condyles.

A torsion is the same condition with the amount of twist 1 to 2 standard deviations greater. An example is when the angle of the femoral neck and greater than 15 degrees, the condition of femoral ante torsion exists (see photo above).

There are at least 3 reasons you need to understand about developmental torsions and versions that occur with growth:

  1. Since they occur in the transverse (horizontal) plane, they affect the progression angle of the foot and thus gait
  2. They affect available ranges of motion of a limb (ex the femur needs to internally rotate 4-6 degrees for normal gait) and can cause pain and/or gait alterations
  3. They can affect the coronal (frontal) plane orientation of the lower limb, which can affect gait and shoe choices. A Rothbart foot type with an elevated 1st metatarsal head will often result in a varus (or inverted) position of the forefoot with respect to the rear foot.

In this series, we will explore these 3 major versional changes, one at a time.

The Gait Guys. Bald? Yes! Good looking? You bet! Yes, we are a little more twisted than most folks : )

All material copyright 2013 The Gait Guys/ The Homunculus Group. All rights reserved.  Please ask before recycling our stuff!

Speed Matters: Brief Thoughts on Gait and Running.

The journal article below sparked a few thoughts for a blog post today.
Have you ever tried to walk slower than your normal pace ? How about running slower than your normal pace (  you know, running with that person who is clearly a minute slower pace) ? Why are both so uncomfortable and labor intensive ? Why does your balance, energy and stability become challenged ? After all, slower should be easier right ?!
There are many reasons and this study hints at a few issues but the bottom line is that speed matters.  Have you ever been driving down the road and you see a big pot hole in the road that you just cannot get around because it is either too big or you do not have time to steer around it ?  What is your first reaction ?  Many will press down on the gas pedal. Why is that ? Well, logic for many is that speeding up will possibly enable you to launch across the void and reduce the impact issues of dropping down into the void.  Men will rationalize the “launch across the pothole” theory, and in some respects they are not wrong.
Running and walking slowly sort of bring out some of the same issues.  When we move slowly the body is more likely to drift into the frontal/coronal (side to side) plane.  Moving more quickly ensures that the dominant path is forward. Slowing down does not ensure that forward will occur. side to side sway enters the picture. And when side to side sway enters as an option we have to spend more time and strategies negotiating the side sway.  This is why we see all kinds of corrections with the limbs and core when we attempt to stand on one foot, but we do not see these issues when we walk or run.  When running we are mostly trying to get the next foot underneath our body so that we do not fall forward flat on our face. Locomotion is a strategy of nothing more than trying to stay upright.  When we run the predominant motion is forward. But when we slow down and reduce the advantage of speed to blur out these issues the challenges begin and other planes of movement become an option and thus planes we need to control. It is much why the elderly have more difficulty moving about, because they have to negotiate and control so many other planes of movement.
So, if you want to bring out some faulty motor patterns, move more slowly and see where your deficits lie. One of our assessments for patients and athletes is to have them walk at a 3second pace meaning each foot fall must be held for 3 seconds before the next step can be initiated. This means stance and swing must be slowed to 3 seconds.  Amazing things will show up if you just slow things down and allow weaknesses to percolate to the surface.  Speed blurs them and keeps them suppressed. It is really a form of cheating and compensation.
So, like in your car, speed matters.
Think about this next time you have to walk or run with a slower person. It may be one of the issues, but there are others and we will eventually get to them.

Gait and Speed on Child Development

J Biomech. 2008;41(8):1639-50. Epub 2008 May 7. The effect of walking speed on the gait of typically developing children. Schwartz MH, Rozumalski A, Trost JP. Abstract

Many gait studies include subjects walking well below or above typical self-selected comfortable (free) speed. For this reason, a descriptive study examining the effect of walking speed on gait was conducted. The purpose of the study was to create a single-source, readily accessible repository of comprehensive gait data for a large group of children walking at a wide variety of speeds. Three-dimensional lower extremity joint kinematics, joint kinetics, surface electromyographic (EMG), and spatio-temporal data were collected on 83 typically developing children (ages 4-17) walking at speeds ranging from very slow (>3 standard deviations below mean free speed) to very fast (>3 standard deviations above mean free speed). The resulting data show that speed has a significant influence on many measures of interest, such as kinematic parameters in the sagittal, coronal, and transverse planes. The same was true for kinetic data (ground reaction force, moment, and power), normalized EMG signals, and spatio-temporal parameters. Examples of parameters with linear and various nonlinear speed dependencies are provided. The data from this study, including an extensive electronic addendum, can be used as a reference for both basic biomechanical and clinical gait studies.

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Neuromechanics weekly: proprioceptive clues in Children’s Gait.

We can learn a lot about gait from watching our children walk. An immature nervous system is very similar to one which is compensating meaning cheating around a more proper and desirable movement pattern; we often resort to a more primitive state when challenges beyond our ability are presented. This is very common when we lose some aspect of proprioception, particularly from some peripheral joint or muscle, which in turn, leads to a loss of cerebellar input (and thus cerebellar function). Remember, the cerebellum is a temporal pattern generating center so a loss of cerebellar sensory input leads to poor pattern generation output. Watch this clip several times and then try and note each of the following:

  • wide based gait; this is because proprioception is still developing (joint and muscle mechanoreceptors and of course, the spino cerebellar pathways and motor cortex)
  • increased progression angle of the feet: this again is to try and retain stability. External rotation allows them to access a greater portion of the glute max and the frontal plane (engaging an additional plane is always more stable).
  • shortened step length; this keeps the center of gravity close to the body and makes corrections for errors that much easier (remember our myelopathy case from last week ? LINK.  This immature DEVELOPING system is very much like a mature system that is REGRESSING.  This is a paramount learning point !)
  • decreased speed of movement; this allows more time to process proprioceptive clues, creating accuracy of motion

Remember that Crosby, Still, Nash and young song “Teach Your Children”? It is more like, “teach your parents”…

Proprioceptive clues are an important aspect of gait analysis, in both the young and old, especially since we tend to revert back to an earlier phase of development when we have an injury or dysfunction.

Ivo and Shawn. Still bald, still good looking, with intact cerebellums and neocortices : )