The hand walkers: The family that walks on all fours. Part 1

Quadrupedalism and its commentary on human gait.  To understand your athlete, your patient, your client, whatever your profession, you need to have a good understanding of neurodevelopment.  If your client has some functional movement pattern flaws it could be from a delayed or expedited neurodevelopmental window. Generalized training and rehab will not correct an early or late window issue; often your work must be more specific.

     When we began our journey into our daily writings on “The Gait Guys blog” we had no idea of the never ending tangents our writing would take pertaining to gait, human movement and locomotion. It has become plainly obvious over time that this blog will likely exist as long as we choose to continue it. 

In 2006 we saw a documentary documentary entitled The Family That Walks On All Fours and the video clip above was from the documentary. It was a fascinating documentary and with our backgrounds in neurology, neurobiology, neuroscience, biomechanics and orthopedics we had more questions than the documentary touched upon. The documentary opened up many thoughts of neuro-development since we all start with a quadrupedal gait. But there had to be more to it than just this aspect because people eventually move through that neurologic window of development into bipedial gait.  This has been in the back of our minds for many years now.  Today we will touch upon this family and their challenges in moving through life, today we talk about Uner Tan syndrome, Unertan syndrome or UTS.

The original story is about the Ulas family of nineteen from rural southern Turkey. Tan described five members as walking with a quadrupedal gait using their feet and the palms of their hands as seen in this video.  The affected family members were also severely mentally retarded and displayed very primitive speech and communication. Since his initial discovery several other families from other remote Turkish villages have also been discovered.  In all the affected individuals dynamic balance was impaired during upright walking, and they habitually chose walking on all four extremities. Tan proposed that these are symptoms of Uner Tan syndrome.

UTS is a syndrome proposed by the Turkish evolutionary biologist Uner Tan. Persons affected by this syndrome walk with a quadrupedal locomotion and are afflicted with primitive speech, habitual quadrupedalism, impaired intelligence. Tan postulated that this is a plausible example of “backward evolution”. MRI brain scans showed changes in cerebellar development which you should know after a year of our blog reading means that balance and motor programming might be thus impaired.  PET scans showed a decreased glucose metabolic activity in the cerebellum, vermis and, to a lesser extent the cerebral cortex in the majority of the patients. All of the families assessed had consanguineous marriages in their lineage suggesting autosomal recessive transmission. The syndrome was genetically heterogeneous.  Since the initial discoveries more cases have been found, and these exhibit facultative quadrupedal locomotion, and in one case, late childhood onset. It has been suggested that the human quadrupedalism may, at least, be a phenotypic example of reverse evolution.

Neurodevelopment of Children:

Children typically go through predictable windows of neurodevelopment. Within a set time frame they should move from supine to rolling over. Then from prone they should learn to press up into a push up type posturing which sets up the spine, core and lower limbs to initiate the leg movements for crawling. Once crawling ensues then eventual standing and cruising follow.  In some children, it is rare yet still not neurodevelopmentally abnormal, they move into a “bear crawl” type of locomotion where weight is born on the hands and feet (just as in our video today of UTS).  Sometimes this window comes before bipedalism and sometimes afterwards but it should remain a short lived window that is progressed through as bipedalism becomes more skilled. 

In studying Uner Tan Syndrome, Nicholas Humphrey, John Skoyles, and Roger Keynes have argued that their gait is due to two rare phenomena coming together.

“First, instead of initially crawling as infants on their knees, they started off learning to move around with a “bear crawl” on their feet.Second, due to their congenital brain impairment, they found balancing on two legs difficult.Because of this, their motor development was channeled into turning their bear crawl into a substitute for bipedalism.”

According to Tan in Open Neurol, 2010

It has been suggested that the human quadrupedalism may, at least, be a phenotypic example of reverse evolution. From the viewpoint of dynamic systems theory, it was concluded there may not be a single factor that predetermines human quadrupedalism in Uner Tan syndrome, but that it may involve self-organization, brain plasticity, and rewiring, from the many decentralized and local interactions among neuronal, genetic, and environmental subsystems.

There is much more we want to talk about on this mysterious syndrome and the tangents and ideas that come from it. We will do so in the coming weeks as we return to this case.  We will talk about other aspects of neurodevelopment which should be interesting to you all since most our readers either are having children, will have them, or are watching them move through these neurologic windows.  And we know that some of our readers are in the fields of therapy and medicine so this should reignite some thoughts of old and new.  In future posts we will talk about cross crawl patterning in the brain, bear crawling, the use of the extensor muscles in upright posture and gait as well as other aspects of neurodevelopment gone wrong. We are not even close to being done with this video and all of its tangents. In the weeks to come we hope you will remain interested and excited to read more about its deep implications into normal and abnormal human gait.


Open Neurol J. 2010 Jul 16;4:78-89. Uner tan syndrome: history, clinical evaluations, genetics, and the dynamics of human quadrupedalism. Tan U.Department of Physiology, Çukurova University, Medical School, 01330 Adana, Turkey. link:

Humphrey, N., Keynes, R. & Skoyles, J. R. (2005). “Hand-walkers: five siblings who never stood up” (PDF). Discussion Paper. London, UK: Centre for Philosophy of Natural and Social Science.

Are you a Gait Troglodyte ? Are you sure ?

Are you a Gait Troglodyte ? Are you sure ? You might want to read on.

Most of us are all still in a cave and unacquainted with some of the affairs of the world. Some of us may find ourselves behind the times when it comes to GMO foods, social media, computers and the internet, smart phones while others may be behind on world issues and politics. Heck, some of us have never even seen “Ancient Aliens” on the History Channel !  It is hard to keep up with everything in this fast paced changing world. Something has to give for each of us and so we pick our poison and decide what it is that we are going to have to remain behind on when it comes to the learning curves of the world. And this is alright, but you have to first admit your “back of the pack” and “still living in a cave” type status on the issues and take some ribbing when acknowledging your limitations.  Failing to admit these inevitable shortcomings while pretending that you are still running with the pack can be a real problem. Not only are you faking yourself out but you may be deceiving those that you attempt to help.

Understanding gait, truly understanding it, is a monumental undertaking. This is why there are just no vast resources on it unlike other things in healthcare. Try going to PubMed and type in “arm swing”, you will see 318 articles. Try “pronation”, 2900 articles.  Now try “heart”, 1 million+ articles.  You get the point. Research is behind on gait, and thus our understanding of it is also poorly reflected in functional medicine and  human bodywork.  We are collectively gait troglodytes, living in stereotypical caveman times when it comes to gait.  Sure there are some good books like Perry’s text, or Michaud’s landmark work but there is a void on gait work and research. Human locomotion via gait (walking and running) is a small and poorly understood component by many. It is much the reason why we started The Gait Guys and began writing daily for over 600 days on gait issues. Little did we know that the door we had opened would continue to swing so wide and encompass so many other aspects that feed into human gait.

One of the aspects that worries us the most these days is the growing volume of “functional” work that is going on in the world of therapy and training.  There is a very important and critical place for this work and we fully admit that everyone needs to be on board with all of the great work that the leaders are teaching. What worries us is the apparent lack of integration of this work into gait assessment, gait therapy, and flawed gait neuro-biomechanics. Once again gait is not getting the pulpit it deserves. Yes, flaws in the functional screens and assessments need to be brought to light and remedied because they can impact bipedal locomotion but, the pendulum swings both ways. Gait can often be a cause of these functional problems that show up on the screens and assessments. If one fixes the functional pattern problems and the gait pattern is not restored then either the dysfunction will return or a new undesirable pattern will be generated. There needs to be more gait understanding and assessment from us all. Gait needs retraining as well, it is as much of a functional pattern as any other, if not more.  Gait deserves a pulpit as well.  Human assessment is clearly a two way street and it is not always clear who is the chicken and who is the egg. The problem may be that when gait does have its pulpit to speak from, who is the speaker ? A gait troglodyte or an expert ?

There will be folks who say we are over thinking this issue. There will be some who are offended. There will be some who cheer. There are some that will say “it will all come out in the wash” once the functional patterns are corrected elsewhere. They are wrong, it just is not that simple. Next to breathing, gait may be the second most compromised and corrupted functional pattern that humans express thousands of times daily. So, it is time to get busy.  It is time to peel off your Gait Troglodyte cloak and step into a 3 piece suit when it comes to understanding and interpreting gait.  If you are working in the world of human movement, locomotion, training, rehab and human biomechanics this is your next challenge.  Lets face it, we can either continue to walk around with our 10 year old flip phone understanding of gait or we can step up to a smart phone understanding of gait.  It is up to you, but know where you are and know your limitations. So be honest with yourself and your next client the next time you assess their gait. Be sure to ask yourself after seeing something that just doesn’t seem right in their gait, is what you see really what you are seeing ? Is that really what is wrong ? Or is it a compensation ? Do you know enough to see things for what they really are ?

Shawn and Ivo, The Gait Guys. 

We may not be Gait Troglodytes……. but some accuse us of living in a cave none the less.  However, if you have seen our cave, you will know it looks much like Bruce Wayne’s Batcave.  It isn’t your everyday cave.

Neurocognitive Control in Movement Perception and Control

You have read our blog posts on how much we respect and admire those that engage in complex motor tasks like gymnastics, martial arts, parqour, dance and others.  The more complex the task the greater the rewards on several levels.
We found yet another article supporting multiple levels of sensory-motor advancement, in this article’s case, dance however it applies broadly across all complex motor tasks.  We have also included another video with dub dancer Marquese Scott with this blog post. You may recall our prior writing with him, link here where we talked briefly about “foot edge work”. The above video is another demo of Marquese doing what he does best, making complex motor tasks look simple.

Neurocognitive control in dance perception and performance.

Acta Psychol (Amst). 2012 Feb;139(2):300-8. Epub 2012 Jan 9.

Department of Sport Science, Bielefeld University, Germany.

Abstract: Dance is a rich source of material for researchers interested in the integration of movement and cognition. The multiple aspects of embodied cognition involved in performing and perceiving dance have inspired scientists to use dance as a means for studying motor control, expertise, and action-perception links. The aim of this review is to present basic research on cognitive and neural processes implicated in the execution, expression, and observation of dance, and to bring into relief contemporary issues and open research questions.


What The Gait Guys have to say:

The abstract review above addresses six issues they discovered and investigated in dancers:

1) dancers’ exemplary motor control, in terms of postural control, equilibrium maintenance, and stabilization;

2) how dancers’ timing and on-line synchronization are influenced by attention demands and motor experience;

3) the critical roles played by sequence learning and memory;

4) how dancers make strategic use of visual and motor imagery;

5) the insights into the neural coupling between action and perception yielded through exploration of the brain architecture mediating dance observation; and

6) a neuroesthetics perspective that sheds new light on the way audiences perceive and evaluate dance expression.

As you have read from some of our previous blog articles, we have some experience in dance. We do this to make sure we are always pressing the edge of human sensorymotor development and learning.  Dance has been one of the most complex body movement endeavors we have undertaken, more difficult than many of the complex movements in various sports.  This is why we never have a problem recommending dance, gymnastics and pilates to our young patient’s parents who want their children to excel in any given sport.  Fast, precise, assured and efficient foot work will take one far in athletics.  It is why in basketball they talk so much about the importance of the first step off a dribble when confronting an opponent. The first step, when fast, precise, assured and efficient, will leave one’s opponent stunned and motionless as their savvy opponent effortlessly passes them by. Nothing teaches these foot skills better than dance in our experience. Just as Marquese displays above, mastering complex footwork leads to advanced body movement possibilities.  And possibilities in sport are what separate the great from the good.  The 6 points discussed above namely exemplary motor control, in terms of postural control, equilibrium maintenance, and stabilization, timing, on-line synchronization, sequencing of learning and memory, the advantages of strategic use of visual and motor imagery, the insights into the neural coupling between action and perception are all major advantages to the athlete who can put them into play at a higher level.  And the more complex cross training of tasks that occurs, the greater likelihood that these issues are what will allow the cream to rise to the top in sport.

The Gait Guys

Gait and Biomechanics and Love Potion #9 !

The topic today is the brain and human movement and music. We would like you to enjoy this video we chose today of Slavik and Anna a little differently that you would normally watch a video. We ask that you cover up the top half of the video with your hand or a thick piece of paper so that you can ONLY see their legs and feet. Trust us, the hands, arms and their youthful attractiveness will distract you from the amazing stuff going on down in the legs and feet. Go ahead now and watch the video and see the amazing skill and precision of complicated foot work. There will be times that the feet are a blur, you will think the video has been sped up. It has not. If you can understand this type of complex footwork gait and running foot strike is going to be child’s play. It is why we study this stuff, because everything after this is easy. These are two of the very best dancers of all time and they show it here moving to the musical group, The Coasters version of “Love Potion #9”. This video is a classic example of complex motor tasks combined to music. Music makes everything better. Weddings, parties, even elevators (usually) are better when there is music. Today we will discuss how the brain can use music to help us learn. If you know this next song, you may find yourself immediately humming it in your head …


Easy as 1 2 3

Or simple as Do Re Mi

ABC, 123, Do Re Mi, baby you and me

There you have it. The chorus to The Jackson 5’s song “ABC”.

Kids have always learned well and fast (such as the alphabet) when music is integrated into a concept. Music provides timing. Music taps into fundamental systems in our brains that are sensitive to melody and beat. And when you are learning a task, timing can access part of the brain to either make it easier, easier to remember, or engrain the learned behavior deeper. When you add music to anything you are exercising other parts of your brain with that task. It is nothing new in the world of music and brain research when it comes to proving that music expands areas of learning and development in the brain. As Dr. Charles Limb, associate professor of otolaryngology and head and neck surgery at Johns Hopkins University states “It (music) allows you to think in a way that you used to not think, and it also trains a lot of other cognitive facilities that have nothing to do with music.”

Several weeks ago we asked you as an athlete, and this pertains to runners and even those walking, to add music to your training. If you are walking, vary the songs in your ipod to express variations in tempo. Use those tempo changes to change your cadence. If you are a runner, once in awhile add ipod training to your workouts and do the same. Your next fartlek (a system of training for distance runners in which the terrain and pace are varied to enhance conditioning) might be a new experience. Perhaps an enjoyable one. Trust us, we have done it. Here at The Gait Guys, with our backgrounds in neurology and biomechanics amongst other things, we are always looking for new ways to learn and to incorporate other areas of brain challenge to our clients. To build a better athlete you have to use training ideas that are often outside the box.

Today’s video of Slavik and Anna is a classic example of complex motor tasks combined to music. It is much about timing. Dancers call it musicality. Asking anyone to learn these movements without music would not be impossible, it would take some time, but without a focus on perfect technique or music timing to the movements someone might be able to learn them crudely in a day or two. BUT, add the timing and musicality and accentuations to that music, such as Slavik and Anna show here, and this becomes a task of many many years study and practice. A task they make appear simple, elegant and fun to do or watch. Can you imagine the foot skill and core abilities of these two ? It is mind boggling the number of complex motor tasks that occur here every second.

So, go grab your iPod and go for a run or a walk. Mix up your songs. Hear the beat, feel the rhythm and change your next workout into “feeling” the change of the music’s embedded metronome. Use those advanced areas of your brain to integrate music and timing into your rehab, your run, your walk, your workout. Don’t just “listen” to the music. Rather, feel it, move your body to it, so your brain can integrate it and embed it and make your task more engrained. Remember what Dr. Charles Limb said,

“It (music) allows you to think in a way that you used to not think, and it also trains a lot of other cognitive facilities that have nothing to do with music.”

Shawn and Ivo……helping you push the edges of human performance, through science, music and medicine.

(And here is a thank you “shout out” to my dance instructors (Godiva, Brittni, Max, Jake, Vance, Ellie, Caleb and Michael) for helping me to understand, struggle, and learn about these complex foot, limb, core motions and how music changes the brain’s learning curve. It has taken my understanding of human movement, functional anatomy and biomechanics to a level that I never knew existed. You make walking and running so simple for me now, simple to do and understand. Thank you !)

Attached here is an article from CNN and Dr. Limb that inspired today’s blog post.

Gait, Running, Dance, Martial Arts and the Mirror neurons of the brain. Today The Gait Guys put it all together.  (Why you need to get familiar with mirror neurons).

When was the last time you actually truly “listened” to music and “used it” while you worked out or ran?  Many of us do it, but many of us are not using the music to its optimal advantage. This is something we will talk about at the end as we summarize today’s very important article.

Beautiful human movement is something to behold.  Being able to watch and appreciate beautiful movement does several things within the brain.

According the the Scientific American Article (LINK) by Columbia University neurologist John Krakauer:

“some reward-related areas in the brain are connected with motor areas …  and mounting evidence suggests that we are sensitive and attuned to the movements of others’ bodies, because similar brain regions are activated when certain movements are both made and observed. For example, the motor regions of professional dancers’ brains show more activation when they watch other dancers compared with people who don’t dance.”

Many things stimulate our brains’ reward centers, among them, both the participation in and the observance of coordinated movements thanks to our mirror neurons. Today we show an example of the world famous Slavi Kryklyvyy once again. The combination of the physical capabilities and the artistic rendering of the fluid and complex movements stir something in your brain.  Thanks to the mirror neuron cells in the brain’s cortex, which link the sensory experience from when a person is performing a movement or when watching someone else do it generates a subsequent motor experience in the brain.  Watching someone execute a complex athletic task for example, your brain’s movement areas subconscously activate and mentally plan and predict how the athlete would move based on what you would do. We do this when watching sports all the time. How many times have you watched an athlete and either verbally or mentally said to yourself “Oh man ! That was a dumb move ! I would never have done that ! I would have done ______ !”  Krakauer mentioned, ” the motor regions of professional dancers’ brains show more activation when they watch other dancers compared with people who don’t dance.”  This will be the same for all athletes. This is the same neurologic phenomenon that also allows you to truly appreciate a movement when it is done with amazing skill and precision.  Think of Cirque du Soleil and you will instantly know what we mean.

Watching Slavik move in the video above is complex motor tasking at its best. Dancers are amazing athletes, they are not just dancers. They are much like martial artists. Take Capoeira for example. It is a Brazilian martial art that combines elements of dance and music. It was created in Brazil mainly by descendants of African slaves with Brazilian native influences. It is a complex and feared martial art known by quick and complex moves, using mainly power, speed, and leverage for leg sweeps. It is a beautiful art, and a deadly art.

So, why does music make it that much better ? It is the same reason why weddings are less touching without music.  It is why music is used in church. It is why dance is paired with music.  Music stimulates the pleasure and reward areas of the brain, such as the orbitofrontal cortex, the ventral striatum and the cerebellum where timing, coordination and movement planning is performed. The combination of music with the motor task amplifies the reward zone in the brain. It is the task of trying to add timing and rhythm to movement that makes these activities that much harder, but that much more rewarding to the brain.  Runners who run with music, those who truly hear the timing and rhythm of the music and then use it in their workouts get a little something extra out of it. But sadly so many people “just listen” to the music instead of incorporating it into the movement.  A smart runner will vary the music and combine it with a run to vary tempo, cadence, speed etc.  That way the brain will be on fire and dish out rewards at a  new level. Dancers have no choice but to force the issue. We will sometimes use a metronome snapping of our fingers or clapping in the rhythm of a clients gait to help them hear the rhythm of their gait, particularly when it is arrhythmic due to pain or faulty biomechanics. We will do this so that it cues a heightened awareness in them. Seeing, feeling and hearing are all additive when sensory-motor relearning is concerned.

Gait and running are complex movements which we take for granted.  They are so automatized that we really do not realize how complex and amazing they are until something goes wrong or until someone brings the subtle flaws to our attention.  Maybe it is a stroke that compromises it, or maybe a neurologic disease like Parkinsons, or maybe it is as simple as a sprained ankle, a torn knee mensicus, a strained hamstring or a degenerative hip.  But any compromise to this complex sensory-motor task of ambulation immediately brings about a recognition that something is wrong to the skilled and aware observer. As in life, we do not appreciate something until something goes wrong with it.  Getting good at recognizing beautiful clean fluid gait and running is our job, and it is now your job. Now that you know better you cannot ignore gait in your clients, your artists, your athletes. Now that you know better, you must hold yourself to a higher level of expertise. Knowing what beautiful looks like will help you better understand what loss of beauty looks like.  It is what will make you better at understanding gait and human movement and locomotion and better at your chosen craft. It is what will heighten your appreciation of the amazing beauty of the human form and motion, whatever form it might take.

Shawn and Ivo.  Two guys who can see the beauty in movement, and who want you to see and feel it too.

A question from a doctor on the topic of limb alignment development.

The following question was forwarded to us from an internist on the USA east coast.


“I have a large number of female patients, many of them elderly.  I have noted that women in our society tend to progress to valgus knee deformity with age, and that TKR (total knee replacement) doesn’t seem to correct that deformity. Men tend more to the varus in our society.  I had formerly chalked that up to inherit gender difference.

3 or 4 years ago, I had occasion to spend a lot of time waiting outside the main Tokyo train station and observed a large number of people coming and going.  I observed the following:
1.  Young women had legs that were either straight or varus.
2.  Young women tended toward toeing in.
3.  They did all this in ridiculous high heels.
After some thought, I tend to attribute it to prolonged sitting in sesa (knees folded under), though being barefoot or in slippers while inside may also contribute.  Women in our society sit with their legs crossed.  Additionally, extensive shoe wearing leads to foot pronation.
So, could you direct me to someone who might have an interest in this observation and can refer me to any research that might have been done in this area?  I’ve had the dickens of a time trying to find anything on it, or even a specialized area of study that cares about such things.”


Thanks for your confidence in us. Here are some thoughts:

Frontal plane deformities (or development) is twofold: genetic (and X linked) and developmental. Children usually go through a varus to straight to valgus to straight development (Ron Valmassey talks about this in his text Clinical Biomechanics of the Lower Extremities). Women generally have larger Q angles (from birth) and this angulation often causes assymetrical epiphyseal development (increased pressure on the lateral malleolus/tibial plateau stunts growth) with overgrowth of the medial femoral condyle. Developmental changes are secondary to weight (obesity causes increase in valgus angle) and posture/muscular devlopment. The increased genu valgus places weight medial to the midline (2nd met) of the foot and the foot accomodates by pronating (often excessively, as noted by both of you). This causes medial rotation of the lower leg and thigh, resulting in lengthening of the glutes (esp G max) resulting in stretch weakness and subsequent over reliance on the gastroc/soleus group for propulsion (remember this group tries to invert the heel in an attempt to cause supination once you go past midstance. Weak intrinsics (as pointed out by Dr Mark) further fuels this cycle. “W” sitting (sometimes a cultural development, as pointed out by Dr Birgit) plays in as well.

As for “toeing in”; may women have the combination of genu valgus with internal tibial torsion (often with femoral retroversion) which makes the condition difficult to treat (the rearfoot needs to be supported, but the forefoot needs to be valgus posted) otherwise the knee is placed outside the saggital plane and the meniscus becomes macerated due to conflicting biomechanics at the knee (Thus the short term fix with orthotics with a return of the pain later).

Yes, high heels and open back shoes are evil as are open backed shoes (we spoke at a convention in Chicago a few years back on this, before some of the research was out).

Thanks for allowing us to participate. below are some references for you.

-The GAIT GUYS…….Ivo and Shawn


J Orthop Sports Phys Ther. 2008 Mar;38(3):137-49.

Differences in lower extremity anatomical and postural characteristics in males and females between maturation groups.

Shultz SJ, Nguyen AD, Schmitz RJ.


Applied Neuromechanics Research Laboratory, Department of Exercise and Sport Science, University of North Carolina at Greensboro, 1408 Walker Ave., Greensboro, NC 27402, USA.


When comparing maturation groups, limb length, pelvic angle, and tibial torsion increased with maturation, and anterior knee laxity, genu recurvatum, tibiofemoral angle, and foot pronation decreased with maturation. Females had greater general joint laxity, hip anteversion, and tibiofemoral angles, and shorter femur and tibial lengths than males, regardless of maturation group. Maturational changes in knee laxity and quadriceps angles were sex dependent.


We observed a general change of posture with maturation that began with greater knee valgus, knee recurvatum, and foot pronation in MatGrp1, then moved toward a relative straightening and external rotation of the knee, and supination of the foot in later maturation groups. While the majority of the measures changed similarly in males and females across maturation groups, decreases in quadriceps angles and anterior knee laxity were greater in males compared to females, and females were observed to have a more inwardly rotated hip and valgus knee posture, compared to males, particularly in later maturation groups.


[PubMed – indexed for MEDLINE]


J Bone Joint Surg Br. 1995 Sep;77(5):729-32.

Development of the clinical tibiofemoral angle in normal adolescents. A study of 427 normal subjects from 10 to 16 years of age.

Cahuzac JP, Vardon D, Sales de Gauzy J.


Centre Hospitalier Universitaire de Toulouse-Purpan, France.


We measured the clinical tibiofemoral (TF) angle and the intercondylar (IC) or intermalleolar (IM) distance in 427 normal European children (212 male and 215 female) aged from 10 to 16 years. In our study, girls had a constant valgus (5.5 degrees) and displayed an IM distance of < 8 cm or an IC distance of < 4 cm. By contrast, boys had a varus evolution (4.4 degrees) during the last two years of growth and displayed an IM distance of < 4 cm or an IC distance of < 5 cm. Values above these for genu varum or genu valgum may require careful follow-up and evaluation.