Splay

Watch this video a few times through. Did you catch the subtle abduction moment of the Hallux (big toe) on impact? Did you see the collapse of the transverse metatarsal arch? No?  Watch it until you do.

What gives? We thought toes were supposed to be stable when they hit the ground (and in fact they are).  Read on…

Think of the adductor hallucis. It has 2 heads. The oblique head arises from the proximal shafts of metatarsals 2-4 and inserts on the MEDIAL aspect of the proximal phalynx of the hallux (along with medial fibers of the flexor hallucis brevis); the transverse head arises from the metatarsophalangeal ligaments of  digits 3-5, and the transverse metatarsal ligament and inserts blending with the oblique head on the proximal phalynx of the hallux.

The action of the adductor hallucis mirrors that of the abductor hallucis (which inserts on the LATERAL side of the proximal phalynx. Together, they act to keep the hallux straight and provide a compressive force which stabilizes the big toe WHEN IT IS ON THE GROUND.

The problem here, is that the base of the Hallux is NOT anchored to the ground. This person has a faulty tripod (most likely an uncompensated forefoot varus) and cannot anchor the big toe, there fore the adductor cannot do it’s job. Is is weak (from lack of use) and we see the result: an abducting big toe AND collapse of the transverse metatarsal arch (which the transverse head of the adductor, under normal conditions maintains).

Looks like this guy needs some exercises to descend the head of the 1st metatarsal and make an adequate tripod. Flexing the distal phalynx of the hallux while extending the metatarsophalangeal joint would be a good start. (see Dr Allen demonstrate this here: http://www.youtube.com/user/TheGaitGuys?feature=grec_index#p/u/11/TyRE9dReVTE )

The Gait Guys…promoting foot literacy here and everywhere.

Follow up post on yesterdays FOOT TRIPOD VIDEO

Good Day Fellow foot geeks !

Yesterday we posted a quick video of a young  teenager who came to us for orthotic prescription.  As you can see in the early part of the video he had a flat foot posturing and increased foot progression angle (feet pointing too much east and west). 

The increased foot progression posturing can be a problem, and accentuate pronation strategies,  particularly if it is outside the normative values of 5-15 degrees. This is because during midstance the limb is internally rotating.  If the foot progression angle is increased as the limb internal rotation occurs while the body mass is progressing over the foot in midstance, the positioning of the medial tripod of the foot is far off the forward/sagittal progression line (the direction of walk). When the tibia and femur internally rotate on such a foot posturing the degree of pronation is accelerated and accentuated. In another way of explaining it, the subtalar joint is almost falling medially outside of the tripod boundaries and thus cannot be controlled by the tripod. It would be like placing a camera directly on the letter “c” in the triangle diagram above, where the points of the triangle represent the positions of the camera tripod legs. The camera is at risk of tipping over because the mass of the cameral is not within the solid boundaries of the triangle.  In the foot, these tripod leg points would be represented by the 1st and 5th Metatarsal heads and the heel forming a triangle.  The goal is to stabilize the tripod on level ground and place the camera  (foot) in the middle of the tripod for maximal stability.  But, when the foot progression angle is increased, the triangle and foot position take on the triangle appearance above, risking pronation excesses.

The problem is that many folks do not know they have developed this problem posturing until symptoms occur.  This young lad was brought into our offices by an aware mom who had heard of similar successes we have had with other children and adults. 

It took all of 10 minutes to retrain his awareness of the foot tripod and posturing of the feet underneath the body (where he noticed that he could not pronate as much as seen at the end of the video clip).  HE did awesome as you can see.  For the first time in his life he saw an arch and knew how to correct his foot posturing. He became aware of the use and need for good toe extension to raise the arch (a phenomenon known as The Windlass Mechanism of Hicks).  The last stage would be to help  him retrain these strategies in gait and various movements. 

We will see if we can find that video somewhere.

Bottom line, …….did this kid need an orthotic……. NO !  It would have kept absent the strength development of the muscles needed to make the correction you see in the video.  This kid now has a fighting chance to develop normally.

Hope this helps to explain what was going on in yesterdays video.

We are………foot nerds…….

Shawn and Ivo