## Foot stiffness and footwear

1. The following proposes a hypothesis for a mechanism by which the foot becomes stiffer as the toes become more dorsiflexed during gait . If true ,one question the hypothesis raises is what effect close fitting footwear might have on foot function .

So the hypothesis ,which may be old hat or even wrong is as follows .

I began by looking at a radiograph of the human foot taken from the dorsal aspect . In the forefoot area , this clearly shows that the metatarsals extend distally to differing degrees . I have heard a line which connects the metatarsal heads called a" metatarsal parabola " so lets just go with that for now . This parabola is in the horizontal plane but is this arrangement which gives rise to the arch during the transition of the foot through late stance .

Consider as an analogous structure to the metatarsals ,the fingers of the hand .
Place your hand flat on a desk with the finger tips a few mm apart (ignore the thumb )
Now keeping the finer tips in place on the desk ,lift the hand off the desk ,pivoting around the finger tips till you reach an angle between the fingers and the desk of about 70 degress . Now look at the fingers relative to each other . They have formed an arch structure . (Think of a piece of guttering about a foot long pushed into sand at an angle of 70 degrees .The part of the guttering you can see above the sand is similar to the finger structure you have created on the desk top and similar to the metatarsal arch formed when a foot , flat on the floor ,transitions towards toe off with the toes becoming more dorsiflexed .

So how is energy stored in this system ? Back to the hand again .
If you try the above hand /desk experiment you will notice that the middle fingers of the four need to bend to stay in the same spot on the desk . With a transitioning foot .this bending is probably replaced with a forward displacement of the second and third metatarsal heads and associated toes causing energy to be stored in the distal transverse ligament .

So do the metatarsal heads of the first and second lesser toes move distally, relative to the other toes , as the toes move into a dorsilflexed position ? You can easily try this out for yourself by taking off your shoes and socks .sitting in a chair and moving your foot from a flat position to a position with the heel raised and observing toe movements ,but for me the answer was yes .

The above also explains pressure distribution under the forefoot .

So that is the theory in rough form .

Any thoughts ?

2. Regards
3. Gerrard Farrell

Glasgow
4. scotfoot, Yesterday at 7:17 PM