podborski

KNEE INJURIES – PART 1

In LESS REALLY IS MORE I talked about how I gone in a direction opposite from that of the industry after my perfect fit experience with Mur. I was now removing material from ski boots instead of adding material and expanding shells where necessary to make room for the structures of the foot. While this seemed to generally have a positive effect on skier balance and the ability to control skis, especially edging, removing material from the sides of the boot liner  exacerbated the fact that in the majority of cases I was encountering the shell wasn’t loading the instep of the foot. The reason for this turned out to be  that there was a void between the top of the tongue of the liner and the inner surface of the shell over the forefoot. This was allowing the foot to move upward into the void space or unload from contact with the sole plate (aka boot board) in response to changes or perturbations in ground reaction force. I coined the effect Separation Anxiety because of the alarm bells it was setting off in the skier’s balance system.

After I became aware of this effect, I started doing experiments to try and understand how it was affecting a skier’s balance and ability to control their skis. While riding ski lifts with foot rests (the old slow chairlifts) I would let one of my feet drop off the foot rest and try and feel what was happening with my foot and leg inside the boot when the foot unloaded from the boot board. At that time, I wasn’t thinking in terms of trying find a solution for knee injuries. I saw this as an issue that would be addressed by refinements in bindings which at that time were rapidly evolving. Through my experiments I had come to the realization that the unloading and reloading of the sole of the foot with the boot board, such as occurs when a skier is moving over irregular terrain, was setting off a chain-reaction of physiological events that were creating balance issues. Although I didn’t know exactly how, this unload/load cycle  seemed to be placing stress on the knee. But my focus was trying to find a way to reduce the effect on skier balance. In effect, I was trying to achieve a net improvement in skier balance by reducing negative balance artifacts.

The standard solution in those days was to attempt wedge the heel with heel or L-pads inserted in the liner. The objective was to keep the foot from lifting. I tried this approach. But I  found it didn’t work as advertised. The pads invariably caused problems with the Achilles tendon or they prevented the heel from seating in the back of the shell, or both. The latter had the effect of making the liner shorter and the boot hell to put on. I was looking for a better solution. But it wasn’t until 1980, while working on Podborski’s boots, that I came up with a device that eventually led to my being granted US Patent Number 4,534,122.