Sunday, May 05, 2013

Shoe wearmarks an aid to diagnosis

Shoes wear with use and that is the nature of the accessory. The effects of three dimensional motion, shear and stress between the foot and ground eventually destroy the prissiness of the shoe. In the normal course of events the life span of good fitting shoe can be up to two years but most will begin to show signs of wear and tear after 6 months. Routine shoe maintenance including minor shoe repairs to quality made shoes can increase longevity but in this throwaway society often the cost of shoe repair is higher than the purchase of a new pair of shoes. Time was no home would be without a shoe repair kit but changes in mass produced footwear with moulding technique has relegated these to the garden shed or antiques saleroom. To the trained eye wear patterns of shoes are a clear indicator of foot problems. This evidence is frequently used to confirm clinical diagnosis by medical experts. Walking is a cyclic event (repeated) and a learned activity. Walking or gait patterns follow biomechanical principles and start with heel strike in the leading extremity. As the body’s Centre of Mass (COM) passes over the weight bearing foot the foot falls into mid stance where it acts as a stable pedestal. As the arch flattens the COM moves distally towards the toes before push off. The same motion is then replicated by the opposing limb. In normal walking shoe wear can be seen on the outer edge of the heel. This corresponds to inversion of the calcaneum and is part of a natural motion to dampen down peak shock at heel strike. As the foot adjusts to midstance it becomes a mobile adaptor and seeks to achieve maximum ground contact whilst supporting the body weight. This is when the arch of the foot sits in its highest position. Weigh bearing across the forefoot travels effortlessly for the outside of the shoe across the ball of the foot. Once the heel lifts form the ground the last part of the shoe to press against the ground is the great toe. Normal wear on the sole should show no excessive wear on the tread. Patches of wear in any part of the ball is indicative of faulty mechanics which can relate to damaged joints. Shoe volume (actually size and shape of the worn shoe) can also help the expert analyse dynamic movement of the damaged foot.

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