THE SCIENCE OF FOOT DYSFUNCTION AND CURE PART 3 – ARCH HEIGHT/FOOT TYPE.

Tags: foot, foot function, Science

“If the only tool you have is a hammer, you tend to see every problem as a nail”

 (Abraham Maslow)

The prevailing paradigm in podiatry is to view dysfunctional flat (low-arched) feet and rigid (high-arched) feet as separate issues with different causes. The common treatment however is the same… orthotics. This is despite no evidence for long-term benefits of orthotics. In reality, dysfunctional low and high arched feet are both caused by a compromised (shoe shaped) forefoot structure, the twist of the forefoot (MacConaill, 1945) on the rearfoot and the resulting instability. Read more in part 1 & part 2 of this series. 

High-rigid arch type – ‘compensated’ shoe-shaped foot.

Misaligned toes of a shoe-shaped forefoot create an unstable base of support. During the forefoot loading phase of the gait cycle, the instability must be compensated by muscular action. If muscles are strong enough to overcome the load produced (125% – 250% of bodyweight in walking and running respectively), the external rotation of the hip and supination of the rear foot on the forefoot creates a high-rigid arch and limited ankle range (Manoli and Graham, 2018). This inflexible foot and ankle is a poor shock absorber and stress fractures and lateral ankle sprains are common consequences (Williams, McClay and Hamill, 2001). With age and/or increased bodyweight, muscles begin to lose the strength to compensate for the instability of the shoe-shaped forefoot.

Flat/collapsed arch type – ‘decompensated’ shoe-shaped foot.

Misaligned toes of a shoe-shaped forefoot create an unstable base of support. During the forefoot loading phase of the gait cycle, the instability must be compensated by muscular action. When the muscles are weak and cannot overcome the load produced (125% – 250% of bodyweight in walking and running respectively) the rear foot and entire lower kinetic chain collapses inwards. Over time, this loading pattern and medial colllapse breaks down the soft tissues of the foot resulting in a dysfunctional collapsed/flat arch and knee injuries (Williams, McClay and Hamill, 2001).

Arch height is determined by rotation of the rear foot on the forefoot (MacConaill, 1945; Sarrafian, 1987) which, in turn, is determined by the ability of musculature to compensate for forefoot instability. Instability created by compromised foot structure (shoe-shaped forefoot) is the ultimate cause of both dysfunctional high-rigid and flat-collapsed arches. To avoid the issue, functional foot structure must be restored. The cure is simple:

1. Wear foot-shaped (functional) shoes with space for the toes to spread and the foot to widen and;

2. Load the feet with body weight creating the force to stimulate restoration of a functional foot shape.

Joe Nimble® functional footwear is based on these concepts and this science.

References.

MacConaill, MA. The postural mechanism of the human foot. Proceedings of the Royal Irish Academy, Section B: Biological, geological and chemical science. 1945; 50: 265-278.
Manoli, A and Graham, B. Clinical and new aspects of the subtle cavus foot: a review of an additional twelve year experience. Fuss and Sprunggelenk. 2018; 16: 3-29.
Sarrafian, SK. Functional characteristics of the foot and plantar aponeurosis under tibiotalar loading. Foot and Ankle. 1987; 8(1), 4-18.
Williams, DS, McClay, IS, Hamill, J. Arch structure and injury patterns in runners. Clinical Biomechanics. 2001; 16: 314-347.

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