Accessible Summary:

Purpose: This paper integrates our understanding of receptors involved in balance when barefoot and shod. The SA II mechanoreceptor is primarily used in making foot position judgments when barefoot, whereas muscle and tendon receptors of the ankle are used when shod. 

Significance: This was the first report to suggest a relation between stability and impact.  Through integration of available data, the suggestion was made, that was later tested, that humans rely primarily on plantar tactile information for basic locomotory mechanics, which include maintenance of stability. Impact control is an unconscious consequence of stability maintenance and optimizing foot comfort.  When tactile information is not available, such as when wearing shoes, or perhaps when the plantar surface is anesthetized by cold, locomotory mechanics is largely organized through muscle receptors which gives less precise position information due to "after-effects." Loss of foot position awareness caused by shoes is the ultimate cause of ankle spraining, and consequences of footwear induced instability.