Boots – shoes – and leggings – Orthopedic boot or shoe with corrective element
Reexamination Certificate
2000-01-31
2001-05-29
Sewell, Paul T. (Department: 3728)
Boots, shoes, and leggings
Orthopedic boot or shoe with corrective element
C036S088000, C036S028000, C036S043000, C036S141000, C036S176000
Reexamination Certificate
active
06237256
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to inserts for footwear, as well as footwear incorporating such inserts, which stimulate cutaneous pressure sensation from the edges of the feet (perimeter of the plantar foot surface) during standing and walking, and thereby improve the ability of the wearer's central nervous system to keep the body's center of gravity balanced and centered over the feet, particularly in persons who experience postural instability as a result of loss of cutaneous touch and pressure sensation due to aging or other factors.
DESCRIPTION OF THE PRIOR ART
One of the more pervasive effects of aging is a loss of cutaneous touch and pressure sensation. The loss of cutaneous sensation in the plantar surface (sole) of the feet has been correlated with impaired postural control (poor balance) and an increased risk of falling. In order to maintain stable upright stance, the center of gravity of the body must be positioned over the base of support established by the feet. Loss of balance and falling occur if the body weight is shifted too close to the limits of this base of support, i.e. too close to the perimeter of the plantar foot surface.
Numerous experimental studies support the important contribution of cutaneous sensation, from the plantar foot surface, in the control of postural balance. This cutaneous sensation acts, within the central nervous system, to trigger and/or modulate the automatic postural reflexes and reactions that act to prevent loss of balance and falling.
It is known that cutaneous sensation from the plantar surface of the foot can be stimulated mechanically by standing on raised protrusions and that such stimulation can reduce the postural sway that occurs during quiet standing. For example, having a person stand on a grid of small indentors (ball bearings) contacting the entire soles of the feet was found, in a laboratory experiment, to lead to increased activation of sensory nerves and concomitant reduction in postural sway when a person is standing still. However, providing increased cutaneous stimulation within the central regions of the plantar foot surface does not provide the central nervous system with information about the proximity of the center of gravity to the perimeter of the base of support, and has not been shown to improve a person's ability to react to a loss of balance and thereby avoid a fall.
Various footwear inserts and articles of footwear have been developed which incorporate raised protrusions of various shapes and sizes in various areas of the upper and/or lower surface of the insole. Invariably, these inserts have been designed for purposes other than improving postural balance and preventing falls.
For example, Daswick (U.S. Pat. No. 4,345,387) and Rosetta (U.S. Des. Pat. No. D373,013) both disclose an inner sole which includes a plurality of upwardly extending protrusions which are located throughout various portions of the inner sole and are designed to provide cushioning. Chang (U.S. Pat. No. 5,682,690) and Selzer (U.S. Des. Pat. No. D281,735) both disclose articles of footwear having a sole with upwardly extending protrusions which are located throughout large areas of the inner sole and are intended to massage the wearer's foot during walking. Hatuno (U.S. Pat. No. 3,757,774) discloses a massage sandal having a plurality of projections extending across the entire surface of the sole for the purposes of promoting blood circulation and strengthening the connective tissues of the foot by massaging the sole of the foot during walking. Padilla (U.S. Pat. No. 4,955,148) discloses a foot support assembly which includes several broad areas of raised support for the purposes of better distributing the forces acting on the foot so as to alleviate pain or discomfort. Douglas (U.S. Pat. No. 1,194,152) discloses a cushion insole with protrusions on the undersurface designed to afford ventilation of the foot. Tuki (U.S. Pat. No. 1,929,126) discloses a resilient sole element for footwear in which protrusions on the undersurface of the insole are intended to provide comfort, to protect against ingress of moisture and to provide protection against electrical shock. Misevich at al (U.S. Pat. No. 4,897,937) disclose an insole base member which uses protrusions of various sizes and shapes to form a mechanical interlock between the insole base and the insole.
Therefore, the prior art does not contain any examples of footwear inserts or articles of footwear which improve a person's ability to react to a loss of balance and thereby avoid a fall.
SUMMARY OF THE INVENTION
The present invention overcomes disadvantages of the prior art by providing an article of footwear and an insert for an article of footwear with a means for stimulating cutaneous pressure sensation from the perimeter of the plantar foot surface (foot sole) whenever the wearer's center of gravity shifts toward the edges of the feet. The inventors have found that increasing cutaneous sensation from the perimeter of the plantar foot surface provides the central nervous system with an enhanced ability to detect, and react to, weight shifts toward the edges of the feet which, if left uncorrected, could result in a loss of balance or a fall. The inventors have found that the inserts and footwear according to the present invention are particularly effective at improving the efficacy of the balance reflexes and reactions that act to correct for the weight shifts that occur as a result of unexpected perturbation (disturbance) of balance.
Although the scope of the present invention is not to be limited by theory, it is believed that promoting cutaneous pressure sensation specifically from the perimeter of the plantar foot surfaces (foot sole) may play an important role, within the central nervous system, in determining the proximity of the body's center of gravity to the stability boundaries of the base of support established by the feet, i.e. the perimeter of the plantar foot surfaces. Center-of-gravity location, relative to the base of support, is believed to be a critical variable that is controlled by the central nervous system in maintaining upright stance.
Accordingly, in one aspect, the present invention provides a foot-contacting insert adapted to be received on an upper surface of a sole in an article of footwear, the insert stimulating cutaneous pressure sensation from the perimeter of the plantar surface of the foot whenever the wearer's center of gravity shifts toward a periphery of the plantar foot surface during standing or walking. One or more narrow, ridge-forming members is located in close proximity to the perimeter of the insert, the inner portion of the insert being smoothly contoured. During standing or walking, the ridge-forming member forms a narrow, elongate, raised ridge which protrudes upwardly against the perimeter of the plantar surface of the foot, the raised ridge being sufficiently narrow, deep and hard to cause localized indentation of the skin and associated stimulation of cutaneous pressure sensation whenever body weight is shifted toward the perimeter of the plantar foot surface.
In another aspect, the present invention provides an article of footwear including a sole having an upper foot-contacting layer adapted to stimulate cutaneous pressure sensation from the perimeter of the plantar surface of the foot whenever the wearer's center of gravity shifts toward a periphery of the plantar foot surface during standing or walking. One or more narrow, ridge-forming members is located near the perimeter of the sole, the inner portion of the sole being smoothly contoured. During standing or walking, the ridge-forming member forms a narrow, elongate, raised ridge which protrudes upwardly against the perimeter of the plantar surface of the foot, the raised ridge being sufficiently narrow, deep and hard to cause localized indentation of the skin and associated stimulation of cutaneous pressure sensation whenever body weight is shifted toward the perimeter of the plantar foot surface.
REFERE
Maki Brian E.
McIlroy William E.
Perry Stephen D.
Ridout & Maybee LLP
Sewell Paul T.
Stashick Anthony
Sunnybrook and Women's College Health Sciences Centre
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