Spring orthotic device

1. A device for assisting locomotion using appendages, wherein the device comprises a proximal portion at a heel end of the device and a distal portion at a toe end of the device, comprising:

(a) a cradle having a proximal end, a distal end, an upper surface, and a lower surface,

(b) a first planar spring plate positioned below the cradle and mechanically connected to the cradle, the spring plate having a proximal end, a distal end, a lateral side between the proximal end and the distal end, a medial side between the proximal end and the distal end, an upper surface, and a lower surface, wherein the proximal end of the cradle and the proximal end of the spring plate are separated by a vertical extent;

(c) a rigid ventral pivot positioned below the spring plate and mechanically connected to the spring plate, wherein the proximal end of the spring plate bends vertically downward around an axis defined by the length of the ventral pivot in response to a downward force applied to the proximal end of the cradle; and

(d) a rigid dorsal pivot positioned between and mechanically connected to the cradle and to the spring plate, wherein the dorsal pivot is positioned proximally of the ventral pivot,

wherein the ventral pivot is positioned between the lateral side and the medial side of the first planar spring plate distally of a point on the first planar spring plate which receives a ground reaction force during a first portion of a gait cycle.

2. The device of 1 , wherein the dorsal pivot and ventral pivot comprise an outer surface having a cross-sectional shape selected from the group consisting of elliptical, hemispherical, tubular pivots, square, and contoured.

3. The device of claim 1 , wherein the dorsal pivot and/or the ventral pivot are hollow.

4. The device of claim 1 , wherein the cradle is configured to receive a human foot.

5. The device of claim 1 , wherein the distal end of the cradle extends to a point above the first planar spring plate which is proximal to a point on the first planar spring plate which receives a ground reaction force during a second portion of the gait cycle, preferably adjacent to a point below the ball of a subject's foot.

6. The device of claim 1 , further comprising rigid toe pivot attached to the lower surface of the first planar spring plate at a point located distally of the ventral pivot, wherein the toe pivot provides an axis around which the spring plate can bend downwardly during a toe-off portion of the gait cycle.

7. The device of claim 1 , wherein the cradle is made from a material selected from the group consisting of carbon fiber, metal, ethylene vinyl acetate, nylon, polyethylene, polypropylene, polyurethane, carbon fiber, or fiberglass.

8. The device of claim 1 , wherein the first planar spring plate is made from a material selected from the group consisting of carbon fiber, polycarbonate plastic, and steel, preferably carbon fiber including KEVLAR fiber and/or fiberglass.

9. The device of claim 1 , wherein the spring plate comprises a plurality of materials, wherein each of the plurality of materials has a different property selected from the group consisting of spring coefficient, modulus of elasticity and tensile strength.

10. The device of claim 1 , wherein the distal end of the first planar spring plate comprises a downwardly extending convex form.

11. The device of claim 1 , further comprising a vertically extending support having a proximal end and a distal end, wherein the distal end is mechanically connected to the upper surface of the cradle, the vertically extending support comprising a mechanical appendage.

12. The device of claim 11 , further comprising a handle attached to the proximal end of the vertically extending support, thereby forming a crutch.

13. The device of claim 11 , further comprising a brace attached to the proximal end of the vertically extending support, wherein the brace extends horizontally and is designed to receive a portion of a subject's leg below the knee.

14. The device of claim 11 , wherein the vertically extending support is attached at the distal end to a receptacle for an amputated limb, thereby forming a prosthetic.

15. The device of claim 11 , wherein the distal end of the vertically extending support is mechanically connected to a mechanical device, the vertically extending support comprising a mechanical appendage for allowing the mechanical device to achieve locomotion.

16. The device of claim 1 , further comprising:

a second planar spring plate positioned below the first planar spring plate, and

a second ventral pivot positioned below the second spring plate and mechanically connected to the second planar spring plate proximally of the ventral pivot positioned below the first planar spring plate.

17. The device of claim 1 , further comprising a planar forefoot spring extending distally from the distal end of the first planar spring plate.

18. The device of claim 1 , wherein the device is retained within a piece of footwear.

19. The device of claim 10 , wherein the convex form of the distal end of the first planar spring plate is a hemispherical forefoot spring.

20. A device for assisting locomotion using appendages, wherein the device comprises a proximal portion at a heel end of the device and a distal portion at a toe end of the device, comprising:

(a) a cradle having a proximal end, a distal end, an upper surface, and a lower surface,

(b) a first planar spring plate positioned below the cradle and mechanically connected to the cradle, the spring plate having a proximal end, a distal end, a lateral side between the proximal end and the distal end, a medial side between the proximal end and the distal end, an upper surface, and a lower surface, wherein the upper surface of the proximal end of the cradle and the upper surface of the proximal end of the spring plate are separated by a vertical extent;

(c) a rigid ventral pivot positioned below the spring plate and mechanically connected to the spring plate; and

(d) a rigid dorsal pivot positioned between the cradle and the spring plate, wherein the dorsal pivot is positioned proximally of the ventral pivot,

wherein the spring plate experiences a double bending during a first portion of a gait cycle, the spring plate bending vertically downward around the ventral pivot and vertically upward around the dorsal pivot in response to a downward force applied to the proximal end of the cradle.

21. The device of claim 20 , wherein the dorsal heel pivot is within between 1 centimeter and 4 centimeters of the proximal end of the spring plate.