Orthotic brace

1. A brace for a joint between two limbs of an animal, comprising:

a first attachment member for coupling to the exterior of the first limb;

a second attachment member for coupling to the exterior of the second limb;

a four bar linkage for determining the kinematics of the first member relative to the motion of the second member; and

a damper for resisting the pivotal motion of the first member relative to the motion of the second member;

wherein said first attachment member includes a rigid portion defining a pocket having a first shape, said second attachment member includes a rigid portion defining a pocket having a second shape, and said four bar linkage includes a first link having a peripheral shape corresponding to the shape of said first pocket, a second link having a peripheral shape corresponding to the shape of said second pocket, a third link pivotally connected to said first link and said second link, and a fourth link pivotally connected to said first link and said second link.

2. The brace of claim 1 wherein said damper is a fluid damper having two elements movable relative to one another, said damper providing a damping force for resisting movement of one element relative to the other element, one said damper element being coupled to said first member, the other said damper element being coupled to said second element.

3. The brace of claim 2 wherein one said damper elements translates relative to the other said damper element.

4. The brace of claim 2 wherein one said damper element is pivotally coupled to the first member at a location proximal to said four bar linkage, and said other damper element is pivotally coupled to said second attachment member at a location distal from said four bar linkage.

5. The brace of claim 1 wherein said four bar linkage permits pivoting of said first attachment member relative to said second attachment member from a flexed position to an extended position, and said damper provides greater resistance to movement from the extended position toward the flexed position than from the flexed position toward the extended position.

6. The brace of claim 1 wherein a first link of said four bar linkage is pivotally coupled at one end to said first attachment member and pivotally coupled at the other end to said second attachment member, a second link of said four bar linkage is pivotally coupled at one end to said first attachment member and pivotally coupled at the other end to said second attachment member, said first link having a first length between pivotal couplings, said second link having a second length between pivotal couplings, the first length being about the same as the second length, the first link not being parallel to said second link.

7. The brace of claim 1 wherein said damper is a fluid damper, said damper including an internal valve for limiting the maximum fluid pressure within said damper.

8. The brace of claim 1 wherein said four bar linkage includes a first link pivotally coupled at a first pivot joint to said first attachment member and pivotally coupled at a second pivot joint to said second attachment member, a second link pivotally coupled at a third pivot joint to said first attachment member and pivotally coupled at a fourth pivot joint to said second attachment member, said first pivot joint being spaced apart from said third pivot joint by a first distance, said second pivot joint being spaced apart from said fourth pivot joint by a second distance, and the first distance is greater than the second distance.

9. The brace of claim 1 wherein said first attachment member couples to a thigh, said second attachment member couples to a calf, said first attachment member includes a rigid, partial hoop shape positioned at the posterior of the first limb and open across the anterior of the first limb, said second attachment member includes a rigid, partial hoop shape positioned at the posterior of the second limb and open across the anterior of the second limb.

10. A brace for a joint between two limbs of an animal, comprising:

a first attachment member for coupling to the exterior of the first limb;

a second attachment member for coupling to the exterior of the second limb;

a four bar linkage for determining the kinematics of the first member relative to the motion of the second member; and

a damper for resisting the pivotal motion of the first member relative to the motion of the second member;

wherein said first attachment member includes a rigid portion defining a pocket having a first shape, said second attachment member includes a rigid portion defining a pocket having a second shape, and said four bar linkage includes a first link having a peripheral shape corresponding to the shape of said first pocket, a second link having a peripheral shape corresponding to the shape of said second pocket, a third link pivotally connected to said first link and said second link, and a fourth link pivotally connected to said first link and said second link; and

wherein said first attachment member couples to a thigh, said second attachment member couples to a calf, said first attachment member includes a rigid, partial hoop shape positioned at the posterior of the first limb and open across the anterior of the first limb, said second attachment member includes a rigid, partial hoop shape positioned at the posterior of the second limb and open across the anterior of the second limb.

11. The brace of claim 10 wherein said damper is a fluid damper having two elements movable relative to one another, said damper providing a damping force for resisting movement of one fluid damper element relative to the other fluid damper element, one said fluid damper element being coupled to said first member, the other said fluid damper element being coupled to said second element.

12. The brace of claim 11 wherein one said fluid damper elements translates relative to the other said fluid damper element.

13. The brace of claim 11 wherein one said fluid damper element is pivotally coupled to the first member at a location proximal to said four bar linkage, and said other fluid damper element is pivotally coupled to said second attachment member at a location distal from said four bar linkage.

14. The brace of claim 10 wherein said four bar linkage permits pivoting of said first attachment member relative to said second attachment member from a flexed position to an extended position, and said damper provides greater resistance to movement from the extended position toward the flexed position than from the flexed position toward the extended position.

15. The brace of claim 10 wherein a first link of said four bar linkage is pivotally coupled at one end to said first attachment member and pivotally coupled at the other end to said second attachment member, a second link of said four bar linkage is pivotally coupled at one end to said first attachment member and pivotally coupled at the other end to said second attachment member, said first link having a first length between pivotal couplings, said second link having a second length between pivotal couplings, the first length being about the same as the second length, the first link not being parallel to said second link.

16. The brace of claim 10 wherein said damper is a fluid damper, said damper including an internal valve for limiting the maximum fluid pressure within said damper.

17. The brace of claim 10 wherein said four bar linkage includes a first link pivotally coupled at a first pivot joint to said first attachment member and pivotally coupled at a second pivot joint to said second attachment member, a second link pivotally coupled at a third pivot joint to said first attachment member and pivotally coupled at a fourth pivot joint to said second attachment member, said first pivot joint being spaced apart from said third pivot joint by a first distance, said second pivot joint being spaced apart from said fourth pivot joint by a second distance, and the first distance is greater than the second distance.

18. A method for rehabilitating an animal joint, comprising:

providing a brace for a joint between two limbs of an animal, comprising:

a first limb attachment member for coupling to the exterior of the first limb;

a second limb attachment member for coupling to the exterior of the second limb;

a four bar linkage for determining the kinematics of the first limb attachment member relative to the motion of the second limb attachment member; and

a damper for resisting the pivotal motion of the first limb attachment member relative to the motion of the second limb attachment member;

wherein said first limb attachment member includes a rigid portion defining a pocket having a first shape, said second limb attachment member includes a rigid portion defining a pocket having a second shape, and said four bar linkage includes a first link having a peripheral shape corresponding to the shape of said first pocket, a second link having a peripheral shape corresponding to the shape of said second pocket, a third link pivotally connected to said first link and said second link, and a fourth link pivotally connected to said first link and said second link;

an electrically-actuatable resistive force device interconnecting the first limb and second limb attachment members,

an electronic controller having memory and being operably connected to the resistive force device, and

a sensor in electrical communication with the controller;

sensing movement of one of the limb attachment members with the sensor;

storing a history of the sensed movement in the memory; and

modifying the resistive force characteristics of the resistive force device by the controller and in response to the history.

19. The method of claim 18 wherein the sensor provides a signal corresponding to the angular relationship of the first limb attachment member relative to the second limb attachment member, and said modifying is a function of the angular relationship.

20. The method of claim 18 wherein said modifying is in response to whether the joint is being extended or flexed.

21. The method of claim 18 wherein the resistive force device operates with magnetorheological fluid and said modifying is by altering the characteristics of the fluid in response to commands from the electronic controller.

22. An apparatus attached proximate to a joint between two limbs of an animal, comprising:

a first attachment member for coupling around the exterior of the first limb;

a second attachment member for coupling around the exterior of the second limb and pivotally connected to said first attachment member;

an electrically-actuatable resistive force device having a forcing characteristic which resists the motion of said first member relative to the motion of said second member, the forcing characteristic capable of being modified by an input command;

a sensor for sensing a parameter resulting from movement of one of said first member or said second member and producing a signal corresponding to the parameter;

an electronic controller operably connected to said resistive force device and receiving the signal, said controller providing the command in response to the signal;

a four bar linkage for determining the kinematic motion of said first member relative to the second member;

a first attachment member for coupling to the exterior of the first limb, said first member including a first rigid portion positioned at the posterior of the first limb; a second attachment member for coupling to the exterior of the second limb, said second member including a second rigid portion positioned at the posterior of the second limb, said second rigid portion being pivotally connected to said first rigid portion; and

wherein said first rigid portion has a partial hoop shape open across the anterior of the first limb, said second rigid portion has a partial hoop shape open across the anterior of the second limb, said first attachment member includes a first flexible strap attachable to said first rigid portion, and said second attachment member includes a second flexible strap attachable to said second rigid potion.

23. The apparatus of claim 22 wherein said sensor is a load cell or an angular position sensor.

24. The apparatus of claim 22 wherein said force device operates with magnetorheological fluid.