Articulated hand prosthesis

1. A hand prosthesis comprising:

a chassis; and

at least one joint adapted to provide for flexion and extension movement of the chassis from a neutral position in relation to the coupling elements, the joint including first and second spring elements having progressive spring characteristics that urge the chassis from an angle of flexion or extension toward the neutral position, wherein the first and second spring elements are elastomer parts;

wherein the chassis is mounted to be rotatable about a rotation axis that is arranged at a right angle to an axis of flexion and extension movement and configured to be parallel to a longitudinal axis of a residual portion of an arm to which the hand prosthesis is mounted;

wherein the neutral position is aligned at an obtuse angle in relation to an angle that is at a right angle to the rotation axis of flexion and extension movement;

a locking device adapted to lock the joint to prevent flexion or extension movement of the chassis, the locking device being actuated in a direction along the rotation axis from a locked position that limits at least one of flexion movement and extension movement of the chassis to a released position that permits at least one of flexion movement or extension movement of the chassis.

2. A hand prosthesis comprising:

a chassis including prosthetic fingers and thumb;

a housing configured to be secured to a residual portion of an arm; and

a joint adapted to secure the chassis to the housing, the joint including a mounting plate coupled to the chassis, a coupling element coupled to the housing and the mounting plate to provide the chassis with flexion and extension movement relative to the housing, a first spring element comprising an elastomeric material and being disposed between the mounting plate and the coupling element that resiliently compresses to resist the flexion movement relative to a neutral position, and a second spring element comprising an elastomeric material and being disposed between the mounting plate and the coupling element that resiliently compresses to resist the extension movement relative to a neutral position, wherein at least one of the first and second spring elements has progressive spring characteristics;

wherein the chassis is mounted to be rotatable about an axis that is arranged at a right angle to an axis of flexion and extension movement and configured to be parallel to a longitudinal axis of the residual portion of an arm;

wherein the neutral position is aligned at an obtuse angle in relation to an angle that is at a right angle to the axis of flexion and extension movement;

a locking device adapted to lock the joint to prevent flexion or extension movement of the chassis, the locking device being actuated in a direction along the rotation axis from a locked position that limits at least one of flexion movement and extension movement of the chassis to a released position that permits at least one of flexion movement or extension movement of the chassis.

3. The hand prosthesis of claim 2 wherein the coupling element includes a rotating pin, the mounting plate includes a bore, which is capable of receiving the rotating pin to couple the coupling element to the housing.

4. The hand prosthesis of claim 3 wherein the coupling element and mounting plate each include opposing portions that contact the spring elements to resist flexion and extension movement from the neutral position.

5. The hand prosthesis of claim 2 , wherein the locking device comprises a push-push element.

6. The hand prosthesis of claim 2 , wherein the locking device comprises mating crown gearing disks, and operating the locking device into the released positioned included separating the crown gearing disks in a direction along the rotation axis.

7. The hand prosthesis of claim 6 , wherein the locking device comprises at least one spring member that biases the crown gearing disks into contact with each other to prevent flexion or extension movement of the chassis.

8. The hand prosthesis of claim 2 , wherein the locking device comprises a disengaging pin and a follower ball, the disengaging pin comprising a track and the follower ball engages the track to hold the locking device in the released position.

9. The hand prosthesis of claim 8 , wherein the track is cardioid shaped.

10. A hand prosthesis comprising:

a chassis; and

at least one joint adapted to secure the chassis to coupling elements on the stump of an arm to provide for flexion and extension movement of the chassis from a neutral position in relation to the coupling elements, the joint including a first spring element comprising elastomeric material that urges the chassis from an angle of flexion toward the neutral position, and a second spring element comprising elastomeric material that urges the chassis from an angle of extension toward the neutral position, wherein the first and second spring elements have progressive spring characteristics such that as the angle of flexion or extension increases during movement of the chassis, the first and second spring elements apply a correspondingly increasing force against the chassis;

wherein the chassis is mounted to be rotatable about a rotation axis that is arranged at a right angle to an axis of flexion and extension movement and configured to be parallel to a longitudinal axis of the stump of an arm;

wherein the neutral position is aligned at an obtuse angle in relation to an angle that is at a right angle to the axis of flexion and extension movement;

a locking device adapted to lock the joint to prevent flexion or extension movement of the chassis, the locking device being actuated in a direction along the rotation axis from a locked position that limits at least one of flexion movement and extension movement of the chassis to a released position that permits at least one of flexion movement or extension movement of the chassis.

11. The hand prosthesis of claim 10 , wherein at least one of the spring elements is a torsion spring.

12. The hand prosthesis of claim 10 wherein the spring elements are removable from the joint to accommodate exchangeable spring elements.

13. The hand prosthesis of claim 10 , wherein the locking device has crown gearing which are engaged to lock the joint.

14. The hand prosthesis of claim 10 , wherein the joint is positioned such that a region of the chassis corresponding to a metacarpal region is capable of flexion or extension movement.

15. The hand prosthesis of claim 10 wherein the spring elements are configured such that the greater that an angle of flexion or extension is between the chassis and the housing, the greater force the spring elements apply to the chassis and housing to return the hand prosthesis to the neutral position.

16. The hand prosthesis of claim 10 , wherein the locking device comprises a push-push element.

17. The hand prosthesis of claim 10 , wherein the locking device comprises mating crown gearing disks, and operating the locking device into the released positioned included separating the crown gearing disks in a direction along the rotation axis.

18. The hand prosthesis of claim 17 , wherein the locking device comprises at least one spring member that biases the crown gearing disks into contact with each other to prevent flexion or extension movement of the chassis.

19. The hand prosthesis of claim 10 , wherein the locking device comprises a disengaging pin and a follower ball, the disengaging pin comprising a track and the follower ball contacts the track to hold the locking device in the released position.

20. The hand prosthesis of claim 19 , wherein the track is cardioid shaped.