Prosthetic Wrist

Abstract

A prosthetic wrist for terminal devices preserves free rotation under high rotational or axial loads.

Claims

1. A prosthetic wrist comprising: a thrust bearing; and a locking ring gear having a bottom surface and a top surface; and said thrust bearing rotationally engaged with said bottom surface of said locking ring gear; and a tapered bearing having an inner race and an outer race, engaged with said top surface of said locking ring gear; and a spindle rotationally engaged with said tapered-bearing inner race; and a housing rotationally engaged with said tapered-bearing outer race; and at least one interference mechanism configured to lock said locking ring gear in a radial position; wherein a prosthetic terminal device fitted into said spindle may be rotated under load while said interference mechanism is not engaged with said locking ring gear, and is held in a fixed radial position when said interference mechanism is engaged with said locking ring gear.

2. The apparatus of claim 1 further comprising: at least one spring engaged with said at least one interference mechanism; and a linkage movably engaged with said interference mechanism, configured to move said interference mechanism against said at least one spring to engage with said locking ring gear; wherein movement of said linkage in a first direction, allows said at least one spring to elongate and disengage said at least one interference mechanism from said locking ring gear, thus allowing rotation of said spindle under load; and moving said linkage in a second direction compresses said at least one spring, engaging said at least one interference mechanism with said locking ring gear, locking rotation of said spindle.

3. An apparatus for joining a terminal device to a prosthetic wrist unit comprising: an adapter having a receiving end and a keyed end; and a spindle configured to receive said keyed end of said adapter; and said adapter receiving end configured to receive a prosthetic terminal device; wherein said adapter may be affixed to a prosthetic terminal device and thus may engage with a prosthetic wrist by said keyed engagement between said adapter and said spindle.

4. A prosthetic wrist comprising: a first housing portion rotationally engaged with a thrust bearing; and a locking ring gear having a bottom surface and a top surface; and said thrust bearing rotationally engaged with said bottom surface of said locking ring gear; and a tapered bearing having an inner race and an outer race, engaged with said top surface of said locking ring gear; and a spindle rotationally engaged with said tapered bearing inner race and fixedly engaged with said locking ring gear; and a second housing portion rotationally engaged with said tapered bearing outer race; and said first housing portion and said second housing portion fixedly engaged; and at least one interference mechanism; and at least one spring engaged with said at least one interference mechanism; and a linkage movable in at least a first direction and a second direction, and movably engaged with said interference mechanism, configured to move said interference mechanism against said at least one spring to engage with said locking ring gear; and an adapter having a receiving end and a keyed end; and said spindle configured to receive said keyed end of said adapter; and said adapter receiving end configured to receive a prosthetic hand; wherein a prosthetic hand fitted into said adapter and said spindle may be rotated under load while said interference mechanism is not engaged with said locking ring gear, and is held in a fixed radial position when said interference mechanism is engaged with said locking ring gear.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] To assist those of skill in the art in making and using the disclosed prosthesis and associated methods, reference is made to the accompanying figures, wherein:

[0012] FIG. 1 is a perspective view of an example embodiment;

[0013] FIG. 2 is an exploded view of the example embodiment of FIG. 1;

[0014] FIG. 3 is a cross-sectional view of the example embodiment of FIG. 1, shown in rotation-locked position.

[0015] FIG. 4a is a perspective view with some components removed, showing the function of the locking twist ring;

[0016] FIG. 4b is another perspective view with some components removed, showing the function of the locking twist ring;

[0017] FIG. 5 is a perspective view of an example adapter and spindle.

DESCRIPTION

[0018] FIG. 1 shows a wrist unit 100 that is an apparatus for engaging prosthetic-terminal devices which are affixed to an adapter 111 at the distal end of the apparatus. The adapter 111 is held by an adapter collet 110 to components contained within the upper housing 114 and lower housing 136 (FIG. 2) which support bi-directional, axial loading as well as side loading, while rotating the prosthetic about axis 109. A twist ring 116 locks and unlocks the rotation of the adapter 111 so that a prosthetic device threaded into the adapter may rotate freely under load, or may be locked into position while under load. Grooves 138 (FIG. 1), at the proximal end of the apparatus increase adhesion when laminated into a composite prosthetic socket.

[0019] FIG. 2 shows an exploded view of the wrist unit 100. FIG. 3 shows a cross-sectional view thereof. Referring to FIG. 2 and FIG. 3, an adapter 111 is affixed to a spindle 124 by way of an adapter collet 110. The adapter 111 has a key 112 that engages with a keyway 125 (FIG. 5) in the spindle 124. The adapter collet 110 seats the adapter 111 in the spindle 124 with the key 112 aligned with the keyway 125. An upper housing 114 is affixed by fasteners to a lower housing 136 to contain the components. Spring plungers 120 are affixed to a twist ring 116 by way of roll pins 118. Spring plungers 120 fit into holes 129 in a locking ring gear 128. One skilled in the art is familiar with spring-loaded pins that may be pressed into a hole to provide interference, and are released from the hole by pressure from the spring. Locking spring-loaded pins into the locking ring gear, locks the ring gear in a radial position. Disengaging spring-loaded pins from the locking ring gear allows free rotation. When rotated counterclockwise and pulled upward, the twist ring 116 rests atop fasteners 119. When rotated clockwise, holes 121 in the twist ring 116 align and receive fasteners 119, enabling downward movement of the twist ring as well as downward movement of the spring plungers 120 to fit into holes 129 to lock rotation of the locking ring gear 128 and thus the spindle 124 and a prosthetic engaged therein.

[0020] By pulling the twist ring 116 away from the locking ring gear 128, the spring plungers 120 are released from the locking ring gear 128, enabling free rotation of the locking ring gear 128 and spindle 124. Pulling the twist ring distally and twisting the twist ring 116 in a counterclockwise direction enables seating of the twist ring above the twist ring stopper fasteners (119) to put the wrist unit into free-rotation mode. Twisting the twist ring in a clockwise direction allows the spring plungers to pull the twist ring down proximally, enabling re-engagement of the spring plungers 120 with the locking gear 128 to put the wrist unit into rotation-locked mode.

[0021] A combination tapered bearing 126 and thrust bearing 130 supports rotation of a prosthetic under load. An adapter 111 is joined to spindle 124 which is in turn joined to the inner race of a tapered bearing 126. The tapered bearing 126 supports loads when the user pulls against the prosthetic or when the prosthetic is under side loading. The thrust bearing supports loads when the user pushes against the prosthetic.

[0022] A thrust bearing 130 supports rotation of a prosthetic, which is affixed to the adapter 111, when under axial loading, as when pushing. A thrust bearing washer 132 provides a surface for the thrust bearing 130 to roll against. A retaining ring 134 holds the locking ring gear 128 and the tapered bearing to the spindle 124. One skilled in the art understands how the adapter 111 engaged with the spindle 124 may rotate freely under a load that is carried by the bearing combination.

[0023] Referring to FIG. 4a and FIG. 4b: FIG. 4a shows a linkage, also referred to as a twist ring 116 with spring plungers 120 disengaged from holes 129 in the locking ring gear 128; and FIG. 4b shows a twist ring 116 with spring plungers 120 engaged with holes 129 in the locking ring gear 128. When the twist ring 116 is moved toward the distal end of the apparatus and is rotated counterclockwise as shown in FIG. 4a, the twist ring 116 rests on fasteners 119 such that spring plungers 120 are disengaged from holes 129 in the locking ring gear 128. When the twist ring 116 is moved toward the proximal end of the apparatus and is rotated clockwise as shown in FIG. 4b, holes 121 align with fasteners 119 such that the twist ring 116 receives fasteners 119. When fasteners 119 are received in the twist ring 116, spring plungers 120 are disengaged from holes 129 in the locking ring gear 128.

[0024] FIG. 5 shows a detail view of the key 112 engaged in the keyway 125. One skilled in the art is familiar with a key that fits through a hole and twists to cause interference.

[0025] These example embodiments should not be construed as limiting.