Abstract:
A multi-function body-powered prosthetic wrist unit that is attachable to the end of a prosthesis on an arm and provides over 270° of smooth pronation and supination rotation with a plurality of indexed rotation locking positions, wrist flexion and extension from 0 to 50° with three locking positions, and a quick disconnect connection for attachment of a variety of terminal devices thereto. Integral cable release assemblies provide body powered release for pronation and supination rotation and flexion and extension. Cable operated locks can be retracted or released passively by body-powered harnessing, and allow momentary (pull-to-release) or alternating (pull/relax) locking functions.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to the field of prosthetic hand and arm attachments, and more particularly to a multi-function body-powered prosthetic wrist unit that provides over 270° of smooth pronation and supination rotation with a plurality of locking positions, wrist flexion and extension from 0 to 50° with several locking positions, and a quick disconnect connection for attachment of a variety of terminal devices, such as hooks, electric hands, tools, implements, and other specialty terminal devices, thereto. 
   2. Background Art 
   Throughout this disclosure the expression “terminal device” is used in the ordinary vernacular of arm prostheses as a device (such as a hook, hand, electric hand, tool or implement) added to the most distal end of an arm prosthesis, for example at a wrist location. In the context of the present wrist unit invention, the terminal device is the device that is attached to the wrist unit. The phrase “active control” refers to motion between adjacent parts that is achieved by body powered harnessing. The phrase “passive control” refers to motion between adjacent parts that is achieved by direct application of external forces. 
   There have been a large number of prosthetic devices for use by amputees who have lost at least one or both hands, or one or both arms. Many of the devices are body-powered and some are driven, or at least assisted, by electrical, myoelectrical, and/or pneumatic means. 
   Most extremity prostheses currently in use have a terminal device (such as a hand or hook) controlled either by movements of a shoulder harness transmitted via a cable (i.e. body powered), or by myoelectric control (i.e., motors triggered by the contraction of muscles in the residual limb). However, conventional actively and passively controlled prosthetic devices have only one or two controlled degrees-of-motion, and provide limited ability to grasp, properly position, and manipulate the terminal device. 
   Thus, there exists a need to provide a prosthetic wrist device having improved control of multiple degrees of pronation and supination rotation, wrist flexion and extension, with a plurality of locking positions, along with a provision for quick and easy attachment of a variety of terminal devices, such as hooks, electric hands, tools, implements, and other specialty terminal devices. 
   Perez, U.S. Pat. No. 3,490,078 discloses a flexible sleeve for a forearm stump which has a threaded female member at the end of the sleeve into which can be threaded a handle of a tool. 
   Bengtson, U.S. Pat. No. 3,802,302 discloses a tool holding prosthetic device having a threaded connector devices for attaching various tools and shows the use of a detent ball. 
   Winter, U.S. Pat. No. 3,942,194 discloses a device for attaching to a hand to which an implement can be removably fastened. 
   Adkins, U.S. Pat. No. 4,661,113 discloses a device which is attachable to an amputee&#39;s prosthesis to enable the amputee to swing a golf club or other device which requires swinging. 
   Keith, U.S. Pat. No. 4,944,765 discloses an artificial arm prosthetic drive device for holding a rotatable tool. 
   Norton et al, U.S. Pat. No. 5,163,966 discloses a prosthetic limb having a means for grasping and holding a bar or tubular member. 
   Farquharson et al, U.S. Pat. No. 5,464,444, commonly owned with the present invention, and hereby incorporated herein by reference, discloses a terminal device that is attachable to the end of a prosthesis on an arm and serves as a universal attachment site for a variety of tools and implements designed to mate with the device. 
   The present invention is distinguished over the prior art in general, and these patents in particular by a multi-function body-powered prosthetic wrist unit that is attachable to the end of a prosthesis on an arm and provides over 270° of smooth pronation and supination rotation with a plurality of indexed rotation locking positions, wrist flexion and extension from 0 to 50° with three locking positions, and a quick disconnect connection for attachment of a variety of terminal devices thereto. Integral cable release assemblies provide body powered release for pronation and supination rotation and flexion and extension. Cable operated locks can be retracted or released passively by body-powered harnessing, and allow momentary (pull-to-release) or alternating (pull/relax) locking functions. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a multi-function body-powered prosthetic wrist unit for attachment to the distal end of an arm prosthesis that is compact in size, very light weight, and smooth in operation. 
   It is another object of this invention to provide a multi-function body-powered prosthetic wrist unit that enables five-functions, including multiple degrees of pronation and supination rotation, wrist flexion and extension, and a quick disconnect provision for quick and easy attachment of a variety of terminal devices, such as hooks, electric hands, tools, implements, and other specialty terminal devices. 
   Another object of this invention is to provide a multi-function body-powered prosthetic wrist unit that allows smooth pronation and supination rotation through a large angle of rotation about a longitudinal axis extending through the wrist unit, and has a plurality of selective indexed rotation locking positions at which it may releasably locked by the wearer. 
   Another object of this invention is to provide a multi-function body-powered prosthetic wrist unit having a quick disconnect member that pivots about an axis transverse to a longitudinal axis extending through the wrist unit and allows for quick attachment and release of a variety of terminal devices thereto, and which has selective pivot locking positions at which it may releasably locked by the wearer. 
   A further object of this invention is to provide a multi-function body-powered prosthetic wrist unit that allows for smooth pronation and supination rotation and flexion and extension motions and has release mechanisms that can be actuated passively by body-powered harnessing. 
   A still further object of this invention is to provide a multi-function body-powered prosthetic wrist unit that is simple in construction, inexpensive to manufacture, and rugged and reliable in operation. 
   Other objects of the invention will become apparent from time to time throughout the specification and claims as hereinafter related. 
   The above noted objects and other objects of the invention are accomplished by a multi-function body-powered prosthetic wrist unit that has a rear member having a back end configured to be releasably attached to the terminal end of an arm prosthesis and a front member rotatably connected the rear member to rotate relative thereto about a longitudinal axis extending through said wrist unit to provide over 270° of smooth pronation and supination rotation and has a plurality of indexed rotation locking positions. The front member of the wrist unit has a quick disconnect connection for attachment of a variety of terminal devices thereto which pivots about an axis transverse to the longitudinal axis to provide flexion from 0 to 50° with three locking positions. Retractable rotation and flexion locking pins connected with respective control cables can be retracted or released passively by body-powered harnessing, and allow momentary (pull-to-release) or alternating (pull/relax) locking functions. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a multi-function body-powered prosthetic wrist unit in accordance with the present invention. 
       FIG. 2  is a longitudinal cross section view of the multi-function body-powered prosthetic wrist unit taken along line  2 — 2  of  FIG. 1 . 
       FIG. 3  is a transverse cross section view of the a multi-function body-powered prosthetic wrist unit taken along line  3 — 3  of  FIGS. 1 and 2 , showing the plurality of indexed rotation locking holes in the flange of the rotation locking member. 
       FIG. 4  is a transverse cross section view through the locking pin housing taken along line  4 — 4  of  FIG. 2 , showing the set screw and licking pin arrangement. 
       FIG. 5  is a transverse cross section view taken along line  5 — 5  of  FIG. 2 , showing the torsion spring between the sleeve of the rotation locking member and the locking pin housing. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to the drawings by numerals of reference, there is shown in  FIGS. 1 ,  2 ,  3  and  4 , a preferred embodiment of the multi-function body-powered prosthetic wrist unit  10  in accordance with the present invention. The wrist unit  10  has a first generally conical front member  11  rotatably connected at its rear end with a second generally cylindrical rear member  16  with a back end configured to be releasably attached to the end of an arm prosthesis. The front member  11  rotates relative to the rear member  16  about a longitudinal axis AL extending through the wrist unit  10 . 
   The conical front member  11  has a slotted opening  11 A extending partially across its front end and a distance rearward along one side thereof. A generally rectangular quick disconnect connector  12  is pivotally mounted in the slotted opening  11 A by a hollow pivot pin  11 B extending transversely through the conical front member  11  and rear portion of the quick disconnect connector. As described hereinafter, the quick disconnect connector  12  is pivotally mounted in the opening  11 A to pivot at an angle “A” of from 0° to about 50° about an axis AT transverse to the longitudinal axis. 
   The quick disconnect connector  12  has a cylindrical cavity  12 A extending a distance inwardly from its front end that functions as a receptacle for receiving the proximal end of various terminal devices TD, and an outer facing side of the quick disconnect connector is fitted with a releasable locking mechanism  13  for releasable attachment of a variety of terminal devices thereto. In the illustrated example, the locking mechanism  13  is a quick-disconnect mechanism having a detent ball  13 A extensible partially through a hole in the side wall of the cylindrical cavity  12 A and a retractable plunger  13 B. The plunger  13 B is biased to a forward extended position by a compression spring  13 C to urge the ball into engagement with an indentation or hole  41  on a cylindrical adapter or insert  40  which is attached to the terminal device TD, or a cylindrical end portion of a terminal device. It should be understood that other types of easily released retaining means may be used. The back end of the quick disconnect connector  12  has an arcuate curved portion  12 B with three locking holes  12 C formed therein. 
   The open back end of the front member  11  has internal threads  11 C that terminate in a snap ring groove in which a snap ring  14  is mounted. A tension spring  15  having one end attached to the snap ring  14  and its other end attached to the arcuate curved portion  12 B of the quick disconnect connector  12 , urges the quick disconnect connector to a normally straight position with its cavity  12 A parallel with the longitudinal axis AL of the wrist unit  10 . In this position, a first one of the three holes  12 C in the arcuate curved portion  12 B of the quick disconnect connector  12  is parallel with the longitudinal axis of the wrist unit. 
   The generally cylindrical rear member  16  has a flat circular flange  16 A at a front end with a generally rectangular locking pin housing  16 B extending rearward a distance from the circular flange portion. A cylindrical cup-shaped lamination ring  16 C is attached to the back side of the flange  16 A by screws  17 . At least one of the screws  17  is an allen head cap screw  17 A. In the illustrated example, the lamination ring  16 C has an outer periphery configured to be engaged in a socket at the distal end of an arm prosthesis. 
   A locking pin bore  18  extends forwardly from the rear end of the locking pin housing  16 B and adjoins a shorter smaller diameter bore  19  which extends through the flat circular flange  16 A of the housing. The rear portion of the bore  18  is provided with internal threads  18 A and a plug  20  having a radial flange  20 A is threadedly engaged therein. A retractable rotation locking pin  21  having a larger diameter rear portion  21 A and a smaller diameter front portion  21 B is slidably disposed in the bore  18  of the locking pin housing  16 B with the smaller diameter front portion received in the smaller bore  19 . A compression spring  22  is engaged between the back end of the rotation locking pin  21  and the plug  20  to normally urge the rotation locking pin forward to a locking position. A rotation control cable  23  is attached at one end to the back end of the rotation locking pin  21  and extends through the spring  22  and the plug  20  engaged in the back end of bore  18 . The other end of the rotation control cable  23  is attached to a harness worn by the amputee (conventional in the art, and therefore not shown). The larger diameter rear portion  21 A of the rotation locking pin  21  is provided with a circumferential cam groove  21 C. The nose of a set screw  24  mounted in the side wall of the bore  18  rides in the cam groove  21 C ( FIG. 4 ). 
   A larger central bore  25  disposed parallel with, and spaced a distance from the locking pin bore  18  extends through the flat circular flange portion  16 A of the cylindrical rear member  16  and a distance rearwardly through the locking pin housing  16 B and adjoins a shorter smaller diameter bore  26  which extends through the rear end of the housing and is surrounded by a counterbore  26 A. A counterbore  25 A in the flange portion  16 A surrounds the central bore  25 . 
   A rotation locking member  27  having a flat circular flange  27 A at a front end and a tubular sleeve portion  27 B extending rearwardly therefrom and terminating in a smaller diameter rear portion  27 C is rotatably mounted in the central bore  25 , with the sleeve portion  27 B and smaller diameter rear portion  27 C journalled therein by a ball bearings  28  received in the counterbores  25 A and  26 A, respectively. A central bore  29  extends through the circular flange  27 A of the rotation locking member  27  and rearwardly thorough its tubular sleeve portion  27 B and terminates in a first short internally threaded bore  29 A near the rear end of the sleeve portion. A second short internally threaded bore  29 B extends inwardly from the rear end of the sleeve portion. A plug  30  having a radial flange  30 A is threadedly engaged the second bore  29 B in the back end of the sleeve portion  27 B of the rotation locking member  27  to retain the bearings  28 . A jamb screw  30 B is threadedly engaged the first bore  29 A to bear against plug  30  and prevent it from becoming unscrewed during rotation of the rotation locking member  27 . 
   The outer circumference of the circular flange  27 A of the rotation locking member  27  has external threads  27 D. The generally conical front member  11  carrying the quick disconnect connector  12  is attached to the rotation locking member  27  by threadedly engaging the internal threads  11 C in its open back end on the exterior threads  27 D of the rotation locking member flange  27 A. Thus, the conical front member  11  and the quick disconnect connector  12  rotate with the rotation locking member  27  as a unit, as described hereinafter. 
   As best seen in  FIG. 3 , the flat circular flange  27 A of the rotation locking member  27  has a plurality of equally spaced apart larger holes  27 E therethrough radially spaced a distance from the central bore  29  in a circular pattern for installing the screws  17  which attach the circular flange  16 A of the rear member  16  to the lamination ring  16 C. A semicircular groove  27 F is formed in the back side of the flange  27 A on the same radius as the larger holes  27 E. When the rotation locking member  27  is rotatably mounted in the central bore  25  of the locking pin housing  16 B, the flat circular flange  27 A of the rotation locking member is disposed in front of the flange portion  16 A of the locking pin housing and the allen head cap screw  17 A is received in the semicircular groove  27 F. The flange  27 A of the rotation locking member rotates relative to the flange portion  16 A of the locking pin housing and the allen head cap screw  17 A. 
   The cap screw  17 A engages one end of the groove  27 F to provide a stop surface to limit the rotational movement. In a preferred embodiment, the semicircular groove  27 F is dimensioned to allow more than 270° of rotational travel. For example, but not limited thereto, the semicircular groove  27 F may be dimensioned to provide a rotational travel limit of 290°. 
   Also, as best seen in  FIG. 3 , the flat circular flange  27 A of the rotation locking member  27  has a plurality of equally spaced apart small holes  27 G therethrough radially spaced a distance from the central bore  29  in a circular pattern aligned with the axis of the retractable rotation locking pin  21 . The small holes  27 G are sized to receive the smaller diameter front portion  21 B of the rotation locking pin  21  in its extended position (described hereinafter). The number and the angular spacing of the small holes  27 G is calculated to provide a plurality of indexed rotation locking positions. For example, there may be sixteen holes, equally spaced apart within a 360° circle to provide 14 indexed locking positions in a 290° rotational travel limit. 
   Referring additionally to  FIG. 5 , one end of a torsion spring  31  is engaged on the neck portion of the plug  30  at the back end of the sleeve  27 B of the rotation locking member  27  and is wound thereon with its other end engaged with on the neck portion of the plug  20  at the back end of the locking pin housing  16 B to allow the flat circular flange  27 A of the rotation locking member, and conical front member  11  attached thereto, to rotate in one direction (clockwise or counter clockwise) against the spring force of the torsion spring. 
   Referring again to  FIG. 2 , an elongate retractable flexion locking pin  32  is slidably received in the central bore  29  of the rotation locking member  27  and a compression spring  33  is disposed between the flexion locking pin and the plug  30  to normally urge the flexion locking pin forward to a locking position. A flexion control cable  34  is attached at one end to the back end of the flexion locking pin  32  and extends through the spring  33 , the jamb screw  301 B, and the plug  30  engaged in the back end of the sleeve portion  27 B of the rotation locking member  27 . The other end of the flexion control cable  34  is attached to a harness worn by the amputee (conventional in the art, and therefore not shown). In its locking position, the front end of the flexion locking pin  32  extends through the rotation locking member flange  27 A and is engaged in one of the three holes  12   c  in the arcuate curved portion  12 B at the back end of the quick disconnect connector  12 . The shank of the retractable flexion locking pin  32  is provided with a circumferential cam groove  32 A. The nose of a set screw  35  mounted in the side wall of the central bore  29  of the locking pin housing  16 B rides in the cam groove  32 A ( FIG. 4 ). The set screw  25  may be installed through an opening in the locking pin housing  16 B. 
   OPERATION 
   Rotation (Pronation and Supination) and Locking 
   The retractable rotation locking pin  21  is moved rearward against the force of the compression spring  22  to a retracted position by tensioning (pulling) and then relaxing the rotation control cable  23  a first time (first pull/relax action). During the first pull stroke, the cam groove  21 C moves rearward and the set screw  24  riding in the cam groove rotates the rotation locking pin  21  and when tension is relaxed, the set screw engages a stop surface in the cam groove such that the front end of the rotation locking pin is pulled away from the flange  27 A of the rotation locking member  27  and is maintained flush with the flat circular flange  16 A at a front end of the locking pin housing  16 B. 
   When the rotation locking pin  21  is in the retracted position, the rotation locking member  27  including its flange  27 A and sleeve portion  27 B, and the attached conical front member  11  carrying the quick disconnect connector  21 , may be manually rotated as a unit about the longitudinal axis AL more than 270° (for example 290°) in one direction (clockwise or counter clockwise) against the spring force of the torsion spring  31 . 
   When the rotation locking member  27  and the attached conical front member  11  carrying the quick disconnect connector  12  is manually rotated, the small holes  27 G in the rotation locking member flange  27 A pass over the retracted rotation locking pin  21  until the desired rotated position is achieved, and then the rotation locking pin  21  is moved forward to an extended locking position by tensioning (pulling) and then relaxing the rotation control cable  23  a second time (second pull/relax action). During the second pull stroke, the cam groove  21 C moves rearward and rotates the rotation locking pin  21  and when tension is relaxed, the set screw  24  riding in the cam groove is disengaged from the stop surface in the cam groove such that the front end of the rotation locking pin is urged forward by the compression spring  22  to be received in one of the plurality of small holes  27 G in the rotation locking member flange  27 A. If the front end  21 B of the rotation locking pin  21 , when released, engages the back surface of the flange  27 A between two adjacent holes, the torsion spring  31  will rotate the flange a sufficient distance to allow the front end of the rotation locking pin to snap into the closest small hole in the flange. 
   Thus, the conical front member  11  carrying the quick disconnect connector  12  may be rotated about the longitudinal axis AL of the wrist unit  10  and releasably locked at selected rotated positions relative to the arm prosthesis through a range exceeding 270° (for example 290°). The plurality of indexed rotation locking positions depends upon the number and angular spacing of the small holes  27 G. For example, there may be sixteen holes, equally spaced apart within a 360° circle to provide 14 indexed locking positions in the 290° rotational travel limit. 
   Flexion and Extension and Locking 
   The retractable flexion locking pin  32  is moved rearward against the force of the compression spring  33  to a retracted position by tensioning (pulling) and then relaxing the flexion control cable  34  a first time (first pull/relax action). During the first pull stroke, the cam groove  32 A moves rearward and the set screw  35  riding in the cam groove rotates the flexion locking pin  32 , and on the relax stroke, the set screw engages a stop surface in the cam groove to maintain the flexion locking pin in a retracted position. In its retracted or unlocked position, the front end of the flexion locking pin  32  is flush with the rotation locking member flange  27 A and is disengaged from the holes  12 C in the arcuate curved portion  12 B at the back end of the quick disconnect connector  12 . 
   When the flexion locking pin  32  is in its retracted position, the quick disconnect connector  12  may be manually pivoted about the pivot pin axis AT transverse to the longitudinal axis AL through an angle of from 0° to about 50° against the force of the tension spring  15 . When the quick disconnect connector  12  is released, the force of the tension spring  15  returns it to the normally straight position with its cavity  12 A parallel with the longitudinal axis AL of the wrist unit  10 . When the quick disconnect connector  12  is being manually pivoted about the pivot pin axis AT, one of the holes  12 C in the arcuate curved portion  12 B at its back end may be positioned to receive the front end of the retractable flexion locking pin  32  when it is released by a second pull/relax action. 
   To release the retractable flexion locking pin  32  from its retracted position to its locking position, it is moved rearward against the force of the spring  33  by tensioning (pulling) and then relaxing the flexion control cable  34  a second time (second pull/relax action). During the second pull stroke, the flexion locking pin  32  and its cam groove  32 A again moves rearward and rotates to a position so as to disengage the set screw from the stop surface of the cam groove, and on the relax stroke the flexion locking pin is urged forward by the force of the spring  33  to again assume its fully forward extended position engaged in one of the selected holes  12 C in the arcuate curved portion  12 B at the back end of the quick disconnect connector  12 . 
   Thus, the quick disconnect connector  12  may be locked in one of three locking positions relative to the longitudinal axis AL of the wrist unit  10 , and conical front member  11  carrying the quick disconnect connector  21 , may be rotated as a unit and locked at any of a plurality of indexed locking positions about the longitudinal axis AL. 
   The phrase “terminal device” has been used throughout this disclosure referring to items that may be releasably connected to the prosthetic wrist unit by attaching them in the cavity  12 A of the quick disconnect connector  12 . Such terminal devices have an end portion that is adapted to be received in the cylindrical cavity  12 A of the quick disconnect connector  12  and held therein by the detent ball and plunger mechanism  13 . In a preferred embodiment, the proximal end of the terminal device TD is attached to a cylindrical insert or adapter  40  that is received in the cavity  12 A and engaged by the detent ball and plunger mechanism  13 . A suitable commercially available insert known as a “Quick Disconnect Insert” is manufactured by Texas Assistive Devices of Brazoria, Tex., and distributed by the Hosmer Dorrance Corporation of Campbell, Calif. This insert is an internally threaded cylindrical fitting which may be attached to various terminal devices and has a plurality of circumferential radially spaced holes  41  through its side wall which allows the terminal device to be selectively positioned at various rotated positions about the axis of the cavity  12 A to provide still further selective positioning of the terminal device. It should be understood that terminal devices may be provided with a cylindrical end portion that is received in the cylindrical cavity of the present quick disconnect connector, and that other types of easily released terminal device retaining means may be used. 
   It should also be understood that a very wide variety of terminal devices may be provided for use with the present wrist unit, such as hooks, electric hands, tools, implements, and other specialty terminal devices. Typical examples of such specialty terminal devices include: personal care items (toothbrush, hairbrush, comb, etc.); kitchen utensils (knife, fork, spoon, whisk, spatula, etc); mechanic and carpentry tools (hammer, wrench, screwdriver, pliers, file, saw, nail holder, etc.); sporting and outdoor gear (fishing rod, reel crank adapter, golf club shank adapter, etc.) and gardening tools (spade, hoe, rake, etc.). 
   Although the wrist unit has been shown and described for purposes of example, as having a pair of cable operated locking pins, one for locking the front member at selected pronation and supination rotation positions, and a second for locking the quick disconnect connection at selected flexion and extension positions, it should be understood that other types of easily released locking means may be used. For example, the wrist unit may be provided with a single cable operated locking pin for locking the front member at selected pronation and supination rotation positions, as described above, and a pivoting lever locking member which releasably engages locking holes or notches in the arcuate curved portion  12 B at the back end of the quick disconnect connector  12  to control the flexion and extension functions. In another example, the wrist unit may be provided a first pivoting lever locking member which releasably engages locking recesses in the rotation locking member sleeve for locking the front member at selected pronation and supination rotation positions, and a second pivoting lever locking member which releasably engages locking holes or notches in the arcuate curved portion  12 B at the back end of the quick disconnect connector  12  to control the flexion and extension functions. 
   It should also be understood that a passageway may be formed through the back end of the cavity  12 A of the quick disconnect connector  12  and passageways may be formed through the front and rear members for receiving an electrical cable such that electrically operated or myoelectric terminal devices such as hooks, electric hands, other specialty terminal devices may be attached and operatively connected through the wrist unit. 
   While this invention has been described fully and completely with special emphasis upon preferred embodiments, it should be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.