Abstract:
A prosthetic device ( 12 ) and liner ( 14 ) form a prosthetic system ( 10 ) that can substantially mimic the cosmetic and functional qualities of a human hand. A harness ( 22 ) is adapted to fit about a remnant portion ( 16 ) of a hand ( 18 ). The harness has an opening ( 26 ) for accommodating the liner ( 14 ). A moveably mounted opposition member ( 24 ) is supported by the harness ( 22 ) and sensors ( 60, 62 ) positioned about the harness ( 22 ) detect a force exerted by an area ( 40 ) in proximity to the hypothenar eminence of remnant portion. Once a force is detected by either sensor ( 60, 62 ) a signal is communicated to a controller ( 70 ) which activates a motor ( 100 ) causing motion of the opposition member ( 24 ).

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates generally to a prosthetic device for a hand. More specifically, the invention relates to a partial hand prosthesis that substantially replicates the functionality and look of fingers of a human hand. Still more particularly, the invention provides an electro-mechanical fitted and partial hand prosthetic device that senses motion on an area substantially proximate the hypothenar eminence of the remnant portion of a hand in order to activate the motion of a prosthetic finger member moveably attached to a prosthetic harness surrounding the hand.  
       BACKGROUND OF THE INVENTION  
       [0002]     Prior attempts have been made to provide a prosthetic device that simulates the look and functionality of the human hand. Most such attempts fall into two camps: cosmetic type prosthesis and active type prosthesis. Cosmetic type prosthetic devices are generally passive and provide no active functionality. Thus, with a cosmetic limb the patient often resorts to using a working limb to accomplish routine tasks. This is not generally desired as it unnatural and can lead to complications associated with overuse syndrome of the working limb.  
         [0003]     An active type prosthesis typically comprises a socket mounted to a patient&#39;s arm with a coupling attached to the socket. The coupling provides an attachment point for a terminal device or task specific tools and different tools can be used depending on the particular task to be accomplished. Prosthetic devices of this type are functional but not cosmetically pleasing as they generally don&#39;t attempt to mimic the look and feel of a real human hand.  
         [0004]     A subclass of the active type class of prosthesis is the electro-mechanical type which tries to replicate both the look and function of the human hand. Such devices typically rely on muscle and tendon forces in other parts of the arm in order to activate the grasping function of the fingers. For example, the upper arm muscle may be flexed in order to cause a set of artificial finger member to come together or grasp an item. However, with such prior art electro-mechanical prosthetic devices, the normal physiologically unconscious use of the device is difficult as the patient may need to concentrate the action of the muscles or tendons providing the operating force.  
         [0005]     Partial hand amputations where the thumb remains intact present a common type of limb deficiency. Prior art prosthetic devices adapted to such cases pose significant disadvantages due to overall lack of adjustability during use. In most cases, patients pre-position the device with their working hand to place fingers extending from the device in a position accommodating a proposed task. Even when the prosthetic device is designed with an opposition post, i.e. a member that resists the motion of one or more working digits of the hand, the lack of feedback to the patient requires the patient to reposition the device for each new task.  
         [0006]     The cases involving partial hand amputations with thumb intact have not, until the present invention, been treated as a special class of limb loss for purposes of prosthetic treatment. No prior art prosthetic is known to effectively utilize the residual thumb and neighboring structures of the remnant portion of the hand in order to help the patient adjust the grip of the device without use of a functional limb. 
     
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS  
       [0007]     The present invention is illustrated by way of example and not limitation in the figures of the accompanying drawings in which like references indicate similar elements, and in which:  
         [0008]      FIG. 1  shows a partial hand prosthetic system according to the invention;  
         [0009]      FIG. 2  shows is a detailed illustration of a liner which can be used as part of the partial hand prosthetic system of  FIG. 1 ;  
         [0010]      FIG. 3  shows the detailed illustration of a prosthetic device which can be used as part of the partial hand prosthetic system of  FIG. 1 ;  
         [0011]      FIGS. 4   a - 4   c  illustrate the operation of an opposition member with respect to a remnant thumb;  
         [0012]      FIG. 5  illustrates the prosthetic system of the present invention on a remnant portion of a hand;  
         [0013]      FIG. 6  is a block diagram illustrating the various electro-mechanical components within a prosthetic device according to the invention;  
         [0014]      FIG. 7  shows the details of on exemplary embodiment of a drive subsystem used to move one or more prosthetic fingers of a prosthetic device according to the invention; and  
         [0015]      FIG. 8  is a detailed mechanical of one exemplary embodiment of a motor, gear head and drive gear arrangement of a prosthetic device according to the invention.  
     
    
     DETAILED DESCRIPTION  
       [0016]     Referring now to the figures,  FIG. 1  shows a prosthetic system, denoted generally as  10 , consisting of prosthetic device  12  and liner  14  which are designed to fit over a remnant portion  16  of a hand  18 . As shown, hand  18  maintains a working thumb thus remnant portion  16  forms a partial hand and prosthetic system  10  is intended to provide a partial hand prosthesis as described herein. In this regard, prosthetic device  12  includes a harness  22  to which one or more prosthetic fingers  24  are movably attached. In a more general sense, prosthetic fingers  24  are designed to move in a direction towards thumb  20  when prosthetic system  10  is worn by a user to a point where it opposes the movement of thumb  20 . As such, the terms “prosthetic fingers”, “finger” or “opposition members” can and will be used interchangeably throughout.  
         [0017]     Liner  14  provides a means for attaching prosthetic device  12  to remnant portion  16  of hand  18 . Preferably, liner  14  provides a snug slip-free fit over remnant portion  16  to securely hold prosthetic device  12  in place (as shown in  FIGS. 4   a ,  4   b  and  5 ). In this regard, it has been found that a silicone liner works well although it is contemplated that a suitable liner can be made from other materials all within the scope of the invention. In any event, as shown, liner  14  is shaped to accommodate prosthetic device  12  about opening  26  which is shaped to accept liner  14  as well as remnant portion  16 .  FIG. 5  shows the entire prosthetic system  10  worn by a user with remnant portion  16  wearing liner  14  and within opening  26  of the prosthetic device  12 .  
         [0018]      FIG. 2  illustrates further details of liner  14  suitable for use in a prosthetic system according to the invention. Liner  14  provides an opening  30  for inserting the remnant portion  16  of a hand  18  during fitting. Of course, it is contemplated that liner  14  will form a relatively snug fit about a user&#39;s hand and that liner  14  including opening  30  and other features thereof may be sized accordingly to accommodate various hand sizes and remnant forms. End periphery  32  of liner  14  is closed forming a glove-like structure for surrounding a remnant portion. In the particular configuration shown, liner  14  includes a second opening  46  for accommodating a thumb. Alternatively, and for cases were a portion of a patient&#39;s thumb has been lost, an artificial thumb extender  44  can be attached to the liner  14  to extend opening  46  into a structure substantially approximating a human thumb. Liner also includes areas  40  and  42  which are near an area known as the hypothenar eminence near the lateral portion of a human hand. Finally, liner  14  provides an attachment point  48  to which the prosthetic device  12  can be secured. The invention is not limited to any specific means of attaching the prosthetic device  12  to the liner  14  although it is preferred that prosthetic device  12  be securely attached to the liner  14 .  
         [0019]      FIG. 3  shows the prosthetic device  12  in more detail. Harness  22  provides a structure to which the various electro-mechanical components for a prosthesis according to the invention can be attached. Opposition members  24  are moveably attached to frame  50  which can rotate about shaft member  52  in the direction of arrow A. Shaft member  52  is provided to allow the rotational motion of the opposition members  24  about harness  22 . As shown, attached to harness  22  are sensors  60  and  62  which are positioned about an area where the hypothenar eminence of a remnant portion of a hand inserted into opening  26  of harness  22  would be. Each sensor is communicably attached to a controller, represented by  70 , which receives signals from the sensors  60 ,  62  corresponding to motion of the remnant portion within harness  22 . The controller  70  is shown attached to the outside of harness  22  although the controller  70  can likewise be placed in other areas about the harness  22  consistent with the invention. Another block  72  is shown attached to harness  22  and is representative of a power source, such as rechargeable batteries, used to provide energy to the various electro-mechanical components of the prosthetic device  12 . This would include controller  70  and motor (not shown in  FIG. 3 ) to drive the shaft member  52  and cause opposition members  24  to pivot about harness in the direction of arrow A.  
         [0020]      FIGS. 4   a ,  4   b  and  4   c  illustrate the operation of a prosthetic system, such as prosthetic system  10 , according to the invention. In particular, the lateral edge  80  of a remnant portion  16  of a hand  18  is shown. As shown, remnant portion  16  includes a remnant thumb  82  which is functioning normally. In  FIG. 4   b , the prosthetic device has been fitted over liner  14  which, in turn, has been fit over remnant portion  16 . A shaft member  52  is mechanically coupled to the opposition member  24  and operated by a motor (not shown in  FIG. 4   b ). As shown, sensors  60  and  62  are arranged proximate to area  80  which is in the vicinity of the hypothenar eminence of the remnant portion  16 . In this position, the sensor  60 ,  62  are situated to detect the motion of the hypothenar eminence which causes the movement of opposition member  24 . The fact that motion of the hypothenar eminence causes motion of opposition members  24  provides a prosthetic device that is physiologically natural for a patient using a prosthetic system according to the invention.  
         [0021]      FIG. 4C  shows the opposition member  24  moving in the direction of remnant thumb  82  after motion has been activated. This motion more naturally mimics the function of a human finger opposing the thumb during normal use. Thus, the invention provides a prosthetic system that is both functional and cosmetically similar to a human hand.  
         [0022]      FIG. 5  shows an alternate view of a prosthetic system according to the invention. Harness  22  of prosthetic device  12  is slipped over liner  14  and held securely in place by strap  110  looping through opening  112  and holding with attachment point  48 . Of course, other ways of holding prosthetic device  12  in place may be utilized. Sensor  60  is communicably coupled via signal line  120  to a controller (not shown in  FIG. 5 ) that actuates motor  100  to drive shaft  102  and thereby operate shaft member  52  coupled to opposition members  24 . In this way, motion detected by sensor  60  causes the movement of opposition members  24 .  
         [0023]     It is contemplated that a variety of electro-mechanical components and device designs may be employed in order to achieve a prosthesis embodying a prosthetic device and system according to the present invention. Therefore, presented herein is but a single embodiment of various electro-mechanical devices and components which have been found to provide the objects and advantages of the invention. As such,  FIG. 6  is a block diagram for a prosthetic device, denoted generally as  140 , including the various electro-mechanical devices and components according to a general embodiment of the invention. A microprocessor  150  acts as the central processing unit of the prosthetic device  140  and receives an input from touch pads  152  via signal path  151 . Touch pads  152  are positioned within a prosthesis structure, such as harness  22 , where movements of the hypothenar eminence can be detected and communicated to microprocessor  150 . As shown, power is derived from a set of rechargeable batteries  160  which, in combination with charger port and power switch  162  as well as battery charger  164 , are capable of providing energy to various electro-mechanical components of the prosthetic device  140 .  
         [0024]     Prosthetic device  140  also includes a DC motor  170  operably coupled to microprocessor  150  via path  171 . Thus, microprocessor  150  may actuate DC motor  170  following the receipt of a detect signal from touch pads  152 . DC motor  170  may, in turn, operate gear head  172  to cause the motion of finger member  174 . As shown, DC motor  170 , gear head  172  and finger  174  are supported by bracket  176 .  
         [0025]     Referring to  FIG. 7 , a block diagram for a prosthetic device according to the invention with the details of a drive system, denoted generally as  200 , is shown. Specifically, controller  70  is communicably coupled to touch pads  152   a  and  152   b . In addition, controller  70  is provided with port  202  to receive programming instructions from computer  210  via signal path  212 . In this way, the controller  70  can be programmed to configure various features of the prosthetic device. For example, computer  210  can be used to set the sensitivity of the touch pads  152   a ,  152   b . In addition, computer  210  can be used to set the direction and speed of the DC motor  170  in order to effect the action of fingers  174 . Also, the limit for the stall current of the DC motor  170  can be set. Of course, other variable and features of the prosthetic device can be changed, modified or set using computer  210  though port  202 .  
         [0026]     As shown, DC motor  170  is in operative communication with planetary gear head  220  which receives a first torque force from the output  219  of DC motor  170  and converts it to a second torque force suitable for driving driven shaft  226  and providing sufficient torque to move fingers  174 . This may be accomplished by setting the gear ratio between the input and output of the planetary gear  220  in order to provide a sufficient torque of the driven shaft  226 . While various gear ratios can be used, it has been found that a high ratio with respect to the input and out is satisfactory. In particular, according to one specific embodiment, a gear ratio of 1024:1 has been found to provide a sufficient torque force at the driven shaft  226  while preventing back drive of the motor  170 . Of course, other ratios may be employed within the scope of the present invention.  
         [0027]     The planetary gear head  220  is operably coupled to gear spurs  222  and  224  which transfer the torque generated by DC motor  170  and gear head  220  to the driven shaft  226  coupled to fingers  174 . Other transfer methods may also be employed including, for example, a three gear spur arrangement as shown in  FIG. 8 . In this way, power provided by the DC motor  170  can be used to move fingers  174 . Of course, it is contemplated that variations of the drive subsystem  200  will be apparent to those of ordinary skill in the art and, therefore, such variations should be considered within the scope of the invention.  
         [0028]     A mechanical layout of a drive system suitable for use in a prosthetic device according to the invention is shown in more detail in  FIG. 8 . The drive system, denoted generally as  250 , uses a motor  252  to operate gear head  254  along shaft  256 . Frame  260  supports these various components as gears  270  transfer mechanical power from the motor  252  to finger members  274  attached to rod  272 . A power connector  280  supplies energy from a power source (not shown in  FIG. 8 ) to the motor  252 .  
         [0029]     As indicated above, various devices and components can be used in order to achieve a prosthetic device having the various features and advantages of the present invention. Table 1 below provides some a material list for some of the electrical and mechanical devices which have been found satisfactory in reducing to practice a suitable prosthesis according to the invention:  
                                 TABLE 1                           List of parts and part numbers for devices and       components used in an exemplary prosthetic       device according to the invention.            Part Num   Part Name   Quantity   Vendor               118396   Motor, 6 V DC   1.0   Maxon       218418   Gearhead, Planetary Type,   1.0   Maxon           1024:1       UPB563450/PCM   Battery, 3.7 Volt, Lithium   2.0   Ultralife           Ion       B84-0500/0550   Battery Charger, Lithium   1.0   Energy           Ion, 1000 mA       Access       910-2050-05   Index Finger   2.0   MIL-E       970-2060-01 REV C   Hand Mounting Assembly   1.0   MIL-E       970-2060-10 REV B   Gear Cover   1.0   MIL-E       970-2060-20   Motor Shaft   1.0   MIL-E       970-2060-30   Bearing   2.0   MIL-E       970-2060-05 REV C   Axle   1.0   MIL-E       KJ08412K   Tie Wrap   1.0   Dennison       FIT-221B, 3/32   Heat Shrink, Black   1.0   Alpha       16P-3100   Charging Jack   1.0   Mouser       910-2020-01   Power Shutoff Plug,   1.0   MIL-E           Modified       N/A   Mounting Screws,   4.0   Global           #4-40 × .125, PFH, SS       N/A   PlateScrews,   4.0   Global           #6-32- × .125, PPH, SS                  
 
         [0030]     It should be understood that modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification and the claims. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.