Abstract:
An internal adapter for use in torque-limiting handles for interchangeable orthopedic tools contains a slidable collar component, house component, retaining ring, spring, driver component, cover and cam which engages a torque-limiting mechanism. A plurality of securing ball mechanisms releasably secure an orthopedic tool in the adapter, while a configuration of chamfered surfaces centrally stabilize the tool. A plurality of guiding chamfers located in a driver component rotationally secures the orthopedic tool.

Description:
FIELD OF INVENTION 
     The present invention relates to the field of medical devices, and more specifically to a self-locking internal adapter for securing medical tools. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of an exemplary embodiment of an internal adapter for a torque-limiting driver. 
         FIG. 2  illustrates an exemplary embodiment of a collar component for an internal adapter. 
         FIG. 3  illustrates an exemplary embodiment of a tapered housing for an internal adapter. 
         FIG. 4  is an exemplary self-locking mechanism for an internal adapter. 
         FIGS. 5   a  and  5   b  illustrate an exemplary embodiment of a driver for an internal adapter. 
         FIGS. 6   a  and  6   b  illustrate an exemplary cam for an internal adapter. 
         FIG. 7  illustrates an exemplary internal adapter for a torque-limiting driver. 
         FIGS. 8   a ,  8   b  and  8   c  illustrate an exemplary internal adapter engaging a tool shaft. 
         FIG. 9  illustrates an exemplary internal adapter assembled with a torque-limiting mechanism. 
         FIG. 10  illustrates an exemplary internal adapter with torque-limiting mechanism assembled inside a handle. 
         FIG. 11  illustrates a torque-limiting mechanism engaging an exemplary internal adapter. 
         FIG. 12  is an exterior view of an exemplary internal adapter with torque-limiting mechanism assembled inside a handle. 
     
    
    
     TERMS OF ART 
     As used herein, the term “adapter” refers to a component of an orthopedic tool handle which engages a tool, 
     As used herein, the term “chamfer” refers to a beveled, angled or tapered edge which engages the edge of a second component to create a secured junction. 
     As used herein, the terms “flattened portion” or “partially flattened portion” refer to a cylindrical surface having an area with a curvature less than that of the cylindrical curvature. A flattened or partially flattened portion may contain a single area or multiple areas of lesser curvature. 
     As used herein, the term “securing ball” refers to any structure or combination of structures which may engage a securing ball detent aperture. A securing ball may be any shape, including, but not limited to, spherical, quasi-spherical, rounded, oblong, ellipsoidal, and combinations of these and other shapes capable of engaging a securing ball detent aperture. 
     BACKGROUND 
     Adjustment tools are used in orthopedic surgery to tighten and adjust mechanical components within orthopedic devices. For example, screwdrivers, spreaders, pliers, hammers, cutters and other tools may be used to adjust screws, pins, rods and other orthopedic devices. The adjustment tools for adjusting these orthopedic devices must be highly stable to allow for precise adjustments, and many types of adjustments may be needed. 
     In order to save space on an operating room instrument table or in a sterilization kit, different orthopedic tools may be designed to be interchangeable with a single handle. For example, it is known in the art to fashion tools of varying lengths with shafts that may be inserted into a single tool handle. 
     As a result, a typical orthopedic tool may actually be a system of three components: a handle, an adapter and a tool. Generally; the handle and the adapter are structurally integrated and permanently attached to each other. Tools are adapted for insertion into the adapter. 
     Adapters for securing medical tools, specifically medical tools with a square or hexagonal shaft, to handles are known in the art. Every adapter has some sort of channel or orifice to receive the tool, and a locking mechanism to secure the tool in place. The function and simplicity of operating the locking mechanism are critical. Even incremental improvements in a locking mechanism can be critical to the outcome of a surgery. 
     Tools must be compact to allow an orthopedic surgeon to perform adjustments to orthopedic devices and other tasks within the confined space of various body regions. 
     Tools must also be versatile, and it is desirable to have as many tools as possible adapted for use with a single adapter and handle. 
     Adapter components are likely to come in contact with bodily fluids and other contaminants during medical procedures. Any contours, grooves and other hard-to-reach surfaces need to be carefully cleaned and sterilized. Exposed attachment components are also more likely to be bumped or inappropriately forced in an attempt to attach a medical tool. As a result, exposed attachment components are frequently damaged. 
     It is desirable to have an adapter for securing medical tools to handles which reduce the number of exposed components and surfaces. 
     It is desirable to have an apparatus for securing and grasping tools which is as compact as possible so that surgeons can operate within the limited spaces and contours of various regions of the body. 
     It is critical to have an adapter for securing medical tools in place as effectively and simply as possible. 
     U.S. Pat. No. 7,343,824 discloses a torque-limiting driver for orthopedic tools having an internal cam and external tool adapter. It is desirable to provide an internal adapter for a torque-limiting driver handle with an internal cam. 
     SUMMARY OF THE INVENTION 
     The present invention is an internal adapter for use in torque-limiting handles for interchangeable orthopedic tools. An internal adapter contains a slidable collar component, house component, retaining ring, spring, driver component, cover and cam which engages a torque-limiting mechanism. A plurality of securing ball mechanisms releasably secure an orthopedic tool in the adapter, while a configuration of chamfered surfaces centrally stabilizes the tool. A plurality of guiding chamfers located in a driver component rotationally secures the orthopedic tool. 
     DETAILED DESCRIPTION OF INVENTION 
     For the purpose of promoting an understanding of the present invention, references are made in the text to exemplary embodiments of an internal adapter for a torque limiting driver for orthopedic tools, only some of which are described herein. It should be understood that no limitations on the scope of the invention are intended by describing these exemplary embodiments. One of ordinary skill in the art will readily appreciate that alternate but functionally equivalent structures and materials may be used. The inclusion of additional elements may be deemed readily apparent and obvious to one of ordinary skill in the art. Specific elements disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one of ordinary skill in the art to employ the present invention. 
     It should be understood that the drawings are not necessarily to scale; instead, emphasis has been placed upon illustrating the principles of the invention. In addition, in the embodiments depicted herein, like reference numerals in the various drawings refer to identical or near identical structural elements. 
       FIG. 1  is an exploded view of an exemplary self-locking internal adapter  100  for a torque limiting driver. Internal adapter  100  contains collar component  10 , tapered housing  20 , retaining ring  30 , spring  35 , cover  40 , driver  50 , bearings  65   a ,  65   b  and cam  70 . Securing balls  60   a ,  60   b ,  60   c ,  60   d  are also shown. When assembled, internal adapter is configured to be secured and housed in torque-limiting driver  90 . 
     As illustrated in  FIG. 1 , collar component  10 , tapered housing  20 , retaining ring  30 , spring  35 , cover  40 , driver  50 , bearings  65   a ,  65   b  and cam  70  are shown as separately manufactured components. In further exemplary embodiments, two or more of collar component  10 , tapered housing  20 , retaining ring  30 , spring  35 , cover  40 , driver  50 , bearings  65   a ,  65   b  and cam  70  may be integrally manufactured or machined. In still further exemplary embodiments, one or more of collar component  10 , tapered housing  20 , retaining ring  30 , spring  35 , cover  40 , driver  50 , bearings  65   a ,  65   b  and cam  70  may be integrally manufactured with torque-limiting driver  90 . 
     As illustrated in  FIG. 1 , retaining ring  30  has gap  31 . In further exemplary embodiments, retaining ring  30  may be a complete ring without gaps. 
     Bearings  65   a ,  65   b  are shown as standard ball bearings known in the art. In further exemplary embodiments, bearings  65   a ,  65   b  may be any bearings known in the art. 
       FIG. 2  illustrates an exemplary embodiment of collar component  10 . Collar component  10  contains external collar base  11  and tubular sliding portion  14 , with tool receiving channel  16  extending the length of collar component  10 . In the exemplary embodiment shown, tubular sliding portion  14  contains securing ball apertures  15   a ,  15   b  ( 15   c ,  15   d  not shown). Securing ball apertures  15   a ,  15   b , ( 15   c ,  15   d  not shown) are equidistant and symmetrically arranged around tubular sliding portion  14 . 
     In further exemplary embodiments, tubular sliding portion  14  may contain additional securing ball apertures. While equidistant and symmetrically arranged securing ball apertures provides for greater securing and stability, in further exemplary embodiments, securing ball apertures may be asymmetrically arranged and positioned at varying distances around tubular sliding portion  14 . 
     Securing ball apertures  15   a ,  15   b ,  15   c ,  15   d  contain a contoured inner surface which creates a diameter smaller than the diameter of securing balls  60   a ,  60   b ,  60   c ,  60   d  (not shown) at the innermost edge of securing ball apertures  15   a ,  15   b ,  15   c ,  15   d . Securing balls  60   a ,  60   b ,  60   c ,  60   d  (not shown) are therefore freely rotatable within securing ball apertures  15   a ,  15   b ,  15   c ,  15   d  but may not pass through securing ball apertures  15   a ,  15   b ,  15   c ,  15   d . In further exemplary embodiments, securing ball apertures  15   a ,  15   b ,  15   c ,  15   d  may contain a lip, rim, ridge or other structure which narrows the diameter of the innermost edge of securing ball apertures  15   a ,  15   b ,  15   c ,  15   d  to prevent securing balls  60   a ,  60   b ,  60   c ,  60   d  (not shown) from passing through. 
       FIG. 2  also shows tool receiving channel  16  extending the length of collar component  10 . In the exemplary embodiment illustrated, tool receiving channel  16  is round tubular with a smooth surface and consistent internal diameter. In further exemplary embodiments, tool receiving channel may contain projections or grooves or may have an inconsistent internal diameter to accommodate a specifically manufactured tool. 
     The rear end of tubular sliding portion  14  contains protuberance  17  and groove  18 , both of which span the external circumference of tubular sliding portion  14 . 
       FIG. 3  is an exemplary embodiment of tapered housing  20 . As shown in  FIG. 3 , tapered housing  20  contains external house base  21  with threaded driver-engaging stem  22 . Interior collar channel  23  extends the length of tapered housing  20 . 
       FIG. 4  illustrates collar component  10  joined with tapered housing  20   b  to create a self-locking mechanism. Collar component  10  is slidably engaged with the inner surface of interior collar channel  23 . 
     Securing balls  60  each correspond with one of securing ball apertures  15 . Securing ball apertures  15  have contoured inner surface  19 , so that the inner diameter of securing ball apertures  15  is slightly less than that of securing balls  60 , so that securing balls  60  do not fall through securing ball apertures  15  but remain freely rotatable in securing ball apertures  15 . The interior surface of interior collar channel  23  creates a cover over securing ball apertures  15  to prevent securing balls  60  from disengaging securing ball apertures  15 . 
     In other exemplary embodiments, securing ball apertures  15  may contain lips, ridges, protuberances, contours or other structures which create a smaller inner diameter and prevent securing balls  60  from falling through securing ball apertures  15 . 
     Interior collar channel  23  also contains tapered surface  25 . The inner diameter of interior collar channel  23  is smaller near the opening of interior collar channel  23  and progressively larger inward of the opening. 
     As spring  35  exerts outward force on collar component  10 , securing balls  60  in securing ball apertures  15  are forced to align with the outer-most, or narrowest, part of tapered surface  25 . Retaining ring  30 , in groove  18 , is also pushed against stop ridge  27  of tapered housing  20 , which prevents collar component  10  from being forced too far outward by spring  35 . 
     As an orthopedic tool would be pushed into tool receiving channel  16 , securing balls  60  freely rotate within securing ball apertures  15 , allowing the tool shaft to proceed through tool receiving channel  16 . When a tool shaft is pushed into tool receiving channel  16 , securing balls  60  are forced slightly towards the inner-most, or wider, part of tapered surface  25 . 
     If the tool is pulled out from tool receiving channel  16 , securing balls  60  are forced toward the outer-most, or narrowest, part of tapered portion  25 , so that securing balls  60  are no longer able to freely rotate. The tool shaft is therefore locked within tool receiving channel  16 . 
     To remove a tool from tool receiving channel  16 , external collar base  11  is pressed inward. Spring  35  is compressed, and collar component  10  slides inward within interior collar channel  23 . Securing ball apertures  15  align with the inner-most, or widest, part of tapered portion  25 , which increases the volume of securing ball apertures  15 . Securing balls  60  are then able to freely rotate within securing ball apertures  15 , allowing the tool shaft to be pulled out of tool receiving channel  16 . 
       FIGS. 5   a  and  5   b  illustrate an exemplary driver  50 . Driver  50  has front threaded portion  51  which corresponds with threaded driver-engaging stem  22  (not shown) of tapered housing  20  (not shown). Tool guiding channel  54  extends the length of driver  50 . Handle-engaging projection  97  projects from the rear of driver  50 . 
     Driver  50  also has bearing shaft surfaces  55   a ,  55   b , which correspond to bearings  65   a ,  65   b , (not shown) respectively, and three flattened surfaces  53   a ,  53   b ,  53   c  (not shown), between bearing shaft surfaces  55   a ,  55   b , which correspond to the inner flattened surfaces of cam  70  (not shown). 
     In the exemplary embodiment shown, tapered rear portion contains two bearing shaft surfaces  55   a ,  55   b  and three flattened surfaces  53   a ,  53   b ,  53   c  (not shown). In further exemplary embodiments, tapered rear portion may contain additional bearing shaft surfaces to correspond to the number of bearings being used. Tapered rear portion may also contain a different number of flattened surfaces in order securely engage a cam being used. 
     Internally, driver  50  contains spring house  56 , which secures spring  35  (not shown) between driver  50  and collar component  10  (not shown). Leading chamfer  57  transitions tool guiding channel  54  to a smaller internal diameter with guiding chamfers  58 . In the exemplary embodiment shown, tool guiding channel  54  contains eight double square guiding chamfers  58 . In further exemplary embodiments, guiding chamfers may be hexagonal or other configuration, and tool guiding channel  54  may contain more or fewer guiding chamfers  58  to correspond to a specific tool shaft or other guiding chamfer configuration. 
     As illustrated in  FIG. 5   b , guiding chamfers  58  do not start at the edge of leading chamfer  57  and contain transition chamfer  59 . As will be illustrated in FIGS.  8   a ,  8   b  and  8   c , the proportional distance of transition chamfer  59  of guiding chamfers  58  from leading chamfer  57  is a critical dimension. 
       FIGS. 6   a  and  6   b  illustrate an exemplary embodiment of cam  70 . As illustrated, cam  70  contains driver channel  71  which extends the length of cam  70 . Driver channel  71  contains flattened surfaces  73   a ,  73   b ,  73   c  which correspond to flattened surfaces  53   a ,  53   b ,  53   c  (not shown) of driver  50  (not shown). When engaged, flattened surfaces  73   a ,  73   b ,  73   c  and  53   a ,  53   b ,  53   c  (not shown) prohibit rotation of driver  50  (not shown) within cam  70 . 
     Cam  70  also contains external contours with a plurality of inclined areas  74  interposed between gradual sloped areas  75  and  77  that culminate in elevated areas  76 . As will be illustrated in  FIGS. 9 ,  10  and  11 , roller  201  (not shown) of torque limiting mechanism  200  (not shown) will roll slowly up and down surfaces  75  and  77  when a maximum torque or pressure omit is reached. 
     In the exemplary embodiment shown, cam  70  contains six elevated areas  76  with six inclined areas  74 . In further exemplary embodiments, cam  70  may contain any number of contours, and contours may be more or less rounded depending on the roller or torque assembly being used. 
       FIG. 7  is an exemplary embodiment of assembled internal adapter  100  without cover  40  (not shown) for use with tool shaft  82 . Bearings  65   a ,  65   b  and cam  70  are secured around driver  50 , with rear portion  97  of driver  50  protruding from bearing  65   b . Driver  50  secures collar component  10  and tapered housing  20 . 
     At one end of tool shaft  82  is handle-engaging portion  87 . The opposite end of tool shaft  82  may contain any tool known in the art. 
     As illustrated in  FIG. 7 , groove  81  transitions tool shaft  82  to handle-engaging portion  87 , which is squared with flat surfaces  85   a ,  85   b  ( 85   c ,  85   d  not shown). In further exemplary embodiments, handle-engaging portion  87  may be hexagonal or any other configuration known in the art. 
     Flat surfaces  85   a ,  85   b  ( 85   c ,  85   d  not shown) each have a corresponding chamfer  83   a  ( 83   b ,  83   c ,  83   d  not shown) and are separated by rounded transitions  84   a ,  84   b  ( 84   c ,  84   d  not shown), each also having a corresponding chamfer  86   a ,  86   b  ( 86   c ,  86   d  not shown). The distance from the center of groove  81  to the edge of chamfer  86   a  (labeled as A in  FIGS. 8   a ,  8   b  and  8   c ) is a critical distance, as will be shown in  FIGS. 8   a ,  8   b  and  8   c.    
       FIGS. 8   a ,  8   b  and  8   c  illustrate an exemplary embodiment of internal adapter  100  engaging tool shaft  82 . 
     As illustrated in  FIG. 8   a , tool shaft  82  is partially inserted into internal adapter  100 . Chamfers  86  engage securing balls  60  and force them into the larger area created by tapered portion  25 . Securing balls  60  are able to freely rotate in securing ball apertures  15  (not shown) and tool shaft  82  is able to pass through tool receiving channel  16  (not shown). The distance from the center of securing balls  60  to leading transition chamfer  59  of guiding chamfers  58  is labeled as B. 
     In the exemplary embodiment shown, distance A is equal to distance B. It is critical that distances A and B are equal to provide quick and secure locking of tool shaft  82  in internal adapter  100 . 
     In  FIG. 8   b , tool shaft  82  is further in tool receiving channel  16  (not shown), with groove  81  aligned with securing balls  60  and chamfers  86  aligned with leading transition chamfer  59  of guiding chamfers  58 . In order to fully secure tool shaft  82  in internal adapter  100 , flat surfaces  85  (not shown) must properly align with guiding chamfers  58 . Securing balls  60  do not engage tool shaft  82  in this position, allowing tool shaft  82  to freely rotate within tool receiving channel  16  and be properly oriented to engage guiding chamfers  58 . 
       FIG. 8   c  illustrates tool shaft  82  secured within internal adapter  100 . Tool shaft  82  is aligned so that handle-engaging portion  87  is aligned with guiding chamfers  58  (not shown) to prevent rotational movement of tool shaft  82  in driver  50 . Securing balls  60  are positioned along the portion of tapered surface  25  of tapered housing  20  creating a smaller volume for securing ball apertures  15  (not shown) and engage tool shaft  82  to prevent movement of tool shaft  82  out of handle  90  (not shown). 
     If tool shaft  82  is pulled outward from handle  90  (not shown), securing balls  60  are unable to rotate within securing ball apertures  15  (not shown) and prevent movement of tool shaft  82 . To release tool shaft  82 , collar component  10  is pushed inward toward handle  90  (not shown) to compress spring  35 . Securing balls  60  are aligned with the portion of tapered surface  25  creating a larger volume for securing ball apertures  15  (not shown). Securing balls  60  are therefore able to freely rotate in securing ball apertures  15  (not shown), allowing tool shaft  82  to be removed from internal adapter  100 . 
     In the exemplary embodiment shown in  FIG. 8   c , chamfers  83  corresponding with flattened surfaces  85  (not shown) correspond to and engage leading transition chamfers  59  (not shown) to stabilize tool shaft  82  centrally in driver  50 . 
       FIGS. 9 and 10  illustrate an exemplary internal adapter  100  fully assembled and connected with torque-limiting mechanism  200 . In the exemplary embodiment shown in  FIG. 9 , torque-limiting mechanism is a torque-limiting mechanism as known in the art and includes spacers  220 , locking screws  230  with plug screw  235 , springs  210 , plungers  205  and rollers  201  with rollers  201  adapted to engage cam  70 . Cam  70  is secured on driver  50  with bearing  65   a  visible and bearing  65   b  (not shown) removed. In further exemplary embodiments, torque-limiting mechanism  200  may be any torque limiting mechanism known in the art, containing similar or equivalent components, and which provides a structural component adapted to engage cam  70 . 
     As illustrated in  FIG. 10 , internal adapter  100 , when secured in a handle, is stable between the rollers  201 . Cover  40  secures internal adapter  100  to handle  90  and fits around assembled collar component  10 , tapered housing  20  and driver  50 . 
     Springs  210  exert pressure on plungers  205  to keep rollers  201  in physical engagement with cam  70  while a tool is in use. Rollers  201  are able to rotate against cam  70 , easily slide over inclined areas  74  (not shown), sloped areas  75  and  77  (not shown) and elevated areas  76  (not shown). Once the desired torque is reached, springs  210  release pressure, causing a gap between rollers  201  and cam  70 . 
     Both torque limiting mechanism  200  and internal adapter  100  are contained within handle cavity  92  (not shown) of handle  90 , which in the exemplary embodiment shown has a T-shape. As illustrated, torque limiting mechanism  200  includes spacer  220 , locking screw  230 , spring  210 , plunger  205  and roller  201 , with roller  201  adapted to engage cam  70 . In further exemplary embodiments, torque limiting mechanism  200  may be any torque limiting mechanism known in the art which provides a structural component adapted to engage cam  70 . 
       FIG. 11  more closely shows the interaction of internal adapter  100  and torque limiting mechanism  200 . Driver  50  is secured to tapered housing  20 , with collar component  10  and securing balls  60  secured in interior collar channel  23  (not shown) by retaining ring  30  and forced outward by spring  35 . Bearings  65   a ,  65   b  and cam  70  are around driver  50 , with flattened surfaces  53   a ,  53   b ,  53   c  (not shown) of driver  50  engaging flattened surfaces  73   a ,  73   b ,  73   c  (not shown) of cam  70 . Driver  50  is therefore unable to rotate within cam  70 . 
     Cover  40  is shown secured to handle  90 , thereby securing internal adapter  100  to handle  90 . Torque-limiting mechanism  200  is also secured to handle  90 . 
     When a tool is inserted in internal adapter  100 , flat surfaces on the tool engage guiding chamfers  58 , which center and stabilize the tool and prevent rotational movement of the tool within tool receiving channel  16 . Similarly, the flattened surfaces on driver  50  engage the inner flattened surfaces of cam  70  to prevent rotational movement of driver  50 , and therefore the tool, within cam  70 . 
     When turning handle  90 , springs  210  of torque limiting mechanism  200  exert force on plungers  205  and push rollers  201  in physical contact with cam  70 . Cam  70  is therefore moved with handle  90  as handle  90  is rotated. Rotation of handle  90  and cam  70  causes driver  50  and ultimately the tool to rotate. Once the desired torque is reached, springs  210  no longer push on plungers  205 , causing rollers  201  to lose physical contact with cam  70 . As handle  90  is rotated, rollers  201  glide across the surface of cam  70 , while cam  70  remains stationary. Handle  90  is therefore rotated while cam  70 , driver  50 , and, ultimately; the tool, remain stationary. Bearings  65   a ,  65   b  aid handle  90  is smoothly rotating about driver  50  when rollers  201  are not engaged with cam  70 . 
       FIG. 12  is an external view of internal adapter  100  assembled in handle  90  with torque limiting mechanism  200  (not shown). As illustrated, external collar base  11 , external house base  21  and the outer-most surface of cover  40  are the only components of internal adapter  100  visible outside handle  90 . In further exemplary embodiments, cover  40  may be entirely contained within handle  90 . In still further exemplary embodiments, house  20  may be more recessed within handle  90 , with external collar base  11  the only protruding portion of internal adapter  100 . In still further embodiments, internal adapter  100  may be entirely encased by handle  90 .