Abstract:
The present invention is a continuous medical instrument adapter that safely provides a 180-degree torque force during a surgical procedure while accommodating the range of motion of the surgeon&#39;s hand during the surgical procedure. The drive mechanism of said adapter is capable of non-lubricated function, enabling it to be used in a medical environment and to be sterilized without loss of function.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a non-provisional application of and claims priority to U.S. Patent Application 61/873,475, filed on Sep. 4, 2013, which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention relates to the field of medical instruments and more specifically a medical instrument system adapter that safely provides a 180-degree torque force during a surgical procedure while accommodating the range of motion of the surgeon&#39;s hand during the surgical procedure. 
       BACKGROUND 
       [0003]    Continuous ratchet drive assemblies are known in the art and used for many applications in tools and machinery. A continuous ratchet drive assembly is characterized by the capability of the gear assembly to receive two input torque forces applied from two different directions and to translate the bi-directional input forces to an output force in a single direction. 
         [0004]    There are many situations in which it is desirable for a dual input torque to produce a single output torque because either a human hand or a gear cannot accommodate 180-degree rotation. Continuous ratchet motion is intended to prevent the loss of half the input torque motion. 
         [0005]    During a surgical procedure, it is desirable to accommodate the range of motion of a surgeon&#39;s hand and to use force effectively, by applying it to the instrument in order to avoid fatigue. However, it has not been possible to apply mechanical principals used for tools and other continuous ratchet drive assemblies to medical instruments. 
         [0006]    This is primarily because the instruments known in the prior art rely on entraining mechanisms which engage and slide mechanical components either over or past each other. Entraining mechanisms involve contact between two or more metal components and require lubrication. However, surgical instruments cannot use lubricants. Tools known in the prior art rely upon parts that generally require the use of lubricants or non-medical grade coatings. Additionally, the movement of these assemblies is not precise or stable enough to withstand medical procedures and subsequent sterilization. 
         [0007]    Without lubrication, medical instruments are prone to galling. Galling is a form of wear characterized by localized material transfer, removal, or formation of protrusions when two solid surfaces slide against each other. 
         [0008]    It is a problem known in the art that medical instruments must be non-galling and capable of functioning without lubricants. 
         [0009]    It is also a problem known in the art that all components and assemblies within a medical instrument must be safe, stable, and capable of high precision and smooth movement. 
         [0010]    For example, U.S. Pat. No. 5,931,062 (Marcovici &#39;062) discloses a continuous ratchet drive gear assembly having a reversing mechanism coupling two driving elements. This coupling forces the two ratchet gears together forcing them to always rotate in opposite directions so that one driving element entrains the shaft and the other driving element overruns the shaft. This causes the shaft to always turn in only one direction, regardless of the direction of rotation of the driving elements. The apparatus taught in Marcovici &#39;062 cannot be used in medical instruments because it requires entraining. 
         [0011]    The entraining mechanism taught by Marcovici &#39;062 involves substantial sliding contact between two metal elements requiring use of lubrication. 
         [0012]    For example, U.S. Pat. No. 5,176,038 (Inokuchi I &#39;038) and U.S. Pat. No. 5,259,259 (Inokuchi II &#39;259) disclose a mechanism to convert the linearly reciprocating motion of a radial handle into a unidirectional rotation of an output shaft through a racks and pinion combination utilizing toothed one-way clutches capable of selective deactivation to reverse output shaft rotation. During operation, the pinions slide in contact with a stationary plate, requiring application of lubricant between the metal surfaces that will be in contact. Similarly, the drive gears situated on shafts have metal surfaces that slide in contact with the bottom surface of the sun gear during rotation, which likewise requires application of a lubricant between the metal surfaces of the drive gears and the sun gear to prevent galling and corrosion. 
         [0013]    In another example, European patent 2,586,570 A1 (Wang &#39;570) discloses a manual tool having a bidirectional mechanical converting means. In one embodiment, a bidirectional mechanical conversion scheme with a reversing means comprising a reversing element sleeved on the main shaft with openings through which pawls can engage with the toothed inner surface to form a one-way clutch and an elastic element between each pair of pawls to keep the pawls diverging against the toothed inner surface. However, the use of an elastic element cannot be autoclaved and thus precludes use of the reversing mechanism for medical use. Further, an elastic element will not provide the required smooth rotational motion required for use in surgical procedures. 
         [0014]    It is desirable to adapt this concept to a medical tool, but there are many engineering issues to overcome, including the use of lubricants and the need to prevent galling. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  illustrates an exemplary embodiment of a continuous ratchet medical instrument (“CRMI”) adapter engaged and used with an output shaft and axial handle and directional arrows showing rotational direction of bi-directional input forces resulting in an output force in a single direction. 
           [0016]      FIG. 2  is a cross sectional isometric view of an exemplary embodiment of a CRMI adapter. 
           [0017]      FIGS. 3   a  through  3   c  illustrate a single embodiment of the CRMI adapter with the selector switch in three alternate positions: forward, reverse, and locked. 
           [0018]      FIG. 4  is an isometric cross sectional view of an exemplary embodiment of a CRMI adapter showing the central housing and locations of the thrust bearings and front and rear gear drive shafts. 
           [0019]      FIG. 5  is an isometric cross sectional view of an exemplary embodiment of a CRMI adapter that illustrates the use of thrust bearings. 
           [0020]      FIG. 6   a  shows a top and a perspective view of two embodiments of the rear drive thrust bearings. 
           [0021]      FIG. 6   b  shows a top view of a prior art bearing. 
       
    
    
     TERMS OF ART 
       [0022]    As used herein, the term “continuous” means capable of constant rotation in one direction without interruption or reversal. 
         [0023]    As used herein, the term “cylindrical housing” means a cylindrically shaped barrel having an inner and outer surface, which houses mechanical components capable of translating bi-directional rotation inputs into a single directional output. 
         [0024]    As used herein, the term “drive path” means the sequence of engagement of internal elements that transfers the input force into the output force. 
         [0025]    As used herein, the term “front” means a location more proximal to the user. 
         [0026]    As used herein, the term “non-rotating rear outer cap” means a stationary structure surrounding components capable of clockwise or counter-clockwise rotation. 
         [0027]    As used herein, the term “one-quarter inch square input shaft” means a shaft having a square inner area with sides one-quarter square inch in length. 
         [0028]    As used herein, the term “output shaft” means a shaft that can be received by an adapter capable of rotating an attached medical device in a pre-selected direction. 
         [0029]    As used herein, the term “rear” means a location more distal to the user. 
         [0030]    As used herein, the term “s-shaped aperture” means an s-shaped opening on an assembly, enabling components housed within the assembly to engage with components outside the assembly. 
       SUMMARY OF THE INVENTION 
       [0031]    The present invention is a medical instrument adapter apparatus. This apparatus includes a rotating outer collar having an internal square adapter, at least one non-rotating rear outer cap, a cylindrical housing secured by a rear end cap and a bi-directional motion converting mechanism. The bi-directional motion converting mechanism includes a front drive gear shaft with front drive gear shaft teeth, a front pawl housing, a rear drive gear shaft with rear drive gear shaft teeth, a rear pawl housing, a triple-square drive gear, two differential drive gear shafts, each including differential drive gears, and a one-quarter inch square input shaft. 
       DETAILED DESCRIPTION OF INVENTION 
       [0032]    For the purpose of promoting an understanding of the present invention, references are made in the text to exemplary embodiments of a continuous ratchet medical instrument adapter, 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 continuous drive ratchet mechanisms 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. 
         [0033]    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 the reference numerals in the various drawings, refer to identical or near identical structural elements. 
         [0034]    Moreover, the terms “about,” “substantially” or “approximately” as used herein may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. 
         [0035]      FIG. 1  illustrates an exemplary embodiment of a continuous ratchet medical instrument (“CRMI”) adapter in use with an output shaft  50  and axial handle  17 , with directional arrows D1 and D2 showing the rotational direction of bi-directional input forces resulting in an output force in a single direction. 
         [0036]    The embodiment shown in  FIG. 1  shows an output shaft  50  inserted into collar  75  and the three position selector switch  70 . Also illustrated in  FIG. 1  are multiple flushing holes  80  traversing the outer circumference of the non-rotating rear outer cap  12  for cleaning and sterilization purposes. Also shown in  FIG. 1  is an ergonomic, medically approved silicone sleeve  14  molded around the outer circumference of the cylindrical housing  11  for positive user grip in the operating room, and the grooved front end cap  13 . 
         [0037]    The CRMI adapter  10  is not a complete driver but an adapter used in conjunction with a medical ratcheting driver, non-ratcheting driver, medical torque wrench or other medical driving device. The CRMI adapter  10  is specifically designed for medical use, having no plastic parts, thus allowing sterilization in an autoclave. 
         [0038]    The CRMI adapter  10  makes a clicking sound to help the doctor monitor rotation of the device. 
         [0039]      FIG. 1  illustrates an embodiment of the CRMI adapter  10  capable of one handed and two-handed operation. For one-handed operation, the user grasps the axial handle  17  attached to the outer surface of the one-quarter inch square input shaft  16 . For two handed operation, the user places one hand on the silicone sleeve  14 , and places the other hand on the axial handle  17  attached to the outer surface of the one-quarter inch square input shaft  16 . 
         [0040]      FIG. 2  is a cross section view of an exemplary embodiment of a CRMI adapter  10 .  FIG. 2  shows a one-quarter inch square input shaft  16  perpendicular to the grooved front end cap  13 , the front pawl housing  20  with integrally formed front drive gear shaft  30  having front drive gear shaft teeth  32 . The front drive gear shaft  30  is operatively connected to the rear drive gear shaft  40  through the first differential gear shaft  18   a  having the first differential drive gear  15   a  and the second differential drive gear shaft  18   b  with differential gear  15   b.    FIG. 2  also illustrates the rear pawl housing  25  with integrally formed rear drive gear shaft  40  having rear drive gear teeth  38 . 
         [0041]      FIG. 2  also shows the location of multiple flushing holes  80  traversing the outer circumference of the non-rotating rear outer cap  12  with a three position selector switch  70 , the triple square drive gear  60  at the junction of the rear drive gear shaft  40  and output shaft  50 , and the internal one-quarter inch square adapter  68  with circular collar  75  situated about the outer circumference of output shaft  50 . 
         [0042]      FIGS. 3   a  through  3   c  illustrate a single embodiment of the CRMI adapter  10  with the three position selector switch  70  in three alternate positions: forward, reverse, and locked. 
         [0043]    As illustrated in  FIGS. 3   a ,  3   b , and  3   c , a user toggles the three position selector switch  70  to select the direction of output rotation. The three positions are indicated relative to their orientation to the collar  75 : F (forward towards the collar  75 ) for clockwise rotation, R (reverse) for counterclockwise, and L (locked central position). 
         [0044]      FIGS. 3   a - 3   c  illustrate the one-quarter inch square input shaft  16 . They also illustrate the integrally formed front drive gear shaft  30  with front drive gear shaft teeth  32  visible in the figures through the s-shaped aperture  21  of the front drive pawl housing  20 . The first front pawl  41  and second front pawl  42  are situated within the front pawl housing  20 .  FIGS. 3   a - 3   c  also show the first differential thrust bearings  53  and differential drive gears  15 . The first rear pawl  43  and second rear pawl  44  are situated within the rear pawl housing  25 , which has an s-shaped aperture  21 . The integrally formed rear drive gear shaft  40  with rear drive gear shaft teeth  38  is visible through the rear pawl housing  25 . 
         [0045]    In the embodiment shown in  FIG. 3   b , the three position selector switch  70  is in the forward position (pushed towards the collar  75 ). In the forward position, two modes of operation are possible: one-handed operation and two-handed operation. 
         [0046]    As shown in the embodiment illustrated in  FIG. 3   a , during operation with the three position selector switch  70  in the forward position, rotation of the one-quarter inch square input shaft  16  in a clockwise direction drives the front pawl housing  20  to rotate in a clockwise direction. The first front pawl  41  is not engaged with the front drive gear shaft teeth  32 , while the second front pawl  42  is engaged with the front gear drive shaft teeth  32  situated in the front drive gear shaft  30 , and drives the first differential gear  15   a  and the second differential gear  15   b . The first and second differential gears  15   a  and  15   b  drive the rear pawl housing  25  to rotate in a counter-clockwise direction. The first rear pawl  43  is not engaged on the rear drive gear shaft teeth  38  situated within the rear drive gear shaft  40 , and the second rear pawl  44  is ratcheting, i.e., engaged with the rear drive gear shaft teeth  32 , but not driving the rear drive gear shaft  40 . The rear gear drive shaft  40  is attached to and drives the triple-square drive gear  60 , which drives the output shaft  50  in a clockwise direction. 
         [0047]    During operation with the three position selector switch  70  in the forward position as shown in the embodiment in  FIG. 3   a , rotation of the one-quarter inch square input shaft  16  in a counter-clockwise direction drives the front pawl housing  20  to rotate in a counter-clockwise direction. The second front pawl  42  is engaged with the front gear drive shaft teeth  32 , but not driving the front drive gear shaft  30 , while the first front pawl  41  is not engaged with the front drive gear shaft teeth  32 . The first and second differential gears  15   a  and  15   b , respectively, drive the rear pawl housing  25  to rotate in a clockwise direction. The first rear pawl  43  is not engaged on the rear drive gear shaft teeth  38 , while the second rear pawl  44  is engaged with the rear drive gear shaft teeth  38  and drives the rear drive gear shaft  40 . The rear gear drive shaft  40  is attached to and drives the triple-square drive gear  60 , which drives the output shaft  50  in a clockwise direction. 
         [0048]    In the embodiment shown in  FIG. 3   a , one handed operation translates a clockwise rotation of the one-quarter inch square input shaft  16  into a clockwise rotation of the output shaft  50 , and two handed operation translates a counter-clockwise rotation of the one-quarter inch square input shaft  16  into clockwise rotation of the output shaft  50 . 
         [0049]    In the embodiment shown in  FIG. 3   b , the three position selector switch  70  is in the reverse position (pushed away from the collar  75 ). In the reverse position, two modes of operation are possible: one-handed operation and two-handed operation. 
         [0050]    As shown in the embodiment illustrated in  FIG. 3   b , during operation with the three position selector switch  70  in the reverse position, rotation of the one-quarter inch square input shaft  16  in a clockwise direction drives the front pawl housing  20  to rotate in a clockwise direction. The second front pawl  42  is not engaged with the front gear drive shaft teeth  32 , while the first front pawl  41  is ratcheting, i.e., engaged with the front drive gear shaft teeth  32 , but not driving the front drive gear shaft  30 . The differential gears  15   a  and  15   b  drive the rear pawl housing  25  to rotate in a counter-clockwise direction. The second rear pawl  44  is not engaged on the rear drive gear shaft teeth  38 , while the first rear pawl  43  is engaged with the rear drive gear shaft teeth  38  and drives the rear drive gear shaft  40 . The rear gear drive shaft  40  is attached to and drives the triple-square drive gear  60 , which drives the output shaft  50  in a counter-clockwise direction. 
         [0051]    As illustrated by the embodiment shown in  FIG. 3   b , during operation with the three position selector switch  70  in the reverse position, rotation of the one-quarter inch square input shaft  16  in a counter-clockwise direction drives the front pawl housing  20  to rotate in a counter-clockwise direction. The first front pawl  41  is engaged with the front gear drive shaft teeth  32  and drives the front drive gear shaft  40 , while the first front pawl  41  is not engaged with the front drive gear shaft teeth  32 . The differential gears  15   a  and  15   b  drive the rear pawl housing  25  to rotate in a clockwise direction. The second rear pawl  44  is not engaged with the rear drive gear shaft teeth  38 , while the first rear pawl  43  is ratcheting, i.e., engaged on the rear drive gear shaft teeth  38 , but not driving the rear drive gear shaft  40 . The rear gear drive shaft  40  is attached to and drives the triple-square drive gear  60 , which drives the output shaft  50  in a counter-clockwise direction. 
         [0052]    In the embodiment shown in  FIG. 3   b , one handed operation translates a counter-clockwise rotation of the one-quarter inch square input shaft  16  into a counter-clockwise rotation of the output shaft  50 , and two handed operation translates a clockwise rotation of the one-quarter inch square input shaft  16  into a counter-clockwise rotation of the output shaft  50 . 
         [0053]    In the embodiment shown in  FIG. 3   c , the three position selector switch  70  is in a central position relative to the collar  75 . In the locked position, only the one-handed mode of operation is possible, enabling the entire instrument to perform the same function as an extension to a driver. 
         [0054]    As illustrated in the embodiment shown in  FIG. 3   c , during operation in the locked position, a clockwise rotation of the one-quarter inch square input shaft  16  does not result in rotation of the front pawl housing  20 . The first front pawl  41  is touching the front drive shaft gear teeth  32  and could ratchet, while the second front pawl  42  is engaged with the front drive gear shaft teeth  32  and could drive the front drive gear shaft  30 . The differential gears  15   a  and  15   b  could drive the rear pawl housing  25 . The first rear pawl  43  is touching the rear drive gear shaft teeth  38  and could ratchet, while the second rear pawl  44  is engaged with the rear drive gear shaft teeth  38  and could drive the rear drive gear shaft  40 . The results in no rotational movement of the front pawl housing  20  or rear pawl housing  25  upon clockwise rotation of the one-quarter inch square input shaft  16  because the front pawl housing  20  and rear pawl housing  25  are locked in place by the second front pawl  42  and the second rear pawl  44 . Clockwise rotation of the one-quarter inch square input shaft  16  drives the triple square drive gear  60  to rotate in a clockwise direction, resulting in clockwise rotation of the output shaft  50 . 
         [0055]    As illustrated in the embodiment shown in  FIG. 3   c , during operation in the locked position, a counter-clockwise rotation of the one-quarter inch square input shaft  16  does not result in rotation of front pawl housing  20 . The second front pawl  42  is touching the front drive shaft gear teeth  32  and could ratchet, while the first front pawl  41  is engaged with the front drive gear shaft teeth  32  and could drive the front drive gear shaft  30 . The differential gears  15   a  and  15   b  could drive the rear pawl housing  25 . The second rear pawl  44  is touching the rear drive gear shaft teeth  38  and could ratchet, while the first rear pawl  43  is engaged with the rear drive gear shaft teeth  38  and could drive the rear drive gear shaft  40 . The result is no rotational movement of the front pawl housing  20  or rear pawl housing  25  upon counter clockwise rotation of the one-quarter inch square input shaft  16  because the front pawl housing  20  and rear pawl housing  25  are locked in place by the first front pawl  41  and the first rear pawl  43 , respectively. A counter clockwise rotation of the one-quarter inch square input shaft  16  drives the triple square drive gear  60  to rotate in a counter-clockwise direction, resulting in a counter-clockwise rotation of the output shaft  50 . 
         [0056]    In the embodiment shown in  FIG. 3   c , clockwise rotation of the one-quarter inch square input shaft  16  results in clockwise rotation of the output shaft  50  at the same speed as the one-quarter inch square input shaft  16 . In the embodiment shown in  FIG. 3   c , counter-clockwise rotation of the one-quarter inch square input shaft  16  results in counter-clockwise rotation of the output shaft  50  at the same speed as the one-quarter inch square input shaft  16 . 
         [0057]      FIG. 4  is an exploded cross section view of an exemplary embodiment of a CRMI adapter  10  showing the center housing  57  and locations of the rear drive thrust bearings  51 , front drive thrust bearings  52 , the first differential drive thrust bearings  53  adjacent to the differential drive gear  15   a  and the second differential drive thrust bearings  54  adjacent to the differential drive gear  15   b,  and the center housing  57  with first center differential drive thrust bearings  55  and second center differential drive thrust bearings  56 . 
         [0058]      FIG. 5  is an isometric cross section view of an exemplary embodiment of a CRMI adapter  10  which illustrates the use of thrust bearings to facilitate reliability in the operating room and to prevent galling between the metal surfaces 
         [0059]      FIG. 5  shows the front drive thrust bearings  52  in a ring configuration about the outer circumference of the one-quarter inch square input shaft  16 . As thrust bearings  52  are situated between the outer surface of the one-quarter inch square input shaft  16  and inner surface of the front end cap  13  (not labeled), they prevent direct contact between the components.  FIG. 5  also illustrates the integrally formed front drive shaft  30  running through the front pawl housing  20 . In the embodiment shown in  FIG. 5 , the front drive gear shaft teeth  32  are engaged with second front pawl  42  (not shown) and the first front pawl  41  is not engaged. 
         [0060]      FIG. 5  further shows the first differential drive thrust bearing  53  in a ring configuration about the outer circumference of the differential drive gear shaft  18   a  to facilitate smooth rotation of the first differential drive gear  15   a  about the differential drive gear shaft  18   a.    FIG. 5  also shows the second differential drive thrust bearing  54  in a ring configuration about the outer circumference of the differential drive gear shaft  18   b  to facilitate smooth rotation of the second differential drive gear  15   b  about the differential drive gear shaft  18   b.    
         [0061]      FIG. 5  further shows the rear drive thrust bearings  51  in a ring configuration about the rear pawl housing  25  with integrally formed rear drive gear shaft  40 . In the embodiment shown in  FIG. 5 , the rear drive gear shaft teeth  38  are engaged with the first rear pawl  43  (not shown) and the second rear pawl  44  is not engaged.  FIG. 5  shows the triple square drive gear  60  situated at the junction of the rear drive gear shaft  40  and output shaft  50 . 
         [0062]    As illustrated in  FIG. 5 , the CRMI adapter  10  secures specialized medical tools internally by means of an internal bit locking mechanism (BMI patent), and has no external screwdriver bit holder. 
         [0063]      FIG. 6   a  shows a top and a perspective view of two embodiments of the rear drive thrust bearings  51 . The use of numerous thrust ball bearings in a ring configuration instead of a standard sleeve design (seen in  FIG. 6   b ) facilitates use of the CRMI adapter  10  in a non-lubricated environment. Eliminating the use of lubricants also enables sterilization of the CRMI adapter  10  in an autoclave.