Abstract:
A surgical tool handle for releasable connection to a surgical tool is described. The tool handle comprises a housing providing a linkage chamber extending from a proximal housing grip end to a distal housing tool end for receiving a tool. A tool linkage is partially housed within the linkage chamber. That way, manipulation of the tool linkage causes a locking pawl to pivot with respect to the housing from an open configuration ready to receive a tool for attachment to the housing to a closed configuration engageable with the tool supported at the distal housing tool end.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. provisional application Ser. No. 61/310,903, filed on Mar. 5, 2010. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to surgical tools for aiding in the installation of orthopedic prostheses in patients. More particularly, the present invention relates to an easily sterilizable handle assembly for use with a surgical tool in preparing a bone site, and for use in installing a prosthesis in the bone. 
     BACKGROUND OF THE INVENTION 
     Complicated surgical tool handles typically have crevices and recesses that are difficult to clean with relative ease without disassembly into separate component parts. Tool handles that are not properly cleaned and sterilized increase the risk of disease transfer from patient to patient. This is especially true following the emergence of certain “prions” that are not killed by normal hospital sterilization. A prion is a type of infectious agent made only of protein. 
     Further, in surgical procedures in which access to the treatment site is limited, it is difficult to use current solutions without subjecting the patient to repeated abrasion and tissue trauma when inserting and extracting surgical instruments. 
     Additionally, the insertion of a prosthetic implant is often problematic, and the orientation of the implant in a properly prepared recess is often critical to minimize recovery time of the patient. Still further, once the appropriate position of the tool is selected, it is often difficult to ensure that the position does not change upon insertion of the assembly through the incision. 
     It would be beneficial, therefore, to have an orthopedic tool handle that easily connects to a surgical tool, and that is readily adjustable, disassemblable, and cleanable. Additionally, it would be beneficial if the tool were partially disassembled for cleaning without the need to completely the component parts of the handle from each other. Further, it would be beneficial to have a handle that enables the surgeon to better maneuver and position a tool head to facilitate preparing a bone site to receive a prosthetic implant in a particular angular orientation. 
     SUMMARY OF THE INVENTION 
     A surgical tool handle aids a surgeon in controlling the use of a tool during surgery, for example, during preparation of a femoral cavity for reception of hip joint prosthesis. The present invention is such a surgical tool handle, but adapted to facilitate sterilization. That way, the present toll handle allows for partial disassembly to facilitate sterilization, while remaining loosely intact to prevent the separation of component parts from the device as a whole. 
     The present surgical handle assembly comprises a housing providing a linkage chamber housing a tool linkage. The housing extends from a proximal housing grip end to a distal housing tool end for receiving a tool. The tool linkage comprises: a handle lever attached to the housing by a proximal housing pivot pin to thereby provide a first pivotable connection between the tool linkage and the housing; a locking pawl attached to the housing by a distal housing pivot pin to thereby provide a second pivotable connection between the tool linkage and the housing; an inverted linkage comprising a proximal inverted linkage end and a distal inverted linkage end connected by a first free pivot pin to the handle lever to thereby provide a third pivotable connection; and a main linkage comprising a proximal main linkage end connected by a second free pivot pin to the proximal inverted linkage end adjacent to the proximal housing end in a fourth pivotable connection and a distal main linkage end connected by a third free pivot pin to the locking pawl adjacent to the distal housing end in a fifth pivotable connection. 
     During use, the handle lever is pivotable about the proximal housing pivot pin from a first, opened position spaced a maximum distance along a range of motion from the proximal housing end to a second, closed position spaced at a closer distance along the range of motion relative to the proximal housing end than the first position. This movement causes the inverted linkage, connected to the handle lever by the first free pivot pin, to move in a proximal direction to thereby move the main linkage, connected to the inverted linkage at the second free pivot pin, in a proximal direction toward the proximal housing end. This causes the locking pawl, connected to the distal main linkage end by the third free pivot pin, to pivot with respect to the housing on the distal housing pivot pin from an open configuration ready to receive a surgical tool for attachment to the housing to a closed configuration engageable with a surgical tool supported at the distal housing tool end. 
     In that respect, the present handle assembly is an adapted instrument used to prepare the cavity of the femur when the iliac crest is the main obstacle. For that reason, the handle assembly is adapted for an anterior approach where the offset from the coronal plane is large enough access to the femur even though the iliac crest prevents direct access to it. 
     These features of the present invention will be apparent upon consideration of the following detailed description in connection with the following drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a rasp handle assembly  10  according to the present invention connected to a surgical tool  12 . 
         FIG. 2  is a side, cross-sectional view of the rasp handle assembly  10  shown in  FIG. 1  connected to a surgical tool  12 . 
         FIG. 3  is a plan view of the rasp handle assembly  10  of  FIG. 1  connected to the surgical tool  12  and showing alternate right and left angled embodiments. 
         FIG. 4  is a side, cross-sectional view of the rasp handle assembly  10  shown in  FIG. 1  prior to connection to the surgical tool  12 . 
         FIG. 5  is a cross-sectional view taken along line  5 - 5  of  FIG. 2 . 
         FIG. 6  is a cross-sectional view taken along line  6 - 6  of  FIG. 2 . 
         FIG. 7  is a broken-away view of the rasp handle assembly  10  shown in  FIG. 1  prior to connection to the surgical tool  12 . 
         FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 2 . 
         FIG. 9  is an illustration of the present handle assembly  10  connected to a rasp  12  during use in a minimally invasive hip surgery procedure where the iliac crest is blocking direct access to the femur. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning now to the drawings,  FIGS. 1 to 4  and  7  illustrate a surgical handle assembly  10  according to the present invention. The handle assembly  10  is shown connected to a surgical tool, such as a broach or rasp  12  for performing a minimally invasive hip replacement surgery. Other tools useful with the handle assembly  10  include, but are not limited to, reamers, angled drivers, twist drills, flexible drills, cannulated drills, bayonet drills, bayonet taps, drill guides, adjustable angle drill guides, taps, and cannulated taps. 
     The handle assembly  10  generally comprises a linkage train  14  disposed within a housing  16 . The housing  16  had a length that extends from a proximal housing section  18  to a distal neck section  20  with an intermediate housing section  22  there between. The intermediate housing section  22  comprises spaced apart right and left side walls  24  and  26  extending upwardly from a bottom wall  28  to an upper opening  30 . 
     A unique feature of the present handle assembly  10  is that the intermediate housing section  22  is further comprised of an axial housing region  22 A aligned along the axis A-A and an angled housing region  225 . As particularly shown in  FIG. 3 , the angled housing region  225  radiates in an outwardly direction with respect to the axis A-A, in either a leftward direction along an axis B-B or a rightward direction along axis B′-B′ (shown in dashed lines). The angle α between axis B-B or B′-B′ and axis A-A ranges from about 5° to about 35°, preferably about 15° to about 25°, and more preferably about 20°. This construction provides the intermediate section  22  having a linkage chamber with a generally U-shaped cross-section perpendicular to axes A-A and B-B (B′-B′) extending from the proximal housing section  18 . The bottom wall  28  is planar along the proximal housing section  18  and both the axial and angled regions  22 A,  22 B of the intermediate housing section  22 . 
     A pair of aligned slots  32 A,  325 , serving as catch recesses, extends from the upper opening  30  part-way into the height of the respective side walls  24 ,  26 . A recess  34  is provided in the bottom wall  28  vertically below the aligned slots  32 A,  325 . A pair of side-by-side vertical bores  36 A,  365  ( FIG. 3 ) extend from the recess  34  to the upper edges of the side walls  24 ,  26  proximally, but adjacent to the respective aligned slots  32 A,  325 . The significance of the aligned slots  32 A,  325 , the recess  34 , and the vertical bores  36 A,  36 B will be discussed hereinafter. 
     The intermediate housing section  22  seamlessly meets the proximal housing section  18  having a generally rectangular shape in cross-section perpendicular to the axis A-A provided by the right and left side walls  24 ,  26 , the bottom side wall  28  and an upper side wall  38 . The upper side wall  38  is contoured to provide a finger grip region  40  adjacent to a ledge  42 . A strike plate  44  is connected to the end of the proximal housing section  18 . 
     The distal neck section  20  of the housing extends in a downwardly direction and angles back to align along a third axis C-C or C′-C′ ( FIG. 3 ) parallel to, but spaced from, the axis A-A. The angle β ( FIG. 1 ) between both of the axes A-A and B-B (B′-B′) and the axis C-C ranges from about 50° to about 80°, preferably about 60° to about 70°, and more preferably about 65°. The angular relationship of axis C-C is the same with both axes A-A and B-B because the latter, while angled with respect to each other, are aligned along a similar plane with respect to axis C-C. 
     In that manner, the right and left side walls  24 ,  26  forming the intermediate housing section  22  seamlessly extend distally and downwardly to form the distal neck section  20  of the housing. However, the bottom wall  28  ends spaced from the distal neck section  20 . This provides a distal lower open slot  46  ( FIG. 2 ) that is vertically below that portion of the upper opening  30  residing in the distal neck section  20 . At the end of the distal neck section  20 , the right and left side walls  22 , meet a rectangularly-shaped portion with curved edges  48  supporting a nose  50 . 
     As shown in  FIGS. 1 to 4 , the linkage train  14  resides inside the housing  16  and comprises a handle lever  52 , an inverted linkage  54 , a main linkage  56  and a locking pawl  58 . The handle lever  52  includes a distal head  60  supporting a main fulcrum pin  62  having opposed ends extending outwardly from the handle lever head in an orientation aligned perpendicular to axis A-A. The opposed ends of pin  62  are received in the respective slots  32 A,  32 B while a proximal end  52 A of the handle lever  52  rests on ledge  42 . Moving in a proximal direction from the main fulcrum pin  62 , the handle lever head  60  divides into spaced apart side walls  60 A,  603  providing a gap there between. 
     The inverted linkage  54  is a relatively short member extending from a downwardly angled proximal end  64  ( FIG. 6 ) to a reduced cross-section distal end  66  ( FIG. 8 ). The distal end  66  of the inverted linkage  54  is received in the gap provided between the opposed side walls  60 A,  603  of the handle lever head  60 . There, a pin  68  secures the inverted linkage  54  to the handle lever head  60  in a pivotable relationship. 
     The main linkage  56  is an elongate member having a proximal section  56 A with its end received in a gap formed by spaced apart side walls  64 A,  643  ( FIG. 6 ) of the downwardly angled proximal end  64  of the inverted linkage  54  and being pivotably connected thereto by a pin  70 . The proximal section  56 A of the main linkage  56  is aligned with the axial region  22 A of the intermediate housing section  22  along axis A-A. From there, and in a similar manner as the overall contour of the intermediate housing section  22 , the main linkage  56  bends into an intermediate angled portion  56 B that coincides with the angled region  223  of the intermediate housing section along axis B-B until it forms into a distal fork portion  56 C. The distal fork portion  56 C extends in a downwardly direction at an angle similar to that of the angled housing portion  20  along axis C-C. 
     A pair of opposed lateral protrusions  72  extend outwardly from the proximal section  56 A of the main linkage  56  adjacent to its pivotable connection with the downwardly angled proximal end  64  of the inverted linkage  54 . When the linkage train  14  resides inside the housing  16 , these protrusions  72  are in a closely spaced, but movable relationship with the inner surfaces of the right and left housing side walls  24 ,  26 . That way, they help stabilize the linkage train  14  inside the housing  16  as the linkage train is manipulated to lock onto and release from a rasp tool  12 , as will be described in detail hereinafter. 
     The locking pawl  58  is another relatively short member extending from a reduced cross-section proximal end  74  to an upwardly extending hook  76 . The proximal end  74  of the locking pawl  58  is received in the distal fork portion  56 C of the main linkage  56 . A pin  78  secures the main linkage  56  to the locking pawl  58  in a pivotable relationship. Further, a housing pivot pin  80  extends through the locking pawl  58  at an intermediate location between the proximal end  74  and the upwardly extending hook  76 . The opposed ends of the pivot pin  80  are received in openings in the right and left housing side walls  24 ,  26  flush with the respective outer surfaces thereof. That way, the hook  76  of the locking pawl  58  is pivotable about a range of motion vertically below the reinforcing nose  50  of the housing  16 . 
     With the linkage train  14  residing inside the right and left side walls  24 ,  26  and the bottom wall  28  comprising the housing  16 , the main linkage  56  extends from the axial housing region  22 A of the intermediate housing section  22  at a position adjacent to the proximal housing section  18 , along the angled housing region section  22 B and to the distal housing neck section  20 . The distal neck section  20  is where the main linkage  56  pivotably connects to the locking pawl  58 . The opposite, proximal section  56 A of the main linkage  56  pivotably connects to the inverted linkage  54  in the intermediate housing section  22  adjacent to the proximal housing section  18  and at a location proximal of the aligned slots  32 A,  32 B in the respective housing side walls  24 ,  26 . 
     The inverted linkage  54  is disposed vertically above the main linkage  56 . The downwardly angled proximal end  64  of the inverted linkage  54  accommodates this vertically aligned relationship. As previously discussed, the opposed distal end  66  of the inverted linkage  54  is pivotably connected to the handle lever  52  at the pivot pin  68 , which is proximal of the main fulcrum pin  62  pivotably received in the respective slots  32 A,  32 B of the right and left side walls  24 ,  26  of the housing  16 . 
     As particularly shown in  FIG. 8 , a linkage lock mechanism  82  comprises a base plate  82 A having a pair of opposed upwardly extending blocking pins  82 B,  820  supported thereon. As further illustrated in  FIGS. 1 to 4 , when the linkage train  14  resides in the housing  16  with the main fulcrum pin  62  seated in the slots  32 A,  32 B, the linkage lock mechanism  82  is moved into position with the blocking pins  82 B,  82 C residing in the bores  36 A,  36 B in the respective side walls  24 ,  26 . With the base plate  82 A seated in the housing recess  34 , the distal ends of the pins  82 B,  82 C extend upwardly beyond the upper edges of the side walls  24 ,  26 . These extending portions of pins  82 B,  82 C block the fulcrum pin  62  and, consequently, the linkage train  14  from being removed from inside the housing  16 . It should be noted that the pivotable connection between the locking pawl  58  and the distal neck section  20  of the housing  16  at pin  80  prevents the linkage train  14  from being completely separate from the housing. 
     Because they are supported on side walls comprising the housing, the fulcrum pin  62  and the pivot pin  80  are referred to in the claims as “housing pivot pins”. That is regardless whether they are intended to be removable from their supported relationship with the housing, as in the case of fulcrum pin  62 , or not, as in the case of pivot pin  80 . The other pivot pins  68 ,  70  and  78  are referred to as “free pivot pins”. That is because those latter pivot pins provide for pivotable movement between the various linkage members they connect together without being supported on the housing. 
     In use, the handle assembly  10  is detachably connectable to a surgical tool  12 , such a broach or rasp, by lifting the handle lever  52  in an upwardly direction, away from the housing ledge  42 . Manipulation is aided by the finger recess  40 . As the proximal end of the handle lever  52  move upwardly, its distal head  60  pivots on the fulcrum pin  62  received in the aligned slots  32 A,  32 B. This movement causes the pivot pin  68  to move upwardly and distally to a position essentially vertically aligned directly above the fulcrum pin  62 . In turn, the inverted linkage  54  moves in an upwardly and distal direction, toward the housing neck section  20 . As the inverted linkage  54  moves, the main linkage  56 , pivotably connected thereto at pin  70 , follows along. This causes the distal fork portion  56 C of the main linkage  56  to move both forwardly or proximally and upwardly between the housing side walls  24 ,  26 . In turn, the locking pawl  58  pivots on the housing pivot pin  80  to move its hook portion  76  from a closely spaced relationship with the housing reinforcing extension  50  to a second position, spaced further away than the first position. 
     As shown in  FIG. 4 , a surgical rasp  12 , or similar tool comprising a body designed to wear or cut bone and cartilage by friction, is now mountable onto the handle assembly  10 . The surgical tool  12  is provided with a main inlet  84  and a secondary inlet  86 . The main inlet  84  is sized and configured to receive the housing reinforcing extension  50  in a snug, but slidable fit. The secondary inlet  86  is now aligned with the hook portion  76 . A locked relationship between the handle assembly  10  and the surgical tool  12  is affected when the handle lever  42  is returned to its original position, resting against the ledge  42 . That return movement causes the locking pawl  58  to pivot on the housing pivot pin  80  to move the hook portion  76  back to the closely spaced relationship with the housing reinforcing extension  50 , to thereby reside in the secondary rasp inlet  86 . As the locking pawl  58  pivots back to its original position, the main linkage  56  moves proximally, which cause the inverted linkage  54  to move in a downwardly and proximal direction as it returns to its original position vertically above the main linkage  56 . 
     As shown in  FIG. 2 , the drive train  14  is locked into position once the first pivot pin  68  is vertically below the fulcrum pivot pin  62  in an “over center” relationship. The over center, locked condition is indicated by arrow  88  as the gap between the two dashed lined centered on pins  62  and  68  with respect to the center of the second pivot pin  70 . The surgical tool  12  is now firmly locked and secured to the handle assembly  10  for use during a surgical procedure. 
     The angular relationship between the various axes A-A, B-B (B′-B′) and C-C provide the present tool handle assembly  10  as being particularly useful for performing minimally invasive hip surgery. For minimally invasive surgery of the hips, most surgeons perform an anterolateral approach known as the Roettinger technique (or Watson-Jones). Depending on the country, some variant of this technique is commonly used. As shown in  FIG. 9 , the handle assembly  10 , however, is an adapted instrument that is used to prepare the cavity of the femur when the iliac crest  90  is the main obstacle. In that respect, the present handle assembly  10  is adapted for an anterior approach where the offset  92  from the coronal plane  94  must be increased to approximately 50 mm. The drawing illustrates use of the handle assembly  10  in a minimally invasive hip surgery procedure where the iliac crest is blocking direct access to the femur. 
     To prepare the handle assembly  10  for cleaning and sterilization, the linkage lock mechanism  82  is manipulated in a direction away from the housing  16  until the blocking pins  82 A,  82 B are completely removed from the bores  36 A,  36 B in the respective side walls  24 ,  26 . The linkage train  14  including the handle lever  52 , inverted linkage  54  and main linkage  56  is now pivotable out of the housing  16  about housing pivot pin  80 . The pivot pin  80  keeps the linkage train  14  from being completely separated from the housing  16 . Thus, the linkage train  14  is separable from the housing  16  in a manner that is sufficient to clean and sterilize all of their parts without the possibility of there being total separation of one for the other. Total separation could easily lead to lost and misplaced parts. 
     The present invention further relates to the handle assembly  10  comprising part of a kit. Typically, a surgical kit comprises a container, the handle assembly  10 , and a surgical tool  12  to be connected to the handle assembly. Representative surgical tools  12  include, but are not limited to, broaches, rasps, reamers, angled drivers, twist drills, flexible drills, cannulated drills, bayonet drills, bayonet taps, drill guides, adjustable angle drill guides, taps, and cannulated taps. Instructions for connecting the surgical tool to the handle assembly  10  are also typically provided with the kit. 
     Additionally, the linkage train  14  and housing  16  are preferably made of a durable material that can be washed and sterilized (e.g., with high heat) to comply with sterilization standards known in the art. In one embodiment, the linkage train  14  and housing  16  are made of metal, such as stainless or a super alloy material. In another embodiment, they are made of a composite material. Though the illustrated embodiment shows the housing  16  as being one piece, in other embodiments it can be modular to facilitate disassembly of the handle assembly  10 . 
     Of course, the foregoing description is that of certain features, aspects and advantages of the present invention, to which various changes and modifications can be made without departing from the spirit and scope of the present invention. Moreover, the handle assembly need not feature all of the objects, advantages, features and aspects discussed above. Thus, for example, those of skill in the art will recognize that the invention can be embodied or carried out in a manner that achieves or optimizes one advantage or a group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. In addition, while a number of variations of the invention have been shown and described in detail, other modifications and methods of use, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is contemplated that various combinations or sub-combinations of these specific features and aspects of embodiments may be made and still fall within the scope of the invention.