Patent Publication Number: US-11376055-B2

Title: System and method for attaching a surgical instrument to a patient&#39;s bone

Description:
This application is a divisional application and claims priority to U.S. patent application Ser. No. 14/674,757, now U.S. Pat. No. 10,603,094, which was filed on Mar. 31, 2015, the entirety of which is expressly incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to orthopaedic surgical instruments and, more particularly, to surgical instruments used to resect a patient&#39;s bone. 
     BACKGROUND 
     Joint arthroplasty is a well-known surgical procedure by which a diseased and/or damaged natural joint is replaced by a prosthetic joint. Typical artificial joints include knee prostheses, hip prostheses, shoulder prostheses, ankle prostheses, and wrist prostheses, among others. To facilitate the replacement of the natural joint with the prosthesis, orthopaedic surgeons use a variety of orthopaedic surgical instruments such as, for example, saws, drills, reamers, rasps, broaches, cutting blocks, drill guides, milling guides, and other surgical instruments. 
     SUMMARY 
     According to one aspect of the disclosure, a surgical instrument system is disclosed. The surgical instrument system comprises a bone fixation pin including a head and a shaft extending from the head to a distal end having a plurality of threads defined therein, and a surgical instrument configured for use with the bone fixation pin. The surgical instrument comprises an elongated shaft defining a longitudinal axis extending through its proximal end and its distal end, a socket defined in the distal end of the elongated shaft that is sized to receive the head of the bone fixation pin, a shank extending outwardly from the proximal end of the elongated shaft along the longitudinal axis that is configured to engage a surgical drill, a sheath extending over the distal end of the elongated shaft, and a locking mechanism coupled to the elongated shaft. The locking mechanism is operable to permit selectively movement of the elongated shaft along the longitudinal axis relative to the sheath between a position in which over-turning or over-torqueing the bone fixation pin is prevented and another position in which full torque may be applied to the bone fixation pin for final tightening or removal of the pin from the bone. In that way, the torque applied to the bone fixation pin may be controlled. 
     In some embodiments, the locking mechanism may include a locking tab that is moveable between a locked position in which the locking tab is positioned in an opening of the sheath to prevent movement of the elongated shaft and an unlocked position in which the locking tab is spaced apart from the opening to permit movement of the elongated shaft. 
     In some embodiments, the locking mechanism may include a body that is positioned in a slot defined in the elongated shaft, and the locking tab may extend outwardly from the body. Additionally, in some embodiments, the body may include a biasing element that biases the locking tab in the locked position. In some embodiments, the slot defined in the elongated shaft may extend longitudinally through the elongated shaft. 
     In some embodiments, the body may include a first end engaged with an inner surface of the sheath. When the locking tab is in the locked position, a second end of the body may be engaged with a distal-facing surface of the elongated shaft. When the locking tab is in the unlocked position, the second end of the body may be disengaged from the distal-facing surface of the elongated shaft. 
     In some embodiments, the first end of the body may be received in a groove defined in the inner surface of the sheath. In some embodiments, the sheath may include a distal opening defined in its distal end and a central passageway that extends inwardly from the distal opening. The elongated shaft may be positioned in the central passageway of the sheath. When the elongated shaft is moved in a first direction relative to the sheath, the distal end of the elongated shaft may be moved along the central passageway toward the distal end of the sheath. 
     In some embodiments, the head of the bone fixation pin may extend from a proximal end of the bone fixation pin to a distal edge. The threads of the shaft may extend from the distal end to a proximal edge, and a first distance may be defined between the distal edge of the head and the proximal edge of the threads. When the elongated shaft is located in a first position relative to the sheath, a second distance may be defined between the distal opening of the sheath and the distal end of the elongated shaft. The second distance may be greater than the first distance such that a number of the threads of the bone fixation pin are positioned in the central passageway of the sheath when the head of the bone fixation pin is fully seated in the socket of the elongated shaft. 
     In some embodiments, the elongated shaft may be moveable to a second position in which a third distance is defined between the opening of the sheath and the distal end of the elongated shaft. The third distance may be less than the first distance. 
     In some embodiments, the locking mechanism may be biased in a locked position in which the elongated shaft is prevented from moving relative to the sheath when the elongated shaft is in the first position. Additionally, the locking mechanism may be in an unlocked position in which the elongated shaft is permitted to move relative to the sheath when the elongated shaft is the second position. 
     Additionally, in some embodiments, the elongated shaft may include a pair of tabs extending outwardly from its proximal end and the sheath includes a pair of guide slots that receive the pair of tabs. The guide slots and the tabs may cooperate to prevent rotational movement about the longitudinal axis. In some embodiments, the socket and the head of the bone fixation pin may have corresponding triangular cross sections. 
     According to another aspect, a method of attaching a surgical instrument to a patient&#39;s bone is disclosed. The method comprises positioning the surgical instrument in a desired location relative to the patient&#39;s bone, inserting a head of a bone fixation pin through a distal opening of a fixation pin driver into a socket defined in an elongated shaft of the fixation pin driver, positioning a threaded distal end of the bone fixation pin in a guide hole defined in the surgical instrument, rotating the fixation pin driver to thread the bone fixation pin into the patient&#39;s bone, engaging a distal end of the fixation pin driver with an outer surface of the surgical instrument, operating a locking mechanism of the fixation pin driver to release the elongated shaft of the fixation pin driver for movement relative to an outer sheath of the fixation pin driver that includes the distal end of the driver, and rotating the fixation pin driver and advancing the socket of the fixation pin driver toward the distal opening of the fixation pin driver to further thread the bone fixation pin into the patient&#39;s bone. 
     In some embodiments, the method may further comprise securing a proximal end of the elongated shaft to a surgical drill. In some embodiments, the surgical instrument may be a cutting guide block. 
     In some embodiments, the method may further comprise engaging an annular flange of the bone fixation pin with the outer surface of the surgical instrument after advancing the socket of the fixation pin driver toward the distal opening of the fixation pin driver. Additionally, in some embodiments, the method may further comprise moving the socket of the fixation pin driver away the distal opening of a fixation pin driver until a biasing element causes the locking mechanism to engage the outer sheath and prevent movement of the elongated shaft. 
     According to another aspect, a surgical instrument system comprises a bone fixation pin including a head extending from a proximal end of the bone fixation pin to a distal edge, and a shaft extending from the head to a distal end having a plurality of threads defined therein that extend from the distal end to a proximal edge. The system also includes a surgical instrument configured for use with the bone fixation pin. The surgical instrument comprises a socket sized to receive the head of the bone fixation pin and a sheath extending over the socket to a distal end. A first distance is defined between the distal edge of the head and the proximal edge of the threads of the bone fixation pin, and the socket is moveable between a plurality of positions relative to the sheath. The plurality of positions includes a first position in which a second distance is defined between the distal end of the sheath and the socket such that a number of the threads of the bone fixation pin are positioned in the sheath when the head of the bone fixation pin is fully seated in the socket. In some embodiments, the socket may be moveable to a second position in which a third distance is defined between the distal end of the sheath and the socket. The third distance may be less than the first distance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description particularly refers to the following figures, in which: 
         FIG. 1  is a perspective view of a surgical instrument system for attaching a surgical instrument to a patient&#39;s bone; 
         FIG. 2  is an elevation view of a distal end of a surgical instrument of the system of  FIG. 1 ; 
         FIG. 3  is a side elevation view of the surgical instrument of  FIG. 2 ; 
         FIG. 4  is a side elevation view similar to  FIG. 3 ; 
         FIG. 5  is an exploded perspective view of the surgical instrument of  FIG. 2 ; 
         FIGS. 6 and 6A  are cross section views of the surgical instrument taken along the line  6 - 6  in  FIG. 3 , with  FIG. 6A  showing a pin with the surgical instrument; 
         FIGS. 7 and 7A  are cross section views of the surgical instrument taken along the line  7 - 7  in  FIG. 4 , with  FIG. 7A  showing a pin with the surgical instrument; 
         FIG. 8  is a perspective view of a cutting block positioned on a patient&#39;s bone and a bone fixation pin of the surgical instrument system of  FIG. 1 ; 
         FIG. 9  is a perspective view similar to  FIG. 8  showing the surgical instrument system of  FIG. 1  used to secure the cutting block to the patient&#39;s bone; and 
         FIG. 10  is a perspective view similar to  FIG. 8  showing the cutting block attached to the patient&#39;s bone with a pair of bone fixation pins. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     Terms representing anatomical references, such as anterior, posterior, medial, lateral, superior, inferior, etcetera, may be used throughout the specification in reference to the orthopaedic implants or prostheses and surgical instruments described herein as well as in reference to the patient&#39;s natural anatomy. Such terms have well-understood meanings in both the study of anatomy and the field of orthopaedics. Use of such anatomical reference terms in the written description and claims is intended to be consistent with their well-understood meanings unless noted otherwise. 
     Referring to  FIG. 1 , a surgical instrument system  10  for attaching a surgical instrument to a patient&#39;s bone is shown. The system  10  includes a bone fixation pin  12  and a fixation pin driver  14  configured to be attached to the head  16  of the fixation pin  12 . As described in greater detail below, the driver  14  is operable to control the torque applied to the fixation pin  12 . 
     The fixation pin  12  includes an elongated shaft  18  that extends distally from the head  16  to a distal tip  20  of the pin  12 . In the illustrative embodiment, the pin  12  is formed as a single, monolithic component from a metallic material such as, for example, stainless steel. In other embodiments, the head  16  and shaft  18 , for example, might be formed as separate components. A plurality of threads  22  are defined in the elongated shaft  18  and extend from the distal tip  20  to a proximal edge  24 . The threads  22  are configured to grip the patient&#39;s bone to hold the pin  12  (hence the surgical instrument) in position on the bone. 
     The head  16  of the fixation pin  12  is positioned at a proximal end  26  of the pin  12 . The head  16  includes a number of substantially planar surfaces  28  that extend distally from the proximal end  26  to a distal edge  30 . In the illustrative embodiment, the surfaces  28  define a generally triangular-shape; in other embodiments, the surfaces  28  may define, for example, a generally square shape. 
     The elongated shaft  18  includes a substantially smooth surface  32  that connects the proximal edge  24  of the threads  22  to the distal edge  30  of the head  16 . The fixation pin  12  also includes an annular flange  34  that extends outwardly from the surface  32 . As shown in  FIG. 1 , a distance  36  is defined between the distal edge  30  and the proximal edge  24 . 
     The driver  14  includes a sheath  40  that extends over an elongated shaft  42 . The shaft  42  is moveable relative to the sheath  40 , but the driver  14  includes a locking mechanism  44  operable to fix the sheath  40  and the shaft  42  in position relative to one another. The shaft  42  has a drive shank  46  formed at its proximal end  48 . The shank  46  is configured to engage a surgical drill or other rotary tool operable to rotate the driver  14  about its longitudinal axis  50 . As shown in  FIG. 1 , the longitudinal axis  50  extends through the proximal end  48  of the shaft  42  and the distal end  52  of the sheath  40 . 
     An opening  54  is defined in the distal end  52  of the sheath  40 , and a cylindrical inner wall  56  extends inwardly from the opening  54 . The inner wall  56  defines a central passageway  58  that extends through the distal end  52  and opposite proximal end  60  of the sheath  40 . The elongated shaft  42  extends outwardly from the proximal end  60  of the sheath  40  to its proximal end  48 . 
     As shown in  FIG. 2 , the distal end  62  of the elongated shaft  42  is positioned in the central passageway  58 . A socket  64  sized to receive the head  16  of the fixation pin  12  is defined in the distal end  62  of the shaft  42 . The socket  64  has a number of substantially planar surfaces  66  that extend inwardly from an annular beveled surface  68 . The surfaces  66  correspond in shape and arrangement to the surfaces  28  of the head  16  such that the head  16  may be snuggly in the socket  64 . The socket  64  is sized so that the head  16  fully seats in the socket  64 , with the annular flange  34  of the pin  12  engaged with the distal end  62  of the elongated shaft  42 . 
     As described above, the shaft  42  is moveable relative to the sheath  40 . As shown in  FIGS. 3 and 4 , the shaft  42  is moveable between a controlled-torque position  70  (see  FIG. 3 ) and a full torque position  72  (see  FIG. 4 ). In the controlled-torque position  70 , the distal flange  74  of the shank  46  is spaced apart from the proximal end  60  of the sheath  40 , and the socket  64  is spaced inwardly from the distal opening  54  of the sheath  40 . In the full torque position  72 , the distal flange  74  of the shank  46  is engaged with the proximal end  60  of the sheath  40 . Additionally, the socket  64  is positioned adjacent the distal opening  54  of the sheath  40 . 
     In the illustrative embodiment, the locking mechanism  44  includes a locking tab  76  that is configured to be received in a slot  78  defined in the sheath  40  when the shaft  42  is in a controlled-torque position  70 . The engagement between the locking tab  76  and the sheath  40  fixes the sheath  40  and the shaft  42  in position relative to one another, as described in greater detail below. 
     Referring now to  FIG. 5 , the sheath  40 , shaft  42 , and locking mechanism  44  are shown in greater detail. In the illustrative embodiment, the sheath  40  is an assembly of two components  80 ,  82 . It should be appreciated that in other embodiments the sheath  40  may be formed as a single monolithic component. The component  80  is positioned distally and defines the distal end  52  of the sheath  40 . The other component  82  includes the proximal end  60  of the sheath  40 . A pair of flanges  84  extend distally from the component  82  and are configured to engage a corresponding pair of slots  86  defined in the component  80  to secure the components  80 ,  82  and assemble the sheath  40 . 
     The proximal component  82  includes a substantially planar surface  88 , and a generally rectangular opening  90  is defined in the surface  88 . A number of inner walls  92  extend inwardly from the opening  90  to define the locking slot  78  described above. As shown in  FIG. 5 , the locking slot  78  opens into the central passageway  58 , which extends through both the components  80 ,  82  of the sheath  40 . 
     As described above, the elongated shaft  42  has a distal end  62  that is positioned in the central passageway  58  of the sheath  40 . A substantially cylindrical surface  100  extends from the distal end  62  to the drive shank  46  formed at the proximal end  48  of the shaft  42 . In the illustrative embodiment, a pair of tabs  102  extends outwardly from the surface  100  near the drive shank  46 . Each tab  102  is received in a guide slot or groove  104  defined in the inner wall  56  of the proximal component  82 . The tabs  102  and grooves  104  cooperate to guide the relative movement of the shaft  42  and sheath  40  and prevent relative rotation between the shaft  42  and the sheath  40 . 
     The shaft  42  has a longitudinal opening  110  defined in the cylindrical surface  100 . A number of inner walls  112  extend inwardly from the opening  110  to another longitudinal opening  114  defined in the opposite side of the surface  100  to define a slot  116  extending through the shaft  42 , as shown in  FIG. 6 . The walls  112  further cooperate to define an inner chamber  118  positioned proximal of the slot  116 . The slot  116  and inner chamber  118  are sized to receive the lever  120  of the locking mechanism  44 . 
     Returning to  FIG. 5 , the locking mechanism  44  has a lever  120  and the locking tab  76  described above. The lever  120  extends from an end  122  that engages the sheath  40  to another lever end  124  that engages the elongated shaft  42 . The lever  120  includes an arm  126  that extends from the lever end  122  and is joined at its opposite end to a body  128 . The body  128  connects the arm  126  to another arm  130  that extends from the lever end  124 . The locking tab  76  extends outwardly from the connecting body  128 . In the illustrative embodiment, the lever  120  and locking tab  76  are formed as a single monolithic component from a resilient material such as, for example, spring steel. 
     As shown in  FIG. 6 , the arm  126  has a lip  132  formed at the lever end  122  that is received in a groove  134  defined in the inner wall  56  of the proximal component  82  of the sheath  40 . The arm  130  has a substantially planar or flat surface  136  at the opposite lever end  124 , which is configured to engage a distal-facing surface  138  of the elongated shaft  42 . 
     In use, the elongated shaft  42  of the fixation pin driver  14  is positioned in the controlled-torque position  70  shown in  FIGS. 3 and 6 . In that position, the surface  136  of the locking mechanism lever  120  is engaged with the distal-facing surface  138  of the elongated shaft  42  and the locking tab  76  is positioned in the slot  78  defined in the sheath  40 . As shown in  FIG. 6 , the distal end  62  of the elongated shaft  42  (and hence the socket  64 ) is spaced apart from the distal opening  54  of the sheath  40  such that a distance  140  is defined between the opening  54  and the distal end  62  and socket  64  of the elongated shaft  42 . 
     A user may load a bone fixation pin  12  into the driver  14  by aligning the head  16  of the pin  12  with the distal opening  54  of the sheath  40 . The user may then advance the head  16  of the pin  12  into the distal opening  54 , along the central passageway  58 , and into the socket  64  of the elongated shaft  42 . As described above, the annular flange  34  of the pin  12  engages the distal end  62  of the elongated shaft  42  when the head  16  is fully seated in the socket  64 . With the head  16  fully seated in the socket  64 , a number of the threads  22  of the pin  12  are positioned in the central passageway  58  of the sheath  40  because the distance  140  is greater than the distance  36  defined between the distal edge  30  of the head  16  and the proximal edge  24  of the threads  22 . 
     As shown in  FIG. 7 , the user may align the distal tip  20  of the pin  12  with a guide pin hole  150  of a surgical instrument such as, for example, femoral cutting block  152 , to be secured to the patient&#39;s bone  154 . In other embodiments, the surgical instrument may be a tibial cutting block, a sizing block, gauge, or other surgical instrument. The user may then advance the distal tip  20  into the hole  150  and into contact with the patient&#39;s bone  154 . As described above, a surgical drill or other rotary power tool may be attached to the drive shank  46  to rotate the driver  14  (and hence the fixation pin  12 ) to screw the pin  12  into the patient&#39;s bone  154 . As the driver  14  is rotated about its axis  50 , the pin  12  advances into the patient&#39;s bone  154 , and the distal end  62  of the sheath  40  is advanced into contact with the cutting block  152 , as shown in  FIG. 9 . 
     When the distal end  62  of the sheath  40  contacts the cutting block  152 , further movement of the driver  14  toward the patient&#39;s bone  154  is prevented. However, continued rotation of the driver  14  causes the pin  12  to continue to advance into the patient&#39;s bone  154 . As the pin  12  advances, the head  16  of the pin  12  is advanced distally, away from the socket  64 . With continued rotation of the driver  14 , the head  16  is advanced out of engagement with the socket  64 . The sheath  40  is sized so that the head  16  is advanced out of engagement with the socket  64  to prevent the user from applying too great a torque to the pin  12 . 
     If the user desires to further tighten the pin  12  or remove the pin  12 , the user may depress the locking tab  76  by applying a force in the direction indicated by arrow  156  in  FIG. 6 . When the locking tab  76  is disengaged from the slot  78 , the user may advance the elongated shaft  42  along the longitudinal axis to the full torque position  72  shown in  FIG. 7 . When the user releases the locking tab  76 , the lever  120  urges the tab  76  back into the slot  78 , as shown in  FIG. 7 . In full torque position  72 , the distal end  62  of the elongated shaft  42  (and hence the socket  64 ) is positioned adjacent to the distal opening  54  of the sheath  40  such that a distance  160  is defined between the opening  54  and the distal end  62  and socket  64  of the elongated shaft  42 . The distance  160  is less than the distance  36  defined between the distal edge  30  of the fixation pin head  16  and the proximal edge  24  of the threads  22  such that the user may apply the full torque of the surgical drill to the fixation pin  12 . In that way, additional torque may be applied to the pin  12  to further tighten the pin or remove the pin  12  from the bone. 
     To return the elongated shaft  42  to the controlled-torque position  70 , the user may pull on the shank  46  as indicated by arrow  162 . The arm  130  of the lever  120  slides along the inner wall  112  of the elongated shaft  42  until it reengages the distal-facing surface  138  in the controlled-torque position  70 . 
     While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected. 
     There are a plurality of advantages of the present disclosure arising from the various features of the method, apparatus, and system described herein. It will be noted that alternative embodiments of the method, apparatus, and system of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of the method, apparatus, and system that incorporate one or more of the features of the present invention and fall within the spirit and scope of the present disclosure as defined by the appended claims.