Patent Publication Number: US-2023140439-A1

Title: Tplo plate compression system and method

Description:
BACKGROUND 
     A Tibial Plateau Leveling Osteotomy (TPLO) is a surgical procedure for stabilizing a canine stifle joint, which is comparable to a human knee joint, after a ruptured cranial cruciate ligament (CCL). When the CCL is ruptured or torn, the animal&#39;s tibia slides forward with respect to its femur, making it difficult to walk and causing pain. In order to stabilize the joint, a curvilinear cut is made to the upper portion of the tibia. This cut portion of the tibia is then rotated to create a more level plane or surface on the top of the tibia, on which the femur can rest. The cut and repositioned portion of the tibia is then secured to the lower portion of the tibia using a TPLO plate. 
     TPLO plates are generally sized and shaped to extend along the two portions of the tibia to facilitate healing of the tibia in its new configuration. In some cases, however, where the cut portion is not properly seated in the lower portion of the tibia or where the osteotomy cut is not sufficiently compressed, the bone may fail to heal properly. 
     SUMMARY OF THE INVENTION 
     The present disclosure relates to a Tibial Plateau Leveling Osteotomy (TPLO) plate which includes a body extending longitudinally from a proximal end to a distal end and defined via a first surface which, in an operative configuration, faces away from a bone and a second surface which, in the operative configuration, faces toward the bone, the body including a proximal portion configured to be positioned over a cut and repositioned proximal segment of a tibia during a TPLO procedure and a distal portion configured to be positioned over a distal segment of the tibia during the TPLO procedure. The TPLO also includes a first distal hole extending through a proximal end of the distal portion of the body from the first surface to the second surface, the first distal hole configured to receive a first distal bone fixation element therein so that the body is rotatable about the first distal bone fixation element relative to a recess of the first distal hole within which a head portion of the first distal bone fixation element is configured to be seated. In addition, the TPLO plate includes a second distal hole extending through the distal portion of the body distally of the first distal hole from the first surface to the second surface, the second distal hole including a sloped compression surface, the second distal hole being configured to receive a second distal bone fixation element therein so that when a head portion of the second distal bone fixation element is slid along the sloped compression surface during insertion of the second distal bone fixation element into the second distal hole, the distal end of the body is moved so that an intersection of the sloped compression surface and the first surface of the body move away from an axis of the second distal bone fixation element rotating the body about the first distal bone fixation element to provide a desired movement of the proximal portion of the body to achieve a desired compression between the cut and repositioned proximal segment of a tibia and the distal segment of the tibia. 
     In an embodiment, the first distal hole is elongated along a longitudinal axis of the distal portion of the body, the first distal hole including a distal portion including a first rounded relief configurated to seat the head portion of the first distal bone fixation element so that, when the first distal bone fixation element is received within the distal portion of the first distal hole, the body is rotatable thereabout. 
     In an embodiment, each of the first and second distal holes is elongated in a direction parallel to a longitudinal axis of the distal portion of the body. 
     In an embodiment, the first distal hole includes a proximal portion including a second rounded relief configurated to seat the head portion of the first distal bone fixation element after a desired axial compression has been applied. 
     In an embodiment, the first and second rounded reliefs of the first distal hole are separated from one another by a transition point that provides resistance to passage of the head of a bone fixation therethrough. 
     In an embodiment, the transition point is a point at which a width of the first distal hole in a direction transverse to a longitudinal axis of the distal portion of the body is a minimum. 
     In an embodiment, the second distal hole further includes a groove extending into the sloped compression surface proximal of a distal end of the second distal hole, the groove configured to permit insertion of the second distal bone fixation element through the second distal hole along a caudal side of the longitudinal axis of the distal portion of the body. 
     In an embodiment, the plate further includes a third distal hole extending through the distal portion of the body, between the first and second distal holes, the third distal hole being configured to receive a third distal bone fixation element therein. 
     In an embodiment, the third distal hole is elongated in a direction parallel to a longitudinal axis of the distal portion of the body. 
     In an embodiment, the third distal hole is configured as a dynamic compression hole including a sloped compression surface along a distal portion thereof so that, when the third distal bone fixation element is inserted through a distal portion of the third distal hole, a head portion of the third distal bone fixation element interfaces with the sloped compression surface of the third distal hole to move the body distally relative to the third distal bone fixation element to provide distal compression of the proximal segment of the tibia against the distal segment of the tibia. 
     In an embodiment, the proximal portion of the body includes three proximal holes, each of which extends through the proximal portion, from the first surface to the second surface, along a proximal edge thereof, each of the proximal holes being configured to receive a proximal bone fixation element therein. 
     In an embodiment, a first one of the three proximal holes extends through the proximal portion in a position configured to facilitate insertion of a first one of the proximal bone fixation elements therethrough into a caudal portion of the proximal segment of the tibia, wherein a second one of the proximal holes extends through the proximal portion in a position configured to facilitate insertion of a second one of the proximal bone fixation elements therethrough into a proximal portion of the proximal segment of the tibia, and wherein a third one of the proximal holes extends through the proximal portion in a position configured to facilitate insertion of a third one of the proximal bone fixation elements therethrough into a cranial portion of the proximal segment of the tibia. 
     In an embodiment, a distance between the second distal hole and the first distal hole is equal to a distance between the first distal hole and the third proximal hole. 
     In an embodiment, the proximal portion of the body is connected to the distal portion of the body via a neck portion curved such that the proximal portion of the body is offset relative to the distal portion of the body toward a caudal side of a longitudinal axis of the distal portion of the body. 
     In an embodiment, the compression surface of the second distal hole is oriented relative to an axis of the distal portion of the body so that, when the plate is placed in a desired position on a tibia, as a head portion of the second distal bone fixation element is slid along the sloped compression surface during insertion of the second distal bone fixation element into the second distal hole, the distal end of the body is moved caudally moving the proximal portion of the body to apply cranial compression. 
     The present disclosure also relates to a method for a Tibial Plateau Leveling Osteotomy (TPLO) which includes positioning a bone plate in a desired initial position with a first surface of the bone plate facing away from the tibia and a second surface thereof facing a tibia so that a proximal portion of the bone plate extends over a proximal tibial segment and a distal portion of the bone plate extends over a distal tibial segment that has been cut away from the proximal tibial segment and rotated and seated within a recess formed in the distal tibial segment when the proximal tibia segment was cut away; inserting a first distal bone fixation element into the distal tibial segment of the tibia via a first distal hole extending through the distal portion of the bone plate such that a head portion of the first distal bone fixation element is seated within a recess extending along a distal portion of the first distal hole; and inserting a second distal bone fixation element into the distal segment of the tibia via a second distal hole extending through the distal portion of the bone plate distally of the first distal hole so that a head portion of the second distal bone fixation element slides along a sloped compression surface extending along a side of the second distal hole to move the distal portion of the bone plate to rotate the bone plate about the first distal bone fixation element to apply compression of the proximal tibial segment against the distal tibial segment. 
     In an embodiment, the first and second distal holes are elongated in a direction parallel to a longitudinal axis of the distal portion of the bone plate. 
     In an embodiment, the method further includes inserting a first proximal bone fixation element through a first proximal hole and a second proximal bone fixation element through a second proximal hole into the proximal tibia segment, the first and second proximal holes extending through the proximal portion of the bone plate so that, when the plate is in the desired initial position, the first and second proximal bone fixation elements fix the proximal portion of the bone plate relative to the proximal tibial segment prior to insertion of the second distal bone fixation element through the second distal hole. 
     In an embodiment, the first proximal bone fixation element is inserted into a cranial side of the proximal tibial segment. 
     In an embodiment, inserting the first distal bone fixation element through the first distal hole includes inserting the first distal bone fixation element into a distal portion of the first distal hole so that the head portion of the first distal bone fixation element engages a relief of the first distal hole. 
     In an embodiment, the second distal bone fixation element is inserted through a groove formed in the sloped compression surface of the second distal hole proximate a distal end of the second distal hole so that the second distal bone fixation element is inserted into the second distal hole caudally of a central axis of the second distal hole. 
     In an embodiment, the method further includes inserting a third distal bone fixation element through a third distal hole extending through the distal portion of the bone plate, between the first and second distal holes, so that a head portion of the third distal bone fixation element slides along a sloped compression surface along a distal portion of the third distal hole to move a distal portion of the bone distally relative to the third distal bone fixation element to generate distal compression of the proximal tibial segment against the distal tibial segment. 
     In an embodiment, as the proximal tibial segment is being distally compressed against the distal tibial segment, the first and second distal bone fixation elements are moved toward proximal ends of the first and second distal holes, respectively. 
     In an embodiment, the compression surface of the second distal hole extends along a caudal side of the second distal hole so that insertion of the second distal bone fixation element into the second distal hole moves rotates the distal portion of the bone plate caudally to apply cranial compression of the proximal tibial segment against the distal tibial 
    
    
     
       BRIEF DESCRIPTION 
         FIG.  1    shows a perspective view of a TPLO bone plate according to an exemplary embodiment of the present disclosure; 
         FIG.  2    shows a longitudinal cross-sectional view of a first hole extending through a distal portion of the TPLO plate of  FIG.  1   ; 
         FIG.  3    shows the longitudinal cross-section view of the first hole as shown in  FIG.  2   , with a first bone fixation element inserted therein; 
         FIG.  4    shows a plan view of a second hole extending through the distal portion of the TPLO plate of  FIG.  1   ; 
         FIG.  5    shows the plan view of the second hole as shown in  FIG.  4   , with a second bone fixation element inserted therein along a caudal side thereof; 
         FIG.  6 A  shows a transverse cross-sectional view of the second hole as shown in  FIG.  5   ; 
         FIG.  6 B  shows a transverse cross-sectional view of the second hole as shown in  FIG.  5   , with the second bone fixation element inserted therein; 
         FIG.  7    shows the plan view of the second hole as shown in  FIG.  4   , with the second bone fixation element moved toward a longitudinal axis of the distal portion; 
         FIG.  8    shows a transverse cross-sectional view of the second hole as shown in  FIG.  7   , with the second bone fixation element moved toward a longitudinal axis of the distal portion; 
         FIG.  9    shows a schematic drawing of the plate according to the exemplary embodiment of  FIG.  1   , positioned over a tibia; 
         FIG.  10    shows a schematic drawing showing force vectors on a tibia according to the exemplary plate of  FIG.  1   ; 
         FIG.  11    shows a longitudinal cross-sectional view of a third hole extending through the distal portion of the TPLO plate of  FIG.  1   ; 
         FIG.  12    shows a plan view of the TPLO plate according to the exemplary embodiment of  FIG.  1   , with the first bone fixation element inserted through the first hole; 
         FIG.  13    shows a plan view of the TPLO plate according to the exemplary embodiment of  FIG.  1   , with the second bone fixation element inserted through the second hole; 
         FIG.  14    shows a plan view of the TPLO plate according to the exemplary embodiment of  FIG.  1   , the plate rotated about the first bone fixation element; and 
         FIG.  15    shows a plan view of the TPLO plate according to the exemplary embodiment of  FIG.  1   , with the third bone fixation element inserted through the third hole. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present disclosure relates to a Tibial Plateau Leveling Osteotomy (TPLO) plate and, in particular, relates to a TPLO plate configured to provide both cranial (i.e., transverse) and distal (i.e., axial) compression during a TPLO procedure. Exemplary embodiments of the present disclosure describe a TPLO plate comprising a proximal portion configured to be positioned over a cut and repositioned upper portion (e.g., proximal portion) of a tibia, and a distal portion configured to be positioned along a lower portion (e.g., distal portion) of the tibia. 
     The distal portion of the plate includes a first hole and a second hole extending therethrough, the first and second holes configured to work in concert to provide a cranial compression. In particular, the second hole may be positioned distally of the first hole. The first and second holes are configured so that, when first and second bone fixation elements are inserted through the first and second holes, respectively, the plate may be rotated about the first bone fixation element so that a distal end of the distal portion is moved in a caudal direction relative to the second bone fixation element and the proximal portion of the plate is moved in a cranial direction. This rotation of the plate provides cranial compression across the osteotomy cut. 
     The distal portion of the plate further includes a third hole extending therethrough, between the first and second holes. The third hole is configured, for example, as a compression hole which, when engaged via a third bone fixation element inserted therethrough, permits the plate to be moved distally relative to the tibia, resulting in a distal compression across the osteotomy cut. It will be understood by those of skill in the art that although the TPLO plates of the present embodiments are described with respect to a canine CCL, the TPLO plate of the present disclosure may also be used to treat the tibia of other quadrupeds such as, for example, felines, bovines, equines, etc. It will also be understood by those of skill in the art that the terms proximal, distal, caudal and cranial are anatomical directional terms for an animal such as, for example, a canine and are employed in a manner consistent with their standard anatomical meanings. 
     As shown in  FIGS.  1 - 15   , a TPLO plate  100  according to an exemplary embodiment of the present disclosure is configured to secure proximal and distal segments of a tibia which have been separated from one another during a TPLO procedure via a substantially curvilinear osteotomy cut as would be understood by those skilled in the art. During a TPLO procedure, a proximal segment of the tibia cut away from the rest of the tibia, rotated relative to the tibia to a new position selected to enhance the stability to, for example, a canine stifle joint (e.g., after injury to a cranial cruciate ligament (CCL)) and secured to the distal segment in this desired position. 
     According to an exemplary embodiment, the TPLO plate  100  comprises a body  101  including a proximal portion  102  sized and shaped to be positioned over the cut and repositioned proximal segment of the tibia, and a distal portion  104  sized and shaped to extend along the distal segment of the tibia so that the plate  100  fixes the position of the cut and repositioned portion of the tibia relative to the distal segment. In an exemplary embodiment, the distal portion  104  includes at least three holes (i.e., a first hole  106 , a second hole  108 , and a third hole  110 ) extending therethrough. The first hole  106  and the second hole  108  are configured to work together so that, when first and second bone fixation elements  112 ,  114  have been inserted therein, respectively, cranial (i.e., transverse) compression of the osteotomy cut is permitted as will be described in more detail below. 
     The third hole  110  extending through the distal portion  104  is, in this embodiment, configured as a distal compression hole so that, when a third bone fixation element  116  is inserted therein, axial (distal) compression of the osteotomy cut is permitted as will also be described in more detail below. The cranial and distal compression together ensure that the cut and repositioned proximal segment of the tibia is optimally seated within a recessed portion of the distal segment formed via the curvilinear cut to enhance a healing of the bone. 
     As shown in  FIG.  1   , the body  101  of the plate  100  extends longitudinally from a proximal end  126  to a distal end  128 . The body  101  is defined via a first surface  130  which, in an operative configuration, faces away from a bone (e.g., the tibia), and a second surface  132  which, in the operative configuration faces toward the bone. The plate  100  includes the proximal portion  102  and the distal portion  104 , which may be connected to one another via a neck portion  124  so that, when in the operative configuration, the proximal portion  102  is positioned over the proximal segment of the tibia as desired, the distal portion  104  extends over and along the distal segment of the tibia while the neck portion  124  extends across the interface between the cut-away portion of the proximal tibia and the distal tibia at the curvilinear osteotomy cut. 
     The distal portion  104  extends distally of the proximal portion  102  along a longitudinal axis L. In one embodiment, this neck portion  124  may be curved so that the proximal portion  102  is offset (e.g., angled) relative to the longitudinal axis L of the distal portion  104 . For example, the proximal portion  102  may be angled in a caudal direction relative to the longitudinal axis L although, as would be understood by those skilled in the art, this angle may be selected in any manner desired to conform to the geometry of the cut-away and rotated portion of the tibia relative to the distal tibia (or any other bone segments involved) in any given procedure. 
     As will be understood by those of skill in the art, the proximal portion  102  is, in this embodiment, preferably constructed, sized, shaped and contoured to conform to the shape and orientation of the cut-away proximal segment of the tibia when the cut-away segment is in a desired position relative to the distal tibia and the distal portion  104  is in a desired position on the distal tibia. In particular, the second surface  132  of this embodiment is specifically contoured so that, when the proximal portion  102  is positioned over the proximal segment of the tibia, the second surface  132  extends along an exterior surface of the cut and rotated proximal segment of the tibia, in contact therewith. 
     In one embodiment (see  FIG.  9   ), the proximal portion  102  includes at least three holes (i.e., a first hole  118 , a second hole  120 , and a third hole  122 ), each of which extends through the proximal portion  102  from the first surface  130  to the second surface  132 , along an edge  134  extending along the proximal end  126  of the plate  100 . Each of the first, second and third holes  118 ,  120 ,  122  of the proximal portion  102  of this embodiment is configured to receive therein a bone fixation element such as, for example, a locking screw to fix the proximal portion  102  of the plate  100  relative to the cut and rotated proximal segment of the tibia. 
     The first hole  118  is positioned on the plate  100  and oriented so that, when the plate  100  is positioned on a tibia in a desired position, the first hole  118  is positioned to receive a bone fixation element through a caudal portion of the proximal segment of the tibia while the second hole  120  is positioned and oriented to receive a bone fixation element through a proximal portion of the proximal segment of the tibia. The third hole  122  is positioned and oriented on the plate  100 , when the plate  100  is in the desired position, to receive a bone fixation element through a cranial portion of the proximal segment of the tibia. As would be understood by those skilled in the art, central axes of each of the first, second and third holes  118 ,  120 ,  122  may be optionally angled to direct bone fixation elements inserted therealong into a desired portion of the proximal segment of the bone (e.g., a central mass of the cut-away portion of the proximal tibia). 
     Furthermore, any or all of the first, second and third holes  118 ,  120 ,  122  of the proximal portion  102  may be configured as locking holes, including a threading extending therein configured to engage corresponding threading on the head of a bone fixation element inserted therein. Thus, bone fixation elements inserted therein may be locking screws including corresponding threading along a head portion thereof. It will be understood by those of skill in the art, however, that the first, second and third holes  118 ,  120 ,  122  of the proximal portion  102  of the plate  100  may have any of a variety of configurations so long as bone fixation elements are insertable therethrough to be inserted into a desired portion of the bone. 
     The distal portion  104  of this embodiment is contoured to extend, when the plate  100  is in the desired position, along the distal segment of the tibia. In particular, in the operative configuration, the second surface  132  extends along the distal segment, in contact therewith. As described above, the distal portion  104  of this embodiment also at least includes three holes extending therethrough—the first hole  106 , the second hole  108  and the third hole  110 . The first hole  106  and the second hole  108  are configured to work together to permit the application of cranial compression across the osteotomy cut when engaged with the first and second bone fixation elements  112 ,  114 . The third hole  110  is configured to permit the application of distal compression across the osteotomy cut when a third bone fixation element  116  is inserted into and engaged therewith. 
     The first hole  106  is positioned adjacent to a proximal end  136  of the distal portion  104 , proximate the neck portion  124 . The first hole  106  is shaped so that, when the first bone fixation element  112  is received therein, the plate  100  may be pivoted about the first bone fixation element  112 . The spherical recess  142  is sized, shaped and configured to engage a head portion  113  of the bone fixation element  112 . In particular, the first hole  106  according to this embodiment is configured so that when the first bone fixation element  112  is inserted along a central axis of the spherical recess  142  (the central axis being substantially normal to the portion of the first surface  130  extending around the recess  142 ), a head portion  113  of the first bone fixation element  112  contacts a surface of the recess  142  permitting the body  101  of the plate  100  to rotate about the first bone fixation element  112  around the central axis of the spherical recess  142 . The first bone fixation element  112  in this embodiment may, for example, be a standard cortex screw. 
     As shown in  FIGS.  2 - 3   , the first hole  106  extends through the distal portion  104 , from the first surface  130  to the second surface  132 , along a central axis which extends, for example, substantially perpendicularly to one of the first and second surfaces  130 ,  132 . In one embodiment, the central axis of the first hole  106  extends through the longitudinal axis L and is elongated along the longitudinal axis L. The first hole  106  includes a proximal portion  138  and a distal portion  140 , each of which is configured to receive the first bone fixation element  112  therein as the plate  100  is moved relative to the first bone fixation element  112  as a result of distal compression. The proximal portion  138  includes a spherical recess  146  extending into the first surface  130  toward the second surface  132  along a central axis. A surface  144  of the spherical recess  146  is sized, shaped and configured to engage a head portion  113  of the bone fixation element  112 . 
     In particular, the bone fixation element  112  is initially inserted into the distal portion  140  of the first hole  106  so that an underside of the head portion  113  of the bone fixation element  112  (i.e., a surface of the head portion  113  facing toward the bone) is seated within the spherical recess  142 . When the head portion  113  of the first bone fixation element  112  is seated in the spherical recess  142 , movement of the plate  100  relative to the tibia is constrained in multiple directions while permitting rotation of the plate  100  about the first bone fixation element  112  (and the central axis of the distal portion  140  of the first hole  106  within which the first bone fixation element  112  is received). 
     In one embodiment, the head portion  113  and the spherical recess  142  are configured so that, when the head portion  113  is received therein, inadvertent translational movement of the plate  100  relative to the tibia is prevented and, when the plate  100  is rotated about the first bone fixation element  112 , the head  113  remains seated within the spherical recess  142 . For example, the first hole  106  may be dimensioned relative to the diameter of a shaft of the first bone fixation element  112  so that the plate  100  is secured against all movement except rotation about the first bone fixation element  112 . Translation along the axis L is prevented by the seating of the first bone fixation element  112  in the distal portion  140  until the first bone fixation element is slightly loosened as will be described in more detail below. This aids the physician in establishing and maintaining a desired initial axial position of the plate  100  until distal compression is applied as will be described below. 
     In this embodiment, the spherical recess  146  of the proximal portion  138  meets the spherical recess  142  of the distal portion  140  at a transition point  147  beyond which the head portion  113  of the first bone fixation element  112  will pass proximally only as distal compression is applied. As indicated above, this transition point  147  has a reduced width that holds the plate  100  in a desired axial position relative to the first bone fixation element  112  until the first bone fixation element  112  has been loosened and distal compression is applied via the third hole  110 . The spherical recess  146  of the proximal portion  138  is thus open to the spherical recess  142  of the distal portion  140  of the first hole  106  at the transition point  147  which may be configured, for example, as a slot having a width (extent transverse to the axis L) that is reduced compared to the widths of the proximal portion  138  and the distal portion  140 . 
     A surface  148  of the spherical recess  146  of the proximal portion  138  of the first hole  106  is also sized, shaped and configured to engage the head portion  113  of the first bone fixation element  112  in a seating configuration. The surface  144  of the spherical recess  142  of the distal portion  140  and the surface  148  of the spherical recess  146  of the proximal portion  138  form a substantially continuous surface. The first hole  106  therefore has a substantially slotted configuration so that the first bone fixation element  112  is translatable along the longitudinal axis L of the distal portion of the plate  100 . Thus, during axial compression of the tibia, the plate  100  moves relative to the bone and the first bone fixation element  112  so that the first bone fixation element  112  is moved from the distal portion  140  of the first hole  106  toward the proximal portion  38 . 
     More specifically, in an exemplary embodiment, the spherical recess  142  of the distal portion  140  and the spherical recess  146  of the proximal portion  138  are separated from one another by a clear transition point  147  (in this case a point of minimum width of the hole  106 ) that creates a generally binary positioning of the head of the first bone fixation element  112  inserted therein. That is, as the axial position of the plate  100  is adjusted (during axial compression), the head of the first bone fixation element  112  assists in establishing an initial axial position and then in locking a final axial position of the plate  100  (after a desired axial adjustment of the plate  100  has been completed) into a desired final axial position as the head  113  of the first bone fixation element  112  is held on the distal side of the transition point  147  (during initial positioning) and then on the proximal side of the transition point  147  after distal compression by the narrowing of the hole  106  at the transition point  147 . This prevents the plate  100  from moving proximally so that head  113  of the first bone fixation element passes the transition point  147  after the increased forces applied during axial compression have been discontinued. 
     In general, after the first bone fixation element  112  has been loosened slightly and distal compression is being applied as described below, the first bone fixation element  112  will be pushed through and past the transition point  147  from the recess  142  into the recess  146 . The narrowness of the hole  106  at the transition point  147  then interferes with the larger diameter of the head  113  of the first bone fixation element  112  to prevent the plate  100  from moving distally away from the desired final position (i.e., holding the plate  100  in a desired position relative to the first bone fixation element  112 ) to maintain the desired distal compression across the osteotomy. 
     According to an exemplary embodiment, the spherical recess  142  of the distal portion  140  and the spherical recess  146  of the proximal portion  138  have differing depths so that subsequent to the transverse compression and prior to the axial compression, the first bone fixation element  112  may be loosened to permit translational movement thereof within the first hole  106 . In one embodiment, the spherical recess  146  extends deeper into the plate  100  (farther from the first surface  130  toward the second surface  132 ) than does the spherical recess  142  of the distal portion  140 . In another embodiment, the spherical recess  146  extends into the plate  100  to a depth shallower than the spherical recess  142  of the distal portion  140 . In one example, the distal and proximal portions  140 ,  138  of the first hole  106  differ in depth by approximately 0.2 mm. Alternatively, the spherical recess  142  of the distal portion  140  and the spherical recess  146  of the proximal portion  138  may have the same depth so long as they intersect to create a transition point  147  that operates to prevent inadvertent movement of the plate  100  relative to the first bone fixation element  112  as described above. 
     The second hole  108 , as shown in  FIGS.  4 - 8   , is configured to receive the second bone fixation element  114  therein such that, as the second bone fixation element  114  is moved into increasing engagement with a portion of the second hole  108 , the distal end  128  of the plate  100  is moved in a caudal direction relative to the second bone fixation element  114  rotating the plate  100  about the first bone fixation element  112 , relative to the spherical recess  142 . In particular, the head portion  113  of the first bone fixation element  112  remains seated within the spherical recess  142  of the distal portion  140  of the first hole  106 . This rotation of the plate  100  moves the proximal portion  102  in a cranial direction, thereby providing cranial compression of the cut-away and repositioned proximal segment of the tibia against the distal segment of the tibia. The second hole  108  of the distal portion  104  of the plate  100  is, in this embodiment positioned distally of the first hole  106 , proximate the distal end  128  of the plate  100  although the second hole  108  could be positioned proximally of the first hole  106  if the orientation of the various elements of such an alternate second hole  108  were made a mirror image (relative to the axis L) of the second hole  108  of this embodiment. 
     The second hole  108  extends through the distal portion  104 , from the first surface  130  to the second surface  132 , and is, in this embodiment, substantially aligned with the first hole  106  along the longitudinal axis L of the distal portion  104 . Similarly to the first hole  106 , the second hole  108  is elongated along the longitudinal axis L from a proximal end  160  to a distal end  158 . The second hole  108  includes a relief  150  into the plate from the first surface  130  toward the second surface  132 . A surface  152  of the relief  150  includes a head receiving portion  155  and a compression portion  154 . The head receiving portion  155  is configured to engage an underside of a head portion  115  of the second bone fixation element  114  after compression. 
     In one embodiment, the head receiving portion  155  is curved (e.g., forming a part of a sphere or a cylinder) while the compression portion  154  is sloped and substantially planar to permit the head portion  115  of the second bone fixation element to slide over the compression portion  154  as the second bone fixation element  114  is inserted into the bone. The angling of the sloped surface of the compression portion  154  relative to the axis of the second bone fixation element  114  (inserted, for example along a central axis of the second hole  108 ) translates motion of the head portion along the central axis of the second hole  108  into motion of the compression portion  154  and the distal portion of the plate  100  lateral to the longitudinal axis L of the distal portion of the plate  100 . 
     In one embodiment, the plane of the compression portion  154  is substantially parallel to the longitudinal axis of the plate  100  and angled relative to the central axis of the second hole  108  so that, as the second bone fixation element  114  is inserted further into the bone, the head portion  115  drives the distal portion of the plate  100  further caudally. In one embodiment, the central axis of the second hole  108  is orthogonal to the axis L so that the plane including the sloped compression surface  154  intersects the plane including the central axis of the second hole  108  and the axis L at an angle selected to achieve a desired ratio of compression distance to distance of insertion of the second bone fixation element  114  into the second hole  108 . 
     In one embodiment, the compression portion  154  of the surface  152  extends along a caudal side of the second hole  108 . The compression portion  154  is sloped (e.g., compression portion  154  is substantially planar to facilitate sliding of the head portion  115  therealong) and extends along an incline at an angle selected so that, as the second bone fixation element  114  is moved further into the second hole  108 , the underside of the head portion  115  is pressed against and slides along the compression portion  154  moving the distal portion of the plate  100  in a caudal direction relative to the second bone fixation element  114  (i.e., the distal portion of the plate  100  moves caudally relative to the second bone fixation element  114  so that, as the plate rotates about the first bone fixation element  112 , the proximal portion of the plate  100  moves cranially to apply cranial compression across the osteotomy). 
     The planar nature of the surface  154  generates a linear relation between the amount of rotation of the screw (corresponding to a depth of insertion of the screw) to the amount of translation of the plate  100 , facilitating the generation of a desired amount of compression. Thus, the angle of the surface  154  can be altered in relation to the geometry of the underside of the head portion  115  of the second bone fixation element  114  to generate a desired ratio between depth of insertion of the second bone fixation element  114  and the amount of compression applied. Those skilled in the art will understand that, although the plate  100  is actually rotating about the first bone fixation element  112  and the distal portion of the plate  100  is moving along a portion of a circle, the small size of the caudal compression distance compared to the radius about which the plate  100  is rotating (distance between the first and second bone fixation elements  112 ,  114 , respectively) renders the compression (movement of the proximal portion of the plate  100 ) substantially linear in the cranial direction. 
     In an embodiment, the surface  152  of the relief  150  also includes a groove  156  extending into the sloped compression portion  154  proximate a distal end  158  of the second hole  108 . This groove  156  is configured to permit insertion of the second bone fixation element  114  into the distal end  158  of the second hole  108  in a position offset from the longitudinal axis L of the distal portion  104 , toward a caudal side of the second hole  108 , as shown in  FIGS.  5 - 6   . Thus, as the second bone fixation element  114  is inserted thereinto, the head portion  115  of the second bone fixation element  114  engages and slides along the compression portion  154  (e.g., at a point P generally aligned with a center of the groove  156 ), moving the distal end  128  of the bone plate in a caudal direction relative to the second bone fixation element  114 , as shown in  FIGS.  7 - 8   , with the second bone fixation element  114  moving toward the longitudinal axis L to be seated within the head receiving portion  155  as the plate  100  is rotated about the first bone fixation element  112  received within the first hole  106 . 
     This rotation of the plate  100  moves the proximal portion  102  in a cranial direction relative to the tibia, applying a cranial compression of the proximal segment of the tibia across the osteotomy against the distal segment of the tibia. Furthermore, a width W of the sloped compression portion (e.g., an extent of the compression portion  154  in a proximal-distal direction) is preferably selected to be at least as great as a maximum amount of axial compression to be applied to the plate  100 . That is, the compression portion  154  is preferably made wide enough so that, as the plate is translated proximally along the longitudinal axis of the plate during axial compression, the point of contact between the underside of the head portion  115  of the second bone fixation element  114  and the surface  152  remains within this width W. As would be understood by those skilled in the art, the width W of the compression portion  154  may be made longer than this difference to accommodate any error in the placement of the second bone fixation element  114 . 
     In one embodiment, as shown in  FIG.  9   , the second hole  108  of the distal portion  104  is separated from the first hole  106  of the distal portion  104  via a distance equal to a distance between the first hole  106  and the third hole  122  of the proximal portion  102 . Thus, when the distal end  128  of the plate  100  is moved in a caudal direction and the plate  100  rotates about the first bone fixation element  112  inserted into the first hole  106 , the proximal portion  102  of the plate  100  is moved in a cranial direction via a corresponding distance to provide compression across the osteotomy. Accordingly, as shown in  FIG.  10   , a cranial compression force exerted on the tibia is equal to a force exerted on the plate  100  via the second bone fixation element  114  inserted through the second hole  108  of the distal portion  104 . 
     The third hole  110 , as shown in  FIG.  11   , extends through the distal portion  104  in a position extending between the first and second holes  106 ,  108  and is configured to receive a third bone fixation element  116 . In one embodiment, the third hole  110  is positioned midway between the first and second holes  106 ,  108 . The third hole  110  in this embodiment is substantially aligned with the first and second holes  106 ,  108  along the longitudinal axis L and may be similarly elongated along the longitudinal axis L. In one embodiment, the third hole  110  is a dynamic compression hole configured to provide distal compression across the osteotomy. For example, the third hole  110  extends through the distal portion  104  from the first surface  130  to the second surface  132  and, similarly to the first hole  106 , includes a proximal portion  162  and a distal portion  164 , which facilitates translational movement of the third bone fixation element  116  therewithin from the distal portion  164  toward the proximal portion  162 , as axial compression is being applied to the tibia. 
     In one embodiment, the proximal portion  162  includes a spherical relief  166  extending into a thickness of the plate from the first surface  130 . The spherical relief  166  is sized and shaped to correspond to an underside of a head portion of the third bone fixation element  116  which, in an exemplary embodiment, may be a standard cortex screw. Thus, the spherical relief  166  may be configured to seat the head portion of the third bone fixation element  116  therein. When the head portion of the third bone fixation element  116  is seated in the spherical relief  166 , the head portion of the bone fixation element  116  may be substantially flush with the first surface  130  of the plate  100  as would be understood by those skilled in the art. It will be understood by those of skill in the art, however, that the head portion of the third bone fixation element  116  is not required to be finally seated within the spherical relief  166 . The third bone fixation element  116  may be moved from the distal portion  164  toward the proximal portion  162  by a distance corresponding to a desired axial compression. 
     The distal portion  164  includes a sloped compression surface  168  inclined at a curve/angle selected so that, as the head portion of the third bone fixation element  116  is pressed thereagainst (e.g., as the third bone fixation element  116  is inserted gradually further into the bone and further through the plate  100 ), the sloped compression surface  168  slides along the head portion of the third bone fixation element  116 . In particular, as the third bone fixation element  116  is driven more deeply into the bone, the head portion of the third bone fixation element  116  slides along the sloped compression surface  168  moving the plate  100  in a distal direction relative to the third bone fixation element  116  applying distal compression across the osteotomy—i.e., the proximal segment of the tibia is pressed distally against the distal segment of the tibia as the proximal portion of the plate  100  (coupled to the cut-away proximal segment of the tibia) is drawn distally by the movement of the distal portion of the plate  100 . 
     According to an exemplary method, the plate  100  may be used to provide both cranial and distal compression during a TPLO procedure. As will be understood by those of skill in the art, upon cutting of a proximal segment of a tibia from a distal segment of the tibia via a substantially curvilinear osteotomy, the proximal segment is rotated and repositioned relative to the distal segment and the plate  100  is then be placed over the separated bone segments so that the proximal portion  102  is positioned over the cut and repositioned proximal segment of the tibia and the distal portion  104  is positioned over the distal segment of the tibia. 
     According to the exemplary method, as shown in  FIG.  12   , the first bone fixation element  112  is first inserted into the distal portion  140  of the first hole  106  so that the head portion  113  of the first bone fixation element  112  is seated within the spherical recess  142  thereof. As shown in  FIG.  13   , the second bone fixation element  114  is then inserted through the groove  156  of the second hole  108  so that the head portion  115  of the second bone fixation element  114  contacts the compression portion  154  of the second hole  108 . Insertion of the first and second bone fixation elements  112 ,  114 , as described above, establishes a preliminary position of the bone plate  100  which is then adjusted as described below. It will be understood by those of skill in the art that bone fixation elements are then inserted through at least two of the holes extending through the proximal portion  102  of the plate  100  to fix the proximal portion  102  relative to the proximal segment of the tibia. In one embodiment, bone fixation elements are inserted through a cranial one of the holes (e.g., third hole  122 ) and one of the other holes (e.g., the first hole  118  and the second hole  120 ) of the proximal portion  102 . 
     As discussed above, as the second bone fixation element  114  is tightened (e.g., rotatably inserted further into the second hole  108 ), the compression portion  154  slides along the head portion  115  so that the distal end  128  of the plate  100  is moved in a caudal direction relative to the second bone fixation element  114 , as shown in  FIG.  14   . As the distal end  128  is moved in a caudal direction relative to the second bone fixation element  114 , the plate  100  rotates about the first bone fixation element  112  that was previously inserted into the first hole  106 , so that the proximal portion  102  of the plate is correspondingly being moved in a cranial direction. Thus, the proximal segment of the tibia, to which the proximal portion  102  is fixed, is being cranially compressed against the distal segment of the tibia across the osteotomy. 
     After cranial compression of the tibia has been fully applied, the third bone fixation element  116  is inserted into the distal portion  164  of the third hole  110 , as shown in  FIG.  15   . As the third bone fixation element is inserted further through the third hole  110 , the head portion of the third bone fixation element  116  slidingly engages the compression surface  168  thereof, moving the plate  100  in a distal direction relative to the third bone fixation element  116 . Thus, the proximal segment of the tibia, to which the proximal portion  102  is fixed, is distally compressed against the distal segment of the tibia. 
     As the osteotomy is being distally compressed, the third bone fixation element  116  is moved relative to the third hole  110  toward the proximal portion  162  of the third hole  110 . It will be understood by those of skill in the art that, during distal compression, the first bone fixation element  112  is similarly being received within the proximal portion  138  of the first hole  106  while the second bone fixation element  114  is moving toward the proximal end  160  of the second hole  108 . Upon completion of the distal compression, the first and second bone fixation elements  112 ,  114  may be tightened and additional bone fixation elements may be inserted through any remaining holes extending through, for example, the proximal portion  102 , to provide further locking of the plate  100  in the desired position relative to the tibia. 
     It will be understood by those of skill in the art that modifications and variations may be made in the structure and methodology of the present invention, without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention, provided that they come within the scope of the appended claims and their equivalents.