Patent Publication Number: US-11642225-B2

Title: Poly-faced bone fusion implant

Description:
PRIORITY 
     This application claims the benefit of and priority to U.S. patent application Ser. No. 15/901,774 filed on Feb. 21, 2018 and U.S. Provisional Application, entitled “Poly-Faced Bone Fusion Implant,” filed on Feb. 23, 2017 and having application Ser. No. 62/462,766. 
    
    
     FIELD 
     The field of the present disclosure generally relates to securing bones together. More particularly, the field of the invention relates to an implant for fusing foot joint bones of the human body. 
     BACKGROUND 
     Proximal Interphalangeal (PIP) foot joint fusion essentially fixes the joint and fuses the proximal and middle phalanx (toe bones) in a straightened or angled position. The PIP is the first joint of the small toes. An indication for surgery is when this joint has a fixed curve deformity, such as due to claw toe, hammer toe, or mallet toe deformities. The deformity may be producing enough pain or functional limitations to warrant surgery. The deformity generally develops gradually and thus becomes fixed in a bent position for a long period of time. 
     There are a variety of ways that a PIP foot joint fusion may be performed. The PIP foot joint may be approached either through a longitudinal or transverse incision on the top of the toe. Once the joint is opened up, a small segment of bone may be removed from either side of the joint, creating enough room for the joint to be realigned. The joint may then be fixated in a straightened or slightly angled position, either by way of a wire or an internal screw. Fixating the PIP foot joint may be performed in association with other procedures, such as a tendon transfer, to help keep the toe in the newly straightened position, as well as procedures to address underlying mechanical problems that may have caused the small toe deformities of the PIP foot joint. 
     SUMMARY 
     A bone fusion implant is provided for fixating adjacent bone portions across a bone fusion site, particularly for treating conditions of Proximal Interphalangeal (PIP), Distal interphalangeal (DIP), and metatarsophalangeal (MTP) foot joints. The bone fusion implant is comprised of an elongate member having a proximal portion and a distal portion that share a line of fixation. A multiplicity of valleys may be disposed on opposite sides of the elongate member and configured to receive an insertion tool. A multiplicity of ramps and longitudinal grooves may be disposed on opposite sides of the elongate member. In one embodiment, proximal ramps are disposed on opposite sides of the proximal portion and extend to the line of fixation, distal ramps are disposed on opposite sides of the distal portion and extend toward the line of fixation, and side ramps are disposed between the distal ramps and extend to the line of fixation. In some embodiments, one or more longitudinal grooves may be disposed along the proximal portion and parallel the proximal ramps, and a keel may separate pairs of adjacent longitudinal grooves. The bone fusion implant may be comprised of a cortical bone allograft that is suitably sized to fuse a bone joint to be treated. A longitudinal axis of the cortical bone allograft may be substantially aligned with the longitudinal axis of the cortical bone to accommodate anisotropy in the structure of the cortical bone. 
     In an exemplary embodiment, a bone fusion implant for treating conditions of Proximal Interphalangeal (PIP), Distal interphalangeal (DIP), and metatarsophalangeal (MTP) foot joints comprises an elongate member comprising a proximal portion and a distal portion that share a line of fixation; proximal ramps disposed on opposite sides of the proximal portion and extending to the line of fixation; distal ramps disposed on opposite sides of the distal portion and extending toward the line of fixation; and side ramps disposed between the distal ramps and extending to the line of fixation. 
     In another exemplary embodiment, the bone fusion implant further comprises a dorsal valley and a plantar valley disposed between the distal ramps and the proximal ramps, the dorsal valley and the plantar valley being configured to receive an insertion tool suitable for grasping and inserting the bone fusion implant into bone. In another exemplary embodiment, the proximal portion is configured to be implanted into a hole drilled in a proximal bone portion, and wherein the distal portion is configured to be implanted into a hole drilled in a distal bone portion, the proximal bone portion and the distal bone portion comprising a bone joint being treated. In another exemplary embodiment, the side ramps are configured to contact the proximal bone portion when the line of fixation is aligned with the outside surface of the proximal bone portion, and wherein the side ramps are configured to ensure that the line of fixation remains substantially aligned with the outside surface during pressing of the distal portion into a hole drilled into the distal bone portion. 
     In another exemplary embodiment, the bone fusion implant is comprised of a cortical bone allograft that is suitably sized to fuse a bone joint to be treated, a longitudinal axis of the cortical bone allograft being substantially aligned with the longitudinal axis of the cortical bone to accommodate anisotropy in the structure of the cortical bone. In another exemplary embodiment, the proximal ramps are configured to facilitate press-fitting the proximal portion into a hole drilled in a proximal bone portion and create relatively greater compression between the proximal portion and the bone near the line of fixation. In another exemplary embodiment, the distal ramps are configured to facilitate press-fitting the distal portion into a bone hole drilled in a distal bone portion and encourage bone graft incorporation. 
     In another exemplary embodiment, the elongate member has at least four sides, such that two opposite of the at least four sides include the proximal ramps and comprise substantially parallel faces of the elongate member between the proximal ramps and a proximal end of the elongate member, and such that two opposite of the at least four sides include the distal ramps and comprise tapered faces of the elongate member between the side ramps and the proximal end, the tapered faces being configured to facilitate a press-fit between the proximal portion and a hole drilled in bone. In another exemplary embodiment, one or more transverse grooves are disposed on any one or more of the side ramps, the proximal ramps, and the distal ramps, the transverse grooves being configured to alleviate pressure and ease inserting the bone fusion implant into a hole drilled in bone. In another exemplary embodiment, any one or more of the side ramps, the proximal ramps, and the distal ramps include a surface texture configured to ease inserting the bone fusion implant into a hole drilled in bone and facilitate bone graft incorporation. In another exemplary embodiment, the surface texture is biased toward the line of fixation so as to facilitate movement of bone toward the line of fixation and inhibit bone movement away from the line of fixation. 
     In another exemplary embodiment, one or more longitudinal grooves are disposed on any one or more of the side ramps, the proximal ramps, and the distal ramps, the longitudinal grooves being configured to ease inserting the bone fusion implant into a hole drilled in bone and facilitate bone graft incorporation. In another exemplary embodiment, one or more longitudinal grooves are disposed along the proximal portion and configured to facilitate inserting the bone fusion implant into bone and encourage bone graft incorporation. In another exemplary embodiment, the proximal portion is disposed at a longitudinal angle with respect to the distal portion, the longitudinal angle being configured such that a bone joint may be fixated with a distal bone portion oriented in a plantar direction relative to a proximal bone portion. In another exemplary embodiment, at least a portion of the elongate member comprises a curved portion that directs the distal portion at the longitudinal angle relative to the proximal portion. 
     In an exemplary embodiment, a bone fusion implant for fixating adjacent bone portions across a bone fusion site comprises an elongate member comprised of a proximal portion and a distal portion that share a line of fixation; a multiplicity of valleys disposed on opposite sides of the bone fusion implant and configured to receive an insertion tool; a multiplicity of ramps comprising longitudinal grooves and disposed on opposite sides of the bone fusion implant; one or more longitudinal grooves disposed along the proximal portion and paralleling the proximal ramps; and a keel separating each pair of adjacent of the one or more longitudinal grooves. 
     In another exemplary embodiment, the proximal portion is configured to be implanted into a portion of a bone hole drilled in a proximal bone portion and the distal portion is configured to be implanted into a portion of the bone hole drilled in a distal bone portion across the bone fusion site. In another exemplary embodiment, the multiplicity of valleys is comprised of distal valleys disposed near the line of fixation and proximal valleys disposed near a proximal end of the bone fusion implant. In another exemplary embodiment, the multiplicity of ramps is comprised of distal ramps disposed on the distal portion and configured to contact a distal bone portion, and wherein the multiplicity of ramps is comprised of proximal ramps disposed on the proximal portion and configured to contact a proximal bone portion. In another exemplary embodiment, the one or more longitudinal grooves extend along the entire length of the proximal portion. In another exemplary embodiment, the one or more longitudinal grooves are comprised of at least four longitudinal grooves, and wherein at least two keels are disposed along the length of the proximal portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings refer to embodiments of the present disclosure in which: 
         FIG.  1    illustrates an isometric view of an exemplary embodiment of a bone fusion implant that is configured to treat conditions of Proximal Interphalangeal (PIP) and Distal interphalangeal (DIP) foot joints, such as claw toe, hammer toe, and mallet toe deformities; 
         FIG.  2 A  illustrates a top plan view of the exemplary embodiment of the bone fusion implant of  FIG.  1   ; 
         FIG.  2 B  illustrates a side plan view of the exemplary embodiment of the bone fusion implant of  FIG.  1   ; 
         FIG.  3    illustrates a cut-away view of a proximal interphalangeal foot joint being fixated by way of the bone fusion implant of  FIG.  1   ; 
         FIG.  4    illustrates a cut-away dorsal-plantar view of a proximal interphalangeal foot joint being fixated by way of the bone fusion implant of  FIG.  1   ; 
         FIG.  5 A  illustrates an isometric view of an exemplary embodiment of a bone fusion implant comprising longitudinal and transverse grooves; 
         FIG.  5 B  illustrates an isometric view of an exemplary embodiment of a bone fusion implant comprising multiple longitudinal grooves; 
         FIG.  6    illustrates an isometric view of an exemplary embodiment of a bone fusion implant comprising a longitudinal bend; 
         FIG.  7    illustrates a cut-away view of a proximal interphalangeal foot joint being fixated at an angle by way of the bone fusion implant of  FIG.  6   ; 
         FIG.  8    illustrates an isometric view of an exemplary embodiment of a bone fusion implant comprising multiple longitudinal grooves; and 
         FIG.  9    illustrates a cut-away view of an exemplary osteotomy of a first metatarsal being fixated by way of the bone fusion implant of  FIG.  8   . 
     
    
    
     While the present disclosure is subject to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. The invention should be understood to not be limited 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 present disclosure. 
     DETAILED DESCRIPTION 
     In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one of ordinary skill in the art that the invention disclosed herein may be practiced without these specific details. In other instances, specific numeric references such as “first bone portion,” may be made. However, the specific numeric reference should not be interpreted as a literal sequential order but rather interpreted that the “first bone portion” is different than a “second bone portion.” Thus, the specific details set forth are merely exemplary. The specific details may be varied from and still be contemplated to be within the spirit and scope of the present disclosure. The term “coupled” is defined as meaning connected either directly to the component or indirectly to the component through another component. Further, as used herein, the terms “about,” “approximately,” or “substantially” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. 
     In general, the present disclosure describes a bone fusion implant for treating conditions of Proximal Interphalangeal (PIP), Distal interphalangeal (DIP), and metatarsophalangeal (MTP) foot joints. The bone fusion implant comprises an elongate member having a proximal portion and a distal portion that share a line of fixation. The proximal portion is configured to be implanted into a hole drilled in a proximal bone portion of the PIP foot joint, and the distal portion is configured to be implanted into a hole drilled in a distal bone portion of the PIP foot joint. Proximal ramps are disposed on opposite sides of the proximal portion and configured to facilitate press-fitting the proximal portion into the hole in the proximal bone portion. Distal ramps are disposed on opposite sides of the distal portion and configured to facilitate press-fitting the distal portion into the hole drilled in a distal bone portion. The proximal and distal ramps create a relatively greater compression between the bone fusion implant and the portion of bone near the line of fixation. Side ramps disposed between the distal ramps and extending toward the line of fixation are configured to contact the proximal bone portion when the line of fixation is aligned with the outside surface of the proximal bone portion. The side ramps ensure that the line of fixation remains substantially aligned with the PIP foot joint during pressing of the distal portion into the hole drilled into the distal bone portion. A dorsal valley and a plantar valley are disposed between the distal ramps and the proximal ramps. The dorsal and plantar valleys are configured to receive an insertion tool suitable for grasping and inserting the bone fusion implant into the hole drilled in proximal bone portion. 
       FIG.  1    illustrates an exemplary embodiment of a bone fusion implant  100  that is configured to treat conditions of PIP, DIP, and MTP foot joints. Such conditions may include, but are not limited to claw toe, hammer toe, and mallet toe deformities. The bone fusion implant  100  may be comprised of a cortical bone allograft that is suitably sized to fuse the PIP, DIP, and MTP joints of the foot. It is contemplated that a longitudinal axis of the cortical bone allograft may be substantially aligned with the longitudinal axis of the cortical bone to accommodate anisotropy in the structure of the cortical bone. 
     The bone fusion implant  100  is a generally elongate member comprised of a proximal portion  104  and a distal portion  108  that share a line of fixation  112  shown in  FIGS.  2 A- 2 B . The proximal portion  104  is configured to be implanted into a hole drilled in a proximal bone portion  116 , such as a proximal phalanx of a PIP foot joint  118 , as shown in  FIGS.  3  and  4   . The distal portion  108  is configured to be implanted into a hole drilled in a distal bone portion  120 , such as a middle phalanx of the PIP foot joint  118 . In the illustrated embodiment, the length of the proximal portion  104  is relatively greater than the length of the distal portion  108 . The lengths of the proximal and distal portions  104 ,  108  are configured to optimize insertion of the bone fusion implant  100  into PIP, DIP, and MTP foot joints, as described herein. In general, however, the lengths of the proximal and distal portions  104 ,  108  are dependent upon the characteristics of the specific bone portions to be fused, or fixated, and thus the lengths of the proximal and distal portions  104 ,  108  may be varied from those shown herein, without limitation. 
     During fusing the PIP foot joint  118 , the proximal portion  104  may be inserted into the proximal bone portion  116  by way of an insertion tool suitable for grasping and pushing the bone fusion implant  100  into bone, such as, by way of non-limiting example, forceps or other similar tool. A dorsal valley  124  and a plantar valley  128  disposed on opposite faces of the distal portion  108  are configured to receive the insertion tool. Upon grasping the bone fusion implant  100  by way of the dorsal and plantar valleys  124 ,  128 , the proximal portion  104  may be pressed into the hole in the proximal bone portion  116 . Side ramps  132 ,  136 , disposed adjacent to the valleys  124 ,  128  on opposite faces of the bone fusion implant  100 , are configured to contact the proximal bone portion  116  when the line of fixation  112  is aligned with the outside surface of the proximal bone portion  116 . The distal bone portion  120  may be pressed onto the distal portion  108  that remains extending outside the proximal bone portion  116 . The side ramps  132 ,  136  ensure that the line of fixation  112  remains substantially aligned with the PIP foot joint  118  during pressing the distal portion  108  into the hole drilled into the distal bone portion  120 . 
     As best illustrated in  FIG.  2 B , proximal ramps  140 ,  144  are disposed on opposite sides of the proximal portion  104 . The proximal ramps  140 ,  144  comprise a tapered thickness of the proximal portion  104  extending away from the valleys  124 ,  128  toward a proximal end  148 . As will be recognized, the proximal ramps  140 ,  144  facilitate press-fitting the proximal portion  104  into the hole drilled in the proximal bone portion  116  and create relatively greater compression between the proximal portion  104  and the bone near the line of fixation  112 . Further, the proximal ramps  140 ,  144  discourage loosening of the proximal portion  104  within the proximal bone portion  116  after being press-fitted into the bone hole. 
     As further shown in  FIG.  2 B , distal ramps  152 ,  156  are disposed on opposite sides of the distal portion  108 . The distal ramps  152 ,  156  are similar to the proximal ramps  140 ,  144 , with the exception that the distal ramps  152 ,  156  comprise a tapered thickness of the distal portion  108  extending away from the valleys  124 ,  128  toward a distal end  160 . The distal ramps  152 ,  156  facilitate press-fitting the distal portion  108  into a bone hole drilled in the distal bone portion  120 . Similar to the ramps  140 ,  144 , the distal ramps  152 ,  156  are configured to create a relatively greater compression between the distal portion  108  and the bone near the line of fixation  112 . As shown in  FIG.  2 B , the distal ramps  152 ,  156  slope toward the distal end  160 , thereby facilitating inserting the distal portion  108  into the bone hole and discouraging loosening of the compression between the distal portion  108  and the distal bone portion  120 . 
     As shown in  FIGS.  2 A- 2 B , the proximal and distal ends  148 ,  160  may be chamfered so as to the minimize resistance to inserting the bone fusion implant  100  into bone. It should be understood, however, that the proximal and distal ends  148 ,  160  need not be chamfered as shown in  FIGS.  2 A- 2 B , but rather the proximal and distal ends  148 ,  160  may include any of various surface features that are found to facilitate inserting the proximal and distal ends  148 ,  160  into holes drilled in bone. For example, the proximal and distal ends  148 ,  160  may be beveled at any of various angles, as desired, or rounded to minimize potential trauma to bone surrounding the hole drilled in bone. 
     In the embodiment of the bone fusion implant  100  illustrated in  FIGS.  2 A- 2 B , the generally elongate member comprising the bone fusion implant has four-sides. As shown in  FIG.  2 B , two opposite sides, upon which the proximal and distal ramps  140 - 156  are disposed, comprise substantially parallel faces  164  of the bone fusion implant  100  between the proximal ramps  140 ,  144  and the proximal end  148 . The two opposite sides that include the side ramps  132 ,  136  comprise angled, or tapered faces  168  of the bone fusion implant  100  between the side ramps and the proximal end  148 . The tapered faces  168  are configured to facilitate a press-fit between the proximal portion  104  and the bone hole drilled into the proximal bone portion  116 . It is contemplated that the press-fit may discourage loosening of the bone fusion implant  100  within the bone and encourage graft incorporation. 
     The bone fusion implant  100  need not be limited to four-sides, but rather the elongate member comprising a poly-faced bone fusion implant may be comprised of greater than four sides. For example, in some embodiments, the elongate member comprising the poly-faced bone fusion implant may have five, six, seven, eight, or any number of sides that is found to facilitate fusing the PIP, DIP, and MTP foot joints, as described herein. Further, the poly-faced bone fusion implant is not limited to being comprised of the side, proximal, and distal ramps  132 - 156  described and shown herein. In some embodiments, for example, the poly-faced bone fusion implant may be comprised of more than two distal ramps  152 ,  156 , such as four distal ramps without limitation. In some embodiments, the poly-faced bone fusion implant may be comprised of more than two proximal ramps  140 ,  144 , such as, by way of non-limiting example, four proximal ramps. 
     Moreover, the poly-faced bone fusion implant may be comprised of various numbers of side, proximal, and distal ramps without limitation. For example, in one embodiment, the elongate member comprising the poly-faced bone fusion implant may be comprised of eight sides with four distal ramps and four side ramps uniformly distributed around the perimeter of the distal portion  108 . Further, such an embodiment of the poly-faced bone fusion implant may be comprised of four or eight proximal ramps that are uniformly distributed around the perimeter of the proximal portion  104 , without limitation. 
     In some embodiments, transverse grooves  172  may be disposed on any of the side, proximal, and distal ramps  132 - 156 . In the embodiment illustrated in  FIGS.  2 A and  2 B , transverse grooves  172  are disposed in the side ramps  132 ,  136  and the proximal ramps  140 ,  144 . The transverse grooves  172  may alleviate pressure and ease inserting the bone fusion implant  100  into the bone. The transverse grooves  172  may further increase the surface area of the bone fusion implant  100  so as to encourage graft incorporation. Once the bone fusion implant  100  has been suitably inserted into the bone, the bone may grow into the transverse grooves  172  and thereby maintain fixation of the implant in the bone. Moreover, it is contemplated that in some embodiments, any of various surface textures or other topological features may be incorporated into any one or more of the ramps  132 - 156 , either in addition to or in lieu of the transverse grooves  172 . For example, in some embodiments, the ramps  132 - 156  may each be comprised of a multiplicity of smaller transverse grooves disposed adjacently along the surface of each ramp. In some embodiments, the smaller transverse grooves may be biased toward the dorsal and plantar valleys  124 ,  128  so as to form sawtooth textures that facilitate movement of bone toward the line of fixation  112  and inhibit bone movement away from the line of fixation. 
       FIG.  5 A  illustrates an isometric view of an exemplary embodiment of a bone fusion implant  180  that is configured to treat deformities of PIP and DIP foot joints. The bone fusion implant  180  is substantially similar to the bone fusion implant  100 , illustrated in  FIG.  1   , with the exception that the bone fusion implant  180  is comprised of proximal and distal ramps  140 - 156  that include longitudinal grooves  184 , in lieu of the transverse grooves  172 . Further, the bone fusion implant  180  comprises a longitudinal groove  188  disposed in each of the tapered faces  168 .  FIG.  5 B  illustrates an exemplary embodiment of a bone fusion implant  192  that comprises a longitudinal groove  196  disposed in each of the side ramps  132 ,  136  in lieu of the transverse grooves  172 . The longitudinal grooves  184 ,  188 ,  196  are configured to facilitate inserting the bone fusion implant into bone and encourage bone graft incorporation, as disclosed herein. 
       FIG.  6    illustrates an isometric view of an exemplary embodiment of a bone fusion implant  200  that is configured to treat deformities of PIP, DIP, and MTP foot joints. The bone fusion implant  200  is substantially similar to the bone fusion implant  100 , illustrated in  FIG.  1   , with the exception that the bone fusion implant  200  is comprised of a proximal portion  104  that is disposed at a longitudinal angle with respect to a distal portion  108 . The bone fusion implant  200  may be used to fixate the PIP foot joint  118  with the distal bone portion  120  (e.g., the middle phalanx) disposed in the plantar direction, at a desired angle, relative to the proximal bone portion  116  (e.g., the proximal phalanx), as shown in  FIG.  7   . In some embodiments, the proximal and distal portions  104 ,  108  may be comprised of straight portions that are disposed at an angle with respect to one another. In some embodiments, a curved portion may be incorporated into the bone fusion implant  200  to direct the distal portion  108  at an angle relative to the proximal portion  104 . In some embodiments, the bone fusion implant  200  may be comprised of a curved elongate member, wherein the distal portion  108  is disposed at angle relative to the proximal portion  104 . It should be recognized, therefore, that any of various techniques may be used to establish an angle between the proximal and distal portions  104 ,  108 , without limitation, and without deviating beyond the spirit and scope of the present disclosure. 
       FIG.  8    illustrates an isometric view of an exemplary embodiment of a bone fusion implant  204  that may be used to treat deformities of PIP, DIP, and MTP foot joints, as well as treating other bones of the human body. The bone fusion implant  204  is a generally elongate member comprised of a proximal portion  104  and a distal portion  108  that share a line of fixation  112  that is similar to that shown in  FIGS.  2 A- 2 B . As shown in  FIG.  9   , the bone fusion implant  204  is configured to be implanted across a fusion site  208 , wherein the proximal portion  104  is implanted into a portion of a bone hole  210  drilled in a proximal bone portion  212  and the distal portion  108  is implanted into a portion of the bone hole  210  drilled in a distal bone portion  216 . As described herein, the lengths of the proximal and distal portions  104 ,  108  are dependent upon the characteristics of the specific bone portions to be fused, or fixated, and thus the lengths of the proximal and distal portions  104 ,  108  may be varied from those shown herein, without limitation. 
     During fusing of the proximal and distal bone portions  212 ,  216 , the bone fusion implant  204  may be inserted into the bone hole  210  by way of an insertion tool suitable for grasping and pushing the bone fusion implant  204  into bone, such as, by way of non-limiting example, forceps or other similar tool. A pair of distal valleys  218  disposed near the line of fixation  112  are configured to receive the insertion tool. Similarly, a pair of proximal valleys  220  near the proximal end  148  may be configured to receive the insertion tool. It is contemplated that the insertion tool may be used to grasp and push the bone fusion implant  204 , by way of the distal valleys  218 , into the bone hole  210  until the distal valleys  218  are near the surface of the bone, at which point the proximal valleys  220  may be utilized to continue pushing the bone fusion implant deeper into the bone hole  210 . The bone fusion implant  204  may be inserted into the bone hole  210  until the distal portion  108  is suitably inserted into the distal bone portion  116  and the proximal portion  104  is suitably inserted into the proximal bone portion  212 , such that the line of fixation  112  is advantageously aligned with the fusion site  208 . 
     As shown in  FIG.  9   , distal ramps  224  disposed on opposite sides of the distal portion  108  are configured to contact the distal bone portion  216 , and proximal ramps  228  disposed on opposite sides of the proximal portion  104  are configured to contact the proximal bone portion  212 . In the illustrated embodiment, the distal ramps  224  and the proximal ramps  228  flare toward the proximal end  148 . In some embodiments, however, the proximal ramps  228  may flare toward the distal end  160 , as discussed herein. Further, in the embodiment of the bone fusion implant  204  illustrated in  FIG.  8 - 9   , the distal ramps  224  are disposed on surfaces that are adjacent to the surfaces comprising the proximal ramps  228 . In some embodiments, however, any of the distal ramps  224  and any of the proximal ramps  228  may share the same surface of the bone fusion implant  204 , without limitation. Moreover, each of the distal ramps  224  includes a longitudinal groove  232 , and each of the proximal ramps  228  includes a longitudinal groove  236 . The longitudinal grooves  232 ,  236  are configured to facilitate inserting the bone fusion implant  204  into bone and encourage bone graft incorporation, as disclosed herein. 
     With continuing reference to  FIG.  8   , each of the proximal ramps  228  is adjacently paralleled by a longitudinal groove  240 . The longitudinal grooves  240  generally are disposed along the entire length of the proximal portion  104 , although various lengths of the longitudinal grooves are contemplated. In the illustrated embodiment of  FIG.  8   , the proximal portion  104  is comprised of four longitudinal grooves  240 . It is envisioned, however, that more or less than four longitudinal grooves  240  may be disposed along the proximal portion  104 , depending on the number of proximal ramps  228  incorporated into the proximal portion  104 , without limitation. A keel  244  separates each pair of adjacent longitudinal grooves  240  and extends along the length of the proximal portion  104 . Although the illustrated embodiment of  FIG.  8    is comprised of two keels  244 , it should be understood that more or less than two keels  244  may be incorporated into the bone fusion implant  204 , depending on the number of proximal ramps  228  comprising the proximal portion  104 , without limitation. Further, as mentioned with respect to the longitudinal grooves  240 , various lengths of the keels  244  are contemplated within the scope of the present disclosure. It is contemplated that the longitudinal grooves  240  and the keels  244  may facilitate inserting the bone fusion implant  204  into bone and encourage bone graft incorporation, as disclosed herein. 
     While the invention has been described in terms of particular variations and illustrative figures, those of ordinary skill in the art will recognize that the invention is not limited to the variations or figures described. In addition, where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art will recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the invention. Additionally, certain of the steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. To the extent there are variations of the invention, which are within the spirit of the disclosure or equivalent to the inventions found in the claims, it is the intent that this patent will cover those variations as well. Therefore, the present disclosure is to be understood as not limited by the specific embodiments described herein, but only by scope of the appended claims.