Patent Publication Number: US-2023149178-A1

Title: Cannulated bone implant and methods of use

Description:
INCORPORATION BY REFERENCE 
     This application claims the benefit of U.S. Provisional Application No. 63/264,233, filed Nov. 17, 2021, the entirety of which is hereby incorporated by reference. 
    
    
     BACKGROUND 
     Field of the Invention 
     The embodiments described herein are directed to bone implants which may be made of artificial materials (e.g., metal or polymers) or from human tissue (e.g., allograft bone) and methods of use. 
     Description of the Related Art 
     Hammertoe is a foot deformity that occurs in the middle joint (i.e., the proximal interphalangeal (“PIP”) joint) and/or the most proximal joint (i.e., the metatarsophalangeal (“MTP”) joint) of the second, third, fourth, or fifth toes. For example,  FIG.  1    illustrates a diagram of the bones in a human foot  1 . Hammertoe occurs in the PIP joint  6  and/or the MTP joint  7  of the second, third, fourth, or fifth toes  2 ,  3 ,  4 ,  5 .  FIG.  2 A  illustrates a normal human foot and  FIG.  2 B  illustrates a human foot with a hammertoe. 
     This condition normally starts out as a mild deformity with the hammertoes being flexible, and the symptoms can often be managed with noninvasive procedures. However, if the condition is left untreated, hammertoes will become more rigid and surgical procedures may be required to improve symptoms. This deformity can be caused by a variety of factors including: wearing certain shoes, trauma, or an abnormal balance of the toe muscles. There are approximately 200,000 cases of hammertoe in the US annually and, according to the 2012 National Foot Health Assessment commissioned by the Institute of Preventive Foot Health, 3% of U.S. adults age 21 and older, roughly 7 million people, have experienced hammertoe. Several symptoms of hammertoe include: pain in the affected toe, corns and/or callouses on the affected toe, swelling, redness, a burning sensation, inability to straighten the toe, and open sores on the affected toe. 
     Currently, one kind of surgery for treating hammertoe requires the use of a Kirschner wire, also known as a “K-wire,” and an implant. The surgery generally involves exposing the PIP joint, removing parts of the PIP joint, pinning a K-wire centrally on the proximal phalanx, and placing in an implant. 
     SUMMARY 
     In some aspects of the disclosure, a cannulated bone implant is disclosed. The cannulated bone implant may comprise a proximal portion, a proximal end, a distal portion, a distal end, a transition portion, a threaded portion, a finned portion, and a central passage. The transition portion may be positioned between the proximal portion and the distal portion. The transition portion may comprise a bend. The threaded portion may be positioned along the proximal portion between the proximal end and the transition portion. The threaded portion may be configured to secure the implant into a bone of a patient. The finned portion may be positioned along the distal portion between the transition portion and the distal end. The finned portion may be configured to prevent migration and/or rotation of the implant in use. The central passage may extend linearly from the proximal end of the implant to the distal end of the implant. 
     The cannulated bone implant of the preceding paragraph can also include one or more of the following features. The threaded portion can be configured to be threaded into a proximal phalanx of the patient. The central passage can be configured to receive a surgical wire. The threaded portion can comprise a first cross-sectional shape. The finned portion can comprise a second cross-sectional shape. The first cross-sectional shape can comprise a first circle. The second cross-sectional shape can comprise a second circle or an oval. The bend can comprise an angle of 15 degrees or less. The implant can comprise a metallic material, a polymeric material, or an allograft material. The angle of the central passage can be 10 degrees or less relative to a longitudinal axis of the proximal portion. The diameter of the central passage can be constant. A height of the threads in the threaded portion can be greatest at the proximal end of the implant and gradually decrease toward the transition portion. The proximal portion can comprise a shaft. The shaft can have an outermost diameter that decreases from the transition portion toward the proximal end of the implant. The external diameter of threads of the threaded portion can be constant. The external diameter of threads of the threaded portion can be smallest at the proximal end of the implant and gradually increase from the proximal end of the implant toward the transition portion. 
     In some aspects of the disclosure, a method of digital arthrodesis or hammertoe correction is disclosed. The method can include accessing a proximal interphalangeal joint between a middle phalanx and a proximal phalanx. A first K-wire is inserted into the proximal phalanx. Bone and/or cartilage is resected from the proximal phalanx and a first aperture is drilled and tapped within the proximal phalanx using a first instrument inserted over the first K-wire. The first K-wire is removed from the proximal phalanx. A second K-wire is inserted into the middle phalanx bone and/or cartilage is resected from the middle phalanx and drilling a second aperture within the end of the middle phalanx using a second instrument inserted over the second K-wire. The second K-wire is removed from the middle phalanx. A proximal portion of a cannulated bone implant is inserted within the first aperture of the proximal phalanx. A third K-wire is inserted into the middle phalanx. An end of the third K-wire is inserted into a passage of the cannulated bone implant. A distal portion of the cannulated bone implant is inserted within the second aperture of the middle phalanx along the third K-wire. The distal portion of the cannulated bone implant is manually compressed within the middle phalanx. 
     In another aspect, the third K-wire is inserted through a proximal portion of the middle phalanx and out past a distal end of a distal phalanx. In another aspect, the third K-wire is advanced into the proximal phalanx and across a metatarsophalangeal joint after inserting the distal portion into the second aperture of the middle phalanx. In another aspect, the middle phalanx is distracted distally to advance the distal portion of the cannulated bone implant into the second aperture of the middle phalanx. In another aspect, the method includes radiographically checking that the first K-wire is centered on a face and/or at a correct depth within the proximal phalanx. In another aspect, the method includes inserting a broach in the second aperture of the middle phalanx to create an ovoid or oval shape to match an oval profile of the distal portion of the cannulated bone implant. In another aspect, the cannulated bone implant has a transition portion positioned between the proximal portion and the distal portion, wherein the transition portion comprises a bend. In another aspect, the cannulated bone implant includes a threaded portion positioned along the proximal portion. In another aspect, the cannulated bone implant includes a finned portion positioned along the distal portion, the finned portion configured to prevent migration and/or rotation of the implant in use. In another aspect, the threaded portion comprises a first cross-sectional shape and the finned portion comprises a second cross-sectional shape. In another aspect, the first cross-sectional shape comprises a circle and the second cross-sectional shape comprises an oval. In another aspect, the passage extends linearly from a proximal end of the implant to a distal end of the implant. In another aspect, the implant comprises a metallic material. In another aspect, the implant comprises a polymeric material. In another aspect, the implant comprises an allograft material. In another aspect, the first instrument is a one-step drill, tap and reamer. In another aspect, the second instrument is the same as the first instrument. In another aspect, the second instrument is a one-step drill and reamer. In another aspect, the second K-wire and the third K-wire are the same K-wire, and the second K-wire is not removed and the third K-wire is not inserted. In another aspect, the first, second and third K-wires are the same K-wire. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates a diagram of the bones of a human foot. 
         FIGS.  2 A- 2 B  illustrate a healthy human foot and a human foot with a hammertoe, respectively. 
         FIG.  3 A  illustrates a perspective view of a configuration of an implant that may be used in a hammertoe procedure. 
         FIG.  3 B  illustrates a side view of the configuration of the implant shown in  FIG.  3 A . 
         FIG.  4 A  illustrates a perspective view of a configuration of an implant that may be used in a hammertoe procedure. 
         FIG.  4 B  illustrates a side view of the configuration of the implant shown in  FIG.  4 A . 
         FIG.  5 A  illustrates a distal end of the implant shown in  FIG.  4 A . 
         FIG.  5 B  illustrates a proximal end of the implant shown in  FIG.  4 A . 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to various embodiments of the present technology, which relates to a bone implant. Although certain specific embodiments of the present technology are described, the present technology is not limited to these embodiments. On the contrary, these described embodiments are merely illustrative of the present technology, and the present technology is intended to also cover alternatives, modifications, and equivalents. Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present technology. However, it will be recognized by one of ordinary skill in the art that embodiments can be practiced without these specific details. In some instances, well known methods, procedures, compounds, compositions and mechanisms have not been described in detail as not to unnecessarily obscure aspects of embodiments of the present technology. Further details regarding bone implants and methods of use that may be incorporated into the embodiments described herein are described in PCT Application No. US2021/031633, filed May 10, 2021, published as WO 2021/231329, the entirety of which is hereby incorporated by reference. 
     Cannulated Implant 
       FIGS.  3 A- 3 B  illustrate a configuration of an implant  100  that may be used in a hammertoe procedure. The implant  100  can have a proximal portion  102 , a transition portion  106 , and a distal portion  104 . The transition portion  106  can be located between the proximal portion  102  and the distal portion  104 . The transition portion  106  can include a bend to cause the distal portion  104  to be angled 7° relative to the proximal portion  102 . In some aspects, the angle of the bend can be approximately 0° to approximately 15°, approximately 2° to approximately 13°, approximately 4° to approximately 11°, or approximately 6° to approximately 9°. In one configuration, the proximal portion  102  can be threaded and the distal portion  104  can be finned. The threaded proximal portion  102  can be configured to secure the implant  100  into a patient&#39;s bone. For example, during a hammertoe correction procedure, the threaded proximal portion  102  can be threaded into the proximal phalanx of a patient&#39;s toe. The finned distal portion  104  can be tapered with a larger diameter at the distal end of the transition portion  106  and a smaller diameter at the distal end  112  of the implant  100 . A tapered finned distal portion  104  prevents the implant  100  from migrating after the implant  100  has been inserted into a patient while promoting micro-motion and bone healing. In a configuration, the shaft of the implant  100  forming the proximal portion  102  can have a diameter that is smallest at a proximal end  110  and gradually increases to a maximum diameter in the transition portion  106 . 
     As shown in  FIG.  3 B , the implant  100  can be cannulated with a straight, narrow passage  108  therein, extending linearly from the proximal end  110  to the distal end  112  of the implant  100 , as shown below. The angle of the passage  108  can be approximately 4.5° relative to a longitudinal axis of the proximal portion  102 . In some aspects, the angle of the passage  108  can be approximately 0° to approximately 10°, approximately 2° to approximately 8°, or approximately 4° to approximately 6° relative to a longitudinal axis of the proximal portion  102 . The implant  100  can be made out of allograft, metal, or polymer. 
       FIGS.  4 A- 4 B  illustrate another configuration of an implant  200  that can be used in a hammertoe procedure. Features of the implant  200  may also be incorporated into the implant  100 , and vice versa. The implant  200  can have a proximal portion  202 , a transition portion  206 , and a distal portion  204 . The transition portion  206  can be located between the proximal portion  202  and the distal portion  204 . The transition portion  206  can include a bend to cause the distal portion  204  to be angled 7° relative to the proximal portion  202 . In some aspects, the angle of the bend can be approximately 0° to approximately 15°, approximately 2° to approximately 13°, approximately 4° to approximately 11°, or approximately 6° to approximately 9°. In one embodiment, the proximal portion  202  can be threaded and the distal portion  204  can be finned. The threaded proximal portion  202  can be configured to secure the implant  200  into a patient&#39;s bone. For example, during a hammertoe correction procedure, the threaded proximal portion  202  can be threaded into the proximal phalanx of a patient&#39;s toe. The finned distal portion  204  can be tapered with a larger diameter at the distal end of the transition portion  206  and a smaller diameter at the distal end  212  of the implant  200 . 
     In an embodiment, the shaft of the implant  200  forming the proximal portion  202  can have a diameter that is smallest at a proximal end  210  and gradually increases to a maximum diameter in the transition portion  206 . The threads on the proximal portion  202  can be reverse tapered or graduated relative to the taper of the shaft of the implant  200 . For example, the threads on the proximal portion  202  can have a height relative to the shaft of the implant  200  that is greater at a proximal end  210  and that decreases toward the transition portion  206 . The external diameter of the threads along the proximal portion  202  may be constant from the proximal end  210  toward the transition portion  206 . This configuration ensures effective contact between the implant  200  and the surgical site. The negative space between the threads allows for new bone to incorporate into the implant  200 , which is important for patients who have poor quality bones. In some embodiments, the external diameter of the threads along the proximal portion  202  may gradually increase from the proximal end  210  toward the transition portion  206 . 
     As shown in  FIG.  4 B , the implant  200  can also be cannulated with a straight, narrow passage  208  therein, extending linearly from the proximal end  210  to the distal end  212  of the implant  200 , as shown below. The angle of the passage  208  can be approximately 4.5° relative to a longitudinal axis of the proximal portion  202 . In some aspects, the angle of the passage  108  can be approximately 0° to approximately 10°, approximately 2° to approximately 8°, or approximately 4° to approximately 6° relative to a longitudinal axis of the proximal portion  202 . The implant  200  can be made out of allograft, metal, or polymer. 
     As shown in  FIGS.  5 A- 5 B , the distal portion  204  can have a cross-sectional shape that is generally oblong or oval while the proximal portion  202  can have a cross-sectional shape that is generally circular. A serrated or finned distal portion  204  that is tapered and has a generally oblong cross-sectional shape prevents the implant  200  from migrating or rotating after the implant  200  has been inserted into a patient. This configuration also promotes micro-motion and bone healing. 
     The openings  208   a ,  208   b  of passage  208  may comprise a generally circular shape that extends through the implant  200 . In some embodiments, the passage  208  extending from the opening  208   a  at the proximal end  210  through the proximal portion  202  may have a different diameter than the passage  208  extending from the opening  208   b  at the distal end  212  through the distal portion. For example, the diameter of the passage  208  may be greater at the distal portion  204  than the diameter of the passage  208  at the proximal portion  202 . In some embodiments, the passage  208  has a constant diameter throughout the implant  200 . 
     Method of Use 
     The implants  100 ,  200  described above can be used in a digital arthrodesis or hammertoe correction procedure. In one method of performing the procedure, a practitioner makes a longitudinal incision along the affected digit, such as along the top (dorsal side) of the foot across a middle phalanx, the PIP joint and a proximal phalanx. Next, the practitioner performs a transverse capsular and tendon incision, such that the PIP joint is exposed. A sagittal saw or reamer can be used to resect the articular cartilage at the base of the middle phalanx and bone and/or cartilage at the head of the proximal phalanx to allow for reduction of the digit. The practitioner may insert an instrument (e.g., a drill, a tap, or combination of a drill and a tap) into the proximal phalanx until the instrument reaches a certain depth within the proximal phalanx. The instrument may comprise a threaded portion configured to match the threaded portions  102 ,  202  of the implant  100 ,  200 . The instrument may have one or more markings that indicate various depths of insertion of the instrument. The instrument may have a plurality of markings that indicate a depth of 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, or more. For example, when the 4 mm marking of the instrument aligns with the distal surface of the proximal phalanx, the instrument is inserted 4 mm into the proximal phalanx. 
     In some embodiments, a K-wire or other guide wire can be used to pre-drill or otherwise prepare the center of the proximal phalanx, if desired or necessary. The K-wire can be placed into a face or head of the proximal phalanx and/or extend into the intramedullary region of the proximal phalanx. The K-wire can be checked radiographically to be centered on the face and/or at a correct depth. A proximal screw in ream or tap and/or a distal reaming may be performed over the K-wire using the instrument described above. In some embodiments, the instrument may comprise a cannulated, one-step drill, tap and reamer. The one-step drill, tap and reamer can be used to create a pilot hole and/or resect the cartilage and/or some bone from the head of the proximal phalanx. The resection can create a resected face of the head of the proximal phalanx. The one-step drill, tap and reamer can include a reamer or planar portion that functions to remove bone and/or cartilage around a circumference of the tapped aperture within the proximal phalanx. The one-step drill, tap and reamer and the K-wire can then be removed. 
     In some embodiments, a similar process can be followed for the middle phalanx. For the middle phalanx, a K-wire can be placed into the middle phalanx and a one-step drill and reamer or a one-step drill, tap and reamer (or a different instrument) can be used to create a pilot hole and/or resect the cartilage and/or some bone from the head of the middle phalanx. In some embodiments, a broach can be used to create an ovoid or oval shape for the implant  100 ,  200 . Optionally, the broach can be cannulated to be advanced over the K-wire. Compared with resecting the proximal or middle phalanx using a saw, the distal reaming using the one-step drill, tap and reamer and/or one-step drill and reamer could spare more bone and/or tissue to allow for better integration of the implant  100 ,  200 . The K-wire can be removed from the middle phalanx or left in the middle phalanx for inserting the distal portion of the implant as described below. 
     After the proximal and middle phalanges are appropriately prepared, the implant  100 ,  200  as described above can be delivered. Preferably with any K-wire removed from the digit, the implant  100 ,  200  may first be delivered into the proximal phalanx to an appropriate depth. For example, the proximal, threaded portion  102 ,  202  of the implant  100 ,  200  may be threaded into the proximal phalanx using an appropriate insertion or delivery device. 
     Next, with the distal portion  104 ,  204  of the implant  100 ,  200  extending from the proximal phalanx, the distal portion of the toe (i.e., the middle and distal phalanges) can be distracted distally to advance the distal portion  104 ,  204  of the implant  100 ,  200  into the middle phalanx. In some embodiments of the method, the distal portion  104 ,  204  of the implant  100 ,  200  is placed over a K-wire and manually compressed. The K-wire can be the same K-wire used for drilling the middle phalanx or a different K-wire. The K-wire can be initially passed through the proximal portion of the middle phalanx until the K-wire extends past the distal end of the distal phalanx. The distal portion  104 ,  204  of the implant  100 ,  200  can be pushed into the middle phalanx over the K-wire (received within the passage  108 ), using the K-wire as a guide. The distal portion  104 ,  204  of the implant  100 ,  200  can be secured within the middle phalanx via a press fit (e.g., via manual compression). The K-wire can then be advanced into the proximal portion  102 ,  202  of the implant  100 ,  200  and/or into the proximal phalanx. The distal end of the K-wire can be cut off, bent, and/or advanced within the middle phalanx. Optionally, the K-wire can cross the PIP and/or the MTP joint (e.g., to stabilize the soft tissues at the MTP joint). Alternatively, the K-wire can be removed from the proximal or middle phalanx. The soft tissue and incisions can be closed in layers. 
     Other Variations and Terminology 
     The terms “first” and “second” are merely numbered for describing corresponding technical features clearly and do not represent the actual order. During particular implementations, the locations of the technical features defined by the terms “first” and “second” are interchangeable. 
     Terms of orientation used herein, such as “top,” “bottom,” “horizontal,” “vertical,” “longitudinal,” “lateral,” “outer,” “inner,” and “end” are used in the context of the illustrated embodiment. However, the present disclosure should not be limited to the illustrated orientation. Indeed, other orientations are possible and are within the scope of this disclosure. Terms relating to circular shapes as used herein, such as “diameter” or “radius,” should be understood not to require perfect circular structures, but rather should be applied to any suitable structure with a cross-sectional region that can be measured from side-to-side. Terms relating to shapes generally, such as “circular” or “cylindrical,” “semi-circular” or “semi cylindrical,” “oval” or “oblong,” or any related or similar terms, are not required to conform strictly to the mathematical definitions of circles, cylinders, oblongs, ovals or other structures, but can encompass structures that are reasonably close approximations. 
     The terms “approximately,” “about,” and “substantially” as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, in some embodiments, as the context may dictate, the terms “approximately,” “about,” and “substantially,” may refer to an amount that is within less than or equal to 10% of the stated amount. The term “generally” as used herein represents a value, amount, or characteristic that predominantly includes or tends toward a particular value, amount, or characteristic. As an example, in certain embodiments, as the context may dictate, the term “generally parallel” can refer to something that departs from exactly parallel by less than or equal to 20 degrees. 
     Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise or otherwise understood within the context as used, is generally intended to convey that certain embodiments include or do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments. 
     Conjunctive language, such as the phrase “at least one of X, Y and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y and at least one of Z. 
     Some embodiments have been described in connection with the accompanying drawings. The figures are drawn to scale, but such scale should not be limiting, since dimensions and proportions other than what are shown are contemplated and are within the scope of the disclosed invention. Distances, angles, etc. are merely illustrative and do not necessarily bear an exact relationship to actual dimensions and layout of the devices illustrated. Components can be added, removed and/or rearranged. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element or the like in connection with various embodiments can be used in all other embodiments set forth herein. Additionally, any methods described herein may be practiced using any device suitable for performing the recited steps. 
     Although this invention has been disclosed in the context of certain embodiments and examples, the scope of this disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Any system, method, and device described in this application can include any combination of the preceding features described in this and other paragraphs, among other features and combinations described herein, including features and combinations described in subsequent paragraphs. While several variations of the invention have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. Various features and aspects of the disclosed embodiments can be combined with or substituted for, one another in order to form varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.