Patent Publication Number: US-2016235455-A1

Title: Expandable open wedge implant

Description:
PRIORITY 
     This application claims the benefit of and priority to U.S. Provisional application, entitled “Expandable Open Wedge Implant,” filed on Feb. 14, 2015 having application Ser. No. 62/116,385. 
    
    
     FIELD 
     The field of the present disclosure generally relates to surgical implants. More particularly, the field of the invention relates to an apparatus and a method for an expandable open wedge implant for performing open wedge osteotomies. 
     BACKGROUND 
     An osteotomy is a surgical operation whereby a bone is cut to shorten, lengthen, or change its alignment. Osteotomy is sometimes performed to correct a hallux valgus (i.e., a bunion), or to straighten a bone that has healed crookedly following a fracture. Osteotomy is typically used to relieve pain in arthritis, especially of the hip and knee, as well as the feet. For instance, osteotomy may be used to correct conditions affecting the hip, such as a coxa vara, where the angle between the head and the shaft of the femur is reduced to less than 120 degrees. Osteotomy may also be used to correct conditions affecting the knee, such as a genu valgum, a condition in which the knees angle in and touch one another, and a genu varum, a condition characterized by an outward bowing of the lower legs in relation to the thighs. Osteotomy is also utilized in the anatomical areas of the spine and wrist. Further, various conditions affecting the feet may be treated by way of osteotomy, such as an Evans Procedure for lateral column lengthening, a Cotton Procedure for medial cuneiform opening wedge osteotomy in the foot, and the like. 
     Generally, there are two ways in which osteotomy is utilized to adjust the orientation of a bone, such as the tibia: 1) a closed wedge osteotomy; and 2) an open wedge osteotomy. With closed wedge osteotomies, a wedge of bone typically is removed from a bone and then the bone is manipulated so as to close the resulting gap, thereby re-orienting the bone relative to other bones and hence adjusting the manner in which load is transferred onto the bone. In the case of open wedge osteotomies, a cut is made into the bone being adjusted and then the bone is manipulated so as to open a wedge-like opening in the bone, whereby the bone is re-oriented relative to the other bones to adjust the manner in which load is transferred onto the bone. The bone is then secured with a desired wedge-like opening by way of screwing metal plates to the bone, or by way of inserting a wedge-shaped implant into the opening in the bone. 
     Although both closed wedge osteotomies and open wedge osteotomies are well known to provide substantial benefits to patients, such surgeries are procedurally challenging for surgeons. As will be appreciated, in the case of open wedge osteotomies, properly stabilizing the bone with the desired wedge-like opening during healing can be very difficult. Further, the wedge-shaped implants used in open wedge osteotomies generally must be matched to the size of the patient&#39;s anatomy and the degree of correction desired. The surgeon is, therefore, challenged with selecting a perfectly sized implant in which performing minor adjustments may be difficult. Further still, wedge-shaped implants used in open wedge osteotomies generally are procedure-specific. For example, an antero-medial procedure may require one configuration of an implant, while a lateral procedure may require another configuration of the implant, and the like. The surgeon is thus again challenged with selecting a perfectly-sized implant, as mentioned above. 
     The present disclosure is, therefore, generally directed to open wedge osteotomy procedures applied to feet, such as the Evans Procedure for lateral column lengthening and the Cotton Procedure for medial cuneiform opening wedge osteotomy, as well as osteotomies for other bone joint locations, and is intended to provide a new and improved osteotomy implant which addresses the foregoing issues. 
     SUMMARY 
     An apparatus and a method are provided for an open wedge implant for open wedge osteotomies. The open wedge implant comprises a wedge body including a first expandable portion and a second expandable portion connected together by way of an intervening distal attachment. In some embodiments, the first and second expandable portions may comprise roughened exterior surfaces that are configured for contacting bone portions exposed during an osteotomy. In some embodiments, the first and second expandable portions may comprise surfaces with apertures that are configured for contacting bone portions exposed during an osteotomy and allowing new bone to grow through. An expander is configured to separate the first and second expandable portions so as to increase a proximal thickness and a wedge angle of the wedge body. A proximal screw is configured to move the expander within the wedge body. Tightening the proximal screw draws the expander distally into the wedge body, thereby changing the open wedge implant from an initial, narrow wedge angle to an expanded wedge angle. In some embodiments, the open wedge implant is adapted for use in osteotomies performed in the feet, such as an Evans Procedure for lateral column lengthening, a Cotton Procedure for medial cuneiform opening wedge osteotomy, and the like. 
     In an exemplary embodiment, an open wedge implant for open wedge osteotomies comprises a wedge body comprising a first expandable portion and a second expandable portion connected together by way of an intervening distal attachment; an expander configured to separate the first and second expandable portions so as to increase a proximal thickness and a wedge angle of the wedge body; and a proximal screw configured to move the expander within the wedge body. In another exemplary embodiment, the open wedge implant is adapted for use in osteotomies performed in the feet, such as an Evans Procedure for lateral column lengthening, a Cotton Procedure for medial cuneiform opening wedge osteotomy, and the like. 
     In another exemplary embodiment, the first and second expandable portions respectively comprise a first face and a second face comprising roughened exterior surfaces of the open wedge implant that are configured for contacting bone portions exposed during an osteotomy. In another exemplary embodiment, the first and second expandable portions respectively comprise a first face and a second face comprising surfaces with apertures of the open wedge implant that are configured for contacting bone portions exposed during an osteotomy and allowing new bone to grow through. In another exemplary embodiment, the first and second expandable portions, and the distal attachment comprise a single component of material. In another exemplary embodiment, the first and second expandable portions, and the distal attachment comprise separate components that are coupled together by any one of various suitable fastening techniques. 
     In another exemplary embodiment, the wedge body is comprised of a semi-flexible material, such as polyetheretherketone (PEEK), or polyetherketoneketone (PEKK). In another exemplary embodiment, the wedge body is comprised of a metal alloy exhibiting shape memory and superelastic properties, such as Nitinol. In another exemplary embodiment, tightening the proximal screw draws the expander distally into the wedge body, thereby changing the open wedge implant from an initial configuration to an expanded configuration. In another exemplary embodiment, the initial configuration is characterized by a relatively narrow proximal thickness and a relatively small wedge angle of the open wedge implant. In another exemplary embodiment, the expanded configuration is characterized by a relatively larger value of the proximal thickness, the wedge angle being proportional to the proximal thickness. In another exemplary embodiment, the distal attachment biases the wedge body in the initial configuration, thereby maintaining an assembled state of the open wedge implant. 
     In another exemplary embodiment, the wedge body comprises a proximal opening configured to receive the expander, such that the first and second expandable portions increasingly separate as the expander is drawn distally into the proximal opening. In another exemplary embodiment, the proximal opening comprises a first bevel in the first expandable portion and a second bevel in the second expandable portion, the first and second bevels being configured to respectively contact a first taper and a second taper respectively disposed on top and bottom sides of the expander. In another exemplary embodiment, the first and second tapers give the expander a distally tapering thickness suitable for separating the first and second expandable portions. 
     In another exemplary embodiment, the expander comprises a recess configured to loosely retain a smooth portion of the proximal screw, the recess allowing free rotation of the smooth portion while a threaded portion of the proximal screw is rotatably engaged within a threaded channel disposed between the first and second expandable portions. In another exemplary embodiment, the expander comprises a countersink configured to retain a head portion of the proximal screw, allowing free rotation of the screw and preventing the expander from becoming disengaged from the screw, the countersink comprising a depth such that the head portion is positioned substantially entirely within the body of the expander and remains substantially flush with the proximal end of the wedge body. In another exemplary embodiment, the proximal screw comprises a proximal socket configured to facilitate engaging and rotating the proximal screw by way of a suitable tool, such as any one of a variety of appropriate drivers. 
     In an exemplary embodiment, a method for a wedge implant for open wedge osteotomies comprises connecting a first expandable portion and a second expandable portion to an intervening distal attachment so as form a wedge body; configuring an expander to separate the first and second expandable portions so as to increase a proximal thickness and a wedge angle of the wedge body; and moving the expander within the wedge body by way of a proximal screw. 
     In another exemplary embodiment, moving the expander further comprises tightening the proximal screw so as to draw the expander distally into the wedge body, thereby separating the first and second expandable portions, and increasing the proximal thickness and the wedge angle of the wedge implant. In another exemplary embodiment, tightening further comprises engaging a proximal socket of the proximal screw and rotating the proximal screw by way of a suitable tool. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings refer to embodiments of the present disclosure in which: 
         FIG. 1  illustrates a perspective view of an exemplary embodiment of an expandable open wedge implant for open wedge osteotomies, according to the present disclosure; 
         FIG. 2  illustrates a side plan view of an exemplary embodiment of an expandable open wedge implant for open wedge osteotomies in accordance with the present disclosure; 
         FIG. 3  illustrates an exploded view of the exemplary embodiment of the expandable open wedge implant illustrated in  FIGS. 1-2 ; 
         FIG. 4  illustrates a transverse cross-sectional view of the exemplary embodiment of the expandable open wedge implant illustrated in  FIGS. 1-2  in an initial configuration, according the present disclosure; 
         FIG. 5  illustrates a transverse cross-sectional view of the exemplary embodiment of the expandable open wedge implant illustrated in  FIG. 3  in an expanded configuration in accordance with the present disclosure; 
         FIG. 6  illustrates a sagittal cross-sectional view of the exemplary embodiment of the expandable open wedge implant illustrated in  FIG. 4  in the initial configuration in accordance with the present disclosure; 
         FIG. 7  illustrates a sagittal cross-sectional view of the exemplary embodiment of the expandable open wedge implant illustrated in  FIG. 5  in the expanded configuration, according the present disclosure; 
         FIG. 8  illustrates a perspective view of an exemplary embodiment of an expandable open wedge implant for open wedge osteotomies, according to the present disclosure; 
         FIG. 9  illustrates a side plan view of the expandable open wedge implant for open wedge osteotomies illustrated in  FIG. 8 , according to the present disclosure; 
         FIG. 10  illustrates a perspective view of an exemplary embodiment of an expandable open wedge implant for open wedge osteotomies, according to the present disclosure; and 
         FIG. 11  illustrates a top plan view of the expandable open wedge implant for open wedge osteotomies illustrated in  FIG. 10 , according to the present disclosure. 
     
    
    
     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 implant,” may be made. However, the specific numeric reference should not be interpreted as a literal sequential order but rather interpreted that the “first implant” is different than a “second implant.” 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 an apparatus and a method for an open wedge implant for open wedge osteotomies. The open wedge implant comprises a wedge body including a first expandable portion and a second expandable portion connected together by way of an intervening distal attachment. The first and second expandable portions respectively comprise a first face and a second face comprising exterior surfaces that are configured for contacting bone portions exposed during an osteotomy. An expander is configured to separate the first and second expandable portions so as to increase a proximal thickness and a wedge angle of the wedge body. A proximal screw is configured to move the expander within the wedge body. Turning the proximal screw clockwise draws the expander distally into the wedge body, thereby changing the open wedge implant from an initial, narrow wedge angle to an expanded wedge angle. The distal attachment biases the wedge body toward the narrow wedge angle, thereby maintaining an assembled state of the open wedge implant. In some embodiments, the open wedge implant is adapted for use in osteotomies performed on the feet, such as an Evans Procedure for lateral column lengthening, a Cotton Procedure for medial cuneiform opening wedge osteotomy, and the like. 
       FIGS. 1-3  illustrate an exemplary embodiment of an expandable open wedge implant  100  for open wedge osteotomies in accordance with the present disclosure. The open wedge implant  100  comprises a wedge body  104 , an expander  108 , and a proximal screw  112 . Broadly, turning the proximal screw  112  clockwise, by way of a suitable tool, draws the expander  108  into the wedge body  104 , thereby changing the open wedge implant  100  from an initial configuration, as shown in  FIGS. 4 and 6 , to an expanded configuration shown in  FIGS. 5 and 7 . As described herein, the open wedge implant  100  is characterized by a relatively narrow proximal thickness  116  in the initial configuration illustrated in  FIG. 6 . In the expanded configuration, however, the proximal thickness  116  assumes a relatively larger value. As will be appreciated, a wedge angle  120  of the open wedge implant  100  is proportional to the proximal thickness  116 . Thus, in the initial configuration, the wedge angle  120  assumes a small angle, whereas in the expanded configuration the wedge angle  120  possesses a relatively larger angle. It should be understood, therefore, that the wedge angle  120  of the open wedge implant  100  is adjustable by way of turning the proximal screw  112 . 
     As illustrated in  FIGS. 1 and 2 , the wedge body  104  comprises a first expandable portion  124  and a second expandable portion  128  connected together by way of an intervening distal attachment  132 , such that the first and second expandable portions  124 ,  128  are separated by a gap  136 . The first and second expandable portions  124 ,  128  respectively comprise a first face  126  and a second face  130 . The first and second faces  126 ,  130  comprise exterior surfaces of the open wedge implant  100  that are configured for contacting bone portions exposed during an osteotomy. As will be recognized, the gap  136  allows for movement of the first and second expandable portions  124 ,  128  relatively to one another during adjustment of the open wedge implant  100 . Further, the distal attachment  132  biases the wedge body  104  in the initial configuration, illustrated in  FIG. 1 , thereby maintaining an assembled state of the open wedge implant  100 . A distal channel  140  facilitates deflection of the first and second expandable portions  124 ,  128 , and operates to maintain a uniform value of the wedge angle  120  along a longitudinal dimension of the open wedge implant  100 . 
     In the embodiment illustrated in  FIGS. 1 and 2 , the first and second expandable portions  124 ,  128 , and the distal attachment  132  comprise a single component of material. In some embodiments, however, the first and second expandable portions  124 ,  128 , and the distal attachment  132  may be separate components that are coupled together by any of various suitable fastening techniques. The wedge body  104  preferably is comprised of a semi-flexible material, such as by way of non-limiting example, a thermoplastic polymer, such as polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), or a metal alloy exhibiting elastic properties, such as Nitinol. In some embodiments, the expander  108  is comprised of the same material as the wedge body  104 . In some embodiments, the expander  108  is comprised of a material that is more rigid than the material comprising the wedge body  104 . 
       FIG. 3  illustrates an exploded view of the wedge body  104 , the expander  108 , and the proximal screw  112  comprising the open wedge implant  100  illustrated in  FIGS. 1-2 . The wedge body  104  comprises a proximal opening  144  configured to receive the expander  108 , such that the first and second expandable portions  124 ,  128  increasingly separate as the expander  108  is drawn into the proximal opening  144 . As such, the proximal opening  144  comprises a first bevel  148  in the first expandable portion  124 , and a second bevel  152  in the second expandable portion  128 . The first and second bevels  148 ,  152  are configured to respectively contact a first taper  156  and a second taper  160  respectively disposed on top and bottom sides of the expander  108 . As illustrated in  FIG. 3 , the first and second tapers  156 ,  160  give the expander  108  a distally tapering thickness suitable for separating the first and second expandable portions  124 ,  128 . A flat distal end  158  of the expander  108  is configured to contact a distal surface  162  of the proximal opening  144  when the open wedge implant  100  is placed into the expanded configuration illustrated in  FIG. 5 . A rounded proximal surface  166  of the expander  108  comprises a curvature which is substantially identical to a curvature of a proximal end of the wedge body  104  so as to give the open wedge implant  100  an exterior finish. 
     The expander  108  comprises a recess  164  configured to loosely retain a smooth portion  168  of the proximal screw  112 . The recess  164  allows free rotation of the smooth portion  168  while a threaded portion  172  of the proximal screw  112  is rotatably engaged within a threaded channel  176  disposed between the first and second expandable portions  124 ,  128 . The expander  108  comprises a countersink  180  configured to retain a head portion  184  of the proximal screw  112 , thereby allowing free rotation of the screw while preventing the expander  108  from becoming disengaged from the screw. The countersink  180  further comprises a depth whereby the head portion  184  is positioned substantially entirely within the body of the expander  108 . In the embodiment illustrated in  FIGS. 1-3 , the depth of the countersink  180  is such that the head portion  184  remains substantially flush with the proximal end of the wedge body  104 . A proximal socket  188  facilitates engaging and rotating the proximal screw  112  by way of a suitable tool, such as any of a variety of appropriate drivers. 
     It should be appreciated that the open wedge implant  100  may be advantageously used in various osteotomies performed in various locations within a patient&#39;s body. As such, the open wedge implant  100  may be implemented with a wide variety of shapes, sizes, and dimensions without deviating from the spirit and scope of the present disclosure. The embodiment illustrated in  FIGS. 4-7  is adapted for use in osteotomies performed in the feet, such as by way of non-limiting example, an Evans Procedure for lateral column lengthening, a Cotton Procedure for medial cuneiform opening wedge osteotomy, and the like. Accordingly, the open wedge implant  100  illustrated in  FIGS. 4-7  is implemented with a shape and dimensions advantageously selected for osteotomies performed in the feet. It should be understood, however, that the open wedge implant  100  is not limited to osteotomies performed in the feet, nor is the open wedge implant  100  to be limited to the shape and dimensions illustrated in  FIGS. 4-7 . Rather, it is to be understood that the open wedge implant  100  may be practiced with a variety of shapes and dimensions selected to advantageously accommodate osteotomies performed in other bone or bone-joint locations throughout the patient&#39;s body. 
     Referring specifically to  FIGS. 4-7 , the open wedge implant  100  generally comprises an initially trapezoidal transverse cross-section with parallel proximal and distal side dimensions  192 ,  196 , wherein the corners of the trapezoid are rounded to form the shape of the open wedge implant  100  illustrated in  FIG. 1 . In the illustrated embodiment of  FIG. 4 , the proximal side  192  is substantially 14 millimeters (mm) and the distal side  196  is substantially 10 mm, with a longitudinal dimension  200  being substantially 16 mm. It will be appreciated that implementing the open wedge implant  100  with the proximal side  192  being wider than the distal side  196  gives the implant a slightly wedge-shaped transverse cross-section. It will be further appreciated that the slightly wedge-shaped transverse cross-section advantageously facilitates inserting the open wedge implant  100  into an opening in bone formed during an osteotomy. 
     As discussed above, tightening the proximal screw  112  draws the expander  108  into the proximal opening  144 , and thus changes the open wedge implant  100  from the initial configuration, shown in  FIGS. 4 and 6 , to an expanded configuration wherein the first and second expandable portions  124 ,  128  are deflected away from one another. The open wedge implant  100  is placed into a fully expanded configuration once the distal end  158  of the expander  108  contacts the distal surface  162 , as illustrated in  FIG. 5 . In the fully expanded configuration, the first and second expandable portions  124 ,  128  are positioned at a maximal separation from one another, thereby maximizing the proximal thickness  116  and the wedge angle  120  of the open wedge implant  100 . In the initial configuration of the open wedge implant  100 , illustrated in  FIGS. 6-7 , the proximal thickness is substantially 4.4 mm and the wedge angle  120  is substantially 7 degrees. In the fully expanded configuration, wherein the proximal screw  112  has been tightened until the distal end  158  contacts the distal surface  166 , as illustrated in  FIGS. 5 and 7 , the proximal thickness is substantially 6.0 mm and the wedge angle  120  is substantially 14 degrees. As will be appreciated, throughout the expandable range of the first and second expandable portions  124 ,  128 , the thickness of the distal attachment  132  remains essentially unchanged. In the illustrated embodiment of  FIGS. 6-7 , the thickness of the distal attachment  132  is substantially 2 mm. As mentioned above, however, various shapes and dimensions may be incorporated into various embodiments of the open wedge implant  100  so as to utilize the open wedge implant in osteotomies performed in various bone or bone-joint locations within the patient&#39;s body without limitation. 
       FIGS. 8-9  illustrate an exemplary embodiment of an expandable open wedge implant  224  for open wedge osteotomies, according to the present disclosure. The open wedge implant  224  is substantially similar to the open wedge implant  100  illustrated in  FIGS. 1-2 , with the exception that the open wedge implant  224  comprises a wedge body  228  including a first roughened face  232  and a second roughened face  236 . In some embodiments, the first and second roughened faces  232 ,  236  comprise any of various surface features that are machined into the first and second faces  126 ,  130 . In some embodiments, the first and second roughened faces  232 ,  236  comprise a roughened surface coating, such as by way of non-limiting example, a Titanium plasma spray coating, or other similar material, applied to a PEEK or PEKK substrate. It will be appreciated that the first and second roughened faces  232 ,  236  provide a relatively more effective contact between the open wedge implant  224  and bone portions exposed during an osteotomy. 
       FIGS. 10-11  illustrate an exemplary embodiment of an expandable open wedge implant  240  configured for open wedge osteotomies in accordance with the present disclosure. The open wedge implant  240  is substantially similar to the open wedge implant  224  illustrated in  FIGS. 8-9 , with the exception that the open wedge implant  240  comprises a wedge body  244  which includes a first expandable portion  248  and a second expandable portion  252 , and an expander  256 . In the embodiment illustrated in  FIGS. 10-11 , each of the first and second expandable portions  248 ,  252  comprises a proximal window  260  and a pair of distal windows  264 . As best shown in  FIG. 11 , the windows  260 ,  264  in the first and second expandable portions  248 ,  252  are vertically aligned so as to form holes passing through the open wedge implant  240 . It will be appreciated that the holes operate to promote bone formation in the area of the osteotomy, and form pathways for new bone growth passing through the open wedge implant  240 . Accordingly, the expander  256  comprises openings  268  so as to minimize any obstruction of the proximal window  260  once the expander  256  has been drawn distally into the opening  144 , as described herein. It should be understood that the open wedge implant  240  is not to be limited to the number and shapes of the windows and openings illustrated in  FIGS. 10-11 , but rather any number and shape of the windows and openings may be incorporated into the open wedge implant  240  without limitation. 
     It is envisioned that open wedge implants, according to the present disclosure, are to be suitably sterilized for surgeries, and packaged into sterilized containers. In some embodiments, the wedge body  104  is packaged into a first sterile container, the expander  108  is packaged into a second sterile container, and the proximal screw  112  is packaged into a third sterile container. The first, second, and third sterile containers are then bundled together into a single, exterior container, thereby forming a convenient surgery-specific osteotomy wedge implant package. In some embodiments, the open wedge implant  100  is assembled and packaged into a single sterile container, thereby removing a need for assembly before or during surgery. It is envisioned that other packaging techniques will be apparent to those skilled in the art without deviating from the spirit and scope of the present disclosure. 
     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.