Patent Publication Number: US-11653913-B2

Title: Orthopedic implant, method, and kit

Description:
TECHNICAL FIELD 
     The invention is in the field of bone implants, and in certain embodiments relates to opening wedge implants used in osteotomy procedures. 
     BACKGROUND 
     Many osteotomy procedures have been devised, these including such procedures as the lateral column lengthening (Evans Osteotomy) and the plantarflexion osteotomy of the medial cuneiform (Cotton Osteotomy) for flatfoot correction. Such procedures generally involve cutting an opening in the bone of a patient, or between bone segments of a patient, and including a wedge or spacer to thereby lengthen the bone or maintain spacing between the bone segments. After the spacer has been inserted between the bone or bone segments, it is generally recommended to provide a means to retain the spacer in place while the bone heals in the case of allograft wedges, or indefinitely in the case of metal spacers. This is likewise necessary when creating an open wedge osteotomy at the base of the first metatarsal bone, a common procedure to address hallux vulgus (bunion deformity). 
     A number of implant-related devices are known for this purpose. A typical device comprises a plate with threaded openings for engaging bone screws that are screwed into the patient&#39;s bone. Some such plates are provided with integral metal wedges, although other such plates are provided without wedges for use with allograft bone wedges or for use with separate titanium bone wedges. While such structures may be successful in provided ancillary plate fixation, they can be difficult to install and ultimately can become uncomfortable for the patient. This is particularly true in foot surgeries, where plates used to secure them are very prominent on the bone and can cause soft tissue and nerve irritation, as the soft tissue structure on the lateral aspect of the calcaneous, the dorsal aspect of the medial cuneiform, and the medial aspect of the base of the first metatarsal are all limited. Given these side effects, in some instances, surgeons have placed wedges without the benefit of ancillary fixation, even though this approach is not recommended. It would be desirable to provide a spacer or spacer implant that is easier to install and more comfortable for the patient than the heretofore described approaches. 
     Generally, it has now been found that an implant that comprises a spacer portion and an integral staple portion, at least the staple portion comprised of a material that has superelastic properties when at the temperature of the human body, may now be provided. The spacer portion has a superior portion and an inferior portion. The staple portion has a crown portion and first and second leg portions that converge from the crown portion. The first and second leg portions are configured to provide a compressing biasing force when the implant is installed with the legs under tension. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of an orthopedic implant in accordance with one embodiment. 
         FIG.  2    is a top plan view of the orthopedic implant shown in  FIG.  1   . 
         FIG.  3    is a side elevational view of the orthopedic implant shown in  FIG.  1   . 
         FIG.  4    is a side elevational view of the orthopedic implant shown in  FIG.  1   , showing the legs of the staple portion of the implant in tension. 
         FIG.  5    is a side elevational view of a kit that includes the orthopedic implant shown in  FIG.  1    positioned in an insertion tool. 
         FIG.  6    depicts a kit that comprises the kit of  FIG.  5    and additionally a drilling template. 
         FIG.  7    is a perspective view of an orthopedic implant in accordance with a second embodiment. 
         FIG.  8    is a plan view of the surgical region of a patient&#39;s medial cuneiform with a portion of the patient&#39;s bone removed in preparation for insertion of an orthopedic implant as part of an osteotomy procedure, and with pilot holes drilled for the staple legs. 
         FIG.  9    is a plan view of a patient&#39;s surgical region after the implant has been installed as part of the osteotomy procedure. 
         FIG.  10    is similar to  FIG.  9    but depicting the surgical region after installation of the implant of  FIG.  7    in a Cotton Osteotomy procedure. 
         FIG.  11    illustrates an alternative embodiment of an orthopedic implant. 
         FIG.  12    depicts a surgical region after the installation of the implant of  FIG.  11    in an Evans Osteotomy procedure. 
         FIG.  13    depicts a surgical region after the installation of a base opening implant for correction of Hallux Valgus. 
     
    
    
     Terms of orientation are for convenient reference to the drawings and are not intended to limit the orientation of the implant in use. 
     DESCRIPTION 
     In general, an orthopedic implant having a spacer portion, or wedge, and a staple portion is provided. The spacer portion has a superior portion and an inferior portion. The staple portion has a first crown portion and first and second leg portions, the first and second leg portions having distal ends that converge from the first crown portion. The first crown portion is connected into the spacer portion proximal to the superior portion. The spacer portion extends in the inferior direction generally towards the distal end of the first and second legs. At least the staple portion, and preferably the entire implant, comprise a material that has superelastic properties, such as many known nickel-titanium alloys (“Nitinol”). The implant is installed into a patient while the legs are under tension, whereby, given the superelastic composition of the leg portions, the first and second leg portions are configured to impart a compressive biasing force on the bone structure of the patient. Via this approach, the implant is resistant to becoming dislodged and the implant creates ancillary support for the spacer portion. 
     As depicted in  FIG.  1   , the exemplary implant  20  comprises a spacer portion  21  and a staple portion  22 , these portions being integral with one another, and, in the illustrated embodiment, composed monolithically of a superelastic nickel-titanium alloy. The staple portion comprises a crown portion  24  and first and second leg portions  25 ,  26 . The first and second leg portions  25 ,  26  have respective distal ends  28 ,  29  that converge from the first crown portion  24 . The crown portion  24  is connected to the spacer portion  21  proximal to the superior portion  30  of the spacer portion. As illustrated, the spacer portion  31  extends from the superior portion  30  to the inferior portion  31  in the inferior direction generally towards the distal ends  28 ,  29  of the first and second leg portions  25 ,  26 . The crown portion  24  of the staple portion  22  is disposed in a position superior to the superior portion  30  of the spacer portion  21 . 
     As also illustrated in  FIG.  1    and as further shown in  FIG.  3   , each of the first and second leg portions  25 ,  26  has a bone retaining feature, which, in the illustrated embodiment, comprises a plurality of barbs  34  disposed on the inner surfaces  35 ,  36  of the leg portions  25 ,  26 . With further reference to  FIG.  3   , the superior portion  30  has a greater lateral dimension  38  than the lateral dimension  39  of the inferior portion  31  to thereby impart a wedge shape to the spacer portion. In practice, the lateral dimensions of the superior and inferior portions  30  and  31 , the lateral extent of the crown portion  24 , and the lengths of the legs  25 ,  26  may be varied substantially and an implant manufacturer may provide several sizes to accommodate various patients and types of operations. 
     The material is composed of a superelastic material, generally a metal alloy, such as Nitinol, a nickel-titanium alloy. Superelasticity is a well-recognized phenomenon of certain alloys in which the material deforms reversibly in response to an applied stress. For the present implants, the material should be superelastic at the normal body temperature of the intended patient, which, in the case of human patient, is in the range of about 95 degrees to 100° F. Generally, the superelastic property of the material when at this temperature causes the legs  25 ,  26  to bias inwardly as illustrated by arrows  33  in  FIG.  4    when moved to a more open position. Via this approach, the first and second portions are configured to impart a compressive biasing force when the implant is installed with the legs under tension. 
     In use, the implant typically is provided in the form of a kit, which, as shown in  FIG.  5   , may be kit  40 . The kit  40  shown in  FIG.  5    comprises the implant  20  and an insertion tool  41  that releasably holds the implant and that maintains the first and second legs in tension via clips or other suitable retainers (not shown). The illustrated insertion tool  41  is intended to be exemplary and is typical of tools known for insertion of conventional surgical staples, and, as supplied, it retains the implant  20  with the legs in tension relative to the original state of the legs. The tool  41  comprises a handle  42  and plunger  44  with biasing rod  45 , and is configured such that, when the plunger  44  is manually depressed, the biasing rod  45  moves relative to the handle  42  and urges the implant  20  to separate from the insertion tool blank. Preferably, as shown in  FIG.  6   , the kit  40  further includes a drilling template  46  having first and second pilots  47 ,  48  that are generally spaced apart at the same distance  51  that separates the first and second leg portions  25 ,  26  for positioning of pilot holes. Other configurations for the insertion tool, template, and kit are possible. For instance, it is contemplated that a kit may include multiple implants of varying sizes. As illustrated, the drilling template is substantially planar, although in some embodiments (not shown) the drilling template may be provided with its own spacer to assist in placement of the template. If multiple implants are available having spacers of differing sizes, then drilling templates having differently sized spacers may be used to gauge the best spacer size to be selected. 
     The form of the implant is not limited to a staple with two legs, and thus, for example, the implant may take the form of implant  50  shown in  FIG.  7   . In this embodiment the implant comprises first and second staple portions  52 ,  53  each integral with a spacer portion  55  and each comprising a material that has superelastic properties at body temperatures. Like that of the implant  20 , each of the staple portions  52 ,  53  comprises a crown portion and leg portions  59 ,  60  and  61 ,  62  that each converge from the respective crown portions and that are configured to impart a compressive biasing force when the implant is installed with the legs under tension. In this implant, the spacer portion  55  bridges the crown portions  57 ,  58  of the first and second staple portions  52 ,  53  and the wedge profile is disposed parallel to the central planes of the staples, although in some embodiments the wedge profile can be disposed laterally or at an angle relative to the staples. In this embodiment the superior transverse edges  54 ,  56  of the spacer portion  55  are generally parallel and have the same dimension as one another, and the inferior transverse edges (one shown at  63 ) are generally parallel to one another and have the same dimension as one another, the dimension of the superior edges being greater than that of the inferior edges. 
     As illustrated in  FIG.  7   , spacer portion  55  may include an optional graft window  45  (shown in hidden lines). Graft window  45  may be packed with bone graft prior to installation to assist with the formation of a solid bone bridge through the spacer portion to fuse the bone portions adjacent the spacer portion  55 . 
     Generally, the illustrated implants are useful for in osteotomy and other surgical procedures not limited to the heretofore enumerated procedures. The surgical method generally comprises surgically exposing one or more bones or bone segments in the patient, cutting the bone to create an opening suitable for insertion of the spacer, and installing an implant as described hereinabove. Using the insertion tool, the spacer is positioned in the opening between the bones or bone segments, and the legs of the staple are positioned in the bone of the patient in a matter sufficient to impart a compressive biasing force on the bones or bone segments to thereby provide ancillary fixation for the spacer portion. The implant is then released from the insertion tool and the patient is allowed to recover from the procedure. The staple portion or portions are inhibited from release from the bone or bone segments via the bone retaining feature. 
     With reference to  FIG.  8   , for instance, the patient&#39;s bone  65  has been prepared for an osteotomy procedure, wherein an opening  68  is sized to receive a wedge-shaped spacer portion of the implant  20  shown in  FIG.  1   . Using the drilling template, pilot holes  66 ,  67  have been drilled into the bone, as shown in  FIG.  8   . The implant is then installed, leaving the configuration shown in  FIG.  9   . The legs of the staple portion exert a compressive force, represented by arrows  69 , on the patient&#39;s bone or bone segments for provision of ancillary fixation. The same may be accomplished with the implant of  FIG.  7   , as depicted in  FIG.  10    in a Cotton Osteotomy procedure or in  FIG.  13    in a base opening procedure for correction of a hallux valgus deformity. In either case, a paste or putty made of bone or other suitable material may be used to fill in any gaps proximal the spacer after installation thereof. 
     With reference to  FIG.  11   , the illustrated alternative implant  70  comprises first and second staple portions  72 ,  73  each integral with a spacer portion  75  and each comprising a material that has superelastic properties at body temperatures. Like that of the implant  20 , each of the staple portions  72 ,  73  comprises a crown portion  77 ,  78  and leg portions  79 ,  80  and  81 ,  82  that each converge from the respective crown portions  77 ,  78  and that are configured to impart a compressive biasing force when the implant is installed with the legs under tension. In this implant, the spacer portion  75  bridges the crown portions  77 ,  78  of the first and second staple portions  72 ,  73  and the wedge profile is disposed transversely to the central planes of the staples. In this embodiment, the spacer portion  75  has a tapered wedged profile such that it is wider at a portion adjacent staple  73  than at a portion adjacent staple  72 . The implant of this embodiment may be useful in the performance of an Evans Osteotomy, as shown in  FIG.  12   , because the narrower wedge dimension at the inferior, or plantar, aspect of the osteotomy minimizes stress placed on the adjacent calcaneocuboid joint. In this embodiment, the superior transverse edges  83 ,  84  are converging and the inferior transverse edges (one shown at  85 ) are likewise converging. As shown, the inferior and superior edges all have the same dimension. 
     The illustrated implants are believed to provide ancillary stability for the spacer portion, and to be more comfortable to the patient than conventional bone plates. 
     Uses of singular terms such as “a,” “an,” are intended to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms. Any description of certain embodiments as “preferred” embodiments, and other recitation of embodiments, features, or ranges as being preferred, or suggestion that such are preferred, is not deemed to be limiting. The invention is deemed to encompass embodiments that are presently deemed to be less preferred and that may be described herein as such. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended to illuminate the invention and does not pose a limitation on the scope of the invention. Any statement herein as to the nature or benefits of the invention or of the preferred embodiments is not intended to be limiting. This invention includes all modifications and equivalents of the subject matter recited herein as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. No unclaimed language should be deemed to limit the invention in scope. Any statements or suggestions herein that certain features constitute a component of the claimed invention are not intended to be limiting unless reflected in the appended claims. Neither the marking of the patent number on any product nor the identification of the patent number in connection with any service should be deemed a representation that all embodiments described herein are incorporated into such product or service.