Patent Publication Number: US-11020156-B2

Title: Bone implant

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation in part application of U.S. patent application Ser. No. 14/429,783, filed Mar. 20, 2015, which is the national stage application of PCT/IB2013/002066, filed Sep. 20, 2013, which claims the benefit of prior filed U.S. Provisional Patent Application, Ser. No. 61/703,327 filed 20 Sep. 2012, which prior application is incorporated herein by reference. 
    
    
     COPYRIGHT &amp; LEGAL NOTICE 
     A portion of the disclosure of this patent document contains material which is subject to copyright protection. The Applicant has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. Further, no references to third party patents or articles made herein is to be construed as an admission that the present invention is not entitled to antedate such material by virtue of prior invention. 
     FIELD OF THE INVENTION 
     This invention relates to a system, devices and methods for bone reinforcement, especially for the treatment of osteoporosis. 
     BACKGROUND OF THE INVENTION 
     Osteoporosis, the reduction of bone density, is one of the major reasons for femoral neck fractures, affecting millions of elderly people worldwide each year. It is, however, increasingly becoming a problem also for young female athletes (see, e.g., Female Athlete Triad, Switzerland. Magazine for “Sportmedizin und Sporttraumatologie” 48 (3), 119-132 (2000), the content of which is incorporated herein by reference). For the treatment of osteoporosis according to the invention, it is essential that the presence of osteoporosis can reliably be diagnosed. There are indeed a number of ways for the diagnosis of osteoporosis and the prediction of bone fracture. The most widely used is dual energy X-ray absorptiometry (DXA). DXA scans are primarily used to measure the areal bone mineral density. An even more reliable method, yielding directly the volume density of a bone, is computed quantitative computer tomography (see for example http://en.wikipedia.org/wiki/Dual-energy X-ray absorptiometry. the entire content of which is hereby incorporated by reference)(See  FIGS. 11, 12A, 12B and 13 ). These figures are referred to as a matter of background information and show, in  FIG. 12 , a DXA scanner adapted to scan the body to evaluate bone mineral density using dual-energy X-ray absorptiometry.  FIGS. 12A and 12B  are schematic views of a DEXA assessment of bone mineral density of the femoral neck and of the lumbar spine, respectively.  FIG. 13  is the output of a full body scan is shown on a screen of a DEXA scanner. 
     One way to prophylactically treat osteoporosis is through the use of pharmaceuticals, which, besides being of limited effectiveness, are often hampered by serious side effects. A better solution seems, therefore, to be the use of prophylactic implants, enhancing the mechanical stability of the bone, thus providing a local and not a systemic way to address the problem. Such implants are generally introduced in either of a number of ways, such as (1) through a bore in the greater trochanter along the femoral neck axis (see for example U.S. Pat. No. 6,679,890 to Margulies and U.S. Pat. No. 6,319,255 to Grundei, the contents of which are hereby incorporated by reference); (2) through the intramedullary canal of the proximal femur (see for example U.S. Pat. No. 8,012,155 to Prygoski, the content of which is hereby incorporated by reference); (3) through a bore in Ward&#39;s triangle (see for example US 2009/0112210 to Philippon, the content of which is hereby incorporated by reference). 
     It is a general feature of the prior art that the bore has been made from the side, i.e. in a plane containing the femur body, the femoral neck and the femoral head. This, however, may damage the surrounding soft tissue. 
     What is needed is a reliable, simple method of reinforcing osteoporotic bone. What is needed is a method that is devoid of any of the systemic side effects of drugs, while being minimally invasive to avoid soft tissue damage. 
     SUMMARY OF THE INVENTION 
     A system, device and method is provided for the treatment of osteoporotic bones, especially of the femoral neck. The system includes a device for positioning the implant under optical and X-ray control, an implant and an applicator for screwing and expanding the implant. The implant includes an insert body and an expansion tube with cut-outs and slits defining legs. The legs expand radially through windows in the insert body when the expansion tube is pushed against the sloped distal portion of the insert body. The expansion process may be better ensured by an anti-rotation device, which prevents the expansion tube from rotating within the insert body. The applicator and implant are provided with means preventing cold welding during the implantation process. 
     It is another object of the invention to provide a means for minimal invasiveness during the introduction of a hip implant. 
     It is another object of the invention to provide an expandable structure within bone, which is able to guide healthy cortical bone to less functional trabecular bone areas, thereby enhancing its stability. 
     It is another object of the invention to provide accurate and simple positioning of a hip implant. 
     It is another object of the invention to provide a hip implant and an applicator for its positioning, insertion and expansion. 
     It is another object of the invention to provide a method for the creation of a hip implant under optimal visual and X-ray control. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic view of the positioning of a hip implant in the region of Ward&#39;s triangle. 
         FIG. 1B  is a schematic view of an alternative positioning of a hip implant into the region of Ward&#39;s triangle. 
         FIG. 2A  is a side view of an unassembled hip implant. 
         FIG. 2B  is a perspective view of an unassembled hip implant.  FIG. 2C  is a perspective view of an assembled hip implant before expansion.  FIG. 2D  is a perspective view of an assembled hip implant after expansion.  FIG. 3A  is a perspective view of an applicator for inserting a hip implant. 
         FIG. 3B  is a detailed perspective view of components of the applicator. 
         FIG. 3C  is a detailed perspective view of a hip implant mounted on an assembled applicator. 
         FIG. 4  is a perspective view of the applicator with a mounted implant and integrated positioning control. 
         FIG. 5A  is a side view of another embodiment of a hip implant in unassembled form.  FIG. 5B  is a side view of the embodiment of  FIG. 5A , in an assembled form. 
         FIG. 6A  is a perspective view of the embodiment of  FIG. 5A  in unassembled form.  FIG. 6B  is a perspective view of the embodiment of  FIG. 5A  mounted on the applicator.  FIG. 6C  is a side view of the embodiment of  FIG. 5A  mounted on the applicator. 
         FIG. 7A  is a side view of a device for controlling the position of hip implants, before implant hole drilling and implant positioning. 
         FIG. 7B  is a side view of the device of  FIG. 7A  for controlling the position of hip implants, after implant hole drilling and during positioning. 
         FIG. 8  is a method for inserting and forming a hip implant. 
         FIG. 9  is . . . a method of the invention for treating osteoporosis. 
         FIG. 10A  is a schematic, exploded view showing more detail of the alternative placement strategy illustrated in  FIG. 1B . 
         FIG. 10B  is a schematic, assembled view showing more detail of the alternative placement strategy illustrated in  FIG. 1B . 
         FIG. 11  is a device used for measuring bone density using dual-energy X-ray absorptiometry. 
         FIGS. 12A and 12B  are schematic views of a DEXA assessment of bone mineral density of the femoral neck and of the lumbar spine, respectively. 
         FIG. 13  is a schematic view of a full body scan appearing on a screen of a DEXA scanner. 
     
    
    
     Those skilled in the art will appreciate that elements in the Figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, dimensions may be exaggerated relative to other elements to help improve understanding of the invention and its embodiments. Furthermore, when the terms ‘first’, ‘second’, and the like are used herein, their use is intended to distinguish between similar elements and not necessarily for describing a sequential or chronological order. Moreover, relative terms like ‘front’, ‘back’, ‘top’ and ‘bottom’, and the like in the Description and/or in the claims are not necessarily used for describing exclusive relative position. Those skilled in the art will therefore understand that such terms may be interchangeable with other terms, and that the embodiments described herein are capable of operating in other orientations than those explicitly illustrated or otherwise described. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following description is not intended to limit the scope of the invention in any way as they are exemplary in nature, serving to describe the best mode of the invention known to the inventors as of the filing date hereof. Consequently, changes may be made in the arrangement and/or function of any of the elements described in the exemplary embodiments disclosed herein without departing from the spirit and scope of the invention. 
     In the following, a complete system of hip implants and its use will be described. The system comprises the implant itself, and additional devices or “applicators” used for precise positioning of the implant. 
     Referring now to  FIG. 1A , part of a femur  100  is shown, with femur body  102 , greater trochanter  104 , femur head  106  and femur neck  108 . The bore  110  for a hip implant is drilled through the cortical bone over Ward&#39;s triangle region of the femur neck, in a direction perpendicular to the plane containing femur body  102 , femur neck  108  and femur head  106 . According to the invention, this positioning of the bore has proven to be minimally invasive, as it minimizes soft tissue damage while placing the implant. The size of bore  110  is in the range of 4 to 8 mm, preferably about 5 mm. Circle  120  indicates the maximal reach in terms of lateral expansion of the implant. The diameter of the circle  120  is, for example, in the range of 4.6 cm, and it may be obtained using an implant having 1.9 cm long legs (see for example  FIGS. 2 and 5 ). In another embodiment (not shown) having longer legs, regions of the femoral head  106  or the greater trochanter  104  may be reached. 
     As an alternative placement strategy illustrated in  FIG. 1B , the hip implant  200  of the present invention may be inserted into the region of the femoral neck  108  from the greater trochanter region  104  of the femur  100 . In accomplishing this placement strategy, a bore  110 ′ is made from the greater trochanter  104  toward the femoral head  106  axially to the femoral neck  108  and perpendicular to a plane  120 ′ of the cross-section of the neck  108 . Using this positioning strategy, the regions of the femoral head  106  and the greater trochanter  104  may also be reached by adjusting the depth of the bore  120 ′. 
     Referring now to  FIGS. 2A-2B , the unassembled components of a hip implant  200  are shown, along with an implant in its assembled state (see  FIG. 2C ) and finally in expanded form (see  FIG. 2D ). Referring in particular to  FIGS. 2A-2B , the main components are made up of two parts, a guiding insert body  210  which is screwed into the bore  110 , and an expansion tube  230  with slits  232  and cut-outs  233 , which, when deformed, form at least two and preferably four or more legs  234 .  FIG. 2A  shows an optional cap  240  for sealing the implant at its proximal end. The insert body  210  is made up of a proximal portion  217  and a distal portion  216  connected at the distal end  211  of the proximal portion  217  by arms  213  to a proximal end  218  of the distal portion  215 . The proximal portion  217  of the insert body  210  has two screw threads, the first thread  212  for screwing the implant into bore  110 , and the second thread  222 , of only a few turns located at a proximal end  215  of the proximal portion  217 , for fixing the implant to the applicator  300 ,  400  used for mounting the implant (see also  FIGS. 3A-3C and 4 ). The arms  213 , extending between the proximal portion  217  of the insert body  210  and the distal portion  216 , define windows  214 . The proximal surface  218  of the distal portion  216  of the insert body  210  is preferably sloped. The angle of the sloped surface  218  is preferably about 45 degrees with respect to the axis of insert body  210 . 
     During assembly of the implant  200 ,  500 , the expansion tube  230  may be slid into hollow insert body  210  until legs  234  make contact with the sloped surface  218  of distal portion  216 , the deflection plate, as shown in  FIG. 2C . Upon pushing expansion tube  230  further into insert body  210 , the legs  234  are deflected outside of windows  214  by being outwardly directed against the sloped surface  218 . This process initiates the lateral expansion of the legs  234  of the implant  200 ,  500 , which is shown in  FIG. 2D  in its final form. The extent to which legs  234  extend laterally depends on a number of parameters, such as the material, for example stainless steel or titanium, and thickness of expansion tube  230 , and the sloped surface  218  of the distal portion  216 , as well as the angle of the slope. 
     The insert body  210  may contain a flange  224  between screw threads  212  and  222 . As shown in  FIG. 2B , flange  224  optionally has two flat regions  226  on opposite sides of insert body  210 . According to the invention, the flat regions  226  are provided to take up the torque applied by the applicator to insert body  210  while the insert body is screwed into bore  110  (see also  FIG. 3 ). This feature minimizes the risk of cold welding of the applicator  300 ,  400  to the insert body  210  during screwing of the implant  200 ,  500  into bore  110 . 
     Referring now to  FIG. 3 , a first embodiment  300  of an applicator  300  for screwing the implant  200  into bore  110  may comprise a tube  340  into which guiding insert body  210 ,  310  can be screwed. In order to avoid the torque being applied to screw thread  222  during screwing the sleeve into the cortical bone, which may run the risk of cold welding the threads, a second tube  350 , the inner diameter of which exceeds the outer diameter of tube  340 , is slid onto tube  340 . The end facing the implant of tube  350  may contain extensions  352  on opposite sides, as shown in  FIGS. 3A-3B . These extensions interface with the flat regions  326  of insert body  210 ,  310 , as shown in  FIG. 3C . The torque exerted during screwing the guiding sleeve into the cortical bone may hence be applied to the flat regions  326 , whereby the risk of cold welding of any parts is minimized. Torque may be applied by means of lever  356  which may be inserted into holes  354  in tube  350 . Larger holes in inner tubes  340 ,  360  help ensure that the torque exerted by lever  356  is exerted primarily on the outer tube  350 . Torque is also applied on tube  340 , but only to a small extent. It is important to note that the torque is not transmitted primarily to the screw thread but instead to the flats  226 . 
     Once the insert body  210  has been properly screwed into the bore and the lever  356  removed, an innermost tube  360  may serve to push expansion tube  230  towards the sloped surface  218  of the distal portion  216 ,  316 , thereby expanding legs  234 ,  334  into the inner space of the femur neck  108 . 
     Referring now to  FIG. 4 , another embodiment  400  of an applicator provides a more accurate positioning of the implant  200 ,  500  under optical and X-ray control. Here, the outermost tube  350 ,  450  exerting the torque on insert body  310 ,  410  during the torquing of screw thread  312 ,  412  into the cortical bone may contain guiding grooves  458 . These guiding grooves keep slider  470  from rotating around the axis of the applicator as it slides along tube  350 ,  450 . Slider  470  may contain optical marks  472  facing the surgeon during the operation, allowing him to position legs  234 ,  334  accurately with respect to the axis of femoral neck  108 . Additional positioning control may be accomplished by providing X-ray absorbing material  474  aligned with optical marks  472  of slider  470 . This permits direct observation by X-rays in addition to the visual method of positioning the implant. Applicator  400  may furthermore be equipped with lever  482  by means of which the innermost tube  460  can be pushed against expansion tube  230  in order to expand legs  234 ,  334  of expansion tube  230 . Removable cap  462  screwed onto the innermost tube  460  may prevent pushing of expansion tube  230  by any accidental movement of lever  482 . 
     Referring now to  FIG. 5 , another embodiment  500  of insert body  510  may contain a section  525  above screw thread  212 ,  312 ,  512  which may be shorter than the corresponding section of insert body  210 ,  310 . Accordingly, the screw thread  522  used for attaching insert body  510  to applicator  400  may be located on the inside of section  525 , as shown in FIGS. SA-SB. This has the advantage of causing even less soft tissue damage during implantation, because of a less protruding outermost tube of applicator  400  (see also  FIG. 6 ). This design also allows a more shallow structure outside of the femoral neck, which advantageously reduces irritation of soft tissue. 
     Referring now to  FIG. 6A-6C , this embodiment of the insert body  510 ,  610  optionally incorporates an anti-rotation device  627 , which in one embodiment is essentially a specially shaped frame of window  214 ,  614 , as shown in  FIGS. 6B-6C . This shape prevents expansion tube  230 ,  530 ,  630  from rotating while it is pushed into the insert body and during the positioning of the implant in the bone. As a result, legs  234 ,  534 ,  634  are free to expand through window  214 ,  614 , while expansion tube  230 ,  530 ,  630  is pushed against the inclined or sloping surface  218 ,  518 ,  618  of distal portion  216 ,  516 ,  616 . The flats  626  of section  525  are formed to absorb the torque exerted by the extensions  652  of applicator  400  while the insert body  510 , 610  is screwed into the bore  110 . 
     In other embodiments insert body  210 ,  310 ,  410 ,  510 ,  610  of the implant  200 ,  500  may be fastened in different ways to applicator  300 ,  400  rather than by screw thread  222 ,  522 . The fastening mechanism may, for example, comprise a bayonet lock, a clamping fastener, or any other means by which the applicator is detachable from the insert body of the implant after the latter has been screwed into bore  110  and expanded. 
     Referring now to  FIG. 7 , the system for forming a hip implant may comprise an additional device  700  for precise implant positioning. Device  700  may comprise a guiding tube  790  which may be placed on the cortical bone  792  at the chosen location of bore  110 ,  793 , as shown in  FIG. 7A . Guiding tube  790  is provided with optical markers with respect to which optical markers  472 ,  772  on slider  470 ,  770  of the applicator are aligned in order to allow precise positioning of the implant, as shown in  FIG. 7B . Guiding tube  790  may furthermore be equipped with markers  796 , made from X-ray absorbing material, aligned with the optical marks  794 . During the operation, markers  796  may be aligned under X-ray control with X-ray markers  474 ,  774  on slider  470 ,  770  of the applicator, allowing for even better control of the process of implant formation and positioning. In addition, alignment of optical markers  794  with the guiding grooves  458  or other optical lines, marks, etc. on tube  350 ,  450 ,  650  without the use of the slider  470 , may aid in positioning the implant. 
     Referring now to  FIG. 8 , a method  800  for the use of the system for forming a hip implant includes any one of a list of steps: in an optional first step  810 , performing diagnostic tests for osteoporosis; in a second step  812 , choosing the location of the implant; in a third step  814 , placing a guiding tube  790  for positioning control; in a fourth step  816 ; forming the bore under precise positioning control; in a fifth step  818 , inserting the implant by means of an applicator through the guiding tube; in a sixth step  820 , screwing the implant into the bone; in a seventh step  822 , expanding the implant; in an eight step  824 , optionally filling the implant and adjacent cancellous bone regions by a filler material (including calcium phosphate, bone cement or the like) preferably through the applicator; in a ninth step  826 , removing the applicator; and, in a tenth step  830 , optionally inserting a cap for sealing the implant. 
     The assembled hip implant  200 ,  500  has an aperture or bore  231 ,  631 ,  631 ′ passing through its central axis. When the hip implant  200 ,  500  device is installed, this central bore  231 ,  631 ,  631 ′, it can allow access to the cancellous region of the bone. Utilizing the aperture or bore  231 ,  631 ,  631 ′, other prosthetics or instruments (e.g., a trocar) and/or biological agents (e.g., a bone growth biologic) can be inserted into the implant site. 
     Referring now to  FIG. 9 , in another embodiment, a method of treating osteoporosis is provided which directs healthy cortical bone to less functional trabecular bone areas, thereby substituting the less functional trabecular areas of the bone with healthy bone mass, the method including several steps. In a first step  910 , the insert is inserted into a bone. In a second step  920 , the insert is expanded inside the bone. In a third step  930 , a bone growth promoter is optionally inserted through the insert into the bone. In a fourth step  940 , the osteoconductive properties of the insert are used to attract and guide bone growth. The osteoconductive properties of said insert may be enhanced by surface treatment or coating of the insert with bone growth enhancing substances or structures. Additionally, the insertion and making of the implant provides a bridging from cortical to trabecular bone areas in a flexible way. Mechanical force from the cortical bone areas may be transduced to the implant body and legs, thereby stimulating bone growth by the intrinsic property of bone to rebuild and restructure at sites of mechanical loading. By designing and making of said implant in a semi-rigid, rather than rigid way, stress shielding with all negative consequences on the stability of the bone is avoided. The rationale behind this is, that the quality of bone can deteriorate in the vicinity of implants due to stress shielding. Because bone is a dynamic tissue, it reacts on loading by building up tissue and gets weaker, when not loaded. By repeatedly transducing the force from cortical areas (via the insert and legs) to trabecular areas, these areas may react by bone growth stimulation/or the ingrowth from cortical areas may be of better quantity and quality. 
     Referring now to  FIGS. 10A and 10B , which show more detail of the alternative placement strategy illustrated in  FIG. 1B , the hip implant  200 ′ of the present invention having a body  510 ′ elongated to a length X (to suit the patient&#39;s particular bone size) when compared to the other embodiments presented herein, may be inserted such that the legs  234 ′ may be extended into the region of the femoral neck  108  by insertion of the implant  200 ′ from the greater trochanter region  104  of the femur  100 . Threads  512 ′ may extend along the entire body  510 ′ of the implant  200 ′. However, only a few threads  512 ′ are required to be able to drive the insert  200 ′ into the desired location. Windows (not shown) are optionally added along the body  510 ′ to allow leaching out of bone growth promoting substances which may be placed therein. In accomplishing this placement strategy, a bore  110 ′ is made from the greater trochanter  104  toward the femoral head  106  axially to the femoral neck  108  and perpendicular to a plane  120 ′ of the cross-section of the neck  108 . The insert body  510 ′ is inserted in the bore  110 ′ and the tool described in  FIG. 3A-3C  drives the insert body to the desired position, where the windows  214 ′ are adjacent the femoral neck area  108 . The expansion tube  230  is then inserted, followed by a spacer  235 . The spacer  235  may be made such that it is porous to contain bone growth promoting compounds. The spacer  235  may also be a power metal pressed part, pressed together with bone growth promoting agents. This spacer  235  allows use of a standard length expansion tube  230  and permits the extrusion of the expansion tube  230  through the windows  214 ′, such that the legs  234 ′ extend through the windows  214 ′, breaking up the trabecular bone and allowing bone regrowth and reinforcement of the femoral neck  108 . A cap  240 ′ may be installed over the end of the insert  230 , to protect against damage to adjacent soft tissue. 
     It should be appreciated that the particular implementations shown and herein described are representative of the invention and its best mode and are not intended to limit the scope of the present invention in any way. For instance, tapping in of the innermost tube  360 ,  460  into the guiding insert body  210 ,  510  with a rod- or trocar-like instrument (not shown) and a mallet (not shown) is an alternative method for expanding the implant  200 , 500 . Of course, there are any number of different ways to press the expansion tube  230 ,  530  into the guiding insert body  210 ,  510  such as by turning a thread which drives the expansion tube therein. In addition, the shape of the surface  218 ,  518  of the deflection plate  216 ,  516  may comprise any shape suitable for deflecting and even directing the deflection of the legs  234 ,  534 . For example, the selection of an appropriate shape for the legs  234 ,  534  and the deflection plate  216 ,  516  may be made to cause the legs to spiral through the cancellous bone, in order to create a larger cavity. 
     Moreover, the system contemplates the use, sale and/or distribution of any goods, services or information having similar functionality described herein. 
     The specification and figures should be considered in an illustrative manner, rather than a restrictive one, and all modifications described herein are intended to be included within the scope of the invention claimed. Accordingly, the scope of the invention should be determined by the appended claims (as they currently exist or as later amended or added, and their legal equivalents) rather than by merely the examples described above. Steps recited in any method or process claims, unless otherwise expressly stated, may be executed in any order and are not limited to the specific order presented in any claim. Further, the elements and/or components recited in apparatus claims may be assembled or otherwise functionally configured in a variety of permutations to produce substantially the same result as the present invention. Consequently, the invention should not be interpreted as being limited to the specific configuration recited in the claims. 
     Benefits, other advantages and solutions mentioned herein are not to be construed as critical, required or essential features or components of any or all the claims. 
     As used herein, the terms “comprises”, “comprising”, or variations thereof, are intended to refer to a non-exclusive listing of elements, such that any apparatus, process, method, article, or composition of the invention that comprises a list of elements that includes not only those elements recited, but may also include other elements described in the instant specification. Unless otherwise explicitly stated, the use of the term “consisting” or “consisting of” or “consisting essentially of” is not intended to limit the scope of the invention to the enumerated elements named thereafter, unless otherwise indicated. Other combinations and/or modifications of the above-described elements, materials or structures used in the practice of the present invention may be varied or adapted by the skilled artisan to other designs without departing from the general principles of the invention. 
     The patents and articles mentioned above are hereby incorporated by reference herein, unless otherwise noted, to the extent that the same are not inconsistent with this disclosure. 
     Other characteristics and modes of execution of the invention are described in the appended claims. 
     Further, the invention should be considered as comprising all possible combinations of every feature described in the instant specification, appended claims, and/or drawing figures, which may be considered new, inventive and industrially applicable. 
     Copyright may be owned by the Applicant(s) or their assignee and, with respect to express Licensees to third parties of the rights defined in one or more claims herein, no implied license is granted herein to use the invention as defined in the remaining claims. Further, vis-a-vis the public or third parties, no express or implied license is granted to prepare derivative works based on this patent specification, inclusive of the appendix hereto and any computer program comprised therein. 
     Additional features and functionality of the invention are described in the claims appended hereto. Such claims are hereby incorporated in their entirety by reference thereto in this specification and should be considered as part of the application as filed. 
     Multiple variations and modifications are possible in the embodiments of the invention described here. Although certain illustrative embodiments of the invention have been shown and described here, a wide range of changes, modifications, and substitutions is contemplated in the foregoing disclosure. While the above description contains many specific details, these should not be construed as limitations on the scope of the invention, but rather exemplify one or another preferred embodiment thereof. In some instances, some features of the present invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the foregoing description be construed broadly and understood as being illustrative only, the spirit and scope of the invention being limited only by the claims that ultimately issue in this application.