Abstract:
Apparatus and method for microfracture surgery to create apertures in a bone tissue surface comprising uniform depth by controlling an insertion length. Verification of insertion length may be accomplished through the use of a color-coded kit wherein each microfracture surgery apparatus comprises a color-coded handle associated with an insertion length and offset angle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application incorporates by reference and claims priority to U.S. Provisional Application Ser. No. 60/991,303, which was filed on Nov. 30, 2007. 
     
    
     FIELD OF THE INVENTION T 
       [0002]    he invention relates to a microfracture surgery apparatus and a method for facilitating the growth of new cartilage. In certain embodiments, the invention comprises a kit comprising a plurality of microfracture surgical devices. 
       BACKGROUND OF THE INVENTION 
       [0003]    Microfracture surgery is an orthopedic surgical technique that can help restore knee cartilage by creating tiny fractures in the adjacent bones, causing new cartilage to develop. It can be used to treat both degenerative knee problems as well as cartilage injuries. The surgery is performed through an arthroscopy. The surgeon first removes any damaged cartilage. Tiny fractures are then created in the adjacent bones through the use of an awl. Blood and bone marrow (which contains stem cells) seep out of the fractures, creating a blood clot that releases cartilage-building cells. The microfractures are treated as an injury by the body, which is why the surgery results in new, replacement cartilage. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    The invention will be better understood from a reading of the following detailed description taken in conjunction with the drawings in which like reference designators are used to designate like elements, and in which: 
           [0005]      FIG. 1A  is a perspective view of a prior art surgical device; 
           [0006]      FIG. 1B  is a perspective view of Applicant&#39;s microfracture surgery apparatus; 
           [0007]      FIG. 2A  shows a second embodiment for the handle portion of the microfracture surgery apparatus of  FIG. 1B ; 
           [0008]      FIG. 2B  shows a third embodiment for the handle portion of the microfracture surgery apparatus of  FIG. 1B ; 
           [0009]      FIG. 2C  shows a fourth embodiment for the handle portion of the microfracture surgery apparatus of  FIG. 1B ; 
           [0010]      FIG. 3  is a side view of extension member  120  and offset extension member  130 ; 
           [0011]      FIG. 4  is a side view of offset extension member  130  and insertion portion  130 ; 
           [0012]      FIG. 5A  shows a side view of one embodiment of the tip portion of Applicant&#39;s microfracture surgery apparatus; 
           [0013]      FIG. 5B  shows a top view of the tip portion of  FIG. 5A . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    This invention is described in preferred embodiments in the following description with reference to the Figures, in which like numbers represent the same or similar elements. Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. 
         [0015]    The described features, structures, or characteristics of the invention may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are recited to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention. 
         [0016]    As those skilled in the art will appreciate, injured joint surface cartilage does not heal. Using microfracture surgery techniques, a surgeon first denudes the bone surface by removing any injured bone surface cartilage. Holes are then formed in the denuded bone surface.  FIG. 1A  illustrates a prior art device  10 , sometimes referred to as a chondro pick, used to form holes in a bone surface during microfracture surgery. Tip  14  is placed against a bone surface, and insertion portion  12  is advanced into the bone. A mallet may be used to tap handle  16  thereby advancing tip  14  inwardly into bone tissue. 
         [0017]    Insertion portion  12  of prior art chondro pick  10  comprises an awl-type structure wherein insertion portion  12  tapers continuously and smoothly from a first diameter of about 0.5 inches at point  18  to a sharp point. As those skilled in the art will appreciate, the deeper the penetration of insertion portion  12  into bone tissue, the greater the injury to that hard tissue. Using prior art device  10 , it is difficult to advance insertion portion  12  a consistent distance into bone tissue. If too little force is applied, then insertion portion  12  is not advanced the desired distance into hard tissue. On the other hand, if too much force is applied, then insertion portion  12  can be advanced beyond a nominal and optimal distance into hard tissue. 
         [0018]    Referring now to  FIG. 1B , Applicant&#39;s microfracture surgery apparatus  100  comprises handle  110 , extension member  120 , offset extension member  130 , and insertion portion  140 . In certain embodiments, extension member  120  is between about 4 inches and about 10 inches in length  125 . In various embodiments, Applicant&#39;s microfracture surgery apparatus  100  can be used in surgical procedures involving various joints disposed in animals, including humans. As those skilled in the art will appreciate, by “joint,” Applicant means an areas where two or more bones meet, wherein most joints are mobile allowing the bones to move relative to one another. 
         [0019]    Such joints include, for example and without limitation, knee joints, hip joints, elbow joints, shoulder joints, and the like. As a result, optimal dimensions for handle  110  and extension member  120  may vary as a function of the anatomy of the joint being repaired. 
         [0020]    In certain embodiments, extension member  120 , offset extension member  130 , and insertion portion  140  are formed from stainless steel. As those skilled in the art will appreciate, stainless steel is defined as an iron-carbon alloy with a minimum of 10.5% chromium content. In certain embodiments, extension member  120 , offset extension member  130 , and insertion portion  140  are formed from Type  630  stainless steel, better known as 17-4; 17% chromium, 4% nickel. In certain embodiments, extension member  120 , offset extension member  130 , and insertion portion  140  are heat-treated, and comprise a Rockwell Hardness between about 40 to 44. 
         [0021]    Applicant&#39;s microfracture surgery apparatus  100  tapers twice in two discontinuous locations, first from cylindrical member  415  ( FIG. 4 ) to a first end of cylindrical member  435  ( FIG. 4 ) via truncated conical member  425  ( FIG. 4 ), and then from a second end of cylindrical member  435  to tip portion. Cylindrical member  435  comprises a constant diameter from a first end to a second end. Applicant has found that use of a wide range of applied forces to handle  110  causes the entire length of insertion portion  140  into hard tissue. As a result, a uniform depth and diameter of holes formed in bone tissue can be achieved when using Applicant&#39;s microfracture surgery apparatus  100 . In marked contrast, use of tapering prior art devices results in holes of varying depth, and also varying diameter. The use of applied force may be caused by tapping handle  110  with a hard instrument like a mallet or a machine-operated structure. 
         [0022]    In the illustrated embodiment of  FIG. 1B , handle  110  is shown comprising a cylindrical shape. In certain embodiments, handle  110  is formed from a rigid material, such as an engineering plastic, metal, and combinations thereof. By “engineering plastic,” Applicant means a polymeric material comprising a tensile modulus of about 500,000 psi or greater, and/or a flexural modulus of about 500,000 psi or greater. In certain embodiments, handle  110  is formed from aluminum. 
         [0023]    Such polymeric materials include, without limitation, one or more polyamides, one or more polyimides, one or more polyetheretherketones, one or more cured epoxy resins, and the like. As those skilled in the art will appreciate, a handle formed using an engineering plastic will have a weight of about 0.25 to about 0.50 times the weight of a metal handle. In certain embodiments, handle  110  is formed from a cellular material having a density of about one half that a handle formed using a comparable non-cellular metal or plastic. 
         [0024]    Referring now to  FIGS. 2A ,  2 B, and  2 C, in other embodiments handle  110  comprises a parallelepiped such as handle  210 . In certain embodiments, handle  210  comprises a square cross-section, wherein width  212  equals height  216 . In other embodiments, handle  210  comprises a rectangular cross-section, wherein width  212  does not equal height  216 . 
         [0025]    In certain embodiments, width  212  is between about 0.5 inches and about 2 inches. In certain embodiments, height  216  is between about 0.25 inches and about 1 inch. Handle  210  further comprises a length  214 , wherein length  214  is between about 4 inches and about 8 inches. 
         [0026]    Referring now to  FIG. 2B , in other embodiments handle  110  comprises a hexagonal cross-section, such as handle  220 . Handle  220  comprises width  222 , height  226 , and length  224 . In certain embodiments, width  222  is between about 0.5 inches and about 2 inches. In certain embodiments, height  226  is between about 0.25 inches and about 1 inch. In certain embodiments, length  224  is between about 4 inches and about 8 inches. 
         [0027]    Referring now to  FIG. 2C , in other embodiments handle  110  comprises an octagonal cross-section, such as handle  230 . Handle  230  comprises width  232 , height  236 , and length  234 . In certain embodiments, width  232  is between about 0.5 inches and about 2 inches. In certain embodiments, height  236  is between about 0.25 inches and about 1 inch. In certain embodiments, length  234  is between about 4 inches and about 8 inches. 
         [0028]    Referring now to  FIG. 3 , a centerline  320  of offset extension member  130  and a centerline  330  of extension member  120  define an offset angle Θ. In certain embodiments, offset angle Θ equals 0 degrees. In certain embodiments, offset angle Θ is about 15 degrees. In certain embodiments, offset angle Θ is about 30 degrees. In certain embodiments, offset angle Θ is about 45 degrees. In certain embodiments, offset angle Θ is about 60 degrees. In certain embodiments, offset angle Θ is about 90 degrees. 
         [0029]    Offset extension member  130  in combination with insertion portion  140   10  comprises an length  310 . In certain embodiments, length  310  is about 0.25 inches. In certain embodiments, length  310  is about 0.50 inches. 
         [0030]    In certain embodiments, handle  110  is color-coded with various markings to separately indicate the different offset angles Θ and lengths  310 . The following example is presented to further illustrate to persons skilled in the art how to make and use the invention. This example is not intended as a limitation, however, upon the scope of the invention. 
       EXAMPLE 
       [0031]    In certain embodiments handle  110  comprises a first color-coded marking to indicate a first embodiment of microfracture surgery apparatus  100  wherein length  310  is 0.25 inches, and angle Θ is 30 degrees, wherein a first insertion length marking is identified from a group of varying colors, shades, and other graphics and a first offset angle marking is identified from a group of varying colors, shades, and other graphics. 
         [0032]    In certain embodiments handle  110  comprises a second marking to indicate a second embodiment of microfracture surgery apparatus  100  wherein length  310  is 0.50 inches and angle Θ is 15 degrees, wherein a second length marking is identified from a group of varying colors, shades, and other graphics, wherein second insertion length marking differs from said first insertion length marking and a second offset angle marking is identified from a group of varying colors, shades, and other graphics, wherein second offset angle marking differs from said first offset angle marking. 
         [0033]    In certain embodiments handle  110  comprises a third marking to indicate a third embodiment of microfracture surgery apparatus  100  wherein length  310  is 0.25 inches and angle Θ is 90 degrees, wherein a third offset angle marking is identified from a group of varying colors, shades, and other graphics, and wherein the third offset angle marking differs from the first and second offset angle markings and a third insertion length marking is identified from a group of varying colors, shades, and other graphics, wherein third insertion length marking differs from the first and second insertion length markings. 
         [0034]    In certain embodiments handle  110  comprises a fourth marking to indicate a fourth embodiment of microfracture surgery apparatus  100  wherein length  310  is 0.50 inches and angle Θ is 60 degrees, wherein a fourth offset angle marking is identified from a group of varying colors, shades, and other graphics, and wherein the fourth offset angle marking differs from the first, second and third offset angle markings and a fourth insertion length marking is identified from a group of varying colors, shades, and other graphics, wherein fourth insertion length marking differs from the first, second, and third insertion length markings. 
         [0035]    Referring now to  FIGS. 1B and 4 , offset extension member  130  comprises wedged-shaped member  405 , cylindrical member  415 , and truncated conical member  425 . Wedged-shaped member  405  and cylindrical member  415  comprise a diameter  410 . In certain embodiments, diameter  410  is between about 0.06 inches to about 0.20 inches. In certain embodiments, diameter  410  is about 0.10 inches. Truncated conical member  425  tapers from diameter  410  to diameter  420 . In certain embodiments, diameter  420  is between about 0.04 inches to about 0.125 inches. 
         [0036]    Insertion portion  140  comprises cylindrical member  435  and conical member  445 . Cylindrical member  435  comprises diameter  420 . Conical member  445  tapers from diameter  420  to diameter  430  at tip portion  150 , wherein diameter  430  is between about 0 inches to about 0.010 inches. 
         [0037]    In certain embodiments conical member  445  uniformly tapers to tip portion  150  as shown in  FIG. 4 . In other embodiments, conical member  445  comprises a more complex shape. For example in the illustrated embodiment of  FIGS. 5A and 5B , conical member  445  comprises  4  surfaces, namely surfaces  510 ,  520 ,  530 , and  540 .  FIG. 5A  shows a side view of this embodiment of conical member  445 , and  FIG. 5B  shows a top view. Opposing surfaces  530  and  540  have been “flattened” such that conical member  445  comprises a “chisel-like” shape. 
         [0038]    Cylindrical member  435 , and conical member  445 , in combination, comprise insertion portion  140 . In certain embodiments, insertion portion  140  comprises a length between about 0.20 inches and about 0.30 inches. In certain embodiments, insertion portion  140  comprises a length of about 0.24 inches. 
         [0039]    While the preferred embodiments of the present invention have been illustrated in detail, it should be apparent that modifications and adaptations to those embodiments may occur to one skilled in the art without departing from the scope of the present invention.