Patent Document

BACKGROUND 
       [0001]    This invention relates to an improved osteochondral autograft transplantation method and apparatus, and more particularly, to such a procedure and apparatus in which a graft is prepared for a recipient opening. 
         [0002]    The human knee consists of three bones—a femur, a tibia, and a patella—that are held in place by various ligaments. The corresponding condyles of the femur and the tibia form a hinge joint, and the patella protects the joint. Portions of the condyles, as well as the underside of the patella, are covered with an articular cartilage, which allow the femur and the tibia to smoothly glide against each other without causing damage. 
         [0003]    The articular cartilage often tears, usually due to traumatic injury (often seen in athletes) and degenerative processes (seen in older patients). This tearing does not heal well due to the lack of nerves, blood vessels and lymphatic systems; and the resultant knee pain, swelling, and limited motion of the bone(s) must be addressed. 
         [0004]    Damaged adult cartilages have historically been treated by a variety of surgical interventions including lavage, arthroscopic debridement, and repair stimulation, all of which provide less than optimum results. 
         [0005]    Another known treatment involves removal and replacement of the damaged cartilage with a prosthetic device. However, prostheses have largely been unsuccessful since they are deficient in the elastic, and therefore in the shock-absorbing, properties characteristic of the cartilage. Moreover, prostheses have not proven able to withstand the forces inherent to routine knee joint function. 
         [0006]    In an attempt to overcome the problems associated with the above techniques, osteochondral autograft transplantation, also known as “mosaicplasty” has been used to repair articular cartilages. This procedure involves removing injured tissue from the damaged area and drilling one or more openings in the underlying bone. A graft, or plug, consisting of healthy cartilage overlying bone, is obtained from another area of the patient, typically from a lower weight-bearing region of the joint under repair, or from a donor patient, and is implanted in each opening. It is extremely important that each plug fit in its opening in a precise manner, and an embodiment of the present invention involves a technique for advancing the art in this respect. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0007]      FIG. 1  is an elevational view of a human knee with certain parts removed in the interest of clarity. 
           [0008]      FIGS. 2A and 2B  are isometric views depicting the femur of the knee of  FIG. 1  and illustrating two steps in the procedure according to an embodiment of the invention. 
           [0009]      FIG. 3  depicts a copy mill apparatus according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    Referring to  FIG. 1  of the drawing, the reference numeral  10  refers, in general, to a knee area of a human including a femur  12  and a tibia  14  whose respective condyles are in close proximity. A cartilage  16  extends over a portion of the condyle of the femur  12 , and a meniscus  18  extends between the cartilage and the tibia  14 . The patella, as well as the tendons, ligaments, and quadriceps that also form part of the knee, are not shown in the interest of clarity. 
         [0011]    Referring to  FIG. 2A , which depicts the femur  12  of  FIG. 1  in an inverted position, it will be assumed that a portion of the cartilage  16  extending over the condyle of the femur  12  has been damaged and resected by the surgeon, or has worn away, leaving a damaged area, or defect  12   a . It will be also assumed that the surgeon has surgically removed areas of the bone below the damaged cartilage at the defect  12   a  so as to form an opening that is suited to receive a plug, or graft. The latter procedure can involve drilling a hole in the underlying bone to a predetermined depth, as shown. 
         [0012]    A graft is harvested from another area of the patient/recipient, such as an undamaged non-load bearing area of the femur or tibia, or from a corresponding area of a donor, in accordance with known techniques. 
         [0013]    Techniques for preparing the defect and/or harvesting the graft are disclosed with more specificity in pending U.S. patent application Ser. No. 11/340,024, filed Jan. 26, 2006; No. 11/338,926, filed Jan. 25, 2006; No. 11/339,194, filed Jan. 25, 2006; No. 11/317,985, filed Dec. 23, 2005; No. 11/340,884, filed Jan. 27, 2006; No. 11/343,156, filed Jan. 30, 2006; and No. 11/339,694, filed Jan. 25, 2006, the disclosures of which are hereby incorporated by reference. 
         [0014]    This graft only generally corresponds to the above-mentioned opening in the defect  12   a  in size and shape, and  FIGS. 2B and 3  depict a system that enables the graft to precisely fit in the opening. 
         [0015]    To this end, and with reference to  FIG. 2B , which depicts the femur of  FIG. 2A , a soft material such as putty, or the like, is placed in the opening in the defect  12   a  and allowed to harden to form a mold  20 . Since this type of material is conventional, it will not be described in detail. The hardened mold  20  is then removed from the defect  12   a  and transferred to a copy-mill apparatus shown, in general, by the reference numeral  24  in  FIG. 3 . 
         [0016]    The apparatus  24  consists of an arm  26  anchored at one end portion by a fixed base  28 , and pivotally mounted at its other end to an arm  30 . The arms  26  and  30  extend generally at right angles to each other, and the other end of the arm  30  is fixed to an adjustable mounting ring  32 . An electric drill  34  is secured in the ring  32  and includes a grinding bit  36  that is rotated by the drill. 
         [0017]    The respective ends of two additional arms  40  and  42  are affixed to the arms  26  and  30 , respectively, in any conventional manner. The arms  40  and  42  are shorter than the arms  26  and  30 , and are connected to the arms at an area between the ends of the latter arms. The arms  40  and  42  extend generally perpendicularly to the arms  26  and  30 , respectively, and the other ends of the arms  40  and  42  are pivotally connected to each other. A stylus  44  is mounted at or near the pivot point between the latter ends of the arms  40  and  42 . 
         [0018]    A graft, described above and referred to by the reference numeral  46  in  FIG. 3 , is placed near the bit  36 , and the mold  20  is placed near the stylus  44 . The electric drill  34  is activated and the surgeon manually manipulates the stylus  44  so that it traces the contour of the mold  20 . The articulation of the arms  26  and  30  and the arms  40  and  42  causes the movement of the stylus  44  to be transferred to corresponding movement of the drill  34  and the bit  36 . Thus, the bit  36  grinds, or cuts, the graft  46  in a contour that corresponds to the contour of the mold  20 . 
         [0019]    It is understood that the stylus  44  can trace other contours on other surfaces of the mold  20 , in which case the bit  36  would be oriented relative to the graft  46  so that the same contour is cut in the graft. 
         [0020]    According to an alternate embodiment, instead of using a mold, the surgeon could use a conventional computer tomography scan, or a computer axial tomography scan, to develop a three dimensional model of the defect  12   a . According to these procedures the instrument takes a series of X-Rays along a fixed axis on which the patient is moved. Computer software is then used to reconstruct the plane x-rays into a three dimensional model of the tissues in the body. Computer software could then be used to create a negative three dimensional model of the defect void. 
         [0021]    Alternately, magnetic resonance imaging or laser scanning could be used to develop the three dimensional model. Further, the model could be reproduced using computer controlled instruments for the manufacture of three dimensional products, such as a rapid prototype device, a three dimensional printer or a stereolithograph, for example. These instruments use a variety of materials and methods to generate three dimensional models from computerized data sets. Still further, the model can be formed using a free hand instrument that is bounded in three dimensional space by a robot using the data obtained from the scan of the defect region. 
         [0022]    Since the techniques discussed in the previous two paragraphs are conventional, they will not be described in detail. 
         [0023]    After the model is formed in accordance with one of the above procedures, it could then be placed into the copy mill in the same manner as the mold  20  and could also be used to shape a graft according to the procedure disclosed above. 
         [0024]    A graft formed in accordance with each of the above embodiments can then be implanted in the opening in the defect  12   a  ( FIG. 2A ), with the assurance that it will fit in a precise manner. In the latter context, examples of tools for retaining a graft and implanting it in an opening are well disclosed in U.S. patent application Ser. No. 10/792,780, filed on Mar. 5, 2004 (now U.S. publication no. 2004/0176771, published Sep. 9, 2004); U.S. patent application Ser. No. 10/785,388, filed on Feb. 23, 2004 (now U.S. application publication no. 2004/0193154, published Sep. 30, 2004); U.S. patent application Ser. No. 10/984,497, filed Nov. 9, 2004; (now U.S. application publication no. 2005/0101962, published May 12, 2005); U.S. patent application Ser. No. 10/815,778, filed Apr. 2, 2004 (now U.S. application publication no. 2005/0222687, published Oct. 6, 2005); U.S. patent application Ser. No. 08/885,752, filed Jun. 30, 1997 (now U.S. Pat. No. 5,919,196 granted Jul. 6, 1999); U.S. patent application Ser. No. 08/797,973, filed Feb. 12, 1997 (now U.S. Pat. No. 5,921,987 granted Jul. 13, 1999); U.S. patent application Ser. No. 08/908,685, filed Aug. 7, 1997 (now U.S. Pat. No. 5,964,805, granted Oct. 12, 1999); U.S. patent application Ser. No. 08/774,799 filed Dec. 30, 1996 (now U.S. Pat. No. 6,007,496); U.S. patent application Ser. No. 09/187,283, filed on Nov. 5, 1998 (now U.S. Pat. No. 6,110,209, granted Aug. 29, 2000); U.S. patent application Ser. No. 09/425,337, filed Oct. 22, 1999 (now U.S. Pat. No. 6,306,142, granted Oct. 23, 2001); U.S. patent application Ser. No. 09/559,532, filed Apr. 28, 2000 (now U.S. Pat. No. 6,375,658, granted Apr. 23, 2002); U.S. patent application Ser. No. 09/118,680, filed Jul. 17, 1998 (now U.S. Pat. No. 6,395,011, granted May 28, 2002); U.S. patent application Ser. No. 09/624,689, filed Jul. 24, 2000 (now U.S. Pat. No. 6,440,141, granted Aug. 27, 2002); U.S. patent application Ser. No. 09/571,363, filed May 15, 2000 (now U.S. Pat. No. 6,488,033, granted Dec. 3, 2002); U.S. patent application Ser. No. 09/243,880, filed Feb. 3, 1999 (now U.S. Pat. No. 6,592,588, granted Jul. 15, 2003); U.S. patent application Ser. No. 10/004,388, filed Oct. 23, 2001 (now U.S. Pat. No. 6,767,354, granted Jul. 27, 2004); U.S. patent application Ser. No. 10/084,490, filed Feb. 28, 2002 (now U.S. Pat. No. 6,852,114, granted Feb. 8, 2005); U.S. patent application Ser. No. 10/665,152, filed on Sep. 22, 2003 (now U.S. publication no. 2004/0059425, published Mar. 25, 2004); U.S. patent application Ser. No. 10/638,489, filed on Aug. 12, 2003 (now U.S. publication no. 2004/0034437, published Feb. 19, 2004); U.S. patent application Ser. No. 10/443,893, filed on May 23, 2003 (now U.S. publication no. 2004/0039400, published Feb. 26, 2004); U.S. patent application Ser. No. 10/947,217, filed on Sep. 23, 2004 (now U.S. publication no. 2006/0060209, published Mar. 23, 2006). The disclosures of each of these patent applications and publications are incorporated herein by reference. 
       Variations 
       [0000]    
       
         
           
             (1) The present invention procedure is not limited to preparing a graft for implantation in the knee, but is equally applicable to other parts of the body. 
             (2) More than one opening, of the type described above, can be formed at or near the defect. 
             (3) A mechanism other than the ring  32  can be used to mount the drill  34  to the rod  30 . 
             (4) The graft could take the form of a synthetic or natural material/scaffold used for resurfacing the defect. 
           
         
       
     
         [0029]    Those skilled in the art will readily appreciate that many other variations and modifications of the embodiment described above can be made without materially departing from the novel teachings and advantages of this invention. Accordingly, all such variations and modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.

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