Abstract:
A cutting implement includes a first tubular portion and a second tubular portion. Each tubular portion is hollow and includes a blade element at a distal end. The blade element helps define an aperture that allows access to the interior hollow portion of the tubular portion. A ligament graft element is threaded through the aperture of each tubular portion and the respective tubular portions are interoperated to cut the ligament graft.

Description:
FIELD OF THE DISCLOSURE 
     The present disclosure relates to a cutting instrument adapted to help a surgeon harvest a replacement tendon for an anterior cruciate ligament (ACL) injury from the quadriceps tendon. 
     BACKGROUND 
     Most people can go through the majority of their life without ever appreciating the complicated structure of the knee that helps them walk. However, the knee remains a fragile mechanical structure that is readily susceptible to damage. While medical advances have made repairing the knee possible, repair of certain types of injuries results in other long term effects. To assist the reader,  FIG. 1  is provided with a brief explanation of the components of the knee. 
     For the purposes of the present disclosure, and as illustrated, the knee may be composed of the quadriceps muscles  10 , the femur  12 , the articular cartilage  14 , the lateral condyle  16 , the posterior cruciate ligament  18 , the anterior cruciate ligament  20 , the lateral collateral ligament  22 , the fibula  24 , the tibia  26 , the patellar tendon  28 , the meniscus  30 , the medial collateral ligament  32 , the patella  34  (shown slightly displaced to the side—it normally rests in the center of the knee) and the quadriceps tendon  36 . Of particular interest for the purposes of the present disclosure is the anterior cruciate ligament (ACL)  20  and what is done to repair the ACL  20 . 
     ACL tears are common in athletes and are usually season ending injuries. The ACL  20  cannot heal—it must be surgically reconstructed. The reconstruction requires replacement tissue. The most common tissue used is a central slip of the patient&#39;s own patellar tendon  28 . In practice, the patellar tendon  28  has proven to be generally effective, but the size of the graft that can be used is limited to the size of the patient&#39;s own patellar tendon  28 . As a rule of thumb, only a third of the patellar tendon  28  may be harvested as a graft. Thus, a doctor will measure the width of the patellar tendon  28 , divide by three, and take the middle third of the patellar tendon  28 . Such harvested grafts are rarely more than 10 mm wide and may be smaller. Taking this tissue from a person&#39;s patellar tendon  28  also causes significant pain and discomfort in the post operative healing period, which may last up to a year, and up to twenty (20) percent of these patients are left with chronic anterior knee pain. 
     Some doctors recommend and use other graft sources, such as cadaver grafts, but cadaver grafts have a higher failure rate. Additionally, there is a non-zero chance of disease transmission or rejection by the patient&#39;s immune system. As a final drawback, cadaver grafts are usually quite expensive and may not be covered by some insurance companies. 
     Other doctors use hamstring tendons (e.g., the distal semitendinosus tendon) because the scar created during harvesting is relatively small and there is less pain during the rehabilitation, but again, the hamstring tendon has its own collection of disadvantages. The disadvantages include the fact that once the graft is taken, a patient&#39;s hamstring will never recover to its previous strength. Further, all hamstring reconstructions stretch and are looser than the original ACL  20 . This loosening is particularly problematic in younger female athletes. 
     Another alternative graft source is the quadriceps tendon  36 . The quadriceps tendon  36  is larger and stronger than either the patellar tendon  28  or the hamstring tendon. The quadriceps tendon  36  is likewise stiffer and less prone to stretching or plastic deformation. However, the qualities that make the quadriceps tendon  36  attractive also contribute to the difficulty in harvesting a graft from the quadriceps tendon  36 . Existing surgical implements require a large incision up the longitudinal axis of the femur  12  on the front or ventral/anterior side of the thigh to cut down to the level of the quadriceps tendon  36 , resulting in a large post operative scar. Additionally, the quadriceps tendon  36  has a consistency similar to the proverbial shoe leather, making it difficult to cut. However, an ACL  20  repaired with grafts from the quadriceps tendon  36  generally results in almost no anterior knee pain postoperatively over the short or long term and recovers quicker. 
     The present inventor&#39;s prior application, U.S. patent application Ser. No. 13/102,562, filed May 6, 2011 (which is hereby incorporated by reference in its entirety), provides a number of devices designed to create a graft from the quadriceps tendon  36  and discloses an element to make the initial cut on the quadriceps tendon  36  as well as a number of secondary cutting implements to trim the distal end of the graft. While these secondary cutting implements are adequate to perform their intended purpose, alternate devices may be more cost effective or have easier engineering realities. 
     SUMMARY 
     The present disclosure provides a secondary cutting implement that is adapted to trim a distal end of a preliminarily harvested graft from the quadriceps tendon in a minimally invasive manner. Once the quadriceps tendon graft is secured, it may be used in conventional manners to repair the anterior cruciate ligament (ACL). 
     The secondary cutting implement comprises a first hollow tubular element and a second hollow tubular element that telescopingly fits within the first tubular element. The distal ends of each tubular element include an interior blade element positioned perpendicular to a longitudinal axis of the tubular element. The interior blade elements are sized such that the distal end of each tubular portion is at least partially open. That is, the blade elements help define an aperture at the distal end of the tubular hollow elements. 
     In use, the quadriceps tendon is cut to a desired length and then the graft portion is threaded through the open distal end of the first tubular element. The graft portion is also threaded through the open distal end of the second tubular element. The tubular elements are rotated in opposite directions causing the interior blade elements to trim the distal end of the graft. 
     Those skilled in the art will appreciate the scope of the disclosure and realize additional aspects thereof after reading the following detailed description in association with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure. 
         FIG. 1  illustrates a conventional knee; 
         FIG. 2  illustrates an exploded perspective view of an exemplary embodiment of the secondary cutting implement of the present disclosure; 
         FIGS. 3A-3F  illustrate schematically operation of the secondary cutting element; and 
         FIG. 4  illustrates a flow chart describing the operation of the secondary cutting element. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the disclosure and illustrate the best mode of practicing the disclosure. Upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims. 
       FIG. 2  illustrates a first exemplary embodiment of a secondary cutting implement  50  according to the present disclosure. The secondary cutting implement  50  is useful for trimming a graft being harvested from the quadriceps tendon  36 , such as occurs when the cutting implement of the previously incorporated &#39;562 application is used to cut a graft from the quadriceps tendon  36 . The secondary cutting implement  50  has a first element  52 , which is hollow and has a first handle end  55  and a first distal end  56 . The first distal end  56  includes a first blade element  58 . The first blade element  58  is positioned perpendicular to a longitudinal axis  60  of the first element  52 . The first blade element  58  may be integrally formed with the body of the first element  52  or fixedly secured thereto. In an exemplary embodiment, the first element  52  is adapted to be reusable while the first blade element  58  is removably affixed thereto such that it can be replaced readily. Thus, the first blade element  58  may be considered disposable or reusable as desired. The first blade element  58  extends, in an exemplary embodiment, approximately halfway across distal end  56  (e.g., covering approximately 45-55% (and in an exemplary embodiment approximately 51%) of the area of the distal end  56 ) and partially defines a first aperture  62  through which a graft may be threaded as explained in greater detail below. In an exemplary embodiment, the first element  52  is made from a metal such as surgical stainless steel (e.g., made out of chromium, nickel, molybdenum, and/or titanium) such as 316L, 316LVM and/or compliant with ASTM F138. In an alternate embodiment, the first element  52  is made from a polymer based material. The first blade element  58  may be made from surgical steel, glass, obsidian, diamond, or the like as desired. In an exemplary embodiment, the first element  52  may be approximately 100 mm long. 
     The second element  54 , which is hollow and has a second handle end  64  and a second distal end  66 . The second distal end  66  includes a second blade element  68 . The second blade element  68  is positioned perpendicular to a longitudinal axis  70  of the second element  54 . The second blade element  68  may be integrally formed with the body of the second element  54  or fixedly secured thereto. In an exemplary embodiment, the second element  54  is adapted to be reusable while the second blade element  68  is removably affixed thereto such that it can be replaced readily. Thus, the second blade element  68  may be considered disposable or reusable as desired. The second blade element  68  extends, in an exemplary embodiment, approximately halfway across second distal end  66  (e.g., covering approximately 45-55% (and in an exemplary embodiment approximately 51%) of the area of the distal end  66 ) and at least partially defines a second aperture  72  through which a graft may be threaded as explained in greater detail below. In an exemplary embodiment, the second element  54  is made from a metal such as surgical stainless steel (e.g., made out of chromium, nickel, molybdenum, and/or titanium) such as 316L, 316LVM and/or compliant with ASTM F138. In an alternate embodiment, the second element  54  is made from a polymer based material. The second blade element  68  may be made from surgical steel, glass, obsidian, diamond, or the like as desired. In an exemplary embodiment, the second element  54  may be approximately 120 mm long and 23 mm in interior diameter. The first element  52  may be sized such that its interior diameter is just large enough to fit around the exterior diameter of second element  54 . 
     By design, the first element  52  is shorter than the second element  54 , and the second element  54  telescopingly fits within the first element  52  such that the second handle end  64  extends out past the first handle end  55  so as to facilitate manipulation of the second element  54  within the first element  52 . 
     In an exemplary embodiment, the handle ends  55  and  64  may be abraded, knurled, or otherwise textured to provide a firm gripping surface. In an alternate embodiment, there may be an explicit handle attached to or formed on the handle ends  55  and  64  to make manipulation and grip more natural. 
       FIGS. 3A-3F  illustrate a technique of using the secondary cutting implement  50  as further explained in the flowchart of  FIG. 4 . The process  100  of harvesting the graft  80  begins with the incision being made (block  102 ) and the tendon being cut to form the graft  80  (block  104 ). As explained in the previously incorporated &#39;562 application, the graft  80  may be created from the quadriceps tendon  36 . 
     Once the graft  80  is cut from the quadriceps tendon  36 , the cutting implement is removed and the first element  52  is threaded through the first aperture  62  (block  106 ), through the hollow portion of the first element  52  and out the first handle end  55 . Thus, the interior dimensions of the hollow portion of the first element  52  should be sized so as to accommodate the graft  80  and the bit of patella  82 . Likewise, the size of the first aperture  62  should be sufficient to pass both the graft  80  and the bit of patella  82 . 
     Note that as used herein “threaded through” or similar phrases draws analogy to threading a needle, and does not refer to the threads on a screw. 
     The graft  80  may then be threaded through the second aperture  72  and the second element  54  (block  108  and  FIG. 3C ). Note that if the apertures  62  and  72  are aligned and the second element  54  is already positioned within the first element  52 , the graft  80  may be threaded through the first and second elements concurrently. As is seen in  FIG. 3C , the second handle end  64  extends past the first handle end  55 . Likewise, at least initially, the apertures  62  and  72  are aligned to allow the graft  80  to pass therethrough. 
     The second element  54  is then rotated relative to the first element  52  (block  110 ,  FIGS. 3D &amp; 3E ). As the two elements  52  and  54  are rotated relative to one another, the blade elements  58  and  68  rotate to one another and effectively close the aperture through which the graft  80  has been passed. This allows the blade elements  58  and  68  to scissor together, thereby cutting the graft  80 . Once the rotation has been effectuated sufficiently, the graft  80  is severed (block  112 ). 
     The graft  80  is then removed (block  114 ) as well as the cutting implement  50  (block  116 ,  FIG. 3F ). Then the graft  80  may be used to repair the ACL as desired. 
     Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.