Abstract:
An intramedullary nail comprising an outer tubular sheath, a flexible rod and a driver element mobile within the sheath longitudinally with an engagement element formed out of the wall of the tubular sheath. After the nail has been inserted, distal end first, into the intramedullary cavity, the flexible rod is pulled, thereby engendering the driver element to advance the engagement element into the cortical bone, thus keeping the intramedullary nail in position within the intramedullary cavity.

Description:
RELATIONSHIP TO PRIOR APPLICATION 
       [0001]    This application is based upon and claims priority from the U.S. Provisional Patent Application number 61311873 filed Mar. 9, 2010 which is incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to an intermedullary device for the stabilization of osseous matter for the purpose of improved healing and mobility during healing. 
       BACKGROUND 
       [0003]    Typically, an intramedullary nail is placed into the intramedullary cavity of physically compromised osseous material in order to maintain proper alignment of the material for optimal healing. The intramedullary nail is then secured by screws to allow support of the bone so that the patient can use the appendage during healing. Previous intramedullary nails had holes on both the distal and proximal ends for the insertion of fixtures, such as screws, that go through the intramedullary hardware and compromised osseous material. The holes that are closest to the point of nail insertion are called the “proximal” holes and those furthest away are the “distal” holes. The most commonly used system for securing an intramedullary nail uses an external guide or jig to find the proximal holes in the nail. With the assistance of the external guide or jig, the surgeon then drills through all of the tissue surrounding the bone and into the bone. For minimal damage and maximal healing, the fixture holes that are drilled into the leg and the bone must precisely align with the insertion holes in the intramedullary hardware so that the hardware can be secured with respect to the medullary canal. 
         [0004]    Various types of external guides and jigs have been proposed to assist in the insertion of intramedullary hardware, such as shown in U.S. Pat. No. 4,733,654 A1 to Marino and U.S. Pat. No. 5,776,194 A1 to Mikol et al. Such external guides and jigs may be temporarily attached to the proximal end of the intramedullary nail to help align the bone fixtures and/or the drill to the receiving opening in the intramedullary nail. While such external guides and jigs are helpful to achieve proper alignment, their accuracy decreases they proceed from the proximal end to the distal end of the intramedullary nail. Additional solutions are needed, especially for attaching the distal end of the intramedullary nail to a distal osseous material fragment. 
         [0005]    There are currently no effective external systems for finding the distal holes of an intramedullary nail. As mentioned above, guides for the distal hole become less reliable as distance from the proximal end of the intramedullary nail increases, particularly if any bending of the intramedullary nail has occurred. A commonly used procedure involves repeated x-raying of the patient to find the hole and then drilling through the leg into the bone. Another method for securing the distal end of the intramedullary nail is to drill the receiving opening into the intramedullary nail only after the intramedullary nail is placed into the bone, as disclosed in U.S. Pat. No. 5,057,110 A1 to Kranz et al. Bioresorbable materials, however, are not as strong as metals, leading to an intramedullary nail that is weaker than desired and has a weaker attachment than desired. 
         [0006]    Continuing, additional problems occur with intramedullary nails using bioresorbable materials due to the healing requirements of a bone with respect to the strength and rigidity of the intramedullary nail. U.S. Pat. No. 4,756,307 A1 to Crowninshield and U.S. Pat. No. 4,338,926 A1 to Kummer et al. disclose an intramedullary nail with bioresorbable portions to weaken the nail relative to the bone over time. These intramedullary nails, however, forsake the use of a transverse bone fastener to achieve the benefit of the bioresorbable portions. 
         [0007]    Finally, while most intramedullary nails remain in the patient&#39;s leg throughout their lifetime, the nail does occasionally need to be removed due to complications. The complications usually arise from the presence of the screws holding the nail in place. When the removal of the nail is necessary the physician must repeat the insertion procedure to find the location of the screws and drill into the leg again. 
         [0008]    It would thus be advantageous to provide an intramedullary nail and related portions and/or components that overcomes the above-noted shortcomings. 
       SUMMARY OF THE INVENTION 
       [0009]    The proposed invention solves the difficulty of the labor and time intensive process of securing an intramedullary nail within the intramedullary cavity of a bone by external screwing and drilling. The proposed invention engenders an anchoring mechanism located within the intramedullary nail to engage the cortical bone. In this way, the labor and time requirements related to securing an intramedullary nail within the intramedullary cavity are substantially reduced. Additionally, the invention achieves the advantage of reduced radiological exposure to patients and medical personnel, and reduced scarring for the patient. Use of the proposed invention is not limited to fractures of the length of the long bone, but could also be used in fractures of the ball from the rest of the long bone or for smaller bones. 
         [0010]    Exemplary embodiments are provided, these embodiments are not to be interpreted as limitations upon the invention. In one embodiment, the bone-securing device comprises a intramedullary nail, open on both ends, having at least one or more engaging elements. The intramedullary nail may be inserted into the intramedullary cavity of a bone such that the intramedullary nail is secured within the intramedullary cavity on one or both sides of a fracture, thereby aligning the fractured bone fragments, thus allowing the promotion of healing and the formation of a new center portion from and between the splintered parts. 
         [0011]    The invention also relates more particularly to engaging elements that are attached to the wall of intramedullary nail. The engaging elements may be attached to the intramedullary nail by, but not limited to, being cut from the material of the wall of the intramedullary nail. Attachment of the engaging elements to the nail itself allows for greater stability than prior internal anchoring devices. After the intramedullary nail is placed into the intramedullary cavity of the bone, the engaging elements are engendered to engage the surrounding cortical bone tissue. The engaging elements are preferably located at the distal end of the intramedullary nail&#39;s insertion point, but there may be a plurality of engaging elements along the length of the intramedullary nail, including at the proximal end. In some embodiments, the end of the intramedullary nail proximal to its insertion point will have openings located on its walls instead of engaging elements. These openings on the proximal end would allow for the insertion of external screws. The intramedullary nail would be compatible with an external guide to allow for the discovery of any screw holes from outside the bone. 
         [0012]    In this invention, the engaging elements are attached to the wall of the intramedullary nail. In the preferred embodiment, the engaging elements are cut directly from the wall of the intramedullary nail so that they are integral to the intramedullary nail. In some embodiments, the materials of the intramedullary nail and that of the engaging elements are different. This may be achieved, for example, at the casting by combining the materials when the intramedullary nail is cast or they may be combined after casting, for example using a dovetail design. In the preferred embodiment, the engaging elements are curved and the tips are self-tapping to facilitate engagement with bone tissue. 
         [0013]    The engaging elements are pushed outward by a mechanism internal to the intramedullary nail. This internal mechanism comprises a threaded flexible rod and a driver that fits within the hollow section of the intramedullary nail. The driver is located on the flexible rod and can either move along the length of the flexible rod or is secured to the flexible rod. This driver shifts position to engender the movement of the engaging elements. 
         [0014]    In one embodiment, the internal, hollow portion of the intramedullary nail is threaded to allow for a controlled movement of the flexible rod. In this embodiment, the driver is bound to the flexible rod such that it moves upwards as the flexible rod screws upwards along the threaded portion of the intramedullary nail. The driver moves with the flexible rod longitudinally along the length of the intramedullary nail and pushes out the engaging elements as it passes through the center of the intramedullary nail. 
         [0015]    In another embodiment, the internal flexible rod rotates in the intramedullary nail without moving longitudinally. In this embodiment, the driver is not secured in place on the rotating flexible rod, but may move along the surface of the flexible rod as the flexible rod turns. In this embodiment, the rotating flexible rod drives the driver into the space between or amongst the engaging elements. In turn, the driver pushes the engaging elements outward relative to the outer surface of the intramedullary nail. In either embodiment, the driver may remain in place between or amongst the engaging elements allowing for improved engagement properties of the engaging elements. 
         [0016]    In another embodiment, the driver is bound to the flexible rod such that it turns with the flexible rod and is already amongst the engaging elements. The driver is shaped such that it initially allows the engaging elements to remain unengaged. Turning the flexible rod a single or partial turn engenders the driver to exert pressure on the engaging elements so that they engage the bone. 
         [0017]    In the preferred embodiment of the invention, the distal end of the intramedullary nail is open and internally constructed to catch bone marrow as the intramedullary nail is driven into the intramedullary cavity of the bone. This internal construction involves a narrowing and curving of the inner portion of distal end such that a concave face is proffered toward any marrow entering the hollow portion of the tube. This catching of the marrow prevents the marrow from clogging any internal structures of the intramedullary nail. 
         [0018]    In the preferred embodiment of the intramedullary nail, the intramedullary nail, the engaging elements, the flexible rod and driver(s) are independently composed of titanium alloy, cobalt chromium, stainless steel or other compounds having similar structural properties. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a front and side view of possible construction of the intramedullary nail with close up of the mechanism of the preferred embodiment 
           [0020]      FIG. 2  is a view of a possible construction of the intramedullary nail with a handheld power device inserted and the anchors extended 
           [0021]      FIG. 3  is the internal structure of the intramedullary nail before the driver engages the anchors 
           [0022]      FIG. 4  the internal structure of the intramedullary nail after the driver has engaged the anchors 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    The intramedullary nail may be placed into a long bone by cutting the outer tissue, drilling into the bone and reaming out the intramedullary space to facilitate the insertion of the intramedullary nail. A guide wire may be sent into the intramedullary space, the intramedullary nail inserted onto the guide wire, and then the intramedullary nail hammered securely into the intramedullary space so that it traverses a broken or weak point in the bone. 
         [0024]    Referring to the  FIG. 1 , the intramedullary nail  100  may be bent or straight to match the structure of the intended bone.  FIG. 1B  is a side view of nail  100  in  FIG. 1A . The nail  100  has a proximal end  102  closer to the point of insertion and a distal end  104  further from the point of insertion. The proximal end  102  may have holes  106  for the insertion of external screws (not shown) as demonstrated by  FIG. 1C . The hole  106  may be circular or they may be compression holes  106 .  FIG. 1D  shows an example of the distal end  104  wherein anchors  108  are attached to the nail. The anchors  108  may be curved as shown in  FIG. 1D . The anchors  108  are able to shift position so that the tips of the anchor extend out of the nail  100  and may engage external material.  FIG. 1E  shows a top view cross section of the distal end  104  with the anchors  108  partially extended out of the nail  100 . In the preferred embodiment, the anchors  108  are positioned fully within the nail  100  until an operator wishes to secure the distal end of the nail  100  within intramedullary space. As shown in  FIG. 1D , the distal end  104  of the nail  100  may be open to allow a guide wire (not shown) to pass through the entire length of the nail  100 . 
         [0025]    The anchors  108  are able to shift position so that their tips extend out of the nail  100  and engage the surrounding cortical bone. The anchors  108  in  FIG. 1D  have tips that are curved toward the distal end  104 , but the anchors  108  may also be attached to the nail  100  on the end of the anchor closer to the proximal end  102  of the nail  100  and the tip of the anchor  108  may be closer to the distal end  104  with the anchor  108  tip pointing toward the proximal end  102 . The anchors  108  may also be perpendicular to the nail  100  so that they would appear sideways to the position of the anchors  108  shown in  FIG. 1D . The anchors  108  can take a variety of shapes. 
         [0026]      FIG. 1F  shows an example of a flexible rod  110  with a driver  112  attached. The driver  112  may be attached to the flexible rod  110  in a variety of ways. For example, the driver  112  may be secured to the flexible rod  110  so that they move in unison. In another example, the flexible rod  110  may be externally threaded and the driver  112  internally threaded such that the driver  112  can screw along the flexible rod  110 , thereby changing its position on the flexible rod  110 . Other configurations are easily produced by a person of ordinary skill in the art. The flexible rod  110  may extend completely through the driver  112  or the driver  112  may be positioned at the terminus of the flexible rod  110 . In the preferred embodiment, the flexible rod  110  is hollow to allow for the insertion of the guide wire. The driver  112  has a body  114  and a conical top  116 . The driver body  114  is structured to fit within the inside of the nail  100 , so that the driver  112  can move longitudinally through the nail  100 . 
         [0027]    As demonstrated by  FIG. 2 , in the inventive concept, the flexible rod  110  with the attached driver  112  is positioned within the nail  100  with the conical top  116  portion closer to the anchors  108  than the driver&#39;s body  114 . The driver  112  may be positioned between the anchors  108  and the proximal end  102  or the distal end  104 . In the example shown in  FIG. 3 , the driver  112  is at the terminus of the flexible rod  110  between the anchors  108  and the distal end  104 . As shown in  FIG. 3 , the anchors  108  are attached to the nail wall  200  and still within the nail  100  with the nail  100  pressed tightly against the intramedullary cavity wall  202 . In the inventive concept, the driver  112  moves between or amongst the anchors  108  and engendered them outward to engage the bone  202 . In the example shown in  FIG. 2 , a handheld power device  204 , such as a riveting tool or similar device, may be used to pull the flexible rod  110  a particular distance toward the proximal end  102 . As shown in  FIG. 3 , such an action will cause the driver  112  to move between or amongst the anchors  108  and push out the anchors  108  so that they engage the intramedullary cavity wall  202 . As reflected in  FIG. 2 , so that the nail  100  is not dislodged by the force of the handheld power device  204 , the nail  100  may have a brace  206  at the top to secure the handheld power device  204  in relation to the nail  100 . The handheld power device  204  may also apply torque if the flexible rod  110  and driver  112  of  FIG. 3  are externally and internally threaded, respectively. As displayed in  FIG. 2 , if the handheld power device  204  applies torque, then the brace  206  would prevent the nail  100  and the handheld power device  204  from moving respective to one another. 
         [0028]    The anchors  108  may be attached to the nail wall  200  by a living hinge. The anchor  108  may also have a space  208  for the attachment of a pin (not shown) that is secured to the nail wall  200  as shown in  FIG. 3 . The anchors  108  may also be attached to the nail wall  200  by a wire ring  210  that is in communication with the nail wall  200  as shown in  FIG. 4 . 
         [0029]    After the driver  112  has been moved a particular distance by the force applied by the handheld power device  204 , the driver  112  remains between or amongst the anchors  108  to secure them in place. This creates a solid line of material through the width of the nail  100  and prevents the anchors  108  from falling back inside the nail  100 . 
         [0030]    Once the driver is in place, it can be held in place by pressure from the anchors ( 108 ) that are wedged between the driver and the intramedullary cavity wall ( 202 ). The flexible rod ( 110 ) and driver ( 112 ) may also be kept from moving through a locking mechanism. Such a locking mechanism may include a screw that goes through the flexible rod ( 110 ) or a clamp that holds the flexible rod ( 110 ) in place. 
         [0031]    If the nail  100  needs to be removed, the handheld power device  204  is again applied and the driver  112  moves further along the length of the nail  100 . The driver  112  then pushes on the internal ends of the anchors  108  and pushes them back against the inside nail wall  200 . This pulls the tip of the anchor  108  out of the bone  202  so that the nail  100  may be removed. 
         [0032]    The nail  100  may be manufactured by separately producing the proximal end  102  and the distal end  104  and joining the two ends together. In one manufacturing method, slots may be cut from the tubular sheath using a mill. The driver  112 , secured to the flexible rod  110 , may be inserted and positioned in the nail  100 . Then anchors  108 , which may also be made using a mill, are inserted into the slots in the nail  100 . These anchors  108  may be secured by pins (not shown) that go through spaces  208  in the anchors  108  or by a ring  210 . If a ring  210  is used, the ring  210  may be flexible enough to allow for bending while inserting into the nail  100 , but resilient enough that it regains its shape when in position in the nail  100 . 
         [0033]    In an alternative manufacturing process, the nail  100  may be produced by methods currently known in the art, for example casting. Before cooling, the flexible rod  110  and driver  112  are inserted into the hollow portion of the nail  100 . Also, before cooling, the nail  100  is laser etched with tabs outlining the desired structure of the anchors  108 . Then the profile of the anchors  108  is stamped into the tabs using a mandrel. This may create a living hinge for the anchors  108 . A mandrel may also be used to stamp a rib into the wall of the nail  100 . This rib would allow for the placement of a flexible ring  210  if the anchors  108  are held in place by a ring  210 . Lastly, one may manufacture the nail  100  by fabricating the dynamic portion of the nail containing the anchors  208  separately then subsequently enjoining the dynamic portion with the remainder of the nail. For example, such enjoining may be accomplished by welding, threading an end of the dynamic portion and the remainder of the nail and screwing them together thereby engendering a connection of the two portions, or other such means providing comparable structural integrity.