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Intramedullary implant for fracture fixation and method of using the sameRelated Patent Categories: Surgery, Instruments, Orthopedic Instrumentation, Internal Fixation Means, Intramedullary FixatorIntramedullary implant for fracture fixation and method of using the same description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070173835, Intramedullary implant for fracture fixation and method of using the same. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] This invention relates to an intramedullary fracture fixation implant and particularly to a fracture fixation implant for fixation of distal fractures of the radius in which the implant is adopted to be axially inserted and secured within the intramedullary canal portions of the bone segments on opposing sides of the fracture. The invention further comprises a method of fracture fixation with the intramedullary fracture fixation implant of the present invention. BACKGROUND AND PRIOR ART [0002] Fractures that occur in proximity to a joint can be difficult to treat. Although plates, screws and pins on the surface of the bone can provide fracture stability, often the close proximity of tendons to the surface of the bone can result in soft tissue irritation and even tendon rupture that can compromise the outcome. Intramedullary fixation of fractures, with or without cross-locking screws, is well known to reduce the problem of soft tissue irritation by placing the bulk of the implant within the bone itself. [0003] Furthermore, intramedullary fixation can provide fracture stability because of either a tight fit of the rod within the bone or fixation from locking screws that cross through the bone and rod. Traditional intramedullary rods, however, are not well suited for fixation of a fracture in proximity to the end of the bone. For example, in the case of fractures of the distal radius, the distal end of the radius is extremely wide with soft cancellous bone within the intraosseous space and only thin weak cortical bone that surrounds the tubular structure; the strongest bone at the distal end of the radius is the thick subchondral bone that extends behind the articular surface and is under the tip of the radial styloid. In the case of fractures of the distal radius, insertion of the implant is not possible through the tubular proximal fragment because of its deep location and the narrow, cylindral nature of the morphology that makes it impossible to direct an intramedullary implant down the center of the bone. Because of this, intramedullary fixation of distal radius fractures has always inserted the device directly through the soft radial surface of the radial styloid in order to direct the implant within the intramedullary canal. This necessarily results in creation of a large additional hole that is at least the diameter of the implant in the small distal fragment, which can easily result in creation of additional fragmentation, collapse of the fragment and resultant loss of fixation. [0004] In addition, since the implant is inserted through this large defect in the distal fragment, it is not possible for the end of the implant to be used to provide axial support to the fragment; instead, the implant is totally dependent on the resistance of the thin cortical bone to translational movement and the purchase of transverse locking screws in the soft, often osteoporotic, metaphyseal bone. As a result, loss of radial length can easily occur, resulting in protrusion of the nail from the insertion site as well as deformity and loss of function. Finally, because the end of the bone is often covered with articular cartilage which is damaged if a nail is inserted through it, standard intramedullary implants are unable to provide support to the end of the bone as they must be placed more proximal to this area to prevent damage to the joint. [0005] Standard intramedullary rods use cross locking screws to prevent the small distal fragment from losing length. Examples of standard intramedullary rods are shown in U.S. patent application Ser. No. 10/377,255 to Warburton and entitled Intramedullary Interlocking Fixation Device for the Distal Radius (U.S. Publication No. 2004/0010255) and U.S. patent application Ser. No. 09/975,514 to Putnam and entitled Intramedullary Rod for Wrist Fixation (U.S. Publication No. 2003/0073999). Because these screws are placed across the nail into the metaphyseal bone of the distal fragment, they are loaded at their tip by the compressive loads that occur across the wrist. This places a significant torque on the screw, which can lead to increased implant loads and can result in breakage, cutout through the bone, or loosening of the screw. In turn these can result in loss of length, deformity, and impaired function of the wrist. [0006] Since the distal radius is made of relatively soft cancellous bone, there is little resistance to side-to-side translational displacements by a standard intramedually nail, particularly since the nail is placed through a hole made in the bone and courses to lie entirely within the metaphyseal cavity. This results in poor support of the fragment by the nail itself, requiring the majority of resistance to displacement to be taken up by the distal crossing screws. [0007] In copending U.S. patent application Ser. No. 10/675,864 to Medoff and entitled Intramedullary Implant for Fracture Fixation (U.S. Publication No. 2005/0070902), an approach was described that provides axial support of the radial styloid by the tip of an implant that is placed intramedullary into the distal fragment. Since the implant lies on the extraosseous surface proximally, the implant enters the fracture site and can be placed with a single longitudinal insertion into the distal fragment. However, this design requires a more extensive dissection for placement of the extramedullary portion of the implant in addition to resulting in an implant that is still fixed on the surface of the bone over one part, with the possibility of further soft tissue irritation. In addition, since the surface portion of the implant must be thin to avoid prominence and soft tissue irritation, this creates a stress riser at the junction of the extramedullary and intramedullary portions of the implant that can result in breakage. [0008] Current intramedullary implants are inserted into a tubular bone from one end and driven to the opposite end. In some applications, the implant is inserted at the proximal end of the bone and driven in an ante grade direction into the distal end of the long bone. In other applications, the implant is inserted at the distal end of a long bone and driven in a retrograde direction into the proximal end. Because the direction of insertion is always uni-directional, current intramedullary designs do not permit fixation both above and below the site of insertion of the implant. In addition, since existing intramedullary implants are designed for insertion in a single direction only (either ante grade or retrograde), these implants are always connected to a driver at one end. SUMMARY OF THE INVENTION [0009] An object of the current invention is to provide an intramedullary implant that can be inserted without the creation of a new, large defect in either fragment, but particularly the small distal fragment, thereby avoiding the risk of additional fracture comminution caused from the insertion procedure itself. [0010] A further object of the invention is to provide an intramedullary implant that can be inserted without the necessity of driving the implant along a single axis into the bone from one end, thereby avoiding the problem of positioning the insertion hole in the bone directly over the end of the implant and resulting in the inability of the implant to support the distal fragment axially and poor resistance to shortening. [0011] A further object of the invention is to provide an intramedullary implant that resists loss of length by providing axial support along its tip to the strong subcortical bone at the end of a fragment. [0012] A further object of the invention is to provide an intramedullary implant that can both resist loss of length through axial support of an unstable bone fragment as well as achieve rotational support from cross locking screws in the unstable fragment. [0013] A further object of the invention is to allow a provision for a relatively smooth tip to be situated centrally within the conical morphology of the tip of the radial styloid, abutting the strong subchondral surface at the end of the bone. In addition to the load support by the tip, the tip is captured by the concave conical bone at the radial styloid, thereby resisting translational movement of the distal fragment by the nail itself. This is comparable to the way a tent is supported by a tent pole. [0014] A further object of the invention is to provide a method of fixation that is simple to apply, allows insertion of an intramedullary implant to span a fracture defect by insertion of the implant through the fracture site itself, with a minimal incision or even subcutaneous approach. [0015] A further object of the invention is to provide instrumentation that allows an intramedullary implant to be inserted through a fracture defect into an intramedullary position, spanning the fracture defect and achieve purchase in the fragments on both sides of a fracture. [0016] A further object of the invention is to provide a means of insertion that allows an intramedullary implant to be inserted in one direction through a relatively central insertion site in the bone, and then displaced in the opposite direction to allow bone purchase on both sides of the insertion site. [0017] A further object of the present invention is to provide instrumentation that cooperates with areas of connection on an intramedullary implant in order to allow the implant to be axially displaced in a direction that is opposite of the initial insertion of the implant into the bone. BRIEF DESCRIPTION OF THE DRAWINGS [0018] FIG. 1 is a schematic view of a step in a method for fixing a bone fracture using the intramedullary fixation device of the present invention; [0019] FIG. 2 is a front elevation view of the intramedullary fixation device according to the present invention; [0020] FIG. 3 is a side elevation view of the intramedullary fixation device according to the present invention; Continue reading about Intramedullary implant for fracture fixation and method of using the same... Full patent description for Intramedullary implant for fracture fixation and method of using the same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Intramedullary implant for fracture fixation and method of using the same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Intramedullary implant for fracture fixation and method of using the same or other areas of interest. ### Previous Patent Application: Flexible nail assembly for fractures of long bones Next Patent Application: Bone fixation and dynamization devices and methods Industry Class: Surgery ### FreshPatents.com Support Thank you for viewing the Intramedullary implant for fracture fixation and method of using the same patent info. IP-related news and info Results in 0.11102 seconds Other interesting Feshpatents.com categories: Novartis , Pfizer , Philips , Polaroid , Procter & Gamble , 174 |
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