Patent Publication Number: US-7914533-B2

Title: Minimally invasive actuable bone fixation devices

Description:
CROSS-REFERENCE 
     This application is a continuation application of Ser. No. 11/383,269, filed May 15, 2006 by Nelson entitled Minimally Invasive Actuable Bone Fixation Devices, to which application priority under 35 USC §120 is claimed, and which claims the benefit of U.S. Provisional Application No. 60/682,652, filed May 18, 2005 entitled Method and System for Providing Reinforcement of Bones, each of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to method and system for providing reinforcement of bones. More specifically, the present invention relates to method and system for providing reconstructive surgical procedures and devices for reconstruction and reinforcement bones, including diseased, osteoporotic and fractured bones. 
     Bone fractures are a common medical condition both in the young and old segments of the population. However, with an increasingly aging population, osteoporosis has become more of a significant medical concern in part due to the risk of osteoporotic fractures. Osteoporosis and osteoarthritis are among the most common conditions to affect the musculoskeletal system, as well as frequent causes of locomotor pain and disability. Osteoporosis can occur in both human and animal subjects (e.g. horses). Osteoporosis (OP) and osteoarthritis (OA) occur in a substantial portion of the human population over the age of fifty. The National Osteoporosis Foundation estimates that as many as 44 million Americans are affected by osteoporosis and low bone mass, leading to fractures in more than 300,000 people over the age of 65. In 1997 the estimated cost for osteoporosis related fractures was $13 billion. That figure increased to $17 billion in 2002 and is projected to increase to $210-240 billion by 2040. Currently it is expected that one in two women, and one in four men, over the age of 50 will suffer an osteoporosis-related fracture. Osteoporosis is the most important underlying cause of fracture in the elderly. 
     One current treatment of bone fractures includes surgically resetting the fractured bone. After the surgical procedure, the fractured area of the body (i.e., where the fractured bone is located) is often placed in an external cast for an extended period of time to ensure that the fractured bone heals properly. This can take several months for the bone to heal and for the patient to remove the cast before resuming normal activities. 
     In some instances, an intramedullary (IM) rod or nail is used to align and stabilize the fracture. In that instance, a metal rod is placed inside a canal of a bone and fixed in place, typically at both ends. See, for example, Fixion™ IM (Nail), www.disc-o-tech.com. This approach requires incision, access to the canal, and placement of the IM nail. The nail can be subsequently removed or left in place. A conventional IM nail procedure requires a similar, but possibly larger, opening to the space, a long metallic nail being placed across the fracture, and either subsequent removal, and or when the nail is not removed, a long term implant of the IM nail. The outer diameter of the IM nail must be selected for the minimum inside diameter of the space. Therefore, portions of the IM nail may not be in contact with the canal. Further, micro-motion between the bone and the IM nail may cause pain or necrosis of the bone. In still other cases, infection can occur. The IM nail may be removed after the fracture has healed. This requires a subsequent surgery with all of the complications and risks of a later intrusive procedure. 
     External fixation is another technique employed to repair fractures. In this approach, a rod may traverse the fracture site outside of the epidermis. The rod is attached to the bone with trans-dermal screws. If external fixation is used, the patient will have multiple incisions, screws, and trans-dermal infection paths. Furthermore, the external fixation is cosmetically intrusive, bulky, and prone to painful inadvertent manipulation by environmental conditions such as, for example, bumping into objects and laying on the device. 
     Other concepts relating to bone repair are disclosed in, for example, U.S. Pat. No. 5,108,404 to Scholten for Surgical Protocol for Fixation of Bone Using Inflatable Device; U.S. Pat. No. 4,453,539 to Raftopoulos et al. for Expandable Intramedullary Nail for the Fixation of Bone Fractures; U.S. Pat. No. 4,854,312 to Raftopolous for Expanding Nail; U.S. Pat. No. 4,932,969 to Frey et al. for Joint Endoprosthesis; U.S. Pat. No. 5,571,189 to Kuslich for Expandable Fabric Implant for Stabilizing the Spinal Motion Segment; U.S. Pat. No. 4,522,200 to Stednitz for Adjustable Rod; U.S. Pat. No. 4,204,531 to Aginsky for Nail with Expanding Mechanism; U.S. Pat. No. 5,480,400 to Berger for Method and Device for Internal Fixation of Bone Fractures; U.S. Pat. No. 5,102,413 to Poddar for Inflatable Bone Fixation Device; U.S. Pat. No. 5,303,718 to Krajicek for Method and Device for the Osteosynthesis of Bones; U.S. Pat. No. 6,358,283 to Hogfors et al. for Implantable Device for Lengthening and Correcting Malpositions of Skeletal Bones; U.S. Pat. No. 6,127,597 to Beyar et al. for Systems for Percutaneous Bone and Spinal Stabilization, Fixation and Repair; U.S. Pat. No. 6,527,775 to Warburton for Interlocking Fixation Device for the Distal Radius; U.S. Patent Publication US2006/0084998 A1 to Levy et al. for Expandable Orthopedic Device; and PCT Publication WO 2005/112804 A1 to Myers Surgical Solutions, LLC for Fracture Fixation and Site Stabilization System. 
     In view of the foregoing, it would be desirable to have a device, system and method for providing effective and minimally invasive bone reinforcement to treat fractured or diseased bones. 
     SUMMARY OF THE INVENTION 
     One embodiment of the present invention provides a low weight to volume mechanical support for fixation, reinforcement and reconstruction of bone or other regions of the musculo-skeletal system. The method of delivery of the device is another aspect of the invention. The method of delivery of the device in accordance with the various embodiments of the invention reduces the trauma created during surgery, decreasing the risks associated with infection and thereby decreasing the recuperation time of the patient. The framework may in one embodiment include an expandable and contractable structure to permit re-placement and removal of the reinforcement structure or framework. 
     In accordance with the various embodiments of the present invention, the mechanical supporting framework or device may be made from a variety of materials such as metal, composite, plastic or amorphous materials, which include, but are not limited to, steel, stainless steel, cobalt chromium plated steel, titanium, nickel titanium alloy (nitinol), super elastic alloy, and polymethylmethacrylate (PMMA). The supporting framework or device may also include other polymeric materials that are biocompatible and provide mechanical strength, that include polymeric material with ability to carry and delivery therapeutic agents, that include bioabsorbable properties, as well as composite materials and composite materials of titanium and polyetheretherketone (PEEK™), composite materials of polymers and minerals, composite materials of polymers and glass fibers, composite materials of metal, polymer, and minerals. 
     Within the scope of the present invention, each of the aforementioned types of device may further be coated with proteins from synthetic or animal source, or include collagen coated structures, and radioactive or brachytherapy materials. Furthermore, the construction of the supporting framework or device may include radio-opaque markers or components that assist in their location during and after placement in the bone or other region of the musculo-skeletal systems. 
     Further, the reinforcement device may, in one embodiment, be osteo incorporating, such that the reinforcement device may be integrated into the bone. 
     In a further embodiment, there is provided a low weight to volume mechanical supporting framework or device deployed in conjunction with other suitable materials to form a composite structure in-situ. Examples of such suitable materials may include, but are not limited to, bone cement, high density polyethylene, Kapton®, polyetheretherketone (PEEK™), and other engineering polymers. 
     Once deployed, the supporting framework or device may be electrically, thermally, or mechanically passive or active at the deployed site within the body. Thus, for example, where the supporting framework or device includes nitinol, the shape of the device may be dynamically modified using thermal, electrical or mechanical manipulation. For example, the nitinol device or supporting framework may be expanded or contracted once deployed, to move the bone or other region of the musculo-skeletal system or area of the anatomy by using one or more of thermal, electrical or mechanical approaches. 
     An embodiment of the invention includes a lockable bone fixation device comprising: a sleeve adapted to be positioned in a space formed in a bone; a guidewire adapted to guide movement of the sleeve; and an actuable lock adapted to secure the sleeve within the space of the bone from an end of the device. The sleeve can be configured to be flexible, have apertures, be expandable and/or be bioabsorbable. Further, the sleeve can be removable from the space within the bone, if desired. The device is adapted and configured to access the space within the bone through an access aperture formed in a bony protuberance of the bone. In a further embodiment, a second sleeve can be provided that is adapted to fit within the first sleeve. Where a second sleeve is provided, the second sleeve can be used to control a retractable interdigitation process or teeth. The sleeve can accomplish this control by being configured with slots or apertures along its length through which the teeth extend when the slots are positioned over the teeth. Once the teeth are exposed through the second sleeve, the teeth or interdigitation process are adapted to engage bone. In still another embodiment of the invention, a cantilever adapted to retain the lockable bone fixation device within the space. Another embodiment of the invention includes adapting the sleeve to be expanded and collapsed within the space by a user. In still another embodiment, the device is adapted to be delivered by a catheter. In yet another embodiment, the distal end of the device is adapted to provide a blunt obdurator surface. In still another embodiment of the device, the distal end of the device is configured to provide a guiding tip. In yet another embodiment of the device, the device is adapted to receive external stimulation to provide therapy to the bone. In still another embodiment of the device, the device is adapted to receive composite material when the device is disposed within a lumen or opening within the body or bone. 
     In another embodiment of the invention, a bone fixation device is provided that comprises: a first sleeve having a retractable interdigitation process at a location along its length adapted to engage a bone; and a second sleeve sized adapted to activate the interdigitation process of the first sleeve. The bone fixation device can be configured to provide a flexible first or second sleeve. In another embodiment, the first or second sleeve can be provided with apertures, can be expandable and/or can be fashioned from bioabsorbable materials. In still other embodiments, either of the first or second sleeve can be removable. In yet another embodiment of the invention, the first and second sleeve are adapted to access a space of the bone through an access aperture formed in a bony protuberance of the bone. In still other embodiments, the second sleeve can be configured to provide a retractable interdigitation process or teeth. Apertures can also be provided in some embodiments, along the length of the device through which the retractable interdigitation process engages the bone. The apertures can, in some embodiments, be on the second sleeve. In some embodiments, the retractable interdigitation process can be adapted to engage bone when actuated by the second sleeve. In still other embodiments, a cantilever retains the bone fixation device within a space of the bone. Further, a first or second sleeve is adapted in some embodiments to be expanded and collapsed within the bone by a user. In still other embodiments, the device is adapted to be delivered by a catheter or catheter-like device. The catheter may be a single or multilumen tube. The catheter may employ methods or apparatus that power or shape the device for introduction and placement. The distal end of the device in some embodiments is adapted to provide a blunt obdurator surface. Additionally, the distal end of the device can have a guiding tip. In still other embodiments, the device is adapted to deliver therapeutic stimulation to the bone. In other embodiments the device is adapted to deliver therapeutic stimulation to the biological processes within bone. These processes are cellular in nature and provide therapeutic remedies to the health of the patient not related to bone. One such therapeutic application is anemia or hemophilia. In yet other embodiments, the device is adapted to receive composite material when the device is disposed within a lumen. 
     In still another embodiment of the invention, a method of repairing a bone fracture is disclosed that comprises: accessing a fracture along a length of a bone through a bony protuberance at an access point at an end of a bone; advancing a bone fixation device into a space through the access point at the end of the bone; bending a portion of the bone fixation device along its length to traverse the fracture; and locking the bone fixation device into place within the space of the bone. The method can also include the step of advancing an obdurator through the bony protuberance and across the fracture prior to advancing the bone fixation device into the space. In yet another embodiment of the method, the step of anchoring the bone fixation device within the space can be included. In still another embodiment of the method, a first sleeve and a second sleeve of the bone fixation device can be engaged to expand an interdigitation process into the bone. 
     An aspect of the invention discloses a removable bone fixation device that has a single end of introduction, deployment, and remote actuation wherein a bone fixation device stabilizes bone. The bone fixation device is adapted to provide a single end in one area or location where the device initiates interaction with bone. The device can be deployed such that the device interacts with bone. Remote actuation activates, deactivates, reduces bone, displaces bone, locks, places, removes, grips, stiffens device, compresses, adjusts, axially adjusts, torsionally adjusts, angularly adjusts, and releases the devices during its interaction with bone. A removable extractor can be provided in some embodiments of the device to enable the device to be placed and extracted by deployment and remote actuation from a single end. The device of the invention can be adapted and configured to provide at least one sleeve. Further the sleeve can be configured to be flexible in all angles and directions. The flexibility provided is in selective planes and angles in the Cartesian, polar, or cylindrical coordinate systems. Further, in some embodiments, the sleeve is configured to have a remote actuation at a single end. Additionally, the sleeve can be configured to have apertures. In still further embodiments, the sleeve is configured to minimize boney in-growth. Another aspect of the invention includes a bone fixation device in that has mechanical geometry that interacts with bone by a change in the size of at least one dimension of a Cartesian, polar, or spherical coordinate system. Further, in some embodiments, bioabsorbable materials can be used in conjunction with the devices, for example by providing specific subcomponents of the device configured from bioabsorbable materials. A second sleeve can be provided in some embodiments where the second sleeve is removable, has deployment, remote actuation, and a single end. Where a second sleeve is employed, the second sleeve can be adapted to provide a deployable interdigitation process or to provide an aperture along its length through which the deployable interdigitation process is adapted to engage bone. In some embodiments, the deployable interdigitation process is further adapted to engage bone when actuated by the sleeve. In some embodiments, the bone fixation device further comprises a cantilever adapted to retain the deployable bone fixation device within the space. The sleeve can further be adapted to be expanded and collapsed within the space by a user. One end of the device can be configured to provide a blunt obdurator surface adapted to advance into the bone. A guiding tip may also be provided that facilitates guiding the device through the bone. Further, the deployable bone fixation device can be adapted to receive external stimulation to provide therapy to the bone. The device can further be adapted to provide an integral stimulator which provides therapy to the bone. In still other embodiments, the device can be adapted to receive deliver therapeutic stimulation to the bone. 
     The invention also includes a method for repairing a bone fracture comprising: accessing a fracture along a length of bone through a bony protuberance at an entry portal; introducing the bone fixation device into the medullary canal through the entry portal; bending the bone fixation device along its length to advance into the medullary space in the bone; bending the bone fixation device along its length to traverse the fracture site; placing a flexible elbow in the medullary canal at the fracture site; stiffening the bone fixation device; locking the bone fixation device to the bone; reducing the fracture with the bone fixation device in place in the medullary canal; locking the flexible elbow to achieve intramedullary reduction of the fracture. The method can further include the step of introducing a guide wire into the medullary space through a bony protuberance at an entry portal. Additionally, the guidewire can be reamed through the bony protuberance at an entry portal. The location of the reamed boney canal can be determined by the fracture anatomy and bone anatomy. In some embodiments of the method, a sleeve can be advanced along the bone fixation device. In such embodiments, the sleeve can function to unlock the spikes from the fixation device. Once the spikes are unlocked from the fixation device, the spikes then fix the device to the bone. Locking butterfly rings can also be employed to lock the device to the bone. The butterfly rings can be locked to the fixation device in some embodiments. Additionally, the rings can be threaded over the device. In other embodiments, a guide jig guides screws through the butterfly rings. Further self tapping screws lock the butterfly rings to the bone and bone fixation device. A set screw can also be used to lock the device at the fracture site. The device can also be stiffened. In performing the method of the invention, fracture fragments can be reduced. 
     Yet another aspect of the invention includes a barb-screw comprising a sleeve, one or more teeth deployable at a distal end of the sleeve, and an actuable lock adapted to secure the sleeve within the space of the bone from an end of the device. 
     These and other features and advantages of the present invention will be understood upon consideration of the following detailed description of the invention and the accompanying drawings. 
     INCORPORATION BY REFERENCE 
     All publications, patents and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which: 
         FIGS. 1A-B  depict an actuable bone fixation device in a pre-deployed and deployed condition; 
         FIGS. 2A-C  depict views of a bearing segment suitable for use in an actuable bone fixation device; 
         FIGS. 3A-C  depict views of a bearing segment suitable for use in an actuable bone fixation device; 
         FIG. 4A-F  depict a retention segment suitable for use in an actuable bone fixation device; 
         FIGS. 5A-B  illustrate an external actuator suitable for use in an actuable bone fixation device; 
         FIGS. 6A-D  illustrate an alternate embodiment of an external actuator suitable for use in an actuable bone fixation device; 
         FIGS. 7A-C  illustrate a pin suitable for use in an actuable bone fixation device; 
         FIGS. 8A-D  illustrate a configuration of an outer sleeve suitable for use in a bone fixation device; 
         FIGS. 9A-D  illustrate an alternate configuration of an outer sleeve suitable for use in a bone fixation device; 
         FIGS. 10A-B  illustrate another embodiment of an actuable bone fixation device in a pre-deployed and deployed condition; 
         FIGS. 11A-B  illustrate yet another embodiment of an actuable bone fixation device in a pre-deployed condition, and deployed condition; 
         FIGS. 12A-C  illustrate the proximal end of an embodiment of an actuable bone fixation device shown in  FIG. 11 , including component parts; 
         FIG. 13A-B  illustrates a universal joint, or u-joint, suitable for use with the devices of the invention; 
         FIG. 14  illustrates a flexible link assembly suitable for use with the devices of the invention; 
         FIGS. 15A-B  illustrate a configuration of a distal assembly; 
         FIGS. 16A-C  illustrate a metaphyseal shaft; 
         FIG. 17  illustrates a metaphyseal locking flange; 
         FIG. 18  illustrates a metaphyseal locking screw; 
         FIG. 19  illustrates a metaphyseal set screw; 
         FIGS. 20A-B  illustrate an alternative embodiment of a u-joint suitable for use with the devices of the invention; 
         FIGS. 21A-B  illustrate an alternative embodiment of a flexible link assembly suitable for use with the invention; 
         FIGS. 22A-B  illustrate a male pin suitable for use with a flexible link assembly; 
         FIGS. 23A-B  illustrate an alternative embodiment of a flexible link assembly; 
         FIGS. 24A-B  illustrate a sheath of a flexible link assembly; 
         FIGS. 25A-B  illustrate an obdurator capture pin; 
         FIGS. 26A-B  illustrate a flexible link male pin; 
         FIG. 27  illustrates a flexible locking pin; 
         FIGS. 28A-B  illustrates a flexible link locking pin; 
         FIG. 29  illustrates an obdurator capture pin; 
         FIGS. 30A-D  illustrate a diaphyseal anchor; 
         FIGS. 31A-B  illustrated a removal tool; 
         FIG. 32  illustrates a device of the invention deployed in a radius bone; 
         FIG. 33  illustrates another actuable bone fixation device according to the invention; 
         FIG. 34  illustrates a cross-section of a diaphyseal to metaphyseal section in a bone; 
         FIG. 35  illustrates a surgical access point into the intramedullary space; 
         FIG. 36  illustrates a device of the invention positioned within an access lumen; 
         FIG. 37  illustrates An actuable barb-screw according to the invention; 
         FIG. 38  illustrates a deployed barb-screw; 
         FIG. 39  illustrates a side view of a barb-screw; 
         FIG. 40  depicts a two part barb-screw according to the invention; 
         FIG. 41  illustrates a deployed actuable bone fixation device deployed with transversely positioned actuable barb-screws; 
         FIG. 42  illustrates a deployed actuable bone fixation device deployed with radially positioned barb-screws; 
         FIG. 43  illustrates a deployed actuable bone fixation device deployed with mixed orientation barb-screws; 
         FIG. 44  illustrates a femur of a patient with an indication of access points; 
         FIG. 45  illustrates a femur of a patient with a drill accessing the shaft; 
         FIG. 46  illustrates a femur with a coring reamer boring a hole in the shaft of the bone; 
         FIG. 47  illustrates a lavage system used with a bidirectional flow path to remove debris from within the bone; 
         FIG. 48  illustrates an actuable bone fixation device within a bone; 
         FIG. 49  illustrates the device of  FIG. 48  from a perspective view; 
         FIG. 50  illustrates a cross-sectional view of the device of  FIG. 48 ; 
         FIG. 51  illustrates deployment of a cross-bone stabilization device; 
         FIG. 52  illustrates positioning of a reinforcement device at a desired location; 
         FIGS. 53A-E  illustrate implantation of a plurality of structural reinforcement devices within a bone; 
         FIG. 54  illustrates an expandable device; 
         FIG. 55  illustrates a device coring into the upper trochanter region of the bone; and 
         FIG. 56  illustrates delivery of a device into the upper trochanter. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     By way of background and to provide context for the invention, it may be useful to understand that bone is often described as a specialized connective tissue that serves three major functions anatomically. First, bone provides a mechanical function by providing structure and muscular attachment for movement. Second, bone provides a metabolic function by providing a reserve for calcium and phosphate. Finally, bone provides a protective function by enclosing bone marrow and vital organs. Bones can be categorized as long bones (e.g. radius, femur, tibia and humerus) and flat bones (e.g. skull, scapula and mandible). Each bone type has a different embryological template. Further each bone type contains cortical and trabecular bone in varying proportions. 
     Cortical bone (compact) forms the shaft, or diaphysis, of long bones and the outer shell of flat bones. The cortical bone provides the main mechanical and protective function. The trabecular bone (cancellous) is found at the end of the long bones, or the epiphysis, and inside the cortex of flat bones. The trabecular bone consists of a network of interconnecting trabecular plates and rods and is the major site of bone remodeling and resorption for mineral homeostasis. During development, the zone of growth between the epiphysis and diaphysis is the metaphysis. Finally, woven bone, which lacks the organized structure of cortical or cancellous bone, is the first bone laid down during fracture repair. Once a bone is fractured, the bone segments are positioned in proximity to each other in a manner that enables woven bone to be laid down on the surface of the fracture. This description of anatomy and physiology is provided in order to facilitate an understanding of the invention. Persons of skill in the art, will appreciate that the scope and nature of the invention is not limited by the anatomy discussion provided. Further, it will be appreciated there can be variations in anatomical characteristics of an individual, as a result of a variety of factors, which are not described herein. 
       FIGS. 1A-B  depict an actuable bone fixation device  100  in a pre-deployed and deployed condition. The bone fixation device  100  has a proximal end  102  and a distal end  104 . The proximal end and distal end, as used in this context, refers to the position of an end of the device relative to the remainder of the device or the opposing end as it appears in the drawing. The proximal end can be used to refer to the end manipulated by the user or physician. The proximal end may be configured such that a portion thereof remains outside the bone. Alternatively, the proximal end is configured such that it does not remain outside the bone. The distal end, thus, can be used to refer to the end of the device that is inserted and advanced within the bone and is furthest away from the physician. As will be appreciated by those skilled in the art, the use of proximal and distal could change in another context, e.g. the anatomical context. 
     The bone fixation device is suitable for reinforcing and/or repairing a bone. Further, the bone fixation device is adapted to be anatomically conformable. Still further, the bone fixation device is adapted to cross a fracture. Once actuated, the device anchors into a portion of the bone and then draws the bone segments effected by the fracture together. Kirshner or K-wires can also be used where there are additional fracture fragments. 
     The bone fixation device  100  has an actuator  110  at a proximal end  102 . The actuator  110  enables a user to control the movement, insertion, deployment, removal, and operation of the device. The actuator  110  has internal threads (not shown) that engage threads  112  formed on a shaft or guidewire  120 . The shaft  120  extends through a proximal bearing segment  132 , intermediate bearing segments  134  and terminates in a distal bearing segment  136 . Interposed between the bearing segments on shaft  120  are anchoring segments  140 . The bearing segments control translation and bending of the device  100 . In some embodiments, the bearing segments can withstand, for example, up to 800 lb of axial loading force. The anchoring segments  140  have radially extending teeth or grippers  142  that deploy upon actuation of the device  100  to interlock the device with the bone, as explained below. 
     The outer sheath  150  is a component of the device  100 . The outer sheath surrounds a portion of the exposed length of the device  100 . Slots  152  are provided along its length that enable the teeth  142  of the anchoring segment  140  to extend radially away from the external surface of the device  100  and into the bone when the device is actuated. The slots  152  can also be adapted to promote or control bending of the device, as will be appreciated below. In  FIG. 1A , the device is depicted in a pre-deployed state, i.e., prior to deploying the anchoring teeth. Prior to deployment, the teeth  142  of the anchoring segment  140  are positioned within the sleeve  150 . When the device is actuated, as illustrated in  FIG. 1B , the actuator  110  is rotated such that the drive shaft  120  is drawn into the actuator  110 . Drawing the drive shaft  120  into the actuator pulls the bearing segments and anchoring segments proximally with respect to the sleeve  150 , thus positioning the anchoring segments  140  and teeth  142  adjacent the slots  152 . In this embodiment, teeth  142  are formed from an expansible material such as a shape memory alloy, such as the nitinol, to restore to an unconstrained position upon actuation of the device. This actuation results in movement of the teeth radially away from the shaft of the device. The teeth are retractable as needed or desired by reversing the direction of rotation of actuator  110 , thereby pushing the bearing segments and anchoring segments distally with respect to the sleeve. The slope and angle of teeth  142  help the edge of slots  152  cam teeth  142  inward to the position shown in  FIG. 1A . 
       FIGS. 2A-C  depict views of a bearing segment  230  (see also, bearing segment  136  in  FIG. 1 ) suitable for use in an actuable bone fixation device at, for example, the distal end. As illustrated in  FIGS. 2A-B , the bearing segment, as depicted, has a substantially spherical dimension, with a lumen  232  positioned therethrough for receiving a drive shaft or guide wire, such as shown above. The lumen, as depicted, has a first circumference at a first end  233  and a second circumference  233 A at a second end. First circumference,  233 , is a distal circumference (as oriented during implantation) adapted and configured to accommodate a swaged or discontinuous intermediate interfering locking feature. The swaged feature prevents proximal to distal translation of the distal bearing segment,  136  of the device, thereby retaining all proximal internal components of the device  100 .  FIG. 2C  illustrates the bearing segment in cross-section further illustrating a substantially circular external shape with a first diameter  233  corresponding to the first circumference and a second diameter  233 A corresponding to the second circumference. When positioned distally, the bearing segment can function as a blunt obdurator adapted to facilitate penetration of bone. 
       FIGS. 3A-C  depict views of another bearing segment  330  suitable for use in an actuable bone fixation device. The bearing segment, as depicted, has a substantially spherical dimension, with a lumen  332  positioned therethrough. The lumen depicted in this embodiment has a constant, or substantially constant, diameter along its length suitable for receiving the drive shaft or guide wire  120  of a device  100 . Additional detents  336 , indentations or lumens can be provided. The detents  336  can be configured on the surface such that the detents would be positioned on opposing sides of the bearing segment  330 , as depicted, without crossing or penetrating the lumen  332  formed to receive the drive shaft. The detents can be formed to receive pins, or be formed to provide an additional lumen through the bearing segment, or compressed or swaged onto the drive shaft or can be configured in any other suitable configuration. As depicted in  FIG. 3C , the lumen  332  traverses the bearing segment  330 , while the detents are formed on opposing sides and oriented 90° from an axis around which the lumen  332  is positioned. Other orientations and configurations are possible without departing from the scope of the invention. 
     Turning now to  FIG. 4A-F , a retention or anchoring segment suitable for use in an actuable bone fixation device of the invention is depicted.  FIGS. 4A-B  illustrate perspective views of the anchoring segment  440  prior to deployment of the teeth  442 . The anchoring segment  440  is adapted to fit within the sleeve  150  ( FIGS. 1A-B ) and to have a central lumen  444  through which a drive shaft  120  ( FIGS. 1A-B ) or guidewire can be positioned. A portion of the exterior surface of the anchoring segment  440  can be configured to form one or more teeth  442 . The teeth  442  can be formed integrally with the anchoring segment  440 . The teeth  442  and/or the anchoring segment  440  can be formed of any suitable material, including nitinol. Where a shape memory alloy is used, the teeth  442  can be configured to assume a pre-determined shape when the teeth are not constrained within the sleeve, as shown in  FIG. 4E . Additional slots  446  can be provided along the length of the anchoring segment. The slots  446  can be used to engage, for example, pins extending from the outer sleeve to control rotational movement of the anchoring segment within the sleeve. Turning to  FIG. 4D-E , the teeth  442  are bent away from the exterior surface of the anchoring segment  440 .  FIG. 4F  illustrates a cross-section of the anchoring device depicted herein wherein the teeth  442  are deflected away from the sides of the anchoring segment. The teeth may emanate from alternate surfaces and cross at the centerline of the lumen  444 , thereby creating a longer cantilever segment. 
       FIGS. 5A-B  illustrate an actuator suitable for use in an actuable bone fixation device. The actuator  510  has a cylindrical body  512  with a threaded female interior  514  or any other configuration capable of actuation for exposure of the teeth  442 . A flange  516  is provided that can be used to anchor the device against a surface, such as bone. Additionally, the top surface of the flange  516  can be adapted to enable control of the actuator  510  and the drive shaft  120  shown in  FIG. 1 . One or more apertures  518  can be provided to engage, for example, screws. The apertures  518  can provide a mechanism to anchor the device to the surface of the bone (as opposed to just abutting the surface of the bone). The outer circumferential surface  517  of the flange  516  can further be provided with markings 
       513  or adapted to provide an indicator to facilitate deploying the teeth by providing an indication to the user of the relative position of the teeth relative to the slots on the sheath and relative to the plane within the bone. Thereby establishing the direction of flexibility of the device while in bone. Additionally, a central aperture  519  which forms a keyway can be provided for engaging an additional tool or device to control the deployment of the bone fixation device. For example, the central aperture  519  can be in the shape of a slit to accept, for example, the head of a flat head screw driver. 
       FIGS. 6A-D  illustrate an alternate embodiment of an actuator  610  suitable for use in an actuable bone fixation device. In the embodiment depicted in  FIGS. 6A-B , the central aperture  619  is adapted to engage a tool with a threaded end.  FIGS. 6C-D  illustrate a top view and side view of the actuator  610 . Similar to the device depicted in  FIG. 5 , actuator  610  has a cylindrical body  612  with a threaded female interior  614  or any other configuration capable of actuation for exposure of the teeth  642 . A flange  616  is provided that can be used to anchor the device against a surface, such as bone. Additionally, the top surface of the flange  616  can be adapted to enable control of the actuator  610  and the drive shaft  120  (shown in  FIG. 1 . One or more apertures  618  can be provided to engage, for example, screws. The apertures  618  can provide a mechanism to anchor the device to the surface of the bone (as opposed to abutting the surface of the bone). Additionally, a central aperture  619  which forms a keyway can be provided for engaging an additional tool or device to control the deployment of the bone fixation device. For example, the central aperture  619  can be in the shape of a slit to accept, for example, the head of a flat head screw driver. 
       FIGS. 7A-C  illustrate a pin  760  suitable for use in an actuable bone fixation device to prevent rotational movement of the anchoring segment relative to the sheath. The pin  760  has a head  762  adapted to engage an interior portion of the sleeve and a neck  764  to fit within the slot in the anchoring mechanism. 
       FIGS. 8A-D  illustrate a configuration of an outer sleeve  850  suitable for use in a bone fixation device. In the configuration depicted, c-cuts  852  and  852 A are used along the length of the sheath  850 . The use of c-cuts provides flexibility in the plane perpendicular to the page described along the central axis of the sheath. As depicted, two types of c-cuts can be used, as opposed to a single type of c-cut shown in  FIG. 1 . At the distal end  804 , c-cuts are paired at a location on the length and extend, from opposite sides, toward a central plane of the sheath. The c-cuts enable the teeth of the device,  442  to extend outward, away from the central shaft, into the bone. Toward a proximal end  802 , c-cuts are shorter in height and extend across a central plane of the sheath (e.g. a plane in which the guidewire or control rod running through the center of the device would lie). Thus, from one side view, the cuts have an s shape profile, as shown in  FIG. 8C . The distal cuts provide flexibility as well as enabling the teeth,  442  to extend through the cuts when the device is actuated. The proximal cuts also provide flexibility, but provide a different degree of flexibility as a result of the orientation and design of the cuts. As depicted in  FIG. 8D , which is a cross-section taken along the lines D-D of  FIG. 8C , the proximal set of c-cuts give the appearance that the sheath is segmented, while the distal cuts appear as opposing c-cuts. By this method the planar preferential flexibility is established in a representative, but not limiting, embodiment of the device. As will be appreciated by those skilled in the art, more than two-types of c-cuts can be used without departing from the scope of the invention. 
       FIGS. 9A-D  illustrate yet another alternate configuration of an outer sleeve suitable for use in a bone fixation device. In the device depicted, instead of providing the deep c-cuts on the proximal set of cuts depicted in  FIG. 8 , spiral cuts  954  are provided. The spiral cut provides flexibility in all directions and in all planes. As depicted, c-cuts  952  are used along at least a portion of the length of the sheath  950   
     Turning now to  FIGS. 10A-B  another embodiment of an actuable bone fixation device  1000  in a pre-deployed and deployed condition is depicted. This embodiment uses an outer sheath  1050  with two types of c-cuts, as illustrated and described with respect to  FIG. 8  above. C-cuts  1052  are used along the length of the sheath  1050 . As described above, the use of c-cuts provides flexibility in the plane perpendicular to the page along the central axis of the sheath. As with  FIG. 8 , two types (or more) of c-cuts can be used, as opposed to a single type of c-cut shown in  FIG. 1 . At the distal end  1004 , c-cuts are paired at a location on the length and extend, from opposite sides, toward a central plane of the sheath. The c-cuts enable the teeth of the device,  1042  to extend outward, away from the central shaft, into the bone. Toward a proximal end  1002 , c-cuts are shorter in height and extend across a central plane of the sheath (e.g. a plane in which the guidewire or control rod running through the center of the device would lie). Thus, from one side view, the cuts have an s shape profile, as shown in  FIG. 10B . The distal cuts provide flexibility as well as enabling the teeth,  1042  to extend through the cuts when the device is actuated. The proximal cuts also provide flexibility, but provide a different degree of flexibility as a result of the orientation and design of the cuts. 
       FIGS. 11A-B  illustrate another embodiment of an actuable bone fixation device  1100  in a pre-deployed and deployed condition. The device  1100  has a proximal end  1102  and a distal end  1104 . Section  1106  is the part of the device that is placed within the metaphyseal section of bone. Section  1106  can also be placed in other types of bone including epiphyseal and diaphyseal. Section  1108  is the section of the device that sits within diaphyseal bone. The proximal end assembly  1110  implements the interface to the metaphyseal bone. Also visible in  FIG. 11  are the metaphyseal locking flange  1112  and metaphyseal locking screw  1114 . Section  1130  is the universal joint that provides articulation and alignment. Section  1132  is the universal joint sheath. The flexible link  1140  provides flexibility in the lateral medial plane. Section  1142  is the flexible link sheath. Section  1150  is the outer sheath of the device with slot  1152 . Section  1160  is the distal end assembly. Section  1162  is the obdurator and Section  1164  is the distal end flexible link male pin. Section  1170  is the diaphyseal anchor with teeth  1172 . At the distal end  1104  and the proximal end  1102  the flexible link sections  1140  can be adapted to engage diaphyseal anchoring segments  1170 . The anchoring segments  1170 , as depicted, fit snugly around the flexible link sections  1130 . Each diaphyseal anchoring segment  1170  can have one or more teeth or grippers  1172  that are adapted to enable the teeth to interdigitate within bone when deployed. The teeth  1172  can be configured to enable the teeth to deflect away from the anchoring segment  1170  and into the bone. The teeth  1172  extend at an angle to enable greatest anchoring with the shortest length. As the teeth  1172  dig into the bone, the teeth oppose torque and oppose proximal and rotational movement. The outer sheath  1150  is positioned to maintain the teeth  1172  adjacent the sections of the device until the slots  1152  are adjacent the teeth  1172 , at which point the teeth  1172  then can engage the bone. The distal end  1104  can be adapted to form an obdurator  1162  to maintain and/or create the space within the bone through which the device penetrates. As illustrated in  FIG. 11B , the teeth  1172  flare away from the device  1100  when adjacent the slots  1152 . 
       FIGS. 12A-C  illustrates an embodiment of the proximal end assembly  1200 . This assembly consists of the metaphyseal shaft  1210 , one or more metaphyseal locking flanges  1220 , the metaphyseal locking screw  1230  and the metaphyseal set screw  1240 . The metaphyseal set screw  1900  is depicted in additional detail in  FIG. 19 . The metaphyseal shaft  1210  translates the fixative forces through the universal joint  1130  to the diaphyseal section  1108 . The metaphyseal locking flange  1220  bears on the metaphyseal shaft  1210 . The metaphyseal locking screw  1230  threads through the metaphyseal locking flange  1220 , cuts into and retains the metaphyseal locking flange  1220  to the metaphyseal shaft  1210 , and secures bone, cartilage, animal tissue to the metaphyseal shaft  1210 . 
       FIGS. 13A-B  illustrates an embodiment of a universal joint  1300 . This embodiment consists of a sheath  1310 , (sheath  2200  is illustrated in additional detail  FIG. 20 ) and a diaphyseal pin  1320 , (diaphyseal pin  2100  illustrated in additional detail  FIG. 21 ). The universal joint  1300  allows the metaphysis section  1106  to have hemispherical rotation relative to the axis of the diaphysis section  1108 . The diaphyseal pin  1320  connects the universal joint  1300  to the first proximal flexible link  1400 . 
       FIG. 14  illustrates an embodiment of the flexible link assembly  1400 . The flexible link assembly  1400  is comprised of the female pin  1420 , (female pin  2300  is illustrated in additional detail in  FIGS. 23A-B ), male pin  1410 , (male pin  2200  is illustrated in additional detail in  FIGS. 22A-B ), and the sheath  1430  (sheath  2400  is illustrated in additional detail in  FIGS. 24A-B ). The male flexible link pin  2200  has bearing surface  2214  that is captured within and slides axially and angularly within the sheath  2400 . The female flexible link pin bearing surface  2312  interfaces to the sheath bearing surface  2430 . The bores  2218  in the male and  2316  in the female pins accept the flexible link locking pin  2800 . The shape of the male flexible link pin  2200  and female flexible link pin  2300  allow medial to lateral flexibility prior to placement of the flexible link locking pin  2800 . The bore  2218  through the male flexible link  2200  accepts the flexible link locking pin  2800 . Upon insertion and proximal to distal actuation of the flexible link locking pin  2800 , the male  2200  and female  2300  flexible link pins are thereby translated such that a locking force is imparted between the sheath  2400  and female flexible link pin. This locking system imparts a resistive force to motion in the medial-lateral plane of the diaphysis and metaphysis. The bore  2218  through the male flexible link pin  2200  is shaped such that there is clearance up to 180 spherical degrees of angulation of the entire assembly, though 30 to 45 degrees of angulation is typical.  FIG. 30  show an embodiment of the diaphyseal anchor  3000  which compromise teeth  3010  and an annular section  3020 . The diaphyseal anchor slips over and rigidly interferes with the shaft  2400  of the flexible link  1400 . The teeth  3010  of the anchoring segment  3000  are designed for specific and maximal fixation to diaphyseal, metaphyseal and epiphyseal bone. The angulation coupled with rotation and shape of the teeth  3010  can take the form of pins, rods, rectangles, frustums of cones, pyramids or other polygons. The number of teeth  3010  is typically two but not limited. In the embodiment shown the teeth  3010  are oriented to prevent axial and rotational translation of the device when deployed within bone. Sets of teeth  3010  can be juxtaposed to resist distal to proximal and proximal to distal axial translation. It is known in the art that the intramedullary space is inconsistent in internal diameter, the diaphyseal anchors  3000  can be specifically designed to accommodate these inconsistencies in internal diameter by changing the shape of the teeth  3010 . 
       FIGS. 15A-B  illustrate an embodiment of the distal end assembly  1500 . The distal end assembly  1500  is comprised of the obdurator or distal bearing surface  1510  (distal bearing surface  2500  is illustrated in additional detail in  FIG. 25 ), distal end flexible link male pin  1520  (flexible link male pin  2600  is illustrated in additional detail in  FIG. 26 ), obdurator captive pin  1530  (obdurator captive pin  2700  is illustrated in additional detail in  FIG. 27 ), flexible link locking pin  1540  (flexible link locking pin  2800  is illustrated in additional detail in  FIGS. 28A-B ). The distal bearing surface  2500  is connected to the flexible locking pin  2800  and outer sheath  2900  in  FIG. 29 . The obdurator captive pin  2700  limits the range of movement of the outer sheath  2900  relative to the teeth  3010  of the anchor segments  3000 . 
       FIGS. 16A-C  illustrate an embodiment of a metaphyseal shaft  1600 . The bearing surface  1630  of this embodiment interfaces to the metaphyseal locking flange  1700 , it can be smooth, serrated, knurled, splined, keyed, polygonal or elliptical. The connective surface  1610  connects the metaphyseal shaft  1600  to the universal joint  1300  of  FIG. 13 . The metaphyseal shaft  1600  provides means to translate fixative forces from the metaphyseal section  1106  of  FIG. 11  to the universal joint  1300 . Within the metaphyseal shaft  1600  is a means to lock the proximal assembly  1200  of  FIG. 12  to the diaphyseal section  1108  of  FIG. 11  through the universal joint  1300  and prevent 360 spherical degrees of movement perpendicular and parallel to the longitudinal axis of the diaphysis. 
       FIG. 17  illustrates an alternate embodiment of a metaphyseal locking flange  1700 . Screw hole  1710  accepts the metaphyseal locking screw  1800  of  FIG. 18 . Opening  1716  accepts the metaphyseal shaft  1600  of  FIG. 16 . Windows  1712  exposes the metaphyseal shaft  1600  and accepts the metaphyseal locking screw threads  1810  and  1820  of  FIG. 18  thereby translating forces through metaphyseal locking screw  1800  to metaphyseal shaft  1600  and locking metaphyseal locking flange  1700  to metaphyseal shaft  1600 . Opening  1716  allows 360 degree rotation of metaphyseal locking flange  1700  about the metaphyseal shaft  1600 . Angle  1720  as described by a line perpendicular to the axis of the shaft and the surface perpendicular to the axis of the screw hole  1710  can be 0 to 180 degrees. This embodiment is meant to be descriptive but not limiting. The function of the metaphyseal locking flange  1700 , metaphyseal locking screw  1800  and metaphyseal shaft  1600  allow for translation of the metaphyseal fixation to diaphyseal fixation that is infinitely adjustable in 360 spherical degrees in the axes parallel and perpendicular to the axis of the diaphysis. 
       FIG. 18  illustrates an embodiment of the metaphyseal locking screw  1800 . The threads  1810  and  1820  of the metaphyseal locking screw can be of a single pitch root in diameter or multiple pitch, root and diameters. The threads  1820  and  1810  can take on a variety of features such as smooth, serrated, knurled, splined, keyed, polygonal or elliptical. The metaphyseal locking screw  1800  can be cannulated through its axis to allow deployment by guide wire. 
       FIG. 31  illustrates an embodiment of a deployment removal tool  3100  for use with the implantable devices of the invention. The tool  3100  consists of a handle  3110 , a flexible shaft  3120  and threaded socket  3130 . 
       FIG. 32  illustrate a radius bone  3201  from an arm having a fracture  3202 , a radius bone with a device  3203  implanted therein, and a cross-sectional view of a portion of a radius bone with a device implanted therein. While  FIG. 32  shows the location of a fracture  3202  in the radius bone  3201 , it will be appreciated that the present invention and the various embodiments thereof can be applied to fractures of varying degrees and at any location within a bone structure. Furthermore, it will be appreciated those skilled in the art that the various embodiments of the present invention can be applied to any bone in an animal including human, and the nature of the fracture may be single, compound or fragmented fractures due to external trauma, or due to bone related disease such as osteoporosis. As depicted in  FIG. 32 , the device  3203 , accesses the bone at a bony protuberance  3204  through the trabecular bone. The device  3203  advances through the cortical bone  3205  and, as pictured, is positioned within the intramedullary space  3206  within the bone marrow or other intramedullary constituents. 
       FIG. 33  illustrates another embodiment of an actuable bone fixation device  3310  having a wire form outer sheath  3320  along at least a portion of the length. The wire sheath can be welded to a stainless steel hypotube, for example, and can be configured to provide the ends be in a turned-out position to prevent rotation. 
     A challenge in bone fixation across the diaphysis to the metaphysis has been securing the cancellous bone in the metaphysis. This bone is sponge-like and can be brittle or vacuous, particularly in osteoporotic patients. A physician must choose between rigid to rigid surface fixation and rigid to porous surface fixation. One embodiment of a system capable of achieving rigid to porous fixation in skeletal bone is described here.  FIG. 34  is a cross section of a diaphysis to metaphysis transition of one of the skeletal bones of an animal or human. A cancellous or porous bone  3401  of the metaphysis is depicted. An intramedullary space  3402  is depicted along an axis of the bone.  FIG. 34  illustrates a portion of a bone  3403  having a transverse fracture and an oblique fracture bone chip  3404 . The challenge in practice is to tie these three bone fragments, one of the diaphysis and the two of the metaphysis together. Embodiments of this invention enable the formation of a foundation rigidly secured in all Cartesian, polar, spherical and cylindrical axes of the diaphysis.  FIG. 35  demonstrates surgical access to the intramedullary space  3502  after creating a lumen  3501  from the metaphyseal bone to the diaphyseal bone. The device,  3601 , described in the preceding invention description is placed in the lumen and deployed as shown in  FIG. 36 .  FIG. 37  illustrates a novel barb-screw. The barb-screw consist of a tool interface such as a hex head, flat head, torx head, or Phillips head screw drive Feature  3701 . Feature  3702  is a thread that threads into and locks to the metaphyseal section of the device  3601  or through the metaphyseal locking flange  1700 . The barb screw is comprised of wires or filaments,  3703 , of nickel titanium or other rigid metallic, polymer, or ceramic material capable of deformation over a significant strain without yield or fracture. In one embodiment, the wires or filaments are beveled at the end  3704 , to create a sharp or penetrating end. Upon removal of suppressive force such as a sheath  3705  or actuation by thermal, electrical, or mechanical means, the filaments undergo a physical change and change shape to  3801  or other shape, as shown in  FIG. 38 . A plurality of wires or filaments  3901  may be positioned along the length of the barb-screw as shown in  FIG. 39 . The wires or filaments may serve multiple purposes, such as creating a thread to facilitate placement of the barb screw. Upon removal of the restraining force or application of an external motive force the dual purpose screw feature,  4001 , can then turn and arc to capture bone as shown in  FIG. 40 . The barb-screw can be deployed through the device  3601 , retained by the thread,  4001 , to the device  3601 , and capture bone transverse  4101  to the placement of the device  3601  as shown in  FIG. 41 . The barb-screw can capture bone radially,  4201 , from the device  3601  as shown in  FIG. 42 . A mixed mode of bone fragment capture may be utilized as well as shown in  FIG. 43 . 
     The actuable barb screw is adapted to provide a small diameter with great amount of surface area upon deployment; a combination of screw and barb capture modalities; locking threads to the device  3601 ; and an activation by removal of external force or by imparting energy to the device by thermal, electrical, optical, or mechanical means. Any frequency of the spectrum of electromechanical radiation may be used to impart such energy to the system. 
     As will be appreciated by those skilled in the art, the actuable barb screw can be configured to provide superior holding force and capture by employing rigid materials that change their radius of capture area after undergoing a change. Further, the barbs may be configured to be displaced as threads to aid insertion of the barb-screw. 
     Additional embodiments, methods, and uses are envisioned in accordance with the inventive attributes. Thus, for example, the drill can be used to bore an access opening into the trabecular (cancellous) bone at a bony protrusion located at a proximal  4401  or distal  4402  end of  FIG. 44  of a bone having a fracture; where the proximal end in the anatomical context is the end closest to the body midline and the distal end in the anatomical context is the end further from the body midline. For example, on the humerus, at the head of the humerus (located proximal, or nearest the midline of the body) or at the lateral or medial epicondyle (located distal, or furthest away from the midline); on the radius, at the head of the radius (proximal) or the radial styloid process (distal); on the ulna, at the head of the ulna (proximal) or the ulnar styloid process (distal); for the femur, at the greater trochanter (proximal) or the lateral epicondyle or medial epicondyle (distal); for the tibia, at the medial condyle (proximal) or the medial malleolus (distal); for the fibula, at the neck of the fibula (proximal) or the lateral malleoulus (distal); the ribs; the clavicle; the phalanges; the bones of the metacarpus; the bones of the carpus; the bones of the metatarsus; the bones of the tarsus; the sternum and other bones with adequate internal dimension to accommodate mechanical fixation. As will be appreciated by those skilled in the art, access locations other than the ones described herein may also be suitable depending upon the location and nature of the fracture and the repair to be achieved. Additionally, the devices taught herein are not limited to use on the long bones listed above, but can also be used in other areas of the body as well, without departing from the scope of the invention. It is within the scope of the invention to adapt the device for use in flat bones as well as long bones. 
     In accordance with one embodiment of the method, an incision  4501  as shown in  FIG. 45  may be made on the skin of the patient at a location substantially aligned with, for example, a proximal or distal end of the fractured bone (e.g., an end of the bone where cancellous bone is located). The incision thus allows the skin substantially surrounding the incision at location to be pulled or folded back in order to expose the end of the fractured bone. The location of the access site is chosen by the surgeon based upon the diagnosis of the best entry point for the various devices of the invention. Access points include-areas of the bone that are considered minimally invasive. These sites include the areas of the bones at the intersection at the elbow, knee, and ankle, i.e. the trabecular or cancellous bone located at the end of the long bones. 
     A drill bit may be operated  4502  by the surgeon to bore an opening to create a space within a central portion of the fractured bone. See, U.S. Pat. No. 6,699,253 to McDowell et al. for Self-Centering Bone Drill. Although, as will be appreciated by those skilled in the art, any tool capable of boring through the layer of tissue and into the fractured bone may be used without departing from the scope of the invention. One example of such a device includes, but is not limited to, a coring reamer  4601  as shown in  FIG. 46  which may be used to bore into the bone as discussed below. See, U.S. Pat. No. 6,162,226 to de Carlo Jr. for Long Bone Reamer with Depth Stop Indicator. The coring reamer in one embodiment may be configured to harvest a bone plug from the access point for future closure of the surgically created wound. This method would facilitate healing, and improve the surgical outcome in regards to strength, infection, and immune rejection of any foreign body. 
     The drill or reamer can be operated along the length of the bone in order to reach the location of the bone fracture. As would be appreciated by those skilled in the art, the use of a flexible reamer may require distal guidance  4602  to prevent inadvertent injury or damage to the surrounding bone. In order to provide such guidance, a wire, or other thin resilient, flexible entity of minimal cross sectional size, can be provided to provide such guidance. The guide wire is placed subsequent to creation of the access site and exposure of the space. A secondary access hole  4603  can be created distal to the initial access. The guide wire is then deployed using standard technique into the bone space, across the bone from the proximal access hole to the secondary access hole. Further, the device can use its distal end as an obdurator to create a path through the bone, through the intramedullary space, and/or across a fracture, is desired. 
     A centering entity  4604 , may be used to “float” the guide wire away from the extremities of the inside feature of the space and bone. The guide wire and centering entity may be left in place throughout the procedure and may be present considerable advantages for subsequent cleaning, and placement of the reinforcement device. The second distal access may be optional. The centering entity, or visualization under fluoroscopy, may obviate the need for the distal access. In this embodiment of the use of the guide wire, the centering entity can be used independently of the distal access. Another embodiment eliminates both the distal access and the centering device. In that embodiment, only the guide wire is used to center the reaming tool. In another embodiment the guide wire is not used. The reaming tool is centered by technique of visualization under fluoroscopy or other means. 
     Thereafter, a channel within the bone, such as within the intramedullary space, is created and is cleaned to remove the bone and fat debris prior to the deployment of the reinforcement device through the space within the fractured bone. Irrigation and cleaning of the channel created in the bone would be accomplished using techniques known in the art. For example, irrigation can be accomplished using water, saline or ringers solution. Solutions that include other solutes may also be beneficial; for example, solutions of having functional or therapeutic advantage, as well as growth stimulation and anti-infection agents such as antibiotic, including gentomiacin. 
     A lavage system can also be used, such as a lavage system  4701  shown in  FIG. 47  which includes bi-directional flow path tubing. The lavage system can be used to remove bone fragments and fat debris from space as a result of using the drill or coring reamer. In one embodiment, the lavage system includes an inflow of saline solution provided into the space of the fractured bone, while a vacuum suction by the flow path tuning removes the bone and debris fragments loosened in saline solution. In this manner, the space within the fractured bone may be cleaned and prepared for the deployment of the reinforcement device to the fracture site of the bone. See, U.S. Pat. No. 4,294,251 to Greenwald et al. for Method of Suction Lavage. 
     The coring reamer or drill can be used to create a space within the fractured bone, as well as past the location of the fracture itself The lavage system can be similarly configured to clean the debris within the space including at the location of the fracture. The reamer or drill may traverse the fracture site independently or in conjunction with a protective sheath across the fracture site. As will be appreciated by those skilled in the art, the space may be reamed from both ends, from a proximal opening and a distal opening up to the fracture site. 
     As discussed above, in accordance with one embodiment of the present invention, the physical trauma to the patient is substantially minimized in treating the bone fracture by limiting the incision to a relatively small location corresponding to the proximal end of the fractured bone, allowing faster patient recovery and wound healing. 
     This procedure can use a smaller opening than the procedure used for an intramedullary nail. Further, the device and its operation, minimizes or eliminates the risk of pain or necrosis of the bone. 
     Candidate materials for the devices and components would be known by persons skilled in the art and include, for example, suitable biocompatible materials such as metals (e.g. stainless steel, shape memory alloys, such a nickel titanium alloy nitinol) and engineering plastics (e.g. polycarbonate). See, for example U.S. Pat. No. 5,190,546 to Jervis for Medical Devices Incorporating SIM Memory Alloy Elements and U.S. Pat. No. 5,964,770 to Flomenblit for High Strength Medical Devices of Shape Memory Alloy. In one embodiment, the outer exoskeleton or sheath may be made of materials such as titanium, cobalt chrome stainless steel. Alternatively, the sheath can be made of biocompatible polymers such as polyetheretherketone (PEEK), polyarylamide, polyethylene, and polysulphone. 
     As will be appreciated by those skilled in the art, the polymer or thermoplastic used to make any of the components of the device, such can comprise virtually any non-radiopaque polymer well known to those skilled in the art including, but not limited to, polyether-etherketone (PEEK), polyphenylsolfone (Radel®), or polyetherimide resin (Ultem®). If desired, the polymer may also comprise a translucent or transparent material, or a combination of materials where a first material has a first radiopacity and the second material has a second radiopacity. Suitable PEEK can include an unfilled PEEK approved for medical implantation. The devices and components can be formed by extrusion, injection, compression molding and/or machining techniques, as would be appreciated by those skilled in the art. 
     Other polymers that may be suitable for use in some embodiments, for example other grades of PEEK, such as 30% glass-filled or 30% carbon filled, provided such materials are cleared for use in implantable devices by the FDA, or other regulatory body. The use of glass filled PEEK would be desirable where there was a need to reduce the expansion rate and increase the flexural modulus of PEEK for the instrument. Glass-filled PEEK is known to be ideal for improved strength, stiffness, or stability while carbon filled PEEK is known to enhance the compressive strength and stiffness of PEEK and lower its expansion rate. Still other suitable biocompatible thermoplastic or thermoplastic polycondensate materials may be suitable, including materials that have good memory, are flexible, and/or deflectable have very low moisture absorption, and good wear and/or abrasion resistance, can be used without departing from the scope of the invention. These include polyetherketoneketone (PEKK), polyetherketone (PEK), polyetherketoneetherketoneketone (PEKEKK), and polyetheretherketoneketone (PEEKK), and generally a polyaryletheretherketone. Further other polyketones can be used as well as other thermoplastics. Reference to appropriate polymers that can be used in the tools or tool components can be made to the following documents, all of which are incorporated herein by reference. These documents include: PCT Publication WO 02/02158 A1, to Victrex Manufacturing Ltd. entitled Bio-Compatible Polymeric Materials; PCT Publication WO 02/00275 A1, to Victrex Manufacturing Ltd. entitled Bio-Compatible Polymeric Materials; and PCT Publication WO 02/00270 A1, to Victrex Manufacturing Ltd. entitled Bio-Compatible Polymeric Materials. Still other materials such as Bionate®, polycarbonate urethane, available from the Polymer Technology Group, Berkeley, Calif., may also be appropriate because of the good oxidative stability, biocompatibility, mechanical strength and abrasion resistance. Other thermoplastic materials and other high molecular weight polymers can be used as well for portions of the instrument that are desired to be radiolucent. 
     Moreover, the outer exoskeleton structure, or sheath, may be a hybrid of metal components to accommodate the interdigitation features or die tubular part of the exoskeleton. 
     In still other embodiments, the device or components can be coated with therapeutic agents or can be configured from polymers with therapeutic agents incorporated therein. 
     The device may be of a variety of lengths and diameters. The length and diameter of the device may be determined by the fracture site and patient anatomy and physiology considerations. The length must traverse the fracture across its angularity to the internal diameter. The diameter ranges from the minimum to the maximum internal diameter for the space. Though not restricted to these values, the length may vary from 1000 mm to 1 mm and the diameter may range from 0.1 mm to 100 mm. These interdigitation features are designed to penetrate 25 to 75% of the cortical bone at the site of the fracture. The designs of the device allow for a multiple lengths of interdigitation in different devices and within the same device. 
     The interdigitation features, upon full deployment, may be configured to open out and into the surrounding bone to hold in place the fragments of the fractured bone. This can be achieved with the use of an inner sleeve  4901  as shown in  FIG. 49 . In one embodiment of the present invention, the cross bone fracture stabilization assembly may be removed after a predetermined period of time during which the bone at the fractured site has substantially and completely healed. The inner sleeve  4801  as shown in  FIG. 48  is then removed and the guide wire  4802  may be used to remove the cross bone fracture stabilization assembly  4803  in one embodiment. Alternatively, within the scope of the present invention, the cross bone fracture stabilization assembly may be permanently positioned within the space so as to remain integrally intact with the bone tissues substantially at the fractured site. 
     As will be appreciated by those skilled in the art, the device can be configured such that an outer sleeve is removable upon deployment of the interdigitation feature (e.g. expansion of the teeth away from the central axis). In another embodiment, the inner sleeve  5001  as shown in  FIG. 50  can be removed causing the teeth  5002  to collapse inward toward the central axis of the outer exoskeleton or sheath  5003 . In an embodiment according to this design, the device to bone connective force would be eliminated upon removal of the inner sleeve. The teeth of exoskeleton or sheath either retract back towards the central axis of the device or upon pulling the device towards the proximal opening in the bone, the teeth disengage from the bone. This allows facile removal of the device. In one embodiment, the outer exoskeleton or sheath may be removed by applying a force opposite in direction away from the outer exoskeleton. 
     While the description above relates to cross bone deployment, this stabilization device is suitable to communicate anatomical forces across any areas of weakened bone. The location of the weakened bone is identified by suitable diagnosis. The cross bone stabilization device  5101  as shown in  FIG. 51  within the scope of the present invention may be deployed across the region of weakened bone. Within the scope of the present invention, the cross bone stabilization device may be made from large diameter for long bones or very small sizes for bones of the hand or foot. The diameter and length of the device are designed for fixation of the bone internally. 
     After positioning the reinforcement device at the desired location within the space so as to substantially be in contact, with the bone fracture, using a K-wire driver  5201  as shown in  FIG. 52 , the bone fragments are attached to the reinforcement device  5202  that is fully deployed, properly positioned within the space and structurally expanded to substantially fill the space where it is positioned. K-wires  5203 , i.e., thin, rigid wires, can be used to stabilize bone fragments. These wires can be drilled through the bone to hold the fragments in place. As would be appreciated by those skilled in the art, the k-wires can also be placed percutaneously (through the skin). 
     More specifically, upon complete removal of the introducer described above from the central aperture, the bone fragments can be attached to the device by K-wires deployed using a K-wire driver so that the fragments are substantially and properly aligned with the bone structure guided by the reinforcement device during the recuperation process. Furthermore, optionally, bone cement, allographic bone, harvested bone, cadaver bone or other suitable bony matrices maybe introduced into the space after removing the introducer to substantially fill the space from the incision site to the reinforcement device. Moreover, prior to closing the incision site, a bone plug may be deployed at the opening of the space of the bone to substantially seal the bony matrix and/or to seal the space. 
     After the device has been implanted according to any of the techniques described herein, the incision site is closed with stitches, for example, to allow the fracture, and the fragments to heal. 
     In another embodiment of the device includes a plurality of independent structural members with inner or outer position across weakened or fractured bone. Though each independent structural member is placed uniquely in bone additional wires, threads, sutures may tie these together across bone so that the plurality of structural members are linked and form a rigid construction that resists anatomical and typical patient loading and forces. In  FIG. 53  are shown examples  5301 ,  5302 ,  5303  and  5304  of independent structural members connected by high tensile strength connective members. With this construction, very small reinforcement and fixation devices may be constructed in situ. 
     In similar construction an expandable device  5401  as shown in  FIG. 54  is envisioned whereby the interdigitating interface to bone lies proximal and distal to the plurality of bars, rods, or other members that tie together both ends. 
     In another example, the upper trochanteric region of the bone or other region of the musculo-skeletal system may be exposed and a hole may be cored out of the femoral neck  5501  as shown in  FIG. 55 . The reinforcement device (e.g., made of nitinol) is then delivered to the bore and expanded to fill the outside diameter of the hole  5601  as shown in  FIG. 56 . The inner diameter of the reinforcement device may be filled and pressurized with the bone cement. Alternatively, the inner diameter of the reinforcement device may be filled with the excised bone, bone plug or allographic bone  5602 . 
     A corollary embodiment of the previously described art include axial translation from distal to proximal ends of the device thereby drawing bone and tissue together through shortening the axial distance distal to proximal. These embodiments have specific applications in fracture non-unions, joint fusions and certain fractures. 
     The devices disclosed herein can be deployed in a variety of suitable ways, as would be appreciated by those skilled in the art. For example, a provisional closed reduction of the fracture can be performed wherein a 1.5 to 2 inch incision is made overlying the metaphyseal prominence of the bone. Blunt dissection is then carried to the fascia whereupon the fascia is incised. The surgical approach to the central aspect (anterior-posterior) proceeds by either splitting the tendon or ligament or muscle longitudinally or by elevating structures of the bone in a subperiosteal fashion. The choice of the particular approach varies with respect to the fractured bone that is being treated. A specialized soft tissue retractor is placed onto the bone retracting the soft tissues away from the entry point of the bone. 
     A guide wire can then be drilled at an angle into the insertion point along the metaphyseal prominence. The angle of placement of the guide wire along the longitudinal axis of the bone depends on the fracture anatomy and particular bone being treated. The guide wire can then be placed under fluoroscopic guidance. An optimally chosen reamer is introduced over the guide wire opening the metaphyseal entry point. Both devices are then removed. 
     A curved guide wire is introduced across the open channel of the metaphysis and is advanced across the fracture site into the diaphysis of the bone. Sequential reaming appropriate for the particular device is performed to prepare the diaphysis. The distance from the fracture site to the entry point is estimated under fluoroscopy and the appropriate device is selected. The reamer is withdrawn and the device is introduced across the guide wire into the metaphysis and across the fracture into the diaphysis. Fluoroscopy confirms the location of the universal joint at the metaphyseal/diaphyseal fracture site. 
     The diaphyseal teeth of the device are deployed and the device is rigidly fixed to the diaphysis of the fractured bone distal to the fracture site. Any extension of the fracture into the joint can now be reduced in a closed fashion and held with K wires or in an open fashion via a dorsal approach to the intra-articular portion of the fracture. Metaphyseal locking flanges with targeting outriggers attached are now advanced (in to the metaphyseal bone) across the metaphyseal shaft. Using the attached targeting outrigger, guidewires are now placed through the metaphyseal locking flanges. The guidewires are directed fluoroscopically to stabilize the intra-articular portion of the fracture and/or to stabilize the metaphyseal fracture securely. Holes are drilled over the guidewires with a cannulated drill bit. Then, self tapping screws are advanced over the guidewires to lock the bone to the shaft and metaphyseal locking flange. The device is now locked within the proximal and distal bone fragments (metaphyseal or diaphyseal) and distal (diaphyseal) bone. This provides for rigid fixation of the comminuted intra-articular fragments to each other, and the fixation between these screws interlocking in to the metaphyseal flange component provides rigid fixation of these intra-articular fragments in the metaphyseal region to the diaphyseal shaft as well. The extremity and fracture is now manipulated until a satisfactory reduction is achieved as visualized under fluoroscopy. Thereafter, the fracture is manipulated under fluoroscopic guidance in order to achieve anatomic alignment of the bone fragments. Once optimal intramedullary reduction is achieved, the universal joint is locked. The fracture is now fixed securely. The guide wire is removed and the wound is closed repairing the periosteum over the metaphyseal entry point and repairing the fascia and closing the skin. A splint maybe applied. 
     While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.