Abstract:
A distraction device that allows for an improved use of the existing process of distraction osteogenesis. The distraction device facilitates the displacement of a healthy portion of bone to a deficient area to enable bone and soft tissue growth in a fracture gap and allows for both vertical and angular bone regeneration.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/668,818, filed Apr. 6, 2005. U.S. Provisional Application No. 60/668,818 is hereby incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a device for regenerating bone in a patient, particularly for use in a distraction osteogenesis method. Specifically, the present invention relates to an improved device that facilitates angled and vertical bone regeneration in the oral cavity, allowing for bone growth in a direction that is not necessarily vertical to the device. 
       BACKGROUND OF THE INVENTION 
       [0003]    During the 1950&#39;s, Professor Gavril Ilizaroz revealed that controlled, mechanically applied tension stress on fractured bone produces successful regeneration of bone and soft tissue, a technique known today as distraction osteogenesis. Initially used for the treatment of fractures and non-unions, his methods have proven successful for limb lengthening and bone transportation. 
         [0004]    Today, distraction osteogenesis is used to lengthen long bones, correct bone deformities, correct maxillofacial abnormalities, and treat periodontal bone deficiency. Generally, distraction osteogenesis involves making small bone cuts at precise positions and applying forces across these cuts using a distraction device to induce and direct normal bone formation. 
         [0005]    More specifically, a typical procedure for distraction osteogenesis involves the following four sequentially performed stages: osteotomy, latency, distraction, and consolidation. The first stage, osteotomy, involves cutting a section of a bone requiring treatment into two pieces, known as a controlled fracture, thus initiating the fracture&#39;s natural healing process. Fracture healing is a process whereby fibrous deformable tissue forms and is gradually replaced by non-deformable tissue (i.e., ossification). 
         [0006]    The second stage, latency, is a “rest” period (e.g., approximately 5-7 days), during which healing of the fracture proceeds until a blood clot is formed. Upon formation of the blood clot, the distraction stage begins. Distraction is a process wherein bony fragments or joint surfaces of a limb are separated or otherwise spread by extension. During distraction, a “gap” is created at the site of the osteotomy. Following formation of the appropriately sized gap, a consolidation stage, or period of healing, occurs. 
         [0007]    During the distraction stage, conventional devices are employed to control and direct the bone distraction. However, conventional distraction devices for intra-oral distraction facilitate bone regeneration in only a vertical direction. Because bone geometries vary from patient to patient and include overlaps and non-vertical angles, vertical regeneration alone does not provide the necessary treatment option for many patients. 
         [0008]    Accordingly, there is a need for a distraction device that allows for improved regeneration of bone, particularly in the oral cavity. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention relates to a distraction device and a method for facilitating angled and vertical bone regeneration in the oral cavity. The device is particularly suited for use by oral surgeons, periodontists, plastic surgeons, and maxilla specialists in the treatment of traumatic injury, cancer, tumor ablation, or growth disharmony, such as those affecting the temporo-mandibular joint (TMJ). The distraction device facilitates the displacement of a healthy portion of bone to a deficient area to allow for bone regeneration and soft tissue growth. Advantageously, the distraction device allows for both vertical and angular bone regeneration by facilitating both vertical and angular distraction. 
         [0010]    The distraction device according to an embodiment of the present invention may be used to regenerate bone tissue in deficient areas of a patient&#39;s upper and/or lower jaw bones (i.e., the maxilla and/or mandible bones) to allow for subsequent dental implantation. According to an aspect of the present invention, the distraction device includes multi-tooth capabilities based on a patient&#39;s needs. One having ordinary skill in the art will appreciate that the distraction device may be used for vertical and angular bone regeneration in other areas of the body and is not limited to intra-oral use. 
         [0011]    According to an embodiment of the present invention, the distraction device includes a threaded rod with a connecting wedge housing at one end, a threaded nut for engaging with the threaded rod, two lower transport plates for positioning on either side of a lower portion of the threaded rod, an upper transport plate for securing an upper portion of the threaded rod, and one or more connecting wedges adapted to fit in the distraction device. 
         [0012]    Each connecting wedge includes a main body and a connecting-wedge extension extending from each side of the main body. The main body of the connecting wedge is offset relative to the connecting-wedge extensions at an angle, referred to as an “offset angle.” The term “wedge” is intended to include, but is not limited to, any structure, device, piece, component, etc. having any suitable shape or size such that it is adapted to provide an offset angle as described herein. As such, the term “wedge” may not be limited to any conventional definition, particular shape, and/or geometric configuration. 
         [0013]    In operation, the two lower transport plates are fixed to a healthy portion of bone or tissue adjacent an area of bone deficiency according to a technique known in the art. An upper transport plate is secured to the site of an osteotomy with a securing mechanism, such as for example standard bone screws. The upper transport plate includes a sleeve through which the threaded rod is passed, thereby releasably coupling the upper transport plate and the threaded rod. The threaded nut is engaged on the threaded rod and may be moved to shift the upper transport plate and adjust a vertical component of the distraction (i.e., the vertical distraction). 
         [0014]    The main body of the connecting wedge is fitted within the connecting wedge housing of the threaded rod. With the main body securely attached to the threaded rod, the connecting wedge extensions are engaged within the lower transport plates, and the threaded rod is stabilized by the lower transport plates. Further, when the threaded rod, the connecting wedge, and the lower transport plates are assembled, the threaded rod extends at an angle that is offset relative to the lower transport plates. That is, the threaded rod and the lower transport plates form an angular relationship that is not necessarily parallel or perpendicular. The angular arrangement of the threaded rod relative to the lower transport plates allows for angular distraction and angular bone regeneration. 
         [0015]    In another embodiment of the present invention, the distraction device includes a threaded rod engaged within a correspondingly threaded hub. The distraction device also includes a shaft that passes horizontally through the hub, wherein each end of the shaft extending out of the sides of the hub are secured by a lower transport plate. The threaded rod, the hub, and the shaft combine to form a setscrew. When rotated in a clockwise direction, the threaded rod moves in a downward direction within the hub and into contact with the shaft. When sufficient contact between the threaded rod and the shaft is established, the threaded rod and the hub are prevented from rotating about the shaft, and the distraction device is in a locked position. 
         [0016]    Correspondingly, when the threaded rod is turned in a counter-clockwise direction, the threaded rod moves in an upward direction and out of contact with the shaft, placing the distraction device in an unlocked position. In the unlocked position, the threaded rod and hub are free to rotate about the shaft and may be positioned at an angle relative to the lower transport plates. When the desired angle of the threaded rod (i.e., the desired angle of bone regeneration) has been assigned, the angle may be set by turning the threaded rod in the clockwise direction to place the distraction device in the locked position. Advantageously, the distraction device allows for the angle of regeneration to be adjusted at any time during the distraction procedure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0017]    The present invention will be more readily understood from the detailed description of the preferred embodiment(s) presented below considered in conjunction with the attached drawings, of which: 
           [0018]      FIG. 1  is an isometric view of a distraction device, according to an embodiment of the present invention; 
           [0019]      FIG. 2  is a rear view of a distraction device, according to an embodiment of the present invention; 
           [0020]      FIG. 3  is a side view of a distraction device, according to an embodiment of the present invention; 
           [0021]      FIG. 4  is an isometric view of a connecting wedge, according to an embodiment of the present invention; 
           [0022]      FIG. 5  is a side view of a connecting wedge, according to an embodiment of the present invention; 
           [0023]      FIG. 6  is an exploded view of a distraction device, according to an embodiment of the present invention; 
           [0024]      FIG. 7  depicts an exemplary connecting wedge having an offset angle of 0° and a distraction device including the exemplary connecting wedge, according to an embodiment of the present invention; 
           [0025]      FIG. 8  depicts an exemplary connecting wedge having an offset angle of 10° and a distraction device including the exemplary connecting wedge, according to an embodiment of the present invention; 
           [0026]      FIG. 9  is an isometric illustration of a distraction device, according to an embodiment of the present invention; 
           [0027]      FIG. 10  depicts an exemplary hub, according to an embodiment of the present invention; and 
           [0028]      FIG. 11  depicts an exemplary shaft, according to an embodiment of the present invention. 
       
    
    
       [0029]    It is to be understood that the attached drawings are for the purpose of illustrating concepts of the present invention and may not be to scale. 
       DETAILED DESCRIPTION OF THE INVENTION  
       [0030]    The present invention relates to a distraction device for facilitating both vertical and angular bone regeneration, particularly in the oral cavity. 
         [0031]      FIGS. 1 ,  2 ,  3 , and  6  depict an exemplary distraction device  100  according to an embodiment of the present invention. The distraction device  100  includes a threaded rod  1 , a threaded nut  4  disposed on the threaded rod  1 , an upper transport plate  2 , one or more lower transport plates  3 A,  3 B, and a connecting wedge  5 . At one end of the threaded rod  1  is a connecting wedge housing  11  that includes an opening  12  shaped and sized to fit the connecting wedge  5 , as described in detail below. In a preferred embodiment, the threaded rod  1  is composed of M0.5×3 standard isometric threads. 
         [0032]    According to an embodiment of the present invention, the one or more lower transport plates  3 A,  3 B are adapted to be secured or attached to a healthy portion of a patient&#39;s bone and/or tissue surrounding the area of bone deficiency, referred to as a target area. For example, if the mandible is the target area, the one or more lower transport plates  3 A,  3 B are fixed below the target bone. In another example, if the maxilla is the target area, the one or more lower transport plates are fixed above the target area. One having ordinary skill in the art will appreciate that the lower transport plates  3 A,  3 B may be secured proximal to the target area by any suitable fastening mechanism or method, including, but not limited to, a screw assembly. 
         [0033]    According to a preferred embodiment, two lower transport plates  3 A,  3 B are employed. Although the distraction device  100  is described as preferably including two lower transport plates  3 A,  3 B, one having ordinary skill in the art will appreciate that any number of lower transport plates may be employed, with an important consideration being that the lower portion of the distraction device  100  is adequately secured in place. 
         [0034]    The lower transport plates  3 A,  3 B each include one or more holes  7 , as shown in  FIG. 2 . Each hole  7  is adapted to accept a screw or similar securing mechanism for affixing the lower transport plates  3 A,  3 B to the area adjacent the target area. Preferably, the lower transport plates  3 A,  3 B are arranged relatively coplanar to each other. 
         [0035]    The upper transport plate  2  is fixed at or near a target area (e.g., the site of an osteotomy) by one or more bone screws passing through one or more holes  6  of the upper transport plate  2 , as shown in  FIG. 2 . The upper transport plate  2  includes a sleeve  15  with an opening sized and shaped to surround the threaded rod  1 . As shown in  FIGS. 1 ,  2 , and  6 , the threaded rod  1  is releasably coupled to the upper transport plate  2 , by passing the threaded rod  1  through the sleeve  15  of the upper transport plate  2 , such that the threaded rod  1  acts as a transport vector for the bone distraction. One having ordinary skill in the art will appreciate that the threaded rod  1  and the upper transport plate  2  may be releasably coupled to one another according to any suitable means or mechanism. One having ordinary skill in the art will appreciate that the upper transport plate  2  and the lower transport plates  3 A,  3 B may be manufactured using any known method, such as, for example, a machining method, a die casting method, or a Computer Numerical Control (CNC) method. 
         [0036]    Disposed on the threaded rod  1  is the threaded nut  4 . The threaded nut  4  is threadably engaged on the threaded rod  1  such that the threaded nut  4  is able to move axially along the threaded rod  1  upon the application of a force. To adjust an amount of vertical distraction provided by the distraction device  100 , a user turns the threaded nut  4  thus causing the threaded nut  4  to move into contact with the upper transport plate  2  and shift the upper transport plate  2  in the desired direction by the desired amount. Because the interior surface of the sleeve  15  is not threaded, the osteotomy moves longitudinally, in parallel with the threaded rod  1 . 
         [0037]    In a preferred embodiment, the threaded nut  4  may be turned using a suitable tool, such as for example a small hexagonal wrench. In an exemplary configuration, the threaded rod  1  includes threads having a pitch of approximately 0.5 mm. According to this exemplary arrangement, the user may turn the threaded nut  4  one complete turn twice a day in order to shift the upper transport plate  2  a total distance of approximately 1 mm a day. Although the threaded nut  4  and the threaded rod  1  are described as engaged by a threaded connection, alternative arrangements for disposing the threaded nut  4  on the threaded rod  1  are contemplated, such that the threaded nut  4  is movable along the threaded rod  1 . 
         [0038]      FIGS. 4 and 5  depict an exemplary connecting wedge  5  according to an embodiment of the present invention. The connecting wedge  5  attaches the lower transport plates  3 A,  3 B to the threaded rod  1 , and also provides a mechanism for setting the angle of the threaded rod  1  relative to the lower transport plates  3 A,  3 B. According to an embodiment of the present invention, the connecting wedge  5  includes a main body  9  and two connecting wedge extensions  10 A,  10 B extending from opposing sides of the main body  9 . Preferably, both the main body  9  and the connecting wedge extensions  10 A,  10 B have a rectangular shape, as shown in  FIG. 4 . One having ordinary skill in the art will appreciate that the main body  9  and the connecting wedge extensions  10 A,  10 B may be integrally formed as a single piece. 
         [0039]    The main body  9  of the connecting wedge  5  is offset relative to the connecting wedge extensions  10 A,  10 B at a particular angle, referred to as an “offset angle,” graphically represented by the symbol “θ” in  FIG. 8 . One having ordinary skill in the art will appreciate that the connecting wedge  5  may be configured to have any desired offset angle. One having ordinary skill in the art will appreciate that each connecting wedge  5  may be configured such that the relative arrangement of the main body  9  and the connecting wedge extensions  10 A,  10 B is adjustable (i.e., the position of the main body  9  and/or the connecting wedge extensions  10 A,  10 B may be made changed to set a new offset angle.) For example, the connecting wedge extensions  10 A,  10 B may be adapted to rotate relative to the main body  9 , to adjust the offset angle provided by the connecting wedge  5 . 
         [0040]    An exemplary connecting wedge  5  having an offset angle of 10° (i.e., the main body  9  is offset relative to the connecting wedge extensions  10 A,  10 B at an angle of 10°) is shown in  FIG. 8 . 
         [0041]    One having ordinary skill in the art will appreciate that the distraction device  100  according to an embodiment of the present invention may be adapted to fit any one of a collection of interchangeable connecting wedges  5 , each having a particular offset angle. Further, it is to be appreciated that the main body  9  may be any shape or size, with an important consideration being that the main body  9  fits securely within the opening  12  of the connecting wedge housing  11  and is adapted for arrangement relative to the connecting wedge extensions  10 A,  10 B to produce an offset angle. 
         [0042]    Each lower transport plate  3 A,  3 B includes an opening  8 A,  8 B that extends perpendicularly to the surface of the target area, as shown in  FIGS. 3 and 6 . The opening  8 A,  8 B are adapted to accept and secure the connecting wedge extension  10 A,  10 B. The openings  8 A,  8 B of the lower transport plates  3 A,  3 B have the same shape as the connecting wedge extensions  10 A,  10 B. Preferably, the openings  8 A,  8 B and the connecting wedge extensions  10 A,  10 B are square-shaped. 
         [0043]    The distraction device  100  is assembled by fitting the main body  9  into the opening  12  of the connecting wedge housing  11  and engaging the connecting wedge extensions  10 A,  10 B within the openings  8 A,  8 B of the lower transport plates  3 A,  3 B, respectively, thus holding the threaded rod  1  and the lower transport plates  3 A,  3 B together. Further, an upper portion of the threaded rod  1  is secured by the upper transport plate  2 , as described above. Advantageously, the distraction device  100  is stabilized by the lower transport plates  3 A,  3 B and the surrounding soft tissue of the region adjacent the target area, thus preventing any separation of the components of the distraction device  100  while in situ. 
         [0044]    The offset angle of the connecting wedge  5  dictates the angle at which the threaded rod  1  extends relative to the lower transport housings  3 A,  3 B, and thus provides the angle of bone regeneration provided by the distraction device  100 .  FIG. 7  depicts an exemplary connecting wedge  5  with an offset angle θ of approximately 0° (i.e., the main body  9  is not offset relative to the connecting wedge extensions  10 A,  10 B). Accordingly, when the connecting wedge  5  depicted in  FIG. 7  is loaded into the distraction device  100 , there is an approximately 0° offset angle between the lower transport plates  3 A,  3 B and the threaded rod  1 . Thus, the distraction device  100  according to this exemplary arrangement provides an approximately 0° angle of angular bone regeneration. 
         [0045]      FIG. 8  depicts an exemplary connecting wedge  5  with an offset angle θ of 10°. Accordingly, when the connecting wedge  5  shown in  FIG. 8  is loaded into the distraction device  100 , the threaded rod  1  extends at a 10° angle relative to the lower transport plates  3 A,  3 B. Thus, the distraction device  100  according to this exemplary arrangement facilitates bone regeneration at a 10° angle. 
         [0046]    Advantageously, each connecting wedge  5  may be configured at a different offset angle, to allow a user to select from a wide range of angles for angular bone regeneration, depending on the individual patient&#39;s needs. The distraction device  100  may be fitted with any one of a collection of connecting wedges  5  depending on the angle of angular bone regeneration desired. 
         [0047]    One having ordinary skill in the art will appreciate that the distraction device  100  may be composed of any suitable material, such as for example titanium or surgical-grade stainless steel. Preferably, the distraction device  100  may be fabricated using known CNC technology. 
         [0048]      FIG. 9  illustrates a distraction device  100  according to another embodiment of the present invention. As shown in  FIG. 9 , the distraction device  100  includes an upper transport plate  2  adapted to be secured the site of an osteotomy. As described above, the upper transport plate  2  includes a sleeve  15  with an opening sized and shaped to surround the threaded rod  1 . 
         [0049]    According to this embodiment of the present invention, the distraction device  100  includes a threaded nut  4  engaged on a threaded rod  1 , as described in detail above. As described above, the threaded nut  4  may be turned to shift the upper transport plate  2  to allow for vertical adjustment of the distraction device  100 . As such, the threaded rod  1  acts as a transport vector for bone distraction. As described above, two lower transport plates  3 A,  3 B are secured to a healthy portion of the patient&#39;s bone or tissue proximal to the target area. The lower transport plates  3 A,  3 B each include a sleeve adapted to accept and secure the ends of a shaft  50 . 
         [0050]    The distraction device  100  includes a hub  30  positioned between the lower transport plates  3 A,  3 B. The hub  30  includes an opening in its top and a threaded interior surface for insertion and engagement of the threaded rod  1 , as shown in  FIG. 10 . The hub  30  also includes an opening on each side that aligns with the openings of the lower transport plates  3 A,  3 B to allow for insertion of the shaft  50 , shown in  FIG. 11 . When assembled, the center portion of the shaft  50  is arranged within the hub  30  and the ends of the shaft  50  are held on either side by the lower transport plates  3 A,  3 B, such that the threaded rod  1  and the shaft  50  are substantially perpendicular to each other, as shown in  FIG. 9 . The threaded rod  1 , the hub  30 , and the shaft  50  combine to form a setscrew for adjustment of the angle of the threaded rod  1  relative to the lower transport plates  3 A,  3 B, which in turn dictates the distraction angle. 
         [0051]    A knob  20 , or other equivalent structure, is positioned at an end of the threaded rod  1  and is used to adjust the position of the threaded rod  1 . In operation, the knob  20  may be turned in a clockwise direction to cause the threaded rod  1  to move downwardly into the hub  30  until the threaded rod  1  makes contact with the shaft  50 . When the threaded rod  1  is moved into sufficient contact with the shaft  50 , the hub  30  and threaded rod  1  are prevented from rotating about the shaft  50 , thus placing the distraction device  100  in a locked position at the desired distraction angle. 
         [0052]    Turning the knob  20  of the threaded rod  1  in a counter-clockwise direction moves the threaded rod  1  out of contact with the shaft  50 , thus placing the device  100  in an unlocked position. In the unlocked position, the threaded rod  1  and hub  30  may be rotated about the shaft  50  to a desired distraction angle. As described above, while maintaining the desired angle, the user may turn the knob  20  in a clockwise direction causing the threaded rod  1  to rotate into contact with the shaft  50 , thus setting the distraction device  100  in a locked position at the desired distraction angle. Advantageously, this embodiment of the present invention allows for in situ adjustment of the angle of regeneration provided by the distraction device  100 . The distraction device  100  according to this embodiment of the present invention allows for the angle of regeneration to be adjusted at any time during the distraction procedure. 
         [0053]    Although the present invention has been described in considerable detail with reference to certain preferred embodiments and version, other versions and embodiments are possible. Therefore, the scope of the present invention is not limited to the description of the versions and embodiments expressly disclosed herein. The references and disclosure provided in the ‘Background of the Invention’ section are not admitted to be prior art with respect to the disclosure provided in the present application.