Abstract:
Provided are an artificial bone constructing unit which is capable of being built into a free shape according to build-up design, and effectively guiding bone replacement, and an artificial bone system. Specifically disclosed are an artificial bone constructing unit and an artificial bone constructing system, wherein in principal, the artificial bone constructing unit which constructs an artificial bone is so made into a block shape that when blocks are assembled, continuous holes through a plurality of blocks are formed.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an artificial bone constituent unit capable of being assembled into a shape appropriate for a living body and effectively guiding bone replacement and an artificial bone constituent system. 
       BACKGROUND ART 
       [0002]    Japanese Patent Application Laid-Open (JP-A) No. 11-19104 (Patent Document 1) discloses an artificial bone prosthesis. The artificial bone prosthesis has a guide groove for splitting and can be divided into an appropriate size by being split along the guide groove. Though the artificial bone prosthesis can be changed in shape to a certain extent, the flexibility of such a change is limited. Thus, the artificial bone prosthesis cannot build an artificial bone in an appropriate shape. 
       PRIOR ART DOCUMENT 
     Patent Document 
       [0000]    
       
         Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 11-19104 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    Therefore, an object of the present invention is to provide an artificial bone constituent unit capable of being assembled into a shape appropriate for a living body by a buildup design and effectively guiding bone replacement and an artificial bone constituent system. 
       Solution to Problem 
       [0005]    The present invention is basically based on findings that the above problem can effectively be solved by blocking artificial bone constituent units forming an artificial bone. 
         [0006]    A first aspect of the present invention relates to an artificial bone constituent unit  1 . The artificial bone constituent unit  1  is used as an artificial bone  3  by assembling a plurality of units thereof into an intended shape. The artificial bone  3  is also called a bone prosthetic agent or a bone filler. The artificial bone constituent unit  1  has a body portion  7  including a first hole  5 . The body portion  7  has connecting portions  9 ,  11 . The connecting portions  9 ,  11  are used to connect the artificial bone constituent unit  1  to one or a plurality of the other artificial bone constituent units  13 ,  15 . Because of the above configuration, the artificial bone  3  in a desired shape can be obtained by assembling the plurality of the artificial bone constituent units  1 . 
         [0007]    In a preferred mode of the first aspect, the first hole  5  communicates with holes  17 ,  19  in other artificial bone constituent units  13 ,  15  connected to the artificial bone constituent unit  1 . Therefore, due to the presence of a continuous hole throughout a plurality of blocks, it becomes easier for body tissues including blood vessel to enter an artificial bone. Accordingly, the artificial bone will effectively replace bone tissues. 
         [0008]    In a preferred mode of the first aspect, the diameter of the first hole  5  is 0.1 mm or more and 1 cm or less. With the presence of a hole in this size, an optical amount of body tissues enters an artificial bone. Accordingly, the artificial bone will effectively replace bone tissues. 
         [0009]    In a preferred mode of the first aspect, the body portion  7  further has a second hole  21  and a third hole  23 . The second hole  21  is perpendicular to the first hole  5 . The third hole  23  is perpendicular to the first hole  5  and the second hole  21 . With the presence of such holes in various directions, body tissues effectively enter an artificial bone. Accordingly, the artificial bone will effectively replace bone tissues. 
         [0010]    In a preferred mode of the first aspect, the body portion  7  is a block in a hexahedral structure. Because the artificial bone constituent unit  1  has such a shape, the unit can freely be designed into the shape of an artificial bone. 
         [0011]    In a preferred mode of the first aspect, the body portion  7  is an isosceles trapezoidal column. Because the artificial bone constituent unit  1  has such a shape, the unit can freely be designed into the shape of an artificial bone. 
         [0012]    In a preferred mode of the first aspect, the body portion  7  is a column and the cross section of the column is a portion of a ring. Because the artificial bone constituent unit  1  has such a shape, the unit can freely be designed into the shape of an artificial bone. 
         [0013]    In a preferred mode of the first aspect, the body portion  7  is a polygonal column (for example, a regular triangular prism or a regular hexagonal prism). Because the artificial bone constituent unit  1  has such a shape, an artificial bone in various shapes can be designed by combining a plurality of artificial bone constituent units. 
         [0014]    In a preferred mode of the first aspect, the body portion  7  is a regular triangular prism. Because the artificial bone constituent unit  1  has such a shape, an artificial bone suitable for a bone lacking region having a spherical structure such as the cranial bone can be designed. 
         [0015]    In a preferred mode of the first aspect, the body portion  7  has a first groove  24  on the surface thereof. Because the artificial bone constituent unit  1  has the groove  24 , an adhesive can easily be injected so that the connection of artificial bone constituent units can be made stronger. 
         [0016]    In a preferred mode of the first aspect, the connecting portions  9 ,  11  further have second grooves  25 ,  26 . When connected to another artificial bone constituent unit, the grooves  25 ,  26  fit in with grooves of the other artificial bone constituent unit to form a hole. Cells and blood vessel enter the formed hole. Accordingly, the connection between artificial bone constituent units becomes stronger. 
         [0017]    In a preferred mode of the first aspect, the connecting portions  9 ,  11  are a convex portion  27  or a concave portion  28 . The convex portion  27  or the concave portion  28  of the artificial bone constituent unit  1  fits into a concave portion  29  or a convex portion  31  of the other connected artificial bone constituent units  13 ,  15  respectively. The artificial bone constituent unit  1  in this mode is connected to the other artificial bone constituent units  13 ,  15  via the convex portion  27  or the concave portion  28 . 
         [0018]    In a preferred mode of the first aspect, the body portion  7  is an isosceles trapezoidal column. The artificial bone constituent unit  1  in this mode is provided with the connecting portions  9 ,  11  at least on isosceles side faces  33 ,  35  of the body portion  7 . The artificial bone constituent unit  1  in this mode is connected to one or a plurality of the other artificial bone constituent units  13 ,  15  via the isosceles side faces. 
         [0019]    A second aspect of the present invention relates to an artificial bone constituent system including the artificial bone constituent unit described above. This system is an artificial bone constituent system  40  including a plurality of artificial bone constituent units. The artificial bone constituent system  40  has at least a first artificial bone constituent unit group  41  and a second artificial bone constituent unit group  61 . The first artificial bone constituent unit group  41  and the second artificial bone constituent unit group  61  have a plurality of first artificial bone constituent units  42  and a plurality of second artificial bone constituent units  62  respectively. 
         [0020]    The first artificial bone constituent unit  42  has a body portion  44 , first connecting portions  47 ,  48 , and second connecting portions  51 ,  52 . The body portion  44  is a portion that has a first hole  43  and a hexahedral structure. The first connecting portions  47 ,  48  are portions mounted on a left side face  45  and a right side face  46  of the body portion  44 . The second connecting portions  51 ,  52  are portions mounted on a front  49  and a rear face  50  of the body portion  44 . The first connecting portions  47 ,  48  are used to connect the first artificial bone constituent unit  42  to one or two artificial bone constituent units  53 ,  54  contained in the first artificial bone constituent unit group  41 . 
         [0021]    On the other hand, the second artificial bone constituent unit  62  has a body portion  64 , first connecting portions  67 ,  68 , and second connecting portions  71 ,  72 . The body portion  64  is a portion that has a first hole  63  and a hexahedral structure. The first connecting portions  67 ,  68  are portions mounted on a left side face  65  and a right side face  66  of the body portion  64 . The second connecting portions  71 ,  72  are portions mounted on a front  69  and a rear face  70  of the body portion  64 . The first connecting portions  67 ,  68  are used to connect the second artificial bone constituent unit  62  to one or two artificial bone constituent units  73 ,  74  contained in the second artificial bone constituent unit group  61 . 
         [0022]    In the artificial bone constituent system, the second connecting portion  51  of the first artificial bone constituent unit  41  is connected to the second connecting portion  72  of the second artificial bone constituent unit  62 . Accordingly, the first artificial bone constituent unit  42  and the second artificial bone constituent unit  62  are connected in the artificial bone constituent system. 
         [0023]    In a preferred mode of the second aspect, if one or two first artificial bone constituent units are connected to the first artificial bone constituent unit group  41  via one of the first connecting portions  47 ,  48  of the first artificial bone constituent unit  42 , the shape of a ring or a portion thereof is formed. Also in the artificial bone constituent system in this mode, if one or two second artificial bone constituent units are connected to the second artificial bone constituent unit group  61  via one of the first connecting portions  67 ,  68  of the second artificial bone constituent unit  62 , the shape of a ring or a portion thereof is formed. Also in the artificial bone constituent system in this mode, the shape of the body portion  44  of the first artificial bone constituent unit  42  and the body portion  64  of the second artificial bone constituent unit  62  is a shape in which the shape of a ring or a portion thereof by the first artificial bone constituent unit group  41  is positioned on an outer circumference of the shape of a ring or a portion thereof by the second artificial bone constituent unit group  61 . Accordingly, an artificial bone constituent system of the present invention can design an artificial bone by assembling artificial bone constituent unit like annual rings of a tree. 
         [0024]    A third aspect of the present invention relates to an artificial bone constituent system  80  having a plurality of first artificial bone constituent units  82  and a plurality of second artificial bone constituent units  102 . The first artificial bone constituent unit  82  has a body portion  88  and a connecting portion  92 . The body portion  88  is a portion that has a first hole  84  and a second hole  86  and has the shape of a regular triangular prism. The connecting portion  92  is a portion mounted on a side face  90 . The connecting portion  92  of the first artificial bone constituent unit  82  is used to connect to another first artificial bone constituent unit or the second artificial bone constituent unit  102 . 
         [0025]    The second artificial bone constituent unit  102  has a body portion  108  and a connecting portion  112 . The body portion  108  is a portion that has a first hole  104  and a second hole  106  and has the shape of a regular triangular prism. The connecting portion  112  is a portion mounted on a side face  110  of the body portion  108 . The connecting portion  112  is used to connect to the first artificial bone constituent unit  82  or another second artificial bone constituent unit. 
         [0026]    The connecting portion  92  of the first artificial bone constituent unit  82  is connected to the connecting portion  112  of the second artificial bone constituent units  102 , thereby connecting the first artificial bone constituent unit  82  and the second artificial bone constituent units  102 . According to an artificial bone constituent system of the present invention obtained in this manner, an artificial bone of the desired size can be obtained by appropriately assembling the first artificial bone constituent unit  82  and the second artificial bone constituent units  102  fitting to the size of a bone lacking region. An artificial bone obtained from an artificial bone constituent system of the present invention can suitably be used as a portion of a spherical structure such as the cranial bone. 
         [0027]    In a preferred mode of the third aspect of the present invention, an artificial bone constituent system further has a third artificial bone constituent unit  122 . The third artificial bone constituent unit  122  has a body portion  128  and a connecting portion  132 . The connecting portion  132  is a portion mounted on a side face  130  of the body portion  128 . The connecting portion  132  is used to connect to the first artificial bone constituent unit  82 , the second artificial bone constituent unit  102 , or the other third artificial bone constituent unit. Accordingly, in an artificial bone constituent system  120 , the first artificial bone constituent unit  82 , the second artificial bone constituent unit  102 , and the third artificial bone constituent unit  122  are connected. According to an artificial bone constituent system of the present invention obtained in this manner, an artificial bone of the desired size can be obtained by appropriately assembling the first artificial bone constituent unit  82 , the second artificial bone constituent unit  102 , and the third artificial bone constituent unit  122  fitting to the size of a bone lacking region. An artificial bone obtained from an artificial bone constituent system of the present invention can suitably be used as a portion of a spherical structure such as the cranial bone. 
       Advantageous Effects of Invention 
       [0028]    The present invention provides flexibility to the shape of an artificial bone by producing the artificial bone by assembling a plurality of artificial bone constituent units. Moreover, because a hole that is continuous throughout a plurality of blocks is present, body tissues including blood vessel enter the artificial bone. Accordingly, the artificial bone will effectively replace bone tissues. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0029]      FIG. 1  is a diagram showing an example of an artificial bone constituent unit.  FIG. 1A  is a perspective view of the artificial bone constituent unit.  FIG. 1B  is a left side view of the artificial bone constituent unit.  FIG. 1C  is a right side view of the artificial bone constituent unit.  FIG. 1D  is a top view of the artificial bone constituent unit.  FIG. 1E  shows a top view of an artificial bone obtained by assembling three artificial bone constituent units. 
           [0030]      FIG. 2  is a diagram showing a different example from the above example of the artificial bone constituent unit.  FIG. 2A  is a perspective view of the artificial bone constituent unit.  FIG. 2B  is a left side view of the artificial bone constituent unit.  FIG. 2C  is a right side view of the artificial bone constituent unit.  FIG. 2D  is a top view of the artificial bone constituent unit.  FIG. 2E  shows a top view when three artificial bone constituent units are assembled.  FIG. 2F  shows a perspective view of the artificial bone when three artificial bone constituent units are assembled. 
           [0031]      FIG. 3  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 3A  is a perspective view of the artificial bone constituent unit.  FIG. 3B  shows a perspective view of the artificial bone when three artificial bone constituent units are assembled. 
           [0032]      FIG. 4  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 4A  is a perspective view of the artificial bone constituent unit.  FIG. 4B  shows a perspective view of the artificial bone when three artificial bone constituent units are assembled. 
           [0033]      FIG. 5  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 5A  is a perspective view of the artificial bone constituent unit,  FIG. 5B  is a left side view of the artificial bone constituent unit.  FIG. 5C  is a right side view of the artificial bone constituent unit.  FIG. 5D  is a top view of the artificial bone constituent unit.  FIG. 5E  is a bottom view of the artificial bone constituent unit.  FIG. 5F  shows a perspective view of the artificial bone when artificial bone constituent units are assembled. 
           [0034]      FIG. 6  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 6A  is a perspective view of the artificial bone constituent unit.  FIG. 6B  is a perspective view of the artificial bone when artificial bone constituent units are assembled. 
           [0035]      FIG. 7  is a diagram showing another artificial bone constituent unit from the above ones.  FIG. 7A  is a perspective view of the artificial bone constituent unit.  FIG. 7B  is a left side view of the artificial bone constituent unit.  FIG. 7C  is a right side view of the artificial bone constituent unit.  FIG. 7D  is a top view of the artificial bone constituent unit.  FIGS. 7E and 7F  are perspective views of artificial bone constituent units with different sizes.  FIG. 7G  is a perspective view of an artificial bone  3  when artificial bone constituent units with different sizes are assembled. 
           [0036]      FIG. 8  is a diagram showing another artificial bone constituent unit from the above ones.  FIG. 7A  is a perspective view of the artificial bone constituent unit.  FIG. 7B  is a left side view of the artificial bone constituent unit.  FIG. 7C  is a right side view of the artificial bone constituent unit.  FIG. 7D  is a top view of the artificial bone constituent unit.  FIGS. 7E and 7F  are perspective views of artificial bone constituent units with different sizes.  FIG. 7G  is a perspective view of the artificial bone when artificial bone constituent units with different sizes are assembled. 
           [0037]      FIG. 9  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 9A  is a perspective view of the artificial bone constituent unit.  9 B is a front view of the artificial bone constituent unit.  FIG. 9C  shows a perspective view of the artificial bone when a plurality of artificial bone constituent units is assembled. 
           [0038]      FIG. 10  is a diagram showing an example of an artificial bone constituent system.  FIG. 10A  is a perspective view of the artificial bone constituent system.  FIG. 10B  is a perspective view showing a first artificial bone constituent unit.  FIG. 10C  is a top view of the first artificial bone constituent unit.  FIG. 10D  is a perspective view showing a second artificial bone constituent unit.  FIG. 10E  is a top view of the second artificial bone constituent unit. 
           [0039]      FIG. 11  is a diagram showing a different example from the above example of the artificial bone constituent system.  FIG. 11A  is a perspective view of the artificial bone constituent system.  FIG. 11B  is a perspective view showing the first artificial bone constituent unit.  FIG. 11C  is a left side view of the first artificial bone constituent unit.  FIG. 11D  is a top view of the first artificial bone constituent unit.  FIG. 11E  is a perspective view showing the second artificial bone constituent unit.  FIG. 11F  is a left side view of the second artificial bone constituent unit.  FIG. 11G  is a top view of the second artificial bone constituent unit. 
           [0040]      FIG. 12  is a diagram showing another artificial bone constituent system from the above ones. This artificial bone constituent system has a plurality of first artificial bone constituent units and a plurality of second artificial bone constituent units.  FIG. 12A  is a perspective view of the artificial bone constituent system.  FIGS. 12B and 12C  are perspective views of the first artificial bone constituent unit.  FIG. 12D  is a front view of the first artificial bone constituent unit.  FIGS. 12E and 12F  are perspective views of the second artificial bone constituent unit.  FIG. 12G  is a front view of the second artificial bone constituent unit. 
           [0041]      FIG. 13  is a diagram showing another artificial bone constituent system from the above ones. This artificial bone constituent system has, in addition to the first artificial bone constituent unit and the second artificial bone constituent unit described above, a third artificial bone constituent unit.  FIG. 13A  is a perspective view of the artificial bone constituent system.  FIGS. 13B and 13C  are perspective views of the third artificial bone constituent unit.  FIG. 13D  is a front view of the third artificial bone constituent unit. 
           [0042]      FIG. 14  is a photo, instead of a drawing, showing the artificial bone obtained by assembling artificial bone constituent units produced according to Example 1. 
           [0043]      FIG. 15  shows photos, instead of drawings, showing the artificial bone constituent units produced according to Example 2.  FIG. 15A  shows the artificial bone constituent unit in the shape of a portion of a ring.  FIG. 15B  shows the artificial bone constituent unit forming a portion of the outer circumference of a ring and the artificial bone constituent unit forming a portion of a ring therewithin. 
           [0044]      FIG. 16  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 16A  is a front view of the artificial bone constituent unit.  FIG. 16B  is a perspective view of the artificial bone constituent unit.  FIG. 16C  shows a front view of the artificial bone when a plurality of artificial bone constituent units is assembled. 
           [0045]      FIG. 17  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 17A  is a front view of the artificial bone constituent unit.  FIG. 17B  is a perspective view of the artificial bone constituent unit.  FIG. 17C  shows a front view of the artificial bone when a plurality of artificial bone constituent units is assembled. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0046]    The embodiments to carry out the present invention will be described below based on drawings.  FIG. 1  is a diagram showing an artificial bone constituent unit according to a first aspect of the present invention.  FIG. 1A  is a perspective view of an artificial bone constituent unit  1 .  FIG. 1B  is a left side view of the artificial bone constituent unit  1 .  FIG. 1C  is a right side view of the artificial bone constituent unit  1 .  FIG. 1D  is a top view of the artificial bone constituent unit  1 .  FIG. 1E  shows a top view of an artificial bone  3  obtained assembling three artificial bone constituent units. 
         [0047]    The artificial bone constituent unit  1  according to the first aspect of the present invention is used as an artificial bone by assembling a plurality thereof into an intended shape. 
         [0048]    The artificial bone constituent unit contains artificial bone materials. An example of the artificial bone material used for an artificial bone constituent unit in the present invention is a calcium based material. Any calcium based material close to components of the bone may be used and is not specifically limited. Examples of the calcium based material include a calcium phosphate based material, a calcium carbonate based material, calcium lactate, and calcium gluconate. Among these calcium based materials, the calcium phosphate based material or the calcium carbonate based material is preferable. Examples of the calcium phosphate based material as material powder include hydroxyapatite, carbonate apatite, fluorine apatite, chlorine apatite, β-TCP, α-TCP, calcium metaphosphate, tetracalcium phosphate, octacalcium phosphate, calcium hydrogenphosphate, calcium dihydrogenphosphate, calcium pyrophosphate, or one or two of salts thereof or solvate thereof and, among these calcium phosphate based materials, α-TCP, β-TCP, or hydroxyapatite is preferable. Examples of the calcium carbonate based material include calcium carbonate and calcium hydrogencarbonate and, among these calcium carbonate based materials, calcium carbonate is preferable. The above calcium based materials may contain other compounds if necessary as long as the above compounds are main components. An artificial bone constituent unit produced from the above materials has a property of gradually replacing bone tissues in a living body. Therefore, an artificial bone constituent unit produced by using calcium based materials can suitably be used for treatment of bone lacking regions. 
         [0049]    In the present invention, the ratio of calcium based materials in the artificial bone constituent unit is preferably 40 to 90 percents by weight when the weight of the artificial bone constituent unit is set to 100 percents by weight. In addition, the artificial bone constituent unit in the present invention preferably contains, in addition to the calcium based material, a finishing agent such as a dicarboxylic compound as well. The finishing agent can prevent a situation in which elution of calcium ions from the artificial bone constituent unit occurs. Elution of calcium ions from the artificial bone constituent unit could cause an inflammatory reaction and cytotoxicity. Therefore, the artificial bone constituent unit containing a finishing agent can prevent a situation in which body tissues in which artificial bone constituent units are set up are damaged by calcium ions eluted from the artificial bone constituent units. Further, the artificial bone constituent unit containing a finishing agent can prevent a situation in which a substance involved in growth of cells is adsorbed by the artificial bone constituent unit. Therefore, after the shape being provided to the artificial bone constituent unit in the present invention, the artificial bone constituent unit preferably contains a finishing agent such as trehalose. The artificial bone constituent unit in the present invention may contain a material needed for the formation of a bearer such as a binder of curable apatite as a secondary member. A person skilled in the art can use such a secondary member appropriately. 
         [0050]    As shown in  FIG. 1A , the artificial bone constituent unit  1  has a body portion  7 . If the size of the body portion  7  is too small, it becomes difficult to assemble the artificial bone constituent units. If the size of the body portion  7  is too large, by contrast, it is difficult for an assembled artificial bone to match a desired shape. Thus, while the volume of the body portion  7  is cited as 0.1 cm 3  or more and 40 cm 3  or less, 0.2 cm 3  or more and 30 cm 3  or less is preferable, and 0.5 cm 3  or more and 10 cm 3  or less is particularly preferable. 
         [0051]    In a preferred mode of the first aspect, as shown in  FIG. 1A , the body portion  7  is a block in a hexahedral structure. Because the artificial bone constituent unit  1  has such a shape, the shape of an artificial bone can freely be designed. In the present invention, the hexahedral structure also contains a structure in which one or a plurality of edges or sides of the hexahedral structure is chamfered. By forming the body portion  7  as a block in a hexahedral structure for an artificial bone constituent unit in the present invention, an artificial bone can take a stable shape when assembled. In a preferred mode of the first aspect, the body portion  7  is an isosceles trapezoidal column. Because the artificial bone constituent unit  1  has such a shape, the shape of an artificial bone can freely be designed. In a preferred mode of the first aspect, the body portion  7  is a column and the cross section of the column is a portion of a ring. Because the artificial bone constituent unit  1  has such a shape, the shape of an artificial bone can freely be designed. 
         [0052]    The body portion  7  has a first hole  5 . As shown in  FIGS. 1B and 1C , the first hole  5  is located on both left and right side faces. As shown in  FIG. 1D , the first hole  5  preferably cuts through the body portion  7 . In a preferred mode of the first aspect, the diameter of the first hole  5  is 0.1 mm or more and 1 cm or less. With the presence of a hole in this size, an optimal amount of body tissues enters an artificial bone. Accordingly, the artificial bone will effectively replace bone tissues. If the diameter of the hole is too small, it becomes difficult for blood vessel or cells to enter the hole. If the diameter of the hole is too large, the strength of an artificial bone constituent unit wanes. Thus, the diameter of the first hole is preferably 0.3 mm or more and 5 mm or less, particularly preferably 0.5 mm or more and 2 mm or less. The sectional shape of the hole may not be, as shown in  FIG. 1B  or  1 C, circular. Examples of the shape of the hole other than the circular shape include an elliptic shape, polygonal shape, and star shape. If the artificial bone constituent unit has one of such shapes, blood vessel and cells can suitably enter deep into an assembled artificial bone. If blood vessel or cells enter the artificial bone, the time needed for the artificial bone to replace the bone in a living body can be reduced. 
         [0053]    In a preferred mode of the first aspect, as shown in  FIG. 1E , the first hole  5  communicates with holes  17 ,  19  present in other artificial bone constituent units  13 ,  15  connected to the artificial bone constituent unit  1 . With the presence of a hole (communicating hole) communicating a plurality of blocks, it becomes easier for body tissues including blood vessel to enter an artificial bone. Accordingly, the artificial bone will effectively replace bone tissues. 
         [0054]    Further, the body portion  7  has connecting portions  9 ,  11 . The connecting portions  9 ,  11  are used to connect the artificial bone constituent unit  1  to one or a plurality of the other artificial bone constituent units  13 ,  15 . With the above configuration, an artificial bone in a desired shape can be obtained by assembling a plurality of the artificial bone constituent units  1 . 
         [0055]    The connecting portions  9 ,  11  may have any shape that can connect the body portions  7 . In the example shown in  FIG. 1A , the connecting portion is formed of the convex portion  9  and the concave portion  11 . The convex portion  9  and the concave portion  11  have shapes to fit in with each other. 
         [0056]      FIG. 2  is a diagram showing a different example from the above example of the artificial bone constituent unit.  FIG. 2A  is a perspective view of the artificial bone constituent unit.  FIG. 2B  is a left side view of the artificial bone constituent unit.  FIG. 2C  is a right side view of the artificial bone constituent unit.  FIG. 2D  is a top view of the artificial bone constituent unit.  FIG. 2E  shows a top view when three artificial bone constituent units are assembled.  FIG. 2F  shows a perspective view of the artificial bone when three artificial bone constituent units are assembled. 
         [0057]    In the example shown in  FIG. 2 , the body portion  7  further has a second hole  21  and a third hole  23 . As shown in  FIGS. 2A to 2D , the second hole  21  is perpendicular to the first hole  5 . Also as shown in  FIGS. 2A to 2D , the third hole  23  is perpendicular to the first hole  5  and the second hole  21 . With the presence of such holes in various directions, body tissues effectively enter an artificial bone. Accordingly, the artificial bone will effectively replace bone tissues. In the example shown in  FIGS. 2A to 2E , the second hole and the third hole are perpendicular to the first hole. However, the second hole and the third hole may not be perpendicular to the first hole. 
         [0058]    If the ratio of volume occupied by the hole to the body portion is too small, it takes time before an artificial bone replaces the bone in a living body. On the other hand, if the ratio of volume occupied by the hole to the body portion is large, the strength of an artificial bone constituent unit wanes. Thus, if the volume of the body portion  7  including the hole is 100, while an example of the volume of the whole hole is 1 or more and 50 or less, 10 or more and 40 or less is preferable and, particularly preferably 10 or more and 30 or less. In the present invention, if the body portion  7  has a plurality of holes, the size of each hole may be the same or different. 
         [0059]    In the example shown in  FIG. 2 , the body portion  7  is an isosceles trapezoidal column. In the artificial bone constituent unit  1  in this mode, the connecting portions  9 ,  11  are provided at least on isosceles side faces  33 ,  35  of the body portion  7 . The artificial bone constituent unit  1  in this mode is connected to one or a plurality of the other artificial bone constituent units  13 ,  15  via the isosceles side faces. In this example, the connecting portions  9 ,  11  are the convex portion  27  or the concave portion  28 . As shown in  FIG. 2E , the convex portion  27  or the concave portion  28  of the artificial bone constituent unit  1  fits into a concave portion  29  or a convex portion  31  of the other connected artificial bone constituent units  13 ,  15  respectively. The artificial bone constituent unit  1  in this mode is connected to the other artificial bone constituent units  13 ,  15  via the convex portion  27  or the concave portion  28 . 
         [0060]    As shown in  FIG. 2A , the body portion  7  may have a plurality of the convex portions  27  and a plurality of the concave portions  28 . If the numbers of convex portions and concave portions are large, it becomes easier to fix an artificial bone constituent unit when connected to another artificial bone constituent unit, which is preferable. However, if there are too many convex portions and concave portions, it becomes almost impossible to provide holes of the desired size and the desired number. Therefore, one or more and eight or less is cited as the numbers of the convex portions and concave portions provided on one surface and the numbers thereof may be two or more and four or less. The convex portions and concave portions may also be provided on a plurality of surfaces. 
         [0061]    Examples of the shape of the convex portion  27  include a cylinder, polygonal column, cone, polygonal cone, and tapering. The shape of a concave portion in the present invention may be any shape into which a convex portion is fitted. The artificial bone is unstable if the convex portion  27  is not sufficiently high. On the other hand, if the convex portion  28  is too high, it becomes more difficult to design an artificial bone. From the above points, the height of the convex portion  27  is preferably 0.1 mm or more and 5 mm or less, still preferably 0.2 mm or more and 3 mm or less, particularly preferably 0.4 mm or more and 2 mm or less. 
         [0062]      FIG. 2F  is a diagram showing a state in which three artificial bone constituent units are connected. As shown in  FIG. 2F , the artificial bone is a curved artificial bone. That is, the artificial bone constituent unit in the present invention can reproduce a curved bone of living beings. Thus, an artificial bone fitting to an affected portion can be obtained by using an artificial bone constituent unit in the present invention. 
         [0063]      FIG. 3  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 3A  is a perspective view of the artificial bone constituent unit.  FIG. 3B  shows a perspective view of the artificial bone when three artificial bone constituent units are assembled. 
         [0064]    As shown in  FIG. 3A , the artificial bone constituent unit has the body portion  7  in a columnar shape and the cross section of the column is a portion of a ring. Because the artificial bone constituent unit  1  has such a shape, the shape of an artificial bone can freely be designed. Further, as shown in  FIG. 3B , if the artificial bone  3  is built using the artificial bone constituent unit  1 , a smooth artificial bone is built so that an artificial bone of lower invasion can be provided. 
         [0065]      FIG. 4  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 4A  is a perspective view of the artificial bone constituent unit.  FIG. 4B  shows a perspective view of the artificial bone  3  when three artificial bone constituent units are assembled. 
         [0066]    As shown in  FIG. 4A , the artificial bone constituent unit has groove  24  on the surface of the body portion  7 . Because the artificial bone constituent unit has the groove  24 , an adhesive can easily be injected to strengthen the connection between the artificial bone constituent units. 
         [0067]    The groove  24  provided on the surface of the body portion  7  can be used as an adhesive injection hole. With an adhesive injected into the groove  24 , the body portion  7  can enhance adhesiveness between adjacent artificial bone constituent units. The strength of an assembled artificial bone is thereby increased. Therefore, an artificial bone obtained by assembling artificial bone constituent units in the present invention can suitably be used also in a bone site under a load in a living body. 
         [0068]    As shown in  FIG. 4A , the groove  24  is preferably provided on one of the left and right side faces or both. When artificial bone constituent units are assembled, the groove  24  is preferably a groove that is continuous from an upper edge to a lower edge of the body portion and is preferably provided in a fixed position of the left and right side faces so that the groove  24  is continuous. The number of the grooves  24  may be one or two per surface as shown in  FIG. 4A  or three or more. Examples of the sectional shape of the groove  24  include a semicircle and polygon. The size of the groove  24  in a semicircular shape is 0.1 mm or more and 5 mm or less in diameter. 
         [0069]    As shown in  FIG. 4B , the groove  24  is preferably provided in each of corresponding positions of the adjacent two artificial bone constituent units. In such a case, the two grooves fit in to function as an adhesive injection hole. 
         [0070]      FIG. 5  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 5A  is a perspective view of the artificial bone constituent unit  1 .  FIG. 5B  is a left side view of the artificial bone constituent unit  1 .  FIG. 5C  is a right side view of the artificial bone constituent unit  1 .  FIG. 5D  is a top view of the artificial bone constituent unit.  FIG. 5E  is a bottom view of the artificial bone constituent unit.  FIG. 5F  shows a perspective view of the artificial bone  3  when artificial bone constituent units are assembled. 
         [0071]    As shown in  FIGS. 5A to 55 , the body portion  7  of the artificial bone constituent unit has, in addition to the connecting portions  9 ,  11  on the isosceles side faces  33 ,  35 , connecting portions  10 ,  12  on atop surface  36  and a undersurface  37  of the body portion  7 . Further, the body portion  7  of the artificial bone constituent unit has the groove  24  on the surface of the isosceles side faces  33 ,  35 . The body portion  7  is connected to another or a plurality of other artificial bone constituent units via the isosceles side faces  33 ,  35 , the top surface  36 , or the undersurface  37 . 
         [0072]      FIG. 5F  is a diagram showing an example of the artificial bone  3  after the artificial bone constituent units  1  being assembled. As shown in  FIG. 3 , when the artificial bone constituent units are assembled, the groove  24  of the artificial bone constituent unit  1  is fitted in with the groove of the adjacent artificial bone constituent unit to form an adhesive injection hole. Moreover, the adhesive injection hole is formed continuously over a plurality of artificial bone constituent units so that many artificial bone constituent units can be fixed by injecting an adhesive from the top position. 
         [0073]      FIG. 6  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 6A  is a perspective view of the artificial bone constituent unit  1 .  FIG. 6B  is a perspective view of the artificial bone  3  when artificial bone constituent units are assembled. 
         [0074]    As shown in  FIG. 6A , the body portion  7  of the artificial bone constituent unit has a hexahedral structure including a plurality of holes  5   a  to  5   e ,  21   a  to  21   e ,  23   a  to  23   e . The body portion  7  has the connecting portions  9 ,  11  on the isosceles side faces  33 ,  35  and the connecting portions  10 ,  12  on the top surface  36  and the undersurface  37  of the body portion  7 . Further, the body portion  7  has grooves  24   a ,  24   b  on the surface of the isosceles side faces  33 ,  35 . The holes  5   a ,  5   c ,  5   e  are perpendicular to the holes  21   a ,  21   c ,  21   e . The holes  5   a ,  5   b ,  5   d  are perpendicular to the holes  23   a ,  23   c ,  23   e . The holes  21   a ,  21   b ,  21   d  are perpendicular to the holes  23   a ,  23   b ,  23   d . The holes  5   b ,  5   c ,  5   d ,  5   e  are also perpendicular to the holes  21   b ,  23   d ,  21   d ,  23   b  respectively. The holes  21   c ,  21   e  are also perpendicular to the holes  23   c ,  23   e  respectively. In this way, the holes are communicatively connected to other holes. 
         [0075]    As shown in  FIG. 6A , the artificial bone constituent unit has a plurality of types of the grooves  24   a ,  24   b . Further, the groove  24   b  is cut through by a hole in the artificial bone constituent unit.  FIG. 6B  is a diagram showing a state when the artificial bone constituent units are assembled. In the example shown in  FIG. 6B , the two adjacent grooves  24   b  form one adhesive injection hole. The adhesive injection hole intersects holes in the vertical direction. Thus, when an adhesive is injected from the adhesive injection hole, the adhesive extends not only in the vertical direction, but also in the horizontal direction. As a result, the adhesive extending in the horizontal direction plays a role of a wedge so that the artificial bone constituent units are further strengthened. 
         [0076]      FIG. 7  is a diagram showing another artificial bone constituent unit from the above ones.  FIG. 7A  is a perspective view of the artificial bone constituent unit  1 .  FIG. 7B  is a left side view of the artificial bone constituent unit  1 .  FIG. 7C  is a right side view of the artificial bone constituent unit  1 .  FIG. 7D  is a top view of the artificial bone constituent unit  1 .  FIGS. 7E and 7F  are perspective views of artificial bone constituent units with different sizes.  FIG. 7G  is a perspective view of the artificial bone  3  when artificial bone constituent units with different sizes are assembled. 
         [0077]    In the example shown in  FIG. 7 , the body portion  7  of the artificial bone constituent unit has a structure in which a plurality of the holes  5 ,  21 ,  23  is included. The body portion  7  of the artificial bone constituent unit is in a columnar shape and the cross section of the column is a portion of a ring. A protruding portion forming a portion of a ring is present on the top surface and has a shape matching the shape of a depression at the bottom. On the other hand, a protruding portion is also present on the left side face of the body portion and has a shape matching the shape of a depression on the right side face. The protruding portion and the depression form a connecting portion. Each of the holes  5 ,  21 ,  23  intersects one of the holes and communicatively connected to other holes. As shown in  FIGS. 7A to 7D , the body portion  7  has the connecting portions  9 ,  11  on the side faces  33 ,  35  and the connecting portions  10 ,  12  on the top surface  36  and the undersurface  37  of the body portion  7 . Further, the body portion  7  has the grooves  24   a ,  24   b  on the surface of the side faces  33 ,  35 . The connecting portions  9 ,  11  have the grooves  25  ( 25   a ,  25   b ),  26  and the connecting portion  10  has grooves  25   c ,  25   d . The groove  25   a  is on the side of an adhesive surface of the connecting portion  9  and the side face  33  and is a portion cutting through from the side of the top surface  36  to the side of the undersurface  37 . The groove  25   a  forms a hole by being fitted in with the groove  24   b  of the body portion  7 . The grooves  25   c ,  25   d  included in the connecting portion  10  are portions on the side face on the side of the side faces  33 ,  35  of the body portion  7 . The groove  25   c  on the side of the side face  33  is communicatively connected to the groove  24   b  on the side face. When artificial bone constituent units are assembled, the groove  24   b , the groove  25   a , and the groove  25   c  form a hole by being fitted in with grooves included in the connection portions of other artificial bone constituent units. When artificial bone constituent units are assembled, the grooves  25   b ,  26  included in the connecting portions  9 ,  11  also form a hole by being fitted in with grooves included in the connection portions of other artificial bone constituent units. If an artificial bone obtained by assembling such artificial bone constituent units is implanted in a human body, cells and blood vessel enter the hole formed by the groove  24   b , the groove  25   a , and the groove  25   c  or the hole formed by the grooves  25   b ,  26 . The cells and blood vessel that have entered as described above can increase connection strength between artificial bone constituent units. Further, connection strength between artificial bone constituent units is increased by providing unevenness (groove) to the surface of the artificial bone constituent unit. Therefore, an artificial bone obtained by assembling such artificial bone constituent units can suitably be used also in a bone site likely to be under a load in a living body. 
         [0078]      FIGS. 7E and 7F  show artificial bone constituent units with different sizes.  FIG. 7G  shows a perspective view when artificial bone constituent units with different sizes as shown in  FIGS. 7A ,  7 E, and  7 F are combined. As shown in  FIG. 7G , the artificial bone is a curved artificial bone. Moreover, the artificial bone can be made to have various degrees of curvature of the artificial bone. Therefore, such artificial bone constituent units can be assembled into an artificial bone having a desired size or a desired curve (curved surface) by fitting to the size of an affected portion and the artificial bone can suitably be used for a bone lacking region. 
         [0079]      FIG. 8  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 8A  is a perspective view of the artificial bone constituent unit.  FIG. 8B  is a front view of the artificial bone constituent unit.  FIG. 8C  is a perspective view of the artificial bone when artificial bone constituent units are assembled. 
         [0080]    As shown in  FIGS. 8A and 8B , the artificial bone constituent unit has the body portion  7  in a regular triangular prism shape. The body portion  7  of the artificial bone constituent unit in this mode has the connection portions  9 ,  11  on at least two surfaces of the three side faces. The body portion  7  has the first hole  5  and second holes  38 . The first hole  5  is a hole cut through from the front to the rear face of the body portion  7 . The second holes  38  ( 38   a  to  38   c ) are having an opening on the side face of the body portion. As shown in  FIG. 8B , the first hole  5  and the second holes  38  ( 38   a  to  38   c ) each intersect other holes. Each hole is communicatively connected to other holes. If, as shown in  FIG. 8C , artificial bone constituent units in a regular triangular prism shape are used, an artificial bone fitted to an affected portion in which a portion of the spherical structure such as the cranial bone is lacking can be obtained. 
         [0081]      FIG. 9  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 9A  is a perspective view of the artificial bone constituent unit.  9 B is a front view of the artificial bone constituent unit.  FIG. 9C  shows a perspective view of the artificial bone when a plurality of artificial bone constituent units is assembled. 
         [0082]    As shown in  FIGS. 9A and 9B , the artificial bone constituent unit has the body portion  7  in a regular hexagonal prism shape. The body portion  7  of the artificial bone constituent unit in this mode has the connecting portion  9  in a convex shape or the connecting portion  11  in a concave shape on each of the six side faces. The connecting portions  9 ,  11  have a groove  39 . In addition, the body portion  7  has the first hole  5  and second holes  39 . The first hole  5  is a hole cut through from the front to the rear face of the body portion  7 . The second holes  39  ( 39   a  to  39   c ) are holes cut through from one side face to the side face opposite thereto. As shown in  FIG. 9B , the first hole  5  and the second holes  39  ( 39   a  to  39   c ) each intersect other holes. Each hole is communicatively connected to other holes. A portion of the second holes  39  is communicatively connected to the groove  39 . When connected to another artificial bone constituent unit, the groove  39  is fitted in with the grove of the other artificial bone constituent unit to form a hole. If, as shown in  FIG. 9C , artificial bone constituent units in a regular hexagonal prism shape are used, an artificial bone fitted to an affected portion in which a portion of the spherical structure such as the cranial bone is lacking can be obtained. 
         [0083]      FIG. 16  is a diagram showing a still different example from the above examples of the artificial bone constituent unit.  FIG. 16A  is a front view of the artificial bone constituent unit.  FIG. 16B  is a perspective view of the artificial bone constituent unit.  FIG. 17C  shows a front view of the artificial bone when a plurality of artificial bone constituent units is assembled. 
         [0084]    As shown in  FIGS. 16A and 168 , the body portion  7  of the artificial bone constituent unit is a dihexagonal prism in which three regular hexagonal prisms are integrally combined. The body portion  7  of the artificial bone constituent unit in this mode has the six connecting portions  9  in the convex shape and the six connecting portions  11  in the concave shape on each of 12 side faces. The connecting portion  9  in the convex shape is provided on all six protruding sides of the body portion  7  of the dihexagonal prism and the connecting portion  11  in the concave shape is provided on all six recessed sides of the body portion  7  of the dihexagonal prism. The connecting portions  9 ,  11  have the groove  39 . In addition, the body portion  7  has the first hole  5  and second holes  39 . The first hole  5  is a hole cut through from the front to the rear face of the body portion  7 . The second holes  39  ( 39   a  to  396 ) are holes cut through from one side face to the side face opposite thereto. The first hole  5  and the second holes  39  ( 39   a  to  39   f ) may each be formed so as to intersect other holes. Each hole is communicatively connected to other holes. A portion of the second holes  39  is communicatively connected to the groove  39 . When connected to another artificial bone constituent unit, the groove  39  is fitted in with the groove of the other artificial bone constituent unit to form a hole. If, as shown in  FIG. 16C , artificial bone constituent units in a dihexagonal prism shape in which three regular hexagonal prisms are integrally combined are used, an artificial bone fitted to an affected portion in which a portion of the spherical structure such as the cranial bone is lacking can be obtained. 
         [0085]      FIG. 17  is a diagram showing a still different example from the above examples of the artificial bone constituent unit. The artificial bone constituent unit shown in  FIG. 17  is a modification of the artificial bone constituent unit shown in  FIG. 16 .  FIG. 17A  is a front view of the artificial bone constituent unit.  FIG. 17B  is a perspective view of the artificial bone constituent unit.  FIG. 17C  shows a front view of the artificial bone when a plurality of artificial bone constituent units is assembled. 
         [0086]    As shown in  FIGS. 17A and 178 , the body portion  7  of the artificial bone constituent unit is a dihexagonal prism in which three regular hexagonal prisms are integrally combined. The body portion  7  of the artificial bone constituent unit in this mode has the three connecting portions  9  in the convex shape and the nine connecting portions  11  in the concave shape on each of 12 side faces. The connecting portion  9  in the convex shape is provided on three sides of six protruding sides of the body portion  7  of the dihexagonal prism and the connecting portion  11  in the concave shape is provided on the remaining three sides. Also, the connecting portion  11  in the concave shape is provided on all six recessed sides of the body portion  7  of the dihexagonal prism. The connecting portions  9 ,  11  have the groove  39 . In addition, the body portion  7  has the first hole  5  and the second holes  39 . The first hole  5  is a hole cut through from the front to the rear face of the body portion  7 . The second holes  39  ( 39   a  to  39   f ) are holes cut through from one side face to the side face opposite thereto. The first hole  5  and the second holes  39  ( 39   a  to  39   f ) may each be formed so as to intersect other holes. Each hole is communicatively connected to other holes. A portion of the second holes  39  is communicatively connected to the groove  39 . When connected to another artificial bone constituent unit, the groove  39  is fitted in with the groove of the other artificial bone constituent unit to form a hole. If, as shown in  FIG. 17C , artificial bone constituent units in a dihexagonal prism shape in which three regular hexagonal prisms are integrally combined are used, an artificial bone fitted to an affected portion in which a portion of the spherical structure such as the cranial bone is lacking can be obtained. 
         [0087]    Comparison of the artificial bone constituent unit shown in  FIG. 16  and the artificial bone constituent unit shown in  FIG. 17  shows that the former has more connection portions with other artificial bone constituent units. Thus, an artificial bone obtained by assembling the artificial bone constituent unit shown in  FIG. 16  has properties of high strength and being less likely to be detached. On the other hand, comparison of the artificial bone constituent unit shown in  FIG. 16  and the artificial bone constituent unit shown in  FIG. 17  shows that the latter has less connection portions with other artificial bone constituent units. Thus, an artificial bone obtained by assembling the artificial bone constituent unit shown in  FIG. 17  has properties of high flexibility and being easy to assemble. Therefore, the artificial bone constituent units shown in  FIGS. 16 and 17  each have different properties and a suitable artificial bone constituent unit depending on properties of the bone, which is an affected portion, may be selected. 
         [0088]      FIG. 10  is a diagram showing an artificial bone constituent system  40  in the present invention. The artificial bone constituent system  40  contains a plurality of artificial bone constituent units. The artificial bone constituent system  40  has at least a first artificial bone constituent unit group  41  and a second artificial bone constituent unit group  61 . The first artificial bone constituent unit group  41  and the second artificial bone constituent unit group  61  have a plurality of first artificial bone constituent units  42  and a plurality of second artificial bone constituent units  62  respectively.  FIG. 10A  is a perspective view of the artificial bone constituent system  40 .  FIG. 10B  is a perspective view showing the first artificial bone constituent unit  42 .  FIG. 10C  is a top view of the first artificial bone constituent unit  42 .  FIG. 100  is a perspective view showing the second artificial bone constituent unit  62 .  FIG. 10E  is a top view of the second artificial bone constituent unit  62 . 
         [0089]    As shown in  FIGS. 10B and 10C , the first artificial bone constituent unit  42  has a body portion  44 , first connecting portions  47 ,  48 , and second connecting portions  51 ,  52 . The body portion  44  is a portion that has a first hole  43  and a hexahedral structure. The first connecting portions  47 ,  48  are portions mounted on a left side face  45  and a right side face  46  of the body portion  44 . The second connecting portions  51 ,  52  are portions mounted on the front  49  and the rear face  50  of the body portion  44 . The first connecting portions  47 ,  48  are used to connect the first artificial bone constituent unit  42  to one or two first artificial bone constituent units  53 ,  54  contained in the first artificial bone constituent unit group  41 . 
         [0090]    On the other hand, as shown in  FIGS. 10D and 10E , the second artificial bone constituent unit  62  has the body portion  64 , first connecting portions  67 ,  68 , and second connecting portions  71 ,  72 . The body portion  64  is a portion that has a first hole  63  and a hexahedral structure. The first connecting portions  67 ,  68  are portions mounted on the left side face  65  and the right side face  66  of the body portion  64 . The second connecting portions  71 ,  72  are portions mounted on a front  69  and a rear face  70  of the body portion  64 . The first connecting portions  67 ,  68  are used to connect the second artificial bone constituent unit  62  to the one or two second artificial bone constituent units  73 ,  74  contained in the second artificial bone constituent unit group  61 . 
         [0091]    In the artificial bone constituent system  40 , the second connecting portion  51  of the first artificial bone constituent unit  41  is connected to the second connecting portion  72  of the second artificial bone constituent unit  62 . Accordingly, the first artificial bone constituent unit  42  and the second artificial bone constituent unit  62  are connected in the artificial bone constituent system  40  of the present invention. As shown in  FIG. 10A , an artificial bone constituent system in the present invention contains artificial bone constituent units of different sizes and therefore, an artificial bone fitted to the shape of a bone of living beings can be assembled. 
         [0092]      FIG. 11  is a diagram showing a different example from the above example of the artificial bone constituent system  40 . The artificial bone constituent system  40  contains a plurality of artificial bone constituent units. The artificial bone constituent system  40  has at least the first artificial bone constituent unit group  41  and the second artificial bone constituent unit group  61 . The first artificial bone constituent unit group  41  and the second artificial bone constituent unit group  61  have the plurality of first artificial bone constituent units  42  and the plurality of second artificial bone constituent units  62  respectively.  FIG. 11A  is a perspective view of the artificial bone constituent system  40 .  FIG. 11B  is a perspective view showing the first artificial bone constituent unit  42 .  FIG. 11C  is a left side view of the first artificial bone constituent unit  42 .  FIG. 11D  is a top view of the first artificial bone constituent unit  42 .  FIG. 11E  is a perspective view showing the second artificial bone constituent unit  62 .  FIG. 11F  is a left side view of the second artificial bone constituent unit  62 .  FIG. 11G  is a top view of the second artificial bone constituent unit  62 . 
         [0093]    As shown in  FIGS. 11B to 11D , the first artificial bone constituent unit  42  has the body portion  44  including the first connecting portions  47 ,  48 , the second connecting portions  51 ,  52 , and third connecting portions  58 ,  59 . The body portion  44  has the first hole  43 , a second hole  53 , and a third hole  54  and has a hexahedral structure. The first connecting portions  47 ,  48  are portions mounted on the left side face  45  and the right side face  46  of the body portion  44 . The second connecting portions  51 ,  52  are portions mounted on the front  49  and the rear face  50  of the body portion  44 . The third connecting portions  58 ,  59  are portions mounted on a top surface  55  and an undersurface  56  of the body portion. The first connecting portions  47 ,  48  are used to connect the first artificial bone constituent unit  42  to the one or two artificial bone constituent units  53 ,  54  contained in the first artificial bone constituent unit group  41 . 
         [0094]    On the other hand, as shown in  FIGS. 11E to 11G , the second artificial bone constituent unit  62  has the first connecting portions  67 ,  68 , the second connecting portions  71 ,  72 , and third connecting portions  78 ,  79 . The body portion  64  has the first hole  63 , a second hole  73 , and a third hole  74  and has a hexahedral structure. The first connecting portions  67 ,  68  are portions mounted on the left side face  65  and the right side face  66  of the body portion  64 . The second connecting portions  71 ,  72  are portions mounted on the front  69  and the rear face  70  of the body portion  64 . The third connecting portions  78 ,  79  are portions mounted on a top surface  75  and an undersurface  76  of the body portion  64 . The first connecting portions  67 ,  68  are used to connect the second artificial bone constituent unit  62  to the one or two artificial bone constituent units  73 ,  74  contained in the second artificial bone constituent unit group  61 . 
         [0095]    If one or two first artificial bone constituent units are connected to the first artificial bone constituent unit group  41  via one of the first connecting portions  47 ,  48  of the first artificial bone constituent unit  42 , the shape of a ring or a portion thereof may be formed. If one or two second artificial bone constituent units are connected to the second artificial bone constituent unit group  61  via one of the first connecting portions  67 ,  68  of the second artificial bone constituent unit  62 , the shape of a ring or a portion thereof may be formed. Incidentally, the shape of the body portion  44  of the first artificial bone constituent unit  42  and the body portion  64  of the second artificial bone constituent unit  62  is preferably a shape in which the shape of a ring or a portion thereof by the first artificial bone constituent unit group  41  is positioned on an outer circumference of the shape of a ring or a portion thereof by the second artificial bone constituent unit group  61 . 
         [0096]      FIG. 12  is a diagram showing an artificial bone constituent system  80  different from the above ones. The artificial bone constituent system  80  has a plurality of first artificial bone constituent units  82  and a plurality of second artificial bone constituent units  102 .  FIG. 12A  is a perspective view of the artificial bone constituent system  80 .  FIGS. 12B and 12C  are perspective views of the first artificial bone constituent unit  80 .  FIG. 12D  is a front view of the first artificial bone constituent unit  80 .  FIGS. 12E and 12F  are perspective views of the second artificial bone constituent unit  102 .  FIG. 12G  is a front view of the second artificial bone constituent unit  102 . 
         [0097]    As shown in  FIGS. 12B to 12D , a body portion  88  of the first artificial bone constituent unit  82  is a regular triangular prism having a first hole  84  and a second hole  86 . The body portion  88  has the first hole  84  and the second holes  86 . The first hole  84  is a hole cutting through from a front  94  to a rear face  96  of the body portion  88 . The second holes  86  ( 86   a  to  86   c ) are holes having an opening on side faces  90  ( 90   a  to  90   c ) of the body portion  88 . As shown in  FIG. 12D , the first hole  84  and the second holes  86  ( 86   a  to  86   c ) each intersect other holes and are communicatively connected to other holes. The body portion  147  further has connecting portions  92  ( 92   a  to  92   c ) on the side faces  90  ( 90   a  to  90   c ) respectively. As shown in  FIG. 12B to 12D , the connecting portion  92   a  has a convex shape and the connecting portions  92   b ,  92   c  have a concave shape. The convex shape and the concave shape of the connecting portions are shapes that fit together. The connecting portion  92   a  of the first artificial bone constituent unit  82  is connected to the connecting portion in the concave shape of another first artificial bone constituent unit or the second artificial bone constituent unit  102 . In contrast, the connecting portions  92   b ,  92   c  of the first artificial bone constituent unit  82  are connected to the connecting portion in the convex shape of another first artificial bone constituent unit or the second artificial bone constituent unit  102 . 
         [0098]    On the other hand, as shown in  FIGS. 12E to 12G , a body portion  108  of the second artificial bone constituent unit  102  is a regular triangular prism having a first hole  104  and a second hole  106 . The body portion  108  has the first hole  104  and the second holes  106 . The first hole  104  is a hole cutting through from a front  114  to a rear face  116  of the body portion  108 . The second holes  106  ( 106   a  to  106   c ) are holes having an opening on side faces  110  ( 110   a  to  110   c ) of the body portion  108 . As shown in  FIG. 12G , the first hole  104  and the second holes  106  ( 106   a  to  106   c ) each intersect other holes and are communicatively connected to other holes. The body portion  108  further has connecting portions  112  ( 112   a  to  112   c ) on the side faces  110  ( 110   a  to  110   c ) respectively. As shown in  FIGS. 12E to 12G , the connecting portions  112   a ,  112   c  have a convex shape and the connecting portion  112   b  has a concave shape. The connecting portions  112   a ,  112   c  of the second artificial bone constituent unit  102  are connected to the connecting portion in the concave shape of the first artificial bone constituent unit  82  or another second artificial bone constituent unit. In contrast, the connecting portion  112   b  of the second artificial bone constituent unit  102  is connected to the connecting portion in the convex shape of the first artificial bone constituent unit  82  or another second artificial bone constituent unit. 
         [0099]    In the artificial bone constituent system  80 , as described above, the first artificial bone constituent unit  82  is connected to the second artificial bone constituent unit  102 . As shown in  FIG. 12A , an artificial bone constituent system according to the present invention can build an artificial bone as part of a spherical structure by combining a plurality of the first artificial bone constituent units  82  and a plurality of the second artificial bone constituent units  102 . Therefore, the artificial bone constituent system according to the present invention can suitably be used for a deficiency of a region having the spherical structure such as the cranial bone. 
         [0100]      FIG. 13  is a diagram showing an artificial bone constituent system  120  different from the above ones. This artificial bone constituent system  120  has, in addition to the first artificial bone constituent unit  82  and the second artificial bone constituent unit  102  described above, a third artificial bone constituent unit  122 .  FIG. 13A  is a perspective view of the artificial bone constituent system  120 .  FIGS. 13B and 13C  are perspective views of the third artificial bone constituent unit  122 .  FIG. 13D  is a front view of the third artificial bone constituent unit  122 . 
         [0101]    As shown in  FIGS. 13B to 13D , the body portion  128  of the artificial bone constituent unit  122  is a regular hexagonal prism having a first hole  124  and second holes  126 . The body portion  128  may have the first hole  124  and the second hole  126 . The first hole  124  is a hole cut through from a front  139  to a rear face  141 . The second holes  126  ( 126   a  to  126   c ) cut through from side faces  130   a ,  130   b ,  130   c  to side faces  130   d ,  130   e ,  130   f  opposite thereto respectively. As shown in  FIG. 13D , the first hole  124  and the second holes  126  ( 126   a  to  126   c ) each intersect other holes and are communicatively connected to other holes. The body portion  128  further has connecting portions  132  ( 132   a  to  132   f ) on the side faces  130  ( 130   a  to  130   f ) respectively. As shown in  FIG. 13B to 13D , the connecting portions  132   a ,  132   c ,  132   e  are in a convex shape and the connecting portions  132   b ,  132   d ,  132   f  are in a concave shape. 
         [0102]    In the artificial bone constituent system  120  according to the present invention, the connecting portions  132   a ,  132   c ,  132   e  of the third artificial bone constituent unit  122  are connected to connecting portions in the concave shape of the first artificial bone constituent unit  84 , the second artificial bone constituent unit  102 , or another third artificial bone constituent unit. In contrast, the connecting portions  132   b ,  132   d ,  132   f  of the third artificial bone constituent unit  122  are connected to connecting portions in the convex shape of the first artificial bone constituent unit  84 , the second artificial bone constituent unit  102 , or another third artificial bone constituent unit. Also in the artificial bone constituent system  120  according to the present invention, the first artificial bone constituent unit  84  and the second artificial bone constituent unit  102  may be connected via the respective connecting portions. In this manner, the first artificial bone constituent unit  84 , the second artificial bone constituent unit  102 , and the third artificial bone constituent unit  122  are connected in the artificial bone constituent system  120 . 
         [0103]    As shown in  FIG. 13A , an artificial bone constituent system according to the present invention can assemble an artificial bone as a portion of the spherical structure by combining a plurality of the first artificial bone constituent units  82 , a plurality of the second artificial bone constituent units  102 , and a plurality of the third artificial bone constituent units  122 . Therefore, the artificial bone constituent system according to the present invention can suitably be used for a deficiency of a region having the spherical structure such as the cranial bone. 
         [0104]    An artificial bone constituent unit according to the present invention can be produced by using publicly known artificial bone materials and publicly known production methods. An example of the production method of the artificial bone constituent unit according to the present invention is injection molding. An example of the production method of the artificial bone constituent unit will briefly be described below. The example of the production method is a method disclosed by WO 2007/094134. This production method of the artificial bone constituent unit includes a kneading process, a molding process, a de-binder (degreasing) process, and a sintering process. The kneading process is a process to knead raw materials including a calcium based material and materials including a binder. The molding process is a process to obtain a molded body having a predetermined shape by using a kneaded material obtained in the kneading process through injection molding using an injection molding machine having a die. The de-binder (degreasing) process is a process to obtain a degreased body by removing a binder contained in the molded body obtained in the molding process. The sintering process is a process to obtain a sintered body by heating the degreased body after the de-binder process for sintering. In the present invention, a cleaning process may further be included after the sintering process. Any person skilled in the art can perform a publicly known post-processing process to appropriately perform post-processing of the molded body. 
         [0105]    As another production method, a curing agent solution is added to a curable artificial bone material having calcium phosphate or calcium carbonate as a main component by using a die cutting production method and the curable artificial bone material is kneaded and after the curable artificial bone material is cured, the artificial bone material is pulled out of the molding die. 
         [0106]    An example of the artificial bone material used for an artificial bone constituent unit according to the present invention is a calcium based material. Any calcium based material close to components of the bone may be used and is not specifically limited. Examples of the calcium based material include a calcium phosphate based material, a calcium carbonate based material, calcium lactate, and calcium gluconate. Among these calcium based materials, the calcium phosphate based material or the calcium carbonate based material is preferable. Examples of the calcium phosphate based material as material powder include hydroxyapatite, carbonate apatite, fluorine apatite, chlorine apatite, β-TCP, α-TCP, calcium metaphosphate, tetracalcium phosphate, octacalcium phosphate, calcium hydrogenphosphate, calcium dihydrogenphosphate, calcium pyrophosphate, or one or two of salts thereof or solvate thereof and, among these calcium phosphate based materials, α-TCP, β-TCP, or hydroxyapatite is preferable. Examples of the calcium carbonate based material include calcium carbonate and calcium hydrogencarbonate and, among these calcium carbonate based materials, calcium carbonate is preferable. The above calcium based materials may contain other compounds if necessary as long as the above compounds are main components. An artificial bone constituent unit produced from the above materials has a property of gradually replacing bone tissues in a living body. Therefore, an artificial bone constituent unit produced by using calcium based materials can suitably be used for treatment of bone lacking regions. 
         [0107]    Using an artificial bone constituent unit according to the present invention, an artificial bone is formed by assembling a plurality of such units. Then, the artificial bone is implanted in a patient who needs such an artificial bone. Thus, the artificial bone constituent unit according to the present invention is effective in treatment of patients who need such an artificial bone. That is, the present invention also provides a treating method of humans and mammals other than humans using the above artificial bone constituent unit according to the present invention. 
       Example 1 
       [0108]    Artificial bone constituent units are actually produced and assembled. The body portion is a hexagon the size of one side of which is about 5 mm. The height of a connecting portion is set to about 1 mm. The artificial bone constituent units are produced by the production method disclosed by WO 2007/094134. 
       (1) Kneading Process 
       [0109]    α-TCP (manufactured by Taihei. Chemical Industrial Co., Ltd., grain size: 10 μm) is used as material powder. A binder is formulated so that the percentage thereof by weight is 24 when the percentage of the material powder by weight is set to 100. As the binders, ethylene-vinyl acetate copolymer, poly(t-butyl methacrylate), paraffin wax, dibutyl phthalate, and stearic acid are used in a blending ratio of 30:30:30:5:5 by weight. A pressure kneader of 300 cc is heated to 150° C., the binders are input in descending order of melting point and after all binders are input, the binders are kneaded for 60 min and then cooled. The obtained kneaded material is ground by a pot mill made of ceramics for use as a material of molding (compound or pellet). 
         [0000]    (2) Molding Process The die is produced according to a CAD image of a bone prosthetic agent after the image thereof is formed by using CAD. A horizontal injection molding machine whose mold clamping force is 12 tons is used. The initial setting of the injection pressure is set to 12 GPa. The temperature of the cylinder of the molding machine is set to 130° C. and the temperature of the die to 20° C. 
       (3) De-Binder Process 
       [0110]    An atmospheric degreasing furnace is heated to the highest temperature in an atmospheric air (for example, in the range of 450 to 550° C.) and kept at the highest temperature for one hour before being cooled. The de-binder process lasts 18 hour including the cooling time. Alumina of 90% (porosity: 20%) is used as a setter. 
       (4) Sintering Process 
       [0111]    The degreased body is heated from the atmospheric air to the highest temperature and kept at the highest temperature for one hour before being cooled. The sintering time lasts 18 hour including the cooling time. The setter used in the de-binder process is directly used. 
         [0112]    The flexural strength of the obtained bone prosthetic agent is 6.1 MPa. 
         [0113]      FIG. 14  is a photo, instead of a drawing, showing artificial bone obtained by assembling artificial bone constituent units produced according to Example 1. According to the present invention, as shown in  FIG. 14 , an artificial bone fitted to the shape of a living body can be custom-made. 
       Example 2 
       [0114]    Artificial bone constituent units are produced in the same manner as in Example 1 except that the shape of the die is changed. 
         [0115]      FIG. 15  shows photos, instead of drawings, showing artificial bone constituent units produced according to Example 2.  FIG. 15A  shows the artificial bone constituent unit in the shape of a portion of a ring.  FIG. 15B  shows the artificial bone constituent unit forming a portion of the outer circumference of a ring and the artificial bone constituent unit forming a portion of a ring therewithin. According to the present invention, as shown in  FIG. 15 , an artificial bone fitted to the shape of a living body can be custom-made. 
       INDUSTRIAL APPLICABILITY 
       [0116]    The present invention can be used in the field of medical materials. 
       REFERENCE SIGNS LIST 
       [0000]    
       
         
           
               1  Artificial bone constituent unit 
               3  Artificial bone 
               5  First hole 
               7  Body portion 
               9 ,  11  Connecting portion 
               21  Second hole 
               23  Third hole 
               24 ,  25 ,  26  Groove 
               27  Convex portion 
               28  Concave portion 
               29  Concave portion 
               31  Convex portion 
               33 ,  35  Side face 
               36  Top surface 
               37  Undersurface 
               38  Second hole 
               39  Second hole 
               40  Artificial bone constituent system 
               41  First artificial bone constituent unit group 
               42  First artificial bone constituent unit 
               43  First hole 
               44  Body portion 
               45  Left side face 
               46  Right side face 
               47 ,  48  Connecting portion 
               49  Front 
               50  Rear face 
               51 ,  52  Second connecting portion 
               61  Second artificial bone constituent unit group 
               62  Second artificial bone constituent unit 
               63  First hole 
               64  Body portion 
               65  Left side face 
               66  Right side face 
               67 ,  68  First connecting portion 
               69  Front 
               70  Rear face 
               71 ,  72  Second connecting portion 
               82  First artificial bone constituent unit 
               84  First hole 
               86  Second hole 
               88  Body portion 
               90  Side face 
               92  Connecting portion 
               94  Front 
               96  Rear face 
               102  Second artificial bone constituent unit 
               104  First hole 
               106  Second hole 
               108  Body portion 
               110  Side face 
               112  Connecting portion 
               114  Front 
               116  Rear face 
               122  Third artificial bone constituent unit 
               124  First hole 
               126  Second hole 
               128  Body portion 
               130  Side face 
               132  Connecting portion 
               139  Front 
               141  Rear face