fig1 a is a schematic view showing a fully assembled bone fixation device according to a preferred embodiment of the present invention . in which 100 is a hollow fixation part , 110 is a joining end , 120 is an injecting end , 130 is a body having a mesh - like texture superficially , 200 is a cover part , 210 is a securing ring , and 220 is a halting part . the hollow fixation part 100 is formed as a unibody , and the securing ring 210 is used to secure the cover part 200 to the body 130 of the hollow fixation part 100 . fig1 b is a schematic view showing the bone fixation device of fig1 a after injecting is completed . in which 100 is a hollow fixation part , 110 is a joining end , 120 is an injecting end , 130 is a body , 200 is a cover part , 210 is a securing ring , 220 is a halting part , and 300 is a medical filling . wherein the medical filling 300 is injected into the cover part 200 via the injecting end 120 of the hollow fixation part 100 , and the medical filling 300 is allowed to completely fill up the cover part 200 and become lump - like . fig2 a is a schematic view showing a fully disassembled bone fixation device according to a preferred embodiment of the present invention . in which 100 is a hollow fixation part , 110 is a joining end , 120 is an injecting end , 130 is a body , 131 is an annular trough , 200 is a cover part , 210 is a securing ring , 220 is a halting part , 221 is an anterior halting component , and 222 is a posterior halting component . moreover , the securing ring 210 is used to secure the cover part 200 to the annular trough 131 of the hollow fixation part 100 . fig2 b is a schematic view showing a fully disassembled bone fixation device according to another preferred embodiment of the present invention . in which 110 is a joining end , 111 is a coupling end of the joining end 110 , 120 is an injecting end , 121 is a coupling end of the injecting end 120 , 131 is an annular trough , 200 is a cover part , 210 is a securing ring , 220 is a halting part , 221 is an anterior halting component , and 222 is a posterior halting component . wherein the hollow fixation part is divided into two portions including the joining end 110 and the injecting end 120 , and the joining end 110 and the injecting end 120 are joined together by screwing . moreover , the securing ring 210 is used to secure the cover part 200 to the annular trough 131 of the hollow fixation part 100 . fig3 a , 3 b , 3 c , 3 d , and 3 e are schematic views showing five different types of body texture for a hollow fixation part of the bone fixation device of the present invention . fig3 a shows : a bone joining device 400 and a hollow fixation part are formed as a unibody , a body 130 having no textures , an injecting end 120 having a plurality of holes for injecting a medical filling into a cover part via the injecting end 120 . fig3 b shows : a bone joining device 400 and a hollow fixation part are formed as a unibody , a body 130 having an annular texture , an injecting end 120 having a plurality of holes for injecting a medical filling into a cover part via the injecting end 120 . fig3 c shows : a bone joining device 400 and a hollow fixation part are formed as a unibody , a body 130 having a striped texture , an injecting end 120 having a plurality of holes for injecting a medical filling into a cover part via the injecting end 120 . fig3 d shows : a bone joining device 400 and a hollow fixation part are formed as a unibody , a body 130 having a speckled texture , an injecting end 120 having a plurality of holes for injecting a medical filling into a cover part via the injecting end 120 . fig3 e shows : a bone joining device 400 and a hollow fixation part are formed as a unibody , a body 130 having a mesh - like texture , an injecting end 120 having a plurality of holes for injecting a medical filling into a cover part via the injecting end 120 . fig4 a , 4 b , 4 c , 4 d , and 4 e are schematic views showing the joining between the bone fixation device with four types of bone joining device to form a spine fixation system , according to a preferred embodiment of the present invention . fig4 a shows : a bone joining device 400 being a receiving trough and may be screwed together with a hollow fixation part , a body 130 having a mesh - like texture , an injecting end 120 having a plurality of holes for injecting a medical filling into a cover part via the injecting end 120 . fig4 b shows : a bone joining device 400 being a joining rod and may be screwed together with a hollow fixation part , a body 130 having a mesh - like texture , an injecting end 120 having a plurality of holes for injecting a medical filling into a cover part via the injecting end 120 . fig4 c shows : a bone joining device 400 being a joining rod , the joining rod 400 is joined with a tightening device 420 and may be screwed together with a hollow fixation part , a body 130 having a mesh - like texture , an injecting end 120 having a plurality of holes for injecting a medical filling into a cover part via the injecting end 120 . fig4 d shows : a bone joining device 400 being a bone plate and may be screwed together with a hollow fixation part , a body 130 having a mesh - like texture , an injecting end 120 having a plurality of holes for injecting a medical filling into a cover part via the injecting end 120 . fig4 e shows : a bone joining device 400 being a receiving trough , the receiving trough 400 is joined with holders 430 by using rods 500 , and may be screwed together with hollow fixation parts , a body 130 having a mesh - like texture , an injecting end 120 having a plurality of holes for injecting a medical filling into a cover part via the injecting end 120 . fig5 a , 5 b , and 5 c are schematic views showing three types of injecting end of the hollow fixation device of the bone fixation device according to a preferred embodiment of the present invention . wherein 100 is a hollow fixation part , and 120 is an injecting end . fig5 a shows : the injecting end 120 having no holes or slits . fig5 b shows : the injecting end 120 having a plurality of slits for injecting a medical filling into a cover part via the injecting end 120 . fig5 c shows : the injecting end 120 having a plurality of holes for injecting a medical filling into a cover part via the injecting end 120 . fig6 a , 6 b , and 6 c are schematic views showing three types of coupling for the hollow fixation device of the bone fixation device according to a preferred embodiment of the present invention . wherein 100 is a hollow fixation part , 110 is a joining end , 111 is a coupling end of the joining end 110 , 120 is an injecting end , and 121 is a coupling end of the injecting end 120 . fig6 a shows : the hollow fixation part 100 being formed as a unibody . fig6 b shows : the joining end 110 being coupled to the injecting end 120 by screwing . fig6 c shows : the joining end 110 being coupled to the injecting end 120 by clasping . fig7 a , 7 b , 7 c , and 7 d are schematic views showing four types of cover part for the bone fixation device according to a preferred embodiment of the present invention . wherein 200 is a cover part . fig7 a shows : the cover part 200 being mesh - like . fig7 b shows : the cover part 200 being made of pet materials . fig7 c shows : the cover part 200 being made of metal . fig7 d shows : the cover part 200 being elastic . fig8 a , 8 b , 8 c , and 8 d are schematic views showing the joining between four types of cover part with the hollow fixation part of the bone fixation device according to a preferred embodiment of the present invention . wherein 130 is a body , 200 is a cover part , and 210 is a securing ring . fig8 a shows : the body 130 being coupled to the cover part 200 by riveting . fig8 b shows : the body 130 being coupled to the cover part 200 by screwing . fig8 c shows : the body 130 being coupled to the cover part 200 by tightening . fig8 d shows : the body 130 being coupled to the cover part 200 by binding . fig9 a , 9 b , and 9 c are schematic views showing the joining between three types of metal cover part with the hollow fixation device of the bone fixation device according to a preferred embodiment of the present invention . wherein 130 is a body , 200 is a cover part , and 210 is a securing ring . fig9 a shows : the cover part 200 being made of metal , and the body 130 being coupled to the cover part 200 by riveting . fig9 b shows : the cover part 200 being made of metal , and the body 130 being coupled to the cover part 200 by screwing . fig9 c shows : the cover part 200 being made of metal , and the body 130 being coupled to the cover part 200 by tightening . fig1 a , 10 b , 10 c , 10 d , 10 e , and 10 f are schematic views showing the surgical steps for joining the bone fixation device of the invention with a bone joining device . wherein 100 is a hollow fixation part , 120 is an injecting end , 200 is a cover part , 300 is a medical filling , 400 is a bone joining device , 410 is a coupling end , 600 is a tube , 700 is an injecting device , 800 is a vertebra , and 900 is a combined device . fig1 a shows : the injecting device 700 , the hollow fixation part 100 , and the cover part 200 are sequentially placed into the tube 600 , and then the tube 600 is implanted into the vertebra 800 where a hole has been created . fig1 b shows : the injecting device 700 , the hollow fixation part 100 , and the cover part 200 are implanted into the vertebra 800 where a hole has been created , then the tube 600 is removed . fig1 c shows : the medical filling 300 is subsequently injected into the hollow fixation part 100 via the injecting device 700 , and then into the cover part 200 via the injecting end 120 . fig1 d shows : the medical filling 300 and the cover part 200 have become lump - like . fig1 e shows : after injecting is completed , the injecting device 700 is removed . fig1 f shows : the bone joining device 400 is then locked into the hollow fixation part 100 . fig1 a , 11 b , and 11 c are schematic views showing the joining between the bone fixation device of the invention with a bone joining device having a tightening mechanism . wherein 100 is a hollow fixation part , 300 is a medical filling , and 400 is a bone joining device . fig1 a shows : the lump - like medical filling 300 fixes a spine fixation system on the vertebra along with a unibody of the hollow fixation part 100 and the bone joining device 400 . fig1 b shows : the spine fixation system fixes itself on the vertebra by using a clasping - type tightening mechanism between the hollow fixation part 100 and the bone joining device 400 . fig1 c shows : the spine fixation system fixes itself on the vertebra by using a screwing - type tightening mechanism between the hollow fixation part 100 and the bone joining device 400 . fig1 a , 12 b , and 12 c are schematic views showing the surgical steps for joining the bone fixation device of the invention with a cover part made of pet . wherein 100 is a hollow fixation part , 120 is an injecting end , 300 is a medical filling , 700 is an injecting device , and 800 is a vertebra . fig1 a shows : the hollow fixation part 100 is implanted into the vertebra 800 where a hole has been created by employing the injecting device 700 . fig1 b shows : the medical filling 300 is subsequently injected into the hollow fixation part 100 via the injecting device 700 , and then into the cover part via the injecting end 120 . fig1 c shows : the medical filling 300 has become lump - like completely . fig1 a , 13 b , 13 c , 13 d , and 13 e are schematic views showing the surgical steps for joining the bone fixation device of the invention with a bone joining device having a tightening mechanism . wherein 100 is a hollow fixation part , 200 is a cover part , 300 is a medical filling , 400 is a bone joining device , 700 is an injecting device , 800 is a vertebra , and 900 is a combined device . fig1 a shows : the hollow fixation part 100 is implanted into the vertebra 800 where a hole has been created by utilizing the injecting device 700 . fig1 b shows : the medical filling 300 is then injected into the hollow fixation part 100 via the injecting device 700 , and then into the cover part via the injecting end . fig1 c shows : the medical filling 300 has become lump - like completely . fig1 d shows : the bone joining device 400 is then locked into the hollow fixation part 100 . fig1 e shows : the bone joining device 400 has been fully combined into the hollow fixation part 100 . fig1 a , 14 b , and 14 c are schematic views showing the surgical steps for joining the bone fixation device of the invention with an elastic metal cover part . wherein 100 is a hollow fixation part , 200 is a cover part , 300 is a medical filling , 400 is a bone joining device , 700 is an injecting device , and 800 is a vertebra . fig1 a shows : the cover part 200 is made of metal , and the injecting device 700 is used to implant the hollow fixation part 100 into the vertebra 800 where a hole has been created . fig1 b shows : the medical filling 300 is then injected into the hollow fixation part 100 via the injecting device 700 , and then into the metal cover part 200 via the injecting end , so as to push open the metal cover part . fig1 c shows : the medical filling 300 has been completely injected and pushed open the metal cover part 200 so it becomes lump - like . fig1 is a schematic view showing a spine fixation system comprising the bone fixation device of the invention being joined with a bone joining device . wherein 100 is a hollow fixation part , 300 is a medical filling , 400 is a bone joining device , 500 is a rod , and 910 is a bone nail . the hollow fixation part 100 is joined to the bone nail 910 by using the bone joining device 400 and the rod 500 . fig1 a is a schematic view showing an artificial hip joint replacement system comprising the bone fixation device being joined with a hip joint substitute and an acetabular implant , according to a preferred embodiment of the present invention . wherein 100 is a hollow fixation part , 200 is a cover part , 520 is a hip joint substitute , 620 is an acetabular implant , 820 is a hip joint , and 810 is a hole . the hollow fixation part 100 and the hip joint substitute 520 are formed as a unibody . during surgery , the hollow fixation part 100 and the cover part 200 are placed into the hole 810 of the hip joint 820 created beforehand . fig1 b is a schematic view showing the system of fig1 a after injecting is completed according to a preferred embodiment of the present invention . wherein 100 is a hollow fixation part , 200 is a cover part , 300 is a medical filling , 520 is a hip joint substitute , 620 is an acetabular implant , and 820 is a hip joint . moreover , the medical filling 300 is injected into the cover part 200 via the injecting end of the hollow fixation part 100 , and the medical filling 300 is allowed to completely fill up the cover part 200 and become lump - like . fig1 is a schematic view showing an artificial hip joint replacement system comprising the bone fixation device being joined with a hip joint substitute and an acetabular implant , according to another preferred embodiment of the present invention . wherein 110 is a joining end , 120 is an injecting end , 200 is a cover part , 520 is a hip joint substitute , 620 is an acetabular implant , and 820 is a hip joint . a hollow fixation part and the hip joint substitute 520 are formed as two parts and joined together by screwing . during surgery , the hollow fixation part 100 and the cover part 200 are placed into the hole 810 of the hip joint 820 created beforehand . fig1 is a schematic view showing an artificial hip joint replacement system comprising the bone fixation device being joined with a hip joint substitute and an acetabular implant , according to yet another preferred embodiment of the present invention . wherein 100 is a hollow fixation part , 200 is a cover part , 300 is a medical filling , 520 is a hip joint substitute , 620 is an acetabular implant , 420 is a tightening device , and 820 is a hip joint . after injecting the medical filling into this artificial hip joint replacement system , a tightening device 420 is used to push and tighten the lump - like cover part toward the bone of surgical site . fig1 is a schematic view showing an artificial hip joint replacement system comprising the bone fixation device being joined with a hip joint substitute and an acetabular implant , according to still another preferred embodiment of the present invention . wherein 100 is a hollow fixation part , 200 is a cover part , 520 is a hip joint substitute , 620 is an acetabular implant , 710 is a first screw , 720 is a second screw , 730 is a plate , 820 is a hip joint , and 810 is a hole . after injecting the medical filling into this artificial hip joint replacement system , the first screw 710 , the second screw 720 , and the plate 730 are used to push and tighten the lump - like cover part toward the bone of surgical site . fig2 is a schematic view showing an artificial hip joint replacement system of the invention being joined with screws and a securing cable , according to a preferred embodiment of the present invention . wherein 100 is a hollow fixation part , 200 is a cover part , 520 is a hip joint substitute , 620 is an acetabular implant , 710 is a first screw , 720 is a second screw , 730 is a plate , 740 is a securing cable , 820 is a hip joint , and 810 is a hole . after injecting the medical filling into the artificial hip joint replacement system , the first screw 710 , the second screw 720 , the plate 730 , and the securing cable 740 are used to push and tighten the lump - like cover part toward the bone of surgical site . fig2 is a schematic view showing an artificial hip joint replacement system of the invention being joined with screws , according to another preferred embodiment of the present invention . wherein 100 is a hollow fixation part , 200 is a cover part , 520 is a hip joint substitute , 620 is an acetabular implant , 710 is a first screw , 711 is a first nut , 720 is a second screw , 721 is a second nut , 750 is a third screw , 820 is a hip joint , and 810 is a hole . after injecting the medical filling into the artificial hip joint replacement system , the first screw 710 , the second screw 720 , the first nut 711 , the second nut 721 , and the third screw 750 are used to push and tighten the lump - like cover part toward the bone of surgical site . fig2 a is a schematic view showing an artificial hip joint replacement system of the invention being joined with a second hollow fixation part , according to a preferred embodiment of the present invention wherein 100 is a hollow fixation part , 200 is a cover part , 300 is a medical filling , 150 is a second hollow fixation part , 520 is a hip joint substitute , 820 is a hip joint , and 920 is a securing plate . the artificial hip joint replacement system is internally reinforced by using the second hollow fixation part 150 and the cover part to provide additional space for injecting the medical filling 300 , and also externally reinforced by further using the securing plate 920 and screws . fig2 b is a schematic view showing the system of fig2 a from another angle of view . fig2 is a schematic view showing a long bone fixation system comprising the bone fixation device being joined with a tightening device , according to a preferred embodiment of the present invention . wherein 100 is a hollow fixation part , 200 is a cover part , 300 is a medical filling , 420 is a tightening device , 650 is a front broken bone , 660 is a rear broken bone , and 670 is a split . the hollow fixation part 100 and the cover part 200 are fitted through the rear broken bone 660 , the split 670 , and the front broken bone 650 , and the front and rear broken bones 650 and 660 are rejoined by injecting the medical filling 300 . the tightening device 420 is further employed to reinforce the joining between the front broken bone 650 , the rear broken bone 660 , and the hollow fixation part 100 in order to enhance the stability thereof . the surgical method thereof is further described in fig2 a to 29 k . fig2 is a schematic view showing a long bone fixation system comprising the bone fixation device being joined with a tightening device , according to another preferred embodiment of the present invention . wherein 100 is a hollow fixation part , 200 is a cover part , 300 is a medical filling , 420 is a tightening device , 650 is a front broken bone , 660 is a rear broken bone , and 670 is a split . the hollow fixation part 100 and the cover part 200 are fitted through the front broken bone 650 , the split 670 , and the rear broken bone 660 , and the front and rear broken bones 650 and 660 are rejoined by injecting the medical filling 300 . the tightening device 420 is further employed to reinforce the joining between the front broken bone 650 , the rear broken bone 660 , and the hollow fixation part 100 in order to enhance the stability thereof . the surgical method thereof is further described in fig2 a to 29 k . fig2 is a schematic view showing a long bone fixation system comprising the bone fixation device being joined with a tightening device , according to yet another preferred embodiment of the present invention . wherein 100 is a hollow fixation part , 200 is a cover part , 300 is a medical filling , 420 is a tightening device , 550 is a supplementary fixation device , 650 is a front broken bone , 660 is a rear broken bone , and 670 is a split . the hollow fixation part 100 and the cover part 200 are fitted through the supplementary fixation device 550 , the front broken bone 650 , the split 670 , and the rear broken bone 660 , and the front and rear broken bones 650 and 660 are rejoined by injecting the medical filling 300 . the tightening device 420 is further employed to reinforce the joining between the front broken bone 650 , the rear broken bone 660 , and the hollow fixation part 100 in order to enhance the stability thereof . the surgical method thereof is further described in fig2 a to 29 k . fig2 is a schematic view showing a long bone fixation system comprising the bone fixation device being joined with a tightening device , according to yet another preferred embodiment of the present invention . wherein 100 is a hollow fixation part , 200 is a cover part , 300 is a medical filling , 420 is a tightening device , 650 is a front broken bone , 660 is a rear broken bone , and 670 is a split . the hollow fixation part 100 and the cover part 200 are fitted through the front broken bone 650 , the split 670 , and the rear broken bone 660 , and the front and rear broken bones 650 and 660 are rejoined by injecting the medical filling 300 . the tightening device 420 is further employed to reinforce the joining between the front broken bone 650 , the rear broken bone 660 , and the hollow fixation part 100 in order to enhance the stability thereof . the surgical method thereof is further described in fig2 a to 29 k . fig2 is a schematic view showing a long bone fixation system comprising the bone fixation device being joined with a tightening device , according to still another preferred embodiment of the present invention . wherein 100 is a hollow fixation part , 200 is a cover part , 300 is a medical filling , 420 is a tightening device , 550 is a supplementary fixation device , 650 is a front broken bone , 660 is a rear broken bone , and 670 is a split . the hollow fixation part 100 and the cover part 200 are fitted through the rear broken bone 660 , the supplementary fixation device 550 , the split 670 , and the front broken bone 650 , and the front and rear broken bones 650 and 660 are rejoined by injecting the medical filling 300 . the tightening device 420 is further utilized to reinforce the joining between the front broken bone 650 , the rear broken bone 660 , and the hollow fixation part 100 in order to enhance the stability thereof . the surgical method thereof is further described in fig2 a to 29 k . fig2 is a schematic view showing a long bone fixation system comprising the bone fixation device being joined with a tightening device , according to a further preferred embodiment of the present invention . wherein 100 is a hollow fixation part , 200 is a cover part , 230 is a second cover part , 300 is a medical filling , 420 is a tightening device , 650 is a front broken bone , 660 is a rear broken bone , and 670 is a split . the hollow fixation part 100 , the cover part 200 , and the second cover part 230 are fitted through the rear broken bone 660 , the split 670 , and the front broken bone 650 , then the front and rear broken bones 650 and 660 are secured together by injecting the medical filling 300 into the cover part 200 , and then reinforced by injecting the medical filling 300 into the second cover part 230 . the tightening device 420 is further utilized to reinforce the joining between the front broken bone 650 , the rear broken bone 660 , and the hollow fixation part 100 in order to enhance the stability thereof . fig2 a to 29 k are schematic views showing the surgical steps for installing the long bone fixation system of the invention . wherein 100 is a hollow fixation part , 200 is a cover part , 220 is a halting part , 300 is a medical filling , 420 is a tightening device , 650 is a front broken bone , 660 is a rear broken bone , 670 is a split , 770 is a drilling device , 780 is a guiding device , 700 is an injecting device , and 790 is a locking device . fig2 a shows : the drilling device 770 drilling into the rear broken bone 660 . fig2 b shows : the drilling device 770 drilling into the rear broken bone 660 , via the split 670 , and into the front broken bone 650 . fig2 c shows : the drilling device 770 being removed after drilling is completed . fig2 d shows : the hollow fixation part 100 and the cover part 200 are placed into a hole 850 created by the drilling device 770 , wherein the injecting device 700 is joined with the hollow fixation part 100 , and the guiding device 780 is allowed to go through the hollow fixation part 100 via the injecting device 700 , into the cover part 200 and push against the halting part 220 , so as to support and protect the cover part 200 from collapsing when it is inserted into the broken bone . fig2 e shows : the hollow fixation part 100 and the cover part 200 being completely inserted into the hole 850 . fig2 f shows : the long bone fixation system being placed into position , and the guiding device 780 is then removed from the system . fig2 g shows : the medical filling 300 is injected into the cover part 200 via the injecting device 700 and the hollow fixation part 100 . fig2 h shows : the medical filling 300 and the cover part 200 have become lump - like . fig2 i shows : the injecting device 700 being removed from the hollow fixation part 100 after injecting is completed . fig2 j shows : the tightening device 420 being locked into the hollow fixation part 100 by using the locking device 790 . fig2 k shows : the tightening device 420 being locked into the hollow fixation part 100 and used to tighten the joining between the front broken bone 650 , the rear broken bone 660 , and the hollow fixation part .