Patent Publication Number: US-11395745-B2

Title: Spinal implant structure and kit thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional application of U.S. patent application Ser. No. 15/457,020, filed Mar. 13, 2017, which claims priority under 35 U.S.C. § 119(a) to Patent Application No. 105107739 filed in Taiwan on Mar. 14, 2016, all of which are hereby expressly incorporated by reference into the present application. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to spinal implant structures and, more particularly, to an intervertebral and intravertebral implant and a tool kit thereof. 
     Description of the Prior Art 
     The spine, also known as the vertebral column, essentially comprises four types of elements, namely the spinal cord, vertebrae, ligaments, and intervertebral discs. Severe osteoporosis, intervertebral disc degeneration, ligament degeneration, joint dislocation, and joint compression may bring mechanical damage to the spine (such as a spinal compression fracture) and thus destabilize the spine. Spinal instability is accompanied by extreme discomfort and pain, thereby predisposing the patient to chronic back pain, spine curvature disorders, and walking disability. 
     Among the ways to cure spinal instability is vertebroplasty, which entails placing an implant in a collapsed vertebral body. The implant in the collapsed vertebral body expands and thereby restores the collapsed vertebral body to its normal height. The implant is filled with a bone autograft or a bone substitute (bone cement) to enhance the stability of the spine with a view to curing spinal instability. 
     A conventional spinal implant structure requires an implanting tool in order to be placed in the collapsed vertebral body and then expands. There is a wide variety of commercially available spinal implant structures and implanting tools. However, the prior art is unsatisfactory and thus still has room for improvement. 
     SUMMARY OF THE INVENTION 
     The present invention provides a spinal implant structure kit, comprising a spinal implant structure and an operating tool for use with the spinal implant structure. The spinal implant structure structurally matches the operating tool so that vertebroplasty can be performed efficiently and easily in terms of the adjustment of the position of the spinal implant structure, expansion of the vertebral body, and perfusion of a bone cement, etc. 
     According to an embodiment of the present invention, a spinal implant structure is provided. The spinal implant structure comprises a first part, a second part, and at least one expansion arm. The second part is disposed along the lengthwise direction of the first part without overlapping the first part. The first part has a larger diameter than the second part. The at least one expansion arm has one end connecting with the first part and forming an included angle with the first part and the other end being a free end. The at least one expansion arm has a support arm. The support arm has one end connecting with the expansion arm and the other end connecting with the second part. The support arm comprises a plurality of weakened regions. In response to a change in the distance between the first part and the second part, the support arm bends at the weakened regions and thus drives the expansion arm to move, so as to increase the included angle and expand the spinal implant structure. The first part, second part, expansion arm, and support arm are formed integrally. 
     In another embodiment of the present invention, a spinal implant kit comprises the spinal implant structure and the operating tool. The operating tool comprises a tool body, a fixing sleeve, a central rod, and an operating handle. The tool body has a connecting portion and a gripping portion. The connecting portion has a tail provided with a jointing structure for connecting with the spinal implant structure. The fixing sleeve fits inside the tool body to fix the distance between a first part and a second part of the spinal implant structure. The central rod fits inside the fixing sleeve to connect with the second part directly or connect with the second part through the fixing sleeve. The operating handle connects with the central rod and rotates to drive the central rod to move in the lengthwise direction of the first part. 
     To render the above and other aspects of the present invention comprehensible, the present invention is hereunder illustrated by embodiments and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  through  FIG. 4B  are schematic views of a spinal implant structure according to an embodiment (first embodiment) of the present invention.  FIG. 1A  and 
         FIG. 1B  show that the spinal implant structure is folded (i.e., not netted).  FIG. 2A  through  FIG. 2C  show that the spinal implant structure (i.e., not netted) has been expanded.  FIG. 3A  and  FIG. 3B  show that the spinal implant structure (i.e., netted) is folded.  FIG. 4A  and  FIG. 4B  show that the spinal implant structure (i.e., netted) has been expanded. 
         FIG. 5A  through  FIG. 8B  are schematic views of the spinal implant structure according to another embodiment (second embodiment) of the present invention.  FIG. 5A  and  FIG. 5B  show that the spinal implant structure (i.e., not netted) is folded.  FIG. 6A  through  FIG. 6C  show that the spinal implant structure (i.e., not netted) has been expanded.  FIG. 7A  and  FIG. 7B  show that the spinal implant structure (i.e., netted) is folded.  FIG. 8A  through  FIG. 8B  show that the spinal implant structure (i.e., netted) has been expanded. 
         FIG. 9A  through  FIG. 15A  are schematic views of the operating tool, respectively. 
         FIG. 16A  through  FIG. 18B  are schematic views of the spinal implant structure and the operating tool coupled thereto according to the first embodiment of the present invention. 
         FIG. 19A  through  FIG. 20C  are schematic views of the spinal implant structure and the operating tool coupled thereto according to the second embodiment of the present invention. 
         FIG. 21A  through  FIG. 21B  are schematic views of the spinal implant structure according to yet another embodiment of the present invention. 
         FIGS. 1A, 2A, 3A, 4A, 5A, 6A, 7A, 8A, 9A, 10A, 11A, 12A, 13A, 14A, 15A, 16A, 17A, 18A, 19A, 20A, 21A  are lateral views.  FIGS. 1B, 2B, 3B, 4B, 5B, 6B, 7B, 8B, 9B, 10B, 11B, 12B, 13B, 14B, 16B, 17B, 18B, 19B, 20B, 21B  are cross-sectional views.  FIGS. 2C, 6C, 10C, 16C, 17C, 19C, 20C  are front views or partial enlarged views. 
     
    
    
     The aforesaid diagrams, which merely serve exemplary purposes to illustrate the shapes and relative positions of the constituent elements of the present invention, are not drawn to scale. 
     Due to the limits of drawing software, a mark, for example, indicative of an anchor A or contact, may be shown in the aforesaid diagrams, but the anchor A or contact is optional rather than required. 
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present invention provides a spinal implant kit which comprises a spinal implant structure and an operating tool. The spinal implant structure is made of a metal or a biocompatible polymer. The metal includes a titanium alloy, whereas the biocompatible polymer includes polyether-ether-ketone (PEEK) and its derivatives. PEEK and cancellous bone are closely in hardness. Furthermore, carbon fiber reinforced PEEK, which is as hard as cortical bone, is applicable to the spinal implant kit of the present invention. However, the present invention is not restrictive of the materials which the spinal implant kit of the present invention is made of, and thus the spinal implant kit of the present invention may also be made of the other biocompatible materials. 
     Spinal Implant Structure 
       FIG. 1A  through  FIG. 8C  illustrate two different embodiments of a spinal implant structure of the present invention.  FIG. 1A  through  FIG. 4B  show a spinal implant structure  100  of the first embodiment of the present invention.  FIG. 5A  through  FIG. 8C  show a spinal implant structure  200  of the second embodiment of the present invention. 
     First Embodiment 
     The spinal implant structure  100 , which is not netted, is illustrated by  FIG. 1A  through  FIG. 2C . Referring to  FIG. 1A  and  FIG. 1B , there are shown a lateral view and a cross-sectional view of the spinal implant structure  100  which is folded, respectively.  FIG. 2A  through  FIG. 2C  are a lateral view, a cross-sectional view, and a front view of the spinal implant structure  100  which has been expanded, respectively. Referring to  FIGS. 1A, 1B, 2A, 2B , the spinal implant structure  100  comprises a body  110  and a fixing screw barrel  120 . When the spinal implant structure  100  is folded, the body  110  becomes a hollow-cored cylinder, and the fixing screw barrel  120  also becomes a hollow-cored cylinder. The spinal implant structure  100  has an expansion end  101  (left end) and a fixing end  102  (right end). The expansion end  101  is expanded with the operating tool (referring to  FIG. 1A  and  FIG. 2A ), and the degree of expansion can be adjusted as needed. 
     [Body] 
     The body  110  of the spinal implant structure  100  comprises a first part  111 , a second part  112 , an expansion arm  113 , and a support arm  114 , and the four parts are formed integrally. Both the first part  111  and the second part  112  are hollow-cored cylinders. The first part  111  and the second part  112 , which are separated and do not overlap (engage), are arranged along the same horizontal axis (X-axis,  FIG. 1B ). That is, the first part  111  and the second part  112  are two smaller independent tubes (which may also be called the first tube  111  and the second tube  112 ) split from the body  110 , and the two parts are connected by the expansion arm  113  and the support arm  114 . The first part  111  contains the fixing screw barrel  120 . The second part  112  contains a fixing component and a netting (to be described later.) The first part  111  has an inner diameter slightly larger than the second part  112  and a length slightly longer than the length of the second part  112 . The degree of the expansion of the spinal implant structure  100  can be changed by adjusting the distance between the first part  111  and the second part  112 . In this embodiment, the degree of the expansion of the spinal implant structure  100  increases, as the first part  111  and the second part  112  get closer to thereby reduce the distance therebetween along the horizontal axis (X-axis). Hence, an operating tool (a central rod, to be described later) is required to draw the second part  112  closer to the first part  111  (i.e., rightward) in order for the spinal implant structure  100  to expand. 
     The bending of the expansion arm  113  enables the spinal implant structure  100  to expand. An end  113   a  (first end) of the expansion arm  113  connects with the first part  111  and extends outward from the first part  111 . The other end  113   b  (second end) of the expansion arm  113  is a free end which does not connect with any other component. A stress weakening portion (weakened section) is defined at a junction  113   c  of the expansion arm  113  and the first part  111 . The stress weakening portion is, for example, made thin or hollowed out so that the stress weakening portion (weakened section) is weaker than its surroundings. When subjected to an applied force, the expansion arm  113  bends outward from the stress weakening portion to effectuate expansion. The stress weakening portion is a notch which may have a valley, a concave, a V-, a U-shape, etc. An included angle θ (shown in  FIG. 2B ) smaller than 90 degrees is formed between the expansion arm  113  and the extension line of the first part  111 . The included angle θ indicates the degree of the expansion of the spinal implant structure  100 . The included angle θ equals 0 degree when the spinal implant structure  100  is folded ( FIG. 1A  and  FIG. 1B ). The included angle θ is larger than 0 degree but smaller than 90 degrees when the spinal implant structure  100  has been expanded ( FIG. 2A  and FIG.  2 B). The expansion arm  113  is in the number of one or more. If the expansion arm  113  is in the number of two or more, the expansion arms  113  connected to the first part  111  are equally spaced apart. As shown in  FIG. 2C , in this embodiment, the spinal implant structure  100  comprises three expansion arms  113  spaced apart by 120 degrees. In another embodiment of the present invention, the expansion arms are in the number of two (and thus spaced apart by 180 degrees), four (and thus spaced apart by 90 degrees) or more. The more the expansion arms are provided, the more uniform the distribution of forces required to effectuate expansion is, the smaller each expansion arm is, and the stricter the requirement for product precision is. 
     The expansion arm  113  (expansion arm body) has therein a support arm  114 . The support arm  114  is tongue-like in shape and can be considered as split from the expansion arm  113 ; in other words, the support arm  114  and the expansion arm  113  are formed integrally. Or, the expansion arm  113  and the support arm  114  can both be considered as split from the body  110 . When the support arm  114  and the expansion arm  113  are integrally formed and split from the body  110 , the manufacturing process of the spinal implant structure  100  can be further simplified. An end  114   a  (first end) of the support arm  114  is not only connected to the inner side of the expansion arm  113 , but also connected to the expansion arm  113  in a manner to be positioned proximate to the first part  111 . The other end  114   b  (second end) of the support arm  114  is connected to the second part  112  in a manner to be positioned proximate to the first part  111 . At least one stress weakening portion (weakened section) is defined at the support arm  114 . This embodiment is exemplified by two stress weakening portions located at a junction  114   c  of the support arm  114  and the expansion arm  113  and a junction  114   d  of the support arm  114  and the second part  112 , respectively. In response to a reduction in the distance between the first part  111  and the second part  112 , the support arm  114  bends at the stress weakening portions under a force. As shown in  FIG. 2B , at the stress weakening portion  114   c , the support arm bends toward the inner side of the spinal implant structure  100 , whereas, at the stress weakening portion  114   d , the support arm  114  bends toward the outer side of the spinal implant structure  100 , thereby driving the expansion arm  113  to bend toward the outer side of the spinal implant structure  100  and thus increasing the included angle θ, so as for the spinal implant structure  100  to expand. The stress weakening portions are, for example, made thin or hollowed out so that the stress weakening portions are weaker than their surroundings; hence, when the support arm  114  is subjected to an applied force, the resultant stress is concentrated on the stress weakening portions, thereby causing structural deformation of the support arm  114  (i.e., the bending of the support arm  114 ). In the expansion process of the spinal implant structure  100 , the distance between the first part  111  and the second part  112  decreases until the both parts meet. However, the first part  111  and the second part  112  do not overlap with or engage each other. 
     The body  110  of the spinal implant structure  100  is preferably formed integrally, for example, by molding, lathing, milling, electrical discharge machining (EDM),  3 D printing, or pressing, to form the first part  111 , the second part  112 , the expansion arm  113 , and the support arm  114  by a one-off process. 
     [Fixing Screw Barrel] 
     Like the body  110 , the fixing screw barrel  120  is a hollow-cored cylinder. The fixing screw barrel  120  fixes the distance between the first part  111  and the second part  112  upon completion of the expansion of the spinal implant structure  100 . The fixing screw barrel  120  has a smaller diameter than the first part  111  so as to fit inside the first part  111 . The fixing screw barrel  120  has an end positioned proximate to the second part  112 , and the end has a protruding portion  121 . The diameter of the protruding portion  121  substantially equals the inner diameter of the second part  112 . The outer surface of the protruding portion  121  has a first outer thread  121   a . The first outer thread  121   a  matches a first inner thread  112   a  disposed on the inner surface of the second part  112 ; hence, the protruding portion  121  can be rotated and inserted into the second part  112  so as to be fixed thereto, allowing the fixing screw barrel  120  to abuttingly connect with the second part  112 . A second inner thread  120   a  is disposed on the inner surface of the fixing screw barrel  120 . The second inner thread  120   a  matches the outer thread (to be described later) of the central rod of the operating tool. After rotating and inserting the central rod into the fixing screw barrel, the user can pull the central rod and thereby drive the fixing screw barrel  120  and the second part  112  to move, allowing the second part  112  to get closer to the first part  111 , so as to effectuate the expansion of the spinal implant structure  100 . 
     Referring to  FIG. 1B , when the spinal implant structure  100  is folded, the tail (right end) of the fixing screw barrel  120  is contained in the first part  111 . Referring to  FIG. 2B , when the spinal implant structure  100  has been expanded, the second part  112  moves toward the first part  111 , and the tail of the fixing screw barrel  120  protrudes from the first part  111 . Another screw nut (not shown, derived from the operating tool) fits around the protruding part of the tail of the fixing screw barrel  120  to prevent the fixing screw barrel  120  from moving toward the second part  112 , thereby fixing the distance between the first part  111  and the second part  112 . To fit the fixing screw barrel  120  inside the other screw nut, an outer thread is disposed on a portion of the outer surface (tail) of the fixing screw barrel  120 . 
     The wall of the fixing screw barrel  120  has one or at least two through holes  122  whereby a bone cement enters the vertebral body during the bone cement perfusion step (to be described later). 
     When the spinal implant structure  100  is in an expansion position ( FIG. 2A ), it has a larger internal volume than when it is folded ( FIG. 1A ), and can therefore support and restore a damaged/collapsed vertebral body; also, a large amount of bone cement can be filled in the spinal implant structure  100  to reinforce the support. 
     [Netting] 
       FIG. 3A  through  FIG. 4B  show that the spinal implant structure  100  has a netting  130  mounted thereon.  FIG. 3A  and  FIG. 3B  show that the spinal implant structure  100  is folded.  FIG. 4A  and  FIG. 4B  show that the spinal implant structure  100  has been expanded. The netting  130  restricts the range of flow of the bone cement being perfused into the spinal implant structure  100 , so as to prevent the bone cement from spilling from the vertebral body, allow the spinal implant structure  100  to be uniformly expanded, and reinforce the vertebral body. 
     The netting  130  is hollow-cored and cylindrical in shape. The netting  130  fits around the expansion arm  113  of the spinal implant structure  100  and can unfold as a result of the expansion of the spinal implant structure  100  ( FIG. 4B ). The openings at the two ends of the netting  130  differ in size. The sidewall of the end with a larger opening has at least one engaging hole  131 . The end is engaged with a first part-facing end of the expansion arm  113 . The other end of the netting  130  has a fixing hole  132  of a smaller diameter ( FIG. 4A ). When the spinal implant structure  100  is folded ( FIG. 3B ), one end of the netting  130  is fixed to the expansion arm  113  through the engaging hole  131 , whereas the other end of the netting  130  is bent to be inserted into the spinal implant structure  100 , and in consequence a fixing component  140  is fixed to the second part  112  through the fixing hole  132 . The fixing component  140  is, for example, a screw whose thread enables it to be rotated and inserted into the second part  112 . The outer diameter of the screw&#39;s head is slightly larger than the diameter of the fixing hole  132  of the netting  130 . Hence, the netting  130  is fixed in place between the screw&#39;s head and thread; in other words, the netting  130  is fixed in place at the junction of the fixing component  140  and the second part  112 . In this embodiment, the netting  130  is disconnectably engaged between the fixing component  140  and the second part  112 ; hence, when the spinal implant structure  100  is expanded ( FIGS. 4A, 4B ), that is, at the time when the second part  112  moves toward the first part  111  under a pulling force, the netting  130  is disconnected from the fixing component  140  under the pulling force, thereby allowing the netting  130  to unfold as a result of the expansion of the spinal implant structure  100 . There are plenty of ways to disconnect the netting  130  from the fixing component  140 , including making the screw head of the fixing component  140  slightly larger than the fixing hole  132  and defining it with a lead angle, or providing several notches on the fixing hole  132 , but the present invention is not limited thereto. Therefore, when the second part  112  moves toward the first part  111  under a pulling force, the netting  130  can be easily disconnected from the fixing component  140  under a reverse pulling force. 
     Second Embodiment 
       FIG. 5A  through  FIG. 6C  show that the spinal implant structure  200  is not netted. The spinal implant structure  200  of the second embodiment is identical to the spinal implant structure  100  of the first embodiment in terms of most technical features. For the sake of brevity, the identical technical features are not described herein. 
       FIG. 5A  and  FIG. 5B  are a lateral view and a cross-sectional view of the spinal implant structure  200  which is folded, respectively.  FIG. 6A  through  FIG. 6C  are a lateral view, a cross-sectional view, and a front view of the spinal implant structure  200  which has been expanded, respectively. Referring to  FIGS. 5A, 5B, 6A, 6B , the spinal implant structure  200  comprises a body  210  and a fixing screw barrel  220 . When the spinal implant structure  200  is folded, the body  210  is a hollow-cored cylinder, and the fixing screw barrel  220  is also a hollow-cored cylinder. The spinal implant structure  200  has an expansion end  201  (left end) and a fixing end  202  (right end). The expansion end  201  is expanded with the operating tool (shown in  FIG. 5A  and  FIG. 6A ), and the degree of expansion can be adjusted as needed. 
     [Body] 
     The body  210  of the spinal implant structure  200  comprises a first part  211 , a second part  212 , an expansion arm  213  and a support arm  214 , and the four parts are integrally formed. Both the first part  211  and the second part  212  are hollow-cored cylinders. The first part  211  and the second part  212 , which are separated and do not overlap, are arranged along the same horizontal axis (X-axis). That is, the first part  211  and the second part  212  can be considered as two smaller independent tubes split from the body  210 , and the two parts are connected by the expansion arm  213  and the support arm  214 . The first part  211  contains the fixing screw barrel  220 . The second part  212  contains a netting  230  and a fixing component  240  ( FIG. 6A  through  FIG. 8B ). The first part  211  has an internal diameter slightly larger than that of the second part  212 . When the spinal implant structure  200  is folded, the distance between the first part  211  and the second part  212  is very short or the two parts even meet each other. The degree of the expansion of the spinal implant structure  200  can be changed by adjusting the distance between the first part  211  and the second part  212 . The second embodiment differs from the first embodiment in that when the first part  211  and the second part  212  move away from each other, that is, the distance between the first part  211  and the second part  212  along the horizontal axis (X-axis) increases, the degree of expansion increases. In view of this, an operating tool (a central rod, to be described later) is required to move the second part  212  toward the expansion end  201  (i.e., leftward), so as to expand the spinal implant structure  200 . 
     The spinal implant structure  200  is expanded because of the bending of the expansion arm  213 . The expansion arm  213  has an end  213   a  (first end) which connects with the first part  211  and extends outward from the first part  211 . The other end  213   b  (second end) of the expansion arm  213  is a free end which does not connect with any other component. A stress weakening portion (weakened section) is defined at a junction  213   c  of the expansion arm  213  and the first part  211 . The stress weakening portion is, for example, made thin or hollowed out so that the stress weakening portion (weakened section) is weaker than its surroundings. When subjected to an applied force, the expansion arm  213  bends outward from the stress weakening portion to effectuate expansion. An included angle θ ( FIG. 6B ) smaller than 90 degrees is formed between the expansion arm  213  and the extension line of the first part  211 . The included angle θ indicates the degree of the expansion of the spinal implant structure  200 . The included angle θ equals 0 degree when the spinal implant structure  200  is folded ( FIG. 5A  and  FIG. 5B ). The included angle θ is larger than 0 degree but smaller than 90 degrees when the spinal implant structure  200  has been expanded ( FIG. 6A  and  FIG. 6B ). The expansion arm  213  is in the number of one or more. If the expansion arm  213  is in the number of two or more, the expansion arms  213  connected to the first part  211  are equally spaced apart. As shown in  FIG. 6C , the spinal implant structure  200  comprises three expansion arms  213  spaced apart by 120 degrees. In another embodiment of the present invention, the expansion arms are in the number of two (and thus spaced apart by 180 degrees), four (and thus spaced apart by 90 degrees) or more. The more the expansion arms are provided, the more uniform the distribution of forces required to effectuate expansion is, the smaller each expansion arm is, and the stricter the requirement for product precision is. 
     The expansion arm  213  has therein a support arm  214 . The support arm  214  is tongue-like in shape and can be considered as formed by being split from the expansion arm  213 ; in other words, the support arm  214  and the expansion arm  213  are formed integrally. On the other hand, the expansion arm  213  and the support arm  214  can both be considered as being split from the body  210 . An end  214   a  (first end) of the support arm  214  is not only connected to the inner side of the expansion arm  213 , but also connected to the expansion arm  213  in a manner to be positioned proximate to the free end  213   b . The other end  214   b  (second end) of the support arm  214  is connected to the second part  112  in a manner to be positioned distal to the first part  211 . At least one stress weakening portion (weakened region) is defined at the support arm  214 . This embodiment is exemplified by two stress weakening portions located at a junction  214   c  of the support arm  214  and the expansion arm  213  and a junction  214   d  of the support arm  214  and the second part  212 , respectively. In response to an increase in the distance between the first part  211  and the second part  212 , the support arm  214  bends at the stress weakening portions under a force. As shown in  FIG. 6B , at the stress weakening portion  214   c , the support arm  214  bends toward the inner side of the spinal implant structure  200 , whereas, at the stress weakening portion  214   d , the support arm  214  bends toward the outer side of the spinal implant structure  200 , thereby driving the expansion arm  213  to bend toward the outer side of the spinal implant structure  200  and thus increasing the included angle θ, so as for the spinal implant structure  200  to expand. The stress weakening portions are, for example, made thin or hollowed out so that the stress weakening portions are weaker than their surroundings; hence, when the support arm  214  is subjected to an applied force, the resultant stress is concentrated on the stress weakening portions, thereby causing structural deformation of the support arm  214  (i.e., the bending of the support arm  214 ). 
     [Derivative Design of the Body] 
     Referring to  FIG. 21A  and  FIG. 21B , which illustrate a spinal implant structure  400  according to yet another embodiment of this invention. The difference between the spinal implant structure  400  and the above-described spinal implant structure  200  lies in the design of a fixing end  402 . As shown in  FIG. 21A , an engagement positioning block  403  (the same design as in the spinal implant structure  200 ) is provided at the fixing end  402  (the left end) of the spinal implant structure  400 , and is used to engage an operating tool described below. A corresponding engaging slot is provided at an engaging end of the operating tool for engaging the spinal implant structure  400 . An extension rib  404  is also provided on the spinal implant structure  400  and extends from the engagement positioning block  403  toward the inner side of the spinal implant structure  400  (i.e., toward the expansion arm  413 ). The extension rib  404  is used for enhancing the strength of the first part  411  of the spinal implant structure  400 , so that structural distortion or fracture can be avoided during the implanting process. Besides, as shown in  FIG. 21B , the engagement positioning block  403  can extend slightly more toward the outer (left) side of the spinal implant structure  400  and have an extra outer protruding block  403 A extending out from the fixing end  402  of the spinal implant structure  400 . When the spinal implant structure  400  comprises the outer protruding block  403 A, it can more steadily connect with or engage an operating tool (as will be described later) having a corresponding slot or recess structure, and the occurrence of sliding or displacement in the implanting process can be reduced. In yet another embodiment of this invention, a recess  405  can be arranged at the inner side of a body  410  of the spinal implant structure  400 . The recess  405  connects to the outside of the body  410 , and has an opening in a horizontal direction (X-axis) of the first part  411 . The recess  405  can be a long concaved slot or groove, and as the recess  405  has one opening end and another closed end, an auxiliary tool (such as a long and thin rod or needle) can be used to reach into the recess  405  from the outside of the body  410  to further apply a force by pressing against the recess  405 . As such, when withdrawing the operating tool, the force applying thereto can be increased without causing displacement of the spinal implant structure  400 , thereby solving the problem of distortion during the implanting process that hampers withdrawal of the operating tool. 
     [Fixing Screw Barrel] 
     Like the body  210 , the fixing screw barrel  220  is a hollow-cored cylinder. The fixing screw barrel  220  fixes the distance between the first part  211  and the second part  212  upon completion of the expansion of the spinal implant structure  200 . The fixing screw barrel  220  has a smaller diameter than the first part  211  so as to fit inside the first part  211 . A third outer thread is disposed on a portion of the outer surface of the fixing screw barrel  220 . The third outer thread matches a third inner thread disposed on the inner surface of the first part  211 . Hence, the fixing screw barrel  220  can be rotated and inserted into the first part  211 , so as to be adjustably moved forward and backward by the threads and fixed in place. Since the position of the fixing screw barrel  220  is adjustable, the front end of the fixing screw barrel  220  can abuttingly connect with the second part  212  so that the second part  212  is fixed in place, thereby fixing the distance between the first part  211  and the second part  212 . Since the fixing screw barrel  220  is adjustably moved forward and backward by the threads, it generates a torque. As a result, the spinal implant structure  200  in operation does not require the fixing screw barrel  220  to move the second part  212 ; instead, a central rod (to be described later) of the operating tool moves the second part  212  horizontally away from the first part  211  and thus effectuates the expansion of the spinal implant structure  200 , and then the fixing screw barrel  220  is moved forward to abuttingly connect with the second part  212 , thereby fixing the second part  212  in place. 
     Referring to  FIG. 5B , when the spinal implant structure  200  is folded, the tail of the fixing screw barrel  220  protrudes from the first part  211  slightly. Referring to  FIG. 6B , when the spinal implant structure  200  has been expanded, the second part  212  separates from the first part  211  to allow the tail of the fixing screw barrel  220  to enter the first part  211  completely and allow the front end of the fixing screw barrel  220  to abuttingly connect with the second part  211 , thereby fixing the distance between the first part  211  and the second part  212 . 
     The wall of the fixing screw barrel  220  has one or at least two through holes  222  whereby the bone cement enters the vertebral body during the bone cement perfusion step (to be described later). 
     [Netting] 
       FIG. 7A  through  FIG. 8B  show that the spinal implant structure  200  has a netting  230  mounted thereon.  FIG. 7A  and  FIG. 7B  show that the spinal implant structure  200  is folded.  FIG. 8A  and  FIG. 8B  show that the spinal implant structure  200  has been expanded. The netting  230  restricts the range of flow of the bone cement being perfused into the spinal implant structure  200 , so as to prevent the bone cement from spilling from the vertebral body, allow the spinal implant structure  200  to be uniformly expanded, and reinforce the vertebral body. 
     The netting  230  is hollow-cored and cylindrical in shape. The netting  230  fits around the expansion arm  213  of the spinal implant structure  200  and can unfold as a result of the expansion of the spinal implant structure  200  ( FIG. 8B ). The openings at the two ends of the netting  230  differ in size. The sidewall of the end with a larger opening has at least one engaging hole  231 . The end is engaged with a first part-facing end of the expansion arm  213 . The other end of the netting  230  has a fixing hole  232  of a smaller diameter ( FIG. 8A ). When the spinal implant structure  200  is folded ( FIG. 7B ), one end of the netting  230  is fixed to the expansion arm  213  through the engaging hole  231 , whereas the other end of the netting  230  is bent to be inserted into the spinal implant structure  200 , and in consequence the fixing component  240  is fixed to the second part  212  through the fixing hole  232 . The fixing component  240  is, for example, a screw whose thread enables it to be rotated and inserted into the second part  212 . The outer diameter of the screw&#39;s head is slightly larger than the diameter of the fixing hole  232  of the netting  230 . Hence, the netting  230  is fixed in place between the screw&#39;s head and thread; in other words, the netting  230  is fixed in place at the junction of the fixing component  240  and the second part  212 . The second embodiment differs from the first embodiment in that the netting  230  of the spinal implant structure  200  is steadily engaged between the fixing component  240  and the second part  212  without getting disconnected, and thus when the spinal implant structure  200  is expanded ( FIGS. 8A, 8B ), that is, at the time when the second part  212  moves toward the expansion end  101  under a pushing force and thus moves away from the first part  211 , the netting  230  unfolds as a result of the expansion of the spinal implant structure  200 . 
     Operating Tool 
     The spinal implant structure of the present invention operates in conjunction with an operating tool in order to perform precise operations, such as implantation, expansion, and bone cement perfusion. Embodiments of the operating tool of the present invention are illustrated by  FIG. 9A  through  FIG. 20C .  FIG. 9A  through  FIG. 15A  are schematic views of the operating tool.  FIG. 16A  through  FIG. 18B  are schematic views of the operating tool and the spinal implant structure coupled thereto according to the first embodiment.  FIG. 19A  through  FIG. 20C  are schematic views of the operating tool and the spinal implant structure coupled thereto according to the second embodiment.  FIG. 9A  through  FIG. 15A  show that, although the operating tool connects with the spinal implant structure  100 , the operating tool is also applicable to the spinal implant structure  200  in part or in full. Persons skilled in the art understand that although the operating tool of the present invention varies slightly in structure and shape, depending on whether it is applied to the spinal implant structure  100  or the spinal implant structure  200 , the variations in structure and shape of the operating tool are designed in accordance with operational concepts and relationships disclosed according to the present invention and thus fall within the scope of the present invention. 
     Referring to  FIG. 9A through 15A , the operating tool of the present invention comprises a tool body  310 , a fixing (screw barrel/screw nut) sleeve  320 , a central rod  330 , an operating handle  340 , a converter  350 , a bone cement perfusing sleeve  360 , and a bone cement ejector  370 . The tool body  310 , fixing (screw barrel/screw nut) sleeve  320 , the central rod  330 , operating handle  340 , and converter  350  together constitute the operating tool whereby the spinal implant structure is expanded ( FIG. 16A  through  FIG. 17C  show how the spinal implant structure  100  is folded/expanded;  FIG. 19A  through  FIG. 20C  show how the spinal implant structure  200  is folded/expanded.) The tool body  310 , fixing (screw barrel/screw nut) sleeve  320 , bone cement perfusing sleeve  360 , and bone cement ejector  370  together constitute the tool for perfusing the bone cement upon completion of the expansion of the spinal implant structure  100  ( FIGS. 18A and 18B ). 
     [Tool Body] 
     Referring to  FIGS. 9A and 9B , the tool body  310  serves as a carrier/connector for the operating tool and connects with the spinal implant structure  100 . The tool body  310  comprises a connecting portion  311  and a gripping portion  312 . The connecting portion  311  is a hollow-cored pipe and has a tail  311   a . The tail  311   a  has a jointing structure which can be connected to the spinal implant structure  100  and fixed thereto integrally. This embodiment is exemplified by thread securing. The ways to couple the tool body  310  and the spinal implant structure  100  together include but are not limited to engagement and thread securing; hence, whatever jointing techniques will be applicable to the present invention, provided that the jointing techniques enable the tool body  310  and the spinal implant structure  100  to be firmly connected and easily disconnected. The gripping portion  312  is, for example, a handle to be gripped by a user or placed on another table/support to fix the kit in place. 
     [Fixing (Screw Barrel/Screw Nut) Sleeve] 
     Referring to  FIG. 10A  through  FIG. 10C , wherein  FIG. 10A  and  FIG. 10B  show the fixing (screw barrel/screw nut) sleeve  320  which operates in conjunction with the spinal implant structure  100 , and  FIG. 10C  shows the fixing (screw barrel/screw nut) sleeve  320  which operates in conjunction with the spinal implant structure  200 . The fixing (screw barrel/screw nut) sleeve  320  is a hollow-cored pipe for fitting inside the tool body  310 . For example, the fixing (screw barrel/screw nut) sleeve  320  comprises a fixing screw barrel/screw nut  321  and a sleeve  322 . The fixing screw barrel/screw nut  321  is specially designed (for example, its wall has an opening  323 ) to separate from the sleeve  322  when rotated and stay in the spinal implant structure  100 , and then the sleeve  322  can be taken out of the spinal implant structure  100 . Referring to  FIG. 10A , the fixing screw nut  321  is disconnected from the fixing (screw barrel/screw nut) sleeve  320  to become a screw nut (i.e., a screw nut for fitting around a protruding part of the fixing screw barrel  120 , as described before and shown in  FIG. 1B ) of the spinal implant structure  100  in the first embodiment. Referring to  FIG. 10C , the fixing screw barrel  321  is disconnected from the fixing (screw barrel/screw nut) sleeve  320  to become the fixing screw barrel  220  ( FIG. 5B ) of the spinal implant structure  200  in the second embodiment. The fixing (screw nut/screw barrel)  321  disconnected from the fixing (screw barrel/screw nut) sleeve  320  is adapted to fix the distance between the first part  111 ,  211  and the second part  112 ,  212  in the spinal implant structure  100 ,  200 . 
     [Central Rod] 
     Referring to  FIGS. 11A and 11B , wherein  FIG. 11A  shows a central rod for use with the spinal implant structure  100 , and  FIG. 11B  shows a central rod adapted for use with the spinal implant structure  100  and equipped with a connecting end  330   a  (left end). The central rod  330  is a slender rod for pulling and/or pushing the second part so as to effectuate the expansion of the spinal implant structure. The front end of the central rod  330  has a thread which matches the inner thread of the fixing screw barrel  120  of the spinal implant structure  100 ; hence, the front end of the central rod  330  can be insertedly fastened to the fixing screw barrel  120  and thus connected to the second part  112  of the spinal implant structure  100  through the fixing screw barrel  120  (as shown in  FIG. 1B ). Alternatively, the thread matches the inner thread of the second part  212  of the spinal implant structure  200  and thus is directly, insertedly fastened to the second part  212  of the spinal implant structure  200  (as shown in  FIG. 5B ). 
     [Operating Handle and Converter] 
     Referring to  FIG. 12A through 13B , the operating handle  340  and the converter  350  drive the central rod  330  to move forward/backward so that the spinal implant structures  100 ,  200  are expanded or folded. The operating handle  340  operates by the principle of the lever whereby the user can exert a small force on the converter  350  by means of a long effort arm of the lever. The converter  350  converts the rotational torque exerted by the user into a horizontal, linear pushing/pulling force, so as to not only render the pushing/pulling force uniform but also reduce unnecessary vibration. 
     [Bone Cement Perfusing Sleeve and Bone Cement Ejector] 
     Referring to  FIG. 14A through 15A , the bone cement perfusing sleeve  360  and the bone cement ejector  370  are adapted to perfuse a bone cement, and their operation is illustrated by  FIGS. 19 ) 18 B, which show that their operation entails inserting the bone cement perfusing sleeve  360  directly into the fixing screw barrel (screw nut)  320 , the tool body  310 , and the spinal implant structure  100 , filling the bone cement perfusing sleeve  360  with the bone cement, and finally pushing the bone cement into the spinal implant structure  100  with the bone cement ejector  370 . Hence, the outer diameter of the bone cement ejector  370  substantially equals the inner diameter of the bone cement perfusing sleeve  360  in order for the bone cement to be pushed into the spinal implant structure  100 . 
     [Operation of Operating Tool and Spinal Implant Structure] 
       FIG. 16A  through  FIG. 17C  are schematic views of the operating tool and the spinal implant structure  100  coupled thereto.  FIG. 16A  through  FIG. 16C  are schematic views of the operating tool and the spinal implant structure  100  coupled thereto and folded.  FIG. 17A  through  FIG. 17C  are schematic views of the operating tool and the spinal implant structure  100  coupled thereto and expanded.  FIG. 16C  and  FIG. 17C  are partial enlarged views of the junction of the operating tool and the spinal implant structure. 
     Referring to  FIG. 16C , the tail  311   a  of the connecting portion  311  of the tool body  310  is operated in a manner to be jointed to the first part  111  of the spinal implant structure  100 .  FIG. 16C  is exemplified by thread jointing. The central rod  330  ( FIG. 11A ) is rotated and inserted into the fixing screw barrel  120 . Then, the operating handle  340  and converter  350  ( FIG. 17A, 17B ) are rotated, so as for the central rod  330  to be pulled backward, thereby effectuating the expansion of the spinal implant structure  100 . Referring to  FIG. 17C , upon completion of the expansion of the spinal implant structure  100 , the fixing screw barrel  120  is at a location conducive to its operating the connecting portion  311  of the tool body  310 ; at this point in time, the user can move the fixing screw nut sleeve  320  ( FIGS. 10A, 10B ) of the operating tool leftward so that it fits around the fixing screw barrel  120  and thus gets fixed thereto. After the fixing screw nut sleeve  320  has fitted around the fixing screw barrel  120 , the user rotates it again in the same direction and applies a torque thereto, so as to separate the fixing screw nut  321  and the sleeve  322  and finish the fixation process. 
       FIG. 19A  through  FIG. 20C  are schematic views of the operating tool and the spinal implant structure  200  coupled thereto.  FIG. 19A  through  FIG. 19C  are schematic views of the operating tool and the spinal implant structure  200  coupled thereto and folded.  FIG. 20A  through  FIG. 20C  are schematic views of the operating tool and the spinal implant structure  200  coupled thereto and expanded.  FIG. 19C  and  FIG. 20C  are partial enlarged views of the junction of the operating tool and the spinal implant structure. 
     Referring to  FIG. 19C , the tail  311   a  of the connecting portion  311  of the tool body  310  is jointed to the first part  211  of the spinal implant structure  200  by engagement for exemplary sake. The central rod  330  ( FIG. 11B ) is rotated and inserted into the second part  212 . Then, the operating handle  340  and converter  350  ( FIGS. 19A, 19B ) are rotated so as to push the central rod  330  forward, thereby effectuating the expansion of the spinal implant structure  200 . After the second part  212  has been pushed forward and fixed in place to effectuate the expansion of the spinal implant structure  200 , as shown in  FIG. 20C , the fixing screw barrel sleeve  320  ( FIG. 10C ) rotates and moves forward so that the front end of the fixing screw barrel sleeve  320  abuttingly connects with the second part  212  to fix it in place. At this point in time, the user rotates the fixing screw barrel sleeve  320  again in the same direction and applies a torque thereto, so as to separate the fixing screw barrel  321  and the sleeve  322 , keep the fixing screw barrel  321 , finish the fixation process, and remove the sleeve  322 . 
     Due to the design of the expansion arm and the support arm of the spinal implant structure of the present invention, the spinal implant structure is steadily expanded within the vertebral body. Furthermore, the design of the netting of the spinal implant structure restricts the range of the flow of the bone cement, reduces the likelihood of a failure of vertebroplasty, and reinforces the vertebral body as a result of the expansion of the spinal implant structure. 
     Due to the design of the connection of the operating tool and the spinal implant structure of the present invention, not only are the spinal implant structure and the operating tool coupled together, but the expansion step and the bone cement perfusion step are also stable, thereby increasing the likelihood of successful vertebroplasty and reducing complications. 
     Although the operating tool of the present invention comprises many components, the components are not only easily put together and separated but also embody plenty practical operation-related advantages. When necessary, the user can easily disassemble the operating tool of the present invention and start to operate the spinal implant structure by hand so as to preclude any possible emergency. Therefore, the operating tool and the spinal implant structure of the present invention have advantages neither anticipated of nor achieved by conventional tools for use in vertebroplasty. 
     Although the present invention is disclosed above by embodiments, the embodiments are not restrictive of the present invention. Equivalent implementation of, or equivalent changes made to, the embodiments by persons skilled in the art without departing from the spirit of the present invention must be deemed falling within the scope of the present invention. Accordingly, the legal protection for the present invention should be defined by the appended claims.