Patent Document

BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention concerns a process and a device for treating vertebral bodies. Spinal diseases or diseases of the vertebral body such as osteoporotic vertebral body fractures, matastatic changed vertebral bodies or hemangioma of the spinal cord are treated using known minimally invasive fusing techniques, which stabilize the pathologically changed vertebrae and prevent the pain associated with the illness. 
     2. Related Art of the Invention 
     The conventional process of vertebroplasty includes the percutaneous dorsal introduction of liquid bone cement under pressure into the pathologically changed vertebrae, which, by appropriate positioning of the patient, is in certain cases repositioned. As a consequence of the use of liquid cement and the use of pressure there occurs however in this process routinely the egress of bone cement. If this occurs in the vertebral canal, then neurological consequences, even to the extent of paralysis, may result. Further, cement embolisms may occur in the lung in the case that the bone cement penetrates into the venous system. 
     SUMMARY OF THE INVENTION 
     The invention is thus concerned with the task of providing a process and a device with which an improved carrying out of the vertebroplasty process is made possible. 
     The task is solved by the inventive process for treatment of vertebral bodies according to claim  1  and the inventive device for carrying out the process according to Claim  10 . 
     Advantageous embodiments and further developments of the invention are set forth in the dependent claims. 
     The inventive process for treatment of vertebral bodies includes the following steps: First a trocar jacket is introduced through the skin into the vertebral body with the assistance of a trocar. The trocar is subsequently removed. Subsequently a biopsy and cement cannula is introduced into the trocar jacket, spongiosa is drawn into the biopsy and cement cannula, and the biopsy and cement cannula is then removed from the trocar jacket. A biopsy and cement cannula, which is filled with bone cement, is subsequently introduced into the trocar jacket. Finally the bone cement is introduced into the vertebral body, in that a plunger is introduced into the biopsy and cement cannula, which presses the bone cement located in the biopsy and cement cannula out of the distal end of the biopsy and cement cannula. 
     The advantage of this process lies therein, that in contrast to the introduction of liquid bone cement with a hypodermic needle, in which the bone cement is pressed with pressure through a narrow needle, in the present case, by the targeted metered or dosed dispensing with use of the plunger, bone cement can be introduced into the vertebral body without having to force the bone cement with high pressure into the vertebral body, so that the danger of the emission of bone cement into the vertebral canal or the veinous system is reduced. By the removal of at least parts of the spongiosa by means of the biopsy and cement cannula, a hollow space is produced in the vertebral body, into which the bone cement can subsequently be introduced. 
     The production of a hollow space, in which at least parts of the spongiosa is withdrawn from the vertebral body, has the advantage, that during the filling in of the bone cement no pressure would be exercised upon the vertebral body; further, diseased parts of the spongiosa can be completely removed and no longer remain in the vertebral body. In particular, it is achieved thereby, that since a hollow space is produced first, there results a good distribution of the bone cement in the area of the vertebral body, with good biomechanical anchoring. 
     In a particularly advantageous further development of the inventive process the bone cement is introduced in a pasty or semi-fluid condition into the vertebral body. It is precisely the processing of liquid bone cement under high pressure that presents itself as the main risk in the known process of vertebroplasty, since the liquid bone cement is particularly susceptible to being emitted into the vertebral canal or the veinous system. However, the use of a biopsy and cement cannula, from which the bone cement is dispensed by means of a plunger, makes possible the use of viscous bone cement. The viscous bone cement can ideally distribute itself in the vertebral body and there presents a very low risk of complication with respect to the emission of the cement out of the vertebral body. 
     Preferably, two biopsy and cement cannulas are introduced into the vertebral body via two trocar jackets. Thereby, a larger area of the inner space of the vertebral body is accessed, from which the spongiosa can be removed and bone cement introduced, whereby the vertebral body can be better stabilized. In order to reach the inner space of the vertebral body particularly effectively with two trocar jackets, two trocar jackets are preferably introduced symmetrically into the vertebral body. 
     Preferably the at least one trocar jacket is introduced into the vertebral body by a transpedicular approach, since this makes possible the most advantageous access to the vertebral body and to the inner space of the vertebral body. In particular, it becomes possible thereby to avoid damage of the nerve roots, which could possibly occur in the case of an extrapedicular access. 
     Preferably the plunger exhibits markings which correspond to the volume of the bone cement to be introduced into the vertebral body. If the plunger is introduced step for step in the biopsy and cement cannula, then it can be determined, on the basis of the markings provided on the outer circumference of the plunger, how much bone cement has already been expelled from the distal end of the biopsy and cement cannula and filled into the vertebral body. 
     Preferably the process is carried out at least section-wise using computer navigation and/or X-ray image control, in order to monitor the positioning of the trocar and the trocar jacket and/or the filling with bone cement and, as necessary, to make corrections. Preferably thus the entire procedure occurs under computer navigation and/or X-ray image control. 
     The inventive device for treatment of the vertebral body, in particular for use in the inventive process, includes at least one biopsy and cement cannula, which is fillable with bone cement, and a plunger, which is introducible into the biopsy and cement cannula. If the plunger is introduced step for step into the biopsy and cement cannula, then the bone cement is carefully extruded from the biopsy and cement cannula. This makes possible a dosed or metered extrusion of bone cement, with which in particular also viscous bone cement can be introduced into the inside of the vertebral body, which significantly reduces the risk of a cement leaving the target area and therewith associated damage in comparison to the introduction of liquid bone cement by means of a forced injection technique. 
     Preferably the plunger is in the form of a cylindrical rod with a knob on the proximal end, wherein the length of the cylindrical rod corresponds to the total volume of the biopsy and cement cannula. If the plunger is thus completely introduced into the biopsy and cement cannula, the distal end of the cylindrical rod comes into registry with the distal end of the biopsy and cement cannula. An introduction of the plunger beyond the length of the biopsy and cement cannula, which could lead to a damaging of the vertebral body, is therewith reliably prevented. 
     Preferably the outer diameter of the cylindrical rod of the plunger corresponds to the inner diameter of the biopsy and cement cannula. If the plunger is thus introduced into the biopsy and cement cannula, then the bone cement located therein and occupying this volume is completely displaced, thereby making possible a precise metering and dispensing of the amount of bone cement introduced into the inner space of the vertebral body. In particular, during the introduction of the plunger into the biopsy and cement cannula, no bone cement can exit at the proximal end of the biopsy and cement cannula. The metered dispensing is further made possible thereby, that the plunger exhibits markings on its outer circumference, which correspond to the volume of bone cement to be introduced into the vertebral body. 
     In an advantageous further development of the invention the biopsy and cement cannula also exhibits equidistant markings on its outer circumference. These serve to make it possible to determine how far the biopsy and cement cannula was inserted into the trocar jacket, in order to prevent that the biopsy and cement cannula is introduced too far into the inner space of the vertebral body, which could lead to a damaging of the vertebral body. 
     Preferably two biopsy and cement cannulas are employed, in order to improve the access to the inner space of the vertebral body and to make possible a more even filling of a greater area of the inner space of the vertebral body with bone cement. 
     Preferably the device includes a trocar and a trocar jacket. These are preferably coordinated in their dimensions to the biopsy and cement cannula, in order to make possible an optimal engagement. 
     Preferably the trocar is in the form of a cylindrical rod with a knob provided on the proximal end and a trocar tip provided on the distal end, wherein the length of the cylindrical rod without the trocar tip corresponds to the total length of the trocar jacket. The trocar can therewith be introduced into the trocar jacket to the extent that only the trocar tip projects beyond the trocar jacket. In this condition trocar and trocar jacket can be introduced into the vertebral body in a particularly simple manner. 
     In an advantageous embodiment of the invention the outer diameter of the cylindrical rod of the trocar corresponds to the inner diameter of the trocar jacket. Thereby a form-fitting seal between the cylindrical rod of the trocar and the trocar jacket is achieved, whereby the trocar, inclusive of the trocar jacket, allows itself to be introduced into the vertebral body in simple manner. 
     Preferably the trocar jacket exhibits markings on its outer circumference. Using these markings it can be read how far the trocar jacket has been introduced into the vertebral body. 
     Preferably the inner diameter of the trocar jacket corresponds to the outer diameter of the biopsy and cement cannula. Therewith also the biopsy and cement cannula can be introduced almost without play into the trocar jacket. Further, the outer dimensions of the trocar jacket are kept as small as possible, in order to make possible a gentle engagement with the vertebral body. 
     In a preferred further development of the invention the trocar is capable of computer navigation. For this it includes in particular connections for a navigation adapter. This enables a particularly safe introduction of the trocar into the vertebral body, whereby damage of the vertebral body can be substantially avoided. 
     Preferably the trocar includes on its knob a steel ring, preferably with connections for an X-ray target device. Otherwise the knob is comprised of a material, which is transparent for X-rays. Therewith, the introduction of the trocar inclusive of the trocar jacket can occur under X-ray image control, whereby in particular by the use of an X-ray target device a precise positioning of the trocar inclusive of the trocar jacket is made possible and damage to the vertebral body is avoided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An illustrative embodiment of the invention is described in the following in greater detail on the basis of figures. There is shown in: 
         FIG. 1   a  a side view through a lumbar vertebrae, in which a trocar jacket was introduced transpedicularly; 
         FIG. 1   b  a side view according to Line A-A in  FIG. 1   a;    
         FIG. 2   a  a side view through a lumbar vertebrae in which a trocar jacket was introduced extrapedicularly; 
         FIG. 2   b  a section along the Line B-B in  FIG. 2   a;    
         FIG. 3   a  a side view through a thoracic vertebrae, in which a trocar jacket was introduced transpedicularly; 
         FIG. 3   b  a section along Line C-C in  FIG. 3   a;    
         FIG. 4   a  a side view through a thoracic vertebrae, in which a trocar jacket was introduced transpedicularly; 
         FIG. 4   b  a section along the Line D-D in  FIG. 4   a;    
         FIG. 5  a view of a trocar; 
         FIG. 6  a view of a trocar jacket; 
         FIG. 7  a schematic representation of the process steps of the introduction of a trocar jacket in the vertebral body; 
         FIG. 8  a schematic representation of the process steps of the introduction of a trocar jacket in the vertebral body; 
         FIG. 9  a schematic representation of the process steps of the introduction of two biopsy and cement cannulas in a trocar jacket; 
         FIG. 10  a schematic representation of the process steps of the drawing in of spongiosa into the biopsy and cement cannulas; 
         FIG. 11  a schematic representation of the vertebral body, in which the spongiosa was partially removed; 
         FIG. 12  a view of the biopsy and cement cannula; 
         FIG. 13  a view of a plunger; 
         FIG. 14  a schematic representation of the process step of the removal of the biopsy sample from the biopsy and cement cannula; 
         FIG. 15  a schematic representation of the process step of the filling of the bone cement into a syringe; 
         FIG. 16  a schematic representation of the process step of the filling of the bone cement into the biopsy and cement cannula; 
         FIG. 17  a schematic representation of the biopsy and cement cannula with plunger seated; 
         FIG. 18  a schematic representation of the biopsy and cement cannula introduced into the trocar jacket with seated plunger; 
         FIG. 19  a schematic representation of the process step of the filling in of the bone cement in the vertebral body; 
         FIG. 20  a schematic representation of the vertebral body following the filling in process according to  FIG. 19 ; 
         FIG. 21  a schematic representation of the vertebral body with removed biopsy and cement cannulas; 
         FIG. 22 . a schematic representation of the vertebral body with introduced bone cement; 
         FIG. 23  a side view of a trocar according to one embodiment of the inventive device; 
         FIG. 24  a side view of a trocar jacket according to one illustrative embodiment of the inventive device; 
         FIG. 25  a side view of a biopsy and cement cannula according to an illustrative embodiment of the inventive device; and 
         FIG. 26  a side view of the plunger according to one illustrative embodiment of the inventive device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First, an illustrative embodiment of the inventive device according to  FIGS. 23 through 26  is described in greater detail, in order to be able to subsequently describe the use of the inventive device in the inventive process on the basis of  FIGS. 1 through 22 . 
       FIG. 23  shows a side view of a trocar  10  with a cylindrical rod  12  and a knob  16  provided on the proximal end of the rod  12  of a material which is transmissive for X-rays. The distal end of the rod  12  includes a trocar tip  14 . The rod  12  exhibits, inclusive of the trocar tip  14 , a length L 1  of approximately 170 mm, wherein the trocar tip  14  has a length of approximately of 5 mm, and an outer diameter d 1  of approximately 3.5 mm. At the transition between the cylindrical rod  12  and the knob  16  there are two connections  17   a ,  17   b  for a (not shown) navigation adapter. On the knob end there is a steel ring  18 , which serves as X-ray target device. 
     The trocar  10  is introducible in a trocar jacket  20 , which is shown in a side view in  FIG. 24 . The trocar jacket  20  includes a jacket  22  and a grip  24  provided on the proximal end of the jacket  22  of likewise X-ray transmissive material. The jacket  22  is defined by a cylindrical rod with an outer diameter d 2   a  and an inner diameter d 2   i . Therein the inner hollow space of the jacket  22  continues through the grip  24 , so that the trocar  10  can be introduced through the grip  24  into the jacket  22  of the trocar jacket  20 . The outer diameter d 2   a  of the jacket  22  is approximately 4.2 mm. The inner diameter d 2   i  of the jacket  22  corresponds approximately to the outer diameter d 1  of the rod  12  of the trocar  10 , is however slightly larger, so that trocar  10  can be introduced, and is approximately 3.6 mm. The total length L 2  of the trocar jacket  20  is 165 mm and corresponds therewith approximately to the length L 1  of the cylindrical rod  12  of the trocar  10  without the length of the trocar tip  14 . If the trocar  10  is introduced through the grip  24  into the trocar jacket  20  until the knob  16  bumps on the grip  24 , then only the trocar tip  14  projects out of the jacket  22  from the distal end of the trocar jacket  20 . 
     On the outer circumference of the trocar jacket  20  circumscribing markings  26  are provided. Preferably these markings are provided equidistant. In the present illustrative embodiment the distance of the markings  26  indicate approximately 10 mm. On these markings  26  it can be read, during the introduction of the trocar  10  inclusive of the trocar jacket  20  into the body of the patient, how far the trocar jacket  20  has already been introduced and in particular how far into the vertebral body. 
       FIG. 25  shows a side view of a biopsy and cement cannula  30  with a jacket  32  in the form of a cylindrical pipe and a grip  34  provided at the proximal end. The biopsy and cement cannula  30  exhibits a total length L 3  of approximately 210 mm. The jacket  32  of the biopsy and cement cannula  30  exhibits an outer diameter d 3   a  and an inner diameter d 3   i . Therein the inner hollow space continues through the grip  34 . The outer diameter d 3   a  of the biopsy and cement cannula  30  is approximately 3.5 mm and corresponds approximately to the inner diameter d 2   i  of the trocar jacket  20 , but is however slightly smaller in dimension, so that the biopsy and cement cannula  30  can be introduced into the trocar jacket  20 . The inner diameter d 3   i  of the biopsy and cement cannula  30  is approximately 3.1 mm. 
     The biopsy and cement cannula  30  exhibits circumscribing markings  36  beginning at the grip  34  located at the proximal end of the jacket  32 , which markings are preferably provided equidistant. In the present illustrative embodiment the markings  36  are provided at a spacing of approximately 10 mm. On the basis of the markings  36  it can be read, how far the biopsy and cement cannula  30  has been introduced into the trocar jacket  20 . The length L 3  of the biopsy and cement cannula  30  is significantly greater, for example approximately a quarter of the length L 3  greater, than the length L 2  of the trocar jacket  20 . This makes is possible that the distal end of the jacket  32  of the biopsy and cement cannula  30  projects also beyond the distal end of the jacket  22  of the trocar jacket  20 , so that the biopsy and cement cannula  30  can be introduced further into the vertebral body than the trocar jacket  20 . On the markings  36  it can thereby be precisely read, how far the distal end of the jacket  32  projects beyond the distal end of the jacket  22  of the trocar jacket  20  (distal end of the jacket  32  of the biopsy and cement cannula  30 ). 
     In  FIG. 26  an illustrative embodiment of a plunger  40  is shown, which includes a cylindrical rod  42  of the length L 4  and a knob  44  joining on the proximal end of the rod  42 . The rod  42  exhibits an outer diameter d 4 , which is approximately 3 mm and therewith corresponds to approximately the inner diameter d 3   i  of the biopsy and cement cannula  30 , however is dimensioned slightly smaller, so that the plunger  40  and the biopsy and cement cannula  30  can be introduced. 
     The plunger  40  exhibits circumscribing markings  46  on the cylindrical rod  42 , which are preferably provided equidistant spaced. In the present illustrative embodiment these are provided beginning at the distal end of the rod  42  and spaced approximately 70 mm apart. On the basis of the outer diameter of approximately 3 mm, such markings  46  with a spacing of 70 mm characterize a volume of approximately 0.5 cm 3 . As the plunger  40  is introduced into a bone cement filled biopsy and cement cannula  30 , the volume of the bone cement extruded from the distal end of the biopsy and cement cannula  30  can be read on the basis of the markings  46 . If for example the plunger  40  is introduced by two markings  46  into the biopsy and cement cannula  30 , there is expelled from the biopsy and cement cannula  30 , which was completely filled with bone cement  60 , a volume of approximately 1 cm 3  of bone cement  60  out of the distal end of the biopsy and cement cannula and into the vertebral body. 
     The length L 4  of the rod  42  is approximately 210 mm and corresponds therewith approximately to the total length L 3  of the biopsy and cement cannula  30 . Therewith the plunger  40  can be completely pushed through the grip  34  into the biopsy and the cement cannula  30 , until the knob  44  of the plunger  40  bumps on the grip  34  of the biopsy and cement cannula  30 , and the distal end of the plunger  40  joins in this position sealingly with the distal end of the biopsy and cement cannula  30 . Thereby it is ensured that the full volume of the bone cement is extruded out of the biopsy and cement cannula  30  and is emptied into the inside of the vertebral body. 
     In the following on the basis of  FIGS. 1 through 22  the use of the illustrative embodiment of the inventive device with trocar  10 , trocar jacket  20 , biopsy and cement cannula  30  and plunger  40  is described in the inventive process. 
     In  FIGS. 1   a  through  4   b  there is represented respectively a vertebral body  70  with pedicles  72  in the side view ( FIGS. 1   a ,  2   a ,  3   a  and  4   a ) as well as a vertical section ( FIGS. 1   b ,  2   b ,  3   b  and  4   b ). The vertebral body  70  shown in  FIGS. 1   a  through  2   b  is a lumbar vertebra while in  FIGS. 3   a  through  4   b  a thoracic vertebra is shown.  FIGS. 1   a  through  4   b  show how the trocar jacket  20  is introduced into the vertebral body  70 . In  FIGS. 1   a ,  1   b ,  3   a  and  3   b  the transpedicular access is shown, and in  FIGS. 2   a ,  2   b ,  4   a  and  4   b  the extrapedicular access is shown. Preferably in the following process the trocar jacket  20  is introduced transpedicularly into the vertebral body  70 , since this simplifies the access to the vertebral interior. In particular in this way damage to the nerve roots, which could possibly occur in the case of extrapedicular access, can be avoided. 
       FIGS. 5 and 6  show the instruments employed in the first process step, namely the trocar  10  according to  FIG. 23  as well as the trocar jacket  20  according to  FIG. 24 . The trocar  10  is slid into the trocar jacket  20 , until the knob  16  of the trocar  10  bumps against the grip  24  of the trocar jacket  20 , so that the trocar tip  14  projects from the distal end of the trocar jacket  20 . The trocar  10  inclusive of the trocar jacket  20  is, as shown in  FIG. 7 , after exposing the access to the vertebral body  70 , is introduced percutaneously dorsally and transpedicularly by careful hammering with a hammer  55  into the vertebral body  70 , until the distal end of the trocar jacket  20  projects straight into the inner space of the vertebral body  70 . This position can be determined on the basis of computer navigation and/or an X-ray imaging control or guidance, whereby supplementally an X-ray target device is employed. Preferably the entire process occurs under computer navigation and/or X-ray image control, in order to be able to control each process step. The computer navigation preferably occurs during the introduction of the trocar  10 , in order to monitor the correct positioning of the trocar  10 . In further progress of the process this can be dispensed with. From this point on preferably at least an X-ray image control is used during the complete process. If no data for computer navigation is available, then preferably two X-ray image controllers are employed. 
     As shown in  FIG. 8 , a second trocar jacket  20  is introduced likewise transpedicularly symmetrically to the first trocar jacket  20 . 
       FIG. 9  shows how subsequently in each of the trocar jackets  20  respectively one biopsy and cement cannula  30  according to  FIG. 25  is introduced. By the light tapping with a hammer  55  respectively right and left the biopsy and cement cannulas  30  are driven through the trocar jacket  20  up to the front edge of the vertebral body  70 . On the markings  36  of the biopsy and cement cannula  30  it can be read how far the biopsy and cement cannula  30  was introduced into the trocar jacket  20 . Since the length L 3  of jacket  32  of the biopsy and cement cannula  30  is larger than the length L 2  of the jacket  22  of the trocar jacket  20 , the distal end of the biopsy and cement cannula  30  can be pushed out beyond the distal end of the trocar jacket  20 . On the basis of the markings  36  it is monitored, that the distal end of the biopsy and cement cannula  30  projects only so far beyond the distal end of the trocar jacket  20  that it lies almost at the inner surface of the inner space of the vertebral body  70  lying opposite to the entry opening (see  FIG. 9 ). The two biopsy and cement cannulas  30  transcend therewith essentially the inner space of the vertebral body  70 . 
       FIG. 10  shows that a syringe  50  is seated upon the two grips  34  of the biopsy and cement cannulas  30 , with which, by aspiration, spongiosa  74  from the inside of the vertebral body  70  is withdrawn through the biopsy and cement cannula  30 . Therein simultaneously also the biopsy and cement cannulas  30  are pulled so far out of the trocar jacket  20 , until approximately the distal end of the biopsy and cement cannulas  30  close the distal end of the trocar jacket  20 , so that two essentially cylindrical hollow spaces  78  are produced in the inside of the vertebral body  70  (see  FIG. 11 ). The hollow spaces  78  thereby have, in a lumbar vertebrae, a length of for example approximately 25 mm and a diameter of approximately 3 mm. The production of the hollow spaces  78  simplifies and facilitates the introduction of the bone cement  60 , which can distribute itself ideally in the hollow spaces, whereby the risk of a bone cement extrusion out of the vertebral body is reduced. Subsequently the two biopsy and cement cannulas  30  are removed from the trocar jacket  20  (See  FIG. 11 ). 
     In  FIGS. 12 through 14  it is shown that the biopsy and cement cannula  30  of the plunger  40  according to  FIG. 26  is introduced, in order to push the obtained biopsy sample  76  out of the biopsy and cement cannula  30 . The biopsy sample  76  can in certain cases be used for histological examination. 
     The term “bone cement”  60  is used in the following to refer to any material which is suited for stabilizing a bone, in particular a vertebral body. In particular, polymethyl-methacrylate (PMMA) or potassium phosphate cement can be employed as materials. 
     Subsequently the viscous bone cement  60  is filled into the biopsy and cement cannula  30 . Thereby either the biopsy and cement cannula  30 , with which the spongiosa  74  was withdrawn and which was subsequently cleaned, or an identically dimensioned or designed further biopsy and cement cannula  30  can be employed. In order to ensure that the biopsy and cement cannula  30  is completely filled, bone cement  60  is preferably filled in with the syringe  50  so long until this is emitted from the distal end of the biopsy and cement cannula  30  (See  FIG. 16 ). This surplus or overspill of bone cement  50  is subsequently removed. Next, the plunger  40  is seated upon the proximal end of the biopsy and cement cannula  30  (See  FIG. 17 ) and the biopsy and cement cannula  30  with seated plunger  40  is introduced into the trocar jacket  20  (See  FIG. 18 ). Alternatively however also first the biopsy and cement cannula  30  can be introduced into the trocar jacket  20  and subsequently the plunger  40  can be seated upon the proximal end of the biopsy and cement cannula  30 . The biopsy and cement cannula  30  are next introduced so far into the trocar jacket  20 , that the distal end of the biopsy and cement cannula  30  projects beyond the distal end of the trocar jacket  20  and almost lies against the oppositely lying inner wall of the vertebral body (See  FIG. 18 ). 
     In  FIG. 19  the process step of the filling of the inner space of the vertebral body  70  with bone cement  60  is shown. The bone cement  60  is filled through the vertebral body  70 , so that the plunger  40  is slowly advanced stepwise in the biopsy and cement cannula  30 , while the biopsy and cement cannula  30  is stepwise extracted from the vertebral body  70 . On the basis of the markings  36  on the biopsy and cement cannula  30  it can be monitored how far the biopsy and cement cannula  30  still projects into the inner space of the vertebral body  70 , while on the basis of the markings  46  on the plunger  40  it can be checked how much bone cement  60  has already be filled into the vertebral body  70 . The biopsy and cement cannula  30  is extracted from the trocar jacket  20  to the extent until the distal end of the biopsy and cement cannula  30  is in registry with or closes the distal end of the trocar jacket  20 . This process step in particular is preferably monitored by X-ray image control, in order to be able to check the introduction of the bone cement  60  at each point and time and in certain cases to immediately terminate the filling in the case that bone cement  60  is emitted from the vertebral body  70 . 
     In the same manner also via the second trocar jacket and the second biopsy and cement cannula  30  bone cement  60  is filled into the vertebral body  70  (See  FIG. 20 ), while the first biopsy and cement cannula  30  remains in its position. If the necessary amount of the bone cement  60  is filled in, then the trocar jacket  20 , the biopsy and cement cannulas  30  as well as the plunger  40  remain in the vertebral body  70  so long until the bone cement  60  is completely set. Subsequently, the plunger  40 , the biopsy and cement cannulas  30  as well as the trocar jacket  20  are sequentially removed (See  FIG. 21 ). 
     In  FIG. 22  the final result of the operation is shown, which shows the vertebral body  70  with introduced bone cement  60 . By the inventive process first a hollow space  78  is produced, in which viscous bone cement  60  from the biopsy and cement cannula  30  is pushed in with the assistance of the plunger  40  without pressure, whereby the risk of an emission of bone cement  60  out of the vertebral body  70  is significantly reduced. 
     REFERENCE LIST 
     
         
           10  Trocar 
           12  Rod 
           14  Trocar Tip 
           16  Knob 
           17   a  Connection for navigation adapter 
           17   b  Connection for navigation adapter 
           18  Steel ring 
           20  Trocar jacket 
           22  Jacket 
           24  Grip 
           26  Marking 
           30  Biopsy and cement cannula 
           32  Jacket 
           34  Grip 
           36  Marking 
           40  Plunger 
           42  Rod 
           44  Knob 
           46  Marking 
           50  Syringe 
           55  Hammer 
           60  Bone Cement 
           70  Vertebral body 
           72  Pedicle 
           74  Spongiosa 
           76  Biopsy sample 
           78  Hollow space 
         L 1  Length (of the cylindrical rod of the trocar) 
         L 2  Length (of the trocar jacket) 
         L 3  Length (of the biopsy and cement cannula) 
         L 4  Length (of the cylindrical rod of the plunger) 
         d 1  Outer diameter (of the cylindrical rod of the trocar) 
         d 2   a  Outer diameter (of the trocar jacket) 
         d 2   i  Inner diameter (of the trocar jacket) 
         d 3   a  Outer diameter (of the biopsy and cement cannula) 
         d 3   i  Inner diameter (of the biopsy and cement cannula) 
         d 4  Outer diameter (of the cylindrical rod of the plunger)

Technology Category: 1