Abstract:
A precision depth guided instrument, such as a Jamshidi needle, is provided for use in various surgeries related to the vertebrae. The instrument includes an outer cannula, an inner cannula and a stylet. After the cortical bone of a vertebra is penetrated by the outer cannula of the instrument, the depth of penetration of the inner cannula is adjusted by rotation of a stop mounted to the outer cannula. The inner cannula is then moved further into the vertebrae, and a stop mounted on the outer cannula controls the depth of penetration of the inner cannula. The correct depth of penetration is determined by radiography prior to the procedure.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 USC 119(e) to the U.S. Application No. 61/448,030, filed Mar. 1, 2011, entitled, “Depth Controlled Jamshidi Needle”, the contents of which are incorporated herein in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to instruments employed for controlling accurate placement of devices, such as Jamshidi needles, used in spinal surgery. In particular, the present invention enables a surgeon to accurately control the depth into the vertebrae that devices used in spinal surgery will be placed. 
     BACKGROUND OF THE INVENTION 
     Medical procedures involving the vertebrae are normally complicated because of the preciseness and accuracy required to avoid both neural damage and injury to major blood vessels. Precision depth guided instruments are required to perform percutaneous spinal surgery. These surgeries sometimes require penetration of the hard cortical bone of the vertebra and traversal of the softer cancellous bone lying thereunder. A large force is normally required by the surgeon to penetrate the cortical bone. Once the cortical bone is penetrated, extreme care must then be taken to avoid rapidly penetrating through all of the cancellous bone. There is also the danger of rapidly passing through the cancellous bone and then through the cortical bone on the other side of the vertebra. This can result in injury or damage to the spinal cord and/or other organs or blood vessels located adjacent the spine. In some instances, the force required to penetrate the cortical bone is greater than a surgeon can apply by hand. In these instances a hammer or other similar instrument is required to force the instrument through the cortical bone. When a hammer or similar instrument is used, there is a greater danger of the instrument passing rapidly through the cancellous bone and out the other side of the vertebra. 
     DESCRIPTION OF THE PRIOR ART 
     U.S. Pat. No. 5,458,579 discloses an apparatus for inserting a trocar/cannula assembly through a wall of an anatomical cavity of an individual. The apparatus includes a housing for holding the trocar/cannula assembly, a device for driving the trocar/cannula assembly into the individual, a spine and a depth stop element mounted on the spine to control the depth which the trocar/cannula assembly is inserted into the individual. 
     U.S. Pat. No. 6,033,411 discloses a depth guided instrument for use in performing percutaneous implantation of hard tissue implant materials. A depth guided stylet includes a point adapted for piercing hard tissue and self-tapping threads for self tapping into hard tissue. The instrument also includes a cannula surrounding the stylet which employs a pawl and rack of gear teeth to assist passing the cannula through the hard tissue. 
     U.S. Pat. No. 7,678,077 discloses an instrument for injecting therapeutic and other agents into an individual at a target site. The instrument includes a catheter having a first elongate shaft and a second elongate shaft slidingly disposed within the first shaft. An indicator is secured to an end of the second elongate shaft and moves relative to a scale to indicate the position of the first and second shafts relative to their insertion into an individual. 
     None of the above noted prior art devices permit the operator of the device to adjust the depth of penetration of the Jamshidi needle or cannula based on information obtained from a patient prior to surgery. The depth of penetration can be adjusted depending on the point of entry into the body of the Jamshidi needle or cannula. 
     SUMMARY OF THE INVENTION 
     A precision depth guided instrument, such as a Jamshidi needle, is provided for use in various surgeries related to the vertebrae. The instrument includes an outer cannula, an inner cannula and a stylet. After the cortical bone of a vertebra is penetrated by the outer cannula of the instrument, the depth of penetration of the inner cannula is adjusted by rotation of a stop mounted to the outer cannula. The inner cannula is then moved further into the vertebrae, and a stop mounted on the outer cannula controls the depth of penetration of the inner cannula. The correct depth of penetration is determined by radiography prior to and during the procedure. 
     Accordingly, it is an objective of the instant invention to provide a device which can be inserted into a patient to an exact location. 
     It is a further objective of the instant invention to provide a device which can be inserted into a vertebra and then a portion of the device controllably moved to an exact location within the vertebra. 
     It is yet another objective of the instant invention to provide a device which can be inserted into a vertebra a measured distance, the measured distance having been predetermined by radiography. 
     It is a still further objective of the invention to provide a device which can be inserted into a vertebra an exact distance without any danger of exceeding the desired distance. 
     Other objects and advantages of this invention will become apparent from the following description taken in conjunction with any accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. Any drawings contained herein constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a perspective view of the invention with the components partially spaced from each other; 
         FIG. 2  is an exploded view of the present invention; 
         FIG. 3  is a view of the invention prior to insertion into a patient; 
         FIG. 4  is a view of the invention after an inner cannula has been moved further into a vertebra; 
         FIG. 5  is a view of the end portion of the present invention illustrating the relationship of the two cannulae and needle; 
         FIG. 6  is a top view of a handle into which a needle is inserted; 
         FIG. 7  is a cross sectional view of the present invention in a vertebra; 
         FIG. 8  is a perspective view of an alternate embodiment of the invention in a position similar to  FIG. 3 ; 
         FIG. 9  is a perspective view of an alternate embodiment of the invention in a position similar to  FIG. 4 ; 
         FIG. 10  is a perspective view of an alternative embodiment of the invention including an optional stop; and 
         FIG. 11  is a perspective view of the invention of  FIG. 1  including an optional stop. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred, albeit not limiting, embodiment with the understanding that the present disclosure is to be considered an exemplification of the present invention and is not intended to limit the invention to the specific embodiments illustrated. 
       FIGS. 1-11 , which are now referenced, illustrate the present invention and the manner in which it is assembled. Like reference numerals refer to like components in the various figures. The needle depth controlled Jamshidi assembly  10  comprises a Jamshidi-type needle  12 , and an outer cannula assembly  14 . The Jamshidi-type needle  12  is slidably disposed within the outer cannula assembly  14 . The Jamshidi-type needle  12  includes a cannula  16  which is secured to a handle  18 . The handle  18  includes a collar or cylindrical portion  20 . This cylindrical portion  20  is fixedly secured to the cannula  16 . The handle  18  preferably has an ergonomic shape that can comfortably fit into a surgeon&#39;s or medical technician&#39;s hand. The handle includes an upper  15  curved portion which is shaped to conform to an individual&#39;s palm. The lower portion of the handle  18  is also curved. The curve of the lower portion of the handle is designed to be grasped by the fingers of an individual to assist in the control of the Jamshidi-type needle  12 . The handle  18  is used to drive the cannula into, and sometimes through bones of a vertebra. Sometimes the Jamshidi-type needle  12  can be driven through the bone only by using pressure exerted by an individual&#39;s hand. Other times a hammer or other instrument must be employed to drive the needle  12  through a bone. There is a risk that, when a hammer or similar instrument is utilized, the Jamshidi-type needle  12  will pass too far into a vertebra. This can cause damage to nerves located nearby. Sometimes the needle passes completely through the vertebra and injures an adjacent blood vessel or internal organ. To prevent this, the present invention utilizes a second cannula  14  which is adjustably secured to the Jamshidi-type needle  12  to provide controlled linear traversal of the Jamshidi-type needle within the outer cannula assembly  14 . 
     A needle  22  is slidably positioned within the cannula  16  of the Jamshidi-type needle  12 . The preferred embodiment of the present invention illustrates the needle  22  as having a conical tip  24  ( FIGS. 5 ). However, other tips and needles can also be employed. For example, a trocar needle  22  can be utilized. The tip  24  can be tapered, hollow, etc. The tip can be utilized to extract a tissue sample. It can also be utilized to anchor the needle  22  to a bone. An orthopedic bone screw or other device can then be passed down the needle  22  and secured to the correct location on a bone. While the preferred embodiment of the present invention discloses a relatively rigid needle  22 , other needles which are flexible can also be employed. 
     The outer cannula  14  comprises an upper portion  26  secured to a cannula  28  ( FIG. 2 ). The upper portion  26  comprises a handle or grip  30  and a threaded sleeve  32 . In the preferred embodiment of the outer cannula, the handle  30  and the threaded sleeve  32  are fixedly secured to each other. In other embodiments, these elements can be pivotably or removably secured to each other. The lower or second end  34  of the outer cannula  14  is constructed and arranged to penetrate and pass through bone. While the lower end  34  is normally a hollow tube with an end that tapers to a sharp edge, other edges can also be employed. For example, the edge can be serrated, saw toothed or sinusoidal. The smooth edge is preferably utilized when the needle assembly is driven straight into or through a bone. The serrations or waves are employed when additional effort is required to penetrate a bone. The handle or grip  30  is preferably provided with apertures  31  into which a surgeon&#39;s fingers can be inserted to control the device. 
       FIG. 7  illustrates an example of one of the uses of the present invention. The outer cannula  14 , the cannula  16  and the tip  24  of the needle  22  are passed through a cortical bone  36  of a vertebra  38  and into the cancellous bone  40 . A sample of the cancellous bone may now be taken. In another situation, the needle  22  may be passed into the cortical bone  36  opposite the point of insertion into the vertebra. In these different situations it is very difficult for a surgeon or medical technician to judge the depth of penetration of the depth controlled Jamshidi type needle  10  into the vertebra. The remedy for this problem lies in the present invention. First, a radiography image of the vertebra being operated upon is taken. Next, the depth into the vertebra that the surgeon wants the needle to penetrate is measured or estimated. 
     The Jamshidi-type needle  12  of the present invention includes a threaded nut  42  or similar device which is rotatably secured to the cannula  16  by a bearing. The threads on the nut  42  match the threads on the sleeve  32 . After the surgeon inserts the needle into a patient and through the cortical bone  36  of a vertebra, the cannula  16  is inserted further into the vertebra by rotating the nut  42 . Rotation of the nut  42  moves the cannula and needle  22  further into the vertebra. The distance that these elements are moved can be measured along the threaded sleeve. The distance the needle needs to travel into the vertebra, which has been determined by radiography, will be measured along sleeve  32 . Preferably a mark or indicia  33  is then placed on sleeve  32 . 
     The surgeon or medical technician can now rotate the nut  42  until it reaches the desired mark of indicia on sleeve  32 . At this point, the cannula  16  and needle  22  are now exactly where they need to be positioned. The nut can be rotated by hand or with a wrench or similar device. The wrench may be utilized if a relatively hard bone is to be penetrated by the device. 
     In an alternate embodiment, the nut  42  is fixedly secured to the collar  20  and handle or grip  30 . In this embodiment the handle  30  is rotated, which in turn rotates the collar  20  and nut  42 . This moves the cannula  16  further into the vertebra until the desired position is reached. Rotation of handle  30  permits additional torque to be applied to the nut  42 , and in certain instances does not required the use of a wrench or similar tool. 
       FIG. 3  illustrates the position of the elements of the invention prior to rotation of nut  42 . The end of cannula  16  is adjacent the end  34  of the outer cannula. The tip  24  of the needle  22  protrudes slightly past this point. As illustrated in  FIG. 4 , after nut  42  is rotated, the inner cannula  16  and needle  22  move past the end  34  of cannula  14 . The distance that the inner cannula  16  and needle move past the end  34  of cannula  14  has been previously determined by radiography. The end  44  ( FIG. 2 ) of cannula  16  can be similar in construction to end  34  of cannula  14 . While the end  44  is normally a hollow tube with an end that tapers to a sharp edge, other edges can also be employed. For example, the edge can be serrated, saw toothed or sinusoidal. The smooth edge is preferably utilized when the needle assembly is driven straight into or through a bone. The serrations or waves are employed when additional effort is required to penetrate a bone. 
       FIG. 6  illustrates the hollow cannula  16  into which the needle  22  is slidably located. Also visible in  FIG. 6  is funnel  17  which extends from the upper portion  15  of handle  18  to the first end  13  of the inner cannula  16 . The funnel  17  includes an open mouth  19  which tapers substantially to the diameter of the inner bore of the inner cannula. The funnel provides the user with an easily targeted aperture for insertion of the needle  22  or a guidewire also known as a Kirshner wire (not shown) often used in spinal as well as other types of surgeries. 
       FIGS. 2 and 11  illustrates an optional collar or spacer  150  that can be placed on the sleeve  32 . This spacer or collar  150  enables the surgeon or medical technician to precisely place the cannula  16  and needle  22  within a bone or other portion of a patient. The precise desired location of the cannula  16  and needle  22  is first determined by radiography. A measurement of this location is taken, and then a spacer or collar  150  is selected; the length of the spacer corresponding to this measurement. The spacer or collar is then placed over the sleeve  32  and the procedure is performed. In at least one embodiment, the spacer member  150  is U-shaped, an inner portion of the U-shape  151  sized to fit around the threaded member. Therefore, the end of the needle is positioned exactly where the surgeon or medical technician has determined it should be. This optional spacer prevents any over-insertion of the cannula  16  and needle  22 . 
       FIGS. 8 and 9  illustrate an alternate embodiment of the present invention. In these figures a Jamshidi-type assembly  112  is slidably disposed within an outer cannula assembly  114 . The Jamshidi-type needle  112  includes a cannula  116  which is secured to a handle  118 . The handle  118  includes a threaded collar portion  120 . This threaded collar portion  120  is fixedly secured or molded to the handle  118 . The handle  118  preferably has an ergonomic shape that can comfortably fit into a surgeon&#39;s or medical technician&#39;s hand. The handle includes an upper curved portion which is shaped to conform to an individual&#39;s palm. The lower portion of the handle  118  is also curved. The curve of the lower portion of the handle is designed to be grasped by the fingers of an individual to assist in the control of the Jamshidi-type assembly  112 . The handle  118  is used to drive the cannula into, and sometimes through bones of a vertebra. Sometimes the Jamshidi-type assembly  112  can be driven through the bone only by using pressure exerted by an individual&#39;s hand. Other times a hammer or other instrument must be employed to drive the Jamshidi-type assembly  112  through a bone. There is a risk, that when a hammer or similar instrument is utilized, the Jamshidi-type assembly  112  will pass too far into a vertebra. This can cause damage to nerves located nearby. Sometimes the needle passes completely through the vertebra and injures an adjacent blood vessel or internal organ. To prevent this, the present invention utilizes a second cannula  114  which is adjustably secured to the Jamshidi-type assembly  112 . 
     A needle, not shown, is slidably positioned within the cannula  116 . This embodiment of the present invention illustrates the needle as having a conical tip  124 , however, other tips and needles can also be employed. For example, a trocar needle can be utilized. The tip  124  can be tapered, hollow, etc. The tip can be utilized to extract a tissue sample. It can also be utilized to anchor the needle to a bone. An orthopedic bone screw or other device can then be passed down the needle and secured to the correct location on a bone. While the preferred embodiment of the present invention discloses a relatively rigid needle, other needles which are flexible can also be employed. 
     The outer cannula  114  comprises an upper portion  126  secured to a cannula  128  ( FIG. 8 ). The upper portion  126  comprises a handle or grip  130 . In this embodiment, the outer or second cannula  114  and the handle  130  are fixedly secured to each other. In other embodiments, these elements can be pivotably secured to each other. The lower end  134  of the outer cannula  114  is constructed and arranged to penetrate and pass through bone. While the end  134  is normally a hollow tube with an end that tapers to a sharp edge, other edges can also be employed. For example, the edge can be serrated, saw toothed or sinusoidal. The smooth edge is preferably utilized when the needle assembly is driven straight into or through a bone. The serrations or waves are employed when additional effort is required to penetrate a bone. The handle or grip  130  can be provided with apertures  131  into which a surgeon&#39;s fingers can be inserted to control the device. 
     The Jamshidi-type assembly  112  of this embodiment includes a threaded collar portion  120 . The second cannula  114  includes a housing  132  at a top end thereof. The housing is relatively hollow and includes threads which match the threads on sleeve portion  120 . After the surgeon inserts the needle into a patient and through the cortical bone  36  of a vertebra, the cannula  116  is inserted further into the vertebra by rotating the handle  118  and sleeve portion  120 . Rotation of sleeve  120  moves the cannula  116  and needle further into the vertebra. The distance that these elements are moved can be measured along the sleeve portion. The distance the needle needs to travel into the vertebra, which has been determined by radiography, will be measured along sleeve portion  120 . Preferably a mark or indicia is then placed on sleeve portion  120 . 
     The surgeon or medical technician can now rotate handle  118  and sleeve  120  until it reaches the desired mark of indicia on sleeve  120 . At this point, the cannula  116  and Jamshidi-type assembly  112  are now exactly where they need to be positioned. 
       FIG. 10  illustrates an optional collar or spacer  160  that can be placed on the sleeve  120 . This spacer or collar  160  enables the surgeon or medical technician to precisely place the cannula  116  and Jamshidi-type assembly  112  within a bone or other portion of a patient. The precise desired location of the cannula  116  and Jamshidi-type assembly  112  is first determined by radiography. A measurement is taken and then a spacer or collar  160  is selected which corresponds to this measurement. The spacer or collar is then placed over the sleeve  120  and the procedure is performed. This optional spacer prevents any over-insertion of the cannula  116  and Jamshidi-type assembly  112 . 
     All patents and publications mentioned in this specification are indicative of the levels of those skilled in the art to which the invention pertains. All patents and publications are herein incorporated by reference to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference. 
     It is to be understood that while a certain form of the invention is illustrated, it is not to be limited to the specific form or arrangement herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown and described in the specification and any drawings/figures included herein. 
     One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiments, methods, procedures and techniques described herein are presently representative of the preferred embodiments, are intended to be exemplary and are not intended as limitations on the scope. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims.