SURGICAL INSTRUMENT

Abstract: A surgical instrument, in particular for percutaneous disectomy, includes a hollow elongate blunt needle (16) having a port (48) in its wall adjacent its tip (46). A hollow tubular cutting member (42) is situated within the needle and has an outwardly flared cutting edge (44). The interior of the cutting member (42) is connected, in use, to a source of suction and it is positioned within the needle such that the cutting edge contacts the internal surface of the needle. The interior of the needle communicates with the interior of the cutting member adjacent the port (48). The wall of the cutting member (42) is spaced from the wall of the needle (16). In use, the annular space defined between the needle (16) and the cutting member is slid longitudinally to sever tissue which is sucked in through the port (48), which tissue is then removed through the interior of the cutting member by suction and/or irrigating fluid.

Description: The present invention relates to a surgical instrument and, in particular, to a percutaneous discectomy device for removing nucleus pulposus from a herniated spinal disc. An estimated eight million Americans suffer chronic low back pain due to disc problems requiring a total disability health care expenditure of over twenty billion dollars. The intervertebrate disc can be looked upon as an osmotic system. Because of a breakdown of macromolecules as a person ages, the number of particles in the internal softer tissue of the disc, known as nucleus pulposus, increases and causes a rise in osmotic pressure, which in turn causes a fluid influx into the disc and raises the intradisc pressure. Concomitantly, fissures begin to form in the fibrous annulus, which defines the outer periphery of the disc, because of the biomechanical forces placed upon it. Accordingly, the intervertebral disc may extend through the annulus thereof and compress nerve roots, causing great pain. The remedy has been in the past to reduce the mechanical forces that were causing the increase in disc pressure by placing the patient in bed. When such conservative therapy failed, the surgical approach was followed. A current surgical approach aims at a total disc removal through a partial hemilaminectomy and thus entails the risks that are associated with major surgery and general anaesthesia. In addition, costs of this surgery and the in-hospital convalescence required are large. Chemonucleolysis has been tried to avoid these problems. The intradiscal pressure is decreased by the percutaneous introduction of chymopapain into the intervertebral disc to dissolve it. Such an approach is effective in the majority of patients but does have some side effects, as some patients are hypersensitive to the drug. GB-A-2018601, on which the precharacterising portion of claim 1 is based, discloses a microsurgical instrument comprising an outer tube which is closed at its front end and has an aperture in its side wall, the edge of which constitutes a first cutting edge. Within the outer tube is an axially movable inner tube which carries a second cutting edge at its front end. The interior of the inner tube communicates with a vacuum conduit controlled by a valve. In use, tissue is aspirated into the aperture by the application of vacuum, cut off by advancing the inner tube and then removed by saline introduced into space between the vacuum conduit and the inner tube. WO-A 81/01363 discloses a surgical instrument comprising an outer tube which is closed by an end wall defining an aperture and within which is an inner tube closed by an end wall defining a further aperture. In use, tissue is aspirated through the two apertures by the application of vaccum and then cut of by relative rotation of the two tubes. The tissue is then removed by the vacuum through the inner tube with the aid of an irrigating fluid which is introduced into the space between the two tubes. The present invention is directed to overcoming all of the problems associated with prior surgical and drug treatments by providing a percutaneous discectomy system which can selectively remove herniated disc tissue in a surgical procedure which does not have the traumatic effect on the patient associated with prior surgical procedures. According to the present invention a surgical instrument of the type comprising a housing, a needle supported by the housing and having a forward portion projecting from the housing, the needle including a first elongate tubular wall member which defines a first central bore and has a port formed in a forward portion of its wall, said port being located adjacent the forward end of said first tubular wall member and a second elongate tubular wall member which defines a second central bore which is unobstructed and sized to permit the passage of tissue therethrough and whose forward end terminates in a cutting edge positioned radially outwardly therefrom, the second tubular wall member being slidably disposed within the first tubular wall member and spaced therefrom to define an annular space between the walls of the two wall members with the cutting edge in sliding contact with the interior surface of the first tubular wall member, the forward portion of the first bore in communication with the port constituting a tissue receiving portion communicating with the second bore, and an irrigating fluid passage adapted to be connected to a source of irrigating fluid and to supply irrigating fluid to the tissue receiving portion, the second elongate tubular wall member being adapted to be connected to a source of suction, the cutting edge being movable from a first position, in which tissue may be drawn through the port into the tissue receiving portion under the influence of the suction, into a second position in which it has traversed the port and severed the tissue which is then evacuated through the second bore with the aid of the irrigating fluid, the forward portion of the first tubular wall member having no opening rearward of the cutting edge when the cutting edge is in the first position, is characterised in that the second tubular wall member is the only tubular wall member within the first tubular wall member, and thus the annular space between the first and second tubular wall members constitutes the irrigating fluid passageway and is the only annular space in the the needle, and in that the second tubular wall member has an opening formed in it extending through the cutting edge to provide internal communication between the annular space and the tissue receiving portion and the second bore to permit the direct passage within the needle of irrigating fluid between the annular space and the second bore. The instrument preferably includes means for moving the cutting edge of the second tubular wall member between its first and second positions, which means preferably includes a diaphragm associated with the second tubular wall member and means for exposing the diaphragm to a source of pulsating pressure. The instrument preferably includes means for providing the irrigating fluid to the annular space and means for providing the source of suction to the second tubular wall member. Accordingly, the present invention provides a surgical instrument, e.g. a percutaneous discectomy device, which allows the selected removal of herniated disc tissue without the major surgical implications of standard back surgery and without the side effects of chemical surgery. This system allows the surgery to occur rapidly without the trauma to the patient which is characteristic of other surgical techniques. The invention provides a guillotine cutting arrangement, irrigation system and vacuum or aspiration system which addresses the problem of cutting and removing disc tissue, which is often dry and tough. The instrument may include a cannula adapted to receive the first tubular wall member. The cannula may be curved and in this event the first and second tubular wall members are sufficiently flexible to fit within it. This embodiment is advantageous if the disc tissue is difficult to reach since the instrument can be bent to curve around bone and tissue structures and address the proper disc without the requirement to drill through, for example, the pelvic bone. This is particularly important for the disc located between the fifth lumbar vertebra and the first sacroiliac vertebra. Further features and details of the present invention will be apparent from the following description of two specific embodiments which is given by way of example with reference to the accompanying drawings, in which: Fig. 1 is a partial schematic, partial section view of an embodiment of the invention, Fig. 2 depicts a cross-sectional view of the tip of the needle of the embodiment of the invention of Fig. 1, Fig. 3 depicts a cross-sectional view similar to Fig. 2 with the cutting edge of the embodiment positioned midway through a cut, Fig. 4 is a figure similar to Fig. 2 with the cutting edge all of the way through a cut, Fig. 5 is a cross-sectional view taken through line 5-5 in Fig. 2, Fig. 6 is yet another alternative embodiment of a surgical instrument. Referring first to Figure 1, a discectomy device is illustrated which includes a handheld percutaneous discectomy probe 12 which has a probe body 14 and a probe needle 16. The system further includes in a preferred embodiment a device 18 for providing and controlling internal irrigation fluid under pressure, a device 20 for providing a pulsed source of positive pressure to drive the system and a device 22 for providing a source of vacuum and collection means for aspirating cut disc tissue. Devices 18,20,22 can be included in a single control device console if desired. The body 14 is comprised of a cylindrical housing 24 which has a central bore 26 and a back pressure relief vent 27. Disposed at one end of the central bore 26 is a plug 28 which has a bore 30 provided therethrough. At the front end of the body 14 is a cap 32 which is secured to the body 14 with glue or other appropriate means. The cap 32 includes a bore 34. Needle 16 is partially inserted into bore 34 and, in a preferred embodiment, glued in place. An irrigation passage 36 communicates with bore 34 at a point adjacent the end of needle 16. This irrigation passage 36 also communicates with the irrigation fluid device 18. The needle 16 defines a central bore 40. Located inside of the central bore 40 of needle 16 and the bore 30 of plug 28 and also the central bore 26 of cylindrical housing 24 is an elongate tubular cutting member 42 which has a flared cutting edge 44 located adjacent the blunt end 46 of the needle 16. An O-ring 38, located in a groove defined by cap 32 and located adjacent the plug 28, provides a seal about tubular member 42. As will be described more fully hereinbelow, the flared cutting edge 44 is positioned to pass across port 48 located adjacent blunt end 46 and provided through the needle 16. The flared cutting edge 44 has a slot 50 therethrough which provides communication between a central bore 52 of the elongate tubular cutting member 42 and the space located between the central bore 26 of the needle 16 and the elongate tubular cutting member 42. The flared cutting edge 44 is compressed when it is inserted in the central bore 40 of needle 16 in order to increase the effectiveness of the guillotine cutting action of device 12. The fact that the rest of the tubular cutting member 42 is spaced from the central bore 40 of needle 16 not only allows the flow of irrigating fluid, as described below, but also reduces friction between the needle 16 and member 42. Provided in the central bore 26 and located about the cutting member 42 is a spring 54. Secured to elongate tubular cutting member 42, at the opposite end from cap 32, is a piston 56. Secured to piston 56 is a flexible diaphragm 58. Diaphragm 58 includes a peripheral lip 60 which is seated in annular groove 62 defined by cylindrical housing 24. A ring member 64 is disposed against the peripheral lip 60 and held in place by a threaded ring 66. This allows the threaded ring 66 to be tightened against the ring 64 which holds the peripheral lip 60 of the diaphragm 58 in place without causing the diaphragm to be pinched or twisted from its position. It is to be understood that upon assembly, the diaphragm is positioned so that the slot 50 in the flared cutting edge 44 is located opposite the port 48 at the blunt end 46 of the needle 16. Another cap 68 is provided adjacent the piston 56 and includes a threaded portion which can be threaded to the body 14 adjacent the threaded ring 66. A chamber is defined between the cap 68 and the diaphragm 58. The cap 68 includes a central bore 70 which guides a portion of the piston 56 and cutting member 42 and which provides a position to seat an O-ring 72, which provides a seal between the elongate tubular cutting member 42 and the another cap 68. The spring 54 biases the piston 56 and the cutting member 42 against the cap 68 so as to keep the flared cutting edge 44 in a first position located adjacent the port 48 as shown in Fig. 2. The vacuum source device 22 is provided in communication with the central bore 52 of the elongate tubular cutting member 42 by aspiration line 55, and the pulsed pressure device 20 is provided in communication with the chamber 74 through a passage 76 provided in the another cap 68. The various positions which the cutting edge 44 can occupy relative to the port 48 are shown in Figs. 2, 3, 4. In Fig. 2, a first position is shown with the port 48 fully open. In Fig. 3, the cutting edge 44 is urged toward the blunt end 46 by pulsed pressure provided to the chamber 74 from the pressure device 20 to capture and sever a piece of disc tissue 78. In Fig. 4, the cutting edge 44 has passed completely by the port 48 and has severed the tissue 78 whereby, with the aid of the irrigating fluid shown by the arrows and the vacuum provided by device 22, the severed tissue is aspirated into a collection bottle and the device 22. A cross-sectional view of the needle including the slot of the cutting edge 44 is depicted in Fig. 5. In a preferred embodiment, the housing 14 can be comprised of plastic or other suitable materials, and the needle 16 and the tubular cutting member 44 can be comprised of flexible stainless steel tubing with the elongate tubular cutting member 42 chrome-plated to prevent galling. The needle and cutting member 42 can be permanently bent to a fixed orientation if desired or can be temporarily bent if it is provided through a bent sleeve as will be described hereinbelow. In a preferred embodiment, the diameter of the needle 16 is 0.084 inches, or approximately 2 millimeters, while the internal diameter of the central passage 52 of the needle 16 is approximately 0.073 inches (1.85mm) with the outer diameter of the tubular cutting member 44 being approximately 0.059 inches (1.5mm). This spacing provides for sufficient irrigating fluid to be provided to slot 50 in order to provide irrigation adjacent the port 48. An alternative embodiment is depicted in Fig. 6, in which apertures 86 are provided through the flared portion of member 42 adjacent cutting edge 44. Apertures 86 provide internal irrigation fluid communication and allow for a strong cutting edge 44. It is to be understood that with internal irrigation as provided by the present invention, irrigation fluid tends not to pass through port 48 and thus does not interfere with the sucking of tissue into port 48. It is also to be understood that in addition to pulsing the source of positive pressure to drive diaphragm 58 and thus to drive the cutting edge 44, the irrigation fluid from device 18 as well as the vacuum from device 22 is also pulsed as follows. The irrigation fluid is periodically pulsed off or to a reduced flow with the port 48 open so as not to reduce the vacuum and the efficiency thereof in pulling tissue into the port. As cutting is completed and the cutting edge 44 closes port 48, the irrigation fluid is pulsed on to assist in removing the severed tissue through aspiration line 55. The vacuum is pulsed to prevent clogging of tissue in aspiration line 55 by providing an impulse to such tissue. It is further to be understood that device 18 can also control the irrigation fluid flow rate independently of the above periodic pulsed flow rate. This second control can be adjusted by the operator by observing the flow of irrigation fluid and tissue in the aspiration line 55 which in a preferred embodiment is substantially clear. If the operator observes a fast irrigation fluid flow with little tissue, the operator can decrease generally the flow rate independently of the first periodic pulsed flow rate so that the vacuum can be more efficient in aspirating tissue. If the operator observes a slow irrigation fluid flow rate with much tissue, the operator can generally increase the fluid flow rate as a preventative measure so that tissue clogging does not occur. The operation of the percutaneous discectomy system 10 is as follows. Using CT scan techniques and the like, the needle 16 can be inserted straight-in between the appropriate vertebrae and into the herniated disc. Prior to the insertion of the needle 16, a small hole can be prepared through the fibrous annular ring which defines the outer periphery of the disc. The needle is then inserted through this opening. As the needle 16 is inserted through the hole drilled in the periphery of the disc, the irrigation device, the suction device, and positive pressure device are turned on to operate the guillotine cutting action of the flared cutting edge 44 relative to the port 48 and to aspirate tissue. As the needle is inserted further into and through the disc, additional tissue is severed and aspirated. Also as the needle is rotated in place, the port 48 is exposed to different portions of the disc and additional tissue is severed and aspirated. Once the required amount of tissue is removed, the needle can be moved from the disc. It is to be understood that if the disc is located in a hard-to-reach area such as between the fifth lumbar and the first sacroiliac vertebrae, then instead of cutting through part of the pelvis or other tissues or bone structures, an introduction and delivery system which includes a curved sleeve or cannula can be inserted using known techniques, such as with the aid of the CT scan so as to avoid the bone obstacles. Such an introduction and delivery system using such a sleeve can also be used, if desired, in the above described straight-in procedure. Once the cannula is positioned, the flexible needle can be inserted through the cannula into the disc so as to remove disc tissue along a linear path. It is to be understood that the port 48 can also be rotated throughout 360° in order to extract additional tissue. Further it is to be understood that if desired, the needle 16 can be permanently bent, and without the use of a sleeve or cannula can be inserted into this position. However, there is then no opportunity to rotate the port 48 located in the needle 16 in order to sever and aspirate tissue on a 360° basis. It is also to be understood that such an introduction and delivery system can be used generally with this invention and can also include devices for precisely maintaining the position of the probe relative to the body. From the above it can be seen that the present invention provides for an instrument for removing tissue from a herniated disc without causing undue trauma to the patient. Additionally the instrument may be flexible so that it can be positioned in otherwise surgically hard to reach areas, plus it provides for irrigation of the severed material to facilitate the aspiration thereof to the collection vessel. The pulsed vacuum creates impulses in the line which act as shock waves to further facilitate the aspiration of the tissue and prevent it from clogging in the needle 16. It is to be understood that although the present invention was described relative to a percutaneous discectomy procedure, a similar instrument can be used to remove tissue from other portions of the body or for other unrelated purposes.

Claims: A surgical instrument comprising a housing (24), a needle (16) supported by the housing and having a forward portion projecting from the housing, the needle (16) including a first elongate tubular wall member which defines a first central bore (40) and has a port (48) formed in a forward portion of its wall, said port (48) being located adjacent the forward end of said first tubular wall member and a second elongate tubular wall member (42) which defines a second central bore (52), which is unobstructed and sized to permit the passage of tissue therethrough and whose forward end terminates in a cutting edge (44) positioned radially outwardly therefrom, the second tubular wall member (42) being slidably disposed within the first tubular wall member and spaced therefrom to define an annular space between the walls of the two wall members with the cutting edge (44) in sliding contact with the interior surface of the first tubular wall member (16), the forward portion of the first bore (40) in communication with the port (48) constituting a tissue receiving portion communicating with the second bore (52), and an irrigating fluid passage adapted to be connected to a source of irrigating fluid (18) and to supply irrigating fluid to the tissue receiving portion, the second elongate tubular wall member (42) being adapted to be connected to a source of suction (22), the cutting edge (44) being movable from a first position, in which tissue (78) may be drawn through the port (48) into the tissue receiving portion under the influence of the suction, into a second position in which it has traversed the port (48) and severed the tissue which is then evacuated through the second bore (52) with the aid of the irrigating fluid, the forward portion of the first tubular wall member having no opening rearward of the cutting edge (44) when the cutting edge is in the first position, characterised in that the second tubular wall member (42) is the only tubular wall member within the first tubular wall member, and thus the annular space between the first and second tubular wall members (16,42) constitutes the irrigating fluid passageway and is the only annular space in the needle (16), and in that the second tubular wall member (42) has an opening (50) formed in it extending through the cutting edge (44) to provide internal communication between the annular space and the tissue receiving portion and the second bore (52) to permit the direct passage within the needle (16) of irrigating fluid between the annular space and the second bore (52). An instrument as claimed in claim 1 characterised in that the first tubular wall member (16) has a cylindrical side surface and a blunt end wall (46). An instrument as claimed in claim 1 or claim 2 characterised by means (20,54,56) for moving the cutting edge (44) of the second tubular wall member (42) between its first and second positions. An instrument as claimed in claim 3 characterised in that the means (20,54,56) for moving the cutting edge (44) includes a diaphragm (58) associated with the second tubular wall member (42) and means (76) for exposing the diaphragm (58) to a source of pulsating pressure (20). An instrument as claimed in any one of the preceding claims characterised by means (36,18) for providing the irrigating fluid to the annular space. An instrument as claimed in claim 5 characterised by means (18) for regulating the flow of the irrigating fluid. An instrument as claimed in any one of the preceding claims characterised by means (55) for providing the source of suction (22) to the second tubular wall member (42). An instrument as claimed in any one of the preceding claims characterised in that the flow of irrigating fluid is "off" when the cutting edge (44) is in its first position and "on" when the cutting edge (44) is in its second position. An instrument as claimed in any one of the preceding claims characterised by a cannula adapted to receive the first tubular wall member (16). An instrument as claimed in claim 9 characterised in that the cannula is curved and that the first and second tubular wall members (16,42) are sufficiently flexible to fit within the curved cannula. An instrument as claimed in any one of the preceding claims characterised in that it is a percutaneous discectomy device.

Inventors: GINSBURG, LEONARD, ONIK, GARY
Applicants: SURGICAL DYNAMICS INC.
Application year: 1985
Main classification: A61B17
IPC codes: A61B17