WO2008035849A1

WO2008035849A1 - Expandable jacking curette for bone fusion surgery

Info

Publication number: WO2008035849A1
Application number: PCT/KR2007/003241
Authority: WO
Inventors: Nam Soo Song
Original assignee: Nam Soo Song
Priority date: 2006-09-23
Filing date: 2007-07-04
Publication date: 2008-03-27

Abstract

Disclosed is an expandable jacking curette for a bone fusion surgery. A cutter is inserted into the surgical region through an elongated guide tube, so that the damage of the tissue is minimized, enabling the percutaneous spinal surgery and the endoscope guide spinal surgery. The cutter has a structure matching with the bone structure or intervertebral structure, so that the cutter curettes the distal ends of the vertebral disc and the bone. The narrow intervertebral space or the bone structure is stably expanded, thereby allowing bone implantation materials, rein¬ forcement agents and fusion cage to be safely complemented. The expandable jacking curette has a lower structure including a crank shaft, at least one first crank arm connected to a crank shaft head by means of a hinge, a cutter connected to the first crank arm by means of a hinge, a support tube allowing the crank shaft to pass therethrough, and at least one second crank arm connected to the cutter by means of a hinge, wherein the second crank arm is connected to a sleeve of the support tube by means of a hinge, thereby forming at least one set of four- fold type crank; and an upper structure including an indicator having an indicator shaft coupled with the crank shaft through a bolt-nut mechanism, and a housing connected to a bracket that supports the indicator and fixes the support tube. The crank shaft moves up and down by rotating the indicator, thereby adjusting the height of the cutter.

Description

EXPANDABLE JACKING CURETTE FOR BONE FUSION

SURGERY

Technical Field

[1] The present invention relates to an intervertebral reamer or an expandable orthopedic drill, which is used to form a bone bed (basin) between vertebral bodies by scraping a spinal disc endplate or a vertebral body endplate until bone bleeding is incurred when performing various spinal interbody fusion surgeries, such as the per- curaneous spinal surgery, minimal invasive spinal surgery, endoscope guide spinal surgery, open spinal surgery, extra foranimal fusion, and anterior spinal surgery.

[2]

Background Art

[3] Conventionally, when performing the intervertebral surgery, a reamer or a drill is inserted between vertebral bodies to expand a space between vertebral discs or vertebral bones. That is, the reamer or the drill is a surgical tool used to perforate a vertebral body or to cut the vertebral body subject to the surgery.

[4] Recently, in order to perform the intervertebral surgery while minimizing damage to the bone, that is, in order to operate the intervertebral surgery without perforating the vertebral body or cutting the vertebral body subject to the surgery, there have been suggested new drills or reamers, in which the height of a cutter installed in a cutter unit of the drill or the reamer is expandable to ensure the sufficient surgical space by enlarging the space between vertebral discs or vertebral bones (see, U.S. Patent Nos. 5,445,639 and 6,224,604).

[5]

Disclosure of Invention Technical Problem

[6] However, the expandable intervertebral or orthopedic drill or reamer includes a pair of three-fold type pivot cranks to support one cutter, so four arms are required for one cutter. Accordingly, sixteen arms are required for four cutters, so that a volume of a cutting unit including a crank shaft and a cutter becomes enlarged. Therefore, it is difficult to insert the cutter unit into the intervertebral space. In addition, due to the cutter unit having an excessive volume, internal tissues are unnecessarily damaged during the surgery. For this reason, the above drill or reamer is locally used for the invasive spinal surgery. If the number of the support arms or the strength of the support arms is reduced to reduce the volume of the cutter unit, it is limited to enlarge the space between the bones or the vertebral bodies, so the drill or reamer does not achieve its original function. In addition, the cutter or the support arm may be broken, causing the medical accident.

[7] According to the conventional expandable reamer used for the spinal surgery or the bone surgery, two three-fold type pivot cranks are provided to support one cutter. Thus, when the cutter is folded on the crank shaft, four crank arms must be folded on one side of the crank shaft, so the distal end of the crank shaft and the length of the cutter may be increased, so that the surgery part is unnecessarily deepened. If the length of the cutter is shortened, the length of the crank arm is also shortened, so that it is limited to enlarge the intervertebral space.

[8] In addition, according to the conventional drill or reamer used for the vertebral surgery or the orthopedic surgery, a reinforcement agent must be injected into the intervertebral space, or the cutter must be expanded to ensure the space, into which materials are injected during the kyphoplasty (osteoplasty) surgery. However, there is no mechanism for draining cancellous bones or bone tissues after cutting.

[9]

Technical Solution

[10] When performing the bone surgery requiring the bone implantation and vertebral body fixation, such as the percutaneous surgery, minimal surgery, endoscope guide surgery, open surgery, and anterior spinal surgery, a tube having a small diameter is introduced into an implantation part to ensure a space and a cutter is expanded to enlarge the space.

[11] In addition, in order to ensure the space in the vertebral body to inject the reinforcement agent into the vertebral body, or to inject materials into the space during the kyphoplasty (osteoplasty) surgery, an apparatus, which cuts the cancellous bone in the vertebral body while adjusting the height of the cutter, is necessary.

[12] The expandable jacking curette for the bone fusion surgery according to the present invention is provided to solve the problem occurring in the conventional reamer used for the vertebral surgery or the bone surgery. According to the expandable jacking curette of the present invention, a cutter is inserted into the vertebral body by means of an elongated guide tube, which is obtained by improving the structure of wings including an expandable cutter, so that damage of the tissue is minimized, and the percutaneous surgery and the endoscope guide spinal fusion surgery are enabled. In addition, the cutter has the four- fold type crank structure, so that the load applied to the cutter from the bone tissue according to the bone structure or the intervertebral structure can be effectively supported or distributed when the wing including the cutter is expanded. Thus, the cutter can easily curette the endplate of the vertebral disc and the bone and can drain or remove the bone tissues, so that the narrow intervertebral space or the bone structure can be stably expanded or supported, thereby allowing bone implantation materials, reinforcement agents and fusion cage to be safely complemented.

[13] In this regard, the present invention provides an expandable jacking curette for the bone fusion surgery, which is different from the conventional expandable reamer or drill used for the vertebral surgery or the bone surgery in that the expandable jacking curette can curette the endplate of the bone, can stably expand or support the space in the bone and can exhaust and remove the bone tissue.

[14]

Advantageous Effects

[15] The present invention provides a four- fold type crank structure, in which two crank arms support a cutter, so that the length of the cutter can be reduced by a half as compared with that of the three-fold type crank structure, in which four crank arms support the cutter, without reducing the size of the space between bones. The four-fold type crank structure of the present invention can minimize the length and volume of a head section including the cutter, while ensuring the space required for the surgery.

[16] Therefore, the expandable jacking curette according to the present invention can be used to inject the bone implantation materials, reinforcement agent or fusion case into the intervertebral space in various spinal interbody fusion surgeries. In addition, when the implantation materials are injected into the intervertebral space during the kyphoplasty (osteoplasty) surgery or the orthopedic bone implantation surgery, the expandable wing curette is inserted into the intervertebral space through a guide tube having a small diameter to ensure the space between vertebral bodies or bones and to remove the cancellous bone while adjusting the height of the cutter.

[17] Due to the four-fold type crank mechanism, the curette can precisely adhere to the vertebral body, the bone and the intervertebral space, which are different depending on patients. Thus, the bone curetting and expansion of the intervertebral space can be obtained by using the same jacking curette. Further, the bone tissue can be easily removed and the bone implantation materials can be easily injected by using the same jacking curette. Brief Description of the Drawings

[18] FIG. 1 is an assembled sectional view of the present invention;

[19] FIG. 2 is an exploded perspective view of the present invention;

[20] FIG. 3 is a perspective view showing two sets of four- fold type cranks according to the present invention;

[21] FIG. 4 is a longitudinal sectional view showing two sets of four- fold type cranks shown in FIG. 3; [22] FIG. 5 is a partially detailed view of a click shown in FIG. 2; and

[23] FIGS. 6 to 8 are views showing the operational state of two sets of four-fold type cranks according to the present invention.

[24] <Description of reference numerals shown in the drawings>

[25] 10: crank shaft, 11; crank shaft head, 12; first crank arm, 13; hinge, 14; cutter, 15; spring, 16; spring groove, 17; spring hole, 18; limiter protrusion, 19; crank shaft connection nut, 20; support tube, 21; support tube sleeve, 22; second crank arm, 23; support tube bracket, 24; drain hole, 25; bracket fastening nut, 28; nozzle, 29; O-ring, 29-1; O-ring slot, 30; indicator, 31; indicator shaft, 40; housing, 41; limiter hole, 42; housing handle, 43; T-handle, 50; guide tube, 60; stopper, 70; click, 71; spring housing groove, 72; spring, 73; metal ball, 74; indicator-side metal ball groove

[26]

Best Mode for Carrying Out the Invention

[27] An expandable jacking curette for the bone fusion surgery according to the present invention comprises: a lower structure including a crank shaft, at least one first crank arm connected to a crank shaft head by means of a hinge, a cutter connected to the first crank arm by means of a hinge, a support tube allowing the crank shaft to pass therethrough, and at least one second crank arm connected to the cutter by means of a hinge, wherein the second crank arm is connected to a sleeve of the support tube by means of a hinge, thereby forming at least one set of four- fold type crank; and an upper structure including an indicator having an indicator shaft coupled with the crank shaft through a bolt-nut mechanism, and a housing connected to a bracket that supports the indicator and fixes the support tube.

[28] FIG. 1 is an assembled sectional view showing the lower structure including at least one four- fold type crank set and the support tube 20 installed at a distal end of the crank shaft 10, and the upper structure including the indicator 30 and the housing 40.

[29] Hereinafter, the structure of the present invention will be described in detail with reference to accompanying drawings.

[30] According to the lower structure of the expandable jacking curette for the bone fusion surgery of the present invention, a cutter is inserted into the vertebral body through an elongated guide tube, so that the damage of the tissue is minimized. In addition, the lower structure of the expandable jacking curette includes a four-fold type crank structure. Thus, when a wing including the cutter is expanded, the cutter precisely matches with the bone structure or the intervertebral structure, so that the load applied to the cutter from the bone tissue can be effectively supported or distributed. Accordingly, the cutter can easily curette the endplate of the vertebral disc and the bone. The lower structure of the expandable jacking curette includes the crank shaft 10, at least one first crank arm 12 connected to the crank shaft head 11 by means of a hinge 13, a cutter 14 connected to the first crank arm by means of a hinge, a support tube 20 allowing the crank shaft 10 to pass therethrough, and at least one second crank arm 22 connected to the cutter 14 by means of a hinge, wherein the second crank arm is connected to the sleeve 21 of the support tube 20 by means of a hinge, thereby forming at least one four-fold type crank set.

[31] According to the upper structure of the expandable jacking curette for the bone fusion surgery of the present invention, the crank shaft moves upward and downward to adjust the height of the wing, so that the space between bones can be stably expanded. Thus, the bone implantation materials, reinforcement agents and fusion cage can be safely complemented. The crank shaft 10 is connected to the indicator shaft 31 of the indicator 30 through a bolt-nut mechanism, and the upper structure includes the housing 40 connected to the bracket 24 that supports the indicator and fixes the support tube 20. The crank shaft moves up and down (forward and backward) as the indicator shaft 31 and the indicator 30 are rotated, thereby adjusting the height of the cutter.

[32] FIG. 2 is an exploded perspective view of the present invention.

[33] The expandable jacking curette according to the present invention comprises: the crank shaft 10, at least one first crank arm 12 connected to the crank shaft head by means of a hinge, the cutter 13 connected to the first crank arm by means of a hinge, the support tube 20 allowing the crank shaft 10 to pass therethrough, the second crank arm 22 connected to the cutter 13 by means of a hinge, in which the second crank arm 22 is connected to the sleeve of the support tube by means of a hinge thereby forming least one four- fold type crank set, the indicator 30 having the indicator shaft 31 coupled with the crank shaft 10 through the bolt- nut mechanism, and the housing 40 that supports the indicator and fixes a handle 43.

[34] Hereinafter, the structure of the present invention will be described in detail with reference to accompanying drawings.

[35] The crank shaft 10 includes a distal end portion having a rectangular column shape, to which the wing including the cutter is attached, and a proximal end portion having a cylindrical shape and being accommodated in the support tube 20. A gap is formed between the crank shaft 10 and the support tube 20 such that the crank shaft 10 can easily move up and down within the support tube 20.

[36] The distal end portion of the crank shaft 10 protrudes out of the sleeve 21 of the support tube 20 and includes an arc-shape head 11 having a diameter identical to that of the sleeve 21 of the support tube to support first crank arms 12 coupled thereto. Slots are formed at outer circumferential portions of the head 11 to receive the crank arms 12 therein. That is, first end portions of the first crank arms 12 are inserted into the slots of the head 11 and second end portions of the first crank arms 12 are coupled to the cutter 14 by means of hinges 13. If one four- fold type crank set is coupled to the crank shaft head 11, one slot is formed at the outer circumferential portion of the head 11. If two sets of four- fold type cranks are provided, two slots are formed at the outer circumferential portion of the head 11. If three sets of four- fold type cranks are provided, three slots are formed in a triangular pattern. If four sets of four- fold type cranks are provided, four slots are formed in a square pattern, in such a manner that first end portions of the first crank arms can be inserted into the slots and second end portions of the first crank arms can be hinged to the cutter.

[37] FIG. 3 is a perspective view showing two sets of four-fold type cranks according to the preferred embodiment of the present invention, and FIG. 4 is a longitudinal sectional view of the four-fold type cranks shown in FIG. 3.

[38] Similar to the slot formed in the sleeve 21 of the opposite support tube, the slot of the crank shaft head 11 serves as a coupling port that receives one end portion of the first crank arm 12 such that the first crank arm 12 can be hinged to the cutter by means of the hinge 13. When the curetting is performed by rotating the housing 40 or the height of the cutter is expanded, the slot formed in the crank shaft head 11 protects the hinge 13 from the rotational force and propelling force of the cutter 14 and the first crank arm 12 while complementing the support force of the first crank arm 12.

[39] A bulge section is formed at the distal end portion of the crank shaft 10 in order to allow the first and second crank arms 12 and 22 to closely adhere to the cutter 14 without forming a gap therebetween when the wing is folded, and to prevent the curetting residue from being embedded between the crank shaft 10 and the first crank arm 12 and between the first crank arm 12 and the cutter 14. Such a bulge section formed at the distal end portion of the crank shaft 10 prevents the curetting residue from being embedded in the first and second crank arms and the arc-shaped cutter during the curetting operation. Here, the bulge section must not interfere with the fourfold type crank including the cutter when the four-fold type crank passes through the guide tube. In addition, the cutter has an arc shape, so that both ends of the cutter cannot be excessively inserted into the bone, thereby preventing the bone from being damaged.

[40] A nut section 19 is installed at the proximal end portion of the crank shaft 10 to couple the crank shaft 10 with the indicator shaft 31. A limiter protrusion 18 is provided at an outer peripheral surface of the nut section 19. The limiter protrusion 18 is inserted into a limiter hole 41 of the housing to restrict the rotation of the housing. In this state, the nut section 19 is coupled with a bolt section of the indicator shaft 31, which is rotated by the user. Thus, the crank shaft moves up and down so that the wing including the cutter supported by the four-fold type crank can be expanded.

[41] In addition, an O-ring slot 29-1 is formed at the intermediate portion of the crank shaft, which is positioned just below the nozzle 28 of the support tube when the crank shaft is maximally moved up, and an O-ring 29 is installed in the O-ring slot. As the crank shaft moves up and down, the O-ring 29 makes contact with the inner peripheral surface of the support tube 20 and moves up and down about the nozzle 28 of the support tube.

[42] The support tube 20 receives the crank shaft 10 and a gap is formed between the support tube 20 and the crank shaft 10 such that the crank shaft 10 can move up and down within the support tube 20. The nozzle 28 is coupled to an upper portion of the support tube 20 and a syringe is coupled to the nozzle 28. Since the gap is formed between the support tube and the crank shaft, the support tube can rotate the housing during the surgery for the purpose of curetting or can drain the bone tissue which is generated when expanding the height of the cutter. In addition, implantation materials can be injected into the gap from a rear surface where curette is not formed while maintaining the height of the vertebral body during the kyphoplasty (osteoplasty) surgery.

[43] As described above, since the O-ring 29 is installed in the O-ring slot 29-1 of the crank shaft 10 positioned below the nozzle 28 of the support tube, the gap between the crank shaft 10 and the inner surface of the support tube 20 can be sealed. In this case, as the crank shaft 10 moves up and down, the relative position of the O-ring 29 is changed about the nozzle 28 of the support tube, so that it is possible to selectively inject washing liquid to the housing or the wing. In other words, if the washing liquid is injected through the nozzle 28 when the wing is folded due to the upward movement of the crank shaft, since the O-ring 29 is positioned adjacent to the wing on the basis of the nozzle 28, the washing liquid is fed into the housing only. In contrast, if the washing liquid is injected through the nozzle 28 when the wing is expanded due to the downward movement of the crank shaft, since the O-ring 29 is positioned adjacent to the housing on the basis of the nozzle 28, the washing liquid is fed into the wing only. If the wing is not completely folded due to impurities penetrating into the wing structure during the surgery, the user inject the washing liquid into the wing structure after expanding the wing, thereby effectively removing impurities penetrating into the wing structure.

[44] A support tube bracket 23 surrounds the outer peripheral surface of the support tube

20 and includes a drain hole 24 communicated with the nozzle 28 of the support tube 20. The support tube bracket 23 is coupled with the housing by means of a bracket fixing nut 25.

[45] The cylindrical sleeve 21, which has a diameter identical to that of the crank shaft head 11 and a thickness greater than the support tube, is integrally formed with the distal end portion of the support tube 20 in order to support the second crank arm 22. As mentioned above, the distal end of the crank shaft 10 protrudes out of the sleeve. Slots are formed at the end portion of the sleeve 21 in opposition to the slots formed at the crank shaft head 11. One end portion of the second crank arm 22 is inserted into the slot and the other end portion of the second crank arm 22 is coupled to the cutter by means of the hinge. Similar to the slot formed in the crank shaft head 11, each slot of the sleeve 21 serves as a coupling port that receives one end of the second crank arm 22 such that the second crank arm is hinged to the cutter. When the curetting is performed by rotating the housing including the cutter or when the height of the cutter is expanded, the slot formed in the sleeve 21 protects the hinge from the rotational force and propelling force of the cutter 14 and the first crank arm 12 while complementing the support force of the second crank arm 22.

[46] If one four- fold type crank set is installed for the sleeve 21, one slot is formed at one end portion of the sleeve. If two sets of four- fold type cranks are provided, two slots are formed at both sides of the sleeve 21. If three sets of four- fold type cranks are provided, three slots are formed in a triangular pattern. If four sets of four- fold type cranks are provided, four slots are formed in a square pattern in opposition to the slots of the crank shaft head 11. First end portions of the second crank arms are inserted into the slots and second end portions of the second crank arms are hinged to the cutter. That is, the first end portions of the first and second crank arms are inserted into the slots formed in the crank shaft head 11 and the sleeve 21, which are opposite to each other, and second end portions of the first and second crank arms are hinged to a pair of cutters at two spots of the cutters, thereby forming the four- fold type crank. In maximum, four sets of the four-fold type cranks can be provided.

[47] The first crank arm 12, which is coupled with the crank shaft head 11, and the second crank arm 22, which is coupled with the sleeve 21, are hinged to the cutter at two spots of the cutter, thereby forming one four-fold type crank set.

[48] Although FIG. 3 shows the one four-fold type crank set, in which the length of the first crank arm is identical to that of the second crank arm, it is also possible to provide at least one four-fold type crank set, in which the length of the first crank arm is different from that of the second crank arm. This type of four- fold type crank set is applicable for a permanent wedge type bone structure.

[49] The first crank arm 12 is connected between the slot of the crank shaft head 11 and the slot of the cutter 14 by means of the hinge 13, and the second crank arm 22 is connected between the slot of the sleeve 21 and the slot of the cutter 14. The slots receiving the first and second crank arms 12 and 22 may protect the hinge from the rotational force and propelling force of the cutter 14 while complementing the support force of the first and second crank arms 12 and 22 when the curetting is performed by rotating the housing 40 or the height of the cutter is expanded. When the wing is folded, the first and second crank arms 12 and 22 must closely adhere to the distal end portion of the crank shaft 10 without forming a gap therebetween. Thus, the first and second crank arms have a linear shape or an arc shape corresponding to the shape of the distal end portion of the crank shaft 10. As mentioned above, the first and second crank arms preferably have an arc shape so as to prevent impurities from being embedded between the crank shaft and the crank arm and between the crank arm and the cutter.

[50] The cutter 14 has a substantially rectangular column shape. The first and second crank arms 12 and 22 are coupled to the cutter at two spots (upper and lower portions) of the cutter 14 by means of the hinge 13, thereby forming one four-fold type crank set. The cutter 14 has a linear column structure or an arc-shaped column structure corresponding to the shape of the crank arm. Preferably, the cutter has an arc-shaped column structure in order to prevent the bone tissue from being embedded in the wing structure during the curetting or the wing is expanded. In this case, both ends of the cutter cannot be excessively inserted into the bone, thereby preventing the bone from being damaged.

[51] Slots are formed in the cutter such that the first and second crank arms 12 and 22 can be accommodated in the slots of the cutter when the first and second crank arms 12 and 22 are folded in such a manner that the bone tissue embedded between the cutter and the crank arms can be easily drained. First end portions of the first and second crank arms 12 and 22 are coupled to the cutter in the slots by means of the hinge.

[52] A blade is formed at an outer edge portion of the cutter to perform the curetting.

The outer surface of the cutter can be variously formed. For instance, a plurality of sharp protrusions can be formed on the outer surface of the cutter.

[53] According to the exemplary embodiment of the present invention, the jacking curette mainly includes two sets of four-fold type cranks, which are provided in opposition to each other about the crank shaft. However, the jacking curette can include four sets of four- fold type cranks. When two or four sets of four- fold type cranks are employed, in order to set the initial configuration of the wing such that the four-fold type cranks including the first and second crank arms 12 and 22 and the cutters 14 can be symmetrically aligned, a spring 15 is preferably provided to deploy the wing in the transverse direction about the crank shaft 10. In order to allow the cutters 14 to be stably and symmetrically maintained when the wing is deployed, a spring hole 17 is formed at the center of the bulge section formed at the distal end portion of the crank shaft 10. In addition, a spring home 16 is formed at the inner portion of each cutter 14 to receive the spring 15 therein. The spring 15 used for deploying the wing extends by passing through the spring hole 17 formed in the crank shaft 10 and both end portions of the spring 15 are rested in the spring homes 16, so that the spring 15 is prevented from being separated from the four- fold type crank. When one or three sets of the four- fold type cranks are provided, the spring hole is not formed in the center of the crank shaft. In this case, the spring home is formed at the crank shaft and the cutter, respectively.

[54] As shown in FIG. 2, the crank shaft 10 is coupled with the indicator shaft 30 through the bolt-nut mechanism. The limiter protrusion 18 installed at the nut section 19 of the crank shaft is inserted into the limiter hole 19, thereby preventing the housing 40 from rotating. The nut section 19 of the crank shaft engages with the bolt section of the indicator shaft 31 so that the nut section 19 can move up and down. As mentioned above, the up-down movement of the crank shaft 10 for adjusting the height of the cutter is caused by the indicator shaft 31 and the indicator 30 which are connected to the nut section 19 through the bolt-nut mechanism.

[55] The indicator 30 is integrally formed with the indicator shaft 31 and is coupled with the housing 40 by means of a bearing. A metal ball hole 74 for a click (see, FIG. 5) is formed at a lower end portion of the indicator that matches with a gauge indicating the height of the wing. This structure prevents the wing from being folded during the curetting operation and allows the height measurement of the cutter when manipulating the indicator.

[56] The indicator 30 and the indicator shaft 31 are coupled with the nut section 19, which is formed at the proximal end portion of the crank shaft 10, through the bolt- nut mechanism in order to move the crank shaft 10 up and down. That is, the nut section 19 provided at the proximal end portion of the crank shaft 10 is coupled with the bolt section of the indicator 30 and the indicator shaft 31, which are manipulated by the user, to move the crank shaft 10 up and down. If the user rotates the indicator 30 in one direction, the crank shaft 10 moves down so that the wing is expanded and the height of the cutter is increased. In contrast, if the user rotates the indicator 30 in the other direction, the crank shaft 10 moves up so that the wing is folded and the height of the cutter is reduced. In this manner, the expandable jacking curette for a bone fusion surgery according to the present invention can expand the wing and adjust the height of the cutter by moving the crank shaft up and down (forward and backward) using the indicator.

[57] The housing 40 is a cylindrical cover that surrounds the crank shaft 10 and the support tube while preventing the crank shaft from rotating. In order to control the maximum expansion height and the minimum expansion height of the wing, the limiter hole 41 is formed in the housing 40 and the limiter protrusion 18 of the crank shaft is inserted into the limiter hole 41 so as to restrict the movement of the crank shaft. In addition, the T-shape handle 43 is installed at the housing to allow the user to easily perform the curetting by rotating the jacking curette. That is, the T-shape handle installed at the housing facilitates the curetting by allowing the user to rotate the housing with reduced force.

[58] In addition, the indicator is coupled with the upper end portion of the housing 40 through the bearing so that the indicator is idly rotated. A spring insertion hole 71 is formed in the housing the longitudinal direction. A metal ball 73 is installed on the spring 72 in the housing. In addition, the click (see, FIG. 5) is installed such that the click makes contact with the metal ball hole 74 formed at the lower end portion of the indicator 30, thereby preventing the wing from being folded during the curetting and allowing the height measurement of the cutter when the user manipulates the indicator.

[59] Further, since the crank shaft 10 finely moves when rotating the indicator 30, in order to exhibit the expansion height of the wing separately from the limiter hole 41 of the housing, the moving distance of the crank shaft 10 is mechanically indicated by using the screw pitch of the indicator 30 or is indicated by using an operator, such as a digital counter that exhibits the moving distance of the crank shaft by digitally detecting the moving distance of the crank shaft. In addition, a device having a click sound function corresponding to the operation of the indicator can be additionally employed.

[60] The guide tube 50 serves as a guide of the jacking curette. The guide tube 50 determines the location and depth required for the surgery such that the jacking curette can be precisely inserted between bones or intervertebral bodies. The diameter of the guide tube 50 is slightly larger than the diameter of the wing when the wing connected to the crank shaft head 11 and the support tube sleeve 21 is completely folded to the distal end portion of the crank shaft. Preferably, the guide tube 50 must have a small diameter to prevent the human tissue, such as a muscle, a ligament, and a bone, from being damaged. The jacking curette is inserted into the intervertebral body by passing through the guide tube.

[61] A stopper 60 is provided as an auxiliary tool of the present invention. The stopper

50 allows the support tube to pass therethrough and is screw-coupled with a bracket which is coupled with the housing through a bolt-nut mechanism. When the curette is being inserted into a surgical region, the stopper prevents the cutter from being excessively inserted into the surgical region beyond the optimum depth. The stopper can be controlled by manipulating two nuts installed on the bracket, so that the position of the cutter relative to the surgical region can be adjusted, limited or fixed.

[62] FIGS. 6 to 8 are views showing the operational state of a pair of four- fold type cranks according to the present invention. FIG. 6 shows the front-load type wing structure used for the wedge type bone structure, FIG. 7 shows the rear-load type wing structure used for the wedge type bone structure, and FIG. 8 shows the horizontal-load type wing structure. [63] Therefore, the four-fold type crank according to the present invention can selectively adopt the front-load type wing structure, the rear-load type wing structure or the horizontal-load type wing structure according to the bone structure or the bone shape of the patient.

[64] In addition, the four-fold type crank according to the present invention may realize various wing shapes using one curette according to the shape of the bone located in the surgical region and according to the direction of load applied to the cutter from the bone structure. Thus, the jacking curette according to the present invention is applicable for various bone structures.

[65]

[66]

[67]

Industrial Applicability

[68] The four-fold type crank set assembled by using hinges according to the present invention can reduce the length of the cutter by a half as compared with that of the three-fold type pivot crank assembled by using sliding collars. In addition, the volume of the wing can be reduced as compared with that of the three-fold type pivot crank when the wing is folded. Further, when the wing is expanded, the surgical region can be expanded more than two times as compared with that of the three-fold type pivot crank equipped with the wing having the size identical to that of the wing of the present invention. That is, the jacking curette of the present invention can be inserted between bones or into the intervertebral space while minimizing the volume of the wing and the cutter. When the wing is expanded, the surgical space can be expanded even through the wing has a small size.

[69] According to the conventional three-fold type pivot crank, only one type of wing can be formed by using one reamer, so that various types of reamers must be prepared to form various types of wings corresponding to the bone structures (the front wedge type, the rear wedge type and the horizontal type). However, the jacking curette according to the present invention may realize three types of wings (maximally five types of wings), so the number of curettes to be prepared by the worker can be reduced to 1/5. Thus, it is not necessary to use a plurality of three-fold type pivot crank reamers by providing the jacking curette according to the present invention.

[70]

[71]

[72]

Claims

[1] An expandable jacking curette for a bone fusion surgery, the expandable jacking curette comprising: a crank shaft; at least one first crank arm connected to a crank shaft head by means of a hinge; a cutter connected to the first crank arm by means of a hinge; a support tube allowing the crank shaft to pass therethrough; and at least one second crank arm connected to the cutter by means of a hinge, wherein the second crank arm is connected to a sleeve of the support tube by means of hinges, thereby forming at least one set of four- fold type cranks, and a height of the cutter is adjusted by moving the crank shaft up and down.

[2] The expandable jacking curette as claimed in claim 1, wherein the cutter of the four-fold type crank is supported by a spring.

[3] The expandable jacking curette as claimed in claim 1 or 2, wherein the crank shaft is coupled with an indicator shaft through a bolt-nut mechanism, a housing is connected to a bracket that supports an indicator and fixes the support tube, and the height of the cutter is adjusted by moving the crank shaft up and down by rotating the indicator and the indicator shaft.

[4] The expandable jacking curette as claimed in claim 1 or 2, wherein the crank shaft has a bulge section which is formed at a distal end portion of the crank shaft.

[5] The expandable jacking curette as claimed in claim 1 or 2, wherein the cutter has a slot formed at a fold part with the crank arm, and the cutter has an arc shape to receive the crank arm when the crank arm moves down.

[6] The expandable jacking curette as claimed in claim 1 or 2, wherein the cutter has a blade formed at both edges of the cutter to perform curetting.

[7] The expandable jacking curette as claimed in claim 1 or 2, wherein the cutter is provided at an outer surface thereof with a plurality of sharp protrusions.

[8] The expandable jacking curette as claimed in claim 3, wherein the bracket coupled to the housing through a bolt-nut mechanism has a stopper having a nut structure, and a position of the stopper is adjusted to limit or fix a position of the cutter in a surgical region.

[9] The expandable jacking curette as claimed in claim 1 or 2, wherein the support tube has a nozzle such that bone tissues are drained through a gap formed between an inner portion of the support tube and the crank shaft.

[10] The expandable jacking curette as claimed in claim 1 or 2, wherein an the crank shaft that moves up and down has O-ring and an O-ring slot about the nozzle of the support tube, and a cleaning liquid is injected into the nozzle when the crank shaft moves up and down so that the bone tissues remaining around a wing or a housing are selectively removed.

[11] The expandable jacking curette as claimed in claim 3, wherein the housing has a spring home, a spring and a metal ball which are longitudinally provided at an upper end portion thereof, and the indicator connected to the housing has a metal ball hole at a lower end portion thereof such that the metal ball hole matches with a gauge indicating a height of the cutter, thereby maintaining the height of the cutter when manipulating the indicator.