System for tightening orthopaedic fixation screws at two different torque levels

Abstract

An orthopedic implant kit for tightening a set screw to the head of a pedicle screw for holding a spinal rod to the pedicle screw, the kit comprising: a screw extender for holding the head of the pedicle screw, a set screw driver for engaging with the set screw to screw the set screw to the head of the pedicle screw, a first torque limiting mechanism for limiting the torque between the set screw driver and the screw extender to a first torque value or a first torque indicating mechanism for indicating that the first torque has been reached, and a second torque limiting mechanism for limiting the torque between the set screwdriver and the screw extender to a second torque value, the second torque value being higher than the first torque value.

Description

[0001] This application is a divisional application of the PCT international invention patent application with application number 202080034150.8, application date March 26, 2020, and invention name “System for tightening orthopedic fixation screws at two different torque levels”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This patent application claims priority to international patent application serial number PCT / IB2019 / 052453 filed on March 26, 2019, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0004] The present invention relates to orthopedics, and more precisely, to orthopedic tools and systems including pedicle screws, rods and corresponding fixation screws. The present invention also relates to instruments for manipulating these elements, and methods of using these elements to apply torque to fixation screws. Background Art

[0005] In the field of orthopedic and implant tools and systems for orthopedic surgery, more specifically spinal fusion surgery for the spine, a set screw is used to push a rod-type or rod-type device downward and attach it to the head of a pedicle screw. The process of pushing a spinal rod downward toward the head of a pedicle screw is also referred to as rod reduction. Before the rod is attached to the head of the pedicle screw, the pedicle screw is attached to the vertebra using a bone anchor, a threaded bone engaging portion, or a bone screw for fastening the pedicle screw to the vertebra of the patient or creature. For this reason, as an example, for several adjacent vertebrae for vertebral fusion, a pedicle screw is attached to each vertebra, and thereafter, by using a rod placed in a groove or U-shaped opening formed by the pedicle screw head, several pedicle screws are mechanically fastened toward each other, forming a row of pedicle screws along the spine. This allows for providing the mechanical support required for spinal stabilization for the spinal fusion of a patient or creature.

[0006] For example, U.S. Patent No. 10,058,355 (this reference is incorporated herein by reference in its entirety) describes an orthopedic implant kit that provides a pedicle screw, a corresponding fixing screw, a rod, and a tool for operating these, including a screw extender for holding the pedicle screw, and a fixing screw driver for threading the fixing screw relative to the screw head of the pedicle screw. As another example, U.S. Patent No. 8,795,283 (this reference is incorporated herein by reference in its entirety) describes another type of complete set of orthopedic surgical systems for spinal stabilization surgical intervention, including a pedicle screw with a head for receiving a rod, and tools required for surgical intervention. In yet another example, U.S. Patent No. 8,262,662 (this reference is incorporated herein by reference in its entirety) provides a system and method for delivering a spinal connector to a spinal anchoring site in the spine. In one embodiment, a spinal implant and an access device are provided, which include a U-shaped receiver member, a bone engaging member, an extension member, a spinal rod, and a fixing screw.

[0007] As described above, similar orthopedic spine surgery concepts, tools, and devices for attaching rods to pedicle screws via fixation screws have been proposed, such as U.S. Pat. No. 5,129,388, U.S. Pat. No. 5,520,689, U.S. Pat. No. 5,536,268, U.S. Pat. No. 5,720,751, U.S. Pat. No. 5,984,923, U.S. Pat. No. 6,056,753, U.S. Pat. No. 6,183,472, U.S. Pat. No. 6 ... No. 258,090, U.S. Pat. No. 6,454,768, U.S. Pat. No. 6,648,888, U.S. Pat. No. 6,740,086, U.S. Pat. No. 7,618,442, U.S. Pat. No. 8,308,782, U.S. Pat. No. 8,876,868, U.S. Patent Publication No. 2006 / 0025771, and U.S. Patent Publication No. 2018 / 0289397, all of which are incorporated herein by reference in their entirety.

[0008] However, when the surgeon or operator of the spinal surgery tool needs to attach the rod to the pedicle screw via the set screw, the prior art tools still present certain problems, particularly in order to find the appropriate amount of torque that needs to be applied to the set screw in different situations. Therefore, despite all the solutions currently proposed in the related spinal surgery tools of the prior art, significantly improved methods, systems and devices for spinal surgery are strongly desired. Summary of the invention

[0009] According to one aspect of the present invention, a method for tightening a set screw to a head of a pedicle screw for holding a spinal rod is provided, wherein the head of the pedicle screw has a groove for accommodating the spinal rod. Preferably, the method comprises the following steps: threadingly engaging a set screw to the head of the pedicle screw, attaching a set screw driver to the set screw, tightening the set screw to the head of the pedicle screw and the spinal rod for the first time with a first torque, the first torque being limited by a first torque limiting mechanism associated with the set screw driver, or by a first torque indicating mechanism for indicating that the first torque has been reached, and tightening the set screw to the head of the pedicle screw and the spinal rod for the second time with a second torque higher than the first torque, the second torque being limited by a second torque limiting mechanism associated with the set screw driver.

[0010] According to another aspect of the present invention, an orthopedic implant kit for tightening a set screw to the head of a pedicle screw for holding a spinal rod to the pedicle screw is provided. Preferably, the orthopedic implant kit includes a screw extender for holding the head of the pedicle screw, a set screw driver for engaging with the set screw to threadably tighten the set screw to the head of the pedicle screw, a handle for rotating the set screw driver relative to the screw extender, a first torque limiting mechanism for limiting the torque between the set screw driver and the screw extender to a first torque value, or a first torque indicating mechanism for indicating that the first torque has been reached, and a second torque limiting mechanism for limiting the torque between the set screw driver and the screw extender to a second torque value, the second torque value being higher than the first torque value.

[0011] The above and other objects, features and advantages of the present invention and the manner of achieving the same will become more apparent, and the invention itself will be best understood through a study of the following description with reference to the accompanying drawings which illustrate some preferred embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings, which are incorporated herein and constitute a part of this specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description given below, serve to explain the features of the invention.

[0013] Figures 1A-1E Different side views of components of an orthopaedic implant kit 100 having a first torque limiting or indicating feature and a second torque limiting feature are shown, wherein: Figure 1AA side cross-sectional view of an orthopedic tool kit 100 is shown having a pedicle screw 1, a screw head 2, a set screw or fastener 3, a spinal rod 7, a screw extender 6, a set screw driver 26, a first torque handle 25 and a second anti-torque handle 29, Figure 1B Shows Figure 1A The same view of FIG. 2 with some cross-sectional views inside the set screw driver 26, the screw extender 6 and the first torque handle 25, Figure 1C A handle 125 having a torque indicating mechanism 127 (e.g., a torque scale) is shown. Figure 1D A simple handle 225 is shown with or without a ratchet mechanism, and Figure 1E A separate torque limiting mechanism 327 is shown which may be operably placed between the upper shaft 8 or the proximal end of the setscrew driver 26 and the handle 25;

[0014] Figures 2A to 2E Different views of the first and second torque limiting features integrated into the set screw driver 226 of the orthopedic tool kit 100 are shown, wherein Figure 2A shows an exemplary cross-sectional view of a set screw driver 226 having a lower section 220 with a hollow cylindrical or tubular body, an intermediate cylindrical housing 237, and a torque driver 210; Figure 2B A first position of the locking bolt 235 is shown, with a side view of the intermediate cylindrical housing 237 with the locking bolt 235, and also three cross-sectional views 1, 2, 3 in the direction of the center axis of the bolt 235, the first breakable pin 227 and the second breakable pin 228; Figure 2C A second position of the locking bolt 235 is shown, with a side view of the intermediate cylindrical housing 237 with the locking bolt 235, and also three cross-sectional views 1, 2, 3 in the direction of the center axis of the bolt 235, the first breakable pin 227 and the second breakable pin 228; Figure 2D and 2E An alternative embodiment of a bolt 235 engaging a notch is shown, showing a side view of the outer surface of the intermediate cylindrical housing 237 and the bolt 235;

[0015] Figures 3A to 3E Exemplary cross-sectional views of different stages of a method during a spinal stabilization surgery according to another aspect of the invention are shown.

[0016] Herein, where possible, the same reference numerals are used to denote the same elements that are common to the figures. In addition, for illustrative purposes, the images are simplified and may not be drawn to scale. DETAILED DESCRIPTION

[0017] According to one embodiment, Figure 1A and1B As shown in the example, an orthopedic implant kit, instrument kit, tool kit or system 100 is provided, which includes a handle 25, a first torque limiting or indicating device 27, a set screw driver 8 that can include a second torque limiting device 28 that can be rotated by the handle 25, a second counter handle 29, a screw extender 6, the second counter handle 29 is engaged with the set screw driver 6, a set screw 3, a pedicle screw 1 with a screw head 2 and a bone anchor or threaded portion 4, and a spinal rod 7. In the illustrated variation, the first torque limiting mechanism or device 27 that limits the torque application to a first torque level T1 is an integral part, or is fixed or otherwise operably connected to the first handle 25, such as a T-shaped handle, which is used to tighten the set screw 3 to the head 2 of the pedicle screw 1 via the set screw driver 26. The first torque level T1 is a torque applied to the fixation screw 3 relative to the head 2 of the pedicle screw 1, for example, when the fixation screw 3 is threadedly engaged with the head 2 of the pedicle screw 1, and also by abutting or otherwise tightening the spinal rod 7 to the head 2 of the pedicle screw 1. The first handle 25 may have a torque limiting mechanism device 27, which may be removably attached to a fixation screw driver 26 for tightening the fixation screw 3, and may be used as a first torque limiting mechanism, such as a handle 25 attached to the end, proximal end, or another portion of the fixation screw driver 26 of the upper shaft 8. Such handles for tightening screws with torque limiting mechanisms 27 are described in U.S. Patent Nos. 2,826,107, 4,244,434, 4,838,264, 5,347,894, 5,746,298, 6,640,674, 7,197,968, 7,938,046, 8,028,608 and 10,034,701, which are incorporated herein by reference in their entirety. When tightening the fixation screw 3 relative to the screw head 2, a screw extender 6 or a screw head holder is fixed to the screw head 2 of the pedicle screw 1, and a counter handle 29 is attached to the screw extender 6 for anti-torque purposes.

[0018] It is important to apply the right amount of torque to the fixation screw 3 tightened against the spinal rod 7 held by the head 2 of the pedicle screw 1, and it depends on the specific circumstances during the orthopedic surgery operation. In addition, the tightening angle of the fixation screw 3 is also an important aspect, which can be converted into a larger torque, which can then be transmitted to the surrounding tissue, thereby causing the risk of screw loosening, implant fracture and / or adjacent segment disease. The present embodiment describes a solution to the fact that the user, operator or surgeon needs to apply different levels of torque during surgery, and provides a mechanism that significantly simplifies the task. For example, see the following publications: Chapman et al., "Factors Affecting the Pullout Strength of Cancellous Bone Screws", "Journal of Biomechanical Engineering", ASME, Vol.118, 391-398, 1996, and Paik et al., "Biomechanical Consequences of Rod Reset of Pedicle Screws: Should It Be Avoided?", "Spine Journal", Vo.13, No.11, pp.1617-1626, 2013, these references are incorporated herein by reference in their entirety.

[0019] In the variant, Figure 1C As shown in , a first handle 125 with a torque indicating mechanism 127 can be used, instead of a mechanism 27 that physically limits the torque that can be applied to the set screw 3, but some type of indication that the first torque level T1 has been reached is made, such as but not limited to visual, tactile, haptic, vibration, mechanical, audible sound, such as a snap or buzzer, or a combination thereof, or other types of feedback that a user or operator can see, hear or feel, or any combination of these features. This can be done with or without any device that actually limits the physical torque applied to the set screw 3. For example, a first handle 125 combined with a torque measuring mechanism can be used, and the torque measuring mechanism is associated with a torque indicator, scale or gauge 127. For example, a handle 125, a wrench, a screwdriver, a driver, an instrument, a key, a tool or a socket and the like based on the operating principles described in U.S. Pat. Nos. 4,664,001, 5,048,381, 5,734,113, 6,196,071, 6,398,552, 6,928,885, 7,806,026, 8,225,679 and D715,611, all of which are incorporated herein by reference in their entirety, can be used to tighten the set screw 3 via the set screw driver 26 while simultaneously warning or otherwise indicating to the user or operator that the first torque level T1 has been reached.

[0020] The first torque level T1 may be specifically designed to be applied to a lockable polyaxial screw, such as a polyaxial pedicle screw, that can be locked by pressure caused by tightening the spinal rod 7 via the fixation screw 3, as exemplarily shown in U.S. Pat. No. 5,882,350, U.S. Pat. No. 6,113,601, and U.S. Pat. No. 6,660,004, which are incorporated herein by reference in their entirety. Another variant is a Medtronic screw that allows such locking. TM CD Horizon Solera pedicle screw system with a locking ring or seat that can be pushed against the spherical head of the pedicle screw. In this variant, a first torque level between the fixation screw 3 and the screw head 2 is such that when tightened to a torque level T1 in the screw head 2 of the pedicle screw 1, the rotational movement of the spinal rod 7 about its own axis is locked, for example so that the surgeon, user or operator cannot turn or otherwise rotate the rod 7 in the groove of the screw head. However, in the case of torque level T1, the pedicle screw 1 still maintains its polyaxiality because the pressure applied to the upper surface or side surface of the spherical part of the bone anchor 4 and the locking ring or seat is not sufficient to lock the polyaxiality. Preferably, the first torque level T1 is approximately in the range between 0.7 Nm and 2.1 Nm, more preferably about 1.4 Nm.

[0021] Next, a second torque limiting mechanism 28 that limits the torque applied to the fixation screw 3 relative to the head 2 of the pedicle screw 1 to a second torque value or level T2 may be incorporated into the fixation screw driver 26, as shown in U.S. Pat. No. 10,058,355, which is incorporated by reference in its entirety. Figure 1B As shown in the cross-sectional view of , the set screw driver 26 comprises an upper shaft 8, the end of which can be engaged with a first handle 25, 125, 225, for example by different mechanical connection types, and a lower shaft 20 that is hollow for accommodating a torque driver 10. An engagement tool 12 of the torque driver 10 can protrude from the lower surface or distal portion of the lower shaft 20 to be able to engage with the set screw 3 for threaded fastening relative to the screw head 2, having a screw engagement mechanism 12. The torque driver 10 and the lower shaft 20 are locked relative to each other by a breakable pin 28 that traverses at least a portion of the lower shaft 20 and the torque driver 10, forming a second torque limiting mechanism 28, which mechanically limits the amount of torque applied to the set screw 3 via the handle 125 relative to the screw head 2 of the pedicle screw 1 to a second torque level T2. In the illustrated variant, the torque driver 10 is formed by an inner bolt, rod or shaft surrounded at the bottom by the lower shaft 20.

[0022] The second torque level T2 is the final torque to be applied to the rod 7 and the screw head 2 via the fixing screw 3, and is significantly higher than the first torque level. Since the second torque level is the final level to be applied to the fixing screw 3, the torque limiting mechanism may be irreversible or may make it impossible to apply a higher torque level to the fixing screw 3. Preferably, the second torque level T2 is approximately in the range of 8 Nm to 12 Nm, more preferably about 10 Nm.

[0023] The set screw driver 26 has an external thread that can be threadedly engaged with the internal thread of the screw extender, having the same pitch as the thread of the set screw. This allows the user or operator to place the set screw 3 onto the front portion of the torque driver 10 of the set screw driver 26, and then threadedly engage with the internal thread of the screw extender 6 to rotate or rotate the set screw 3 downward through the screw extender together with the set screw driver 26 until the set screw 3 contacts and threadedly engages with the internal thread of the head 2 of the pedicle screw 1. When the set screw 3 is threadedly fixed in the head 2 and the set screw driver 26 continues to be rotated or rotated by the handle 125, 225, once the front face FF of the set screw 3 contacts the spinal rod 7, the torque increases until the point where the pin 28 breaks. The pin 28 is designed and sized to maintain torque to a second torque level T2 and will break when the second torque level T2 is exceeded. Once the pin 28 breaks, further rotation of the set screw driver 26 therefore no longer affects the rotation and threaded engagement of the set screw 3 within the head 2 of the pedicle screw 1, because the set screw driver 26 will no longer rotate the torque driver 10. In other words, the set screw driver 26 can rotate freely without rotating the torque driver 10. Therefore, when the second torque limiting mechanism 28 (a breakable pin in the illustrated variation) is activated or effective, that is, when the second torque level T2 has been reached and the pin 28 breaks, when the user or operator rotates the set screw driver 26 by holding the handle 125, the set screw driver 26 will be threadedly advanced downward toward the set screw 3 without rotating the set screw 3. In turn, the pedicle screw 1 will gradually be pushed away and released from the screw extender 6. The second handle 29 is removably attached to the screw extender 6 so that the user or operator can tighten the set screw 3 into the head 2 of the pedicle screw 1 with one hand while holding the head 2 of the pedicle screw via the screw extender 6 and the second handle 29. This operating principle of the second torque limiting mechanism 28 integrated with the set screw driver 26 is also shown in FIGS. 13A-13C, 14 and 15 of U.S. Pat. No. 10,058,355, which is incorporated herein by reference in its entirety. It is also possible to combine the second torque limiting mechanism with a torque indicating mechanism, or not to limit the torque to the torque level T2, but only to indicate it.

[0024] The first torque limiting mechanism 27 or the first torque indicating mechanism 127 is preferably designed so that the first torque level T1 is less than the second torque level T2 applied by the second torque limiting mechanism 28, for example by a factor that is bigger than five. This means that in the case where the first torque limiting mechanism 27 is used with the handle 25, once the first torque level is reached, the handle 25 can no longer increase the torque that can be applied to the set screw 3. Therefore, this requires the user or operator to remove the handle 25 from the set screw driver 26 and replace the handle 25 by placing another handle to the set screw driver 26, such as a handle 25 with a mechanism that limits the torque to a second, higher torque level T2, a handle 125 with only a torque indicating mechanism 127, or another type of handle 225 without torque limitation or indication, so that the second, higher level of torque can be applied to the set screw 3 until the second torque level T2 is reached. In the case where the handle 125 is used, the same handle can be used to apply the first torque level T1 and the second torque level T2, for example by having a scale that shows two different torque levels T1 and T2.

[0025] As another example, the torque limiting mechanism or device 327 can be a separate device that is not integral with the handle 25, 125, but can be placed between the handle 25 and the set screw driver 26, such as a handle 25 that is not equipped with a different type of torque limiting or indicating mechanism, such as Figure 1E As shown in . For example, the torque limiting mechanism 327 or device can be embodied as a proximal end that is removably connected to the upper shaft 8 or the set screw driver 26 and the handle 25, 125, for example, as a mechanical connection element having a ratchet-type or bendable lever or protrusion that engages with the recessed portion, and also includes two interconnecting elements for interconnecting between the handle 25 and the set screw driver 26. In this regard, two different torque limiting mechanisms or devices 327 can be used in this arrangement, one for torque level T1 and one for torque level T2, and the two mechanisms or devices can therefore be visually marked. As another variation, at the area where the handle 225 is to be connected to the screw extender 6, the torque limiting or indicating mechanism 27, 127, 327 can be part of or integrated into the proximal end of the upper shaft 8 or the set screw driver 26.

[0026] In another variation, a torque limiting mechanism or torque indicating mechanism for measuring or applying torque limitation can be integrated or connected between the handle 29 and the screw extender 6, or by having a torque limiting or torque indicating mechanism for measuring or applying torque limitation between the handle 29 and the screw extender 6, and having a torque limiting or torque indicating mechanism for measuring or applying torque limitation between the handle 25, 125, 225 and the fixing screwdriver 26.

[0027] In another variation, Figure 2A-2C , a first torque indicating mechanism is integrated into a set screw driver 326 together with a second torque limiting mechanism 228 as a frangible pin. In this variant, the set screw driver 326 comprises a cylindrical hollow area in the lower section 220, which houses the torque driver 210 with an engagement tool 212 for engaging with the set screw 3 at the distal end, but also an intermediate cylindrical housing, tube or barrel 237, which is located between the lower section 220 of the set screw driver and the torque driver 210. The first torque indicating mechanism is arranged to mechanically cooperate between the torque driver 210 and the intermediate cylindrical housing 237, with a locking bolt 235 engaged with a transverse slot 238, and a first frangible pin 227 that traverses both the torque driver 210 and the intermediate cylindrical housing 237. In a first position, the rotational or pivoting movement between the torque driver 210 and the intermediate cylindrical housing 237 is locked by the first frangible pin 227, thereby limiting the torque that can be applied to a first torque level T1. For this purpose, the first breakable pin 227 is sized and designed to break when a torque is applied at a first torque level between the torque driver 210 and the intermediate cylindrical housing 237. In other words, the breaking of the pin 227 can be considered as releasing the first torque retention mechanism embodied by the pin 227. In the second position, the rotation between the torque driver 210 and the intermediate cylindrical housing 237 is again blocked by the wall 239 of the transverse slot 238.

[0028] The first position is Figure 2B 1, 2, 3 along the central axis of the set screw driver 326. When a low torque below the first torque level T1 is applied with the set screw driver 326 (e.g., with the handle 125, 225), the locking bolt 235 abuts against the side wall 241 of the transverse groove 238, and the first breakable pin 227 has not yet broken. When the first torque level T1 between the torque driver 210 and the intermediate cylindrical housing 237 is exceeded, the first breakable pin 227 will break, as shown in FIG. Figure 2C 4. This will produce a mechanical shake or tremor to the set screw driver 326 that can be felt by the user, and will also produce an audible snap or click that can be heard by the user, and can provide a signal to the user that the first torque has been reached, as a first torque indication mechanism. Next, the locking bolt 235 will move from contact with the side wall 241 and will move through the transverse slot 238 to abut against the other side wall 239 and be locked again thereby to transition from the first position to the second position by rotating a specific angle defined by the length of the transverse slot 238 between the torque driver 210 and the intermediate cylindrical housing 237, as represented by the second position. Figure 2C The three cross-sections of FIG. 4 , 5 and 6 are shown. The locking bolt 235 will then abut against the side wall 241 of the transverse groove 238 .

[0029] The intermediate cylindrical housing 237 and the lower section 220 of the set screw driver 326 are still locked together with the second breakable pin 228 that requires a higher second torque level T2 to break. In this regard, the pin 228 can be considered as a second torque holding mechanism that holds the two elements 237 and 220 together until the second torque level T2 is reached and will release when the second torque level T2 is reached. In this regard, as an example, one or two (2) or more second breakable pins 228 are arranged 180 degrees relative to each other to lock the rotation of the set screw driver 226 with the lower section 220 relative to the intermediate cylindrical housing 237 until the higher, second torque level T2 is applied. In a variant, there can be several breakable pins 228. For controlled breaking, it is preferred to have only one second breakable pin 228.

[0030] Instead of pins 227, 228, other types of breakable, bendable, releasable, retainable devices may be used which, when a specific torque threshold level is applied, can release the rotational lock between the intermediate cylindrical housing 237 and the fixing screw driver 326 at a second torque level T2 to form a second torque retaining mechanism, or release the rotational lock between the torque driver 210 and the intermediate cylindrical housing 237 at a first torque level T1 to form a first torque retaining mechanism, such as but not limited to a breakable plate, a breakable hook, a lever, a ratchet-type fastening element that can be released when a threshold torque is applied, a recessed structure.

[0031] In addition to the breaking of the first breakable pin 227 and the sliding of the bolt in the transverse slot 238, which causes the torque driver 210 to rotate a limited angle relative to the intermediate cylindrical housing 237, an additional mechanism can be provided to further warn the user, operator or surgeon operating the set screw driver 326 that the first torque level has been reached. In the illustrated variant, during the transition from the first position to the second position by the locking bolt 235, in other words, during the sliding of the bolt 235 from the wall 241 to 239 of the slot 238, the protrusions 272 to the lower or upper side walls of the transverse slot 238 are made so that the passing of the locking bolt 235 over these protrusions 272 will produce a snapping or ratcheting sound, and also produce a vibration that the user, operator or surgeon can hear and feel. In the illustrated variation, a plurality of thin longitudinal grooves 271 are arranged starting from the lower side wall or the upper side wall of the transverse groove 238, with a small protrusion 272 at the top, the protrusion being designed to transition the locking bolt 235 from the first position to the second position with a very small additional torque, which is less than or significantly less than the first torque level T1, thereby generating vibration or ratcheting sound when the locking bolt 235 passes over these protrusions 272.

[0032] Other mechanisms may be used to generate additional indications to the user, operator, or surgeon that the first torque level T1 has been reached, such as Figure 2DAs shown in FIG. 1 , the lever 275 has teeth, notches, or a laterally extending arrangement parallel to the transverse slot 238 that engages with the teeth, notches, cogs, pinions, ratchet wheels 276 of the locking bolt 235, which will produce a ratcheting sound and vibration when transitioning from the first position to the second position. Another example is shown in FIG. Figure 2E As shown in FIG. 2 , two levers 278 are symmetrically arranged on the upper and lower sides of the transverse slot 238, the bolt 235 has a square or rectangular cross-section, and the lever 278 has a sawtooth shape to ensure that the transition from the first position to the second position can only occur once in one direction. The direction of the sawtooth will prevent the bolt 235 from moving backward through the transverse slot 238. Instead of a lever, a portion of the intermediate cylindrical housing 237 may have an edge with sawtooth, wavy or triangular teeth, and a portion of the bolt 235 has corresponding sawtooth, wavy or triangular teeth, respectively, which are pushed together by a spring mechanism. The biasing force of the spring mechanism that pushes the corresponding teeth together can be designed to provide a first torque level T1.

[0033] Using the above embodiments, the breaking of the first frangible pin 227 or the snapping of the bolt 235 against the rough, recessed or serrated structure (e.g., lever 275 or protrusions 272, 276) when the bolt 235 transitions through the transverse slot 238, or a combination of the two, produces audible, snapping and vibration feedback to the user, operator or surgeon who is operating the handles 125, 225 and handle 29 with his hands to tighten the set screw 3 to reach and exceed the first torque level T1 without using different handles or using a scale that needs to read the torque level. The breaking of the first frangible pin 227 will produce a slight shaking, snapping or cracking sound, while the recessed structure will emit a vibration and snapping sound to ensure that the user will determine that the first torque level on the set screw 3 has been reached. In addition, the recessed structure can also provide mechanical retention for the rotational movement between the torque driver 210 and the intermediate cylindrical housing 237, and can itself serve as a torque limiting mechanism for the first torque level T1.

[0034] As another variation, the first breakable pin 227 is absent, but the protrusion 272 or lever 275 or ratchet-like element is designed to prevent the locking bolt 235 from sliding within the transverse slot 238 to provide mechanical retention when torque is applied between the torque driver 210 and the intermediate cylindrical housing 237 until the first torque level T1 is reached, wherein the bolt 235 moves, transitions or slides to the sidewall 239 of the transverse slot 238. The lever 275 and its length and mass, the protrusions 272, 276 and the longitudinal slot 271 can be designed to emit a specific acoustic sound audible to the user, surgeon or operator when the bolt 235 slides through the transverse slot 238. In the absence of the first breakable pin 227, the torque driver 210 can be rotated back relative to the intermediate cylindrical housing 237 so that the first position is reached again to have a reversible mechanism indicating the first torque level. In this regard, the first torque limiting mechanism and the first torque indicating mechanism may be integrated into a common device, such as by a ratchet-type device having one or more notches that engage with the sawtooth or wave-shaped structure, as described above.

[0035] In the context of the present invention, the first breakable pin 227 and Figure 2B and 2C The longitudinal groove 271 and the protrusion 272 shown in Figure 2D and 2E Other types of retaining mechanisms shown in the figures having a lever 275 and protrusions 272, 276, 279 describe different devices referred to herein as first torque retaining mechanisms, which can be used as an indicator when a first torque is exceeded or reached, or as a torque limiter to limit the application of the first torque to a first torque level, or both.

[0036] According to another aspect, a method is provided for placing a spinal rod 7 into the heads 2 of a series of pedicle screws 1 and tightening or securing a set screw 3 to the heads, such as Figures 3A to 3E In these figures, different stages of the method are shown, showing by way of example three pedicle screws 1.1 to 1.3 attached to three vertebrae V1 to V3, but using a different number of pedicle screws 1.1 to 1.3 and a different number of vertebrae V1 to V3 is also within the scope of this embodiment. These figures schematically and exemplarily show three adjacent vertebrae V1 to V3, each vertebra having a pedicle screw 1.1, 1.2 and 1.3 attached thereto, respectively, with corresponding bone anchors 4.1, 4.2 and 4.3. In Figure 3A Before being shown in FIG. 1 , none of the screw heads 2.1, 2.2 and 2.3 of the pedicle screws 1.1, 1.2 and 1.3 has a spinal rod 7 inserted therein. Figure 3AAs shown in , the user first places the left side of the spinal rod 7 into the screw head 2.1 by moving the spinal rod 7 in the direction B1 so that the rod 7 is placed in the U-shaped groove of the head 2.1, and then threadably but loosely attaches the fixation screw 3.1 to the screw head 2.1 to ensure that the rod 7 does not leave the U-shaped groove of the screw head 2.1. Typically, the spinal rod 7 will have a pre-bent shape, which will be the desired shape of the spine for fusion, so that the adjacent vertebrae V1 to V3 will be pushed by the spinal rod 7 to the desired arrangement adjacent to each other.

[0037] Next, if Figure 3B As shown in FIG, by using the instrument or tool kit 100 as described above, the set screw 3.1 is screwed down into the screw head 2.1 to abut against the rod 7 and threadedly attached to the head 2.1 by a first torque level T1, at which point the pre-bent rod 7 is located within the U-shaped grooves of the two adjacent heads 2.2 and 2.3. After this, the user threadably but loosely attaches the set screw 3.2 to the screw head 2.2. Next, as Figure 3C As shown in , the set screw 3.2 is screwed down into the screw head 2.2 to abut against the rod 7 and threadedly attached to the head 2.2 by a first torque level T1, again by using the instrument or tool kit 100 as described above. After this, the user threadably but loosely attaches the set screw 3.3 to the screw head 2.3.

[0038] Afterwards, if Figure 3D As shown in FIG, the fixing screw 3.3 is screwed down into the screw head 2.3 again by using the instrument or tool kit 100 to abut against the rod 7 and is threadedly attached to the screw head 2.3 by a first torque level T1. At this stage, all pedicle screws 1.1, 1.2 and 1.3 are attached to the rod 7 by the fixing screws 3.1 to 3.3, which are tightened by torque at the first torque level T1. Next, as Figure 3E As shown in , from left to right, each fixing screw 3.1, 3.2 and 3.3 is tightened at a second torque level T2 to complete spinal stabilization with the spinal rod 7. This is accomplished by using the second torque limiting feature of the tool kit 100. For each fixing screw 3.1, 3.2 and 3.3, a different tool kit 100 is used. Generally, since the spinal rod 7 has a pre-bent shape, the spinal rod 7 can be placed in two or more pedicle screw heads at a time, and then the fixing screws 3.1 to 3.3 are tightened one by one in sequence along the spinal rod 7 from either direction. Using this method, the tightening steps can be reduced to a single instrument kit, or even to a single instrument itself as described above, thereby saving a lot of operating time and cost.

[0039] Although the present invention has been disclosed with reference to certain preferred embodiments, many modifications, changes and variations of the described embodiments and their equivalents are possible without departing from the spirit and scope of the present invention. Therefore, it is intended that the present invention not be limited to the described embodiments, but rather be given the broadest reasonable interpretation according to the language of the appended claims.

Claims

1. An orthopedic implant kit, the orthopedic implant kit being used to tighten a fixing screw onto the head of a pedicle screw, the kit comprising: A screw extender, the screw extender is used to hold the head of the pedicle screw; a set screw driver for engaging the set screw to threadably tighten the set screw relative to the head of the pedicle screw; a first torque limiting mechanism or a first torque indicating mechanism, the first torque limiting mechanism being used to limit the torque between the set screw driver and the screw extender to a first torque value, the first torque indicating mechanism being used to indicate that the first torque value has been reached between the set screw driver and the screw extender; as well as A second torque limiting mechanism is used to limit the torque between the fixing screw driver and the screw extender to a second torque value, and the second torque value is higher than the first torque value.

2. The orthopedic implant kit according to claim 1, wherein: The first torque limiting mechanism or the first torque indicating mechanism and the second torque limiting mechanism are integrated into the setscrew driver.

3. The orthopedic implant kit according to claim 1, further comprising: A handle is provided for rotating the set screw driver relative to the screw extender, the first torque limiting mechanism or the first torque indicating mechanism is arranged between the handle and the set screw driver, and the second torque limiting mechanism is integrated into the set screw driver.

4. The orthopedic implant kit according to claim 1, further comprising: A handle for rotating the set screw driver relative to the screw extender, the first torque limiting mechanism or the first torque indicating mechanism is configured to be arranged between the handle and the set screw driver, and the second torque limiting mechanism is configured to be arranged between the handle and the set screw driver.

5. The orthopedic implant kit according to claim 2, wherein: The fixing screw driver comprises: a shaft having a set screw engaging portion; a tubular element surrounding the shaft; and an outer housing surrounding the tubular element, the outer housing having external threads for threadingly engaging the internal threads of the screw extender, The first breakable pin is arranged between the tubular element and the outer shell, forming a part of the first torque limiting mechanism or the first torque indicating mechanism, and the second breakable pin is arranged between the tubular element and the shaft, forming the second torque limiting mechanism.

6. The orthopedic implant kit according to claim 5, wherein: The fixing screw driver also includes: Means for producing at least one of a vibration or a sound when the first frangible pin as part of the first torque indicating mechanism breaks.

7. The orthopedic implant kit according to claim 6, wherein: The mechanism comprises a protrusion that engages with a recessed portion of the side wall of the tubular element.

8. The orthopedic implant kit according to claim 4, wherein: The fixing screw driver also includes: A bolt is used to prevent rotational movement between the tubular element and the outer shell after the first frangible pin breaks.

9. The orthopedic implant kit according to claim 1, wherein: The first torque indicating mechanism includes at least one of: a torque scale, a mechanism that produces vibration when the first torque value is exceeded, a mechanism that produces shaking when the first torque value is exceeded, and a mechanism that produces an audible sound when the first torque value is exceeded.

10. A method for tightening a fixing screw, the method tightening the fixing screw to the head of a pedicle screw for holding a spinal rod, the head of the pedicle screw having a groove for receiving the spinal rod, the method comprising the steps of: threadably engaging a set screw to the head of the pedicle screw; attaching a setscrew driver to the setscrew; tightening the set screw to the head of the pedicle screw and the spinal rod for the first time with a first torque limited by a first torque limiting mechanism associated with the set screw driver or by a first torque indicating mechanism for indicating that the first torque has been reached; and The set screw is tightened a second time to the head of the pedicle screw and the spinal rod using a second torque higher than the first torque, the second torque being limited by a second torque limiting mechanism associated with the set screw driver.

11. The method for tightening a set screw according to claim 10, wherein: During the first tightening and second tightening steps, the first torque limiting mechanism and the second torque limiting mechanism act between the set screw driver and the head of the pedicle screw to which the screw extender is removably attached.

12. The method for tightening a set screw according to claim 10, wherein: The first torque level is such that the spinal rod cannot be rotated within the recess by manual manipulation while maintaining the polyaxiality of the pedicle screw.

13. A set screw driver for an orthopedic implant kit having a screw extender for tightening a set screw into a head of a pedicle screw, the set screw driver comprising: a first torque limiting mechanism or a first torque indicating mechanism, the first torque limiting mechanism being used to limit the torque between the set screw driver and the screw extender to a first torque value, the first torque indicating mechanism being used to indicate that the first torque value has been reached between the set screw driver and the screw extender; as well as A second torque limiting mechanism is used to limit the torque between the fixing screw driver and the screw extender to a second torque value, and the second torque value is higher than the first torque value.

14. The set screw driver of claim 13, further comprising: a shaft having a set screw engaging portion; a tubular member surrounding the shaft; as well as an outer casing surrounding the tubular element, Wherein, a first frangible pin or ratchet type device is arranged between the tubular element and the outer shell, forming part of the first torque limiting mechanism or the first torque indicating mechanism, and a second frangible pin is arranged between the tubular element and the shaft, forming the second torque limiting mechanism.

15. The set screw driver according to claim 14, wherein: The fixing screw driver also includes: A bolt is used to prevent rotational movement between the tubular element and the outer housing after the breakage of the frangible pin or the release of the ratchet-type device.

16. The set screw driver according to claim 13, wherein: The first torque indicating mechanism includes at least one of: a mechanism that generates vibration when the first torque value is exceeded, a mechanism that generates shaking when the first torque value is exceeded, and a mechanism that generates an audible sound when the first torque value is exceeded.

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