Surgical needle

Abstract

A relatively thin-walled surgical needle according to the present specification includes a trocar having a trocar-tip and a stylet having a stylet-tip and which is removably receivable within the trocar. The trocar-tip and the stylet-tip can form a contiguous piercing surface when stylet is received within the trocar.

Description

Surgical NeedleFIELD

[0001] The present specification relates generally to medical needles and more particularly to surgical needles for use in procedures such as vertebroplasty or biopsies.BACKGROUND

[0002] Image-guided surgical procedures equip highly skilled surgeons with advanced visualization capabilities that extend beyond traditional senses such as sight and touch. Technologies like X-ray, Computed Tomography (CT), Magnetic Resonance Imaging (MRI), and ultrasound enhance the surgeon's ability to perform procedures by providing internal views of the patient. This approach reduces the necessity for large incisions that splay the target area to permit visual access to internal structures, thereby reducing patient trauma and shortening healing times. Moreover, these technologies alleviate the need for surgeons to rely on tactile sensation and mental visualization based on experience and anatomical training. Collectively, these advancements fall under the category of 'minimally invasive surgery,' which aim to reduce physical intervention and improve patient outcomes.

[0003] The equipment for advanced visualization is complex and costly, often presenting logistical challenges when integrating into the surgical environment. Allowing surgeons to have both physical access to the patient's target area and immediate, actionable visual information for the procedure demands careful coordination. Additionally, there is a concern for the surgeon's health, as these procedures may involve repeated exposure to potentially harmful radiation.SUMMARY

[0004] An aspect of the specification provides a surgical needle including: a trocar having a trocar-tip; a stylet having a stylet-tip and removably receivable within the trocar; the trocar-tip and the stylet-tip forming a contiguous piercing surface when stylet is received within the trocar; and, the trocar having a wall thickness of less than about 0.229 millimeters.

[0005] An aspect of the specification provides a needle wherein the wall thickness is less than about 0.22 millimeters.

[0006] An aspect of the specification provides a needle wherein the wall thickness is less than about 0.2 millimeters.

[0007] An aspect of the specification provides a needle wherein the wall thickness is less than about 0.15 millimeters.

[0008] An aspect of the specification provides a needle wherein the wall thickness is less than about 0.13 millimeters.

[0009] An aspect of the specification provides a needle wherein the wall thickness is less than about 0.130 millimeters.

[0010] An aspect of the specification provides a needle wherein the wall thickness is about 0.127 millimeters.

[0011] An aspect of the specification provides a needle wherein the trocar is between about an 8 gauge and about a 22 gauge and the stylet is about one gauge greater than the trocar.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Certain non-limiting example embodiments will now be discussed in relation to the attached Figures in which:

[0013] Figure 1 shows a side-elevation view a surgical needle in accordance with an embodiment.

[0014] Figure 2 shows an exploded view of the surgical needle of Figure 1 , with the stylet removed from the trocar.

[0015] Figure 3 shows a portion of the exploded view of Figure 2 focusing on the tip of the needle.

[0016] Figure 4 shows a variation on the tip shown in Figure 3.

[0017] Figure 5 shows a partial sectional view of the body of needle of Figure 1 towards its tip.

[0018] Figure 6 shows a real-world comparison of a prior art surgical needle in comparison with a surgical needle according to the present specification, under CT Image guidance.DESCRIPTION

[0019] Referring now to Figures 1 and Figure 2, a surgical needle is indicated generally at 100. Surgical needle 100 can be used for a variety of procedures, but in a presently preferred embodiment, needle 100 can be used for an image guided intervention such as vertebroplasty or a biopsy.

[0020] Needle 100 comprises a body 104 between a handle 108 and a tip 112. As best seen in Figure 2, needle 100 separates into a stylet 100-1 and a trocar 100-2. Needle 100 can also be reassembled from the separated state in Figure 2 to the assembled state in Figure 1 . Stylet 100-1 thus includes a body 104-1 between a stylet handle 108-1 and stylet-tip 112-1 , while trocar 100-2 includes a body 104-2 between trocar handle 108-2 and a trocar-tip 1 12-2.

[0021] Stylet handle 108-1 and trocar handle 108-2 of Figure 2 combine to form handle 108. As best seen in Figure 1 , a locking mechanism 116, such as a luer-lock or mechanical equivalent, releasably affixes stylet handle 108-1 to trocar handle 108-2 to create the unitary handle 108 of Figure 1 . Stylet handle 108-1 and trocar handle 108-2 can be thus aligned and twisted together and locked securely. The locking mechanism maintains stylet 100-1 and trocar 100-2 in a fixed position relative to each other during a procedure, mitigating risk of accidental dislodgement or movement that could compromise safety and effectiveness.

[0022] Note that trocar 100-2 is hollow while stylet 100-1 is solid. Expressed differently, body 104-2 is a tube while body 104-1 is a shaft that coaxially fits within body 104-2. This coaxial relationship will be discussed further below.

[0023] Stylet-tip 112-1 and trocar-tip 112-2 form the respective distal ends of body 104-1 and body 104-2. As best seen in Figure 3, stylet-tip 1 12-1 and trocar-tip 1 12-2 are formed in complementary fashion to provide a contiguous piercing surface for needle 100 in the assembledstate of Figure 1 . It will thus be appreciated that the overall length of body 104-1 and length of body 104-2 are chosen to provide such a contiguous piercing surface. Machining of tip 112 can, for example, be done from a purely cylindrical pairing of body 104-1 and body 104-2.

[0024] In Figure 3, tip 112 can be described as a multi-faceted taper, reminiscent of a pyramid shape. The delineated area suggests a transition point where the sides of the taper begin, forming a sharp and angular profile that converges to a point. This design can provide for precise penetration, where the multi-sided taper facilitates easy insertion with minimal resistance.

[0025] The exact shape of the tip 112 is not particularly limited. Other tip geometries can also provide smooth insertion, reduce resistance and address other factors for safe and effective treatment of the patient. Figure 4 shows a tip 112a, which is a non-limiting illustrative variant of tip 112. In Figure 4, like elements bear like references followed by the suffix “a”. Tip 1 12a, and its constituents, stylet-tip 112a-1 and trocar-tip 112a-2, present a cylindrical form intersected by an angular plane, resulting in a tapered profile. This intersection creates a chisel-like tip, with the angular cut allowing for a sharp, precise point that for piercing tissue. The cylindrical base provides a smooth initial entry, while the angular taper facilitates penetration with increased control and accuracy. This geometry combines the uniformity of a cylinder with the incisive quality of an angled slice, optimizing the needle for medical application. Other variations on the shape of tip 112 will now occur to those of skill in the art.

[0026] In operation, needle 100 is initially placed in the assembled state of Figure 1 . The surgeon grasps handle 108 and directs tip 112 into the target site of a patient. In a vertebroplasty context, for example, tip 112 passes through several layers of tissue including the skin, subcutaneous tissue including musculature, ligaments, fascia and ultimately through a dorsal surface of the vertebra, such as the pedicle, until it reaches the vertebral body, the ultimate injection site for the bone cement. The exact path can vary depending on the technique (transpedicular, extrapedicular, or anterolateral approach), the patient’s anatomy, and the specific vertebra being treated. As mentioned, the procedure is typically performed under image guidance.

[0027] Thus a person of skill in the art will appreciate that several mechanical factors are considered when devising the structure of needle 100. For example, the shape of tip 112 andthe rigidity of body 104 are important mechanical factors in the structure of needle 100 in order to elegantly pierce the tissue and safely reach the injection site. At the same time, the handle 108 is formed to ergonomically conform to the surgeon’s hand. The exact shape of the handle 108, however, is not particularly limited.

[0028] Further factors regarding the mechanical structure of body 104 include providing an exterior diameter of body 104 that is minimally invasive to the patient during insertion, while providing trocar 100-2 with an interior diameter engineered to facilitate optimal flow of the bone cement under applied pressure, providing efficient and controlled delivery to the target site within the vertebra. Another factor in the selection of diameters is the reduction of beam hardening artifacts in the imaging system to provide improved visualization for the surgeon. A still further factor is reducing the time for the overall procedure, which reduces potential harmful exposure of ionizing radiation to both the patient and in particular the surgeon who can experience a harmful accumulation of doses for every procedure that is performed. Even an overall fractional reduction in procedure times accumulate to free-up operating theatres for additional procedures.

[0029] In addition because its possible to see the interior of trocar 100 — 2 it is possible to identify material within the lumen of the trocar 100-2 under image guidance. For example, in the case of a biopsy, it can be possible to confirm that a tissue sample has been successfully extracted and drawn into trocar 100-2, before the trocar 100-2 is removed the patient. This presents an advantage over prior art trocars, where beam hardening artifcacts obscure the lumen of the trocar, and accordingly, with prior art trocars, the trocar has to be completely removed from the patient so the stylet can be passed back down to see if a sample emerges from the end of the trocar. If no sample emerges, then the procedure has to begin again, re-entering the patient. Accordingly, the prior art can lead to increased trauma to the patient as repeated attempts at extracting a viable sample may be required. Indeed, the trauma can be sever and on occasion, biopsies lead to patient depth. Trocar 100-2 reduces this risk due to the visibility of the lumen under image guidance.

[0030] Thus the present specification provides a novel needle 100 where various gauges of body 104 and the gauges of its constituents, stylet body 104-1 and trocar body 104-2, can be chosento consider at least one or more of the foregoing factors. Referring now to Figure 5, a partial sectional view of needle 100 is shown along body 104. (Handle 108 is not shown in Figure 5 for illustrative convenience.) Figure 5 highlights certain relevant dimensions of body 104. Notably, Dimension A corresponds to the outer diameter of trocar body 104-2, Dimension B corresponds to the inner diameter of trocar body 104-2 and Dimension C corresponds to the to the thickness of the wall 120 of trocar body 104-2. Dimension C is thus a function of Dimension A minus Dimension B. Table I shows a list of example dimensions according to the present specification. Dimension D corresponds to the outer diameter of stylet body 104-1 .TABLE I

[0031] The data populated in Table I thus show a range of dimensions that provides an external Diameter A while providing an increased interior Diameter B, thus preserving a thickness of wall for Dimension C that: a) reduces beam hardening artifacts of trocar body 104-2 under image guidance; b) reduces tissue damage; c) provides as a passage of interior Dimension B as to control pressurized introduction of bone cement into the target area without overflow; d) during such introduction, provides a Dimension C (ie. Thickness of wall 120 of body 104-2) to withstandthe pressure of the bone cement without rupture or deformation. Indeed, it is believed that overall pressure for injection can be reduced by about 40% over prior art needles, as compared to the prior art needles where about 800 to about 1200 psi is used, or even higher for water pressure injection techniques.

[0032] Also note that, as per Table I, Dimension D is smaller than Dimension B. In other words, the exterior diameter of stylet body 104-1 is smaller than interior diameter of trocar body 104-2. The difference between Dimension B and Dimension D represents the gap between the stylet body 104-1 and the trocar body 104-2. A sufficient gap is maintained in order to allow easy insertion and removal, while also supporting the rigidity of the needle 100 during insertion, and providing the contiguous piercing tip 112.

[0033] It is to be understood that even though gauges may be expressed in Table I according to a particular standard, those gauge standards are based on manufacturing standards according to the “Birmingham Gauge” (also known as the “Stubs Iron Wire Gauge”) rather than reflecting what dimensions may be selected within the scope of this specification. In other words, nonstandard gauges are contemplated; there is no need to specifically adhere to standard gauges if other dimensions within those ranges are manufactured according to the ranges in this specification. Thus, intermediate values and ranges to those expressed in Table I are contemplated. Furthermore, since the Birmingham Gauge standard was originally expressed in inches, the degree of precision expressed in millimeters those example dimensions should not be construed as limiting. Hence, this context can be considered by the skilled artisan when construing the term “about” as used herein in relation to dimensions.

[0034] In general terms, beyond Table I, the present specification contemplates a trocar body 104-2 of between about an 8 gauge and about a 22 gauge, and a corresponding stylet body 104-1 of one gauge greater than the trocar body 104-2.

[0035] In variants, where needle 100 is used for biopsies, including image guided biopsies, such considerations are similar except focus on the extraction of tissue samples from the target site rather than the introduction of bone cement or co axial biopsy devices or therapeutic liquids or drug delivery or eluting materials. The chosen dimensions for biopsies from Table I may thusbe different from the chosen dimensions for vertebroplasty. In the case of biopsies, it can also be noted that the wider lumen of trocar 100-2 can allow for the use of a larger biopsy gun as compared to the prior art. As Table I shows, stylet body 104-1 can be one gauge higher than trocar body 104-2, meaning that the biopsy gun of one gauge higher would also be usable. In the case of prior art trocars, typically the biopsy gun would be at least two gauges higher than the trocar.

[0036] It will now be appreciated by a person skilled in the art that the material chosen to construct body 104 need not be particularly limited although the inventor provides these comments. A presently preferred material for body 104 is stainless steel, which can be constructed according to the specifications discussed herein Again, the material is not particularly limited subject to manufacturability according to the specifications described herein, generally including materials that are medical grade and which are strong, durable, and biocompatible, and according to presently known materials, typically are one of stainless steel, titanium, tungsten or nitinol, again subject to manufacturability. Materials that reduce beam hardening artifacts under image guidance may be preferred. Thus, a range of presently known or future devised materials (considering presently known or future manufacturing techniques for those materials) that accord with the specifications herein are contemplated.

[0037] While the foregoing discusses certain embodiments, it is to be understood and emphasized that further variations, combinations, and / or subsets of the embodiments are contemplated. For example, trocar body 104-1 may have a lubricious coating such as silicone, hydrophilic polymer coatings, polytetrafluoroethylene (PTFE), heparin, hydrogel, polyvinylpyrrolidone (PVP) and even diamond-like carbon coatings may be chosen, again subject to biocompatibility and other considerations understood by those skilled in the art. Stylet body 104-1 (and / or body 104-2) may also be provided with a lubricious coating, although chosen not to interfere with the bone cement and / or considering biocompatibility on the interior of a vertebra. Additional coatings may be considered, such as amino caproic acid to reduce bleeding.

[0038] The present specification provides certain advantages over the prior art. For example, prior art needles have trocars with thicker walls than those shown in Table I. Notably, prior art needles typically have a wall thickness equal to or greater than about 0.229 millimeters, vs the embodiments discussed herein which have a wall thickness (Dimension “C”) of about 0.127mm. Thus, according to the present specification, a trocar body 104-2 having a wall thickness “C” of less than about 0.229 millimeters is contemplated. Likewise a trocar body 104-2 having a wall thickness of less than about 0.22 millimeters is contemplated. Likewise a trocar body 104-2 having a wall thickness of less than about 0.21 millimeters is contemplated. Likewise a trocar body 104-2 having a wall thickness of less than about 0.20 millimeters is contemplated. Likewise a trocar body 104-2 having a wall thickness of less than about 0.2 millimeters is contemplated. Likewise a trocar body 104-2 having a wall thickness of less than about 0.19 millimeters is contemplated. Likewise a trocar body 104-2 having a wall thickness of less than about 0.18 millimeters is contemplated. Likewise a trocar body 104-2 having a wall thickness of less than about 0.17 millimeters is contemplated. Likewise a trocar body 104-2 having a wall thickness of less than about 0.16 millimeters is contemplated. Likewise a trocar body 104-2 having a wall thickness of less than about 0.15 millimeters is contemplated. Likewise a trocar body 104- 2 having a wall thickness of less than about 0.14 millimeters is contemplated. Likewise a trocar body 104-2 having a wall thickness of less than about 0.13 millimeters is contemplated. Likewise a trocar body 104-2 having a wall thickness of less than about 0.130 millimeters is contemplated. Likewise a trocar body 104-2 having a wall thickness of about 0.127 millimeters contemplated.

[0039] Needles according to the present specification can, a) reduce beam hardening artifacts under image guidance; b) reduce tissue damage; c) provide as a passage of interior Dimension B as to control pressurized introduction of bone cement into the target area without overflow;d) during such introduction, provide a Dimension C (ie. Thickness of wall 120 of body 104-2) to withstand the pressure of injection (e.g. bone cement) or withdrawal (e.g. tissues, such as tissues for biopsy) without rupture or material deformation, e)allows identification of acquisition of biopsy tissue in the needle while its in the patient on CT image guidance; amongst providing other advantages.

[0040] Furthermore, it has been noted that the reduction of wall thickness (Dimension C) over the prior art can lead to a pressure drops to the inverse of the improvement in diameter to the 4thpower.

[0042] Thus, the inventors believe that a 10% increase in interior diameter of the trocar body 104-2 can result in about 30% decrease in pressure. To contrast, a prior art 11 g needle has about 0.305 mm wall thickness, so with a 2.946 mm outer diameter, the interior diameter of the prior art 11g needle is 2.337 mm. By contrast, according to the present specification, about a 0.127 mm wall for an 11 gauge needle to the present specification that would go to about 2.692 mm. Doing the math, 2.692 / 2.337=1.152 or about a 15% increase in interior diameter. Such a 15% increase in diameter can mean about a 40% decrease in pressure. Such a decrease in pressure can thus reduce the amount of time to perform the procedure (e.g. injection or extraction) as a greater volume of material can be passed through trocar body 104-2 as compared to the prior art. The reduced amount of time thereby reduces exposure of harmful ionizing radiation from the imaging equipment and the amount of time that a patient experiences potential trauma from the surgery. It will allow for lower pressure injection systems to be used decreasing the risk of cement extravasation into veins or the spinal canal or lung embolus.

[0043] While the foregoing highlights the decrease in pressure, it is to be understood that further unexpected advantages can accrue. Figure 6 shows an image of the screen of a Toshiba Aquillon Computed Tomography (CT) machine whereby a prior art trocar 600 is shown (left side) beside a trocar 100-2 (right side) according to the present specification. The image in Figure 6 is not a simulation but indeed shows that prior art trocar 600 generates far more beam hardening artifacts than trocar 100-2. Indeed, the hollow channel of trocar body 104-2 is visible allowing even for potential visualization of material (e.g bone cement injection, or tissue extraction) within that hollow channel. io

[0044] It is noted that prior art trocar 600 has been used in hundreds of thousands procedures since about the year 2000. While quantitative data is unavailable, it is the understanding of Inventor Murphy, a leading interventional neuroradiologist who holds several patents in the area of Vertebroplasty (see for example, US6273916B1 ) that prior art trocar 600 has been successfully used in many procedures in which it is deployed and thus any deficiencies (beam hardening artifacts, over filling of the vertebral cavity) therein have been accepted as tolerable. Thus needle 100 of the present specification is novel and non-obvious as it provides unexpected advantages over the prior art.

[0045] The scope of the monopoly of this specification is defined by the claims, properly construed in relation to the narrative and drawings. Any limiting phrases should not be viewed in isolation but in view of the broader context of the entire teachings and advantages afforded by the specification.

Claims

Claims1 . A surgical needle comprising: a trocar having a trocar-tip; a stylet having a stylet-tip and removably receivable within the trocar; the trocar-tip and the stylet-tip forming a contiguous piercing surface when stylet is received within the trocar; and, the trocar having a wall thickness of less than about 0.229 millimeters.

2. The needle of claim 1 wherein the wall thickness is less than about 0.22 millimeters.

3. The needle of claim 1 wherein the wall thickness is less than about 0.2 millimeters.

4. The needle of claim 1 wherein the wall thickness is less than about 0.15 millimeters.

5. The needle of claim 1 wherein the wall thickness is less than about 0.13 millimeters.

6. The needle of claim 1 wherein the wall thickness is less than about 0.130 millimeters.

7. The needle of claim 1 wherein the wall thickness is about 0.127 millimeters.

8. The needle of claim 1 wherein the trocar is about an 8 gauge and the stylet is about a 9 gauge.

9. The needle of claim 1 wherein the trocar is about a 9 gauge and the stylet is about a 10 gauge.10.The needle of claim 1 wherein the trocar is about a 10 gauge and the stylet is about an 11 gauge.1 1 .The needle of claim 1 wherein the trocar is about an 11 gauge and the stylet is about a 12 gauge.

12. The needle of claim 1 wherein the trocar is about a 12 gauge and the stylet is about a 13 gauge.

13. The needle of claim 1 wherein the trocar is about a 13 gauge and the stylet is about a 14 gauge.

14. The needle of claim 1 wherein the trocar is about a 14 gauge and the stylet is about a 15 gauge.

15. The needle of claim 1 wherein the trocar is about a 14 gauge and the stylet is about a15 gauge.

16. The needle of claim 1 wherein the trocar is about a 15 gauge and the stylet is about a16 gauge.

17. The needle of claim 1 wherein the trocar is about a 16 gauge and the stylet is about a17 gauge.

18. The needle of claim 1 wherein the trocar is about a 17 gauge and the stylet is about an 18 gauge.

19. The needle of claim 1 wherein the trocar is about an 18 gauge and the stylet is about a 19 gauge.

20. The needle of claim 1 wherein the trocar is between about 8 gauge and about 22 gauge and the stylet is about one gauge greater than the trocar.

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