Abstract:
An improved Luer-lock fitting for hypodermic needles and methods for using the fitting to inject suspended solids into a body. The improved fitting includes a lumen having a curvedly tapered, distally decreasing throat region, which is believed to provide improved flow of suspended solids into the hypodermic needles. One fitting includes at least two threads to provide a more secure fitting able to withstand higher injection pressures. Another fitting includes rounded wings better able to withstand jarring by endoscope eyepieces and resisting being dislodged from position. One method includes injecting suspended solids into soft tissue such as sphincter mechanisms. One method includes injecting suspended solids into tissue surrounding a mechanism to correct defects.

Description:
FIELD OF THE INVENTION 
     The present application is related to devices and methods for injecting suspended solids into a body. Specifically, the present invention is related to a hypodermic needle assembly and hub having a curvedly tapered lumen and higher pressure Luer-lock fittings for joining syringes to hypodermic needles, and methods for using same. 
     BACKGROUND OF THE INVENTION 
     Hypodermic needles are commonly used to inject fluids into a body. It will be understood that injection of fluids occurs both with respect to human bodies and animal bodies. While the present invention, in its preferred embodiment, is intended for use in injecting fluids into a human body, veterinary applications are specifically contemplated. The needles have a sharpened distal end and often have a hub fitting on the proximal end for mating to a syringe. The fitting is often a Luer fitting, which describes generally the male-female shapes of the syringe and needle hub, respectively. When the Luer fitting includes means such as threads for locking the male and female parts together, the fitting is known as a Luer-lock tip. The Luer-lock fitting is a standard fitting in the medical field, often having a single thread having nominally three turns about the longitudinal axis of the syringe. The Luer-lock fitting is well suited for administering agents such as drugs through common hypodermic needle lengths. 
     A composition and method for treating urinary incontinence is described in related U.S. patent application Ser. No. 08/676,592, filed Jul. 8, 1996, entitled IMPROVED TISSUE INJECTABLE COMPOSITION AND METHOD OF USE, herein incorporated by reference. The composition includes solid particles having an average size of between about 100 and 1,000 microns, preferably between 200 and 500 microns. The particles can be carried in a suspension such as a fluid or gel. 
     Standard Luer-lock fittings have been used to inject the particles into a body through the employment of endoscopes, but with less than optimal results due in part to problems related to the particular application. One problem is the long needle lengths required for the application. Needle lengths are dictated both by anatomy and by the length of endoscopes used in the procedures. Needles used in injecting solids into the urinary sphincter muscles are nominally 16 inches long. Needles used in injecting solids into esophageal sphincter can be about 60 inches long. The longer internal paths have a higher resistance to flow than the shorter paths typically found in hypodermic needles. 
     Another problem is related to the nature of the injected composition. The injectable material includes solid particles suspended in a carrier, such as a gel. A typical Luer-lock fitting includes a lumen having a large inside diameter proximal end and a smaller inside diameter distal end. The transition from large inside diameter to small inside diameter can be a step change or a straight taper, as the shapes are easy to mold and manufacture. These transition taper shapes work well with typical liquids, but work less than optimally with large particles suspended in a liquid carrier. In particular, the particles can be swept along a straight taper region to a location immediately proximal of the small inside diameter portion, and become bunched up at this point. The particles massed at one point can prevent the further passage of any particles. What would be desirable is a Luer-lock fitting better able to lessen the blockage by the large particles. 
     Still another problem with conventional Luer-lock fittings is the use of a single thread. Attempting to force large, possibly bunched, suspended particles suspended in a viscous carrier through long hypodermic needles can require high pressure. In practice, this can require a great deal of hand pressure on the plunger of a syringe. In practice, this high pressure can result in fluid leakage at the Luer-lock fitting. The loss of the fluid can be a significant problem, as it serves as the carrier for the particles. With loss of the carrier in the Luer-lock fitting, the particles become more concentrated, and less likely for flow through the fitting and into the hypodermic needle lumen. What would be desirable is a fitting better able to withstand the high pressures required to inject suspended solids through hypodermic needles. 
     SUMMARY OF THE INVENTION 
     The present invention includes a hypodermic needle having an improved Luer-lock fitting for injection of suspended solids through the needle. The present invention includes methods for using the improved fitting to inject solid particles suspended in a viscous carrier through long hypotube sections and into soft tissue to treat deficiencies. Applicants believe the present invention reduces the blockage of Luer fittings by large, suspended solid particles. Applicants also believe the present invention provides a fitting better able to withstand the higher pressures applied when injecting viscous suspensions through long hypotube sections. 
     One improved fitting according to the present invention includes a substantially cylindrical or tubular hub body affixed to the proximal end of a hypodermic needle. The hub body has a proximal end for receiving fluid, a distal end for ejecting fluid, a lumen therethrough, and a hub body wall having a threaded region. The body includes a region having a curvedly tapered inside diameter, decreasing the inside diameter with increasing distal position. The curved taper region is preferably disposed distally of a standard, straight, Luer tapered region. The curved taper is believed to reduce the likelihood of blockage from particles bunching up near the taper distal end. Blockages have been observed in Luer fittings having straight tapers. Such blockages can preclude further particle flow and can cause large back pressures. Applicants believe even small blockages can preferentially allow flow of a suspension fluid over flow of suspended particles, concentrating the particles in less fluid until the blockage becomes more pronounced. 
     A preferred embodiment has more than a single thread, providing a tighter, pressure resistant seal between syringe and Luer-lock fitting. One fitting has two start threads 180 degrees opposed, each wrapping around the fitting for about 1 and ½ turns. One fitting hub has two opposed wings extending outward from the longitudinal axis of the hub. The wings provide a structure for tightly grasping and turning the hub relative to the syringe. Preferred wings have a rounded periphery. The rounded wings can deflect objects striking the wings, lessening the force which can act to dislodge a positioned hypodermic needle. In particular, the rounded wings can deflect an endoscope eyepiece knocking against the hub. 
     In use, a long hypodermic needle having a Luer-lock hub according to the present invention is provided. A suspension of solids in a liquid carrier is provided in a syringe adapted to mate to the Luer-lock fitting. The syringe is secured to the Luer-lock fitting at a point in time as dictated by the user. In one method, the syringe is secured before advancing the needle into the patient. In another method, the syringe is secured only after the needle tip has been advanced close to the target site. The needle is preferably advanced through an endoscope such that the sharp needle tip is visualized as the tip is advanced. 
     The sharp needle tip can be advanced until the target site is penetrated, and the syringe plunger depressed until a sufficient amount of solid suspension has been injected into the target. The needle can be retracted and advanced to different target sites until the area has been treated. A preferred use of the present invention is the augmentation of urinary, anal and gastric sphincter mechanisms with injected solid particles. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a system for injecting suspended solids, including a syringe and hypodermic needle with hub having a Luer-lock fitting and rounded wings; 
     FIG. 2 is a top view of a the hypodermic needle and hub of FIG. 1; and 
     FIG. 3 is a longitudinal cross-sectional view of the Luer-lock hub fitting of FIG. 1 (with wings not shown), illustrating the curvedly tapered lumen region. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a system  20  for injecting suspended solids including a syringe  22  and a hypodermic needle assembly  24 . Syringe  20  includes a generally cylindrical body  28  having a distal portion  30  and a threaded region  32 . Disposed within syringe body  28  is a plunger  26  having a distal portion  40  and rubber seals  38 . Syringe  22  has a tapered, protruding male member  34  having a lumen  36  therethrough. Member  34 , in a preferred embodiment, has a standard Luer taper. 
     Hypodermic assembly  24  includes a proximal hub  42  and a needle  44 . Needle  44  is commonly formed of hypotube and is illustrated having a protective sheath  46  disposed over needle  44 . Hub  42  includes a threaded cylindrical region  50  having a lumen  48  therethrough. Lumen  48  substantially defines the longitudinal axis of hypodermic needle assembly  24 . Threaded cylindrical region  50  includes an inner wall surface  52 , preferably having a standard Luer taper adapted to mate with syringe member  34 . In hub threaded region  50 , a preferred embodiment has more than one start thread, to provide additional sealing force over the length of threaded regions  50  and  32  when tightened. In the embodiment of FIG. 1, hub threaded region  50  has two start threads, with one start indicated at  54  and the other disposed 180 degrees opposite. In this embodiment, each of the two threads wraps 1 and ½ turns about the hub. Some previous devices have utilized only a single thread which has sometimes proven less than optimal in retaining the suspension carrier fluid within the Luer-lock fitting under pressure. Other previous hub devices have utilized only protruding, stub-like ears in place of threads. These devices have sometimes proven unable to provide sufficient strength when a user attempted to provide a tight seal between syringe and hub. Hub  42  includes two wings  54 , each having a thinner, internal portion  56 , and a thicker, rounded, peripheral rib portion  58 . 
     Referring now to FIG. 2, hypodermic needle assembly  24  is further illustrated in greater detail. In a preferred embodiment, hub lumen  48  includes a Luer taper region  62  and a curvedly tapered region  60 . Curvedly tapered region  60  is indicated by phantom lines in FIG. 2, illustrating the lumen through hub  42 , which continues through needle  44 . Needle  44  terminates in a distal skived portion  64 . In a preferred embodiment, wings  54  are consistently oriented relative to skived portion  64 . In one embodiment, wings  54  are oriented such that the widest portions of skived portion  64 , as indicated at  65 , are oriented outward in the same direction as wings  54 . This orientation of skived portion  64  provides a predictable configuration that is consistent with the insertion of the needle tip through an endoscope while lessening the chance of wings  54  being dislodged by the endoscope eyepiece. 
     A preferred embodiment hub has wings to aid in securing a tight, pressure resistant fitting for the Luer-lock fitting. At least some prior art devices for injecting suspended solids have lacked wings. These device hubs have proven difficult to grasp tightly and held with latex gloved hands. The prior device drawbacks have sometimes lead users to affix clamps to the hypodermic hub in order to rotate the hub and syringe sufficiently tightly so as to form a tight seal. Wings  54  have a rounded periphery in a preferred embodiment, as illustrated in FIG.  2 . The rounded periphery provides a rounded surface such that if another device, such as an endoscope eye-piece, collides with the wings, the other device can glance off the wings rather than connect squarely and risk dislodging a previously positioned needle tip. 
     Referring now to FIG. 3, Luer taper  62  and curved taper  60  are illustrated in detail. In one embodiment, Luer taper  62  is a straight, ANSI taper, tapering from 0.170 inch inside diameter to 0.155 inch inside diameter over a length of 0.250 inch. In one embodiment, curved taper  60  extends from a proximal bend point  70  to a distal bend point  72 , having curved portion  60  therebetween. The curvedly tapered region in one embodiment is substantially non-linearly distally decreasing. In one embodiment, curved portion  60  has a shape described by a parabola. In another embodiment, curved portion  60  has a shape described by a logarithmic function. In a preferred embodiment, the surface of curve  60  changes less per unit distance with increasing distal position, having a steeper slope near proximal bend point  70 . Applicants believe curved taper  60  provides an orderly transition for the suspended beads or particles being forced into the hypodermic needle. Applicants believe the curved transition region substantially lessens the occurrence of particles jamming together and blocking or substantially increasing the back pressure in lumen  48 . Applicants have experienced blockage when attempting to inject a solid suspension through a fitting having a straight taper rather than a curved taper. The particles were observed to bunch together near the taper distal end, preventing further passage of particles and creating large back-pressure in the lumen, in response to continued applied syringe plunger pressure. 
     In use, the user can select an appropriate needle length to use and an appropriate solid suspension. After inserting and positioning an endoscope, the targeted site can be visualized and identified. A preferred use of the present invention is augmenting soft tissue with injected solid particles. While a preferred method utilizes an endoscope, other visualization methods such as fluoroscopy are also within the scope of the invention. Syringe  22  can be filled with an appropriate amount of solid suspension. Hypodermic needle assembly  24  can be filled with the solid suspension or other inert fluid and inserted into the endoscope. In a preferred method, hub wings  54  are properly oriented so as to properly orient needle skived portion  64  so as to optimally pierce the targeted site, such as a sphincter mechanism. 
     Syringe  22  can be secured to hypodermic needle assembly  24  by inserting syringe  22  into hub lumen  48  and rotating syringe  22  relative to hub  42  while holding hub wings  54  firmly. In one method, syringe and hub are secured together after the needle has been inserted into the endoscope. In another method, syringe and hub are secured together prior to inserting the hypodermic needle into the endoscope. Using the endoscope, needle distal skived portion  64  can be incrementally moved into position and into the targeted site in a sphincter mechanism. The rounded hub wings of the preferred embodiment should provide resistance to the needle being dislodged, should the wings be jarred during advancement through the endoscope, such as during an inadvertent collision with the endoscope eyepiece. 
     Once in place, suspended solids can be injected into the target site. The wings and multiple threads of the preferred embodiment provide structure to enable the formation of a tight, pressure resistant seal between syringe and needle hub. The curved taper of the present invention provides resistance to blockage which can be caused by the accumulation of the particles to be injected. The needle can be repeatedly retracted and advanced into multiple tissue sites proximate a location until treatment is complete. The needle and endoscope can then be withdrawn. 
     Numerous characteristics and advantages of the invention covered by this document have been set forth in the foregoing description. It will be understood, however, that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of parts without exceeding the scope of the invention. The inventions&#39;s scope is, of course, defined in the language in which the appended claims are expressed.