Patent Publication Number: US-2011060311-A1

Title: Implantable reel for coiling an implantable member

Description:
FIELD 
     The present invention is related to medical implants, and more particularly, to implants comprising a material that may be coiled. 
     BACKGROUND 
     A variety of medical implants include a length of elongated material, such as tubing or wiring. For example, implanted pumps may include a length of tubing extending between the pump location and the desired delivery point, wherein the tubing serves to convey a prescribed dosage of medicine, such as pain killer, to a portion of the patient&#39;s body. As another example, electrical stimulation sources or pulse generators are used in combination with electrodes to provide electrical stimulation of nerves for the treatment of pain. As further background to existing treatment systems, reference is made to U.S. Patent Application Publication No. 2005/0010259 that discloses electrical stimulation and drug therapy systems, and the content of the aforementioned application is incorporated herein by reference in its entirety. 
     In general, because of its size, a pulse generator is typically separated from the electrodes that actually deliver the electrical stimulation to the target area, where the target may be the spinal cord or its peripherhal nerves, or other body locations, such as the head or legs. More particularly, a length of wiring or lead is implanted and extends between the pulse generator and the electrodes placed at the target location, wherein the electrodes are interconnected to the lead using a coupling, or alternatively, the electrodes may be integrally formed at the end of the lead itself. 
     Leads typically are supplied by a medical device manufacturer, and therefore, are available pre-made and can include wiring for an electrode array. More particularly, leads typically contain a plurality of conductors leading to a coupling or corresponding number of electrodes that may be separated at the distal end of the lead. Such configuration allows electrical stimulation to be provided over an area rather than at one specific point. Referring to  FIG. 1 , a neurostimulator  102  is shown that includes a lead  106  and a pulse generator  110 . The lead  106  has a distal end  114  that typically comprises a plurality of electrodes  118 . The proximal end  122  of the lead  106  typically is adapted for mating with the pulse generator  110 . Because the structure of the lead  106  has a plurality of conductors leading to a plurality of electrodes  118 , a surgeon typically does not modify the length of the lead  106  because of the difficulty that would be associated with trying to splice the different conductors together. Accordingly, the surgeon typically uses the lead  106  as it is manufactured, and does not modify its length. 
     During the course of a surgical procedure to implant a neurostimulator  102 , the surgeon will implant the pulse generator  110  in an appropriate body location, such as the upper chest, buttock or abdomen of the patient. The surgeon will also implant a lead  106  and electrode  118  and connect the lead  106  to the pulse generator  110 . The surgeon chooses the length of the lead  106  based upon the patient&#39;s size and perhaps other factors, such as patient growth, but must choose a lead length that is at least long as the distance between the pulse generator  110  and the electrode target location. The excess length of the lead  106  is then typically inserted or tucked into the patient&#39;s body at one of the incision locations. As discussed further below, it is this last step that poses several problems. 
     One issue associated with the excess length of the lead is that, since the surgeon must essentially push the excess length into the incision, the wiring of the lead can sometimes become kinked and damaged, thereby requiring replacement. In addition, the excess length can create an unsightly appearance under the patient&#39;s skin, and may some times bulge. This can detrimentally impact patient satisfaction and can also negatively influence cooperation with the treating physician. Also, if the surgeon must replace or augment one or more components of a previously implanted system, the wiring must be dissected from tissue that has grown around its length. Accordingly, if the wiring is looped and/or otherwise awkwardly positioned, then subsequent removal of the wiring can be more difficult than a neatly situated lead. Therefore, it would be advantageous to provide a device and method for use that allows a surgeon to utilize pre-manufactured leads and organize excess length of such leads within a surgical site. 
     SUMMARY 
     The present invention addresses the shortcomings of the prior art by providing a device for spooling the excess wiring associated with a lead that extends between the electrodes and pulse generator of an electrical stimulation implant system. The present invention also has application to providing a spool for implanted tubing that is associated with, for example, an implantable drug delivery system. The present invention has application to systems that are implantable within humans, and also has application to veterinary medicine, wherein the devices and methods described herein may be used in association with treating, for example, animals, such as horses. 
     It is to be understood that the present invention includes a variety of different versions or embodiments, and this Summary is not meant to be limiting or all inclusive. 
     This Summary provides some general descriptions of some of the embodiments, but may also include some more specific descriptions of certain embodiments. 
     As a general example, one embodiment is an implantable system that includes: (a) a source unit (such as a pulse generator for an electrical stimulation system, and/or a drug reservoir and/or fluid pump for a drug treatment system); (b) an elongated member operatively associated with the source unit (where, for example, the elongated member may be an electrical lead and/or tubing to convey a drug); and (c) a spool for receiving at least one winding of the elongated member. 
     It is an aspect of the present invention to provide an implantable spool for use in an implantable medical treatment system. The system has a treatment source unit and a flexible elongated member connected to the treatment source unit. The implantable spool may be spaced apart from the treatment source unit and a distal end of the flexible elongated member. The implantable spool preferably includes a core around which at least a portion of the flexible elongated member may be wound. In accordance with embodiments of the present invention, the treatment source unit may comprise a drug pump and/or a pulse generator. In accordance with embodiments of the present invention, the elongated flexible member may comprise a tubing and/or an electrical wiring lead. In accordance with embodiments of the present invention, the spool may further comprise a pair of flanges connected to the core. In accordance with embodiments of the present invention, the spool may comprise a cap covering at least a portion of a winding channel located between the pair of flanges. In accordance with embodiments of the present invention, at least a first flange of the pair of flanges may comprise a groove for receiving at least a portion of the elongated member. In accordance with at least some embodiments of the present invention, the groove is located on a tab attached to the first flange. In accordance with at least some embodiments of the present invention, the tab comprises a pair of opposing fingers oriented transverse to an outer lateral surface of the first flange. In accordance with embodiments of the present invention, one or more of the flanges may comprise an aperture adapted for receiving a suture. 
     As noted above, the present invention has application to both drug delivery systems and electrical stimulation systems. Thus it is an aspect of the present invention to provide an electrical stimulation system for providing electrical stimulation to an internal tissue of a patient. The system includes: an implantable pulse generator; an implantable lead operatively associated with the pulse generator; and an implantable spool adapted for receiving at least a first winding of the lead. 
     It is a further aspect of the invention to provide a system that allows for a variety of structures to fulfill certain functions. Thus, an implantable system for providing treatment to an internal tissue of a patient is provided. The system includes: a source unit, such as a drug pump or a pulse generator; an elongated member, such as electrical wiring or tubing; and a device for receiving at least a first winding of the elongated member. 
     It is also an aspect of the present invention to provide a spool that can be used in combination with other treatment components, including pre-existing components. Thus, in subcombination, an implantable spool is provided for use in an implantable system where an elongated member is to be implanted. 
     It is also an aspect of the present invention to provide a method of using a spool for winding at least a portion of an elongated member. Thus, in accordance with embodiments of the present invention, a method of installing a neurostimulation system in a patient is provided. The method includes: 
     (a) making an incision in a first tissue of the patient, the incision for placement of a pulse generator; 
     (b) making an incision in a second tissue of the patient, the incision for placement of at least one electrode; 
     (c) winding at least a portion of a lead around an inner core of a spool, the lead interconnecting the electrode(s) to the pulse generator; and 
     (d) implanting the spool within the patient. 
     In addition, the method may further comprise inserting a portion of the lead into a groove, covering at least a portion of a winding channel of the spool with a cap, and/or suturing the spool to tissue of the patient. The method is also applicable to implanting a drug treatment system. 
     A method of assembling an implantable system is also provided. The method of assembling includes providing an implantable source unit, an implantable elongated member, and an implantable spool for receiving at least a first winding of the elongated member. 
     Various embodiments of the present invention are set forth in the attached figures and in the detailed description of the invention as provided herein and as embodied by the claims. It should be understood, however, that this Summary does not contain all of the aspects and embodiments of the present invention, is not meant to be limiting or restrictive in any manner, and that the invention as disclosed herein is and will be understood by those of ordinary skill in the art to encompass obvious improvements and modifications thereto. 
     Additional advantages of the present invention will become readily apparent from the following discussion, particularly when taken together with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view of an electrical stimulation system known in the prior art; 
         FIG. 2  is a side elevation view of an electrical stimulation system in accordance with embodiments of the present invention; 
         FIG. 3  is a side elevation view of the spool in accordance with at least one embodiment of the present invention; 
         FIG. 4  is a front elevation view of the spool shown in  FIG. 3 ; 
         FIG. 5  is a cross-sectional view of a spool in accordance with embodiments of the present invention; 
         FIG. 6  is a side elevation view of the spool shown in  FIG. 5 ; 
         FIG. 7  is a front elevation view of a spool in accordance with embodiments of the present invention; 
         FIG. 8  is a detail view of a portion of the spool shown in  FIG. 7 ; 
         FIG. 9  is a front elevation view of a spool in accordance with embodiments of the present invention; 
         FIG. 10  is a side elevation view of the spool shown in  FIG. 9 ; and 
         FIG. 11  is a front elevation view of a patient with a system comprising the present invention implanted into the patient. 
     
    
    
     The drawings are not necessarily to scale. 
     DETAILED DESCRIPTION 
     In accordance with embodiments of the present invention, a device is provided for organizing an implantable elongated member within a patient, wherein the elongated member may be tubing associated with a drug delivery system, or may be wiring associated with an electrical stimulation system. In general, embodiments of the present invention comprise a spool or reel used to organize the excess length of the elongated material. 
     Referring now to  FIG. 2 , and in accordance with embodiments of the present invention, an electrical stimulation system  200  is shown. The electrical stimulation system  200  comprises a pulse generator  110 , a lead  106 , electrodes  118 , and reel or spool  204 . Although the spool  204  may have any shape, it is preferably round or oval, and includes an inner core  208  around which the excess lead  106  is wrapped. 
     Referring now to  FIGS. 3 and 4 , side and front elevation views of spool  204  are shown, respectively. In accordance with embodiments of the present invention, the spool  204  comprises first and second flanges  216  for forming a winding channel  218 , thereby laterally confining the excess wiring wound within the spool  204 . As noted above, the spool  204  also includes an inner core  208 . The inner core is preferably sized for maintaining an acceptable radius of curvature for the lead  106 , such that the lead  106  cannot be detrimentally kinked when being wrapped within the spool  204  during surgery. 
     In accordance with embodiments of the present invention, although the spool  204  may be a variety of sizes, the spool  204  preferably comprises a diameter D between about 0.75 to 1.75 inches, and more preferably, a diameter D between about 1.0 to 1.5 inches. In addition, although its thickness may also be a variety of sizes, the spool  204  preferably comprises a thickness T of about 0.25 to 0.5 inches. The size of the spool  204  chosen by the surgeon will depend in part upon the amount of excess wiring to be wound around the spool  204 , the size of the patient, the implantation location within the patient, and the nature of the wiring used as the lead  106 . 
     The spool  204  and its inner core  208  are preferably sized for allowing space between the outer surface  220  of the inner core  208  and the circumferential edge  224  of the flange  216  so that the lead  106  may be wrapped around the inner core  208  without extending substantially beyond circumferential edge  224  of the flange  216 . Of course, the spool  208  may be made and provided in a variety of sizes, thereby allowing for a greater number of windings of the lead  106  within the spool  204 . 
     Referring now to  FIG. 5 , a cross-sectional view of spool  204  is shown, in which an optional flap, covering or cap  500  is provided. The cap  500  covers at least a portion of the circumferential edge  224  of the spool  204  after the excess lead  106  is wound around the inner core  208 . The cap  500  prevents tissue from growing into the area between flanges  216  after the spool  204  and lead  106  have been implanted. The cap  500  may enclose nearly the entire circumferential edge  224  of the spool  204 , or it may cover only a portion of it. As shown in  FIG. 6 , a first cap portion  500   a  may be used in combination with a second cap portion  500   b,  wherein the use of a plurality of caps  500  allows the lead  106  to enter and exit the spool  204  at gaps between the cap portions  500   a  and  500   b.  Of course, a number of different types of coverings for the winding channel  218  are possible, and such variations are within the scope of the present invention. 
     The cap  500  may use a variety of ways for interconnecting to the spool  204 , such as a living hinge on one its lateral edges  504  with an flange  216  of the spool  204 , or it may form a friction fit at one or more of its lateral edges  504  with the outer surface  222  of the flanges  216  of the spool  204 . In use, a surgeon would wind the excess lead  106  around the inner core  208  of the spool  204 , and then apply the optional cap  500  at a location that does not interfere with the entry and exit of the lead  106  to the spool  204 . The cap  500  may further comprise one or more openings or slits  508  sized to guide or hold the lead  106 . 
     Referring now to  FIGS. 7 and 8 , and in accordance with embodiments of the present invention, a spool  204  is shown that comprises an optional guide or groove  700  that is operatively associated with a portion of the spool  204  or its features, such as one of the flanges  216 . The groove  700  serves as a receptacle for receiving a portion of the lead  106  and holding the lead in place. Thus, the natural tendency of the wound lead  106  to radially expand after winding around the inner core  208  can be resisted by use of one or more grooves  700  to hold the lead  106 . Referring now to  FIG. 8 , an embodiment of a groove  700  is illustrated, wherein the groove  700  is formed on an inward facing tab  702  by two opposing fingers  704  and  708 . In accordance with embodiments of the present invention, the fingers  704  and  708  may be oriented transverse to an outer surface  222  of an flange  216  of the spool  204 . In addition, a separation distance between the fingers  704  and  708  may vary to provide a smaller opening diameter d o  than an inner groove diameter d i . One or more of the fingers  704  and  708  may be biased and/or flexible. Accordingly, the groove holds or receives the lead  106 , and other available structures used alone or in combination include a slit in one or more of the flanges  216 , and other structures, such as a clasp, a clip, an elastic member or band, etc. 
     Referring now to  FIGS. 9 and 10 , and in accordance with embodiments of the present invention, a spool  204  is shown that includes an optional suture aperture  900  for suturing the spool  204  to surrounding tissue at a desired implantation site. Accordingly, the suture aperture  900  provides a way to secure the spool  204  to a tissue of the patient. 
     In addition, alternative ways of securing the spool  204  to tissue may comprise other possible structures, including a tab for receiving a staple, or a clip for tissue engagement, etc. The suture aperture  900  may be located at a variety of locations, such as through an flange  216 , or on a tab operatively associated with the spool  204 . 
     In accordance with embodiments of the present invention, the spool  204  may comprise a biasing member (not shown), wherein the spool  204  automatically releases and/or retracts a portion of the lead  106 . 
     If desired, combinations of the features described herein may be used, such as use of a cap  500  in combination with a groove  700 , or a groove  700  used in combination with a suture aperture  900 . 
     Referring now to  FIG. 11 , embodiments of the present invention include a method of using the spool  204 . Accordingly, in use, a surgeon first provides an incision for receiving at least the spool  204 . The surgeon also winds at least a portion of the lead  106  within the spool  204  and implants the spool  204  and lead  106  within a patient P. The spool  204  is sized for being appropriate for implanting spaced apart from at least one of the pulse generator  110  and the electrodes  118 , or within the vicinity of at least one of the pulse generator  110  and the electrodes  118 . In accordance with embodiments of the present invention, the spool  204  may be positioned such that either the lead.  106  extends in a substantially straight line between the pulse generator  110  and the location of the implanted electrodes  118 , or it is alternatively positioned to accommodate the anatomy of the patient P, such as at a third location where the lead typically forms a bend between the pulse generator  110  and the location where the electrodes  118  are implanted. Optional steps associated with the method of use include inserting the lead  106  into a groove  700  that is associated with the spool  204 , placing a cap  500  over at least a portion of the winding channel  218 , and/or suturing the spool  204  to tissue at the spool implant location. Additional optional steps include closing the incision, causing a second incision to be made at a later time, and unwinding or winding at least a portion of the lead  106  from the spool  204 . Embodiments of the present invention further include a method of assembling an implantable system, the method comprising: providing a source unit, such as a pulse generator or drug reservoir; providing an elongated member such as an electrical lead or tubing; and providing a spool for receiving a least a first winding of the elongated member. Additional steps of the method of assembling may include providing the spool with added features, such as: a cover; a groove; and a structure associated with allowing the spool to be attached to tissue of a body. 
     At least portions of the spool  204  and/or its associated features may be made from one or more materials that possesses the appropriate strength characteristics necessary to withstand conditions from the body and associated implants when used in medical applications. In addition, the materials may be chosen to provide desired flexibility characteristics. In accordance with embodiments of the present invention, examples of materials that may be used to make at least portions of the spool  204  include, but are not necessarily limited to, silicone, polyether ether plastics, such as ketone (PEEK), polyether ketone ketone (PEKK), ultra high molecular weight polyethylene (UHMWPE), and polymethylmethacrylate (PMMA); metals, such as titanium and stainless steel; composites; as well as other tissue compatible materials. 
     While particular embodiments of the present invention have been described in some detail, it should be understood that other related embodiments are intended to be within the scope of the present invention. For example, other ways to functionally and structurally provide an implantable spooling device in combination with an elongated member, such as tubing or electrical wiring, are encompassed by the present invention, whether such structures employ flanges and/or an inner core, and/or whether such structures are integrally made or form a connectable part of the elongated member itself or another implantable member, and/or whether such structures include other features that are well within the knowledge of those of ordinary skill in this art, and/or whether such structures are conventional structures or those that may be developed in the future. In particular, however, other implantable reels or spool mechanisms, including those that may comprise a biasing member or auto-wind/rewind capability are considered within the scope of the invention. Furthermore, such devices may include adaptations of pumps or pulse generator units, and/or couplings, and/or tubing, and/or electrical leads, and/or exit orifices, and/or electrode arrays. 
     The foregoing discussion of the invention has been presented for purposes of illustration and description. The foregoing is not intended to limit the invention to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the invention are grouped together in one or more embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate preferred embodiment of the invention. 
     While various embodiments of the present invention have been described in detail, it is apparent that modifications and adaptations of those embodiments will occur to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the present invention, as set forth in the following claims.