Patent Publication Number: US-2018035871-A1

Title: Laparoscopic instrument with recessed seal

Description:
BACKGROUND 
     1. Field of the Invention 
     This invention relates to an instrument including a surgical apparatus, such as a laparoscopic tube end used for performing laparoscopic, pelvoscopic, arthroscopic, thoroscopic and/or similar such procedures, and more particularly to an electrosurgical apparatus having a handpiece for fluidically sealing, isolating and electrically insulating a detachable tip when engaged with a laparoscopic tube end. 
     2. Background of the Invention 
     Medical procedures such as laparoscopy and the like, which employ a tip at the end of a tube for insertion into the patient, are beneficial because the incisions necessary to perform them are minimal in size, therefore promoting more rapid recovery and lower costs. For example, a patient who undergoes laparoscopic surgery may typically return to normal activity within a period of a few days to about a week, in contrast to more invasive procedures requiring a relatively larger incision (which may require about a month for recovery). Although the term “laparoscopic” is typically used hereinafter, such use of the term “laparoscopic” should be understood to encompass any such similar or related procedures such as, for example, arthroscopic, endoscopic, pelvoscopic and/or thoroscopic or the like, in which relatively small incisions are used. 
     However, when a tip is detachably connected to the tube end of a laparoscopic device, complications may occur if fluid breaches the connection and enters the interior of the tip or tube end. For example, septic contamination may arise in the laparoscopic device and/or electrical current may unintentionally leak therefrom. After each laparoscopic procedure, the device is also exposed to brushing, chemicals for cleaning and/or sterilization by various methods which may include heating, cooling, and flushing with additional chemicals. The seal in the handpiece may degrade to the point where it loses its integrity (either over use of hundreds of cycles, or from handpiece abuse; which can result in unintended cautery causing damage and injury to tissue around a surgical site). 
       FIGS. 1-2  shows a tube end assembly  11  of a reusable handpiece  23  to which a conventional tip (which may be a single-use device, or “SUD”)  20  may be removably attached, thereby providing an instrument  10 . The tip  20  has an end effector  22  in the form of a scissors, grasper and the like. The tube end assembly  11  distally extends from a tube  61 , which in turn distally extends from the handpiece having handles (or other suitable controls, not shown, for actuating the tip  20 ) operable by the medical personnel or physician performing the surgery. The tube end assembly  11  includes an elastomeric tube end seal  15 , which is typically made from EPDM (ethylene propylene diene monomer) and is in the form of an O-ring. 
     The seal  15  provides an electrically-safe seal between the interface of the tube end assembly  11  and the tip  20 . The main purpose of the seal  15  is to prevent fluids from wicking or seeping into the seam between the two parts of the device (i.e., the point of attachment of the tube end assembly  11  and the tip  20 ). The seal  15  is typically attached to the tube end assembly  11  via epoxy onto the tube end assembly so that the seal stays in place for multiple uses. One such seal is described in U.S. Patent Publication No. 2007/0027447, the entire contents of which are expressly incorporated herein in their entirety. 
     There are two potential problems with a seal of this configuration, namely: (1) it needs to be soft enough (i.e., has a low durometer) to deform and create a seal, which means that the seal  15  wears down quickly, resulting in the handpiece  23  being no longer usable; and (2) the epoxy seal between the seal  15  and the tube end assembly  11  eventually becomes brittle and cracks due to exposure to repeated sterilization cycles (e.g., via chemical sterilization or autoclaving). 
     Once the integrity of the seal is lost, collateral damage can occur any time electrosurgical energy is applied to the device. In the illustrated device, the laparoscopic surgical tip  20  is assembled to the tube of the handpiece  23  using a dual-threaded threaded connector. In other words, the tip  20  includes a yoke  50  having external threading, which engages complementary internal threading on an actuation rod (not shown) extending along the length of the tube  61  (thereby providing for the actuation of the end effector), and a back hub  400  includes internal threading (not shown) which engages complimentary external threading  21  on the tube end assembly  11  to secure the back hub to the tube  61 . The seal  15  on the handpiece  23  is compressed by the back hub to create a barrier for electricity and fluids. 
     SUMMARY OF THE INVENTION 
     A feature of the disclosure provides handpiece for interfacing with an instrument tip. The handpiece may include a tube end having an interface at a distalmost end thereof and configured to attach to the instrument tip, the tube end having a retention seal channel about an exterior of the tube end, a retention seal fixedly positioned in the retention seal channel, the retention seal having a sealing ring channel about an exterior of the retention seal, an elastically-deformable sealing ring press-fit into the sealing ring channel such that the sealing ring is immovable in a longitudinal direction of the tube end, and an outer sheath positioned about the tube end such that the outer sheath and tube end sandwich the sealing ring and at least a portion of the retention seal. 
     The interface may be threaded and configured to attach to complimentary threads on the instrument tip. Also, the sealing ring may have a pentagonal cross section. 
     The retention seal may be made of a material which is softer than the tube end, and the sealing ring may be made of a material which is softer than the retention seal. The retention seal may further include a ridge positioned about a circumference of the tube end, the ridge further positioned, in the longitudinal direction of the tube end, between a distalmost end of the outer sheath and the interface. The ridge may be further configured to engage an inside of a back hub of the instrument tip and create a seal therewith. 
     The retention seal may further include a flange inwardly tapering toward a proximal end of the tube end, the flange positioned at a distalmost end of the outer sheath and configured to restrict movement of the outer sheath relative to the tube end. Also, the retention seal may be molded to the retention seal channel. Further, the retention seal may be made of plastic. 
     In the longitudinal direction of the tube end, the outside of the sealing ring may be downwardly tapered from a highest center point, and a lowest point of the outside of the sealing ring may be flush with the outside of the retention seal. 
     The tube end may further include a protrusion on the outside thereof, the retention seal may further include a recess, such that the protrusion engages with the recess. 
     Another feature of the disclosure provides an instrument having an instrument tip, and a handpiece for interfacing with the instrument tip. The handpiece may include a tube end having an interface at a distalmost end thereof and configured to removably attach to the instrument tip, the tube end having a retention seal channel about an exterior of the tube end, a retention seal fixedly positioned in the retention seal channel, the retention seal having a sealing ring channel about an exterior of the retention seal, an elastically-deformable sealing ring press-fit into the sealing ring channel such that the sealing ring may be immovable in a longitudinal direction of the tube end, and an outer sheath positioned about the tube end such that the outer sheath and tube end sandwich the sealing ring and at least a portion of the retention seal. 
     The instrument tip may include instrument tip threads, and the interface may include interface threads such that the interface threads threadedly engage with the instrument tip threads. 
     The instrument tip may further include a back hub, the retention seal may further include a ridge positioned about a circumference of the tube end, the ridge further positioned, in the longitudinal direction of the tube end, between a distalmost end of the outer sheath and the interface, and the ridge may be configured to engage an inside of the back hub and create a seal therewith. 
     The retention seal may further include a flange inwardly tapering toward a proximal end of the tube end, the flange positioned at a distalmost end of the outer sheath and configured to restrict movement of the outer sheath relative to the tube end. Also, the retention seal may be molded to the retention seal channel. Also, in the longitudinal direction of the tube end, the outside of the sealing ring may be downwardly tapered from a highest center point, and a lowest point of the outside of the sealing ring may be flush with the outside of the retention seal. 
     A further feature of the disclosure provides a method of assembling a handpiece for interfacing with an instrument tip. The method may include affixing a retention seal in a retention seal channel on an outside of a tube end, press-fitting an elastically-deformable sealing ring into a sealing ring channel on an outside of the retention seal, such that the sealing ring may be immovable in a longitudinal direction of the tube end, and affixing an outer sheath about the tube end such that the outer sheath and tube end sandwich the sealing ring and at least a portion of the retention seal. Also, the affixing of the retention seal comprises overmolding the retention seal to the outside of the tube end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of an end of a reusable handpiece with a conventional seal; 
         FIG. 2  shows a perspective view of an assembled embodiment of a laparoscopic surgical tip of  FIG. 1 ; 
         FIG. 3  show a partial cutaway view of a tube end assembly according to a feature of the disclosure; 
         FIG. 4  shows a side view of the tube end assembly according to a feature of the disclosure; 
         FIG. 5  shows a side sectional view of the tube end assembly according to a feature of the disclosure, taken along lines A-A of  FIG. 4 ; 
         FIG. 6  shows a side sectional view of the tube end and retention seal according to a feature of the disclosure; 
         FIG. 7  shows a side view of the tube end and retention seal according to a feature of the disclosure; and 
         FIG. 8  shows a perspective view of the sealing ring according to a feature of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only, and are presented for providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice. 
       FIGS. 3-8  show an exemplary embodiment of components of a tube end assembly  111  of a reusable handpiece  123  in accordance with a non-limiting aspect of the disclosure. The tube end assembly  111  includes a tube end  101  having an interface  121  for engaging and/or attaching to the back hub  400  of the tip  20 . This interface  121  may include exterior threading (which may threadedly engage with complimentary threads on the back hub  400  of the tip  21 ). The tube end may be made of stainless steel or other suitable material. 
     The proximal end of the tube end  101  is configured to attach to a distal end of a tube  161  to form a continuous lumen therewith, through which an actuable shaft may be inserted. The tube end  101  also includes a channel  102  located between the interface  121  and proximal end of the tube end. This channel  102  is configured to receive an extended retention seal  104 , which is overmolded to the tube end  101  by injection molding. In this way, the use of epoxy or other adhesives is avoided. The retention seal  104  may be made from polypropylene or any other suitable material, and may have a Rockwell hardness of 93, but materials of other suitable hardnesses may be used. The retention seal  104 , tube end  101  and sealing ring  150  (and tube  161 ) are covered with a fluid-resistant outer sheath  116  which may be heat-shrunk and/or extruded thereover, thereby forming the tube end assembly  111 . The outer sheath  116  may be made of polyetheretherketone (PEEK) or other suitable material. 
     The retention seal  104 , once affixed to the tube end  101 , is generally flush therewith. The retention seal  104  includes an internal recess  106  for engaging a protrusion  108  on the tube end. In this way, the retention seal  104  is further prevented from movement in the axial direction relative to the tube end  101 . The retention seal  104  includes, in this order from the distal direction, a featureless distalmost part  110 , a ridge  112 , a featureless intermediate part  113 , a flange  114 , a channel  108  and a proximal part  118  which inwardly tapers in the proximal direction. The diameter of the tube end  101  at the distalmost part may be 0.155-0.158 inches, although other suitable dimensions may be used, and the diameter of the tube end at the ridge  112  may be 0.164-0.0166 inches, although other suitable dimensions may be used. 
     The ridge  112  may have a trapezoidal or rounded cross-section, or may have a cross-section that is a combination of both, e.g., by having rounded sides and a flat uppermost part, the latter of which may have a width in longitudinal direction X of 0.005-0.007 inches, although other suitable dimensions may be used. The ridge is configured to engage the inner surface of the back hub  400  of the tip  20  to create a seal therewith, which prevents fluid from entering the instrument at the tip-handpiece connection point (i.e., the “seam”) thereof. This engagement also preserves the electrical safety of the instrument, since electricity does not flow where it is not wanted. 
     The flange  114  inwardly tapers toward a proximal end of the tube end  101 , and is affixed to a distalmost end of the outer sheath  116 . The flange is configured to restrict movement of the outer sheath relative to the tube end  101 . The diameter of the tube end  101  at the flange  114  may be 0.196 inches, although other suitable dimensions may be used. 
     The channel  108  of the retention seal  104  is configured to retain an elastically-deformable sealing ring  150 , which is press-fit into the channel, which serves to prevent movement of the seal in the longitudinal direction X relative to the retention seal. Once inserted into the channel  108 , the sealing ring  150  is covered (along with the rest of the tube end assembly  111 ) by the outer sheath  116 . Thus, as shown in  FIG. 5 , the sealing ring  150  is sandwiched between the outer sheath  116  and the retention seal  104 , and therefore the sealing ring and at least a portion of the retention seal are sandwiched between the outer sheath  116  and tube end. 
     The channel  108  may have a width in the longitudinal direction X of 0.090 inches, and the sealing ring  150  may have a width in the longitudinal direction X of 0.080 inches, although other widths of each of these elements may be used. Once the sealing ring  150  is covered (along with the rest of the tube end assembly  111 ) by the outer sheath  116 , the pressure of the outer sheath against the sealing ring causes the sealing ring to expand in the longitudinal direction X and therefore fill the channel  108 , and can form a secure seal therewith without the use of epoxy or other adhesive. Further, rather than forming a right angle in the channel  108 , the intersection between the channel walls and channel bottom may be curved. 
     The sealing ring  150  may have a pentagonal cross section. For example, as shown in  FIGS. 3, 5 and 8 , in the longitudinal direction X the outside of the sealing ring  150  may be downwardly tapered from a highest center point  150   a  to a lowest point at the edge points of the sealing ring, such that the edge points are flush with the outside of the retention seal  104 . The sealing ring  150  may have a Shore durometer of 70, but materials of other suitable durometers may be used. The pentagonal cross section of the sealing ring  150 , together with the Shore durometer, allows the sealing ring to be installed in the outer sheath  116  without getting torn or otherwise damaged during the assembly process, and further helps prevent the outer sheath from displacement in the longitudinal direction X relative to the sealing ring, while still form a secure seal between the sealing ring and the outer sheath, without the use of epoxy or other adhesive. Further, the sealing ring  150  may be made out of ethylene propylene diene terpolymer (EPDM); however, other flexible materials may be used. Thus, the retention seal  104  is made of a material which is softer than the tube end  101 , and the sealing ring  150  is made of a material which is softer than the retention seal. 
     A method of assembling the tube end assembly  111  will now be described. First, the extended retention seal  104  is overmolded to the channel  102  of the tube end  101  by injection molding. Then, the sealing ring  150  is press fit into the channel  108  of the retention seal  104 . Next, the retention seal  104 , tube end  101  and sealing ring  150  (and tube  161 ) are covered with the outer sheath  116  by heat shrinking and/or extrusion thereover, thereby forming the tube end assembly  111 . 
     In view of the foregoing, the present disclosure, through one or more of its various aspects, embodiments and/or specific features or sub-components, is thus intended to bring out one or more of the advantages as specifically noted below. While the present disclosure includes description with respect to a medical device and procedure, the present invention may be used in a variety of other, non-medical, environments. 
     The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of apparatus and systems that utilize the structures or methods described herein. Many other embodiments may be apparent to those of skill in the art upon reviewing the disclosure. Other embodiments may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. Additionally, the illustrations are merely representational and may not be drawn to scale. Certain proportions within the illustrations may be exaggerated, while other proportions may be minimized. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive. 
     One or more embodiments of the disclosure may be referred to herein, individually and/or collectively, by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any particular invention or inventive concept. Moreover, although specific embodiments have been illustrated and described herein, it should be appreciated that any subsequent arrangement designed to achieve the same or similar purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all subsequent adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the description. 
     The Abstract of the Disclosure is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may be directed to less than all of the features of any of the disclosed embodiments. Thus, the following claims are incorporated into the Detailed Description, with each claim standing on its own as defining separately claimed subject matter. 
     The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments which fall within the true spirit and scope of the present disclosure. Thus, to the maximum extent allowed by law, the scope of the present disclosure is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.