Patent Description:
In surgical procedures, a suture is typically used to secure the edges of tissue together so as to maintain those tissue edges in proximity to one another until healing is substantially completed. The suture is generally directed through the portions of the tissue to be joined and formed into a single loop or stitch, which is then knotted or otherwise secured (e.g., with a crimped fastener) so as to maintain the edges of the tissue in the appropriate relationship to each other for healing to occur.

In some situations a series of individual, separate stitches of substantially uniform tension are made in tissue. Inasmuch as the stitches are individual and separate from one another, the removal of one stitch does not require the removal of all of the stitches or cause the remaining stitches to loosen. However, each individual stitch requires an individual knot (or some other stitch-closing device, e.g., a crimped fastener) for securing the stitch in place about the wound.

It is sometimes necessary or desirable to close a wound with sutures without having to form knots in the suture or utilize loop-closing devices (e.g., crimped fasteners), such as, for example, in the surgical repair of organs or tissues where access to the repair site is restricted. In these situations, a fused loop of suture can be used to maintain the wound edges in sufficient proximity for a sufficient period of time to allow healing to occur.

Polymer sutures are particularly amenable to various fusing or joining processes, such as, for example, by welding, where sections of the sutures can be fused together upon application of sufficient heat to the sections to cause partial melting and fusion of the sections of the sutures.

Efforts have heretofore been made to fuse together segments of polymer suture using (i) the direct application of heat, or (ii) the application of ultrasonic energy.

Unfortunately, effecting welding via the direct application of heat suffers from two significant disadvantages. First, the direct application of heat to sutures in situ may produce undesirable heating of the surrounding tissue. Second, with the direct application of heat to sutures, it is difficult to selectively melt only the interface between the suture segments which are to be welded without melting the entire cross-section of the suture, which can drastically weaken the suture.

For these reasons, it is generally preferred to apply non-thermal energy to the suture material in situ in order to induce localized heating of the suture material in the areas or sections to be fused. In particular, ultrasonic energy may be effectively applied to sections of suture material to induce frictional heating of the sections in order to fuse or weld the sections of the suture together. While such ultrasonic welding of sutures can be an important improvement over direct thermal welding of sutures (i.e., ultrasonic welding melts only the parts of the suture that touch each other and not the whole cross-section of the suture), thereby preserving the strength of the suture, ultrasonic welding suffers from two significant disadvantages of its own. First, ultrasonic welding requires bulky, expensive equipment. Such equipment may not be compatible with certain kinds of surgery and, in any case, increases cost. Second, due to the nature of ultrasonic transducers and waveguides, ultrasonic welding requires straight line access between the energy source and the weld site, so that it is incompatible with curved or flexible instruments.

<CIT> discloses a fused loop including portions of segments to be joined together which are fused in a welding process to form a welded joint.

It is, therefore, an object of the present invention to provide a new and improved approach for forming connections (which may also be referred to as joinders or welds) within the body which does not suffer from the problems associated with the prior art.

According to the present invention, there is provided an electrically weldable suture material according to claim <NUM>. Further developments of the invention can be gathered from the dependent claims.

These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein:.

This disclosure describes inventive concepts with reference to specific examples. However, the intent is to cover all modifications, equivalents, and alternatives of the inventive concepts within the scope of the appended claims.

Forming surgical stitches in anatomic regions with difficult surgical access is a challenge in minimally invasive surgery. This disclosure describes an invention that joins sutures by welding (instead of, for example, tying or knotting). This saves time and can be done in extremely confined spaces. Unlike existing suture welding systems, the present invention can deliver suture welds through a serpentine path, such as through a curved catheter, using low-cost welding apparatus. Aspects of the disclosed invention can be particularly beneficial to manufacturers of robotic surgical systems. For example, a fully automated suturing device accessory can be utilized in surgical robotic systems.

Conventional "needle-and-thread" suturing requires manual or instrument access and is time-consuming, requires maneuvering room and leaves bulky knots at the surgical site. Crimp-type joinder devices leave behind a foreign body (e.g., a metal crimp) at the joinder site, and the high crimping force required to actuate the crimp necessitates substantial shaft diameter and limited shaft length. Existing suture welding devices utilizing the direct application of heat risk undesirable heating of surrounding tissues and/or suture weakening. Existing ultrasonic suture welding devices are bulky and expensive and require straight line access to the surgical site. Existing surgical robotic manipulators are time-consuming, require maneuvering room, and have a steep learning curve.

Traditionally, formed sutures are passed through tissue with a needle and tied with a knot into a loop to close wounds and allow the healing of tissue. Minimally invasive surgery (MIS) and robotic surgery place demands on the surgeon's skill due to the need to tie suture knots in regions of the body which are inaccessible to the surgeon's hands. Many surgical instruments have been developed that assist the surgeon in knot tying or provide a knot substitute. Such instruments have been invented by the present inventor and others. One known instrument comprises a tool for the formation of welded loops of suture, and another considers the welded loop of suture itself as a surgical fastener. While this method of joining suture into stitches facilitates suturing in difficult to access regions of the body, in practice it requires an ultrasonic generator, transducer and wave guide to complete welds in monofilament suture. This apparatus is bulky and expensive, and requires straight-line access to the surgical site from the point of incision.

The present invention seeks to improve upon these earlier inventions through the use of a novel suture material.

A novel aspect of the disclosed invention includes:
a suture material that is directly weldable using a small amount of simple low voltage electrical energy;.

Aspects of the present disclosure include:.

These, and other, benefits can be achieved by the new suture material of the present invention.

The suture material aspect of the present invention is made of a filament of biocompatible material, of a diameter, strength and flexibility consistent with surgical suture, and electrically conductive with a predictable resistance value.

The apparatus aspect includes a mechanism for holding the overlapping portion of a suture loop; a mechanism for applying contact pressure through the overlapping region; and a mechanism for applying and controlling electrical current through the overlapping region to cause localized heating of the overlapping region by the electrical current passing through the overlapping region and thereby causing localized melting of the overlapping region, which then re-solidifies so as to form a weld.

Some versions of the apparatus further include a mechanism for clamping the suture to maintain suture tension during the welding process; a mechanism for trimming suture tails extending past the suture loop; a handle with controls for allowing a user (e.g., a surgeon) to maneuver the apparatus and initiate the welding process; and an elongated straight, curved, articulating, flexible and/or steerable shaft connecting the distal welding apparatus to the proximal handle, allowing the user to maneuver the welding apparatus into regions of the body with difficult access (such as in MIS procedures).

Further versions of the apparatus include means for controllably or automatically penetrating tissue, passing suture, tensioning suture, trimming suture tails and releasing the formed tissue-fastening suture loop. Examples of these means are disclosed in prior <CIT> by the present inventor and may be used individually or in combination with this new welding apparatus.

The welding process aspect shares many characteristics in common with resistance or spot welding of metals, with several important novel distinctions, including but not limited to: low voltage and special electrical isolation necessary for medical devices; the ability to work with non-metallic conductive materials; and means for controlling the localization and depth of material melt so as to preserve the high strength of the highly linearized molecular chains of the conductive polymer or the composite materials being welded.

The suture loop formed by the material, apparatus and process disclosed herein is a tissue-fastening device or construct in the form of a continuous loop formed in situ. The loop comprises a filament of the biocompatible, conductive material disclosed herein, arcing approximately in the configuration of a circle, with an overlapping region joined by a weld.

Also disclosed herein are other structures made of the disclosed material, and welded in situ, but not necessarily taking the form of a loop or comprising filamentous material of a uniform cross-section.

<FIG> shows a short length of filamentous biocompatible material <NUM>. In one version of the present invention, material <NUM> has the characteristics of being substantially round in cross-section, and falling within the ranges dictated by United States Pharmacopeia for suture diameters (USP29-<NUM>) and tensile strengths (USP29-<NUM>) and equivalent international standards. Material <NUM> further has the characteristics of being electrically conductive with a known resistance, and meltable with a melting temperature above <NUM>° C (so that material <NUM> is in solid form in a human body). Thus, material <NUM> comprises an electrically conductive thermoplastic material.

In a preferred form of the invention, material <NUM> is a monofilament of a thermoplastic polymer compounded with a conductive additive. In some versions, a dispersant is used to assure uniform mixing of the conductive additive within the polymer matrix. In some versions, the base thermoplastic polymer and conductive additive (and dispersant, if required) are melt-compounded (mixed), extruded, and drawn to produce a monofilament with substantially linear molecular chains for superior strength and flexibility. In other versions, the melt-compounded (mixed) material is injection molded into single or multi-part devices for medical applications. In some versions, the thermoplastic polymer is a bio-absorbable material currently approved for use as a suture or implant material (e.g., Polylactic Acid (PLA), Polyglycolide (PGA), Polydioxanone (PDS), a thermoplastic linear polyester such as that sold under the tradename TephaFLEX™, etc.). In other versions, the thermoplastic polymer is a non-absorbable material (e.g., Nylon, Polypropylene, Polycarbonate, etc.). In some versions, the conductive additive is an inert and/or non-toxic material such as carbon black, carbon fiber, iron oxide (Fe203 and others) or metallic powders or nanoparticles. In other versions, the conductive additive is any one of intrinsically conducting polymers (ICPs) including, but not limited to, polyacetylene, polyaniline, polythiophene, polyphenylenevinylene. In some versions, these non-thermoplastic polymers are compounded with thermoplastic base polymers. In other versions, the non-thermoplastic polymers are applied as a film coating to a base polymer filament or part. In some versions the conductive coating is a continuous or patterned coating of conductive ink. In some versions a conductive polymer or composite may be co-extruded on the outside of another not necessarily conductive polymer at its core. In a version the core material has a higher melting temperature than the co-extruded outside layer. In other versions, the filament may be a multi-strand structure such as braided suture made of bundles of microfilaments of conductive thermoplastic polymer, or a composite of different filaments braided together. In one version, conductive and non-conductive filaments are combined into a single braided suture. In another embodiment, microfilaments of varying melt temperatures and conductivity are braided together such that localized weld melting does not melt filaments of higher melting temperature, thereby preserving their highly linearized molecular orientation and high strength characteristics and producing a strong weld region. In one version, high strength, high-melt-temperature polymer filaments are provided in a low-melt temperature metallic matrix such that when applying electric current through adjacent portions of the polymer filament/metal matrix, the metal fuses but leaves the high strength filaments undamaged. In still another version, metallic suture or wire is used, however, pure metal is generally less desirable than conductive thermoplastic because high melt temperatures of metals and high thermal conductivity in metals risk damage to surrounding tissue, and melt spread in metals is more difficult to control than melt spread in polymers. In a version of the material, the material filament has transverse (side-to-side) conductivity but not axial (end-to-end) conductivity, which has the benefit of protecting the body from stray electrical current in the event of a break in the suture before or during welding. The transverse but not axial conductivity feature may result from drawing or stretching a composite material with a low conductive additive fill ratio, since the chain of additive may be broken axially during stretching but compacted transversely due to diameter reduction.

According to the invention, material <NUM> is a conductive thermoplastic polymer.

<FIG> shows an apparatus <NUM> for welding a length of conductive thermoplastic suture <NUM>. The length of conductive thermoplastic suture <NUM> comprises a first end <NUM> and a second end <NUM>. First end <NUM> and second end <NUM> overlap at a contact point <NUM> so as to form a loop of suture <NUM>. The loop of suture <NUM> is held in its loop configuration by a clamping mechanism <NUM> applied at contact point <NUM>. Clamping mechanism <NUM> comprises a first electrode <NUM> conforming to the surface of first end <NUM> of suture <NUM> and a second electrode <NUM> conforming to the surface of second end <NUM> of suture <NUM>. A spring <NUM> applies a predetermined force between electrodes <NUM>, <NUM> so as to maintain pressure on contact point <NUM>. In one version, first electrode <NUM> and second electrode <NUM> are disposed substantially parallel to one another, resulting in line contact between first suture end <NUM> and second suture end <NUM> (not shown). In another version (i.e., the version shown in <FIG>), there is a relative curvature between first electrode <NUM> and second electrode <NUM>, resulting in a point contact between first suture end <NUM> and second suture end <NUM>. A structural frame <NUM> holds the components of the clamping mechanism (i.e., first electrode <NUM>, second electrode <NUM> and spring <NUM>) in place. Importantly, structural frame <NUM> is nonconductive between first electrode <NUM> and second electrode <NUM>. An electrical circuit <NUM> comprising, at a minimum, a power source <NUM> and a switch <NUM>, is connected to first electrode <NUM> and second electrode <NUM> as shown in <FIG> such that closing switch <NUM> applies a voltage across first electrode <NUM> and second electrode <NUM> and allows current to flow through first suture end <NUM> and second suture end <NUM> at contact point <NUM>. Preferably, power source <NUM> comprises a DC battery, but in other versions, power source <NUM> may comprise an exterior AC power source with an isolation transformer and a rectifier, or a low- or high-frequency AC power source.

In other versions of the present disclosure, additional features may be added to apparatus <NUM> in order to facilitate its use as a surgical instrument, such as tissue penetrating and suture passing means; tensioning means; clamping means to secure suture ends <NUM>, <NUM> so as to facilitate welding with the suture under tension; suture tail trimming means; weld region drying gas introduction means; an elongated and/or serpentine delivery shaft; and/or a handle for manual user interface or an electro-mechanical interface for connection to a surgical robot. These additional means and features are well known in the art and described in detail in prior patents (e.g., <CIT>) by the present inventor and others.

An illustrative method and process for forming a weld in conductive thermoplastic suture <NUM> is shown in <FIG>. Closing switch <NUM> causes current to flow from first electrode <NUM>, through first suture end <NUM>, across contact point <NUM>, through second suture end <NUM> and then to second electrode <NUM>. The highest resistance in this circuit is at contact point <NUM>, resulting in heat build-up taking place in this region and spreading into first suture end <NUM> and second suture end <NUM>. The heat build-up results in a localized melt region <NUM> that spreads into first suture end <NUM> and second suture end <NUM> as the heat increases. In one version, switch <NUM> is opened and the current stopped before the melt spreads across the full cross-section of the suture material. This differs from conventional resistance welding of metal where the full metal thickness is usually desired to be involved in the weld and is due to the non-isotropic nature of drawn, extruded monofilament suture.

In order to repeatedly and reliably achieve the optimum depth of melt penetration into suture ends <NUM>, <NUM>, a number of process control methods may be employed. In many of these process control methods, we will be referring to circuitry and components not shown in the simplified schematic shown in <FIG>, such as a microprocessor and various sensors, however, they can be assumed to be deployed in the conventional manner familiar to those skilled in the art. In one such version, a simple timer is used to control the amount of time that the weld circuit is switched on. In another version, first and second electrodes <NUM>, <NUM> are configured such that as melting spreads, electrodes <NUM>, <NUM> move toward each other as the melted material is displaced, and electrodes <NUM>, <NUM> contact each other when the optimum amount of material has melted. The contacting electrodes short together, shunting current around the suture and stopping the heating. A current sensor may then be used to signal a microprocessor to interrupt the weld circuit. In another version, a displacement sensor may be substituted for the self-contacting electrodes to signal a microprocessor to shut off the circuit when the desired weld displacement has occurred. Other versions employ temperature sensors to control the weld circuit through a microprocessor, shutting off the weld circuit when a pre-set peak temperature or thermal distribution has been sensed. In still other versions, combinations of time, displacement and temperature sensors are employed and optimum weld parameters are determined by a microprocessor-based algorithm.

<FIG> shows a tissue fastening device or construct <NUM> having a length of electrically conductive thermoplastic material formed into a continuous loop in situ, and joined by a partial depth penetration weld. In this figure, we see regions of virgin monofilament <NUM> with high tensile strength resulting from highly linearized molecular chains, notionally represented by lines roughly parallel to the suture axis, surrounding a weld region <NUM> with amorphous molecular orientation, notionally represented by random, disorganized lines. The tensile strength of the virgin monofilament is significantly stronger than that of the re-melt region. When tension is placed on the loop, the top and bottom portions of the overlapping loop ends load the weld region in shear, and since the area of the weld region is greater than the cross-section of the suture, the stress in this region is reduced as long as there is virgin high strength suture material on both sides of the weld region to distribute the load.

<FIG> show a clip <NUM> made of molded conductive thermoplastic material that may be electrically welded in situ, e.g., to occlude vessels such as veins and arteries for surgical hemostasis, or to clamp together tissue, etc. <FIG> shows clip <NUM> prior to deployment. Clip <NUM> comprises a first end <NUM> having a recess <NUM> and a second, opposing end <NUM> having a protruding feature <NUM>. Protruding feature <NUM> on second end <NUM> mates with recess <NUM> on first end <NUM> so as to create a contact point of high resistance to initiate the weld melt. <FIG> shows clip <NUM> welded in situ around a blood vessel <NUM>. Electrodes (not shown) applied to facing surfaces of first end <NUM> and second end <NUM> on clip <NUM> initiate a weld melt region <NUM> and bond first end <NUM> and second end <NUM> to one another so that clip <NUM> occludes blood vessel <NUM>.

<FIG> show another illustrative device <NUM> made of molded conductive thermoplastic material that is electrically welded in situ to occlude a section of a hollow organ <NUM>, such as a stomach, to allow the organ to be surgically divided. Device <NUM> comprises (i) a first strip <NUM> having a row of conductive thermoplastic needles <NUM> terminating in needle tips <NUM>, and (ii) a second strip <NUM> having counterpart recesses (not shown) for receiving needle tips <NUM>. In this version of the disclosure, an apparatus (not shown) delivers first strip <NUM> of conductive thermoplastic needles <NUM> through two layers of the organ (i.e., through the two side walls of the hollow organ) and second strip <NUM> is welded to the needle tips <NUM> of first strip <NUM> after needle tips <NUM> have penetrated and emerged from the organ. By controlling the depth of melting of needles <NUM>, the distance between the top portion (i.e., second strip <NUM>) and bottom portion (i.e., first strip <NUM>) of device <NUM> can be controlled, thereby controlling the degree of "squeeze" applied to the organ and accommodating organs with variable thickness. In this way, welded surgical fasteners functionally similar to a row of stitches or surgical staples may be delivered in a continuous linear process.

<FIG> shows a suturing instrument <NUM> for surgery comprising a distal end <NUM> and a proximal end <NUM> connected by a shaft <NUM>. Distal end <NUM> is an end effector and includes mechanical and electrical means for manipulating tissue and suture material for the formation of surgical stitches. Proximal end <NUM> contains actuating means for driving and operating the stitch-forming means at distal end <NUM> through wires and linkages (not shown in <FIG>) passing through shaft <NUM>. Shaft <NUM> has sufficient length to reach anatomical structures within the interior of a body, with proximal end <NUM> of the instrument remaining outside of a body, distal end <NUM> reaching target tissue at a surgical site, and shaft <NUM> passing through intervening tissue and spaces, e.g., by passing through a small incision in a body wall such as the abdominal wall. In one version (not shown), proximal end <NUM> of instrument <NUM> includes a handle adapted to be held by a human hand and the actuating means on proximal end <NUM> includes various buttons, triggers, levers, etc. for controlling the stitch-forming means at distal end <NUM>, and a battery for supplying power to weld the suture. In another version (also not shown), the handle contains motors, linear actuators, pneumatic or hydraulic cylinders, or other actuation means to drive the stitch-formation means, a microprocessor-controlled circuit to sequence the stitch formation and welding, a trigger or button to initiate the stitch formation process, and a battery to power the actuators and circuit. Still other versions have a handle and external power means such as a power cord or pneumatic or hydraulic hoses. In another version (shown), proximal end <NUM> includes electrical and/or mechanical interfaces <NUM> for connection to a surgical robot.

<FIG> shows a version of a distal end effector <NUM> for surgical stitching instrument <NUM> (or other surgical stitching instrument). Distal end effector <NUM> comprises a slidable grasper <NUM> for grasping a piece of tissue and means for passing and welding a loop of suture about the grasped tissue, as will be discussed in further detail below.

Slidable grasper <NUM> includes a passage <NUM> for passing a length of conductive thermoplastic polymer monofilament suture <NUM> (having a distal end <NUM>) therethrough, a hook feature <NUM> with a groove <NUM> opening on the inside of hook feature <NUM>, and a needle hole <NUM> aligning with groove <NUM> of hook feature <NUM>. Slidable grasper <NUM> also comprises a bore <NUM> for passing a needle <NUM> therethrough.

In use, and looking now at <FIG>, hook feature <NUM> of slidable grasper <NUM> is moved proximally (i.e., in the direction of arrow <NUM>) so as to pinch the tissue to be sutured (not shown) between a first textured grasping surface <NUM> and a second textured grasping surface <NUM>.

Looking now at <FIG>, needle <NUM> comprises a groove <NUM> so that after needle <NUM> has been advanced through the tissue (not shown) which is pinched between grasping surfaces <NUM>, <NUM> and needle <NUM> is disposed in needle hole <NUM> of hook feature <NUM>, groove <NUM> in needle <NUM> is aligned with groove <NUM> in hook feature <NUM>, whereby to form a continuous circular path (i.e., by means of groove <NUM> of hook feature <NUM> and groove <NUM> in needle <NUM>).

Looking next at <FIG>, suture <NUM> may be advanced through the continuous circular path formed by groove <NUM> of needle <NUM> and groove <NUM> of hook feature <NUM> until distal end <NUM> of suture <NUM> passes back over a portion of suture <NUM> proximal to distal end <NUM>, whereby to form a loop of suture passing through the tissue captured in distal end effector <NUM>, with distal end <NUM> of suture <NUM> contacting the proximal portion of suture <NUM> at overlapping region <NUM>. Suture <NUM> is advanced by motor-driven rollers in shaft <NUM> and/or proximal end <NUM> of instrument <NUM> which engage and push suture <NUM> through the circular path, or by other driving means in shaft <NUM> and/or proximal end <NUM> of instrument <NUM> (not shown) known to those skilled in the art.

After suture <NUM> has been advanced through the aforementioned circular path so as to form the loop of suture, an articulating gripping mechanism <NUM> may be used to firmly grasp distal end <NUM> of suture <NUM> adjacent the proximal portion of suture <NUM> at overlapping region <NUM>, leaving proximal portion of suture <NUM> free to slide axially for tensioning. To this end, and looking now at <FIG>, articulating gripping mechanism <NUM> comprises a first lever <NUM> and a second lever <NUM> which pivot about pins <NUM> and <NUM>, respectively. When suture <NUM> is being advanced through groove <NUM> of needle <NUM> and groove <NUM> of hook feature <NUM>, levers <NUM>, <NUM> are held apart, creating a gap in line with groove <NUM> in needle <NUM> and circular groove <NUM> of hook feature <NUM>, thereby allowing distal end <NUM> of suture <NUM> to pass through the gap in order to form the loop of suture. After distal end <NUM> of suture <NUM> is in place at overlapping region <NUM>, levers <NUM>, <NUM> are closed on distal end <NUM> of suture <NUM>, grasping distal end <NUM> and holding it firmly in place in overlapping region <NUM>. Levers <NUM>, <NUM> are made of a nonelectrically-conductive material except for a first electrode <NUM> disposed where levers <NUM>, <NUM> grip distal end <NUM> of suture <NUM>. Electrode <NUM> only makes electrical contact with distal end <NUM> of suture <NUM>.

After distal end <NUM> of suture <NUM> is clamped by levers <NUM>, <NUM> in overlapping region <NUM>, needle <NUM> is retracted and the suture advancement means that advanced suture <NUM> through the circular path is reversed so as to retract the loop of suture <NUM> and tighten the loop of suture <NUM> around the tissue grasped by slidable grasper <NUM> (<FIG>).

Once the loop of suture has been tightened around the tissue (not shown), a second electrode <NUM> is advanced to contact the portion of suture that overlaps with distal end <NUM> of suture <NUM> (i.e., portion <NUM> of <FIG>) in overlapping region <NUM>. Voltage potential is applied across first electrode <NUM> and second electrode <NUM> and current flows across the overlapping suture region <NUM>, thereby causing heating, melting and the formation of a weld in accordance with the method described above in relation to <FIG>.

After welding distal end <NUM> of suture <NUM> to the proximal portion of the suture at overlapping suture region <NUM>, a knife blade <NUM> is advanced to cut the suture supply proximal to the weld so as to separate the welded loop from instrument <NUM> (Fig. <FIG>). Hook feature <NUM> of slidable grasper <NUM> is then moved distally so as to re-open slidable grasper <NUM>, thereby releasing the pinched tissue. First lever <NUM> and second lever <NUM> are also separated to release the welded loop stitch <NUM> surrounding the tissue (<FIG>). The actuators at proximal end <NUM> of instrument <NUM> then return distal end effector <NUM> to the position of <FIG> and instrument <NUM> is ready to form another stitch.

<FIG> shows a version of the present disclosure incorporated into a highly articulated end effector <NUM> for robotic surgery. This embodiment includes a four degree of freedom (DoF) slave-robot end effector controlled remotely by a surgeon stationed at a master-robot control console. The principal degrees of freedom include: an instrument shaft <NUM> rolling about axis R, a mid-section "knuckle" <NUM> articulating in pitch about axis P, and first (<NUM>) and second (<NUM>) independently rotating tool elements disposed in opposition to each other, each rotating about yaw axis Y. Other robotic end effectors employ articulating segments or other means to achieve four or five DoF motion. The end effector described thus far in this paragraph is known to the art and is in common usage in robotic surgery.

<FIG> shows an embodiment of the present disclosure that forms a suture stitch in the same manner as the disclosure described in <FIG>, but differs through the addition of a highly articulated end effector (e.g., the end effector of <FIG>). In an embodiment, first articulating opposed tool element <NUM> is a semi-circular shaped rigid body with an inward facing groove <NUM> terminating in a needle hole <NUM> at its distal end. Second tool element <NUM> is a semi-circular shaped needle with an inward facing suture groove <NUM> and a sharp tissue penetrating point <NUM> on its distal end. The distal portion of the needle <NUM> (i.e., second tool element <NUM>) has a radius <NUM> to align with needle-receiving hole <NUM> in tool element <NUM>. When first and second tool elements <NUM> and <NUM> are closed in opposition (as shown in <FIG>), inward facing grooves <NUM> and <NUM> form a continuous groove through which suture may be advanced.

<FIG> shows a partial section view of an embodiment of the present disclosure schematically displaying the means for forming a suture stitch with the end effector. A flexible suture delivery tube <NUM> aligns with grooves <NUM> and <NUM> in opposing tool elements <NUM> and <NUM> when tool elements <NUM> and <NUM> are closed in opposition. The distal end <NUM> of the suture delivery tube <NUM> is fixed relative to first tool element <NUM> (in other embodiments the mechanism may be reversed and delivery tube <NUM> may be fixed to second tool element <NUM>). The flexibility of the suture delivery tube <NUM> allows the suture delivery tube to maintain its alignment with first tool element <NUM> throughout the full range of motion of the articulating end effector. The flexible suture delivery tube <NUM> serves the same purpose as the suture passage <NUM> described in <FIG>, with the difference of being flexible and allowing articulation of the end effector.

<FIG> show detail views of suture grippers <NUM> and <NUM>. Suture grippers <NUM> and <NUM> provide multiple functions in the suture formation process. In an embodiment they are arranged on a ramped guide surface provided on the end effector (not shown in <FIG>, but of the sort well known to those skilled in the art of gripping mechanisms) such that they separate as grippers <NUM> and <NUM> move distally and come together as they move proximally. Their movement is controlled by flexible gripper actuation linkage <NUM> which has sufficient flexibility to actuate the grippers throughout the full range of motion of the end effector. The grippers <NUM> and <NUM> move into three distinct positions: feed position (<FIG>) where the grippers are separated partially to allow suture to pass between them, clamp/weld position (<FIG>) where steps <NUM> in the gripper surfaces come together to clamp and hold the distal end of the suture strand (i.e., the overlapping portions of the suture strand) for loop tensioning and welding, and release/cut position (<FIG>) where the grippers separate wide enough to release the welded loop of suture and sharp cutter surface <NUM> slides distally to snip the welded suture loop free of the suture supply exiting feed tube <NUM>.

<FIG> also shows weld electrode <NUM> actuated distally and proximally by flexible electrode linkage <NUM> which has sufficient flexibility to control movement of the weld electrode throughout the full range of motion of the. end effector. In an embodiment the suture grippers <NUM> and <NUM> are electrically insulated except for the distal surfaces of the grippers contacting the distal side of the overlapping conductive suture segments held in the clamped position. The electrode <NUM> is electrically insulated except for a portion of the distal surface which can be brought into contact with the proximal side of the overlapping conductive suture segments held in the clamped position. In an embodiment either or both flexible actuation linkages <NUM> (of grippers <NUM> and <NUM>) and <NUM> (of electrode <NUM>) are insulated, and conductive and arranged to deliver electrical energy to either the grippers or the electrode or both. In other embodiments separate flexible insulated wires deliver electrical energy to either or both grippers <NUM> and <NUM> and/or electrode <NUM>. In embodiments where only one element (i.e., the grippers <NUM> and <NUM>, or the electrode <NUM>) has an insulated conductor, the other element (i.e., the electrode <NUM>, or the grippers <NUM> and <NUM>) may be connected to ground through the instrument shaft and connected components. Electrical potential is applied between the non-insulated portions of the gripper surfaces and the electrode, causing current to flow through the overlapping conductive suture segments, thereby causing localized melting at the interface between the suture segments, resulting in a welded connection between the suture segments. Where the overlapping conductive suture segments are either end of a continuous suture loop, a welded stitch is formed.

<FIG> illustrate an embodiment of the present disclosure in a body as it might be viewed by a surgeon at a robotic control console.

<FIG> shows an opening <NUM> in tissue <NUM> that the surgeon would like to close with a stitch. The surgeon's hand and wrist movements at the master-robot on the control console are replicated by the instrument end effector <NUM> in the body. The surgeon's thumb and forefinger movements are replicated by the tool element <NUM> and the needle <NUM>. The surgeon positions the tool element <NUM> and needle <NUM> astride the tissue opening to be stitched.

<FIG> shows the tool element <NUM> and needle <NUM> closed in opposition in response to the surgeon bringing their thumb and forefinger together. The needle <NUM> has penetrated through both sides of the tissue opening, completing a continuous circular groove (i.e., the conjoined circular grooves <NUM> and <NUM>) from the needle <NUM> to the tool element <NUM>. If they are happy with the stitch location defined by the needle placement, the surgeon initiates the stitch process by depressing a footswitch, or a voice-activated command, or other means available to initiate action. In an embodiment the stitch process is a fully automated sequence. In other embodiments some steps are automatically initiated in sequence and others are initiated by the surgeon. The first step in this sequence is activation of a suture advancing mechanism connected to the flexible suture delivery tube <NUM>, which advances a fixed length of conductive suture equal to the circumference of the continuous inward facing groove of the tool element <NUM> and needle <NUM> (i.e., the conjoined circular grooves <NUM> and <NUM>), plus additional material to form an overlapping region for the suture loop. The next step in the sequence is activation of an actuating mechanism connected to the flexible gripper actuation linkage <NUM> and the suture grippers <NUM> and <NUM> to move the grippers from the feed position (<FIG>) to the clamp/weld position (<FIG>), thereby gripping the distal end of the advanced suture in the overlap region.

<FIG> shows the tool element <NUM> and needle <NUM> opened and released from the tissue leaving conductive suture <NUM> threaded through both sides of the tissue opening. In an embodiment this motion is controlled by the surgeon at the control console by separation of their thumb and forefinger. In another embodiment, the separation of the tool element <NUM> and needle <NUM> is automatically initiated by the robot as part of the automated stitching process.

<FIG> shows the suture loop tensioned by reversal of the suture advancing mechanism. In an embodiment, tensioning is initiated automatically and suture is pulled to a predetermined or programmed tension value. In another embodiment, the surgeon controls the tensioning process through a control means such as a trigger, slide mechanism, foot switch or similar means. In an embodiment, the control means includes tactile haptic feedback such that the surgeon has the sensation of pulling on the suture to achieve the desired tension of the stitch. In an embodiment where the separation of the tool element <NUM> and the needle <NUM> is performed automatically by the robot, the surgeon controls and feels tension through haptic feedback by separation of their thumb and forefinger which is temporarily disengaged from controlling the motion of the tool element <NUM> and needle <NUM>. Once desired or predetermined tension has been achieved, the weld process is initiated by initiation of an actuator connected to the flexible electrode linkage <NUM>. The electrode <NUM> is brought into contact with the proximal side of the overlapping region of the conductive suture loop with a predetermined contacting force. Electrical current is then passed through the overlapping region (i.e., by passing an electrical current between electrode <NUM> and grippers <NUM> and <NUM>), causing the interface between the suture segments in the overlapping region to locally melt and fuse into a weld.

<FIG> shows the final step of the stitching sequence where the tensioned, welded loop <NUM> has been cut free from the suture supply exiting the suture delivery tube <NUM> and released from the end effector by actuation and movement of the suture grippers <NUM> and <NUM> from the clamp/weld position (<FIG>) to the cut/release position (<FIG>).

<FIG> shows an embodiment with integrated tissue grasping and manipulation capability. This embodiment of an end effector has a first tool element <NUM>, a needle <NUM>, and a second opposing hollow tool element <NUM>. Hollow tool element <NUM> includes an opening <NUM> which is sufficiently large for needle <NUM> to rotate through, and a blunt or textured, non-tissue-penetrating end <NUM> that directly opposes and aligns with a matching blunt or textured non-tissue-penetrating end <NUM> on tool element <NUM>.

<FIG> show an embodiment of end effector with tissue grasping and manipulation capability (i.e., the end effector of <FIG>) as it might be viewed in a body by a surgeon at a robot control console.

<FIG> shows first and second opposing tool elements <NUM> and <NUM> separated in preparation for grasping tissue. Needle <NUM> is outside hollow tool element <NUM> and needle point <NUM> (not shown in <FIG>) protected in hollow opening <NUM>. The motion of the opposing tool elements is controlled by the movement of the surgeon's thumb and forefinger, and needle <NUM> moves with, and maintains its protected orientation with hollow tool element <NUM>, while the surgeon grasps and manipulates tissue as one might do with surgical forceps.

<FIG> shows the opposing tool elements <NUM> and <NUM> grasping tissue at a location where the surgeon would like to place a stitch. The non-tissue-penetrating ends of the opposing tool elements <NUM> and <NUM> pinch the tissue at the exact spot where the needle <NUM> will penetrate, thereby facilitating easy entry and penetration by the needle <NUM>. When satisfied with the location, the surgeon initiates the stitching process by depressing a foot switch, using a voice command or other means to initiate the automated sequence. The first step in the sequence is activation of an actuator that "fires" the needle <NUM> through the tissue.

<FIG> shows needle point <NUM> penetrating the tissue and seated in needle hole <NUM> in tool element <NUM>, and establishing (in conjunction with tool element <NUM>) an uninterrupted suture groove (i.e., the conjoined circular grooves <NUM> and <NUM>) through the tissue.

<FIG> shows hollow tool element <NUM> retracted from the tissue, either by action on the part of the surgeon or automatically as part of the automated stitch sequence, leaving needle <NUM> in place (i.e., passed through the tissue and seated in needle hole <NUM> in tool element <NUM>). The remainder of the stitch sequence is the same as that described in <FIG>.

Claim 1:
An electrically weldable suture material for positioning in the body of a human or another mammal, the suture material comprising a first portion and a second portion positionable in contact with one other, such that when the suture material is positioned in the body of a human or another mammal and electric current flows from said first portion to said second portion, heat is generated by electrical resistance at the point of contact between said first portion and said second portion so as to melt regions of said first portion and said second portion, and when the electric current is thereafter terminated, the melted regions of said first portion and said second portion re-solidify, characterized in that the suture material is a biocompatible conductive thermoplastic material.