A surgical instrument includes a housing and an elongated shaft extending distally therefrom. The elongated shaft includes a proximal portion, a distal portion and a flexible portion supported therebetween. The flexible portion permits pivotal movement of the distal portion of the elongated shaft and an end effector supported thereon. A locking mechanism is operatively associated with the flexible portion of the elongated shaft to selectively impede pivotal motion of the distal portion. The locking mechanism includes a fluid chamber defined within the flexible portion in which a variable viscosity fluid disposed. The variable viscosity fluid is responsive to the application of an electromagnetic field to exhibit increased rigidity in the presence of the electromagnetic field and reduced rigidity in the absence of the electromagnetic field. An electrical coil is arranged such that the electromagnetic field may be selectively induced by the delivery of electrical energy from a power source.

BACKGROUND

1. Technical Field

The present disclosure relates to a surgical apparatus for laparoscopic and endoscopic procedures. In particular, the disclosure relates to a surgical apparatus having a locking mechanism for maintaining a remotely-actuated component of the instrument at a particular position or orientation.

2. Background of Related Art

Typically in a laparoscopic, endoscopic, or other minimally invasive surgical procedure, a small incision or puncture is made in a patient's body. A cannula is then inserted into a body cavity through the incision, which provides a passageway for inserting various surgical devices such as scissors, dissectors, retractors, or similar instruments. To facilitate operability through the cannula, instruments adapted for laparoscopic or endoscopic surgery typically include a relatively narrow, elongated shaft extending distally from a housing, and supporting an end effector at its distal end. Arranging the shaft of such an instrument through the cannula allows a surgeon to manipulate actuators on the housing from outside the body to induce the end effector to carry out a surgical procedure at a remote internal surgical site. This type of minimally invasive procedure has proven beneficial over traditional open surgery due to reduced trauma, improved healing and other attendant advantages.

Some laparoscopic or endoscopic instruments are steerable, and thus may provide a surgeon with a range of operability suitable for a particular surgical purpose. For example, an instrument may be configured such that the end effector may be aligned with a longitudinal axis of the instrument to facilitate insertion of the elongated shaft through the cannula. Thereafter, the end effector may be induced to articulate, or move off-axis as necessary to appropriately orient the end effector for engaging the targeted tissue. Some mechanisms for articulating the distal end of an endoscopic instrument include a pair of tendons, or tension-bearing drive cables, with distal ends anchored to the articulating portion of the instrument on opposite sides of the longitudinal axis. The proximal ends of the drive cables are operatively coupled to an actuator on the housing that is responsive to manipulation by the surgeon to draw one of the drive cables proximally while simultaneously permitting distal motion in the other drive cable. This motion in the drive cables induces pivotal motion of the articulating portion of the instrument.

When the end effector of a steerable, articulating instrument has been satisfactorily positioned and oriented, a surgeon may maintain the position and orientation of the end effector by continuously exerting the necessary forces on the actuators at the housing. Alternatively, some instruments are provided with a locking mechanism that permits the surgeon to temporarily lock the position and orientation of the end effector so that a continuous exertion of force at the housing is not required. Often these locking mechanisms operate by engaging the drive cables within the housing to arrest their motion. However, regardless of the construction materials, the drive cables exhibit a spring rate that is amplified over the length of the drive cables, and thus, the drive cables may tend to stretch when external loads are applied to the elongated shaft. This tendency to stretch may be associated with an unintended change in orientation of the end effector, e.g., without a corresponding manipulation of the actuators initiated by the surgeon.

SUMMARY

The present disclosure describes a surgical instrument including a housing and an elongated shaft extending distally from the housing, the elongated shaft includes a proximal portion defining a longitudinal axis, a distal portion, and at least one flexible portion supported between the proximal and distal portions to permit pivotal movement of the distal portion of the elongated shaft with respect to the longitudinal axis. An end effector is supported by the distal portion of the elongated shaft, and is adapted for surgically treating tissue. A locking mechanism is operatively associated with the at least one flexible portion of the elongated shaft to selectively impede pivotal motion of the distal portion of the elongated shaft. The locking mechanism includes a fluid chamber defined within the flexible portion of the elongated shaft and a variable viscosity fluid disposed within the fluid chamber. The variable viscosity fluid is responsive to the application of an electromagnetic field such that the variable viscosity fluid exhibits an increased rigidity in the presence of the electromagnetic field and a reduced rigidity in the absence of the electromagnetic field. An electrical coil is coupled to a power source and extends at least partially through the flexible portion of the elongated shaft. The electrical coil is arranged such that the electromagnetic field may be selectively induced by the delivery of electrical energy from the power source to the coil.

The variable viscosity fluid may include a ferrofluid. The power source may be operatively associated with a locking actuator supported by the housing, and the locking actuator may be operable between a locked position wherein the power source supplies electrical energy to the coil and an unlocked position wherein the power source prohibits the delivery of electrical energy to the coil. The locking actuator may also be responsive to movement to intermediate positions between the locked and unlocked positions to progressively increase and decrease the delivery of electrical energy to the coil.

A plurality of radially spaced fluid chambers may be defined within the flexible portion of the elongated shaft, and the coil may encircle each of the plurality of radially spaced fluid chambers. Alternatively or additionally, a plurality of longitudinally spaced fluid chambers may be defined in the flexible portion of the elongated shaft, and wherein a plurality of correspondingly longitudinally spaced coils may be arranged in the flexible portion of the elongated shaft. Each of the plurality of longitudinally spaced coils may be independently coupled to the power source such that an independent supply of electrical energy may be delivered to each of the longitudinally spaced coils.

The surgical instrument may also include at least one articulation cable extending at least partially through the elongated shaft. A distal end of the articulation cable may be operatively coupled to the distal portion of the elongated shaft and a proximal end of the articulation cable may be operatively coupled to an articulation actuator such that manipulation of the articulation actuator induces an attendant pivotal motion of the distal portion of the elongated shaft with respect to the longitudinal axis.

The end effector may include a pair of jaw members, and at least one of the jaw members may be selectively movable between an open position substantially spaced from the other of the pair of jaw members and a closed position wherein the jaw members are closer together. At least one of the pair of jaw members may be adapted to couple to a source of electrosurgical energy that is independent from the electrical energy delivered to the coil.

According to another aspect of the disclosure, an articulating surgical instrument includes a housing and an elongated shaft extending distally from the housing. The elongated shaft includes a proximal portion defining a longitudinal axis, a distal portion pivotally coupled to the proximal portion, and at least one flexible portion supported between the proximal and distal portions of the elongated shaft. An end effector is supported by the distal portion of the elongated shaft, and the end effector is adapted for surgically treating tissue. At least one tensile member extends longitudinally through the elongated shaft. The at least one tensile member is selectively movable to induce an attendant bending of the flexible portion of the elongated shaft and a corresponding pivotal motion of the distal portion of the elongated shaft. A locking mechanism is operatively associated with the flexible portion of the elongated shaft to selectively vary the rigidity of the flexible portion of the elongated shaft. The locking mechanism includes a variable viscosity fluid disposed within the flexible portion of the elongated shaft. The variable viscosity fluid is responsive to an electromagnetic field such that the variable viscosity fluid exhibits an increased rigidity in the presence of the electromagnetic field and a reduced rigidity in the absence of the electromagnetic field. The locking mechanism also includes a field generator selectively operable to apply and remove the electromagnetic field.

The at least one tensile member may include at least one pair of articulation cables selectively movable in opposed longitudinal directions to induce the attendant pivotal motion of the distal portion of the elongated shaft. The flexible portion of the elongated shaft may include an elongated extrusion constructed of a flexible material, and the at least one pair of articulation cables may be slidably disposed within at least one pair of articulation lumens extending through the elongated extrusion.

The variable viscosity fluid may be disposed within at least one fluid chamber defined in the elongated extrusion. The field generator may include a coiled conductor arranged about the at least one fluid chamber, and the coiled conductor may be electrically coupled to a power source disposed within the housing. The coiled conductor may be arranged in a relief notch defined in an exterior surface of the elongated extrusion that extends longitudinally along the elongated extrusion. A central lumen may be defined through the elongated extrusion, and wherein a return conductor may extend through the central lumen to couple a distal end of the coiled conductor to the power source.

The elongated extrusion may also include a pair of end sections that exhibit a reduced diameter with respect to a longitudinally central portion of the elongated extrusion. The end sections may be dimensioned to engage the proximal and distal portions of the elongated shaft.

DETAILED DESCRIPTION

Referring initially toFIG. 1, a steerable endoscopic instrument10is depicted generally as instrument10. Instrument10includes a housing12near a proximal end, an end effector16near a distal end and an elongated shaft18therebetween. Elongated shaft18includes a proximal portion20extending distally from the housing12and an articulating distal portion22supporting the end effector16. The articulating distal portion22includes an outer end effector support tube22a. The proximal portion20defines a longitudinal axis A-A, and is sufficiently long to position the end effector16through a cannula (not shown) at an operative site. An outer tubular member24is provided over the proximal portion20and, together with the end effector support tube22a, provides protection and support to the interior mechanisms therein (see, e.g.,FIG. 2). At least one joint or flexible portion28is established between the proximal and distal portions20,22of the elongated shaft18permitting the distal portion22and the end effector16to articulate or pivot relative to the longitudinal axis A-A as described in greater detail below (see, e.g.,FIG. 4). The end effector16defines an end effector axis B-B, which is aligned with the longitudinal axis A-A when the articulating distal portion22of the elongated shaft18is in a “home” configuration.

The end effector16includes a pair of opposing jaw members30and32. The jaw members30,32are operable from the housing12to move between a closed configuration and an open configuration (seeFIG. 4). When the end effector16is in the closed configuration, a distal portion of each of the jaw members30,32is adjacent the distal portion of the other of the jaw members30,32. The closed configuration allows the end effector16to assume a narrow profile to facilitate insertion of the end effector16through the cannula (not shown) into a body cavity. Inside the body cavity, the jaw members30,32may be moved to the open configuration in which the distal portions of the jaw members30,32are substantially spaced to receive tissue therebetween. The end effector16is configured for unilateral movement wherein only movable jaw member32moves relative to the end effector axis B-B (while stationary jaw member30remains stationary relative to the end effector axis B-B) as the end effector16is moved between the open and closed configurations. However, bilateral motion is also contemplated wherein both of the jaw members30,32are configured to be moveable relative to the axis B-B.

Housing12is accessible by the surgeon from outside the body cavity to control the positioning, orientation and operation of the end effector16when the end effector16is positioned inside the body cavity at a surgical site. To provide this operability, the housing12supports various actuators that are operable to induce or prohibit movement in the end effector16through various modes. These actuators may include a locking trigger40, and a pair of articulation dials42a,42b. The articulation dials42a,42bare operable to pivot the distal portion22of the elongated shaft18to various articulated orientations with respect to the longitudinal axis A-A. For example, articulation dial42amay be rotated in the direction of arrows “C0” to induce pivotal movement in a first plane, e.g., a vertical plane, as indicated by arrows “C1.” Similarly, articulation dial42bmay be rotated in the direction of arrows “D0” to induce pivotal movement in a second plane, e.g., a horizontal plane, as indicated by arrows “D1.”

The trigger40is operatively associated with a locking mechanism100to selectively adjust the rigidity of the flexible portion28, as described below with reference toFIG. 3. The locking trigger40is movable in a longitudinal direction as indicated by arrows “E0” between locked and unlocked positions. When the trigger40is in the unlocked position, e.g., a proximal position, the flexible portion28is pliable, and the articulation dials42a,42bare functional as described above. However, when the trigger40is in the locked position, e.g., a distal position, the flexible portion is substantially more rigid, and the articulation dials42a,42bare inoperable to pivot the distal portion22of the elongated shaft18as described in greater detail below. Thus, the trigger40is operable to lock and maintain the end effector16in a particular orientation with respect to the longitudinal axis A-A. As described in greater detail below, the trigger40may also be movable to intermediate positions to incrementally or progressively increase and decrease resistance to articulating motion as the locking trigger40is moved toward the locked position.

Other actuators include shoulder roll knob44, a pivoting handle46and a finger trigger48. The shoulder roll knob44is operable to rotate the elongated shaft18about the longitudinal axis A-A, and may thus cooperate with the articulation dials42a,42bto permit the end effector16to be appropriately positioned and oriented in a three dimensional environment to effectively engage tissue. The pivoting handle46may be approximated and separated relative to a stationary handle50to move the jaw members30,32between the open and closed configurations. Finger trigger48is operable to lock the pivoting handle46in an approximated position with respect to the stationary handle50, and thus maintain the jaw members30,32in the closed configuration.

When the jaw members30,32are in the closed configuration, the surgeon may initiate the delivery of electrosurgical energy to the jaw members30,32by manipulating a push button52provided on the housing12. In alternate embodiments, the delivery of electrosurgical energy may be initiated with a footswitch (not shown) or other external actuators. Push button52is in electrical communication with a source of electrosurgical energy, such as electrosurgical generator54. The electrosurgical generator54serves to produce electrosurgical energy and also to control and monitor the delivery of the electrosurgical energy. Various types of electrosurgical generators54, such as those generators provided by Covidien—Energy-based Devices, of Boulder, Colo., may be suitable for this purpose. Electrosurgical generator54may be housed within the stationary handle50as depicted schematically inFIG. 1, or may alternatively be electrically and mechanically coupled to the instrument10by a cable (not shown). The electrosurgical generator54is in electrical communication with at least one of the jaw members30,32.

Referring now toFIG. 2the elongated shaft18is depicted with the end effector support tube22aand the outer tubular member24separated from the flexible portion28. The flexible portion28includes a pliable material to permit elastic bending of the flexible portion28. In other embodiments (not shown) the flexible portion28may be constructed of a plurality of discrete rigid segments that are pivotally arranged with respect to one another to permit the distal portion22to pivot relative to the longitudinal axis A-A (FIG. 1). The flexible portion28permits passage of a drive member, such as drive tube60, therethrough. The drive tube60is operatively associated with the pivoting handle46and the end effector16such that manipulation of the pivoting handle46induces movement of the jaw members30,32between the open and closed configurations. The drive tube60may be configured to transmit tensile, compressive or torsion loads to the jaw members, or alternatively, the drive tube60may house additional drive members (not shown) for moving the jaw members30,32.

The flexible portion28also permits passage of four tensile members, such as articulation cables62. A distal end of each of the articulation cables62is secured to a distal-most portion of the flexible portion28, or may alternatively be secured to a component of distal articulating portion22, such as the end effector support tube22a. A proximal end (not shown) of each articulation cable62is operatively associated with one of the articulation dials42a,42b(FIG. 1). The articulation dials42a,42beach impart opposed longitudinal motion (seeFIG. 4) to the articulation cables62and, thus, pivotal motion of the distal portion22about the flexible portion28. The articulation cables62are arranged near an outer circumference of the flexible portion28and have a radial spacing of about 90 degrees. Thus, the articulation cables62define two orthogonal planes of articulation in which the distal portion22may pivot.

The articulation cables62may be constructed of stainless steel wire or other material suitable for transmitting tensile forces to the distal-most portion of the flexible portion28. Regardless of the construction materials, the articulation cables62exhibit a spring rate that is amplified over the length of the articulation cables62and thus, the articulation cables62may tend to stretch when external loads are applied to the elongated shaft18. This tendency to stretch may be associated with an unintended change in orientation of the distal portion22of the elongated shaft18, e.g., without a corresponding movement of the articulation dials42a,42binitiated by the surgeon. To diminish this unintended movement of the articulation cables62and end effector16, a locking mechanism100(FIG. 3) that permits the flexible portion28to exhibit a variable rigidity without directly engaging the articulation cables62may be provided.

Referring now toFIG. 3, the locking mechanism100is depicted with the flexible portion28in a curved configuration. The flexible portion28includes an elongated extrusion102constructed of a flexible, medical-grade material. Plastic and/or elastomeric materials that are sufficiently flexible, dimensionally stable, electrically insulating, and/or non-irritating when placed in contact with skin and other tissues may be included in the construction of the elongated extrusion68. The extrusion102includes end sections102aand102bthat exhibit a reduced diameter to facilitate coupling the flexible portion28between the end effector support tube22aand the outer tubular member24(FIG. 2). A central lumen104is defined in the elongated extrusion102and is configured to permit passage of the drive tube60(FIG. 2) therethrough. Spaced radially around the central lumen104, a set of articulation lumens106are defined in the extrusion102to permit passage and sliding movement of the articulation cables62(FIG. 2).

To provide the flexible portion28with a variable rigidity, a variable viscosity material, such as a ferrofluid “F,” is included in a plurality of fluid chambers110defined in the extrusion102. Plugs112are provided at the longitudinal extremities of the fluid chambers110to maintain the ferrofluids “F” therein. Typically, ferrofluids include magnetic particles, such as magnetite, dispersed and suspended in a carrier fluid and, thus, the ferrofluids tend to exhibit a change in viscosity in response to an applied electromagnetic field. In the presence of an electromagnetic field, the magnetic particles are induced to line up and rigidize the extrusion102to a degree that is proportional to the magnitude or strength of the electromagnetic field. To facilitate the generation of an electromagnetic field, a coiled wire114is arranged around the fluid chambers110in a relief notch or spiral groove116defined in an exterior surface of the extrusion102. Inducing an electric current to flow through the coiled wire114generates an electromagnetic field around the fluid chambers110. The electromagnetic field may have poles oriented along an axis of the extrusion102such that the ferrofluids tend to rigidize the extrusion102with whatever curvature was imparted to the extrusion102when the electromagnetic field was generated.

The coiled wire114may be coupled to a power source provided as part of the electrosurgical generator54. The power source may be a separate component of the generator54such that the current provided to the coiled wire114is independent of the electrosurgical current that is provided to the jaw members30,32(FIG. 1). Alternatively, the power source may be provided as a separate module entirely independent of the generator54. A proximal end of the coiled wire114is coupled to a negative (−) terminal of the generator54, and the distal end of the coiled wire114is coupled to a positive (+) or return terminal. The distal end of the coiled wire114may return to the generator54through the central lumen104, an additional longitudinal lumen (not shown) provided in the extrusion102, or may alternatively return in a spiral path through a spiral notch (not shown). In still other embodiments (not shown), the coiled wire114may be electrically coupled to the generator54through one or more of the articulation cables62.

The generator54is operatively coupled to the locking trigger40to control the supply of an electrical current to the coiled wire114. The flow of an electric current through the coiled wire114generates an electromagnetic field about the fluid chambers110, and the electromagnetic field, in turn, increases the viscosity of the ferrofluid “F” within the fluid chambers110. The characteristics of the electrical current supplied, and thus the characteristics of the electromagnetic field generated, and the resultant viscosity of the ferrofluid “F” may be dependent on the degree that the locking trigger40is moved toward a locked position. For example, the magnitude of the electromagnetic field generated may be proportional to the distance the locking trigger40is moved in the direction of the arrows “E0.” The degree to which the ferrofluids “F” in fluid chambers110rigidize the flexible portion28is controlled by the movement of the trigger40. When appropriate, the locking trigger40may be returned to the unlocked position to interrupt the supply of power to the coiled wire114, and return the flexible portion28to a pliable configuration.

Referring now toFIG. 4, when the locking mechanism100is in an unlocked configuration, and the flexible portion28is pliable, the distal portion22of the elongated shaft18may be moved to an articulated position. The surgeon may manipulate the articulation dials42a,42b(FIG. 1) to draw particular articulation cables62proximally while opposed articulation cables62are advanced distally as indicated by arrows “C2” and “D2.” This opposed longitudinal motion in the articulation cables62induces the flexible portion28to bend, and allows the end effector16to be appropriately positioned and oriented relative to targeted tissue (not shown). The jaw members30,32are moved to the open configuration to receive the tissue by manipulating pivoting handle46(FIG. 1) to move the drive tube60.

The surgeon may move the locking trigger40to maintain the distal portion22of the elongated shaft18at the articulated position. By moving the locking trigger40to rigidize the flexible portion28, the surgeon provides a stable platform for end effector16to be moved to the closed configuration about tissue. The jaw members30,32are permitted to clamp the tissue with an appropriate closure force, and electrosurgical energy may be provided to treat the tissue without unintended motion of the end effector16. Since the articulation cables62need not be engaged to maintain the articulated position of the distal portion22, any movement or stretching of the articulation cables62will not be transmitted to the end effector16. When the surgical procedure is complete, the surgeon may return the locking trigger40to the unlocked position to permit the flexible portion28to return to a pliable condition. The flexible portion28may then be returned to the aligned configuration depicted inFIG. 1to facilitate withdrawal of the end effector16from the operative site through a cannula (not shown).

Referring now toFIG. 5, an alternate embodiment of a locking mechanism200is depicted with a flexible extrusion202arranged in a generally straight configuration. The extrusion202includes a central lumen204, which permits passage of drive tube (not shown), electrical conduits, or other control mechanisms therethrough. The extrusion202defines a plurality of longitudinally spaced fluid chambers210a,210btherein. Each fluid chamber210a,210bis sealed with a plug112and filled with a ferrofluid “F.” A proximal set of fluid chambers210ais encircled by a coiled wire214athat extends longitudinally to the same general extent as the proximal fluid chambers210. A distal set of fluid chambers210bis similarly encircled by a distal coil214bthat extends longitudinally to the same general extent as the distal fluid chambers210b. Each of the coils214a,214bis independently coupled to a power source in the electrosurgical generator54such that an independent current may be induced to flow through each of the coils214aand214b.

In use, the viscosity of the ferrofluid “F” in each of the two sets of longitudinally spaced fluid chambers210a,210bmay be independently controlled by controlling an electric current flowing through each of the respective coils214a,214b. Independent control of the viscosity of the ferrofluid “F” in each of the sets of fluid chambers210a,210bmay, for example, facilitate the creation of compound curves in the extrusion202. An “s-curve” may be created by sequentially creating oppositely directed bends in a proximal and distal portion of the extrusion202. With the extrusion202in the straight configuration, a current may be induced to flow through only the distal coil214bwhile no current flows through the proximal coil214a. The proximal portion of the extrusion202will thus remain pliable while the distal portion will become more rigid. A surgeon may then induce bending of the proximal portion in the first direction while the distal portion remains generally straight. Thereafter, the surgeon may interrupt the current through the distal coil214hwhile inducing a current to flow through the proximal coil214a. The bend in the proximal portion of the extrusion202will be maintained due to the increased viscosity of the ferrofluid “F” in the proximal fluid chambers210a, while the distal portion of the extrusion202becomes pliable. The surgeon may then impart a bend to the distal portion of the extrusion202in a direction opposite to the bend in the proximal portion of the extrusion202.

The surgeon may employ a set of articulation cables62(FIG. 2) extending through articulation lumens (not shown) defined in the extrusion202to induce bending of the extrusion202. Alternatively, another mechanism (not shown) may be provided with the instrument, or the surgeon may rely on external implements to induce the bending.

Referring now toFIG. 6, another alternate embodiment of a locking mechanism200is depicted with a flexible extrusion302arranged in a generally straight configuration. The extrusion302includes a central lumen304, which permits passage of drive tube (not shown), electrical conduits, or other control mechanisms therethrough. The extrusion302defines a plurality of radially-spaced fluid chambers310, similar to the radially spaced fluid chambers110described above with reference toFIG. 3. Each fluid chamber310a,310bis sealed with a pair of plugs112and filled with a ferrofluid “F.” Each of the fluid chambers310is encircled by an independent coil314a,314b, which is coupled to an independent power source in the electrosurgical generator54. The coils314a,314bprovide independent control over the rigidity of the ferrofluid “F” in the fluid chambers310.

The embodiments of the disclosure described above include a ferrofluid “F” disposed within fluid chambers110,210,310. Other embodiments are envisioned in which other types of variable viscosity fluids are disposed in the fluid chambers110,210and310. For example, electro-rheological fluids (ER fluids) and magneto-rheological fluids (MR fluids) may also exhibit an appropriate change in rigidity in response to an applied electromagnetic field.

Although the foregoing disclosure has been described in some detail by way of illustration and example, for purposes of clarity or understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims.