Debridement device and method

Devices, systems and methods for cutting and sealing of tissue such as bone and soft tissue. Devices, systems and methods include delivery of energy including bipolar radiofrequency energy for sealing tissue which may be concurrent with delivery of fluid to a targeted tissue site. Devices include debridement devices which may include a fluid source. Devices include inner and outer shafts coaxially maintained and having cutters for debridement of tissue. An inner shaft may include electrodes apart from the cutter to minimize trauma to tissue during sealing or hemostasis. Devices may include a single, thin liner or sheath for electrically isolating the inner and outer shafts.

BACKGROUND

The present invention is generally directed to devices, systems and methods for cutting and sealing tissue such as bone and soft tissue. The present invention may be particularly suitable for sinus applications and nasopharyngeal/laryngeal procedures and may combine or provide Transcollation® technology with a microdebrider device.

Devices, systems and methods according to the present disclosure may be suitable for a variety of procedures including ear, nose and throat (ENT) procedures, head and neck procedures, otology procedures, including otoneurologic procedures. The present disclosure may be suitable for a varient of other surgical procedures including mastoidectomies and mastoidotomies; nasopharyngeal and laryngeal procedures such as tonsillectomies, trachael procedures, adenoidectomies, laryngeal lesion removal, and polypectomies; for sinus procedures such as polypectomies, septoplasties, removals of septal spurs, anstrostomies, frontal sinus trephination and irrigation, frontal sinus opening, endoscopic DCR, correction of deviated septums and trans-sphenoidal procedures; rhinoplasty and removal of fatty tissue in the maxillary and mandibular regions of the face.

Sinus surgery is challenging due to its location to sensitive organs such as the eyes and brain, the relatively small size of the anatomy of interest to the surgeon, and the complexity of the typical procedures. Examples of debriders with mechanical cutting components are described in U.S. Pat. Nos. 5,685,838; 5,957,881 and 6,293,957. These devices are particularly successful for powered tissue cutting and removal during sinus surgery, but do not include any mechanism for sealing tissue to reduce the amount of bleeding from the procedure. Sealing tissue is especially desirable during sinus surgery which tends to be a complex and precision oriented practice.

Electrosurgical technology was introduced in the 1920's. In the late 1960's, isolated generator technology was introduced. In the late 1980's, the effect of RF lesion generation was well known. See e.g., Cosman et al.,Radiofrequency lesion generation and its effect on tissue impedance, Applied Neurophysiology (1988) 51: 230-242. Radiofrequency ablation is successfully used in the treatment of unresectable solid tumors in the liver, lung, breast, kidney, adrenal glands, bone, and brain tissue. See e.g., Thanos et al.,Image-Guided Radiofrequency Ablation of a Pancreatic Tumor with a New Triple Spiral-Shaped Electrode, Cardiovasc. Intervent. Radiol. (2010) 33:215-218.

The use of RF energy to ablate tumors or other tissue is known. See e.g., McGahan J P, Brock J M, Tesluk H et al.,Hepatic ablation with use of radio-frequency electrocautery in the animal model. J Vasc Interv Radiol 1992; 3:291-297. Products capable of aggressive ablation can sometimes leave undesirable charring on tissue or stick to the tissue during a surgical procedure. Medical devices that combine mechanical cutting and an electrical component for cutting, ablating or coagulating tissue are described, for example, in U.S. Pat. Nos. 4,651,734 and 5,364,395.

Commercial medical devices that include monopolar ablation systems include the Invatec MIRAS RC, MIRAS TX and MIRAS LC systems previously available from Invatec of Italy. These systems included a probe, a grounding pad on the patient and a generator that provides energy in the range of 450 to 500 kHz. Other examples of RF bipolar ablation components for medical devices are disclosed in U.S. Pat. Nos. 5,366,446 and 5,697,536.

Medical devices are also used to ablate heart tissue with RF energy. See, e.g., Siefert et al.Radiofrequency Maze Ablation for Atrial Fibrillation, Circulation 90(4): I-594. Some patents describing RF ablation of heart tissue include U.S. Pat. Nos. 5,897,553, 6,063,081 and 6,165,174. Devices for RF ablation of cardiac tissue are typically much less aggressive than RF used to cut tissue as in many procedures on cardiac tissue, a surgeon only seeks to kill tissue instead of cutting or removing the tissue. Cardiac ablation of this type seeks to preserve the structural integrity of the cardiac tissue, but destroy the tissue's ability to transfer aberrant electrical signals that can disrupt the normal function of the heart.

Transcollation® technology, for example, the sealing energy supplied by the Aquamantys® System (available from Medtronic Advanced Energy of Portsmouth, N.H.) is a patented technology which stops bleeding and reduces blood loss during and after surgery and is a combination of radiofrequency (RF) energy and saline that provides hemostatic sealing of soft tissue and bone and may lower transfusion rates and reduce the need for other blood management products during or after surgery. Transcollation® technology integrates RF energy and saline to deliver controlled thermal energy to tissue. Coupling of saline and RF energy allows a device temperature to stay in a range which produces a tissue effect without the associated charring found in other ablation methods.

Other ablation devices include both mechanical cutting as well as ablation energy. For example, the PK diego® powered dissector is commercially available from Gyms ENT of Bartlett, Tenn. This device utilizes two mechanical cutting blade components that are moveable relative to each other, one of which acts as an electrode in a bipolar ablation system. The distal end portion of the device includes six layers to accomplish mechanical cutting and electrical coagulation. The dual use of one of the components as both a mechanical, oscillating cutting element and a portion of the bipolar system of the device is problematic for several reasons. First, the arrangement exposes the sharp mechanical cutting component to tissue just when hemostasis is sought. In addition, the electrode arrangement does not provide for optimal application of energy for hemostasis since the energy is applied essentially at a perimeter or outer edge of a cut tissue area rather than being applied to a central location of the cut tissue. The arrangement of the device also requires more layers than necessary in the construction of a device with both sharp cutters and RF ablation features. The overabundance of layers can make it difficult to design a small or optimally-sized distal end. Generally speaking, the larger the distal end, the more difficult it is for the surgeon to visualize the working surfaces of the device. The use of six layers at the distal end of the system also interferes with close intimate contact between the tissue and the electrodes. Some examples of cutting devices are described in U.S. Pat. Nos. 7,854,736 and 7,674,263.

The Medtronic Straightshot® M4 Microdebrider uses sharp cutters to cut tissue, and suction to withdraw tissue. While tissue debridement with the Medtronic microdebrider system is a simple and safe technique, some bleeding may occur. The Medtronic microdebrider does not include a feature dedicated to promoting hemostasis or bleeding management. Thus, nasal packing is often used.

DETAILED DESCRIPTION

FIG. 1illustrates a system10according to an aspect of the present invention. The system10includes a device100having a distal end region indicated generally at120and a proximal end region indicated generally at110. The device includes an outer shaft130and an inner shaft140coaxially maintained within the outer shaft130. A portion of the inner shaft140is shown inFIG. 1at distal end region120. Proximal end region110includes a button activation cell200comprising a housing204and a button202, the proximal end region further comprising a hub175coupled to inner shaft140. The hub is configured to couple to a handle or handpiece177which can be manipulated by a user (e.g., a surgeon). The handpiece177, in turn may be coupled to an integrated power console or IPC179for driving the device100and specifically for controlling rotation of inner shaft140. The IPC179may also include a fluid source (not shown) and may provide fluid delivery to device100.

Proximal end region110also includes a fluid source connector150, a power source connector160and a suction source connector170for connection to a fluid source152, a power source,162and/or a suction source of system10. One fluid useful with the present disclosure is saline, however, other fluids are contemplated. Power source162may be a generator and optionally may be designed for use with bipolar energy or a bipolar energy supply. For example, the Transcollation® sealing energy supplied by the Aquamantys® System (available from Medtronic Advanced Energy of Portsmouth, N.H.) may be used. Both the fluid source152and suction source172are optional components of system10. However, use of fluid in conjunction with energy delivery aids in providing optimal tissue effect as will be further explained, thus embodiments of the present invention include specific arrangement of the device100for coupling of energy with a fluid. In use, a fluid (e.g., saline) may be emitted from an opening at the distal end region of the device100. Tissue fragments and fluids can be removed from a surgical site through an opening (not shown inFIG. 1) in the distal end region via the suction source172, as will be further explained below.

FIG. 2shows an enlarged perspective view of distal end portion120of device100. The outer shaft130includes a window or opening134at a distal end135of the outer shaft135. Window134is defined by an outer shaft cutting edge or cutter132, which comprises cutting teeth133. The outer shaft130may be rigid or malleable or combinations thereof and may be made of a variety of metals and/or polymers or combinations thereof, for example may be made of stainless steel. A distal portion148of the inner shaft140can be seen through the window or opening134of outer shaft130. InFIG. 1, inner shaft140is depicted in a position such that an inner shaft cutting edge or cutter141(FIG. 3), comprising cutting teeth143is facing an inner wall (not shown) of outer shaft130. Cutter141defines an inner shaft window or opening154(FIG. 3). Outer and inner shaft cutters132and141may move relative to one another in oscillation or rotation (or both) in order to mechanically cut tissue. For example, outer shaft cutter132may remain stationary relative to the hub175and button assembly200while the inner shaft cutter141may rotate about a longitudinal axis A of the device, thereby cutting tissue.

Rotation of inner shaft140may be achieved via manipulation of hub175(FIG. 1). that can orient the inner shaft140relative to the outer shaft130and may additionally allow for locking of the inner shaft relative to the outer shaft in a desired position, i.e., inner shaft may be locked in position when cutter141is facing down and electrode assembly142is facing up. As described above, hub175may be connected to a handle or handpiece177which may be controlled by an IPC179. Alternatively, the hub175and/or handle portions may be manipulated manually. Inner shaft140may be selectively rotated to expose an electrode assembly142comprising electrodes142a,142b, through opening134of outer shaft130, as shown inFIG. 2. Electrodes142a,142bmay comprise electrode traces and the electrode traces may extend from the distal portion148of the inner shaft to a proximal end151(FIG. 10) of the inner shaft140. As depicted inFIG. 2, inner shaft140is positioned such that the inner shaft cutter141is facing the interior (not shown) of outer shaft130and may be said to be in a downward facing direction and comprise a downward position. In the downward position, tissue is shielded from the inner shaft cutter141during hemostasis (via energy delivery through electrodes142a,142b), thereby delivering energy to tissue with no attendant risk that the cutting teeth143of the inner shaft140will diminish the efforts to achieve hemostasis. Device100may thus comprise two modes: a cutting or debridement mode and a sealing or hemostasis mode and the two modes may be mutually exclusive, i.e. hemostasis is achieved via energy delivery to tissue while cutters132,141are not active or cutting. As described below, energy may be advantageously delivered simultaneously with a fluid such as saline to achieve an optimal tissue effect by delivering controlled thermal energy to tissue.

As depicted inFIG. 3, when the inner shaft140is oriented such that the cutter141is in the downward position, rotating inner shaft140approximately 180 degrees relative to the outer shaft130will expose inner shaft cutter141and inner shaft opening154through the outer shaft opening134. When the inner shaft cutter141is positioned as shown inFIG. 3, the inner shaft cutter141may be said to be in an upward position. The inner shaft opening154is fluidly connected to an inner shaft lumen156, a portion of which can be seen inFIG. 7. Lumen156extends from the inner shaft distal portion148to the proximal end151(FIG. 10) of inner shaft140and may be fluidly connected with the suction source172. With this configuration, tissue cut via inner and outer shaft cutters141,132may be aspirated into the inner shaft lumen156through the inner shaft opening154upon application of suction source172, thereby removing tissue from a target site.

With reference betweenFIGS. 4 and 5, the inner shaft140comprises a proximal assembly168including a proximal assembly shaft component169(more clearly seen inFIG. 5) and electrodes142aand142b. Inner shaft140also includes a joining assembly144, which may be a non-conductive component and more specifically may comprise a liquid crystal polymer (LCP) overmold assembly. The joining assembly144may effectively join or connect the distal portion148of inner shaft140with the proximal assembly shaft component169(most clearly depicted inFIG. 5). Joining assembly144includes an extension portion146which aids in minimizing arc tracking from the electrodes142aand142bas will be further elucidated in the following discussion.

Electrodes or electrode traces142aand142bcomprise bipolar electrodes and may comprise wet or dry electrodes. Electrodes142aand142bmay be used to deliver any suitable energy for purposes of coagulation, hemostasis or sealing of tissue. Electrodes142aand142bare particularly useful with fluid such as saline provided by fluid source152(FIG. 1) which may be emitted near the outer shaft opening134. Outer shaft opening134is fluidly connected to an outer shaft lumen136, shown in phantom inFIG. 7. Lumen136extends from outer shaft opening134to the proximal end region110of device100and may be fluidly connected to the fluid source152(FIG. 1). Thus, fluid can be delivered to the opening134of outer shaft130and interacts with electrode traces142a,142b, as will be further described with reference toFIG. 1. In this manner, electrode traces142aand142bcan advantageously provide Transcollation® sealing of tissue when used with the Transcollation® sealing energy supplied by the Aquamantys System, available from the Advanced Energy Division of Medtronic, Inc. With respect to “wet” RF coagulation technology, the technology for sealing tissue described in U.S. Pat. Nos. 6,558,385; 6,702,810, 6,953,461; 7,115,139, 7,311,708; 7,537,595; 7,645,277; 7,811,282; 7,998,140; 8,048,070; 8,083,736; and 8,361,068 (the entire contents of each of which is incorporated by reference) describe bipolar coagulation systems believed suitable for use in the present invention. Other systems for providing a source of energy are also contemplated.

BothFIGS. 4 and 5depict the distal end region120of device100, with outer shaft130removed.FIG. 4shows a portion of the inner shaft140coaxially maintained in an insulation liner or sheath180. The liner180may extend from a location proximal the inner shaft cutter141and cutting teeth143, along inner shaft140, to the proximal end151of inner shaft140. Liner180provides insulation between the inner and outer shafts130,140, thus providing electrical isolation of the electrodes142aand142bfrom outer shaft130as well as from one another while only adding a single, very thin layer to the overall device100. Liner180may be made of any suitable material, for example, fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE), or any other material suitable as a non-conductive or electrically insulative material. Regardless, liner180is constructed so as to be negligible in its contribution to the overall diameter of the device100and particularly the distal end region120of the device100.

FIG. 5shows the distal end region120of device100with both the outer shaft130and the insulation liner180removed, thus exposing only portions of inner shaft140. As described above, inner shaft140includes a distal portion148, which includes cutter141, and an inner shaft proximal assembly168including proximal assembly shaft component169. The individual distal portion148and shaft component169can be seen more clearly inFIG. 7in which the joining assembly144and electrodes142a,142bare removed. The proximal assembly shaft component169may comprise a variety of suitable materials and for example, may comprise a liquid crystal polymer (LCP) extruded shaft component that is configured to support the placement of metallized conductors (e.g., electrodes142a,142b) and may support overmolding (e.g. of joining assembly144) and/or a plating process, such as described below. Proximal assembly shaft component169may undergo a laser etching process to form the depressed areas145suitable for electrode placement or plating. Other methods of forming the depressed areas145are also contemplated.FIG. 6shows inner shaft140with the electrodes or electrode traces142a,142bremoved from the proximal portion168and joining assembly144. Electrodes142aand142bmay be formed on the proximal assembly shaft component169and on a portion of joining assembly144in a plating process for forming electrode traces. The portion over which the electrode traces may be applied includes depressed areas145(FIG. 6), which may be laser etched areas. One process of electrode plating may include first applying copper sufficient to conduct the desired power and then adding nickel and gold layers to the laser etched area145. Other metals and combinations of metals are also contemplated, for example, silver may be used or any other metal or combination of metals effective in providing a cross section which meets power requirements for the energy delivery. Regardless, the plating process and overall electrode142a,142bthickness or depth is configured such that the electrodes142a,142bdo not negatively impact the diameter of the device100. As but one example, the electrode plating process may result in a dimensional change to the overall diameter as little as 0.0015″.

FIG. 5also more fully depicts joining assembly144which joins the distal portion148with the inner shaft proximal assembly168of the inner shaft140. As seen inFIG. 5, portions of distal portion148and proximal assembly shaft component169may be configured in a “puzzle piece” arrangement as is indicated at joining assembly144which follows the lines of the puzzle piece. Each of the distal portion148and proximal assembly shaft component169include a mating edge192,190, respectively. This configuration distributes forces acting on the inner shaft140when the device100is in a cutting mode to aid in a secure coupling of the distal portion148and shaft component169. The joining assembly extension portion146is located between electrodes146aand146b. This extension portion146provides adequate space between the electrodes146a,146bto mitigate arc tracking between the two and to improve the tissue depth effect.

Returning toFIG. 1, when fluid from fluid source152is provided through lumen136of the outer shaft130, the fluid may travel between the outside diameter of the inner shaft140and the inside diameter of the outer shaft130to the distal end120of device100. Fluid travels distally down the lumen136of outer shaft130and may “pool” in an area shown inFIG. 1as essentially defined by the opening134of outer shaft130. Likewise, electrodes142aand142bmay be located slightly below the surface of the joining assembly144and/or the inner shaft proximal portion168(FIGS. 4,5), creating another area for fluid pooling. This depressed electrode142a,142bsurface can also prevent wear of the electrodes142a,142b. Pooling of fluid at the electrodes142a,142ballows for effective interaction between the fluid and the electrodes which in turn can provide effective and advantageous sealing of tissue, and in particular may provide effective Transcollation® sealing of tissue.

With continued reference toFIG. 1, electrodes142aand142bare situated in an area generally centrally located with respect to the outer shaft opening134when inner shaft cutter141is in a downward position. This generally central location of the electrodes142a,142ballows for energy delivery at an optimal point of debridement. In other words, after inner shaft cutter141and outer shaft cutter132are rotated or oscillated relative to one another to cut tissue, rotating inner shaft cutter141to the downward position to expose electrodes142a,142band deliver energy through the electrodes142a,142bmay allow for hemostasis in an area generally central to where debridement or cutting of tissue had taken place. The generally centered electrodes142a,142ballow for energy to essentially travel or radiate outwardly from the electrodes142a,142bto coagulate the approximately the entire area of tissue previously cut. In other words, energy, and particularly RF energy may be provided at the center or near center of a portion of tissue previously cut or debrided.

FIGS. 8 and 9depict an alternative outer shaft130and inner shaft140whereby an outer shaft window or opening134ais essentially enlarged as compared to outer shaft window134(FIG. 2) via a proximal window portion138. This enlarged opening134amay afford an inner shaft140having significantly larger electrodes142c,142d, such as depicted inFIG. 9. Electrodes142c,142dmay be otherwise constructed similar to electrodes142aand142b(e.g.,FIG. 2) and the remaining portions of inner shaft140may be constructed as described above.

FIG. 10depicts a section of proximal assembly168of inner shaft140which section, when assembled in device100, is generally situated within button activation assembly200(FIG. 1). Electrodes142aand142bare shown as individual traces separated by proximal assembly shaft component169, which isolates the electrode traces142a,142bfrom one another. Electrodes142aincludes a proximal portion comprising a partial ring300extending at least partially circumferentially around proximal assembly shaft component169. Likewise electrode142bcomprises a proximal portion comprising a ring301which may extend fully circumferentially around proximal assembly shaft component169as depicted inFIG. 10. Rings300and301provide contact surface area for electrical contacts such as clips216a,216b(FIGS. 12,14).

FIGS. 11-14depict the button activation assembly200and the way in which energy provided to electrodes142a,142b.FIG. 11shows a partial cutaway view of the button activation assembly200one housing half204b(FIG. 12) removed such that only housing half204ais shown leaving portions of the button activation assembly200exposed. As shown inFIG. 11, at the proximal end region110of device100is provided a fluid housing156connected to the fluid connector150and an electrical contact housing210connected to the power source connector160. The power source connector160is in turn coupled to a power cord or cable161comprising wires161a,161band161c. Power cord161is coupled to a printed circuit board (PCB)206via wires161a,161band161c. In addition, electrical contacts164and166electrically couple the power cord to caps208aand208b, as further explained with reference topFIGS. 12-14.

FIG. 12shows and exploded view of the button activation cell200ofFIG. 11as well as a portion of proximal end region110with portions of the button activation cell removed.FIG. 13shows an enlarged view of the portion of proximal end region110shown inFIG. 13with still further portions removed. With reference betweenFIGS. 12-14,FIG. 12shows two housing halves204aand204bwhich may be attached via any attachment device such as screws400and may, as described above, house various components of the button activation cell200as well as the fluid housing, electrical contact housing210and clip housing220. Also depicted inFIG. 12are o-rings158a,15bare adjacent fluid housing156and an o-ring228which is adjacent housing220for sealing fluid from the various components, including the electrical components provided in electrical contact housing210.

Clip housing220, shown alone or apart from cell200inFIG. 12, comprises two windows224a,224b. Clips216aand216bare provided in windows224a,224bwith a flag218a,218bof each clip216aand216bviewable through or adjacent to windows224a,224b, such as depicted in assembled form inFIG. 13. Attached to clip housing220are two retaining rings222a,222b, for retaining the clips216aand216bin housing220. As best seen inFIG. 14, post connectors214a,214bare coupled to clip flags218a,218band provided on post connectors214a,214bare springs212a,212b. Over post connectors214a,214band springs212a,212bare provided caps208a,208b. Also as best seen inFIG. 14, clips216aand216bare coupled to an in contact with rings300and301respectively of electrode traces142a,142b. Clips216a,216b, post connectors214a,b, springs212a,212band caps208a,208bare made of an electrically conductive material and provide electrical contact of the caps208a,208bto rings300and301when a source of power is activated or applied at caps208a,208b. As seen inFIGS. 11 and 12, the caps208a,208bare provided under the PCB206, over which is provided button202. Depressing button202drives a button contact assembly203which in turn moves to close circuitry of the PCB206allowing a pathway for current to flow from the power source162thus providing power to the electrodes142a,142bthrough the clips216a,216bas described above.

When energy is activated or applied to clips216a,216b, due to the intimate contact of clips216aand216bwith electrode rings300and301, electrical communication with bipolar electrodes142a,142bis achieved whereby energy is delivered along electrode traces142aand142bto the distal end120of device100and is applied to a targeted area of tissue as described herein above. This aspect of the present disclosure integrates electrodes142aand142bto the inner shaft140while isolating the inner shaft and electrodes142aand142bfrom other components and while distributing the required power to two separate and distinct electrodes142a,142b. This design also minimizes the number of layers required to make the distal end120of the device.

FIG. 15is a top view of the button activation assembly200and depicts an alignment fiducial420through a window430in housing204. Alignment fiducial420is provided on housing221(FIG. 13). The alignment fiducial420is one of two fiducials which may be provided on device100, with the second fiducial not shown. Alignment fiducials (e.g.,420) are provided as indicators of alignment of inner cutter141and may be colored to indicate a particular alignment configuration.

Various modifications and alterations to this disclosure will become apparent to those skilled in the art without departing from the scope and spirit of this disclosure. It should be understood that this disclosure is not intended to be unduly limited by the illustrative embodiments and examples set forth herein and that such examples and embodiments are presented by way of example only with the scope of the disclosure intended to be limited only by the claims set forth herein as follows.