Patent Description:
Surgical access systems such as trocar systems as disclosed for example in US patent application publication number <CIT>, facilitate minimally invasive surgery across a body wall and within a body cavity. For example, in abdominal surgery, trocars provide a working channel across the abdominal wall to facilitate the use of instruments within the abdominal cavity. Trocar systems typically include a can nula, which provides the working channel, and an obturator that is used to place the cannula across a body wall, such as the abdominal wall. The obturator is inserted into the working channel of the cannula and pushed through the body wall with a penetration force of sufficient magnitude to result in penetration of the body wall. Alternatively, the cannula with an obturator is passed through an incision formed by the "Hasson," or cut-down, technique, which includes incremental incisions through the body wall until the body wall is incised through its entire thickness. Once the cannula has traversed the body wall, the obturator can be removed.

With the cannula in place in the body wall, various instruments may be inserted through the cannula into the body cavity. One or more cannulae may be used during a procedure. During the procedure, the surgeon manipulates the instruments in the cannulae, sometimes using more than one instrument at a time. The manipulation of an instrument by a surgeon may cause frictional forces between the instrument and the cannula in which the instrument is inserted. These frictional forces may result in movement of the cannula in an inward or outward direction within the body wall. If the cannula is not fixed in place, the proximal or distal motions of the instruments through the cannula may potentially cause the cannula to slip out of the body wall or to protrude further into the body cavity, possibly leading to injury to the patient.

The surfaces of the cannula associated with a trocar are generally smooth. The smoothness of a cannula surface makes placement of the cannula through a body wall relatively easy and safe. However, a smooth cannula may not have the desired retention characteristics once the cannula has been placed through a body wall. This smoothness and ease of placement may present problems as instruments and specimens are removed from a body cavity through the cannula and the associated seal systems of the trocar. It is highly desirable for a cannula to remain fixed in an appropriate position once placed. Additionally, if the Hasson technique is used, the incision may be larger than the cannula that may be placed through the incision. Therefore, it is desirable to provide a means to seal the incision site after the cannula has been inserted in order to insufflate a patient.

Various solutions to the issue of trocar-cannula fixation or stabilization have been attempted. These attempts include an inflatable balloon attached to the distal portion of the cannula with a thick foam bolster proximal to the insertion point into the body wall, raised threads or raised rings associated with the outer surface of the cannula, mechanically deployable enlarging portions arranged at the distal end of a cannula and suture loops or hooks associated with the proximal end of the trocar. These attempts have provided some degree of fixation or stabilization, but they have often led to cannulae having a relatively large outside diameter. Further, the thick foam bolster associated with balloon trocars has reduced the usable length of the cannula. There remains a need for a cannula fixation or stabilization device that includes a sleeve having retention means that minimize the increase in diameter. Additionally, the cannula fixation or stabilization device may include a lower profile and increase the working length of the cannula.

Methods for achieving the above comprise inflatable toroidal balloons that are sized larger than the cannula associated with the access device and usually disposed at or toward the distal end thereof. During insertion of the access channel through a body wall, the balloon is deflated. The balloon is inflated when the access channel is within the body cavity and properly placed. Most of the balloons associated with access devices are distensible or made of an elastic material. In some cases the balloons are made of a non-distensible or non-elastic material.

According to the present invention there is provided a cannula assembly as recited in Claim <NUM>. Dependent claims disclose embodiments. No surgical methods are claimed per-se. A cannula assembly, in various embodiments in accordance with the present invention, can be used in general, abdominal, gynecological and thoracic minimally invasive surgical procedures to establish a path of entry or to gain access through the tissue planes and/or potential spaces for endoscopic instruments. In various embodiments, a balloon trocar comprises an inflatable balloon at the distal end of a trocar cannula and a bolster toward the proximal end of the cannula. To use the balloon trocar, a surgeon inserts the balloon trocar into the body cavity such that the balloon section of the cannula is within the cavity, e.g., for abdominal surgery, beyond the peritoneal lining and within the abdominal cavity. The balloon is inflated and the bolster located toward the proximal end of the cannula is moved distally along the length of the cannula in order to compress the balloon against the inside of the body wall and seal the incision. With the bolster against the outer surface of the body wall, the balloon is maintained in compression against the inner surface of the body wall. In this manner, a seal is created between the balloon and the body wall, thereby allowing a surgeon to insufflate a patient. The balloon may remain inflated during the duration of a laparoscopic surgery, which may last up to four hours or more.

An elastic balloon is formed as a small inflatable structure. When deflated, an elastic balloon assumes a natural "low-profile" condition and conforms to the outer surface of the access channel or cannula. A non-elastic balloon is formed to assume a preferred maximum size and shape in a natural condition. Therefore, there exists a surplus of non-elastic balloon material when the balloon is deflated. As such, non-elastic balloon structures associated with an access channel that closely conforms to the exterior of the access channel and minimizes the interference between the deflated balloon and the tissue of a body wall during the insertion of the access device are desirable.

In accordance with various embodiments, a balloon trocar is provided in which the balloon or retention component reduces insertion force of the balloon trocar. In one embodiment, a balloon or expandable membrane positioned on or near the distal end of the cannula of the trocar is void or without or having little air within the balloon and is folded proximally or away from the direction in which the trocar is to be inserted into the body cavity. The evacuation of air and folding of the balloon reduces resistance and the insertion force used to insert the cannula within the body cavity without reducing balloon strength to maintain retention by the balloon and integrity of the seal and the balloon itself. Additionally, such a balloon permits the utilization of a reduced insertion force relative to the insertion force of a non-folded balloon. A reduced insertion force permits a more controlled entry of the trocar into the body cavity. A more controlled entry reduces inadvertent and undesirable contact with organs, tissue, other inserted devices or ports within the body cavity. Also, a reduced insertion force reduces potential trauma to the incision or entry site as less force is applied to the site as the trocar is being inserted into the body cavity.

In various embodiments, an access channel or cannula that is associated with a surgical access device or trocar is provided. The cannula is sized and configured to receive a retention and stabilizing balloon along the distal portion. A non-elastic balloon made of polyolefin, nylon, polyester, polyethylene or the like is placed along a location upon the cannula. The deflated non-elastic balloon is maintained in the lowest profile condition for insertion through a body wall. The balloon conforms very closely the profile of the cannula. A folded balloon condition is maintained.

In certain embodiments, a cannula assembly is provided. The cannula assembly comprises a cannula and a sleeve. The cannula has a proximal end, a distal end opposite the proximal end, and a lumen extending from the proximal end to the distal end along a longitudinal axis. The lumen is configured to receive a surgical instrument therein. The cannula comprises a generally tubular cannula body and an annular recess. The generally tubular cannula body has an exterior surface and a first outer diameter. The annular recess is formed in the exterior surface of the cannula body adjacent the distal end of the cannula. The annular recess is transverse to the longitudinal axis. The annular recess has a second outer diameter smaller than the first outer diameter of the cannula body. The sleeve has a proximal end and a distal end. The sleeve is disposed around the cannula from adjacent the proximal end of the cannula to the annular recess. The sleeve comprises an elongate tubular body and a balloon positioned distal the elongate tubular body. In some embodiments, the sleeve further comprises a chamfered leading edge at the distal end of the sleeve. In some embodiments, the annular recess has a textured surface adapted to receive an adhesive. In some embodiments, the cannula assembly further comprises a conditioning aid removably disposed around the balloon. The conditioning aid is sized to compress the balloon proximally along the exterior surface of the generally tubular cannula body in a snug fit defining a low diameter insertion profile.

In certain embodiments, a method of making a cannula assembly having an inflatable balloon is provided. The method comprises positioning a generally tubular sleeve over a cannula, bonding the sleeve to the cannula, locally heating a predetermined length of the tubular sleeve, applying an source of inflation fluid to the tubular sleeve to form a balloon, and conditioning the balloon to constrict against the cannula. The generally tubular sleeve has a proximal end and a distal end. The cannula has a proximal end and a distal end and comprises an elongate cannula body with an annular groove formed in the cannula body at the distal end of the cannula. Bonding the sleeve to the cannula comprises bonding the proximal end and the distal end of the sleeve to the cannula. Locally heating the tubular sleeve comprises locally heating a predetermined length of the tubular sleeve adjacent the distal end of the tubular sleeve. The balloon is formed adjacent the distal end of the tubular sleeve. After forming the balloon and while the balloon retains residual heat from the local heating, the balloon is conditioned to constrict against the cannula.

With reference to <FIG> and <FIG>, a typical laparoscopic procedure is illustrated where a plurality of trocars <NUM> are placed through a body wall <NUM>, such as an abdominal wall, and into a body cavity <NUM>, such as an abdominal cavity. The body cavity <NUM> is insufflated, or inflated with gas, to distend the body wall <NUM> and provide a working space for the laparoscopic procedure. The trocars <NUM> each include a cannula <NUM> and a seal <NUM>. Positive pressure is maintained within the body cavity <NUM> by the seal <NUM> associated with the cannula <NUM>. In addition, the cannula <NUM> must form a gas-tight seal against adjacent tissue. If positive pressure is lost, either through the seal <NUM> associated with the cannula <NUM> or the seal between the cannula and the adjacent tissue, the procedure may be compromised.

As the body cavity <NUM> is inflated, the body wall <NUM> may be greatly distended. The access sites may tend to enlarge under the distention of the body wall <NUM> and compromise the positioning and sealing of the cannula <NUM>. As stated above, the manipulation of instruments <NUM> used through the trocars <NUM> may result in movement of the cannulae <NUM> in either a proximal or distal direction within the access site through the body wall <NUM>. As this occurs, some liquefaction may take place and the preferred relationship between the cannula <NUM> and the body tissue may be compromised.

Referring now to <FIG>, a typical assembled trocar <NUM> is shown having a cannula <NUM>, a seal housing <NUM> and an obturator <NUM>. The cannula <NUM> typically has a smooth exterior surface <NUM> so that it may be inserted through the body wall <NUM> easily. The seal housing <NUM> contains a seal system that prevents retrograde gas-flow. The obturator <NUM> is a cutting or piercing instrument that creates the pathway through the body wall <NUM> through which the cannula <NUM> follows. Surgical obturators <NUM> are generally sized and configured to create a defect in tissue that is appropriate for the associated cannula <NUM>. However, the defect may have a tendency to enlarge during a surgical procedure as the trocar <NUM> or cannula <NUM> is manipulated. As an instrument <NUM> is urged distally and proximally, or inserted and withdrawn, the cannula <NUM> may move or even be inadvertently withdrawn due to the friction between the instrument <NUM> and the seal <NUM> of the trocar housing.

With specific reference to <FIG>, a trocar <NUM> or access device is shown where the outer surface <NUM> of the cannula <NUM> includes a plurality of raised features <NUM>. These raised features <NUM> are sized and configured to increase resistance to proximal and distal motion as instruments <NUM> are maneuvered, and especially as specimens are removed, through the trocar <NUM>. The prior art includes either sequential raised rings or a raised coarse-thread <NUM>. While the rings or threads <NUM> of the prior art may stabilize the cannula <NUM> to some degree, they do not necessarily seal the cannula <NUM> against the adjacent tissue of a body wall <NUM>. There may be gas loss associated with the use of these systems. The raised rings or threads <NUM> also increase the insertion force required to penetrate a body wall <NUM>. The insertion force may be reduced in the instance of a continuous coarse thread <NUM> in comparison to a sequence of discrete raised rings or features as a threaded cannula <NUM> may actually be "screwed" into the tissue defect in accordance with the thread direction and pitch, rather than pushed through without appropriate rotation.

With reference to <FIG>, a surgical access device <NUM> according to prior art includes a cannula <NUM> having an inflatable balloon <NUM> associated with the distal-end portion <NUM> of the cannula. The balloon <NUM> is sized and configured to fit snugly around the cannula <NUM> in the uninflated condition. The balloon <NUM> is inflated after the cannula <NUM> is properly placed through the body wall <NUM> and into the body cavity <NUM>. The balloon <NUM> is generally held against the interior surface <NUM> of the body wall <NUM> by a counter-force that is associated with a sliding counter-force member, such as a foam bolster <NUM>. The bolster <NUM> is associated with the proximal portion of the cannula <NUM>. The balloons <NUM> associated with the devices of the prior art are typically "thick-walled" structures constructed as part of the cannula <NUM>. The balloon <NUM> is generally bonded to the distal-end portion <NUM> of the cannula <NUM> and an inflation channel or lumen is provided within the wall of the cannula <NUM>.

With reference to <FIG>, an embodiment of trocar cannula assembly <NUM> having advanced fixation features is illustrated. The trocar cannula assembly <NUM> can include a seal housing <NUM> and a sleeve sub assembly <NUM> comprising a trocar cannula <NUM>, a sleeve <NUM> including an inflatable balloon <NUM>, a retention disc <NUM>, and a tip protector <NUM> or conditioning aid. Various aspects described herein with respect to certain embodiments of trocar cannula assembly can be used in either balloon cannulae or retention cannulae.

With continued reference to <FIG>, the seal housing <NUM> or valve housing can include an instrument seal and a zero seal. In some embodiments, the valve housing can be removably coupled to the cannula <NUM> and in one embodiment includes an inlet for supplying insufflation gas into a body cavity such as the abdominal cavity. The instrument seal and zero seal enclosed in the valve housing in various embodiments can be separate or monolithic seals. The zero seal and instrument seal can seal an instrument path through the valve housing into a lumen <NUM> (<FIG>) of the cannula <NUM>. In other embodiments, the trocar cannula <NUM> can have an instrument seal and a zero seal, separate or monolithic seals, positioned directly therein with no separate valve housing such that the trocar cannula with a sealed instrument channel path has a relatively short length from a proximal end to the distal end defining a low height profile.

In certain embodiments, the trocar cannula assembly <NUM> can be sized to receive surgical instruments such as laparoscopic surgical tools having standard sizes. For example, the trocar assembly <NUM> can be a "<NUM> trocar cannula," sized and configured to receive surgical tools from sized up to a <NUM> surgical tool product class. In other embodiments, a trocar assembly <NUM> can be an "<NUM> trocar cannula" or a "<NUM> trocar cannula," sized and configured to receive surgical tools sized as large as an <NUM> or <NUM> surgical tool product class respectively. In some embodiments, the trocar cannula assembly <NUM> can be included in a kit comprising the trocar cannula assembly <NUM>, a seal housing <NUM> and an obturator insertable through the seal housing <NUM> and the cannula assembly <NUM>.

With reference to <FIG>, the trocar cannula <NUM> can include a fluid inlet port <NUM>. The fluid inlet port <NUM> is adapted to receive a source of fluid such as a syringe. The fluid can comprise air, another gas such as carbon dioxide, a gas mixture, or a liquid such as water, a saline solution, or another liquid solution. As further discussed herein, the fluid inlet port <NUM> is fluidly coupled to the sleeve <NUM> such that addition of fluid to the fluid inlet port <NUM> inflates the balloon <NUM>.

In some embodiments, the fluid inlet port <NUM> can include a one-way valve such as a poppet valve or check valve <NUM>. Once fluid is added to the fluid inlet port <NUM> through the check valve <NUM>, the check valve <NUM> maintains the fluid within the sleeve <NUM> and balloon <NUM> of the trocar cannula assembly <NUM>. The check valve <NUM> can be selectively opened to allow the fluid to escape or be withdrawn such as by syringe when it is desired to deflate the balloon <NUM>.

With reference to <FIG>, the trocar cannula <NUM> has a proximal end <NUM>, a distal end <NUM>, and a lumen <NUM> extending from the proximal end <NUM> to the distal end <NUM> along a longitudinal axis L. The lumen <NUM> is configured to receive a surgical instrument therein such as a laparoscopic surgical tool.

With continued reference to <FIG>, the trocar cannula <NUM> comprises a seal housing interface <NUM> at the proximal end <NUM>, the fluid inlet port <NUM> distal the seal housing interface <NUM>, a generally tubular cannula body <NUM> extending distally from the fluid inlet port <NUM>, an annular recess such as an annular groove <NUM> in the cannula body <NUM> adjacent the distal end <NUM> of the cannula <NUM>, and a distal tip <NUM>. The seal housing interface <NUM> can comprise a seal such as an O-ring <NUM> (<FIG>) to sealingly engage a seal housing.

In the illustrated embodiments, the fluid inlet port <NUM> comprises a fluid inlet <NUM> and a fluid dome <NUM>. The fluid inlet <NUM> is configured to receive the source of inflation fluid and can include the check valve <NUM> positioned therein (<FIG>).

As illustrated, the fluid dome <NUM> of the fluid inlet port <NUM> is fluidly coupled to the fluid inlet <NUM>. In some embodiments, the fluid inlet port <NUM> can have a generally smooth outer surface <NUM>. The smooth outer surface <NUM> can allow adhesive to flow underneath the sleeve <NUM> and obtain a relatively strong balloon-to-cannula bond. In some embodiments, the fluid inlet port <NUM> can be shaped with a curved profile such as a generally teardrop shape and the fluid dome <NUM> can have a curved profile to reduce the likelihood of the fluid pathway for balloon inflation/deflation can become plugged. In other embodiments, the fluid inlet port <NUM> can have another curved profile such as a generally cylindrical, elliptical, or oval profile. In other embodiments, the fluid inlet port <NUM> can have another curvilinear profile.

With continued reference to <FIG>, the cannula body <NUM> extends distally from the fluid inlet port <NUM> to the distal end <NUM> of the cannula <NUM>. The cannula body <NUM> has an exterior surface <NUM> and a first outer diameter D1. The exterior surface <NUM> of the cannula body <NUM> is configured to facilitate installation of the sleeve <NUM> thereon. For example, the exterior surface <NUM> of the cannula body <NUM> can include a relatively lightly textured surface finish to facilitate sliding advancement of the sleeve <NUM> over the cannula body <NUM>.

In some embodiments, the cannula body <NUM> can include one or more fluid channels <NUM> or grooves that extend generally longitudinally from the fluid inlet port <NUM> towards the distal end <NUM> of the cannula <NUM>. The fluid channel <NUM> can be formed in the exterior surface <NUM> of the cannula body <NUM> and extend a depth d into the cannula body <NUM>. As illustrated, the fluid channel <NUM> is fluidly coupled to the fluid inlet port <NUM> and extends distally to a location adjacent the balloon <NUM> of the sleeve <NUM>. The fluid channel <NUM> can thus work in conjunction with the balloon <NUM> to allow fluid passage for balloon <NUM> inflation and deflation. Advantageously, with the fluid channel <NUM> embedded in the cannula body <NUM>, the sleeve sub-assembly <NUM> can have a relatively small outer diameter and low-profile. Desirably, with a relatively small diameter and low-profile, the cannula assembly <NUM> can have a relatively low insertion force. Similarly, the balloon <NUM> and fluid channel <NUM> geometry can reduce the incidence of the balloon <NUM> plugging the fluid flow path during deflation.

With continued reference to <FIG>, the cannula body <NUM> includes an annular recess such as an annular groove <NUM> adjacent the distal end of the trocar cannula <NUM>. The annular groove <NUM> is formed in the cannula body <NUM> at an orientation generally perpendicular to the longitudinal axis L of the trocar cannula <NUM>. The annular recess comprises an annular groove <NUM> having a recessed surface extending a relatively short length along the longitudinal axis L of the trocar cannula <NUM> adjacent the distal end of the trocar cannula <NUM>.

<FIG> illustrates a cut away detail view of an embodiment of annular groove <NUM>. The annular groove <NUM> has a proximal edge <NUM>, a distal edge <NUM>, and an annular interface surface <NUM> between the proximal edge <NUM> and the distal edge <NUM>. The annular interface surface <NUM> has a second outer diameter D2 smaller than the first outer diameter D1 of the cannula body <NUM>. The proximal edge <NUM> can have a generally stepped edge extending between the first outer diameter D1 of the cannula body <NUM> and the second outer diameter D2 of the annular interface surface <NUM>. Desirably, the stepped edge can enhance sealing performance of the sleeve <NUM> to the cannula body <NUM> to maintain fluid within the balloon <NUM> in an inflated configuration.

With continued reference to <FIG>, in some embodiments, the distal edge <NUM> of the annular groove <NUM> can have a ramped edge. The ramped edge can extend at an angle transverse to the annular interface surface <NUM>. In other embodiments, the distal edge <NUM> of the annular groove <NUM> can comprise a generally stepped edge or an edge having another geometric profile such as a radiused curvilinear edge.

With reference to <FIG>, in some embodiments, the distal tip <NUM> at the distal end <NUM> of the cannula <NUM> has a distal edge <NUM> that extends at an angle θ relative to a plane perpendicular to the longitudinal axis L of the cannula <NUM>. The angle θ can be between about <NUM> degrees and about <NUM> degrees. In some embodiments, of cannula assembly <NUM> having a <NUM> size, the distal edge <NUM> of the distal tip <NUM> can be angled at approximately <NUM> degrees relative to the plane perpendicular to the longitudinal axis L. In embodiments of cannula assembly <NUM> having other sizes, for example <NUM> and <NUM> cannulae, the angle can be slightly different to match the correlated cannulae <NUM>. For example, in some embodiments of <NUM> cannula assembly, the angle θ can be approximately <NUM> degrees, and in some embodiments of <NUM> cannula assembly, the angle θ can be approximately <NUM> degrees. In other embodiments of cannula assembly <NUM> other angles can be used.

Advantageously, the angled distal tip <NUM> can greatly reduce the force required to insert the cannula assembly <NUM> through a body wall such as the patient's abdominal wall as compared with a distal tip having a straight tip with a distal edge perpendicular to the longitudinal axis of the cannula. Balloon trocars having straight tips have primarily been introduced through body walls into surgical sites through relatively large incisions using a cut-down technique. Desirably, the angled distal tip <NUM> can facilitate the use of a fixation cannula in surgical procedures including various cannula insertion techniques with various incision lengths. For example, a fixation trocar having an angled distal tip can be inserted with a relatively low insertion force with insertion techniques including insertion techniques with bladed, non-bladed optical, or insufflation obturators.

In some embodiments, the cannula body <NUM> can be formed of a polycarbonate material. Desirably, the hardness and relative rigidity of the material allows the cannula <NUM> to serve as a supporting tube to install the flexible sleeve <NUM> and balloon <NUM> and a port to insert obturators or other medical instruments. In other embodiments, the cannula body <NUM> can comprise other materials, such as, for example polyester materials.

The sleeve <NUM> extends from adjacent the proximal end of the trocar cannula to adjacent the annular groove <NUM>. The sleeve has a proximal end and a distal end with an inflatable segment adjacent the distal end. The sleeve can be coupled to the trocar cannula at the proximal end of the sleeve and the distal end of the sleeve.

The sleeve can be coupled to the trocar cannula by a technique that creates a relatively low diametric profile at the coupling, has desirable sealing performance, and can be efficiently manufactured. For example, in some embodiments, the trocar cannula can have a substantially smooth continuous outer surface, and the sleeve can be coupled to the smooth surface by application of an adhesive to form a chemical bond. In other embodiments, the sleeve can be coupled to the trocar cannula by heat welding or UV welding to create a fused coupled region. As further discussed with respect to <FIG>, the sleeve is coupled to the trocar cannula at a noncontinuous region of the outer surface, at an annular groove formed therein. In some embodiments, different coupling techniques can be used at the proximal end of the sleeve than are used at the distal end, while in other embodiments, substantially similar coupling techniques can be used at the proximal end and the distal end of the sleeve.

With reference to <FIG>, an embodiment of sleeve <NUM> and cannula assembly <NUM> is illustrated. The sleeve <NUM> comprises a proximal interface section <NUM> or coupler at the proximal end <NUM>, an elongate tubular body <NUM> extending distally from the coupler, a balloon <NUM> positioned distal the elongate tubular body <NUM>, and a bonding segment <NUM> (see <FIG>) distal the balloon.

In some embodiments, the sleeve <NUM> can be monolithically unitarily formed, such as by stretch blow molding. Advantageously, the stretch-blow molding process allows for a high degree of control of the balloon material, thickness and shape.

The sleeve <NUM> can comprise a polyolefin material such as one commonly used as heat shrink tubing. In certain embodiments, a Sumitomo A2 clear polyolefin tubing can be used. Advantageously, a sleeve <NUM> comprising a polyolefin material, is latex free, non-porous, and non-fragmenting, unlike latex or silicone rubber materials. Desirably, the polyolefin tubing material can be soft, flexible, and can include a high degree of cross-linking such that it has a relatively high strength for a given material thickness compared to other tested materials. In embodiments of cannula assembly <NUM> having a polyolefin sleeve <NUM>, despite having an incredibly thin balloon section, the balloon <NUM> can typically be over-inflated with an average of <NUM> times of a designed inflation pressure without rupturing. Also, the softness and flexibility of the polyolefin material improves the feel of the device for the user while also reducing the insertion force. In other embodiments the sleeve can comprise other materials such as a silicone material, cilran, polyisoprene, a polyurethane material, a polyurethane blend, TYGON®, VITON®, SANTOPRENE®, MYLAR®, or another suitable polymeric material.

The cannula assembly includes one balloon <NUM> positioned at a distal location on the cannula <NUM>. It is contemplated that in various other embodiments, additional balloons can be incorporated to account for variations in a patient's abdominal wall thickness and anatomy. Also, balloons at different locations may use different material. The balloon may be distensible or non-distensible or a combination of both. The balloon <NUM> in one embodiment is doughnut shaped or in one aspect disc-like. The size of the balloon <NUM> can vary to vary the desired retention of the trocar cannula <NUM> with the patient's body.

With continued reference to <FIG>, the coupler <NUM> is sized and configured to engage the cannula <NUM>. For example, in the illustrated embodiment, the coupler <NUM> has a curved profile in an eccentric or generally teardrop shape to match the teardrop shape of the fluid dome <NUM> of the cannula <NUM>. Advantageously, this matching profile can allow a tight fit when the sleeve <NUM> is installed on to the cannula <NUM>, reducing the potential for leakage therebetween.

In some embodiments, an outer surface of the coupler at the proximal end <NUM> is textured. The rough surface facilitates the bonding of adhesives to the sleeve <NUM>, preventing the sleeve <NUM> from being separated from the cannula <NUM> when the balloon <NUM> is fully inflated. For example, a roughened or textured surface can create a plurality of relatively small channels which enhance flow of a chemical adhesive though a wicking or capillary action process to create a strong adhesive bond between the sleeve <NUM> and the cannula <NUM>. Desirably, a textured or roughened surface at the coupler can allow the sleeve <NUM> to comprise a material that can be otherwise difficult to bond with adhesives.

With continued reference to <FIG>, the elongate tubular body <NUM> or shaft of the sleeve <NUM> extends distally from the coupler <NUM>. The shaft is uniform and thin-walled, but thick enough to withstand sliding movement of a retention disc <NUM> or other bolster.

<FIG> illustrates a distal end of the cannula assembly <NUM> with the sleeve <NUM> positioned on the cannula <NUM>. Advantageously, a sleeve <NUM> formed by a stretch blow molding process can allow for increased control of the thickness t1 of the elongate tubular body <NUM> to minimize an outer diameter of the trocar cannula assembly <NUM> resulting in a smaller incision size for the patient. In some embodiments, the elongate tubular body <NUM> can have a thickness t1 of approximately <NUM> (<NUM> inches) to approximately <NUM> (<NUM> inches).

With continued reference to <FIG>, as illustrated, the sleeve <NUM> comprises a non-distensible inflatable balloon <NUM> distal of the elongate tubular body <NUM>. The balloon <NUM> can have a thickness t2 that is smaller than the thickness t1 of the elongate tubular body <NUM>. Advantageously, stretch blow molding a polyolefin material to form the balloon <NUM> can provide a high strength material with a relatively low thickness. In some embodiments, the balloon can have a thickness between about <NUM> (<NUM> inches) and <NUM> (<NUM> inches). In certain embodiments, the balloon can have a thickness of approximately <NUM> (<NUM> inch).

Advantageously, abrupt thickness transitions at the balloon/shaft interfaces can be significantly reduced or eliminated through the stretch blow molding process. Desirably, the relatively high degree of control in the balloon thickness of the stretch blow molding process can also contribute to a minimized outer diameter adjacent the distal end of the cannula assembly, resulting in a reduction in insertion force.

With reference to <FIG>, the sleeve <NUM> can have a chamfered leading edge <NUM> at the distal end thereof. Desirably, the angle of the chamfered leading edge <NUM> with respect to a longitudinal axis of the bonding segment <NUM> can be chosen to provide a smooth transition between the distal end of the cannula and the distal end of the sleeve. With the bonding segment <NUM> positioned in the annular groove <NUM>, the longitudinal axis of the bonding segment is substantially parallel to the longitudinal axis of the cannula. Such a smooth transition can contribute to a reduction in insertion force for the trocar cannula assembly as compared with a trocar cannula assembly having a generally squared corner at the distal end. In some embodiments, the angle of the chamfered leading edge <NUM> can be between approximately <NUM> degrees and approximately <NUM> degrees relative to the longitudinal axis of the bonding segment <NUM>.

<FIG> and <FIG> illustrate a cut-away detail view of the distal end of the cannula assembly <NUM> with the sleeve <NUM> positioned on the cannula <NUM>. The outer surface <NUM> of the bonding segment <NUM> at the distal end <NUM> of the sleeve <NUM> is textured, providing a rough bonding surface to assist in the bonding of adhesives to the sleeve <NUM> by retaining adhesive and to promote flow of the adhesives between the sleeve and the cannula by wicking of adhesive through a capillary action process. In some embodiments, the annular interface surface <NUM> of the annular groove <NUM> is textured such as with small pits, grooves, or a roughened surface to assist in the bonding of the sleeve to the cannula. In some embodiments, a combination of cyanoacrylate instant adhesive and UV cure adhesive can be used for the sleeve-cannula bond coupling the bonding segment <NUM> to the annular groove <NUM>. In other embodiments, other adhesives, such as only a cyanoacrylate adhesive or only a UV cure adhesive, or another type of adhesive can be used. Desirably, the adhesive can be applied substantially within the annular groove <NUM> such that the distal end <NUM> of the cannula <NUM> can have a smooth low profile transition between the sleeve <NUM> and the cannula <NUM>. Advantageously, the low profile transition between the sleeve <NUM> and the cannula <NUM> can reduce the insertion force required to position the cannula assembly <NUM> in a surgical site.

In some embodiments, the low profile transition can be further enhanced by disposition of an adhesive <NUM> predominantly within the annular groove <NUM> of the cannula body <NUM>. The bonding segment <NUM> of the sleeve <NUM> and the annular groove <NUM> of the cannula <NUM> is sized and configured to facilitate the disposition of the adhesive <NUM> predominantly within the annular groove <NUM>. The annular surface of the annular groove has a first length l1 along the longitudinal axis of the cannula, the bonding segment has a second length l2 along the longitudinal axis of the cannula, and the second length is smaller than the first length. Thus, the annular interface surface <NUM> of the annular groove <NUM> comprises an engagement segment <NUM> and an exposed segment <NUM>. The engagement segment <NUM> is defined by the second length l2 and engaged by the bonding segment <NUM>. The exposed segment <NUM> is defined by a difference between the first length l1 and the second length l2. The exposed segment <NUM> can desirably be sized to provide a sufficient surface for disposition of a bead of adhesive to maintain the bonding segment <NUM> of the sleeve <NUM> with respect to the annular groove <NUM>. Thus, an adhesive <NUM> can be at least partially applied to the exposed segment <NUM> of the annular interface surface <NUM> to couple the bonding segment <NUM> to the annular groove <NUM>.

In some embodiments the sleeve <NUM> can be adhesively bonded to the cannula <NUM> at the proximal interface surface <NUM> or coupler with a combination of cyanoacrylate instant adhesive and UV cure adhesive similar to the adhesive bonding of the bonding segment <NUM> to the annular groove <NUM>. In other embodiments, other adhesives, such as only a cyanoacrylate adhesive or only a UV cure adhesive, or another type of adhesive can be used.

<FIG> illustrate a retention disc <NUM> for positioning on the cannula assembly <NUM>. In some embodiments, the cannula assembly <NUM> includes a proximal fixation member such as a retention disc <NUM> positioned proximal the balloon <NUM> around the elongate tubular body <NUM> of the sleeve <NUM>. After the trocar cannula assembly <NUM> is inserted through a body wall at a surgical site, the balloon <NUM> can be inflated to maintain the position of the trocar cannula assembly <NUM> in the surgical site, and the proximal fixation member or retention disc <NUM> can prevent the trocar cannula <NUM> from advancing further into the surgical site.

As illustrated in <FIG>, the retention disc <NUM> can comprise a generally circular disc with a center hole <NUM> defining a passage <NUM> through the retention disc <NUM>. The passage <NUM> of the center hole <NUM> can have a ribbed profile on an inner diameter. The ribbed profile can include a plurality of annular grooves <NUM>. The ribbed profile can frictionally engage an outer surface of the elongate tubular body <NUM> of the sleeve <NUM> such that the retention disc <NUM> is manually slidable along the sleeve <NUM> but tends to remain in a selected position.

In some embodiments, the retention disc <NUM> can be formed of an elastomeric polymer material such as a KRATON® material. A retention disc <NUM> formed of a KRATON® material can provide a desired level of frictional engagement with the outer surface of the sleeve <NUM> and present an ergonomically pleasing soft, flexible feel to a user of the trocar cannula. Advantageously, the round corners and soft material of the retention disc <NUM> provide an atraumatic means to hold the trocar in place. In some embodiments, the retention disc <NUM> can be formed by an injection molding process. Advantageously, embodiments of a trocar cannula having a single molded retention disc <NUM> can have manufacturing and assembly efficiencies and facilitate ease of use relative to a clamp mechanism having multiple assembled components.

In some embodiments, the trocar cannula assembly <NUM> can be configured to resist movement of the retention disc <NUM> proximally along the cannula body <NUM> to prevent the trocar cannula <NUM> from advancing further into the surgical site. For example, an exterior surface <NUM> of the cannula body <NUM> can have a slight taper such that it has a smaller outer diameter at the distal end relative to the outer diameter at the proximal end of the cannula body. Thus, a friction force generated by the frictional engagement between the retention disc <NUM> and the sleeve <NUM> can increase as the retention disc <NUM> is slid proximally along the trocar cannula <NUM>. The retention disc <NUM> can be used to fixate the trocar cannula <NUM> relative to a body wall. The tight fit, ribbed profile, and tapered cannula <NUM> prevent the retention disc <NUM> from advancing along the cannula body <NUM> when an instrument is inserted into the cannula <NUM>.

In some embodiments, a retention disc <NUM> comprising an elastomeric polymer material can exhibit creep when stored under tension. Advantageously, where the exterior surface <NUM> of the cannula body <NUM> includes a slight taper, before use the retention disc <NUM> can be positioned adjacent the distal end having a relatively small outer diameter when not in use to reduce the incidence of creep in the retention disc <NUM>. During use, the retention disk <NUM> is advanced proximally up the shaft of the cannula <NUM> to an area of larger cannula diameter, allowing placement and fixation of the disc <NUM>. Additionally, such a tapered cannula body <NUM> can have further advantages in manufacturability of the cannula body <NUM>. For example, such a tapered profile can facilitate release of the cannula body <NUM> from a mold in embodiments where the cannula body <NUM> is formed with an injection molding process.

In other embodiments, the cannula assembly <NUM> can comprise a bolster <NUM>' such as a generally cylindrical or conical stability member with a clamp mechanism. For example, in some embodiments the cannula assembly <NUM> can include a stability assembly including one of the various clamp mechanisms described in <CIT>.

With reference to <FIG>, in some embodiments, a trocar assembly <NUM> can include a conditioning aid <NUM> to constrict the balloon <NUM> relative to the body <NUM> and to protect the balloon <NUM> during shipping. Moreover, the required insertion force can be observed to vary proportionally with an overall outer diameter of the trocar cannula assembly <NUM> at the balloon <NUM>. Thus, before use, it can be desirable to reduce insertion force by folding the balloon <NUM> into an insertion configuration having a low diameter and relatively smooth transition from the distal tip <NUM> of the cannula <NUM> to the balloon <NUM>.

A non-elastic or non-distensible balloon <NUM> in a deflated or insertion configuration does not automatically conform to the exterior surface <NUM> of the cannula body <NUM>. In some embodiments, the material can have a tendency to wrinkle, form folds and/or creases and may project at various points away from the exterior surface <NUM> of the cannula body <NUM>. The irregularities that the un-inflated balloon may possess, can present resistance during insertion of the un-inflated retention balloon <NUM> through a body wall. Folding the balloon <NUM> into the insertion condition can reduce the force required for insertion. In some embodiments, in the insertion configuration the balloon <NUM> is folded along the cannula body <NUM> towards the proximal end <NUM> of the cannula <NUM>. Folding the balloon <NUM> towards the proximal end <NUM> can result in one or more folds in the balloon <NUM> in the insertion configuration. For example, in some embodiments, the balloon <NUM> can be folded proximally in a single step and in other embodiments, the balloon <NUM> can be initially folded distally in a first fold and subsequently folded proximally in a second fold. By folding the balloon <NUM> against the trocar placement direction, it helps reduce the insertion force and lower the balloon diametric profile. The conditioning aid <NUM> can maintain the balloon <NUM> in the insertion configuration until it is removed from the trocar cannula assembly <NUM> for insertion to a surgical site. Moreover, the conditioning aid <NUM> can protect the balloon <NUM> and/or distal tip <NUM> of the cannula assembly <NUM> from damage during shipping or prior to operational use.

Advantageously, a trocar cannula system can achieve have a reduced diameter and relatively low insertion force if the conditioning aid <NUM> is advanced over the balloon <NUM> to constrict the balloon <NUM> relative to the body <NUM> when the balloon is in a formable state. For example, as further discussed below with respect to <FIG>, with a stretch blow molded balloon, the conditioning aid <NUM> can be advanced over the balloon <NUM> when the balloon retains residual heat. The duration of the formable state can vary based on the material used and the thickness of the balloon <NUM>. Accordingly, it can be desirable to monitor the temperature of the balloon material and/or the elapsed time from the formation of the balloon to ensure application of the conditioning aid <NUM> while the balloon <NUM> is in the formable state. The conditioning aid <NUM> can thus constrict the formed balloon <NUM> against the cannula as it cools. Advantageously, constricting the balloon <NUM> against the cannula body while the balloon <NUM> is in a formable state can achieve a lower outer diameter relative to folding an equivalent previously-formed balloon against the cannula body. Moreover, further significant reductions in insertion force can be observed if the balloon <NUM> is folded in a two-step process (with an initial distal tuck or fold followed by a second distal fold) while the balloon retains residual heat and before positioning of the conditioning aid <NUM> on the cannula body.

<FIG> illustrates a conditioning aid <NUM> comprising a hollow tubular segment. In the illustrated embodiment, the conditioning aid <NUM> comprises a section of tubing having an interior surface <NUM> with an inner diameter. The inner diameter of the interior surface <NUM> is sized to provide a snug fit over the folded balloon <NUM> of the trocar cannula assembly. The illustrated tubular segment conditioning aid <NUM> is a relatively simple construction which can desirably provide certain manufacturing and assembly efficiencies. In other embodiments, conditioning aids can take on many forms such as, for example, shrink tubing, a cap, a cone or a coil of appropriate inside diameter. In certain embodiments, the conditioning aid can be made from a variety of materials, including, for example, thermoplastics, thermosets, metals and glass. In some embodiments, the conditioning aid can be generally conical or can include a tapered interior surface to facilitate removal prior to use. Desirably, the conditioning aid can have a smooth interior surface to optimize conditioning and prevent damage to the balloon.

In one embodiment, It can be desired that the conditioning aid <NUM> is configured to prevent proximal movement of the conditioning aid <NUM> past the balloon <NUM>. In some embodiments, the conditioning aid <NUM> is shaped to have a somewhat smaller diameter at a distal end than at a proximal end to prevent the conditioning aid <NUM> from moving proximally and past the balloon <NUM> to maintain the conditioning aid <NUM> on the balloon <NUM>. In other embodiments, the conditioning aid <NUM> may have detents or projections that prevent the conditioning aid <NUM> from moving proximally. In some embodiments, the cannula assembly <NUM> can further comprise a spacer between the retention disk <NUM> or bolster <NUM>' and the conditioning aid <NUM> to prevent the conditioning aid <NUM> from moving proximally past the balloon <NUM>. The retention disk <NUM> or bolster <NUM>' in one embodiment is positioned near the balloon <NUM> or the conditioning aid <NUM> is sufficiently long to contact the retention disk <NUM> or bolster <NUM>' to prevent the conditioning aid <NUM> from moving proximally past the balloon <NUM>. Preventing the conditioning aid <NUM> from moving proximally past the balloon <NUM> prevents the conditioning aid <NUM> from losing contact with the balloon <NUM> losing pressure and protection of the balloon <NUM> and tip <NUM>.

<FIG> illustrate various methods for manufacture of trocars described herein. Embodiments of cannula assembly <NUM> discussed herein can include a preformed sleeve <NUM>. In some embodiments, the cannula <NUM> can be formed from a suitable material, such as a polycarbonate or polyester material, with an injection molding process.

With reference to <FIG>, a method of making a cannula assembly <NUM> is illustrated. A roll of polyolefin heat-shrink tubing is cut into sections or blanks then heated to shrink the tubing down to an installation size slightly larger than the cannula <NUM>. The sleeve <NUM> can then be positioned <NUM> over the cannula <NUM>. Once the slightly oversized sleeve <NUM> is installed on the cannula <NUM>, the sleeve <NUM> can be heated <NUM> to shrink onto the exterior surface <NUM> of the cannula body <NUM>. For example, the elongate tubular body <NUM> of the sleeve can be formed line-to-line for installation and then heated slightly to shrink down onto the exterior surface <NUM> of the cannula body <NUM>. The sleeve <NUM> is positioned <NUM> over the cannula <NUM>. The sleeve <NUM> can be advanced until the proximal interface section <NUM> of the sleeve <NUM> is positioned about a fluid inlet port <NUM> of the cannula <NUM> and the bonding segment <NUM> of the sleeve <NUM> is positioned <NUM> in the annular groove <NUM>.

With reference to <FIG>, once the sleeve has been positioned <NUM> on the cannula <NUM>, the sleeve <NUM> can be trimmed on the proximal end <NUM> and cut at the distal end <NUM> to form or create a chamfered leading edge <NUM>.

With reference to <FIG>, once the preformed sleeve <NUM> has been advanced over the cannula <NUM> and the bonding segment <NUM> of the sleeve <NUM> is positioned within the annular groove <NUM> of the cannula <NUM>, the sleeve <NUM> can be coupled or bonded <NUM> to the cannula <NUM>. For example, in some embodiments, the proximal end <NUM> of the sleeve <NUM> and the distal end <NUM> of the sleeve <NUM> are each bonded <NUM> to the cannula <NUM>. In some embodiments, the proximal interface section <NUM> of the sleeve <NUM> is adhered to a location adjacent the proximal end <NUM> of the cannula <NUM> and the bonding segment <NUM> is adhered to the annular groove <NUM>. For example, one or more of a cyanoacrylate adhesive and a UV cure bonding adhesive can be used to couple the sleeve <NUM> to the cannula <NUM>.

The retention disc <NUM> can be positioned proximally of the balloon <NUM> around an outer surface of the sleeve <NUM>. When installing the retention disc <NUM> on to the sleeve sub assembly <NUM>, a fixture can be used to slightly expand the disc <NUM> to install over the balloon <NUM> and to avoid any possible balloon <NUM> damage.

With continued reference to <FIG>, once the sleeve <NUM> has been positioned <NUM> on and bonded <NUM> to the cannula, the subassembly is then locally heated <NUM> at the distal end proximal to the bonding site. The amount of material that is heated goes directly into forming the balloon and determines the wall thickness of the balloon. Excellent control of wall thickness can be achieved by selecting the appropriate width of the heating elements that deliver heat to the section of tubing to be formed into the balloon. For example, heating elements that are <NUM>" wide consistently produce balloons with a perimeter wall thickness of <NUM>" (+/- <NUM>"). In other embodiments, different sized heating elements can locally heat the distal end of the sleeve <NUM> to form balloons having different thicknesses.

Once the sleeve is locally heated <NUM>, an inflation fluid is applied <NUM> to the sleeve <NUM> to form a balloon adjacent the distal end of the sleeve <NUM> proximal the bonding. <FIG> schematically illustrates formation of the balloon <NUM>. The balloon can be formed in a generally circular disc shapeor the balloon can be formed in a generally toroidal or donut shaped balloon. The balloon <NUM> can be formed having other geometries, such as a generally frusto-conical profile or another rounded profile. Advantageously, this control in balloon shape can maximize the total working distance of the device. Furthermore, the round balloon shape and soft material provides an atraumatic means to hold the trocar assembly <NUM> in place.

Once the balloon is formed, the balloon can be conditioned <NUM> to constrict against the cannula. For example, as illustrated in <FIG>, the balloon <NUM> can be folded along the elongate tubular body <NUM> of the sleeve <NUM> towards the proximal end <NUM> of the cannula <NUM> into an insertion configuration. As described above, significant reductions in insertion force can be achieved by folding the balloon in a two step process (an initial distal tuck or fold followed by a second proximal tuck or fold while the balloon retains residual heat). Desirably, the balloon can be conditioned <NUM> when the balloon retains heat from the local heating to enhance the constriction of the balloon. As illustrated in <FIG>, in some embodiments, the conditioning aid <NUM> can then be advanced <NUM> over the balloon <NUM> to keep the balloon <NUM> folded until use and to retain a smooth transition from cannula distal tip <NUM> to balloon <NUM>. <FIG> schematically illustrate such conditioning with a conditioning aid. The interior surface of the conditioning aid <NUM> desirably has an inner diameter D3 sized to constrict the balloon <NUM> against the cannula body <NUM>.

At final sleeve sub assembly <NUM> configuration (<FIG>), the retention disc <NUM> can be placed relatively close to the distal end <NUM> of the cannula <NUM> with the conditioning aid <NUM> flushed against it. The retention disc <NUM> acts as an anchor and prevents the conditioning aid <NUM> from sliding proximally past the balloon <NUM> prior to use. Similarly, with a position adjacent the distal end <NUM> of the cannula <NUM>, the retention disc <NUM> can be placed at a relatively small diameter of the cannula body <NUM> to avoid stretching the inner diameter prior to use.

Various balloon <NUM> folding techniques can be used to provide a relatively low diametric profile to reduce insertion force for the trocar cannula assembly. For example, in some embodiments, the balloon <NUM> can be folded proximally upon itself in a single folding step. Using a conditioning aid <NUM>, the balloon <NUM> can be pushed against or towards a retention disk <NUM> or bolster <NUM>' causing the balloon <NUM> to fold upon itself in a proximal direction. Alternatively, as described further below, the balloon <NUM> can be folded in a two-step process with an initial distal fold followed by a proximal fold. The balloon folding technique to be incorporated in a method of manufacture for a trocar cannula assembly can be selected to provide a desired insertion force and ease of manufacturability. Desirably, further reductions in insertion force can be achieved if the two-step folding process is performed when the balloon is in a formable state.

Subsequent to or during the extraction of air, a retention disk <NUM> or bolster <NUM>' of the trocar without a sleeve or cone (e.g., the bolster base) can be slid or pushed against a proximal end of the balloon <NUM> to push or apply a force distally away from the proximal end <NUM> of the trocar cannula <NUM>. The distal end <NUM> of the bolster can be positioned adjacent the proximal end <NUM> of the balloon <NUM>, as illustrated schematically in <FIG>. Using a conditioning aid <NUM>, the balloon <NUM> is pushed against or towards the retention disk <NUM> or bolster <NUM>' causing the balloon <NUM> to fold upon itself in a proximal direction. A compressive force of the conditioning aid <NUM> against the balloon <NUM> continues as the conditioning aid <NUM> slides over the balloon <NUM>. This sliding movement fully compresses the balloon <NUM> into a preferred, compressed condition, as illustrated schematically in <FIG>. The conditioning aid <NUM> can be advanced using a linear motion or a slight twisting motion to provide a relatively low balloon insertion profile. The retention disk <NUM> or bolster can be moved proximally when the conditioning aid <NUM> is in place covering the entire folded balloon <NUM>. Placement of the conditioning aid <NUM> over the balloon <NUM> and in particular over the fold in the balloon <NUM> maintains the fold in the balloon <NUM> and/or the evacuation of air from the balloon <NUM>. A removable base support can be removably attached to the cannula <NUM> and used as a support to push the proximal end of the balloon <NUM>.

As illustrated schematically in <FIG>, subjecting or applying sterilization <NUM> to the balloon <NUM>, e.g., applying gamma sterilization to the balloon <NUM> further maintains the balloon <NUM> folded against the cannula <NUM> and further reduces the outer profile of the balloon <NUM> to be flushed or flattened against or towards the outer surface of the cannula <NUM>. The resulting inflation configuration of the balloon <NUM> is illustrated schematically in <FIG>.

The sterilization <NUM> process may include electron-beam, gamma radiation or heat. The irradiation provides a "setting" of the folded material to a predetermined condition, size and shape. The material of the compressed balloon <NUM> may be partially cross-linked during this process. In the instance where heat may be applied, a heat-shrinkable material may be used for the sleeve <NUM> thereby compressing the balloon <NUM> without the friction associated with sliding a snug fitting conditioning aid <NUM> over the un-inflated balloon. The irradiation process <NUM> may involve a sterilization process in which the assembled trocar cannula <NUM> and sleeve <NUM> with balloon <NUM> are sterilized for surgical use.

Vacuum, syringes or other air evacuation devices can be used to remove the fluid from the balloon. A cap can cover the check-valve <NUM> of the trocar cannula assembly <NUM> to facilitate maintenance of the evacuation of fluid from the balloon <NUM> and to prevent seeping of ambient air into the balloon <NUM>. Compression or restriction of the balloon <NUM> by the conditioning aid <NUM> facilitates maintenance of the evacuation of air and to prevent seeping of ambient air into the balloon <NUM>. As a balloon trocar cannula assembly <NUM> may be turned and torqued against the body cavity or incision during use, a balloon <NUM> may rupture. The folding of the balloon <NUM> does not increase the likelihood of balloon <NUM> rupture and prevents potential damage to the balloon <NUM> during insertion. Further application of the syringe or other air evacuation devices to remove air from the balloon may be applied while the conditioning aid <NUM> is placed or remains on the balloon <NUM>, during and/or after sterilization and/or prior to removal of the conditioning aid <NUM>.

With reference to <FIG>, as illustrated, some embodiments of balloon trocar including a conditioning aid <NUM> applied while the balloon was in a formable state (plotted as a dotted line) can have a reduced insertion force profile as compared with an equivalent balloon trocar having a balloon formed without a conditioning aid (plotted as a solid line). <FIG> illustrates insertion force versus insertion depth (as compared with reference positions along the cannulae, illustrated schematically above the plotted insertion force profiles) of various exemplary balloon trocar cannulae. The lightened line illustrates a reduction in insertion force local maxima or 'peaks' for an exemplary trocar cannula assembly having a balloon with a chamfered leading edge <NUM> and formed with a conditioning aid <NUM> as further discussed herein as compared with an exemplary balloon trocar cannula without these aspects. For example, at reference position <NUM> a local insertion force maximum can be reduced by a balloon formed with a conditioning aid. It is contemplated that certain advantageous reductions in insertion force maxima can be achieved by a balloon trocar cannula having one or both of these aspects.

Claim 1:
A cannula assembly comprising:
a cannula (<NUM>) having a proximal end (<NUM>), a distal end (<NUM>) opposite the proximal end (<NUM>), and a lumen extending from the proximal end (<NUM>) to the distal end (<NUM>) along a longitudinal axis (L), the lumen configured to receive a surgical instrument therein, the cannula (<NUM>) comprising:
a generally tubular cannula body (<NUM>) having an exterior surface (<NUM>) and a first outer diameter (D1); and
an annular recess (<NUM>) formed in the exterior surface of the cannula body (<NUM>) adjacent the distal end (<NUM>) of the cannula (<NUM>), the annular recess (<NUM>) transverse to the longitudinal axis (L), the annular recess (<NUM>) having a second outer diameter (D2) smaller than the first outer diameter (D1) of the cannula body (<NUM>), and the annular recess having a textured surface adapted to receive an adhesive; and
a sleeve (<NUM>) having a proximal end (<NUM>) and a distal end (<NUM>), the sleeve disposed around the cannula from adjacent the proximal end (<NUM>) of the cannula to the annular recess (<NUM>), the sleeve (<NUM>) comprising:
an elongate tubular body (<NUM>); and
a balloon (<NUM>) positioned distal the elongate tubular body (<NUM>);
wherein the annular recess (<NUM>) extends along the cannula a first length (<NUM>) relative to the longitudinal axis; and the sleeve comprises a bonding segment (<NUM>) distal the balloon (<NUM>), the bonding segment (<NUM>) extending into the recess (<NUM>) a second length (l2) relative to the longitudinal axis, the second length less than the first length.