Seal assembly for a cannula

CROSS-REFERENCE TO RELATED APPLICATIONS

0001The present disclosure relates generally to medical and surgical devices, and more specifically to seal assemblies for cannulas.

0002Arthroscopic or, more generally, endoscopic surgical procedures enable closed surgery to be performed via portals through which a variety of elongated instruments may be passed to gain access to an internal surgical work site. Very often a disposable cannula is inserted into the portal in order to provide a convenient passageway through which various instruments may be passed. Because many arthroscopic procedures require the use of pressurized fluid to distend and irrigate the joint being operated upon, the cannula must provide a sealed passageway in order to enable instruments to be passed into and out of the cannula while maintaining a fluid seal whether or not an instrument is in the cannula passageway. The sealing of such cannula passageways is usually accomplished by one or more elastomeric membranes attached to the proximal end of the elongated cannula.

0003Since the fluid at the work site is pressurized, care must be taken to avoid leakage during the time the instrument is being inserted. Current seal assemblies for use in cannulas leak excessively and improvement on the amount of leakage out of the cannula is desired. In addition, upon insertion of an instrument into an opening on the seals of current models, fluid sprays out of the opening. In order to prevent this from occurring, the seal is covered by placing a spray shield on the proximal end of the cannula. <figref idref="f0001">Fig. 1</figref> shows a current cannula model <b>10</b> that has a spray shield <b>11</b> covering the seal assembly <b>12</b> at the proximal end <b>13</b> of the cannula <b>10.</b> However, the size of the spray shield <b>11</b> makes it difficult for the surgeon to work in tight operative spaces. Therefore, a sealing assembly that minimizes this problem is also needed.

0004Furthermore, the variety of instruments which must be inserted through the cannula seal includes instruments of varying sizes and configurations. While the instrument shafts are usually cylindrical, some instruments may have unusually large or sharp distal tips which may cut a seal element upon the insertion or extraction of the instrument thus making it less suitable for subsequent instruments which must be inserted during the same surgical procedure. It is desirable, therefore, to devise a sealing cannula which minimizes this problem.

0005Finally, in addition to instruments, sutures may also be passed through the seal assembly. In fact, the management of these sutures has become critical to the technical success of the surgery. Indeed, tangled sutures can terminate an arthroscopic procedure. Therefore, an approach to suture management is also needed. <patcit id="pcit0001" dnum="EP0369314A"><text>EP0369314</text></patcit> discloses an introducer sheath assembly having an improved valve assembly at least three elastic disc shaped membranes. <patcit id="pcit0002" dnum="US5009391A"><text>US5009391</text></patcit> discloses a valve assembly comprising a hollow body member, a compression member received on one end of the body member, a device for adjusting the position of the compression member, and a valve device.

SUMMARY OF THE INVENTION

0006The present invention relates to a seal assembly for a cannula, as defined in claim 1. The cannula includes a housing having a proximal portion and a distal portion. The seal assembly is located in the proximal portion of the housing and includes a first seal including a first tri-slit, a second seal disposed co-axially and proximal to the first seal and including a second tri-slit, and a third seal disposed co-axially to the first seal and the second seal and including a central opening having a diameter of between 1.5mm (.060 inches) to 3.0mm (.120 inches). In an embodiment, a cap is coupled to the proximal portion of the housing and adjacent the third seal and includes a plurality of suture retaining features, such as tabs, for management of sutures during surgery. In another embodiment, the seal assembly further includes a space located between the second seal and the third seal. In yet another embodiment, the first tri-slit and the second tri-slit are offset by an angle α, which is 180°. In a further embodiment, the first tri-slit, the second tri-slit and the central opening define a channel passing through the seal assembly. In yet a further embodiment, the first seal and the second seal are configured to form a seal against sutures and the third seal is configured to form a seal against shafted instruments. In an embodiment, the third seal comprises a synthetic material. In another embodiment, the third seal comprises a polymer, such as polyisoprene.

0007The present disclosure also relates to a seal assembly having a first seal including a first tri-slit and at least one interlocking member, a second seal disposed co-axially and proximal to the first seal, the second seal including a second tri-slit and at least one interlocking member, and a third seal disposed co-axially and proximal to the first seal and the second seal, the third seal including a central opening. The interlocking member of the first seal and the interlocking member of the second seal interlock with each other. In an embodiment, the first seal and the second seal both include multiple interlocking members, wherein the interlocking members of the first seal and the interlocking members of the second seal interlock with each other. The interlocking between the interlocking member of the first seal and the interlocking member of the second seal facilitates positioning of the first tri-slit and the second tri-slit at an angle α, which is 180°, relative to each other.

0008Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

0009The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the embodiments of the present invention and together with the written description serve to explain the principles, characteristics, and features of the invention. In the drawings: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Fig. 1</figref> shows a perspective view of a prior art cannula having a spray shield coupled to the proximal end of the cannula.</li><li><figref idref="f0002">Fig. 2</figref> shows an exploded perspective view of the cannula of the present disclosure.</li><li><figref idref="f0003">Fig. 3A</figref> shows a top view of the first and second seals of the seal assembly of the present disclosure.</li><li><figref idref="f0004">Fig. 3B</figref> shows a top view of the first and second seals of the present disclosure showing suture coming out of the tri-slits.</li><li><figref idref="f0005">Fig. 4</figref> shows a cross-sectional perspective view of the proximal portion of the cannula of the present disclosure.</li><li><figref idref="f0006">Fig. 5</figref> shows a perspective view of the cap of the present disclosure as located on the proximal portion of the cannula.</li></ul>

DETAILED DESCRIPTION OF THE EMBODIMENTS

0010The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

0011An embodiment of a cannula of the present disclosure is illustrated in <figref idref="f0002">Fig. 2</figref> and designated generally by reference number <b>100.</b> The cannula includes a seal assembly for substantially reducing the amount of fluid leakage from the cannula and specifically for forming a seal against sutures and shafted instruments.

0012The cannula <b>100,</b> which is plastic, but could be made from other material known to one of ordinary skill in the art, includes a housing <b>101</b> having a proximal portion <b>102</b> and a distal portion <b>103.</b> Near the proximal portion <b>102,</b> an outflow tube <b>112</b> provides a means for removing fluid from the inner lumen of the distal portion <b>130</b> during surgery. Although, it is also within the scope of this disclosure that the tube <b>112</b> may be used as an inflow tube for supplying fluid to the inner lumen of the distal portion <b>130</b> during surgery. A cover <b>121</b> is detachably coupled to the inflow tube <b>112</b> for closing off the inflow tube while the cannula <b>100</b> is not in use. Located in the proximal portion <b>102</b> is a seal assembly <b>103.</b> The seal assembly <b>130</b> includes a first seal <b>104</b> having a first tri-slit <b>105,</b> a second seal <b>106</b> that is disposed co-axially and proximal to the first seal <b>104</b> and includes a second tri-slit <b>107,</b> and a third seal <b>108</b> that is disposed coaxially and proximal to the first seal <b>104</b> and the second seal <b>106</b> and includes a central opening <b>109.</b> The first seal <b>104</b> and the second seal <b>106</b> both have four sides (<b>104a-d, 106a-d).</b> The seals <b>104,106</b> also have openings <b>110,111</b> that extend through the seals 104,106. The second seal <b>106</b> sits proximal to the first seal <b>104</b> such that no space exists between the seals <b>104,106,</b> the openings <b>110,111</b> of both seals <b>104,106</b> are aligned, and the tri-slits <b>105,107</b> are offset by an angle α, as is further shown in <figref idref="f0003">Fig. 3A</figref>. For the purposes of this disclosure, the angle α is between approximately 150° and approximately 210°, but preferably is 180°. Sides (<b>104a-b</b>, <b>106a-b)</b> and sides (<b>104c-d, 106c-d</b>) of the seals <b>104,106</b> are made to interlock with each other. For example, as shown in <figref idref="f0003">Fig. 3A</figref>, the seals <b>104,106</b> include interlocking members, such as tabs <b>122</b> and detents <b>123,</b> which interlock with one another. The tabs <b>122</b> and detents <b>123</b> alternate with regards to the seals <b>104,106</b> that they are located on. This interlocking feature facilitates positioning of the tri-slits <b>105,107</b> at an angle, approximately 180°, relative to each other each time the seals <b>104,106</b> are assembled together. Other interlocking features, known to one of ordinary skill in the art, may be used.

0013Also shown in <figref idref="f0003">Fig. 3A</figref>, the tri-slits <b>105,107</b> are of a Y-shaped configuration with each slit <b>105,107</b> defining a pair of slit arms (<b>105a-b, 107a-b)</b> joined together at one end <b>105c,107c</b> and forming an obtuse angle as shown. Thus, they each define an arrow pointing in an opposed direction to each other and also define a pair of intersection points 113, forming a channel, as further discussed below, that that extends completely through both seals <b>104,106.</b> Added to each pair of arms <b>(105a-b, 107a-b)</b> are slit legs <b>105d, 107d,</b> which, as described above, are located at an angle α, between approximately 150° to approximately 210°, but preferably 180° from each other. As is shown in <figref idref="f0004">Fig. 3B</figref>, the tri-slits <b>105,107</b> provide a seal against the sutures 200 by having a channel, as further discussed below, that has the smallest possible opening to the sutures <b>200</b> and substantially reduces the amount of fluid leaving the cannula. For the purposes of this disclosure, both the first <b>104</b> and the second <b>106</b> seals are made from silicon. However, other material known to one of ordinary skill in the art could be used, including, but not limited to, rubber, vinyl, polyurethane elastomers, or a combination of components, including styrene-ethylene-butylene-styrene (SEBS) block co-polymers, polyolefins, mineral oils, and silicone oils.

0014The third seal 108 is located proximal to the first <b>104</b> and second <b>106</b> seals and includes a central opening <b>109,</b> along with four other openings <b>114</b> that are located around the outer diameter of the seal <b>108.</b> The seal <b>108</b> is in a co-axial relationship with the first <b>104</b> and second <b>106</b> seal such that the central opening <b>109</b> is aligned with the center 113 of the tri-slits <b>105,107</b> and the openings <b>114</b> on the outer diameter are aligned with the openings <b>110,111</b> on the first and second seals <b>104,106.</b> As shown in <figref idref="f0005">Fig. 4</figref>, the central opening <b>109,</b> which is between approximately 1.5mm (.060 inches) to approximately 3.0mm (.120 inches) in diameter, is configured to form a seal against shafted instruments <b>140</b> that have a diameter that is larger than the opening <b>109.</b> The instrument <b>140</b> is first inserted into the central opening <b>109,</b> and then through the Y-slit channel of the second seal <b>106.</b> Once the instrument is inserted into the opening <b>109,</b> the walls <b>150</b> of the opening <b>109</b> push outward toward the second seal <b>106,</b> yet remain against the shaft of the instrument <b>140</b> to create a seal against any fluid that may flow through the tri-slits <b>105,107</b> and towards the third seal <b>108.</b> For the purposes of this disclosure, the central opening <b>109</b> is round, but it could be of another shape. The third seal <b>108</b> is manufactured from a polymer material, specifically polyisoprene, to substantially reduce the amount of tearing or wear as a result of insertion and/or withdrawal of sharp instruments. Other natural or synthetic materials known to one of ordinary skill in the art, and that would substantially reduce the amount of tear or wear, could also be used. These materials include, but are not limited to, silicone, rubber, vinyl, polyurethane elastomers, or a combination of components, including styrene-ethylene-butylene-styrene (SEBS) block co-polymers, polyolefins, mineral oils, and silicone oils.

0015As mentioned above in <figref idref="f0001">Fig. 1</figref>, upon insertion of an instrument into an opening on the seals of current cannulas, fluid sprays out of the opening. In order to prevent this from occurring, the seal is covered by placing a spray shield on the proximal end of the cannula. This additional step is eliminated in the present disclosure by integrating the spray shield, which in this disclosure is the third seal <b>108,</b> into the cannula. Without the spray shield covering the proximal portion of the cannula, the overall size of the cannula <b>100</b> is smaller, thereby making it easier for the surgeon to work in tight operative spaces.

0016In addition to eliminating the step of adding a spray shield onto the proximal portion, the cannula <b>100</b> of the present disclosure also substantially reduces the amount of fluid spray that occurs outside of the cannula <b>100.</b><figref idref="f0005">Fig. 4</figref> shows a space <b>160</b> that is located between the second seal <b>106</b> and the third seal <b>108.</b> This space <b>160</b> allows for a substantial reduction in the amount of fluid spray that occurs outside of the cannula <b>100</b> by causing some of the fluid that would otherwise be sprayed outside of the cannula <b>100</b> to be reflected back toward the second seal <b>106.</b> In addition to causing a reflection of the fluid, the space <b>160</b> also substantially reduces the force required to insert surgical instruments <b>140</b> by allowing the walls <b>150</b> of the opening to have the space needed to push outward toward the second seal <b>106.</b> If this space wasn't present and the third seal <b>108</b> was against the second seal <b>106,</b> there would be no space to allow the walls <b>150</b> to push outward and a greater amount of force would therefore be required to insert the instrument <b>140.</b>

0017The seal assembly <b>130</b> is placed in the proximal portion <b>102</b> of the housing <b>101</b> such that the openings (<b>110,111,114</b>) of the seals (<b>104,106,108)</b> are placed over columns <b>115</b> that are located along the inside perimeter <b>116</b> of the proximal portion <b>102.</b> These columns <b>115</b> provide support for the seals (<b>104,106,108</b>).

0018A plastic cap <b>118</b> is coupled to the proximal portion <b>102</b> of the housing <b>101</b> and is adjacent to the third seal <b>108.</b> The cap <b>118</b> may be made from another material known to one of ordinary skill in the art. Having the cap <b>118</b> on the proximal portion <b>102</b> of the housing <b>101</b> compresses the seal assembly <b>130</b> and directs fluid leakage during surgery through a channel <b>117</b> defined by the first tri-slit <b>105,</b> second tri-slit <b>107,</b> and central opening <b>109,</b> thereby limiting the fluid leakage to the channel <b>117</b> and substantially reducing the amount of fluid leakage from the cannula <b>100.</b> This reduction in fluid leakage eliminates the possibility of having to use a spray shield and dealing with the above-described problems that result from this use. The cap <b>118</b> includes a central opening <b>119</b> and a plurality of suture retaining features <b>120,</b> or tabs, for the management of multiple strands of sutures during surgery.

0019There are several advantages for having the tabs <b>120</b> on the cap <b>118.</b> As shown in <figref idref="f0006">Fig. 5</figref>, having multiple tabs <b>120</b> on the cap <b>118</b> allows for different strands of suture <b>201, 202</b> to be simultaneously arranged in separate positions. In addition, the tabs <b>120</b> are molded into the cap <b>118,</b> which avoids the need for an accessory device and/or a modification to the housing <b>101</b> by the surgeon to manage the sutures <b>201,202.</b> Furthermore, the tab length extends past the proximal portion <b>102</b> of the housing <b>101 to</b> allow the capture of a suture <b>201,202</b> that is placed behind the tab <b>120</b> and drawn upwards. Additionally, the tabs <b>120</b> are tapered to maintain secure contact with suture strands of various sizes, such as strands <b>201</b> and <b>202.</b> Finally, a suture <b>201,202</b> is easily removed once it is secured to the tab <b>120</b> without damage to the suture <b>201,202</b> or housing <b>101.</b> It is within the scope of this disclosure that the number, size, shape, length, orientation, and thickness of the tabs <b>120</b> could be adjusted to make for alternative embodiments.

0020As various modifications could be made to the exemplary embodiments, as described above with reference to the corresponding illustrations, without departing from the scope of the present disclosure, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto.