FIELD OF THE INVENTION
The present invention generally relates to minimally invasive-surgical cannula, and more particularly, to a
manipulable cannula having parallely arranged anti-rotation grooves.
BACKGROUND OF THE INVENTION
This section is intended to introduce the reader to various aspects of art that may be related to various
aspects of the present disclosure, which are described below. This discussion is believed to be helpful in
providing the reader with background information to facilitate a better understanding of the various aspects
of the present disclosure. Accordingly, it should be understood that these statements are to be read in this
light, and not just as admissions of prior art.
In the most commonly employed configurations, the coupling mechanism in surgical robotic system
transferring the controlling motions from the functional end of the robotic arm to the detachably attached
surgical instrument has a finite range of motion owing to the arrangement of components on its either side.
The limitation in motion adversely hampers the free movement of the coupling arrangement, so necessitated
during the surgery. Now, in order to compensate for the undue loss in free motion of the coupling
arrangement, the robotic arm may have to traverse an undesirable broader course that may enhance
probability of potential conflict between said arms.
Recently, advancement in coupling mechanism is witnessed in the form of modular interfaces that allow
easy detachability of surgical instruments or diagnostic devices and their movement independent of the
robotic system during performance of surgery. With introduction of modular interfaces, the traditionally
occurring cannula assembly that allows long narrow surgical instruments to work inside the body through
small access incision or port site may not be of substantial help owing to the attachment means specific to
existing coupling arrangements.
Now, particularly when deploying the interface at the manipulating end of robotic system, since the
interface is held freely movable to allow it traverse an undesirable broader course to reach remote aperture
sites within the body cavity, the stability of whole interface-cannula complex is of prime concern. Current
designs propose various structures, some quiet complex and some not rigid enough to hold cannula intact
during full play. In addition, it is desirous to have uniform system of attachment of cannula independent of
the size and dimensions of cannula and the connector.
In the light of aforementioned challenges, there exists a need for standard cannula design capable of
establishing a rigidifying secure connection with the modular interfacing arrangements and preventing any
accidental slippage of cannula during surgery.
SUMMARY OF THE INVENTION
In one general aspect of the invention, a cannula having a proximal and a distal end is provided. The
cannula towards its proximal end bears an anti-rotation configuration comprising at least two grooves
having a non-circular profile such that a flat surface is defined therebetween closing ends of each groove
thereby interrupting an otherwise smooth and continuous circumferential profile of grooved cannula to
prevent said cannula from rotating and moving axially when in locked position during surgical insertion.
In one significant aspect of the invention a coupling arrangement including a connector coupling cannula
with an interfacing arrangement is provided that comprises a central support member having disposed
therewithin a resilient member configured to share an abutting relation with a pair of support member wings
extending rearward from the support member towards the interfacing arrangement, said support member
further extending in a frontal direction towards the cannula to include at least two pair of gripping members
so adapted to securely hold the cannula therebetween and release the cannula, in response to the interaction
between the resilient member and the support member wings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of cannula in accordance with one general embodiment of the present
disclosure
Figure 2 presents a cross sectional view of an attachment means of cannula in accordance with one other
embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
Some embodiments of this invention, illustrating all its features, will now be discussed in detail. The
following discussion provides many example embodiments of the inventive subject matter. Although each
embodiment represents a single combination of inventive elements, the inventive subject matter is
considered to include all possible combinations of the disclosed elements.
The invention has for its object an improved cannula attachment system of the aforementioned type that
securely attaches to the freely movable modular interfacing arrangement, eliminates possibility of
unintended automatic sliding out of cannula so fastened, and is still easy to manufacture and use.
In an advantageous embodiment of the present disclosure, an anti-rotation feature is provided in cannula as
it is formed of at least two grooves with a semi-circular profile towards its proximal end. The cannula
described herein in the description section of the document is capable of accommodating industry
standardized surgical instruments having outside diameters such as 5mm or 8mm.
In one general aspect, referring to Figure 1, a cannula, generally designated by reference numeral 50, with
an anti-rotation feature is presented. The figure shows cannula 50 with grooves 10 and 20 that are not
rendered fully circular in their profile; rather an intermittent gap is provided in between two closing ends
completing the otherwise smooth and continuous circumferential profile of cannula. This serves as a
locking mechanism that fixes the cannula 50 at desired angle with respect to the interfacing arrangement 60
and precludes shifting, twisting or any axial movement of cannula 50 once inserted during the surgical
incision.
In one another particular embodiment of the present disclosure, the two non-circular grooves 10 & 20, as
shown in Figure 1 defines a plain flat surface extending between the two grooves 10 & 20 that is designed
to include a generally longitudinally extending slit 30 therethrough. In the illustrated embodiment, it is to be
understood that the slit is provided to pierce only through few inches of cannula wall, approximately
ranging between .045 to .095 inches. The longitudinally extending slit 30 is configured to accommodate
therein a sensor and strain gauge (not shown in figure) to detect if the interfacing arrangement 60 is
attached securely with the cannula 50, and also to measure forces acting on the cannula 50 by the
interfacing arrangement 60 while it is being maneuvered inside the body cavity.
Now, referring to Figure 2, a connector 40 configured to attach cannula 50 to the interface arrangement 60
is provided. The connector 40 may include a central support member 42 having disposed therein a resilient
member 43 that further shares an abutting relationship with a pair of support member wings 44(a), 44(b)
that extends rearward from the support member 42 towards the interfacing arrangement 60. Extending in
frontal direction from the central support member 42 towards the cannula are provided at least two pair of
gripping members 48(a), 48(b) for engaging the cannula 50 therebetween rigidly and securely to prevent
inadvertent slip out during performance of surgery. In one preferred embodiment, the connector 40 may
have laterally extending protrusion like clips 46(a), 46(b) that can be pressed inwards to actuate the support
member wings 44(a), 44(b) causing compression of resilient member 43 and opening apart of gripping
members 48(a) and 48(b).
As can be clearly seen from Figure 2, the central support member 42 of the connector 40 engageably
couples with the tool interfacing arrangement 60 and is configured to receive therewithin a resilient member
43, for example a torsion spring. The resilient member 43 shares an abutting relationship with central
support member wings 44(a), 44(b) that are further operably connected with laterally extending protrusions
46(a), 46(b) on either side of the support member 42 such that the protrusions when pressed manually
compresses the torsion spring 43, which further causes concomitant movement of gripping members 48(a),
48(b) it is coupled with. Upon compressing the spring 43, the extensions of central support member 42, in
the form of grippers 48(a), 48(b) are pulled outwardly of their radial centers so as to receive the cannula 50
therebetween. When released, the torsion spring 43 decompresses to cause the support member wings 44(a),
44(b) to resume their original position, which further causes the two pair of gripping members 48(a), 48(b)
to embrace respectively each of the two grooves 10, 20 of the cannula 50 such that the cannula 50 is firmly
and rigidly held therebetween the gripping members 48(a) and 48(b).
In one preferred embodiment of the present invention, the sensor and the strain gauge are accommodated at
least in part in the slit 30 such that the sensor and the strain gauge protrude outward of the slit 30. Now, as
the clips 46(a), 46(b) are pressed inwards, the partially protruding sensor and strain gauge deforms as it
presses against the central support member 42, which helps the sensor to detect if the cannula is adequately
held by the interface arrangement 60. Likewise in its configuration with respect to the central support
member 42, the strain gauge also protruding partially out gets pressed when cannula 50 is held by the
interfacing arrangement 60 and measure forces acting on the cannula 50 by the interfacing arrangement 60
when it is maneuvered inside the body cavity.
The foregoing description has been directed to one or more specific embodiments of this invention. It will
be apparent; however, that other variations and modifications may be made to the described embodiments,
with the attainment of some or all of their advantages. Accordingly this description is to be taken only by
way of example and not to otherwise limit the scope of the invention. Therefore, it is the object of the
appended claims to cover all such variations and modifications as come within the true spirit and scope of
the invention.

What is claimed is:
A cannula having a proximal and a distal end with the proximal end bearing an anti-rotation
configuration comprising at least two grooves having a non-circular profile such that a flat surface
is defined therebetween closing ends of each groove thereby interrupting an otherwise smooth and
continuous circumferential profile of cannula to prevent said cannula from rotating and moving
axially when in locked position during surgical insertion.
The cannula of claim 1, wherein the flat surface defined between closing end of each groove further
forms thereupon a narrow slit to accommodate at least in part one sensor to detect if the cannula is
securely engaged with a robotic arm and surgical instrument connecting interfacing arrangement.
The cannula of claim 2, wherein the narrow slit may further accommodate at least in part a strain
gauge to measure force exerted on the cannula by the interfacing arrangement engageable
therewith.
The cannula of claim 2, wherein the slit is formed to pierce only through a relatively small
thickness of cannula wall, preferably between .045 to .095 inches.
A coupling arrangement including a connector coupling cannula with an interfacing arrangement,
and comprising:
a central support member having disposed therewithin a resilient member configured to share an
abutting relation with a pair of support member wings extending rearward from the support member
towards the interfacing arrangement, said support member further extending in a frontal direction
towards the cannula to include at least two pair of gripping members so adapted to securely hold the
cannula therebetween and release the cannula in response to the interaction between the resilient
member and the support member wings.
The coupling arrangement of claim 5, wherein the resilient member is a torsion spring.
The coupling arrangement of claim 5, wherein in response to pressing of support member wings
inwards concomitant outward pulling of the pair of gripping members from their radial centers
occurs so as to securely receive the cannula therebetween, and in response to releasing of the
support member wings, the gripping members overlap to securely and rigidly hold the cannula
therewithin.
8) The coupling arrangement of claim 5, wherein the connector may further have laterally protruding
clip on either side of support member such that pressing of clip inwards result in concomitant
movement of support member wings and that of the gripping members.
9) The coupling arrangement of claim 5, wherein the connector connecting the interfacing
arrangement with the cannula involves a cannula comprising at least two grooves having a noncircular
profile such that a flat surface is defined therebetween two grooves thereby interrupting an
otherwise smooth and continuous circumferential profile of cannula, said flat surface further
accommodating thereupon a slit to house at least in part one protruding sensor and a strain gauge.
10) The coupling arrangement of claim 4, wherein the two pair of gripping members are configured to
embrace each respective grooved section of cannula such that the protruding sensor or strain gauge
housed partially within the slit of cannula presses against the central support member to detect and
measure forces acting on the cannula by the interfacing arrangement.