WO1999021487A1

WO1999021487A1 - Suture feeding and tensioning device

Info

Publication number: WO1999021487A1
Application number: PCT/US1998/022800
Authority: WO
Inventors: Thomas D. Egan; Richard B. Streeter
Original assignee: Axya Medical, Inc.
Priority date: 1997-10-27
Filing date: 1998-10-27
Publication date: 1999-05-06
Also published as: JP3430152B2; AU1203099A; JP2001520907A

Abstract

A device (1) for use in conjunction with a surgical stitch-forming device whereby suture material (7) is fed through a housing (3) from a rotatable suture driver member (2) within the housing. The suture drive member (2) includes a suture engaging channel (9) which rotates with the spool, and engages with a section of the suture during rotation of the suture drive member (2) to feed the suture out of the device. Tension can be applied to the suture let out of the device by rotating the supply spool in the opposite direction. Feeding, and tensioning of the suture are resistant to slippage and non-damaging to the suture due to a large suture gripping force distributed over a relatively large contact area.

Description

SUTURE FEEDING AND TENSIONING DEVICE

FIELD OF THE INVENTION

The present invention pertains to the field of surgical suturing, specifically to suturing instruments used in Minimally Invasive Surgery (MIS) where conventional needle and thread suturing is difficult due to limited surgical access.

BACKGROUND OF THE INVENTION

The field of MIS has spawned several instruments designed to facilitate suturing in areas of limited surgical access. These instruments can be roughly divided into instruments where suture thread is pulled through tissue behind a solid needle attached to the thread, the needle having been previously forced through the tissue, and instruments where suture is pushed through a hollow tube or semi enclosed channel. The later category, pushed suture, is most applicable to the present technology.

U.S. Pat. No. 4,312,337 to Donohue, entitled "Cannula and Drill Guide Apparatus", discloses a device for passing metallic wire suture through bone. Donohue relies on the stiff nature of metallic wire to permit hand feeding of the wire suture. Tensioning is accomplished by twisting or tying the wire ends together.

U.S. Pat. No. 4,935,027 to Yoon, entitled "Surgical Suture Instrument with Remotely Controllable Suture Material Advancement", and U.S. Pat. No. 4,957,498 to Bays et al, entitled "Suturing Instrument", disclose suture feed mechanisms based on opposed rolling elements. The nature of rolling contact elements on suture, where substantially cylindrical suture is contacted by a cylindrical roller whose axis is orthogonal to that of the suture, is to contact the suture at a single point. In practice the suture deflects at the point of contact resulting in a small elliptical area of contact at the interface between the suture and each roller. Motive friction that can be applied by the roller to move the suture is characterized as the amount of force applied between the roller and the suture, multiplied by the coefficient of friction between the two materials. Crushing stress imposed on the suture by the roller can be characterized as roller force divided by contact area. It is therefore evident that motive friction is limited by contact area if crushing the suture is to be avoided and a small contact area results in a small motive friction of the suture.

The '027 and '498 patents attempt to address this situation through use of a rubber contact surface on the roller. The material increases the coefficient of friction and the conforming nature of the rubber increases the contact area the roller load is distributed over. However, the area increase is slight and the conforming nature of the rubber results in unevenly distributed contact forces thereby reducing the effective force that can be applied to provide motive friction.

U.S. Pat. No. 5,417,700 to Egan, entitled "Automatic Suturing and Ligating

Device", discloses a device for automatically forming a complete stitch where suture material is fed and tensioned from a single source.

The present invention represents an advancement over the prior art through automation of the feeding and tensioning process.

OBJECTS OF THE INVENTION

It is an object of the present invention to grip (hold) thread (e.g., suture) in a positive (non-slipping) manner.

It is also an object of the present invention to forcibly feed (i.e., push) thread (e.g., suture) in a positive (non-slipping) manner.

It is also an object of the present invention to tension (i.e., pull) thread (e.g., suture) in a positive (non-slipping) manner.

It is also an object of the present invention to grip, feed, and tension thread with sufficient force to generate sufficient friction to be non-slipping in its intended use while distributing the gripping force over sufficient area to avoid damaging the thread.

It is also an object of the present invention to evenly distribute gripping force over the gripping area.

It is also an object of the present invention to confine the path of the thread while feeding, tensioning, or holding in a way that inhibits the ability of the thread to bunch-up, kink, fold or otherwise suffer buckling compressive failure.

It is also an object of the present invention to provide a gripping surface that does not introduce sharp contact points that might cause cuts, nicks or dents in the thread.

It is also an object of the present invention to provide an easy loading method for suture into a feeding or tensioning device.

It is also an object of the present invention to provide a feeding and tensioning system including an integrated supply spool of suture.

It is also an object of the present invention to provide a feeding and/or tensioning mechanism that can be interchangeably driven by manual or mechanized power.

It is also an object of the present invention to provide a tensioning mechanism that provides a user-selectable suture tension in a repeatable automatic process. It is also an object of the present invention to feed thread-like pharmaceutical products into difficult-to-access regions of the body by means of a tube or catheter.

SUMMARY OF THE INVENTION

The foregoing objects are met in a new suture feeding and tensioning device. The new structure includes, in a preferred embodiment, an internal spool of suture material, preferably monofilament suture material, which is contained within a housing that confines the suture to the spool, except for passages in the housing that guide a single strand of the suture from the spool to a suture gripping or engaging structure, and from the gripping structure to a passageway exiting the device. The passageway guiding the suture from the spool to the gripping structure is constructed such that when the spool and gripping structure are rotated together, relative to the housing, suture is directed off the spool surface, around a flange defining the end of the spool, aligned with the gripping structure, and finally into the gripping structure.

In the preferred embodiment, the gripping structure consists of a circumferential slot in the spool, preferably away from the spool drive portion. In another embodiment the suture supply is external to the device or loaded into the device in a loose fashion, without the need for a spool to supply the suture from within the device. The slot is narrower than the diameter of a single strand of the suture material and is bounded on at least one side by a movable member or wall which is biased toward the slot. The movable member can be a disk of flexible material, or a solid disk biased by a force-exerting element such as a spring. As the suture is forced into the slot by the rotational movement of the spool relative to the housing, the slot is spread apart and the suture is grasped therein by the biasing force of the movable member.

The length of engagement of the suture is dependent upon the circumference of the gripping structure and the locations of the points where suture is guided into, and out of, the gripping structure. In a preferred embodiment, as much of the gripping structure circumference as spacing of the suture entrance and exit passages will allow is used. In a preferred embodiment this results in approximately 75% of the circumference being used to engage the suture.

The flat surfaces of the walls of the slot contact the suture, which is typically cylindrical, in line contact. The width of the line is determined by the amount of contact deflection of the suture and the surface characteristics of the walls of the slot. Therefore the contact area of the suture with the gripping structure is the length of suture in the gripping structure multiplied by the width of contact with both walls of the slot. This is a large area of contact in comparison to the point contact produced by roller feeding mechanisms, thereby permitting significantly greater gripping force to be exerted over the suture contact area.

The suture exits the gripping structure and is guided out of the slot by a ramp that is stationary with respect to the housing. Once free of the gripping structure the suture is guided into a passage in communication with the structure or device in which the suture is to be used, such as, for example, a surgical stitching device. In the preferred embodiment, the passageway from the gripping structure to the device in which the suture is to be used has no sharp bends and is only slightly larger in diameter than the diameter of the suture itself. In this way the suture moves freely through the passage and is confined so as to avoid buckling or snagging within the passageway.

The feeding of the suture to the device in which it is to be used is accomplished by rotating the spool and gripping structure together in a direction that pushes suture from the supply spool and through the exit passageway. Tensioning of the suture is accomplished by reversing the direction of rotation. Initial loading of suture on the spool from an external supply may be performed by continuous rotation of the spool in the tensioning direction until a sufficient length of suture has been loaded on the spool. In one preferred embodiment, the force to rotate the spool and gripping structure together is controlled in such a way as to feed a precise length of suture to the device in which it is to be used. In another preferred embodiment, the suture is fed onto the spool under a predetermined force. In another embodiment, the suture is tensioned to a predetermined tension value. In another embodiment, the suture is tensioned for a predetermined distance. In another embodiment, the suture is fed and/or tensioned to a distance and/or under a force determined by the user.

According to one aspect of the invention, there is provided a suture feeding and tensioning device, which comprises: a. A housing disposed about a reference axis, the housing including a suture exit aperture; b. A suture drive member disposed within the housing and adapted for rotation about the reference axis, said drive member having a lateral surface extending at least in part in the direction of the reference axis and including a suture channel disposed about the reference axis and having sidewalls extending radially inward from the lateral surface of the drive member; c. A suture feeder for feeding a suture into the channel, whereby the suture is frictionally engaged with the sidewalls of the channel; and d. A suture extractor disposed near the suture exit aperture and extending into the suture channel, thereby defining a continuous suture path from the suture channel into the suture exit aperture.

The device can further comprise a selectively operable driver for rotating the suture drive member relative to the housing. In a preferred embodiment, the driver causes selectively controlled rotation of the spool in both clockwise and counterclockwise directions.

In one embodiment, at least one of the sidewalls of the suture channel is resilient. In another embodiment, both of the sidewalls of the suture channel are resilient. The sidewalls of the suture channel can be textured or substantially smooth. The device can further include a suture supply spindle for supporting a coil of suture.

In one embodiment, the housing further includes a suture entrance aperture coupled to the suture feeder and defining a suture path from the spindle through the suture entrance aperture to the suture channel.

In another embodiment, the spindle is preferably coaxial with and affixed to the suture drive member and includes at least one at least in part radially extending flange disposed between the spindle and the suture channel in the suture drive member. The housing includes an inner surface disposed about and adjacent to the lateral surface of the suture drive member. The housing thus defines a suture path between the spindle and the channel at a predetermined distance along the channel from the suture exit aperture.

In one embodiment, the suture extractor includes a suture guide member affixed to the housing and disposed within the suture channel and about the reference axis for defining, in part, a continuous suture path within the suture channel and between the suture channel and the suture exit aperture.

The suture extractor can include a suture exit tube extending from the suture path through the suture exit aperture of the housing to points external to the housing. In a preferred embodiment, the diameter of the suture exit tube is less than twice the diameter of the suture.

In a preferred embodiment, the diameter of the suture exit aperture is preferably less than twice the diameter of the suture. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric and schematic view of the device and its controls, according to one aspect of the invention.

FIG. 2 is an exploded isometric view of the mechanical portion of the suture feeding and tensioning device.

FIGS. 3a and 3b are section views of the spool/driver structure, guide ring and suture showing the grasping action of the gripping structure slot.

FIG. 4 is a plan view of the mechanical portion of the device.

FIG. 5 is a side elevational view of the device shown in FIG. 4.

FIG. 6 is an isometric view of the spool structure and feeding mechanism.

FIG. 7 is a sectional view of the spool structure shown in FIG. 4. taken along section line A-A.

FIGS. 8A-8C are enlarged sectional views of a portion of the housing and suture drive member along respective section lines A-A, B-B and C-C of FIG. 2.

FIG. 9 is an electrical schematic diagram of a feeding and tension control circuit according to one aspect of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows an overview of the device and its controls. The individual components of the device are illustrated more clearly in FIGS. 2-8. A schematic diagram of a microprocessor-based control system for the device is shown in FIG. 9.

A suture feeding and tensioning device 1 consists of at least the following components: a suture drive member 2, a housing 3, a suture feeder 4, and a suture extractor 5.

As shown in FIG. 2, the housing 3 may be in one or more parts 3a, 3b and is disposed about a reference axis X. The housing includes a suture exit aperture 6 for suture 7 to leave the housing.

As shown most clearly in FIGS. 3a and 3b, the suture drive member 2 is disposed within the housing and is adapted for rotation within the housing about the reference axis. The drive member has a lateral surface 8 which extends at least partially in the direction of the reference axis and includes a suture channel 9 that is also disposed about the reference axis. The suture channel has sidewalls 10 that extend radially inward from the lateral surface of the drive member.

The suture feeder 4 feeds suture 7 into the suture channel 9 so that the suture 7 is frictionally engaged with the sidewalls 10 of the channel. The suture extractor 5, shown most clearly in FIG. 6, is disposed near the suture exit aperture 6 and extends into the suture channel 9 so as to define a continuous path for the suture from the suture channel into the suture exit aperture.

The device can include a selectively operable driver 11, shown in FIG. 1, which causes selectively controlled rotation of the suture drive member 2 relative to the housing. In one embodiment, the driver 11 can be a gear mechanism, including a driven gear 12 and a driver gear 13. In another embodiment, the driver 11 can be a belt pulley, motor shaft, thumb wheel or any other means known to the art to impart selective clockwise and counterclockwise rotational movement to the suture drive member 2. At least one of the sidewalls of the channel can be resilient, relative to the other sidewall, so that the suture can be frictionally engaged by or wedged into the channel upon flexible movement of the resilient sidewall relative to the other sidewall. In another embodiment, both of the sidewalls of the channel are relatively resilient. An advantage of relatively resilient sidewalls is less potential for damage to the suture when it is engaged within the suture channel. Alternatively, the channel sidewalls can be rigid if a relatively compressible suture material is used.

The sidewalls of the suture channel 9 can be either textured or smooth, or desired, to effect an optimum contact area with the suture 7 engaged frictionally therebetween. In a preferred embodiment, the sidewalls of the channel are smooth so as to distribute more evenly over the suture within it the gripping force of the sidewalls on the suture material. In another embodiment, as shown in FIG. 3a, the sidewalls can include, for example, ribs, bumps, or other irregularities which cause the gripping force on the suture to be unevenly distributed. Another preferred embodiment includes concentric ribs or grooves to promote increased contact area between the sidewalls and the suture.

In a preferred embodiment, the extent of contact between the sidewalls of the channel and the suture within the channel is maximized along the length of the channel so that the force exerted on the suture by the channel sidewalls is distributed over a relatively large area. This large area of contact enhances the control that the user has over the movement of the suture into and out of the device, as well as the control that the user has over the tension imparted to the suture once it has been fed from the device. In an especially preferred embodiment, the contact area between the suture and the channel is effected over at least 75% of the circumference of the suture drive member in which the suture channel is located.

The device can further include a suture supply spindle 14 for supporting a coil of suture. The supply spindle can be external to the housing or internal to it, as detailed more fully below. In the embodiment in which the suture supply spindle 14 is external to the housing 3, as shown in FIG. 1, the housing includes a suture entrance aperture 15 which is coupled to the suture feeder to define a suture path 16 from the spindle through the suture entrance aperture to the suture channel.

In the embodiment, in which the suture supply spindle 14 is internal to the housing 3, as shown in FIG. 2, the spindle is preferably coaxial with and affixed to the suture drive member 2. The spindle in this embodiment includes at least one flange 17, shown most clearly in FIGS. 3a and 3b, which extends at least in part radially therefrom. The flange 17 is disposed between the spindle and the suture channel in the suture drive member.

The housing 3 includes an inner surface 3' disposed about and adjacent to the lateral surface of the suture drive member. This inner surface is contoured, as shown in FIG. 2, to define a suture path 18, shown most clearly in FIGS. 8B and 8C, between the spindle and the suture channel at a predetermined distance along the channel from the suture exit aperture. This suture path allows the suture to ride over the flange 17 and into the suture channel 9 when the channel and drive member are rotated relative to the housing in a direction which lets suture out of the device. The suture can then be frictionally engaged within the sidewalls of the channel.

The suture extractor 5 optionally includes a suture guide member 19 which is preferably affixed to the housing 3 and disposed within the suture channel 9 and about the reference axis X. The guide member 19 defines, in part, a continuous suture path within the suture channel and between the suture channel and the suture exit aperture. In one embodiment the guide member 19 can be split to permit installation into the channel, which may be integral with the suture drive member. In another embodiment, the suture drive member 2 and the channel are separate components joined at assembly, allowing the guide member 19 to be installed without being split. In yet another embodiment the guide member 19 or just the exit ramp portion of the guide member 19 are integral to the housing 3a and 3b. In yet another embodiment, the guide member 19 is not present, and the suture exits the housing on the basis of its own inherent stiffness, or with the aid of an optional suture exit tube 20 which extends from the suture path through the suture exit aperture of the housing to points external to the housing. The suture exit tube preferably has a diameter or opening dimension which is less than twice the diameter or largest cross-sectional dimension of a single suture, so that the suture cannot buckle or get caught in the exit tube on its way out of the housing. Other elements may be used to effect extraction, such as, for example, a protuberance extending from inner surface 3' into the suture channel 9.

In a preferred embodiment the guide member 19 can include an indent 21 which receives the edge of the exit tube 20 so that a substantially uninterrupted surface is formed between the exit portion 22 of the guide member 19 and the inside diameter of the exit tube 20. In a preferred embodiment the exit tube 20 is continuous and of sufficient length to guide the suture to the point of use. The exit tube 20 can be rigid or flexible, straight or have multiple bends or curves. In a preferred embodiment the inside diameter of the exit tube 20 is slightly larger than the diameter of a single strand of the suture material 7 and made from or lined with a lubricious material. In another embodiment, a passage 23 serves as a guide for suture exiting the housing, and no separate exit tube is required. The passage 23 allows for positioning of the exit tube 20 so that it extends through the suture exit aperture in the housing.

It is also preferred that the diameter or opening dimension of the suture exit aperture in the housing be less than twice the diameter or largest cross-sectional dimension of a single suture, so that the suture cannot easily double back on itself or otherwise get snagged within the exit aperture.

FIG. 5 shows the relationship between the housing 3 a, 3 b and the suture drive member 2, which preferably fits within the housing and is partially accessible to a driver element, as discussed more fully below. FIG. 6 illustrates a plan sectional view of the suture drive member and housing, taken along section lines B-B of FIG. 5. This view clearly shows the path of the suture 7 from the suture drive member, along the suture channel on the outside of an optional guide member 19, through an optional exit tube 20, and through a suture exit aperture and out of the device.

FIG. 7 illustrates a sectional view of the housing and suture drive member as assembled, with a detail portion illustrating the location of the suture feeder 4, the operation of which is shown in detail in FIGS. 8A-8C.

FIG. 8A is taken along section lines A-A of the housing shown in FIG. 2. FIG. 8C is taken along section lines C-C of the housing shown in FIG. 2. These two FIGURES are identical in that they illustrate portions of the housing 3 in which the housing 3 directly abuts the suture drive member 2, thereby defining a first region A in which suture is confined. This region A corresponds to a bobbin or other spool- type device on which a section of suture can be wound. The first region A is completely isolated from the suture channel, as clearly shown in FIGS. 8A and 8C.

FIG. 8B is taken along section lines B-B of the housing shown in FIG. 2. In this FIGURE, a portion of the housing 3 is cut away so that it is still adjacent to. but not directly abutting, the suture drive member 2. thereby defining a second region B of variable width in communication with first region A. The presence of the second region B establishes a link between the first region A and the suture channel 10. This region can alternatively be of constant width.

The second region B is large enough to accommodate a single suture so that it can pass out of the first region A, into the second region B. At some point beyond section B-B of the housing, the second region B becomes smaller and disappears, thereby forcing the suture 7 into the suture channel, as shown in FIG. 8C.

As shown in FIGS. 1 and 9, a drive element 11 is connected to a drive portion V of the suture drive member 2. In a preferred embodiment the drive element 11 consists of a motor 25 and a pinion gear 26 which engages with driven gear 12. Other drive element, as previously mentioned, are known to the art and can be used in place of those shown. A means of controlling the length of suture fed from the device is included. In one preferred embodiment an encoder 27 is used to monitor the length of suture to be fed and/or tensioned. Other ways of measuring the length of suture displaced, or the angular displacement of the suture drive member 2 or the drive element 11, are known to the art.

As shown in FIG. 9, a preferred embodiment of the device includes a microprocessor-based controller 28 to control the feed and tensioning functions of the device. In one embodiment the distance of suture fed by the device is programmed in the software of controller 28. The encoder 27 provides feed distance feedback to the controller. In one preferred embodiment, the tension on the suture is controlled by an electronic tension control circuit 29 consisting of a sense resistor 30 in one leg of the motor 25 power lead, a voltage comparator 31 and a variable resistor 32. Electrical current needed to drive the motor 25 is proportional to suture tension. The sense resistor 30 permits measurement of a voltage proportional to motor current. This voltage and a reference voltage measured at the variable resistor 32 are fed into the voltage comparator 31. When voltage at the sense resistor 30 exceeds the reference voltage measured at the variable resistor 32, the voltage comparator 31 sends a signal to the controller 28 to stop the motor at the desired suture tension as preset by the user at the variable resistor 32. Another preferred embodiment adds a manual input device such as a level or trigger that is in turn attached to a second encoder. The controller software is designed such that displacement of the input device is proportional to displacement of the suture.

In this embodiment the electronic tension control circuit 29 may be used to control the upper limit of user-directed tension. Still another embodiment employs a manual input device such as a level or trigger that is mechanically coupled to the drive portion V of the suture drive member 2. In this embodiment tension is controlled by the user through visual and/or tactile feedback. Other preferred embodiments use limit switches, mechanical stops, analog controllers, slip clutches, spring force control, user manual/visual/tactile control and the like, all known to the art, to control feed distance and tension.

Inasmuch as the present invention is subject to many variations, modifications and changes in detail, it is intended that all subject matter discussed above or shown in the accompanying illustrations be interpreted as illustrative only and not to be taken in a limiting sense.

Claims

1. A suture feeding and tensioning device, comprising: a. A housing disposed about a reference axis, the housing including a suture exit aperture; b. A suture drive member disposed within the housing and adapted for rotation about the reference axis, said drive member having a lateral surface extending at least in part in the direction of the reference axis and including a suture channel disposed about the reference axis and having sidewalls extending radially inward from the lateral surface of the drive member; c. A suture feeder for feeding a suture into the channel, whereby the suture is frictionally engaged with the sidewalls of the channel; and d. A suture extractor disposed near the suture exit aperture and extending into the suture channel, thereby defining a continuous suture path from the suture channel into the suture exit aperture.

2. A suture feeding and tensioning device according to claim 1 , further comprising a selectively operable driver for rotating the suture drive member relative to the housing.

3. A suture feeding and tensioning device according to claim 2, wherein the driver causes selectively controlled rotation of the spool in both clockwise and counterclockwise directions.

4. A suture feeding and tensioning device according to claim 1, wherein at least one of the sidewalls of the suture channel is resilient.

5. A suture feeding and tensioning device according to claim 4, wherein both of the sidewalls of the suture channel are resilient.

A suture feeding and tensioning device according to claim 1, wherein the sidewalls of the suture channel are textured.

7. A suture feeding and tensioning device according to claim 1, wherein the sidewalls of the suture channel are substantially smooth.

8. A suture feeding and tensioning device according to claim 1, further comprising a suture supply spindle for supporting a coil of suture.

9. A suture feeding and tensioning device according to claim 8, wherein the housing further includes a suture entrance aperture coupled to the suture feeder and defining a suture path from the spindle through the suture entrance aperture to the suture channel.

10. A suture feeding and tensioning device according to claim 8, wherein the spindle is coaxial with and affixed to the suture drive member, wherein the spindle includes at least one at least in part radially extending flange disposed between the spindle and the suture channel in the suture drive member, and wherein the housing includes an inner surface disposed about and adjacent to the lateral surface of the suture drive member, wherein the housing defines a suture path between the spindle and the channel at a predetermined distance along the channel from the suture exit aperture.

11. A suture feeding and tensioning device according to claim 1, wherein the suture extractor includes a suture guide member affixed to the housing and disposed within the suture channel and about the reference axis for defining in part a continuous suture path within the suture channel and between the suture channel and the suture exit aperture.

12. A suture feeding and tensioning device according to claim 1, wherein the suture extractor includes a suture exit tube extending from the suture path through the suture exit aperture of the housing to points external to the housing.

13. A suture feeding and tensioning device according to claim 12, wherein the diameter of the suture exit tube is less than twice the diameter of the suture.

14. A suture feeding and tensioning device according to claim 1, wherein the diameter of the suture exit aperture is less than twice the diameter of the suture.