Surgery – Instruments – Suture or ligature
Reexamination Certificate
2000-12-08
2002-03-19
Chaudhuri, Olik (Department: 2814)
Surgery
Instruments
Suture or ligature
Reexamination Certificate
active
06358271
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to improvements in sutures and suturing techniques, and more particularly to materials and devices for making high-strength fused suture loops during surgical procedures.
BACKGROUND OF THE INVENTION
In surgical procedures, a monofilamentous suture is typically used to stitch or secure the edges of tissue together to maintain them in proximity until healing is substantially completed. The suture is generally directed through the portions of the tissue to be joined and formed into a single loop or stitch, which is then knotted or otherwise secured in order to maintain the wound edges in the appropriate relationship to each other for healing to occur. In this manner a series of stitches of substantially uniform tension can be made in tissue. Because the stitches are individual and separate, the removal of one stitch does not require removal of them all or cause the remaining stitches to loosen. However, each individual stitch requires an individual knot or some other stitch-closing device for securing the stitch around the wound.
It is sometimes necessary or desirable to close a wound site with sutures without having to form knots or incorporate loop-closing devices in the sutures, such as, for example, in surgical repair of delicate organs or tissues, where the repair site is relatively small or restricted. A fused suture loop must provide the appropriate tension on the wound edges and the appropriate strength to maintain the wound edges in sufficient proximity for a sufficient time to allow healing to occur.
Polymer sutures are particularly amenable to various fusing or joining processes, such as, for example, welding, whereby sections of the sutures can be fused together upon application of sufficient heat to the sections to cause partial melting and fusion of the sections. Because the direct application of heat to sutures in situ may produce undesirable heating of the surrounding tissue, it is preferred to apply non-thermal energy to the suture material in situ to induce localized heating of the suture material in the areas or sections to be fused. In particular, ultrasonic energy may be effectively applied to sections of suture materials to induce frictional heating of the sections in order to fuse or weld them together.
While sutures typically fail under tensile loads applied along the principal axis of the suture, suture welds often fail in shear, i.e., in the plane of the fused region between the overlapped segments of suture material. It is desirable to have the failure strength of the suture joint be at least as great as the failure strength of the suture material away from the joint.
U.S. Pat. No. 5,417,700 to Egan and U.S. Pat. No. 3,515,848 to Winston et al. disclose apparatus and methods for ultrasonic welding of sutures. The Winston et al. patent discloses, for example, the application of mechanical energy to a segment of material to be joined in either of two different directions. For joining plastic suture materials, mechanical energy is applied in a direction substantially parallel to the axis of the segments to be joined. For joining metallic suture materials, mechanical energy is applied in a direction substantially normal to this axis. The Winston et al. patent further discloses the use of a spherical welding tip for use in joining metallic suture materials.
Although ultrasonic welding of sutures is known, it has heretofore been difficult or impossible to control the suture welding process in order to produce suture welds of sufficient strength and reliability to replace, or enhance the strength of, suture knots or other loop closure devices.
It is therefore an object of the present invention to overcome the disadvantages inherent in prior art suture loop joints and joining processes.
SUMMARY OF THE INVENTION
The present invention provides a fused loop of an elongated material, such as a polymeric or monofilamentous suture material, which has a strength in the joint region which is at least equal to, if not greater than, the strength of the parent material. The present invention also provides means for controlling the size and shape of the fused portion of the joint region in order to maximize joint strength.
According to one aspect of the invention, there is provided a fused loop of an elongated material comprising one or more segments of the material which extends along a principal axis. Portions of the segments are joined together to form a loop at a joint region which extends between first and second ends. The joint region includes a first portion of elongated material extending from the first end, a second portion of elongated material extending from the second end, and a fused portion or layer between and joining the first and second portions at points between the first and second ends of the joint region. The fused portion preferably comprises a relatively thin layer of fused material from the first and second portions.
The term “fused”, as used herein, refers to material which has been heated to a plastic or fluid state and subsequently allowed to cool, so that the relatively highly-oriented molecular structure of the parent material is transformed into a relatively randomly-oriented molecular structure characterizing the fused portion of the joint region. The term “shear area”, as used herein, refers to the area of the fused portion between and substantially parallel to the segments of material joined in the joint region. In contrast, the cross-sectional area of the segments or the fused portion refers to the area in a plane substantially transverse to the principal axis of the segments.
The elongated material in the first and second portions of the joint region is characterized by a relatively high degree of molecular orientation in the direction of the principal axis of the material, and thus relatively high strength in the direction of the principal axis. The fused material in the fused portion of the joint region is characterized by a relatively random molecular orientation, and thus relatively low strength in the direction of the principal axis of the material. The cross-sectional area of the first and second portions of the segment at the first and second ends of the joint region, yet outside of (i.e., not abutting) the fused portion, is greater than the cross-sectional area of the first and second portions of the joint region which abut the fused portion.
In one embodiment, the cross-sectional area of the first and second portions of the segment at the first and second ends of the joint region, yet outside of the fused portion, is approximately equal to the cross-sectional area of a segment of the elongated material outside of the joint region.
In a preferred embodiment, the total cross-sectional area of the first and second portions of the joint region which abut the fused portion is a minimum at approximately the midpoint of the fused portion. In a more preferred embodiment, the total cross-sectional area of the first and second portions of the segment at the midpoint of the fused portion is approximately half the total cross-sectional area of the first and second portions at the first and second ends of the joint region and outside of, or not abutting, the fused portion. In an especially preferred embodiment, the change in cross-sectional area of the first and second portions of the segment, per unit length of those portions, is substantially constant over the length of the fused portion of the joint region.
The elongated material may comprise a substantially monofilamentous material, such as, for example, a polymer. In a preferred embodiment, the elongated material is a thermoplastic polymer, such as a surgical suture material.
The segments of elongated material are preferably joined in a weld at the joint region. The weld can be effected with various types of energy, such as, for example, ultrasonic, laser, electrical arc discharge, and thermal energy.
The loop of elongated material can be made by joining portions of a single segment of the elongated material. Alternatively, the loop can be ma
Egan Thomas D.
Fenton, Jr. Paul V.
Axya Medical Inc.
Chaudhuri Olik
McDermott & Will & Emery
Trinh (Vikki) Hoa B.
LandOfFree
Fused loop of filamentous material and apparatus for making... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fused loop of filamentous material and apparatus for making..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fused loop of filamentous material and apparatus for making... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2860186