Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Peptide containing doai
Reexamination Certificate
2001-01-25
2003-06-24
Henley, III, Raymond (Department: 1614)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Peptide containing doai
C514S021800, C606S002000, C606S008000, C606S213000, C606S214000
Reexamination Certificate
active
06583117
ABSTRACT:
TECHNICAL FIELD
The present invention relates to methods for joining living tissues, including veins, arteries, microvessels, tubes, nerves, organ tissues and biological surfaces, such as peritoneum, omentum, fascia, shin, artificial tissues, and to pharmaceutical products useful in joining these tissues.
BACKGROUND ART
Joining tissues such as veins, arteries, microvessels, tubes, nerves, tissues and biological surfaces such as the peritoneum and skin has mainly been carried out clinically to date by suturing and microsuturing.
Microsuturing requires considerable skill and is a time consuming procedure. Frequently, tissues which have been joined by microsuturing form considerable scar tissue. Some of the difficulties encountered with microsuturing can be better understood by considering the example of rejoining damaged peripheral nerve tissue.
Peripheral Nerves
The electrical signals that control the body's organs and transmit information back and forth to the central nervous system (CNS) travel along peripheral nerves. The structure of these peripheral nerves is analogous to telephone cables. In a telephone cable there is a strong protective outer coating that protects all the inner components. The copper wires are often grouped in separate insulating tubes that lead to different systems. Each of the inner copper wires is a single line that can transmit electricity in either direction and has an insulating coating around it so that it does not interfere with the lines next to it.
A peripheral nerve (
FIG. 1
) has an outer membrane consisting of connective tissue such as collagen. This membrane (epineurium) protects and holds the separate nerve bundles together. The nerve bundles which lie inside this membrane are called fascicles. These fascicles also have a collagen based surrounding membrane and their task is to group together nerve axons supplying a similar area of the body. Inside the fascicle membrane the axons are surrounded by loose connective tissue. The axons are a long extension from a cell body which is contained within the CNS in the spine or the brain. Sensory axons transmit to the CNS and motor axons transmit from the CNS. Nerve metabolism is sustained by the vascular system from both outside the nerve and along the centre of the nerve.
Peripheral nerves can have very small diameters. For instance, the mature median nerve at the wrist is approximately 1 cm in diameter and contains an average of forty fascicles, each of which can contain up to 4500 axons. When a peripheral nerve is cut all axons distal to the wound change their properties as axon flow is cut off from the cell body. Even when the nerve is reconnected, these axons continue to degenerate distally. The Schwann cells which normally wrap themselves around the axons as insulation guide regenerating axons. Joining nerves as accurately as possible by lining up corresponding fascicles enables the axons to more efficiently regenerate.
Operating upon nerves has been facilitated by using magnification and special microsurgical equipment. Accurate repairs need to be effected at the fascicular level ensuring that regeneration is along the correct bundle leading to the original area those axons supplied. The current technique of peripheral nerve repair uses microsuturing (FIG.
2
). This technique requires a dedicated, trained surgeon as microsuturing of just one of the many fascicles with three or more microsutures (using say a 70 micron diameter needle and 30 micron thread) can take very long operating times.
Microsuturing is at present clinically used where the skills are available. Unfortunately, there are relatively few surgeons who have the necessary manipulative skills for operating at high magnification. Even a reasonable microsuturing technique results in long operating times with added damage to the inner axons due to sutures penetrating the thin insulating perineurial sheath. The use of sutures results in some scarring of the repair due to foreign body reaction. There is also evidence which indicates that in the long term scar tissue formation and scar maturation can lead to impairment of the joined nerve.
Work has been performed on the use of lasers alone in effecting nerve joins. One of the problems of laser welding has been the fact that the intact gel-like nerve tissue of the axons is actually under pressure within the fascicle. When the fascicle is cut this material extrudes. This can lead to the direct laser weld being formed on nerve tissue rather than the surrounding membrane of the fascicle, causing nerve damage. To date the welds have typically been made using infrared lasers such as CO
2
lasers which rely on water absorption for energy transfer. Tissue preparation before welding relies on overlapping the nerve membranes. This is difficult due to the extruding gel-like axons and so can lead to denaturation of the nerve axon material. The affected tissue tends to scar and the fibrous tissue that proliferates as a result is a poorer electrical conductor than nerve tissue. The bonds formed to date as described in the prior art using laser welding have typically lacked strength. These laser joins alone tend to fail so microsuturing has been used in addition to welding to strengthen these joins.
To deal with at least some of the deficiencies of laser welding, various glues have been used in forming the welds. These low protein concentration, fluid glues tend to run between the ends of the nerve that are being joined which may result in damage to the axoplasm of the nerve fascicle and also hinder regeneration. They are also applied around the join which is then circumferentially welded. These joins later show thick scarring which causes stricture of the nerve. Moreover, the joins tend to be weak.
The welding techniques so far available also tend to lack precision. Factors that influence the precision of this approach adversely include differences in: the consistency of the glue used; the aperture of the needle or other device used to apply the glue; and the pressure exerted in applying the glue.
DESCRIPTION OF THE INVENTION
The present invention provides a method for joining tissue comprising:
aligning and abutting edges of the tissue to be joined;
applying a solder, across the aligned and abutted edges; and
exposing the solder to an energy source under conditions which provide a transfer of energy from the source to the solder to cause the solder to bond to the tissue surface adjacent the edges thus providing a weld holding the edges together.
In addition to causing the solder to bond to the protein of the underlying tissue, the energy transfer can affect the structure of the solder itself leading to bonding within the solder and an enhancement of the strength of the solder and hence the join.
Drops of solder are typically used where the solder is a fluid solder, and are “painted” across the edges.
The solder can also be provided as a preformed solid strip.
The energy source is typically a laser.
A variety of tissue types can be joined using this method. The method is applicable to anastomoses of biological tubes including veins, arteries, lymphatics, nerves, vasa efferentia, fallopian tubes, bile ducts, tubes of the alimentary canal, the ureter, the urethra, tear ducts, bronchi and any other such bodily tubes as well as to repairs of incisions or tears of biological organs such as kidneys, liver or spleen, or of biological surfaces such as the peritoneum and skin. It will therefore be understood that the method can be used in a variety of join situations including the joining of cylindrical anastomoses and the closure of linear defects such as incisions.
Where the tissue repair is with respect to nerve tissue or other tissue tubes where the tube contents need to be protected from damage, it is especially important that the weld should not be concentrated on the edges being joined as this can damage extruded tissue. Rather, the weld should be distributed across the planar or tubular surface in which the discontinuity lies.
Where the tissue to be repaired is an essentially hollow body tube
Dawes Judith Margaret
Lauto Antonio
Owen Earl Ronald
Piper James Austin
Trickett Rodney Ian
Delacroix-Muirheid C.
Henley III Raymond
Howson and Howson
The Microsearch Foundation of Australia
LandOfFree
Method of tissue repair does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of tissue repair, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of tissue repair will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3143488