Surgical suture abstract
The invention relates to a surgical suture which can be used for
stitching together extensive skin deformations or skin areas desired
to be surgically removed or in view of preventing the expansion
of the scar of conventional surgical wounds. Therefore, the suture
of the invention is made of silicone elastomer having a visco-elastic
elongation of more than 50%, preferably more than 100% and an elongating
force of only 1-20N when the elongation is 100%.
Surgical suture claims
I claim:
1. A surgical suture used for stitching a surgical wound in such
a manner that the suture pierces a tissue at the edge of a wound,
characterized in that the suture made of silicone elastomer has
thickness within the range of 0.5 to 3 mm, has a visco-elastic elongation
of from about 50% to greater than 100% and the elongating force
is within the range of 1-20N when the elongation is 100%.
2. A surgical suture as set forth in claim 1 characterized in
that the suture has a break elongation from about 500% to about
700%.
3. A surgical suture as set forth in claim 1 characterized in
that the suture has a breaking strength from about 500N/cm.sup.2
to about 800N/cm.sup.2.
4. The surgical suture as set forth in claim 1 characterized in
that over a range of application of the suture, wherein the suture
stitched onto a wound has an elongation of 5-100%, the suture has
a stress-strain curve which is nearly linear such that, as the edges
of a wound draw closer to each other, the suture retains a wound
closing force.
5. The surgical suture as set forth in claim 4 characterized in
that the suture has a break elongation from about 500% to about
700%.
6. The surgical suture as set forth in claim 4 characterized in
that the suture has a break elongation from about 500% to about
800N/cm.sup.2.
7. The surgical suture as set forth in claim 4 characterized in
that the suture has a breaking strength from about 500N/cm.sup.2
to about 800N/cm.sup.2.
8. The surgical suture as set forth in claim 4 characterized in
that the suture has a breaking strength in excess of 800N/cm.sup.2.
9. The surgical suture as set forth in claim 1 characterized in
that the suture has a breaking strength in excess of 800N/cm.sup.2.
Surgical suture description
BACKGROUND OF THE INVENTION
The present invention relates to a surgical suture which can be
used for stitching up even extensive skin areas or skin deformations
to be surgically removed or which can be used for precluding the
expansion of the scar of conventional surgical wounds.
It is prior known that extensive deformations of skin areas can
be surgically removed and the resulting tissue-devoid area can be
closed by means of mechanical devices, described e.g. in Patent
publications U.S. Pat. No. 5263971 EP-648093 and WO 93/21849
as well as by means of tissue expanders. The question is about the
removal of skin deformations or the removal of a bald scalp area.
However, the above-mentioned devices are expensive and inconvenient
to use.
On the other hand, a problem with conventional surgical wounds
is the expansion of scar in several portions of the body as the
suture migrates in a certain manner within tissues gradually therethrough
and the tissue extends and the scar may expand.
Patent publication U.S. Pat. No. 5147382 discloses a surgical
suture having a useful yield elongation within the range of 2-9%
and a visco-elastic elongation of 10-30% as well as a break elongation
of 20-45%. The curves shown in FIGS. 1 and 2 of the publication
indicate that the discussed filament has a stiffness which, even
within the range of elastic elongation, is at least one order in
excess of that of the present invention. A curve C depicted in FIG.
2 of the application corresponds more or less to this prior known
case.
Even though the publication discloses the use of silicone elastomer
as one of several alternatives the suture is excessively stiff to
be used in the purpose of the invention for stitching together extensive
removable skin areas or, in terms of conventional surgical wounds,
for preventing the expansion of a scar for the reason that the suture
or filament migrates through the tissue.
SUMMARY AND OBJECTS OF THE INVENTION
An object of the invention is to provide a surgical suture which,
on the one hand, is suitable for stitching together extensive sections
of skin to be removed and, on the other hand and in terms of conventional
surgical wounds, is capable of preventing the expansion of a scar.
This object will be achieved by means of a surgical suture of the
invention on the basis of the characterizing features set forth
in the annexed claim 1. The non-independent claims disclose preferred
embodiments for the invention.
BRIEF DESCRIPTION OF THE DRAWING
The invention will now be described in more detail with reference
made to the accompanying drawings, in which
FIG. 1 shows an extensive skin-area wound which is stitched together
by means of a suture of the invention and
FIG. 2 illustrates stress-strain curves A and B for a suture of
the present invention in comparison with a stress-strain curve C
for conventional surgical sutures.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1 a skin area wound 10 bordered by skin edges
12 and 14 is sutured together by means of suture 16 secured in a
known manner by piercing the skin adjacent edges 12 and 14.
The suture material used for stitching a surgical wound is silicone
elastomer. This type of suture or filament has a break elongation
in excess of 500%, typically in excess of 700% and the filament
has a breaking strength in excess of 500 N/cm.sup.2 typically in
excess of 800 N/cm.sup.2. In view of an object of the invention,
the filament diameter or thickness varies within the range of 0.5-3
mm. The filament cross-section may be circular, polygonal or flat.
The suture or filament stitched onto a wound may have an elongation
which varies within the range of 0-100%. If the intention is to
close extensive skin-area wounds, as in FIG. 1 the elongation is
first typically within the range of 30-50% but, if necessary, may
be more than that. Thus, as the edges of a wound draw closer to
each other, the suture retains a wound closing force. When the suture
is used in conventional surgical wounds, which do not involve the
removal of extensive skin areas, the suture or filament may have
a lower elongation but, even then, the continuing tensile stress
of the filament prevents expansion of the scar.
The steepness of a stress-strain curve can be affected by adjusting
the stiffness of elastomer by varying the mixing proportions of
components and the number of catalysts or inhibitors. Depending
on the stiffness of a filament material and the thickness of a filament,
the filament or suture elongates 100% when the force is within the
range of 1-20 N. This range of elongation and force can be used
for handling wounds of varying sizes and in various types of tissue.
A suture of the invention offers a higher efficiency and a wider
range of application than the prior known devices for stitching
together extensive skin-area wounds. In addition, the suture of
the invention is substantially more inexpensive. The types of silicone
suitable for manufacturing the suture have been commercially available
for a long time from various manufacturers. Monofilament sutures
of a desired thickness are obtained by extruding silicone paste,
prior to its final polymerization, through orifices of a suitable
size. |