Surgical Thread and Surgical Device

Abstract

A surgical thread and a surgical device. The surgical thread includes at least two adjacent elongated elements that are connected to each other and include filament fibers such that a maximum cross-sectional diameter of the thread is substantially greater than the cross-sectional diameter of the thread in the direction perpendicular to the maximum diameter, and the elements are connected by a structure that is arranged to be broken at least at the ends of the elements such that the thread can be divided into single elements. The surgical device includes a needle and a surgical thread attached to the surgical needle.

Description

In the following, the invention will be described by means of an example and with reference to the appended drawings, in which

FIG. 1 illustrates a known technique for fixing a tendon, modified Kessler,

FIG. 2 shows a single element belonging to a surgical thread, and

FIG. 3 shows a surgical thread according to the invention.

FIG. 1 illustrates a known technique for fixing a tendon, modified Kessler. According to this technique, the tendon can be fixed by using only one thread loop formed of a surgical thread 7 to connect the parts 5 and 6 of the tendon. For connecting the ends of the thread loop, an ordinary knot 8 is presented. The span of the surgical thread 7 inside the tendon is shown with a broken line.

FIG. 2 shows a single element 1 of the surgical thread according to the invention. In the case of FIG. 2, the element 1 comprises two partial elements 2 twisted around each other. The partial elements 2 have been made of several filament fibers 3. The filament fibers 3 are degradable under tissue conditions, preferably poly-D-L-lactide fibers.

FIG. 3 shows a surgical thread according to the invention, comprising parallel elements 1. In the case of FIG. 3, the number of parallel elements is three. The elements 1 may be of the type shown in FIG. 2, although this is not necessary. The structure connecting the elements 1 comprises, in the case of three parallel elements 1, two connecting threads 4, each having been wound around two elements in an alternating manner so that both connecting threads have been wound around the middle element 1 and the connecting threads 4 intersect at the middle element 1, and the connecting thread 4 proceeds all the time with a given pitch in the longitudinal direction of the elements 1. The directions of rotation of the connecting threads 4 are opposite to each other. The single connecting thread 4 has been wound around two elements in such a way that if the connecting thread 4 has been wound clockwise around the first element 1, it has been wound counterclockwise around the second element 1. Naturally, the directions of rotation may also be the other way around, but it is essential that the direction of rotation always changes when proceeding to the next element. When the connecting threads 4 are viewed in a direction perpendicular to the longitudinal direction of the elements 1, the connecting threads form a pattern with the shape of the number 8.

After a tendon has been fixed, for example, by the technique shown in FIG. 1 by forming a thread loop between the damaged parts of the tendon, a suitable length of the connecting threads 4 can be unwound around the elements 1. Thus, the ends of the elements can be tied one by one, wherein three small knots are formed instead of one large knot, which make better mobility and healing of the tendon possible.

EXAMPLE

The values presented in this example are values obtained from sterilized material (25 kGy being the minimum dose of gamma radiation used for sterilization). Because it is difficult to measure the cross-sectional area of a tendon fixing in a reliable way, making it more difficult to define the strength, maximum forces have been used as the variables, instead of strength values.

The filament fibers were made by melt spinning of poly-L/D-lactide (PURASORB®, manufactured by PURAC Biochem B.V., Holland; the inherent viscosity being 4.98 dL/g and the ratio of D/L isomers=96/4). The diameter of the obtained filaments with a circular cross-section was 0.08 to 0.09 mm. The maximum loading capacity of a single filament was about 2 N (drawing speed 30 mm/min, 50 mm drawing span).

An element was made of 12 filaments, to have a maximum loading capacity of about 20 N (drawing speed 20 mm/min, 50 mm drawing span) and a diameter of about 0.5 mm.

A flat surgical thread was made of three elements by joining the elements with two connecting threads, each consisting of two filaments (see FIG. 3). The connecting threads were made of the same material as the elements. The maximum loading capacity of the finished surgical thread under drawing was about 60 N (drawing speed 20 mm/min, 50 mm drawing span), and the smaller diameter was smaller than 0.7 mm and the larger diameter was smaller than 1.7 mm.

The performance of the above-mentioned surgical threads was tested with a tendon model. The tendons used in the testing were extensor tendons of rear cloven hooves of frozen slaughter swine, their size corresponding to the size of the flexor tendon of a human finger. When the tendon was fixed with the surgical thread according to the invention, the average maximum loading capacity of the fixing was about 80 N (drawing speed 20 mm/min, drawing span 35 mm).

For comparison, corresponding tendons were fixed with commonly used suture techniques by using a commercial suture thread. Under drawing, the following results were obtained for the maximum loading capacity:

Six-filament Savage 4-0 with Ticron 76 N,

four-filament Savage 3-0 with Ticron 68 N,four-filament Savage 4-0 with Ticron 56 N,modified duplex Kessler 3-0 with Ticron 68 N, andmodified Kessler 3-0 with Ticron 35 N.

In a dynamic endurance test, the tendon fixing made by a flat surgical thread according to the invention endured an average of 4000 cycles of a 35 N load, followed by 4000 cycles of a 45 N load, before the fixing seam was opened by one millimetre (extensor tendon of rear cloven hooves of slaughter swine, frequency lower than 1 Hz, drawing span 35 mm). The opening of one millimetre is considered the critical gap encumbering the healing of a tendon.

The above-described facts do not restrict the invention, but the invention may vary within the scope of the claims.

Claims

1-10. (canceled)

11. A surgical thread, comprising: at least two adjacent elongated elements which are connected to each other and comprise filament fibers in such a way that a maximum cross-sectional diameter of the thread is substantially greater than a cross-sectional diameter of the thread in the direction perpendicular to the maximum cross-sectional diameter; anda connecting structure connecting the elements, wherein the connecting structure is arranged to be broken at least at ends of the elements such that the thread can be divided into single elements.

12. The thread according to claim 11, wherein the elements comprise more than one filament fiber.

13. The thread according to claim 12, wherein the elements have been divided into partial elements comprising filament fibers, the partial elements being twisted around each other.

14. The thread according to claim 10, wherein the connecting structure comprises connecting threads arranged to tie the elements together.

15. The thread according to claim 10, wherein the connecting structure comprises a film connecting the elements.

16. The thread according to claim 10, wherein the thread comprises three adjacent elements connected by a structure comprising two connecting threads, of which a first connecting thread is wound around a first and a second of the elements in an alternating manner, and a second connecting thread is wound around the second and a third of the elements in an alternating manner in such a way that the first and the second connecting thread intersect at the second element.

17. The thread according to claim 10, wherein the thread comprises a material that is degradable in tissue conditions.

18. The thread according to claim 17, wherein the thread comprises a polymer, copolymer or polymer mixture that is degradable in tissue conditions.

19. The thread according to claim 18, wherein the material degradable in tissue conditions is a poly-α-hydroxy acid.

20. The thread according to claim 19, wherein the material degradable in tissue conditions is poly-D-L-lactide.

21. A surgical device, comprising: a surgical needle; anda surgical thread attached to the surgical needle, the surgical thread comprising at least two adjacent elongated elements that are connected to each other and comprise filament fibers such that a maximum cross-sectional diameter of the thread is substantially greater than a cross-sectional diameter of the thread in the direction perpendicular to the maximum cross-sectional diameter, and the elements are connected by a connecting structure that is arranged to be broken at least at the ends of the elements in such a way that the thread can be divided into single elements.