JPS59131348A - Prosthetic material for tensile load support tissue and production thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to prosthetic materials for ligament or ligament replacement or repair.

PRIOR ART A commonly employed ligament and key repair procedure involves the use of tissue transplanted from elsewhere in the body to the defect site. This remedial measure often fails due to a number of factors. These factors include insufficient strength of the transplanted tissue, dependence of transplanted tissue growth on vascular regeneration, and insufficient attachment or fixation strength of the transplanted tissue.

There is a great need for damaged ligament and mt-replacement prostheses, and numerous attempts have been made in the past to provide such prostheses.

However, there are no prosthetic materials that are widely used today. Causes of prosthesis failure include insufficient tensile strength, insufficient fixation, deterioration of the device due to mechanical compression, and deterioration of the interface between the prosthesis and tissue. Sometimes.

Previously attempted bone and soft tissue attachment methods include: U.S. Pat. Nos. 3,971,670 and 4,127,90.
No. 2, No. 4,129,470, No. 3,992,725
No. 4,149,277. These patents teach attachment by tissue ingrowth to the porous surfaces of the prosthesis.

U.S. Patent Nos. 3,613,120 and 3,545,00
No. 8 and No. 4,209,859. These patents teach methods of attaching tissue to porous fabrics by various means of maintaining attachment to the repair tissue.

U.S. Patent Nos. 3,896,500 and 3,953,89
No. 6, No. 3,988,783 and No. 4,301,5
No. 51. These patents teach attachment to bone by rigid mechanical devices such as screws, threads or other devices.

SUMMARY OF THE INVENTION As extensively described herein, a prosthetic material according to the present invention is made of porous polytetrafluoroethylene (P) formed by concentric loops of continuous filaments.
TFE). The prosthesis is immediately attached post-operatively by means of a necessary eyelet formed at the end of the tied and consolidated loop which can be fixed directly to the bone tissue. This initial attachment is strengthened as tissue grows into the porous strand material, eventually becoming redundant and providing permanent attachment of the prosthesis.

In order to achieve the said object, as described extensively herein, according to the present invention, the entire prosthesis is connected to at least one eyelet for initial attachment to the bone tissue subjected to tensile loads. A method of manufacturing a tensile load-bearing tissue prosthesis of the type having a large number of parallel, longitudinally adjacent strands is to elongate the desired strands from continuous filaments until a desired number of parallel strands are obtained. forming a number of elongated concentric loops, where the concentric loops define a protruding elongated area, and then the loops define a single elongated area to form an eyelet; The method also includes a fixing process to prevent the ends of the joined loops from becoming separated.

Preferably, the method includes the additional step of twisting the looped strands around the longitudinal axis of the prosthesis. The present invention will be better understood by reference to the drawings. However, these drawings are for illustrative purposes only and are not intended to limit the scope of the invention and should be read in conjunction with the specification.

FIG. 1 in the margin below is a graph illustrating the logarithm of stabilized tissue ingrowth and maximum thickness of the strands of the prosthesis of the present invention as a function of the % characteristic gap size.

FIG. 2 is a photomicrograph of the PTFE material used in the construction of the prosthesis of Example B.

FIG. 3 is a photomicrograph of the PTFE material used in the construction of the prosthetic material of Example C.

FIG. 4 is a photomicrograph of the material of FIG. 3 laterally stretched to measure characteristic gap dimensions.

FIG. 5 shows a schematic perspective view of one prosthesis constructed according to the invention.

FIG. 6 schematically depicts the implantation of an anterior cruciate ligament prosthesis not constructed in accordance with the present invention.

Figure 7 shows one of the prosthetic materials of the present invention.
This is a schematic depiction of the process of this method.

FIG. 8 shows a schematic perspective view of another prosthetic material constructed according to the present invention.

FIG. 9 is a perspective view schematically depicting steps in another method of constructing a prosthetic material of the present invention.

FIG. 10 is a schematic perspective view of yet another prosthesis constructed in accordance with the present invention, and FIGS. 11A, 11B and 11C depict the prosthesis of FIG. FIG. 2 is a perspective view showing an anterior cruciate ligament prosthesis implanted in a knee joint.

SUMMARY OF THE INVENTION The article of the invention described herein is a prosthetic material for ligament or lock replacement or repair. The prosthesis is made of multiple strands of porous PTFE. The porosity of the strands is characterized by a continuous pore area. The size of the strands is small enough to allow tissue to grow within and through the strands. The porosity or porosity of the pores is greater than 30% to provide sufficient adhesion for mechanical attachment of tissue in the interstitial space of the prosthesis. This porosity is required only for those parts of the prosthesis that are intended to be securely fixed by tissue anchorage.

Porosity as used here is defined as ρ2 %porosity = [1−]X100 ρ1 where ρ2 is the density of the porous material and ρ1 is the solids content of the porous material. This is the density of formation. ρ1 for unsintered PTFE is 2.3 gmlan6, and for the sintered material the value of fd 2.2 grl'm is used as ρ1. However, this value actually varies somewhat depending on the sintering and cooling conditions.

Rapid post-surgical attachment of the present invention is provided by the eyelet, which is directly attached to the bone tissue. This initial attachment is promoted and eventually strengthened as tissue grows into the porous strand material, resulting in permanent attachment of the prosthesis to the tissue. Tissue can easily grow between the strands because the strands are not attached to each other or held tightly together. However, the depth to which the tissue can grow into each strand is determined by the size of the open pores or passageways within the porous microstructure.

A complex open pore region is formed by the solid PTFE matrix. In some cases, the matrix is formed of large rigid nodes interconnected by flexible, relatively inelastic filaments. Although the nodes may provide a rigid, inflexible structure to the ingrown tissue, the fibrils can be bent and displaced by the invading tissue. Nine other microstructures of the present invention have smaller nodes that appear simply as fibril junctions. In both cases, the tensile strength of the fibrils is very high. Although fibrils can be bent by tissue, they cannot be significantly stretched. The microstructures of the present invention can be characterized by average pore size, which is used to infer the depth of ingrowth tissue. The short fibril length hinders and delays tissue penetration. Thus, for porous strands with short length fibrils, the overall strand size must be small enough so that ingrowth and attachment occurs throughout the strand.

The method used here to characterize the fibril length of a unique microstructure is by visual inspection of that microstructure. Photographs at appropriate magnifications can be obtained by scanning electron microscopy or, in some cases, by optical microscopy.

The porous PTFE materials of the present invention can vary sufficiently in their microstructure that various means must be used to measure the characteristic pore size. Strauss fibers as produced by the method described in axis B have a microstructure distinctly characterized by nodes interconnected by fibrils. The characteristic gap dimensions for this type of material can be determined by direct measurements of the interplanar spacing. This measurement is carried out along a straight line located in the direction of force conduction (FIG. 2). In order to properly characterize the spacing, a sufficiently large number of measurements must be taken. The average nodal spacing thus obtained is used to characterize the interstitial space and thereby infer the depth of ingrowth into the microstructure.

In the strand material produced by the stretching method as described in U.S. Pat. No. 3,962,153 or the product of U.S. Pat. No. 4,187,390, PT
The FE nodes are smaller and can hardly be made obvious. In the highly elongated products manufactured by these patents,
The spacing between the nodes is very large, and the fibrils are packed together. The sintering step in the manufacture of these materials causes the bundles of fibrils to loosen and form secondary attachment points. For this reason, the microstructure of such materials is not easily apparent even under magnification. To measure the characteristic gap dimensions of these materials, it is necessary to measure the distance between the fibril suspension points, rather than measuring the length of the fibrils (i.e., the nodal space). The gap dimensions of these materials can be observed when preparing the specimen for microscopy by stretching the material slightly at right angles to the direction of force conduction. Using a sample with reduced longitudinal shrinkage, fibril attachment points are revealed by microscopic examination when the sample is stretched 10% in the transverse direction. Therefore, the distance between fibril connections is measured at all apparent gaps formed between fibril bundles. This measurement is taken in the direction of the force. In the same way as in the method described earlier for node spacing,
The fibril suspension distance measurements must be sufficient in number to characterize the pore size of the microstructure.

Figure 3 shows how this type of material has no lateral extension compared to Figure 4, a photomicrograph of the same material with 10% lateral extension. Lateral stretching, which is used only to characterize the microstructure of the material, represents a temporary structural readjustment. When this material is subjected to a longitudinal force, it returns to its original lateral dimensions and restores its original microstructure. As mentioned above, the nodes that make up this microstructure are believed to be displaced by ingrown tissue. A method for measuring the characteristic gap size for this type of material is shown in FIG. Once the characteristic gap size is determined by the method described above, the appropriate size of the strand can be determined.

FIG. 1 shows the relationship between the characteristic gap size and the depth of tissue ingrowth into the microporous strands of the invention. The abscissa in FIG. 1 relates to the maximum depth of tissue penetration into the microstructure of the desired characteristic gap size, regardless of implantation time. This relationship is obtained from the results of numerous experiments with many types of implants. All of these implants are available in U.S. Pat. No. 3,953,566 and U.S. Pat.
, 153 or as described in Example B in '.

The maximum thickness of the strand that provides tissue penetration throughout the strand is approximately twice the depth of tissue penetration.

The maximum thickness of the strand is represented by the right ordinate in FIG. As used herein, thickness is the appropriate minor cross-sectional dimension of the strand, such as the circular cross-sectional diameter of the strand, or the thickness of the longitudinal cross-section of the strand. In general, a combination of a characteristic gap space dimension and a strand thickness below the curve is preferred as it quickly completes tissue penetration across the strand cross-section. A preferred combination can be determined by the following relationship.

For CID value > 7μ, 120μ, tn (strand diameter) < 2.28 x 10-2 (CID)-
For 4,36CID value>120μ, tn (strand diameter)<, 6.9 s x 1o
-2(CID)-9,94 where CID is the characteristic gap dimension in microns, tn is the natural logarithm, and the strand diameter is given in inches.

The depth of tissue penetration into the porous structure decreases rapidly as the characteristic gap size decreases below 10 microns. This reduction is due to the fact that in the characteristic spacing and smaller spacing structures described above, there are fewer interstitial passageways large enough to accommodate single cells of the desired type. At characteristic spatial dimensions of 120μ and larger, substantial vascularization is accompanied by tissue ingrowth, greatly increasing the depth of penetration. This is thought to cause the relationship between the gap size and the depth of tissue penetration to increase in a gradient manner, as shown in FIG.

The main ingredient for a successful ligament or key prosthesis is a prosthesis with adequate strength. In many cases, prosthetic materials used to replace these natural structures are subjected to very high tensile loads. In some cases, the prosthesis must be many times stronger than the maximum load that will be placed on it to compensate for the time-dependent root-like properties of the prosthesis.

From a mechanical strength standpoint, those of ordinary skill in the art will understand that the number of individual strands that are modeled for a particular application depends on several factors. These factors include the cross-sectional area of the individual strands, the tensile strength of the individual strands, and the tensile forces required for the particular application, including the safety factor of deformation strain limits. The individual strands used in the present invention are described in U.S. Patent No. 3.953.5.
No. 66, U.S. Pat. No. 3,962,153 or Example B below. In order to minimize the overall size of the device, it is desirable to use high tensile kamatric materials, thereby minimizing the size of the drill hole in the bone into which the device is to be installed.

The tensile strength of the matrix refers to the strength for porous specimens of the polymer, as described in U.S. Patent No. 3.95.
3.566.

In a preferred form of the invention, - the strand material has a matrix tensile strength greater than 20,000 psi, a porosity greater than 30%, and interconnected channels formed by knot and fibril boundaries; It is a porous PTFE with a microstructure characterized by.

- The size of the strands and the characteristic gap dimensions of the microφ structure are selected such that tissue ingrowth throughout the strand occurs quickly.

- Each strand and final component has the necessary and sufficient strength to meet all the mechanical requirements of the particular application.

Uniparallel strands result from multiple loops formed from continuous filaments of strand material.

- The ends of the multiple loops are brought together and shaped into at least one eyelet for attachment to bone tissue.

The equalization of the load on the prosthetic material strands subjected to one tensile force is
1. Minimize the difference in length of the loops used to form parallel strands.

2. Compressing the loop strands in the eyelet area to bring about strand-to-strand attachment.

The monoprosthesis also includes means for distributing tensile loads to each strand as the prosthesis moves in a radial range, the means including:

1. Screw in the vertical axis of the strand bundle.

2. Loosely woven strands.

- Although the ligament prosthesis embodied in Figure 10 is shown as having a pair of opposing eyelets consisting of elongated loops, the present invention is formed with loops tied together for attachment to bone. It also includes a single eyelet 324 that is inserted. The other end 316 of the knot is loose or flared so that it can be attached to soft tissue, such as muscle tissue, by suturing, for example. In the latter case, the closed loop ends provide additional resistance to the threading of the strands after stitching.

The non-prosthetic single eyelet embodiment 310 may find use in arm repair or replacement.

Example A This example shows a prosthesis in which the strand thickness was too large relative to the gap dimensions characterizing the microstructure and satisfactory strength was not achieved (FIG. 1). The strand thickness (diameter) was 0.26 inches, the porosity was about 80%, and the characteristic gap size was about 78 microns. This gap size was determined as shown in FIG.

This prosthesis was used to completely replace the anterior cruciate ligament in dogs by placing it through drilled holes in the tibia and femur. The prosthetic material strands 6 are placed in the original ligament position 2
Four drill holes were drilled in the tibia 2 and femur 4 to form one loop of material with two strands (Figure 6). Initial fixation was performed by tying the ends of the strand together at knot 8 to form one continuous loop. Ingrowth and formation of tissue into the interstices of the microporous material was expected to increase the initial fixation force and distribute pressure to the surrounding tissue. Each strand that crossed the knee joint had a tensile strength of approximately 550 pounds. Therefore, the combined force of these two strands was 1,100 pounds. After being implanted for 260 days, the knee joint was removed.

Drill holes T6 were made in the tibia and femur for attachment to the tensile test tube. After removing all collateral support structures around the knee, the femur was separated from the tibia along the axis of the prosthetic ligament at a constant rate of 500 vrtn per minute until failure. The length of the intra-articular space between the bone tunnels represents the portion of the prosthesis under tensile loading due to tissue attachment to the prosthesis within the bone tunnel during testing. The mode of failure of this device system was rupture of the prosthesis at a location outside the bone tunnel. Surprisingly, this cleavage occurred at a value of only 200 pounds.

By histological investigation, we found that this strength reduction was related to the fact that bone ingrowth into the prosthesis was generally restricted to depths below I If. With strands of this diameter and characteristic gap size, attachment occurs only on the annular portion of the surface of the prosthesis. This reduced area therefore becomes the only loading material of the prosthesis when tension is first applied; failure occurs first in the peripheral annulus of the material and then progresses through the center of the prosthesis. .

EXAMPLE B The experience cited in Example A has shown that tissue ingrowth must penetrate the entire cross-section of the strand in order to obtain adequate long-term device strength. Therefore, prostheses were constructed using strands with similar porosity and characteristic gap dimensions, but of much smaller diameter. The strand material used in the construction of the anterior cruciate ligament prosthesis of this example was manufactured as follows.

PTFE dispersion powder (ICI America r Ftu o
nCD i 23 J resin) was mixed with 130 Cc of PTFEI per pound of rIsOPARKl odorless solvent (manufactured by Exxon Corporation) and compressed into pellets with a diameter of 0.
It was molded into a 108 inch rod. This was done using a piston extruder with a reduction ratio of 96:1 from sphere to shaped rod in cross-sectional area.
r K vessel at 60° C. and extended to 8.7 times the original length between the capstans at an output rate of about 86.4 feet per minute. The diameter of the capstans was approximately 2.8 inches and the center-to-center distance was approximately 4.5 inches. The diameter of the bar was reduced from about 0.108 inch to about 0.04 inch by this stretching. I 5opar K was then removed from this extension.

Next, this extensible rod was pulled through a circular compression mold heated to 300°C. The mold opening tapered at a 10 degree angle from about 0.050 inch to 0.025 inch 9 and then remained constant at a length of about 0.025 inch.

The output rate of material exiting the mold was 7.2 feet per minute.

The extensible bar was then brought into contact with a heating drive capstan and heated to 300° C. at 6.57°C per minute. These capstans had a diameter of 2.75 inches and a center-to-center distance of 4.5 inches.Finally, the rods were de-shrinked and exposed for 30 seconds in an air oven at approximately 367°C.Final In morphology, the fibers produced by this method had the following characteristics:

Diameter = 0.026 inches Matrix Tensile Strength = 74,000 Pat Porosity = 80.8% Characteristic Gap Size = 74μ Below Margins Place the prosthesis 10 on a shelf (not shown) as shown in FIG. It consisted of two steel spools 42°44 mounted on. This spool was supported on posts 46.48 with a center edge-to-edge spacing of 14 crn. These steel spools were threaded so that one flange was removed by removing Ye and υ. The strands of PTFE were passed through the two spools 80 times to tie a total of 160 strands to the two spools.

Both ends of the fiber were tied with multiple square knots. One spool was removed from the post, rotated 180°, and reattached to the post.

This provided a half turn of the thread about the longitudinal axis of the construct. This construct was then wrapped with a thin film of PTFE at three locations, each for a total of 25 turns. This membrane is disclosed in U.S. Patent No. 3,
It was manufactured according to the teachings of No. 962,153 and had the following characteristics:

Width = 0.375 inches Thickness = 0.00025 inches Longitudinal Matrix Tensile 9 Strength = 70,000 p
si porosity = 84% The strand bundle is placed at two points 28 adjacent to the spool 42.44
．． The thin film was wrapped at 30 to form small holes 24, 26 at both ends of the construct (FIG. 8).

The center point 38 was also wrapped with a membrane. The two spools were then removed from the support and placed on a thin metal wire plate designed to prevent rotation and longitudinal shrinkage.

The shelves were then exposed to 375° C. for 6 minutes in an air oven. After cooling, the spools were removed from both ends of the construct. The site of the spool provided an eyelet through which the ligamentous prosthesis construct could be attached to the bone with screws or other suitable fixation means. All parts wrapped in membrane were compressed by shrinkage of the membrane during heat treatment. Then I joined the strands together. During the heating cycle described above, some fiber-to-fiber adhesion occurred even in the unwound areas. The fibers were then separated individually using a metal peck rod. The construct thus consisted of 160 strands of microporous PTFE connecting two eyelets of somewhat densified material. The prosthesis 10 has a 180-degree angle along the tensile load direction to better distribute the tensile load to the strands 20.
It had a screw thread of °. A PTFE tape wrap 38 surrounding the strand 20 and located approximately centrally between the ends 14.degree. 16 of the prosthesis serves to protect the strand 20 from untwisting and maintain the thread 9 intact during implantation.

As in the case of PTFE winding 28.30, winding 38
is intended to be placed external to the bone contacting surface so as not to inhibit tissue ingrowth into the strand 20.

The device manufactured by the method described above was implanted in the knee of a sheep to replace the resected anterior cruciate ligament (Fig. 11A,
(See Figures 11B and 11C).

This implantation was accomplished by drilling one A-inch hole in both the tibia and femur. The hole in the tibia was drilled along the native anterior cruciate axis that had been removed earlier, and the socket was exposed to the side. A hole in the femoral region was opened on the lateral distal femoral surface proximal to the femoral maxilla. The tunnel was angled so that the hole exit was created near the center of the lateral femoral beam at the level of the femoral knee. The prosthesis 10 was guided from the femoral exit side through the intercondylar space, across the intra-articular space, and through the tibial tunnel. The eyelets 24,26 and the rolled portions 28', 30 towards the ends of the component were placed so as to be located outside the bone drill tunnel. The central rolled portion 38 of the component was placed in the intra-articular space. Next, prosthetic material 1
It was fixed to the bone with a self-threading orthopedic screw 32.34 passed through the 01 eyelet 24.26. The knee joint was confirmed to be stable immediately after surgery.

Three months after implantation, the knee was removed from the animal, holes were made in the tibia and femur, and a miko was attached to the holes to perform an axial tensile test of the ligament structure/component.

After removing the muscle tissue and dissecting the collateral support structures of all knee joints, the femur was separated from the tibia with a break trench at a constant speed of 500 Tra per minute. The equipment system was damaged in 642nd. The ligament prosthesis broke at the small hole where it was secured to the femur. When the load exceeded the fixation provided by the ingrowth of tissue into the intraosseous portion, dehiscence occurred and the fixation screw also dehisced.

The device failed due to unwinding of the strand material in the eyelet area after several strands were broken. Histological observation of this sample showed ingrowth between and within the strands of tissue.

Tissue ingrowth had progressed completely through several strand diameters. We expect that the trabeculae will exhibit complete and thorough ingrowth of most strands at longer implantation times.

Example C The thin film of expanded PTFE used as the strand material in this embodiment was manufactured by E., 21921 Maryland.
lekton Three Blue Ba1l Ro
ad % W, L, Gore an located at P.O. Box 1010
d As8ociates.

Inc., Textiles Division, product number Y10383. This membrane had the following properties.

Width = 0.25 inches Thickness = 0.0010 inches Matrix Tensile Strength = 93,400 bonds/square inches Porosity = 50 inches Characteristic Gap Size = 11.0 microns From the manner in which the prosthetic ligament failed as described in Example B: It was found that improvement in the bonding between the strands in the small hole area is desired. Accordingly, a method of construction with some modifications to the method of Example B was employed for the prosthesis 110 shown in FIG.

Four spools 141, 142, 143 and 144i were mounted on shelves (as shown). The spool is on the shelf, 9
It was supported by posts 145, 146, 147 and 148 positioned to form a rectangle measuring cm x 5 cm (Figure 6). These steel spools have one 7
I cut the threads so that I could remove it with a run. PTFE
A total of 60 strands of wood were wrapped around these four threads.
It was circulated. A strand of thin PTFE material was twisted 20 times around the longitudinal axis of the strand during one rotation of four threads. Then tie both ends of the continuous strand to one side of the bundle.
They were tied together at the midpoint on the cTn side.

The 3.5 crn width at each midpoint 150 and 152 on the 5 crn side was compressed into a rectangular cross section of 0.058 inch by 0.150 inch using a mold. During compression, the mold was heated to 360°C and immediately cooled. This pre-compression step is necessary to facilitate placement of the construct into the eyelet compression mold. Next, the center 1-inch portion of the pre-compression area is covered with a PTFE thin film.
I rolled it 5 times. This membrane was manufactured according to the teachings of US Pat. No. 3,962,153 and had the following characteristics.

Width = 0.375 inches Thickness = 0.0O025 inches Machine direction matrix tensile strength = 70,000 p
si porosity = 84% Next, remove this device and set the center distance to 14cr++02
The book was placed on a two-post shelf (similar to Figure 7) with steel bottles of books so that the center of the pre-compressed, thin-film-wrapped portion was at the center of the bottle. Referring to FIG. 10, two parallel pre-compression sections were assembled adjacent to each bin, and points 128,130 were wrapped a total of 25 times using expanded PTFE membrane of the type described above.

Both ends 114, 116 of the component were placed into the final eyelet forming mold. Next, the small holes 124 and 126 were compressed in the mold to a calculated specific gravity of 2.2, and immediately heated at 360°C for 10
Heated for minutes then cooled. Removed from the hole-forming mold, the component was twisted 180° about its longitudinal axis and remounted on a two-post shelf.

Next, the 0.4-inch width 138 at the middle part of the small holes 124 and 126 was tightly wrapped with the above-mentioned thin film to form 25 layers, and compressed with a heated cylindrical mold to a calculated specific gravity of 2.2. The compression was maintained at 360° C. for 10 minutes, then cooled and removed from the mold. Thus, as shown in Figure 1O, the present component consists of 120 microporous PTFE strands 120 connected to two small holes 124, 126 formed by a dense strand material and a multilayer PTFE membrane.
It got better. , EllJa, J--mostly the goal was to maintain the integrity of the remaining strands so that one or more strands could do their job. This densification also provides a more even strand load under tension. The purpose of the 1800 screw thread in the strand bundle was to provide a well-balanced strand load as the implanted bundle moved within the radius of the femoral condyle within the intercondylar space.

The purpose of the compressed section in the center of the strand bundle was to help retain the embedded mid-machine torsion.

We found that the loosely woven strands located on the longitudinal axis also help distribute the tensile forces to the strands, and the 180
I think it could be used as a substitute for screws.

Those skilled in the art would know how to construct a loose strand braid.

The brace R manufactured by the above-mentioned method was implanted in the knee of a sheep to replace the excised anterior cruciate ligament. This embedding was achieved using the technique described in Example B (first
(See Figure 1). Six months after implantation, the reconstructed knee will be removed and tested for tensile strength as previously described. The results of this test indicate that the tensile force of this device system is expected to be at least 600 Bonds, provided that no extraneous bone fails before the ligament reconstruction fails. Furthermore, this tensile force value is expected to be achieved due to the presence of tissue attachment to the individual fibers contained within the bone tunnel. It is expected that histological observations will show substantial tissue formation between and invading the individual strands 6 months after implantation.

[Brief explanation of drawings]

FIG. 1 is a logarithmic graph of the stabilized tissue ingrowth and maximum thickness of the strands of the prosthetic material of the invention as a function of the characteristic gap size, and FIG. 2 shows an example of the invention. FIG. 3 is a micrograph of a PTFE material (fibrous) used in the construction of a prosthetic material, and FIG. , FIG. 4 is a photomicrograph of the material of FIG. 3 (fibrous) stretched laterally to measure the characteristic gap dimensions, and FIG. 5 is a photomicrograph of one prosthetic material constructed according to the invention. FIG. 6 is a perspective view schematically depicting the implantation of an anterior cruciate ligament prosthesis not constructed according to the present invention, and FIG. 7 is a perspective view of one prosthesis of the present invention. FIG. 8 is a perspective view schematically showing the process of one method of constructing the material; FIG. 8 is a schematic perspective view of another prosthetic material constructed according to the present invention; FIG. 10 is a perspective view schematically showing steps in another method of constructing one prosthetic material of the present invention, and FIG. 10 is a schematic perspective view of yet another prosthetic material constructed according to the present invention. 11A, 11B, and 11C are perspective views showing the prosthesis of FIG. 8 implanted in a knee joint as an anterior cruciate ligament prosthesis. 6... Strand, 8... Yusushi, 10... Prosthetic material, 24.26... Small hole, 20... Strand, 30
, 38...Makibe, 120...Strand, 12
4,126...small hole, 141-143...thread winding. The following is an engraving of the blank drawings (no changes to the contents) FIG. 1-11 Procedural amendment (method) February 2, 1982; 1981 Patent Application No. 165326 2. Name of the invention: Prosthetic material for tensile load-bearing tissue and its manufacturing method 3. Person making the amendment. Relationship with the case. Patent applicant 4. Agent (4 others). 5. Order for amendment. Date - January 31, 1980 (Delivery date) 6. Subject of amendment (11Ha, "Representative of applicant" column (2) Power of attorney (3) Drawing 7, Contents of amendment (1+, ( 21 Attachment circular (3) Engraving of drawings (no change in content) 8 List of attached documents (1) Request for correction 1 copy (2) Power of attorney and translation 1 copy each (3) Engraved drawings 1 copy

Claims (1)

[Scope of Claims] 1. Longitudinal adjacent and parallel microporous polytetrafluoroethylene material having continuous pores bounded by nodules and fibrils at the site where attachment to the tensile support tissue is required. If the thickness of each strand is made up of unattached strands, the thickness of the material is such that tissue ingrowth can occur substantially across the entire strand thickness. If the material is selected in conjunction with the structure, and the characteristic gap dimension of this material is greater than approximately 7μ and the thickness of the strand is determined by the following correlation, if CID>7μ, ≤120μ. For tn (strand diameter) ≦6.98X10-2 (CID)
-4,356 CID≧120μ, tn
, 94 (where CID is the characteristic gap dimension (in microns), An is the natural logarithm, and the strand diameter is in inches). , said loop is formed of continuous filaments of said material, said strands are brought together to form a hole at least at one end of said elongated region, and said strands are brought together to form a hole under tension. The product may be initially attached to the bony tissue under tension, and the product further includes means for restraining the ends of the gathered loops to prevent dispersion. A product manufactured for use as a tensile load-bearing tissue for connection between donor tissues. 2. The article of claim 1, wherein two opposing eyelets are formed by the ends of the converged loops. 3. The product according to claim 4 or 2, wherein each of the small holes is a strand portion glued together so as to apply a uniform load. . 4. A tension-loading device having a plurality of parallel longitudinally adjacent strands connected and spaced apart from at least one eyelet in which the prosthesis is initially attached to the bone tissue subjected to the tension-loading. A method for manufacturing a prosthesis of such tissue, comprising the following steps: a) placing a number of spaced pin means to define an elongated area according to the required size of the prosthesis; b. forming a number of elongated loops from continuous filaments of the desired strand material in the windings of a number of bin means until the desired number of parallel strands is obtained;
and a step of gathering the ends of the loops at one end of the elongated area to form a small hole C (this gathering step includes a step of fixing the ends of the gathered loops to prevent the gathered loops from dispersing). Good manufacturing method. 5. If the prosthesis is intended to be moved in a radial range, twisting the looped strands of the longitudinal axis of the prosthesis to distribute the load more evenly. The manufacturing method according to claim 4, further comprising: 6. The manufacturing method according to claim 5, wherein the loop-shaped strand is twisted by about 180°. 7. The method further comprises the step of forming the looped strands into a loose braided structure so as to distribute the load more evenly when the prosthesis is used to be moved in a radial range. manufacturing method. 8. having a plurality of parallel, longitudinally adjacent strands connected and spaced apart from at least one eyelet in the receptacle for initially attaching the prosthesis to the bone tissue subjected to tension;
A method for manufacturing a prosthetic material of a tissue subjected to a tensile load, the method comprising:
Steps of IL''e as follows: a. A number of bin means are spaced apart to define the elongated area according to the required size of the prosthesis; b. The desired number of parallel strands is obtained. forming a plurality of elongated loops from a continuous filament of the desired strand material to the circumference of this plurality of pin means, and looping at one end of the elongated region to form an eyelet. A manufacturing method other than the step of gathering together the ends of the loop (this gathering step includes a step of fixing the gathered loop ends to prevent the gathered loops from being separated),
The above-mentioned manufacturing method includes the step of compressing and heating the converged ends at a temperature and time sufficient to fuse the terminal ends of the loops. 9. The claim also includes a preliminary step of wrapping a strand of high-strength material in a direction tangential to the axis of the prosthetic material at a position adjacent to the eyelet of the gathered end to prevent dispersion. The manufacturing method described in item 4 or item 8. 10. High strength material has matrix tensile strength of approximately 70.0
00 psi foamed polytetrafluoroethylene. 11. The manufacturing method according to claim 8, wherein the gathered ends are compressed and heated in a die having the desired shape and size of the holes.