Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
  • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
  • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
  • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
  • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
  • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
  • A61B17/72—Intramedullary pins, nails or other devices
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
  • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
  • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
  • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
  • A61B17/72—Intramedullary pins, nails or other devices
  • A61B17/7283—Intramedullary pins, nails or other devices with special cross-section of the nail
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/04—Hollow or tubular parts of organs, e.g. bladders, tracheae, bronchi or bile ducts
  • A61F2/06—Blood vessels
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/08—Muscles; Tendons; Ligaments
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/40—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material
  • A61L27/44—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material having a macromolecular matrix
  • A61L27/48—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material having a macromolecular matrix with macromolecular fillers
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
  • A61L31/12—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material
  • A61L31/125—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material having a macromolecular matrix
  • A61L31/129—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material having a macromolecular matrix containing macromolecular fillers
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
  • A61L31/14—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
  • A61L31/148—Materials at least partially resorbable by the body
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/3094—Designing or manufacturing processes
  • A61F2/30965—Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
  • A61F2002/30108—Shapes
  • A61F2002/30199—Three-dimensional shapes
  • A61F2002/30261—Three-dimensional shapes parallelepipedal
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
  • A61F2002/30108—Shapes
  • A61F2002/30199—Three-dimensional shapes
  • A61F2002/30291—Three-dimensional shapes spirally-coiled, i.e. having a 2D spiral cross-section
  • A61F2002/30298—Parallelepipedal body made by spirally rolling up a sheet or a strip around itself
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2230/0063—Three-dimensional shapes
  • A61F2230/0082—Three-dimensional shapes parallelepipedal
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2230/0063—Three-dimensional shapes
  • A61F2230/0091—Three-dimensional shapes helically-coiled or spirally-coiled, i.e. having a 2-D spiral cross-section

Definitions

• implants or their parts o components- which are manufactured at least partially of a absorbable polymer and/or of a polymer composite containing reinforcing elements, for fixation of bone fractures, osteotomies or arthrodeses, joint damages, tendon and ligamen damages etc.
• Such implants are e.g. rods, screws, plates, intra edullary nails and clamps, which have been described i the professional literatures of material- technique and medicine.
• J. Leenslag, A. Pennings, R. Veth and H. Janse "Bone Implant” describes an implant material fo reconstructive surgery of bone tissue, which material comprises a biodegradable porous polymer material an biodegradable or biostable fibres.
• Self-reinforced absorbable fixation devices have significantl higher strength values than the non-reinforced absorbable fixation devices.
• U.S. Pat. No. 4 743 257, P. T ⁇ rmala, P Rokkanen, J. Laiho, M. Tamminmaki and S. Vainionpaa describes a self-reinforce surgical composite material, which comprises an absorbabl polymer or copolymer, which has been reinforced with absorbable reinforcing elements, which have the same chemica element composition as the matrix.
• the known self-reinforced absorbable surgical composites have certain good mechanical strength properties, they have the disadvantage that the mechanical strength properties are strongly anisotropic.
• the known self reinforced absorbable composites which have been manufacture e.g. with the sintering technique or with fibrillatio (drawing) technique, are parallel reinforced, the bindin forces between, the reinforcing elements are determined by the strength of the matrix and of the boundary surface betwee matrix and reinforcing elements.
• the parallel reinforcin means here that reinforcing elements, like fibres, threads fibrils or bundles of them form parallel structures into the matrix.
• the tensile strength of the reinforcing elements i hundreds or thousands of MPa, but the internal strength of th matrix and of the matrix - reinforcing element boundary i only the order of magnitude of 10-100 MPa.
• the fracture of self-reinforce absorbable composites occurs relatively easily as th delamination between the parallel reinforcing element layer or between the parallel reinforcing elements, when th external forces affect to the implant from such a direction that the reinforcing elements cannot carry those externa forces.
• the delamination means the fracture o the composite material along the matrix between th reinforcing elements or along the boundary surface between th matrix and the reinforcing elements.
• This invention describes self-reinforced, absorbable surgica materials and/or implants and/or their parts and/o components, which can be implanted into the living tissue on its surface for the purpose of e.g. to repair tiss damages, to join tissues or their parts to each other, augment tissues or their parts, to separate tissues or the parts from each other and/or from their surroundings, and/ to conduct material between tissues or their parts and/or out" " of tissues or from the outside into the tissues, for which aelf-reinforced materials and/or implants or their parts and/or components is characteristic that their reinforcing elements are wound at least partially around some axis penetrating the implant.
• the reinforcing elements can be typically oriented molecular chains, molecule chain groups or their parts, oriented crystalline lamellae or spherulites, fibrils or their parts or corresponding morphological structural elements. They can also be fibres, filaments, film fibres, threads, braids, - non-vowen* .structures, networks, meshes, knits or vowen structures or corresponding.
• the reinforcing elements do not form in the materials of the invention coherent straight planar structures, th delamination surfaces in the materials of the invention ar at least partially curved and/or partially or completel eliminated depending on in which way the reinforcing elements have been wound around some axis penetrating the implant.
• the materials of the invention have mor isotropic strength properties than the known self-reinforce absorbable materials and implants have. Therefore the implant of the invention have a better reliability in operation an they have more many-sided applications than the known implant have.
• the invente implants their parts or components contain at least one hole hollow or cavity, around which the reinforcing elements hav -been wound at least partially.
• Such implants have several advantages in comparison to the known ones.
• the implan contains a hole, hollow or cavity or corresponding, the mas of the implant is smaller than the mass of the solid implant This means advantageously a smaller amount of foreign materia in the tissues of the patient in the former case.
• a hole, hollow or cavity increases also the surface area of the implant which accelerates its hydrolysis in living tissues.
• a hollow inside of the implant can be used also to guide the implant into the tissue e.g. with a suitable guiding device. Additionally, a metallic rod, wire etc.
• a self-reinforced absorbable screw of the invention as the screwdriver socket during the implantation of the screw by inserting the tip of the screwdriver into the hole so that the torque force from th screwdriver is divided along the screw axis.
• a consequenc of spiral orientation such screws resist clearly highe torque forces than the known parallel fibre reinforced or non-reinforced absorbable screws because the torque force i received as tensile stresses by the wound reinforcing element which typically have very high tensile strength.
• the torqu forces are received by the screw material mainly as shear forces.
• the implant of th invention is an intramedullary nail, which is at leas partially hollow and where the reinforcing elements hav been wound at least partially around the long axis of the intramedullary nail.
• the cross-sectional form of such a intramedullary nail can be e.g. a circle, an ellipse, triangle, a quadrangle, a polygone or like a four-leave clover, kidney-like etc.
• Figure 1 shows some typica embodiments of the cross-sectional form of the intramedullar nail. It is self-evident that also other forms of the cross section than those given in Figure 1 can be applied in th intramedullary nails of the invention.
• the wall th intramedullary nail contains at least one elongated groove or hole, which has been formed by bending the wall of th intramedullary nail inside or by splitting it at least partially or by making at least one hole into the wall of th implant.
• the elongated groove or hole(s) give to th intramedullary nail flexibility in such an amount that th intramedullary nail does not split easily the bone, when th intramedullary nail is hammered into a tight drill hole insid of the bone.
• Figure 2 shows typical cross-sectional forms of intramedullary nails, which have in their wall a groove, a fissure * ⁇ r holes to increase its flexibility.
• Figure 3 shows some examples in perspective view of intramedullary nails of the invention.
• th intramedullary nail of Figure 3a spirally oriented lines have been drawn, describing the orientation of reinforcin elements.
• the intramedullary nails can include also holes through which they can be fixed into bone e.g. with screws as is show schematically in a cross-sectional Figure 3e.
• fixation devices of the invention can be manufactured o absorbable (biodegradable or resorbable) polymers, copolymers, polymer mixtures or composites which have been described in many publications, like e.g. in the following inventions: U.S. Pat. No. 3 297 033, U.S. Pat No. 3 636 956, U.S. Pat. No. 4 052 988, U.S. Pat. No.4 343 931, U.S. Pat. No. 3 969 152 U.S. Pat. No. 4 243 775, FI Pat. Appl. No. 85 5079, FI Pat. Appl. No. 86 0366, FI Pat. Appl. No. 86 0440 and FI Pat. Appl. No.. 88 5164.
• Table 1 gives some known biodegradable polymers, which ca be used as such or as mixtures as raw materials of th implants of the invention both as matrix material (as binding polymer) and/or as reinforcing elements. Table 1. Absorbable polymers
• Glycolide/L-lactide copolymers PGA/PLLA
• Glycolide/trimethylene carbonate copolymers PGA/TMC
• the implants of the invention can be manufactured o absorbable polymers or copolymers by using one polymer o polymer mixture.
• the devices can be reinforced in addition to self-reinforcing also with fibres which are manufacture of other resorbable polymer or polymer mixture or with fibre which are manufactured of a resorbable ceramic materia (like with ⁇ -tricalciumphosphate fibres or with CaAl-fibres; see e.g. EPO Appl. 146 398) and/or with biostable fibres like glass-, " carbon- or polymeric fibres.
• the devices of the invention can contain also layered part comprising e.g. (a) a flexible surface layer which increase the toughness of the implant and/or acts as a hydrolysi barrier and (b) a stiff inner layer.
• the surgical devices of the invention can be manufactured o absorbable polymers and of possible absorbable and/o biostable reinforcing fibres by means of different method like with methods known in plastics technology. Such method are e.g. injection moulding, extrusion as such or combined with fibrillation and forming (see e.g. FI Pat. Appl. No.
• the devices of the invention can be manufactured from th above raw materials also by means of so called solution techniques.
• at least part of the polymer is dissolved i a suitable solvent or it is plasticized with a solvent an the material or material mixture is compressed to a devic or preform by means of pressure and possibly applying heat so that the dissolved or plasticized polymer glues the material to a macroscopical sample, from which the solvent ca be removed by evaporation.
• the devices of the invention can include additionally different kind of additives or auxiliary materials to facilitate the processing of the material (e.g. stabilizators, antioxidants or plasticizers) or to chang its properties (e.g. plasticizers or powder-like cerami materials or biostable fibres like polyaramide-or carbo fibres), or to facilitate its use (e.g. colours).
• additives or auxiliary materials to facilitate the processing of the material (e.g. stabilizators, antioxidants or plasticizers) or to chang its properties (e.g. plasticizers or powder-like cerami materials or biostable fibres like polyaramide-or carbo fibres), or to facilitate its use (e.g. colours).
• the devices of th invention contain some bioactive material or materials, lik antibiotic or chemotherapeutic additives facilitating th healing of the wound, growth hormone, antifertilizatio additive, anticoagulant (like heparine) etc.
• bioactive implants are especially advantageous in clinical use, becaus they have in addition to the mechanical function als biochemical, medicinal etc. effects in different tissues.
• the materials of the invention have good mechanica properties, they can be processed mechanically into differen forms.
• the plate preforms can be rolled, compressed stamped, upset, bent etc. either when cooled to a temperatur below the room temperature or at the room temperature or a an elevated temperature. They can be processed also b drilling, grinding, milling etc. or with other methods of mechanical processing or by other methods like lase processing or water jet cutting or ultra sound cutting.
• Th rods and tubes of the invention can be processed also wit the corresponding methods. E.g.
• the torsional load carrying capacity of the spiral reinforced rod was measured by fixing the ends of the rod into a torsional strength measurement device and by winding the other end of the rod in the same direction where the spiral reinforcement had been wound in the rod. As a comparison the torsional load carrying capacity of the parallel thread reinforced rods was measured. The maximum force of torsional load was for spiral reinforced rods 18 N and for parallel thread reinforced rods 10 N.
• Melt spinning and (hot) drawing method was applied t manufacture fibres of the following absorbable polymers: poly-L-lactide (Mw 260 000, L-lactide/D-lactide copolymer (molar ratio 90/10), glycolide/lactide copolymer (molar ratio 90/10) and poly- ⁇ -hydroxy butyrate (Mw ca. 700 000).
• the polymers were manufactured by Boehringer/Ingelheim (Germany), CCA biochem (Holland) and ICI (England).
• Example 1 According to the principles of Example 1 the above fibres were applied to manufacture spiral reinforced and parallel reinforced absorbable (self-reinforced) rods by the sintering technique.
• the torsional load carrying capacity of each rod was measured according to the method of Example 1.
• the torsional load carrying capacities of the spiral oriented rods were 1.3-2 times higher than those of parallel fibre reinforced rods.
• Dexon R -sutures (size USP 1) were applied to manufacture absorbable, self-reinforced screws with the following dimensions: the total length 120 mm, the diameter of the screw core 6 mm, the length of the threaded part 20 mm (in the tip of the screw), the maximum thread diameter 8 mm, the maximum diameter of the head 9 mm.
• the length of the mandrel was 140 mm.
• the maximum thickness of the mandrel was 3 mm at the one end and 2 mm at the other end.
• SUBSTITUTESHEET mandrel was a square.
• the filament wound preform was cut t the length of 125 mm and it was sintered to a headless scre preform with the 20 mm long thread part at its tip leavin the metal mandrel inside of the screw preform.
• the above screw mould was applied.
• the head was upset with th compression moulding technique to the other end of the scre preform (to the end where the metal mandrel was thicker) .
• the screw head was upset in such a way that the metal mandrel was uncovered 5 mm.
• the metal mandrel was drawn out of the screw, which left inside of the screw a square hol penetrating the screw.
• the torsional load carrying capacity of the spiral oriente screw was measured by pushing into the hole inside of th screw a long tip of a screwdriver which fitted tightly int the hole.
• the handle of the screwdriver and the tip of the thread part of the screw were fixed to the torsional strengt measurement apparatus and the torsional load carrying capacit was measured by winding the handle of the screwdriver aroun its long axis until the screw broke.
• a similar measuremen was done for parallel thread reinforced screws.
• the torsiona load carrying capacity of the spiral reinforced screws was 1. times higher than that of the parallel thread reinforce screws.
• Linen weave type fabric was woven of glycolide/lactide suture (Vicryl R , size 1 USP) by using Vicryl sutures both as warp an weft yarns.
• the fabric was rolled up to a ca. 8 mm thick an 40 mm long roll, which was flattened to a 5 mm thick fla roll which was pushed into a compression mould cavity wit dimension 5 x 15 x 40 mm which was open from one long, narro side.
• a suitable rectangular steel plate was compressed on th fabric roll, the mould was evacuated and the fabric wa sintered at ca. 180°C (time 10 min, pressure 2000 bar) to self-reinforced rod with dimensions 5 x 5 x 40 mm and with square cross-section.
• a layered rod was made for compariso by filling the mold with (5 x 40 mm) Vicryl fabric strip and by sintering them together.
• Figure 5a shows schematically a rod according to th invention.
• a spiral orientation of the fabric has been described with a thick spiral line at the end of the rod an the positions of the warp and weft yearns on the surface o the rod have been described with thin lines.
• Figure 5b show the corresponding layered rods with the fabric layers in vertical position. (During the compression of this rod the fabrics were in a horizontal position. )
• Compression moulding technique was applied to manufacture of poly-L-lactide (Mw ca. 700 000, manufacturer CCA biochem, Holland) 5 mm thick plates, which were drawn and rolled at an elevated temperature (rolling temperature > 90°C) to 0.4 mm thick films.
• a 30 mm wide piece of the film was heated to ca. 90°C and rolled according to Figure 5a to a roll which was sintered to a spiral oriented rod with dimensions 5 x 5 x 30 mm in the mould of Example 4 at temperature 175°C.
• the layered rod according to Figure 5 b was manufactured by filling the cavity of the mould of Example 4 with 5 x 30 mm big strips which were cut from the drawn and rolled film.
• the drawin was repeated for the drawn prefom by using an other die wit the hole tip diameter of 1.2 mm.
• the final self-reinforce (parallel fibre reinforced) rod had the diameter of 1.15 mm.
• the rod was cut into 20 mm long pieces. Part of the rods were transformed to spiral reinforced by winding the ends of the rods at the opposite directions at 90°C tempereature so tha the final orientation of the reinforcing fibrils deviated ca. 45° from the direction of the long axis of the rod.
• Th torsional load resistance of spiral reinforced and paralle reinforced rods was measured at room temperature.
• the spira reinforced rods had about 1.4 times higher torsional load carrying capacity in comparison to the parallel fibre reinforced rods, when the spiral oriented rods were loade in the same direction where the spiral reinforcement wa oriented.
• the dimensions of the rods were: the length 60 mm the diameter 4.8 mm.
• the mandrel was removed from the inside of the tube and anothe mandrel was pushed into the hole inside of the tube. This mandrel had a longitudinal 1 mm deep and broad groove on its surface.
• a schematic cross-sectional Figure 6a shows the self- reinforced tube and the mandrel, which has a longitudinal groove.
• the tube was heated to 110°C and it was deformed with a heated tool so that part of the tube wall yielded into the groove of the mandrel according to the Figure 6b.
• the tube was cooled to the room temperature, the tool and the mandrel were removed giving an intramedullary nail according to the Figure 6c.
• Dexon R sutures (size 1 USP) were braided to three-dimensiona cylindrical, longitudinal braid by so called 3-D techniqu (Figure 7 gives schematically the location of the Dexo sutures in the braid structure).
• the thickness of the brai was ca. 6 mm.
• Corresponding screws were manufactured of Dexon sutures by filling the mould cavity with parallely oriented Dexon threads and by sintering them to screws.
• the 3-D braided screws of the invention showed the torsional strength of 1.4 NM.
• the parallel thread reinforced screws showed the torsional strength of 0.8 NM.
• 3-D braided preforms were manufactured according to Example 8 of PLLA-fibres and of PLDLA-fibres (weight ratio 1:1).
• the preforms were sintered in a cylindrical mould to 120 mm long and 2.6 mm diameter rods at the temperature 175°C.
• the partially threaded rods were cut to 3 mm long pieces and a flat head with the maximum diameter of the head 6 mm was upset to the non-threaded end of the rod b compression moulding in a hot mould (T >100°C).
• a vertical osteotomy was done into the distal end of the femu of a rabbit into the cancellous bone area.
• the osteotomy wa fixed with two screws which were manufactured with the abov method.
• the fixation technique is shown schematically in a anteroposterial view (cross-section) in the Figure 9. Afte one year's follow-up time it was found that the osteotom had healed well.
• Three-dimensional braiding technique was applied to braid o Dexon R sutures (size USP 1) a tube-like preform with the maximum diameter of 3 mm and with the wall thickness of 1 mm.
• the Figure 10 shows schematically the structure of the preform. Part of Dexon threads can be seen at the cut end of the preform.
• a 40 ram long piece of preform was located into the cavity of an injection mould.
• the cavity had the form of a screw (length 40 mm, maximum therad diameter 4.5 mm, minimum thread diameter 3.2 mm, maximum diameter of the flat head 8 mm).
• the mould cavity of the mould was filled with polyglycolic acid (manufacturer Boehringer/Ingelheim, Germany) melt by applying the injection moulding technique (injection moulding machine: model Battenfeldt, Austria) .
• the polyglycolide melt filled the cavity, the medullary cavity inside of the Dexon thread preform and covered also the Dexon preform.
• the cavity was cooled rapidly.
• the same mould was applied to manufacture screws of polyglycolide melt without Dexon thread braid reinforcement.
• the spiral reinforced screws (including the Dexon thread braid) showed the shear strength of 120 MPa and the non-reinforced screws showed the shear strength of 75 MPa.

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• Health & Medical Sciences (AREA)
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• Heart & Thoracic Surgery (AREA)
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• Oral & Maxillofacial Surgery (AREA)
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• 1989
  • 1989-04-26 FI FI891973A patent/FI88111C/fi not_active IP Right Cessation
• 1990
  • 1990-04-24 AU AU55301/90A patent/AU5530190A/en not_active Abandoned
  • 1990-04-24 EP EP19900906234 patent/EP0422177A1/de not_active Withdrawn
  • 1990-04-24 WO PCT/FI1990/000113 patent/WO1990012550A1/en not_active Application Discontinuation
  • 1990-04-24 JP JP50633290A patent/JPH03505537A/ja active Pending
• 1993
  • 1993-12-10 AU AU52332/93A patent/AU5233293A/en not_active Abandoned

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