WO2010006453A1 - Clou médullaire - Google Patents

Clou médullaire Download PDF

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Publication number
WO2010006453A1
WO2010006453A1 PCT/CH2008/000322 CH2008000322W WO2010006453A1 WO 2010006453 A1 WO2010006453 A1 WO 2010006453A1 CH 2008000322 W CH2008000322 W CH 2008000322W WO 2010006453 A1 WO2010006453 A1 WO 2010006453A1
Authority
WO
WIPO (PCT)
Prior art keywords
nail
duct
bonding agent
recited
intramedullary nail
Prior art date
Application number
PCT/CH2008/000322
Other languages
English (en)
Inventor
Meinrad Fiechter
Thomas Sommer
Samuel Maurer
Original Assignee
Meinrad Fiechter
Thomas Sommer
Samuel Maurer
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Meinrad Fiechter, Thomas Sommer, Samuel Maurer filed Critical Meinrad Fiechter
Priority to PCT/CH2008/000322 priority Critical patent/WO2010006453A1/fr
Publication of WO2010006453A1 publication Critical patent/WO2010006453A1/fr

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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
    • 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
    • A61B17/7233—Intramedullary pins, nails or other devices with special means of locking the nail to the bone
    • A61B17/7258—Intramedullary pins, nails or other devices with special means of locking the nail to the bone with laterally expanding parts, e.g. for gripping the bone
    • A61B17/7266—Intramedullary pins, nails or other devices with special means of locking the nail to the bone with laterally expanding parts, e.g. for gripping the bone with fingers moving radially outwardly
    • 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
    • A61B17/7233—Intramedullary pins, nails or other devices with special means of locking the nail to the bone
    • 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
    • A61B17/74—Devices for the head or neck or trochanter of the femur
    • A61B17/742—Devices for the head or neck or trochanter of the femur having one or more longitudinal elements oriented along or parallel to the axis of the neck
    • A61B17/744—Devices for the head or neck or trochanter of the femur having one or more longitudinal elements oriented along or parallel to the axis of the neck the longitudinal elements coupled to an intramedullary nail
    • 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
    • A61B17/70—Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
    • A61B17/7097—Stabilisers comprising fluid filler in an implant, e.g. balloon; devices for inserting or filling such implants
    • A61B17/7098—Stabilisers comprising fluid filler in an implant, e.g. balloon; devices for inserting or filling such implants wherein the implant is permeable or has openings, e.g. fenestrated screw
    • 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
    • A61B17/7216—Intramedullary pins, nails or other devices for bone lengthening or compression
    • A61B17/7225—Intramedullary pins, nails or other devices for bone lengthening or compression for bone compression
    • 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
    • A61B17/84—Fasteners therefor or fasteners being internal fixation devices
    • A61B17/86—Pins or screws or threaded wires; nuts therefor
    • A61B17/864—Pins or screws or threaded wires; nuts therefor hollow, e.g. with socket or cannulated
    • 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
    • A61B17/88—Osteosynthesis instruments; Methods or means for implanting or extracting internal or external fixation devices
    • A61B17/8802—Equipment for handling bone cement or other fluid fillers
    • A61B17/8833—Osteosynthesis tools specially adapted for handling bone cement or fluid fillers; Means for supplying bone cement or fluid fillers to introducing tools, e.g. cartridge handling means
    • A61B17/8836—Osteosynthesis tools specially adapted for handling bone cement or fluid fillers; Means for supplying bone cement or fluid fillers to introducing tools, e.g. cartridge handling means for heating, cooling or curing of bone cement or fluid fillers
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
    • A61B2017/00367—Details of actuation of instruments, e.g. relations between pushing buttons, or the like, and activation of the tool, working tip, or the like
    • A61B2017/00411—Details of actuation of instruments, e.g. relations between pushing buttons, or the like, and activation of the tool, working tip, or the like actuated by application of energy from an energy source outside 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
    • A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
    • A61F2002/30003—Material related properties of the prosthesis or of a coating on the prosthesis
    • A61F2002/3006—Properties of materials and coating materials
    • A61F2002/30065—Properties of materials and coating materials thermoplastic, i.e. softening or fusing when heated, and hardening and becoming rigid again when cooled
    • 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
    • A61F2/46—Special tools or methods for implanting or extracting artificial joints, accessories, bone grafts or substitutes, or particular adaptations therefor
    • A61F2002/465—Special tools or methods for implanting or extracting artificial joints, accessories, bone grafts or substitutes, or particular adaptations therefor using heating means
    • 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
    • A61F2210/00—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2210/0071—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof thermoplastic

Definitions

  • the invention relates to an intramedullary nail for stabilizing a fractured bone, to a device for applying energy to a liquifiable bonding agent of an intramedullary nail, to a method for stabilizing a fractured bone using an intramedullary nail as well as to a hip screw for stabilizing a fractured neck of femur.
  • Intramedullary nails are driven into the medullary canal of the bone and affixed therein by screws or bolts. Often, the cross-section of the intramedullary nail decreases towards the distal end of the nail. After complete healing of the bone at the fracture site, the rod may stay within the bone or it may be removed through a hole drilled in the end of the bone.
  • antegrade nailing the nail is inserted from the proximal end of the bone
  • retrograde nailing the nail is inserted from the distal end of the bone.
  • US 2007/0270833 Al (P. M. Bonutti et al.) relates to a method for stabilizing a fractured bone.
  • the method includes positioning an elongate rod in the medullary canal of the fractured bone and forming a passageway through the cortex of the bone.
  • the method further includes positioning a fastener in the passageway of the cortex and thermal bonding of the fastener to a bonding region of the elongate rod.
  • US 4,369,772 discloses a method for strengthening a fractured bone by drilling a hole along the axis of the medullary canal of the bone, inserting into the hole a substantially inflexible tube having an outside diameter less than the diameter of the hole, injecting into the tube and around the tube a semisolid hardenable mixture of methyl methacrylate and poly(methyl methacrylate), and allowing time for the mixture to harden.
  • This method aims at filling all the interstices and voids in the bone to provide a solid struc- ture.
  • a bone cement such as PMMA
  • filling out all voids between the tube and the bone simplifies the locking of the tube to the bone.
  • injecting the bone cement may be difficult, depending on the geometry of the tube and the surrounding bone.
  • the bone cement has to be injected with a certain pressure. Hardening of the bone cement takes some time which may lead to an extension of the operating time. Furthermore, there is a danger that the bone cement may leak in the region of the fracture.
  • the nail is provided with at least a first duct for at least partially receiving a bonding agent liquefiable by the application of energy.
  • the duct extends continuously from a proximal region of the nail to a distal region of the nail. In the distal region the nail is provided by at least one opening connecting the duct with an outer surface of the nail.
  • the following steps are carried out for stabilizing a fractured bone: a) The intramedullary nail is introduced into the medullary canal of the bone. b) A device for applying energy to the liquefiable bonding agent is inserted into the duct of the intramedullary nail. c) Energy is applied to the bonding agent and the liquefied bonding agent is pressed out through the at least one opening in the distal section of the nail by further advancing the device for applying energy. Thereby, the bonding agent is applied in a region between an outer surface of the intramedullary nail and the bone to be stabilized.
  • the inventive method does not aim at filling all voids be- tween the intramedullary nail and the surrounding bone, but the local application of the bonding agent aims only at producing a form fit between the distal segment of the intramedullary nail and the bone, in particular the trabecular (cancellous bone), where a strong fixation is possible due to the porous structure of the bone. Leaking of the bonding agent in the region of the fracture is avoided because this region is usually not contacted by the bonding agent.
  • the shank portion of the intramedullary nail is usually not to be provided with openings connecting the duct with an outer surface of the nail.
  • the inventive method is particularly well suited in cases where the fracture is at the end of the long bone.
  • the number and placement of openings for distributing the bonding agent within the bone may be chosen in such a way that tight fixation on both sides of the fracture or with all parts of the fractured bone, respectively, is ensured.
  • the inventive nail as well as the corresponding method can be used for human as well as veterinary purposes.
  • the opening (ore in a preferred case, a plurality of openings) may be substantially radial, however, in special cases it may as well be oriented in an inclined fashion.
  • the bonding agent may be provided within the intramedullary nail and/or externally applied during the fixation process.
  • the invention is applicable in antegrade as well as retrograde operation methods.
  • the device for applying energy to the liquefiable bonding agent of the intramedullary nail comprises a neck as well as a tip section to be inserted into the duct of the intramedullary nail.
  • the tip section allows for energy transfer to the bonding agent.
  • the length of the neck as well as its further geometrical properties are chosen in such a way that the tip section of the inserted device may reach the distal region of the nail.
  • Useable kinds of energy are heat, ultrasonic vibrations, other vibrations (such as oscillating rotation), electromagnetic radiation, etc.
  • the tip section comprises a heating element.
  • the heating element is an electrical (resistance) heating element which is supplied by electricity by means of a feed accommodated within the neck.
  • the dissipa- tion of heat is more easily controllable.
  • the heat has to be applied in such a way that the contact surfaces of the bone are not heated above these temperatures whereas at the same time the bonding agent is sufficiently liquefied that it may be pressed out through the opening and that it is able to fill out the structuring of the bone (in particular of the trabecular) in order to achieve a positive fit between the nail and the bone.
  • the bonding agent is liquefied by directly contacting the agent with the heating element.
  • a system for stabilizing a fractured bone comprises an intramedullary nail and a device for applying energy as described above.
  • the nail as well as the device may be adapted to each other, especially concerning their mutual geometry.
  • the intramedullary nail is made from a material having a thermal conductivity of 22 W/mK or less, in particular from titanium, a titanium alloy, steel or fiber-reinforced plastics.
  • a material having a thermal conductivity of 22 W/mK or less in particular from titanium, a titanium alloy, steel or fiber-reinforced plastics.
  • materials with low thermal conductivity avoids that the heat used for liquefying the bonding agent is transferred to the bone in such a way that the bone may be damaged.
  • a titanium alloy may have a thermal conductivity of about 6.7 W/mK, pure titanium is at about 22 W/mK, chirurgical steel at 15 W/mK.
  • Fiber-reinforced plastics allow for a particularly low thermal conductivity.
  • the nail may comprise a heat barrier made from such a material, e. g. in the form of a sleeve, whereas the heat barrier is designed in such a way that the dissipation of heat into further regions contacting the surrounding bone is inhibited.
  • the bonding agent is a bio-degradable thermoplastic material, most preferably an amorphous polymer.
  • Amorphous polymers are preferred, because it is not necessary to heat these materials above the melting point in order to deform them, but only their glass transition temperature has to be reached which usually is considerably lower.
  • a suitable material for the bonding agent is PLLA (poly-L-lactide), an amorphous thermoplastic material having a glass transition temperature of 50 - 80 0 C.
  • PLLA poly-L-lactide
  • other bio-degradable materials that are liquefiable by the application of energy may be employed.
  • materials may be used that are not bio-degradable but biocompatible.
  • the bonding agent may be provided by a therapeutic agent, e. g. with an agent that promotes wound healing.
  • the bonding agent is initially provided within the duct of the intramedullary nail, i. e. the nail is shipped with the bonding agent in place. This ensures that the material and quantity of the bonding agent match the intramedullary nail and the additional step of inserting the bonding agent is spared during the operation.
  • the bonding agent is introduced into the duct prior to inserting the device for applying energy or simultaneously with inserting the device for applying energy.
  • the form fit between the intramedullary nail and the bone may be improved by providing the outer surface of the distal region of the nail with a structuring.
  • the structuring comprises at least one of the following:
  • all these structurings are appropriate for providing a strong fixation of the intramedullary nail to the bone.
  • the structuring assures two-dimensional fixation, i. e. fixation against axial as well as against rotational movement of the intramedullary nail with respect to the bone.
  • the structurings may be produced by techniques that are known as such, as sand blasting, etching, cutting, milling etc.
  • the intramedullary nail may comprise one or several bends. This allows for optimally adapting the geometry of the nail to the geometry of the bone.
  • the neck of the device for applying energy is flexible. This allows for fully inserting the neck as well as the tip even in cases where the inside geometry of the bone is complicated.
  • a heating device having in its tip an electrical heating element which is supplied by electricity by means of a feed accommodated within the neck, is particularly preferred.
  • an internal cross-section of the duct is reduced in the distal region of the nail compared to a shank region of the nail.
  • the internal cross-section of the duct is substantially constant along the length of the nail, and the thickness of the tip of the device for applying energy is correspondingly larger, adapted to the internal cross-section of the duct.
  • the tip of the device may be expandable once positioned in place, e. g. by an umbrella-like mechanism.
  • the intramedullary nail may comprise a second duct for receiving a guide wire.
  • a guide wire into the medullary canal before opening the canal and inserting the intramedullary nail.
  • the wire serves as a guide for the (cannulated) drill, for a cannulated awl or a reaming device.
  • the nail is inserted over the guide wire.
  • the tip section of the device for applying energy has a shape that converges towards a free end of the tip section, whereas the free end section of the tip section is preferably spherical or conical.
  • Such forms greatly facilitate the insertion of the device into the duct of the intramedullary nail.
  • the tip section of the device for applying energy may further comprise a sealing element, in particular on O-ring sealing element. This element will inhibit the passage of liquefied bonding agent to the back of the tip. Its outside diameter is adapted to the inside diameter of the duct in the distal region of the nail.
  • the device for applying energy may comprise a further section allowing for energy transfer to a bonding agent provided in the proximal region of the intramedullary nail, the further section being distant from the tip section. This allows for simultaneously locking (or unlocking) the intramedullary nail in its distal as well as in its proximal region.
  • a distance between the tip section and the further section is preferably variable.
  • the tip section comprises a flexible helical element (having approximately the form of a usual cork-screw) allowing for energy transfer to the bonding agent.
  • a flexible helical element having approximately the form of a usual cork-screw
  • the tip section comprises a plurality of elements, each of which allows for energy transfer to the bonding agent, whereas the elements are mounted in such a way that they are movable in respect to each other. Again this provides for high flexibility without having to reduce the active (i. e. energy-transferring) surface of the tip.
  • the inventive method may further comprise the following steps:
  • the hip screw d) guiding a hip screw through a through-hole in a proximal region of the intramedullary nail, the hip screw having an axial duct provided by a bonding agent liquefiable by applying energy, the duct extending continuously from a proximal region of the hip screw to a distal region of the hip screw and whereas in its distal region the hip screw is provided by at least one opening connecting the duct with an outer surface of the screw;
  • the described hip screw for stabilizing a fractured neck of femur whereas the hip screw is provided with a duct for at least partially receiving a bonding agent liquefiable by applying energy, the duct extending continuously from a proximal region of the nail to a distal region of the screw and whereas in the distal region the screw is provided by at least one opening connecting the duct with an outer surface of the screw, may be used in hip screw applications known from the prior art, i. e. in principle its use is independent from the use of the inventive intramedullary nail.
  • an intramedullary nail being fixed to a bone by a liquefiable bonding agent comprises the step of liquefying the bonding agent by applying energy (e. g. heat) to the bonding agent by a device as de- scribed before.
  • energy e. g. heat
  • the device for applying energy may be mechanically fastened to the intramedullary nail, such that the nail may be removed by retracting the device.
  • This method for removing an intramedullary nail may be used as well in the case of removing hip screws or bolts and screws used to affix a bone plate to a bone, respectively, all being provided with a duct for at least partially receiving a bonding agent liquefiable by the application of energy.
  • Fig. 1 a cross-sectional view of a first embodiment of an inventive femoral nail
  • Fig. 2 a cross-sectional view of a second embodiment of an inventive femoral nail
  • FIG. 3A, 3B cross-sectional views of a first embodiment of an inventive tibial nail
  • Fig. 4 a cross-sectional view of a second embodiment of an inventive tibial nail
  • Fig. 5 a cross-sectional view of a first embodiment of an inventive heating device
  • Fig. 6 a cross-sectional view of a second embodiment of an inventive heating device
  • FIG. 7A-C schematic views of tips of an inventive heating device
  • Fig. 8 a side view of a tip of an inventive heating device
  • Fig. 9 a cross-sectional view of a flexible tip of an inventive heating device.
  • Fig. 10 a cross-sectional view of a tip of an inventive heating device, the tip having a reduced diameter.
  • the Figure 1 shows a cross-sectional view of a first embodiment of an inventive femoral nail.
  • the nail 100 made of titanium has been fully inserted into the intramedullary canal of the femur 1, which is fractured in the region of the femoral head 2 (fracture 3).
  • the nail 100 comprises two sections 100a, 100b being offset to each other by an angle of about 1 r and being connected to each other by a bend 100c. In the given example, the length of both sections 100a, 100b is about equal.
  • the proximal section 100a is provided with a duct 101 which extends into the region of the bend 100c, where it is provided with a plurality of radial openings 102 connecting the duct 101 with the outer surface of the nail 100.
  • the nail 100 may be axially locked by introducing a blank of PLLA (poly-L-lactide) into the duct 101 and by subsequently heating the blank above its glass transition temperature (50 - 80 0 C for PLLA) using a heating device (see below) and pressing the liquefied material out of the openings 102.
  • PLLA poly-L-lactide
  • a hip screw 120 made of titanium is positioned through a corresponding opening 103 in the proximal section 100a of the nail 100, close to the bend 100c.
  • the distal end of the hip screw 120 extends into the femoral head 2, where it is locked.
  • a blank 121 made from PLLA is introduced into a duct 122 of the hip screw 120.
  • locking is established by heating the blank using a heating device 140 and pressing out the liquefied material out of radial openings 123 connecting the duct 122 to the outer surface of the hip screw 120. This leads to a stable form fit between the hip screw 120 and the surrounding region of the femoral head 2.
  • a threaded bolt 104 is screwed into the proximal section 100a of the femoral nail 100, which is provided with a corresponding inner thread.
  • the tip of the threaded bolt 104 contacts the outer surface of the hip screw 120 and thereby inhibits further rotation of the hip screw 120.
  • the proximal openings of both the duct 101 of the femoral nail 100 as well as of the duct 122 of the hip screw 120 are sealed by sealing caps 105 (the sealing cap for the hip screw 120 which is not shown in Figure 1 will be inserted after extraction of the heating device).
  • the sealing caps 105 protect the soft tissue and inhibit bone or tissue growing and occluding the opening created for inserting the femoral nail 100 into the bone.
  • a locking screw may be screwed into the duct 122 of the hip screw in order to compress the fractured segments of the femoral head 2.
  • the femoral nail 100 is locked using a screw 106 which radially traverses the femur 1 and which is accommodated within an opening 107 of the femoral nail 100 arranged close to the distal tip of the nail 100.
  • a screw 106 which radially traverses the femur 1 and which is accommodated within an opening 107 of the femoral nail 100 arranged close to the distal tip of the nail 100.
  • the application area of the hip screw 120 as described in connection with Figure 1 is not restricted to the example shown. Generally, it may be used in most of the known applications of hip screws, especially in connection with locking screws or intramedullary nails that are of the conventional type.
  • the Figure 2 shows a cross-sectional view of a second embodiment of an inventive femoral nail.
  • the nail 200 has been fully inserted into the intramedullary canal of the femur 1, which is fractured in the region of the shaft 4 (fracture 3).
  • the nail 200 made of titanium is provided with a duct 201 which extends along substantially the entire length of the nail 200. Close to the distal end of the nail 200, the duct 201 is provided with a plurality of radial openings 202 connecting the duct 201 with the outer surface of the nail 200.
  • the nail 200 is axially locked on the distal side of the fracture 3 by introducing a blank made from PLLA into the duct 201 and by subsequently heating the blank using a heating device (see below) and pressing out the liquefied material out of the openings 202. This leads to a stable form fit between the nail 200 and the surrounding region of the femur 1.
  • a bolt 220 is positioned through a corresponding opening 203 in the nail 200 for proxi- mally locking the nail 200.
  • the distal end of the bolt 220 is locked by introducing a blank made from a thermoplastic material into a duct 222 of the bolt 220. Again, locking is established by heating the blank using a heating device and pressing out the liquefied material out of the radial openings 223 connecting the duct 222 to the outer surface of the bolt 220. This leads to a stable form fit between the bolt 220 and the surrounding region of the femur 1.
  • Figures 3A, 3B are cross-sectional views of a first embodiment of an inventive tibial nail.
  • the nail 300 has been fully inserted into the intramedullary canal of the tibia 10, which is fractured in the region of the shaft 1 1 (fracture 12).
  • the nail 300 made of titanium comprises two sections 300a, 300b being offset to each other by an angle of about 14°, the sections 300a, 300b being connected to each other by a bend 300c.
  • the geometry of the nail 300 is adapted to the geometry of the tibia 10.
  • the tibial nail 300 is provided with a duct 301 which extends about substantially the entire length of the nail 300.
  • the duct 301 is provided with a plurality of first radial openings 302 in the distal section 300b, close to the distal end of the nail 300, as well as with a plurality of second radial openings 303 in the proximal section 300a.
  • the openings 302, 303 connect the duct 301 with the outer surface of the nail 300.
  • the nail 300 is axially locked on the distal as well as on the proximal side of the fracture 12 by introducing a blank made from PLLA into the duct 301 and by subsequently heating the blank using a heating device (see below) and pressing out the liquefied material out of the openings 302, 303.
  • a heating device see below
  • the corresponding process is described in more detail below.
  • the duct 301 of the tibial nail 300 may be sealed by means of a sealing cap, or a locking screw may be screwed into the tibial nail 300.
  • the Figure 4 shows a cross-sectional view of a second embodiment of an inventive tibial nail.
  • the tibial nail 400 mostly corresponds to the one described above, in connection with Figure 3. Distally, it is locked in the same way as the tibial nail according to the first embodiment. However, proximal locking is effected using screws 410, 41 1, 412 traversing the tibia and accommodated in corresponding radial openings 413, 414, 415 in the tibial nail 400.
  • the middle opening 414 is elongated whereas the other openings 413, 415 have a circular cross-section.
  • locking bolts having a duct and openings connecting the duct with the outer surface of the bolts, similar to the bolt described above, in connection with Figure 2.
  • This allows for locking the bolts using a thermoplastic material such as PLLA providing for a form fit between the bolt and the surrounding bone.
  • the tibial nail 400 is distally fixed as described above, inserting a heating device into the duct 401.
  • the midle screw 41 1 is inserted into the elongated opening 414.
  • the further two screws 410, 412 are set. It is to be noted that it may not be necessary to have three screws for proximal lock- ing. in some cases two screws or a single screw (preferably a screw accommodated in an elongated opening) will suffice.
  • the Figure 5 is a cross-sectional view of a first embodiment of an inventive heating device.
  • the tip section 51 1 of the heating device 510 may be inserted into the duct 501 of the intramedullary nail 500.
  • the device 510 comprises a handle 512, a power supply (not displayed), an elastic neck 513 and a tip section 51 1 connected to the distal end of the neck 513.
  • the tip section 51 1 comprises a resistance heating element 514 and a contact element 515 being in thermal contact.
  • the electrical power for the heating element 514 is provided by means of conductors contained within the neck 513.
  • the shape of the contact element 515 is adapted to the geometry of the duct 501 of the intramedullary nail 500. Its axial dimension is rather small in order to facilitate the insertion of the tip section 51 1 , especially to facilitate the passing of bends of the intramedullary nail 500.
  • a blank of a biodegradable thermoplastic material such as PLLA is introduced into the duct 501.
  • the tip section 51 1 of the heating device 510 is introduced into the duct 501 until the contact element 515 contacts the blank. Now, the heating element 514 is heated.
  • the thermoplastic material 505 accomodated within the duct 501 and being contacted by the contact element 515 is liquefied, and the device 510 may be further introduced into the duct 501 using the handle 512, thereby pressing out the liquefied material 505 through openings 502 connecting the duct 501 with the outer surface of the nail 500.
  • neck 513 and tip section 51 1 are enabled due to the flexibility of the neck 513. Despite its flexibility, the neck 513 is designed in such a way, that axial forces may be transmitted.
  • the pressed out material 505 is distributed within the trabecular of the surrounding bone and provides for a positive fit after solidification.
  • the proximal end of the intramedullary nail 500 may be provided with an inner thread 503, which may be used for affixing the heating device 510. Subsequently, the elastic neck 513 together with the tip section 51 1 may be further introduced using a (mechanical, electromechanical or pneumatic) pressing aid. The locking of a corresponding hip screw, locking bolt or proximal locking of the intramedullary nail may be effected using the same device or a different device. For straight intramedullary nails, simple cylindrical tip sections may be employed, and it is not required that the neck is elastically deformable.
  • an insert which seals the portion of the duct lying distally of this region, prohibiting the permeation of thermoplastic material into this region.
  • the insert may be screwed into a corresponding thread or it may be positioned on a dedicated seat that is provided within the duct. After locking, the insert may be removed or it may be left within the intramedullary nail.
  • the Figure 6 is a cross-sectional view of a second embodiment of an inventive heating device, which is specifically suited for simultaneous proximal as well as distal unlocking in cases where an intramedullary nail is to be removed. This may be required in the case of complications or due to other reasons, when the biodegradable material is not yet sufficiently degraded.
  • the tip section 521 of the heating device 520 may be inserted into the duct 501 of the intramedullary nail 500.
  • the device 520 comprises a handle 522, a power supply (not displayed), an elastic neck 523 and a tip section 521 connected to the distal end of the neck 523.
  • the tip section 521 comprises a heating element 524 and a contact element 525.
  • the heating device 520 comprises a further heating element 526 en- closed by a further contact element 527 attached distally to the handle 522.
  • Introduction of the neck 523 and tip section 521 into the duct 501 is enabled due to the flexibility of the neck 523.
  • the neck 523 is designed in such a way, that axial forces may be transmitted.
  • the device 520 is attached to the nail 500 by means of a screw connection between the device 520 and the inner thread 503 of the nail 500.
  • the shapes of the contact elements 525, 527 are adapted to the geometry of the duct 501 of the intramedullary nail 500.
  • the heating elements 524, 526 are heated, they are in thermal connection with the contact elements 525, 527.
  • the thermoplastic material 505 accomodated within the openings 502, 504 and close to the outer surface of the intramedullary nail 500 is liquefied. Thereby, the intramedullary nail 500 is unlocked from the surrounding bone tissue and may be removed by pulling the handle 522 of the device 520.
  • the distance of the contact elements 525, 527 is adjustable such that the same device 520 may be used for differently shaped and sized intramedullary nails. Removal of hip screws, locking bolts etc. may be effected the same way.
  • the Figures 7A-7C show different possible forms of contact elements for heatable tips of heating devices for locking inventive intramedullary nails.
  • the contact element 540 may be generally spherical (see Figure 5) or conical (see Figure 7A).
  • the heating element 541 and the contact element 540 may be in one piece or two pieces.
  • the contact element may be further provided with a sealing element such as an O-ring 542 (see Figure 7B), inhibiting backflow of the thermoplastic material in a region behind the tip section of the heating device.
  • a heat conductive insert 543 (e. g. made of steel or titanium) is separate from a heating element 541, whereas the heating element 541 is designed in such a way that it may contact the insert 543 for transmitting heat.
  • the insert 543 is introduced into the duct of the intramedullary nail prior to the locking operation, e. g. together with the blank of thermoplastic material.
  • the insert 543 may be provided within the duct already during manufacture of the nail.
  • the Figure 8 to 9 show exemplary tip geometries which are specifically suited for the removal of intramedullary nails being locked using a thermoplastic material.
  • a thermoplastic material In this case - contrary to the case of locking - it is necessary to simultaneously heat all regions in which the thermoplastic material has been distributed when locking the nail. Therefore, it is nec- essary to have extended contact elements. At the same time it has to be possible to introduce these contact elements into the duct of the intramedullary nail, even in cases where the nail has one or several bends.
  • the Figure 8 is a side view of a first variant of a suitable tip of an inventive heating device.
  • the contact element 551 has a helical shape (similar to a corkscrew). It constitutes the heating element, being made of a flexible material or based on a flexible supporting body having a coating constituting the heating element.
  • the Figure 9 is a cross-sectional view of a flexible tip of another inventive heating device. It comprises a plurality of contact elements 552.1...552.4 having the shape of spherical caps which are movable to each other. This allows for passing bends of the intramedullary nail, whereas the contact elements 552.1 ...552.4 are slightly pushed apart from each other.
  • the Figure 10 is a cross-sectional view of a tip of an inventive heating device, the tip having a reduced diameter compared to the tips described above.
  • This tip is to be used to- gether with intramedullary nails 506 having a distal region 506a, in which the inside diameter of the duct 507 is reduced accordingly.
  • Reduction of the diameter of the heatable tip of the device allows for easily introducing the tip into the duct 507 of the intramedullary nail 506 even in the case of bends.
  • the corresponding reduction of the inside diameter of the duct 507 ensures good thermal contact for locking and/or unlocking the nail.
  • heating element that is integrated into the intramedullary nail itself and that may be e. g. electrically contacted from the outside;
  • the bonding agent may be chosen differently from PLLA. Furthermore, it may comprise a therapeutic agent.
  • the bonding agent may be introduced into the duct in the form of a blank prior to the locking step or it may be already provided within the duct during manufacture of the nail or hip screw.
  • the geometry of the intramedullary nails, locking screws, hip screws may be chosen differently or combined in a different way, etc.
  • the outside contour of the intramedullary nail may be polygonal (having rounded edges), circular, star-shaped etc. and it may be fluted.
  • the diameter of the intramedullary nail needs not be constant along the length of the nail, e. g.
  • the intramedullary nail may comprise a further canal (which may be essentially parallel to the duct) for guide wire applications.
  • the hip screw its diameter is preferably circular, whereas in the contact region with the intramedullary nail it may be provided with flat surface portions or it may have a polygonal cross-section in order to provide for a lock against rotation.
  • the intramedullary nail as well as the hip screw may be made of a different material than titanium such as implant steel or reinforced plastics.
  • the outside surface of the nails, bolts or screws may be additionally provided by a structuring as mentioned above.
  • the invention creates an intramedullary nail that allows the fast and secure fixation of long bone fractures and which especially simplifies distal locking of the nail to the bone.

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  • Health & Medical Sciences (AREA)
  • Orthopedic Medicine & Surgery (AREA)
  • Surgery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Neurology (AREA)
  • Medical Informatics (AREA)
  • Molecular Biology (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Surgical Instruments (AREA)

Abstract

L'invention porte sur un clou médullaire (100), destiné à stabiliser un os fracturé, qui est pourvu d’au moins un premier conduit (101) pour recevoir au moins partiellement un agent de liaison liquéfiable par application d'énergie. Le conduit (101) s'étend en continu à partir d'une région proximale du clou (100) vers une région distale du clou (100), alors que dans la région distale, le clou (100) est pourvu d’au moins une ouverture (102) reliant le conduit (101) à une surface extérieure du clou (100). Lors de l'utilisation du clou médullaire (100), il n'est plus nécessaire qu'un verrouillage distal exécute le processus difficile consistant à percer avec précision un trou à l'intérieur de l'os afin d'être capable de régler des boulons ou des vis de verrouillage, ce qui simplifie le processus et évite le besoin d'incisions supplémentaires. Un dispositif de ciblage n'est plus nécessaire. L'emploi d'un agent de liaison qui peut être activé par énergie permet une activation rapide au bon moment (c'est-à-dire lorsque le clou médullaire est correctement positionné à l'intérieur de l'os).
PCT/CH2008/000322 2008-07-18 2008-07-18 Clou médullaire WO2010006453A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/CH2008/000322 WO2010006453A1 (fr) 2008-07-18 2008-07-18 Clou médullaire

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CH2008/000322 WO2010006453A1 (fr) 2008-07-18 2008-07-18 Clou médullaire

Publications (1)

Publication Number Publication Date
WO2010006453A1 true WO2010006453A1 (fr) 2010-01-21

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PCT/CH2008/000322 WO2010006453A1 (fr) 2008-07-18 2008-07-18 Clou médullaire

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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4653489A (en) * 1984-04-02 1987-03-31 Tronzo Raymond G Fenestrated hip screw and method of augmented fixation
WO1995015732A1 (fr) * 1993-12-06 1995-06-15 Coutts Richard D Fixation de dispositifs orthopediques
JPH07184920A (ja) * 1993-12-27 1995-07-25 Terumo Corp 固定補強用樹脂充填器具
DE19741087A1 (de) * 1997-09-18 1999-04-08 Schumann Klaus In der Chirurgie zu verwendende Vorrichtung zum festen Verbinden zweier Knochenteile oder eines Knochenteils mit einem Prothesenglied
US20030083662A1 (en) * 2001-11-01 2003-05-01 Middleton Lance M. Orthopaedic implant fixation using an in-situ formed anchor
US20040049192A1 (en) * 2002-09-10 2004-03-11 Hirotaka Shimizu Osteosynthetic apparatus
WO2004112661A1 (fr) * 2003-06-20 2004-12-29 Myers Thomas H Procede et appareil de renforcement des proprietes biochimiques d'implants
US20070260250A1 (en) * 2006-05-05 2007-11-08 Sdgi Holdings, Inc. Reinforcement of boney material surrounding a bone implant
US20080027456A1 (en) * 2006-07-19 2008-01-31 Csaba Truckai Bone treatment systems and methods

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4653489A (en) * 1984-04-02 1987-03-31 Tronzo Raymond G Fenestrated hip screw and method of augmented fixation
WO1995015732A1 (fr) * 1993-12-06 1995-06-15 Coutts Richard D Fixation de dispositifs orthopediques
JPH07184920A (ja) * 1993-12-27 1995-07-25 Terumo Corp 固定補強用樹脂充填器具
DE19741087A1 (de) * 1997-09-18 1999-04-08 Schumann Klaus In der Chirurgie zu verwendende Vorrichtung zum festen Verbinden zweier Knochenteile oder eines Knochenteils mit einem Prothesenglied
US20030083662A1 (en) * 2001-11-01 2003-05-01 Middleton Lance M. Orthopaedic implant fixation using an in-situ formed anchor
US20040049192A1 (en) * 2002-09-10 2004-03-11 Hirotaka Shimizu Osteosynthetic apparatus
WO2004112661A1 (fr) * 2003-06-20 2004-12-29 Myers Thomas H Procede et appareil de renforcement des proprietes biochimiques d'implants
US20070260250A1 (en) * 2006-05-05 2007-11-08 Sdgi Holdings, Inc. Reinforcement of boney material surrounding a bone implant
US20080027456A1 (en) * 2006-07-19 2008-01-31 Csaba Truckai Bone treatment systems and methods

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