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WO2011134440A2 - Joint implant, especially the knee joint - Google Patents

Joint implant, especially the knee joint Download PDF

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Publication number
WO2011134440A2
WO2011134440A2 PCT/CZ2011/000040 CZ2011000040W WO2011134440A2 WO 2011134440 A2 WO2011134440 A2 WO 2011134440A2 CZ 2011000040 W CZ2011000040 W CZ 2011000040W WO 2011134440 A2 WO2011134440 A2 WO 2011134440A2
Authority
WO
WIPO (PCT)
Prior art keywords
knee joint
joint
implant
shell mould
patient
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/CZ2011/000040
Other languages
French (fr)
Other versions
WO2011134440A3 (en
Inventor
Miroslav PÍŠKA
Josef SEDLÁK
Ondřej CHARVÁT
Martin Madaj
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vysoke Uceni Technicke V Brne
Original Assignee
Vysoke Uceni Technicke V Brne
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 Vysoke Uceni Technicke V Brne filed Critical Vysoke Uceni Technicke V Brne
Priority to EP11764461.7A priority Critical patent/EP2588033A2/en
Publication of WO2011134440A2 publication Critical patent/WO2011134440A2/en
Publication of WO2011134440A3 publication Critical patent/WO2011134440A3/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • A61F2/38—Joints for elbows or knees
    • 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
    • A61F2/30756—Cartilage endoprostheses
    • 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
    • A61F2/30942—Designing or manufacturing processes for designing or making customized prostheses, e.g. using templates, CT or NMR scans, finite-element analysis or CAD-CAM techniques
    • 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
    • A61F2/38—Joints for elbows or knees
    • A61F2/3859—Femoral components
    • 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
    • A61F2/30756—Cartilage endoprostheses
    • A61F2002/30757—Cartilage endoprostheses made of a sheet covering the natural articular surface, e.g. cap
    • 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
    • A61F2/30767—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
    • A61F2/30771—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves
    • A61F2002/30878—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts
    • A61F2002/30879—Ribs
    • 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
    • A61F2/30942—Designing or manufacturing processes for designing or making customized prostheses, e.g. using templates, CT or NMR scans, finite-element analysis or CAD-CAM techniques
    • A61F2002/30948—Designing or manufacturing processes for designing or making customized prostheses, e.g. using templates, CT or NMR scans, finite-element analysis or CAD-CAM techniques using computerized tomography, i.e. CT scans
    • 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
    • A61F2/30942—Designing or manufacturing processes for designing or making customized prostheses, e.g. using templates, CT or NMR scans, finite-element analysis or CAD-CAM techniques
    • A61F2002/30962—Designing or manufacturing processes for designing or making customized prostheses, e.g. using templates, CT or NMR scans, finite-element analysis or CAD-CAM techniques using stereolithography

Definitions

  • Joint implant especially the knee joint.
  • the invention relates to a joint implant, especially the the knee joint, comprising a femoral component, an insert and a tibial component.
  • a joint can be exemplified by the physiological movement in the knee joint, which is a complex combination of rolling, rotary and sliding movements.
  • the burden on the joint while walking on a flat surface is a multiple of the body weight; in case of climbing stairs, walking uphill and carrying heavy loads, the burden is even higher.
  • a known total knee replacement is an assembly comprising primarily three main components, used to renew the natural function of the knee joint.
  • the components are: femoral component, insert and tibial component.
  • the femoral component is the fundamental segment of the total knee replacement assembly.
  • Standard femoral components are currently produced from bio-compatible Cr-Co-Mo or Ti alloys using the methods of casting and chip machining. Femoral components are made in standard sizes so as to suit the biggest range of patients possible.
  • the inner shape of the femoral component is composed of five surfaces that ensure a proper seating of the replacement on the distal part of the femur. In most cases, the replacement is fixed with two plugs and bone cement - if a cemented replacement is used. Fixing non-cemented replacements is ensured by the gradual ingrowth of the bone into the porous inner surface of the replacement.
  • the disadvantages of these solutions are in particular the relatively large weight and rigidity of the femoral components, determined by the size, shape design and material applied.
  • Another disadvantage is the relatively large loss of the patient's bone due to osteotomy and settlement of the implant onto the bone. In this case, once again, it is necessary to repeat the operation after some time, which is accompanied by another loss of the original bone and larger size of the implant .
  • Another disadvantage is the method of fixing of the plugs by drilling, which is technologically simple, but does not prevent the replacement from loosening axially.
  • a joint implant especially the knee joint, comprising a femoral component, an insert and a tibial component, as specified in this invention.
  • the femoral component of the knee joint replacement is composed of a shell mould attachable to the distal part of the femur, where the reference plane determining the outer and inner shape of the mould is a trimmed, spaced and smoothed surface of the distal part of the patient's femur that accounts for the overall curvature of the knee joint.
  • the outer lateral and antero-posterior dimensions of the shell mould advantageously match the specific knee joint of the given patient.
  • the inner surface of the shell mould is ribbed, where the ribs lock laterally and longitudinally in grooves created operatively in the distal part of the patient's femur.
  • the shell mould is advantageously made from a bio-compatible material.
  • the joint implant as mentioned above is made so that CT data on the patient's affected knee joint are evaluated and, after these data are edited in a CAx application, an individual 3D model for the shell mould is created.
  • the final 3D model is then transformed into a high-resolution STL format and a shell mould is produced, for instance using the additive method of DMLS (Direct Metal Laser Sintering) , where:
  • CT - Computed tomography - is a medical imaging technology based on tomography, created using computer equipment and providing a three-dimensional image of the investigated object;
  • CAx - Computer-Aided Technologies - is a term that covers broad range of computer applications for designing, analyzin and manufacturing parts;
  • STL - Stereolithography - is a format type for storing data on three-dimensional objects and is used in many computer programmes to support the production of parts;
  • DMLS - Direct Metal Laser Sintering - is a production method using the technology of continuous sintering of particles using laser.
  • the trimmed, spaced and smoothed surface of the distal part of the patient's femur that accounts for the overall curvature of the knee joint is used as the reference surface that determines the outer and inner shape of the shell mould. Outer dimensions are chosen to suit the specific knee joint, individually for each patient. When the thickness of the layer is added to the reference surface, the required shell mould for the knee joint is created. The thickness of the shell mould is chosen to maintain the correct function of the implant .
  • Fixation to the knee joint is achieved using a system of ribs, suitably placed laterally and longitudinally on the inner side of the shell mould of the knee replacement.
  • the ribs lock into the grooves operatively created in the distal part of the patient's femur.
  • the replacement is made, for example using the DMLS additive technology, from a bio-compatible material that features a low specific gravity, a high strength to density ratio and specific tribological properties.
  • the subject of the invention is a new type of a shell- moulded joint implant, including the overall design and implementation of its production technology.
  • the implant of a shell-moulded type can be used as a replacement in case of cartilage degradation not only in human knee joints.
  • the design of the proposed technology consists in obtaining the patient's CT data, their processing and preparation of a model of the required joint. Based on these data, a corresponding joint replacement model is created in a CAx application, and then produced from a bio-compatible alloy using an additive production method.
  • a great benefit of this joint replacement type is a smaller intervention in the patient's body, with a reduced resection on the thigh bone, better maintenance of the bone mass, shorter operation time and lower financial costs.
  • the femoral component of the shell-moulded implant is made to achieve the same functional parameters as the current batch-produced implants. Compared to current implacts, the shell-moulded implant makes it possible to maintain more of the patient's bone mass, reduce the extent of operation as well as operative and post-operative trauma.
  • the main advantage of the shell-moulded implant is its shape, derived from the actual shape of the patient's femur, with a relatively small thickness, thanks to which it is not necessary to perform an extensive resection of the distal part of the femur during the operation, as is the case of commonly used femoral components. Thanks to a system of ribs on the inner surface of the implant, simple fixation and rigidity of the implant are secured.
  • the description above also shows that a shell-moulded replacement has a lower weight and in general the operation is much more regardful of the patient.
  • CT data on the patient's affected knee joint are enough to create an STL model of the knee joint.
  • an individual 3D model of the shell-moulded replacement is created.
  • the final 3D model is then transformed into a high-resolution STL format, which will ensure a sufficient quality of the surface of the implant.
  • Production as such is carried out from a bio-compatible material using for example the DMLS additive method, one of a group of rapid prototyping technologies. Excellent mechanical properties and corrosion resistance in combination with low specific gravity are typical for this alloy.
  • the new type of a shell-moulded implant brings the following advantages: retaining the thigh bone to a much larger extent than until now for the necessary revision operations; maintaining the extent of mobility and anatomical load; reduction of the risk of displacement of the shell- moulded implant; renewal of the natural function of the knee joint using a very durable implant with a long lifecycle; lower production and operating costs due to a lower consumption of materials, reduced time of operation etc., and another advantage is a distinct reduction of the weight of the shell-moulded implant compared to the current implant types as well as a better specific load capacity of the contact surfaces of the implant and the bone. Advantages also include smaller post-operative trauma for patients - shorter treatment time and reduction or elimination of repeated operations and implant replacements.
  • FIG. 1 shows an axonometric view of the shell- moulded replacement, implanted on the distal part of the femur.
  • Fig. 2 shows an axonometric view of the inner surface of the shell-moulded implant with fixation ribs.
  • An embodiment of the knee joint implant comprises a femoral component, a PE insert and a tibial component.
  • the femoral component of the knee joint replacement comprises shell mould 1, attachable to the distal part of femur 2.
  • the trimmed, spaced and smoothed surface of the distal part of the patient's femur 2 that accounts for the overall curvature of the knee ⁇ joint is used as the reference surface that determines the outer and inner shape of shell mould 1.
  • the outer lateral and antero-posterior dimensions of shell 1 match the specific knee joint of the given patient.
  • the thickness of shell 1 is chosen to maintain the correct function of the implant.
  • the inner surface of shell 1 contains ribs 3, placed laterally and longitudinally, which lock in grooves created operatively in the distal part of the patient's femur 2.
  • Shell 1 is made for example from the bio-compatible material T16A14V.
  • Shell mould 1 is fixed to the knee joint using a system of ribs 3, which lock into grooves created operatively in the distal part of the patient's femur 2.
  • the CT data on the patient's affected knee joint are evaluated.
  • an individual 3D model of shell mould 1 is created.
  • the final 3D model is then transformed into a high-resolution STL format and shell mould 1 is produced, for instance using the additive method of DMLS .
  • the replacement is made from a bio-compatible material that features a low specific gravity, a high strength to density ratio and specific tribological properties.
  • a joint implant as specified in this invention can be especially used in medicine - surgery and orthopedics.

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  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Orthopedic Medicine & Surgery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Transplantation (AREA)
  • Cardiology (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Vascular Medicine (AREA)
  • Veterinary Medicine (AREA)
  • Animal Behavior & Ethology (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Public Health (AREA)
  • Physical Education & Sports Medicine (AREA)
  • Rheumatology (AREA)
  • Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Manufacturing & Machinery (AREA)
  • Prostheses (AREA)

Abstract

The invention relates to a joint implant, especially the knee joint, comprising a femoral component, an insert and a tibial component. The femoral component of the knee joint replacement is composed of a shell mould (1) attachable to the distal part of the femur (2), where the reference plane determining the outer and inner shape of the mould (1) is a trimmed, spaced and smoothed surface of the distal part of the patient's femur (2) that accounts for the overall curvature of the knee joint. The outer lateral and antero-posterior dimensions of the shell mould (1) match the specific knee joint of the given patient. The inner surface of the shell mould (1) contains ribs (3), where the ribs lock laterally and longitudinally in grooves created operatively in the distal part of the patient's femur (2). The shell mould (1) is advantageously made from a bio-compatible material.

Description

Joint implant, especially the knee joint.
Technical field
The invention relates to a joint implant, especially the the knee joint, comprising a femoral component, an insert and a tibial component.
State of the art
There are many causes that could result in a joint disease. These most often include degeneration, i.e. aging and wear of joint cartilage - primary and secondary osteoarthrosis. The causes for primary osteoarthrosis are not known in detail. Secondary arthrosis is the consequence of another disease, for example traumatic injury, metabolic disease - gout, autoimmune disease - rheumatoid arthritis, etc. A joint can be exemplified by the physiological movement in the knee joint, which is a complex combination of rolling, rotary and sliding movements. The burden on the joint while walking on a flat surface is a multiple of the body weight; in case of climbing stairs, walking uphill and carrying heavy loads, the burden is even higher. These facts predetermine the huge demands on the structure of implants, surgical technique and post-operative rehabilitation.
Globally, the issues of treatment are studied by many research and development centres; numerous solutions have been designed, yet they are not commonly used for the treatment of the knee joint. The known solutions are described for example in: HIDEOMI WA A ABE, ADEL REFAAT AHMED, TETSUYA SHINOZAKI, TAKASHI YANAGAWA, MASANORI TERAUCHI AND KENJI TAKAGI SHI . Reconstruction with autologous pasteurized whole knee joint II: application for osteosarcoma of the proximal tibia. In: Journal of Orthopaedic Science . Volume 8, Number 2 / March, 2003, p. 676; G. PAPACHRISTOU . Photoelastic study of the internal and contact stresses on the knee joint before and after osteotomy Journal. Archives of Orthopaedic and Trauma Surgery. Volume 124, Number 5 / June, 2004, p. 533; JOEL L. LANOVAZ AND RANDY E. ELLIS. Experimental Validation of a 3D Dynamic Finite-Element Model of a Total Knee Replacement. Medical Image Computing and Computer-Assisted Intervention. Volume 3749/2005, p. 317; J. BRUNS, M. VOLKMER AND S. LUESSENHOP. Pressure distribution at the knee joint. Archives of Orthopaedic and Trauma Surgery. Volume 113, Number 1 / December, 1993, p. 224; MAHONEY, 0., McClung C, PHIL . , SCHMALZRIED, T. Improved Extensor Mechanism Function with the Scorpio Total Knee Replacement, Orthopedic Research Society Annual meeting, 1999. Available at: ww .stryker . com/orthopaedics/sites/scorpioknee/scorpiorefs . php ; SEDLAK, J. Technology of Prototype Production with the Support of Reverse Engineering and CAD/CAM: Dissertation thesis. Brno: University of Technology in Brno, Faculty of Mechanical Engineering, Institute of Engineering Technology, 2008. 104 p., 11 annexes. Dissertation thesis supervisor: Miroslav PISKA, CSc; SEDLAK, J.; PISKA, M. Modern technologies of implant productions with reverse engineering and CAD/CAM support. In TRANSFER 2008. Trencin: Digital Graphic, 2008. pp. 66-67. ISBN: 978-80-8075-357-3; MARC- ANTOINE ROUSSEAU, JEAN-YVES LAZENNEC AND YVES CATONNE. Early mechanical failure in total knee arthroplasty International Orthopaedics. International Orthopaedics 10.1007/s00264-006- 0276-7, 2005, p. 117; ROZKOSNY, L. How to Produce Fully Functional Metal Parts Directly from 3D CAD Data, [on-line]. February 2008 [cited 20. May 2008]. Available at www: <http : //www . techtydenik. cz/detail . php?action=show&id=3698 &mark =>. ohlers, T. "Wohlers Report 2007, State of the Industry Annual Worldwide Progress Report" Wohlers Associates, Inc. 2007; LEYENS, Ch., PETERS, M . Titanium and Titanium Alloys. Fundamentals and Applications. Willet-VCH., Koln, Germany, 2nd ed., 2005, p. 513, ISBN 3-527-30534-3. Treatment is usually accompanied by a rather large invasive operation in the patient's body and is quite expensive.
A known total knee replacement is an assembly comprising primarily three main components, used to renew the natural function of the knee joint. The components are: femoral component, insert and tibial component. The femoral component is the fundamental segment of the total knee replacement assembly.
Standard femoral components are currently produced from bio-compatible Cr-Co-Mo or Ti alloys using the methods of casting and chip machining. Femoral components are made in standard sizes so as to suit the biggest range of patients possible. The inner shape of the femoral component is composed of five surfaces that ensure a proper seating of the replacement on the distal part of the femur. In most cases, the replacement is fixed with two plugs and bone cement - if a cemented replacement is used. Fixing non-cemented replacements is ensured by the gradual ingrowth of the bone into the porous inner surface of the replacement. The disadvantages of these solutions are in particular the relatively large weight and rigidity of the femoral components, determined by the size, shape design and material applied. These attributes contribute to a higher specific load on contact points, especially due to gravitational and inertial forces, which could result in the implant being loosened and in the need of another operation. Another disadvantage is the relatively large loss of the patient's bone due to osteotomy and settlement of the implant onto the bone. In this case, once again, it is necessary to repeat the operation after some time, which is accompanied by another loss of the original bone and larger size of the implant . Another disadvantage is the method of fixing of the plugs by drilling, which is technologically simple, but does not prevent the replacement from loosening axially.
Essence of invention
The deficiencies mentioned above are to a great extent removed by a joint implant, especially the knee joint, comprising a femoral component, an insert and a tibial component, as specified in this invention. Its essence is that the femoral component of the knee joint replacement is composed of a shell mould attachable to the distal part of the femur, where the reference plane determining the outer and inner shape of the mould is a trimmed, spaced and smoothed surface of the distal part of the patient's femur that accounts for the overall curvature of the knee joint.
The outer lateral and antero-posterior dimensions of the shell mould advantageously match the specific knee joint of the given patient.
Advantageously, the inner surface of the shell mould is ribbed, where the ribs lock laterally and longitudinally in grooves created operatively in the distal part of the patient's femur. The shell mould is advantageously made from a bio-compatible material.
The joint implant as mentioned above is made so that CT data on the patient's affected knee joint are evaluated and, after these data are edited in a CAx application, an individual 3D model for the shell mould is created. The final 3D model is then transformed into a high-resolution STL format and a shell mould is produced, for instance using the additive method of DMLS (Direct Metal Laser Sintering) , where:
CT - Computed tomography - is a medical imaging technology based on tomography, created using computer equipment and providing a three-dimensional image of the investigated object;
CAx - Computer-Aided Technologies - is a term that covers broad range of computer applications for designing, analyzin and manufacturing parts;
STL - Stereolithography - is a format type for storing data on three-dimensional objects and is used in many computer programmes to support the production of parts; and
DMLS - Direct Metal Laser Sintering - is a production method using the technology of continuous sintering of particles using laser.
The trimmed, spaced and smoothed surface of the distal part of the patient's femur that accounts for the overall curvature of the knee joint is used as the reference surface that determines the outer and inner shape of the shell mould. Outer dimensions are chosen to suit the specific knee joint, individually for each patient. When the thickness of the layer is added to the reference surface, the required shell mould for the knee joint is created. The thickness of the shell mould is chosen to maintain the correct function of the implant .
Fixation to the knee joint is achieved using a system of ribs, suitably placed laterally and longitudinally on the inner side of the shell mould of the knee replacement. The ribs lock into the grooves operatively created in the distal part of the patient's femur.
The replacement is made, for example using the DMLS additive technology, from a bio-compatible material that features a low specific gravity, a high strength to density ratio and specific tribological properties.
The subject of the invention is a new type of a shell- moulded joint implant, including the overall design and implementation of its production technology. The implant of a shell-moulded type can be used as a replacement in case of cartilage degradation not only in human knee joints. The design of the proposed technology consists in obtaining the patient's CT data, their processing and preparation of a model of the required joint. Based on these data, a corresponding joint replacement model is created in a CAx application, and then produced from a bio-compatible alloy using an additive production method.
A great benefit of this joint replacement type is a smaller intervention in the patient's body, with a reduced resection on the thigh bone, better maintenance of the bone mass, shorter operation time and lower financial costs.
The femoral component of the shell-moulded implant is made to achieve the same functional parameters as the current batch-produced implants. Compared to current implacts, the shell-moulded implant makes it possible to maintain more of the patient's bone mass, reduce the extent of operation as well as operative and post-operative trauma. The main advantage of the shell-moulded implant is its shape, derived from the actual shape of the patient's femur, with a relatively small thickness, thanks to which it is not necessary to perform an extensive resection of the distal part of the femur during the operation, as is the case of commonly used femoral components. Thanks to a system of ribs on the inner surface of the implant, simple fixation and rigidity of the implant are secured. The description above also shows that a shell-moulded replacement has a lower weight and in general the operation is much more regardful of the patient.
To create a shell-moulded replacement, CT data on the patient's affected knee joint are enough to create an STL model of the knee joint. Subject to editing these data in a CAx application, an individual 3D model of the shell-moulded replacement is created. The final 3D model is then transformed into a high-resolution STL format, which will ensure a sufficient quality of the surface of the implant. Production as such is carried out from a bio-compatible material using for example the DMLS additive method, one of a group of rapid prototyping technologies. Excellent mechanical properties and corrosion resistance in combination with low specific gravity are typical for this alloy. The new type of a shell-moulded implant brings the following advantages: retaining the thigh bone to a much larger extent than until now for the necessary revision operations; maintaining the extent of mobility and anatomical load; reduction of the risk of displacement of the shell- moulded implant; renewal of the natural function of the knee joint using a very durable implant with a long lifecycle; lower production and operating costs due to a lower consumption of materials, reduced time of operation etc., and another advantage is a distinct reduction of the weight of the shell-moulded implant compared to the current implant types as well as a better specific load capacity of the contact surfaces of the implant and the bone. Advantages also include smaller post-operative trauma for patients - shorter treatment time and reduction or elimination of repeated operations and implant replacements.
List of drawings A joint implant as stipulated in this invention will be described in detail on a specific embodiment using attached drawings, where Fig. 1 shows an axonometric view of the shell- moulded replacement, implanted on the distal part of the femur. Fig. 2 shows an axonometric view of the inner surface of the shell-moulded implant with fixation ribs.
Embodiments of the invention
An embodiment of the knee joint implant comprises a femoral component, a PE insert and a tibial component. The femoral component of the knee joint replacement comprises shell mould 1, attachable to the distal part of femur 2. The trimmed, spaced and smoothed surface of the distal part of the patient's femur 2 that accounts for the overall curvature of the knee · joint is used as the reference surface that determines the outer and inner shape of shell mould 1. The outer lateral and antero-posterior dimensions of shell 1 match the specific knee joint of the given patient. The thickness of shell 1 is chosen to maintain the correct function of the implant. The inner surface of shell 1 contains ribs 3, placed laterally and longitudinally, which lock in grooves created operatively in the distal part of the patient's femur 2. Shell 1 is made for example from the bio-compatible material T16A14V.
Shell mould 1 is fixed to the knee joint using a system of ribs 3, which lock into grooves created operatively in the distal part of the patient's femur 2.
As regards the method of production ' of this joint implant, the CT data on the patient's affected knee joint are evaluated. Subject to editing these data in a CAx application, an individual 3D model of shell mould 1 is created. The final 3D model is then transformed into a high-resolution STL format and shell mould 1 is produced, for instance using the additive method of DMLS . The replacement is made from a bio-compatible material that features a low specific gravity, a high strength to density ratio and specific tribological properties.
Industrial use
A joint implant as specified in this invention can be especially used in medicine - surgery and orthopedics.

Claims

P A T E N T C L A I M S
A joint implant, especially the knee joint, comprising a femoral component, an insert and a tibial component, characterized by the fact that the femoral component of the knee joint replacement is composed of a shell mould (1), attachable to the distal part of the femur
(2), where the reference surface that determines the inner and outer shape of the shell mould (1) is a trimmed, spaced and smoothed surface of the distal part of the patient's femur that accounts for the overall curvature of the knee joint.
A joint implant as in Claim 1, wherein the outer lateral and antero-posterior dimensions of the shell mould (1) match the specific knee joint of the given patient.
3. A joint implant as in Claim 1, wherein the inner surface of the shell mould (1) contains ribs (3), placed laterally and longitudinally, which lock in grooves created operatively in the distal part of the patient's femur (2).
A joint implant as in Claim 1, wherein the shell mould (1) is made from a bio-compatible material.
PCT/CZ2011/000040 2010-04-27 2011-04-26 Joint implant, especially the knee joint Ceased WO2011134440A2 (en)

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CZPV2010-318 2010-04-27

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015024122A1 (en) 2013-08-21 2015-02-26 Laboratoires Bodycad Inc. Anatomically adapted orthopedic implant and method of manufacturing same
CZ309024B6 (en) * 2020-08-17 2021-12-01 Vysoké Učení Technické V Brně Kit for applying joint replacements

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2006297137A1 (en) * 2005-09-30 2007-04-12 Conformis Inc. Joint arthroplasty devices
EP1886640B1 (en) * 2006-08-08 2009-11-18 BrainLAB AG Planning method and system for adjusting a free-shaped bone implant
EP2114312B1 (en) * 2007-02-14 2014-01-08 ConforMIS, Inc. Method for manufacture of an implant device

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015024122A1 (en) 2013-08-21 2015-02-26 Laboratoires Bodycad Inc. Anatomically adapted orthopedic implant and method of manufacturing same
EP3035891A4 (en) * 2013-08-21 2017-05-03 Laboratoires Bodycad Inc. Anatomically adapted orthopedic implant and method of manufacturing same
US9737406B2 (en) 2013-08-21 2017-08-22 Laboratories Bodycad Inc. Anatomically adapted orthopedic implant and method of manufacturing same
CZ309024B6 (en) * 2020-08-17 2021-12-01 Vysoké Učení Technické V Brně Kit for applying joint replacements

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