EP3226811A1

EP3226811A1 - Ceramic spacer for the two-sided replacement of implants in shoulder, knee, and hip as a result of infections

Info

Publication number: EP3226811A1
Application number: EP15805149.0A
Authority: EP
Inventors: Andreas Rempp; Ralph Autenrieth; Alfons Kelnberger; Roman Preuss; Heinrich Wecker; Tobias Weiss; Javad Parvizi
Original assignee: Ceramtec GmbH
Current assignee: Ceramtec GmbH
Priority date: 2014-12-05
Filing date: 2015-12-03
Publication date: 2017-10-11
Also published as: DE102015224150A1; WO2016087561A1; JP2017536214A; CN107223041A; BR112017010111A2; RU2017123560A; US20170340445A1

Abstract

The invention relates to a spacer (1) comprised of individual components (2, 3, 4, 9, 10, 12) as joint replacement in the arthroplasty of shoulder, knee, and hip for the temporary surgical care of infections in the joint. The problems addressed by the invention are those of avoiding an adhesion of the bone to the spacer and a release of wear products, achieving that the patient does substantially not experience any mobility restriction, and keeping the wear and tear of the spacer as little as possible. These problems are solved in that at least one component of the spacer (1) is made of a ceramic material, of a plurality of ceramic materials, or of a non-ceramic material having a ceramic coating.

Description

Ceramic spacers for the two-sided change of implants in the shoulder, knee and hip as a result of infections

The invention relates to a spacer ("spacer") made of individual components as joint replacement in the endoprosthetics of the shoulder, the knee and the hip for the temporary surgical treatment of infections in the joint.

Spacers, also called spacers, are known in the field of joint endoprosthetics and are used temporarily to support the healing of bacterial infections, due to endoprosthetic care, and to allow during the healing phase a mechanical minimal functionality of the joint apparatus.

Healing support is provided by local, controlled delivery of antibiotic or antibacterial substances. A minimal functionality of the joint is achieved if the spacer has at least the following shape elements:

· Distally a stem or shaft, similar to a stem or stem of an artificial hip joint, which supports the spacer in the medullary canal of the femur.

Proximally a ball segment or ball head capable of articulating to a limited extent (especially with respect to the number of load and motion changes) in the hemisphere of the acetabular cavity remaining after removal of the artificial acetabular cup. The life / application of the spacer ends when the infection healed after a few weeks, the spacer is removed and a new endoprosthesis, if necessary revision endoprosthesis, is used.

Previous spacer systems are usually based on PMMA bone cements, which are mixed or filled with antibiotic agents, usually gentamicin and / or vancomecin, and either delivered as prefabricated implants or produced during the surgical operation with provided material mixtures and molds.

There are a number of fundamental disadvantages or limitations - depending on the system used - which have a negative effect on the patient:

• Increasing patient retention increases the risk of the bone growing on the spacer, which makes removal of the temporary implant difficult or undesirable bone loss on removal. This risk is favored by the material and shape specific surface roughness and the chemical-biological properties of the materials used in a negative respect.

• The low wear resistance of the materials used in tribological stress restricts the patient extremely in his mobility. The released wear products - cement particles and ceramic particles with which the cements are often filled to increase the strength - may provoke negative biological reactions and increase the risk of wear of the subsequently installed endoprostheses by so-called third-body wear. • The low mechanical strength of the temporary spacers compared to regular prostheses means that the patient must limit the load (height of the load and number of load cycles) and thus his mobility extremely, if a failure of the spacer is to be avoided by breakage.

Due to the coarse shape of the cement spacers, only very inaccurate friction pairings can usually be produced or available, which leads to increased wear and insufficient guidance and stability of the joints.

The invention has for its object to improve a placeholder or spacer according to the preamble of claim 1 so that an increase of the bone to the spacer and a release of wear products is avoided. In addition, the patient should experience essentially no mobility impairment and it should be the wear of the spacer as low as possible, which can lead to insufficient guidance and stability of the joints. With the present invention, these disadvantages are eliminated and there are a number of other advantages, which are described below.

The stated object is achieved by a spacer or spacer according to claim 1.

Characterized in that the placeholder consists of at least one component of a ceramic or of several ceramic materials, or of a non-ceramic material with a ceramic coating, an increase of the bone to the spacer and a release of wear products is avoided. In addition, the patient essentially learns no mobility restrictions and the wear of the spacer is as low as possible, so that no insufficient guidance and stability of the joints occurs.

Preferably, all exposed surfaces of the at least one ceramic component are polished with contact to biological tissue or processed so that their surface roughness Ra is less than 0.35 μιτι. An increase of the bone is excluded.

To promote the healing process, the at least one ceramic component carries at least in some areas a coating or multiple coatings with one or more antibiotic agents. The placeholder consists in one embodiment of a ceramic shaft with a cantilevered receiving element and on the receiving element is a metallic sleeve attached and on the sleeve, a ceramic ball head is anchored. The placeholder thus consists of the same components as a classic prosthesis. Preferably, the coupling between the shaft and sleeve and between the sleeve and ball head by a conical clamping connection or the coupling between the shaft and sleeve takes place as a clamping connection based on truncated pyramid geometries or form-fitting based on a square geometry, for. to favor the shaping of the shank by uniaxial dry pressing of ceramic powder or the coupling takes place material or form-fitting using bone cement.

The sleeve may also be jammed on the receiving element via one or more stops. To prevent rotation of the shaft in the bone, the bone engaging portion of the shaft has a rectangular or oval shape in cross section.

For a joint replacement in endoprosthetics of the knee, the placeholder preferably consists exclusively of two components, namely a femoral component of bone cement or of a ceramic material and a tibial component of a ceramic material and the femoral component has two mutually parallel sliding surfaces, which on two Bumps arranged parallel to one another are mounted on the tibial component. Preferably, to improve stability, the femoral component between the sliding surfaces is closed.

To avoid rotation, the tibial component on the underside opposite the bulges on a right-angled protruding pin, which is non-circular in cross-section and preferably has an angular or oval cross-section.

The invention thus describes a placeholder (spacer) for the temporary surgical treatment of infections in endoprosthetics, in one or more parts, consisting of one or more ceramic materials in combination with interface modules made of plastic or metal, optionally additionally partially or completely coated with an antibiotic Active substance or antibacterial materials.

Advantageously:

• all exposed surfaces (surfaces in contact with biological tissue) of the spacer are polished or otherwise processed, with the aim of preserving the Reduce surface roughness to reduce bacterial adherence and biofilm formation.

The coating releases one or more antibiotic agents during the time in the human body, e.g. in the form of a gentamicin-containing palmitate layer - alternatively, the coating may also be in the form of antibiotic-acting metals, e.g. Silver or copper, which prevent bacterial colonization without necessarily release active ingredients.

• the release kinetics of the drug can be adapted to the patient's needs, e.g. by multiple layers with different active ingredient concentration and / or layer thickness, if the release in time dependence of the penetration of the layers by body fluids or by degradation of the layers (biological degradation) and thus drug release from outside to inside.

Usable ceramic materials:

• High-purity alumina, in particular the CeramTec material Biolox Forte

• Zirconia-reinforced aluminum oxide (ZTA), in particular the CeramTec material Biolox Delta

• Yttrium stabilized zirconia (3Y-TZP), in particular the CeramTec material MZ1 1 1

Cerium-stabilized zirconium oxide (Ce-TZP), in which the stabilization of the tetragonal phase of the zirconium oxide is carried out by cerium oxide.

• Yttrium-stabilized zirconia with secondary phases containing, for example, strontium aluminates as dispersoids (SHYTZ) and reaching the highest values with regard to the parameter fracture toughness. Of course, all variants of this material are suitable for the component according to the invention.

Also non-oxide ceramic materials, e.g. Silicon nitride Si3N4 may be used as the ceramic material for this invention.

Embodiments for use in hip and shoulder arthroplasty - advantageously:

• The system is modular and consists of a shaft with attached adapter sleeve and a turn plugged ball head or ball segment head. See the figures.

• In principle, the ceramic ball head resembles the conventional ball end caps of hip endoprosthetics, but meets application-related lower requirements with regard to geometry tolerances and surface quality

• The diameter of the ceramic ball head 4 is in the range between 48 and 60 mm, as an articulation against the remaining cavity of the removed

Metal pan in the acetabulum takes place or against the natural acetabulum, if an infection of a hemi-endoprosthesis is present - gradations in 6 mm steps are economically useful, other gradations are of course also possible

· The functional zone of the articulating sphere of the ball head may be smaller than usual in a hip endoprosthesis (spherical segment).

• The coupling between the shaft and sleeve and between the sleeve and the ball head by conical clamping connections - alternatively, the coupling between the shaft and sleeve can also be designed as a clamp connection based on truncated pyramid geometries or positively on

Based on a square geometry, for example, to the shaping of the shaft by uniaxial dry pressing ceramic powder favor - alternatively, the coupling can also be material or form-fitting using intra-operatively on zumischendem bone cement (possibly including antibiotic agent such as gentamicin) take place

If the coupling is made in the case of a conical clamping connection by larger cone diameter than in conventional hip endoprostheses, so as to realize larger stem diameter, which reduces the bending stresses in the ceramic stem neck compared to metal shanks, the sleeve consists of an established implant alloy such as TiAl6V4, CoCrMo, stainless steel or pure titanium - alternatively, the sleeve may also consist of a biocompatible polymer, eg PE, XPE, Vitamin E XPE, PEEK, PEKK, PMMA

belong to a system multiple sleeves, with different inner and / or outer diameters, but only one of which can be used at the same time (not combinable), which allow a variation of the position of the ball head along the shaft neck (so-called "neck jump" or "neck length" )

For example, sleeves made of polymer materials do not have a purely frictional connection (e.g., a conical clamp connection), but additionally have one or more stops which become active upon reaching a predefined stress condition in the clamp connection due to the associated relative displacement

the ceramic shanks on basic forms of known implant systems, the more bone-sparing is the spacer depending on the extracted, infected system (maintaining the existing bony bearing) and / or subsequently to be implanted new or revision system (maintaining the created bony bearing in the process) from an economic point of view can also one Reduced variety of forms are offered, which is based on established, market-leading systems - alternatively, a unitary geometry would also be possible, which allows high quantities with low diversity

• The ceramic shaft has a collar on the proximal part, which provides additional support and thus contributes to both

Sink in the shaft and prevent ingrowth.

Alternatively, a dense ceramic coating can be applied to an established hip stem made of a metallic material, so that the stem is sufficiently similar to a full ceramic stem with respect to the surface or its chemical, physical and biological properties in order to sufficiently increase osseointegration and bacterial colonization to reduce.

The invention will be further explained with reference to figures.

Figure 1 shows a spacer according to the invention or spacer 1, consisting of a shaft 2 with a cantilever receiving element 13 for a sleeve 3 and a head 4. The shaft 2 and the head 4 are made of a ceramic. The sleeve 3 consists in this embodiment of a metal. So that the shaft 2 is implantable against rotation in the bone, it has a rectangular or oval shape in cross-section. FIG. 2 shows the shaft 2 alone. At the marked point A1, it has an anatomical design. At the marked point A2, the shaft has large radii. In area A3 there are only soft transitions in cross section. The shaft has a maximum cross section of 14 ^* 14 mm in the area A4.

Figure 3 shows different sizes of the shaft 2. Figure 4 shows conventional ball heads 5 in comparison to the ball heads 4 for the spacers including the sleeves 3. The ball heads 4 are larger than the conventional ball heads 5 for hip prostheses.

The surface roughness Ra of the shaft 2 after sintering is preferably 0.25 to 0.35. The ball head 4 of the spacer 1 has a surface roughness of preferably 0.1 μιτι.

Design for use in knee arthroplasty:

FIGS. 5a, 5b show the state of the art in knee joint prostheses. This prosthesis consists of a ceramic femoral component 6, a PE component 7 and a ceramic tibia component 8. FIG. 5a shows the prosthesis implanted and FIG. 5b not yet implanted.

FIGS. 6 and 7 show spacers according to the invention for the knee.

FIG. 6 a shows a femoral component 9 made of bone cement, which is mounted on a tibial component 10 according to the invention made of a ceramic. The tibial component 10 consists essentially of a rectangular plateau of a ceramic with bulges 15 on which the femoral component 9 is mounted with its sliding surfaces 14. On its underside, the tibial component 10 on a pin 1 1, which is shaped out of round for security against rotation, for example, has an angular or oval cross-section. Both the femoral component 9 and the tibial component 10 are anchored in the bone with bone cement. In Figures 7a and 7b, an alternative spacer is shown. The femoral component 12 in this embodiment consists of a ceramic, such as the tibial component 10. The tibial component 10 is formed identically with the tibial component 10 according to FIG. 6b.

Advantageously: · The femur component 9, 12 of the spacer has a simplified geometry, oriented on existing spacers made of PMMA materials-alternatively, a universal geometry can be realized which represents the average of the inner contour of the most common implant systems on the market or the Minimai geometry (minimum material condition) of an overlay of these systems • The tibial component 10 is realized in the form of a simplified ceramic plateau, where the joint space is realized by inserting one or more stackable spacer plates

The spacer plates are made of ceramic or a low abrasion polymer, e.g. PE, XPE, Vitamin E-XPE, where the polymer could additionally be filled with one or more antibiotic agents released in vivo

Preparation of ceramic components:

The articulating components can be produced by known manufacturing methods, e.g. uniaxial or isostatic dry pressing, cutting shaping, single or multi-stage sintering (hot isostatic pressing possible but possibly not necessary), grinding and polishing in the sintered state, which reduces grinding and polishing due to lower requirements on tolerances and surface finishes or sub-steps if necessary can be omitted. Shaping of the articulating components could also be accomplished by ceramic injection molding (CIM or LIM).

In the case of use in hip or shoulder arthroplasty, the following methods for producing the shaft 2 are conceivable:

• slip casting

· Dry pressing

• wet pressing

• CIP (cold isostatic pressing) - cold-isostatic pressing with final contour accuracy

• CIM (ceramic injection molding) - ceramic injection molding

• Gelcasting • LIM (low pressure injection molding)

After sintering, if necessary, the surface of the ceramic shaft is mechanically reworked by grinding and / or vibratory finishing and / or polishing in such a way that the surface is as smooth as possible, which does not osseointegrate as little or as little as possible into the bone, and if necessary obstructs the bacterial colonization sufficient adhesion of the coating allows.

In the case of application in hip or shoulder arthroplasty, the metallic sleeve 3 is advantageously produced cost-saving by deep drawing from sheet metal blanks.

Claims

claims

1 . Spacer (1) of individual components (2, 3, 4, 9, 10, 12) as joint replacement in the endoprosthetics of the shoulder, the knee and the hip for the temporary surgical treatment of infections in the joint, characterized in that the placeholder (1) consists of at least one component of one of ceramic or of several ceramic materials, or of a non-ceramic material with a ceramic coating.

2. Platzhalter according to claim 1, characterized in that all exposed surfaces of the at least one ceramic component are polished with contact to biological tissue or processed so that their surface roughness Ra is less than 0.25 μιτι.

3. placeholder according to claim 1 or 2, characterized in that the at least one ceramic component carries at least in some areas a coating or more coatings with one or more antibiotic agents.

4. placeholder according to one of claims 1 to 3 for a joint replacement in the arthroplasty of the hip and the shoulder, characterized in that the placeholder (1) consists of a ceramic shaft (2) with a cantilever receiving element (13) on the receiving element (13) a metallic sleeve (3) is fixed and on the sleeve (3) a ceramic ball head (4) is anchored.

5. Platzhalter according to claim 4, characterized in that the coupling between the shaft (2) and sleeve (3) and between the sleeve (3) and ball head (4) by conical clamping connection or the coupling between the shaft (2) and sleeve (3 ) as a clamping connection based on truncated pyramid geometry or positively based on a square geometry, for example, to favor the shaping of the shank (2) by uniaxial dry pressing ceramic powder or the coupling material or form-fitting is done using bone cement.

6. placeholder according to claim 4, characterized in that the sleeve (3) is clamped on the receiving element (13) via one or more stops.

7. Platzhalter according to one of claims 1 to 6, characterized in that the engaging in a bone portion of the shaft (2) has a rectangular or oval shape in cross section.

8. Platzhalter according to one of claims 1 to 3 for a joint replacement in the endoprosthetics of the knee, characterized in that the placeholder consists exclusively of two components (9, 10 or 10, 12), namely a femoral component (9) made of bone cement or of a ceramic material (12) and of a tibial component (10) made of a ceramic material and the femoral component (9, 12) has two parallel sliding surfaces (14) which are arranged on two mutually parallel vaults (15) on the tibial component (12). 10) are stored.

9. placeholder according to claim 8, characterized in that the femoral component (9, 12) between the sliding surfaces (14) is closed.

10. Platzhalter according to claim 8 or 9, characterized in that the tibial component (10) on the bulges (15) opposite underside has a right-angled protruding pin (1 1), which is non-circular in cross-section and preferably an angular or oval cross-section having.