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Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_4 | Pages 7 - 7
1 Apr 2019
Paulus A Dirmeier S Hasselt S Kretzer P Bader R Jansson V Utzschneider S
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Introduction

It is well-known that wear debris generated by metal-on-metal hip replacements leads to aseptic loosening. This process starts in the local tissue where an inflammatory reaction is induced, followed by an periprosthetic osteolysis. MOM bearings generate particles as well as ions. The influence of both in human bodies is still the subject of debate. For instance hypersensitivity and high blood metal ion levels are under discussion for systemic reactions or pseudotumors around the hip replacement as a local reaction. The exact biopathologic mechanism is still unknown. The aim of this study was to investigate the impact of local injected metal ions and metal particles.

Material and Methods

We used an established murine inflammation model with Balb/c mice and generated three groups. Group PBS (control group, n=10) got an injection of 50µl 0.1 vol% PBS-suspension, Group MI (Metal-ion, n=10) got an injection of 50µl metal ion suspension at a concentration of 200µg/l and Group MP (Metal-particles, n=10) got an injection of 50µl 0.1 vol% metal particle suspension each in the left knee. After incubation for 7 days the mice were euthanized and the extraction of the left knee ensued. Followed by immunhistochemical treatment with markers of inflammation that implied TNFα, IL-6, IL-1β, CD 45, CD 68, CD 3, we counted the positive cells in the synovial layer in the left knees by light microscopy, subdivided into visual fields 200× magnified. The statistical analysis was done with Kruskal-Wallis test and a post hoc Bonferroni correction.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_5 | Pages 80 - 80
1 Mar 2017
Paulus A Ebinger K Hasselt S Jansson V Bader R Kretzer J Utzschneider S
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Introduction

Metal on metal bearings are used especially in hip resurfacing. On the one hand, small bone preserving implants can be used. On the other hand recent studies found a variety of local and systemic side effects, for instance the appearance of pseudotumors, that are explained by pathologic biological reaction of the metal wear debris. The detailed mechanisms are still not understood until now. Thus it was the aim of this study to investigate the local reaction of metal wear particles and metal ions in a murine model. The hypothesis was that mainly metal ions provoke adverse histopathological reactions in vivo.

Material and Methods

Three groups, each with 10 Balb / c mice were generated. Group A: injection of a 50 µl metal ion suspension at a concentration of 200 µg / l in the left knee. Group B: injection of a 50 µl 0,1 vol% metal particle suspension into the left knee joint. Group C (control group): injection of a 50 µl of 0,1 vol% PBS-suspension in the left knee. Incubation for 7 days, followed by euthanasia of the animals by intracardiac pentobarbital. The left and right knee, the lungs, kidneys, liver and spleen were removed. Histologic paraffin sections in 2 microns thickness were made, followed by HE (overview staining) and Movat (Pentachrom staining) staining. The histologic analysis was a done by a light microscopic evaluation of the subdivided visual fields at 200× magnification.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_10 | Pages 98 - 98
1 May 2016
Utzschneider S Paulus A Hasselt S Jansson V Giurea A Neuhaus H Grupp T
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Introduction

The complex process of inflammation and osteolysis due to wear particles still is not understood in detail. So far, Ultra-high-molecular-weight-polyethylene (UHMWPE) is the bearing material of choice in knee arthroplasty and revision knee arthroplasty, but there is a growing demand for alternative bearing materials with improved wear properties. Lately, increasing interest developed in the use of natural and carbon-fiber-reinforced-poly-ether-ether-ketones (CFR-PEEK).

While there is a lack of data concerning the effects of CFR-PEEK particles on human tissue, the effects of such wear debris in vitro and in animal studies is controversially discussed.

The aim of this study was to analyze human tissue containing CFR-PEEK as well as UHMWPE wear debris.

The authors hypothesized no difference between the used biomaterials because of similar size parameters of the wear particles in a prior knee simulator study of this implant.

Methods and Materials

Synovial tissue samples of 10 patients while knee revision surgery of a rotating hinge knee implant design (Enduro®, Aesculap, Germany) were achieved. The tibial inserts of this design were made from UHMWPE (GUR 1020), whereas the bushings and flanges are made of CFR-PEEK containing 30% polyacrylonitrile (PAN) based carbon fibers (PEEK-Optima LT1, Invibio Ltd. Thornton-Cleveleys, UK). In a prior in vitro test most of the released CFR-PEEK particles were in a size range between 0.1 and 2μm. The implant survival until revision surgery was 22 (2.5–48 min.-max.) months. As a control synovial tissue out of a patient also got knee revision surgery without any PEEK components.

The tissue was fixed with 4% paraformaldehyde, embedded in paraffin, sliced into 2 µm thick sections

stained with hematoxylin and eosin in a standard process. A modified panoptical staining (preincubation in propylenglycol; >3h; 35°C) was also done which stained the UHMWPE particles turquoise.

The study was approved by the ethics committee of the local university.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_9 | Pages 123 - 123
1 May 2016
Paulus A Brosseder S Schroeder C Jansson V Grupp T Schwiesau J Utzschneider S
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Introduction

The complex cellular mechanisms of the aseptic loosening of total joint arthroplasties still remain not completely understood in detail. Especially the role of adherent endotoxins in this process remains unclear, as lipopolysaccharides (LPS) are known to be very potent modulators of the cell response on wear particle debris. Contributing factors on the LPS affinity of used orthopedic biomaterials as their surface roughness have to be investigated. The aim of this study was to evaluate the affinity of LPS on the surface roughness of different biomaterials in vitro. The hypothesis of the study was that rough surfaces bind more LPS than smooth surfaces.

Materials and methods

Cubes with a side length from ultra-high-molecular-weight-polyethylene (UHMWPE), crosslinked polytethylene (XPE), carbon fibre reinforced poly-ether-ether-ketone (CFR-PEEK), titanium, titanium alloy, Polymethyl methacrylate (PMMA), implant steel (CoCr) and instrument steel (BC) were produced (figure 1). Cubes of each material have been produced with a rough and a smooth surface. Before the testings, all cubes and used materials were treated with E-Toxa-Clean(®) to eliminate pre-existing LPS on the used surfaces. The cubes were then fixed on the cap of a glass that was filled with a LPS solution with a concentration of 5 IE/ml. After 30 minutes the cube was removed and the LPS concentration in the supernatant was measured. The endotoxin content of each sample was evaluated by a Limulus Amoebocyte Lysate (LAL) - Test (Lonza, Verviers, Belgium). The detection level of endotoxin was set at < 0.005 EU/ml diluted 1/10.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 80 - 80
1 Sep 2012
Utzschneider S Lorber V Dedic M Paulus A Sievers B Jansson V
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Periprosthetic osteolysis depends on the biological activity of wear particles, but there is little known about the distribution of polyethylene wear particles (PE) in the surrounding joint tissue. The purpose of this study was to examine the localisation of wear particles of six different PEs, including four crosslinked polyethylenes (XPE), as well as their biological activity in the murine knee.

Material and Methods

Wear particles of 4 XPE- and 2 UHMWPE-inserts were isolated (knee joint simulator). For all groups the particles were similar in size and shape (mean diameter 0.3–05μm; 20nm-nucleopore-filter; ISO; n = 100.000).56 female Balb/c mice were randomly assigned to six treatment groups and one control group: control (PBS), XPE1 (3×30 kGy Gamma, annealed/sequential irradiated), XPE2 (95 kGy E-beam, remelted), XPE3 (65 kGy E-beam, remelted), XPE 4 (50 kGy Gamma, remelted), UHMWPE 1, UHMWPE 2. 50 μl of each particle suspension [(0.1% vol/vol (particle volume/PBS volume) after removal of endotoxin] were injected into the left knee joint. After 1 week the mice were killed and a histological and immunhistochemical analysis of the knee joints was done (IL-1, TNF-, ICAM-1). For the immunhistochemistry the articular cartilage, the bone marrow and the synovial membrane were evaluated semiquantitatively (Kruskal-Wallis test; all pairwise multiple comparison procedure; Bonferoni correction; significance level: p<0.05).

Results

All groups showed a thickened synovial layer with an increased cellular infiltration. The particles of XPE 1 and 2 were localised in the bone marrow as well as in the joint space. In contrast, the particles of XPE 3 and 4 were distributed in the synovial layer and in the bone marrow as well, but not in the joint space. The UHMWPE1 particles were mainly located in the bone marrow and joint space while the UHMWPE2 particles were mainly found in the bone marrow and the synovial layer. For all PE groups there was a higher cytokine expression compaired to control (p<0.0024) without any differences between the groups (bone marrow/synovial layer). The chondrocytes in the groups with XPE 1- and XPE 2-particles expressed more TNF- than in the control group and the other treatment groups (p = 0.000).


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_II | Pages 222 - 222
1 May 2011
Utzschneider S Dedic M Paulus A Schroeder C Sievers B Gottschalk O Sadoghi P Jansson V
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Crosslinked polyethylene (XPE) was developed to reduce wear in hip and knee arthroplasty. Periprosthetic osteolysis depends on many factors including biological activity of wear particles. This study examines the relative inflammatory effect of different crosslinked polyethylenes compared to ultra-high-molecular-weight-polyethylene (UHMWPE) particles in vivo.

Materials and Methods: Wear particles of 3 XPE- (1 sequential irradiated/annealed; 2 remelted inserts) and 1 UHMWPE-insert were isolated from a knee joint simulator (20nm-nucleopore-filter;acid digestion method;ISO). Particles were analysed by scanning electron microscopy (n=66000). For all groups the particles were smooth, granular, irregular and less fibrillar. More than 85% of the particles were submicron. After removal of endotoxin the particles were suspended in a phosphate buffered saline solution (0.1% vol/vol (particle volume/PBS volume)). Endotoxin levels were controlled using standardised endotoxin detection tests (Lonza) in all samples.

40 female Balb/c mice were randomly assigned to one of five treatment groups (according to the national guidelines of animal protection laws): control (n=8); XPE1 (95 kGy E-beam, remelted; n=8); XPE2 (65 kGy E-beam, remelted; n=8), XPE3 (3x30 kGy Gamma, annealed and sequential irradiated; n=8) and UHMWPE particles (n=8). 50 μl of the particle suspension were injected into the murine left knee under sterile conditions. The leukocyte–endothelial cell interactions and the synovial microcirculation were performed by intra-vital fluorescence microscopy one week after particle injection to assess the inflammatory reaction to the particles (by measuring the rolling fraction of leukocytes, the adherent cells and the functional capillary density (FCD)). Data analysis was performed using a computer-assisted microcirculation analysis system (Cap-Image).

For the statistical analysis the Kruskal-Wallis test was used to determine differences within the groups, followed by an all pairwise multiple comparison procedure with a Bonferoni correction. The level of significance was set at p< 0.05.

Results: The fraction of the rolling leukocytes, adherent cells and FCD increased significantly (p< 0.05) in all bio-materials compared to control group. However, there was no significant difference between the UHMWPE and the XPE particle groups (p> 0.05).

Conclusion: Our data suggest that crosslinked polyethylene wear particles do not lead to a higher inflammatory reaction in vivo compared to UHMWPE particles.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_IV | Pages 621 - 621
1 Oct 2010
Utzschneider S Datz J Harrasser N Jansson V Paulus A Plitz W
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Osteolsyis is one of the main reasons for revision of total joint replacements. The osteolytic reaction is influenced by dose, size (particles < 1μm are believed to be biologically more active) and shape of wear particles, so that low wear rates and biologically less active particles are required.

In addition, in the knee a range of design and kinematic variables have to be considered as they can markedly influence wear regardless of the type of polyethylene used. Furthermore, UHMWPE (ultra-high-molecular-weight-polyethylene) fatigue occurs more frequently in the knee joint than in the hip joint due to its changing tribocontact areas combined with high weight bearing. This is why crosslinked polyethylene (XPE) is still controversially discussed for use in total knee prostheses.

Question: Is XPE appropriate for both fixed- and mobile-bearing knee prostheses? Are XPE-particles different from UHMWPE-particles?

Method: In a knee-joint-simulator (Stallforth-Ungeth-uem) 4 XPE (1 sequential irradiated/annealed, 3 different remelted, fixed- and mobile-bearing-types) and 2 UHMWPE-inserts (fixed- and mobile-bearing) were tested (ISO). The gravimetric wear rates (mg/year) were measured (5mill. cycles), the wear mechanism was analysed by scanning electron microscope (SEM). Furthermore, 100.000 particles were analysed by SEM (20nm-nucleo-pore-filter;acid digestion method;ISO) in size and shape.

Results: All the inserts showed traces of abrasion, scratching and wear polishing. XPEs produced lower wear rates (range 0,6–4,3mg/year;p< 0,05) than UHM-WPEs (range 8,4–8,5mg/year) in fixed- as well as mobile-bearing knee prostheses without fatigue reactions. The sequentially irradiated and annealed insert showed the lowest wear rate (0,6mg/year;p< 0,05) overall. For all the groups the particles were smooth, granular, irregular and less fibrillar and more than 85% of the particles were submicron. The particle size was independent of the radiation dose. Fixed-bearings produced a larger amount of particles < 1μm (93,2–96,3%;p< 0,05) than mobile-bearings (85,5–89,5%).

Conclusion: All crosslinked tibial inserts, fixed- as well as mobile-bearings, showed statistically significant (p< 0.05) reduced wear rates without any fatigue reactions. The fixed-bearing sequential irradiated and annealed insert had the lowest wear rate (p< 0.05). XPEs (fixed- and mobile-bearings) and UHMWPEs have similar wear particles in shape. The particle size was independent of the radiation dose, but most of the particles are in the biologically more active range of size (fixed> mobile-bearing). Due to this further investigation with in-vivo-models is required.