Particle disease. A comprehensive theory of periprosthetic osteolysis: a review

Prosthetic Metals: Release, Metabolism and Toxicity

The development of metallic joint prostheses has been ongoing for more than a century alongside advancements in hip and knee arthroplasty. Among the materials utilized, the Cobalt-Chromium-Molybdenum (Co-Cr-Mo) and Titanium-Aluminum-Vanadium (Ti-Al-V) alloys are predominant in joint prosthesis construction, predominantly due to their commendable biocompatibility, mechanical strength, and corrosion resistance. Nonetheless, over time, the physical wear, electrochemical corrosion, and inflammation induced by these alloys that occur post-implantation can cause the release of various metallic components. The released metals can then flow and metabolize in vivo, subsequently causing potential local or systemic harm. This review first details joint prosthesis development and acknowledges the release of prosthetic metals. Second, we outline the metallic concentration, biodistribution, and elimination pathways of the released prosthetic metals. Lastly, we discuss the possible organ, cellular, critical biomolecules, and significant signaling pathway toxicities and adverse effects that arise from exposure to these metals.

Quantity and Size of Titanium Particles Released from Different Mechanical Decontamination Procedures on Titanium Discs: An In Vitro Study

Complications such as peri-implantitis could ultimately affect the survival of a dental implant. The prevention and treatment of peri-implant diseases require managing bacterial biofilm and controlling environmental risks, including the presence of pro-inflammatory titanium (Ti) particles in the peri-implant niche. Objectives included the evaluation of the size and quantity of Ti particles released from moderately roughened Ti surfaces during common mechanical surface decontamination methods. One hundred and forty moderately roughened Ti discs were divided into seven groups (n = 20 per group); six groups received mechanical decontamination procedures (ultrasonic scaling (US) with a metal tip and poly-ether-ketone (PEEK) under low and medium power settings, air-polishing with erythritol powder, and Ti brush), and the control group underwent air-water spray using a dental triplex. The rinsing solution was collected for Ti mass analysis using inductively coupled plasma mass spectrometry (ICPMS), as well as for Ti particle size and count analysis under scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). US metal tip instrumentation generated 34.00 ± 12.54 μg and 34.44 ± 6.08 μg of Ti under low and medium power settings, respectively. This amount of Ti generation was significantly higher than other instrumentation methods. The mean Ti particle size of the US groups ranged from 0.89 ± 0.27 μm to 1.25 ± 0.24 μm. No statistically significant difference was found in the particle size among US groups and Ti brush group (1.05 ± 0.11 μm), except for US with the PEEK tip, where a significantly smaller mean particle diameter was found at the low power setting (0.89 ± 0.27 μm). Mechanical instrumentation can produce Ti particulates and modify the implant surfaces. US using a metal tip generated the highest amount of Ti with smaller Ti size particles compared to all other commonly used mechanical surface instrumentations. The EDS analysis confirmed Ti in PEEK US tips. It can be suggested that deterioration from the PEEK US tip and Ti brush, as observed under SEM, is an additional source of Ti release during Ti surface decontamination.

FDG-Avid Periprosthetic Particle Disease Mimicking Osteosarcoma Recurrence

ABSTRACT

A 24-year-old man with a history of osteosarcoma presented with swelling in his right thigh for more than 1 year. 18 F-FDG PET/CT demonstrated increased FDG uptake in multiple juxtacortical masses around the prosthesis, which highly suggested the possibility of osteosarcoma recurrence. A biopsy was performed, and the pathology confirmed the diagnosis of particle disease. The current case indicates that particle disease should be considered when interpreting the PET/CT images with high FDG uptake around the prosthesis.

Efficient prediction of MRI gradient-induced heating for guiding safety testing of conductive implants

PURPOSE

To propose an efficient numerical method to predict the temperature increase of an implantable medical device induced by any linearly polarized homogeneous magnetic field, according to the ISO 10974 methodology for testing of gradient-induced device heating.

THEORY AND METHODS

The concepts of device-specific power and temperature tensors are introduced to mathematically describe the electromagnetic and thermal anisotropic behavior of the device, from which the device heating for an arbitrary exposure direction can be predicted. The proposed method is compared to a brute-force approach based on simulations, and validated by applying it to four reference orthopedic implants with a commercial simulation software.

RESULTS

The proposed method requires about 5% $$ \% $$ of the time required by the brute-force approach, and 30% $$ \% $$ of the memory occupancy. The temperature increase predicted by the proposed method over a range of incident magnetic field exposures deviated from brute-force direct simulations by less than± $$ \pm $$ 0.3% $$ \% $$ .

CONCLUSION

The proposed method allows efficient prediction of the heating of an implantable medical device induced by any linearly polarized homogeneous magnetic field using a small fraction of the simulations required by the brute-force approach. The results can be used to predict the worst-case orientation of the gradient field, for subsequent experimental characterization according to the ISO 10974 standard.

Hypersensitivity and lymphocyte activation after total hip arthroplasty

In the last decades total hip arthroplasty (THA) has become a standard procedure with many benefits but also a few still unsolved complications, which can lead to surgical revision in 19-23% of cases. Thus, aseptic loosening and metal hypersensitivity remain challenges. The phenomenon of wear debris causes chronic inflammation, which produces osteolysis and aseptic loosening. Wear debris promotes osteoclast production and inhibits osteoblasts by secretion of pro-inflammatory cytokines. Micro-abrasions can be induced by abrasive, adhesive and fatigue wear and cause a liberation of metal ions, which lead to another immune response elicited mostly by macrophages. Another reaction in the neocapsule can be a type IV hypersensitivity reaction to various alloys, containing metals such as nickel, cobalt and chromium. Patch testing and the lymphocyte transformation test (LTT) are not the best diagnostic possibilities to exclude a postoperative hypersensitivity reaction, because of the different alignment of the epicutaneous cells compared to the periprosthetic deep tissue. This hypersensitivity reaction is mostly induced by cytokines, which are secreted by macrophages rather than lymphocytes. In cell cultures and in animal studies, multipotent mesenchymal stem cells (MSC) have been shown to play a role in improving initial implant integration, to limit periprosthetic osteolysis and also to reconstitute peri-implant bone stock during implant revision. Thus, MSC might be used in the future to prolong the durability of THA. A better understanding of the interactions between primary chronic inflammation, corrosion, osteolysis and hypersensitivity is mandatory to develop new therapeutic strategies, aiming at the reduction of the incidence of implant failures. In this article the underlying immunological mechanisms to aseptic loosening are presented.

Effects of denosumab treatment on the expression of receptor activator of nuclear kappa-B ligand (RANKL) and TNF-receptor TNFRSF9 after total hip arthroplasty-results from a randomized placebo-controlled clinical trial

We investigated whether the drug denosumab modulates the inflammatory response after total hip arthroplasty in a randomized controlled trial. Significantly increased expression of RANKL was found in patients treated with denosumab. This could provide an explanation for the rebound effect with rapid loss of BMD seen after discontinuation of denosumab treatment.

PURPOSE

To evaluate whether denosumab, a human monoclonal antibody directed against receptor activator of nuclear factor kappa-B ligand (RANKL), modulates the inflammatory response after cementless total hip arthroplasty (THA) in patients with osteoarthritis of the hip.

METHODS

Sixty-four patients operated with cementless THA were randomized to two doses of 60-mg denosumab or placebo 1-3 days and 6 months postoperatively. Serum samples were analyzed by a multiplex extension assay detecting 92 inflammation-related proteins. Bone turnover markers were assessed. Proteins were analyzed using linear mixed effect models. Validation of conspicuous findings was performed with ELISA.

RESULTS

Two proteins were significantly affected by denosumab treatment: RANKL and tumor necrosis factor receptor super family member 9 (TNFRSF9). Serum levels of RANKL were more than twice as high in the denosumab than in the placebo group 3 months after surgery (ratio 2.10, p<0.001). Six and 12 months after surgery, the expression of RANKL was still elevated in the denosumab-treated group (ratios 1.50, p < 0.001; 1.47, p =0.002). The expression of TNFRSF9 was lower in the denosumab group at 3 months (ratio 0.68, p<0.001). In the denosumab group, concentrations of bone turnover markers were substantially reduced after 3 months, remained suppressed after 6 and 12 months, but increased above baseline at 24 months after surgery.

CONCLUSION

Two subcutaneous denosumab injections 6 months apart increase RANKL and depress TNFRSF9 after THA. This provides a possible explanation for the rebound effect on bone turnover markers as well as bone mineral density (BMD) upon withdrawal of denosumab. None of the other measured markers of inflammation was influenced by denosumab treatment.

Energy-Dispersive X-ray Spectroscopic Investigation of Failed Dental Implants Associated with Odontogenic Maxillary Sinusitis

The failed dental implant associated with maxillary sinusitis is a multifactorial phenomenon and should be investigated thoroughly. The inflammatory process induced by accumulated biofilm and wear debris may increase mucous secretion and mucous thickening, which finally may lead to severe complications such as maxillary sinusitis. The inflammatory cytokines might compromise the long-term osseointegration of the related implant. In this study, implants retrieved from three patients who experienced implant failure relating to maxillary sinusitis were investigated using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy. SEM analysis of the implant apical region revealed a less-compact bone structure, indicating the high bone turnover due to an inflammatory process. The ratio of calcium (Ca) and phosphorus (P) was negligible in all specimens. Detection of fluorine (F), sodium (Na), silicon (Si), gold (Au), aluminum (Al), and magnesium (Mg) confirmed the contamination. The selected cases presented different biological aspects that might play the central role in the failed dental implants associated with maxillary sinusitis: the contamination of potentially toxic elements, microorganism infection, and long perforation of implant apex into the sinus. Each of the above phenomena needs to be confirmed with further clinical study with a larger number of failed implants and accompanying tissue samples.

Excessive production of mitochondrion‑derived reactive oxygen species induced by titanium ions leads to autophagic cell death of osteoblasts via the SIRT3/SOD2 pathway

The incidence of peri-implant bone loss is high, and is a difficult condition to treat. Previous studies have shown that titanium (Ti) ions released from implants can lead to osteoblast cell damage, but the specific mechanisms have not been elucidated. The present study established a Ti ion damage osteoblast cell model. The levels of mitochondrion-derived reactive oxygen species (mROS) and autophagy, cell viability and the sirtuin 3 (SIRT3)/superoxide dismutase 2 (SOD2) pathway were examined in this model. It was found that Ti ions decreased osteoblast viability. Moreover, with increased Ti ion concentration, the expression levels of microtubule associated protein 1 light chain 3α (LC3) progressively increased, P62 decreased, autophagic flow increased and mROS levels increased. After the addition of an autophagy inhibitor Bafilomycin A1 and Mito-TEMPO, a mitochondrial antioxidant, the production of mROS was inhibited, the level of autophagy was decreased and cell activity was improved. In addition, with increased Ti ion concentration, the activity of SOD2 decreased, the acetylation level of SOD2 increased, the SIRT3 mRNA and protein expression levels decreased, and the activity of SIRT3 was significantly decreased. Furthermore, it was demonstrated that SIRT3 overexpression reduced the acetylation of SOD2 and increased the activity of SOD2, as well as reducing the production of mROS and the expression level of LC3, thus increasing cell viability. Therefore, the present results suggested that excessive production of mROS induced by Ti ions led to autophagic cell death of osteoblasts, which is dependent on the SIRT3/SOD2 pathway.

Umbilical cord-derived mesenchymal stem cells for treating osteoarthritis of the knee: a single-arm, open-label study

BACKGROUND

Despite being a common cause of quality-of-life impairment, there are no efficacious therapies that could prevent the progression of knee osteoarthritis (KOA). We conducted an open-label trial of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) and hyaluronic acid (HA) for treating KOA.

METHODS

This open-label study was conducted from July 2015 to December 2018 at Cipto Mangunkusumo Hospital, Jakarta, Indonesia. Patients diagnosed with KOA were injected three times, comprising of 10 × 106 units of hUC-MSCs in 2-ml secretome implantation and 2-ml hyaluronic acid (HA) injection in the first week, followed with 2-ml HA injection twice in the second and third week.

RESULTS

Twenty-nine subjects (57 knees) were recruited. Seventeen (58.6%) subjects were male, and the mean age was 58.3 ± 9.6 years. Thirty-three (57.9%) knees were classified into Kellgren-Lawrence grade I-II KOA (mild OA). hUC-MSCs significantly decreased pain measured by visual analogue scale in severe KOA from initial to 6th month follow-up [5 ± 2.97 to 3.38 ± 2.44 (p = 0.035)]. The International Knee Documentation Committee score significantly increased at 6th month follow-up (53.26 ± 16.66 to 65.49 ± 13.01, p < 0.001, in subjects with grade I-II and 48.84 ± 18.41 to 61.83 ± 18.83, p = 0.008, in subjects with severe KOA). The Western Ontario and McMaster Universities Osteoarthritis decreased significantly in both groups from initial to 6th month follow-up (from 22.55 ± 15.94 to 13.23 ± 10.29, p = 0.003, and from 27.57 ± 15.99 to 17.92 ± 19.1, p = 0.003, in those with mild and severe KOA, respectively).

CONCLUSIONS

hUC-MSCs could be a potentially new regenerative treatment for KOA. The maximum effect of hUC-MSCs was achieved after 6 months of injection.

LEVEL OF EVIDENCE

Therapeutic level II.

Influence of single nucleotide polymorphisms (SNPs) in genetic susceptibility towards periprosthetic osteolysis

Wear debris-induced inflammatory osteolysis remains a significant limiting factor for implant replacement surgeries. Hence, a comprehensive understanding of the complex network of cellular and molecular signals leading to these inflammatory responses is required. Both macrophages and monocytes have a critical role in the instigation of the inflammatory reaction to wear debris but differ in the extent to which they induce cytokine expression in patients. Lately, single nucleotide polymorphisms (SNPs) have been associated with genetic susceptibility among individual patients with implant failure. Studies have shown that SNPs in key pro-inflammatory cytokines and their receptors are associated with osteolytic susceptibility. Likewise, SNPs within several genes involved in the regulation of bone turnover have also been found to be associated with wear debris induced osteolysis. It is presumed that SNP variance might play a decisive role in the activation and signaling of macrophages, osteoblasts, chondrocytes, fibroblasts and other cells involved in inflammatory bone loss. Understanding the extent to which SNPs exist among genes that are responsible for inflammatory bone loss may provide potential targets for developing future therapeutic interventions. Herein, we attempt to summarize the various susceptible genes with possible SNP variance that could contribute to the severity of periprosthetic osteolysis in patients with implants.

Lactobacilli can attenuate inflammation in mouse macrophages exposed to polyethylene particles in vitro

Objective

It is well established that polyethylene (PE) wear particles induce macrophage production of cytokines and mediators associated with the pathogenesis of inflammatory osteolysis. The objective of this study was to examine the potential of three Lactobacillus strains to attenuate the TNF-α cytokine response of macrophages exposed to Ceridust 3615 PE particles. An in vitro experimental model using the RAW 246.7 macrophage cell line and PE particles was utilized.

Results

Lactobacillus strains were found to modulate the cytokines in a strain and dose specific manner. Only the Lactobacillus acidophilus strain that was tested was able to attenuate PE particle-induced TNF-α production by RAW 246.7 macrophages. This effect was independent of IL-10 cytokine levels since all three strains of lactobacilli yielded comparable levels of IL-10. It was concluded that some, but not all, Lactobacillus strains may be useful in reducing the risk of inflammatory osteolysis and that further studies in appropriate in vivo models are warranted. Furthermore, this in vitro model can be used to evaluate the inflammatory potential of new materials being tested for use as joint implants.

Polyethylene particles inserted over calvarium induce cancellous bone loss in femur in female mice

Focal bone resorption (osteolysis) induced by wear particles contributes to long-term orthopedic joint failure. However, the impact of focal osteolysis on remote skeletal sites has received less attention. The goal of this study was to determine the effects of polyethylene particles placed over calvaria on representative axial and appendicular skeletal sites in female mice. Because recent work has identified housing temperature as an important biological variable in mice, response to particle treatment was measured in animals housed at room (22 °C) and thermoneutral (32 °C) temperature. Osteolysis was evident in skeletal tissue adjacent to particle insertion. In addition, cancellous bone loss was observed in distal femur metaphysis. The bone loss was associated with lower osteoblast-lined perimeter and lower mineralizing perimeter in distal femur, lower osteocalcin gene expression in tibia, and lower serum osteocalcin, suggesting the response was due, at least in part, to reduced bone formation. Mild cold stress induced by sub-thermoneutral housing resulted in cancellous bone loss in distal femur and lumbar vertebra but did not influence skeletal response to particles. In summary, the results indicate that focal inflammation induced by polyethylene particles has the potential to result in systemic bone loss. This is significant because bone loss is a risk factor for fracture.

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Wear particles contribute to orthopedic joint failure by promoting focal inflammation- mediated osteolysis.

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Here we investigated effects of polyethylene particles placed over calvaria on remote skeletal sites in female mice.

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Particles placed over calvaria resulted in focal inflammation and cancellous bone loss in distal femur metaphysis.

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Lower osteoblast-lined perimeter suggests reduced bone formation contributed to bone loss in distal femur.

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Our results suggest focal inflammation induced by polyethylene particles has the potential to result in systemic bone loss.

The Role of the Chemokine System in Tissue Response to Prosthetic By-products Leading to Periprosthetic Osteolysis and Aseptic Loosening

Millions of total joint replacements are performed annually worldwide, and the number is increasing every year. The overall proportion of patients achieving a successful outcome is about 80–90% in a 10–20-years time horizon postoperatively, periprosthetic osteolysis (PPOL) and aseptic loosening (AL) being the most frequent reasons for knee and hip implant failure and reoperations. The chemokine system (chemokine receptors and chemokines) is crucially involved in the inflammatory and osteolytic processes leading to PPOL/AL. Thus, the modulation of the interactions within the chemokine system may influence the extent of PPOL. Indeed, recent studies in murine models reported that (i) blocking the CCR2–CCL2 or CXCR2–CXCL2 axis or (ii) activation of the CXCR4–CXCL12 axis attenuate the osteolysis of artificial joints. Importantly, chemokines, inhibitory mutant chemokines, antagonists of chemokine receptors, or neutralizing antibodies to the chemokine system attached to or incorporated into the implant surface may influence the tissue responses and mitigate PPOL, thus increasing prosthesis longevity. This review summarizes the current state of the art of the knowledge of the chemokine system in human PPOL/AL. Furthermore, the potential for attenuating cell trafficking to the bone–implant interface and influencing tissue responses through modulation of the chemokine system is delineated. Additionally, the prospects of using immunoregenerative biomaterials (including chemokines) for the prevention of failed implants are discussed. Finally, this review highlights the need for a more sophisticated understanding of implant debris-induced changes in the chemokine system to mitigate this response effectively.

An ideal dielectric coat to avoid prosthesis RF-artefacts in Magnetic Resonance Imaging

The number of people submitted to total hip or knee arthroplasty increased in the last years and it is likely to grow further. Hence, the importance of a proper investigation tool that allows to determine and recognize the potential presence of perioperative and/or postoperative diseases becomes clear. Although the Magnetic Resonance Imaging (MRI) technique demonstrated several advantages over the other common tomography tools, it suffers from the arise of image artefacts if it is performed in presence of metallic prostheses. In particular, the so-called RF-artefacts are caused by the inhomogeneity in the radiofrequency magnetic field of MRI, due to the electric currents induced on the metal surface by the field itself. In this work, a near-zero permittivity dielectric coat is simulated to reduce those currents and, therefore, the RF-artefacts onset in the final image. Numerical results confirm that the dielectric coat strongly reduces the magnetic field inhomogeneity, suggesting a possible solution to a well-known problem in the MRI field.

TNF-α suppression and osteoprotegerin overexpression inhibits wear debris-induced inflammation and osteoclastogenesis in vitro

PURPOSE

Periprosthetic osteolysis, involving RANK/RANKL/osteoprotegerin (OPG) and TNF-α/NFκB signaling, contributes to bone resorption and inflammation. We constructed lentivirus vectors to inhibit TNF-α and enhance OPG expression and assessed their impacts on wear debris-induced inflammation and osteoclastogenesis in an osteoclast/osteoblast coculture system.

METHODS

We transduced mouse osteoblastic MC3T3-E1 cells with Lenti-negative control (Lenti-NC), Lenti-OPG or Lenti-siTNFα-OPG, and murine macrophage/monocyte RAW264.7 cells with Lenti-NC, Lenti-TNF-α siRNA or Lenti-siTNFα-OPG. Then, TNF-α and OPG protein levels were evaluated by enzyme-linked immunosorbent assay. We cocultured transduced MC3T3-E1 and RAW264.7 cells in transwell chambers in the presence of 0.1 mg/mL Ti particles to investigate the capacity of TNF-α inhibition to reduce wear debris-induced inflammation. We also assessed mRNA levels TNF-α, IL-1β, IL-6 and OPG by RT-PCR as well as osteoclastogenesis by tartrate-resistant acid phosphatase.

RESULTS

Lenti-siTNFα-OPG ameliorated Ti-particle-induced expression of TNF-α, IL-1β, IL-6 in MC3T3-E1/RAW264.7 cocultures, while enhancing mRNA and protein levels of OPG, and reducing the fraction of tartrate-resistant acid phosphatase (TRAP)+ cells.

CONCLUSIONS

Lenti-siTNFα-OPG can inhibit the wear debris-induced inflammatory responses and osteoclastogenesis in vitro, and may represent a promising therapeutic candidate for the treatment or prevention of wear particle-induced osteolysis.

Macrophage polarization and activation in response to implant debris: influence by "particle disease" and "ion disease"

Macrophages derive from human embryonic and fetal stem cells and from human bone marrow-derived blood monocytes. They play a major homeostatic role in tissue remodeling and maintenance facilitated by apoptotic "eat me" opsonins like CRP, serum amyloid P, C1q, C3b, IgM, ficolin, and surfactant proteins. Three subsets of monocytes, classic, intermediate, and nonclassic, are mobilized and transmigrate to tissues. Implant-derived wear particles opsonized by danger signals regulate macrophage priming, polarization (M1, M2, M17, and Mreg), and activation. CD14(+) monocytes in healthy controls and CD16(+) monocytes in inflammation differentiate/polarize to foreign body giant cells/osteoclasts or inflammatory dendritic cells (infDC). These danger signal opsonins can be pathogen- or microbe-associated molecular patterns (PAMPs/MAMPs), but in aseptic loosening, usually are damage-associated molecular patterns (DAMPs). Danger signal-opsonized particles elicit "particle disease" and aseptic loosening. They provide soluble and cell membrane-bound co-stimulatory signals that can lead to cell-mediated immune reactions to metal ions. Metal-on-metal implant failure has disclosed that quite like Ni(2+), its neighbor in the periodic table Co(2+) can directly activate toll-like receptor 4 (TLR4) as a lipopolysaccharide-mimic. "Ion disease" concept needs to be incorporated into the "particle disease" concept, due to the toxic, immune, and inflammatory potential of metal ions.

Metal ions as inflammatory initiators of osteolysis

Osteolysis and aseptic loosening currently contribute 75 % of implant failures. Furthermore, with over four million joint replacements projected to be performed in the United States annually, osteolysis and aseptic loosening may continue to pose a significant morbidity. This paper reviews the osteolysis cascade leading to osteoclast activation and bone resorption at the biochemical level. Additionally, the metal ion release mechanism from metallic implants is elucidated. Even though metal ions are not the predominating initiator of osteolysis, they do increase the concentration of key inflammatory cytokines that stimulate osteoclasts and prove to be a contributor to osteolysis and aseptic loosening. Osteolysis is a competitive mechanism among a number of biological reactions, which includes debris release, macrophage and osteoclast activation, an inflammatory response as well as metal ion release. Pharmacological therapy for component loosening has also been reviewed. A non-surgical treatment of osteolysis has not been found in the literature and thus may become an area of future research. Even though this research is warranted, comprehensively understanding the immune response to orthopedic implants and their metallic ions, and thus, creating improved prostheses appears to be the most cost-effective approach to decrease the morbidity related to osteolysis and to design implants with greater longevity. The ionic forms, cytokines, toxicity, gene expression, biological effects, and hypersensitivity responses of metallic elements from metal implants are summarized as well.

Inhibitory effects of ursolic acid on osteoclastogenesis and titanium particle-induced osteolysis are mediated primarily via suppression of NF-κB signaling

Ursolic acid (UA), a pentacyclic triterpenoid found in a variety of plants, has attracted considerable attention because of its important biological and pharmacological activities. However, its effect on osteoclasts and mechanism of action require further investigation. In this study, we evaluated the effects of UA on osteoclastogenesis and osteoclast-mediated osteolysis in vitro and in vivo, and explored its possible mechanism of action. The results indicated that UA could inhibit receptor activator of nuclear factor-κB ligand (RANKL)-mediated osteoclastogenesis and the bone resorptive function of osteoclasts in a concentration-dependent manner in vitro. Further, UA effectively inhibited the mRNA and protein expression of NFATc1, primarily via the suppression of nuclear factor-κB (NF-κB) signaling, and partly through the suppression of c-Jun N-terminal kinase (JNK) signaling. Additionally, UA treatment downregulated the expression of NFATc1-regulated osteoclast marker genes. Likewise, UA induced dose-dependent attenuation of titanium (Ti) particle-induced mouse calvarial bone loss, and decreased the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts. In conclusion, these results demonstrate that UA protects against wear particle-induced osteolysis by suppressing osteoclast formation and function. These effects are associated with the inhibition of the NF-κB- and JNK-related signaling pathways.

Recent patents and designs on hip replacement prostheses

Hip replacement surgery has gone through tremendous evolution since the first procedure in 1840. In the past five decades the advances that have been made in technology, advanced and smart materials innovations, surgical techniques, robotic surgery and methods of fixations and sterilization, facilitated hip implants that undergo multiple design revolutions seeking the least problematic implants and a longer survivorship. Hip surgery has become a solution for many in need of hip joint remedy and replacement across the globe. Nevertheless, there are still long-term problems that are essential to search and resolve to find the optimum implant. This paper reviews several recent patents on hip replacement surgery. The patents present various designs of prostheses, different materials as well as methods of fixation. Each of the patents presents a new design as a solution to different issues ranging from the longevity of the hip prostheses to discomfort and inconvenience experienced by patients in the long-term.

The biological response to a failed extra-articular polyester ligament used for AC Joint reconstruction at the shoulder girdle: a retrieval analysis of five cases

The LockDown device (previously called Surgilig) is a braided polyester mesh which is mostly used to reconstruct the dislocated acromioclavicular joint. More than 11,000 have been implanted worldwide. Little is known about the tissue reaction to the device nor to its wear products when implanted in an extra-articular site in humans. This is of importance as an adverse immunological reaction could result in osteolysis or damage to the local tissues, thereby affecting the longevity of the implant. We analysed the histology of five LockDown implants retrieved from five patients over the last seven years by one of the senior authors. Routine analysis was carried out in all five cases and immunohistochemistry in one. The LockDown device acts as a scaffold for connective tissue which forms an investing fibrous pseudoligament. The immunological response at the histological level seems favourable with a limited histiocytic and giant cell response to micron-sized wear particles. The connective tissue envelope around the implant is less organised than a native ligament.

Genetic susceptibility of early aseptic loosening after total hip arthroplasty: the influence of TIMP-1 gene polymorphism on Chinese Han population

Objective

Genetic factor plays an important role in early failure of total hip arthroplasty (aseptic loosening) etiology, and TIMP-1 gene may be involved. The present study was conducted to reveal possible association between TIMP-1 polymorphisms with the risk of early failure of total hip arthroplasty (THA) (aseptic loosening).

Methods

The TIMP-1 single nucleotide polymorphisms (SNPs) rs4898, rs6609533, and rs2070584 were genotyped in 59 subjects who were diagnosed as aseptic loosening after total hip arthroplasty and in 100 controls.

Results

The TIMP-1 SNP rs4898 T allele in the case group was found to be 1.32 fold (P = 0.0013, 95% CI = 1.16 to 1.58) than the control group. Similarly, the G allele of rs6609533 was found to be associated with increased risk of aseptic loosening (OR = 1.78, 95% CI = 1.52 to 2.17, P < 0.0001). For SNP rs2070584, no statistical association was found (A vs. G, OR = 1.14, 95% CI = 0.97 to 1.40, P = 0.2028).

Conclusion

The results showed that the TIMP-1 SNPs rs4898 and rs6609533 were associated with the increased risk of early aseptic loosening susceptibility.

Release of titanium ions from an implant surface and their effect on cytokine production related to alveolar bone resorption

Although interest in peri-implant mucositis and peri-implantitis has recently been increasing, the mechanisms driving these diseases remain unknown. Here, the effects of titanium ions on the inflammation and bone resorption around an implant were investigated. First, the accumulated amount of Ti ions released into gingival and bone tissues from an implant exposed to sodium fluoride solution was measured using inductively coupled plasma mass spectrometry. Next, the cellular responses in gingival and bone tissues to Ti ions and/or Porphyromonas gingivalis-lipopolysaccharide (P. gingivalis-LPS) were assessed using a rat model. More Ti ions were detected in the gingival tissues around an implant after treatment with sodium fluoride (pH 4.2) than in its absence, which suggests that the fluoride corroded the implant surface under salivary buffering capacity. The injection of Ti ions (9ppm) significantly increased the mRNA expression and protein accumulation of chemokine (C-C motif) ligand 2, as well as the ratio of receptor activator of nuclear factor-κB ligand to osteoprotegerin, in rat gingival tissues exposed to P. gingivalis-LPS in a synergistic manner. In addition, the enhanced localization of toll-like receptor 4, which is an LPS receptor, was observed in gingival epithelium loaded with Ti ions (9ppm). These data suggest that Ti ions may be partly responsible for the infiltration of monocytes and osteoclast differentiation by increasing the sensitivity of gingival epithelial cells to microorganisms in the oral cavity. Therefore, Ti ions may be involved in the deteriorating effects of peri-implant mucositis, which can develop into peri-implantitis accompanied by alveolar bone resorption.

Influence of clinical and radiological variables on the extent and distribution of periprosthetic osteolysis in total hip arthroplasty with a hydroxyapatite-coated multiple-hole acetabular component: a magnetic resonance imaging study

Polyethylene wear-induced osteolysis constitutes the most severe long-term complication of total hip arthroplasties (THA). Our aim was to assess through MRI the severity and growth pattern of osteolysis, as well as the influence clinical-radiographic variables exert. We analyzed 75 THA with an average evolution time of 13.67years. The implant was a titanium alloy, non-cemented, multiple-hole model with hydroxyapatite coating. Osteolysis was found with a peripheral pattern in 48 and a central pattern in 6; in 52 cases it was continuous, and in 4, isolated. Out of 118 screws, 20 exhibited lysis. There was a proportional correlation between osteolysis severity and wear rate with age, physical activity and acetabular abduction, as well as an association between said variables and peripheral and continuous patterns.

Genetic susceptibility to total hip arthroplasty failure: a case-control study on the influence of MMP 1 gene polymorphism

Background

Genetic factors plays an important role in early failure of total hip arthroplasty (THA) etiology and MMP-1 gene polymorphism rs5854 may be involved. The present study was conducted to reveal the possible association between MMP-1 rs5854 C/T polymorphism and the risk of early failure of THA (aseptic loosening).

Methods

The rs5854 single nucleotide polymorphism (SNP) in MMP-1 gene was genotyped in 63 subjects who were diagnosed as aseptic loosening after total hip arthroplasty within 10 years and in 81 age and gender matched controls.

Results

The genotype frequencies of the MMP-1 rs5854 C/T polymorphism were 57.1% (CC), 28.6% (CT), and 14.3% (TT) in patients with failure of THA, and 79.0% (CC), 17.3% (CT), and 3.7% (TT) in the controls (P = 0.0099). Rs5854 polymorphism was found to be significantly associated with increased risk of aseptic loosening.

Conclusion

The results showed the rs5854 SNP was associated with increased risk of the early aseptic loosening susceptibility.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_177

Periprosthetic bone loss: diagnostic and therapeutic approaches

Total joint replacement surgery is being performed on an increasingly large part of the population. Clinical longevity of implants depends on their osseointegration, which is influenced by the load, the characteristics of the implant and the bone-implant interface, as well as by the quality and quantity of the surrounding bone. Aseptic loosening due to periprosthetic osteolysis is the most frequent known cause of implant failure. Wear of prosthetic materials results in the formation of numerous particles of debris that cause a complex biological response. Dual-energy X-ray Absorptiometry (DXA) is regarded as an accurate method to evaluate Bone Mineral Density (BMD) around hip or knee prostheses. Further data may be provided by a new device, the Bone Microarchitecture Analysis (BMA), which combines bone microarchitecture quantification and ultra high resolution osteo-articular imaging. Pharmacological strategies have been developed to prevent bone mass loss and to extend implant survival. Numerous trials with bisphosphonates show a protective effect on periprosthetic bone mass, up to 72 months after arthroplasty. Strontium ranelate has been demonstrated to increase the osseointegration of titanium implants in treated animals with improvement of bone microarchitecture and bone biomaterial properties.

Wear Debris Characterization and Corresponding Biological Response: Artificial Hip and Knee Joints

Wear debris, of deferent sizes, shapes and quantities, generated in artificial hip and knees is largely confined to the bone and joint interface. This debris interacts with periprosthetic tissue and may cause aseptic loosening. The purpose of this review is to summarize and collate findings of the recent demonstrations on debris characterization and their biological response that influences the occurrence in implant migration. A systematic review of peer-reviewed literature is performed, based on inclusion and exclusion criteria addressing mainly debris isolation, characterization, and biologic responses. Results show that debris characterization largely depends on their appropriate and accurate isolation protocol. The particles are found to be non-uniform in size and non-homogeneously distributed into the periprosthetic tissues. In addition, the sizes, shapes, and volumes of the particles are influenced by the types of joints, bearing geometry, material combination, and lubricant. Phagocytosis of wear debris is size dependent; high doses of submicron-sized particles induce significant level of secretion of bone resorbing factors. However, articles on wear debris from engineered surfaces (patterned and coated) are lacking. The findings suggest considering debris morphology as an important parameter to evaluate joint simulator and newly developed implant materials.

Effects of ginsenosides rg1 on osteoblasts cultured with ti particles

The aim of this study was to explore the role and effect of ginsenosides Rg1 on osteoblasts cultured with Ti particles. Osteoblasts from neonatal rats were cultured with particles and different doses of Rg1, the main active ingredient in ginsenosides Rg1. We found that the COX-2, PGE₂, TNF-α, IL-1, and IL -6 concentrations in the medium of cells cultured with Ti particles significantly increased as compared with that of the control cells (p<0.05 or p<0.01). In addition, cells cultured with Ti particles alone exhibited the highest concentrations of these molecules. The PGE₂, TNF-α, IL-1, and IL-6 levels in the medium of cells cultured with Rg1 were in between those of the control cells and the cells cultured with Ti particles alone. The IL-1ra level in the group cultured with Ti and medium-dose Rg1 was the highest followed by the cells cultured with Ti and high-dose Rg1 and those cultured with Ti and low-dose Rg1 (p<0.05). In conclusion, ginsenosides can reduce the levels of inflammatory cytokines produced by osteoblasts on induction with Ti particles and can prevent prosthesis loosening.

NF-κB signaling and bone resorption

The transcription factor NF-κB is a family of proteins involved in signaling pathways essential for normal cellular functions and development. Deletion of various components of this pathway resulted with abnormal skeletal development. Research in the last decade has established that NF-κB signaling mediates RANK ligand-induced osteoclastogenesis. Consistently, it was shown that inhibition of NF-κB was an effective approach to inhibit osteoclast formation and bone resorptive activity. Identification of the molecular machinery underlying NF-κB activation permitted osteoclast-specific deletion of the major components of this pathway. As a result, it was clear that deletion of members of the proximal IKK kinase complex and the distal NF-κB subunits and downstream regulators affected skeletal development. These studies provided several targets of therapeutic intervention in osteolytic diseases. NF-κB activity has been also described as the centerpiece of inflammatory responses and is considered a potent mediator of inflammatory osteolysis. Indeed, inflammatory insults exacerbate physiologic RANKL-induced NF-κB signals leading to exaggerated responses and to inflammatory osteolysis. These superimposed NF-κB activities appear to underlie several bone pathologies. This review will describe the individual roles of NF-κB molecules in bone resorption and inflammatory osteolysis.

The Irish National Joint Registry: where are we now?

BACKGROUND

Ireland is currently in the process of establishing a National Joint Registry.

AIM

We aim to determine which implants and surgical techniques are currently being used by Irish orthopaedic surgeons and to examine the impact that a National Joint Registry may have on arthroplasty practice in Ireland.

METHODS

The study consisted of a postal questionnaire sent to all public service consultant orthopaedic surgeons in The Republic of Ireland.

RESULTS

We had a response rate of 76.6 %. Of this 76.6, 86.4 % regularly perform total hip arthroplasty (THA) and 84.7 % perform total knee arthroplasty. Of those who perform THA, 86.3 % use different implants in younger patients. Thirteen different femoral implants are used, and seven different knee implants. We conservatively estimate that at least 3,918 total hip arthroplasties and 2,604 total knee arthroplasties are performed in Ireland each year. At present we have no way to precisely monitor the number of arthroplasty procedures being performed, and we have no way of accurately monitoring the short- or long-term outcomes of the many implants used.

CONCLUSIONS

The establishment of a National Joint Registry for Ireland would benefit the Irish orthopaedic community, and given the large number of procedures being performed, may also be of benefit to the international orthopaedic community.

Adenovirus-mediated small interfering RNA targeting tumor necrosis factor-α inhibits titanium particle-induced osteoclastogenesis and bone resorption

Wear particles are phagocytosed by macrophages, resulting in cellular activation and the release of pro-inflammatory factors, which cause periprosthetic osteolysis and subsequent aseptic loosening, the most common causes of total joint arthroplasty (TJA) failure. During this pathological process, tumor necrosis factor (TNF)-α plays an important role in wear particle-induced osteolysis. Therefore, in this study, we used adenovirus-mediated small interfering RNA (siRNA) targeting TNF-α to suppress the TNF-α release from activated macrophages in response to titanium particles. Our results showed that recombinant adenovirus (Ad-TNF-α-siRNA) suppressed the TNF-α release from activated macrophages in response to titanium particles, and reduced titanium particle-induced osteoclastogenesis and bone resorption in the presence of receptor activator of nuclear factor-κB ligand (RANKL). In addition, the conditioned medium of macrophages challenged with titanium particles (Ti CM) stimulated osteoprogenitor RANKL expression. The conditioned medium of macrophages challenged with titanium particles and Ad-TNF-α-siRNA (Ti-Ad CM) reduced the mRNA expression in MC3T3-E1 cells compared to Ti CM. Based on these data, TNF-α strongly synergizes with RANKL to promote osteoclast differentiation. Furthermore, TNF-α promoted osteoclast differentiation by stimulating osteoprogenitor RANKL expression. Ad-TNF-α-siRNA effectively suppressed osteoclast differentiation and bone resorption following exposure to titanium particles in the presence of RANKL. In addition, recombinant adenovirus (Ad-TNF-α-siRNA) does not have a toxic effect on the murine macrophage cell line, RAW264.7. Consequently, it can be concluded that recombinant adenovirus-mediated siRNA targeting TNF-α (Ad-TNF-α-siRNA) may provide a novel therapeutic approach for the treatment of periprosthetic osteolysis.

Presence of interleukin-17C in the tissue around aseptic loosened implants

PURPOSE

The most common long-term complication of joint arthroplasty is aseptic loosening. The proinflammatory cytokines secreted by macrophages are involved in aseptic loosening. Recently, a novel proinflammatory cytokine IL-17C was reported to participate in inflammatory diseases by synergising with proinflammatory cytokines. However, the relationship between IL-17C and the aseptic loosening is unclear.

METHODS

The tissues around aseptic loosened implants were collected during revision surgery and handled by formalin fixation and embedded in paraffin. The presence of IL-17C in the tissues around the aseptic loosened implants was investigated in 12 aseptic loosening patients using immunofluorescence.

RESULTS

The presence of IL-17C protein in the tissues around aseptic loosened implants was detected by immunofluorescence. There are no statistical differences between optical density of IL-17C in aseptic loosening samples and in rheumatoid arthritis samples (positive control).

CONCLUSIONS

These results suggest the presence of IL-17C in aseptic loosening. Interleukin-17C was related to the inflammation of aseptic loosening, possibly by contributing to the inflammation and osteolysis in the tissues surrounding aseptic loosened implants.

Blockade of JNK and NFAT pathways attenuates orthopedic particle-stimulated osteoclastogenesis of human osteoclast precursors and murine calvarial osteolysis

Particles released from orthopedic implants attract immune host defense cells to the bone-implant interface and contribute to development of inflammation. The inflammatory microenvironment supports recruitment and differentiation of osteoclasts, the primary culprit of osteolysis. Therefore, understanding the complex signals that contribute to osteoclastogenesis and osteolysis is a sensible approach to design strategies to inhibit bone loss. The signaling cascades that coordinate osteoclastogenesis have been widely investigated. These include MAP kinases, Akt/PI3K pathway, NF-κB signal transduction pathway, and NFAT pathway. We have recently reported that polymethylmethacrylate (PMMA) particles activate the NFAT pathway in murine osteoclast precursors and that NFAT inhibitors dose-dependently block PMMA-induced osteoclastogenesis. In the current study, we examined the role of JNK and NFATc1 in mice in response to PMMA particles using murine calvaria model. We show that locally administered MAPK/JNK inhibitor SP600125 and calcineurin/NFAT inhibitor cyclosporine-A effectively blocked PMMA-induced osteolysis in murine calvaria. To buttress the clinical relevance of JNK/NFATc1-based regulation of PMMA-induced osteoclastogenesis, we evaluated the effect of PMMA using human macrophages. We demonstrate that SP600125 and cyclosporine-A abolished particle-induced osteoclastogenesis in human osteoclast progenitors retrieved from patients undergoing total hip replacement. Thus JNK and NFATc1 appear to act as significant mediators of orthopedic particle-induced osteolysis in humans.

miR-21 expression is related to particle-induced osteolysis pathogenesis

Previous studies have found that microRNA-21 (miR-21) is an important functional factor during osteoclast differentiation. Abnormal osteoclastogenesis induced by wear particles is the main cause of aseptic loosening in joint replacements. The aim of the present study is to investigate the possible role of miR-21 in the pathogenesis of particle-induced osteolysis (PIO). miR-21 expression was examined in a PIO mouse model using real-time (RT-PCR). Osteoclastogenesis was determined by a tartrate resistant acid phosphatase (TRAP) quantification method. A toluidine blue staining assay was used to examine calvarial osteolysis. The results demonstrated that miR-21 was significantly upregulated in the PIO animal model. Knocking out miR-21 in the particle-stimulated tissue could ameliorate osteolysis symptoms. Additionally, through our analysis of PDCD4 and AP-1 expression, we suggest that the feedback loop of AP-1, miR-21, and PDCD4 might have an important influence on the development of PIO and that miR-21 is a potential target for implant loosening therapies.

Advantages and disadvantages of ceramic on ceramic total hip arthroplasty: a review

BACKGROUND

Ceramic on ceramic (COC) total hip arthroplasty (THA) was developed to reduce wear debris and accordingly, the occurrence of osteolysis and aseptic loosening especially in younger patients. Based on the excellent tribological behavior of current COC bearings and the relatively low biological activity of ceramic particles, significant improvement in survivorship of these implants is expected.

METHODS

We used manual search to identify all relevant studies reporting clinical data on COC THAs in PubMed. The objective was to determine whether current COC THA offers a better clinical outcome and survivorship than non-COC THA.

RESULTS

Studies with early generation ceramic bearings yielded 68% to 84% mean survivorship at 20 years follow-up which is comparable with the survivorship of non-COC THAs. Studies on current ceramic bearings report a 10-year revision-free interval of 92% to 99%. These outcomes are comparable to the survivorship of the best non-COC THAs. However, there are still concerns regarding fracture of sandwich ceramic liners, squeaking, and impingement of the femoral neck on the rim of the ceramic liner leading to chipping, especially in younger and physically active patients.

CONCLUSION

Current COC THA leads to equivalent but not improved survivorship at 10 years follow-up in comparison to the best non-COC THA. Based on this review, we recommend that surgeons weigh the potential advantages and disadvantages of current COC THA in comparison to other bearing surfaces when considering young very active patients who are candidates for THA.

Comparison of the cytotoxic and inflammatory responses of titanium particles with different methods for endotoxin removal in RAW264.7 macrophages

It is generally accepted that periprosthetic bone resorption is initiated through aseptic inflammation aggravated by wear particles that are generated from artificial joint. However, some studies have demonstrated that "endotoxin-free" wear particles are almost completely unable to stimulate the macrophage-mediated production of proinflammatory cytokines. Here, we compare the titanium particles with different methods of endotoxin removal. The results indicated that different titanium particle preparation dosages did not significantly change particle size, morphology, and chemical composition. But it could cause variations in the endotoxin concentration of titanium particles and inflammatory responses in RAW264.7 macrophages. The particles with higher endotoxin levels correlated with more extensive inflammatory responses. When testing endotoxins using the supernatant of particle suspensions, it would lead to false negative results compared with testing the particle themselves. And when using the particles themselves, all the particles should be removed by centrifugation to avoid particle interference before the absorbance value was determined. Therefore, we suggest that research concerning wear particles should completely describe the endotoxin testing process, including endotoxin removal from particles and the details of endotoxin testing. Moreover, future research should focus on the surface of wear particles (the potential role of adherent endotoxin) rather than the particles themselves.

Are periprosthetic tissue reactions observed after revision of total disc replacement comparable to the reactions observed after total hip or knee revision surgery?

STUDY DESIGN

Comparative study.

OBJECTIVE

To compare periprosthetic tissue reactions observed after total disc replacement (TDR), total hip arthroplasty (THA), and total knee arthroplasty (TKA) revision surgery.

SUMMARY OF BACKGROUND DATA

Prosthetic wear debris leading to particle disease, followed by osteolysis, is often observed after THA and TKA. Although the presence of polyethylene (PE) particles and periprosthetic inflammation after TDR has been proven recently, osteolysis is rarely observed. The clinical relevance of PE wear debris in the spine remains poorly understood.

METHODS

The number, size, and shape of PE particles, as well as quantity and type of inflammatory cells in periprosthetic tissue retrieved during CHARITÉ TDR (n = 22), THA (n = 10), and TKA (n = 4) revision surgery were compared. Tissue samples were stained with hematoxylin/eosin and examined by using light microscopy with bright field and polarized light.

RESULTS

After THA, large numbers of PE particles of size less than 6 μm were observed, which were mainly phagocytosed by macrophages. The TKA group had a broad size range with many larger PE particles and more giant cells. In TDR, the size range was similar to that observed in TKA. However, the smallest particles were the most prevalent with 75% of the particles being less than 6 μm, as seen in revision THA. In TDR, both macrophages and giant cells were present with a higher number of macrophages.

CONCLUSION

Both small and large PE particles are present after TDR revision surgery compatible with both THA and TKA wear patterns. The similarities between periprosthetic tissue reactions in the different groups may give more insight into the clinical relevance of PE particles and inflammatory cells in the lumbar spine. The current findings may help to improve TDR design as applied from technologies previously developed in THA and TKA with the goal of a longer survival of TDR.

Genetic susceptibility to aseptic loosening following total hip arthroplasty: a systematic review

Introduction Aseptic loosening is the most common cause of total hip arthroplasty (THA) failure and revision surgery. Genetic polymorphisms could be determinant factors for implant loosening. Source of data We performed a comprehensive search of Medline, CINAHL, Googlescholar, Embase and Cochrane databases, using various combinations of the keyword terms 'aseptic loosening', 'gene', 'hip arthoplasty', 'genetics', 'loosening'. Twelve studies detailing the genetic investigation of patients with aseptic loosening of a THA were identified. Areas of agreement SNPs of GNAS1, TNF-238 A allele, TNF-α promoter (-308G→A) transition, IL6-174 G allele, interleukin (IL)-6 (-597) and (-572), MMP-1-promoting gene, C/C genotype for the MMP1, MT1-MMP, MMP-2, transforming growth factor-beta1 signal sequence (29T→C) transitions, A/A genotype for the OPG-163, and MBL were overexpressed in patients with aseptic loosening and periprosthetic osteolysis. Areas of controversy Data from single centre studies do not allow one to compare the results of different studies. Conclusion Several gene pathways and genes contribute to the genetic susceptibility to aseptic loosening following THA. Further studies will enhance the understanding of prosthesis failure, and may inform and direct pharmaceutical interventions. Growing points Further multi-centre prospective studies are necessary to confirm the general validity of the findings reported. Single-centre findings should be replicated in other centres and populations to open new avenues for pre-surgical genetic testing and to investigate immune response modulation in THA. Areas timely for developing research Research in this field could lead to better understanding of mechanisms behind aseptic osteolysis, and improve the results of THA.

Do tissues from THA revision of highly crosslinked UHMWPE liners contain wear debris and associated inflammation?

BACKGROUND

Polyethylene wear debris is a major contributor to inflammation and the development of implant loosening, a leading cause of THA revisions. To reduce wear debris, highly crosslinked ultrahigh-molecular-weight polyethylene (UHMWPE) was introduced to improve wear properties of bearing surfaces. As highly crosslinked UHMWPE revision tissues are only now becoming available, it is possible to examine the presence and association of wear debris with inflammation in early implant loosening.

QUESTIONS/PURPOSES

We asked: (1) Does the presence of UHMWPE wear debris in THA revision tissues correlate with innate and/or adaptive immune cell numbers? (2) Does the immune cell response differ between conventional and highly crosslinked UHMWPE cohorts?

METHODS

We collected tissue samples from revision surgery of nine conventional and nine highly crosslinked UHMWPE liners. Polarized light microscopy was used to determine 0.5- to 2-μm UHMWPE particle number/mm2, and immunohistochemistry was performed to determine macrophage, T cell, and neutrophil number/mm2.

RESULTS

For the conventional cohort, correlations were observed between wear debris and the magnitude of individual patient macrophage (ρ=0.70) and T cell responses (ρ=0.71) and between numbers of macrophages and T cells (ρ=0.77) in periprosthetic tissues. In comparison, the highly crosslinked UHMWPE cohort showed a correlation between wear debris and the magnitude of macrophage responses (ρ=0.57) and between macrophage and T cell numbers (ρ=0.68). Although macrophages and T cells were present in both cohorts, the highly crosslinked UHMWPE cohort had lower numbers, which may be associated with shorter implantation times.

CONCLUSIONS

The presence of wear debris and inflammation in highly crosslinked UHMWPE revision tissues may contribute to early implant loosening.

Magnetic resonance imaging near metal implants

The desire to apply magnetic resonance imaging (MRI) techniques in the vicinity of embedded metallic hardware is increasing. The soft-tissue contrast available with MR techniques is advantageous in diagnosing complications near an increasing variety of MR-safe metallic hardware. Near such hardware, the spatial encoding mechanisms utilized in conventional MRI methods are often severely compromised. Mitigating these encoding difficulties has been the focus of numerous research investigations over the past two decades. Such approaches include view-angle tilting, short echo-time projection reconstruction acquisitions, single-point imaging, prepolarized MRI, and postprocessing image correction. Various technical advances have also enabled the recent development of two alternative approaches that have shown promising clinical potential. Here, the physical principals and proposed solutions to the problem of MRI near embedded metal are discussed.

Particle disease on fluoride-18 (NaF) PET/CT imaging

Particle disease is a loss of bone that commonly occurs about five years after arthroplasty. The cause is secondary to microabrasive wear and shedding of any portion of the prosthesis, and the microscopic foreign bodies activate inflammation which can lead to pain. This report describes the imaging findings of an 80-year-old female with particle disease detected with 18F-fluoride PET/CT.

Titanium ion induces necrosis and sensitivity to lipopolysaccharide in gingival epithelial-like cells

Gingival epithelial-like cells (GE-1) were cultured and used to examine the cellular responses of gingival tissues to varying concentrations of titanium (Ti) ions. Titanium ions at concentrations of more than 13 ppm significantly decreased the viability of GE-1 cells and increased LDH release from the cells into the supernatant, but had no significant effect on their caspase 3 activity. These data suggest that a high concentration of Ti ions induced necrosis of the GE-1 cells. Titanium ions at a concentration of 5 ppm significantly increased the level of CCL2 mRNA expression in GE-1 cells exposed to lipopolysaccharide derived from Porphyromonas gingivalis in a synergistic manner. Moreover, the mRNA expression levels of TLR-4 and ICAM-1 in GE-1 cells loaded with Ti ions at 9 ppm were significantly enhanced as compared with those in GE-1 cells without Ti stimulation. We suggest that Ti ions are in part responsible for monocyte infiltration in the oral cavity by elevating the sensitivity of gingival epithelial cells to microorganisms. Taken together, these data indicate that Ti ions may be involved in cytotoxicity and inflammation at the interfaces of dental implants and gingival tissue.

Impact of titanium ions on osteoblast-, osteoclast- and gingival epithelial-like cells

PURPOSE

To investigate the effects of titanium (Ti) ions on the cell viability, the cell differentiation and the gene expressions related to bone resorption including Receptor Activator of NF-kappaB Ligand (RANKL) and Osteoprotegerin (OPG) in the tissues around dental implants, the osteoblast-, osteoclast-, and gingival epithelial-like cells were exposed to Ti ions.

METHODS

An MTS assay was carried out to evaluate the viabilities of osteoblast-like MC3T3-E1, osteoclast-like RAW264.7 and epithelial cell-like GE-1 cells. The gene expressions in these cells were analyzed by the use of RT-PCR and real-time quantitative RT-PCR.

RESULTS

Ti ions in the concentration range 1-9 ppm had little effect on the viabilities of MC3T3-E1, RAW264.7 and GE-1, whereas 20 ppm Ti ions significantly decreased the viabilities of all cells. Analyses of RT-PCR and real-time quantitative RT-PCR data revealed that Ti ions at 9 ppm remarkably inhibited the expressions of Runx2, Osterix and type I collagen in MC3T3-E1. In RAW264.7, Ti ions showed no effects on the levels of mRNAs for TRAP and cathepsin K enhanced by RANKL. Ti ions at the range of 1-9 ppm showed no effects on the levels of mRNAs for RANKL and OPG in GE-1, while Ti ions at 9 ppm enhanced the expression of these genes in MC3T3-E1.

CONCLUSIONS

These results, taken together, suggested that Ti ions show the biological effects, both on the viabilities of osteoblast and osteoclast and on the differentiation of either the osteoblastic or osteoclastic cells, which may influence the prognosis of dental implants.

Optical 3D methods for measurement of prosthetic wear of total hip arthroplasty: principles, verification and results

Total hip arthroplasty (THA) significantly improves the quality of life in majority of patients with severe osteoarthritis. However, long-term outcomes of THAs are compromised by aseptic loosening and periprosthetic osteolysis which needs revision surgery. Both of these are causally linked to a prosthetic wear deliberated from the prosthetic articulating surfaces. As a result, there is a need to measure the mode and magnitude of wear. The paper evaluates three optical methods proposed for construction of a device for the non-contact prosthetic wear measurement. Of them, the scanning profilometry achieved promising combination of accuracy and repeatability. Simultaneously, it is time efficient to enable the development of a sensor for wear measurement.

[Classification of prosthetic loosening and determination of wear particles]

Nowaday, loosening of orthopaedic implants implies important medical and socioeconomic problems. Implant loosening is caused by implant infections as well as aseptic loosening, due to particle disease and mechanical alterations. Clinically we divide the implant infection into early and late infections. Morphologically it is possible to reliably detect the infection by quantification of neutrophil granulocytes. Additionally molecular methods are suitable to detect micro-organisms which are responsible for the prosthetic joint infection including their resistance to antibiotics. Particle disease may be reproducibly classified by the detection of different types of wear particles, particularly polyethylene, metal, ceramic and cement. The aetiology of the indeterminate type of the periprosthetic membrane is obscure, but may be associated with osteopathies. This classification of the periprosthetic membrane morphology provides clinically significant information concerning clinical management of implant loosening.