The biology of aseptic osteolysis

Assessing the reliability of automated cell count analysis of synovial fluid in the setting of revision total knee arthroplasty

PURPOSE

The diagnostic challenges of periprosthetic joint infection (PJI) for orthopedic surgeons are significant. Prior research has indicated that patients with adverse reactions, dislocations, and aseptic loosening exhibit a heightened count of white blood cells (WBC) in their synovial fluid, along with an increased polymorphonuclear cell percentage (PMN%). The prevalence of false-positive results raises concerns about the reliability of these tools in distinguishing aseptic failure from PJI.

METHODS

We have performed a retrospective inquiry of the medical records of all patients who have undergone aseptic revision total knee arthroplasty (TKA) at our tertiary referral arthroplasty center. We conducted an assessment on 552 knees by applying the guidelines set forth by the 2018 International Consensus Meeting. Recorded preoperative parameters: aspiration results (WBC, PMN%, and AD immunoassay), preoperative and intraoperative diagnoses, microbiologic and histopathologic findings from periprosthetic tissue samples, and prosthetic details.

RESULTS

Among the causes of aseptic revision investigated, patients with polyethylene wear exhibited the highest median WBC count (median 1091 cells/µL, range 83.5-1715.5 cells/µL; p = 0.010). Concerning periprosthetic conditions, patients with wear-induced synovitis exhibited a significantly higher synovial fluid WBC count (median 1093 cells/µL, range 587-1683 cells/µL; p < 0.001). Among all the reasons for failure, periprosthetic fractures had the greatest percentage of WBC counts surpassing 3000 cells/µL (18.1% [2 of 11]; p = 0.006).

CONCLUSION

Our study has uncovered significant variations in WBC count during aseptic revision TKA when utilizing automated cell counting. Therefore, to optimize diagnostic accuracy in synovial aspiration during aseptic revision TKA, it is advisable to employ a combination of WBC count and PMN%, along with manual counting techniques or AD, depending on the specific clinical scenario.

LEVEL OF EVIDENCE

III.

Angiopoietin 1 Relieves Osteolysis by Promoting Macrophage Mitophagy Through the TBK1-SQSTM1 Pathway to Inhibit AIM2 Inflammasome-Mediated Pyroptosis

Osteolysis resulting from wear particles and subsequent aseptic loosening is a leading cause of revision surgery of artificial joints. The underlying pathogenesis of particle-induced osteolysis (PPO) has remained largely uncertain. Addressing how to mitigate osteolysis caused by wear particles presents a significant challenge for orthopedic surgeons. This study aimed to explore the molecular mechanism by which Angiopoietin (Ang-1) inhibits osteoclast activation to alleviate osteolysis. RAW264.7 mouse macrophages were stimulated with LPS or RANKL to induce osteoclast formation. Additionally, titanium (Ti) particles (50 mg) were subperiosteally implanted around the cranial suture of mice to establish a calvarial osteolysis model. Ang-1, a member of the pro-angiogenic factor protein family and an important inflammatory regulator molecule, was utilized in this model. TRAP staining was utilized to detect osteoclast activation, while a western blot was conducted to identify key proteins associated with mitophagy and pyroptosis. Scanning electron microscopy was employed to observe the morphology and dimensions of Ti particles. Additionally, a combination of micro-CT, H&E, Masson's trichrome, and immunohistochemical staining techniques were applied to analyze the calvarial samples. Results indicated that Ang-1 could inhibit LPS- or RANKL-induced osteoclastogenesis and alleviate Ti particle-induced calvarial osteolysis in mice. TBK-1, a key signaling molecule involved in initiating mitophagy, was found to be mechanistically enhanced by Ang-1 through promoting TBK-1 phosphorylation in macrophages. This process inhibited AIM2 inflammasome-mediated pyroptosis and impeded osteoclastogenesis. Overall, this research uncovers a novel mechanism by which Ang-1 can attenuate inflammatory osteolysis, potentially offering a new therapeutic approach for PPO.

Association between the canal filling ratio and bone resorption in trabecular metal stems in reverse total shoulder arthroplasty: a radiographic analysis using tomosynthesis

Background

Several factors affect the incidence of osteopenia with cortical narrowing (CNO) in reverse shoulder arthroplasty. This study aimed to compare the incidence of CNO with different fixation methods (cemented or cementless) using a single implant (trabecular metal humeral stem) evaluated using tomosynthesis and to analyze the factors affecting the incidence of CNO for cementless stem fixation.

Methods

A total of 109 patients (cementless: 75 cases; cemented: 34 cases) who underwent reverse total shoulder arthroplasty were included in this study. The patients were divided into 2 groups (cementless or cemented), and the incidence of CNO was compared. In addition, patients in the cementless group were divided into 2 groups (canal filling ratio [CFR] of ≥ 0.7 or < 0.7), the incidence of CNO was compared, and the Cramer's coefficient of association between CNO and CFR > 0.7 (and 0.8) was calculated.

Results

No significant difference was observed in the incidence of CNO between the cementless and cemented groups (7/75 vs. 3/35, P value = 1.0). The association between CNO and the CFR using Cramer's coefficient of association showed that there were few correlations (coefficient: 0.14, P value = .59).

Conclusion

Cementless reverse total shoulder arthroplasty with a trabecular metal stem has a similar low incidence of CNO as cemented fixation, and the incidence of CNO with a trabecular metal stem was lower than that reported in previous studies. A CFR > 0.7 was not associated with the incidence of CNO.

Artemisinic acid attenuates osteoclast formation and titanium particle-induced osteolysis via inhibition of RANKL-induced ROS accumulation and MAPK and NF-κB signaling pathways

Periprosthetic osteolysis (PPO) is the most common cause of joint arthroplasty failure. Its progression involves both biological and mechanical factors. Osteoclastogenesis induced by wear from debris-cell interactions, ultimately leading to excessive bone erosion, is considered the primary cause of PPO; therefore, targeting osteoclasts is a promising treatment approach. Currently available drugs have various side effects and limitations. Artemisinic acid (ArA) is a sesquiterpene isolated from the traditional herb Artemisia annua L. that has various pharmacological effects, such as antimalarial, anti-inflammatory, and antioxidant activities. Therefore, this study was aimed at investigating the effect of ArA on osteoclast formation and bone resorption function in vitro, as well as wear particle-induced osteolysis in vivo, and to explore its molecular mechanism of action. Here, we report that ArA inhibits RANKL-stimulated osteoclast formation and function. Mechanistically, ArA suppresses intracellular reactive oxygen species levels by activating the antioxidant response via nuclear factor erythroid-2-related factor 2 (Nrf2) pathway upregulation. It also inhibits the mitogen-activated kinases (MAPK) and nuclear factor-κB (NF-κB) pathways, as well as the transcription and expression of NFATc1 and c-Fos. In vivo experiments demonstrated that ArA reduces osteoclast formation and alleviates titanium particle-induced calvarial osteolysis. Collectively, our study highlights that ArA, with its osteoprotective and antioxidant effects, is a promising therapeutic agent for preventing and treating PPO and other osteoclast-mediated osteolytic diseases.

Warfarin and bisphosphontes interaction in patients undergoing total knee arthroplasty

Background

Patients undergoing knee arthroplasty (TKA) surgery need anticoagulant therapy, mainly warfarin for prevention of venous thromboembolism (VTE). Warfarin is mainly eliminated by renal glomerular filtration where 92 % of warfarin is excreted in urine. Warfarin overdose may lead to significant bleeding and warfarin underdosing may cause VTE and other complications. Thus, international normalized ratio (INR) monitoring is crucial in TKA patients taking warfarin. Great interest has been expressed in bisphosphonate to reduce periprosthetic osteoporosis in patients undergoing total joint arthroplasty. Many human case reports and cohort studies proved bisphosphonates induced impaired renal function.

Objectives

The main goal of the current study is to examine the pharmacodynamin effect of bisphosphonates on warfarin excretion and clinical effects in patients undergoing TKA surgery.

Methods

Fifty patients undergoing TKA were recruited in the current study. Twenty five patients were given warfarin and twenty five patients were given warfarin and bisphosphonates starting three days after surgery. INR, major bleeding events and minor bleeding events were followed up in all recruited patients for one month after surgery.

Results

warfarin plus zoledronic acid group had significantly higher percent of post INR greater than 4 (p = 0.022) and significantly higher percent of minor bleeding events (p = 0.041) than warfarin only group.

Conclusion

Concomitant administration of bisphosphonates may increase warfarin bleeding adverse effects in elderly patient undergoing TKA.

Injectable Self-Healing Oxidized Starch/Gelatin Hybrid Hydrogel for Preventing Aseptic Loosening of Bone Tissue Engineering

Aseptic loosening presents a formidable challenge within the realm of bone tissue engineering, playing a pivotal role in the occurrence of joint replacement failures. The development of therapeutic materials characterized by an optimal combination of mechanical properties and biocompatibility is imperative to ensure the enduring functionality of bone implants over extended periods. In this context, this study introduced an injectable, temperature-sensitive irisin/oxidized starch/gelatin hybrid hydrogel (I-OG) system. The hierarchical cross-linked structure endows the I-OG hydrogel with controlled and adjustable physical and chemical properties, making it easy to adapt to different clinical environments. This hydrogel exhibits satisfactory injectable properties, excellent biocompatibility, and good temperature sensitivity. The sol-gel point of the I-OG hydrogel, close to the body temperature, allows it to cushion the shaking of the implant and maintain an intact state during compression of bone tissue. Significantly, the I-OG hydrogel effectively filled the gap between the implant and bone tissue, successfully inhibiting aseptic loosening induced by titanium particles, a result that confirmed the slow release of the irisin protein from the gel. Collectively, the findings from this study strongly support the proposition that functional hydrogels, typified by the I-OG system, hold substantial promise as an accessible and efficient treatment strategy for mitigating aseptic loosening.

Lack of Consensus on the Definition of Aseptic Loosening in Total Ankle Replacement: A Narrative Systematic Review

Background: Aseptic loosening is one of the most common modes of failure of total ankle replacement (TAR). However, a precise definition of aseptic loosening is still lacking. This systematic review aimed to identify the variations of applied definitions and offer insights into the lack of consensus. Methods: Human studies reporting aseptic loosening of TAR published in peer-reviewed journals within the last decade were considered. The search strategy involved specific terms in Embase, MEDLINE ALL, and the Cochrane Library. Variations in aseptic loosening definitions were analysed. Results: Of 767 studies, 88 were included in this study. Only nine studies precisely defined aseptic loosening with significant variations. Twenty-two studies referenced the term and fifty-seven reported it as a complication but neither defined nor referenced it. Conclusions: Significant uncertainty exists regarding the universal definition of aseptic loosening of TAR, and many variations occur in terms of the assessment approach and criteria.

Effect of functionalized titanium particles with dexamethasone-loaded nanospheres on macrophage polarization and activity

OBJECTIVE

The aim of this study was to determine the effect of titanium micro particles (TiP) previously functionalized with nanoparticles doped with dexamethasone (Dex) and doxycycline (Dox), on macrophage polarization and activity.

METHODS

Macrophages RAW264.7 were cultured in the presence TiP loaded with dexamethasone -NPs (Dex)- and doxycycline -NPs (Dox)-, and as control, TiP with or without doped NPs. Cells were tested with and without previous bacterial lipopolysaccharide endotoxin (LPS) stimulation. Their morphology, proliferation, cytotoxicity, phenotypic change, and cytokines release were assessed by LIVE/DEAD, DNA release, metabolic activity, brightfield and scanning electron microscopy. The test Kruskall-Wallis was used for comparisons, while the cytokine expression profiles were examined by hierarchical clustering (p < 0.05).

RESULTS

Upon exposure with TiP macrophages were activated and polarized to M1, but without depicting cytotoxic effects. The particles were phagocytised, and vacuolized. When exposed to functionalised TiP with NPs(Dex) and NPs(Dox), the ratio M1/M2 was up to forty times lower compared to TiP alone. When exposed to LPS, TiP reduced cell viability in half. Functionalised TiP with NPs(Dex) inhibited the cytokine release exerted by TiP on macrophages. When macrophages were exposed to functionalised TiPs with NPs(Dex) with and without LPS, the effect of TiP on cytokine secretion was inhibited.

SIGNIFICANCE

Functionalised TiPs with NPs(Dex) and NPs(Dox) may potentially have beneficial effects on modulating titanium and LPS-related inflammatory reactions.

Impact of humeral stem length on calcar resorption in anatomic total shoulder arthroplasty

BACKGROUND

Use of standard-length anatomic total shoulder (TSA) humeral stems has been associated with high rates of medial calcar bone loss. Calcar bone loss has been attributed to stress shielding, debris-induced osteolysis, and undiagnosed infection. Short stem and canal-sparing humeral components may provide more optimal stress distribution and thus lower rates of calcar bone loss related to stress shielding. The purpose of this study is to determine whether implant length will affect the rate and severity of medial calcar resorption.

METHODS

A retrospective review was performed on TSA patients treated with three different-length humeral implants (canal-sparing, short, and standard-length designs). Patients were matched 1:1:1 based on both gender and age (±4 years), resulting in 40 patients per cohort. Radiographic changes in medial calcar bone were evaluated and graded on a 4-point scale, from the initial postoperative radiographs to those at 3 months, 6 months, and 12 months.

RESULTS

The presence of any degree of medial calcar resorption demonstrated an overall rate of 73.3% at one year. At 3 months, calcar resorption was observed in 20% of the canal-sparing cohort, while the short and standard designs demonstrated resorption in 55% and 52.5%, respectively (P = .002). At 12 months, calcar resorption was seen in 65% of the canal-sparing design, while both the short and standard designs had a 77.5% rate of resorption (P = .345). The severity of calcar resorption for the canal-sparing cohort was significantly lower at all time points when compared to the short stem (3 months, P = .004; 6 months, P = .003; 12 months, P = .004) and at 3 months when compared to the standard-length stem (P = .009).

CONCLUSION

Patients treated with canal-sparing TSA humeral components have significantly lower rates of early calcar resorption with less severe bone loss when compared to patients treated using short and standard-length designs.

Translational Characterization of Macrophage Responses to Stable and Non-Stable CoCrMo Wear and Corrosion Debris Generated In-Situ for Total Hip Replacement

Metal wear and corrosion debris remain a limiting factor for long-term durability of total hip replacement (THR). Common wear particle production techniques for research differ from the actual tribocorrosion processes at the implant site, potentially causing loss of valuable information. The aim of this study was to investigate reactions to freshly generated and time-stabilized particles and ions released from CoCrMo-alloy using a bio-tribometer, which mimics conditions of the periprosthetic environment. THP-1 macrophages were challenged with freshly produced or time-stabilized wear debris. Wear generation took place in a custom-built bio-tribometer inside a CO2 incubator operating with a reciprocating rotation of an Al2O3 ball against a CoCrMo disc. Two different electrochemical conditions with increasingly forced corrosion rates were tested: +0.45 V (passive domain) and +0.67 V (transition to transpassive domain). Cell viability, proinflammatory cytokines, electrochemical measurements and ICP-MS metal ion content analyses were performed. Cobalt/ chromium concentrations were 6.6/ 1.6 ppm in the passive domain and almost doubled to 11.4/ 3.0 ppm in the passive-transpassive domain. Under those electrochemical conditions, freshly produced and time-stabilized CoCrMo wear decreased cell viability to the same extent. Secretion of proinflammatory cytokines were not significantly different for freshly produced and time-stabilized debris. This study suggests that freshly generated and time-stabilized metal particles/ions cause similar toxicity and inflammatory reactions in macrophages, indicating that standard practices for generating wear debris are valid methods to evaluate wear particle disease. Other cell types, materials, and corrosion potentials need to be studied in the future to solidify the conclusion.

Use of Femoral Head Allograft for Extended Bone Loss in Revision Total Ankle Arthroplasty: A Case Report

CASE

A 38-year-old male patient presented with severe ankle pain 13 years after a total ankle arthroplasty (TAA). Radiographic evaluation revealed loosening of the implant and extensive osteolytic lesions. The medial tibial plafond and malleolus were reconstructed using a fresh-frozen femoral head graft, and revision TAA was performed. The midterm results were satisfactory, with adequate integration of the allograft and stable implant components.

CONCLUSION

The use of the allograft technique in revision TAA is feasible in the presence of severe bone loss, including the malleoli, and allows firm component fixation of the reconstructed bone.

SOST gene suppression stimulates osteocyte Wnt/β-catenin signaling to prevent bone resorption and attenuates particle-induced osteolysis

The most common cause for prosthetic revision surgery is wear particle-induced periprosthetic osteolysis, which leads to aseptic loosening of the prosthesis. Both SOST gene and its synthetic protein, sclerostin, are hallmarks of osteocytes. According to our previous findings, blocking SOST induces bone formation and protects against bone loss and deformation caused by titanium (Ti) particles by activating the Wnt/β-catenin cascade. Although SOST has been shown to influence osteoblasts, its ability to control wear-particle-induced osteolysis via targeting osteoclasts remains unclear. Mice were subjected to development of a cranial osteolysis model. Micro CT, HE staining, and TRAP staining were performed to evaluate bone loss in the mouse model. Bone marrow-derived monocyte-macrophages (BMMs) made from the C57BL/6 mice were exposed to the medium of MLO-Y4 (co-cultured with Ti particles) to transform them into osteoclasts. Bioinformatics methods were used to predict and validate the interaction among SOST, Wnt/β-catenin, RANKL/OPG, TNF-α, and IL-6. Local bone density and bone volume improved after SOST inhibition, both the number of lysis pores and the rate of skull erosion decreased. Histological research showed that β-catenin and OPG expression were markedly increased after SOST inhibition, whereas TRAP and RANKL levels were markedly decreased. In-vitro, Ti particle treatment elevated the expression of sclerostin, suppressed the expression of β-catenin, and increased the RANKL/OPG ratio in the MLO-Y4 cell line. TNF-α and IL-6 also elevated after treatment with Ti particles. The expression levels of NFATc1, CTSK, and TRAP in osteoclasts were significantly increased, and the number of positive cells for TRAP staining was increased. Additionally, the volume of bone resorption increased at the same time. In contrast, when SOST expression was inhibited in the MLO-Y4 cell line, these effects produced by Ti particles were reversed. All the results strongly show that SOST inhibition triggered the osteocyte Wnt/β-catenin signaling cascade and prevented wear particle-induced osteoclastogenesis, which might reduce periprosthetic osteolysis. KEY MESSAGES: SOST is a molecular regulator in maintaining bone homeostasis. SOST plays in regulating bone homeostasis through the Wnt/β-catenin signaling pathway. SOST gene suppression stimulates osteocyte Wnt/β-catenin signaling to prevent bone resorption and attenuates particle-induced osteolysis.

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.

BMP-2 functional polypeptides relieve osteolysis via bi-regulating bone formation and resorption coupled with macrophage polarization

Osteolysis caused by wear debris around the prosthesis is the main reason for aseptic loosening. Extending prosthetic service life is still challenging. In this study, we first synthesized a bone morphogenetic protein-2 (BMP-2) functional polypeptide (BMP2pp), and evaluated the effects of BMP2pp on macrophage polarization and impaired osteogenesis caused by titanium (Ti) particles in vitro. Then, we delineated the impact of BMP2pp on bone formation and resorption in a mouse calvarial bone osteolysis model induced by Ti particles. The results showed that BMP2pp not only alleviated the Ti-induced inhibition of osteoblastic differentiation in human placenta-derived mesenchymal stem cells (hPMSCs) but also prevented Ti-induced M1 macrophage polarization and promoted M2 macrophage differentiation in mice. Conditioned medium from BMP2pp-activated macrophages increased the osteogenesis of hPMSCs. The western blot results indicated a significant decrease in the expression of NF-κB inducing kinase (NIK) and phospho-NF-κB p65 in bone marrow-derived macrophages treated with BMP2pp. Furthermore, we clarified the protective effect of BMP2pp on bone formation and the reduction in bone resorption coupled with the immunomodulatory properties of calvarial osteolysis in mice. In summary, BMP2pp ameliorated the Ti-mediated impairment in osteogenic potential of hPMSCs, suppressed the M1 polarization of macrophages by inhibiting the activation of the NF-κB signaling pathway, and ameliorated Ti-induced bone osteolysis. Our research suggests that BMP2pp may be a potential option for treating prosthetic loosening induced by wear debris from prostheses.

Anterior Bone Loss after Cervical Baguera C Disc versus Bryan Disc Arthroplasty

OBJECTIVES

The objectives of this study were to identify the risk factors and incidence of anterior bone loss (ABL) after Baguera C cervical disc arthroplasty (CDA) and identify whether design differences in artificial discs affect ABL.

METHODS

In this retrospective radiological review of patients who underwent single-level Baguera C CDA in a medical center, the extent of ABL and the following radiological parameters were recorded: global and segmental alignment angle, lordotic angle (or functional spinal unit angle), shell angle, global range of motion (ROM), and ROM of the index level. ABL at the index level was grade 0-2. Grade 0 was defined as no remodeling, grade 1 as spur disappearance or mild change in body contour, and grade 2 as obvious bone regression with Baguera C Disc exposure.

RESULTS

Combining grade 1 and grade 2, ABL was found in 56 upper adjacent vertebrae and 52 lower adjacent vertebrae of the 77 patients. Only 18 patients (23.4%) had no ABL. Shell angle differed significantly between ABL grades of both the upper and lower adjacent level: 0.0° in grade 0 and 1 ABL vs. 2.0° in grade 2 ABL of the upper adjacent level (p < 0.05); and 0.0° in grade 0 and 1 ABL vs. 3.5° in grade 2 ABL of the lower adjacent level (p < 0.05). A female predominance of ABL was found. Hybrid surgery and artificial disc size were also related to ABL.

CONCLUSIONS

ABL is more common in Baguera C Disc arthroplasty than Bryan Disc arthroplasty. Larger shell angle was related to ABL after CDA with Baguera C Discs, which may indicate that shell angle is pivotal in determining the incidence of ABL after CDA. Females had more ABL with Baguera C Disc arthroplasty; this might be related to shorter endplate lengths as well as a smaller endplate-implant mismatch.

Vitamin E-added Highly Cross-Linked Polyethylene Decreases the Risk of Osteolysis in an In Vivo Arthroplasty Model

Introduction Aseptic loosening is one of the most important complications of arthroplasty surgery. It is known that immune response against particles plays role in the pathogenesis of aseptic loosening. Polyethylene (PE) has an important place in these particles. There are limited in vivo studies examining aseptic loosening caused by PE residues. Objective The aim of the present study is to evaluate the aseptic loosening created by highly cross-linked PE (HXLPE) and vitamin E-added PE particles in an in vivo knee prosthesis model. Materials and methods Thirty-nine male Sprague-Dawley rats, which were randomized into three groups, were included in the study. After surgical exposure of knee joints of rats, femoral intramedullary canals were drilled and instilled with isolated saline solution and saline solution that contained standard PE or vitamin E-added PE particles according to their groups. Afterwards, a titanium implant was placed on the femoral articular surface of each animal. Rats received intraarticular injections weekly of the same solution, which was initially instilled into their femoral canal. The rats were sacrificed at the end of the third week and then underwent radiological and histopathological evaluations. Result In histopathological evaluation, periprosthetic membrane formation, inflammatory cell change, and cellular damage of cartilage and bone tissue around the implant were assessed. There was a statistically lesser amount of cellular damage and periprosthetic membrane formation in the vitamin-E/HXLPE group compared to the HXLPE group (p=0.04, p=0.001). No significant difference was found between the PE groups with respect to inflammatory cells (p=0.715). Conclusions HXLPE caused more significant osteolysis compared to VE-HXLPE. Antioxidants in PE could provide a reduction in osteolysis and aseptic loosening.

Ion release and local effects of titanium metal particles from dental implants: An experimental study in rats

BACKGROUND

The objective of this study was to evaluate the accumulation of ions in blood and organs caused by titanium (Ti) metal particles in a mandibular defect in rats, together with a description of the local reaction of oral tissues to this Ti alloy debris.

METHODS

Twenty Sprague-Dawley rats were randomly distributed into three groups: an experimental group with a mandibular bone defect filled with metallic debris obtained by implantoplasty; a positive control group; and a negative control group. Thirty days after surgery, the rats were euthanized and perilesional tissue surrounding the mandibular defect was removed, together with the lungs, spleen, liver, and brain. Two blood samples were collected: immediately before surgery and before euthanasia. The perilesional tissue was histologically analyzed using hematoxylin-eosin staining, and Ti, aluminum, and vanadium ion concentrations in blood and organs were measured by TQ-ICP-MS. Descriptive and bivariate analyses of the data were performed.

RESULTS

All rats with implanted metal debris showed metal particles and a bone fracture callus on the osseous defect. The metal particles were surrounded by a foreign body reaction characterized by the presence of histiocytes and multinucleated giant cells (MNGCs). The experimental group had a significant higher concentration of Ti ions in all studied organs except lung tissue (p < 0.05). In addition, there were more V ions in the brain in the experimental group (p = 0.008).

CONCLUSIONS

Although further studies are required to confirm the clinical relevance of these results, Ti metal particles in the jaw might increase the concentration of metal ions in vital organs and induce a foreign body reaction.

Novel Tuning of PMMA Orthopedic Bone Cement Using TBB Initiator: Effect of Bone Cement Extracts on Bioactivity of Osteoblasts and Osteoclasts

Bone cement containing benzoyl peroxide (BPO) as a polymerization initiator are commonly used to fix orthopedic metal implants. However, toxic complications caused by bone cement are a clinically significant problem. Poly (methyl methacrylate) tri-n-butylborane (PMMA-TBB), a newly developed material containing TBB as a polymerization initiator, was found to be more biocompatible than conventional PMMA-BPO bone cements due to reduced free radical generation during polymerization. However, free radicals might not be the only determinant of cytotoxicity. Here, we evaluated the response and functional phenotypes of cells exposed to extracts derived from different bone cements. Bone cement extracts were prepared from two commercial PMMA-BPO cements and an experimental PMMA-TBB. Rat bone marrow-derived osteoblasts and osteoclasts were cultured in a medium supplemented with bone cement extracts. More osteoblasts survived and attached to the culture dish with PMMA-TBB extract than in the culture with PMMA-BPO extracts. Osteoblast proliferation and differentiation were higher in the culture with PMMA-TBB extract. The number of TRAP-positive multinucleated cells was significantly lower in the culture with PMMA-TBB extract. There was no difference in osteoclast-related gene expression in response to different bone cement extracts. In conclusion, PMMA-TBB extract was less toxic to osteoblasts than PMMA-BPO extracts. Although extracts from the different cement types did not affect osteoclast function, PMMA-TBB extract seemed to reduce osteoclastogenesis, a possible further advantage of PMMA-TBB cement. These implied that the reduced radical generation during polymerization is not the only determinant for the improved biocompatibility of PMMA-TBB and that the post-polymerization chemical elution may also be important.

Desferrioxamine alleviates UHMWPE particle-induced osteoclastic osteolysis by inhibiting caspase-1-dependent pyroptosis in osteocytes

BACKGROUND

Cell death and inflammation are the two important triggers of wear particle-induced osteolysis. Particles, including cobalt-chromium-molybdenum and tricalcium phosphate, have been reported to induce pyroptosis in macrophages and osteocytes. Although macrophage pyroptosis facilitates osteoclastic bone resorption and osteolysis, whether osteocyte pyroptosis is involved in osteoclastic osteolysis still needs further investigation. Desferrioxamine (DFO), an FDA-approved medication and a powerful iron chelator, has been proven to reduce ultrahigh-molecular-weight polyethylene (UHMWPE) particle-induced osteolysis. However, whether DFO can ameliorate UHMWPE particle-induced osteolysis by decreasing pyroptosis in osteocytes is unknown.

RESULTS

A mouse calvarial osteolysis model and the mouse osteocyte cell line MLO-Y4 was used, and we found that pyroptosis in osteocytes was significantly induced by UHMWPE particles. Furthermore, our findings uncovered a role of caspase-1-dependent pyroptosis in osteocytes in facilitating osteoclastic osteolysis induced by UHMWPE particles. In addition, we found that DFO could alleviate UHMWPE particle-induced pyroptosis in osteocytes in vivo and in vitro.

CONCLUSIONS

We uncovered a role of caspase-1-dependent pyroptosis in osteocytes in facilitating osteoclastic osteolysis induced by UHMWPE particles. Furthermore, we found that DFO alleviated UHMWPE particle-induced osteoclastic osteolysis partly by inhibiting pyroptosis in osteocytes. Schematic of DFO reducing UHMWPE particle-induced osteolysis by inhibiting osteocytic pyroptosis. Wear particles, such as polymers, generated from prosthetic implant materials activate canonical inflammasomes and promote the cleavage and activation of caspase-1. This is followed by caspase-1-dependent IL-β maturation and GSDMD cleavage. The N-terminal fragment of GSDMD binds to phospholipids on the cell membrane and forms holes in the membrane, resulting in the release of mature IL-β and inflammatory intracellular contents. This further facilitates osteoclastic differentiation of BMMs, resulting in excessive bone resorption and ultimately leading to prosthetic osteolysis. DFO reduces UHMWPE particle-induced osteolysis by inhibiting osteocytic pyroptosis.

Pyroptosis in Periprosthetic Osteolysis

Periprosthetic osteolysis (PPO) along with aseptic loosening (AL) caused by wear particles after artificial joint replacement is the key factor in surgical failure and subsequent revision surgery, however, the precise molecular mechanism underlying PPO remains unclear. Aseptic inflammation triggered by metal particles, resulting in the imbalance between bone formation by osteoblasts and bone resorption by osteoclasts may be the decisive factor. Pyroptosis is a new pro-inflammatory pattern of regulated cell death (RCD), mainly mediated by gasdermins (GSDMs) family, among which GSDMD is the best characterized. Recent evidence indicates that activation of NLRP3 inflammasomes and pyroptosis play a pivotal role in the pathological process of PPO. Here, we review the pathological process of PPO, the molecular mechanism of pyroptosis and the interventions to inhibit the inflammation and pyroptosis of different cells during the PPO. Conclusively, this review provides theoretical support for the search for new strategies and new targets for the treatment of PPO by inhibiting pyroptosis and inflammation.

Assessment of the systemic immune response in patients with inflammatory complications of large joint implants

One of the most common reasons for the progressing of aseptic instability of implanted structures in patients with end-stage osteoarthrosis is a disorder of immunogenulatory processes of bone tissue remodeling along with chronic inflammatory response influenced by endoprosthesis wear components. This research features the specifics of systemic immune response in patients with inflammatory complications in late postoperative period after total replacements of large joints. The factor analysis enabled determining the most significant immunological mechanisms associated with the progressing of implant aseptic instability. Pathogenetically significant components involved in the formation of cellular and humoral immune responses in patients with signs of inflammatory activity in late postoperative period have been identified. Our findings can be used in designing diagnostic and prognostic criteria for systemic inflammatory response severity in preoperative monitoring of the condition of patients in need of large joint arthroplasties, and also in detecting the progress of implant aseptic instability.

The role of foreign body response in peri-implantitis: What is the evidence?

Historically, there has been broad consensus that osseointegration represents a homeostasis between a titanium dental implant and the surrounding bone, and that the crestal bone loss characteristic of peri-implantitis is a plaque-induced inflammatory process. However, this notion has been challenged over the past decade by proponents of a theory that considers osseointegration an inflammatory process characterized by a foreign body reaction and peri-implant bone loss as an exacerbation of this inflammatory response. A key difference in these two schools of thought is the perception of the relative importance of dental plaque in the pathogenesis of crestal bone loss around implants, with obvious implications for treatment. This review investigates the evidence for a persistent foreign body reaction at osseointegrated dental implants and its possible role in crestal bone loss characteristic of peri-implantitis. Further, the role of implant-related material release within the surrounding tissue, particularly titanium particles and corrosion by-products, in the establishment and progression in peri-implantitis is explored. While it is acknowledged that these issues require further investigation, the available evidence suggests that osseointegration is a state of homeostasis between the titanium implant and surrounding tissues, with little evidence that a persistent foreign body reaction is responsible for peri-implant bone loss after osseointegration is established. Further, there is a lack of evidence for a unidirectional causative role of corrosion by-products and titanium particles as possible non-plaque related factors in the etiology of peri-implantitis.

Biomimetic materials based on zwitterionic polymers toward human-friendly medical devices

This review summarizes recent research on the design of polymer material systems based on biomimetic concepts and reports on the medical devices that implement these systems. Biomolecules such as proteins, nucleic acids, and phospholipids, present in living organisms, play important roles in biological activities. These molecules are characterized by heterogenic nature with hydrophilicity and hydrophobicity, and a balance of positive and negative charges, which provide unique reaction fields, interfaces, and functionality. Incorporating these molecules into artificial systems is expected to advance material science considerably. This approach to material design is exceptionally practical for medical devices that are in contact with living organisms. Here, it is focused on zwitterionic polymers with intramolecularly balanced charges and introduce examples of their applications in medical devices. Their unique properties make these polymers potential surface modification materials to enhance the performance and safety of conventional medical devices. This review discusses these devices; moreover, new surface technologies have been summarized for developing human-friendly medical devices using zwitterionic polymers in the cardiovascular, cerebrovascular, orthopedic, and ophthalmology fields.

Involvement of NF-κB/NLRP3 axis in the progression of aseptic loosening of total joint arthroplasties: a review of molecular mechanisms

Particulate wear debris can trigger pro-inflammatory bone resorption and result in aseptic loosening. This complication remains major postoperative discomforts and complications for patients who underwent total joint arthroplasty. Recent studies have indicated that wear debris-induced aseptic loosening is associated with the overproduction of pro-inflammatory cytokines. The activation of osteoclasts as a result of inflammatory responses is associated with osteolysis. Moreover, stimulation of inflammatory signaling pathways such as the NF-κB/NLRP3 axis results in the production of pro-inflammatory cytokines. In this review, we first summarized the potential inflammatory mechanisms of wear particle-induced peri-implant osteolysis. Then, the therapeutic approaches, e.g., biological inhibitors, herbal products, and stem cells or their derivatives, with the ability to suppress the inflammatory responses, mainly NF-κB/NLRP3 signaling pathways, were discussed. Based on the results, activation of macrophages following inflammatory stimuli, overproduction of pro-inflammatory cytokines, and subsequent differentiation of osteoclasts in the presence of wear particles lead to bone resorption. The activation of NF-κB/NLRP3 signaling pathways within the macrophages stimulates the production of pro-inflammatory cytokines, e.g., IL-1β, IL-6, and TNF-α. According to in vitro and in vivo studies, novel therapeutics significantly promoted osteogenesis, suppressed osteoclastogenesis, and diminished particle-mediated bone resorption. Conclusively, these findings offer that suppressing pro-inflammatory cytokines by regulating both NF-κB and NLRP3 inflammasome represents a novel approach to attenuate wear-particle-related osteolytic diseases.

Osteocytic cells exposed to titanium particles increase sclerostin expression and inhibit osteoblastic cell differentiation mostly via direct cell-to-cell contact

The mechanism underlying induction of periprosthetic osteolysis by wear particles remains unclear. In this study, cultured MLO‐Y4 osteocytic cells were exposed to different concentrations of titanium (Ti) particles. The results showed that Ti particles increased expression of the osteocytic marker SOST/sclerostin in a dose‐dependent manner, accelerated apoptosis of MLO‐Y4 cells, increased the expression of IL‐6, TNF‐α and connexin 43. SOST silence alleviated the increase of MLO‐Y4 cells apoptosis, decreased the expression of IL‐6, TNF‐α and connexin 43 caused by Ti particles. The different co‐culture systems of MLO‐Y4 cells with MC3T3‐E1 osteoblastic cells were further used to observe the effects of osteocytic cells' changes induced by Ti particles on osteoblastic cells. MLO‐Y4 cells treated with Ti particles inhibited dramatically differentiation of MC3T3‐E1 cells mostly through direct cell‐to‐cell contact. SOST silence attenuated the inhibition effects of Ti‐induced MLO‐Y4 on MC3T3‐E1 osteoblastic differentiation, which ALP level and mineralization of MC3T3‐E1 cells increased and the expression of ALP, OCN and Runx2 increased compared to the Ti‐treated group. Taken together, Ti particles had negative effects on MLO‐Y4 cells and the impact of Ti particles on osteocytic cells was extensive, which may further inhibit osteoblastic differentiation mostly through intercellular contact directly. SOST/sclerostin plays an important role in the process of mutual cell interaction. These findings may help to understand the effect of osteocytes in wear particle‐induced osteolysis.

PAP Polypeptide Promotes Osteogenesis in Jaw Bone Defect Repair by Inhibiting Inflammatory Reactions

Jaw defects are common in oral and maxillofacial diseases and require surgical repair in extreme cases. Given the limitations in availability and efficacy of autologous bone grafts or allografts, great effort has been made in finding suitable, biocompatible, and effective artificial bone materials. Considering the key role of inflammation in bone resorption, we sought to identify a polypeptide with anti-inflammatory and bone-promoting effects. Rat bone marrow-derived mesenchymal cells (BMSCs) were treated with lipopolysaccharide (LPS) to induce an inflammatory environment, and 1,538 differentially abundant polypeptides were identified using mass spectrometry. Based on mass spectrometry signal intensity, multiple of difference, and structural stability, PAP was screened out as the polypeptide with the lowest abundance in the inflammatory condition. PAP showed no cytotoxicity to BMSCs with increasing concentrations. PAP (10 μM) also increased alkaline phosphatase activity and mRNA expression of Ocn, Bmp2, and Runx2 in a concentration-dependent manner, which confirmed that it can promote osteogenic induction of rat BMSCs. Moreover, PAP reduced LPS-induced expression of inflammatory cytokines (TNF-α, IL-1β, IL-6) and reactive oxygen species and inhibited polarization of RAW 264.7 macrophages to the inflammatory type. Finally, a skull defect mouse model was established, and mice were injected with LPS and/or PAP. Micro-CT, histological analysis, and immunohistochemical staining showed that PAP significantly reduced the number of LPS-induced bone resorption pits and maintained bone integrity. Overall, the polypeptide PAP screened using LPS stimulation of BMSCs is not cytotoxic and can inhibit the inflammatory reaction process to promote osteogenesis. This study thus provides a basis for development of PAP as a new osteogenic material in the repair of jaw defects.

IL-10 inhibits osteoclast differentiation and osteolysis through MEG3/IRF8 pathway

OBJECTIVE

Osteolysis caused by wear particles is the main reason for joint replacement failure. Inhibition of osteoclast differentiation relieves wear particle-induced osteolysis. Our study aimed to explore the effect of lncRNA maternally expressed gene 3 (MEG3) on osteoclast differentiation and wear particle-induced osteolysis, and to improve the potential mechanism of interleukin-10 (IL-10) inhibition on osteoclast differentiation.

METHODS

Polymethylmethacrylate (PMMA) -induced osteolysis mice model and receptor activator of nuclear factor-B ligand (RANKL) -induced osteoclast differentiation model were constructed. Tartrate-resistant acidic phosphatase (TRAP) staining, hematoxylin-eosin (HE) staining, immunohistochemical staining, bone resorption assay, dual-luciferase assay, RNA pull-down assay, RNA immunoprecipitation, and chromatin immunoprecipitation were executed.

RESULTS

MEG3 levels were increased and interferon regulatory factor 8 (IRF8) levels were decreased in PMMA-induced osteolysis mice. IL-10 inhibited RANKL-induced osteoclast differentiation, promoted MEG3 methylation, and inhibited MEG3 expression. Moreover, knockdown of MEG3 inhibited osteoclast differentiation and increased IRF8 levels. Meanwhile, MEG3 combined with signal transducer and activator of transcription 1 (STAT1), STAT1 combined with IRF8, and overexpression of MEG3 inhibited STAT1 binding to IRF8. Further studies have shown that knockdown of MEG3 inhibited osteoclast differentiation and alleviated osteolysis, but knockdown of IRF8 weakened these results.

CONCLUSION

MEG3 regulated the expression of IRF8 by binding to STAT1, thereby affecting osteoclast differentiation and wear particle-induced osteolysis. IL-10 might inhibit osteoclast differentiation by MEG3/IRF8.

Bisphosphonates in Total Joint Arthroplasty: A Review of Their Use and Complications

Background

Considerable interest has been expressed in the use of bisphosphonates to treat periprosthetic osteoporosis with the clinical goals of reducing periprosthetic fractures and prolonging implant survival.

Methods

A systematic review was performed with the goal of identifying both basic science and clinical studies related to the risks and benefits of bisphosphonate use in total joint arthroplasty.

Results

Studies have shown that bisphosphonates may increase early bony ingrowth, decrease the postoperative loss of bone mineral density, and increase the longevity of implants by reducing the need for revisions secondary to aseptic loosening. Continuing bisphosphonates for 1 year postoperatively seems to provide the greatest benefit, with only marginal benefit being shown by continuing therapy for up to 2 years. Current data present some concerns for an increased risk of periprosthetic fractures especially in younger patients, and prolonged therapy is not recommended due to the potential risk of atypical femur fractures. Patients should be counseled regarding the risk of side effects of bisphosphonates, including the risk of osteonecrosis of the jaw, which is a rare but serious side effect. They should also be counseled on the risk of atypical femur fractures and gastrointestinal intolerance.

Conclusions

Orthopedic surgeons could consider bisphosphonates for up to 1 year postoperatively regardless of the patient’s prior bone mineral density, after discussion regarding the risks and benefits with the patient.

What Are the Long-term Surgical Outcomes of Compressive Endoprosthetic Osseointegration of the Femur with a Minimum 10-year Follow-up Period?

BACKGROUND

Endoprosthetic reconstruction after oncologic resection of bone tumors requires stable fixation between the prosthesis and residual host bone. Compressive osseointegration has been developed as an alternative to traditional stemmed implants to address the challenges and complications of achieving this fixation. Sufficient time has now passed from the advent of compressive implants to allow for an assessment of the intermediate-term and long-term results of this form of fixation.

QUESTIONS/PURPOSES

At a minimum follow-up of 10 years after implantation of a compressive osseointegration device for oncologic reconstruction: (1) What is the risk of periprosthetic fracture, aseptic loosening, or implant breakage resulting in revision surgery for endoprosthesis removal? (2) What is the long-term cortical response at the host-endoprosthesis interface as visualized on plain radiographs?

METHODS

A single-center, retrospective study was performed between 2002 and 2010, in which 110 patients with primary bone sarcoma of the proximal or distal femur were considered for oncologic resection and reconstruction. Patients were considered for a compressive osseointegration endoprosthesis if they were 50 years of age or younger, had not previously received femoral radiation, had no metabolic disease impairing bone healing, were not diagnosed with metastatic disease, and had life expectancy greater than six months. Of the 110 patients, 25 were treated with a compressive osseointegration implant of the proximal or distal femur, and 85 patients were treated with conventional stemmed implants or amputation because of older age, advanced disease, metabolic comorbidities, inability to tolerate a nonweightbearing postoperative period, or in the case of rotationplasty, patient preference. All patients who received this device during the period of study were considered eligible for inclusion in this review. The median (range) age was 18 years (7 to 50), and 13 of 25 patients were men. Five patients died of disease before the minimum follow-up duration of 10 years; two underwent amputation due to local recurrence and three died with the implant in situ, leaving 20 patients for complete analysis. Median follow-up was 144 months, and all 20 surviving patients had a minimum follow-up of 10 years (121 to 230 months). The primary endpoint was reoperation and implant removal for periprosthetic fracture, aseptic loosening, or mechanical breakage of any component of the compressive device in the endoprosthesis. In final analysis, death was considered a competing event to revision surgery, and cumulative incidence was reported after competing-event analysis. A secondary aim was radiographic evaluation of the host-implant interface to assess the long-term cortical response to compressive osseointegration.

RESULTS

Spindle fracture or loosening was noted in three patients, and the remaining 17 patients maintained the compression device until the final follow-up. The risk of reoperation for aseptic loosening, periprosthetic fracture, or mechanical breakage of the implant using a competing risks estimator was 12% at 10 years (95% CI 0% to 26%). These complications occurred within 29 months of the index surgery; no patients had implant loosening or mechanical breakdown after this initial period. On radiographic assessment, 14 patients demonstrated cortical hypertrophy of the bone-implant interface, six patients had maintenance of the native cortical contour, and no patients had cortical atrophy or narrowing at the implant interface.Conclusion Long-term follow-up in patients with compressive osseointegrative endoprosthetic devices demonstrated no late revisions because of periprosthetic fracture, aseptic loosening, or implant breakage in this cohort with a minimum 10-year follow-up. There was no evidence of late-onset cortical atrophy or stress shielding at the host-implant interface. This study supports the long-term stability of the interface between host bone and the endoprosthesis in compressive osseointegration devices.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Backside polyethylene wear in reverse shoulder arthroplasty

BACKGROUND

Aseptic loosening from implant-associated osteolysis in reverse shoulder arthroplasty (RSA) may contribute to premature implant failure. Although articular side polyethylene (PE) damage has been well documented in the literature, no studies to date have investigated backside wear in RSA. The aims of this investigation were to (1) document and compare the damage between the backside and articular surface in explanted RSA components, (2) assess whether certain quadrants have a greater propensity for damage, and (3) report the most common mode(s) of backside PE damage.

METHODS

Twenty-one RSA humeral liners retrieved during revision procedures between 2005 and 2014 were included for analysis. The mean time between implantation and extraction was 16 months (10 days-88 months). Diagnoses at the time of revision included dislocation (10), infection (4), mechanical failure (3), loosening (2), and unknown (2). Liners were examined under light microscopy (×10-30 magnification) and damage on the articular and backside of the liner surface was graded using the modified Hood score. The location and damage modality were compared between the articular side and backside of the implant.

RESULTS

Damage was noted on the articular surfaces of all 21 liners and on the backside surface of 20 liners. The total damage in all the quadrants was higher on the articular surface than on the backside of the component, with a mean difference in total quadrant damage scores of 11.74 ± 3.53 (P < .001). There was no difference in damage among the quadrants on the backside (P = .44) or the articular surface (P = .08). The articular side exhibited greater scratching, abrasion, and surface deformation than the backside (P < .001).

CONCLUSIONS

This short-term retrieval study demonstrated that backside PE damage occurs on the humeral component of RSA implants. There was greater damage to the articular side of the liner but wear to the backside was present in almost all liners. The clinical importance of backside wear in RSA and its overall contribution to PE particulate disease and osteolysis needs further investigation.

SEM-EDX Analysis of Metal Particles Deposition from Surgical Burs after Implant Guided Surgery Procedures

The preparation of the implant site in guided surgery procedure takes place without irrigation, which could lead to increased friction of the drills with the formation and release of debris or metal particles. The presence of metal particles in the peri-implant tissue could represent a trigger for macrophage activity, bone resorption processes, and consequent implant loss. According to the guided surgical protocol, the study aimed to evaluate the presence of metal particles deposited during implant site preparation. Twenty-five adult porcine ribs from the same adult individual were chosen due to their trabecular bone structure, similar to facial bones. The samples were all 8 cm (length) × 3 cm (depth) × 2 cm (width) and were further subdivided to obtain 50 elements of 4 cm × 3 cm × 2 cm. Plexiglass was used to create structures such as surgical guides so that their function could be mimicked, and the guided implant site preparation sequence could be performed with them. The drill kit used in this study is a guided surgery drill kit characterized by high wear resistance, high yield strength, and good corrosion resistance. This same kit was used 50 times in this way to prepare 50 different implant sites and evaluated at different edges and number of preparation (T0-neutral edge, T1-1 full preparation, T2-10, T3-20, T4-30, T5-40, and T6-50) by SEM-EDX to assess the presence of any metal deposition. The presence of metal residues in the implant site increased according to the cycles of use of the drills. We have observed that in the first three groups, there is no presence of metals. This is evident in groups T3 and T4. Finally, the presence of metal residues becomes significant in the study’s last two groups of samples. The study highlighted how the lack of irrigation in the work site leads the deposition of metal particles and in addition to a reduction in the efficiency of the drills, resulting in less precise cutting, altering the shape of the prepared site, and, lastly, reducing the primary stability of the implants.

Additive Effect of Parathyroid Hormone and Zoledronate Acid on Prevention Particle Wears-Induced Implant Loosening by Promoting Periprosthetic Bone Architecture and Strength in an Ovariectomized Rat Model

Implant-generated particle wears are considered as the major cause for the induction of implant loosening, which is more susceptible to patients with osteoporosis. Monotherapy with parathyroid hormone (PTH) or zoledronate acid (ZOL) has been proven efficient for preventing early-stage periprosthetic osteolysis, while the combination therapy with PTH and ZOL has exerted beneficial effects on the treatment of posterior lumbar vertebral fusion and disuse osteopenia. However, PTH and ZOL still have not been licensed for the treatment of implant loosening to date clinically. In this study, we have explored the effect of single or combined administration with PTH and ZOL on implant loosening in a rat model of osteoporosis. After 12 weeks of ovariectomized surgery, a femoral particle-induced periprosthetic osteolysis model was established. Vehicle, PTH (5 days per week), ZOL (100 mg/kg per week), or combination therapy was utilized for another 6 weeks before sacrifice, followed by micro-CT, histology, mechanical testing, and bone turnover examination. PTH monotherapy or combined PTH with ZOL exerted a protective effect on maintaining implant stability by elevating periprosthetic bone mass and inhibiting pseudomembrane formation. Moreover, an additive effect was observed when combining PTH with ZOL, resulting in better fixation strength, higher periprosthetic bone mass, and less pseudomembrane than PTH monotherapy. Taken together, our results suggested that a combination therapy of PTH and ZOL might be a promising approach for the intervention of early-stage implant loosening in patients with osteoporosis.

Investigation on tribological behaviors of biodegradable pure Zn and Zn-X (Li, Cu, Ge) binary alloys

As a potential biodegradable implant material, zinc (Zn) alloys have attracted increasing attention due to their good biocompatibility and moderate degradation rate. Zn and its alloys are expected to become candidate materials for medical devices. The metals implanted in the human body will inevitably undergo friction in the human body before it is completely degraded. Friction and wear are essential factors which may cause medical devices' service failure. However, there are still few studies on the friction and wear properties of biodegradable Zn-based alloys in the human body, and most studies just focus on the mechanical properties, degradation properties and biocompatibility of the alloys. Thus, it is crucial to study the friction and wear properties of Zn and its alloys. In the present work, we investigated the tribological properties of biodegradable pure Zn and Zn-X (Li, Cu, Ge) alloys. Our study found that under simulated body fluid and dry friction conditions, the addition of alloying elements Li and Cu can improve the friction properties of Zn. Among the four metals, Zn-0.5Li alloy has the lowest friction coefficient and the best wear resistance. Hank's solution has lubricating and corrosive effects. That is to say, when the alloy is rubbed in Hank's solution, it can not only be protected by the lubrication of the solution, but also tribocorrosion will occur as well.

Physicochemical and Biological Characterization of Ti6Al4V Particles Obtained by Implantoplasty: An In Vitro Study. Part I

Implantoplasty is a mechanical decontamination technique that consists of polishing the supra-osseous component of the dental implant with peri-implantitis. This technique releases metal particles in the form of metal swarf and dust into the peri-implant environment. In the present in vitro study, the following physicochemical characterization tests were carried out: specific surface area, granulometry, contact angle, crystalline structure, morphology, and ion release. Besides, cytotoxicity was in turn evaluated by determining the fibroblastic and osteoblastic cell viability. As a result, the metal debris obtained by implantoplasty presented an equivalent diameter value of 159 µm (range 6–1850 µm) and a specific surface area of 0.3 m²/g on average. The particle had a plate-like shape of different sizes. The release of vanadium ions in Hank’s solution at 37 °C showed no signs of stabilization and was greater than that of titanium and aluminum ions, which means that the alloy suffers from a degradation. The particles exhibited cytotoxic effects upon human osteoblastic and fibroblastic cells in the whole extract. In conclusion, metal debris released by implantoplasty showed different sizes, surface structures and shapes. Vanadium ion levels were higher than that those of the other metal ions, and cell viability assays showed that these particles produce a significant loss of cytocompatibility on osteoblasts and fibroblasts, which means that the main cells of the peri-implant tissues might be injured.

Bisphosphonate-enoxacin inhibit osteoclast formation and function by abrogating RANKL-induced JNK signalling pathways during osteoporosis treatment

Osteoporosis is an age‐related disease characterized by low mineral density, compromised bone strength and increased risk of fragility fracture. Most agents for treating osteoporosis focus primarily on anti‐resorption by inhibiting osteoclast activity. Bisphosphonate (BP) is a potent anti‐resorptive agent that has been used clinically for decades and is proven to be effective. However, BP has a variety of side effects and is far from being an ideal anti‐osteoporosis agent. BP selectively binds to calcium crystals, which are subsequently taken up or released by osteoclasts. Based on the action of BP, we previously demonstrated the inhibitory effect of a novel bone‐targeting BP derivative, bisphosphonate‐enoxacin (BE). In the current study, we used bone marrow‐derived osteoclast cultures to further assess the inhibitory effect of BE on osteoclastogenesis and employed reverse transcription PCR and real‐time PCR to examine expression of osteoclast‐specific genes. Additionally, we used bone resorption and F‐actin immunofluorescence assays to evaluate the effect of BE on osteoclast function and investigated the potential mechanisms affecting osteoclast differentiation and function in vitro. Furthermore, an ovariectomized (OVX) rat model was established to evaluate the therapeutic effects of BE on preventing bone loss. Results showed that BE exerted potent inhibitory effects on osteoclast formation and bone resorption by specifically abrogating RANKL‐induced JNK signalling, and that it preserved OVX rat bone mass in vivo without any notable side effects. Collectively, these results indicated that the BP derivative BE may have significant potential as a treatment for osteoporosis and other osteolytic diseases.

miR-9-5p promotes wear-particle-induced osteoclastogenesis through activation of the SIRT1/NF-κB pathway

To explore the potential function of miR-9-5p in wear-particle-induced osteoclastogenesis, we examined the expression of SIRT1 and miR-9-5p in particle-induced osteolysis (PIO) mice calvariae and polyethylene (PE)-induced RAW 264.7 cells and found that SIRT1 expression was downregulated while miR-9-5p expression was upregulated in both models. We then verified that miR-9-5p targets SIRT1. miR-9-5p was found to promote PE-induced osteoclast formation from RAW 264.7 cells by tartrate-resistant acid phosphatase staining and detection of osteoclast markers, and miR-9-5p activation of the SIRT1/NF-kB signaling pathway was found in cells by detecting the expression of SIRT1/NF-kB pathway-related proteins and rescue assays. In conclusion, we found that miR-9-5p activated the SIRT1/NF-κB pathway to promote wear-particle-induced osteoclastogenesis. miR-9-5p may be a useful therapeutic target for PIO remission and treatment.

Enalapril inhibits inflammatory osteolysis induced by wear debris in a mouse model

Objective

Aseptic loosening, the most frequent complication after total joint replacement, is probably caused by an inflammatory response to the shedding of wear debris from the implant. The only effective treatment is surgical revision. Using a mouse model, we investigated whether enalapril inhibits wear debris-induced inflammatory osteolysis.

Methods

Titanium (Ti) alloy particles were introduced, and calvarial bone from syngeneic mice was implanted into air pouches established in BALB/c mice. Histological and molecular analyses were performed with inflammatory tissue samples obtained from mice treated with and without enalapril.

Results

Enalapril inhibited tissue inflammation and inflammatory osteolysis induced by Ti particles, reducing pouch membrane thickness and decreasing inflammatory cell infiltration. In addition, enalapril inhibited the expression of the inflammatory cytokines vascular endothelial growth factor and tumor necrosis factor-α.

Conclusions

Our study provides evidence that enalapril inhibits Ti particle-induced inflammatory osteolysis, and it may be a potentially useful treatment for aseptic loosening.

Variation and trends in reasons for knee replacement revision: a multi-registry study of revision burden

Background and purpose - Studies describing time-related change in reasons for knee replacement revision have been limited to single regions or institutions, commonly analyze only 1st revisions, and may not reflect true caseloads or findings from other areas. We used revision procedure data from 3 arthroplasty registries to determine trends and differences in knee replacement revision diagnoses.Patients and methods - We obtained aggregated data for 78,151 revision knee replacement procedures recorded by the Swedish Knee Arthroplasty Register (SKAR), the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), and the Kaiser Permanente Joint Replacement Registry (KPJRR) for the period 2003-2017. Equivalent diagnosis groups were created. We calculated the annual proportions of the most common reasons for revision.Results - Infection, loosening, and instability were among the 5 most common reasons for revision but magnitude and ranking varied between registries. Over time there were increases in proportions of revisions for infection and decreases in revisions for wear. There were inconsistent proportions and trends for the other reasons for revision. The incidence of revision for infection showed a uniform increase.Interpretation - Despite some differences in terminology, comparison of registry-recorded revision diagnoses is possible, but defining a single reason for revision is not always clear-cut. There were common increases in revision for infection and decreases in revision for wear, but variable changes in other categories. This may reflect regional practice differences and therefore generalizability of studies regarding reasons for revision is unwise.

Intra-operative Clodronate Rinsing Improves the Integration of the Femoral Stem in a Prospective, Double-blinded, Randomized, Placebo-controlled Clinical RSA-study

Background:

Periprosthetic bone loss after Total Hip Arthroplasty (THA), detected as an early migration of the prosthesis may predict later loosening of the implant.

Objective:

We hypothesized that intra-operative bisphosphonate rinsing would reduce bone resorption after THA. It might therefore be possible to achieve better early fixation of the implant.

Methods:

Nineteen patients suffering from arthrosis were recruited in a prospective, double-blinded, randomized, placebo-controlled clinical pilot trial. Patients were operated with an uncemented Bimetric stem using tantalum markers. The femoral proximal intramedullary canal was rinsed with 1mM clodronate in nine patients and with saline in 10 patients. These patients were followed for two years using radiostereometric analysis (RSA), dual energy x-ray absorptiometry (DXA) and the Harris Hip Score (HHS).

Results:

We did not found any significant differences between the study groups with regards to the primary output measures (maximum total point motion, MTPM). However, there was evidence that clodronate could affect periprosthetic bone quality; a beneficial effect in BMD in Gruen zone 3 during the two-year follow-up was observed, BMD decreased less in the clodronate group (p = 0.02). The maximal x-translation of the stem at 3-24 months was significantly two-fold, being higher in the placebo group (p = 0.02). The baseline BMD and the maximal total point motion (MTPM) at 3-24 months showed a positive correlation in the clodronate group and a negative correlation in the placebo group.

Conclusion:

In conclusion, further studies with larger patient groups and longer follow-up periods are needed to estimate the clinical importance of these findings and further to prove if an intraoperative clodronate rinsing prior to application of femoral stem during THA can prevent periprosthetic bone loss.

Clinical Trial Registration No.: NCT03803839

Endoprothetik am oberen Sprunggelenk

Arthrosis of the upper ankle is usually the long-term consequence of an ankle fracture. In the case of advanced osteoarthritis - after all conservative therapy options have been exhausted - the therapeutical options are reduced to the choice between arthrodesis and prosthesis, the technique and follow-up treatment of which this article presents. The mobility achieved after endoprosthetic treatment is usually less than the normal physiological level, but still functionally sufficient.

Metal Hypersensitivity in Joint Arthroplasty

Metal hypersensitivity in joint arthroplasty is a very controversial topic with limited evidence. With increasing numbers of joint replacements being done annually, a clear understanding of the pathogenesis, clinical picture, preimplant screening, postimplant workup, and treatment plan is crucial. This review article looked at all the available evidence regarding metal hypersensitivity and summarized the key findings. An algorithm was also proposed for preimplant screening, postimplant workup, and management.

Inhibitory effect of acetyl-11-keto-β-boswellic acid on titanium particle-induced bone loss by abrogating osteoclast formation and downregulating the ERK signaling pathway

Wear debris-induced osteoclast accumulation around implants plays a crucial role during the progression of periprosthetic osteolysis (PPO). We have confirmed that acetyl-11-keto-β-boswellic acid (AKBA) promotes bone formation and protects against particle-induced bone destruction in vivo. However, the effect of AKBA on titanium-induced bone resorption is unknown. In this study, we detected the inhibitory effect of AKBA on titanium-induced bone erosion in vivo and used RAW264.7 cells and bone marrow macrophages (BMMs) to investigate the effect and underlying mechanism of AKBA on the differentiation and resorptive function of osteoclasts. Our findings revealed that AKBA inhibited particle-induced bone loss and osteoclast formation in vivo. Furthermore, AKBA exerted inhibitory effects on RANKL-induced osteoclastogenesis, osteoclastic ring-dependent resorption and the expression of osteoclast marker genes via the ERK signaling pathway in vitro. Our data further established the protective effect of AKBA on titanium particle-induced bone erosion from a new perspective of bone erosion prevention, strongly confirming that AKBA is an appropriate agent for protection against PPO.

The effect of strontium ranelate on titanium particle-induced periprosthetic osteolysis regulated by WNT/β-catenin signaling in vivo and in vitro

Aseptic loosening following periprosthetic osteolysis is the primary complication that limits the lifetime of total joint arthroplasty (TJA). The wear particles trigger a chronic inflammation response in the periprosthetic tissue and turn over the bone balance to bone resorption. The present study aimed to investigate the possible effect and mechanism of strontium ranelate (SR), a clinically safe drug for osteoporosis, on particle-induced periprosthetic osteolysis. Thirty-six female C57BL/6j mice underwent tibial Ti-nail implantation to establish an animal model of aseptic loosening. After 12 weeks, micro-CT results showed that strontium ranelate could inhibit periprosthetic bone resorption. In vitro, Ti particles were used to stimulate RAW264.7 cell line to collect conditioned medium, and co-culture MC3T3-E1 cell line with conditioned medium to establish a cell model of aseptic loosening. The results of alkaline phosphatase (ALP) detection, immunofluorescence, and flow cytometry demonstrated that strontium ranelate could regulate the expression of OPG/RANKL, promote differentiation and mineralization, and inhibit apoptosis in osteoblasts. Moreover, we revealed that SR's exerted its therapeutic effect by down-regulating sclerostin, thereby activating the Wnt/β-catenin signal pathway. Therefore, this research suggests that strontium ranelate could be a potential drug for the prevention and treatment of particle-induced aseptic loosening post-TJA.

Wear of hip prostheses increases serum IGFBP-1 levels in patients with aseptic loosening

The biological mechanisms involved in aseptic loosening include inflammation-associated and bone resorption-associated processes. Coordinated cellular actions result in biochemical imbalances with devastating consequences for the joint. Given that this condition is not known for showing systemic signs, we investigated whether circulating levels of inflammation-related proteins are altered in patients with aseptic loosening. Our study included 37 patients who underwent revision surgery due to hip osteolysis and aseptic loosening and 31 patients who underwent primary total hip arthroplasty. Using antibody arrays, we evaluated the serum levels of 320 proteins in four patients from each group. The results showed differences in insulin-like growth factor-binding protein 1 (IGFBP-1) concentrations, which we then quantified using enzyme-linked immunosorbent assay tests in all study patients. The results confirmed that serum IGFBP-1 concentrations were higher in the revision surgery patients than in the hip arthroplasty patients. In vitro studies showed that exposure of human osteoblasts to titanium particles induced an IGFBP-1 release that further increased when exposure to particles was performed in media conditioned by human M1 macrophages. These findings suggest that elevated serum IGFBP-1 levels in patients with aseptic loosening can arise from increased local IGFBP-1 production in the inflammatory environment of the periprosthetic bed.

Influence of different anteversion alignments of a cementless hip stem on primary stability and strain distribution

BACKGROUND

Stem anteversion in total hip arthroplasty is well known to have a high impact on dislocation, but empirical data regarding the clinical and biomechanical influence is lacking. Therefore, we evaluated the impact of different anteversion alignments on the primary stability and strain distribution of a cementless stem.

METHODS

The cementless CLS Spotorno stem was implanted in 3 different groups (each group n = 6, total n = 21) with different anteversion alignments: reference anteversion (8°), +15° torsion in anteversion (+23°), -15° torsion in retroversion (-7°) using composite femurs (Sawbones). Primary stability was determined by 3-dimensional micromotions using a dynamic loading procedure simulating walking on level ground. Additionally, surface strains were registered before and after stem insertion in the 3 different groups, using one composite femur for each group (total n = 3).

FINDINGS

The micromotion measurements did not show a significant difference between the 3 evaluated alignments. Moreover, determination of the strain distribution did also not reveal an obvious difference.

INTERPRETATION

This biomechanical study simulating walking on level ground indicates that there is no considerable influence of stem ante-/retroversion variation (±15°) on the initial stability and strain distribution when evaluating the cementless CLS Spotorno in composite femora.

Melatonin suppresses Ti-particle-induced inflammatory osteolysis via activation of the Nrf2/Catalase signaling pathway

Aseptic loosening induced by osteolysis is recognized as a late complication of joint replacement. Osteoclasts stimulated by Titanium (Ti) nanoparticles play a critical role in periprosthetic osteolysis. Emerging evidence indicates that melatonin, a hormone primarily synthesized by the pineal gland, has been shown an inhibitory effect on osteoclast formation. However, it is unclear whether melatonin could suppress Ti-particle-induced osteoclastogenesis and what the underlying mechanisms were involved in. Herein, we aimed to investigate the effect of melatonin on osteoclast differentiation and osteolysis stimulated by Ti particles. Our results showed that the in vitro osteoclastogenesis of mouse bone marrow monocytes (BMMs) stimulated by Ti particles was suppressed by melatonin treatments in a dose-dependent manner. Further experiments revealed that melatonin up-regulated the expression of the nuclear factor erythroid 2-related factor 2 (Nrf2) and catalase (CAT) at both the mRNA and protein levels. The role of the Nrf2/CAT signaling pathway was confirmed by the fact that silencing the expression of NRF2 by small interfering RNA (siRNA) counteracted the anti-osteolysis effects of melatonin. Furthermore, in vivo intraperitoneal injection of melatonin successfully attenuated periprosthetic osteolysis induced by Ti particles in a murine calvarial model. Our findings demonstrate that melatonin is a promising therapeutic agent for treating periprosthetic osteolysis by inhibiting the Ti-particle-stimulated osteoclastogenesis via activation of the Nrf2/Catalase signaling pathway.

Blockade of XCL1/Lymphotactin Ameliorates Severity of Periprosthetic Osteolysis Triggered by Polyethylene-Particles

Periprosthetic osteolysis induced by orthopedic implant-wear particles continues to be the leading cause of arthroplasty failure in majority of patients. Release of the wear debris results in a chronic local inflammatory response typified by the recruitment of immune cells, including macrophages. The cellular mediators derived from activated macrophages favor the osteoclast-bone resorbing activity resulting in bone loss at the site of implant and loosening of the prosthetic components. Emerging evidence suggests that chemokines and their receptors are involved in the progression of periprosthetic osteolysis associated with aseptic implant loosening. In the current study, we investigated the potential role of chemokine C-motif-ligand-1 (XCL1) in the pathogenesis of inflammatory osteolysis induced by wear particles. Expressions of XCL1 and its receptor XCR1 were evident in synovial fluids and tissues surrounding hip-implants of patients undergoing revision total hip arthroplasty. Furthermore, murine calvarial osteolysis model induced by ultra-high molecular weight polyethylene (UHMWPE) particles was used to study the role of XCL1 in the development of inflammatory osteolysis. Mice received single injection of recombinant XCL1 onto the calvariae after implantation of particles exhibited significantly greater osteolytic lesions than the control mice. In contrast, blockade of XCL1 by neutralizing antibody significantly reduced bone erosion and the number of bone-resorbing mature osteoclasts induced by UHMWPE particles. In consistence with the results, transplantation of XCL1-soaked sponge onto calvariae caused osteolytic lesions coincident with excessive infiltration of inflammatory cells and osteoclasts. These results suggested that XCL1 might be involved in the development of periprosthetic osteolysis through promoting infiltration of inflammatory cells and bone resorbing-osteoclasts. Our further results demonstrated that supplementing recombinant XCL1 to cultured human monocytes stimulated with the receptor activator of nuclear factor kappa-B ligand (RANKL) promoted osteoclastogenesis and the osteoclast-bone resorbing activity. Moreover, recombinant XCL1 promoted the expression of inflammatory and osteoclastogenic factors, including IL-6, IL-8, and RANKL in human differentiated osteoblasts. Together, these results suggested the potential role of XCL1 in the pathogenesis of periprosthetic osteolysis and aseptic loosening. Our data broaden knowledge of the pathogenesis of aseptic prosthesis loosening and highlight a novel molecular target for therapeutic intervention.

Effect of Flavonoid Supplementation on Alveolar Bone Healing-A Randomized Pilot Trial

We investigated the effects of two common dietary supplements on bone healing in dental extraction sockets in humans. In this randomized pilot trial, male subjects took Grape Seed Extract [GSE] or Grapefruit Extract [GFE] starting two weeks prior to dental extraction and maintained this regimen for sixty days after surgery. Extraction sockets were filled with a collagen plug. After 24 h, a socket sample was collected and processed for quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) and an 84-gene wound healing assay. Sixty days after tooth extraction, a core of newly formed bone was obtained prior to dental implant placement and processed for histology. qRT-PCR revealed that GFE led to a significant decrease in platelet-derived growth factor and interleukin (IL)1-β compared to GSE, and a significant decrease in IL-6 and CXCL2 compared to control. GSE led to a significant increase in coagulation factor Von Willebrand and inflammatory marker IL1-β compared to GFE. WISP1 and CXCL5 were upregulated in both groups. Overall, GFE showed a downregulation of inflammation and GSE led to a decrease in collagen density and increased osteoclasts. This pilot trial highlights the need for further investigation on the mechanism of action of such supplements on bone healing and oral health.

Titanium particles damage osteocytes and inhibit osteoblast differentiation

Purposes

to study the effect of titanium particles on MLO-Y4 and the effects of osteocytes alterations on osteoblasts.

Methods

cultured MLO-Y4 osteocytes were exposed to different concentrations of titanium (Ti) particles, cell viability was measured using the Cell Counting Kit-8 (CCK-8) assay, apoptosis of MLO-Y4 cells was evaluated by flow cytometry, Real-time PCR quantification of mRNA expression of SOST, at the same time with Western Blot detection sclerosteosis protein expression levels.MC3T3-E1 cells culture with MLO-Y4 cells exposed to different concentrations of titanium (Ti) particles in vitro, in order to detection of osteoblast osteogenetic activity.

Results

Our results showed that Ti particles inhibited cell viability of MLO-Y4 osteocytes in a dose-dependent manner. Incubation with Ti particles caused apoptosis of MLO-Y4cells.Treatment with Ti particles significantly increased expression of the osteocytic marker SOST/sclerostin. Furthermore, treatment of MLO-Y4 cells with Ti particles produced a dose-dependent decrease in ALP activity and decreased mineralization of MC3T3-E1 cells through direct cell-cell contact.

Conclusions

Titanium particles damage osteocytes and inhibit osteoblast differentiation.