Release of zirconia nanoparticles at the metal stem-bone cement interface in implant loosening of total hip replacements

Performance evolution of the Nano Boron nitride enhanced bone cement composites

Bone cement is a research hotspot and has been partially applied in the field of bone repair thanks to the good mechanical, physical and antibacterial properties. However, the easy wear and high temperature during curing characteristics would cause surrounding tissue necrosis, which seriously limits the wider application to some extent. In this work, the hexagonal boron nitride (h-BN) nano flakes were optimized to enhance the bone cement matrix (PMMA) via mechanical doping. The doping of h-BN into PMMA results in an improved mechanical (bending stress increased by 26%), thermal-conductivity (increased by 175% with the loading of 20 wt%), wear-resistance properties, in addition, the h-BN has no significant impact on cell activity. What's more, the co-modification of PMMA with h-BN and Vancomycin (Va) endows the bone cement composites with more persistent drug release characteristics. This comprehensive performance evolution evaluation provides a reference for the innovative application of modified bone cement.

Zirconium as a Promising Synovial Biomarker for Loose Cemented Knee Prosthesis

BACKGROUND

Aseptic loosening is the most common mode of failure after total knee arthroplasty. Despite this, the diagnosis often remains challenging and mainly relies on imaging modalities. Until today, no biomarker exists to aid in diagnosing loosening of the implants. As zirconium (Zr) is often found in bone cement, where it serves as radiopacifier, this study aimed to establish Zr as a synovial biomarker for loosened cemented knee prostheses.

METHODS

A total of 31 patients scheduled for revision of a cemented knee prostheses were included. In all patients, the initial used cement contained Zr. After arthrotomy, specimens of synovial fluid were taken and levels of Zr were measured by inductively coupled plasma mass spectrometry. Depending on the necessary amount of force for explantation, the implants were graded "loose" or "well-fixed". Preoperative radiographs were evaluated by 2 independent physicians.

RESULTS

The concentration of Zr in the synovial fluid differed significantly (P < .001) between the "loose" (mean 170.9 μg/L, range 0 to 1941 μg/L) and the "well-fixed" (mean 0.6 μg/L, range 0 to 6 μg/L) implants. The receiver operating characteristic analysis revealed 0.25 μg/l as an optimal cutoff value leading to a sensitivity of 0.84, a specificity of 0.92, a positive predictive value of 0.94, and a negative predictive value of 0.79. There was no significant difference in the diagnostic performance compared to radiographs (P = .66).

CONCLUSIONS

Zirconium proved to be a reliable novel synovial biomarker for diagnosing aseptic loosening of knee prothesis fixed with cement containing Zr. This biomarker should not be interpreted in isolation, but in combination with existing diagnostic tools.

Layered Double Hydroxide Modified Bone Cement Promoting Osseointegration via Multiple Osteogenic Signal Pathways

Poly(methyl methacrylate) (PMMA) bone cement has been widely used in orthopedic surgeries including total hip/knee replacement, vertebral compression fracture treatment, and bone defect filling. However, aseptic loosening of the interface between PMMA bone cement and bone often leads to failure. Hence, the development of modified PMMA that facilitates the growth of bone into the modified PMMA bone cement is key to reducing the incidence of aseptic loosening. In this study, MgAl-layered double hydroxide (LDH) microsheets modified PMMA (PMMA&LDH) bone cement with superior osseointegration performance has been synthesized. The maximum polymerization reaction temperature of PMMA&LDH decreased by 7.0 and 11.8 °C, respectively, compared with that of PMMA and PMMA&COL-I (mineralized collagen I modified PMMA). The mechanical performance of PMMA&LDH decreased slightly in comparison with PMMA, which is beneficial to alleviate stress-shielding osteolysis, and indirectly promote osseointegration. The superior osteogenic ability of PMMA&LDH has been demonstrated in vivo, which boosts bone growth by 2.17- and 18.34-fold increments compared to the PMMA&COL-I and PMMA groups at 2 months, postoperatively. Moreover, transcriptome sequencing revealed four key osteogenic pathways: p38 MAPK, ERK/MAPK, FGF, and TGF-β, which were further confirmed by IPA, qPCR, and Western blot assays. Hence, LDH-modified PMMA bone cement is a promising biomaterial to enhance bone growth with potential applications in relevant orthopedic surgeries.

Release characteristics of enoxaparin sodium-loaded polymethylmethacrylate bone cement

BACKGROUND

This study aimed to prepare the polymethylmethacrylate (PMMA) bone cement release system with different concentrations of enoxaparin sodium (ES) and to investigate the release characteristics of ES after loading into the PMMA bone cement.

METHODS

In the experimental group, 40 g Palacos®R PMMA bone cement was loaded with various amount of ES 4000, 8000, 12,000, 16,000, 20,000, and 24,000 AXaIU, respectively. The control group was not loaded with ES. Scanning electron microscopy (SEM) was used to observe the surface microstructure of the bone cement in the two groups. In the experiment group, the mold was extracted continuously with pH7.4 Tris-HCL buffer for 10 days. The extract solution was collected every day and the anti-FXa potency was measured. The experiment design and statistical analysis were conducted using a quantitative response parallel line method.

RESULTS

Under the SEM, it was observed that ES was filled in the pores of PMMA bone cement polymer structure and released from the pores after extraction. There was a burst effect of the release. The release amount of ES on the first day was 0.415, 0.858, 1.110, 1.564, 1.952, and 2.513, respectively, from the six groups with various ES loading amount of 4000, 8000, 12,000, 16,000, 20,000, and 24,000 AXaIU, all reaching the peak of release on the first day. The release decreased rapidly on the next day and entered the plateau phase on the fourth day.

CONCLUSION

The prepared ES-PMMA bone cement has high application potential in orthopedic surgery. ES-PMMA bone cement shows good drug release characteristics. The released enoxaparin sodium has a local anti-coagulant effect within 24 h after application, but it will not be released for a long time, which is complementary to postoperative anti-coagulation therapy.

Wear debris released by hip prosthesis analysed by microcomputed tomography

Total hip arthroplasty uses commercial devices that combine different types of biomaterials. Among them, metals, ceramics and metal oxides can be used either in the prosthesis itself or in the cement used to anchor them in the bone. Over time, all of these materials can wear out and release particles that accumulate in the periprosthetic tissues or can migrate away. We used histology blocks from 15 patients (5 titanium metallosis, 5 alumina prostheses, 5 with altered methacrylic cement) to perform a microCT study and compare it with conventional histology data. An EDS-SEM analysis was done to characterise the atomic nature of the materials involved. A morphometric analysis was also performed in 3D to count the particles and assess their density and size. The metallic particles appeared to be the largest and the ceramic particles the finest. However, microCT could not reveal the wear particles of radiolucent biomaterials such as polyethylene and the very fine zirconia particles from cement fragmentation. MicroCT analysis can reveal the extent of the accumulation of these debris in the periprosthetic tissues. LAYOUT DESCRIPTION: Hip prostheses progressively degrade in the body by releasing wear debris. They accumulate in the periprosthetic tissues. Microcomputed tomography was used to image three types of radio-opaque wear debris: metal, ceramic and zirconia used in the bone cements.

Local Cellular Responses to Metallic and Ceramic Nanoparticles from Orthopedic Joint Arthroplasty Implants

Over the last decades, joint arthroplasty has become a successful treatment for joint disease. Nowadays, with a growing demand and increasingly younger and active patients accepting these approaches, orthopedic surgeons are seeking implants with improved mechanical behavior and longer life span. However, aseptic loosening as a result of wear debris from implants is considered to be the main cause of long-term implant failure. Previous studies have neatly illustrated the role of micrometric wear particles in the pathological mechanisms underlying aseptic loosening. Recent osteoimmunologic insights into aseptic loosening highlight the important and heretofore underrepresented contribution of nanometric orthopedic wear particles. The present review updates the characteristics of metallic and ceramic nanoparticles generated after prosthesis implantation and summarizes the current understanding of their hazardous effects on peri-prosthetic cells.

Toxicity, biodistribution and oxidative damage caused by zirconia nanoparticles after intravenous injection

Background: As a promising nanomaterial for biomedical applications, zirconia nanoparticles (ZrO₂) have aroused concern recently, but the toxicity of ZrO₂ in vivo has received little attention.

Purpose: The aim of this study is to demonstrate the systematic single dose toxicity, biodistribution and oxidative damage of ZrO₂ in vivo after intravenous injection in mice.

Materials and methods: Ten ICR mice were used at the high dose of ZrO₂ including 600, 500, 400 and 300mg/kg. Maximum tolerated dose (MTD) of 150 nm ZrO₂ was determined as 500mg/kg. Hematology analysis and blood biochemical assay were determined for the evaluation of oxidative damage caused by ZrO₂. Biodistribution of ZrO₂ was investigated by ICP-OES and TEM.

Results: Mice treated with higher dose (500mg/kg) showed significant spread in white blood cell counts (p<0.05). Especially, the serum ALT levels of 500mg/kg groups increased significantly (p<0.05) compared with the control group. ZrO₂ particles would not induce any changes in appearance and micromorphology of liver at 100 and 350mg/kg. Spleen samples showed no significant changes in micromorphology of the lymphoid follicles and in the size of the red pulp after injection of ZrO₂ at all doses. The serum of ZrO₂-treated animals (350 and 500mg/kg) has reduced levels of SOD compared to the control group (p<0.05). ZrO₂ persists in membrane-enclosed vesicles called lysosomes in the liver and spleen macrophages without abnormal changes of ultrastructure.

Conclusion: These findings would contribute to the future development of ZrO₂-based drug delivery system and other biomedical applications.

Macrophage polarization following three-dimensional porous PEEK

Macrophages play an important role in foreign body reaction (FBR), and exhibit a detrimental or beneficial function in tissue repair while polarized into different phenotypes. The objective of this work is to evaluate the effect of three-dimensional (3D) porous polyetheretherketone (PEEK) on macrophage polarization through sulfonating PEEK and establishing a mouse air pouch model. The in vivo results show that the sulfonated PEEK induced higher levels of anti-inflammatory cytokine together with lower levels of pro-inflammatory cytokine. In addition, it was found that a relatively mild infiltration of inflammatory cells was caused and there were more M2 macrophages and less M1 ones when compared with PEEK. It indicates that 3D porous PEEK induces a shift to M2 macrophages and has large potential in regenerative medicine application.

Clinically advancing and promising polymer-based therapeutics

In this review article, we will examine the history of polymers and their evolution from provisional World War II materials to medical therapeutics. To provide a comprehensive look at the current state of polymer-based therapeutics, we will classify technologies according to targeted areas of interest, including central nervous system-based and intraocular-, gastrointestinal-, cardiovascular-, dermal-, reproductive-, skeletal-, and neoplastic-based systems. Within each of these areas, we will consider several examples of novel, clinically available polymer-based therapeutics; in addition, this review will also include a discussion of developing therapies, ranging from the in vivo to clinical trial stage, for each targeted area of treatment. Finally, we will emphasize areas of patient care in need of more effective, accessible, and targeted treatment approaches where polymer-based therapeutics may offer potential solutions.

Osteogenic activity and angiogenesis of a SrTiO3 nano-gridding structure on titanium surface

Dual effect of alveolate double-layered SrTiO₃ nano-gridding based on Ti substrate: osteogenic activity and angiogenesis.

An overview of chitin or chitosan/nano ceramic composite scaffolds for bone tissue engineering

Chitin and chitosan based nanocomposite scaffolds have been widely used for bone tissue engineering. These chitin and chitosan based scaffolds were reinforced with nanocomponents viz Hydroxyapatite (HAp), Bioglass ceramic (BGC), Silicon dioxide (SiO₂), Titanium dioxide (TiO₂) and Zirconium oxide (ZrO₂) to develop nanocomposite scaffolds. Plenty of works have been reported on the applications and characteristics of the nanoceramic composites however, compiling the work done in this field and presenting it in a single article is a thrust area. This review is written with an aim to fill this gap and focus on the preparations and applications of chitin or chitosan/nHAp, chitin or chitosan/nBGC, chitin or chitosan/nSiO₂, chitin or chitosan/nTiO₂ and chitin or chitosan/nZrO₂ in the field of bone tissue engineering in detail. Many reports so far exemplify the importance of ceramics in bone regeneration. The effect of nanoceramics over native ceramics in developing composites, its role in osteogenesis etc. are the gist of this review.