In 2020 almost 90% of femoral heads for total hip implants in Germany were made of ceramic. Nevertheless, the cellular interactions and abrasion mechanisms in vivo have not been fully understood until now. Metal transfer from the head-neck taper connection, occurring as smear or large-area deposit, negatively influences the surface quality of the articulating bearing. In order to prevent metal transfer, damage patterns of 40 Biolox delta ceramic retrievals with CoC and CoPE bearings were analysed. A classification of damage type and severity for each component (n=40) was done according to an established scoring system. To investigate the physical properties, the surface quality was measured using confocal microscopy, quantitative analysis of phase composition were performed by Raman spectroscopy and qualitative analysis of metal traces was done by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). The periprosthetic tissue was analysed for abrasion particles with SEM and EDX. Both bearing types show different damage patterns. Dotted/ drizzled metal smears were identified in 82 % of CoC (n=16) and 96 % of CoPE (n=24) bearings. Most traces on the ceramic heads were identified in the proximal area while they were observed predominantly in the distal area for the ceramic inlays. The identified marks are similar to those of metallic bearings. Metallic smears lead to an increase of up to 30 % in the monoclinic crystalline phase of the ceramic. The roughness increases by up to six times to Ra=48 nm. Ceramic and metallic wear particles from the articulating surfaces or head neck taper junctions were found in the periprosthetic tissue. Damage patterns on CoC hip implants seem to be similar to those of metallic implants. More detailed analysis of CoC implants are needed to understand the described damage patterns and provide advice for prevention

Musculoskeletal disorders is one of most important health problems human population is facing includes. Approximately 310 thousand of hip protheses have been used in 45 years and older patients in total according to the recent studies have been done. [1, 2]. Many factors, including poor osseointegration or relaxation of the implant due to stress, limit the life of the load-bearing implants [3]. To overcome these difficulties and to protect metal implants inside the body, the surfaces of the implants were coated with silver ion doped hydroxyapatite/bioglass. In this study, silver doped hydroxyapatite ceramic powder and 6P57 bioglass were synthesized. Two different coating suspensions, 100% bioglass and 70% Ag-HAp / 30% bioglass, were prepared in methyl alcohol with a solid content of 1% by weight. Two layers were coated on the external fixator nails by using electrospray method with the bioglass and Ag-Hap/Bioglass suspensions respectively. The coated implants were cut with an equal surface area and kept in human blood plasma for different time. The scanning electron microscopy (SEM, Zeiss Supra 50VP and Zeiss Evo 50EP) and stereo microscope (Zeiss Axiocam Stemi 2000-C) were used to characterize microstructure and thickness of coated surface. Energy dispersive X-ray Spectroscopy was used characterized of chemical composition of coating. Changing of pH value of plasma was measured by pH meter (Hanna HI83414). In addition, the ICP method was used to determine the elements contained in the plasma fluid after dissolution. As a result of this study, physical and chemical changes occurring on the coating surface in different time periods are presented in detail

Introduction and Objective. Calcium phosphates are among the most commonly used bone graft substitute materials. Compositions containing predominantly monetite (∼84.7%) with smaller additions of beta-tricalcium phosphate (β-TCP; ∼8.3%) and calcium pyrophosphate (Ca-PP; ∼6.8%) have previously been demonstrated to exhibit osteoinductive properties. Such a multi-component calcium phosphate bioceramic was fashioned in the form of hollowed-out, dome-shaped devices (15 mm diameter, 4 mm height), each reinforced with a 3D printed Ti6Al4V ELI frame. With the aim to induce bone formation beyond the skeletal envelope, these devices were investigated in vivo using a sheep (Ovis aries) occipital bone model. Materials and Methods. The bioceramic composition was prepared from a mixture of β-TCP/dicalcium pyrophosphate and monocalcium phosphate monohydrate powders mixed with glycerol. The Ti6Al4V ELI frame was positioned into a dome-shaped mould and bioceramic paste was poured over the frame and allowed to set, in sterile water, prior to removal from the mould. In adult female sheep (n=7), the devices were positioned directly over the bone and stabilised using self-drilling screws. After 52 weeks, the devices were retrieved, resin embedded, and used for X-ray micro-computed tomography (micro-CT), histology, backscattered electron scanning electron microscopy (BSE-SEM), energy dispersive X-ray spectroscopy (EDX), micro-Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR). Results. The bioceramic composition (Ca/P: ∼0.85 at. %) transforms to carbonated apatite (Ca/P: ∼1.2 at. %, Mg/Ca: ∼0.03 at. %), in vivo, largely at the expense of monetite and Ca-PP whereas β-TCP remains detectable. Discrete particles of Ca-PP are identified by correlative BSE-SEM and micro-Raman spectroscopy. Together with chemical transformation, physical degradation is evident within the bulk of the bioceramic. Beyond the confines of the skeletal envelope, de novo bone occupies ∼53–84% (∼73 ± 11%; mean ± standard deviation) of the hollowed-out space. Low porosity and the arrangement of remodelled bone into a concentric lamellar pattern is indicative of cortical-like structure. Such areas are typically surrounded by yet unremodelled, and microstructurally disordered, woven bone that stains intensely with blue cationic dyes, owing to relatively higher acid phosphate content. This pattern indicates a recurring sequence of woven bone formation followed by remodelling. Bone formation is also visible within the bioceramic. Recently remodelled and areas of ongoing remodelling are identified by relatively lower mineral density than the surrounding woven bone. Dendritic extensions of osteocytes appear to extend into the bioceramic surface. Both micro-Raman spectroscopy and FTIR reveal little, if any, detectable difference between the mineral and organic phases of the extracellular matrix, between de novo and native bone. Conclusions. The bioceramic composition undergoes physical degradation, but remains largely intact by 52 weeks in vivo, and only partially transforms to carbonated apatite. In addition to very high bone volume within the hollowed-out bioceramic device, the overall composition and microstructure of de novo bone are similar to native bone. Notably, the mineral phase of bone in response to, and in direct contact with the β-TCP, monetite, and Ca-PP, remains exclusively carbonated apatite

Total ankle replacement (TAR) has a mean survivorship of 77% at 10 years which is poor compared to other types of joint arthroplasty. Osteolysis and aseptic loosening are commonly cited TAR failure modes, the mechanisms of which are unknown. Retrieval analyses of TAR devices may reveal mechanisms of failure similar or dissimilar to other joint replacements. This study investigated whether TAR explants exhibit similar damage modes to those recognised in other total joint replacements. 22 Ankle Evolution System TARs (Transystème, Nimes, France) were implanted and retrieved by the same surgeon. Mean implantation time was 7.8 yrs (5.3 to 12.1 range). Pain and/or loosening were the indications for revision. Macro photography, an Alicona Infinite microscope and the Hood/Wasielewski scale were used to classify damage modes on the polyethylene insert. Scanning electron microscopy with energy dispersive X-ray spectroscopy was used to determine the composition of third body debris and to image the fixation surface of the tibial components. Mean damage score was 185.4 (± 40.0 SD). Damage modes common to total knee replacements were identified on both the superior and inferior insert surfaces, these included: burnishing, scratching, pitting and abrasion. Titanium particles, hydroxyapatite fragments and bone debris were embedded in the insert surfaces. Fixation surface delamination was identified by the ongrowth of tissue between the cobalt chromium substrate and titanium alloy coating. Damage modes indicative of high levels of wear and deformation were evident. Pitting caused by third body debris was abundant and suggested fixation surface wear and failure

Summary. Macroscopic grading, histologic grading, morphometry, mineral analysis, and mechanical testing were performed to better understand the changes that occur in the cartilage, calcified cartilage, and subchondral bone in early osteoarthritis. Introduction. The earliest changes in osteoarthritis (OA) remain poorly understood due to the difficulty in detecting OA before patients feel pain. We have published details of the mature bovine patella model showing the pre-OA state where no gross macroscopic changes are visible yet microstructural changes indicate very early degeneration. In this new study, we proceed to investigate this model further by more comprehensively quantifying the changes in articular cartilage (AC), zone of calcified cartilage (ZCC), and subchondral bone (SB) in pre and early OA. Methods. Patellae from mature cow were studied. Gross examination with India ink was used to classify macroscopic cartilage degeneration. Two groups were selected in this study: one with no visible surface degeneration (pre-OA) and the other with mild to moderate macroscopically visible surface degeneration (early OA). Histologic staining with Safranin O and Fast Green was analysed with two osteoarthritic scoring systems: Mankin and OOCHAS. Differential Interference Contrast (DIC) microscopy was used to quantify morphometric changes. Degree of mineralisation was analysed with energy dispersive X-ray spectroscopy (EDS) to quantify the calcium and phosphorus content of the mineralised tissues. Material properties of calcified cartilage and subchondral bone were tested macroscopically using 3 point bending. Results. In the early OA group, cartilage was fissured and showed matrix loss. In its hydrated state, average cartilage thickness was significantly greater (p<0.05) in the early OA group by 24% compared to pre-OA group. The early OA group showed an 88% increase in ZCC thickness. Early OA tissue was graded significantly higher in OOCHAS grading and structure scores, cellularity, and staining scores of Mankin grading but not in the tidemark integrity score. Pre-OA and early OA tissues showed no significant differences in ZCC or SB mineralisation although all samples showed an increase in the degree of mineralisation going from the upper to the deeper ZCC and SB. Macroscopic mechanical testing showed no significant differences in mechanical properties between pre-OA and early OA groups. However within groups, the ZCC was an order of magnitude less stiff than the SB. Micromechanical testing showed that deeper ZCC and SB were stiffer than their regions closer to the joint surface. Conclusions. Early osteoarthritic changes in the joint tissues produce macro-level cartilage degeneration as well as microstructural changes. The combination of mineralisation and mechanical data show that though calcified cartilage and subchondral bone have similar mineralisation profiles, their material properties are drastically different, suggesting that stiffness is not purely the result of the mineral phase

Summary. A promising approach to stimulate in vivo bone formation by using our newly developed magnesium-based bone substitutes, which can be an alternative to treat the patients with bone loss in addition to the anticatabolic drugs and growth factors. Introduction. Bone impairment arising from osteoporosis as well as other pathological diseases is a major health problem. Anti-catabolic drugs such as bisphosphonates and other biological agents such as bone morphogenetic proteins and insulin-like growth factor can theoretically apply to stimulate bone formation. However, the formation of more brittle bone and uncontrolled release rate are still a challenge nowadays. Hence, we propose to stimulate bone formation by using a newly developed magnesium-based bone substitute. Indeed, the presence of magnesium ions can stimulate bone growth and healing by enhancing osteoblastic activity. This study aims to investigate the mechanical, in vitro and in vivo properties of this novel bone substitute. Methods. The bone substitutes were prepared by incorporating 9% TMSPM-treated Mg granules (i.e. 45μm & 150μm) into biodegradable polymer, polycaprolactone (PCL). The TMSPM silane-coupling agent treatment was used to protect the Mg particles from rapid degradation. Compression test was performed to study the mechanical properties of the bone substitute by using the MTS machine. A 7-day stimulated body fluid (SBF) immersion test was conducted to test their bioactivity. The surface composition was checked by energy dispersive x-ray spectroscopy (EDX) after immersion. The cytocompatibility and osteogenic differentiation properties of the bone substitutes were studied by MTT, ALP assays and qRT-PCR with the use of MC3T3-E1 pre-osteoblasts. Finally, the in vivo response of the bone substitutes was evaluated by using rat model of 2 months. Micro-CT was used to monitor the volume change of bone formation. Pure PCL was used as the control. Results. At least 36% higher compressive modulus was found on the new bone substitutes as compared to pure PCL. Calcium and phosphate deposition were detected on the Mg bone substitutes but not on pure PCL after 7-day SBF immersion. Significantly higher cell viabilities and specific ALP activities were found on the new bone substitutes as compared to pure PCL. Additionally, significantly higher ALP, Type I collagen, osteopontin and Runx2 expressions were found on the Mg-based substitutes at different time points. Finally, more than 15% new bone was found on the Mg bone substitutes after 1 week of post-operation and 40% higher after 3 weeks. Discussion/Conclusion. The increased compressive moduli of the Mg-based bone substitutes suggested that the mechanical property of PCL could be enhanced by incorporating Mg granules and the values fall within the range of cancellous bone (50 – 800 MPa). Moreover, the detection of the calcium and phosphate on the bone substitutes showed that they might possess osteoinductivity. The in vitro study showed the enhanced cytocompatibility and osteogenic differentiation properties of the new bone substitutes, which was possibly due to the effect of Mg ions release. Our previous study showed that only a low level of Mg ions (i.e. 50ppm) is able to stimulate the growth and differentiation of osteoblasts. Hence, this suggested the importance of controlling the release of Mg ions. This also explained why more new bone formation was found on the new bone substitutes than pure PCL during animal implantation. Hence, all the data presented here suggested our new bone substitutes maybe a potential candidate to stimulate new bone formation

Objectives

The cytotoxicity induced by cobalt ions (Co²⁺) and cobalt nanoparticles (Co-NPs) which released following the insertion of a total hip prosthesis, has been reported. However, little is known about the underlying mechanisms. In this study, we investigate the toxic effect of Co²⁺ and Co-NPs on liver cells, and explain further the potential mechanisms.