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

Reports of improved functional outcome of Metal on Metal Hip Resurfacing Arthroplasty (mHRA) to Total Hip Replacement needs to be balanced with concerns of metal ion release. By removing cobalt-chrome, cHRA reduces these risks. To the author's knowledge, there is no data available on functional outcomes of cHRA, therefore the aim of the study was to compare the function between cHRA patients and mHRA patients. 24 patients received a unilateral cHRA (H1, Embody) and was compared to 24 age and gender matched patients with a unilateral mHRA (BHR, Smith and Nephew). All patients completed the Oxford Hip Score (OHS)[T2] and underwent gait analysis on an instrumented treadmill before and at a mean of 74wks (+/− 10) for mHRA and 53wks (+/− 2) for cHRA post op. Walking trials started at 4km/h and increased in 0.5km/h increments until a top walking speed (TWS) was achieved. Vertical ground reaction forces (GRF) were recorded along with the symmetry index (SI). Spatiotemporal measures of gait were also recorded. Vertical GRF were captured for the entire normalised stance phase using statistical parametric mapping (SPM; CI = 95%). The gain in OHS was similar: H1 (25-46), BHR(27-47). TWS increased by 19% with H1 (6.02 – 8.0km/hr), and 20% with BHR (6.02 – 7.37km/hr). SPM of the entire gait cycle illustrated the restoration of symmetry in both groups with no difference in GRF across the stance phase between groups at 5km/hr pre-op and post-op. At faster speeds (6.5km/hr), H1 patients had a mid-support GRF slightly closer to normal compared to BHR. Both groups increased step length similar from pre to post op (H1:0.76 – 0.85cm, BHR:0.77-0.86cm). In this study, subjective and objective functional outcome measures suggest that short term functional outcomes of ceramic resurfacing is not inferior to metal resurfacing

Background. With promising antibiofilm properties, rifampicin is considered as a cornerstone in the complementary treatment of bone and joint infections. But, achieving an adequate concentration of rifampicin long-term in bone tissue is a challenge. Long-term systemic administration also comes with concomitant side effects. Thus, local delivery of rifampicin in a carrier to ensure the high local concentration of antibiotic in surgical site after intervention due to infection could be a valuable alternative. However, an ideal platform for local delivery of rifampicin is still lacking. A calcium sulphate/hydroxyapatite (CaS/HA) (Cerament, Bonesupport AB, Sweden) biomaterial was used as a local delivery platform. Here we aimed 1) to evaluate the injectability of CaS/HA hand-mixed with rifampicin at various concentrations up to maximum one daily dose used systemically in clinical practice 2) to test a clinically used and commercially available mixing device containing the biphasic ceramic with rifampicin. Materials & Methods. Three different concentrations (100 mg, 300 mg and 600 mg) of rifampicin powder (Rifampicin Ebb, Sanofi S.P.A, Italy) diluted in 5 mL of mixing solution (C-TRU, Bonesupport AB, Sweden) were used. Rifampicin solution was mixed to the CaS/HA powder and the injectability of the CaS/HA plus rifampicin composite was evaluated by extruding 250 µL of paste manually through a graduated 1 mL syringe connected to an 18G needle (Ø=1.2 mm, L=4 cm). Mixing was done with a spatula for 30 s at 22°C ±1°C. Total weight of the paste before and after extrusion were measured. To normalize the amount of composite that remained in the needle and syringe tip after injection, the mean of the paste extruded from the syringe at 3 min was calculated for the tested concentrations (normalized value). Injectability (%) was calculated by dividing the weight of the paste extruded from the syringe with normalized value. Each test was repeated for three times at various time points (3, 5, 7 and 9 min). Additionally, 300 mg rifampicin was chosen to mix with the CaS/HA in a commercially available mixing system, which is used clinically. Results. All three combinations of CaS/HA plus rifampicin (100 mg, 300 mg & 600 mg) could be completely extruded from 1 mL syringes at 3 min. At 5 min, 100 mg & 300 mg could still be injected, whereas 600 mg was uninjectable or solidified. At 7 min, rifampicin 100 mg & 300 mg showed 34% and 11% of injectability respectively. At 9 min, no injectability was observed. The material was completely set within 15 minutes with all concentrations. With commercial mixing system, at the recommended injection time of 4 min, 78% of the CaS/HA plus rifampicin (300 mg) composite could be injected. Conclusions. The injectability was reduced with the increasing concentration of rifampicin. CaS/HA plus rifampicin (100 mg and/or 300 mg) could be used by hand mixing and transferred to a syringe or by using an available mixing system containing the ceramic. For higher concentrations of rifampicin, the rheological properties of the ceramics have to be modified for injectability

Background. Innovative developments for total knee arthroplasty enhanced anatomical design and fixation in order to decrease particle-induced aseptic implant loosening. As hypersensitivity reactions to metallic implant materials have been recognized to possibly cause premature implant failure, ceramic materials might constitute a proper alternative solution. The aim of this prospective short-term study was the initial comparison of a completely metal-free ceramic with a geometrically identical metallic arthroplasty over a one-year follow-up period. Methods. Eighty patients requiring primary total knee arthroplasty were enrolled within this open-label prospective comparative study. Patients were randomly divided among two groups to either undergo implantation of a completely metal-free system using a composite matrix material containing aluminum oxide (Al2O3) and zirconium oxide (ZrO2) (n=40), or an anatomically identical metallic knee system made of a cobalt-chromium alloy (Co28Cr6Mo) (n=40) produced by the same manufacturer. Clinical assessment was performed preoperatively, and during follow-up at three and twelve months using the Knee Society Score, Oxford Knee Score and EQ-5D-VAS. For radiological evaluation, standard preoperative and postoperative standardized radiographs were taken at mentioned follow-up visits. Results. Demographical data were not significantly different among our two study groups, and no patient has been lost to follow-up. The postoperative clinical scores improved significantly at three and twelve month follow-ups, but did not differ statistically among groups. The radiologically evaluated mean postoperative mechanical and anatomical axes showed proper alignment within both groups at all times. Notably, no revision surgery had to be performed, and no complications were recorded whatsoever. Conclusion. To our knowledge, this is the first study comparing a total ceramic metal-free knee system with a geometrically identical metallic TKR. Within the short-term follow-up of minimally one year, no significant differences could be demonstrated clinically or radiologically, therefore making this ceramic knee system a suitable option for patients with a known hypersensitivity to metal. Mid-term and long-term studies will be required to demonstrate the overall efficiency of this TKR to potentially expand its medical indication

Wear particles produced by alumina ceramic-on-ceramic (CoC) bearings cause a minimal immunological response with low cytotoxicity and inflammatory potential. 1, 2. However, more comprehensive immunological studies are yet to be completed for the composite CoC (zirconia-toughened, platelet reinforced alumina) hip replacements due to difficulties in isolating the very low volume of clinically relevant wear debris generated by such materials in vitro. The aim of this study was to compare the cytotoxic effects of clinically relevant cobalt chromium (CoCr) nano-particles with commercial composite ceramic particles. Composite ceramic particles (commercial BIOLOX® delta powder) were obtained from CeramTec, Germany and clinically relevant CoCr wear particles were generated using a six station pin-on-plate wear simulator. L929 fibroblast cells were cultured with 50µm. 3. of CoCr wear debris or composite ceramic particles at low to high volumes ranging from 500µm. 3. –0.5µm. 3. per cell and the cyctotoxic effects of the particles were assessed over a period of 6 days using the ATP-Lite™ cell viability assay. The composite ceramic particles were bimodal in size (0.1–2µm & 30–100nm) and showed mild cytotoxic effects when compared with equivalent particle volumes (50µm. 3. ) of clinically relevant CoCr nano-particles (10–120nm). The CoCr nano-particles had significant cytotoxic effects from day 1, whereas the composite ceramic particles only showed cytotoxic effects at particle concentrations of 50 and 500µm. 3. after 6 days. The increased cytotoxicity of the clinically relevant CoCr nano-particles may have been attributed to the release of Co and Cr ions. This study demonstrated the potential cytotoxic effects of model ceramic particles at very high volume concentrations, but it is unlikely that such high particle volumes will be experienced routinely in vivo in such low wearing bearing materials. Future work will investigate the longer-term effects on genotoxicity and oxidative stress of low volumes of clinically-relevant generated BIOLOX® delta ceramic wear particles

Long-term survival and favourable outcome of implant use are determined by bone-implant osseointegration and absence of infection near the implants. As with most diseases, prevention is the preferred approach. Silver ion doped calcium phosphate based ceramic coating (Silveron®) for implant coating has been shown previously to be a potent antimicrobial agent as indicated by in vitro testing. The present study reports on clinical experience using silver ion doped calcium phosphate based ceramic coated external fixator pins as surgical treatment in the management of chronic osteomyelitis and open fractures. Ten patients had external fixators: six for open fractures of ankle, three for chronic osteomyelitis of the femur, one for tibia pseudoarthrosis. The electrospray method was used for coating the external fixator pins with silver ion doped calcium phosphate-based ceramics. A radiofrequency energy source was used to sinter the coated pins. Microbiological, roentgenographic, toxic and biochemical analyzes of patients were carried out. Wound debridement, and subsequent wound care resulted in control of the infection in three chronic osteomyelitis and in healing of seven fractures after follow-up ranging from three to six months. In total 67 pins were used in 10 patients but only one pin was positive microbiologically in one patient. Collectively, these data clearly illustrate that the toxic effects of silver were not observed at the doses used. Silver ion doped calcium phosphate based ceramic coating (Silveron®) can be used to prevent infection associated with the implant

Different 3D printing techniques for orthopaedic ceramic implants fabrication were compared. Stereolithography of calcium-phosphate slurries makes possible to achieve pre-determined pore size (50 mkm and more) and porosity of 70–80%. For the first time ceramic implants based on double calcium alkali metal phosphates (rhenanites) with given architecture serving good osteoconductivity as well as high resorptivity and strength (up to 10 MPa) were obtained. Development of biomaterials based on calcium phosphates for orthopaedics is an important area of modern materials science. Chemical, physical and mechanical compatibility of this materials is a primary goal for this field. An ideal implant should gradually dissolve and be replaced by the new bone tissue in the patience body. Bone is a multilevel organic/inorganic composite and the main inorganic compound is hydroxyapatite (HA, Ca. 10. (PO. 4. ). 6. (OH). 2. ). Due to this, biomaterials based on HA are widely used, along with biomaterials based on tricalcium phosphate (TCP, Ca. 3. (PO. 4. ). 2. ); however, low solubility of HA (lowest soluble phosphate) as well as TCP does not meet all of the requirements that biomaterials should have. In this work decreasing of the crystal lattice energy approach was used as a strategy of improving the solubility. Modifying the chemical composition by replacing Ca. 2+. cation in the TCP structure by a singly charged alkali metal cation leads to structural changes from TCP to CaMPO. 4. (M=Na, K) – rhenanite. This work focuses on using double calcium alkali metal phosphates Ca. (3 – x). М. 2x. (PO. 4. ). 2. (x = 0–1, М = Na, K) as bioresorbable osteoconductive ceramic implant. Additive manufacturing techniques are the most competitive technology which has been applied in the medical field for the direct or indirect construction of scaffolds and hard or soft tissues. Different techniques were used to prepare ceramics with given structure based on double calcium alkali metals phosphates to improve its osteoconductive properties. High resolution stereolithography (SLA) of ceramic photocurable resins has a great potential in fabrication of high quality complex shaped ceramics. For the first time ceramic implants based on double calcium alkali metal phosphates (rhenanites) with pre-determined pore size (50 mkm and more) and porosity of 70–80% were obtained. Given architecture of scaffold is serving a good osteoconductivity as well as a high resorptivity and strength (up to 10 MPa). High resolution SLA can be easily used for fabrication of a small size implants (3mm in diameter/height or less) for in vivo experiments, and it can be freely used to fit any shade in osteoconductive properties of ceramic materials designed for bone grafting. Russian Science Foundation supported this study under Grant No. 14-19-00752. The authors acknowledge partial support from Lomonosov Moscow State University Program of Development

Orthopaedic and trauma implant related infection remains one of the major complications that negatively impact clinical outcome and significantly increase healthcare expenditure. Hydroxyapatite has been used for many years to increase implant osseointegration. Silver has been introduced into hydroxyapatite as an antimicrobial coating for orthopedic implants. This surface coatings can both increase tissue compatibility and prevent implant-related infections. We examined infection markers and blood silver values, liver and kidney function tests of 30 patients with of three groups of orthopedic implants, external fixators, intramedullary nails and hip replacements, coated with Ag + ion doped CaP based ceramic powder to determine safety and effectiveness of this dual-function coating. During 1 year follow-up, the pin sites were observed at the external fixator group, and wound areas for the proximal femoral nail and hip arthroplasty group at regular intervals. In addition, liver and kidney function tests, infection markers and blood silver values were checked in patients. In the external fixator group, only 4 out of 91 pin sites (%4.39) were infected. The wound areas healed without any problem in patients with proximal femoral nails and hip arthroplasty. There was no side effect suggesting silver toxicity such as systemic toxic side effect or argyria in any patient and blood silver level did not increase. Compared to similar patient groups in the literature, much lower infection rates were obtained (p = 0.001), and implant osseointegration was good. In patients with chronic infection, the implants were applied acutely after removing the primary implant and with simple debridement. Unlike other silver coating methods, silver was trapped in hydroxyapatite crystals in the ionic form, which is released from the coating during the process of osseointegration, thus, the silver was released into the systemic circulation gradually that showed antibacterial activity locally. We conclude that the use of orthopedic implants with a silver ion added calcium phosphate-based special coating is a safe method to prevent the implant-related infection. This work was supported by TUBİTAK Project Number 315S101

Aluminia ceramic on ceramic (COC) bearing surfaces have been used for 35 years in total hip arthroplasty (THA). Studies report 85% survival at a minimum follow-up of 18.5 years. Nonetheless, an audible noise is a finding associated with COC bearings with incidence rates of 2–10%. This study aims to determine the prevalence of noise and evaluate its effect on patients. All patients who had a COC THA from August 2003 to December 2010 were contacted and asked to complete a standardised questionnaire. This asked about the presence and characteristics of a noise and if associated with activities, pain and whether this phenomenon should be mentioned preoperatively. Four consultant surgeons performed 282 consecutive primary COC THAs in 258 patients. (Male=122, Female=136 mean age 68.5; age range 28–88). In all cases, the same brand of ceramic acetabular component and stems were implanted. 11.0% had a noise, of which 5.5% had a squeak. Pain was experienced in 38.7% of patients in hips that made a noise. There was no trauma and one dislocation in this group. In this study, 85% of noises occur during weight-bearing although no patients have reduced daily activities as a result of the noises. Of all the patients, 55.0% stated they would have preferred to have known about a noisy hip possibility before consenting but none would have refused consent. Squeaking has not been a problem here despite the prevalence being higher than most in the literature. The authors recommend that squeaking should be discussed preoperatively. A checklist for Orthopaedic Trainees is being drafted to enable trainees to counsel patients appropriately, allowing patients a better opportunity to give informed consent

Bone grafting utilises tissue harvesting from second anatomic location of same patient (autograft) or from a human donor (allograft) to treat bone defects. Limited availability of bone grafts, donor site morbidity and risk of disease transmission led to an alternative strategy for bone grafting as synthetic materials that can promote bone regeneration. Engineered bone grafts are biocompatible and possess sufficient mechanical strength to support fractured bone. Polymer scaffolds lack mechanical stability whereas ceramic scaffolds are stiffer resulting in loosening of implants. Combining polymer and ceramic to form scaffolds can enhance the physical and mechanical properties and can be used for bone tissue engineering. We hypothesised that the nucleation of hydroxyapatite in carboxymethyl cellulose (CMC) matrix would improve scaffold properties physically and mechanically; thus, demonstrating CMC based biomimetic process to synthesise novel CMC/ HA scaffolds with suitable physical, mechanical and biological properties for bone tissue engineering. CMC/ HA scaffolds were synthesized by in situmethod at room temperature (RT) and 60°C and are labelled as CHRT and CH60 respectively, keeping the molar ratio of Ca/P as constant ∼1.6. The nucleation of hydroxyapatite (HA) from calcium chloride (CaCl. 2. ) and sodium dihydrogen phosphate (NaH. 2. PO. 4. ) was initiated inside carboxymethyl cellulose (CMC). CaCl. 2. solution was introduced gently in aqueous solution of CMC, thereafter; NaH. 2. PO. 4. solution was added dropwise and the mixture was stirred vigorously, kept overnight for aging at RT to obtain milky white slurry. The slurry was washed with distilled water to neutralize, cast into moulds and dried in hot air oven for 72 h to obtain scaffolds. Scanning electron microscopy (SEM) was performed to determine the surface topography of the scaffolds. Mechanical properties were tested with Universal Testing Machine (UTM) and cytotoxicity was performed by MTT assay using fibroblast cells (NIH 3T3). SEM images shows that HA aggregates like beads and knitted orderly over CMC backbone. There is an increase in HA agglomerates and decrease in bead size with increase in synthesis temperature from RT to 60°C. Scaffolds synthesized at 60°C show enhanced mechanical properties. Compressive strength of CHRT and CH60 are 0.68 MPa and 0.9 MPa respectively and compressive moduli of CHRT and CH60 are 33 MPa and 69 MPa respectively. MTT assay confirmed proliferation of fibroblast cells, hence; proved the non-toxic nature of the scaffolds. MTT assay reveals the cell viability (cell exoskeleton) on the scaffolds after 24 h incubation. In this study, CMC/ HA scaffolds were synthesised by in situmethod at RT and 60°C. Enhanced mechanical properties and cytocompatibility reveal the potentiality of the scaffolds for bone tissue engineering purposes

Background. The CoCrMo large bearings had shown a high failure rate, because of metal ion and particle release. Alumina matrix composite (AMC) ball heads have shown to mitigate such phenomena. The aim of this study was to investigate the leaching properties of AMC clinically as well as experimentally. Methods. Two patient groups were compared: a control group (n=15) without any implant (Controls) and 15 Patients with unilateral treatment with Biolox delta ceramic-on-ceramic (CoC). Whole-blood samples of Controls and Patients (after 3 and 12 months from treatment with CoC) were measured by means of trace element analysis using a HR-ICPMS. The leaching behaviour of BIOLOX delta was also analysed in-vitro: five Biolox delta heads and five CoCrMo heads were immersed in serum for seven days at 37°C. Aluminium, cobalt, chromium and strontium were detected based on HR-ICPMS. Results. In Patients, most elements remained below the limit of detection (LoD), except for aluminium and strontium. The aluminium values of Controls were below the LoD (27.2μg/L). The values of Patients after three months show a median of 34.2μg/L and after 12 months 37.1μg/L (p=0,510). Strontium ranged from 39.7μg/L of Controls and 79.6μg/L and 70.7μg/L of Patients, after three and twelve months, respectively. This difference was not statistically significant (p=0,322). The leaching experiments showed high amounts of cobalt (177.3μg/L) and chromium (4.2μg/L) released by CoCrMo. Ceramic heads didn't show any significant release. Conclusions. The current study revealed that there was no significant increase of any element in patients with CoC bearings. Metal heads released high values of cobalt in leaching test. As this release occurred even without any joint articulation, as shown in the experiments, surface corrosion seems to be a relevant mechanism in the ion release of metal bearings. A limitation of the study is that Controls differed from Patients within the clinical trial. Level of evidence. III

Background. The doses of local rhBMP-2 in commercially available materials are high with known drawbacks such as inflammation and premature bone resorption. The latter can be prevented by adding bisphosphonates like zoledronic acid (ZA) but systemic ZA has side effects and patient adherence to treatment is low. In a recent study, we have shown that local co-delivery of rhBMP-2 and ZA via a calcium sulphate/hydroxyapatite (CS-HA) biomaterial can be used to regenerate both cortical and trabecular bone in a rat model of metaphyseal bone defect. Even low doses of local ZA in the biomaterial showed promising results and increased bone formation within the defect compared to the controls. A step before clinical translation of the local treatment regimen is to evaluate the in-vivo release kinetics of these additives and thus in this study, we aimed to investigate the in-vivo pharmacokinetics of rhBMP-2 and ZA from the CS-HA biomaterial in a rat abdominal muscle pouch model over a period of 4-weeks. Methods. In-vivo release kinetics of 125I labeled rhBMP-2 and 14C labeled ZA was performed using an abdominal muscle pouch model in rats (n=6). Both rhBMP-2 and ZA were labeled commercially with a radiochemical purity of >95%. The detection of 125I -rhBMP-2 release was performed by implanting pellets of the CS-HA biomaterial containing 125I -rhBMP-2 and ZA and the same animals followed over a period of 4-weeks (day 1, 3, 7, 14, 21& 28) using SPECT imaging. Similarly, the 14C-ZA was detected by implanting CS-HA pellets containing rhBMP-2 and 14C-ZA. Release was detected via scintillation counting and at each time point (Day 1, 7, 14& 28) 6-animals were sacrificed. Results. BMP Release. The CS-HA biomaterial retained 95±11% after 3-days, 88±12% after a week, 66±9% after 2 weeks, 51±5% after 3 weeks and 43±7% of 125I labeled rhBMP-2 after 4-weeks in-vivo (SPECT-CT). ZA Release. The CS-HA biomaterial retained 89±14% after a week, 84±8% after 2 weeks, 83±9% after 3 weeks and 77±3% of 14C labeled ZA after 4 weeks of in-vivo implantation. Discussion. Improved carriers and better knowledge of the release might improve the effect of bone active drugs in orthopedics. Our previous study shows that an off-the-shelf ceramic biomaterial combined with ZA alone or with both rhBMP-2 and ZA can be used to regenerate bone with potential for clinical translational. This study demonstrates long-term co-delivery of both rhBMP-2 and ZA in-vivo via the biomaterial. Constant availability of rhBMP-2 over a long period of time can give osteoinductive properties to the material while presence of local ZA prevents premature bone loss. The pharmacokinetic release pattern differs from what we have reported in vitro with less BMP and more ZA being released in vivo during the first 4 weeks. We speculate that rapid protein passivation of the ceramic material slows the release of BMP and partly preventing the ZA binding to apatite

Background. Staphylococcus aureus is a human pathogen involved in implant-related infections. In these diseases, biofilm production is the key pathogenic event, and it increases antibiotic resistance of the organism. Because this phenomenon, local delivery of antibiotics could allows reaching high concentrations in the infected tissue without the secondary effects linked to systemic administration. Here we report the use of a ceramic biomaterial (SBA-15) as a carrier of antibiotics in order to deliver them directly in the infected tissue. Material and methods. SBA-15 discs were loaded with vancomycin, rifampin and a combination of both according to the protocol described by Molina-Manso et al. Loaded discs were introduced in a 0.5 McFarland suspension of S. aureus 15981 and incubated during 6 and 24 hours in order to develop a biofilm. After incubation, samples were sonicated during 5 minutes and 1:10 serial dilutions were performed in order to count viable bacteria. All experiments were performed in triplicate. Results. A statistically significant decrease in the number of viable bacteria was detected for all antibiotics at 6 hours, and also for vancomycin and the combination. Rifampin showed an increase in the number of viable bacteria at 24 hours. No differences were detected between vancomycin and the combination of antibiotics. Conclusion. SBA-15 can carry antibiotics that have effect on bacterial biofilm. The use of rifampin alone showed a loss of the effect after 24 hours of incubation, probably due to the selection of resistant mutants that nullify the effect of the antibiotic. No differences have been detected between vancomycin alone and its combination with rifampin in this experiment

Although the response of macrophages to polyethylene debris has been widely studied, it has never been compared with the cellular response to ceramic debris. Our aim was to investigate the cytotoxicity of ceramic particles (Al. 2. O. 3. and ZrO. 2. ) and to analyse their ability to stimulate the release of inflammatory mediators compared with that of high-density polyethylene particles (HDP). We analysed the effects of particle size, concentration and composition using an in vitro model. The J774 mouse macrophage cell line was exposed to commercial particles in the phagocytosable range (up to 4.5 μm). Al. 2. O. 3. was compared with ZrO. 2. at 0.6 μm and with HDP at 4.5 μm. Cytotoxicity tests were performed using flow cytometry and macrophage cytokine release was measured by ELISA. Cell mortality increased with the size and concentration of Al. 2. O. 3. particles. When comparing Al. 2. O. 3. and ZrO. 2. at 0.6 μm, we did not detect any significant difference at the concentrations analysed (up to 2500 particles per macrophage), and mortality remained very low (less than 10%). Release of TNF-α also increased with the size and concentration of Al. 2. O. 3. particles, reaching 195% of control (165 pg/ml v 84 pg/ml) at 2.4 μm and 350 particles per cell (p < 0.05). Release of TNF-α was higher with HDP than with Al. 2. O. 3. particles at 4.5 μm. However, we did not detect any significant difference in the release of TNF-α between Al. 2. O. 3. and ZrO. 2. at 0.6 μm (p > 0.05). We saw no evidence of release of interleukin-1α or interleukin-1ß after exposure to ceramic or HDP particles

Summary Statement. Fretting and corrosion has been identified as a clinical problem in modular metal-on-metal THA, but remains poorly understood in modern THA devices with polyethylene bearings. This study investigates taper damage and if this damage is associated with polyethylene wear. Introduction. Degradation of modular head-neck tapers was raised as a concern in the 1990s (Gilbert 1993). The incidence of fretting and corrosion among modern, metal-on-polyethylene and ceramic-on-polyethylene THA systems with 36+ mm femoral heads remains poorly understood. Additionally, it is unknown whether metal debris from modular tapers could increase wear rates of highly crosslinked PE (HXLPE) liners. The purpose of this study was to characterise the severity of fretting and corrosion at head-neck modular interfaces in retrieved conventional and HXLPE THA systems and its effect on penetration rates. Patients & Methods. 386 CoCr alloy heads from 5 manufacturers were analyzed along with 166 stems (38 with ceramic femoral heads). Metal and ceramic components were cleaned and examined at the head taper and stem taper by two investigators. Scores ranging from 1 (mild) to 4 (severe) were assigned in accordance with the semi-quantitative method adapted from a previously published technique. Linear penetration of liners was measured using a calibrated digital micrometer (accuracy: 0.001 mm). Devices implanted less than 1 year were excluded from this analysis because in the short-term, creep dominates penetration of the head into the liner. Results. The majority of the components were revised for instability, infection, and loosening. Mild to severe taper damage (score ≥2) was found in 77% of head tapers and 52% of stem tapers. The extent of damage was correlated to implantation time at the head taper (p=0.0004) and at the stem taper (p=0.0004). Damage scores were statistically elevated on CoCr heads than the matched stems (mean score difference=0.5; p<0.0001) and the two metrics were positively correlated with each other (ρ=0.41). No difference was observed between stem taper damage and head material (CoCr, ceramic) (p=0.56), nor was a correlation found between taper damage and head size (p=0.85). The penetration rate across different formulations of HXLPE was not found to be significantly different (p=0.07), and therefore grouped together for further analysis. Within this cohort, penetration rate was not found to be associated with head size (p=0.08) though a negative correlation with implantation time was noted (ρ=−0.35). When analyzed along with taper damage scores, a correlation was not observed between head taper damage scores and HXLPE penetration rates (p=0.51). Discussion. The results of this study do not support the hypothesis that 36+ mm ceramic or CoCr femoral heads articulating on HXLPE liners are associated with increased risk of corrosion among HXLPE liners when compared with smaller diameter heads. A limitation of this study is the semi-quantitative scoring technique, heterogeneity of the retrieval collection and short implantation time of the larger diameter heads. Because corrosion may increase over time in vivo, longer-term follow-up, coupled with quantitative taper wear measurement, will better assess the natural progression of taper degradation in modern THA bearings

We have developed a new drug delivery system using porous apatite-wollastonite glass ceramic (A-W GC) to treat osteomyelitis. A-W GC (porosity, 70% and 20% to 30%), or porous hydroxyapatite (HA) blocks (porosity 35% to 48%) used as controls, were soaked in mixtures of two antibiotics, isepamicin sulphate (ISP) and cefmetazole (CMZ) under high vacuum. We evaluated the release concentrations of the antibiotics from the blocks. The bactericidal concentration of ISP from A-W GC was maintained for more than 42 days, but that from HA decreased to below the detection limit after 28 days. The concentrations of CMZ from both materials were lower than those of ISP. An in vivo study using rabbit femora showed that an osseous concentration of ISP was maintained at eight weeks after implantation. Osteoconduction of the A-W GC block was good. Four patients with infected hip arthroplasties and one with osteomyelitis of the tibia have been treated with the new delivery system with excellent results

There is a lack of carriers for the local delivery of rifampicin (RIF), one of the cornerstone second defence antibiotic for Staphylococcus aureus deep bone infections (DBIs). RIF is also associated with systemic side effects, and known for causing rapid development of antibiotic resistance when given as monotherapy. We evaluated a clinically usedbi-phasic calcium sulphate/hydroxyapatite (CaS/HA) biomaterial as a carrier for dual delivery of RIF with vancomycin (VAN) or gentamicin (GEN). It was hypothesized that this combined approach could provide improved biofilm eradication and prevent the development of RIF resistance.

Methods: 1) Biofilm eradication: Using a modified crystal violet staining biofilm quantification method, the antibiotics released at different time points (Day 1, 3, 7, 14, 21, 28 and 35) from the hemispherical pellets of CaS/HA(500 mg)-VAN (24.57 mg) / GEN (10.35 mg) composites with or without RIF (8.11 mg) were tested for their ability to disrupt the preformed 48-h old biofilms of S. aureus ATCC 25923, and S. aureus clinical strain P-3 in 96-well microtitre plate. For each tested group of antibiotic fractions, five separate wells were used (n=5). 2) Testing for resistance development: Similar to the method mentioned above the 48-h biofilm embeded bacteria exposed to antibiotic fractions from different time points continuously for 7 days. The biofilms remained were then tested for RIF resistant strains of bacteria.

Overall, there was clear antibiofilm biofilm activity observed with CaS/HA-VAN/GEN+RIF combinations compared with CaS/HA-VAN/GEN alone. The S. aureus strains developed resistance to RIF when biofilms were subjected to CaS/HA-RIF alone but not with combinations of CaS/HA-VAN/GEN+RIF

Enhanced antibiofilm effects without development of RIF resistance indicates that biphasic CaS/HA loaded with VAN or GEN could be used as a carrier for RIF for additional local delivery in clinically demanding DBIs.

Acknowledgement: We deeply acknowledge the Royal Fysiographic Society of Lund, Landshövding Per Westlings Minnesfond and the Stina and Gunnar Wiberg fond for financial support.

We report the findings from independent prospective clinical and laboratory-based joint-simulator studies of the performance of ceramic femoral heads of 22.225 mm diameter in cross-linked polyethylene (XLP) acetabular cups. We found remarkable qualitative and quantitative agreement between the clinical and simulator results for the wear characteristics with time, and confirmed that ceramic femoral heads penetrate the XLP cups at only about half the rate of otherwise comparable metal heads. In the clinical study, 19 hips in 17 patients were followed for an average of 77 months. In the hip-joint simulator a similar prosthesis was tested for 7.3 million cycles. Both clinical and simulator results showed relatively high rates of penetration over the first 18 months or 1.5 million cycles, followed by a very much lower wear thereafter. Once an initial bedding-in of 0.2 mm to 0.4 mm had taken place the subsequent rates of penetration were very small. The initial clinical wear during bedding-in averaged 0.29 mm/year; subsequent progression was an order of magnitude lower at about 0.022 mm/year, lower than the 0.07 mm/year in metal-to-UHMWP Charnley LFAs. Our results show the excellent tribological features of alumina-ceramic-to-XLP implants, and also confirm the value of well-designed joint simulators for the evaluation of total joint replacements

Objectives

Our study aimed to examine not only the incidence but also the impact of noise from two types of total hip replacement articulations: ceramic-on-ceramic and ceramic-on-polyethylene.

Bone has a remarkable capacity to heal. However, in some instances the amount of bone which is needed to heal exceeds its healing capacity. Due to reported issues with current treatments there is continued research into alternative approaches with a view to producing an off the shelf alternative to the gold standard autologous bone transplants. The current investigated the use of a chitosan/hydroxyapatite scaffold, which was used to covalently bone morphogenetic protein and vascular endothelial growth factor using a UV crosslinking process. Results indicate that the incorporation of hydroxyapatite increased the mechanical properties of the scaffold compared to chitosan alone. Furthermore, crosslinking was confirmed using swelling studies and FTIR analysis. Elisa indicated that physiological doses of BMP were released after 10 days while in vitro testing did not indicate a cytotoxic response to the scaffold. In vivo testing in a rat femoral defect model indicated the efficacy of the treatment with scaffolds containing BMP and VEGF in combination resulting in more bone in the defect compared to the scaffold alone 8 weeks post-surgery.