Aim. Prosthetic joint infections pose a major clinical challenge. Developing novel material surface technologies for orthopedic implants that prevent bacterial adhesion and biofilm formation is essential. Antimicrobial coatings applicable to articulating implant surfaces are limited, due to the articulation mechanics inducing wear, coating degradation, and toxic particle release. Noble metals are known for their antimicrobial activity and high mechanical strength and could be a viable coating alternative for orthopaedic implants [1]. In this study, the potential of thin platinum-based metal alloy coatings was developed, characterized, and tested on cytotoxicity and antibacterial properties. Method. Three platinum-based metal alloy coatings were sputter-coated on medical-grade polished titanium discs. The coatings were characterized using optical topography and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS). Ion release was measured using inductively coupled plasma optical emission spectrometry (ICP-OES). Cytotoxicity was tested according to ISO10993-5 using mouse fibroblasts (cell lines L929 and 3T3). Antibacterial surface activity, bacterial adhesion, bacterial proliferation, and biofilm formation were tested with gram-positive Staphylococcus aureus ATCC 25923 and gram-negative Escherichia coli ATCC 25922. Colony forming unit (CFU) counts, live-dead fluorescence staining, and SEM-EDS images were used to assess antibacterial activity. Results. Three different platinum-based metal alloys consisting of platinum-iridium, platinum-copper, and platinum-zirconium. The coatings were found 80 nm thick, smooth (roughness average < 60 nm), and non-toxic. The platinum-copper coating showed a CFU reduction larger than one logarithm in adherent bacteria compared to uncoated titanium. The other coatings showed a smaller reduction. This data was confirmed by SEM and live-dead fluorescence images, and accordingly, ICP-OES measurements showed low levels of metal ion release from the coatings. Conclusions. The platinum-copper coating showed low anti-adhesion properties, even with extremely low metal ions released. These platinum-based metal alloy coatings cannot be classified as antimicrobial yet. Further optimization of the coating composition to induce a higher ion release based on the galvanic principle is required and copper looks most promising as the antimicrobial compound of choice. Acknowledgments. This publication is supported by the DARTBAC project (with project number NWA.1292.19.354) of the research program NWA-ORC which is (partly) financed by the Dutch Research Council (NWO); and the AMBITION project (with project number NSP20–1-302), co-funded by the PPP Allowance made available by Health-Holland, Top Sector Life Sciences & Health to ReumaNederland

Aim. A novel anti-infective biopolymer implant coating was developed to prevent bacterial biofilm formation and allow on-demand burst release of anti-infective silver (Ag) into the surrounding of the implant at any time after surgery via focused high-energy extracorporeal shock waves (fhESW). Method. A semi-crystalline Poly-L-lactic acid (PLLA) was loaded with homogeneously dissolved silver (Ag) applied onto Ti6Al4V discs. A fibroblast WST-1 assay was performed to ensure adequate biocompatibility of the Ag concentration at 6%. The prevention of early biofilm formation was investigated in a biofilm model with Staphylococcus epidermidis RP62A after incubation for 24 hours via quantitative bacteriology. In addition, the effect of released Ag after fhESW (Storz DUOLITH SD1: 4000 impulses, 1,24 mJ/mm. 2. , 3Hz, 162J) was assessed via optical density of bacterial cultures (Escherichia coli TG1, Staphylococcus epidermidis RP62A, Staphylococcus aureus 6850) and compared to an established electroplated silver coating. The amount of released Ag after the application of different intensities of fhESW was measured and compared to a control group without fhESW via graphite furnace atomic absorption spectrometry (GF-AAS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Results. The coating with 6% Ag reduced Staphylococcus epidermidis biofilm formation by 99.7% (mean±SD: 2.1×10^5 ± 3,9×10^5 CFU/µL) compared to uncoated controls (6.8×10^7 ± 4.9×10^7 CFU/µL); (p=0.0001). After applying fhESW the commercially available electroplated silver coating did not prevent the growth of all tested bacterial strains. Bacterial growth is delayed with 4% Ag and completely inhibited with 6% Ag in the novel coating, except for a small increase of S. aureus after 17 hours. SEM and EDS confirmed a local disruption of the coating after fhESW. Conclusions. This novel anti-infective implant coating has the potential to prevent bacterial biofilm formation. The on-demand burst release of silver via fhESW could be an adjunctive in the treatment of implant related infection and is of particular interest in the concept of single stage revision surgery

Introduction. The use of irrigation solution during surgical procedures is a common and effective practice in reduction of bioburden and the risk of subsequent infection. The optimal irrigation solution to accomplish this feat remains unknown. Many surgeons commonly add topical antibiotics to irrigation solutions assuming this has topical effect and eliminates bacteria. The latter reasoning has never been proven. In fact a few prior studies suggest addition of antibiotics to irrigation solution confers no added benefit. Furthermore, this practice adds to cost, has the potential for anaphylactic reactions, and may also contribute to the emergence of antimicrobial resistance. We therefore sought to compare the antimicrobial efficacy and cytotoxicity of irrigation solution containing polymyxin-bacitracin versus other commonly used irrigation solutions. Methods. Using two in vitro breakpoint assays of Staphylococcus aureus (ATCC#25923) and Escherichia coli (ATCC#25922), we examined the efficacy of a panel of irrigation solutions containing topical antibiotics (500,000U/L Polymyxin-Bacitracin 50,000U/L; Vancomycin 1g/L; Gentamicin 80mg/L), as well as commonly used irrigation solutions (Normal saline 0.9%; Povidone-iodine 0.3%; Chlorhexidine 0.05%; Castile soap 0.45%; and Sodium hypochlorite 0.125%) following 1 minute and 3 minutes of exposure. Surviving bacteria were counted in triplicate experiments. Failure to eradicate all bacteria was considered to be “not effective” for that respective solution and exposure time. Cytotoxicity analysis in human fibroblast, osteoblast, and chrondrocyte cells exposed to each of the respective irrigation solutions was performed by visualization of cell structure, lactate dehydrogenase (LDH) activity and evaluation of vital cells. Toxicity was quantified by determination of LDH release (ELISA % absorbance; with higher percentage considered a surrogate for cytotoxicity). Descriptive statistics were used to present means and standard deviation of triplicate experimental runs. Results. Polymyxin-Bacitracin, Saline and Castile soap irrigation at both exposure times were not effective at eradicating S aureus or E coli (Figure 1). In contrast, Povidone-iodine, Chlorhexidine, and Sodium hypochlorite irrigation were effective at eradicating both S aureus and E coli. Vancomycin irrigation was effective at S aureus eradication but not against E coli, whereas Gentamicin irrigation showed partial efficacy against E coli eradication but none against S aureus. The greatest cytotoxicity was seen with Chlorhexidine (49.4% ± 1.9). This was followed by Castile soap (33.2% ±3.9), Vancomycin (9.01% ±5.1), Polymyxin-Bacitracin (8.45% ±1.5), and Gentamicin irrigation (4.72% ±2.3) (Figure 2 and Figure 3 microscopy images). Povidone-iodine and Sodium hypochlorite showed least cytotoxicity (0.05% ±0.08 and 0.11%±0.19, respectively). Similar trends were seen at both exposure times and across fibroblasts, osteoblasts and chondrocytes. Discussion. This in vitro study suggests that addition of polymyxin-bacitracin to saline irrigation solution is a futile exercise. Taken within the context of its associated expense, risk of hypersensitivity and impact upon antimicrobial resistance, our findings bring its widespread clinical usage into question. Povidone-iodine may be a more effective option, with a more favorable cytotoxicity profile than the other commonly used irrigation solutions. Clinical outcomes should be studied to determine the most effective agent, concentration, and exposure time for intraoperative irrigation

Introduction. Particle-induced oxidative stress in cells is a unifying factor that determines toxicity and carcinogenicity potential in biomaterials. A previous study by Bladen et al. showed the production of significant levels of reactive oxygen species (ROS) following the stimulation of phagocytes by UHMWPE and CoCr wear debris [1]. Latest generation bearing materials such as silicon nitride also need to be tested for potential generation of ROS in phagocytic cells. This study aimed to investigate the production of reactive oxygen species in L929 fibroblasts stimulated with clinically relevant doses of nanoscale and micron-sized silicon nitride (Si. 3. N. 4. ) particles, silica nanoparticles, and CoCr wear debris. Silica nanoparticles were included as a comparison material for situations where the Si. 3. N. 4. particle's surface are oxidised to silicon dioxide [2]. Materials and Methods. Si. 3. N. 4. particles (<50 nm and <1 µm, Sigma), silica nanopowder (<100 nm, Sigma) and clinically relevant CoCr wear particles were heat-treated at 180°C for 4 h to remove endotoxin. Particles were then re-suspended in sterile water by sonication. L929 murine fibroblasts were cultured with low doses (0.5 µm. 3. /cell) and high doses (50 µm. 3. /cell) of Si. 3. N. 4. particles, and high doses (50 µm. 3. /cell) of silica nanoparticles and CoCr wear debris. Cells were incubated for three and six days at 37°C with 5% (v/v) CO. 2. tert-Butyl hydroperoxide (TBHP) was used as a positive control for the production of ROS in the cells. Intracellular ROS was measured using Image-IT LIVE kit (Invitrogen). This assay is based on carboxy-2',7'-dichlorodihydro-fluorescein diacetate (carboxy-H2DCFDA), which forms a non-fluorescent derivative by intracellular esterases and then reacts with intracellular ROS to form green fluoroscence producing derivative carboxy- dichlorodihydro-fluorescein. Images were captured using a confocal microscope and analysed using ImageJ for corrected total cell fluorescence (CTCF). The results were expressed as mean ± 95% confidence limits and the data was analysed using one-way ANOVA and Tukey-Kramer post-hoc tests. Results and Discussion. Si. 3. N. 4. nanoparticles significantly reduced the ROS levels in L929 fibroblasts at low doses (0.5 μm. 3. /cell) and high doses (50 μm. 3. /cell) over a period of six days; whereas no significant change in the levels of ROS was observed in cells treated with micron-sized Si. 3. N. 4. particles [Figure 1]. Only a few cells treated with high doses of CoCr wear particles (50 μm. 3. /cell) survived for up to six days and produced significantly higher levels of ROS [Figure 1, 2]. Interestingly, cells challenged with high doses (50 μm. 3. /cell) of Si. 3. N. 4. and silica nanoparticles produced statistically similar levels of ROS in cells [Figure 1]. This might be due to the potential surface oxidation of Si. 3. N. 4. nanoparticles, which makes their surface chemistry and biological identity similar to silica nanoparticles. Conclusion. Unlike existing implant materials such as UHMWPE and CoCr, silicon nitride has demonstrated the capacity to reduce or maintain normal levels of ROS in macrophages depending on the particle size and dose. Acknowledgements. The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. GA-310477 LifeLongJoints

Aberrant infrapatellar fat metabolism is a notable feature provoking inflammation and fibrosis in the progression of osteoarthritis (OA). Irisin, a secretory subunit of fibronectin type III domain containing 5 (FNDC5) regulate adipose morphogenesis, energy expenditure, skeletal muscle, and bone metabolism. This study aims to characterize the biological roles of Irisin signaling in an infrapatellar fat formation and OA development. Injured articular specimens were harvested from 19 patients with end-stage knee OA and 11 patients with the femoral neck fracture. Knee joints in mice that overexpressed Irisin were subjected to intra-articular injection of collagenase to provoke OA. Expressions of Irisin, adipokines, and MMPs probed with RT-quantitative PCR. Infrapatellar adiposity, articular cartilage damage, and synovial integrity verified with histomorphometry and immunohistochemistry. Infrapatellar adipose and synovial tissues instead of articular cartilage exhibited Irisin immunostaining. Human OA specimens showed 40% decline in Irisin expression than the non-OA group. In vitro, the gain of Irisin function enabled synovial fibroblasts but not chondrocytes to display minor responses to the IL-1β provocation of MMP3 and MMP9 expression. Of note, Irisin signaling reduced adipogenic gene expression and adipocyte formation of mesenchymal progenitor cells. In collagenase-mediated OA knee pathogenesis, forced FNDC5 expression in articular compromised the collagenase-induced infrapatellar adipose hypertrophy, synovial hypercellularity, and membrane hyperplasia. These adipose-regulatory actions warded off the affected knees from cartilage destruction and gait aberrance. Likewise, intra-articular injection of Irisin recombinant protein mitigated the development of infrapatellar adiposity and synovitis slowing down the progression of cartilage erosion and walking profile irregularity. Affected joints and adipocytes responded to the Irisin recombinant protein treatment by reducing the expressions of cartilage-deleterious adipokines IL-6, leptin, and adiponectin through regulating PPAR&gamma, function. Irisin dysfunction is relevant to the existence of end-stage knee OA. Irisin signaling protects from excessive adipogenesis of mesenchymal precursor cells and diminished inflammation and cartilage catabolism actions aggravated by adipocytes and synovial cells. This study sheds emerging new light on the Irisin signaling stabilization of infrapatellar adipose homeostasis and the perspective of the therapeutic potential of Irisin recombinant protein for deescalating knee OA development

Osteoarthritis (OA) is a multifactorial debilitating disease that affects over four million Canadians. Although the mechanism(s) of OA onset is unclear, the biological outcome is cartilage degradation. Cartilage degradation is typified by the progressive loss of extracellular matrix components - aggrecan and type II collagen (Col II) – partly due to the up-regulation of catabolic enzymes - aggrecanases a disintegrin and metalloprotease with thrombospondin motifs (ADAMTS-) 4 and 5 and matrix metalloproteinases (MMPs). There is currently no treatment that will prevent or repair joint damage, and current medications are aimed mostly at pain management. When pain becomes unmanageable arthroplastic surgery is often performed. Interest has developed over the presence of calcium crystals in the synovial fluid of OA patients, as they have been shown to activate synovial fibroblasts inducing the expression of catabolic agents. We recently discovered elevated levels of free calcium in the synovial fluid of OA patients and raised the question on its role in cartilage degeneration. Articular cartilage was isolated from 5 donors undergoing total hip replacement. Chondrocytes were recovered from the cartilage of each femoral head or knee by sequential digestion with Pronase followed by Collagenase and expanded in DMEM supplemented with 10% heat-inactivated FBS. OA and normal human articular chondrocytes (PromoCell, Heidelberg, Germany) were transferred to 6-well plates in culture medium containing various concentrations of calcium (0.5, 1, 2.5, and 5 mM CaCl2), and IL-1β. Cartilage explants were prepared from the same donors and included cartilage with the cortical bone approximately 1 cm2 in dimension. Bovine articular cartilage explants (10 months) were used as a control. Explants were cultured in the above mentioned media, however, the incubation period was extended to 21 days. Immunohistochemistry was performed on cartilage explants to measure expression of Col X, MMP-13, and alkaline phosphatase. The sulfated glycosaminoglycan (GAG, predominantly aggrecan) content of cartilage was analyzed using the 1,9-dimethylmethylene blue (DMMB) dye-binding assay, and aggregan fragmentation was determined by Western blotting using antibody targeted to its G1 domain. Western blotting was also performed on cell lysate from both OA and normal chondrocytes to measure aggrecan, Col II, MMP-3 and −13, ADAMTS-4 and −5. Ca2+ significantly decreased the proteoglycan content of the cartilage explants as determined by the DMMB assay. The presence of aggrecan and Col II also decreased as a function of calcium, in both the human OA and bovine cartilage explants. When normal and OA chondrocytes were cultured in medium supplemented with increasing concentrations of calcium (0.5–5 mM Ca2+), aggrecan and Col II expression decreased dose-dependently. Surprisingly, increasing Ca2+ did not induce the release of MMP-3, and −13, or ADAMTS-4 and-5 in conditioned media from OA and normal chondrocytes. Interestingly, inhibition of the extracellular calcium-sensing receptor CaSR) reversed the effects of calcium on matrix protein synthesis. We provide evidence that Ca2+ may play a direct role in cartilage degradation by regulating the expression of aggrecan and Col II through activation of CaSR

Bone morphogenetic proteins (BMPs) are able to induce osteogenic differentiation in many cells, including muscle cells. However, the actual contribution of muscle cells to bone formation and repair is unclear. Our objective was to examine the capacity of myogenic cells to contribute to BMP-induced ectopic bone formation and fracture repair. Osteogenic gene expression was measured by quantitative PCR in osteoprogenitors, myoblasts, and fibroblasts following BMP-2 treatment. The MyoD-Cre x ROSA26R and MyoD-Cre x Z/AP mouse strains were used to track the fate of MyoD+ cells in vivo. In these double-transgenic mice, MyoD+ progenitors undergo a permanent recombination event to induce reporter gene expression. Ectopic bone was produced by the intramuscular implantation of BMP-7. Closed tibial fractures and open tibial fractures with periosteal stripping were also performed. Cellular contribution was tracked at one, two and three week time points by histological staining. Osteoprogenitors and myoblasts exhibited comparable expression of early and late bone markers; in contrast bone marker expression was considerably less in fibroblasts. The sensitivity of cells to BMP-2 correlated with the expression of BMP receptor-1a (Bmpr1a). Pilot experiments using the MyoD-Cre x Rosa26R mice identified a contribution by MyoD expressing cells in BMP-induced ectopic bone formation. However, false positive LacZ staining in osteoclasts led us to seek alternative systems such as the MyoD-cre x Z/AP mice that have negligible background staining. Initially, a minor contribution from MyoD expressing cells was noted in the ectopic bones in the MyoD-cre x Z/AP mice, but without false positive osteoclast staining. Soft tissue trauma usually precedes the formation of ectopic bone. Hence, to mimic the clinical condition more precisely, physical injury to the muscle was performed. Traumatising the muscle two days prior to BMP-7 implantation: (1) induced MyoD expression in quiescent satellite cells; (2) increased ectopic bone formation; and (3) greatly enhanced the number of MyoD positive cells in the ectopic bone. In open tibial fractures the majority of the initial callus was MyoD+ indicating a significant contribution by myogenic cells. In contrast, closed fractures with the periosteum intact had a negligible myogenic contribution. Myoblasts but not fibroblasts were highly responsive to BMP stimulation and this was associated with BMP receptor expression. Our transgenic mouse models demonstrate for the first time that muscle progenitors can significantly contribute to ectopic bone formation and fracture repair. This may have translational applications for clinical orthopaedic therapies

Animal studies examining tendon-bone healing have demonstrated that the overall structure, composition, and organization of direct type entheses are not regenerated following repair. We examined the effect of Low-Intensity Pulsed Ultrasound (LIPUS) on tendon-bone healing. LIPUS may accelerate and augment the tendon-bone healing process through alteration of critical molecular expressions. Eight skeletally mature wethers, randomly allocated to either control group (n=4) or LIPUS group (n=4), underwent rotator cuff surgery following injury to the infraspinatus tendon. All animals were sacrificed 28 days post surgery to allow examination of early effects of LIPUS. Humeral head – infraspinatus tendon constructs were harvested and processed for histology and immunohistochemical staining for BMP2, Smad4, VEGF and RUNX2. All the growth factors were semiquantitative evaluated. T-tests were used to examine differences which were considered significant at p < 0.05. Levene's Test (p < 0.05) was used to confirm variance homogeneity of the populations. The surgery and LIPUS treatment were well tolerated by all animals. Placement of LIPUS sensor did not unsettle the animals. Histologic appearance at the tendon-bone interface in LIPUS treated group demonstrated general improvement in appearance compared to controls. Generally a thicker region of newly formed woven bone, morphologically resembling trabecular bone, was noted at the tendon-bone interface in the LIPUS-treated group compared to the controls. Structurally, treatment group also showed evidence of a mature interface between tendon and bone as indicated by alignment of collagen fibres as visualized under polarized light. Immunohistochemistry revealed an increase in the protein expression patterns of VEGF (p = 0.038), RUNX2 (p = 0.02) and Smad4 (p = 0.05) in the treatment group. There was no statistical difference found in the expression patterns of BMP2. VEGF was positively stained within osteoblasts in newly formed bone, endothelial cells and some fibroblasts at the interface and focally within fibroblasts around the newly formed vessels. Expression patterns of RUNX2 were similar to that of BMP-2; the staining was noted in active fibroblasts found at the interface as well as in osteoblast-like cells and osteoprogenitor cells. Immunostaining of Smad4 was present in all cell types at the healing interface. The results of this study indicate that LIPUS may aid in tendon to bone healing process in patients who have undergone rotator cuff repair. This treatment may also be beneficial following other types of reconstructive surgeries involving the tendon-bone interface

The purpose of this study is to report a unique overgrowth syndrome and discuss the insights into the complex orthopaedic management. Written consent to report this case was granted. The patient's condition, wrongly diagnosed as Proteus syndrome, is characterised by a genetic mutation in PIK3CA, a critical regulator of cell growth. This lead to unregulated cellular division of fibroblasts isolated to the lower limbs. The legs weighed 117 kg, with a circumference of >110 cm. In addition to lower limb overgrowth, numerous musculoskeletal and organ pathologies have been encountered since birth requiring treatment from a wide variety of healthcare specialists and basic scientists. At 32 years, the patient developed septicaemia secondary to an infected foot ulcer. Amputation had been discussed in the elective setting, however the presence of sepsis expedited surgery. The above knee amputation took 9 hours and four assistants including a plastic surgeon. A difficult dissection revealed a deep subcutaneous fatty layer that integrated with deep muscle, massive hypertrophy of cutaneous nerves and the sciatic nerve and ossification within the distal quarter of the quadriceps muscles requiring osteotomy. The lower limb osteology was grossly aberrant. The size of the amputated limb did not permit use of a tourniquet and cell salvage reintroduced 10.5 litres of blood with a further 6 units of red cells intra-operatively. The leg stump successfully took to a split-skin graft. A unique phenomenon was witnessed post-operatively whereby the stump continued to grow due to upregulation of fibroblasts secondary to trauma. Targeted genetic therapies have been successfully developed to suppress this stump growth. This unique and unclassified overgrowth syndrome was caused by a mutation in the PIK3CA gene. Orthopaedic management of the oversized limb was complex requiring multiple surgeons and prolonged general anesthetic. A multi-disciplinary approach to this condition is required for optimizing outcomes in these patients

Peri-prosthetic osteolysis and subsequent aseptic loosening is the most common reason for revising total hip replacements. Wear particles originating from the prosthetic components interact with multiple cell types in the peri-prosthetic region resulting in an inflammatory process that ultimately leads to peri-prosthetic bone loss. These cells include macrophages, osteoclasts, osteoblasts and fibroblasts. The majority of research in peri-prosthetic osteolysis has concentrated on the role played by osteoclasts and macrophages. The purpose of this review is to assess the role of the osteoblast in peri-prosthetic osteolysis. In peri-prosthetic osteolysis, wear particles may affect osteoblasts and contribute to the osteolytic process by two mechanisms. First, particles and metallic ions have been shown to inhibit the osteoblast in terms of its ability to secrete mineralised bone matrix, by reducing calcium deposition, alkaline phosphatase activity and its ability to proliferate. Secondly, particles and metallic ions have been shown to stimulate osteoblasts to produce pro inflammatory mediators in vitro. In vivo, these mediators have the potential to attract pro-inflammatory cells to the peri-prosthetic area and stimulate osteoclasts to absorb bone. Further research is needed to fully define the role of the osteoblast in peri-prosthetic osteolysis and to explore its potential role as a therapeutic target in this condition. Cite this article: Bone Joint J 2013;95-B:1021–5

Introduction. Currently, different techniques to evaluate biocompatibility of orthopaedic materials, including two-dimensional (2D) cell culture for metal and ceramic wear debris and floating 2D surfaces or three-dimensional (3D) agarose gels for UHMWPE wear debris, are used. We have developed a single method using 3D agarose gels that is suitable to test the biocompatibility of all three types of wear debris simultaneously. Moreover, stimulation of the cells by wear particles embedded in a 3D gel better mimics the in vivo environment. Materials and Methods. Clinically relevant sterile UHMWPE and CoCr wear particles were generated using methodologies described previously [1,2]. Commercially available nanoscale and micron-sized silicon nitride (Si. 3. N. 4. ) particles (<50 nm and <1 μm, Sigma UK) were sterilised by heat treatment for 4h at 180°C. Agarose-particle suspensions were prepared by mixing warm 2% (w/v) low-melting-point agarose solution with the particles dispersed by sonication in DMEM culture media. The suspensions were then allowed to set at room temperature for 10 min in 96 well culture plates. Sub-confluent L929 murine fibroblasts were cultured on the prepared gels for up to 6 days in 5% (v/v) CO. 2. at 37°C. After incubation, the viability of cells was measured using the ATP-lite assay. The results were expressed as mean ± 95% confidence limits and the data was analysed using one-way ANOVA and Tukey-Kramer post-hoc analysis. Results and Discussion. The gels were observed to ensure uniform distribution of particles and migration of cells into the gel. No significant reduction in viability was observed for nanoscale and micron-sized Si. 3. N. 4. particles at low doses (0.5 μm. 3. per cell) and high doses (50 μm. 3. per cell), or for UHMWPE wear debris at high doses (100 μm. 3. per cell) [Figure1]. Moreover, the viability was significantly reduced for high doses of CoCr wear debris (50 μm. 3. per cell) and the positive control, camptothecin (2 μg.ml. −1. ) at day 6 [Figure1]. These results are consistent with the literature [2,3] and therefore validate our 3D agarose cell culture method for comparing cytotoxicity of polymer, metal and ceramic particles in a single assay, simultaneously. Conclusion. Biocompatibility ofpolymer, metal and ceramic wear debris can be tested simultaneously by using 3D particle embedded agarose gels. Acknowledgements. The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. GA-310477 LifeLongJoints

The process by which pathologic scar tissue forms after TKA and restricts functional range of motion is relatively poorly understood. Arthrofibrosis may develop in patients who have normal intra-operative range of motion (ROM). However, passive flexion, extension, or both can become restricted and painful, sometimes several weeks after surgery following an early post-operative period of normal motion. The response to both nonsurgical and surgical treatment is often unsatisfactory. Arthrofibrotic scar contains dense fibrous tissue with abundant fibroblasts. Heterotopic bone is frequently found in patients with arthrofibrosis. Stiffness may result from inadequate postsurgical pain management or rehabilitation or from a biologic process that causes rapid proliferation of scar tissue. Genetic factors also may play a role, although it is difficult to predict which patients are at increased risk for arthrofibrosis after TKA. Surgical technique also can contribute; oversizing the femoral component, overstuffing the patella, or rotational malalignment can play a role. Manipulation can be helpful, particularly during the first three months after surgery. However, maintaining motion long term also requires an effective pain management and physical therapy program after manipulation. Arthroscopy may also have a role to remove scar tissue in the suprapatellar pouch and medial and lateral gutters usually between six months and one year after TKA. After one year following TKA, open surgical release or revision surgery is the most effective method to increase motion. However, only modest gains are likely to be achieved and pain may not be improved

Our previous study has revealed that silver nanoparticles (AgNPs) have potential to promote wound healing by accelerated re-epithelization and enhanced differentiation of fibroblasts. However, the effect of AgNPs on the functionality of repaired skin is unknown. The aim of this study was to explore the tensile properties of healed skin after treatment with AgNPs. Immunohistochemical staining, quantitative assay and scanning electron microscopy (SEM) were used to detect and compare collagen deposition, and the morphology and distribution of collagen fibers. Our results showed that AgNPs improved tensile properties and led to better fibril alignments in repaired skin, with a close resemblance to normal skin. Based on our findings, we concluded that AgNPs were predominantly responsible for regulating deposition of collagen and their use resulted in excellent alignment in the wound healing process. The exact signaling pathway by which AgNPs affect collagen regeneration is yet to be investigated

Orthopaedic cobalt chromium particles and ions can induce indirect DNA damage and chromosome aberrations in human cells on the other side of a cellular barrier in tissue culture. This occurs by intercellular signalling across the barrier. We now show that the threshold for this effect depends on the metal form and the particle composition. Ionic cobalt and chromium induced single strand breaks at concentrations equivalent to those found in the blood of patients with well functioning metal on metal hip prostheses. However, they only caused double strand breaks if the chromium was present as chromium (VI), and did not induce chromosome aberrations. Nanoparticles of cobalt chromium alloy caused DNA double strand breaks and chromosome aberrations, of which the majority were tetraploidy. Ceramic nanoparticles induced only single strand breaks and/or alkaline labile sites when indirectly exposed to human fibroblasts. The assessment of reproductive risk from maternal exposure to biomaterials, especially those liberated by orthopaedic implants, is not yet possible with epidemiology. Whilst the barrier model used here differs from the in vivo situation in several respects, it may be useful as a framework to evaluate biomaterial induced damage across physiological barriers

Orthopaedic cobalt chromium particles and ions can induce indirect DNA damage and chromosome aberrations in human cells on the other side of a cellular barrier in tissue culture. This occurs by intercellular signalling across the barrier. We now show that the threshold for this effect depends on the metal form and the particle composition. Ionic cobalt and chromium induced single strand breaks at concentrations equivalent to those found in the blood of patients with well functioning metal on metal hip prostheses. However, they only caused double strand breaks if the chromium was present as chromium (VI), and did not induce chromosome aberrations. Nanoparticles of cobalt chromium alloy caused DNA double strand breaks and chromosome aberrations, of which the majority were tetraploidy. Ceramic nanoparticles induced only single strand breaks and/or alkaline labile sites when indirectly exposed to human fibroblasts. The assessment of reproductive risk from maternal exposure to biomaterials, especially those liberated by orthopaedic implants, is not yet possible with epidemiology. Whilst the barrier model used here differs from the in vivo situation in several respects, it may be useful as a framework to evaluate biomaterial induced damage across physiological barriers

Infection and skin ulcer are major problems in Total Knee Arthroplasty (TKA) and Bipolar Hip Prosthesis (BHP). Sugar (sucrose) has been used for wound care in many countries because it absorbs fluid, stimulates granulation, and suppress growth of bacteria. Trafermin ∗∗∗∗∗ recombinant human basic fibroblast growth factor ∗∗∗∗∗ FGF ∗∗∗∗∗ accelerates granulation process and improves quality of wound healing. We have used sucrose and trafermin for treatment of infection after TKA and BHP. Six infected TKA with skin ulcer and one infected BHP with fistula were treated with Trafermin and sugar. TKA were performed in four osteoarthritis and two rheumatoid arthritis, and BHP was for femoral neck fracture. Implants were removed in three cases because of deep infection. One was male and six were female, average age were 60.8 years old ranged 43 to 77. Follow-up period were one to 5 years. Four cases were related to MRSA. Sugar treatment were performed for two to 23 weeks, and Trafermin was sprayed once a day for two to 16weeks. In BHP case, sugar therapy was performed intermittently. In two deep infected TKA cases, infection ceased in one to 4 month and revision TKA were performed. In other four TKA cases, infection were ceased in two to 16 weeks. In BHP case, fistula closed in three years. Combination of Trafermin and sugar is useful for management of infection and skin ulcer after TKA and BHP

Objective. The aim of this study was to investigate PDGF release in the peripheral circulation following trauma and to correlate it with the numbers of MSCs in iliac crest bone marrow (BM) aspirate. Methods. Trauma patients with lower extremity fractures (n=18, age 21–64 years) were recruited prospectively. Peripheral blood was obtained on admission, and at 1, 3, 5 and 7 days following admission. The serum was collected and PDGF was measured using ELISA. Iliac crest (BM) aspirate (20ml) was obtained on days 0–9 following admission. MSCs were enumerated using standard colony-forming unit fibroblasts (CFU-F) assay. Results. We observed a gradual increase in serum PDGF levels following fracture (r. 2. =0.79, p=0.005, n=18), which reached up to 4-fold on day 7. In 12 out of 18 patients recruited for CFU-F study, an increase in iliac crest BM CFU-F/ml of aspirate was observed, reaching an average 10-fold post-fracture (range days 3 to day 9). In 15 patients, for which PDGF and CFU-F were measured in parallel, a strong positive correlation was observed between CFU-F numbers per millilitre of BM aspirate and circulating PDGF levels (r=0.55, p< 0.05). Discussion and conclusion. Our data demonstrate, for the first time, that BM MSC pool in humans is not static and can be stimulated following trauma. This is not a result of mobilisation of MSCs into systemic circulation. Rather, MSC activation at remote sites, like iliac crest BM, can be due to systemic up-regulation of several cytokines and growth factors, including PDGF, in peripheral circulation. This data therefore enable a more comprehensive understanding of MSC dynamics in response to trauma and can inform the design of a clinical trial aimed to optimise the location and timing of BM harvest for use in bone regeneration following fracture

Although chondrocytes have been used for autologous implantation in defects of articular cartilage, limited availability and donor-site morbidity have led to the search for alternative cell sources. Mesenchymal stem cells from various sources represent one option. The infrapatellar fat-pad is a promising source. Advantages include low morbidity, ease of harvest and ex-vivo evidence of chondrogenesis. Expansion of MSCs from human fat-pad in FGF-2 has been shown to enhance chondrogenesis. To further elucidate this process, we assessed the role of TGF-?3, FGF-2 and oxygen tension on growth kinetics of these cells during expansion. Methods. Infrapatellar fatpads were obtained from 4 donors with osteoarthritis. Cells were expanded in various media formulations (STD, FGF, TGF and FGF/TGF) at both 20% and 5% oxygen tensions. Colony forming unit fibroblast assays were performed for each expansion group and assessed with crystal violet staining. Cell aggregates from each group underwent chondrogenic differentiation in 5% and atmospheric oxygen tension. Pellets were analyzed on day 21. Results. 5% Oxygen tension during expansion increased the colony size for both FGF and FGF/TGF groups. Cells expanded in FGF/TGF proliferated more rapidly. Biochemical analysis revealed that cells expanded in FGF-2 had higher glycosaminoglycan synthesis rates, a marker for chondrogenesis. Differentiation at 5% pO. 2. led to higher levels of sGAG but its effect was generally less potent compared to expansion in FGF-2. Discussion. In agreement with previous findings, expansion of fat-pad MSCs in FGF-2 resulted in enhanced chondrogenesis and increased colony forming capacity. Combined FGF-2 and TGF-?3 during expansion decreased the population doubling time but led to decreased matrix synthesis. Differentiation in low oxygen was beneficial to subsequent chondrogenesis. In conclusion, addition of FGF-2 during the expansion phase was the most potent promoter of the subsequent chondrogenesis of hMSCs isolated from the infrapatellar fat-pad

Background. The process of osteolysis is well studied both in vivo and in vitro. Although multiple pathways have been implicated in osteolytic change and animal models have been developed there are few human tissue studies. There are no extensive human tissue studies comparing osteoarthritic hips to well fixed and loose prostheses. Methods. We have investigated 96 genes previously implicated in the osteolytic pathway. Genes were included based on previous implication in osteolysis in basic science studies. Candidates included cytokines, growth factors, apoptotic factors, matrix proteinases, interleukins, apoptotic proteins and macrophage activators. Results. One hundred patients were enrolled into the study and had intraoperative hip tissue removed after ethics approval. Patients were recruited from three cohorts, those undergoing primary hip replacement, revision of a well fixed prosthesis and revision for osteolytic change. A low density Taqman array method was used to determine gene expression for the 96 candidate genes. Expression of five housekeeping genes was measured and expression normalised between the samples. Statistical analysis was undertaken using significance testing and ROC analysis. There were seven candidate genes that were statistically significantly linked to aseptic loosening (p< 0.05) and strongly associated (AUC >0.77); these were BMP4, Frizzled related protein, fibroblast growth factor 18, IL8, IRAK 3, osteoprotegrin and PTGS2. There were a further nine genes which were highly predictive of osteolytic change (AUC >0.77), but did not reach significance (p>0.05): VEGFB, SFRP, TLR3, TLR5, TP53, IGF1, CTSK, CHIT 1 and CCL 18. Conclusion. We have been able to distinguish for the first time between factors which are associated with osteolytic change, those associated with exposure to wear debris in a well fixed prosthesis and those associated with the process of osteoarthritis

Purpose. Internal fixation of fractures in the presence of osteopenia has been associated with a failure rate as high as 25%. Enhancing bone formation and osseointegration of orthopaedic hardware is a priority when treating patients with impaired bone regenerative capacity. Fibroblast Growth Factor (FGF) 18 regulates skeletal development and could therefore have applications in implant integration. This study was designed to determine if FGF 18 promotes bone formation and osseointegration in the osteopenic FGFR3−/− mouse and to examine its effect on bone marrow derived mesenchymal stem cells (MSCs). Method. In Vivo: Intramedullary implants were fabricated from 0.4 × 10mm nylon rods coated with 300nm of titanium by physical vapour deposition. Skeletally mature, age matched female FGFR3−/− and wild type mice received bilateral intramedullary femoral implants. Left femurs received an intramedullary injection of 0.1μg of FGF 18 (Merck Serono), and right femurs received saline only. Six weeks later, femurs were harvested, radiographed, scanned by micro CT, and processed for undecalcified for histology. In Vitro: MSCs were harvested from femurs and tibiae of skeletally mature age matched FGFR3−/− and wild type mice. Cells were cultured in Alpha Modified Eagles Medium (αMEM) to monitor proliferation or αMEM supplemented with ascorbic acid and sodium beta-glycerophosphate to monitor differentiation. Proliferation was assessed through cell counts and metabolic activity at days 3, 6 and 9. Differentiation was assessed through staining for osteoblasts and mineral deposition at days 6, 9 and 12. Results. Wild type mice exhibited more peri-implant bone formation compared to FGFR3−/− mice. Peri-implant bone formation at the proximal metaphyseal-diaphyseal junction was increased in FGF18 treated femurs compared with contralateral control femurs in wild type (p = NS) and FGFR3−/− (p = 0.04) mice. Histological analysis corroborated micro CT findings, with FGF 18 treated FGFR3−/− femurs forming peri-implant bone instead of the fibrous response seen in controls. In vitro studies showed that FGF18 significantly increased MSC proliferation and metabolism in a dose dependent manner in wild type and FGFR3−/− mice. Osteoblast differentiation was inhibited by FGF18 in wild type MSCs, but was increased at physiological concentrations in cells harvested from FGFR3−/− mice. Conclusion. FGF 18 increases bone formation and osseointegration of intramedullary implants in osteopenic mice and increases MSC proliferation in both the presence and absence of FGFR3. FGF18 also promoted osteoblast differentiation in the absence of FGFR3 signalling, most likely via FGFR1 or 2. Additional work is needed to confirm the identity of the alternate FGFR and to evaluate its capacity to improve osseous healing in unfavourable in-vivo environments