Introduction

Periprosthetic infections are leading causes of revision surgery resulting in significant increased patient comorbidities and costs. Considerable research has targeted development of biomaterials that may eliminate implant-related infections.¹ This in vitro study was developed to compare biofilm formation on three materials used in spinal fusion surgery – silicon nitride, PEEK, and titanium – using one gram-positive and one gram-negative bacterial species.

Introduction

The complex cellular mechanisms of the aseptic loosening of total joint arthroplasties still remain not completely understood in detail. Especially the role of adherent endotoxins in this process remains unclear, as lipopolysaccharides (LPS) are known to be very potent modulators of the cell response on wear particle debris. Contributing factors on the LPS affinity of used orthopedic biomaterials as their surface roughness have to be investigated. The aim of this study was to evaluate the affinity of LPS on the surface roughness of different biomaterials in vitro. The hypothesis of the study was that rough surfaces bind more LPS than smooth surfaces.

Introduction

Due to its remarkable stoichiometric flexibility and surface chemistry, hydroxyapatite (HAp) is the fundamental structural material in all vertebrates. Natural HAp's properties inspired an investigation into silicon nitride (Si₃N₄) to see if similar functionality could be engineered into this bioceramic. Biological and in situ spectroscopic analyses were used to monitor the response of osteosarcoma cells (SaOS-2) to surface-modulated Si₃N₄ and a titanium alloy after long-term in vitro exposure.

Aim

The primary aim of this in vitro study was to test the efficacy of daptomycin to eradicate staphylococcal biofilms on various orthopedic implant surfaces and materials. The secondary aim was to quantitatively estimate the formation of staphylococcal biofilm on various implant materials with different surface properties.

Aim. The rise of multidrug-resistant bacteria and the decreasing efficacy of antibiotic therapy in successfully treating biofilm-associated infections are prompting the exploration of alternative treatment options. This study investigates the efficacy of different bioactive glass (BAG) formulations - alone or combined with vancomycin - to eradicate biofilm. Further, we study the influence of BAG on pH and osmotic pressure as important factors limiting bacterial growth. Method. Different BAG-S53P4 formulations were used for this study, including (a) BAG-powder (<45 μm), (b) BAG-granules (500–800 μm), (c) a cone-shaped BAG-scaffold and (d) two kinds of BAG-putty containing granules, with no powder (putty-A) or with additional powder (putty-B), and a synthetic binder. Inert glass beads were included as control. All formulations were tested in a concentration of 1750 g/ml in Müller-Hinton-Broth. Targeted bacteria included methicillin-resistant Staphylococcus aureus (MRSA) and epidermidis (MRSE). Vancomycin was tested at the minimum-inhibitory-concentration for each strain (1 µg/ml for MRSA; 2 μg/ml for MRSE). To investigate the antibiofilm effect of BAG alone or combined with vancomycin, 3 hour-old MRSA or MRSE biofilms were formed on porous glass beads and exposed to BAG ± vancomycin for 24h, 72h and 168h. After co-incubation, biofilm-beads were deep-washed in phosphate-buffered saline and placed in glass vials containing fresh medium. Recovering biofilm bacteria were detected by measuring growth-related heat production at 37°C for 24h by isothermal microcalorimetry. Changes in pH and osmotic pressure over time were assessed after co-incubation of each BAG formulation in Müller-Hinton-Broth for 0h, 24h, 72h and 168h. Results. All BAG formulations showed antibiofilm activity against MRSA and MRSE in a time-dependent manner, where longer incubation times revealed higher antibiofilm activity. BAG-powder and BAG-putty-B were the most effective formulations suppressing biofilm, followed by BAG-granules, BAG-scaffold and finally BAG-putty-A. The addition of vancomycin had no substantial impact on biofilm suppression. An increase in pH and osmotic pressure over time could be observed for all BAG formulations. BAG-powder reached the highest pH value of 12.5, whereas BAG-putty-A resulted in the lowest pH of 9. Both BAG-putty formulations displayed the greatest increase on osmotic pressure. Conclusions. BAG-S53P4 has demonstrated efficient biofilm suppression against MRSA and MRSE, especially in powder-containing formulations. Our data indicates no additional antibiofilm improvement with addition of vancomycin. Moreover, high pH appears to have a larger antimicrobial impact than high osmolarity. Acknowledgements. This work was supported by PRO-IMPLANT Foundation (Berlin, Germany). The tested materials were provided by Bonalive Biomaterials Ltd (Turku, Finland)

Aim. Infections in long bones can be divided in osteitis, osteomyelitis and septic non-unions. All are challenging situations for the orthopaedic surgeon. Treatment is a mix with debridement, radical resection of infected tissue, void filling with different types of products, and antibiotic therapy of different kinds. In cavitary bone defects, bioglasses such as BAG-S53P4 have given good results in early or mid-term follow-up. Results of such treatment in segmental bone defects remain unknown. The goal of our study was to evaluate efficacity of active bioglass BAG-S53P4 in septic segmental bone defects. Method. A retrospective cohort study has been done in a single specific orthopaedic center devoted to treatment of infected bony situations. All cases were a severe septic bone defect. We have compared the segmental bone defects to the cavitary ones. Results were analyzed on recurrence of infection, bone healing, functional result and complication rate. Results. 14 patients were included with a minimum follow-up of 1 year after treatment. 8 were in the group “cavitary”, 6 in the group “segmental”. The mean age was 54 years-old (30–76). Sex-ratio was 2.5. All patients have been treated with bone resection and debridement of infected bone and tissue, even if more than 1 surgery was necessary in some cases. After cleaning, 7 patients have needed a local flap, and 1 a free flap. Then, all bone defects were filled up by bioglass BAG-S53P4*. Additional antibiotherapy with specific molecules based of the results of bacterial analysis, was given for a minimum time-period of 6 weeks. In the “cavitary” group, the mean volume of BAG-S53P4 was de 21.25 ml (10–60). In the “segmental” group, it was of 12.5 ml (10–20). The healing rate was of 80% in the “cavitary” group and of 100% in the “segmental” one. No complication related to the bioglass insertion was noted. Conclusions. Different publications have been made using bioglass in the treatment of infected bone with a continuous bone such as osteitis or osteomyelitis. Our study is the first one to compare specifically the results obtained in a cavitary defect where the bone is still in continuity, and in a segmental defect. Active bioglass such as the BAG-S53P4 seems to be a good option in the treatment of segmental septic bone defects in the limb. *BonAlive Biomaterials Ltd, Turku, Finland

Aims

The standard of wide tumour-like resection for chronic osteomyelitis (COM) has been challenged recently by adequate debridement. This paper reviews the evolution of surgical debridement for long bone COM, and presents the outcome of adequate debridement in a tertiary bone infection unit.

Purpose. Osteochondral lesions (OCL) of the talus remain a challenging therapeutic task to orthopaedic surgeons. Several operative techniques are available for treatment, e.g. autologous chondrocyte implantation (ACI), osteochondral autograft transfer system (OATS), matrix-induced autologous chondrocyte implantation (MACI). Good early results are reported; however, disadvantages are sacrifice of healthy cartilage of another joint or necessity of a two-stage procedure. This case describes a novel, one-step operative treatment of OCL of the talus utilizing the autologous matrix-induced chondrogenesis (AMIC) technique in combination with a collagen I/III membrane. Method. 20 patients (8 female, 12 male; mean age 36, range 17–55 years) were assessed in our outpatient clinic for unilateral OCL of the talus. Preoperative assessment included the AOFAS hindfoot scale, conventional radiography, magnetresonancetomography (MRI) and SPECT-CT. Surgical procedure consisted of debridement of the OCL, spongiosa plasty from the iliac crest and coverage with the I/III collagen membrane (Chondrogide, Geistlich Biomaterials, Wolhusen, Switzerland). Clinical and radiological followup was performed after one year. Results. The mean preoperative AOFAS hindfoot scale was poor with 63.1 points (SD 19.6). At one year followup the score improved significantly (p<0.01) to 86 points (SD 12). At one year followup conventional radiographs showed osseous integration of the graft in all cases. MRI at one year showed intact cartilage covering the lesions in all cases. Conclusion. The initial results of this ongoing study are encouraging. The clinical and radiological results at one year followup are comparable with the results of ACI, OATS and MACI. The AMIC procedure is a readily available, economically efficient, one step surgical procedure. No culturing after chondrocyte harvesting or destruction of viable cartilage is necessary

Biomaterials used in regenerative medicine should be able to support and promote the growth and repair of natural tissues. Bioactive glasses (BGs) have a great potential for applications in bone tissue engineering [1, 2]. As it is well known BGs can bond to host bone and stimulate bone cells toward osteogenesis. Silicate BGs, e.g. 45S5 Bioglass® (composition in wt.%: 45 SiO. 2. , 6 P. 2. O. 5. , 24, 5 Na. 2. O and 24.5 CaO), exhibit positive characteristics for bone engineering applications considering that reactions on the material surface induce the release of critical concentrations of soluble Si, Ca, P and Na ions, which can lead to the up regulation of different genes in osteoblastic cells, which in turn promote rapid bone formation. BGs are also increasingly investigated for their angiogenic properties. This presentation is focused on cell behavior of osteoblast-like cells and osteoclast-like cells on BGs with varying sample geometry (including dense discs for material evaluation and coatings of highly porous Al. 2. O. 3. -scaffolds as an example of load-bearing implants). To obtain mechanically competent porous samples with trabecular architecture analogous to those of cancellous bone, in this study Al. 2. O. 3. scaffolds were fabricated by the well-known foam replication method and coated with Bioglass® by dip coating. The resulted geometry and porosity were proven by SEM and μCT. Originating from peripheral blood mononuclear cells formed multinucleated giant cells, i.e. osteoclast-like cells, after 3 weeks of stimulation with RANKL and M-CSF. Thus, the bioactive glass surface can be considered a promising material for bone healing, providing a surface for bone remodeling. Osteoblast-like cells and bone marrow stromal cells were seeded on dense bioactive glass substrates and coatings showing an initial inhibited cell attachment but later a strong osteogenic differentiation. Additionally, cell attachment and differentiation studies were carried out by staining cytoskeleton and measuring specific alkaline phosphatase activity. In this context, 45S5 bioactive glass surfaces can be considered a highly promising material for bone tissue regeneration, providing very fast kinetics for bone-like hydroxyapatite formation (mineralization). Our examinations revealed good results in vitro for cell seeding efficacy, cell attachment, viability, proliferation and cell penetration onto dense and porous Bioglass®-coated scaffolds. Recent in vivo investigations [3] have revealed also the angiogenic potential of bioactive glass both in particulate form and as 3D scaffolds confirming the high potential of BGs for bone regeneration strategies at different scales. Implant surfaces based on bioactive glasses offer new opportunities to develop these advanced biomaterials for the next generation of implantable devices and tissue scaffolds with desired tissue-implant interaction

Introduction. Core decompression is used in precollapse lesions to forestall disease progression in avascular necrosis (AVN) of femoral head (FH). The author reports a new technique using reverse bone graft technique to effectuate core decompression. Aim. To prevent precollapse in Ficat Type 1&2 and revascularization using synthetic bone graft material. Methods. A 18 year female police trainee with Magnetic Resonance Imaging (MRI) confirming AVN Stage 2 Ficat, clinically painful hip not evident in x-rays consented to undergo this new technique. Reverse bone graft technique with a Coring reamer – Patent 5423823. A minimally invasive technique with lateral 2 cm incision introducing 8.5 mm core reamer to remove a core of bone up to the subchondral bone. The subchondral cyst decompressed and curetted under video recorded Image Intensifier (II). Demarcated avascular bone segment excised and bone graft reversed and inserted with cortical bone acting as a support to prevent collapse and the distal segment augmented using 5 grams of osteoconductive granular synthetic bone graft material based on calcium phosphate hydroxyapatite (HA 2500–5000 μm). Avascular segment histopathologically confirmed AVN. The metaphyseal entry was extrapoliated at the lateral cortex using the combined necrotic angle described by Kerboul in the anteroposterior and lateral views under II. Protected weight bearing for 2 months to prevent stress riser. Biomaterials. HA granules named as GranuMas™ developed under Intensified Research in Priority Areas (IRPA) Research Project (No. 03-01-03-0000-PR0026/05) and invented by the Advance Materials Research Centre (AMREC) and manufactured by GranuLab –Patent P1 20040748 fulfilling the criteria for American Society for Testing and Materials (ASTM) F1185-88(1993) Standards which is ‘Standard Specification for Composition of Ceramic Hydroxyapatite for Surgical Implants’. Derived from Malaysian limestone, ranging from 200–5000 μm gamma sterilized. Results. After 6 months, there was no collapse of subchondral bone and the FH showed revascularization along bone grafted site with viable graft and increased radiotracer activity using 99-Tc MDP Bone Planar Scintigraphy. Clinical analysis follow up at 2 years was descriptive rather than statistical with a x-ray evident incorporated graft and with pain free full range of movement. Discussion. Reduction in intraosseous pressure is achieved by using large bore 8.5 mm coupled with HA granules promoting revascularization. The core tract entering through the metaphyseal region reduces risk of subtrochanteric fracture a potential complication of vascularized fibular grafts and with less morbidity with other treatment methods for osteonecrosis of the femoral head. The concept can be extended in introducing stem cell and biologic material to treat AVN. Conclusion. This technique is minimally invasive and effective in young patients with early stage of FH AVN and has shown revascularization along the bone grafted site

Objectives

The purpose of this study was to evaluate in vivo biocompatibility of novel single-walled carbon nanotubes (SWCNT)/poly(lactic-co-glycolic acid) (PLAGA) composites for applications in bone and tissue regeneration.