Aims. Demineralised bone matrix (DBM) is rarely used for the local delivery of prophylactic antibiotics. Our aim, in this study, was to show that a graft with a bioactive glass and DBM combination, which is currently available for clinical use, can be loaded with tobramycin and release levels of antibiotic greater than the minimum inhibitory concentration for Staphylococcus aureus without interfering with the bone healing properties of the graft, thus protecting the graft and surrounding tissues from infection. Materials and Methods. Antibiotic was loaded into a graft and subsequently evaluated for drug elution kinetics and the inhibition of bacterial growth. A rat femoral condylar plug model was used to determine the effect of the graft, loaded with antibiotic, on bone healing. Results. We found that tobramycin loaded into a graft composed of bioglass and DBM eluted antibiotic above the minimum inhibitory concentration for three days in vitro. It was also found that the antibiotic loaded into the graft produced no adverse effects on the bone healing properties of the DBM at a lower level of antibiotic. Conclusion. This antibiotic-loaded bone void filler may represent a promising option for the delivery of local antibiotics in orthopaedic surgery. Cite this article: Bone Joint J 2016;98-B:1126–31

Background:. Little is known about the forces carried by the Taylor Spatial Frame (TSF) hexapod fixator. Our aim was to measure the TSF resultant force and how this changed during the consolidation phase. Method:. Five patients undergoing correction of tibial deformities were recruited. Measurements were taken at 2, 4, 8 and 12 weeks post-correction during various activities. Instrumented struts incorporating strain gauges measuring axial force were temporarily used each time. Strut forces and lengths were used to determine frame kinetics. The resultant axial fixator forces and moments were calculated relative to sitting. Ground reaction forces (GRF) were measured using the treadmill force plates. Results & Discussion:. Due to the subjects' varying confidence in weight bearing the forces varied both inter- and intra-activity and over post-corrective time. Variation in individual strut forces produced a resultant force and bending moment across the fixation. As the healing bone assumed more load over time there was a reduction in the force and bending excursions across the frame as a percentage of GRF, achieving a minimum by 8 weeks. Conclusion:. Instrumented TSFs are a useful means of assessing the forces acting during healing. Monitoring of these forces can determine optimal removal

Introduction. Intraosseous transcutaneous amputation prostheses (ITAP) provide an alternative means of attaching artificial limbs for amputees. Conventional stump-socket devices are associated with soft tissue complications including; pressure sores and tissue necrosis. ITAP resolves these problems by attaching the exo-prosthesis transcutaneously to the skeleton. The aim of this study is to increase the attachment of dermal fibroblasts to titanium alloy in vitro. Fibronectin (Fn) and laminin 332 (Ln) enhance early cell growth and adhesion. We hypothesize that silanized dual coatings of fibronectin and laminin (SiFnLn) will be more durable when compared with adsorbed dual coating (AdFnLn), and will enhance early fibroblast growth and adhesion compared to single coatings. Methods. The kinetics of dual single and dual protein coating attachment onto titanium alloy was quantified on silanized 10mm diameter discs using radiolabelled Fn (125I-Fn) and Ln (125I-Ln). Sixty discs were polished, sterilized and silanized. Coating durability was assessed when soaked in fetal calf serum (FCS) for 0, 1, 24, 48 and 72hrs. Data was compared to un-silanized Ti discs with the same coatings. Five thousand human dermal fibroblasts were seeded on discs (n = 6) of Ti polished alone (Pol), Ti with adsorbed fibronectin (AdFn), Ti with adsorbed laminin (AdLn), Ti adsorbed dual coating (AdFnLn), Ti silanized (Si), Ti silanized with fibronectin (SiFn), Ti silanized with laminin (SiLn), Ti silanized with a dual coating (SiFnLn) for 24hrs. In order to measure cell adhesion fibroblasts were fixed, vinculin stained using mouse vinculin antibody and alexa fluor. Axiovision Image Analysis software was used to measure cell area, vinculin focal adhesion markers per cell and per unit cell area. Data was analysed in SPSS and significance was assumed at the 0.05 level. Results. Silanized dual coatings bonded to Ti alloy in significantly larger quantities compared with adsorbed coatings at all time points (all p values < 0.05). Fibroblasts cultured on dual coatings were significantly larger, produced more vinculin markers per cell, and per unit cell area compared with single coatings. Cells on SiFnLn were larger with more numerous vinculin markers per cell, and per unit cell area compared with AdFnLn (p<0.05). Conclusion. This study has demonstrated that covalently bonding both fibronectin and laminin to Ti alloy provides a durable, dual coating that enhances early fibroblast growth and attachment compared with either protein coating alone in vitro. Our study showed that there is non-competitive binding of laminin on Ti surfaces in the presence of fibronectin. Dual coatings may be applied to the skin-penetrating region of transcutaneous devices to improve the skin seal and this may have positive implications for the development of ITAP

Introduction. Following amputation, residual stumps used to attach the external prostheses can be associated with sores, infection and skin necrosis. These problems could be overcome by off loading the soft tissues. Intraosseous transcutaneous amputation prostheses (ITAP) attach external implants directly to residual bone reducing these complications. However, a tight seal at the skin implant interface is crucial in preventing epithelial down-growth and infection. Fibronectin (Fn) and laminin 332 (Ln), enhance early cell growth and adhesion of keratinocytes. Silanization to titanium alloy (Ti) allows these proteins to bond to the metal directly. We hypothesize that silanized dual coatings of fibronectin and laminin (SiFnLn) will be more durable than absorbed proteins and that keratinocyte adhesion will be increased compared with Ti controls and single silanized proteins. Methods. 10 mm diameter Ti alloy discs were polished, sterilized and silanized. The kinetics of silanized single and dual protein coating attachment onto titanium alloy was quantified using radio-labelled Fn(125I-Fn) and Ln(125I-Ln). Coating durability was assessed when soaked in fetal calf serum (FCS) for 0, 1, 24, 48, 72hrs. Data was compared to un-silanized Ti discs with the same amount of adsorbed proteins. In order to study cell attachment 20 × 103 keratinocytes were seeded on the discs (n = 6): silanized (Si), silanized fibronectin (SiFn), silanized laminin (SiLn), silanized dual coating (SiFnLn) for 1, 4 and 24hrs. Adhesion of cells was assessed using mouse vinculin antibody for 2hrs and alexafluor for 1hr which stains focal adhesions responsible for attaching cells to surfaces. Axiovision Image Analysis software was used to measure cell area, vinculin markers per cell unit and per unit cell area on 15 cells per disc. Data was analysed in SPSS and significance was assumed at the 0.05 level. Results. Silanized dual coatings bonded to Ti alloy in significantly larger quantities compared with adsorbed coatings (all p values < 0.05). When proteins were combined on silanized discs the same amount of each protein was attached as when used as a single coating (i.e. non competitive binding). Keratinocytes cultured on silanized dual coatings were significantly larger, produced more vinculin markers per unit cell and per cell area compared with single coatings at all time points. Conclusion. This study has demonstrated that silanized using dual proteins on Ti alloy enhances early keratinocyte growth and attachment in vitro. It also shows that there is non-competitive binding of laminin to Ti alloys in presence of fibronectin. This may lead to improved epidermal attachment to ITAP creating a tight seal at the implant interface, which will prevent migration of the epithelium and subsequent infection in vivo

Introduction. In total hip arthroplasty ceramic on ceramic bearing couples are used more and more frequently and on a wordwide basis. The main reason of this choice is reduction of wear debris and osteolysis. The tribological properties and the mechanical behaviour of the implanted ceramic must remain the same throughout the patient's life. The aim of this study was to evaluate the resistance of Alumina Matrix Composite to environmental degradation. Material and method. The alumina matrix composite or BIOLOX ® delta is manufactured in Germany by CeramTec. It is made up of 80 vol.% Al2O3, 17 vol.% Yttria Stabilized ZrO2 and 3vol.% strontium aluminate platelets. The zirconia grains account for 1.3 mol.% of the Yttria content. Accelerated aging tests in water steam at 142°C, 134°C, 121°C, and 105°C were performed to evaluate the aging kinetics of the composite. X-ray diffraction was used to determine the monoclinic phase content on the material surface. Phase transformation is associated with weakness and increase in roughness of zirconia ceramic implants. Results. The data below shows average monoclinic contents before and after aging in water vapour according to the ISO standard test (134°C, 2 bars water steam, 10 h) on the surface and inside the 28 mm taper(12/14 taper) femoral ball heads manufactured in alumina ceramic composite. There are precisions concerning the roughness and the load to failure before and after aging concerning 28mm diameter heads. Before Aging 13%+/-3% of Monoclinic content. After 10 H at 134°C23%+/-3% of Monoclinic content the roughness of the polished surface remain the same (5nm+/− 2). The load to failure of 28 mm heads before aging is 76 kN +/− 5kN, and 72 kN +/− 5kN after aging. The results show that although a rise in monoclinic content is predictable after long aging duration in vivo, the impact of the transformation is quite different to monolithic zirconia. A zirconia femoral head exhibits an important increase of roughness from 2 nm to more than 50 nm when submitted to the same duration of ageing. Other tests with hip simulators under severe micro separation have been done to analyse the impact of aging on wear performance. The main wear zone on femoral heads underwent a phase transformation from tetragonal to monoclinic (23% monoclinic) at 5 milion cycles duration without any change in roughness after 5Mc duration. Conclusion. This experimental testing program has enabled a prediction for the long-term in vivo environmental resistance of prostheses made out of Alumina Matrix Composite. The substantial improvement in mechanical properties and the excellent wear behaviour, even under severe microseparation conditions has been clinically confirmed. Today more than 960,000 ceramic ball heads and more than 450 000 ceramic inserts made of the alumina matrix composite have been implanted. Additionally, due to enhanced mechanical behaviour, new applications in orthopaedics are possible