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Bone toxicity and inhibition of bone healing by combination and high doses of antibiotics: An in vitro study
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Abstracts / Injury Extra 43 (2013) 71–127
[1B.4] The biomechanical role of the periosteum in fracture prevention P. Pastides ∗ , I. Khan, M. Jones, P. Theobald Cardiff University School of Engineering, United Kingdom Aim: The periosteum has a well recognised role in osteogenesis and as a source of stem cells. However the mechanical properties of the periosteum and its role in fracture prevention are a neglected domain. The aim of this study was to evaluate whether the presence or not of the periosteum effects the strength of bone and hence has a role in fracture prevention. Methods: 40 immature porcine metacarpal bones were stripped off all soft tissue coverings apart from the periosteum. 20 of these were completely stripped of their periosteal coverings whilst the remaining 20 retained it. The bones were then placed on support bars, either along the diaphysis or at the growth plates. They were then subjected to 3 point bending tests until failure via controlled relative displacement by a descending plunger. The forces and fracture patterns generated were collected and compared. Results: With the support bars along the diaphysis, we found a statistically significant amount of force was needed to fracture the bones with the intact periosteum compared to the periosteal stripped group (p < 0.05). In the presence of the periosteum, the fragments were less displaced compared to the periosteal stripped group, being held together by a ‘periosteal bridge’. With the support bars at the growth plates, failure occurred at the metaphyseal–diaphyseal region in all cases. More force was required to cause fracture within the periosteal preserved group however this was not statistical significant. The ‘periosteal bridge’ was again noted. Discussion: We can conclude that the periosteum plays an important biomechanical role in increasing diaphyseal strength. It appears to act as a shock absorber, increasing the biomechanical capabilities of bone to withstand fracture. The ‘periosteal bridge’ reduces displacement of fragments and may accelerate the healing process. This is further evidence to support minimisation of periosteal damage during operative procedures. http://dx.doi.org/10.1016/j.injury.2012.07.226 [1B.5] Bone toxicity and inhibition of bone healing by combination and high doses of antibiotics: An in vitro study I. Pountos ∗ , T. Georgouli, K. Henshaw, H. Bird, P.V. Giannoudis Academic Department of Trauma & Orthopaedics, University of Leeds, United Kingdom Aim: The aim of this study was three-fold. Firstly, to investigate the effect of a wide range of concentrations of vancomycin and gentamycin on the proliferation and osteogenic differentiation of mesenchymal stem cells (MSCs). Secondly, to assess the effect of the expected peak plasma concentrations of benzylpenicillin (penicillin G), flucloxacillin, cefuroxime and metronidazole on MSC proliferation and osteogenesis and thirdly to investigate if combinations of the above antibiotic drugs have a negative impact on the aforementioned biological properties of MSC’s. Materials and methods: Trabecular bone was obtained from 10 patients (6 males), with a mean age of 36 (18–72) suffering from long bone fractures. Mesenchymal Stem Cells (MSCs) were isolated by enzymatic digestion and the cells were cultured till passage 3 (P3). Functional assays on proliferation and osteogenic differentiation were performed under the influence of different concentrations of the studied antibiotics.
Results: Vancomycin at a concentration of 200 g/ml and higher inhibited both MSC proliferation and osteogenic differentiation. Gentamycin inhibited MSC proliferation at concentrations of 75 g/ml and higher while alkaline phosphatise activity was decreased in all concentrations except at the 25 g/ml. In isolation, benzylpenicillin, flucloxacillin, cefuroxime and metronidazole at their peak plasma concentrations did not affect the proliferation of MSCs. However the combination of benzylpenicillin, flucloxacillin and metronidazole found to inhibit the proliferation and calcium production by the cells. Conclusion: Antibiotics used parenterally at their expected peak plasma concentrations found to have no effect on MSCs ability to proliferate and differentiate towards osteogenic lineage. Nonetheless, higher plasma concentrations and combinations of different formulations can have detrimental effects on bone physiology and bone healing. http://dx.doi.org/10.1016/j.injury.2012.07.227 [1B.6] Effectiveness of antibiotic-laden synthetic bone graft materials: In vitro characterisation A. Al Khudairy 1,2,∗ , J.P. Phelan 2 , S.P. Hudson 2 , O. O’Donovan 2 , R. Galvin 1 , J.F. Quinlan 2 , J. O’Dwyer 2 1 2
Royal College of Surgeons, Ireland Waterford Institute of Technology, Ireland
The role of local antibiotic delivery becomes increasingly important in the treatment of open fractures and chronic osteomyelitis. There is an increase in the trend of using biodegradable carriers because of their effectiveness and safety. This study aims to assess the antibiotic elution characteristics from CaSO4 and CaSO4 /TCP synthetic bone graft materials (SBGM) and to investigate the influence of antibiotic addition on the microstructure and mechanical properties of the carrier. The effect of drying on mechanical properties of the carriers and antibiotics effectiveness in selected samples were also investigated. This was an in vitro non-randomised controlled study with a pilot component. Gentamicin and vancomycin were added to CaSO4 and CaSO4 /TCP SBGM in 10% (w/w). Elution characteristics after immersion in 10 ml PBS were studied over 4 weeks and gentamicin-loaded SBGM were further studied after immersion in 2 ml PBS and assayed for antibiotic presence. Microstructural characterisation was studied using Scanning Electron Microscopy (SEM) while solid state NMR analysed the chemical structures of antibiotics upon incorporation in SBGM and before and after immersion in PBS. The effect of drying on the mechanical properties of the antibiotic-free and antibiotic-loaded grafts was also investigated. Both CaSO4 and CaSO4 /TCP carriers exhibited a gradual release of vancomycin over 14 days and a burst release of gentamicin. Gentamicin elution in a reduced volume of 2 ml PBS showed a burst release over 3 days and trace amount up to 21. Antibiotics addition delayed the setting time and impaired the mechanical properties of SBGMs whilst drying improved their structural integrity. ssNMR did not detect any structural changes in the antibiotics and microbiology results were inconclusive. In conclusion, vancomycin follows a gradual release pattern from both carriers while gentamicin follows a burst release pattern. Antibiotic addition delays setting time and impairs the mechanical properties of SBGMs. http://dx.doi.org/10.1016/j.injury.2012.07.228
Abstracts / Injury Extra 43 (2013) 71–127
[1B.4] The biomechanical role of the periosteum in fracture prevention P. Pastides ∗ , I. Khan, M. Jones, P. Theobald Cardiff University School of Engineering, United Kingdom Aim: The periosteum has a well recognised role in osteogenesis and as a source of stem cells. However the mechanical properties of the periosteum and its role in fracture prevention are a neglected domain. The aim of this study was to evaluate whether the presence or not of the periosteum effects the strength of bone and hence has a role in fracture prevention. Methods: 40 immature porcine metacarpal bones were stripped off all soft tissue coverings apart from the periosteum. 20 of these were completely stripped of their periosteal coverings whilst the remaining 20 retained it. The bones were then placed on support bars, either along the diaphysis or at the growth plates. They were then subjected to 3 point bending tests until failure via controlled relative displacement by a descending plunger. The forces and fracture patterns generated were collected and compared. Results: With the support bars along the diaphysis, we found a statistically significant amount of force was needed to fracture the bones with the intact periosteum compared to the periosteal stripped group (p < 0.05). In the presence of the periosteum, the fragments were less displaced compared to the periosteal stripped group, being held together by a ‘periosteal bridge’. With the support bars at the growth plates, failure occurred at the metaphyseal–diaphyseal region in all cases. More force was required to cause fracture within the periosteal preserved group however this was not statistical significant. The ‘periosteal bridge’ was again noted. Discussion: We can conclude that the periosteum plays an important biomechanical role in increasing diaphyseal strength. It appears to act as a shock absorber, increasing the biomechanical capabilities of bone to withstand fracture. The ‘periosteal bridge’ reduces displacement of fragments and may accelerate the healing process. This is further evidence to support minimisation of periosteal damage during operative procedures. http://dx.doi.org/10.1016/j.injury.2012.07.226 [1B.5] Bone toxicity and inhibition of bone healing by combination and high doses of antibiotics: An in vitro study I. Pountos ∗ , T. Georgouli, K. Henshaw, H. Bird, P.V. Giannoudis Academic Department of Trauma & Orthopaedics, University of Leeds, United Kingdom Aim: The aim of this study was three-fold. Firstly, to investigate the effect of a wide range of concentrations of vancomycin and gentamycin on the proliferation and osteogenic differentiation of mesenchymal stem cells (MSCs). Secondly, to assess the effect of the expected peak plasma concentrations of benzylpenicillin (penicillin G), flucloxacillin, cefuroxime and metronidazole on MSC proliferation and osteogenesis and thirdly to investigate if combinations of the above antibiotic drugs have a negative impact on the aforementioned biological properties of MSC’s. Materials and methods: Trabecular bone was obtained from 10 patients (6 males), with a mean age of 36 (18–72) suffering from long bone fractures. Mesenchymal Stem Cells (MSCs) were isolated by enzymatic digestion and the cells were cultured till passage 3 (P3). Functional assays on proliferation and osteogenic differentiation were performed under the influence of different concentrations of the studied antibiotics.
Results: Vancomycin at a concentration of 200 g/ml and higher inhibited both MSC proliferation and osteogenic differentiation. Gentamycin inhibited MSC proliferation at concentrations of 75 g/ml and higher while alkaline phosphatise activity was decreased in all concentrations except at the 25 g/ml. In isolation, benzylpenicillin, flucloxacillin, cefuroxime and metronidazole at their peak plasma concentrations did not affect the proliferation of MSCs. However the combination of benzylpenicillin, flucloxacillin and metronidazole found to inhibit the proliferation and calcium production by the cells. Conclusion: Antibiotics used parenterally at their expected peak plasma concentrations found to have no effect on MSCs ability to proliferate and differentiate towards osteogenic lineage. Nonetheless, higher plasma concentrations and combinations of different formulations can have detrimental effects on bone physiology and bone healing. http://dx.doi.org/10.1016/j.injury.2012.07.227 [1B.6] Effectiveness of antibiotic-laden synthetic bone graft materials: In vitro characterisation A. Al Khudairy 1,2,∗ , J.P. Phelan 2 , S.P. Hudson 2 , O. O’Donovan 2 , R. Galvin 1 , J.F. Quinlan 2 , J. O’Dwyer 2 1 2
Royal College of Surgeons, Ireland Waterford Institute of Technology, Ireland
The role of local antibiotic delivery becomes increasingly important in the treatment of open fractures and chronic osteomyelitis. There is an increase in the trend of using biodegradable carriers because of their effectiveness and safety. This study aims to assess the antibiotic elution characteristics from CaSO4 and CaSO4 /TCP synthetic bone graft materials (SBGM) and to investigate the influence of antibiotic addition on the microstructure and mechanical properties of the carrier. The effect of drying on mechanical properties of the carriers and antibiotics effectiveness in selected samples were also investigated. This was an in vitro non-randomised controlled study with a pilot component. Gentamicin and vancomycin were added to CaSO4 and CaSO4 /TCP SBGM in 10% (w/w). Elution characteristics after immersion in 10 ml PBS were studied over 4 weeks and gentamicin-loaded SBGM were further studied after immersion in 2 ml PBS and assayed for antibiotic presence. Microstructural characterisation was studied using Scanning Electron Microscopy (SEM) while solid state NMR analysed the chemical structures of antibiotics upon incorporation in SBGM and before and after immersion in PBS. The effect of drying on the mechanical properties of the antibiotic-free and antibiotic-loaded grafts was also investigated. Both CaSO4 and CaSO4 /TCP carriers exhibited a gradual release of vancomycin over 14 days and a burst release of gentamicin. Gentamicin elution in a reduced volume of 2 ml PBS showed a burst release over 3 days and trace amount up to 21. Antibiotics addition delayed the setting time and impaired the mechanical properties of SBGMs whilst drying improved their structural integrity. ssNMR did not detect any structural changes in the antibiotics and microbiology results were inconclusive. In conclusion, vancomycin follows a gradual release pattern from both carriers while gentamicin follows a burst release pattern. Antibiotic addition delays setting time and impairs the mechanical properties of SBGMs. http://dx.doi.org/10.1016/j.injury.2012.07.228