@article{DiermeierSindersbergerAngeleetal., author = {Diermeier, Andreas and Sindersberger, Dirk and Angele, Peter and Kujat, Richard and Monkman, Gareth J.}, title = {Sensor system for use with low intensity pulsed ultrasound}, series = {Sensor review}, volume = {39}, journal = {Sensor review}, number = {6}, publisher = {Emerald}, issn = {0260-2288}, doi = {10.1108/SR-11-2018-0304}, pages = {828 -- 834}, abstract = {Purpose Ultrasound is a well-established technology in medical science, though many of the conventional measurement systems (hydrophones and radiation force balances [RFBs]) often lack accuracy and tend to be expensive. This is a significant problem where sensors must be considered to be "disposable" because they inevitably come into contact with biological fluids and expense increases dramatically in cases where a large number of sensors in array form are required. This is inevitably the case where ultrasound is to be used for the in vitro growth stimulation of a large plurality of biological samples in tissue engineering. Traditionally only a single excitation frequency is used (typically 1.5 MHz), but future research demands a larger choice of wavelengths for which a single broadband measurement transducer is desirable. Furthermore, because of implementation conditions there can also be large discrepancies between measurements. The purpose of this paper deals with a very cost-effective alternative to expensive RFBs and hydrophones. Design/methodology/approach Utilization of cost-effective piezoelectric elements as broadband sensors. Findings Very effective results with equivalent (if not better) accuracy than expensive alternatives. Originality/value This paper concentrates on how very cost-effective piezoelectric ultrasound transducers can be implemented as sensors for ultrasound power measurements with accuracy as good, if not better than those achievable using radiation force balances or hydrophones.}, language = {en} } @article{ZellnerHierlMuelleretal., author = {Zellner, Johannes and Hierl, Katja and Mueller, Michael and Pfeifer, Christian and Berner, Arne and Dienstknecht, Thomas and Krutsch, Werner and Geis, Sebastian and Gehmert, Sebastian and Kujat, Richard and Dendorfer, Sebastian and Prantl, Lukas and Nerlich, Michael and Angele, Peter}, title = {Stem cell-based tissue-engineering for treatment of meniscal tears in the avascular zone}, series = {Journal of Biomedical Materials Research Part B Applied Biomaterials}, volume = {101}, journal = {Journal of Biomedical Materials Research Part B Applied Biomaterials}, number = {7}, editor = {Gilbert, Jeremy}, doi = {10.1002/jbm.b.32922}, pages = {1133 -- 1142}, abstract = {Meniscal tears in the avascular zone have a poor self-healing potential, however partial meniscectomy predisposes the knee for early osteoarthritis. Tissue engineering with mesenchymal stem cells and a hyaluronan collagen based scaffold is a promising approach to repair meniscal tears in the avascular zone. 4 mm longitudinal meniscal tears in the avascular zone of lateral menisci of New Zealand White Rabbits were performed. The defect was left empty, sutured with a 5-0 suture or filled with a hyaluronan/collagen composite matrix without cells, with platelet rich plasma or with autologous mesenchymal stem cells. Matrices with stem cells were in part precultured in chondrogenic medium for 14 days prior to the implantation. Menisci were harvested at 6 and 12 weeks. The developed repair tissue was analyzed macroscopically, histologically and biomechanically. Untreated defects, defects treated with suture alone, with cell-free or with platelet rich plasma seeded implants showed a muted fibrous healing response. The implantation of stem cell-matrix constructs initiated fibrocartilage-like repair tissue, with better integration and biomechanical properties in the precultured stem cell-matrix group. A hyaluronan-collagen based composite scaffold seeded with mesenchymal stem cells is more effective in the repair avascular meniscal tear with stable meniscus-like tissue and to restore the native meniscus.}, subject = {Meniskusschaden}, language = {en} } @article{EnglertAngeleFierlbecketal., author = {Englert, Carsten and Angele, Peter and Fierlbeck, J. and Dendorfer, Sebastian and Schubert, T. and M{\"u}ller, R. and Lienhard, S. and Zellner, J. and Nerlich, Michael and Neumann, Carsten}, title = {Conductive bone substitute material with variable antibiotic delivery}, series = {Der Unfallchirurg}, volume = {110}, journal = {Der Unfallchirurg}, number = {5}, publisher = {Springer}, doi = {10.1007/s00113-007-1229-3}, pages = {408 -- 413}, abstract = {A new bone substitute, consisting of hydroxylapatite and calcium sulphate, was prepared in two formulations and analysed for its mechanical strength and antibiotic elution.The bone substitute PerOssal has osteoconductive and degradable properties. The material has a built-in capillary structure, which results in an immediate fluid uptake. Antibiotics absorbed to the bone substitute resulted in a prolonged release rate. Mechanical strength was investigated by an unconfined compression test up to failure under both wet and dry conditions for both formulations of the bone substitute. Antibiotic release was analysed microbiologically for two antibiotics, vancomycin and gentamicin, over an elution period of 10 days using the agar diffusion method.The drug release analysis resulted in a prolonged release rate of both antibiotics over 10 days. In vitro the amount of gentamicin and vancomycin eluted at day 10. From one pellet still exceeded the minimal inhibitory concentration of most aetiologically important pathogens. Formulation two of the present bone substitute is significantly harder in both wet and dry conditions when compared to formulation one. Both formulations lose strength in the wet condition relative to their performance in the dry condition. However, formulation two is as hard under wet conditions as formulation one is when dry.PerOssal is a suitable new degradable osteoconductive bone substitute that can be loaded with antibiotic solutions, which are released in effective doses over 10 days. The mechanical strength of PerOssal is sufficient to support cancellous bone defects in non-weight-bearing areas or in combination with osteosynthesis.}, subject = {Knochenersatz}, language = {en} } @inproceedings{PenzkoferGrechenigKujatetal., author = {Penzkofer, Rainer and Grechenig, S. and Kujat, Richard and Angele, Peter and Dendorfer, Sebastian}, title = {Biomechanical comparison of the dorsal femur condyles and the iliac crest in terms of failure behavior}, series = {XXV Congress of the International Society of Biomechanics, Glasgow, UK, 12th-16th July 2015}, booktitle = {XXV Congress of the International Society of Biomechanics, Glasgow, UK, 12th-16th July 2015}, language = {en} }