Bio-Medical Materials and Engineering - Volume 14, issue 2

Authors: Zieren, Jürgen | Neuss, Heiko | Paul, Marco | Müller, Joachim

Article Type: Research Article

Abstract: Background: Nowadays the surgical treatment of abdominal hernias includes the use of synthetic meshes in most cases. Due to chronic foreign body reactions, however, the most commonly used polypropylene meshes can lead to material hardening and recurrent hernias. As a proven cruciate ligament replacement polyethylene terephthalate (KoSa hochfest® ) showed only little foreign body reactions and provided excellent clinical outcomes. In an animal trial it was therefore tested as mesh implant for hernia treatment and compared with Prolene® . Material and method: The study was carried out in 12 mini‐pigs. 10×10 cm of the musculofascial abdominal layer was resected, …the peritoneum was preserved. A 15×15 cm synthetic mesh was implanted in sublay‐technique (either KoSa hochfest® , Telos GmbH, Marburg, Germany or Prolene® , Ethicon, Norderstedt, Germany), mainly to test for chronic foreign body reactions. An independent pathologist tested the mesh size and foreign body reaction at 2 and 6 months, analysing the number of foreign body giant cells. Results: No significant differences in mesh size were observed, neither between the compared groups nor with respect to the time periods. Compared to KoSa hochfest® the foreign body reaction was significantly stronger in the Prolene® implants, both at 2 and at 6 months (number of foreign body giant cells at 2 months: Prolene® /KoSa hochfest® : 2.2±0.4/0.8±0.2, at 6 months: 4.6±1.3/1.1±0.5). In contrast to KoSa hochfest® , Prolene® still showed significant foreign body reactions at 6 months as well as calcifications of all samples. Conclusion: The animal trials revealed that due to its high biocompatibility and little foreign body reaction KoSa hochfest® is a promising implant for the treatment of hernias. Show more

Citation: Bio-Medical Materials and Engineering, vol. 14, no. 2, pp. 127-132, 2004

Authors: Hedia, H.S. | Mahmoud, Nemat‐Alla

Article Type: Research Article

Abstract: The continuous increase of man's life span, and the growing confidence in using artificial materials inside the human body necessities introducing more effective prosthesis and implant materials. However, no artificial implant has biomechanical properties equivalent to the original tissue. Recently, titanium and bioceramic materials, such as hydroxyapatite are extensively used as fabrication materials for dental implant due to their high compatibility with hard tissue and living bone. Titanium has reasonable stiffness and strength while hydroxyapatite has low stiffness, low strength and high ability to reach full integration with living bone. In order to obtain good dental implantation of the biomaterial; …full integration of the implant with living bone should be satisfied. Minimum stresses in the implant and the bone must be achieved to increase the life of the implant and prevent bone resorption. Therefore, the aim of the current investigation is to design an implant made from functionally graded material (FGM) to achieve the above advantages. The finite element method and optimization technique are used to reach the required implant design. The optimal materials of the FGM dental implant are found to be hydroxyapatite/titanium. The investigations have shown that the maximum stress in the bone for the hydroxyapatite/titanium FGM implant has been reduced by about 22% and 28% compared to currently used titanium and stainless steel dental implants, respectively. Show more

Keywords: von Mises stress, dental implant, functionally graded material (FGM), finite element, optimization

Citation: Bio-Medical Materials and Engineering, vol. 14, no. 2, pp. 133-143, 2004

Authors: Hu, X.Q. | Isaac, G.H. | Fisher, J.

Article Type: Research Article

Abstract: In metal on metal hip prostheses, the contact mechanics can influence the lubrication and wear rate. In particular, during the bedding‐in wear, the contact area gradually increases to an optimal value, and the wear rate reduces as the contact stress reduces and the lubrication conditions improve. Geometrical designs that reduce the volume of bedding‐in wear as the optimal contact area develops are preferable. The objective of this study was to analyse the wear volume as a function of contact area during the bedding‐in period, with the aim of identifying geometrical design configurations that give lower bedding‐in wear. As the radial …clearance was reduced, the bedding‐in wear volume to reach an optimal contact area also reduced. For a fixed radial clearance, increasing the head diameter also reduced the bedding‐in wear volume. Show more

Keywords: Hip prostheses, metal on metal, contact area, wear

Citation: Bio-Medical Materials and Engineering, vol. 14, no. 2, pp. 145-149, 2004

Authors: Dargahi, Javad | Najarian, Siamak

Article Type: Research Article

Abstract: This paper reports on the design, fabrication, testing, and modeling of a novel semiconductor microstrain gauge endoscopic tactile sensor. The designed assembly consists of two semiconductor microstrain gauge sensors, which are positioned at the back‐face of a prototype endoscopic grasper. The sensor can measure, with reasonable accuracy, the magnitude and the position of an applied load on the grasper. The in‐house electrical amplification system for the microstrain gauges is also designed, fabricated, and tested. The intensity of the magnitude of the applied force to the endoscopic grasper can be visually seen on a light emitting diode (LED) device. In total, …20 different force magnitudes, from 0.5 to 10 N with an increment of 0.5 N, for 7 different locations of the endoscopic grasper were tested experimentally. The sensor exhibits high force sensitivity, large dynamic range, and good linearity. It is insulated and can operate safely in wet environments. A 3‐dimensional finite element modeling (FEM) is used to predict the behavior of the designed system under various loading conditions. There is a good correlation between the theoretical predictions of the force magnitudes and their points of application, which are computed by FEM, and experimentally obtained results. Potentially, the miniaturized electronic device could be integrated with an endoscope and the complete system could be used in operating rooms. Show more

Keywords: Endoscopy, tactile sensor, FEM, minimally invasive surgery

Citation: Bio-Medical Materials and Engineering, vol. 14, no. 2, pp. 151-166, 2004

Authors: Qiao, Ai Ke | Zeng, Yan Jun | Xu, Xiao Hu

Article Type: Research Article

Abstract: The numerical simulation of the conventional 1‐way bypass graft and the presented 2‐way bypass graft used in the stenosed femoral arteries were completed. Purpose of the present study was to ascertain whether the modified geometry configuration of 2‐way bypass graft could improve the flow conditions of femoral bypass graft. The physiological flows in 1‐way and 2‐way models were simulated with finite element method under the same calculation conditions. Comparisons were made between the hemodynamics of 1‐way and 2‐way models. The results suggested that 2‐way bypass graft could result in more favorable and regular flow conditions than 1‐way bypass graft, and …could decrease the probability of intimal hyperplasia, restenosis and surgery failure in femoral bypass graft. Show more

Keywords: Simulation, bypass graft, restenosis, hemodynamics, intimal hyperplasia

Citation: Bio-Medical Materials and Engineering, vol. 14, no. 2, pp. 167-174, 2004

Authors: Li, Fangzhen | Hu, Kuanghu | Su, Wanfang | Li, Shuyu | Cai, Nian | Huang, Zhiying | Hu, Yingxiong

Article Type: Research Article

Abstract: In this paper the recognition of Small Cell Carcinoma (SCC) is studied. For each type we select 128 samples for training, and randomly measure 200 cells in each sample. We introduce multi‐scale morphology based on centroid coordinates to extract the boundaries of nuclei and obtain feature images of nuclei. The features of lung cancer cells are described by morphological and colorimetrical parameters, which is valuable to recognize SCC. Then the architecture of self‐organizing feature mapping (SOFM) neural network is studied for recognition of SCC. The weights of the network are adjusted by self‐organizing competition, and finally inputted patterns are classified. …This algorithm has the advantage of parallelism and fast‐convergence, and may simplify the analysis of SCC. Clinical experiment results show that the correctness ratio of this system may reach 95.3% while recognizing lung cancer cell types. Our work is significant to the pathological researches of lung cancer, assistant clinic diagnosis, and assessment of therapeutic effects. Meanwhile a software system named as SCC.LUNG is established for automatic analysis. Show more

Keywords: Recognition of SCC, SOFM, neural network, mathematical morphology, colorimetry

Citation: Bio-Medical Materials and Engineering, vol. 14, no. 2, pp. 175-184, 2004

Authors: Lee, Jin Soo | Chae, Gang Soo | Kim, Moon Suk | Cho, Sun Hang | Lee, Hai Bang | Khang, Gilson

Article Type: Research Article

Abstract: Biodegradable polymers have been extensively investigated because of regulating drug release rate easily, obviating the need to remove the device, and good biocompatibility. Among the biodegradable polymers currently under investigation, poly(D,L‐lactide‐co‐glycolide) (PLGA) copolymers are the most widely studied because of their long history of safe clinical use as drug carrier. 50 :50 PLGA was used as a model degradable polymer in this study to investigate the degradation behaviour on drug release from bulk degradable polymers in vitro. 5‐fluorouracil (5‐FU) was used as a model drug. Molecular weight change, residual mass, water uptake, morphological change of PLGA wafers, and pH of release …test medium were characterized to investigate the effect of polymer degradation on drug release. The release rate of 5‐FU increased with the increase of 5‐FU loading amount and the release profiles of 5‐FU irrespective of 5‐FU loading amount followed near first order release kinetics. Show more

Citation: Bio-Medical Materials and Engineering, vol. 14, no. 2, pp. 185-192, 2004

Authors: Wei, Hung‐Wen | Chung, Ming‐Yen | WS Huang, Vincent | Cheng, Cheng‐Kung

Article Type: Research Article

Abstract: The hip stem design based upon X‐ray films requires sufficient information in order to customize for the patient. If the errors are resulted from rotating angles, more X‐ray films may carry out the solution. The present study aimed to realize the improvement of multiple X‐ray films for hip stem design. Eight X‐ray films were taken from a volunteer. The characteristic length of X‐ray film was input into cosine function to derive the relative rotating angle of each X‐ray film. The combinations of 2, 4, 6, and 8 X‐ray films that included true AP view and lateral view were obtained to …construct the corresponding stem. CT images were used to construct femur and stem model to verify the rotating angle of femur in each X‐ray film. A quantitative comparison was made between the hip stems for the fill ratio, fit gap and contact area. The results showed that the markers on the body surface would result in error and were unable to provide reference to the rotating angle of femur. The contact area and fill ratio of the stems designed by 6 or 8 X‐ray films would get closer to that by CT images. It is concluded that the rotation of the femur could be determined from the length of femoral neck as well as the distance between the tips of medial and lateral condyles. The use of 6 or more X‐ray films for custom‐made hip stem as a source of design is recommended in this study. Show more

Keywords: Custom hip stem, X‐ray film, femur rotation

Citation: Bio-Medical Materials and Engineering, vol. 14, no. 2, pp. 193-202, 2004

Authors: Nambu, Satya Narasimha | Lewis, Gladius

Article Type: Research Article

Abstract: The finite element analysis method was used to determine the stresses in all sections of a three‐dimensional model of the proximal section of the human knee joint into which was cemented two parts of a total knee joint replacement (the tibial tray and the tibial baseplate), fully constrained at its distal end, and subjected to a total compressive joint force of 2 kN acting on points corresponding to the condyles. When the mean values of these stresses were computed for all sections of the model, two important trends were seen. First, when the load was applied dynamically, the stresses were …between 1 and 20% different than when it acted quasi‐statically. Second, regardless of how the load was applied, the stresses when the tibial baseplate was considered fabricated from ultra‐high‐molecular‐weight polyethylene ranged from about 40% lower to about 320% higher compared to when Ti–13Nb–13Zr alloy was used. The significance of these findings as well as the limitations of the study are discussed. Show more

Keywords: Finite element analysis, total knee joint replacement, maximum principal stress, von Mises stress

Citation: Bio-Medical Materials and Engineering, vol. 14, no. 2, pp. 203-217, 2004

Authors: Fujie, Hiromichi | Miyagaki, Junpei | Terrier, Alexandre | Rakotomanana, Lalao | Leyvraz, Pierre‐Francois | Hayashi, Kozaburo

Article Type: Research Article

Abstract: To study bone adaptation to detraining in growing rats, nine weeks‐old immature female Wistar rats (n=110) were subjected to treadmill running programs (30 or 60 minutes‐a‐day) for up to 15 weeks, followed by unrestricted cage activities for the subsequent 15 weeks. The results revealed that (1) the cross‐sectional area and mechanical properties of the midshaft bone significantly increased in response to running exercise, (2) its structural properties remained unchanged after the cessation of exercise, whereas the material properties returned to control level at a relatively early stage, (3) in the metaphysis, cortical bone area remained unchanged but trabecular bone area …decreased in response to running exercise, (4) both areas slightly increased after the cessation of exercise, and (5) the changes in the mechanical properties and morphology of bone depended upon the repetition number and/or the duration of exercise, and were larger with longer duration of exercise. Show more

Keywords: Bone remodeling, cortical and trabecular bones, mechanical property, morphology, running exercise, detraining, rat

Citation: Bio-Medical Materials and Engineering, vol. 14, no. 2, pp. 219-233, 2004