Bio-Medical Materials and Engineering - Volume 3, issue 2

Article Type: Other

DOI: 10.3233/BME-1993-3206

Citation: Bio-Medical Materials and Engineering, vol. 3, no. 2, pp. I-II, 1993

Authors: Guglielmino, E. | La Rosa, G. | Leonardi, W. | Longo, G. F.

Article Type: Research Article

Abstract: The mechanical behaviour of the Castaman external fixator was determined using different mounting configurations in a system that simulated a long bone fracture during the formation of the bone callus. The first stage of the study was the determination of the stress-strain characteristics of the system with monolateral mounting. The second stage, the object of this study, is the analysis of the system with bilateral mounting and a comparison between the two configurations of the external fixator examined. Strain gauge analysis was used to determine the strains and stresses in the various elements of the system (fiches and external unit). …Numerical techniques (FEM) were also used in order to confirm the results obtained using the simulation system. The results obtained show clearly the greater stiffness of the bilateral system. Combined bending and compressive stresses are present on both the screws and the external units, and reveal a little asymmetrical behaviour due to the conicity of the screws. Show more

Keywords: external fixators, FEM, strain-gauges

DOI: 10.3233/BME-1993-3201

Citation: Bio-Medical Materials and Engineering, vol. 3, no. 2, pp. 57-65, 1993

Authors: Akai, Masami | Shirasaki, Yoshio | Tateishi, Tetsuya

Article Type: Research Article

Abstract: The purpose of this study was to ana1yze the joint stiffness after immobi1ization in a rat's lower extremity model. Rat knee joints were surgically immobilized in a full flexed position for periods of up to 7 weeks with or without intraarticular intervention. The biomechanical analysis was assessed by measuring the bone-joint-bone sample as a cantilever. Measurement was performed with (a) knee flexion angle with gravity, (b) fast Fourier transform analysis of time-dependent mechanical noise with random frequencies, and (c) dynamic stiffness and loss tangent with sinusoidal vibration at a certain frequency. The results showed that the conventional static mechanical test …could not detect the intraarticular changes of the whole knee joint. The measurement of the viscoelastic properties covering wide frequencies revealed that an accurate change occurred. Show more

Keywords: joint contracture, viscoelastic property, fast Fourier transform, cantilever model

DOI: 10.3233/BME-1993-3202

Citation: Bio-Medical Materials and Engineering, vol. 3, no. 2, pp. 67-73, 1993

Authors: Walsh, W. R. | Guzelsu, N.

Article Type: Research Article

Abstract: Bone tissue is a composite material composed of an inorganic stiff mineral phase embedded in a compliant organic matrix. Similar to other composites, the mechanical properties of bone depend upon the properties, volume fraction, and orientation of its constituents as well as the bonding interactions. Interfacial bonding between the mineral and organic constituents are based, in part, on electrostatic interactions between negatively charged organic domains and positively charged mineral surface. Phosphate and t1uoride ions can alter mineral-organic interfacial causing a permutation in the mechanical properties. Partial debonding between the mineral and organic constituents of bone may play an important role …in the mechanical properties of aged and diseased bone. The present study examines the effects of phosphate and t1uoride ion treatment on the compression properties of cortical bone and the reversibility of the effect. Show more

Keywords: cortical bone, mechanical properties, compression, interfacial bonding, fluoride

DOI: 10.3233/BME-1993-3203

Citation: Bio-Medical Materials and Engineering, vol. 3, no. 2, pp. 75-84, 1993

Authors: Kim, Sung S. | Park, Joon B.

Article Type: Research Article

Abstract: A double-layered tube consisting of a porous inner tube and a solid outer tube was used to perfuse isotonic saline solution into blood to prevent blood cell adhesion. Polystyrene/poly(styrene-co-butadiene) (PS/SBR) porous tubes were made using a dipping method. Citrated canine blood was circulated for 30 min with the flow rate of lOO mlImin using an in vitro blood circulation setup which makes nonpulsatile blood flow. Blood cell adhesion in the PS/SBR porous tubes decreased with increased saline perfusion rate regardless of changes in variables such as tube porosities, tube materials, and perfusion materials. The relationship between blood cell adhesion and …perfusion rate was semi-logarithmic. Blood cell adhesion was relatively high in the more porous tube (65% sugar tube), compared to the less porous tube (55% sugar tube) for an identical saline perfusion rate. The blood cell adhesion in the sulfonated PSISBR porous tube was less than that in the nonsulfonated (control) PS/SBR porous tube. The blood cell adhesion was also decreased by citrate perfusion. The results of this study indicates that the saline perfusion method can be used to prevent blood cell adhesion in the blood lines of extracorporeal circulation systems (such as hemodialysis and heart-lung machines) if certain technical problems involving the surface roughness can be resolved. Show more

Keywords: saline perfusion, platelet adhesion, blood cell adhesion, blood compatibility, porous materials, extracorporeal circulation systems, blood lines

DOI: 10.3233/BME-1993-3204

Citation: Bio-Medical Materials and Engineering, vol. 3, no. 2, pp. 85-100, 1993

Authors: Park, Joon B. | Kim, Sung S.

Article Type: Research Article

Abstract: An in vitro experiment under laminar nonpulsatile blood flow and an acute canine ex vivo femoral A-V series shunt experiment were undertaken to investigate the effectiveness of saline perfusion through pores of porous tubes to prevent formation of mural thrombus. PS/SBR porous tubes were used for the in vitro experiment. Commercially obtained ePTFE porous tubes were etched by sodium naphthalenide, and the etched tubes were used for the ex vivo experiment. According to the results of the in vitro experiment, mural thrombus on the surface of the porous tube could be prevented by the saline perfusion. Adhered blood cells …decreased semi-logarithmically with increased perfusion rate (up to 0.022 ml/min-cm2 ) of isotonic saline solution. According to results of the ex vivo experiment, mural thrombus decreased with increased perfusion rate (up to 0.060 ml/min-cm2 ). Show more

Keywords: blood compatibility, saline perfusion, fluid perfusion, thrombosis, ePTFE tubes, sodium naphthalenide

DOI: 10.3233/BME-1993-3205

Citation: Bio-Medical Materials and Engineering, vol. 3, no. 2, pp. 101-116, 1993