Browse Articles

The prevalence of soft tissue graft in anterior cruciate ligament (ACL) reconstruction, as well as the preference for bioabsorbable fixation continues to grow in clinical practice. This paper presents one complication related to biocomposite screw fixation used in ACL reconstruction found in clinical practice associated with a retrieval analysis of a broken biocomposite interference screw made by PLLA-HA (75% PLLA, 25% HA), arthroscopically removed from the tibial site at 8 months after ACL reconstruction with soft tissue autograft in a young patient. The fragment of broken screw was analysed in terms of surface and structural analysis following an established implant retrieval protocol. The retrieved implant surface shows cracks and breakdown signs characteristic to the final phase of resorption but incomplete probably due to biomechanical stress. The present study is important since it is one of the few cases recorded for both a composite implant as well as for an early complication, supporting the idea that the breakage of biocomposite screws should be considered during ACL reconstruction. Keywords: biocomposite screw, biodegradable polymer, ACL reconstruction, retrieval analysis, SEM

The paper presents the results obtained by the authors for the mathematical modeling of the mechanical behaviour variation of the composite material with polymeric or elastomeric matrix and reinforced with protein fibers (CFP), depending on the concentration of the reinforced material. The mathematical model of the main mechanical properties of a composite material allows optimal approximation variants of material that is as close to that required in a particular field. The method proposed in this article is generally applied to the composite materials and is valid not only for the case of mechanical properties dependence of a single parameter (the concentration of a constituent) but in the case of dependence on several parameters, case in which the possibilities of achieving a favourable variant are much larger and more accurate. In the category of free parameters of the mathematical model can enter all the constituents’ concentrations, but, in addition, also important are the technological parameters: temperature in the manufacturing process, the reinforced material granulation, the degree of stirring, pressure, etc. Keywords: CFP, mathematical model, variation, mechanical properties, optimal variants

This paper presents a method to improve the performance of glass fiber processing by cutting of the fiber reinforced polymeric materials based on the application of ultrasonic vibrations on the cutting tool. General conditions of the process are established and, based on the analysis of the processing mechanism, the authors provided the fundamental condition for the selection of the cutting speed values in the case of ultrasonically assisted cutting of glass fiber reinforced polymeric materials. The paper also presents the theoretical foundations of rising the macrogeometric accuracy of ultrasonically assisted cutting in the case example of the universal grip turning. Keywords: polymeric materials, ultrasonic cutting, glass fiber

The elements of afferent pedicle of the liver have a segmental distribution to the liver parenchyma. Divergence part of the hepatic portal vein is the main element of intraparenchymatous spatial distribution vasculo-ductal systems. On 500 divergence (intraparenchimal) portions of of hepatic portal vein (125 pieces of liver corrosion casts, 125 ultrasound images, 125 images of MDCT angiography and 125 images of MR angiography), it was highlighted a number of six morphological types of intraparenchymatous part of hepatic portal vein, which are presented as follows. Symmetric bifurcation (standard portal vein anatomy) (Type I - 76.2%) in which the main portal vein trunk divides into right and left portal branches. Trifurcation, (Type II - 10.4%) in: the left branch, the (right) anterior branch, and the (right) posterior branch. Quadrifurcation, (Type III - 0.2%) in: anterior and posterior branches in the right part, and lateral and medial branches in the left part. Asymmetric bifurcation, (Type IV - 7.4%) in which the (right) posterior branch is the first branch of the main portal vein trunk Asymmetric bifurcation of the right branch, (Type V - 4.4%) in which the branch for segment V or VIII (anterior branch) is the first branch of the right branch. Asymmetric bifurcation of the right branch, (Type VI - 1.4%) in which the branch for segment VI or VII (posterior branch) is the first branch of the right branch. Knowledge of these aspects is important both to investigate morphological imaging, and in performing partial resection and liver transplantation. Keywords: hepatic portal vein branches; morphological types; corrosion casts; ultrasound images; MDCT angiography; MR angiography; clinical and surgical inplications

Dislocation of the humeral head is a very common traumatic disorder of the shoulder. Most of the time the dislocation is antero-inferior, which causes a detachment of the antero-inferior capsulolabral complex. This injury predisposes to redislocation, thus requiring surgical fixation, the so called Bankart repair, during which the labrum is reinserted to the glenoid cavity. The aim of our study is to follow the particularities of the outcome after the arthroscopic Bankart repair, accomplished with two different types of suture anchors, bioabsorbable and metallic anchors. Considering the surgical technique there is no difference between the implantation of the two types of suture anchors. There was no significant difference in the rehabilitation outcome between the studied groups. Our results correspond with the findings of other research papers. The arthroscopic management of Bankart lesion is less invasive, which shortens the rehabilitation period. The main disadvantages of metallic suture anchors are the loosening of the anchor and the revision surgery, which also can be complicated. Keywords: Bankart lesion, shoulder arthroscopy, shoulder recovery, suture anchors

The orthodontic appliances can be built in a great diversity of resin that could be classified by one of the criteria, in thermoplastic and thermo set. This paper has as purpose to compare three resins used for orthodontic appliances, one thermoplastic and two thermo set –Biocryl C (Scheu Biostar), Orthocryl (Dentaurum), Orthoplast (Vertex Dental) – from the mechanical properties respect such as surface hardness and indentation elastic modulus. We tested six specimens; two from each type of these resins. Each specimen was fixed on a support and they were tested with Nano Indenter G200 from Keysight (Agilent). We obtained as a result that the thermoplastic material has a lower elastic modulus than the other thermo set. Keywords: thermoplastic resin, thermo set resin, elastic modulus, hardness, nanoindentation

Among the reinforced composites the ones with fabric reinforcements are studied due to of their excellent properties. This type of materials allows the control of properties due to the placement of fabrics in the reinforcement structure. This study is carried out to identify the effect of reinforcement sheets orientation on the mechanical properties of composites with epoxy matrix and the effect of modified matrix on the same properties. Four types of fabrics had been used as reinforcements for materials each material being reinforced with a single type of fabric excepting the medial sheet which is the same for all the materials. Both three point bending tests and compressive tests were performed perpendicular on the reinforcement plane. Keywords: epoxy resin, modified epoxy, fabrics, bending tests, compressive tests

The lower jaw is frequently exposed to fracture, by accidents, violence, accidental falls, sports injuries, pathological fracture, etc. We have investigated the behaviour of mandibular bone in a particular clinical case of fracture, in which we experimentally applied two osteosynthesis plates and analyzed the effects of occlusal loading on the fracture line by finite element method. We observed that in this case, maximum deformations occur in the mandibular condyles and the maximum and minimum normal stresses occur in the osteosynthesis plates. Even if bite and mastication determine important efforts on osteosynthesis plates, titanium alloy supports well these loads, and, as an important aspect, the bone parts during healing are not the object of excessive mechanical loads. Keywords: FEA, mastication, osteosynthesis, fracture, mandible

In this paper is presented an experimental, theoretical and numerical study about the use of a biodegradable composite material in the manufacturing process of the suspension elements for plane sieves used in mills from bakery industry. The material was obtained by reinforcing an unsaturated polyester resin with cotton fabric. Tensile tests were performed for materials having one, three, five and seven layers of cotton fabric and the optimum solution was chosen. The material properties, obtained from the experimental tests, were used in a finite element model realized for the strength calculus of the suspension element. The numerical results were validated analytically. The study confirms that the biodegradable materials can be used for manufacturing of the suspension elements of a plansifter and can be adapted for other parts or industrial structures. Keywords: sifting, biodegradable material, polyester resin, finite element, cotton

Computerized reconstruction of anatomical structures is becoming very useful for developing anatomical teaching modules and animations. The first computer-aided 3D reconstruction was achieved in 1965 by Glaser and Van der Loos. With the improvements in computer hardware and software tools, computerized modeling of anatomical structures has become very useful for visualizing complex 3D forms. Three-dimensional visualization of various microanatomic structures using special preparation and staining methods is important. Although databases exist consisting of serial sections derived from frozen cadaver material, plastination represents an alternate method for developing anatomical data useful for computerized reconstruction. Plastination is used as an excellent tool for studying different anatomical and clinical questions. The sheet plastination technique is unique because it offers the possibility to produce transparent slices series, which can easily be processed morphometrically. A female pelvis was obtained, plastinated, sectioned and subject to 3D computerized reconstruction using WinSURF modeling system (SURFdriver Software). Qualitative observations revealed that the morphological features of the model were consistent with those displayed by typical cadaveric specimens. Morphometric analysis indicated that the model did not significantly differ from a sample of cadaveric specimens. This data supports the use of plastinates for generating tissues sections useful for 3D computerized modeling. Keywords: plastination, 3D reconstruction, anatomy, female pelvis, urinary bladder, uterus