Comparison of biomechanical stability of osteosynthesis materials in long bone fractures

Aim To calculate stress and deformation under the force of pressure and bending in the dynamic compression plate (DCP), locking compression plate (LCP), selfdynamisable internal fixator (SIF) and locked intramedullary nail (LIN) in the models of juvidur, beef tibia bone (cadaver) and software of bone model simulator. Methods Juvidur and bone models were used for the experimental study, static tests were performed with SHIMADZU AGS-X tester. CATIA software was used to create a 3D model for the SCA simulator, while software ANSYS to calculate the tension and deformation for compressive and bending forces. Stress and deformation analysis was performed with the use of Finite Element Analysis (FEA). Results Weight coefficients of research methods were different (juvidur=0.3; cadaver=0.5; SCA Simuator=0.2), and weight coefficients of the force of pressure Kp=0.5 and bending forces in one plane K1=0.25 and K2=0.25 in another plane, the overall result on the dilatation of DCP, LCP, LIN and SIF on juvidur and veal cadaver models showed that the first ranking was the LIN with a rank coefficient KU-LIN = 0.0603, followed by the IFM with KU-IFM = 0.0621, DCP with KU-DCP = 0.0826 and LCP with KU-LCP = 0.2264. Conclusion Dilatation size did not exceed 0.2264 mm, hence the implants fulfilled biomechanical conditions for the internal stabilization of bone fractures. Prevalence goes to the locked intra-medullar nailing and Mitković internal fixator in the treatment of diaphyseal, transversal, comminuted fractures in relation to DCP and LCP

Distal tibial pilon fractures (AO/OTA type B, and C) treated with the external skeletal and minimal internal fixation method

Background/Aim. Distal tibial pilon fractures include extra-articular fractures of the tibial metaphysis and the more severe intra-articular tibial pilon fractures. There is no universal method for treating distal tibial pilon fractures. These fractures are treated by means of open reduction, internal fixation (ORIF) and external skeletal fixation. The high rate of soft-tissue complications associated with primary ORIF of pilon fractures led to the use of external skeletal fixation, with limited internal fixation as an alternative technique for definitive management. The aim of this study was to estimate efficacy of distal tibial pilon fratures treatment using the external skeletal and minimal internal fixation method. Methods. We presented a series of 31 operated patients with tibial pilon fractures. The patients were operated on using the method of external skeletal fixation with a minimal internal fixation. According to the AO/OTA classification, 17 patients had type B fracture and 14 patients type C fractures. The rigid external skeletal fixation was transformed into a dynamic external skeletal fixation 6 weeks post-surgery. Results. This retrospective study involved 31 patients with tibial pilon fractures, average age 41.81 (from 21 to 60) years. The average follow-up was 21.86 (from 12 to 48) months. The percentage of union was 90.32%, nonunion 3.22% and malunion 6.45%. The mean to fracture union was 14 (range 12-20) weeks. There were 4 (12.19%) infections around the pins of the external skeletal fixator and one (3.22%) deep infections. The ankle joint arthrosis as a late complication appeared in 4 (12.90%) patients. All arthroses appeared in patients who had type C fractures. The final functional results based on the AOFAS score were excellent in 51.61%, good in 32.25%, average in 12.90% and bad in 3.22% of the patients. Conclusion. External skeletal fixation and minimal internal fixation of distal tibial pilon fractures is a good method for treating all types of inta-articular pilon fractures. In fractures types B and C dynamic external skeletal fixation allows early mobility in the ankle joint. [Projekat Ministarstva nauke Republike Srbije, br. III41017

ANATOMIC AND PHYSIOLOGICAL FEATURES OF DISTAL LOWER LEG AND THEIR INFLUENCE ON THE PROCESS OF OSTEOGENESIS

Osteogenesis is the process of bone tissue forming, i.e. bone or callus regeneration. This process is influenced by many factors, and the degree of bone fragments’ stability and vascularization in the fracture area are the basic local factors which determine the nature of reparative process. Regenerative process of all bone structures increases with increasing of blood supply.The distal lower leg has its specific biomechanical features, and plays an important role in the transfer of body weight to foot. The distal part of tibia has a small diameter, which as a consequence has reduced diameter in medullar cave. Through this anatomic feature, the medullar network in the lower tibia part is also reduced.As for anatomic aspect, vascularization in the lower end of tibia is poor. It primarily depends on periosteal vascularization, because medullar vascularization is reduced. Fasciae, tendons and skin cover the lower part of the leg, and there is no muscle mass. These tissues have poor vascular network and that is why the extraosseous blood circulation in tibia is poor, and does not participate in the osteogenesis process. For these reasons, distal lower leg represents a predelection site for delayed osteogenesis and pseudoarthrosys development.Osteosynthesis causes secondary damage to bone and soft tissue circulation. The screw plate damages the periosteal circulation – in the lower part of tibia it is the main source of vascularization, and for this reason, this method of osteosynthesis should not be applied. The external fixator has a sparing role regarding vascularization, and that is the reason why this method is recommended for fracture stabilization at the level of distal lower leg

REVERSE ENGINEERING OF THE MITKOVIC TYPE INTERNAL FIXATOR FOR LATERAL TIBIAL PLATEAU

In orthopaedic surgery it is very important to use proper fixation techniques in the treatment of various medical conditions, i.e. bone fractures or other traumas. If an internal fixation method, such as plating, is required, it is possible to use Dynamic Compression Plates (DCP) or Locking Compression Plates (LCP) and their variants. For DCP implants it is important to match the patient's bone shape with the most possible accuracy, so that the most frequent implant bending is applied in the surgery. For LCP implants it is not so important to match the patient’s bone shape, but additional locking screw holes are required. To improve the geometrical accuracy and anatomical correctness of the shape of DCP and to improve the LCP geometric definition, new geometrical modelling methods for the Mitkovic type internal fixator for Lateral Tibia Plateau are developed and presented in this research. The presented results are quite promising; it can be concluded that these methods can be applied to the creation of geometrical models of internal fixator customized for the given patient or optimized for a group of patients with required geometrical accuracy and morphological correctness

IMPLANT MATERIAL SELECTION USING EXPERT SYSTEM

Most certainly, in the field of medicine there is a great contribution of new techniques and technologies, which is reflected in an entire system of health care services. Customized implants are both fully geometrically and topologically adjusted so as to meet the needs of individual patients, thus making each implant unique. Their production requires joint efforts of a multidisciplinary team of different profile experts who combine their knowledge in the Implant knowledge model. Thus, we develop an expert system which should help or replace humans in the process of Implant material selection. This paper gives an overview of the expert system concept for the given problem. Its task is to carry out a selection of biomaterial (or class of material) for a customized implant. The model significantly improves the efficiency of preoperative planning in orthopaedics

DESIGN OF 3D MODEL OF CUSTOMIZED ANATOMICALLY ADJUSTED IMPLANTS

Design and manufacturing of customized implants is a field that has been rapidly developing in recent years. This paper presents an originally developed method for designing a 3D model of customized anatomically adjusted implants. The method is based upon a CT scan of a bone fracture. A CT scan is used to generate a 3D bone model and a fracture model. Using these scans, an indicated location for placing the implant is recognized and the design of a 3D model of customized implants is made. With this method it is possible to design volumetric implants used for replacing a part of the bone or a plate type for fixation of a bone part. The sides of the implants, this one lying on the bone, are fully aligned with the anatomical shape of the bone surface which neighbors the fracture. The given model is designed for implants production utilizing any method, and it is ideal for 3D printing of implants

Interdisciplinary crossover for rapid advancements - collaboration between medical and engineering scientists with the focus on Serbia

Over the past decades, development of engineering sciences has vastly contributed to advancements in medicine by production of numerous devices for diagnostics and treatment. In the middle of the 20th century, a new scientific field, biomedical engineering (BE), was established, which has developed into an extremely complex scientific discipline requiring a distinctive educational profile. Various study programs in BE have been established at universities around the world but also at several universities in Serbia. Also, intensive research in this field is performed at several scientific institutions in Serbia. In the present paper, short summaries of the research results of several groups of engineers and medical doctors are presented as an illustration of the wide field of BE research and possibilities of its application in diagnosis and therapy of various diseases

Interdisciplinary crossover for rapid advancements: Collaboration between medical and engineering scientists with the focus on Serbia

Napretku medicine su poslednjih decenija veoma mnogo doprineli pronalasci iz različitih oblasti inženjerstva. Polovinom dvadesetog veka uspostavlja se nova naučna oblast, biomedicinsko inženjerstvo (BI), koje se do sada razvilo u veoma složenu naučnu disciplinu koja je zahtevala i poseban obrazovni profil. Na univerzitetima širom sveta, kao i na nekoliko univerziteta u Srbiji ustanovljeni su različiti programi iz oblasti biomedicinskog inženjerstva. Takođe, u nekoliko naučnih institucija u Srbiji sprovode se intenzivna istraživanja u ovoj oblasti. U ovom radu prikazani su rezultati istraživanja nekoliko grupa naučnika iz oblasti inženjerstva i medicine sa ciljem da se ilustruje koliko je široko polje istraživanja u oblasti biomedicinskog inženjerstva i kakve su mogućnosti njihove primene u dijagnostici i lečenju različitih bolesti.Over the past decades, development of engineering sciences has vastly contributed to advancements in medicine by production of numerous devices for diagnostics and treatment. In the middle of the 20th century, a new scientific field, biomedical engineering (BE), was established, which has developed into an extremely complex scientific discipline requiring a distinctive educational profile. Various study programs in BE have been established at universities around the world but also at several universities in Serbia. Also, intensive research in this field is performed at several scientific institutions in Serbia. In the present paper, short summaries of the research results of several groups of engineers and medical doctors are presented as an illustration of the wide field of BE research and possibilities of its application in diagnosis and therapy of various diseases

Total hip arthroplasty for femoral neck fractures as an urgent procedure

Background/Aim. Total hip arthroplasty (THA) is one of the most widely accepted operative methods for femoral neck fracture (FNF) in elderly. However, the data on the early THA for FNF are very limited. The aim of this study to determine if there were differences in postoperative complications and functional outcomes between an urgent and delayed THA following FNF. Methods. This prospective study included a total of 244 patients who had THA following FNF from January 2010 to January 2013. In the first group 41 FNF patients were treated with THA within less than 12 hours of admission. A total of 203 FNF patients were operated in delayed settings, of whom 162 required prolonged preoperative processing and comorbidities correction. The group II consisted of 41 FNF patients who were fit for the early surgery at admission, but the operation was delayed due to institution related reasons. Main outcome measurements included mortality, functional outcome assessement, cardiological and pulmonary complications, pressure ulcers, dislocations, infections, length of hospitalization and revisions. Results. There were no differences in terms of age, gender, type of implants, neither in mortality, nor complications. There were differences in hospital length of stay [t (51.72) = -10.25, p < 0.001)]. The patients operated within less than 12 hours of admission, had significantly better scores at all three time points of functional outcome assessment: at discharge t (80) = 2.556, p < 0.012; one month t (80) = 4.731, p < 0.001; three months t (80) = 5.908, p < 0.001. Conclusion. THA for FNF as an urgent procedure is not a widely accepted concept. Our findings indicate that the early operative treatment, does not worsen clinical outcomes, and our results give an advantage to the policy of the early THA for FNF