Aleksandar Matic - Academia.edu (original) (raw)

Papers by Aleksandar Matic

International Journal of Precision Engineering and Manufacturing, Jul 1, 2018

In this paper, a method of parameterisation of a proximal femur model is presented. The created m... more In this paper, a method of parameterisation of a proximal femur model is presented. The created model retains all the anatomical and morphological features of a realistic model. The parametric model of the femur, the so-called master model, is defined by establishing a relation between appropriate femoral regions which extend along the parametrically described axis of the femur. An initial 3D model of the femur is segmented from the CT image and further parameterized to a master model with the potential for customization, i.e. for adaptation to patient-specific values using X-ray images, still maintaining precise anatomical consistency. The first step towards the femur customization is the contour extraction of different types of tissues represented in X-ray images. As medical images can be blurry, image processing was carried out and a Canny edge detector operator was applied. The numerical values of the parameters were determined by manual measuring of defined regions on an X-ray image. The variability testing was performed on 12 femurs. The proposed model can greatly contribute to preoperative planning, implant selection, as well as to the overall shortening of intervention time.

Tribology in industry, Dec 1, 2014

Total knee replacement (TKR) is considered, during last years, as a very successful surgical tech... more Total knee replacement (TKR) is considered, during last years, as a very successful surgical technique for removing knee joint deformities and eliminating pain caused by cartilage damage. In literature, as primary causes for knee joint endoprothesis damage are cited complex movements which cause occurrences of complex stress conditions, sagital radius conformity, sliding, types of materials etc. Aim of this study is analysis of contact stresses that occur on tibial implant for 15°, 45° and 60° knee flexion and 50 kg, 75 kg, 100 kg and 125 kg weight. Knee joint prosthesis model and finite elements method (FEM) analysis are done in software Catia V5. For this analysis we used ultra-high molecular weight polyethylene (UHMWPE) for tibial implant material and AISI 316, AISI 317, AISI 321, 17-4PH, CoCrMo, Ti6Al4V and SAE A-286 for femoral component materials. Results show that area of maximal contact stress is identified in medial and lateral part of tibial implant. Von Mises stress values vary regarding of flexion degree and weight, but values are approximate for types of chosen materials. Contact stress location corresponds to damage that occur on tibial implant during exploitation.

In studies so far have been shown that clinical analysis of the gait parameters is extremely impo... more In studies so far have been shown that clinical analysis of the gait parameters is extremely important for improving diagnostics and following illness or deficiencies of lower extremities, as well as for analyzing recuperation levels after therapy. Purpose of this paper is to analyze possibility of using easily affordable web cameras for recording knee movement. Recordings are made with web cam on Fujitsu lifebook E laptop. Algorithm for object tracking is made in programming environment MatLAB. Five participants have participated in this research. Results are graphically presented for left and right leg for one gait cycle along straight line and values for anterior posterior (AP) translation are shown in tables for every phase of gait cycle. Acquired study results show that it is possible to measure observed parameter in this way and that values correspond with values obtained in previous studies.

International Orthopaedics, Jul 2, 2015

Purpose Previous clinical studies have shown that anterior cruciate ligament (ACL) ruptures requi... more Purpose Previous clinical studies have shown that anterior cruciate ligament (ACL) ruptures require reconstructive surgery. The main goal of this study is an objective test definition for unstable knee diagnosis based on real measurements by using infrared cameras and adequate software. Methods In the study of gait analysis 35 males with deficient ACL's participated. Pathological parameters for anterior posterior translation (APT) and internal external rotation (IER) and their values of kinematic data were obtained from a gait analysis 3D system. Movement curves were obtained by recording the position of fluorescent markers over time. A machine learning algorithm was developed in order to support decisions on the severity of the ACL injury and its corresponding deficiency. The algorithm was based on logistic regression. Results The value of APT, designated as exponentiation of the Ө coefficient (Exp (Ө)) of APT, showed that the likelihood of ACL-deficient knee occurrence due to higher values of APT is 1.1758 (95 % CI) times more frequent than that of the patients with lower values of APT. The value of IER, designated as Exp (Ө) of IER, showed that the patients with higher values of IER present 2.2516 (95 % CI) times higher values of ACL-deficient knee frequency than those with lower values. Conclusion This study showed that the creation of ordered pairs of pathological parameters gives a wider picture of ACL deficiency and that such an algorithm may improve both examination and treatment of patients.

2018 7th Mediterranean Conference on Embedded Computing (MECO), 2018

The paper presents preliminary results of the application of a portable motion capture system to ... more The paper presents preliminary results of the application of a portable motion capture system to define a mathematical model of the movements inside the knee joint (for a clinically healthy knee, for cruciate ligament deficiency and for degenerative disease of the knee). In this study we used the OptiTrack motion capture system. Gathered data were processed with the programming environment MATLAB in order to define a mathematical estimation model and classification algorithm. Clinical verification and the analysis of the classification model performance indicators show the full potential of such motion capture systems for various examinations.

The paper presents a framework for technology enhanced education (TEE) in orthopaedics aimed at e... more The paper presents a framework for technology enhanced education (TEE) in orthopaedics aimed at employment of ubiquitous information and communication technology (ICT) and digital technologies in order to compensate for an unaffordable learning environment. On the other side, the concept involves both (bio)engineers, ICT specialists, and orthopaedic surgeons in an interprofessional collaboration, leveraging multidisciplinary approaches to improve the quality of clinical-oriented education. Preliminary results indicate increased motivation and satisfaction of both the learners and educators.

Srpski arhiv za celokupno lekarstvo, 2021

Introduction/Objective. The essence of the treatment of degenerative knee joint diseases is pain ... more Introduction/Objective. The essence of the treatment of degenerative knee joint diseases is pain relief, restoring motion range and stability of knee joints. Methods. In this study, 35 patients participated after having surgery of the knee joint. The patients had a posterior-stabilized (PS) endoprosthesis in one joint, and a posterior cruciate ligament retaining (CR) endoprosthesis in the other. Kinematic data was collected using a 3D optical system for tracking fluorescent markers in time. Based on these data, the following parameters were determined: degree of flexion, mediolateral (ML) translation, lateral gap, medial gap, and the angle of change between the transtibial and transfemoral axes. Results. The results show a more pronounced flexion degree with the PS prosthesis compared to the CR prosthesis. Also, the results show negligible values of the ML translation, lateral gap, and medial gap in both types of prostheses. Using the non-parameter Wilcoxon test, a substantial diffe...

$Research paper thumbnail of Adverse plasma fatty acid composition in patients with femoral neck fracture1$

Canadian Journal of Physiology and Pharmacology, 2019

Our study aimed to examine the status of plasma fatty acids (FAs), inflammatory markers, and lipi... more Our study aimed to examine the status of plasma fatty acids (FAs), inflammatory markers, and lipid peroxidation in patients with femoral neck fractures. The study included 20 patients (64–86 years) with femoral neck fractures indicated for surgery and a control group of 17 elderly subjects without fractures or serious chronic diseases. Plasma was obtained during the first 12 h postfracture and presurgery and 7 days postop. Compared to the control, patients had significantly higher saturated FA (SFA) and monounsaturated FA as well as increased TNF-α and IL-6. Opposite to that, levels of individual and total n-6 polyunsaturated FA (PUFA), individual and total n-3 PUFA, n-6/n-3 ratio, and levels of thiobarbituric acid reactive substances (TBARS) were markedly lower in the patient than in the controls. On the seventh day after the surgery, we showed a further rise in the SFA, oleic acid, and TNF-α and reductions of n-6 PUFA and IL-6. Taken together, our results suggest that altered FA s...

Acta Chirurgica Iugoslavica, 2015

2015 IEEE 15th International Conference on Bioinformatics and Bioengineering (BIBE), 2015

International Journal of Molecular Sciences

The beneficial effects of HBO in inflammatory processes make it an attractive type of treatment f... more The beneficial effects of HBO in inflammatory processes make it an attractive type of treatment for chronic arthritis. In addition, the effects of combination therapy based on adipose stem cells and HBO on OA progression have not been fully investigated. The current study explored the efficacy of intra-articular injection of allogeneic adipose-derived mesenchymal stem cells (ADMSCs) combined with hyperbaric oxygenation treatment (HBO) in a rat osteoarthritis (OA) model. The rat OA model was induced by intra-articular injection of monoiodoacetate (MIA) and 7 days after application of MIA rats were divided into five groups: healthy control (CTRL), osteoarthritis (OA), ADMSCs (ADS), the HBO+ADS21day and HBO+ADS28day groups. A single dose of 1 × 106 allogeneic ADMSCs suspended in sterile saline was injected into the knee joint alone or in combination with HBO treatment. Rats were sacrificed at 3 or 4 weeks after MIA injection. Treatment outcomes were evaluated by radiographic, morpholog...

Serbian Journal of Experimental and Clinical Research, 2015

Discoid meniscus is a morphological anomaly of the lateral meniscus that appears in 1–5% of menis... more Discoid meniscus is a morphological anomaly of the lateral meniscus that appears in 1–5% of meniscectomies. A precise diagnosis remains difficult to make, and many dilemmas hinder effective treatment. To evaluate the incidence of discoid meniscus in patients who underwent knee arthroscopy, as well as the discoid meniscus type, follow-up problems, combined knee lesions, and postoperative results. This retrospective study included 1357 patients who received knee arthroscopy during the period between January 2007 and December 2013. We analysed the discoid meniscus incidence, sex distribution, type distribution (Monllau classification), noted preoperative symptomatology, rupture incidence and type (O’Connor classification), anomaly presence and other intra-articular lesion correlations. The IKDC score was used to evaluate the operative treatment results. The DLM incidence was 1.03%. The most common type of discoid meniscus was complete 5 (35.71 %). The dominant symptom was pain, which w...

Acta chirurgica Iugoslavica, 2015

The aim of this study was to evaluate total knee arthroplasty success, throw gait analysis of pat... more The aim of this study was to evaluate total knee arthroplasty success, throw gait analysis of patients who were underwent a surgery according to objective indicators. Material and methods: Fourteen patients were participated in our study who suffered from a certain type of gonarthrosis. Data were gathered(collected) using a commercial OptiTrack system for motion recording using six infrared cameras. Markers were placed on patients? lower extremities, on previously determined anatomical regions. After recording the data were processed using computing environment MATLAB. Results: Observing our lab results we noticed a significant reduction in range of motion (ROM) of arthritic knees in relation to the healthy knees. ROM reduction is primarily related to flexion and extension, as well as to medial and lateral translation. Following the TKA, ROM increases, and these values get close to the values that were measured in a healthy knee. The results were presented using graphs for a healthy...

Vojnosanitetski pregled, 2016

Background/Aim. Posterior cruciate ligament is the primary stabilizer of the posterior tibia tran... more Background/Aim. Posterior cruciate ligament is the primary stabilizer of the posterior tibia translation and secondary stabilizer of external tibial rotation as well as varus, valgus knee angulation. It is the strongest ligament in the knee that hurts the rarest. The aim of this study was to show the indications for surgery, present the surgical technique and give results of surgical treatment of posterior knee instability. Methods. The study icluded 12 patients who were tretaed surgically for posterior knee instabilility at the Institute for Orthopaedic Surgery ?Banjica?, Belgrade, in the period from 1st January 2010 to 1st January 2014. All of them had arthroscopically assisted anatomic reconstruction of posterior crucuate ligament done with 4-strand hamstring tendon graft. Postoperative follow-up lasted approximately 42 months and Lysholm values and International Knee Documentation Committee (IKDC) score were compared as well as the clinical status. Results. All treated patients ...

Vojnosanitetski pregled, 2011

Background/Aim. Medial open wedge tibial osteotomy is one of the most widely accepted method of t... more Background/Aim. Medial open wedge tibial osteotomy is one of the most widely accepted method of treatment for varus knee deformity in younger patient population. Its success depends on the quality of fixation and preservation of the outer cortex of the tibia. The aim of the study was to evaluate stress distribution in five numerically designed plate configurations which can be used in open wedge tibial osteotomy. Methods. The paper describes the 3D numerical model of the tibia with 10? varus deformity correction obtained by an optical scanner ATOS. The simulation anticipated axial compressive loads of 700 N, 1 400 N and 2 100 N. We used a modification of the standard T-plate in all of the five tested models. Modalities were tested with and without a metal block, and with and without a stable angle fixation plates and screws. Software PAK was used in the analysis of stress distribution. Results. With exception for the standard T-plate configuration without the supporting block, the l...

2013 2nd Mediterranean Conference on Embedded Computing (MECO), 2013

ABSTRACT Foot load observed as pressure distribution is examined in relation to a foot and ankle ... more ABSTRACT Foot load observed as pressure distribution is examined in relation to a foot and ankle functions within the gait cycle. This load defines the modes of healthy and pathological gait. Determination of the patterns of healthy, i.e. “normal” walk is the basis for classification of pathological modes. Eleven healthy participants were examined in this initial study. Participants walked over pressure plate barefoot at their self - selected speed. Maximal values of the pressure were recorded in the heel, the first, the second and the third metatarsal joints and in the hallux region. Largest contact duration is recorded in the metatarsal region.

Computer Science and Information Systems, 2013

In this study we modeled a patient specific 3D knee after anterior cruicate ligament (ACL) recons... more In this study we modeled a patient specific 3D knee after anterior cruicate ligament (ACL) reconstruction. The purpose of the ACL reconstruction is to achieve stability in the entire range of motion of the knee and the establishment of the normal gait pattern. We present a new reconstruction technique that generates patient-specific 3D knee models from patient?s magnetic resonant images (MRIs). The motion of the ACL reconstruction patients is measured by OptiTrack system with six infrared cameras. Finite element model of bones, cartilage and meniscus is used for determination stress and strain distribution at different body postures during gait analysis. It was observed that the maximum effective von Mises stress distribution up to 8 MPa occurred during 30% of the gait cycle on the meniscus. The biomechanical model of the knee joint during gait analysis can provide insight into the underlying mechanisms of knee function after ACL reconstruction.

Serbian Journal of Experimental and Clinical Research, 2012

Anterior cruciate ligament (ACL) injuries are relatively common in young athletes and quite often... more Anterior cruciate ligament (ACL) injuries are relatively common in young athletes and quite often require surgical reconstruction. Th e purpose of the ACL reconstruction is to achieve stability in the entire range of motion of the knee and to re-establish a normal gait pattern. For this study, we examined nineteen adult men. Subjects walked along a pathway at their own speed. Motion curves were obtained based on the kinematic data collected using the OptiTrack system with six infrared cameras. Anteriorposterior tibia translation, as the leading ACL pathological parameter, was indirectly determined by monitoring the difference in the length of the distance between markers positioned at the femoral lateral epicondyle and at the tuberosity of the tibia in space and in the sagittal plane. Additionally, the angle of the internal-external rotation was monitored using the gradient of the tangent line of the motion curve. Anterior-posterior tibia translation and internal-external rotation were signifi cantly diff erent after reconstruction surgery compared with preoperational measurements. Preoperational measurements included the maximal values of the AP translation and IE rotation in the early stance phase of the gait cycle. An increase of the AP translation and IE rotation values may cause degeneration of the cartilage. Th ese results reveal that a more precise diagnosis of the ligament instability can be made, providing relevant indicators for the type of treatment.

The Journal of Physical Chemistry B

A detailed understanding of the local dynamics in ionic liquids remains an important aspect in th... more A detailed understanding of the local dynamics in ionic liquids remains an important aspect in the design of new ionic liquids as advanced functional fluids. Here, we use small-angle X-ray scattering and quasi-elastic neutron spectroscopy to investigate the local structure and dynamics in a model ionic liquid as a function of temperature and pressure, with a particular focus on state points (P,T) where the macroscopic dynamics, i.e., conductivity, is the same. Our results suggest that the initial step of ion transport is a confined diffusion process, on the nanosecond timescale, where the motion is restricted by a cage of nearest neighbors. This process is invariant considering timescale, geometry, and the participation ratio, at state points of constant conductivity, i.e., state points of isoconductivity. The connection to the nearest-neighbor structure is underlined by the invariance of the peak in the structure factor corresponding to nearest-neighbor correlations. At shorter timescales, picoseconds, two localized relaxation processes of the cation can be observed, which are not directly linked to ion transport. However, these processes also show invariance at isoconductivity. This points to that the overall energy landscape in ionic liquids responds in the same way to density changes and is mainly governed by the nearest-neighbor interactions.

International Orthopaedics, 2015

Previous clinical studies have shown that anterior cruciate ligament (ACL) ruptures require recon... more Previous clinical studies have shown that anterior cruciate ligament (ACL) ruptures require reconstructive surgery. The main goal of this study is an objective test definition for unstable knee diagnosis based on real measurements by using infrared cameras and adequate software. In the study of gait analysis 35 males with deficient ACL&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s participated. Pathological parameters for anterior posterior translation (APT) and internal external rotation (IER) and their values of kinematic data were obtained from a gait analysis 3D system. Movement curves were obtained by recording the position of fluorescent markers over time. A machine learning algorithm was developed in order to support decisions on the severity of the ACL injury and its corresponding deficiency. The algorithm was based on logistic regression. The value of APT, designated as exponentiation of the Ө coefficient (Exp (Ө)) of APT, showed that the likelihood of ACL-deficient knee occurrence due to higher values of APT is 1.1758 (95 % CI) times more frequent than that of the patients with lower values of APT. The value of IER, designated as Exp (Ө) of IER, showed that the patients with higher values of IER present 2.2516 (95 % CI) times higher values of ACL-deficient knee frequency than those with lower values. This study showed that the creation of ordered pairs of pathological parameters gives a wider picture of ACL deficiency and that such an algorithm may improve both examination and treatment of patients.