Julius Griškevičius

Research of Muscular Activity during Gait of Persons with Cerebral Palsy

Assessing muscular activity during gait in CP persons could provide valuable information in prescribing appropriate treatment to reduce the consequences of cerebral palsy as well as limiting further complication in cerebral palsy children. The main goal of this study was explored working regularities of muscle pairs in children population to show dependencies and variation on gait parameters. Functional evaluation was carried out on 20 cerebral palsy patients. The research have been done by using the system EMG. A surface electrode picked up on the main groups of muscles of lower limbs: the Rectus Femoris, the Vastus Lateralis, the Medial Hamstrings, the Lateral Gastrocnemius, and the Anterior Tibialis. There were several phases to the signal approach such as: data acquisition, data pre-processing, data modeling, data analysis and interpretation. From the results seen that for each task subjects have different strategies for keeping balance during walk depending on the basic level of muscle contraction or antagonistic and synergistic contraction required for that activity.

Quantitative Analysis of Parkinsonian Tremor in a Clinical Setting Using Inertial Measurement Units

Background Parkinsons disease (PD) is a neurodegenerative disorder that affects human voluntary movements. Tremor is one of the most common symptoms of PD and is expressed as involuntary oscillation of the body. Tremors can be analysed in the frequency domain. Objective The aim of the current study was to examine selected tremor parameters (frequency, root mean square, and approximated entropy) in order to quantify the characteristics of patients diagnosed with PD, compared to a healthy control group, and to compare the parameters by dividing the subjects according to UPDRS assessment. Methods The subjects were divided into two groups: a group of people diagnosed with PD (n = 19) and a control group consisting of healthy volunteers (CO = 12). Each subject performed motor tasks specific to certain tremors: the finger-to-nose test. Each subject performed a motor task three times. A nine degree of freedom (DOF) wireless inertial measurement unit was used for the measurement of upper limb motor tasks. For the quantitative estimation of kinetic and postural tremors, dominant frequency, root means square, and approximation entropy were selected and calculated from the measured angular velocity and linear acceleration signals. A one-way ANOVA with a significance level of α = 0.05 was used to test the null hypothesis that the means of the tremor metrics were the same between the PD and CO groups. Results Statistically significant differences between PD patients and control groups were observed in ApEn acceleration signal of kinetic tremor, ApEn angular velocity signal of kinetic tremor, ApEn angular velocity of postural tremor, frequency acceleration signal of postural tremor, and RMS angular speed kinetic tremor. Conclusion Application of inertial measurement units for clinical research of patients and PD tremor evaluation allows providing quantitative information for diagnostic purposes, during screening in a clinical setting that differentiates between PD patients and controls.

Differences in temporal gait parameters between multiple sclerosisand healthy people

Multiple sclerosis (MS) causes severe gait problems and there are limited studies to quantitatively identify the specific gait parameters that are affected. The aim of the current study was to characterize the temporal gait parameters in MS patients and ascribe them to clinical variables, in order to enable target-oriented management. A total of 14 MS patients and 11 healthy controls (CO) were evaluated clinically by expanded disability status scale (EDSS) and quantitatively by the Timed 25 Foot Walk (T25FW) using non-invasive wireless inertial sensors. The self-selected walking velocity was used as a covariate in the analysis to ensure that group differences were not due to differences in walking velocity between the MS and CO groups. Reduced step time and cadence were seen in patients with MS. We also found significant correlations between biomechanical gait parameters and EDSS score, which provides a clinical rating of disease severity. Temporal gait variability noted as associated to slower walk in MS.

Biomechanical evaluation of native acromioclavicular joint ligaments and two reconstruction techniques in the presence of the sternoclavicular joint: A cadaver study:

Background: Where is over 100 reconstruction techniques described for acromioclavicular (AC) joint reconstruction. Although, it is not clear whether the presence of the sternoclavicular (SC) joint influences the biomechanical properties of native AC ligaments and reconstruction techniques. The purpose of the present study was to investigate the biomechanical properties of native AC joint ligaments and two reconstruction techniques in cadavers with the SC joint still present. Materials and Methods: We tested eight fresh-frozen cadaver hemithoraces for superior translation (70 N load) and translation increment after 1000 cycles (loading from 20 to 70 N) in a controlled laboratory study. There were three testing groups created: native ligaments, the single coracoclavicular loop (SCL) technique, and the two coracoclavicular loops (TCL) technique. Superior translation was measured after static loading. Translation increment was calculated as the difference between superior translation after cyclic and static loading. Results: Native AC ligaments showed significantly lower translation than the SCL (p = 0.023) and TCL (p = 0.046) groups. The SCL had a significantly lower translation increment than native AC ligaments (p = 0.028). There was no significant difference between reconstruction techniques in terms of translation (p = 0.865) and translation increment (p = 0.113). Conclusions: Native AC joint ligaments had better static properties than both reconstruction techniques and worse dynamic biomechanical properties than the SCL technique. The SCL technique appeared to be more secure than the TCL technique. The presence of the SC joint did not have an observable influence on test results.

ALTERNATIVE METHOD OF UPPER EXTREMITY FUNCTION ASSESSMENT OF STROKE PATIENTS BY ANGULAR KINEMATIC PARAMETERS

This study focuses on the functional assessment of the upper extremity of stroke patients via analysis of angular kinematics features. Amplitudes and angular velocities of multi-joint movements more precisely describe functional state at different impairment levels. However, the arm movement as a whole could be analyzed by means of joint angle–angle diagrams, which illustrate the 2D trajectory of upper extremity during movement and show the visual ranges of upper extremity in different cycles of motion. The functional range of motion of each upper extremity segment in all patient groups for more accurate assessment of capability was calculated. Moreover, we calculated the area (S) between two curves in joint angle–angle diagrams as a novel index of the complete upper extremity movement range evaluation. Our findings correspond to clinical rates and upper extremity assessment based on joint angle–angle diagrams seems to be a promising method for accurate assessment and/or predicting the outcomes of rehabilitation programs.

BIOMECHANICAL COMPARISON OF THE CORACOCLAVICULAR SPACE FIXATION USING THREE DIFFERENT SUTURE TECHNIQUES

Coracoclavicular space fixation with suture loops is a well-known surgical technique for the treatment of dislocations. However, out of 100 different surgical treatments no single one has been established as a gold standard. The following research aims to improve the technique and focuses on a development of new fixation technique using composite sutures, which would withstand forces during ligament healing process. Three different fixation techniques (one loop and two separate suture loops and W-system) were tested on a custom built mechanical testing device. Applied load was continuously increased at a loading rate of 30N/min until the failure of the sutures. Ultimate tensile strength and suture elongation at failure were measured. The W-system had statistically significant higher load to failure and higher stiffness compared to one loop and two separate loops techniques. Biomechanical properties of a suture fixation technique can be improved by connecting them into one system to create particular arrangement of the sutures. The measurements can be easily repeated and this testing protocol can serve as a good starting point to standardize procedures of evaluation of different joint fixation techniques and to develop new ones.

Different Stabilization Techniques for Type 62B3 Acetabular Fractures in Combination With Primary Total Hip Arthroplasty in Elderly Patients: A Biomechanical Comparison

Introduction: The total hip arthroplasty (THA) as part of acute fracture management is used for acetabular fractures in elderly patients. Our objective was to assess the stability of osteosynthesis performed using 2 different techniques in combination with THA in an experimental model. Materials and Methods: We conducted 20 experiments using the left-side hemipelves composite bone models. There were 2 testing groups: 1- and 2-stage osteosynthesis. The acetabular fractures of the anterior column and posterior hemitransverse were simulated. The same THA technique was used in both groups. The stability of osteosynthesis was explored and compared between the groups by measuring the fracture displacement of anterior and posterior columns under the standardized test load (1187 N) protocol. Load distance diagrams were generated. Results: The 0.680-mm gap (0.518; 1.548) of the posterior column in the 1-stage group (n = 10) was higher than the 0.370-mm gap (0.255; 0.428) in the 2-stage group (n = 10; P = .002). There was no significant difference between the gap of the anterior column in the 1- and 2-stage groups (0.135 [0.078; 0.290] mm vs 0.160 [0.120; 0.210] mm; P = .579). Conclusion: The 2-stage osteosynthesis of the anterior and posterior columns in combination with THA provides better stability of posterior column when compared to 1-stage method in composite bone models.

Neurological diseases differentiation analysis using inertial measurement units

Human gait is cyclic process, which is affected by various neurological disorders like Parkinsons disease (PD) or multiple sclerosis (MS). Instrumented gait analysis facilitate monitoring and diagnosing motor deficiencies; it may serve as a tool for clinicians evaluating the patients. This study aims at finding biomechanical parameters that allow separating pathological gaits via application of inertial sensors to capture the gait. The experiment involved 33 subjects divided in three groups PD, MS and healthy controls (CO). The analysis showed the statistically significant difference between stride time of the right leg in MS and CO groups, left stride time between PD and CO, stance time difference between PD and CO group, right and left leg. Hip flexion and extensions amplitudes difference was between CO and PD group, left hip flexion and extension.

Investigation of mutual aerobic and lower limb muscular activity during cycling.

The evaluation of physical activity is a complex task that requires performing an analysis of muscular activity and aerobic/anaerobic threshold and it is often difficult to observe and propose a single method. The purpose of the article is to evaluate a relation between aerobic capacity and activity of lower limb muscles via changes of muscles EMG signal during physical, sub-maximal veloergometric loading. The activity parameters of 5 lower limb muscles such as semitendinosus, rectus femoris, biceps femoris, gastrocnemius medialis, and tibialis anterior were measured and analyzed during the veloergometric exercise tests and the heart rate and the aerobic capacity were estimated from registered data. The obtained aerobic parameters allow setting an individual and overall voluntary physical capacity. The regression oxygen function presented allows analyzing and predicting the ability of subjects to generate energy while maintaining muscle activity during the exercise. The correlation between the consumption of oxygen and constant physical loading time is determined. It was found that comparing VO2max capabilities the physical effort in the male group was 16% higher than in women. Oxygen consumption and maximum muscle effort dependency on the load time was established. It was observed that the maximal muscular effort appeared before VO2max reached maximal limit in both groups. The maximal oxygen consumption is achieved in the middle or sometimes at the beginning (depending on load) of exercise while maximal muscular effort was found in several phases of cycling: at the beginning and at the end of loading time.