Journal of Mechanics in Medicine and Biology

In the last years, the internet and multimedia technologies are widely used to exchange medical images and practicing telemedicine; which exposes this data to various illegitimate attacks due to their sensitivity. For this reason, many researchers work to afford a proper security and an efficient protection during the transmission. In this context, we propose a blind multi-watermarking approach for medical images using Lifting Wavelet Transform and Fast Walsh–Hadamard Transform. This approach proves the ability to embed a binary image ($32\times 32$), used for integrity purposes, in addition to the patient information (EPR) associated with the medical cover image. Moreover, an error correcting code was used to improve the security of the EPR. We tested the proposed approach on different imaging modalities, and the obtained results show a good imperceptibility and robustness against several common attacks.

Surgery of nucleus pulposus removal is one of the methods used for the treatment of lumbar disc herniation in the clinic. In order to understand the strain states of the lumbar intervertebral disc (IVD) after nucleotomy, the axial compression experiments of porcine lumbar IVD were implemented using digital image correlation (DIC) technology. The normal IVDs are named as control group; the IVDs treated with trypsin by removing the nucleus pulposus are named as experimental group. The distributions and the change rules of both axial and radial strains in different regions of the IVD with load were studied, and the experimental results of two groups were compared. The results show that both axial and radial strains of different regions increased with stress in two groups, and the variation had non-uniformity. The axial strain in the posterior region of the annulus fibrosus (AF) was larger than that in the anterior region, and the inner AF was larger than that of the outer AF. The axial strain increase of the experimental group was larger than that of the control group obviously. In the posterior region, the radial strain increase was larger than that in the anterior region, and the outer AF was significantly larger than that of the inner AF. The radial strain direction of the experimental group in the inner AF was towards the center of the nucleus pulposus, which was opposite to that of the control group, and the radial strain increase was evidently smaller than that of the control group. In the outer AF, the radial strain direction of the experimental group was the same as that of the control group and the radial strain increase was significantly larger than that.

Mitral Stenosis (MS) is an abnormal condition of the heart mitral valve in which the valve orifice area is reduced leading to many complications in heart function. Noninvasive and less expensive procedures for diagnosis are not currently available. The aim of this work was to explore the use of the radial artery pulse (RAP) to diagnose MS. This paper analyzed the effect of the development and growth of MS on possible radial artery noninvasive assessment parameters. For this, MS was introduced to ex vivo by varying the orifice area to either 1, 2, 3, 4 or 5cm² in a hybrid cardiopulmonary electrical analogous model based on clinically obtained healthy controls with an orifice area of 6cm². Results showed that a mitral valve area less than 2cm² significantly influenced the pulse magnitude and time parameters. A strong correlation was observed in pulse height (PH), mean pulse height (MPH), and time occurrence of the dichotic notch. This may be due to increased blood remaining in the left atrium and hence decreased stoke volume (SV). SV is proportional to arterial pulse pressure which is evident from the decrease in the PH and MPH in MS. In summary, this study provides the first evidence that MS may be diagnosed by examining peripheral pulses which thus, needs further investigation to use RAP as a noninvasive and less expensive MS diagnostic tool.

The anterior and posterior iliac spine markers frequently used to define the pelvis, are commonly occluded during three-dimensional (3D) motion capture. The occlusion of these markers leads to the use of various tracking marker configurations on the pelvis, which affect kinematic results. The purpose of this investigation was to examine the agreement of CODA pelvis kinematic results when two different tracking marker configurations were used during roofing tasks. 3D motion data were collected on seven male subjects while mimicking two roofing tasks. Hip joint angles (HJAs) were computed using the CODA pelvis with two different tracking marker configurations, the trochanter tracking method (TTM), and virtual pelvis tracking method (VPTM). Agreement between tracking marker configurations was assessed using cross-correlations, bivariate correlations, mean absolute differences (MADs), and Bland–Altman (BA) plots. The correlations displayed no time lag and strong agreement (all $r>0.83$) between the HJA from the VPTM and TTM, suggesting the timing occurrence of variables are comparable between the two tracking marker configurations. The MAD between the VPTM and TTM displayed magnitude differences, but most of the differences were within a clinically acceptable range. Caution should still be used when comparing kinematic results between various tracking marker configurations, as differences exist.

Using fuzzy logic methods, some complex experiments that are not possible due to critical limitations can be simulated in a short time. In this study, experimental data of Newtonian 40% aqueous glycerin solution (GS) and non-Newtonian 600ppm aqueous xanthan gum solution (XGS) working fluids were used to model the hydraulic performance of a centrifugal blood pump. A novel fuzzy logic-based model (FLM) for modeling the hydraulic performance of the pump model is proposed. In the proposed model, there are two inputs which are flow rate and impeller rotational speed and one output which is head pressure. In FLM, the range for flow rate is 1–7.8L/min in GS and 1–8L/min in XGS, and for head pressure 50–245mmHg in GS and 50–215mmHg in XGS. In addition, impeller rotational speed range is 2700–3600rpm for both fluids. The estimated results with FLM were validated with the experimental results and it was seen that the FLM was compatible with the experimental results with an accuracy of 96.25%. These results imply that the developed FLM is acceptable and can be used to assist in determining the performance of blood pumps.

The aim of this paper is cardiac sound segmentation in order to extract significant clinical parameters that can aid cardiologists in diagnosis, through maximal overlap discrete wavelet transform (MODWT) and abrupt changes detection. After reconstruction of the fifth to seventh level of decomposition of the pre-processed phonocardiogram (PCG), we can correctly measure the time duration of Fundamental heart sounds (S1, S2), while the third and fourth levels localize murmurs and clicks. From this scope, it is possible to establish the time interval between clicks and fundamental heart sounds or evaluating murmur severity through energetic ratio. We have tested this approach on several phonocardiography records. Results show that this method performs greatly on long and short PCG records and gives the precise duration of fundamental heart sounds; we have achieved an accuracy of 88.6% in cardiac sounds segmentation.

As the effect of many medical agents such as nonsteroidal anti-inflammatory drugs or antibiotics were investigated on bone fracture healing, there is no study about the anesthetic agents when compared histopathologically and biomechanically. We asked the question that if a superiority can be between them since we operate many fractures and see the delayed or nonunions. Although different anesthetic agents are used in general anesthesia, the effects of these substances on bone fracture healing are not clear. Here, we intended to research different anesthetic agents on fracture union in rats. The study was done between January 2020 and November 2021 in a university animal research laboratory. Totally 48 male Wistar-Albino rats weighing 250–300g were seperated into 3 groups as Tiyopental Na in Group 1, Ketamin in Group 2 and Propofol in Group 3. For anesthesia; 40, 100, 100mg/kg of single dosages were injected intraperitoneally, respectively. A shaft fracture was created bilaterally to the tibia of all rats. Kirschner (K) wire is used for the fixation of fractures. Biomechanical and histopathological examination in bones is performed at the end of the first and second months in terms of fracture healing. It has been found that the fracture union in group 1 was statistically signifigant higher than group 3 at the end of the first and second months histopathologically (P = 0.006, P = 0.002). It is also found there is a statistically significant difference between groups 1 and 3 after the second month biomechanically (P = 0.013). Although the union was higher in group 1 than group 2 histopathologically and biomechanically after the first and second months, there was no statistically significant difference (P = 0.376, 0.039; P = 0.028, 0.867). There was a general trend in the decrease of union measurements starting from group 1 to 3 at the end of the first and second month both histopathologically and biomechanically. In this study, it is found that there was a positive consistency between histopathological and biomechanical results with respect to bone union. They supported each other. Fracture healing is stronger in rats that were anesthetized by using thiopental than those using ketamine and propofol, we think that this may affect the choice of anesthetic agent and further studies are needed.

In order to study the influence of different stenosis rates of blood vessels on the fatigue strength and service life of lower limb arterial stent, numerical simulation was conducted for the mechanical behavior of four types of nickel-titanium alloy lower limb arterial stents (Absolute Pro, Complete SE, E-luminexx-B and Pulsar-35) under the action of radial compression, release and pulsating loads, so as to predict the fatigue life and safety of stents at different stenosis rates (0%, 30%, 50% and 70%). The study found that with increased vascular stenosis rate, both the elastic stress and strain of stent tend to increase, while the fatigue strength, service life and safety tend to decrease. When a stent is implanted in a normal blood vessel, its fatigue strength satisfies the requirement of a 10-year service life requirement, with maximum elastic stress and strain occurring on both sides of the connecting ribs at the end of stent. When the vascular stenosis rate is greater than 30%, the fatigue strength of the stent does not meet requirement of a 10-year service life, and fatigue fracture is likely to occur at the most stenotic part of the blood vessel. With increased vascular stenosis rate, the E-luminexx-B stent with the largest width of support had a significant decrease in its service life. The stent whose supporting unit is of symmetric wave peak structure has a longer service life compared with that whose supporting unit is of offset wave peak structure. The revealing of the influence of vascular stenosis rate on the mechanical properties and fatigue life of stents provides theoretical reference for the fracture failure mechanism of stents.

Osteoporosis is a bone disease characterized by a low bone mass that may seriously lead to vertebral fractures. Nowadays, especially elderly people, are most vulnerable to this complication. Hence, it is essential to prevent and predict the high-risk of mechanical stress that causes bone fractures. In this paper, a new computational methodology is developed to prevent the increase in the risk of bone failure in osteoporotic cervical vertebra based on mechanical stress assessment. The cortical bone thickness and the trabecular bone density from computed tomography (CT) scan data are the main initial input parameters for the computation. The methodology is based on a combination of finite element (FE) modeling of the lower cervical spine and the design of experiment (DoE) technique to establish surface responses assessing mechanical stress in healthy and osteoporotic vertebrae. The results reveal that the mechanical stress applied to an osteoporotic cervical vertebra is higher by an average of 35% compared to a healthy vertebra, respecting the applied conditions. Based thereon, a safety factor ($S$) is introduced to predict and indicate the state of osteoporosis in the vertebra. A safety factor $S\ge 2.45$ is found to correspond to a healthy state, 1.85 $\le S<$ 2.45 for an osteopenic state, 1 $\le S<$ 1.85 for an osteoporotic state, and $S\le$ 1 to indicate a severe osteoporosis state. The developed computational methodology consists of an efficient tool for clinicians to prevent early the risk of osteoporosis and also for engineers to design safer prostheses minimizing both mechanical stress concentration and stress shielding.

Object: In this paper, eight male basketball players were tested for physical fitness using the method of sports biology. The content of the physical examination is the isokinetic muscle strength of the shoulder joint. This paper aims to investigate the effect of shoulder isokinetic muscle strength on athletic performance. Methods: This paper uses the principles of sports biology and the isokinetic muscle strength test system to measure the shoulder torque and fatigue index of eight basketball players. At the same time, this paper analyzes the obtained data using the method of mathematical statistics. Results: There were significant differences in the test data of eight male basketball players (P < 0.05). The fatigue of basketball players is mainly in the middle and late stages of sports. At average speed, the fatigue index of the shoulder is the lowest at 180°/s. Conclusion: Basketball players have stronger shoulder extensors than flexors. The balance of strength in the shoulder flexors is greater than the balance in the extensors.

This paper studies the biomechanics of muscles after swimming. This paper uses exercise biomechanics and deep learning models to process surface EMG signals after muscle injury. In this way, the relationship between the EMG signal and muscle strength after muscle injury after swimming can be obtained. Studies have found a proportional relationship between muscle strength and the strength of EMG signals during muscle injury recovery after swimming. The conclusions of this study can provide us with some clinical experience in the recovery of muscle damage during physical exercise.