| 1. |
- Ahmed, Kirstin, 1974, et al.
(författare)
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Mechanical load applied by Intraosseous Transcutaneous Amputation Prosthesis (ITAP) during walking on level and sloped treadmill: A case study
- 2023
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Ingår i: Medical Engineering and Physics. - 1350-4533 .- 1873-4030.
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Tidskriftsartikel (refereegranskat)abstract
- This proof of concept study presents a method to collect and analyse kinetic data from one participant with a transfemoral amputation fitted with a percutaneous osseointegrated implant walking on a level and sloped treadmill. We describe the construction of and results from a bespoke wireless six axis load cell built into one participant’s prosthetic assembly. The load cell does not clinically compromise the participant in any way and is an initial milestone in the development of a light-weight wireless load cell for use with percutaneous osseointegrated implants. In this case, it is the first time that kinetic data from a participant fitted with an Intraosseous Transcutaneous Amputation Prosthesis has been published. We propose that the data can be used to model the load transfer to the host bone, with several clinically significant applications. The raw dynamic data are made available and quasi-static load cases for each functional phase of gait are presented. Peak forces obtained in the medio-lateral (X), cranio-caudal (Y) and antero-posterior (Z) axes over level ground respectively were -243.8 N (0.24 BW), 1321.5 N (1.31 BW) and -421.8 N (0.42 BW); uphill were -141.0 N (0.14 BW), 1604.2 N (1.59 BW), -498.1 (0.49 BW); downhill were -206.0 N (0.20 BW), 1103.9 N (1.09 BW), -547.2 N (0.54 BW). The kinetics broadly followed non-amputated gait patterns with some gait strategies consistent in participants with other implant designs or prosthetic socket connections, for example offloading the artificial limb downhill.
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| 2. |
- Atashipour, Rasoul, 1983, et al.
(författare)
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Mechanical characterization of human skin—A non-invasive digital twin approach using vibration-response integrated with numerical methods
- 2023
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Ingår i: Medical Engineering and Physics. - 1350-4533 .- 1873-4030. ; 121
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes an innovative approach to identify elastic material properties and mass density of soft tissues based on interpreting their mechanical vibration response, externally excited by a mechanical indenter or acoustic waves. A vibration test is performed on soft sheets to measure their response to a continuous range of excitation frequencies. The frequency responses are collected with a pair of high-speed cameras in conjunction with 3-D digital image correlation (DIC). Two cases are considered, including suspended/fully-free rectangular neoprene sheets as artificial tissue cutout samples and continuous layered human skin vibrations. An efficient theoretical model is developed to analytically simulate the free vibrations of the neoprene artificial sheet samples as well as the continuous layered human skins. The high accuracy and validity of the presented analytical simulations are demonstrated through comparison with the DIC measurements and the conducted frequency tests, as well as a number of finite element (FE) modeling. The developed analytical approach is implemented into a numerical algorithm to perform an inverse calculation of the soft sheets' elastic properties using the imported experimental vibration results and the predicted system's mass via the system equivalent reduction/expansion process (SEREP) method. It is shown that the proposed frequency-dependent inverse approach is capable of rapidly predicting the material properties of the tested samples with high accuracy.
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| 3. |
- Höglund, Gustav, et al.
(författare)
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The importance of inertial measurement unit placement in assessing upper limb motion
- 2021
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Ingår i: Medical Engineering and Physics. - : Elsevier. - 1350-4533 .- 1873-4030. ; 92, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Motion analysis using inertial measurement units (IMU) has emerged as an alternative to optical motion capture. However, the validity and reliability of upper limb measurements varies significantly between studies. The objective of this study was to determine how sensor placement affects kinematic output in the assessment of motion of the arm, shoulder, and scapula. IMUs were placed proximally/distally on arms, and medially/laterally on the scapula, in a group of eleven healthy participants, while performing nine different motion tasks. Linear regressions and mixed models analysed how these different sensor placements affected the estimated joint motion by establishing the linear relationship between sensors placed on the same body segment. The placement of sensors affected the measured kinematic output considerably, most prominent affect was seen for sensor placement on scapula during flexion and abduction, and on forearm during pronation/supination. The slope of the linear regression lines was 2.5 during flexion, 2.7 during abduction, and 1.8 for forearm pronation/supination. The results of this study suggest that the forearm sensor should be placed on the dorsal side of the forearm, at the distal end; the upper arm sensor should be placed laterally, on the distal part of the arm; and the sensor on the scapula should be placed cranially, along the spine of scapula.
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| 4. |
- Januario, Leticia, 1990-, et al.
(författare)
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Serratus anterior sEMG – sensor placement and test position for normalization purposes during maximal and submaximal exertions
- 2022
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Ingår i: Medical Engineering and Physics. - : Elsevier. - 1350-4533 .- 1873-4030. ; 101
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Tidskriftsartikel (refereegranskat)abstract
- There is great variability regarding serratus anterior sEMG sensor placement and test positions during normalization procedures. We investigated between-trials reliability of serratus anterior sEMG, acquired at two sensor placements and four test positions, during maximal and submaximal isometric contractions. Twenty young healthy women participated. sEMG was captured at the 7th intercostal space and at the xiphoid process level, in the mid-axillary line, during maximal and submaximal isometric contractions, in four test positions. Intraclass Correlation Coefficient (ICC2,1), coefficient of variation and standard error of measurement were calculated. Interactions between sensor placements and test positions were investigated using a two-way repeated-measures ANOVA. All test conditions presented ICC2,1 > 0.8. There was no interaction between sensor placement and test position. Signal obtained from the sensor at 7th intercostal space was more stable between-trials and showed higher amplitude, during maximal and submaximal contractions, at seated positions with shoulder protracted at both 90° or 125° of flexion. We suggest to acquire serratus anterior sEMG at the 7th intercostal space and perform maximal or submaximal isometric contractions for signal normalization with shoulder protracted and flexed, at seated position.
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| 5. |
- Parker, Louis P., et al.
(författare)
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In silico parametric analysis of femoro-jugular venovenous ECMO and return cannula dynamics : In silico analysis of femoro-jugular VV ECMO
- 2024
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Ingår i: Medical Engineering and Physics. - : Elsevier BV. - 1350-4533 .- 1873-4030. ; 125
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Tidskriftsartikel (refereegranskat)abstract
- Background: : Increasingly, computational fluid dynamics (CFD) is helping explore the impact of variables like: cannula design/size/position/flow rate and patient physiology on venovenous (VV) extracorporeal membrane oxygenation (ECMO). Here we use a CFD model to determine what role cardiac output (CO) plays and to analyse return cannula dynamics. Methods: : Using a patient-averaged model of the right atrium and venae cava, we virtually inserted a 19Fr return cannula and a 25Fr drainage cannula. Running large eddy simulations, we assessed cardiac output at: 3.5–6.5 L/min and ECMO flow rate at: 2–6 L/min. We analysed recirculation fraction (Rf), time-averaged wall shear stress (TAWSS), pressure, velocity, and turbulent kinetic energy (TKE) and extracorporeal flow fraction (EFF = ECMO flow rate/CO). Results: : Increased ECMO flow rate and decreased CO (high EFF) led to increased Rf (R = 0.98, log fit). Negative pressures developed in the venae cavae at low CO and high ECMO flow (high CR). Mean return cannula TAWSS was >10 Pa for all ECMO flow rates, with majority of the flow exiting the tip (94.0–95.8 %). Conclusions: : Our results underpin the strong impact of CO on VV ECMO. A simple metric like EFF, once supported by clinical data, might help predict Rf for a patient at a given ECMO flow rate. The return cannula imparts high shear stresses on the blood, largely a result of the internal diameter.
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| 6. |
- Thesleff, Alexander, 1986, et al.
(författare)
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Low plasticity burnishing improves fretting fatigue resistance in bone-anchored implants for amputation prostheses
- 2022
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Ingår i: Medical Engineering & Physics. - : Elsevier BV. - 1350-4533 .- 1873-4030. ; 100
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Tidskriftsartikel (refereegranskat)abstract
- Fretting fatigue is a common problem for modular orthopedic implants which may lead to mechanical failure of the implant or inflammatory tissue responses due to excessive release of wear debris. Compressive residual stresses at the contacting surfaces may alleviate the problem. Here we investigate the potential of a surface enhancement method known as low plasticity burnishing (LPB) to increase the fretting fatigue resistance of bone-anchored implants for skeletal attachment of limb prostheses. Rotation bending fatigue tests performed on LPB treated and untreated test specimens demonstrate that the LPB treatment leads to statistically significantly increased resistance to fretting fatigue (LPB treated test specimens withstood on average 108,780 load cycles as compared with 37,845 load cycles for untreated test specimens, p = 0.004). LPB treated test specimens exhibited less wear at the modular interface as compared with untreated test specimens. This surface treatment may lead to reduced risk of fretting induced component failure and a reduced need for revision of implant system componentry.
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| 7. |
- Yadav, Priti, 1985-, et al.
(författare)
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Influence of loading direction due to physical activity on proximal femoral growth tendency
- 2021
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Ingår i: Medical Engineering and Physics. - : Elsevier BV. - 1350-4533 .- 1873-4030. ; 90, s. 83-91
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Tidskriftsartikel (refereegranskat)abstract
- Longitudinal bone growth is regulated by mechanical forces arising from physical activity, whose directions and magnitudes depend on activity kinematics and intensity. This study aims to investigate the influence of common physical activities on proximal femoral morphological tendency due to growth at the femoral head growth plate. A subject-specific femur model based on magnetic resonance images of one able-bodied 6-year old child was developed, and the directions of hip contact force were described as load samples at a constant magnitude. Finite element analysis was performed to predict growth rate and growth direction, and expected changes in neck-shaft angle and femoral anteversion were computed corresponding to circa 4 months of growth. For most loading conditions, neck-shaft angle and femoral anteversion decreased during growth, corresponding to the femur & rsquo;s natural course during normal growth. The largest reduction in neck-shaft angle and femoral anteversion was approximately 0.25 degrees and 0.15 degrees. Our results suggest that most common physical activities induce the expected morphological changes in normal growth in able-bodied children. Understanding the influence of contact forces during less common activities on proximal femoral development might provide improved guidelines and treatment planning for children who have or are at risk of developing a femoral deformity.
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| 8. |
- Öhberg, Fredrik, 1969-, et al.
(författare)
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Comparison between two mobile applications measuring shoulder elevation angle–A validity and feasibility study
- 2021
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Ingår i: Medical Engineering and Physics. - : Elsevier. - 1350-4533 .- 1873-4030. ; 98, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Pain in the shoulder complex affects the working population where work with elevated arms is a risk factor. The aim of the present study was to compare a mobile application for measurements of arm elevation, ErgoExposure, against an existing mobile application, ErgoArmMeter, in a laboratory setting and to test the feasibility in a field trial. Eleven persons performed three tasks in the laboratory setting: static, dynamic, and simulated work tasks, where the applications were validated against an optical tracking system (OTS). Also, ErgoExposure was tested by a teacher in a real-world situation. Limits of agreement for the static task varied between -6.1° to 4.2° (ErgoExposure) and between -7.6° to 5.2° (ErgoArmMeter). The average root mean square difference for dynamic and simulated work tasks was 3.4° (ErgoExposure) and 7.7° (ErgoArmMeter). From the field trial, different work tasks produced distinct exposure variation analysis patterns. Both apps showed similar results compared to OTS, but ErgoExposure was more accurate than ErgoArmMeter.
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| 9. |
- Kok, Joeri, et al.
(författare)
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Augmenting a dynamic hip screw with a calcium sulfate/hydroxyapatite biomaterial
- 2021
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Ingår i: Medical Engineering and Physics. - : Elsevier BV. - 1350-4533. ; 92, s. 102-109
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Tidskriftsartikel (refereegranskat)abstract
- Internal fixation failure in hip fractures can lead to reoperation. Calcium sulfate/hydroxyapatite (CaS/HA) is a biomaterial that can be used for augmenting fracture fixation. We aimed to determine whether an injection of 2 ml CaS/HA increases the fixation of a dynamic hip screw inserted in synthetic and human trabecular bone. The study consists of two parts: 1) synthetic bone blocks (n = 74), with three subgroups: empty (cannulated screw, no injection), cannulated, and fenestrated; and 2) osteoporotic human femoral heads (n = 29), with the same subgroups. The heads were imaged using µCT. Bone volume fraction, insertion angle, and head diameter were measured. Pullout tests were performed and peak force, stiffness, and work were measured. The fenestrated group showed increases in pullout strength compared to no injection in the synthetic blocks. The cannulated group showed a higher pullout strength in low-density blocks. In the femoral heads, the variation was larger and there were no significant differences between groups. The bone volume fraction correlated with the peak force and work, and the insertion angle correlated with the stiffness. CaS/HA can improve the fixation of a dynamic hip screw. For clinical use, spreading of the material around the threads of the screw must be ensured.
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