Annals of Biomedical Engineering

Eslami, Parastou; Hartman, Eline M. J.; Albaghadai, Mazen; Karady, Julia; Jin, Zexi; Thondapu, Vikas; Cefalo, Nicholas V.; Lu, Michael T.; Coskun, Ahmet; Stone, Peter H.; Marsden, Alison; Hoffmann, Udo; Wentzel, Jolanda J.

doi: 10.1007/s10439-020-02631-9pmid: 33067688

Endothelial shear stress (ESS) identifies coronary plaques at high risk for progression and/or rupture leading to a future acute coronary syndrome. In this study an optimized methodology was developed to derive ESS, pressure drop and oscillatory shear index using computational fluid dynamics (CFD) in 3D models of coronary arteries derived from non-invasive coronary computed tomography angiography (CTA). These CTA-based ESS calculations were compared to the ESS calculations using the gold standard with fusion of invasive imaging and CTA. In 14 patients paired patient-specific CFD models based on invasive and non-invasive imaging of the left anterior descending (LAD) coronary arteries were created. Ten patients were used to optimize the methodology, and four patients to test this methodology. Time-averaged ESS (TAESS) was calculated for both coronary models applying patient-specific physiological data available at the time of imaging. For data analysis, each 3D reconstructed coronary artery was divided into 2 mm segments and each segment was subdivided into 8 arcs (45°).TAESS and other hemodynamic parameters were averaged per segment as well as per arc. Furthermore, the paired segment- and arc-averaged TAESS were categorized into patient-specific tertiles (low, medium and high). In the ten LADs, used for optimization of the methodology, we found high correlations between invasively-derived and non-invasively-derived TAESS averaged over segments (n = 263, r = 0.86) as well as arcs (n = 2104, r = 0.85, p < 0.001). The correlation was also strong in the four testing-patients with r = 0.95 (n = 117 segments, p = 0.001) and r = 0.93 (n = 936 arcs, p = 0.001).There was an overall high concordance of 78% of the three TAESS categories comparing both methodologies using the segment- and 76% for the arc-averages in the first ten patients. This concordance was lower in the four testing patients (64 and 64% in segment- and arc-averaged TAESS). Although the correlation and concordance were high for both patient groups, the absolute TAESS values averaged per segment and arc were overestimated using non-invasive vs. invasive imaging [testing patients: TAESS segment: 30.1(17.1–83.8) vs. 15.8(8.8–63.4) and TAESS arc: 29.4(16.2–74.7) vs 15.0(8.9–57.4) p < 0.001]. We showed that our methodology can accurately assess the TAESS distribution non-invasively from CTA and demonstrated a good correlation with TAESS calculated using IVUS/OCT 3D reconstructed models.

Benitez, Jessica; Fontanarosa, Davide; Wang, Jiaqiu; Paritala, Phani Kumari; McGahan, Tim; Lloyd, Thomas; Li, Zhiyong

doi: 10.1007/s10439-020-02655-1pmid: 33079320

Acute cerebral ischemic events and thrombosis are associated with the rupture/erosion of carotid atherosclerotic plaques. The aim of the present study was to determine the impact of calcification deposition on the wall shear stress (WSS) and stresses within the plaques using 3D fluid–structure interaction (FSI) models. Six patients with calcified carotid atherosclerosis underwent multisequence magnetic resonance imaging (MRI) and were divided into three groups according to the calcification volume. To evaluate the role of the calcification deposition on the stresses, the calcification content was replaced by lipids and arterial tissue, respectively. By comparing the results from the simulation with calcification, and when changing it to lipids there was a significant increment in the stresses at the fibrous cap (p = 0.004). Instead, by changing it to arterial tissue, there was no significant difference (p = 0.07). The calcification shapes that presented the highest stresses were thin concave arc-shaped (AS1) and thin convex arc-shaped (AS3), with mean stress values of 107 ± 54.2 and 99.6 ± 23.4 kPa, respectively. It was also observed that, the calcification shape has more influence on the level of stress than its distance to the lumen. Higher WSS values were associated with the presence of calcification. Calcification shape plays an important role in producing high stresses in the plaque. This work further clarifies the impact of calcification on plaque vulnerability.

Thomeer, Lucas; Guan, Shanyuanye; Gray, Hans; Schache, Anthony; de Steiger, Richard; Pandy, Marcus

doi: 10.1007/s10439-020-02646-2pmid: 33094419

The purpose of this study was to measure the three-dimensional movements of the femur, tibia and patella in healthy young people during activities of daily living. A mobile biplane X-ray imaging system was used to obtain simultaneous measurements of six-degree-of-freedom (6-DOF) tibiofemoral and patellofemoral kinematics and femoral condylar motion in ten participants during standing, level walking, downhill walking, stair ascent, stair descent and open-chain (non-weightbearing) knee flexion. Seven of the eleven secondary motions at the knee—three translations at the tibiofemoral joint, three translations at the patellofemoral joint, and patellar flexion—were coupled to the tibiofemoral flexion angle (r2 ≥ 0.71). Tibial internal–external rotation, tibial abduction–adduction, patellar rotation, and patellar tilt were each weakly related to the tibiofemoral flexion angle (r2 ≤ 0.45). The displacements of the femoral condyles were also coupled to the tibiofemoral flexion angle (r2 ≥ 0.70), with the lateral condyle translating further on the tibial plateau than the medial condyle. The center of rotation of the tibiofemoral joint in the transverse plane was located on the medial side in all activities. These findings expand our understanding of the kinematic function of the healthy knee and may be relevant to a range of applications in biomechanics, including the design of prosthetic knee implants and the development of knee models for use in full-body simulations of movement.

Vakiel, Paris; Dennison, Christopher R.; Shekarforoush, Mehdi; Scott, Michael; Hart, David A.; Shrive, Nigel G.

doi: 10.1007/s10439-020-02652-4pmid: 33094418

Changes in stress transferred across articular joints have been described as a substantial factor in the initiation and progression of joint disease such as post-traumatic osteoarthritis and have thus been of interest to biomechanical researchers. However, to date, stress magnitudes within the menisci have not been successfully measured. In this study, a novel method for measuring stress within the menisci is presented. Small Fibre Bragg Grating (FBG) sensors were inserted inside menisci and used to measure mechanical stress during replicated gait cycles. In-vitro stress measurements within the menisci were preformed for healthy gait and gait following surgical damage to the joints. Together with our capability to reproduce in vivo motions accurately, the improvements in fibre optic technology have allowed for the first direct measurement of mechanical stress in menisci.

Blázquez-Carmona, Pablo; Mora-Macías, Juan; Morgaz, Juan; Fernández-Sarmiento, José Andrés; Domínguez, Jaime; Reina-Romo, Esther

doi: 10.1007/s10439-020-02665-zpmid: 33111968

Bone lengthening and bone transport are regeneration processes that commonly rely on distraction osteogenesis, a widely accepted surgical procedure to deal with numerous bony pathologies. Despite the extensive study in the literature of the influence of biomechanical factors, a lack of knowledge about their mechanobiological differences prevents a clinical particularization. Bone lengthening treatments were performed on sheep metatarsus by reproducing the surgical and biomechanical protocol of previous bone transport experiments. Several in vivo monitoring techniques were employed to build an exhaustive comparison: gait analysis, radiographic and CT assessment, force measures through the fixation, or mechanical characterization of the new tissue. A significant initial loss of the bearing capacity, quantified by the ground reaction forces and the limb contact time with the ground, is suffered by the bone lengthening specimens. The potential effects of this anomaly on the musculoskeletal force distribution and the evolution of the bone callus elastic modulus over time are also analyzed. Imaging techniques also seem to reveal lower bone volume in the bone lengthening callus than in the bone transport one, but an equivalent mineralization rate. The simultaneous quantification of biological and mechanical parameters provides valuable information for the daily clinical routine and numerical tools development.

Jazinizadeh, Fatemeh; Quenneville, Cheryl E.

doi: 10.1007/s10439-020-02670-2pmid: 33123827

Due to the adverse impacts of hip fractures on patients’ lives, it is crucial to enhance the identification of people at high risk through accessible clinical techniques. Reconstructing the 3D geometry and BMD distribution of the proximal femur could be beneficial in enhancing hip fracture risk predictions; however, it is associated with a high computational burden. It is also not clear whether it provides a better performance than 2D model analysis. Therefore, the purpose of this study was to compare the 2D and 3D model reconstruction’s ability to predict hip fracture risk in a clinical population of patients. The DXA scans and CT scans of 16 cadaveric femurs were used to create training sets for the 2D and 3D model reconstruction based on statistical shape and appearance modeling. Subsequently, these methods were used to predict the risk of sustaining a hip fracture in a clinical population of 150 subjects (50 fractured, and 100 non-fractured) that were monitored for five years in the Canadian Multicentre Osteoporosis Study. 3D model reconstruction was able to improve the identification of patients who sustained a hip fracture more accurately than the standard clinical practice (by 40%). Also, the predictions from the 2D statistical model didn’t differ significantly from the 3D ones (p > 0.76). These results indicated that to enhance hip fracture risk prediction in clinical practice implementing 2D statistical modeling has comparable performance with lower associated computational load.