Bio-Medical Materials and Engineering - Volume 32, issue 6

Authors: Lee, Jin-Ah | Koh, Yong-Gon | Kang, Kyoung-Tak

Article Type: Research Article

Abstract: BACKGROUND: The post-cam mechanism in the posterior-stabilized (PS) implant plays an important role, such as durability and kinematic performances, in total knee arthroplasty (TKA). OBJECTIVE: The purpose of this study was to evaluate the difference in the kinematics and contact stress of five post-cam designs, which are flat-and-flat, curve-and-curve (concave), curve-and-curve (concave and convex), helical, and asymmetrical post-cam designs, using three-dimensional finite element models. METHODS: We designed the post-cam model with five different geometries. The kinematics, contact stress, and contact area were evaluated in the five post-cam designs under gait cycle loading conditions using the finite …element method. RESULTS: There were no differences in the contact stress and area on the tibial insert in all designs. The largest internal rotation was shown in the swing phase for the helical design, and the largest tibial posterior translation was observed for the curve-and-curve (concave) design. The curve-and-curve (concave) design showed the lowest contact stress and the largest posterior tibial translation during the gait cycle. CONCLUSIONS: Considering the kinematics and contact stress, we found that the curve-and-curve (concave) design was more stable than other designs. From the results, we found the important factors of TKA implant considering stability and kinematics. Show more

Keywords: Total knee arthroplasty, implant, kinematics, design, gait

DOI: 10.3233/BME-201097

Citation: Bio-Medical Materials and Engineering, vol. 32, no. 6, pp. 323-332, 2021

Authors: Yamauchi, Yoshikane | Saito, Yuichi | Yasuda, Atsushi | Shirai, Suguru | Kondo, Hiroshi | Uehara, Hirofumi | Sakao, Yukinori | Kawamura, Masafumi | Yokobori, Toshimitsu | Tanuma, Tadashi

Article Type: Research Article

Abstract: BACKGROUND: Thoracic CO2 insufflation with positive intrathoracic pressure is usually effective during thoracoscopic surgery, however, lung collapse is sometimes insufficient. We hypothesized that inappropriate bronchial collapse might cause this unsuccessful lung collapse. OBJECTIVE: The objective of this study was to construct a computational mechanical model of bronchi for practical simulation to discover the optimal conditions of positive intrathoracic pressure during thoracoscopic surgery. METHODS: Micro-focus high-resolution X-ray computed tomography measurements of lungs from just-slaughtered swine were extracted, and the three-dimensional geometries of the bronchi under pressurized and depressurized conditions were measured accurately. The mechanical properties of …the bronchus were also measured. Computational fluid dynamics (CFD) and computational structural mechanics (CSM) analyses were conducted. RESULTS: The CSM results indicated that the present structural model could simulate bronchial occlusion. The CFD results showed that airflows from pressed lung alveoli might cause low-internal-pressure regions when suddenly or heterogeneously pushed airflow was injected from a small branching bronchus to a large bronchus. A preliminary computational mechanical model of bronchi was constructed. CONCLUSIONS: We demonstrated the performance of the mechanical model of bronchi in rough simulations of bronchial occlusions. However, this model should be verified further using human data to facilitate its introduction to clinical use. Show more

Keywords: Thoracoscopic surgery, positive intrathoracic pressure, CO2 insufflation, computational fluid dynamics, computational structural mechanics

DOI: 10.3233/BME-211228

Citation: Bio-Medical Materials and Engineering, vol. 32, no. 6, pp. 333-345, 2021

Authors: He, Jin-Mei | Zhu, Peng-Fei | Li, Li-Hua | Wang, Zhen | Li, Xiao-Li | Wang, Song | Ren, Hai-tao | Chen, Chang-Sheng | Chu, Bin | Li, Bo | Liu, Wei-Qiang

Article Type: Research Article

Abstract: BACKGROUND: Transforming growth factor-β1 (TGF-β1) plays an important role in chondrocyte growth and the synthesis of extracellular matrix (ECM). Due to the rapid metabolism, controlled release systems for TGF-β1 have attracted increasing interest recently. OBJECTIVE: In this study, a silk fibroin (SF)/chitosan (CS) scaffold incorporated with TGF-β1-loaded microspheres (MSs) was created for cartilage reparation. METHOD: The optimal proportion of the SF/CS composite scaffold was determined by evaluating their micromorphology and the proliferation rate of fibroblasts on the surface. Then, SF/CS/TGF-β1-loaded MS scaffolds were prepared by the adsorption method. TGF-β1 release capacity, degradation patterns, cytocompatibility and in …vivo implantation were evaluted. RESULTS: The SF/CS/TGF-β1-loaded MS scaffold showed good TGF-β1 release over more than 16 days, which could sequentially stimulate chondrocyte synthetic activity. In vitro cell proliferation experiments showed the SF/CS/TGF-β1-loaded MS scaffold could promote chondrocytes adhesion, growth, proliferation and maintained the cellular morphology. An in vivo study demonstrated that a low inflammatory response was observed in rats and that the materials exhibited good biocompatibility. CONCLUSION: the results indicated that our SF/CS/TGF-β1-loaded MS scaffold constitute a promising therapeutic option for cartilage reparation. Show more

Keywords: Silk fibroin, chitosan; TGF-β1, microspheres, cartilage reparation

DOI: 10.3233/BME-201178

Citation: Bio-Medical Materials and Engineering, vol. 32, no. 6, pp. 347-358, 2021

Authors: Mochizuki, Tomoharu | Sato, Takashi | Katsumi, Ryota

Article Type: Research Article

Abstract: BACKGROUND: The association between the toe angle and bony rotational factors is critical to explain issues related to the onset and progression of knee osteoarthritis (OA). OBJECTIVE: The study aimed to clarify the association between the toe angle and each of the femoral and tibial transvers direction relative to gait direction, rotational knee alignment, and bony torsional deformity for the subjects with knee OA. METHODS: This study evaluated 58 knees in 24 healthy elderly (72 ± 5 years) and 34 varus knee OA (72 ± 6 years). A three-dimensional (3D) assessment system was used on 3D …models and biplanar long-leg radiographs with the toe angle reflecting gait direction, applying a 3D-to-2D image registration technique. The main parameters on the transverse plane were: (1) toe angle, (2) transverse direction of the femur and tibia relative to the gait direction, (3) femoral neck anteversion, (4) condylar twist angle, (5) tibial torsion, and (6) rotational knee alignment. RESULTS: The alignment parameters, except for the tibial transverse direction, were different between healthy and osteoarthritic knees. In knee OA, the femoral neck anteversion - femoral transverse direction (p = 0.001), femoral transverse direction - tibial transverse direction (p < 0.001), and tibial transverse direction - toe angle (p < 0.001) were associated. CONCLUSIONS: The osteoarthritic knees showed that the femoral neck anteversion was associated with the femoral transverse direction, which determined the tibial transverse direction by adjusting the rotational knee alignment, leading to the toe angle. Show more

Keywords: Functionally oriented alignment, toe angle, transverse bony factors, knee osteoarthritis, healthy elderly

DOI: 10.3233/BME-211245

Citation: Bio-Medical Materials and Engineering, vol. 32, no. 6, pp. 359-373, 2021

Authors: Lim, Jin Xi | He, Min | Chong, Alphonsus Khin Sze

Article Type: Research Article

Abstract: BACKGROUND: An increasing number of bone graft materials are commercially available and vary in their composition, mechanism of action, costs, and indications. OBJECTIVE: A commercially available PLGA scaffold produced using 3D printing technology has been used to promote the preservation of the alveolar socket after tooth extraction. We examined its influence on bone regeneration in long bones of New Zealand White rabbits. METHODS: 5.0-mm-diameter circular defects were created on the tibia bones of eight rabbits. Two groups were studied: (1) control group, in which the bone defects were left empty; (2) scaffold group, in which the PLGA scaffolds …were implanted into the bone defect. Radiography was performed every two weeks postoperatively. After sacrifice, bone specimens were isolated and examined by micro-computed tomography and histology. RESULTS: Scaffolds were not degraded by eight weeks after surgery. Micro-computed tomography and histology showed that in the region of bone defects that was occupied by scaffolds, bone regeneration was compromised and the total bone volume/total volume ratio (BV/TV) was significantly lower. CONCLUSION: The implantation of this scaffold impedes bone regeneration in a non-critical bone defect. Implantation of bone scaffolds, if unnecessary, lead to a slower rate of fracture healing. Show more

Keywords: Bone substitute, bone graft, bone defect, Poly-Lactic Co-Glycolic Acid

DOI: 10.3233/BME-216017

Citation: Bio-Medical Materials and Engineering, vol. 32, no. 6, pp. 375-381, 2021