Biomechanical optimization scheme of artificial ankle inserts based on porous structure design / 中国组织工程研究

BACKGROUND:Prosthesis loosening and wear are still the main problems in the failure of total ankle replacement,which are closely related to the micro-motion of the implant-bone interface,the contact stress of the articular surface and joint motion.The design of artificial joint components,including insert and tibial/talar stem prosthesis,is a key factor affecting the force,motion,and micromotion of the contact interface of the ankle joint.The development of new inserts is of great significance to improve the survival rate of artificial ankle joints. OBJECTIVE:The finite element model of the total ankle replacement model was constructed to detect the biomechanical properties of the porous structure-optimized inserts,and the effect of the porous structure-optimized inserts on reducing prosthesis micromotion and improving the contact behavior of the articular surface was analyzed. METHODS:Based on the CT scan data of the right ankle joint of a healthy adult and the INBONE Ⅱ system product manual,a three-dimensional model including bone and artificial joint system was established,and the total ankle replacement model(model A)was obtained after osteotomy and prosthesis installation,and then through four new types of inserts,G50,G60,D50,and D60,were obtained by transforming the porous structure of the original insert,and the original one was replaced with different inserts to establish an optimized total ankle replacement model(models B-E)corresponding to the inserts.The gait loads were applied on the five models to simulate the gait conditions.The differences in micromotion and articular surface contact behaviors at the implant-bone interface of all five models were compared. RESULTS AND CONCLUSION:(1)In the gait cycle,the micromotion of the prosthesis of the four optimized total ankle replacement models was lower than that of the original model.Compared with model A,the micromotion of the prosthesis in models B-E decreased by 5.4%,10.1%,8.1%,and 20.9%,respectively.The high micromotion area of t ??he tibial groove dome in the optimized model was significantly smaller than that of the original model.(2)The four optimized models obtained a larger articular surface contact area.Compared with model A,the average contact area of t ??he inserts in models B-E increased by 11.8%,14.7%,8.1%,and 32.6%,respectively.(3)Similar to the effect of increasing the contact area,compared with the original model,the contact stress of the optimized model decreased in varying degrees,and the value of model E decreased the most significantly(P<0.05),it is due to good mechanical properties and large porosity of the Diamond lattice that constitutes the D60-type insert.(4)The research results show that the use of porous structure to improve the inserts can improve the elasticity of the inserts and increase its ability to absorb joint impact,for favorable conditions are created for reducing micromotion at the implant-bone interface and improving joint contact behavior.

Finite element analysis of artificial ankle elastic improved inserts / 中国修复重建外科杂志

OBJECTIVE@#To discuss the influence of artificial ankle elastic improved inserts (hereinafter referred to as "improved inserts") in reducing prosthesis micromotion and improving joint surface contact mechanics by finite element analysis.@*METHODS@#Based on the original insert of INBONE Ⅱ implant system (model A), four kinds of improved inserts were constructed by adding arc or platform type flexible layer with thickness of 1.3 or 2.6 mm, respectively. They were Flying goose type_1.3 elastic improved insert (model B), Flying goose type_2.6 elastic improved insert (model C), Platform type_1.3 elastic improved insert (model D), Platform type_2.6 elastic improved insert (model E). Then, the CT data of right ankle at neutral position of a healthy adult male volunteer was collected, and finite element models of total ankle replacement (TAR) was constructed based on model A-E prostheses by software of Mimics 19.0, Geomagic wrap 2017, Creo 6.0, Hypermesh 14.0, and Abaqus 6.14. Finally, the differences of bone-metal prosthesis interface micromotion and articular surface contact behavior between different models were investigated under ISO gait load.@*RESULTS@#The tibia/talus-metal prosthesis interfaces micromotion of the five TAR models gradually increased during the support phase, then gradually fell back after entering the swing phase. The improved models (models B-E) showed lower bone-metal prosthesis interface micromotion when compared with the original model (model A), but there was no significant difference among models A-E ( P>0.05). The maximum micromotion of tibia appeared at the dome of the tibial bone groove, and the ​​micromotion area was the largest in model A and the smallest in model E. The maximum micromotion of talus appeared at the posterior surface of the central bone groove, and there was no difference in the micromotion area among models A-E. The contact area of the articular surface of the insert/talus prosthesis in each group increased in the support phase and decreased in the swing phase during the gait cycle. Compared with model A, the articular surface contact area of models B-E increased, but there was no significant difference among models A-E ( P>0.05). The change trend of the maximum stress on the articular surface of the inserts/talus prosthesis was similar to that of the contact area. Only the maximum contact stress of the insert joint surface of models D and E was lower than that of model A, while the maximum contact stress of the talar prosthesis joint surface of models B-E was lower than that of model A, but there was no significant difference among models A-E ( P>0.05). The high stress area of the lateral articular surface of the improved inserts significantly reduced, and the articular surface stress distribution of the talus prosthesis was more uniform.@*CONCLUSION@#Adding a flexible layer in the insert can improve the elasticity of the overall component, which is beneficial to absorb the impact force of the artificial ankle joint, thereby reducing interface micromotion and improving contact behavior. The mechanical properties of the inserts designed with the platform type and thicker flexible layer are better.

Human acellular amniotic membrane scaffolds encapsulating juvenile cartilage fragments accelerate the repair of rabbit osteochondral defects.

AIMS: The purpose of this study was to explore a simple and effective method of preparing human acellular amniotic membrane (HAAM) scaffolds, and explore the effect of HAAM scaffolds with juvenile cartilage fragments (JCFs) on osteochondral defects. METHODS: HAAM scaffolds were constructed via trypsinization from fresh human amniotic membrane (HAM). The characteristics of the HAAM scaffolds were evaluated by haematoxylin and eosin (H&E) staining, picrosirius red staining, type II collagen immunostaining, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Human amniotic mesenchymal stem cells (hAMSCs) were isolated, and stemness was verified by multilineage differentiation. Then, third-generation (P3) hAMSCs were seeded on the HAAM scaffolds, and phalloidin staining and SEM were used to detect the growth of hAMSCs on the HAAM scaffolds. Osteochondral defects (diameter: 3.5 mm; depth: 3 mm) were created in the right patellar grooves of 20 New Zealand White rabbits. The rabbits were randomly divided into four groups: the control group (n = 5), the HAAM scaffolds group (n = 5), the JCFs group (n = 5), and the HAAM + JCFs group (n = 5). Macroscopic and histological assessments of the regenerated tissue were evaluated to validate the treatment results at 12 weeks. RESULTS: In vitro, the HAAM scaffolds had a network structure and possessed abundant collagen. The HAAM scaffolds had good cytocompatibility, and hAMSCs grew well on the HAAM scaffolds. In vivo, the macroscopic scores of the HAAM + JCFs group were significantly higher than those of the other groups. In addition, histological assessments demonstrated that large amounts of hyaline-like cartilage formed in the osteochondral defects in the HAAM + JCFs group. Integration with surrounding normal cartilage and regeneration of subchondral bone in the HAAM + JCFs group were better than those in the other groups. CONCLUSION: HAAM scaffolds combined with JCFs promote the regenerative repair of osteochondral defects. Cite this article: Bone Joint Res 2022;11(6):349-361.

Research progress in molecular coupling mechanism of osteogenic differentiation and angiogenesis in traumatic bone defects / 中华创伤杂志

Management of bone defects caused by fractures，bone tumors or infections is clinically difficult as well as a hot topic in current studies. With further researches over bone defects，the construction of tissue-engineered bone has played a great role in the treatment of bone defects. Blood vessels not only provide the necessary nutritional mineral salts，growth factors，hormones for bone formation，also are able to mediate the interaction among osteoblasts and osteoclasts，osteocytes，bone autonomic nerve and endothelial cells，since bone formation exist spatially and temporally connection with angiogenesis. Therefore，the authors make a systematic literature review on the research progress of the coupling mechanism of angiogenesis and osteogenic differentiation，blood vessels and related signal pathways on osteogenic differentiation and angiogenesis-related molecules in osteogenic differentiation during the process of traumatic bone defects，so as to provide new ideas for the treatment of bone defects.

Application of human acelluar amniotic membrane in tissue engineered scaffold construction / 中国组织工程研究

BACKGROUND: Human acellular amniotic membrane is a kind of extracellular matrix material with good biocompatibility and biological activity. It has been widely used in various clinical studies because of its low immunogenicity, small rejection and easy preparation.OBJECTIVE: To review the applications of human acellular amniotic membranes in tissue engineering field, such as skin, blood vessel, cornea, cartilage and bone.METHODS: CNKI (from January 2005 to May 2017), CBMdisc (from January 2005 to May 2017), PubMed (from January 1990 to May 2017) and Elsevier (from January 1990 to May 2017) were retrieved for articles addressing the application of human acellular amniotic membrane as a tissue-engineered scaffold in the bone, cartilage, skin, and blood vessels.The keywords were acelluar amniotic membrane, scaffold, material, tissue engineering ECM in Chinese and English, respectively.RESULTS AND CONCLUSION: Human acellular amniotic membrane owns the structure and function of the natural extracellular matrix, which can be combined with stem cells from different sources to differentiate into different tissues and organs, such as bone, cartilage, skin, blood vessel, and corneal tissues. As a tissue-engineered scaffold, human acellular amniotic membrane has good biocompatibility, biodegradability and low immunogenicity, although it has some shortcomings, such as poor strength and post-transplantation rejection reactions. Therefore, the future studies are mainly focused on shortening the adhesion time between cells and scaffolds, increasing the own mechanical strength of human acellular amniotic membrane, optimizing the cell growth microenvironment, and combining human acellular amniotic membrane with other tissue-engineered scaffolds.