ABSTRACT
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.
Subject(s)
Adult , Male , Humans , Ankle , Ankle Joint/surgery , Finite Element Analysis , Tibia/surgery , Talus , Stress, Mechanical , Biomechanical PhenomenaABSTRACT
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.
ABSTRACT
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.