BACKGROUND:Osteoporosis is a common comorbidity in patients with knee osteoarthritis.The impact of osteoporosis on the prognosis of unicompartmental knee arthroplasty is a trending topic of current research. OBJECTIVE:To investigate the effect of different bone densities on the stress value and stress distribution of each structure in the joint after unicompartmental knee arthroplasty using finite element analysis,and to evaluate the correlation between osteoporosis and complications. METHODS:CT and MRI were adopted to obtain the lower limb image data of a volunteer.Geomagic Studio,Ansys workbench,and Mimics were used to establish a finite element model of the knee joint with normal sclerotin condition(T-value≥-1.0).The finite element model of the knee joint with osteopenia(-2.5

Objective To obtain a more suitable puncture method for venipuncture robot through experiments.Methods By using different puncture speeds and angles for biomimetic materials, the force-time curves by various puncture methods were obtained. Results During puncture process, with the increase of the puncture angle, a smaller puncture force was required. The faster puncture speed would lead to a larger puncture force. Conclusions The 40°-45° puncture angleand the 120-300 mm/min puncture speed should be used for designing the puncture method of venipuncture robot. The results provide references for selecting the puncture angle and speed of the venipuncture robot.

Objective To design and develop an in vitro simulation device for circumferential stress of mural coronary artery, so as to achieve the in vitro loading of mural circumferential stress under coronary myocardial bridge oppression with different degrees. MethodsUsing the in vitro simulation device for myocardial bridge coronary artery hemodynamics, the in vitro measurement of mural circumferential stress was achieved. Based on the experimental data, the in vitro loading of mural circumferential stress under coronary myocardial bridge oppression with different degrees was achieved. Results The in vitro measurement experiment showed that the maximum, average and fluctuation of circumferential stress at proximal end of mural coronary artery would increase significantly with the increase in the degree of myocardial bridge oppression. The in vitro loading experiment of mural circumferential stress verified that the loading waveform coincided basically with the experimental waveform from in vitro measurement. Conclusions The device could realize the in vitro loading of mural circumferential stress, which provided an in vitro simulation platform which was as close as possible to the in vivo environment, so as to explore the influence from hemodynamic abnormality of proximal mural coronary artery on the occurrence of atherosclerosis and plaque rupture.

OBJECTIVE: To investigate the effect of Kartogenin (KGN) combined with adipose-derived stem cells (ADSCs) on tendon-bone healing after anterior cruciate ligament (ACL) reconstruction in rabbits. METHODS: After the primary ADSCs were cultured by passaging, the 3rd generation cells were cultured with 10 μmol/L KGN solution for 72 hours. The supernatant of KGN-ADSCs was harvested and mixed with fibrin glue at a ratio of 1∶1; the 3rd generation ADSCs were mixed with fibrin glue as a control. Eighty adult New Zealand white rabbits were taken and randomly divided into 4 groups: saline group (group A), ADSCs group (group B), KGN-ADSCs group (group C), and sham-operated group (group D). After the ACL reconstruction model was prepared in groups A-C, the saline, the mixture of ADSCs and fibrin glue, and the mixture of supernatant of KGN-ADSCs and fibrin glue were injected into the tendon-bone interface and tendon gap, respectively. ACL was only exposed without other treatment in group D. The general conditions of the animals were observed after operation. At 6 and 12 weeks, the tendon-bone interface tissues and ACL specimens were taken and the tendon-bone healing was observed by HE staining, c-Jun N-terminal kinase (JNK) immunohistochemical staining, and TUNEL apoptosis assay. The fibroblasts were counted, and the positive expression rate of JNK protein and apoptosis index (AI) were measured. At the same time point, the tensile strength test was performed to measure the maximum load and the maximum tensile distance to observe the biomechanical properties. RESULTS: Twenty-eight rabbits were excluded from the study due to incision infection or death, and finally 12, 12, 12, and 16 rabbits in groups A-D were included in the study, respectively. After operation, the tendon-bone interface of groups A and B healed poorly, while group C healed well. At 6 and 12 weeks, the number of fibroblasts and positive expression rate of JNK protein in group C were significantly higher than those of groups A, B, and D (P<0.05). Compared with 6 weeks, the number of fibroblasts gradually decreased and the positive expression rate of JNK protein and AI decreased in group C at 12 weeks after operation, with significant differences (P<0.05). Biomechanical tests showed that the maximum loads at 6 and 12 weeks after operation in group C were higher than in groups A and B, but lower than those in group D, while the maximum tensile distance results were opposite, but the differences between groups were significant (P<0.05). CONCLUSION After ACL reconstruction, local injection of a mixture of KGN-ADSCs and fibrin glue can promote the tendon-bone healing and enhance the mechanical strength and tensile resistance of the tendon-bone interface.
Animals ; Rabbits ; Adipocytes ; Anterior Cruciate Ligament Reconstruction ; Fibrin Tissue Adhesive/therapeutic use* ; Stem Cells

Objective To propose a new multi-joint series venipuncture system, explore the mechanics and kinematics-based related control problems involved in needle insertion and needle picking during the puncture process, and verify feasibility of this system. Methods A puncture manipulator was built, and needle displacement control algorithm was proposed by combing with the puncture mechanics model. The the forward kinematics was calculated by using DH method, so as to obtain the tip coordinates. Then the inverse kinematics was calculated by using the geometric method. The forward and inverse processes were closely connected. The position error of the end coordinates before and after needle picking was compared by using the method of kinematics positive solution-inverse solution-re-positive solution. Finally, experimental verification and simulation were conducted by combining with the physical object. Results Through simulation and experiments, accuracy of the theoretical model was verified. The needle insertion algorithm could be used to achieve success with only one needle insertion, which provided theoretical basis for the control of robot arm. The position error before and after needle picking could be controlled within 1 mm from the end trajectory. The end needle tip of robot arm was almost kept fixed during the needle picking process. Therefore, this needle picking scheme was feasible and could basically verify that the needle picking action of robot arm met the accuracy and safety requirements. Conclusions The venipuncture manipulator truly simulates the needle insertion and needle picking action during the puncture process, and can safely and accurately realize the needle insertion and needle picking action with needle tip as the fixed point, indicating that it has certain clinical value.