Structural Design and Finite Element Simulation Analysis of Grade 3 Graded Porous Titanium Implant.

The metal titanium is often used as a dental implant material, and the elastic modulus of solid titanium implants does not match the biological bone tissue, which can easily produce a stress shielding effect and cause implant failure. In this paper, a three-level gradient porous structure implant was designed, and its mechanical and biological adaptability were studied by finite element simulation analysis. Combined with the comprehensive evaluation of the mechanical and biological properties of implants of various structures, the analysis found that a porous implant with porosity of 59.86% of the gradient was the best structure. The maximum equivalent stress of this structure in the mandible that simulated the oral environment was 154.34 MPa, which was less than half of its theoretical compression yield strength. The strain of the surrounding bone tissue lies in the bone compared with other structures, the proportion of the active state of plastic construction is larger, at 10.51%, and the fretting value of this structure and the bone tissue interface is the smallest, at only 10 µm.

[Effect of electroacupuncture on the multifidus muscle in patients with lumbar disc herniation].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on lumbar dysfunction and multifidus muscle characteristics in patients with lumbar disc herniation (LDH). METHODS: Sixty patients with LDH were randomly divided into an observation group and a control group, 30 cases in each group. The patients in the control group were treated with symptomatic treatment. On the basis of the treatment of the control group, the patients in the observation group were treated with acupuncture at L3-S1 Jiaji (Ex-B 2) and Dachangshu (BL 25), and the ipsilateral L3 and L5 Jiaji point were connected with EA (continuous wave, frequency of 20 Hz, and the intensity was appropriate to the patient's tolerance). The needles were retained for 20 min, once every other day, and 10 times were taken as a course of treatment. A total of 2 courses of treatment was given. The modified Oswestry disability index (ODI) as well as the physical component summary (PCS) and mental component summary (MCS) of the 36-item short form health survey (SF-36) were compared between the two groups before and after treatment. Lumbar MRI was performed before and after treatment to measure the cross-sectional area (CSA), fatty infiltration (FI) and T2 values of multifidus muscle at the lower edge of L4 and L5 vertebral bodies. RESULTS: After treatment, the ODI, PCS and MCS socres in the two groups were improved compared with those before treatment (P<0.05), and the ODI and PCS socres in the observation group were better than those in the control group (P<0.05). After treatment, the FI and value of T2 in the observation group were lower than those before treatment (P<0.05), and lower than those in the control group (P<0.05). CONCLUSION: EA could improve lumbar dysfunction, relieve edema and fatty infiltration of multifidus muscle in patients with LDH.