Objective To study topological structure of a new type of three-dimensional (3D) printed height increasing insoles for leg length discrepancy (LLD) and its effect on biomechanics of lower limbs. Methods Topological structure for middle and rear part of the insole was optimized by solid isotropic microstructures with penalization (SIMP), the force was loaded and the boundary conditions were set according to force area of the insole, and the height increasing insole with thermoplastic polyurethanes (TPU) materials was printed by selected laser sintering (SLS). The insoles were used in 9 patients with LLD, visual analogue scale (VAS) and Maryland foot function scores were used to compare pain and foot function changes of patients before and after using the insole, and the 3D gait analysis system was used to compare spatiotemporal parameters and vertical ground reaction force (vGRF) of both lower limbs. Result sAfter the patient wore 3D printed insole, VAS scores decreased, Maryland foot function scores increased, vGRF of both lower limbs decreased, and the difference of cadence, stance phase and swing phase in both lower limbs decreased. Conclusions The 3D printed height increasing insole after topology optimization can improve coordination of lower limb movement, reduce ground impact, relieve pain and improve foot function, thus providing an effective personalized orthopedic plan for LLD treatment in clinic.

Objective To evaluate the biomechanical properties of 3D printed individualized titanium alloy pelvic prosthesis in static and gait states by the method of finite element analysis. Methods Three patients with different types of pelvic tumors were treated by hemi-pelvic arthroplasty with resection of hemi-pelvis. CT and MRI were performed before the surgery, and the corresponding individualized titanium alloy pelvic prostheses were designed. The pelvic models were reconstructed with 3D reconstruction technique, and then assembled with the individualized pelvic prostheses. The human skeletal muscle model was established by AnyBody software to perform gait dynamics analysis. The stress distribution and stress concentration areas of 3 reconstructed pelvic models in static and gait states were obtained by ABAQUS. Results Under both static and gait conditions, the maximum stress of the 3 pelvic prostheses was smaller than the yield strength of the titanium alloy. The pelvic ring of the reconstructed pelvis could meet the rule of stress conduction. The patients’ daily life returned to normal condition after the surgery. Conclusions The effect of 3D prosthetic titanium prosthesis on recovery of pelvic ring is satisfactory, and its effectiveness and stability can meet the requirement of human biomechanics. The analytic results can provide references for clinicians and prosthesis designers.

Objective To establish a three-dimensional(3D) finite element model of cervical vertebrae (C1-7), and study its biomechanical properties under muscle force by cervical traction, so as to provide references for clinical treatment. Methods On the basis of nonlinear finite element model of normal cervical vertebrae and combined with clinical traction methods, cervical traction at the extension angle of 0°, 10°, 20°, 30°, 40° under the same traction weight, was simulated by finite element analysis (FEA) software to obtain and select the joint force and muscle force that were appropriate for FEA on the model. Results In the process of cervical extension by traction, under the muscle force, the average maximum equivalent stress of cervical vertebrae, intervertebral disc and uncovertebral joints increased by 4.86, 1.79, 0.69 MPa, respectively, and the average maximum relative displacement of cervical vertebrae in sagittal and vertical axis direction increased by 11.1, 1.26 mm, respectively. The biomechanical properties of cervical traction were similar to the FEA results reported in the literature. Conclusions Neck muscles play an active role in promoting the stress and displacement of cervical vertebrae, intervertebral discs and uncovertebral joints and it should be taken into consideration when performing cervical traction in clinic. In addition, the traction angle should not be too large: 0°-20° is generally recommended as a relatively safe angle range at the initial stage.

Objective To understand the epidemic status of clonorchiasis and awareness of prevention and control knowledge in Xinfeng County of Jiangxi Province, so as to provide the evidences for control measures. Methods The baseline survey was carried out with a clue in vestigation of raw-fish eating behavior in potential endemic areas in 2016.The residents were examined by stool tests. The metacercariae of Clonorchis sinensis in fish, the rediae and cercariae in freshwater mollusk were detected. The feces samples of cats, dogs and pigs were collected and examined by sedimentation technique. Meanwhile, the epidemic factors, health knowledge and behavior were also surveyed. Results The residents in 26 villages had the habit of eating raw freshwater fish, and 19.51% of the respondents had this habit. The average infection rates of the population, Parafossarulus striatulus, freshwater fishes and reservoir hosts were 21.56%, 0, 8.24% and 2.27%, respectively. The infection rate of the population increased with age. There was a significant positive correlation between the behavior and the infection rate of the population (r = 0.88, P < 0.01). Only 11.46% of the respondents knew that eating raw-fish might cause C. sinensis infection, and 5.28% of them knew that C. sinensis was harmful to health. Conclusions Twenty-six villages in five townships were endemic areas of clonorchiasis in Xinfeng County. The permanent solution of prevention and control of clonorchiasis is to strengthen the health education and change the habit of raw-fish eating gradually.

Objective: To examine the safety and effectiveness of a new stent graft system for endovascular repair of abdominal aortic aneurysm(AAA). Methods: This is a prospective,multi-center,single-arm clinical trial. The patients with AAA treated with a new stent graft system were enrolled at 21 centers from September 2018 to September 2019 in China. Follow-up was performed before discharge, and at 30, 180, 360 days after operation, respectively. The primary safety endpoint was the incidence of major adverse events(MAE) within 30 days. The primary efficacy endpoint was the success rate of AAA treatment at 360 days. Secondary safety endpoints were the incidence of perioperative access complications and acute lower limb ischemia,all-cause mortality, AAA related mortality and incidence of serious adverse events (SAE) at 180 and 360 days. Secondary efficacy endpoints were the incidence of type Ⅰ or Ⅲ endoleak,stent displacement,and conversion to open surgery or re-intervention at 180 and 360 days. Results: One hundred and fifty-six patients were enrolled,including 137 males and 19 females. The age was (68.9±6.9) years (range:48.2 to 84.6 years).Maximum aneurysm diameter was (50.8±11.2) mm (range:25.0 to 85.0 mm),diameter of proximal landing zone was (21.2±2.5) mm (range:17.0 to 29.5 mm),and length of proximal landing zone was (31.4±13.0) mm (range:11.0 to 75.0 mm).The incidence of MAE was 1.3% (2/156) at 30 days,both were all-cause death cases. The success rate of AAA treatment was 88.5% (138/156) at 360 days. No perioperative access complication and acute lower limb ischemia occurred. All-cause mortality was 2.0% (3/154) at 180 days and 2.6% (4/153) at 360 days,and there was no AAA related death. The incidence of SAE was 23.0%(35/152) at 180 days and 30.5%(46/151) at 360 days, and no device-related SAE occurred. The incidence of type Ⅰor Ⅲ endoleak was 3.4% (5/147) at 180 days and 3.5% (5/144) at 360 days. Conclusion: The new stent graft system is easy to operate,and early-term safety and effectiveness results are expected.
Humans ; Middle Aged ; Aged ; Aged, 80 and over ; Prospective Studies ; China ; Ischemia ; Aortic Aneurysm, Abdominal/surgery*