This paper is to report our study in which the differences between prosthetic restoration and surgical reconstruction using traditional clasp retention technology were analyzed based on three-dimensional finite element methods in our laboratory. Firstly, the maxillary unilateral defect model was developed using medical image processing software MIMICS. Secondly, the prosthesis was generated by mirroring technology. The clasp was designed according to the methods raised by Aramany. Then, the stress distribution of maxilla was calculated by simulating occlusion. According to the results, after osseointegration of surgical reconstruction, stresses of unaffected abutments were reduced significantly, and less stress of junction occurred near zygoma of affected side, which were all less than stresses of prosthesis restoration. Thus, removing the clasp of surgical reconstruction increased the stresses of unaffected abutments. The stress trends of maxillary components were different between prosthetic restoration and surgical reconstruction. Surgical reconstruction is better than prosthesis restoration in protection of the abutments. Clasp can alleviate the occlusal burden of maxilla. Varieties of retentive technologies can be considered in prosthesis restoration. The surgical reconstruction is more conducive to rehabilitate unilateral maxilla biomechanically in clinic.
Biomechanical Phenomena ; Finite Element Analysis ; Humans ; Image Processing, Computer-Assisted ; Mandibular Reconstruction ; methods ; Maxilla ; surgery ; Maxillofacial Prosthesis ; Osseointegration ; Zygoma

Objective To investigate the clinical epidemiological characteristic of the cancer in upper digestive tract detected by endoscopy and pathologically diagnosed in Xi'an.Methods Patients with cancer of upper digestive tract,detected by endoscopy and pathologically diagnosed from 1991.1 to 2002.12 were selected.The main clinical data,epidemiologyical,endoscopic manifestation and the pathological characteristics were studied.Results The overall diagnosis rate of upper digestive tract cancer was 8.13% in 12 years.Of all the patients who underwent endoscopy,cancer of esophagus,cardia,stomach and duodenum was 3.42%,1.44%,3.26% and(0.01%),respectively.Although the incidences of esophageal cancer and gastric cancer fluctuated,they showed remarkable decreasing tendency(P=0.000).Meanwhile,the incidence of cardiac adenocarcinoma increased slightly(P=0.000).The male/female ratio of cardiac cancer is 6.29∶1,which is much higher than that of esophageal cancer and gastric cancer(P=0.000).The ratio of squamous cell cancer and adenocarcinoma in esophagus didn't chang in 12 years((P=0.562)),and the adenocarcinoma of esophagus did not show any remarkable tendency (P=0.557).Conclusion Esophageal cancer is the most frequent cancer of upper digestive tract in Xi'an.The detection rate of esophageal cancer and gastric cancer has decreased respectively,and cardiac cancer has increased.Cardiac cancer is different from either esophageal or gastric cancer.

This study was aimed to estimate the effect of different ProDisc-C arthroplasty designs after it was implanted to C5-C6 cervicalspine. Finite element (FE) model of intact C5-C6 segments including the vertebrae and disc was developed and validated. Ball-and-socket artificial disc prosthesis model (ProDisc-C, Synthes) was implanted into the validated FE model and the curvature of the ProDisc-C prosthesis was varied. All models were loaded with compressed force 74 N and the pure moment of 1.8 Nm along flexion-extension and bilateral bending and axial torsion separately. The results indicated that the variation in the curvature of ball and socket configuration would influence the range of motion in flexion/extension, while there were not apparently differences under other conditions of loads. The method increasing the curvature will solve the stress concentration of the polyethylene, but it will also bring adverse outcomes, such as facet joint force increasing and ligament tension increasing. Therefore, the design of artificial discs should be considered comprehensively to reserve the range of motion as well as to avoid the adverse problems, so as not to affect the long-term clinical results.
Arthroplasty ; Biomechanical Phenomena ; Finite Element Analysis ; Humans ; Intervertebral Disc ; Pressure ; Prostheses and Implants ; Range of Motion, Articular ; Spine ; Zygapophyseal Joint

This study investigated the effect of prolonged walking with load carriage on body posture, muscle fatigue, heart rate and blood pressure of the tested subjects. Ten healthy volunteers performed 30 min walking trials on treadmill (speed = 1.1 m/s) with different backpack loads [0% body weight (BW), 10% BW, 15% BW and 20% BW]. The change of body posture, muscle fatigue, heart rate and blood pressure before and after walking and the recovery of muscle fatigue during the rest time (0, 5, 10 and 15 min) were collected using the Bortec AMT-8 and the NDI Optotrak Certus. Results showed that the forward trunk and head angle, muscle fatigue, heart rate and blood pressure increased with the increasing backpack loads and bearing time. With the 20% BW load, the forward angle, muscle fatigue and systolic pressure were significantly higher than with lighter weights. No significantly increased heart rate and diastolic pressure were found. Decreased muscle fatigue was found after removing the backpack in each load trial. But the recovery of the person with 20% BW load was slower than that of 0% BW, 10% BW and 15% BW. These findings indicated that the upper limit of backpack loads for college-aged students should be between 15% BW and 20% BW according to muscle fatigue and forward angle. It is suggested that backpack loads should be restricted to no more than 15% BW for walks of up to 30 min duration to avoid irreversible muscle fatigue.
Blood Pressure ; Body Weight ; Exercise Test ; Healthy Volunteers ; Heart Rate ; Humans ; Muscle Fatigue ; Posture ; Walking ; physiology ; Weight-Bearing

We observed the effect of vibration parameters on lumbar spine under different vibration conditions using finite element analysis method in our laboratory. In this study, the CT-images of L1-L5 segments were obtained. All images were used to develop 3D geometrical model using the Mimics10. 01 (Materialise, Belgium). Then it was modified using Geomagic Studio12. 0 (Raindrop Geomagic Inc. USA). Finite element (FE) mesh model was generated by Hypermesh11. 0 (Altair Engineering, Inc. USA) and Abaqus. Abaqus was used to calculate the stress distribution of L1-L5 under different vibration conditions. It was found that in a vibration cycle, tensile stress was occurred on lumbar vertebra mainly. Stress distributed evenly and stress concentration occurred on the left rear side of the upper endplate. The stress had no obvious changes under different frequencies, but the stress was higher when amplitude was greater. In conclusion, frequency and amplitude parameters have little effect on the stress distribution in vertebra. The stress magnitude is positively correlated with the amplitude.
Biomechanical Phenomena ; Finite Element Analysis ; Humans ; Lumbar Vertebrae ; physiology ; Vibration

Objective To study the effect of enteral nutrition combined with parenteral nutrition in the treatment of elderly patients with acute pancreatitis complicated with hyperlipidemia .Methods 50 patients with acute pancreatitis and hyperlipidemia were enrolled ,and they were randomly divided into observation group (n=25) and control group (n=25) according to the digital table .The patients in the observation group were given enteral nutrition combined with parenteral nutrition , the control group was treated with parenteral nutrition support , The effect of nutrition support was compared between the two groups .Results The blood and urine amylase levels in the two groups after 8d were (69 ±11)U/L and (184 ±24)U/L,(72 ±21)U/L and (177 ±21)U/L,respectively,while the levels were (278 ±32)U/L and (884 ±108)U/L,(271 ±31)U/L and (863 ±119)U/L after 4d,which after 1d were (574 ±57)U/L and (2278 ±321)U/L,(593 ±61)U/L and (2311 ±343)U/L,respectively,and the levels after 8d were significantly lower than those after 4d ( the observation group:t=30.883,P=0.000;t=31.636,P=0.000.The control group:t=26.574,P=0.000,t=28.385,P=0.000),and the levels after 4d were significantly lower than those after 1d (the observation group:t=22.641,P=0.000;t=20.580,P=0.000.The control group:t=23.529,P =0.000,t =19.942,P =0.000).The albumin and prealbumin of the control group after 8d were (31.49 ±3.17)g/L and (90.51 ±20.07) mg/L,respectively,which of the observation group were (33.49 ± 3.08)g/L and (103.73 ±22.89)mg/L,respectively,there were statistically significant differences between the two groups (t=2.262,P=0.028;t=2.171,P=0.035).The total cholesterol and triglyceride levels in the observation group were (2.81 ±0.81) mmol/L and (2.74 ±0.24) mmol/L,respectively,which in the control group were(2.93 ±0.73)mmol/L and (2.67 ±0.31)mmol/L,respectively,which were significantly higher than those after 1d (the observation group:t=7.798,P=0.000,t=3.371,P=0.003;the control group:t=8.079,P=0.000,t =2.560,P=0.000).Conclusion For the acute pancreatitis elderly patients with hyperlipidemia ,the enteral nutrition combined with parenteral nutrition support can effectively improve the patients 'clinical symptoms and signs ,promote the remission.

Objective: To evaluate the effects of 650 nm-10.6 μm combined laser in patients with knee Osteoarthritis (OA) and to determine whether the combined laser provides greater pain relief and improved function compared with red light. Methods: Forty-eight patients with knee OA were randomly allocated to two groups (24 per group), receiving 20 rain irradiation with 650 nm -10.6 μm combined laser or red light emitting diode respectively on point Dubi (ST 35) 3 times a week for the first course (2 weeks) and twice a week for the second one (4 weeks). The main outcome measures were WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) scores. In addition, patients' global assessment, adverse effects and validation of patient blinding were analyzed. Results: All the patients completed the first course, but 12 were lost during the second one. Due to the high dropout rate by the second course, only the data acquired from the first course could be analyzed. No differences of general data of patients and WOMAC scores were found in between-group comparison before treatment (P>0.05). The WOMAC scores of patients in both combined laser group and red light group reduced significantly compared to baseline by the end of the first course (P<0.01). There were no significant differences on the reduction rate of WOMAC scores between two groups (P>0.05). Neither the patients' global assessment nor the dropout rate showed statistical differences between two groups (P>0.05). There was no difference between two groups in patients correctly guessing the treatment assignment (P>0.05). There was no significant difference in the reduction rate of WOMAC scores and the patients' global assessment between patients who guessed their assignment (P>0.05). Conclusion: Both combined laser and red light irradiation are beneficial to patients with knee OA. But as the statistical indifferences between two groups, the authors can't conclude from this study whether the combined laser is more effective.

Objective To evaluate the role of mitochondrial permeability transition pore (mPTP) in attenuation of myocardial ischemia-reperfusion (I/R) injury by sufentanil postconditioning in rats.Methods Sixty male Sprague-Dawley rats,aged 14-15 weeks,weighing 350-420 g,were randomly divided into 4 groups (n =15 each):sham operation group (group S),group I/R,cyclosporin A group (group CP) and sufentanil postconditioning group (group SP).Myocardial I/R was produced by occlusion of left anterior descending branch of coronary artcry for 30 min followed by reperfusion.In groups CP and SP,cyclosporin A 5 mg/kg and sufentanil 1 μg/kg were injected via the jugular vein at 5 min before reperfusion respectively,while the equal volume of normal saline was injected in group I/R.At 10 min of reperfusion,hearts were excised,the myocardial mitochondria were immediately isolated and the activity of mPTP was measured by spectrophotometry.MAP and HR were recorded at 30 min of equilibration,at 30 min of ischemia and at 120 min of reperfusion and rate-pressure product (RPP) was calculated.Arterial blood samples were obtained at 120 min of reperfusion for determination of the plasma cardiac troponin Ⅰ (cTnⅠ) concentration.The animals were then sacrificed for determination of infarct size (IS) and area at risk (AAR),and IS/AAR was calculated.The mitochondrial ultra-structure was examined with electron microscope.Results Compared with group S,the mPTP activity and plasma cTnI concentration were significantly increased,and MAP and RPP were significantly decreased in the other three groups (P ＜ 0.05).Compared with group I/R,the mPTP activity,plasma cTnI concentration and IS/ARR were significantly decreased in groups CP and SP,and MAP was significantly increased in group CP (P ＜ 0.05).Compared with group CP,MAP was significantly decreased (P ＜ 0.05),while no significant change was found in the other indexes in group SP (P ＞0.05).Significant mitochondrial swelling,and disruption and disappearance of cristae were showed in I/R group.The mitochondrial structure was more complete in CP and SP groups than that in group I/R,and the disrupted cristae were found in a small number of mitochondria in CP and SP groups.Conclusion The mechanism by which sufentanil postconditioning reduces myocardial I/R injury is related to inhibition of mPTP opening in rats.

Objective To investigate the effect of type 2 diabetes mellitus (DM) on the attenuation of myocardial ischemia-reperfusion (I/R) injury by sufentanil postconditioning in rats.Methods Male pathogen-free Sprague-Dawley rats,weighing 160-180 g,were used in the study.A model for type 2 DM was established by the feeding of high-fat diet-induced insulin resistance and intraperitoneal streptozocin 35 mg/kg.DM was confirmed by blood glucose level ≥ 16.7 mmol/L one week after injection.Eighteen type 2 diabetic rats were randomly divided into 3 groups (n =6 each):DM sham operation group (DM-S group) ; DM-I/R group; DM sufentanil postconditioning group (DM-SP group).Another 18 healthy nondiabetic rats were chosen and randomly divided into 3 groups (n =6 each):nondiabetes mellitus sham operation group (NDM-S group) ; nondiabetes mellitus I/R group (NDM-I/R group) ; nondiabetes mellitus sufentanil postconditioning group (NDM-SP group).Myocardial I/R was induced by 30 min occlusion of the left anterior descending branch of coronary artery (after 30 min of equilibration) followed by 120 min of reperfusion.Sufentanil 1.0 μg/kg was injected via the right jugular vein 5 min before reperfusion in NDM-SP and DM-SP groups.MAP,SP and HR were recorded immediately before ischemia,at 30 min of ischemia and at 120 min of reperfusion and rate-pressure product (RPP) was calculated.Arterial blood samples were collected at 120 min of reperfusion for measurement of plasma cardiac troponin Ⅰ (cTnⅠ) concentration.The rats were then sacrificed for determination of the myocardial infract size.Results MAP and RPP were decreased,while the plasma cTnl concentration was increased during reperfusion in diabetic and nondiabetic rats.Sufentanil postconditioning decreased the myocardial infract size and plasma concentrations of cTnⅠ,and increased MAP and RPP during reperfusion in nondiabetic rats,but had no effect on the parameters in diabetic rats.Conclusion Type 2 DM interferes with sufentanil postconditioning-induced myocardial protection in rats.

BACKGROUND:Integrated Traditional Chinese and Western Medicine minimaly invasive treatment for halux valgus based on wrapped curtain method with “8”-shaped bandage and sub toe pad external fixation has been used for a long time in the clinic. This method abandons the internal implant fixationandexternal plaster fixation. After surgery, patients could take care of themselves. However, theactivity of the broken end may cause fracture nonunion, which once aroused scholars’ question. Recently, with the continuous improvement of foot biomechanics research, foot finite element model and applications become a reality.
OBJECTIVE:To evaluate thestability of osteotomy after the operation of wrapped curtain method with“8”-shaped bandage and sub toe pad external fixation on the basis of static finite element method.
METHODS:A young female volunteer with halux valgus was selected, whose body weight was 58 kg, and right foot halux abductor valgus angle was 24°; intermetatarsal angle was 13°; proximal articulator set angle was 7°; distal articulator set angle was 7°. CT was used to scan the right foot. ABAQUS software was applied to establish a finite element model of right foot halux valgus bone, and model of the first metatarsal neck minimaly invasive osteotomy was simulated based on wrapped curtain method with external fixation. Von Mises stress and displacement at the osteotomy endwere calculated.
RESULTS AND CONCLUSION:(1) The maximum stress was 0.067 MPa without external fixation, and the maximum stress was 1.258 MPa with the external fixation. Stress was mainly distributed in the outer edge of the osteotomy. (2) The maximum absolute displacement was 0.363 mm without external fixation, and the maximum absolute displacement was 0.716 mm with external fixation. The two largest displacements were both in the Z-axis direction. Statistical analysis confirmed that the four nodes absolute displacement and stress were significantly different (P< 0.01). (3) The maximum relative displacement was 0.101 mm. The maximum relative displacement was 0.046 mm with external fixation. The maximum relative displacement without external fixation was-0.102 mm and occurred in the Z-axis. The maximum relative displacement with external fixation was 0.110 mm and occurred in the Y-axis. (4) One-way analysis of variance confirmed that the four nodes relative displacements were not statisticaly significant in X-axisand Y-axis (P> 0.05). The four nodes relative displacements were statisticaly significant in Z-axis (P< 0.05). (5) These findings suggest that the external fixation based on wrapped curtain method after halux valgus surgery could effectively reduce osteotomy displacement. The moderate stress and elastic fixation are conducive to fracture healing.