BACKGROUND:Acetabular cup orientation is critical for preserving the range of motion and preventing dislocation of the prosthesis. Cup malpositioning may result in an increased polyethylene wear rate,pelvic osteolysis and acetabular migration (aseptic loosening).There are no definite criterion for the orientation of the acetabular cup.OBJECTIVE:To explore the relationship between acetabular cup Position and the load distribution within the acetabulum and to confirm an optimal range of cup position.thereby providing a theoretical criterion from a biomechanical aspect for proper cup implantation in clinical work.DESIGN:Repeated measurements.SETTING:Second Department of Orthopaedics in the First Clinical Hospital of Jilin University.MATERIALS: One healthy male adult fresh Cadaveric pelvis was offered by the Department of Anatomy in Jilin University.METHODS:This experiment was carried out at the Institute of Orthopaedics in the First Clinical Hospital of Jilin University,and the Institute of Biomechanics in Jilin University from September 2005 to May 2006.Cadaveric pelvic was scanned with spiral CT,and then the two-dimensional images were evaluated using GE medical systems software and the outline of the pelvis was identified by the edge detective estimation.Pelvic coordinate data were put into the computer to build up a three-dimensional (3D) finite element model of the pelvic using Solidworks software.A P48 non-cemented cup from Tianjin Huabei Medical Instrument Factory was used,and the 3D measurement of the cup was carried out by CLY single-arm 3D measurement apparatus,which was made in Testing Technology Institute of China.The measurement data were transferred into computer.Through the CAD SliodWorks2003 software,the 3D model of the cup was automatically reconstructed. Afterwards, one-foot standing position was simulated to conduct the loading and constraint of the model,the Mises and shear force distributing of the cup were analyzed,forecasting the mechanical risk of prosthetic failure.MAIN OUTCOME MEASURES:The evaluation of Mises stress and shear force distributions under different cup positions.RESULTS:In the 3D finite element modeI of human pelvis.the number of total nodes was 103043 and the number of total elements was 69271.Abduction angle did not affect the Mises and shear force distributions between the range of 40°-50°(P>0.05).However,significant affects appeared in Mises and shear force once the abduction angle was<35°or>50°.The change of the cup anteversion within 5°-30°would not affect the Mises and shear forces in the acetabulum(P>0.05).CONCLUSION:A uniform load distribution on the cup-bone interface can be obtained when the cup abduction angle is from 40°to 50°.The change of the cup anteversion angle can not affect the load distribution in the acetabulum,therefore the cup abduction range of 40°-50°can be confirmed as the safe range for cup implantation.

BACKGROUND: Brain injury can be induced by repeated high positive acceleration ( + Gz) exposure, but the mechanism was still unclear.OBJECTIVE: To investigate the role of apoptosis in higher + Gz exposures induced brain injury by observing the changes of mRNA expression of bcl-2,bax, p53, and interleukin-1β(IL-1β) hydroxylase in rat brain.DESIGN: Randomized control experimental study based on experimental SD rat model.SETTING: Aviation medicine research center of a hospital.MATERIALS: Twenty-six healthy male SD rats, weighed from 180 to 220 g,were randomly divided into control group(4 rats) and + Gz exposure group (22 rats).INTERVENTIONS: Rats were fixed on the rotating arm of animal centrifuger with their heads towards axis. Rats in + Gz exposure group were exposed to + 14 Gz for three times, each for 45 seconds with 30 minutes interval in between. Rats in control group were subject to the same experiment in + 1 Gz. The rat brains were taken 30 minutes, 6 hours, 24 hours and 48 hours after the last centrifuge run, and then fixed and embedded. Changes of bcl-2, bax, p53, and IL-1β hydroxylasein mRNA expressions in rat brain were measured with semi-quantitative reverse transcription polymerase chain reaction(RT-PCR) . Apoptotic cells were detected by terminal deoxynucleotide(correction of deoxynuleotide) transferase-mediated dUTP nick end labeling(TUNEL) technique.MAIN OUTCOME MEASURES: The changes of bcl-2, bax, p53, and IL-1 β hydroxyalse mRNA expressions at each time points.RESULTS: After repeated + Gz exposures for 6 hours, bcl-2 mRNA expression in rat brain tissue(0. 32 ± 0. 08) was found significantly lower than in control group(0. 69 ± 0. 15), while mRNA expressions of bax, p53, and interleukin-1β converting enzyme(ICE) 0.55 ±0. 09, 0. 48 ±0. 12, 0.79 ±0. 12were significantly higher than in control group 0.33 ±0. 09, 0. 31 ±0.05,0.51 ± 0.09 ( P ＜ 0. 01 ) . After 24 hours of exposure, mRNA expression of bcl-2 in rat brain tissue (0. 28 ± 0.05) was significantly lower than in control group, while the mRNA expressions of bax, p53, and ICE 0.61 ±0. 15,0.54 ± 0. 07, 0. 84 ± 0. 15 were significantly higher than in control group ( P ＜ 0.01); but the difference of brain bcl-2, bax, p53 and ICE mRNA expressions had no statistical significance when exposed for 0.5 hour and 48 hours( P ＞ 0.05). Partly apoptotic cells were observed at exposure for 6 hours and 24 hours.CONCLUSION: Changes of bcl-2, bax, p53 and ICE mRNA expressions, as well as apoptosis in rats brain can be induced by repeated + Gz exposures and may be involved in the molecular mechanisms of brain injury.

Objective To compare postoperative complications between endoscopic thyroidectomy via breast areola approach and open thyroidectomy.Methods From June 2011 to June 2014,475 patients underwent thyroidectomy.Patients were divided into traditional open group (251 cases) and endoscopic thyroidcctomy group (224 cases).Postoperative complications were recorded and compared.Results All operations were successfully completed.There was no case in endoscopic thyroidectomy group converted to traditional open surgery.There was no serious postoperative complication occurred,including injury to trachea,mediastinal emphysema,intraoperative massive hemorrhage and cardiopulmonary accidents.The difference of postoperative complication between two groups had no statistical significance (all P ＞0.05) as to permanent recurrent laryngeal nerve injury,Homer syndrome,permanent hypoparathyroidism,chyle leakage,postoperative hemorrhage and infection of incision.However,postoperative ecchymosis was more often in endo group (P ＜0.05).Conclusions Compared to traditional open thyroidectomy,endoscopic thyroidectomy via breast areola approach has significant cosmetic advantages without increasing the incidence of major postoperative complications.

BACKGROUND: During the hip replacement, selection of prosthesis often depends on patients' bone condition. There has been no gold standard for selection of prosthesis. It will be of scientific significance to select femoral prostheses implanted under different bone densities through three-dimensional finite element analysis and simulated contrast mechanical tests.OBJECTIVE: Three-dimensional finite element analysis was employed to select femoral prostheses according to different bone densities, and simultaneously simulated contrast mechanical tests were performed to determine the age criteria regarding the selection of femoral prosthesis during the hip replacement.DESIGN, TIME AND SETTING: An open experiment was performed at the Second Department of Orthopedics, First Clinical Hospital of Jilin University and Institute of Biomechanics, Jilin University between September 2006 and May 2007.MATERIALS: Freshly adult femoral specimens were harvested from cadavers.METHODS: Three-dimensional finite element models of femur were established using Solidworks software. Following the known formula, the bone density and elastic modulus at different age brackets were calculated and input into the computer. The human one-foot standing condition was simulated and pressure was loaded on the reconstructed femoral models.MAIN OUTCOME MEASURES: Some biomechanical characteristics of uncemented and cemented femoral prostheses, such as the distress distribution and initial micromovement at different bone densities, were measured.RESULTS: Relatively well-distributed whole distress and slight initial micromovement of uncemented femoral prostheses were found in male patients at 30-60 years old and in female patients at 40-55 years old. Symptoms of cemented femoral prostheses the same as the uncemented femoral prostheses were present in male patients at 60-70 years and in female patients older than 55 years old.CONCLUSION: Results of three-dimensional finite element analysis and simulated contrast mechanical tests suggest that uncemented femoral prostheses provide better therapeutic effects in male patients younger than 60 years and in female patients younger than 55 years than cemented femoral prosthesis.

BACKGROUND:Standard artificial prosthesis does not well match to patients' skeleton due to absolute individuation,while the difference between them does not keep the stabilization of artificial joint for a long term.OBJECTIVE:To construct three-dimensional models of custom-made femoral prosthesis by using computer-aided design and to verify whether custom-made femoral prosthesis is superior to popular femoral prosthesis via simulating and contrasting mechanical study.DESIGN,TIME AND SETTING:Opening study was performed in the Orthopaedics Institute of the First Clinical Hospital and the Biomechanics Institute,Jilin University between September 2006 and May 2007.MATERIALS:One fresh femur was derived from adult corps.METHODS:Two-dimensional images of the fresh femur was obtained by using total-length CT scanning and processed with computer edge recognition and three-dimensional contour extraction software to identify outer and inner contour of bone cavity,extract contour data of bone cavity and prosthesis,and construct three-dimensional models of femur and custom-rhade femoral prosthesis.SolidWorks software was used to establish three-dimensional prosthetic models in common biological and bone cement types; moreover,bone-cement,biological,and custom-made femoral prosthesis were replaced via simulating clinical surgery.MAIN OUTCOME MEASURES:Standing on single or double feet was simulated to measure stress distribution,interface stress,and primary micromotion of femoral prosthesis in the three types.RESULTS:Edge extracting was replaced by Canny calculator,characterizing by stable running,credible outcome,and consistent with the primary request.Stress,femoral stress,interface stress,and primary micromotion of custom-made femoral prosthesis were significantly lower than biological and'bone-cement femoral prosthesis (P ＜ 0.01).CONCLUSION:The computer-aided design is reliable to perform the assistant design of prosthesis; furthermore,biomechanical properties of the custom-made femoral prosthesis are superior to those of popular femoral prosthesis.

Objective To explore the effects of excise-induced fatigue on the microloop plasticity of prefrontal cortex through observing the expression of parvalbumin positive neurons in prefrontal cortexes of rats induced by exhaustive exercise,so as to find out the possible mechanism of the central regulation of exercise-induced fatigue by measuring the expression of NMDAR2B receptors.Methods Thirty-six Wistar rats were randomly divided into an exhausted group (E),a repeated exhaustion group (RE) and a control group (CG),each of 12.For group E,the adjusted Bedford incremental load of treadmill exercise program was employed:the initial treadmill speed was 8.2 m/min,lasting for 15 minutes,then increased to 15 m/min for another 15 minutes,and finally increased to 20 m/min till exhaustion.For RE group,they were given continuous treadmill exercises to exhaustion for consecutive 7 days.The immunofluorescence technique was used to observe the expression of PV+ interneurons after exhausted treadmill running.The Western blotting technique was used to determine the expression of NMDAR2B in the tissue of the prefrontal cortex.Results After the exhausted treadmill running,the expression of PV+ interneurons in the prefrontal cortexes of both E and RE groups increased significantly compared with the control group(P＜0.01).The immunofluorescence results indicated that NMDAR2B positive neurons were seen in group E,but not obviously in group CG and RE.The Western blotting showed that compared with CG group the protein expression of NMDAR2B in prefrontal cortexes of group E was relatively high,and that of group RE was relatively low,but without significant difference (P＞0.05).The running distance and prefrontal cortex NMDAR2B expression were found negatively correlated (P＜ 0.01).Conclusions Exhaustive exercises have an impact on the plasticity in rats' prefrontal cortex neural network through regulating the local loop of PV positive neurons.This plasticity of the prefrontal cortex is involved in the regulation of central fatigue.The present study might provide morphological basis for the research of central mechanism of the exercise-induced fatigue.

Objective To study the length changes of the inferior glenohumeral ligament(IGHL) during shoulder abduction with MRI and 3D software.Methods Fourteen right shoulder joints of 14 healthy volunteers were evaluated in 7 isometric abduction positions(0?,30?,60?,90?,120?,150?,and 180?) using MRI scanning.3D shoulder models were reconstructed and the attachment points of the ligaments were located.The shortest ligament lengths were calculated between each origin and insertion in 3D space for each abduction position.Results During shoulder abduction,the 3D distance of AIGHL was found to elongate and attained the maximal length at 120? abduction(54.5 mm?3.0 mm)(P

The purpose of this study is to observe the changes in gene expressions of bcl 2, bax, p53 and interleukin 1? converting enzyme (ICE) in the cerebral tissue of rat exposed to repeated +Gz, and to explore the pathogenetic role of apoptosis in brain damage induced by repeated +Gz exposures. The expression levels of bcl 2, bax, p53 and ICE in cerebral tissue of rats exposed to repeated +Gz were measured by semi quantitative reverse transcription polymerase chain reaction (RT PCR), and the apoptotic cells in brain tissue were detected by terminal deoxynuleotidyl transferase mediated dUTP nick end labeling technique. The results showed that the bcl 2 expression levels in the brain 6h and 24h after repeated +Gz exposures were significantly lower than those of control group, whereas the bax, p53 and ICE expression levels in the brains tissue 6h and 24h after repeated +Gz exposures were significantly higher than those of control group. Apoptotic cells could be observed in cerebral cortex, CA1 subregion of hippocampus and striatum at 6h and 24h after repeated +Gz exposures. It is suggested that the changes in bcl 2, bax, p53 and ICE expressions in rat brain can be induced by repeated +Gz exposures and apoptosis might be one of the molecular mechanisms of brain damage induced by repeated +Gz exposures

Objective To explore the effect of thyroid hormone on bone metabolism.Methods The thyroid in the rabbits had been cut off and the physics and histology of the bone in the rabbits were observed.The therapeutic effect of exterofection thyroid hormone was also observed.Results The lacking or reducing of thyroid hormone could lead to osteoporosis.The substitutive treatment of T_4 could partially inhibit the oesteopenia.Conclusion When the T_3 level equals to the level of T_4,the oesteopenia of the rabbits with thyroid being cut off may be caused by the lack of calcitonin.

BACKGROUND: Bone metabolism disorder happens in diabetic environment, bone defects in which are difficult to repair. Study addressing osteogenic property of adipose-derived stroma cells (ADSCs) in diabetic environment provides theoretical basis for its application in certain environment.OBJECTIVE: To explore the effects of high glucose (HG) and advanced glycation end-products (AGEs) on osteogenic capacity of human ADSCs. METHODS: 100 mg/L AGEs and 27.5 mmol/L HG were used to simulate in vitro diabetic environment and intervened ADSCs osteogenic differentiation. The cells were divided into 4 groups, with 6 samples in each group. The expression of type Ⅰ collagen was examined by fluorescent immunofluorescence at 21 days after osteogenic induction. The number of calcification nodes was counted under contrast phase microscopy at 14, 21 and 28 days. RESULTS AND CONCLUSION: Fluorescent quantitation scan showed that the type Ⅰ collagen amount of the AGEs+HG treated group was 2.76 times lower than that of the control group. AGEs+HG reduced the number of ADSCs calcification nodes compared with the control, HG, and AGEs groups, the differences were statistical significant (P < 0.01). AGEs and HG exposure inhibit the cognate osteogenic differentiation of ADSCs, which suggest that AGEs and HG are unfavorable factors that reduce ADSCs osteogenic ability.