BACKGROUND:Three-dimensional finite element studies found that the instal ation location of the hip prosthesis is closely related to the effects of hip replacement, but studies on different anteversion and abduction angle of the hip prosthesis mounting position on the effects of hip biomechanics are not much. OBJECTIVE:To analyze the biomechanical characteristics of different prosthetic positions in hip arthroplasty using three-dimensional finite element analysis. METHODS:One healthy volunteer was selected and data of pelvis and femur were col ected. Three-dimensional geometric model of this volunteer was established and received finite element network partitioning. CT scan was used to obtain prosthesis model data and accurate prosthesis model was established. 16 kinds of different prosthesis position model of hip replacement were established. Vertical y downward force of 780 N was applied on the top of sacroiliac joint and pubic symphysis. The acetabular stress peak, femoral stress peaks, polyethylene liner peak stress and polyethylene liner damage zone volume of 16 kinds of model were observed. RESULTS AND CONCLUSION:(1) The acetabular stress peak, femoral stress peaks, polyethylene liner peak stress and polyethylene liner damage zone volume of 16 kinds of different prosthesis position model of hip replacement, anteversion angle 10° abduction angle 50° got the best results. The acetabular stress peak was 51.23 MPa;femoral stress peak was 26.34 MPa. Polyethylene liner peak stress was 5.288 MPa and polyethylene liner damage zone volume was 2.239×10-7 m3. (2) These results indicated that anteversion angle 10° abduction angle 50° is the ideal hip replacement degree. The peak stresses of acetabulum, femur, and polyethylene liner at this instal ation angle are minimum;polyethylene liner damage zone volume is also minimum. This can provide data for clinical reference.

BACKGROUND: In recent years, al kinds of absorbable internal fixation materials have been used in the clinical treatment of patel ar transverse fractures. OBJECTIVE: To investigate the repairing effect of absorbable internal fixation materials on patel ar transverse fractures. METHODS: Total y 102 cases of fresh patel ar transverse fractures were included 62 males and 40 females cases, with a mean age of (41.85±11.15) years, and according to treatment methods, they were divided into two groups: observation group (n=52) using absorbable screws for reconstruction and control group (n=50) using Kirschner wire repair. At 12 months after repair, Lysholm knee function score were measured and evaluated, and the occurrence of adverse events was recorded. RESULTS AND CONCLUSION: The knee function score and excel ent rate of the observation group were significantly higher than those of the control group (both P < 0.05). In the observation group, there were four cases of fracture displacement, but no skin irritation and other adverse events occurred; in the control group, there were two cases of nonunion and five cases of skin irritation or internal fixation loosening and slippage. Therefore, there was a higher incidence of adverse events in the control group compared with the observation group (P < 0.05). These experimental results show that the use of absorbable screws in the repair of patel ar transverse fracture can promote the functional recovery of the knee joint, with good biocompatibility.

Objective To assess left ventricular systolic synchrony and systolic function, as well as the relationship between left ventricular systolic synchrony and systolic function in patients with myocardial infarction with real-time three-dimensional echocardiography (RT-3DE). Methods Thirty patients with myocardial infarction and 20 healthy subjects underwent RT-3DE. Full-volume imaging was performed and the data was analyzed. A series of global and regional left ventricular volume curves were plotted. The parameters of left ventricular systolic function, synchrony in global and regional cardiac ventricle were obtained. Results ESV, EDV were larger and the LVEF was lower in the group of patients with myocardial infarction than those of the control group (P＜0.01). All the systolic synchrony parameters were significant larger in patients with myocardial infarction than in the control group (P＜0.001). The LVEF values, especially Tmsv-16-SD% and Tmsv-16-Dif%, were negative correlated with all the systolic synchrony parameters (r=-0.755, -0.747). The regional left ventricular systolic function parameters (rEF and rgEF) were lower and the Tmsv% was longer (P＜0.05) in the zones with infarction in patients with anterior myocardial infarction than those of the control group. The changes of Tmsv% were in coincidence with that in regional left ventricular systolic function. Conclusion RT-3DE can be used to evaluate left ventricular systolic synchrony and systolic function. The left ventricular systolic asynchrony has negatively effect on systolic function.

BACKGROUND:Lumbar spinal stenosis is clinical repaired with decompression, bone fusion and internal fixation, and different internal fixation materials can be chosen during the surgery. OBJECTIVE:To explore the influence of polyetheretherketone (PEEK) pedicle screw fixation combined with interbody fusion on the bone fusion rate of patients with lumbar spinal stenosis. METHODS:A retrospective analysis was performed in 63 cases of lumbar spinal stenosis undergoing decompression and interbody fusion. These patients were divided into control group (titanium internal fixation system,n=31) and experimental group (PEEK pedicle internal fixation system,n=32) according the internal fixation materials folowed by posterior spinal decompression with interbody fusion. The Oswestry dysfunction index scores before and 4, 12, 24 weeks postoperatively and bone fusion rates at 4, 12, 24 weeks postoperatively were compared between the two groups. RESULTS AND CONCLUSION:Oswestry dysfunction index scores showed a gradual decline in both two groups before and 4, 12 and 24 weeks after treatment, but there was no difference at different time (P > 0.05). At 4 and 24 weeks after treatment, there was no difference in the bone fusion rates between the two groups (P > 0.05), but at 12 weeks after treatment, the bone fusion rate in the experimental group was better than that in the control group (P < 0.05). During the surgery, no infection and other adverse events occurred in the two groups. These results indicate that both PEEK and titanium internal fixation systems for lumbar tube stenosis have obtained good results, but PEEK material has a better role in the bone fusion at 4-12 weeks after internal fixation.

Objective To assess the left ventricular (LV) systolic synchrony in patients with myocardial infarction using real-time three dimensional echocardiography(RT-3DE) and speckle tracking imaging(STI). Methods Twenty-five healthy subjects and thirty patients with myocardial infarction underwent two-dimensional echocardiography and RT-3DE examination. The systolic synchrony parameters derived from RT-3DE were the dispersion of time and the maximum difference of time to minimum regional volume for 16 LV segments (Tmsv-16-SD and Tmsv-16-Dif). When the Tmsv-16-SD was above the percent 99 of the control group distribution in patients with myocardial infarction were considered statistically different from those in the control group and were accordingly classified as LV systolic asynchrony. The time from the onset of QRS complexes to systole peak strain from the radial vectors was recorded using STI. The standard deviation and the maximal temporal difference of the radial (TRS-SD and TRS-Dif) of 18 segments were calculated as indicator of LV systolic synchrony. LV systolic asynchrony was defined as an interval≥130 ms for the absolute difference in time to peak radial strain for the anteroseptal wall versus the posterior wall (TAS-POST). Results All the systolic synchrony parameters derived from RT-3DE and STI were significantly larger in the myocardial infarction group than those of the control group (all P＜0.01 ).For Tmsv-16-SD and Tmsv-16-Dif,a moderate correlation with TRS-SD and TRS-Dif( r = 0.675 and 0.620,all P＜0.01) was found. No significant difference and general consistency were found between the systolic asynchrony parameters by RT-3DE and STI ( P = 0.125, Kappa = 0.60). Conclusions RT-3DE and STI provide effective tools to assess the LV systolic synchrony. There is no obvious correlation between these methods, thus it is essential of using different methods and parameters to evaluate the LV systolic synchrony.

Objective To assess left ventricular(LV) longitudinal strain in patients with coronary heart disease by two-dimensional speckle tracking imaging (2DSTI),and to explore the clinical value of 2D longitudinal strain in detecting myocardial ischemia. Methods Forty-four patients with coronary heart disease (CHD group) and 28 age-matched subjects (control group) were enrolled into this study. The two-dimensional data were obtained in apical 4-chamble, 2-chamber and long axis view. And the longitudinal strains of every segments, the average longitudinal strain of LV 18 segments (SL18), the average longitudinal strain of 12 segments (SL12,excluded the 6 apical segments) were analyzed. Results In the patients with CHD, the longitudinal strain of ischemia segments and the global LV longitudinal strain were significantly decreased than that of the control subjects. Both in patients with CHD and in control subjects,the longitudinal strains in apical segments were higher than that of middle and basal segments. There was significant difference between SL18 and SL12 ( P=0.027 in CHD group and P =0.003 in control group).Receiver operating curve (ROC) analysis demonstrated that the cutoff point of SL18 to detect myocardial ischemia was - 18.8％ (sensitivity 80.2％ and specificity 74.1％ ) ,and the cutoff point of SL12 to detect myocardial ischemia was - 17.8％ ( sensitivity 81.7％ and specificity 85.6％ ). Conclusions 2D longitudinal strain was sensitive to detect myocardial ischemia, SL12 was better than SL18 in detecting myocardial ischemia. 2DSTI might be useful for identifying patients with severe CHD.

Objective To assess left ventricular (LV) untwisting in patients with acute myocardial infarction(AMI) in different location by two-dimensional speckle tracking imaging(2D-STI),searching for sensitive parameter to evaluate the untwisting motion,to explore the impact of myocardial infarction(MI)location and number of MI segments on left ventricular untwisting movement.Methods Forty-one patient with AMI (AMI Group) were divided into two groups (anterior wall-anteroseptum group and inferior wall-posterior wall group) according to the MI location,and 31 age matched subjects were involved as the control group.Acquire the bull's eyes map of systolic strain (LPSS) values by automated function imaging(AFI)and locate the position and number of segments of MI by it.Access twist at aortic valve closure (AVCtw),twist at mitral valve open (MVOtw),peak twist velocity(PTV),untwisting rate in IVRT (Untw-R),peak untwisting velocity(PUV),time to peak untwisting velocity(TPUV) and half time of untwisting (UHT)with STI.Results Compared with control group,left ventricular ejection fraction (LVEF),global LPSS,PUV and Untw-R of AMI group decreased significantly (P ＜0.001),T-PUV (P ＜0.001) and UHT (P =0.028) increased significantly.The number of MI segments correlated with Untw-R (r =-0.420,P =0.006) significantly.There was no significant correlation between number of MI segments and UHT,PUV,TPUV.Untw-R in anterior wall-anteroseptum group were lower than inferior wall-posterior wall group(P =0.022).For PTV,PTW,T-Ptw,PUV,UHT and T-PUV,there was no significant difference between anterior wall-anteroseptum group and inferior wall-posterior wall group.Conclusions LV untwisting motion of AMI patients can be observed by 2D-STI.Untw-R is a sensitive parameter to evaluate the untwisting motion of AMI patients.The untwisting motion of AMI patients decrease significantly,even worse in anterior wall-anteroseptum AMI patients.

Objective To assess the left ventricular dyssynchrony in coronary artery disease(CAD) without visual segmental wall motion abnormalities using strain delay index (SDI).Methods A total of 135 patients under suspicion of CAD were recruited in this study.Two-dimensional cchocardiography was performed to collect dynamic images of left ventricular apical long axis views,tow-chamber views,four chamber views and parasternal short axis mitral views,papillary views and apical views.The time to minimal systolic longitudinal,radial,circumferential strain (Tssl,Tssr and Tssc) were measured from the start point of QRS wave in electrocardiogram.The left ventricular segmental standard deviation (Tssl-SD,Tssr-SD,Tssc-SD),maximal difference (Tssl-Dif,Tssr-Dif,Tssc-Dif) and longitudinal,radial,circumferential SDI (LSDI,RSDI,CSDI) of 18 left ventricular segments were calculated.Results According to coronary angiography results,patients were divided into three groups:severe stenosis group,mild stenosis group and control group.Compared with the other two groups,SDI and Tssl-SD,Tssl-Dif were decreased in severe stenosis group (P ＜0.001 or P ＜0.05).However,there were not significant differences between the mild stenosis group and the control group except Tssr-SD.The receiver operating characteristic (ROC) curves analysis demonstrated that LSDI had the highest accuracy and Tssl-SD had the lowest accuracy for detecting severe CAD (areas under the curve were 0.891,0.797,0.666,0.580 and 0.556 respectively).High sensitivity and specificity (80.6％ and 86.7％,respectively) were shown when using-12.67％ as a cutoff point of LSDI to diagnose severe CAD.Conclusions SDI can be helpful for assessing the left ventricular dyssynchrony in patients without visual segmental wall motion abnormalities,and LSDI is the most effective parameter to detecting severe CAD.

Objective To evaluate the function and synchronization in patients with paroxysmal atrial fibrillation(PAF) by two dimensional speckle tracking imaging(2D-STI) measuring the strain of left atrial.Methods Thirty healthy controls and thirty-five patients with PAF were studied.The PAFs were divided into group PAF1 during the diapause and group PAF2 during the stage of attack.From the strain-time curve of 2D-STI workstation,the peak velocity(Vs,Ve and Va),the peak amplitude of longitudinal strain (Ss,Se and Sa) and strain rate (SRs,SRe and SRa) were acquired in the course of systole,the early and the late diastole respectively.The synchronization of left atrial (Ts-SD,Te-SD and Ta-SD) could be gotten from the time to the peak strain.The correlation were analysed between the synchronization indices and the strain rate parameters.Results ①No significant differences were found at the age,heart rate,E/A,IVS,LVEDD and LVEF.Compared with the control group,the LAD increased and DT decreased in PAF1 and PAF2 groups (P ＜0.05).②The peak velocity were slower,the peak strain were shorter and the peak strain rate were lessened in the PAFs than the controls(P ＜0.05),except the SRa(P ＞0.05).③The Ts-SD and Te-SD were much more different during the three groups(P ＜0.05),the PAF2 showed fewer synchronization; the Ta-SD was higher in the PAF1 than the controls(P ＜0.05).④The Ta-SD had a positive correlation with SRa(r =0.61,P ＜0.01).Conclusions The reservoir and conduit function of left atrial are impaired in PAFs during the diapause,the booster pump could recover partially,however,there are dyssynchronization.The booster pump function disappear during the stage of attack and there are worse synchronization.2D-STI may paly important roles in the assessment of function and synchronization of left atrial.

Objective To evaluate left atrial function in patients with ischemic cardiomyopathy(ICM)and dilated cardiomyopathy(DCM)by two dimensional-speckle tracking imaging(2D-STI).Methods Twenty-two patients with ICM,twenty-six with DCM and thirty-two healthy subjects were studied.The maximum volume(LAVmax),minimum volume(LAVmin)and volume before the systole(LAVp)of left atria were acquired using biplane area-length method,and calculated the total emptying volume(LATV),expansion index(AEI),active emptying volume(LAEV)and fraction(LAEF)of left atria.The strain and strain rate during systole and late of diastole(Ss,SRs,Sa and SRa)were measured at each left atrial wall (septal,lateral,anterior and inferior).The average of them were worked out.The correlation of left atrial function and strain rate were analysed.Results ①No significant differences were found at the age,sex,heart rate and the E wave between the mitral leaflet tips during all the groups.Compared with the control group,the peak of A wave,the deceleration time of E wave and LVEF decreased in ICM and DCM groups,while the LAD,LVEDD and E/A increased significantly in the two groups(P＜0.05).There were no significant differences between ICM and DCM.②Compared with the controls,the LAVmax increased,AEI and LAEF decreased significantly in patients with ICM and DCM,even lower in DCM(p＜0.05).③Compared with the controls,the Ss,SRs,Sa and SRa reduced significantly in patients with ICM and DCM(P＜0.05),and the DCM showed much significant differences than ICM(P＜0.05).④The AEI had a positive correlation with SRs(r =0.765,P＜0.01).The LAEF had a significant correlation with SRa(r =0.830,P＜0.01).Conclusions The accumulation during systole and active emptying function during late of diastole are both lower in ICM and DCM,even worse in the latter.The 2D-STI may paly an important role in the evaluation of left atrial function.