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 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 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 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 the left ventricular systolic function after renal sympathetic denervation(RSD) in beagles with heart failure by layer-specific two-dimensional speckle tracking imaging.Methods Twenty-three beagles were randomly divided into control group (8 dogs),URSD group (8 dogs)and RSD group (7 dogs).Control group was implanted with pacemakers without pacing,URSD group was implanted with pacemakers and underwent 3 weeks of rapid right ventricular pacing,and RSD group underwent catheter-based RSD bilaterally and was simultaneously implanted with pacemakers.All standard measurements were obtained from the left ventricular short-axis views at the levels of mitral annulus,papillary muscle and apex,and apical four-chamber,two-chamber,and long-axis views.The peak systolic longitudinal strain and circumferential strain of each layer of the left ventricle were measured by layerspecific two-dimensional speckle tracking imaging.Results After 3 weeks,all of the dogs in both the URSD and RSD groups showed lower left ventricular diastolic and systolic function compared with those in the control group,however,the dogs in the RSD group had a higher LV ejection fraction (LVEF) than the dogs in the URSD group(P ＜ 0.05).Compared with the control group,the global longitudinal strain,circumferential strain and radial strain all decreased significantly in URSD and RSD groups.The longitudinal strain of endo-and mid-cardium and the circumferential strain in endo-cardium were significantly higher in RSD group than those in URSD group(P ＜0.05).Conclusions Myocardial systolicfunction is impaired in dogs with heart failure,layer-specific two-dimensional speckle tracking imaging can provide effective tools to assess the left ventricular systolic function.Renal sympathetic denervation can improve the myocardial systolic function in dogs with heart failure.

Objective To evaluate the feasibility and accuracy of three-dimensional (3D) printed left atrial appendage (LAA) models based on 3D transesophageal echocardiography (3D-TEE) data and the application value for treating special anatomic LAA.Methods Data of 18 patients of atrial fibrillation who were underwent LAA occlusion were retrospectively analyzed,including 3D-TEE and CT volume data of the patients.The 3D-TEE data of the LAA were post-processed and a flexible material was used to print the LAA model by 3D printer.The morphological classification and lobulated classifications of LAAs were assessed by the 3D printed models.The measurements of long axis,short axis and depth of LAAs were also performed.And the measurement and classification results were compared with those based on 3D-TEE and CT volume images.A occluder release test was performed on the 3D printed models for patients with challenging LAA morphology.Results For all 18 patients,3D-TEE full volume data of the LAA were successfully reprocessed and printed as 3D LAA models.The consistency of morphological classifications and lobulated classifications of LAAs based on 3D printed models and cardiac CT were 0.92 and 0.83,respectively.No significant differences of LAA ostium dimensions (long axis and short axis) and depth were found between the measurement results based on 3D printed models and 3D-TEE (all P＞0.05).A simulation of LAA occlusion rehearsal was successfully performed on 3D models of two challenging cases.Conclusion The echocardiographic 3D printing technique has high feasibility and accuracy,and can be promising for personalized planning in cases of transcatheter special morphological LAA occlusion.

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.

Objective To assess left ventricular function early and late improvement of patients with acute myocardial infarction (AMI) treated by percutaneous coronary intervention (PCI) by speckle tracking imaging (STI).The clinical values of the assessment of STI for the prognosis and heart function improvement of AMI patients treated by PCI were discussed.Methods 73 AMI patients who had AMI for the first time and had been treated by primary PCI from September 2010 to July 2011 and were examined in the follow-ups from December 2010 to February 2012 in our hospital were enrolled.Dynamic images were acquired before PCI,at 3 months and 6 months after PCI and analyzed by STI.Dynamic images were analyzed for longitudinal peak systolic strain (LPSS),radial peak systolic strain (RPSS) and circumferential peak systolic strain (CPSS) values by STI.According to the comparison of left ventricular ejection fraction (LVEF) before PCI and 6 months after PCI,patients were divided into left ventricular function improved group (ΔLVEF6＞5％) and not-improved group.According to the comparison of LVEF before PCI and 3 months after PCI,improved group were divided into left ventricular function early-improved group (ΔLVEF3 ＞5％) and late-improved group.Results The values of all STI parameters before PCI,3 months and 6 months after PCI in improved group were higher than those in not-improved group (P ＜0.001,all).LPSS before PCI and at the follow-ups and RPSS at 3 months after PCI in early-improved group were higher than those in late-improved group (LPSS at 3 months after PCI:P＜0.001;Other parameters:P ＜0.05).There were significant correlations between all STI parameters and both ΔLVEF3 and ΔLVEF6.LPSS before PCI was more closely related to ΔLVEF3 (r =-0.781,P ＜0.001).CPSS at 6 months after PCI was more closely related to ΔLVEF6 (r =-0.834,P ＜ 0.001).Conclusions Early and late function improvement of left ventricle in AMI patients who is treated by PCI are accurately assessed by STI.The precise analyses of longitudinal and circumferential movements in STI are important for clinical diagnosis.