Regional variations in MR relaxation of hip joint cartilage in subjects with and without femoralacetabular impingement

The objective of this study was to analyze regional variations of magnetic resonance (MR) relaxation times (T_1ρ and T₂) in hip joint cartilage of healthy volunteers and subjects with femoral acetabular impingement (FAI). Morphological and quantitative images of the hip joints of 12 healthy volunteers and 9 FAI patients were obtained using a 3 T MR scanner. Both femoral and acetabular cartilage layers in each joint were semi-automatically segmented on sagittal 3D high-resolution spoiled gradient echo (SPGR) images. These segmented regions of interest (ROIs) were automatically divided radially into twelve equal sub-regions (30⁰ intervals) based on the fitted center of the femur head. The mean value of T_1ρ/T₂ was calculated in each sub-region after superimposing the divided cartilage contours on the MR relaxation (T_1ρ/T₂) maps to quantify the relaxation times. T_1ρ and T₂ relaxation times of the femoral cartilage were significantly higher in FAI subjects compared to healthy controls (39.9 ± 3.3 msec in FAI vs. 35.4 ± 2.3 msec in controls for T_1ρ (P = 0.0020); 33.9 ± 3.1 msec in FAI vs. 31.1 ± 1.7 msec in controls for T₂ (P = 0.0160)). Sub-regional analysis showed significantly different T_1ρ and T₂ relaxation times in the anterior-superior region (R9) of the hip joint cartilage between subjects with FAI and healthy subjects, suggesting possible regional differences in cartilage matrix composition between these two groups. Receiver operating characteristic (ROC) analysis showed that sub-regional analysis in femoral cartilage was more sensitive in discriminating FAI joint cartilage from that of healthy joints than global analysis of the whole region (T_1ρ: area under the curve (AUC) = 0.981, P = 0.0001 for R9 sub-region; AUC = 0.901, P = 0.002 for whole region; T₂: AUC = 0.976, P = 0.0005 for R9 sub-region; AUC = 0.808, P = 0.0124 for whole region). The results of this study demonstrated regional variations in hip cartilage composition using MR relaxation times (T_1ρ and T₂) and suggested that analysis based on local regions was more sensitive than global measures in subjects with and without FAI.     

髋关节发育不良髋臼假体位置与稳定的三维有限元分析

目的利用三维有限元仿真的方法，研究全髋关节置换术治疗成人髋关节发育不良时3 种不同髋臼假体位置与髋臼 假体初始稳定的相关性，为临床手术操作提供参考依据。方法采用专门的生物力学有限元网格划分器，从髋关节发育不良的CT 扫描数据中，建立高度仿真的个性化髋骨三维有限元模型，并模拟在真臼位置安放髋臼假体的解剖位重建、将髋臼内壁打磨穿透内移的中心化重建、和在真性髋臼上方假臼高位重建3种常见的临床手术方案，模拟不同臼杯假体位置对全髋关节置换术后髋臼假体稳定的影响。结果髋臼假体在真臼位置安放的解剖重建，出现应力集中和大剪切应力的可能性最小，穿透内移安放的模拟应力分布略高于真臼重建，而在假体上移高位安放的模拟则出现预测应力大幅增加。结论成人髋关节发育不良全髋关节置换术中应尽可能在真臼位置重建和安放臼杯假体，以达到最优的应力分布和稳定性。     

人工髋关节置换术后并发症防治的护理体会

对58例髋关节置换病人，从术前的心理疏导、全身的护理评价、充分的术前准备至术后的一般护理、并发症防治的护理、功能锻炼、出院指导，给予全程的护理干预．随访1～2年，假体松动1例，57例未发生其他并发症．     

基于Kane方程的3SPS+1PS并联仿生髋关节试验机动力学研究

针对一种以空间对称3SPS+1PS并联机构为核心模块的髋关节试验机,为分析其动力学特性,基于凯恩方程法,从并联机构的运动学出发,建立了各主动支链与动平台中心点速度、加速度之间的关系。选取动平台中心点的速度和姿态角的导数为广义速率,得到了各构件的偏角速度、偏速度,考虑并联试验机的摩擦环节,建立了库伦摩擦模型;并通过得到的广义惯性力、广义主动力和广义摩擦力建立并联试验机的动力学模型。通过对动力学模型仿真得到主动支链的驱动力和驱动功率,并分析其动力学特性及摩擦力的影响。