DESIGN OF CEMENTLESS FEMORAL PROSTHESES ADAPTIVE TO SECONDARY

通过对55例骨关节炎患者的85个髋关节和60例正常髋关节患者的90个髋关节的三维CT图像分析，我们发现需要9种不同宽度和近端半径的不同干设计来适应继发性骨关节炎的髋关节。在正常髋中，观察股骨近端管与股骨长度的解剖特征的比例性。因此，我们制作了股骨颈骨折和股骨头无菌性坏死的原型柄，其近端半径、峡部位置、偏移值和宽度会随着柄的大小而增加，但增加的比例不同。通过对股骨颈骨折和股骨头无菌性坏死的原型柄、Omniflex柄、Omniflex j -柄（Osteonics,Allendale,New Jersey）和AML柄（DePuy,Warsaw,Indiana）的微动测量，在2000 N的轴向循环载荷下，柄的最大微动平均值分别为43.1mum、54.7mum、62.0mum和56.2mum，均为上下方向近端微动。在20 Nm旋转载荷下，最大微动平均值分别为38.0、48.0、55.2和67.5 mum，均为前后方向近端微动。在2000N轴向载荷下，股骨近端内侧受压应变分别为完整股骨的18.6%、23.6%、25.9%和44.6%。通过计算机模拟对股骨假体进行三维模板化，针对髋关节二次骨关节炎设计的原型假体、Omniflex假体、Omniflex j型假体和AML型假体近端管填充率（管内横截面比例）分别为61.2%、59.8%、56.5%和53.8%，近端磨齿率（磨齿皮质在皮质区域内的比例）分别为1.10%、1.69%、1.30%和5.17%。根管峡位充填率分别为75.8%、68.1%、68.6%和74.1%，根管峡位充填率分别为0.69%、0.68%、0.70%和2.25%。因此，我们使用三维CT图像设计的原型柄具有最小的微动、最高的管腔填充率和最低的摩擦率，因此获得了满意的初始固定和与股骨管的相容性。少

Analyzing the anatomical features of the hip joint in 85 hips of 55 patients with osteoarthritic hip and 90 hips of 60 subjects with normal hip using three-dimensional CT images,we found that 9 different stem designs varying in width and proximal radius were required to accommodate the hips with secondary osteoarthritis.In normal hips,the proportionality of the anatomical features of the proximal femoral canal to the femoral length was observed.Thus,we manufactured prototype stems for femoral neck fracture and aseptic necrosis of the femoral head which proximal radius,isthmus position,off-set value and width would increase with the stem size,but the ratios of the increase were different.By micromotion measurements of the prototype stems for femoral neck fracture and aseptic necrosis of the femoral head,Omniflex stem,Omniflex J-stem (Osteonics,Allendale,New Jersey) and AML stem (DePuy,Warsaw,Indiana), under the axial cyclic loading of 2000 N,maximum average of micromotion of the stems w … More ere each 43.1mum,54.7mum,62.0mum and 56.2mum,that were all proximal micromotions in superior-inferior direction.Under the rotational loading of 20 Nm,maximum average of micromotions were each 38.0mum,48.0mum,55.2mum and 67.5 mum,that were all proximal micromotions in anterior-posterior direction.The proximal medial compression strains of the femur were each 18.6%,23.6%,25.9% and 44.6% of those of the intact femur under the 2000N axial loading.By three-dimensional templating of femoral prostheses using computer simulation,canal filling ratios(ratio of the cross-section of the stem within the canal area) in proximal of the prototype stem designed for secondary osteoarthritis of the hip,Omniflex stem,Omniflex J-stem and AML stem were each 61.2%,59.8%,56.5% and 53.8%,and rasp ratios(ratio of the rasped cortex within the cortex area) in proximal of those were 1.10%,1.69%,1.30% and 5.17 %. Canal filling ratios in isthmus level of those stems were each 75.8%,68.1 %,68.6% and 74.1%,and rasp ratios in isthmus level were each 0.69%,0.68%,0.70% and 2.25%.Therefore, our prototype stems designed using three-dimensional CT images had smallest micromotion,highest canal filling ratio and lowest rasp ratio,so obtained satisfied primaly fixation and compatibility to the femoral canal. Less