膝关节统计学形状模型的几何外形有效性验证

Geometric Shape Validation of Knee Statistical Shape Model

目的获取中国男性健康膝关节的解剖参数范围,并验证健康膝关节统计学形状模型(statistical shape model,SSM)在几何外形上的有效性,为基于膝关节SSM的假体设计提供依据。方法采集112例健康男性膝关节CT影像,建立三维膝关节模型,每例模型都单独作为目标模型,剩余模型作为训练集进行主成分分析(principal component analysis,PCA),将得到的SSM向着目标模型进行拟合预测,得到SSM拟合模型。在样本模型和SSM拟合模型上分别标记出相同的解剖测量点,并得出17个线性参数和3个角度参数。对解剖参数值采用独立样本t检验和Mann-Whitney U检验进行统计学检验,若得出的P值均大于0.05,则证明SSM在几何外形上的有效性。结果解剖参数的定性和定量对比分析的结果显示,线性参数值的平均偏差均小于6 mm,角度参数值均小于2.5°;统计学检验的结果显示所有解剖参数的P>0.05,证明膝关节SSM拟合模型与真实健康模型在几何外形上不具有统计学差异。结论获得了健康膝关节解剖参数的参考范围,并验证了膝关节SSM模型在外形上与真实健康模型具有一致性。研究结果为基于膝关节SSM的假体设计提供依据。

Objective To obtain the range of anatomical parameters of healthy knee joints in Chinese males and validate a statistical shape model(SSM)based on the geometric shape of a healthy knee to provide references for the design of knee SSM-based prostheses.Methods Computed tomography(CT)images of knee joints from 112 healthy males were acquired to build three-dimensional(3D)knee joint models.Each model was the target model separately,and the remaining models were used as the training set for principal component analysis(PCA).The obtained knee SSM was fitted to the target model to predict the SSM.The exact anatomical measurement points were marked on the sample and SSM prediction models,and 17 linear and 3 angular parameters were derived.The values of the anatomical parameters were statistically tested using an independent samples t-test and Mann-Whitney U-test,and the validity of the SSM in terms of geometric shape was demonstrated if the resulting P-values were all greater than 0.05.Results Qualitative and quantitative comparative analyses of anatomical parameters showed that the mean deviation of linear parameters was less than 6 mm,and that of angular parameters was less than 2.5°.The results of statistical tests showed P>0.05 for all anatomical parameters,proving that the knee SSM prediction model was not statistically different from the true healthy model in terms of geometric shape.Conclusions This study derived a reference range of anatomical parameters for a healthy knee and demonstrated that the knee SSM model was consistent with the real healthy model in terms of shape.The results provide a reference for the design of knee SSM-based prostheses.