基于MRI和CT二维图像重建膝关节三维数字化模型的股骨髁扭转角差异性研究

COMPARISON OF FEMORAL CONDYLAR TWIST ANGLE IN THREE DIMENSIONAL RECONSTRUCTION DIGITAL MODELS OF KNEE JOINT BASED ON TWO DIMENSIONAL IMAGES OF MRI AND CT

目的研究基于MRI和CT二维图像建立的人膝关节三维数字化模型上股骨髁扭转角(femoral condylar twist angle,CTA)测量的差异,为术前股骨假体旋转位置设计中选择最佳CTA测量方法提供参考。方法取10具正常成人尸体膝关节标本,分别于三维数字化模型和尸体标本中测量CTA。实验分为4组:A组为基于MRI二维影像重建三维数字化模型测量组,B组为基于CT二维影像重建三维数字化模型测量组,C组为尸体标本保留膝关节软骨测量组,D组为尸体标本去除膝关节软骨测量组。统计分析各组CTA差异。结果三维数字化模型中A、B组CTA分别为(6.43±0.53)、(3.31±1.07)°,比较差异有统计学意义(t=10.235,P=0.000)。膝关节标本中C、D组CTA分别为(5.21±1.28)、(3.33±1.12)°,比较差异亦有统计学意义(t=5.770,P=0.000)。而A、C组间CTA比较差异无统计学意义(t=3.219,P=0.110),B、C组间差异有统计学意义(t=5.779,P=0.000)。结论在基于MRI二维图像重建的膝关节三维数字化模型上测量的CTA更接近膝关节保留软骨状态下的实际测量值,有利于指导术前规划。

Objective To study the difference of femoral condylar twist angle（CTA） measurement in three dimensional（3-D） reconstruction digital models of human knee joint based on the two dimensional（2-D） images of MRI and CT so as to provide a reference for selecting the best method of CTA measurement in preoperative design for the femoral prosthesis rotational position. Methods The CTA of 10 human cadaveric knee joint was measured in 3-D digital models based on MRI（group A）, in 3-D digital models based on CT（group B）, in the cadaveric knee joint with cartilage（group C）, and in the cadaveric knee joint without cartilage（group D）, respectively. The statistical analysis of the differences was made among the measurements of the CTA. Results The CTA values measured in 3-D digital models were（6.43±0.53）° in group A and（3.31±1.07）° in group B, showing significant difference（t=10.235, P=0.000）. The CTA values measured in the cadaveric knee joint were（5.21±1.28）° in group C and（3.33±1.12）° in group D, showing significant difference（t=5.770, P=0.000）. There was significant difference in the CTA values between group B and group C（t=5.779, P=0.000）, but no significant difference was found between group A and group C（t=3.219, P=0.110）. Conclusion The CTA values measured in the 3-D digital models based on MRI are closer to the actual values measured in the knee joint with cartilage, and benefit for preoperative plan.