Hananouchi Takehito, Sugano Nobuhiko, Nakamura Nobuo, Nishii Takashi, Miki Hidenobu, Yamamura Mitsuyoshi, Yoshikawa Hideki
Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka Suita, Osaka 565-0871, Japan.
Arch Orthop Trauma Surg. 2007 Jul;127(5):381-5. doi: 10.1007/s00402-007-0349-0. Epub 2007 May 24.
Preoperative femoral templating for total hip arthroplasty (THA) has been performed by antero-posterior radiographs of both hips which should be taken with the femur rotated internally to reduce the effect of femoral anteversion. However, there is no criterion to evaluate the optimal rotated radiograph. Here, we quantitatively investigated 50 femora whether the thickness of the lesser trochanter (TLT) was useful when evaluating the femoral rotation, and assessed the effect of prosthetic templating on the inappropriate rotated radiographs.
We assessed 50 femora of 46 consecutive osteoarthritic patients using "synthetic X-ray" based on computer tomography (CT) images, which can be displayed as virtual plain radiographs with any magnification and any projected direction such as plain radiographs. We made four femoral radiograph groups of different rotation prepared (neutral, 15 degrees, 30 degrees, and 45 degrees external rotation), and measured the TLT. We also templated femoral stem on the different rotated synthetic X-ray of each patient, and investigated the effect of inappropriate rotated radiograph by the measurement of the position and the size of the stem.
Seventy-four percent of the neutral rotational group had less than 5 mm of the TLT. While 30 degrees and 45 degrees external rotation group had few cases with less than 5 mm of the TLT. Compared to the neutral group, smaller stem size was selected in more than 80% cases of 30 degrees and 45 degrees external rotational group, and the stem position in these two groups was more than 5 mm proximally.
We suggest that when templating femoral stem, this criterion "the TLT is less than 5 mm" reduces some risks by inappropriate rotated radiograph.
全髋关节置换术（THA）术前股骨模板测量是通过双髋前后位X线片进行的，拍摄时股骨应内旋以减少股骨前倾的影响。然而，目前尚无评估最佳旋转X线片的标准。在此，我们对50根股骨进行了定量研究，探讨小转子厚度（TLT）在评估股骨旋转时是否有用，并评估假体模板测量在不适当旋转X线片上的影响。
我们基于计算机断层扫描（CT）图像，使用“合成X线”对46例连续骨关节炎患者的50根股骨进行评估，“合成X线”可显示为具有任何放大倍数和任何投影方向的虚拟平片，类似于平片。我们制备了四个不同旋转角度的股骨X线片组（中立位、外旋15度、30度和45度），并测量TLT。我们还在每位患者不同旋转角度的合成X线片上进行股骨柄模板测量，并通过测量柄的位置和大小来研究不适当旋转X线片的影响。
中立旋转组中74%的患者TLT小于5mm。而外旋30度和45度组中TLT小于5mm的病例较少。与中立组相比，外旋30度和45度组中超过80%的病例选择了更小尺寸的柄，且这两组中柄的位置在近端超过5mm。
我们建议，在进行股骨柄模板测量时，“TLT小于5mm”这一标准可降低因不适当旋转X线片带来的一些风险。
