Chen Eduard, Goertz Wolfgang, Lill Christophe A
Department of Orthopedic Surgery, University of Heidelberg, Germany.
Comput Aided Surg. 2006 Nov;11(6):309-16. doi: 10.3109/10929080601090516.
The purpose of this study was to investigate the relationship of cup position versus pelvic lateral tilt and inclination. While computer assisted navigation systems use only the pelvic frontal plane for cup placement, it is important to realize the effect of leg length differences or increased pelvic inclination, i.e., caused by contracted hip flexors.
Using a sawbone model of the pelvis, cup position measurements were performed with different pelvic inclination and lateral tilt angles. The measured values were compared with outcome variables from a mathematical model. A computer program was developed to perform a reverse calculation to verify the mathematical model.
The mathematical model proved correct in the sawbone pelvis experiment. The cup position changed from 15 degrees anteversion in 0 degrees pelvic inclination to 0.5 degrees retroversion in 15 degrees pelvic inclination. Regardless of pelvic inclination, the vertical cup projection stayed in a safe range of 37-47 degrees. Leg length differences greater than 3 cm have significant effects on the positioning of acetabular cups in the frontal plane.
Using computer navigation, it is possible to determine pelvic inclination and lateral tilt during an operation by calculating the angular difference between the anatomic frontal plane and the "real world" frontal plane (i.e., the OR table). This method may be helpful in increasing the accuracy of positioning of acetabular cups.
本研究旨在探讨髋臼杯位置与骨盆侧倾及倾斜度之间的关系。虽然计算机辅助导航系统在髋臼杯置入时仅使用骨盆额状面，但认识到腿长差异或骨盆倾斜度增加（即由髋屈肌挛缩引起）的影响很重要。
使用骨盆的锯骨模型，在不同的骨盆倾斜度和侧倾角度下进行髋臼杯位置测量。将测量值与数学模型的结果变量进行比较。开发了一个计算机程序来进行反向计算以验证数学模型。
在锯骨骨盆实验中，数学模型被证明是正确的。髋臼杯位置从骨盆倾斜度为0度时的前倾15度变为骨盆倾斜度为15度时的后倾0.5度。无论骨盆倾斜度如何，髋臼杯的垂直投影都保持在37 - 47度的安全范围内。腿长差异大于3 cm对髋臼杯在额状面的定位有显著影响。
使用计算机导航，在手术过程中通过计算解剖学额状面与“真实世界”额状面（即手术台）之间的角度差异，可以确定骨盆倾斜度和侧倾。这种方法可能有助于提高髋臼杯定位的准确性。
