Viceconti Marco, Chiarini Alessandro, Testi Debora, Taddei Fulvia, Bordini Barbara, Traina Francesco, Toni Aldo
Laboratorio di Tecnologia Medica, Istituti Ortopedici Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy.
Langenbecks Arch Surg. 2004 Oct;389(5):400-4. doi: 10.1007/s00423-003-0446-7. Epub 2004 Jan 15.
All computer-aided surgery technologies assume that the surgeon knows the best position for the implant components. However, there is indirect evidence that simple anatomical information may not be sufficient for the surgeon to decide size and position of the implant in a repeatable manner.
In the present study we estimated the variability in choosing the size and position of the components of a cementless total hip replacement (THR), using template-on-radiograph as well as computed tomography (CT)-based computer-aided planning. In addition, using a computer model, we assessed the sensitivity to such variability of implant fitting, location of the joint centre, skeletal range of motion, and resting length of major hip muscles. Using templates, surgeons selected the size with variability up to 2.5 mm for the stem and up to 4 mm for the socket. A similar variability was also observed when the CT-based planning program was used.
No major differences were found between surgeons. The standard deviation over repeated planning sessions of the selected position for each component, using the CT-based planning software, was found to be 3.9 mm and 8.9 degrees .
On the basis of the computer simulation, this variability did not affect the selected biomechanical parameters in a drastic way, although some differences were observed, especially in the lever arm of the hip muscles.
所有计算机辅助手术技术都假定外科医生知道植入部件的最佳位置。然而，有间接证据表明，简单的解剖学信息可能不足以让外科医生以可重复的方式决定植入物的尺寸和位置。
在本研究中，我们使用X线片模板以及基于计算机断层扫描（CT）的计算机辅助规划，估计了非骨水泥型全髋关节置换术（THR）部件尺寸和位置选择的变异性。此外，我们使用计算机模型评估了植入物拟合、关节中心位置、骨骼运动范围和主要髋部肌肉静息长度对这种变异性的敏感性。使用模板时，外科医生选择的股骨柄尺寸变异性高达2.5毫米，髋臼杯尺寸变异性高达4毫米。使用基于CT的规划程序时也观察到了类似的变异性。
外科医生之间未发现重大差异。使用基于CT的规划软件，每个部件所选位置在重复规划过程中的标准差为3.9毫米和8.9度。
基于计算机模拟，尽管观察到了一些差异，尤其是在髋部肌肉的力臂方面，但这种变异性并未对所选生物力学参数产生重大影响。
