Min Lee Jong, Baek Seung-Hoon, Soo Lee Yeon
Department of BioMedical Engineering, School of BioMedical Science, Daegu Catholic University, Gyungbuk, South Korea.
Department of Orthopedic Surgery, School of Medicine, Kyungpook National University, Kyungpook National University Hospital, Daegu, South Korea.
Front Surg. 2022 Dec 26;9:997848. doi: 10.3389/fsurg.2022.997848. eCollection 2022.
PolyWare™ software (PW) has been exclusively used in the majority of polyethylene wear studies of total hip arthroplasty (THA). PW measurements can be significantly inaccurate and unrepeatable, depending on imaging conditions or subjective manipulation choices. In this regard, this study aims to shed light on the conditions needed to achieve the best accuracy and reliability of PW measurements.
The experiment looked at how PW fluctuated based on several measurement conditions. x-ray images of in-vitro THA prostheses were acquired under a clinical x-ray scanning condition. A linear wear rate of 6.67 mm was simulated in combination with an acetabular lateral inclination of 36.6° and anteversion of 9.0°.
Among all the imported x-ray images, those with a resolution of 1,076 × 1,076 exhibited the best standard deviation in wear measurements as small as 0.01 mm and the lowest frequencies of blurriness. The edge detection area specified as non-square and off the femoral head center exhibited the most blurriness. The x-ray image that scans a femoral head eccentrically placed by 15 cm superior to the x-ray beam center led to a maximum acetabular anteversion measurement error of 5.3°.
Because PW has been the only polyethylene wear measurement tool used, identifying its sources of error and devising a countermeasure are of the utmost importance. The results call for PW users to observe the following measurement protocols: (1) the original x-ray image must be a 1,076 × 1,076 square; (2) the edge detection area must be specified as a square with edge lengths of 5 times the diameter of the femoral head, centered at the femoral head center; and (3) the femoral head center or acetabular center must be positioned as close to the center line of the x-ray beam as possible when scanning.
PolyWare™软件（PW）在大多数全髋关节置换术（THA）的聚乙烯磨损研究中被独家使用。PW测量可能会因成像条件或主观操作选择而存在显著的不准确和不可重复性。在这方面，本研究旨在阐明实现PW测量最佳准确性和可靠性所需的条件。
该实验研究了PW如何基于多种测量条件波动。在临床X射线扫描条件下获取体外THA假体的X射线图像。模拟了6.67 mm的线性磨损率，并结合36.6°的髋臼外侧倾斜度和9.0°的前倾角。
在所有导入的X射线图像中，分辨率为1076×1076的图像在磨损测量中表现出最佳的标准差，低至0.01 mm，模糊频率最低。指定为非正方形且偏离股骨头中心的边缘检测区域模糊度最高。将股骨头置于比X射线束中心上方15 cm处进行偏心扫描的X射线图像导致髋臼前倾角测量最大误差为5.3°。
由于PW一直是唯一使用的聚乙烯磨损测量工具，识别其误差来源并制定对策至关重要。结果要求PW用户遵循以下测量方案：（1）原始X射线图像必须为1076×1076的正方形；（2）边缘检测区域必须指定为边长为股骨头直径5倍的正方形，以股骨头中心为中心；（3）扫描时股骨头中心或髋臼中心必须尽可能靠近X射线束的中心线定位。
