Comparative study of manual and digital method in the calculation of the tibial plateau angle in dogs

ABSTRACT There are few published data on the applicability and reliability of digital methods for measuring the TPA compared with manual measurement. The objective of this study was to compare the TPA obtained by calculating standard manual on conventional radiographs, with the values obtained by calculations in digital images through a computer program. Bilateral digital radiographs of hind limb were analyzed in true profile for 20 healthy dogs older than two years. Three observers with similar levels of experience in calculating the TPA conducted measurements on each radiograph. First we calculated the angle of the tibial plateaus manually in x-ray film and then the calculations were made through the program offered by the computer program in the digital image. The results of this study showed significant differences between the methods, with average value of 20.48±3.71 digital calculating average and 23.90±2.4 in the manual calculation. P value was < 0.01 when comparing averages. No significant difference in manual calculation in right profile were found between interobserver assessments, suggesting greater variation in manual calculation compared to digital. The calculation performed by the software showed less variation in values. The slight variation obtained in our results is believed to be due to the facilities provided by the software. There was a difference between the values obtained by means of conventional and digital methods for calculating the angle of the tibial plateau, and the smaller digital values between the observers and the digital method in the calculation of the tibial plateau angle led to less variation when compared to the manual method.

摘要 目前鲜有公开数据探讨数字化测量方法相较于手工测量法在胫骨平台角（Tibial Plateau Angle，TPA）测量中的适用性与可靠性。本研究旨在对比通过常规X线片手工计算得到的TPA值，与通过计算机程序对数字影像进行计算得到的TPA值。研究纳入20只年龄大于2岁的健康犬，对其后肢双侧数字X线片采用标准侧位（true profile）进行分析。3名在TPA测量领域经验水平相近的观察者对每一张X线片开展测量：首先通过X线胶片手工计算胫骨平台角，随后借助计算机程序对数字影像完成计算。本研究结果显示两种测量方法存在显著性差异：数字化计算法的平均结果为20.48±3.71，手工计算法的平均结果为23.90±2.4。两组均值比较的P值小于0.01。观察者间对右侧侧位片的手工测量结果未发现显著性差异，这提示相较于数字化方法，手工测量的变异程度更大；而软件计算得到的数值变异程度更低。本研究观测到的微小结果变异，被认为源于软件所提供的操作便利性。常规测量方法与数字化方法在胫骨平台角计算中得到的数值存在差异；相较于手工测量法，数字化测量方法以及观察者间的数字化计算结果均表现出更低的变异程度。