Page 121 - Demo

Reliability on determining the footprint of the torn ACL on MRI1196Data processing and statistical analysis The x, y, z coordinates were calculated for each of the marked points using Statistical Package for the Social Sciences version 23 (SPSS, IBM, Armonk, NY, US). The x-axis represents the lateral-to-medial direction, the y-axis the anterior-to-posterior direction and the z-axis the caudal-to-cranial direction. To quantify the intra- and interobserver reliability, the distance between the first and the second assessment and the distance between observers was calculated for each coordinate and the 3D point ( i.e. x, y, z and 3D). The total 3D distance between the marked points was calculated using the following formula, where x1, y1 and z1 represents observer 1 or measurement 1 and x2, y2 and z2 represents observer 2 or measurement 2.𝐷𝑡𝑜𝑡𝑎𝑙= √(𝑥1−𝑥2)2+(𝑦1−𝑦2)2+ (𝑧1−𝑧2)2Intraclass correlation coefficients (ICC 2-way random, absolute agreement) were calculated between the first and second assessment of an observer and between observer groups (Orthopedic Residents, Orthopedic Surgeons and MSK radiologists). Values less than 0.5 were considered to be indicative of poor reliability, values between 0.5 and 0.75 indicate moderate reliability, values between 0.75 and 0.9 indicate good reliability, and values greater than 0.90 indicate excellent reliability.8 Scatter plots using the Bland & Altman method were used to visually assess agreement between raters.10,16 This was performed for the X, Y, Z and 3D coordinate. The mean difference and the limits of agreement were calculated and depicted in the scatter plots. Statistical analysis were performed in close collaboration with a biostatistician.ResultsThe residents in orthopedic surgery were all in their fifth year of their six year residency program. The orthopedic surgeons had an average experience of 11 years (2,7 and 25 years) in ACL reconstructive surgery. The MSK radiologists had an average experience of 5 years in reading MRI scans of the knee (both 5 years). Mark Zee.indd 119 03-01-2024 08:56