Page 125 - Demo

Reliability on determining the footprint of the torn ACL on MRI12362.97 mm between the first and second assessment. The assessments of the x-coordinate showed an excellent agreement, while those on the yand z-coordinates showed slightly lower ICC values, but still classify as excellent agreement. This miniscule difference, although not significant, could be explained by the anterior-to-posterior and caudal-to-cranial planes compared to the lateral-to-medial plane. This implies that nearly all observers selected the same sagittal slice to identify the center of the femoral footprint of the ACL. The challenge in identifying the femoral footprint of the ACL is how deep and/or how high the footprint is located on the medial wall of the lateral femoral condyle, hence the anterior-toposterior and caudal-to-cranial planes (y-coordinate and z-coordinate respectively). This seems to be reflected in the found ICCs.Our results are in contrast to those of Swami et al, who studied 62 MRI scans in pediatric patients, half of which contained an ACL tear.19 A mean intraobserver difference of 1.2 mm (± 0.7mm) and a mean interobserver difference of 1.8mm (±1.1mm) were shown. Swami et al asked their observers, which included one radiologist and one medical student, to identify the entire geometry of the footprint of the ACL, out of which a center point was calculated and used for comparison.19 The geometry of the femoral insertion of the ACL compromises approximately 100mm2(50-197mm2 reported).9,18,20 In our study, observers were asked to identify the center of the footprint with a small circle of only 8 pixels, replicating a Kirschner wire in the center of the stump of the torn ACL. Identifying a surface from which a center point is calculated may be more forgiving than direct determination of a center point which can explain the difference in results between our study and the results of Swami et al. On the other hand, asking an observer to determine the center of the femoral footprint can be regarded as a more complex task compared to drawing the entire geometry of the femoral footprint of the ACL. When an observer is asked to identify a center of an ellipse, one first has to define the ellipse in his mind. This potentially decreased the reliability as a consequence of the methods used in our study, but still excellent reliability is demonstrated. Swami studied pediatric patients ranging from 10-17 years of age.19 Our study only included scans of subject with closed epiphysis of the distal Mark Zee.indd 123 03-01-2024 08:56