Generating finite element models of the knee: How accurately can we determine ligament attachment sites from MRI scans?

In this study, we evaluated the intra- and inter-observer variability when determining the insertion and origin sites of knee ligaments on MRI scan images. We collected data of five observers with different backgrounds, who determined the ligament attachment sites in an MRI scan of a right knee of a 66-year-old male cadaver donor. We evaluated the intra- and inter-observer differences between the ligament attachment center points, and also determined the differences relative to a physical measurement performed on the same cadaver. The largest mean intra- and inter-observer differences were 4.30 mm (ACL origin) and 16.81 mm (superficial MCL insertion), respectively. Relative to the physical measurement, the largest intra- and inter-observer differences were 31.84 mm (superficial MCL insertion) and 23.39 mm (deep MCL insertion), respectively. The results indicate that, dependent on the location, a significant variation can occur when identifying the attachment site of the knee ligaments. This finding is of particular importance when creating computational models based on MRI data, as the variations in attachment sites may have a considerable effect on the biomechanical behavior of the human knee joint.