Fig. 3

The Bland–Altman analysis [13] was performed by plotting the difference between the two measurement techniques against their average. The analysis showed that the means of the measurement pairs were spread evenly and randomly, and therefore, no systematic error existed for a native (1580 m/s) and b adjusted speed of sound (1696 m/s) in cartilage. CT = computed tomography, US = ultrasonography, CI = confidence interval