Forensic age estimation of living persons from the knee: Comparison of MRI with radiographs

To perform a study to clarify how strong the chronological age relates to ossification of the knee in Chinese on X-rays and the MRI when a similar four-stage grading system was used. 322 individuals with conventional radiographs and MRI were collected from routine medical investigations and evaluated retrospectively. Bland Altman plots were performed to reveal the agreement of grading of MRI and radiograph. Regression analysis was conducted to establish a mathematical model for age estimation. The ossification process of the knee occurs earlier in females than in males for about 1-2 years. The process on X-ray grading is consistently higher than that of MRI. The chronological age is well correlated with both grading of MRI and radiograph (all p values were less than 0.001). By comparison, the R-square of grading of MRI were relatively higher than that of radiograph. Finally, the chronological age is well correlated with the ossification of the knee when both grading of MRI and radiograph were used, with the R-square for MRI were relatively higher than that of radiograph. Furthermore, the use of MRI will reduce exposure to X-ray radiation as much as possible.