Prevalence of ossification of the sacrotuberous ligament in a Japanese population assessed by postmortem computed tomography.

Individual identification is one of the important roles of forensic medicine. In this process, recognizing specific anatomical features on the remains of the victims is important. Ossification of sacrotuberous ligament (OSTL) is a rare condition found on pelvic bones. Its mechanisms of development and epidemiology remain unknown. Although there are some case reports, there is no study that studied the prevalence of OSTL in the Japanese population. In forensic fields, postmortem computed tomography (PMCT) is gaining more attention. As it is recommended to include the whole body in the scan range, it enables forensic practitioners to observe body parts that are not routinely dissected during a standard autopsy, and pelvic bone is one of those parts. This study aimed to determine the prevalence of OSTL in the Japanese population by PMCT image analysis. This study included 540 cases from a single institution. Of those cases, there were 17 (3.1%) OSTL cases in total. The average age of OSTL-positive cases was 72.6 years old. While unilateral development of the right side was highest in the group, only one case showed bilateral development. We showed right-side predominant occurrences in elderly men, which is similar to the previous results from overseas. The rarity of OSTL may work as a good marker at superimposition, the method utilized for individual identification on PMCT. For better understanding and discussing its validity, more studies on OSTL are needed in the future.