Figure 1. Confirmation of situations at the time of an ACL injury by physical therapists (photo by Hirokazu Kobayashi, the first author): The data of "injury mechanism," "dynamic alignment," etc. from the interviews and observation of the subjects were kept in medical records: (1) Skilled physical therapists listened to the subjects mention situations at the time of the injury and requested them to reproduce the situations at the time of the injury as accurately as possible. (2) & (3) The skilled physical therapists also requested them to reproduce the scene by using the unaffected leg to confirm the injury mechanism and the dynamic alignment at the time of the injury.