The information provided here is not a replacement for a doctor. You shouldn't use it for the purpose of self-diagnosing or self-medicating but rather so you can have a more informed discussion with a professional TCM practitioner.
Because it is a herb specifically indicated to treat tendons injuries as can be seen on Japanese Teasel Root's page.
Its main actions are: Tonifies the Liver and Kidneys. Assists in the healing of bones. Both stops bleeding and moves Blood. Calms the foetus.