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.
Japanese Teasel Roots is a Warm herb that tastes Bitter and Sour. It targets the Kidney and the Liver.
Its main actions are: Tonifies the Liver and Kidneys. Assists in the healing of bones. Both stops bleeding and moves Blood. Calms the foetus.
Joint stiffness Sore lower back Sore knees Fractures Abnormal uterine bleeding Traumatic injuries Restless foetus Uterine bleeding during pregnancy Threatened miscarriage Arthralgia