Hello: Traditional Chinese medicine believes that madder has the effects of cooling blood and stopping bleeding, removing blood stasis, and stimulating menstruation. It is mainly used to treat blood heat, vomiting and epistaxis, metrorrhagia, amenorrhea, blood stasis, bruises, and rheumatic arthralgia. Millet Spatholobus has the effects of promoting blood circulation, regulating menstruation and relieving pain, relaxing muscles and activating collaterals. It is used for irregular menstruation, dysmenorrhea, amenorrhea, rheumatic arthralgia, numbness and paralysis, blood deficiency and chlorosis. As you said, "eating madder and millipedia" is definitely effective for knee pain.