Sichuan Teasel (Dipsacus asper), known as Xu Duan in Traditional Chinese Medicine (TCM), has been used for centuries to "tonify the liver and kidneys," "strengthen bones and sinews," and support joint health. Its traditional applications often include addressing joint pain, lower back pain, and weakness in the knees, especially attributed in TCM to deficiencies in the kidney and liver systems. The roots are the primary part used in decoctions and herbal formulas for musculoskeletal complaints.

Despite its longstanding use, scientific validation for Sichuan Teasel's effectiveness in supporting joint health remains limited. Some laboratory and animal studies suggest that extracts from the plant may possess anti-inflammatory and osteoprotective properties, which could theoretically benefit joint function or bone health. However, these studies are preliminary and often not directly focused on joint disorders or conducted in humans. There are no well-designed clinical trials in humans that specifically establish its efficacy for joint support.

In summary, the use of Sichuan Teasel to support the joints is primarily justified by traditional usage in TCM, with modest preclinical scientific interest but insufficient high-quality evidence from human studies. Therefore, the evidence rating is 2 out of 5, reflecting established tradition but limited scientific confirmation.