What causes cold bi syndrome?

Cold Bi syndrome refers to a condition characterized by excessive cold pathogenic influence invading the bones and tendons, with limb and joint areas being the primary sites of pain. Clinical manifestations include severe, fixed-location pain in the limbs and joints; pain alleviated by warmth but exacerbated by cold; restricted joint flexion and extension; non-erythematous skin in some areas; and no local warmth upon palpation. Pulse Bi syndrome arises during a later stage of Wind-Bi, Cold-Bi, or Damp-Bi when pathogenic factors transform into heat and impair Yin, often triggered by prolonged or persistent fever. Symptoms include joint pain accompanied by localized heat, swelling, and tenderness; slight relief with cooling measures; marked tenderness on palpation; involvement of one or multiple joints; and frequently associated systemic symptoms such as high fever, aversion to wind, dry mouth, and irritability.