The

Medical Cases of WU Jutong

（《吴鞠通医案》） proposes the principle of "treating all

Bi

（痹） diseases through

taiyin

"， which forms the basis for analyzing WU Jutong's understanding of the causes， mechanisms， and treatments of

Bi

（痹） diseases， providing a reference for clinical diagnosis and treatment. Through an interpretation of the phrase "treating all

Bi

（痹） diseases through

taiyin

"， it is suggested that

Bi

（痹） diseases is primarily caused by dampness， necessitating a focus on spleen and lung in treatment. WU emphasized four main causes of

Bi

（痹） diseases （wind， cold， dampness， and heat）， with dampness being the predominant factor. The disease location is initially in lung， for which external dampness invades lung first， and internal dampness obstructs the source of water metabolism， impeding lung

qi

and

qi

failing to disperse， then dampness further accumulates in the joints， leading

to

Bi

（痹） diseases. WU Jutong proposed the modified

Mufangji Decoction

（木防己汤） as the foundational prescription for treating

Bi

（痹） diseases. By comparing the similarities and differences between the modified and original

Mufangji Decoction

， and analyzing the adjustments in herbal prescriptions， the clinical characteristic of "treating all

Bi

（痹） diseases through

taiyin

" is further substantiated.