Objective To observe the clinical efficacy of Tiaohe Yinyang acupotomy（acupotomy for regulating and harmonizing yin and yang） for knee osteoarthritis（KOA）. Methods A total of 88 patients with KOA were randomized into a acupotomy group and a sham-acupotomy group

44 cases in each group. In the acupotomy group

acupotomy was applied at yin side（4-5 high stress points i.e. pes anserinus and terminal of popliteus） and yang side（1-2 high stress points i.e.stimulation point of infrapatellar ligament and suprapatellar bursa） of knee joint. In the sham-acupotomy group

sham-acupotomy was applied at the same points as the acupotomy group. The treatment was given once a week for 2 weeks in the two groups. Before and after treatment

the Western Ontario and McMaster Universities arthritis index（WOMAC）score

visual analogue scale（VAS） score

thickness of medial and lateral collateral ligaments of knee joint

motion range of knee joint and plantar pressure distribution were observed in the two groups. In the follow-up of 3 months after treatment

the WOMAC and VAS scores were recorded in the acupotomy group. Results After treatment

the sub item scores（pain

stiffness and function） and total scores of WOMAC and VAS scores were decreased in the both groups（P<0.05）

pain score

function score and total score of WOMAC and VAS score in the acupotomy group were lower than those in the sham-acupotomy group（P<0.05）. Before and after treatment

there were no statistical differences in thickness of medial and lateral collateral ligaments of knee joint and motion range of knee joint between the two groups（P>0.05）. After treatment

the plantar medial pressure was increased while the plantar lateral pressure was decreased（P<0.05）

and the plantar force line moved medially in the acupotomy group. In the follow-up

the sub item scores and total score of WOMAC and VAS score were lower than those before and after treatment in the acupotomy group（P<0.05）.Conclusion Tiaohe Yinyang acupotomy can improve the clinical symptoms of knee joint in patients with KOA by changing the local biological stress.