The joint surgery system includes a treatment tool capable of performing a high-frequency treatment using a high-frequency current and an ultrasonic treatment using ultrasonic vibration on a treatment target site in a joint cavity filled with a conductive liquid, and the high-frequency device. A high-frequency output unit that outputs high-frequency energy for treatment to the treatment tool, an ultrasonic output unit that outputs ultrasonic energy for ultrasonic treatment to the treatment tool, and a measurement unit that measures the temperature of the liquid And when the measurement temperature measured by the measurement unit is equal to or higher than a predetermined temperature, the high frequency output unit is controlled to stop the output of the high frequency energy, and the output of the ultrasonic energy is continued. A control unit that controls the ultrasonic output unit.関節用手術システムは、導電性の液体で満たした関節腔内の処置対象部位に対して、高周波電流による高周波処置と超音波振動による超音波処置とを行なうことが可能な処置具と、前記高周波処置のための高周波エネルギーを前記処置具に出力する高周波出力部と、前記超音波処置のための超音波エネルギーを前記処置具に出力する超音波出力部と、前記液体の温度を測定する測定部と、前記測定部で測定した測定温度が所定の温度以上である場合に、前記高周波エネルギーの出力を停止させるように前記高周波出力部を制御し、前記超音波エネルギーの出力を継続するように前記超音波出力部を制御する制御部と、を備える。
