Usefulness of the surgical chair supporting operator’s knees

Wataru Nishimoto¹, Hiroshi Kawahira², Yoshihiro Shimomura³, Masaaki Itoh⁴, Yuji Nishizawa⁴, Takashi Miki⁵, Hisahiro Matsubara⁶. ¹Graduate School of Medical and Pharmaceutical Science, Chiba University, ²Center for Frontier Medical Engineering, Chiba University, ³Division of Design Science, Graduate School of Engineering, Chiba University, ⁴Department of colorectal surgery, National Cancer Center Hospital East, ⁵Department of Medical Physiology, Graduate School of Medicine, Chiba University, ⁶Department of Frontier Surgery, Graduate School of Medicine, Chiba University

In laparoscopic surgery, surgeons are forced to observe a monitor closely and also keep upright posture, and it is considered that they are factors of surgeon’s burden. It has been known that operators realized burden reduction and the operation’s accuracy was improved when they were sitting. We developed the surgical chair to retain operator’s lower limbs by supporting their knees and analyzed the effects. 

Laparoscopic surgeons used the newly developed chair for colorectal surgery. After surgery, we asked the surgeons to fill out questionnaire for their impression. We also got the  both sides of gastrocnemius muscles potential during the surgery. In addition we analyzed the electromyogram and evaluated the muscle burdens of the lower limbs. The measurement is done at gastrocnemius’ surface electromyogram. We converted the obtained data to root mean square (RMS) and calibrated by the maximum voluntary electroactivity, and compared the average of every 10 minutes by the significance test.

In case the subjects used the chair, the amplitude of the electromyogram was significantly smaller at the left leg’s medial head of gastrocnemius muscle, but larger at the right leg’s lateral head.

Considering this results, surgeries also operate a foot switch by a right leg thus the chair became an obstacle to the operation and the burden of the right leg was increased. On the other hand, the left leg that is the pivot foot was effectively reduced the burden for a long time to put the weight by the chair.

We are investigating the hardness of the chair. For a biological measurement, we are going to measure the burden of the lumbar muscle and the intervertebral disk.