Vibration transmission member, ultrasonic treatment instrument, and method of manufacturing vibration transmission member

An ultrasonic treatment instrument comprising:

• a vibration transmission member configured to transmit ultrasonic vibration;
• and
• a jaw configured to grip a living tissue between the jaw and the vibration transmission member, wherein:
• the vibration transmission member includes:
• a main body configured to transmit the ultrasonic vibration,
• a treatment portion located at the distal end of the main body, the treatment portion being configured to grip the living tissue between the treatment portion and the jaw, and the treatment portion configured to apply the ultrasonic vibration to the living tissue,
• a first covering formed of a material that has an electrical insulating property and has a thermal conductivity lower than a thermal conductivity of the main body, the first covering covering a part of a surface of the treatment portion, and
• a second covering formed of a material that has an electrical insulating property and has a thermal conductivity lower than the thermal conductivity of the main body, the second covering located on the first covering, wherein
• the second covering includes a first area and a second area, the first area located adjacent to the second area in a peripheral direction of the main body and disposed closer to a jaw side than the second area is,
• a thickness of the first area is smaller than a thickness of the second area,
• the treatment portion includes:
• a treatment surface configured to apply the ultrasonic vibration to the living tissue, and
• a back surface opposite to the treatment surface, and
• the first covering and the second covering cover the surface of the treatment portion which excludes the treatment surface and includes at least the back surface.

A vibration transmission member comprising:

• a main body configured to transmit ultrasonic vibration;
• a treatment portion located at the distal end of the main body, the treatment portion configured to apply ultrasonic vibration to a living tissue, the treatment portion including a curved portion curved in a first direction;
• a first covering formed of a material that has an electrical insulating property and has a thermal conductivity lower than a thermal conductivity of the main body, the first covering covering a part of a surface of the treatment portion;
• and
• a second covering formed of a material that has an electrical insulating property and has a thermal conductivity lower than the thermal conductivity of the main body, the second covering located on the first covering, wherein
• the second covering includes a first area and a second area, the first area located adjacent to the second area in a peripheral direction of the main body, and
• a thickness of the first area is smaller than a thickness of the second area,
• the first area includes a first cutout and a second cutout, the first cutout is located in a side of the first direction, and the second cutout is located in a side of a second direction opposed to the first direction.