Medical instrument

A medical instrument comprising:

• a housing;
• a fixed handle;
• a movable handle that is configured to move relative to the fixed handle, the movable handle being configured to move from a first position to a second position in a direction towards the fixed handle, the second position being a position of the movable handle that is closest to the fixed handle;
• and
• a spring provided between the housing and the movable handle and configured to apply a biasing force to the movable handle, the medical instrument being configured to control the biasing force generated in the spring when the movable handle moves from the first position to the second position,
• wherein:
• the medical instrument is configured such that:
• the biasing force of the spring against the movable handle increases as the movable handle moves from the first position to the second position, and the biasing force of the spring in the first position is less than the biasing force of the spring in the second position, and
• as the movable handle moves from the first position to the second position, an amount of increase in the biasing force generated in the spring decreases when the spring is closer to the second position than the first position, and
• the movable handle is configured to move from the second position to the first position with respect to the fixed handle by the biasing force of the spring when a surgeon releases a grip of the movable handle with respect to the fixed handle.