A method comprises providing a medical instrument having a first tendon that extends from an interface at a proximal end of the medical instrument to an actuated element at a distal end of the medical instrument. The first tendon has a first tension in the medical instrument as provided. The interface comprises a first plate connected to a second plate by a support. The first tendon has a portion extending between the first and second plate and passing through holes in the first and second plates. The interface also comprises an engagement structure attached to a proximal end of the first tendon. The method also comprises receiving the engagement structure into engagement with a manipulator which includes increasing tension in the first tendon from the first tension to a preload tension. After receiving the engagement structure, the actuated element is actuated by pulling the first tendon.
