FIG. 1.

(Top) The LISA consists of the following: (1) impactor complex that measures tissue displacement and causes the contusion, (2) spine stabilizer that secures the spinal cord, (3) vibration isolator that prevents vibration from being transmitted from the impactor complex to the force sensor located below the spine stabilizer, (4) base, and (5) control box that contains circuits that control the impactor position and its duration of contact with the spinal cord. It also conveys biomechanical information to the impactor complex. (Bottom) Cartoons of the impactor complex illustrate the mechanism of tissue displacement control. In position A, the distance from the laser sensor (pink vertical line) to the reflecting surface (DRS) of the impactor is calibrated in its fully extended position (vertical large arrow). Tip distance (TD) = tip thickness (3 mm) + DRS. In position B, the impactor is withdrawn and moved laterally away from the laser beam path (horizontal large arrow). The distance from the laser sensor to the spinal cord is measured (cord distance [CD]). The desired tissue displacement is determined by the difference between the cord distance and tip distance (CD-TD). The impactor is returned back to the laser beam path and is ready for impact.