This paper reports a new study for comparing two double-bundle reconstructions of anterior cruciate ligament (ACL), used by one of the authors in surgery. It describes the experimental setup, protocol and results in a sample case. The experiment was performed in five steps, using FlashPoint optical system: first the intact knee kinematics was analysed; then ACL was resected and the knee examined; ACL was reconstructed using the gracilis semitendinous tendon and the new kinematics recorded; ACL was reconstructed again with the same tendon and a different orientation of the femoral tunnel and kinematics was recorded; finally the knee was dissected to digitize bone surfaces, ligaments insertions and tunnel position. The off-line elaboration of data allowed to evaluate anatomical and functional results. The comparison of reconstructed knee laxities and ranges of motion with normal and ACL-deficient knee suggested that the most vertical tunnel performed better than the horizontal one.