This experimental cadaver study assessed computer navigation for the arthroscopic measurement of full-thickness cartilage defects in the knee joint. Cartilage defects were measured during arthroscopy using three cartilage defect-managing modules to compare fixed (invasive) and noninvasive rigid-body fixations. The comparison of all three systems tested revealed a difference between the noninvasive and the fixed rigid-body fixation, with a mean value of 0.07 mm for the width, 0.15 mm for the height, and 0.17 mm for the surface area of the cartilage defect (P > .05). Every point of the cartilage defect was attainable with the pointer tip. The force applied to the instrument during the defect palpation to keep the leg stable during the navigation process was acceptable. In conclusion, the cartilage defect-managing module allows the precise measurement of full-thickness cartilage defects in the knee joint during arthroscopy and that the module can be used with noninvasive rigid-body fixation.