Huang X, et al. - Eighteen lumbar vertebrae (L1–6) from three fresh calf spines to insert 6.5 × 40-mm pedicle screws (considered standard for treatment of spinal degenerative diseases, fractures, tumors, and deformities) were utilized in this study by the researchers in order to compare the biomechanics of reinserted pedicle screws using the former entry point and trajectory with those of perfectly inserted pedicle screws. In group A, the experimental screw was removed after being totally inserted, in group B, after 80% of the total trajectory implanted and in group C, the experimental screw was removed after 60% of the total trajectory was attained. Among reinserted screws and correct screws in the 3 groups, no important variations in pedicle screw axial pullout strength were seen. In comparison with that of the control screw, stiffness measurement raised for the reinserted screw. Fracturing was seen between the vertebral body and pedicle. Hence, using the previous entry point and trajectory, a surgeon could remove the pedicle screw when necessary, inspect the trajectory, and reinsert the screw, theoretically.