The objective of this paper was to study pedicular screws fixation strength on vertebral bodies by varying its repositioning angle. For this Study, eight pigs were selected, making up a total of 40 lumbar vertebrae, which were divided into 4 study groups. In the first group, the screws were inserted at zero degree, and in the second group, they were inserted and reinserted at the same position, while in the third group, the screws were reinserted within a 14-degree range, and, in the fourth group, within a 28-degree range. All screws were tested for pullout strength. Group I presented a pullout average of 146.85N. Group II presented a pullout average of 77.34N. Group III had an average of 97.75N. Group IV had an average of 110.02. It was concluded that the procedure of replacing screws should be avoided. Should any repositioning is required, this should be performed by changing repositioning angles as much far from the first one as possible.
Spine; Pedicle screws; Biomechanics
