OBJECTIVE: to analyze experimentally the early alterations of the bone-screw interface with tapping techniques in the cancellous bone of the cervical vertebrae. METHODS: five wooless sheep (Santa Inês) were analyzed. Pilot holes of 2.5 mm were performed at both sides of the third cervical vertebrae in the proximal and distal portion. The tapping process was done in the right proximal hole before the 3.5 mm screw insertion (Group A), while the left proximal hole was not tapped (Group B) and the two distal holes were used as control (Group C). The interface alterations between bone and screw were analyzed through histomorphometric study, considering the number of trabeculae fractures between the screw pitch; the highest distance of transversal trabeculae fracture caused by the screw insertion; the greatest extension of the longitudinal trabeculae fracture caused by the screw insertion and the contact line between bone and screw. RESULTS: tapping the pilot hole caused alterations of bone tissue microstructure around the implant, when compared to alterations produced by insertion of the screw, without tapping or pilot hole. The evaluation of the contact between bone and screw was the parameter that presented statistical difference in comparison between the insertion of the implant with and without tapping. CONCLUSION: in comparison with the pilot hole, all the analyzed parameters presented statistical difference.
Spine; Bone screws; Spinal fusion
