Effect of instrumentation growing rods of sliding pedicle screw system insertion on growth of immature porcine spine

Abstract

Objective To investigate the influence of the instrumentation growing rods of sliding pedicle screw system insertion on the growth of the spine in an animal model. Methods A total of 15 pigs （about 3-month age） were randomly assigned into 3 groups： group A, blank control group only exposing posterior lamellar; group B （control group） , inserting the traditional pedicle screw system; group C （test group） , inserting the instrumentation growing rods of sliding pedicle screw system. The average heights of T6, 7, 8, 9, and T7/8, T8/9, T0/10 discs, and the distance of both up- and down-ends of titanium rod sliding in group C were measured. X ray was used to examined the morphology of the spine. Results Three months after operation, the average heights of T6, 7, 8, 9, and T7/8, T8/9, T9/10 discs in group C had no remarkble difference from those in group A （ P 〉 0. 05 ） , but significantly larger than in group B （ P 〈 0. 05 ）. Growth occurred in both up- and down-ends of the titanium rods for a total average of 44 mm. Conclusion The instrumentation growing rods of sliding pedicle screw system placement has no evident influence on the progression of the immature porcine spine. Key words: Internal fixation system ; Spine ; Growth; Pig