Impact of Pedicle Fill on Axial Pullout Power in Spinal Fixation After Rod Discount.
Orthopedics. 2017 Nov 01;40(6):e990-e995
Authors: Albanese Ok, Ordway NR, Albanese SA, Lavelle WF
Rod discount to pedicle screws is used for a wide range of spinal fixation procedures; nonetheless, it may possibly alter the integrity of the screw-bone interface. The authors investigated the impact of pedicle fill (ratio of pedicle screw diameter to pedicle diameter) on the energy of the screw-bone interface after simulated rod discount on 17 vertebrae (three thoracolumbar backbone specimens). Pedicle diameter was measured with customary medical computed tomography scan protocols. The authors decided the minimal pedicle diameter for every stage. Polyaxial pedicle screws have been surgically positioned bilaterally with a freehand method with customary medical anatomic landmarks. The pedicle pairs have been instrumented with pedicle screws of predetermined diameter, 1 with better than 80% fill and 1 with lower than 80% fill. A simulated discount maneuver was carried out with a 5-mm hole adopted by an axial pullout take a look at to evaluate screw interface energy. Comparability of insertion torque between lower than 80% fill and better than 80% fill didn’t present important will increase. A big distinction in pullout load (P=.043) occurred with better than 80% fill (791±637 N) in contrast with lower than 80% fill (636±492 N). No important distinction in stiffness was famous (P=.154) with pedicle fill of better than 80% (427±134 N/mm) in contrast with lower than 80% (376±178 N/mm). The present findings assist the usage of better than 80% pedicle fill for optimum screw anchoring in pedicle screw-based constructs involving rod discount. Surgeons ought to take into account putting screws that may safely fill vertebral pedicles, particularly on the apex of the curve and the proximal and distal ranges of constructs, the place extreme forces are imparted to the screws. [Orthopedics. 2017; 40(6):e990-e995.].
PMID: 28968476 [PubMed – indexed for MEDLINE]