Multiaxial inter-vertebral and vertebral pedicle pedicle screw fixation for spinal fractures: a biomechanical comparative study

Abstract

Objective To compare the biomechanical stability of the multiaxial inter-vertebral and vertebral pedicle screw fixation in vertebral fracture fixation of the spinal fracture model. Methods Six lumbar fracture models were made on fresh calf lumbar spine specimens at L1 -L5 to compare the stability of four transpedicular multiaxial screws and six transpedicular multiaxial screws by examining the range of motion (ROM) in flexion, extension, lateral bending and torsion. Results Biomechanical experiment found that four multiaxial screws transpedicular fixation specimen exhibited a significantly larger ROM in flexion and extension than the intact specimens; while six multiaxial transpedicular screw fixation specimen exhibited a smaller ROM than the intact specimens (t =4. 844,P ＜0. 01 ;t =3. 722,P ＜0.05 ). The ROM of six multiaxial transpedicular screw fixation specimen was significantly smaller than that of four multiaxial transpedicular screw fixation specimen in flexion, extension, lateral bending and rotation ( P ＜ 0. 01 ). Conclusions Compared with four multiaxial transpedicular screw fixation, six multiaxial transpedicular screw fixation exhibits a significantly larger stability in flexion, extension, lateral bending and rotation, as provides theoretical basis for treatment of thoracolumbar fractures with pedicular screw fixation. Key words: Spinal fractures; Biomechanics; Pedicle screws