Does the length of the intermediate pedicle screw influence outcome in unstable thoracolumbar burst fractures? A prospective randomized study in India.

Abstract

A prospective randomized study. To investigate the impact of intermediate pedicle screw length on radiological and functional outcomes in unstable thoracolumbar burst fractures (TLF) treated with short-segment posterior fixation (SSPF). Although intermediate screws confer biomechanical advantages, there is no consensus on the ideal intermediate screw length. Sixty-six patients with unstable TLF (Load Sharing Classification score ≥7) and normal neurology requiring SSPF were randomized into two groups. Group 1 (long intermediate screw [LIS]) underwent SSPF with a long intermediate screw (occupying >50% of the vertebral body, length ≥40 mm), while group 2 (short intermediate screw [SIS]) received a short intermediate screw (occupying <50% of the vertebral body, length ≤35 mm). Radiological parameters (restoration of anterior body height [ABH], posterior body height [PBH], ABH/PBH ratio, local kyphosis angle [LKA], and regional kyphosis angle [RKA]) and functional parameters (Visual Analog Scale score and Oswestry Disability Index) were evaluated. Demographic variables (age, sex), mode of injury, and fracture pattern were comparable between groups. The LIS group showed a significant improvement in RKA correction in the immediate postoperative period (p =0.019), but this difference was not sustained at the final follow-up (p =0.713). Other radiological and functional parameters were comparable between the two groups at the 2-year follow-up. Although long intermediate pedicle screw provided better correction of regional kyphosis in the immediate postoperative period for unstable TLFs with LSC ≥7, the outcomes were comparable between both long and short intermediate pedicle screws at longterm follow-up.