Comparison of Polyaxial or Poly/Monoaxial Mixed Screw Fixation for Treatment of Thoracolumbar Fractures with O-Arm Navigation: A Case-Control Study

Abstract

Background: Navigation and minimally invasive techniques have revolutionized spinal surgery. There are different types of pedicle screws for navigation-assisted percutaneous internal fixation for thoracolumbar burst fractures, resulting in 2 different types of internal fixation approaches: the PPP method (polyaxial screw fixation for all 3 vertebrae) and the MPM method (polyaxial screw fixation for the injured vertebra and monoaxial screw fixation for the adjacent vertebrae). This study aims to compare these 2 different methods for treatment of thoracolumbar fractures via O-arm navigation.

Methods: From January 2017 to January 2018, 45 patients were enrolled according to the criteria with a minimal follow-up of 1 year; there were 21 patients in the PPP group, and 24 patients in the MPM group. For follow-up, the demographic features and clinical outcomes were collected and evaluated.

Results: With regard to preoperative indices and demographic features, no significant difference was observed between these 2 groups (P > 0.05). For operation time, intraoperative bleeding, and length of hospitalization, no significant difference was observed either between the 2 groups (P > 0.05). The Cobb angle and anterior vertebrae body height (AVBH) of the injured vertebra were significantly restored in both groups 1 day after surgery (P < 0.05). However, the Cobb angle and AVBH in the MPM group was better corrected than that in the PPP group 1 day, 3 months, and 12 months after surgery, respectively (P < 0.05). In contrast, loss of Cobb angle and AVBH in the PPP group were significantly larger than the MPM group (P < 0.05). Meanwhile, no difference in the Visual Analog Scale and the Oswestry Disability Index were found between the 2 groups (P > 0.05).

Conclusions: Both MPM and PPP systems are good for treatment of single-segment thoracolumbar fracture. However, MPM showed better restoration effect and postoperative maintained Cobb angle than PPP.

Keywords: Monoaxial screws; O-arm navigation; Polyaxial screws; Thoracolumbar fractures.