Tricortical screw spinal fixation: a scoping review and introduction of technique, biomechanical advantages, and clinical outcomes in high-risk vertebral fractures

Abstract

Background/objective: Tricortical pedicle screw (TCPS) fixation has emerged as a biomechanically superior alternative to conventional unicortical/bicortical methods for spinal stabilization in high-risk populations, particularly elderly patients with osteoporotic or diffuse idiopathic skeletal hyperostosis (DISH)-related vertebral fractures. This review evaluates TCPS fixation's biomechanical advantages, clinical outcomes, and surgical considerations to address these challenges.

Methods: A scoping review was conducted using the PRISMA scoping review checklist. PubMed was searched through March 1, 2025. Inclusion criteria were studies reporting treatment parameters and follow-up results of TCPS spinal fixation. Data was analyzed to synthesize clinical outcomes, with a focus on hardware failure rates.

Results: 5 studies satisfied the final inclusion criteria, consisting of 3 case series and 2 cohorts. These 5 studies included 85 patient cases. The included patients had a weighted mean age of 78.97 years, with a sex distribution consisting of 54.8% (n = 40) males and 45.2% (n = 33) females. 62.4% (n = 53) patients were positive for DISH. Affected vertebrae were mostly located in the thoracolumbar region (64.1%), followed by the thoracic (21.8%) and lumbar regions (14.1%). 76.5% (n = 65) of patients were treated with TCPS fixation, and 23.5% (n = 20) were treated conventionally. A total of 636 screws were inserted, consisting of 46.2% (n = 294) tricortical and 53.8% (n = 342) conventional pedicle screws. Of the tricortical screws, 1.36% (n = 4) loosened, while 20.5% (n = 70) of conventional screws loosened. 3 patients treated with TCPS fixation experienced implant failure, while 6 patients treated with conventional pedicle screw fixation experienced implant failure.

Conclusion: TCPS fixation enhances spinal stabilization in high-risk fractures through tri-cortical load distribution, minimizing screw loosening and invasiveness. While requiring precise trajectory planning to avoid perforation risks, it offers shorter operative times, reduced blood loss, and improved biomechanical stability, particularly in osteoporotic/DISH patients. Further prospective studies are needed to optimize patient selection and refine navigation-assisted techniques for broader applicability.

Keywords: Pedicle screw; Penetrating endplate screw; Spinal fixation; Tricortical screw fixation.

Fig. 1

illustrates the flow diagram of the literature search. The search strategy yielded 150 studies, of which 4 were included upon the pre-specified study inclusion criteria. 1 additional study was included after further search of the literature (Table 1). 3 case series and 2 cohorts were included. Critical appraisal returned low risk of bias for all included studies

Fig. 2

The methods of three pedicle screw insertion techniques. From top to bottom, they are Roy-Camille, Magerl, and Krag, respectively. From Smith, J. (2022. Retrieved from Song M, Sun K, Li Z, et al. “Stress distribution of different lumbar posterior pedicle screw insertion techniques: a combination study of finite element analysis and biomechanical test.” Sci Rep. Jun 21 2021;11(1):12968. 10.1038/s41598-021-90686-6

Fig. 3

Lateral view of the spine depicting the three insertion methods of pedicle screw fixations; unicortical (USPS), bicortical (BCPS) and tricortical (TCPS). BCPS penetrates the pedicle and endplate of the fractured vertebrae. TCPS penetrates the endplate of the fractured vertebrae in addition to the endplate of the adjacent vertebrae

Fig. 4

FEA values of mean range of motion, maximum motion displacement and maximum stress experienced by screws with UCPS, BCPS and TCPS insertion. Tested motion states include flexion, extension, left lateral bending, right lateral bending, left rotation, and right rotation. Data from Zhang et al. 2020