Lateral mass intrapedicular screw fixation: A radiological evaluation of screw pullout strength.

Background: Lateral mass intrapedicular screw (LMIS) fixation was introduced in 2021 as a safe and simple alternative method for the fixation of the subaxial cervical spine in the treatment of various cervical spine diseases. The purpose of this study was to evaluate and compare the screw pullout strength of this new technique to the trajectories of two other major methods, the transpedicular screw (TPS) and lateral mass screw (LMS) methods.

Methods: Two hundred and three patients who underwent a cervical computed tomography (CT) scan at our institution were included in the study. A region of interest for each of the three trajectories was selected using axial slices of the cervical vertebra from C3 through C6, and the CT number (Hounsfield unit) was calculated.

Results: A total of 4872 data points were collected. The average age of the patients was 59.5 years. The male-to-female ratio was 135:68. The number of patients over the age of 65 was 93. The average CT numbers were 511.9 for TPS, 473.1 for LMS, and 598.5 for LMIS. There was a significant difference in the CT number among the three trajectories, even when adjusted for sex and age.

Conclusion: LMIS is a promising alternative to the common methods used for subaxial cervical spine fixation that has a significant pullout strength. This approach is worth considering in many patients.