Digital anatomic study of computer simulated sacral pedicle screw placement for treatment of sacral fracture

Abstract

Objective To investigate the digitized anatomical structure and application of computer simulated sacral pedicle screw placement for treatment of sacral fracture. Methods Three-dimensional reconstruction from CT data of the 61 adult human pelvises was conducted using the Mimics software. Safe zones for S1-4 pedicle screw placement were defined, imbedding of sacral screw was simulated, and screw entry point, length, diameter and direction were measured. Results Screws entry site of S1 was located on the lateral border of S1 superior articular process basilar part. Screw entry sites of S2-4 was located on the upward of the midpoint of ligature between sacral plate upper and lower foramina sacralia posteriora lateral border, and the screw entry site moved outside gradually from the top to the bottom along with larger camber and smaller diameter and length of the pedicle screws. Significant differences between the female and male patients were noted in the distance between screw entry site of S2 and S3 sacral hole superior border tangent (L2), the vertical dimension between screw entry site of S2 and center of the sacral crest (L3), the largest diameter of S3 screw (P 0.05). Conclusion Anatomical measurements of sacral pedicle including the screw entry point, length, diameter, and direction by the Mimics software might be a reference for clinical treatment of sacral fracture. Key words: Sacrum; Bone nails; Computer simulation; Anatomy