A New Trajectory of the Percutaneous S1 Pedicle Screw: A Prospective Analysis With 2–4 Years of Follow-up

Purpose: S1 pedicle screw loosening remains a significant challenge in lumbosacral fixation due to the unique anatomical and biomechanical properties of the sacrum. Traditional trajectories often face limitations, including poor screw hold and an elevated risk of complications. This study introduces the Vishal Peshattiwar (VP) trajectory for S1 pedicle screw placement, aiming to optimize screw positioning, improve construct stability, and reduce associated complications.Methods: A prospective analysis was conducted on 117 patients undergoing L5–S1 minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and multilevel MIS-TLIF including the L5–S1 level between June 2019 and August 2022. In total, 234 S1 pedicle screws were placed using the VP trajectory under O-arm-guided 3-dimensional computed tomography navigation. Screw parameters, including length, entry point, and angulation, were analyzed. Finite element analysis (FEA) was performed using Altair OptiStruct software to assess displacement forces and elemental stresses.Results: The average screw length was 45.90 mm in men and 44.88 mm in women. The caudocranial angle ranged from 50° to 65°, and the lateromedial angle from 18° to 25°. FEA demonstrated reduced displacement forces and elemental stresses, indicating improved construct stability. At a 2- to 4-year follow-up, complications were minimal, with 1 case of bilateral screw breakage and 1 dural tear.Conclusion: The VP trajectory provides an improved approach for S1 screw placement, offering enhanced biomechanical stability, reduced complications, and better long-term outcomes. Its application is most effective with minimally invasive surgical techniques and navigation assistance.