Introduction: Experience with free-hand thoracic pedicle screw placement is well described in the literature. Published techniques rely on various starting points and trajectories for each level or segment of the thoracic spine. Few provide specific guidance on sagittal and axial trajectories. The goal of this study; propose a uniform entry point and sagittal trajectory for all thoracic levels during free-hand pedicle screw placement and determine the accuracy of this technique.

Methods: Retrospective review post-operative (CT) images of 33 consecutive patients who underwent open, free-hand thoracic pedicle screw fixation using our uniform entry point and trajectory technique for all levels. The entry point is 3 mm caudal to the lateral margin of the superior articulating facet-transverse process (LSAF-TP) junction. The sagittal trajectory is orthogonal to the dorsal curvature of the spine at that level (Fig1.). Medial angulation (axial trajectory) is approximately 30 degrees at T1,T2, and 20 from T3-T12. Breach was defined as >25% of the screw diameter outside of the pedicle or vertebral body.

Results: 219 consecutive screws evaluated, no screws excluded. Screws placed for varied pathology: 61%-trauma, 12%-infection, 18%-tumor, 9%-deformity (Fig2). The distribution; (10.5%)-T1, (12.3%) -T2, (5%)-T3, (5.9%)-T4, (4.6%)-T5, (3.7%)-T6, (6.8%)-T7, (10.5%)-T8, (10.5%)-T9, (11.4%)-T10, (8.7%)-T11, (10%)-T12 (Fig3). There were 9 total lateral breaches (4.1%) and no medial breaches. (Fig4). No supra- or infra-pedicular breaches. No neurovascular or hardware complications. Medial angulation, measured post-operatively was determined, on the average, 30 degrees at T1+T2, and 20 from T3-T12 (Fig5a/b).

Conclusions: It is feasible to place free-hand thoracic pedicle screws using a uniform entry point and sagittal trajectory for all levels. Entry point does not have to be adjusted. Other techniques are effective and widely employed, this particular method provides more specific parameters and may be easier to learn, teach and adopt.

Patient Care: Improve the simplicity of placement for thoracic pedicle screws

Learning Objectives: 1. Understand a modified thoracic screw insertion point

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