Freehand thoracic pedicle screw technique using a uniform entry point and sagittal trajectory for all levels: preliminary clinical experience

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Experience with freehand 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. Furthermore, few studies provide specific guidance on sagittal and axial trajectories. The goal of this study was to propose a uniform entry point and sagittal trajectory for all thoracic levels during freehand pedicle screw placement and determine the accuracy of this technique.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The authors retrospectively reviewed postoperative CT scans of 33 consecutive patients who underwent open, freehand thoracic pedicle-screw fixation using a uniform entry point and sagittal trajectory for all levels. The same entry point for each level was defined as a point 3 mm caudal to the junction of the transverse process and the lateral margin of the superior articulating process, and the sagittal trajectory was always orthogonal to the dorsal curvature of the spine at that level. The medial angulation (axial trajectory) was approximately 30° at T-1 and T-2, and 20° from T-3 to T-12. Breach was defined as greater than 25% of the screw diameter residing outside of the pedicle or vertebral body.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>A total of 219 thoracic pedicle screws were placed with a 96% accuracy rate. There were no medial breaches and 9 minor lateral breaches (4.1%). None of the screws had to be repositioned postoperatively, and there were no neurovascular complications associated with the breaches.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>It is feasible to place freehand thoracic pedicle screws using a uniform entry point and sagittal trajectory for all levels. The entry point does not have to be adjusted for each level as reported in existing studies, although this technique was not tested in severe scoliotic spines. While other techniques are effective and widely used, this particular method provides more specific parameters and may be easier to learn, teach, and adopt.</jats:p></jats:sec>

Evaluation of a more ventral starting point for thoracic pedicle screws: higher maximal insertional arc and more medial and safer screw angulation

“…21,24 Most descriptions of the freehand technique follow a series of key steps, including creating a pilot hole in the dorsal cortex at a specified starting point, cannulating the pedicle with a gearshift, and probing the pedicle for potential breaches. 8,12,15,19 For the past decade, the senior author has utilized a modified freehand technique with a more ventral starting point. Prior to creating a pilot hole, the dorsal bone at the lamina-transverse process junction is removed with a large rongeur to the depth of the superior articular facet (SAF), creating a flat surface from the SAF to the starting point.…”

Free-Hand Pedicle Screw Insertion of Thoracic Spine Using Fennell Technique: Initial Results and Review of Literature

“…The various techniques described in the literature has been summarized in ►Table 1. In this study, the method described by Fennell et al 1 was used. They included 219 thoracic pedicle screws in the study and had 9 lateral breach (4.1%) and no medial breach.…”

“…All the cases were performed by a single surgeon (C.D.). Pedicle screws were placed using the technique described by Fennell et al 1 A uniform entry point of 3 mm caudal to the junction of the lateral margin of superior articular process and transverse process of the corresponding vertebra (►Fig. 1A).…”

“…Various free-hand screw insertion techniques have been described in the literature. [1][2][3][4][5][6] Many of the described trajectories, mention various entry points and medial angulation depending on the level of thoracic spine. Fennell et al 1 described a free-hand pedicle screw insertion technique in the thoracic spine using a uniform entry point and sagittal angulation for all levels in the thoracic spine.…”

The Concept of Lamina–Pedicle Perpendicularity: Part 1. Lumbar Spine

“…While many studies have focused on screw inclination in the mediolateral direction [12][13][14][15], few have assessed the sagittal plane [16][17][18][19]. For proper sagittal trajectories of pedicle screws, bony landmarks, such as the lamina surface, the spinous process, and the facet joint tilt, can be used as anatomic references [20].…”