"Free-hand" technique for thoracolumbar pedicle screw instrumentation: Critical appraisal of current "State-of-Art"

Abstract

Pedicle screws are widely used for instrumentation of the thoracolumbar spine. The anatomic studies performed in the last two decades, detailing the complex morphometry and three-dimensional anatomy of the thoracolumbar pedicles, have enabled the emergence of the so-called "free-hand" technique of pedicle screw placement based exclusively on anatomical parameters. However, in the thoracic spine, the benefits of pedicle screws have been tempered by its potential risks, such as, spinal canal violation, pedicle fracture, nerve root compression, and vascular lesions. Furthermore, the narrow and inconsistent shape of the thoracic pedicles, especially in spinal deformity, makes their placement technically challenging. In this article, the authors make a critical appraisal of current "state-of-art" of "free-hand" technique of pedicle instrumentation, analyzing its anatomical basis, surgical technique, present indications and limitations as well as the role of adjuvant image-guided and neurophysiological monitoring methods.

Intraoperative electromyographic monitoring to optimize safe lumbar pedicle screw placement – a retrospective analysis

“…Pedicle screw technique has evolved over time and experience; however, “free-hand” technique is most widely practiced [1–5]. This technique involves visual identification of certain anatomical landmarks to find an appropriate entry point and then preparing the pedicle for screw placement [6, 7]. Whether the instruments used or the screw itself had breached the pedicle, is completely dependent on surgeon’s perception.…”

Stimulation of Pedicle Screws with Diathermy: Is it a Viable Option to Detect Breaches?

“…No single method of checking pedicle violation is absolutely accurate [12]. An almost universally practised method of probing the pedicle tract with a ball-tipped probe has been shown to have a relatively poor accuracy, with medial breaches as high as upto 32% being missed out on the same [13].…”

Free-hand pedicle screws insertion technique in the treatment of 120 consecutive scoliosis cases operated without use of intraoperative neurophysiological monitoring

“…In our practice we perform an accurate anatomic exposition of posterior bone structure of the spine, beginning with subperiosteal dissection, to remove muscles insertion with minimal hemorrhage; hemostasis is meticulous, as to reduce blood loss and maintain a clear operating field, determining correct insertion point for screws. The entry point is the intersection between a line that passes just laterally to the inferior articular process and a line, which bisects the transverse process [14]. The direction of the screws follows the axis of the pedicle.…”