BACKGROUND Understanding of the pedicle anatomy is necessary for pedicle screw placement; however, there have been few Thai studies reporting on thoracic pedicle morphometry. OBJECTIVE To determine important anatomical measurements for thoracic pedicle screw fixation. MATERIAL AND METHOD T1-T12 vertebral pedicles were evaluated in 27 cadavers. The diameter angle, length and entry point of t...

STUDY DESIGN Evaluation using 3-dimensional screw trajectory software and computed tomographic scans. OBJECTIVE To investigate the anatomic feasibility of laminar screw placement in the upper thoracic spine compared with pedicle screw placement. SUMMARY OF BACKGROUND DATA Although laminar screws have been suggested as an alternative to pedicle screws in the upper thoracic spine, previous an...

BACKGROUND Lateral pedicle wall perforations occur frequently during pedicle screw insertion. Although it is known that such an occurrence decreases the screw pull-out strength, the effect has not been quantified biomechanically. MATERIALS AND METHODS Twenty fresh cadaveric lumbar vertebrae were harvested, and the bone mineral density (BMD) of each was evaluated with dual-energy radiography a...

The pig spine is widely used as a large animal model for preclinical research in human medicine to test new spinal implants and surgical procedures. Among them, pedicle screw is one of the most common method of fixation of those implants. However, the pedicle of the porcine vertebra is not as well defined and not as large as the pedicle of the human vertebra. Therefore, the position of the scre...

There are three basic concepts that are important to the biomechanics of pedicle screw-based instrumentation. First, the outer diameter of the screw determines pullout strength, while the inner diameter determines fatigue strength. Secondly, when inserting a pedicle screw, the dorsal cortex of the spine should not be violated and the screws on each side should converge and be of good length. Th...

BACKGROUND The foremost concern of a surgeon during pedicle screw fixation is safety. Assistive modalities, especially intraoperative electromyographic monitoring (EMG) can function as an essential tool to recognize screw malposition that compromise neural integrity, so that the screws can be repositioned immediately rather than later. We intend to study the efficacy of intraoperative EMG monit...

BACKGROUND Pedicle screws are biomechanically superior over other spinal fixation devices. When improperly positioned, they lose this advantage and put adjacent structures at risk. Accurate placement is therefore critical. Postoperative computed tomography (CT) scans are the imaging gold standard and have shown malposition rates ranging from 2% to 41%. The O-arm (Medtronic Navigation, Louisvill...

AIM To assess the feasibility and efficacy of TLIF with unilateral pedicle screw and contralateral percutaneous lumbar transfacet screw fixation for the treatment of lumbar degenerative disorders. MATERIAL AND METHODS A series of computed tomography (CT) digital images from 60 patients (30 males and 30 females) with L3-S1 segments, were reconstructed in three dimensions using a software named...

BACKGROUND Pedicle screw instrumentation is widely used for spinal stabilization. However, the accuracy for free-hand screw placement ranges from 69% to 94%. This study assesses the value of the existing classification systems, and investigates their impact on the ability to assess the accuracy of free-hand screw placement. METHODS Data were collected retrospectively from the medical records ...

Intra-and early post-operative aortic injury by pedicle screw is not a rare complication in orthopedic surgery, but aortic penetration by a screw head over a long time period is considered as an uncommon case. There are various surgical management options for thoracic aortic injury caused by malpositioned spinal instruments. We report a case of a patient who underwent minimally invasive graft r...