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Study Design: Anatomic study using computed tomographic scans., Objective: The purpose of this paper was to determine the trajectory of pedicle screw insertions, in regard to posterior bony landmarks encountered during standard posterior exposure of the spine between the seventh cervical (C7) and the fifth thoracic (T5) vertebrae, when lateral fluoroscopic and radiographic guidance may be obstructed by the scapula and shoulders., Summary of Background Data: Only a few studies have evaluated the intraoperative sagittal trajectory of pedicle screw insertion., Materials and Methods: We assessed 64 participants of a health screening program using whole-spine computed tomographic scans. On the basis of 5 previously reported methods, we designed 3 freehand trajectories: lamina surface method (angle between the superior vertebral endplate and the surface of the lamina), spinous process method (angle between the superior vertebral endplate and a line connecting the tips of the index spinous process and the one cephalad to it), and facet tilt method (angle between the superior endplate and the superior facet tilt). We calculated each of the angles for the C7-T5 vertebrae and determined the most reliable method using coefficients of variation (CV) and intraobserver and interobserver reliability., Results: The lamina surface method had the smallest CVs for C7 and T1, and the mean angles were larger than 90 degrees (range, 94.7-102.4 degrees). The spinous process method had the smallest CVs between T2 and T5, and the mean angles were <90 degrees (range, 85.0-87.0 degrees). The intraobserver and interobserver reliabilities were good or excellent for both methods., Conclusions: The ideal sagittal trajectories for pedicle screw insertion are nearly orthogonal to the lamina surface or the line connecting the spinous processes, but were different for each of the vertebrae. The lamina surface method was the most reliable for C7 and T1, whereas the spinous process method was most reliable between T2 and T5., Level of Evidence: Level III.

Study Design: Pilot single-centre, stratified, prospective, randomized, double-blinded, parallel-group, controlled study., Objective: To determine whether vertebral end-plate perforation after lumbar discectomy causes annulus reparation and intervertebral disc volume restoration. To determine that after 6 months there would be no clinical differences between the control and study group., Summary of Background Data: Low back pain is the most common long-term complication after lumbar discectomy. It is mainly caused by intervertebral disc space loss, which promotes progressive degeneration. This is the first study to test the efficiency of a previously described method (vertebral end-plate perforation) that should advocate for annulus fibrosus reparation and disc space restoration., Methods: We selected 30 eligible patients according to inclusion and exclusion criteria and randomly assigned them to the control (no end-plate perforation) or study (end-plate perforation) group. Each patient was evaluated in 5 different periods, where data were collected [preoperative and 6-mo follow-up magnetic resonance imaging and functional outcome data: visual analogue scale (VAS) back, VAS legs, Oswestry disability index (ODI)]. Intervertebral space volume (ISV) and height (ISH) were measured form the magnetic resonance images. Statistical analysis was performed using paired t test and linear regression. P<0.05 was considered statistically significant., Results: We found no statistically significant difference between the control group and the study group concerning ISV (P=0.6808) and ISH (P=0.8981) 6 months after surgery. No statistically significant differences were found between ODI, VAS back, and VAS legs after 6 months between the 2 groups, however, there were statistically significant differences between these parameters in different time periods. Correlation between the volume of disc tissue removed and preoperative versus postoperative difference in ISV was statistically significant (P=0.0020)., Conclusions: The present study showed positive correlation between the volume of removed disc tissue and decrease in postoperative ISV and ISH. There were no statistically significant differences in ISV and ISH between the group with end-plate perforation and the control group 6 months after lumbar discectomy. Clinical outcome and disability were significantly improved in both groups 3 and 6 months after surgery.