Under neural navigation with the use of intraoperative three dimensional imaging quality O-arm , pedicle screws inserted at the thoraolumbar/lumbar spine after insertion of the reference frame at the spinous process above or below the level of instrumentation followed by O-Arm imaging and uploading the images to the stelth navigation system and pedicle tract identification using instrumented tools guided by the Navigation polyaxial screws is inserted.

pedicle screws inserted using marker screws after posterior exposure of thoracolumbar /lumbar spine by either open midline posterior exposure or minimal invasive posterior wiltse style exposure with expandable tubular retractor, anatomical landmark for insertion of pedical screws identified and followed by inserting of a cervical distraction screw size 3 / 12 mm as a stable marker using high speed drill. C-arm floro is used to take antroposterior and lateral view to confirm the position of the marker screws at this stage.free hand technique supported by the images provided to cannulate the pedicle with the use of information on the images taken for all the marker screws simultaneously.

The screws are inserted in two or more consecutive levels to prevent motion at the segments that are being fused. It will be done using one of the two guidance technique depending on which arm the patient will be randomized to.

Investigators will determine the rate of screws breach in the two comparison groups

screw insertion time in each technique which will be assessed by calculating the total time from puncture at the entry point by awl to complete all screw insertions into pedicles divided by the number of pedicle screws

investigators will determine which group needs more screws revision

Investigators will determine degree of screws breach in the two comparison groups

investigators will ascertain direction of the breach, if it is lateral ,medial , inferior , or superior.

the two groups will be compared in rate of neurological or vascular complications.