A simple intraoperative method for assessment of pedicle screw trajectory using contrast medium injection.

Abstract

STUDY DESIGN: Retrospective radiologic study. OBJECTIVE: To introduce a novel

method for intraoperative verification of the pedicle screw pathway using

contrast medium injection. SUMMARY OF BACKGROUND DATA: Various surgical

techniques and equipments, such as, mechanical probing, intraoperative

fluoroscopy, computer-assisted navigation system, and neurophysiological

monitoring have been devised to assist accurate pedicle screw placement. However,

pedicle screw misplacement remains of considerable concern, even to experienced

spine surgeons. MATERIALS AND METHODS: Fifty pedicle screws placed using the

devised contrast medium technique in 39 consecutive patients were included. The

authors used a contrast medium injection to verify pedicle screw tracts when

pedicle wall violation was doubtful with conventional methods. Contrast medium

(Iopamidol) was injected through the prepared screw path under fluoroscopic view.

The screw path preparation was deemed successful when contrast medium was

contained within the prepared screw tract. Pedicle screw placements were

interpreted by postoperative computed tomography. RESULTS: Intraoperative

verifications of pedicle screw paths using contrast medium technique showed that

6 of the 50 (12%) screw paths were disrupted, and these paths were redirected.

Posteoperative computed tomography evaluations showed that 39 of the 50 (78%)

screws were correctly placed. Of the 11 misplaced screws, 9 (18%) were

interpreted as exhibiting cortical encroachment, and 2 (4%) as exhibiting mild

frank penetration. CONCLUSIONS: The intraoperative injection of contrast medium

provides a simple, fast, safe, and reliable means of verifying pedicle screw

tract, when pedicle wall violation is doubtful.