Charactor of Modality and Resident Level in Pedicle Screw Accuracy and Neurosurgical Education

Abstract

Objective: Evolving pressure on surgical education necessitates safe and efficient learning of techniques. We evaluated the effect of training year using anatomic, percutaneous fluoroscopy guided and computer navigated techniques on the accuracy of pedicle screw placement to attempt to determine if different modalities may be better suited for different levels of training. Methods: All instrumented thoracic and lumbar cases performed at Detroit Medical Center by the Neurosurgery Service between August 2012 and June 2013 were included.Cases had hardware verified by post-operative CT. Hardware placement was graded according to Mirza SK et al., grade 0 (within pedicle), grade 1 (< 2 mm breach), grade 2 (> 2 mm breach) , and grade 3 (extrapedicular). Pedicle screws were reviewed independently by a resident and attending surgeon. Rates of pedicle breach, EBL, length of case, pedicle size and pedicle starting point were all reviewed. Pedicles were analyzed on PACS system in axial views, using sagittal views to identify the correct level. Results: A total of 306 pedicle screws were evaluated in 36 patients. The overall rate of accurate pedicle screw placement among residents defined as Grade 0 or 1 placement was 86.8%.Fluoroscopically placed screws had significantly less breaches than anatomic screws 11% vs 20% (p = 0.03). Fluoroscopic cases had significantly less medial breeches (20%) than anatomic (50%) (p < 0.05) and computer assisted cases (73%) (p < 0.05). EBL values for fluoroscopic, anatomic and Body Tom cases were 425 cc, 720 cc, and 816 cc respectively. Resident level was found to be inversely proportional to breech rate (R squared 0.45). We did not see any clear difference in breach rate for resident level in different modalities. Conclusion: Supervised neurosurgical residents can place pedicle screws within published rates of acceptable breach. Interestingly our study revealed an inverse relationship between resident experience and pedicle screw accuracy. Fluoroscopic placement of pedicle screws compared to computer assisted and anatomic techniques results in lower medial breach rate and may be better suited for junior level residents.