Utilization of the 3D-printed spine model for freehand pedicle screw placement in complex spinal deformity correction

We aim to demonstrate the safety and efficacy of utilizing 3D-printed spine models to facilitate freehand pedicle screw placement in complex spinal deformity correction. Currently there is no data on using 3D-printed models for freehand pedicle screw placement spinal deformity correction.

All patients undergoing spinal deformity correction over a 16-month period (September 2015 - December 2016) at the Spine Hospital of Columbia University Medical Center by the senior surgeon were reviewed. 3D-printed spine models were used to facilitate intraoperative freehand pedicle screw placement in patients with severe spinal deformities. Intraoperative O-arm imaging was obtained after pedicle screw placement in all patients. Screws were graded as intrapedicular, <2 mm breach, 2-4 mm breach, and >4 mm breach; anterior breaches >4 mm were also recorded. Screw accuracy was compared to a historical cohort (not using 3D-printed models) using SPSS 23.0 (Chicago, IL, USA).

A total of 513 freehand pedicle screws were placed from T1 to S1 in 23 patients. Overall, 494 screws (96.3%) were placed in acceptable positions according to the pre-operative plan, which had no statistically significant difference (P=0.99) compared to a historical cohort with less severe deformities. There were 84.2% screw that were intrapedicular or <2 mm breach; among the 81 screws (15.8%) with >2 mm breach, 67 were lateral breaches (most are intended juxtapedicular placement), whereas 14 were medial breaches. There were 11 screws (2.1%) that required repositioning due to pedicle violation, and eight screws (1.6%) had >4 mm anterior breach and required shortening. There was no neuromonitoring change or any other complications directly or indirectly related to freehand pedicle screw placement.

The 3D-printed spinal model can make freehand pedicle screw placement safer in severe spinal deformity cases with acceptable accuracy, and no neurological or vascular complications.