gms | German Medical Science

Objective: Studies validating robotic technology in the spine have so far mainly focused on degenerative disease of the lumbar spine. Traumatic instability may be associated with a motion of vertebral elements relative to each other which in turn may lead to a decreased accuracy of a spinous process clamp attached to the dorsal elements. The aim of the present study is therefore to compare the accuracy and utility of a robotic-assistance system to conventional fluoroscopy-guided pedicle screw placement for traumatic spinal fractures.

Method: Forty (n=40) patients suffering from traumatic spinal fracture and requiring instrumentation were included in the study, with n=20 patients undergoing instrumentation with robotic assistance and n=20 patients using conventional technique. Robot-guidance (Mazor SpineAssist/Renaissance) was based on preoperative planning and intraoperative fluoroscopic matching. In the “conventional” group, pedicle screws were placed based on anatomical landmarks and anterior-posterior and lateral fluoroscopy. The primary outcome measure was accuracy of screw placement as assessed using the Gertzbein-Robbins scale. Screw grades A and B (less than 2mm pedicle breach) on postoperative coronal, sagittal and axial CT imaging were regarded as clinically acceptable, while all other grades were counted as misplacements.

Results: A total of 234 screws were placed on 117 levels. The upper thoracic spine (Th1-Th6) accounted for 18 operated levels (15%), the lower thoracic spine for 51 (43%) while the remaining 48 (42%) were lumbosacral. In the robot group (n=20, 108 screws), trajectories were graded A or B in 86 (79.6%) of screws. The misplacement rate was 20.4% (22/108 screws). In the conventional group (n=20, 126 screws), acceptable trajectories made up 73.8% of screws (93/126) with a misplacement rate of 26.2% (33/126). There was no difference in screw accuracy between groups (Chi2, 2-tailed Fisher´s exact, p=0.35). One screw misplacement in the open group required a revision surgery (5%), but none were required in the robot group.

Conclusions: Pedicle screw placement for traumatic spinal fractures of the thoracolumbar spine can be performed effectively and safely using robot-guided assistance, but accuracy rates and direction of deviation are similar to conventional technique.