gms | German Medical Science

Objective: Pedicular screw placement is a standard procedure for spinal fusion in the lumbar and thoracic spine. Poor screw placement puts neural structures at risk and might reduce the primary stability of the spondylodesis. An image-guided spinous process mounted minirobot was recently introduced to improve the rate of proper srew placement and first series showed its high accuracy. However, no study has yet compared if robot-assisted screw placement indeed is superior to conventional screw placement.

Methods: 112 consecutive cases who underwent lumbar or lower thoracic spinal fusion with 578 pedicle screws were included in a retrospective analysis. 57 patients received pedicle screws under fluoroscopic guidance only, whereas 55 patiens underwent robot-assisted screw placement (35 via a percutaneous approach, 20 via a midline incision). The screw position was reviewed on postoperative CT-scans. Further evaluated parameters were duration of intraoperative x-ray, hospitalization, administration of opioid analgetics and rate of complications.

Results: Robot-assisted pedicle screw implantation resulted in correct placement (no breaching of the pedicular corticalis) in 94.5% of the screws compared to 91.4% for conventionally placed screws. Intraoperative x-ray exposure was found to be 34 s per screw during robot-assisted compared to 77s during conventional procedures. Both findings were statistically significant. Duration of postoperative hospitalization (10.5 compared to 14.6 d), administration of opioid analgetics (45.5 compared to 88.9%) and rate of minor and mayor complications (20.9 compared to 41.2%) were lower in robot-assisted procedures. Subgroup analysis revealed that this could rather be attributed to the surgical approach (percutaneous versus midline incision), than to application of robot assistance. The significance of these findings however was compromised by the heterogenity of the groups.

Conclusions: In terms of accuracy and intraoperative x-ray exposure robot-assisted procedures were superior to conventional screw placement. Duration of hospitalization, administration of opioid analgetics and complication rate seem to be better in patients who underwent percutaneous procedures.