Simulation and analysis of non-navigational errors in robot-assisted pedicle Kirschner wire placement surgery

Surgical errors of orthopedics robotic are influenced by a multitude of factors. This study aims to investigate the impact of non-navigational errors on the accuracy of pedicle screw placement in orthopedic surgery.

Initially, a robot-assisted Kirschner wire (K-wire) placement simulation system was constructed, comprising a universal arm, wide-angle cameras, microscope cameras, and a vertebral base. Utilizing this system, we conducted a systematic analysis of the effects of four factors on non-navigational errors: operator habits, guide-to-bone surface distance, robotic arm stiffness, and vertebral fixation stiffness.We investigated two distinct operator habits: Habit 1 involves first positioning the K-wire against the bone surface through the guide and then inserting it using a bone drill; Habit 2 involves clamping the K-wire onto the bone drill and then inserting it together. Based on the control variable method, we designed precision measurement experiments for K-wire placement under different factors, forming 26 variable combinations to investigate the K-wire placement errors under each factor and their proportions in the overall error.

A total of 933 K-wire placements were performed in this study. The average deviation under Habit 2 conditions was 0.51 mm, compared to 0.13 mm under Habit 1 conditions; the average deviation was 0.36 mm when the guide-to-bone surface distance was 5 cm, and 0.28 mm when the distance was 1 cm; the average deviation was 0.36 mm under the 600 mm robotic arm condition, and 0.24 mm under the 500 mm robotic arm condition; the average deviation was 0.37 mm in the Plaster-Fixed Vertebra Group, and 0.85 mm in the Silicone-Fixed Vertebra Group.

Operator habits and vertebral fixation stiffness are the primary factors influencing non-navigational errors, while guide-to-bone surface distance and robotic arm stiffness are secondary factors. This study recommends adopting Habit 1 in clinical surgeries, minimizing the guide-to-bone surface distance, and enhancing the stiffness of the robotic arm and vertebral fixation to reduce non-navigational errors and improve the accuracy of robot-assisted pedicle screw placement.