The accuracy and learning curve analysis of the robot assisted percutaneous thoracolumbar screw placement

English Keywords:Orthopedic robot  Thoracolumbar fracture  Pedicle screw insertion  Learning curve

English Abstract:

  【Abstract】 Objectives: To explore the accuracy and learning curve of percutaneous screw placement assisted by "Tianji" orthopedic robot during internal fixation of thoracolumbar fracture. Methods: A retrospective anal?鄄ysis was performed in 24 patients with single-segment thoracolumbar fracture who were consecutively enrolled in the hospital from March 2019 to January 2020. They were treated by the same surgeon using "Tianji" or?鄄thopedic surgical robot. There were 14 males and 10 females with the age of 22-54 years(averaged 39.29±9.73 years). Of all patients, 9 cases were of T12 fracture, 10 cases of L1, 4 cases of L2, and 1 case of L3. Based on the operation date, patients were divided into group A, group B, group C, and group D. CT scan was performed 3-5 days after operation. The accuracy of screw placement was estimated using the proportion of Category A screws according to Gertzbein-Robbins classification. Path-planning duration (Duration from placing spinous process Clamp towards completing before movement of positioner), screw implantation time(from the beginning of robot arm moving to screw implanted into a satisfied position under fluoroscopy), and total operation time (from incision to wound disinfection and bandaging) were statistically analyzed. The learning curve of robot assisted percutaneous thoracolumbar fracture internal fixation technology was evaluated by curvi?鄄linear regression analysis. Results: There were no statistically significant differences in fracture types, total number of surgical segments, screws numbers, age, and gender among the 4 groups(P>0.05). The total accura?鄄cy of screw placement in this study was 98.03%(100/102), including 100 screws of Category A, 2 screws of Category B, and no screw of Category C and D. The difference of screw setting accuracy among the four groups is not statistically significant(P>0.05, grade A 96.0%, grade B 96.1%, grade C 100%, and grade D 100%). In two cases, number 1 and number 2, there was deviation between the guide pin trajectory and the planned trajectory. After two planning adjustments, the screws were successfully implanted. Of path-planning duration(group A 44.83±13.60min, group C 29.17±2.14min, and group D 29.33±1.37min), there were signifi?鄄cant differences between group A and group C/ group D(P<0.01), and there was no statistical difference be?鄄tween group C and group D(P>0.05). Of the total operation time(group A 137.83±18.00min, group C 120.50±4.59min, and group D 119.67±5.24min) and the screw-implantation time(group A 46.17±6.68min, group C 40.00±2.90min, and group D 38.67±3.01min), group A has significant differences from group C/ group D(P<0.05), and group C has no statistical difference from group D(P>0.05). The path-planning duration, total surgery duration and screw-implantation durationof group B(31.67±1.86, 120.33±5.85, and 40.67±2.25 respec?鄄tively) were not statistically different from those in groups A, C, and D(P>0.05). After the curvilinear regres?鄄sion analysis, it showed that the path-planning time(P<0.001), the screw-implantation time(P<0.001), and the total surgery time(P<0.001) significantly decreased with the increasing numbers of patients. And after the num?鄄ber reaching 12 in the medium stage, the three parameters stayed relatively stable. Conclusions: "Tianji" Orthopedic Robot has higher accuracy and stability in percutaneous thoracolumbar internal screw fixation. And this technology has certain learning curve in its early application. The learning curve quickly becomes stable with the increase in cases.