Accuracy of screw placement and learning curve analysis of robot-assisted minimally invasive transforaminal lumbar interbody fusion

English Keywords:Robot  Transforaminal lumbar interbody fusion  Degenerative lumbar disease  Learning curve

English Abstract:

  【Abstract】 Objectives: To investigate the pedicle screw placement accuracy of robot-assisted minimally invasive transforaminal lumbar interbody fusion(RA-MIS-TLIF) and analyze its learning curve. Methods: A retrospective analysis was conducted on the clinical data of 160 patients with degenerative lumbar diseases treated at the Department of Orthopedics, Sichuan Academy of Medical Sciences & Sichuan Provincial People′s Hospital between January 2019 and June 2022. The patients were divided into a robot group(n=80) and a manual group(n=80) based on the surgical approach. Each group was further divided into four subgroups(1, 2, 3, 4) of 20 patients each, arranged sequentially according to the order of surgery dates. The total operative time, blood loss, and planning and screw placement time of the two surgical methods were statistically analyzed. Preoperative, postoperative 1d, and six-month postoperative visual analogue scale(VAS) scores for pain and Oswestry disability index(ODI) were compared across the four subgroups. The trends in total operative time and blood loss with increasing surgery cases were analyzed using a logarithmic regression model. Screw placement classification was evaluated using the Gertzbein-Robbins classification based on postoperative CT scans, and then the screw placement accuracy was calculated. Results: All the surgeries were successfully completed. In the robot group, the total operative time was 162.9±5.7min, blood loss was 91.4±9.5mL, and planning and screw placement time was 42.1±1.3min; In the manual group, the total operative time was 169.1±6.6min, blood loss was 101.0±9.2mL, and planning and screw placement time was 57.0±6.3min. A total of 320 screws were placed in each group, with accuracy rates of 97%(311/320) in the robot group and 92%(295/320) in the manual group. Neither group had grade C or D screws. The total operative time decreased with the increase in the number of surgeries in both groups. The robot group achieved relative stability between subgroups 2 and 3[y=-5.894×ln(x)+183.891, R2=0.576, P<0.05], while the manual group achieved relative stability between subgroups 3 and 4[y=-4.424×ln(x)+184.221, R2=0.376, P<0.05]. The blood loss also decreased with the increase in the number of surgeries in both groups, the robot group achieved relative stability between subgroups 2 and 3[y=-9.480×ln(x)+125.361, R2=0.547, P＜0.05], and the manual group achieved relative stability also between subgroups 2 and 3[y=-3.868×ln(x)+114.183, R2=0.148, P＜0.05]. Postoperative VAS scores in the robot group decreased from 6.9±1.1 preoperatively to 2.4±0.9 on postoperative 1d(P<0.05) and to 1.1±0.4 at six months(P<0.05). In the manual group, VAS scores decreased from 7.0±0.9 preoperatively to 2.4±0.9 on postoperative 1d(P<0.05) and to 1.4±0.6 at six months(P<0.05). ODI in the robot group decreased from (59.5±7.1)% preoperatively to (20.0±4.1)% on postoperative 1d(P<0.05) and to (10.8±3.0)% at six months (P<0.05). In the manual group, ODI scores decreased from (57.7±6.9)% preoperatively to (19.6±4.6)% on postoperative 1d(P<0.05) and to (11.3±3.4)% at six months(P<0.05). All the 160 patients completed follow-ups with no severe complications reported during the follow-up period. Conclusions: Comparing with traditional MIS-TLIF with manual pedicle screw placement, RA-MIS-TLIF has a higher accuracy of screw placement and a smoother learning curve, which stabilizes after approximately 20 cases.