[TiRobot-assisted percutaneous sacroiliac cannulated screw fixation for posterior pelvic ring injury with sacral variations].

Objective: To investigate the effectiveness of TiRobot-assisted percutaneous sacroiliac cannulated screw fixation in the treatment of posterior pelvic ring injuries with sacral variations, and to evaluate its feasibility and safety. Methods: The clinical data of 7 patients with Tile type C pelvic fractures and sacral variations treated with TiRobot-assisted percutaneous sacroiliac cannulated screw fixation between January 2020 and June 2021 were retrospectively analyzed. There were 5 males and 2 females with an average age of 36 years (range, 17-56 years). The causes of injury were traffic accident in 4 cases and falling from height in 3 cases. According to Tile classification of pelvic fractures, there were 1 case of type C1.1, 1 case of type C1.2, and 5 cases of type C1.3; according to Denis classification of sacral fractures, there were 3 cases of zone Ⅰ and 4 cases of zone Ⅱ; sacral deformities included 3 cases of lumbar sacralization, 2 cases of sacral lumbarization, and 2 cases of accessory auricular surface of the sacrum. The time from injury to operation ranged from 2 to 7 days, with an average of 4.6 days. The implantation time of each screw, the fluoroscopy times of each guide pin, the quality of fracture reduction (according to Matta score), the excellent and good rate of screw position, the healing time of fracture, and the incidence of complications were recorded, and the effectiveness was evaluated by Majeed score. Results: A total of 13 screws were implanted during the operation, the implantation time of each screw was 10-23 minutes, with an average of 18.2 minutes; the position of the guide pin was good, and no guide pin was adjusted, the fluoroscopy times of each guide pin were 3-7 times, with a median of 4 times. Postoperative imaging data at 3 days showed that the position of sacroiliac screw implantation was evaluated as excellent. No complication such as incision infection or vascular nerve injury occurred, and no adverse events related to robotic devices occurred. At 3 days after operation, according to Matta score, the quality of fracture reduction was excellent in 6 cases and good in 1 case, and the excellent and good rate was 100%. All the 7 patients were followed up 6-15 months, with an average of 12.4 months. Bone union was achieved in all patients, and the healing time ranged from 18 to 24 weeks, with an average of 21.2 weeks. Majeed score at last follow-up was 81-95, with an average of 91.5; 5 cases were excellent, 2 cases were good, and the excellent and good rate was 100%. Conclusion: TiRobot-assisted percutaneous sacroiliac cannulated screw fixation for posterior pelvic ring injury with sacral variation is accurate, safe, minimally invasive, and intelligent, and the effectiveness is satisfactory.