Imaging and clinical study on the relationship between abnormal development of the proximal sacrum and precise insertion of sacroiliac screws / 中华骨科杂志

ABSTRACT

Objective:To investigate the clinical efficacy of robot-assisted sacroiliac screw implantation in the treatment of proximal dysplasia sacral fractures.Methods:A retrospective analysis was conducted on 191 patients admitted to the Pelvic Department of Tianjin Hospital from May 2016 to January 2021 who underwent robot assisted sacroiliac screw implantation with sacral fractures, including 105 males and 86 females, aged 38.5±6.5 years (ranging from 19 to 69 years old). Among them, there were 85 patients with dysplasia of proximal sacrum. According to the classification of proximal sacral dysplasia, the patients were divided into five groups the steep sacral alar slope group ( n=60), the mastoid protrusion group ( n=30), the lumbar sacralization group ( n=25), the sacral foramen oval degeneration group ( n=23) and the S 1 anterior cortical depression group ( n=10). The remaining 106 patients were normal group. Iliac cortical density (ICD) line typing was recorded in the 85 patients. The the completion of sacroiliac screw implantation, the Gras score of screw position after operation, the postoperative complications, the minimum diameter of S 1 screw channel (R1), the angle ∠A between the S 1 sacroiliac screw in the coronal plane and the cephalic side, and the angle ∠B between the S 1 sacroiliac screw in the water plane and the ventral side were recorded and compared with those of normal development patients. Results:The incidence of steep sacral alar slope was the highest (31.4%, 60/191). There were 2 or more developmental abnormalities in 24 cases. In 85 cases with dysplasia of proximal sacrum, ICD line type I was found in 8 cases, type II in 12 cases and type III in 65 cases. 49 patients (58.8%, 49/85) were able to complete the implantation of S 1 sacroiliac screw, while 36 patients (35.3%, 36/85) were only able to complete the implantation of S 2 sacroiliac screw. The Gras score of postoperative screw position was 90.05% for grade I, 9.94% for grade II, and 0 for grade III. In 1 case the sacroiliac screw pierced through the anterior cortex of the sacrum, and in 1 case the screw partially threaded into the sacral foramen, and there were no symptoms of iatrogenic nerve injury. The R1 values of the preoperative steep sacral alar slope group, the mastoid protrusion group, the sacral foramen oval degeneration group, the lumbar sacralization group, the sacral foramen oval degeneration group and normal development patient group were 11.4±3.0, 11.6±3.2, 9.8±3.0, 8.8±4.2, 6.5±4.4, and 11.4±3.4 mm, respectively. The differences between the lumbar sacralization group, the sacral foramen oval degeneration group, and the S1 anterior cortical depression group with the normal development patients were statistically significant, respectively ( t=-3.05, P=0.005; t=-2.32, P=0.022; t=-3.45, P=0.006). The postoperative angle ∠A of the above six groups were 33.8°±4.2°, 20.8°±3.5°, 25.8°±2.5°, 35.5°±4.5, 27.8°±3.5° and 26.8°±5.0°, respectively. The postoperative angle ∠B of the above six groups were 27.8°±3.5°, 36.2°±3°, 26.3°±1.8°, 29.8°±2.7°, 14.8°±1.5° and 37.2±4.2°, respectively. The differences between the ∠A of the steep sacral alar slope group, the mastoid protrusion group, and tthe lumbar sacralization group with that of the normal development patients were statistically significant, respectively ( t=9.17, -7.48, 7.97, P<0.001). The differences between the ∠B of the steep sacral alar slope group, the lumbar sacralization group, the sacral foramen oval degeneration group, and the S 1 anterior cortical depression group with that of the normal development patients were statistically significant, respectively ( t=-14.68, -10.93, -19.79, -35.8, P<0.001). Conclusion:This study proposes the "absolute stenosis" of the S 1 screw channel; In the treatment of patients with abnormal proximal sacral fracture, attention should be paid to S 1 anterior cortical depression and lumbar sacralization, and robot-assisted sacroiliac screw implantation can further improve the safety and accuracy of sacroiliac screw implantation.