Preoperative CT Simulation of Iliosacral Screws for Treating Unstable Posterior Pelvic Ring Injury

BackgroundPercutaneous iliosacral screw placement is an important surgical method for the treatment of pelvic unstable fractures, but either intraoperative X-ray screws or navigational screws may be misplaced. This study aimed to demonstrate a safe, effective, and rapid medthod for placing iliosacral screws for the treatment of unstable posterior pelvic ring injury according to preoperative computed tomography (CT) planning using simulated screws. MethodsAfter preoperative CT simulation of iliosacral screws planning screw insertion point and trajectory, intraoperative percutaneous iliosacral screws were used to treat unstable pelvic posterior ring injury.The mechanism of injury, Tile classification, number of screw implants, operative time of each screw implantation, radiation exposure time of each screw implantation screw position, complications, and postoperative follow-up time were collected.Screw position grading was evaluated by Smith grading. ResultsA total of 24 screws were implanted in 21 patients (9 men and 12 women;mean age 41.3 years:range 14-71 years). Tile classification included:Tile B:15 patients;Tile C:6 patients. The mean placement time of each screw was 19.5 minutes (range 14-32min); Radiation exposure time: 0.6 min (range 0.5-0.9min); Two screws were inserted in 3 patients; One screw was inserted in 18 patients; According to Smith grading standard, grade0:20 cases; and Grade1:1 case; Mean postoperative follow-up time was 17.1months (range12-25 months); None of the patients showed nonunion. ConclusionsPreoperative CT simulation of iliosacral screws for placement planning, screw trajectory, and intraoperative placement of screws is a safe method that can be used to reduce surgical time, radiation exposure, and accurate screw placement.

Comparison of Biomechanical Performance of Five Different Treatment Approaches for Fixing Posterior Pelvic Ring Injury

Background. A large number of pelvic injuries are seriously unstable, with mortality rates reaching 19%. Approximately 60% of pelvic injuries are related to the posterior pelvic ring. However, the selection of a fixation method for a posterior pelvic ring injury remains a challenging problem for orthopedic surgeons. The aim of the present study is to investigate the biomechanical performance of five different fixation approaches for posterior pelvic ring injury and thus provide guidance on the choice of treatment approach in a clinical setting. Methods. A finite element (FE) model, including the L3-L5 lumbar vertebrae, sacrum, and full pelvis, was created from CT images of a healthy adult. Tile B and Tile C types of pelvic fractures were created in the model. Five different fixation methods for fixing the posterior ring injury (PRI) were simulated: TA1 (conservative treatment), TA2 (S1 screw fixation), TA3 (S1 + S2 screw fixation), TA4 (plate fixation), and TA5 (modified triangular osteosynthesis). Based on the fixation status (fixed or nonfixed) of the anterior ring and the fixation method for PRI, 20 different FE models were created. An upright standing loading scenario was simulated, and the resultant displacements at the sacroiliac joint were compared between different models. Results. When TA5 was applied, the resultant displacements at the sacroiliac joint were the smallest (1.5 mm, 1.6 mm, 1.6 mm, and 1.7 mm) for all the injury cases. The displacements induced by TA3 and TA2 were similar to those induced by TA5. TA4 led to larger displacements at the sacroiliac joint (2.3 mm, 2.4 mm, 4.8 mm, and 4.9 mm), and TA1 was the worst case (3.1 mm, 3.2 mm, 6.3 mm, and 6.5 mm). Conclusions. The best internal fixation method for PRI is the triangular osteosynthesis approach (TA5), followed by S1 + S2 screw fixation (TA3), S1 screw fixation (TA2), and plate fixation (TA4).