Study design: Prospective non-randomized study. Background: Management of high-grade spondylolisthesis (HGS) remains challenging. Spinopelvic fixation such as iliac screw (IS) wasdeveloped to deal with HGS. However concerns regarding constructs prominence and increased infection-related revision surgery have complicated it’s use. We aim to introduce the modified iliac screw (IS) technique in treating high-grade L5/S1 spondylolisthesis (HGS) and it’s clinical and radiological outcomes. Methods: Patients with L5/S1 HGS who underwent modified IS fixation were enrolled. Pre- and postsurgical upright full and lumbar spine radiographs were obtained to analyze sagittal imbalance, spinopelvic parameters, pelvic incidence-lumbar lordosis mismatch (PI-LL), slip percentage, slip angle (SA), lumbosacral angle (LSA) and fusion status. Visual analogue scale (VAS), Oswestry disability index (ODI) were evaluated pre- and postoperatively for clinical outcomes assessment. Estimated blood loss, operating time, perioperative complications and revision surgery were documented. Results: From Jan 2018 to March 2020, 32patients (15 males) with mean age of 58.66 ± 7.77 years were included. The mean follow-up period was 49 months. The mean operation duration was 171.67 ± 36.66 min. At the last follow-up: 1) the VAS and ODI score were significantly improved (p<0.05), 2) PI increased by an average of 4.3°, the slip percent, SA and LSA were significantly improved (p<0.05), 3) four patients (16.7%) with sagittal imbalance recovered a good sagittal alignment, PI-LL within ± 10° was observed in all patients. One patient experienced wound infection. One patient underwent a revision surgery due to pseudoarthrosis at L5/S1. Conclusion The modified IS technique is safe and effective in treating L5/S1 HGS. Sparing use of offset connector could reduce hardware prominence, leading to lower wound infection rate and less revision surgery. The long-term clinical affection of increased PI value is unknown.

Background The removal of spinal implants was needed in revision surgery or in some cases whose fracture had healed or fusion had occured. The slip of polyaxial screw or mismatch of instruments would make this simple procedure intractable. Here we introduced a simple and practical method to address this clinical dilemma. Methods This is a retrospective study. The patients underwent new technique for retrieving the implants from July 2019 to July 2022 were labeled as group A, while the patients January 2017 to January 2020 were labeled as group B. Patients in each group were subdivided into revision surgery group and simple implants removal group according to the surgery fashion. In the new technique, the retrieved rod was cut off to a proper length which was matched with the size of tulip head, and was replaced into the tulip head. After tightened with nut, a monoaxial screw-rod “construct” was formed. Finally, a counter torque was applied to remove the “construct”. The operation duration, intraoperative blood loss, post-operative bacteria culture, hospital stay and costs were documented and analyzed. Results A total of 116 polyaxial screws with difficult removal of 78 patients (43 screws in group A, 73 screws in group B) were successfully retrieved by using this method. Significant differences were found in the mean operation duration, intraoperative blood loss when comparing the r group in group A and B, as well as the s group in group A and B (P < 0.05). There were no significant differences in hospital stay and costs between group A and B. Three patients were found positive bacteria culture of drainage tube/tape in group A (3/30), while 7 patients in group B (7/48). The most prevalent bacteria was Propionibacterium acnes. Conclusion This technique is practical and safe in for the poly-axial screw with difficult retrieval. Reduced operation duration and intraoperative bloods loss may potentially alleviate the hospitalization burden of patients. Positive cultivation results are common after implants removal surgery, but they rarely represent an organized infection. A positive culture with P. acnes or S. epidermidis should be interpreted with caution.