Background Despite advancements in fixation techniques, S1 pedicle screw loosening remains a common complication of lumbosacral fusion surgeries for degenerative lumbar conditions, with reported rates ranging from 15.6% to 41.9%. This complication can compromise fusion success, leading to nonunion, adjacent segment disease, and revision surgeries. Compared with other surgical challenges, less is known about the incidence and predictors of S1 pedicle screw loosening. Given the high prevalence of S1 screw loosening and its associated complications, this systematic review and meta-analysis aim to report the incidence and risk factors contributing to S1 pedicle screw loosening in sacral fixation for degenerative lumbar conditions. Methods The literature search was conducted across 2 databases: PubMed and OVID. Study inclusion criteria were adults (age >18 years) undergoing lumbar fusion with S1 sacral fixation for degenerative lumbar conditions, with a minimum follow-up of 12 months and radiographic confirmation of screw loosening. Eligible studies included cohort or case-control designs that reported screw loosening rates. Extracted data included patient demographics (age, gender, body mass index, and bone mineral density [BMD]), surgical factors (screw type, length, and number of fusion levels), and complication rates. Results Of 174 studies queried, 21 met inclusion criteria, comprising 2598 patients who underwent lumbar fusion with sacral fixation with S1 pedicle screws (mean age 62 ± 7.2 years). The overall screw loosening rate in patients was 23.8% (696/2924) but varied from 3.0% to 55.0%. The pooled proportion of S1 pedicle screw loosening in patients after lumbosacral fixation was 27% (relative risk = 0.27, 95% CI 0.22–0.34, P < 0.0001). When assessed per screw, the screw-specific loosening rate was 8.7%. The pooled proportion of individual S1 pedicle screws loosening after lumbosacral fixation is 10% (relative risks = 0.10, 95% CI 0.06–0.17, P < 0.0001). Among included patients, the mean BMD was −0.63 ± 1.5, and the mean vertebral bone quality score was 3.3 ± 0.02. Conclusion The aggregate rate of S1 pedicle screw loosening after sacral fixation is 23.8%, highlighting a significant complication rate that may compromise surgical success. This complication is associated with adverse outcomes, pseudarthrosis, and adjacent segment disease, which can significantly impact patient quality of life. The high failure rate emphasizes the need for careful surgical planning, including patient-specific considerations such as BMD and vertebral bone quality, as well as the selection of optimal fixation techniques in lumbosacral fusion surgeries. Clinical Relevance While advancements in surgical techniques and hardware design have reduced failure rates, the persistent variability across studies underscores the need for further research. Level of Evidence 1.

Introduction: The optimal surgical approach for intraarticular calcaneal fractures remains debated. This study compares deep infection rates between the extended lateral (EL) and sinus tarsi (ST) approaches. Methods: A retrospective review was conducted of 782 patients treated surgically for OTA 82B/C calcaneal fractures across 15 institutions. Deep infection was defined as requiring surgical débridement or treatment for osteomyelitis. Risk factors were identified using univariate and multivariate analyses. Results: Of 782 fractures, 444 were treated with EL and 338 with ST. Deep infections occurred in 6.8% of EL and 3.0% of ST cases ( P = 0.017). Multivariate analysis found that surgical approach ( P = 0.03) and age ( P < 0.001) were independent risk factors. EL had more wound complications; ST had more symptomatic implants. Conclusion: The ST approach was associated with lower rates of deep infection and wound complications, even in higher-risk patients.

(1) Background and introduction: High-demand lumbosacral fusions are often supplemented with sacral-alar-iliac (SAI) screws. The idealized SAI trajectory was estimated to traverse 35 mm of sacrum before crossing the sacroiliac (SI) joint. However, there is debate on how much osseous purchase SAI screws achieve. The goal of this study was to determine the amount of osseous engagement achieved using a porous fusion–fixation screw (PFFS) when placed in a stacked SAI configuration. (2) Materials and methods: We retrospectively reviewed 40 consecutive patients who underwent sacropelvic fixation with stacked PFFS at our institution from 1 June 2022 to 30 June 2023, using intraoperative computed tomography (CT)-based computer navigation. A snapshot of each screw was taken and the length of purchase within the sacrum and ilium was measured on the axial image along the anterior and posterior aspect of each screw. Nineteen patients did not have adequate images available for review and were excluded. (3) Results: The overall mean anterior sacral engagement was 38.6 mm (±8.2 mm), which was found to be statistically significantly greater than the hypothesized threshold of 35 mm (p < 0.001), while posterior sacral engagement was 28.1 mm (±8.6 mm), which was not found to be statistically significantly greater than the hypothesized threshold of 35 mm (p = 1). The mean difference in sacral engagement between the anatomical location for the cephalad screws was 10.3 mm (p < 0.001) and 10.6 mm (p < 0.001) for the caudal screws. The total sacral surface area available for bone ingrowth for bilateral stacked PFFS was calculated to be 3338.3 mm², while the total iliac surface area available for bone ingrowth was 4364.8 mm². A mean difference in surface area availability between anatomical locations was −689.5 mm² (p < 0.001) for the sacrum and 689.5 mm² (p < 0.001) for the ilium. (4) Discussion and conclusions: The SAI trajectory screws in this cohort of patients achieved approximately 39 mm of sacrum engagement anteriorly and 28 mm posteriorly. This is consistent with prior estimates based on the idealized SAI pathway through the sacrum. PFFSs allow for simultaneous sacropelvic fixation and SI joint fusion, which may reduce the incidence of de novo SI joint pain in patients with long fusion constructs.

Background S1 pedicle screw loosening remains a recognized complication after lumbosacral fusion, but its incidence in shorter-segment constructs for degenerative lumbar disease remains incompletely defined. Methods Adults who underwent lumbosacral fusion, including S1 pedicle fixation, for degenerative lumbar pathology between 2021 and 2024 were retrospectively reviewed. Included patients had at least 12 months of radiographic follow-up. Screw loosening was defined as a radiolucent zone of at least 1 mm around the S1 screw and graded using a modified Shimizu-Lenke scheme (grades 0, 1, 2A, 2B, and 3). Results A total of 68 patients met inclusion criteria, with a mean age of 58.6 ± 14.4 years. The overall incidence of S1 screw loosening was 4.4% (3/68), with a mean time to screw loosening of 43.0 ± 9.2 weeks postoperatively. Interbody devices were placed at L5 to S1 in 66/68 (97.1%), most commonly via transforaminal lumbar interbody fusion approach (48/68, 70.6%), followed by anterior lumbar interbody fusion (13/68, 19.1%) and oblique lateral interbody fusion (5/68, 7.4%). Most constructs were short-segment fusions, and most patients received interbody support. Because loosening events were uncommon, analyses of potential associations with bone quality, construct characteristics, and alignment parameters should be interpreted as exploratory. Conclusion In this single-institution cohort, S1 pedicle screw loosening after degenerative short-segment lumbosacral fusion was uncommon. The findings support the need for larger studies with longer follow-up to clarify the contributions of bone quality, alignment, and fixation strategy to loosening risk. Clinical Relevance Variability of clinical presentation of S1 screw loosening highlight the need for further investigation into the relationship between S1 screw loosening and clinical outcomes. Level of Evidence 3.