Background: Lumbar spinal stenosis (LSS) and carpal tunnel syndrome (CTS) often predate transthyretin amyloid cardiomyopathy. Objective: The aim of this study was to determine if patients with LSS/CTS have higher rates of cardiovascular events and worse survival, even in the absence of recognized transthyretin amyloid cardiomyopathy and the incidence of amyloidosis in patients with LSS/CTS. Methods: Retrospective population-based cohort study of patients (cases) with LSS/CTS diagnosis between 1995 and 2015 (50-90 years old) identified through Rochester Epidemiology Project (Minnesota, USA). Cases were matched with 3 age- and sex-matched controls. Outcomes—investigated with comprehensive regression models—were heart failure, atrial arrhythmias, device implantation, composite endpoint, survival, and incident amyloidosis. Results: A total of 6,076 LSS cases and 16,205 controls and 6,664 CTS cases and 17,462 controls were included. Compared to controls, LSS and CTS cases had more comorbidities at baseline and higher likelihood of cardiac events. Survival was worse in LSS cases vs controls (HR: 1.26; 95% CI: 1.19-1.33; P < 0.001) but similar in CTS cases vs controls (HR: 0.95; 95% CI: 0.90-1.01; P = 0.10). For LSS and CTS groups, respectively, the 10-year rate of amyloidosis diagnosis was 1.1% (vs 0.5% for controls, cause-specific HR: 2.18; P < 0.001) and 0.9% (vs 0.3%, cause-specific HR: 2.87; P < 0.001). Patients with both LSS and CTS had a 10-year incidence rate of amyloidosis of 1.45%. Conclusion: LSS and CTS were associated with increased likelihood of cardiovascular events and amyloidosis diagnosis. This highlight the importance of a dedicated assessment of cardiovascular symptoms for LSS/CTS patients, particularly if both conditions are present.

BACKGROUND CONTEXT In multilevel spine fusion (>4 levels), pelvic fixation is commonly used to improve fusion rates at L5–S1, reduce instrumentation failure, and maintain alignment. However, pelvic fixation failures remain common, with acute complications occurring in approximately 5% of cases and long-term failure rates reported between 34% and 47%. PURPOSE To determine whether placement of triangular titanium implants (TTI) suprajacent to S2-alar-iliac (S2AI) screws reduces pelvic fixation failure in multilevel spine fusion for adult spinal deformity. STUDY DESIGN/SETTING Prospective, multicenter, international, partially blinded randomized clinical trial. PATIENT SAMPLE A total of 222 patients undergoing multilevel (≥4 levels) spinal fusion with planned S2AI pelvic fixation. OUTCOME MEASURES Radiographic measures of pelvic fixation failure. METHODS Adults aged 21–75 years with spinal deformity undergoing multilevel fusion were randomized 1:1 to S2AI fixation alone or S2AI with TTI placement suprajacent to each screw. At 24-month follow-up, full-spine radiographs and CT imaging were evaluated by an independent radiologist for screw integrity, rod fracture, implant positioning, bone apposition, sacroiliac joint fusion, and adverse bone reactions. Screw and implant lucencies were graded using a modified Shimizu-Lenke classification. RESULTS The primary composite endpoint (S2AI screw breakage, lucency or pullout, or rod fracture distal to S1) occurred less frequently in the S2AI+TTI group compared with S2AI alone (11.0% vs 19.5%, p=0.0415). All individual components of the composite endpoint, except distal rod fracture, occurred less frequently in the TTI group. TTI placement did not significantly affect sagittal or coronal alignment. The overall rate of rod fracture was slightly higher in the S2AI+TTI group (9.2% vs 5.3%), though this difference was not statistically significant (p=0.197). CONCLUSIONS Placement of triangular titanium implants suprajacent to S2AI screws significantly reduces pelvic fixation failure rates in multilevel spine fusion. FDA Device/Drug Status iFuse 3D (Approved for this indication).

Objectives Frailty, reflecting reduced physiological reserve and increased vulnerability to stressors, is common among patients with idiopathic normal pressure hydrocephalus (iNPH). The extent to which frailty influences gait outcomes following ventriculoperitoneal shunting (VPS) remains unclear. This study evaluated the association between frailty and objective gait changes after VPS in patients with iNPH. Methods A single-center database was reviewed for patients who underwent VPS for iNPH with preoperative gait analysis between October 2018 and May 2024. Gait parameters included cadence, velocity, stability ratio, step width, stride length, single and total support. Patients were stratified by the modified 5-item frailty index (mFI) into non-frail (mFI-0), pre-frail (mFI-1), and frail (mFI-2+). Generalized additive mixed-effects models evaluated time, mFI, and their interaction with patient-specific random effects. Results Of the 242 patients that were included, 60 (24.8%) were classified preoperatively as non-frail, 109 (45%) were pre-frail, and 73 (30.2%) were frail, with no difference in age distributions across groups. A total of 844 gait analyses were performed with a median of three per patient and a median latest follow-up time of 12.2 months. Preoperative gait parameters varied significantly across mFI groups. However, the degree of change in gait parameters between preoperative and first postoperative gait assessments did not differ across mFI groups, with most patients exhibiting improvement. Conclusion Frailty correlated with worse baseline gait performance but did not diminish the likelihood or durability of gait improvement following VPS. These findings suggest that VPS yields meaningful gait benefits in patients with iNPH regardless of frailty status.

BACKGROUND CONTEXT Nonunion remains a common complication after posterior lumbar interbody fusion and is associated with persistent back pain, lower health-related quality of life, and increased reoperation rates. Although recombinant bone morphogenic protein-2 (rhBMP-2) remains a gold standard to increase fusion efficacy in high-risk patients, it is costly and associated with adverse effects including postoperative seroma, neuritis, and potential for heterotopic ossification. I-Factor, a P-15 polypeptide enhanced composite bone graft, has level-one evidence supporting its noninferiority to autograft. However, direct clinical comparisons of fusion rates with i-Factor and rhBMP-2 are limited and poorly controlled. PURPOSE The current study utilized a self-controlled design to compare posterolateral lumbar fusion efficacy between lateralities grafted with i-Factor or Infuse (rhBMP product). STUDY DESIGN/SETTING Self-controlled prospective cohort study. PATIENT SAMPLE All adult patients who underwent open 1- to 3-level posterolateral lumbar fusion with or without TLIF for degenerative conditions by a single surgeon at an academic center between 2022 and 2024 were prospectively enrolled. OUTCOME MEASURES Fusion status, fusion cross-sectional area, fusion mass maturity, and regularity. METHODS All patients were randomly assigned by a third party to receive i-Factor in one posterolateral gutter and Infuse in the contralateral gutter. Posterolateral fusion at each level was assessed on the one-year postoperative CT scan based on continuous osseous bridging. Fusion masses were further characterized based on cross-sectional area and osseous maturity and regularity. Paired univariate analysis compared fusion metrics based on laterality. RESULTS A total of 71 patients with 114 unique fusion levels were enrolled. In TLIFs, there were no significant differences in frequencies of i-Factor and Infuse placement on the non-facetectomy side. Fusion rates in the i-Factor and Infuse grafted posterolateral gutters were 86.8% and 84.2%, respectively (p=0.700). There were no significant differences in posterolateral fusion mass cross-sectional area, maturity, or bony regularity. CONCLUSIONS In this self-controlled lumbar fusion cohort, there were no significant differences in posterolateral fusion mass quantitative or qualitative metrics based on the use of i-Factor or Infuse, suggesting both can be efficacious graft options in selected high-risk patients. FDA Device/Drug Status Yes—iFactor (approved for this indication).

Study design Retrospective Cohort Study. Objective The objective of this study is to investigate the effect of cage subsidence on neuroforaminal area after anterior cervical discectomy and fusion (ACDF) utilizing computed tomography (CT). Summary of background data Restoration of disc height via implantation of an interbody device provides an indirect decompression of the cervical neuroforamina. Interbody cage subsidence is a potential postoperative occurrence, but the effect of this on neuroforaminal area has yet to be characterized. Methods A retrospective review was conducted of patients who underwent one- to four-levels of ACDF utilizing an interbody device with anterior plating. Cage subsidence, neuroforaminal area, height and width were measured on CT scans preoperatively and at least 6 months postoperatively. Levels with a cumulative sum of cranial and caudal subsidence greater than 4 mm were classified as severely subsided, while levels with cumulative subsidence less than 4 mm were classified as non-severely subsided. Results A total of 83 patients (151 levels) were included in this retrospective analysis. Average endplate subsidence was 3.2 ± 1.9 mm. Non-severely subsided levels demonstrated a greater perioperative increase in neuroforaminal area (7.9 vs 2.1 mm2, p < 0.001), neuroforaminal height (1.1 vs 0.4 mm, p < 0.001) and neuroforaminal width (0.7 vs 0.1 mm, p < 0.001) compared to severely subsided levels. Interbody subsidence significantly predicted a decreased change in neuroforaminal height, width and area (p < 0.001). Severe subsidence was associated with an increased rate of pseudarthrosis, but similar reoperation rates and recurrent neurologic deficits between the two groups. Conclusions Severe subsidence of interbody cages after an ACDF was associated with a decreased perioperative change in neuroforaminal dimensions. This decrease in the size of the neuroforamen may reduce the effect of indirect decompression of the nerve root.

BACKGROUND:Magnetic Resonance Elastography (MRE) of the brain provides quantitative biomarkers of mechanical properties of brain tissue. Prior studies have shown that an advanced 3D MRE can differentiate idiopathic normal pressure hydrocephalus (iNPH), from other neurodegenerative disorders. In this pilot study, we assessed whether a simplified 2D MRE protocol, that is more widely available, could detect stiffness differences between iNPH and non-iNPH cognitively impaired patients, thus providing preliminary diagnostic discrimination, while using a previously developed 3D MRE classifier as a secondary exploratory comparator. METHODS:In this prospective study, 10 patients with clinically diagnosed iNPH (iNPH-group) and 10 cognitively impaired patients due to non-iNPH causes (CI-group), underwent 2D brain MRE between September 2024 and April 2025. Median stiffness was extracted from a standardized, manually defined region of interest at the brain vertex. A previously validated 3D MRE pattern-analysis support vector machine (SVM) classifier was applied to this prospective cohort as a secondary exploratory comparator. Group differences were assessed using Wilcoxon rank-sum tests. Diagnostic performance was evaluated using receiver operating characteristic analysis as an exploratory assessment of discrimination. RESULTS:Median stiffness was higher in iNPH-group than CI-group (1.62 vs 0.98 kPa; p < 0.001). Stiffness demonstrated excellent discriminatory ability, yielding an apparent AUC of 1.00 with an optimal threshold of 1.43 kPa. The 3D SVM decision metric also yielded an apparent AUC of 1.00. The pretrained SVM model classified 18 of 20 subjects correctly (accuracy: 90.0% [95% CI: 68.3%-98.8%]). While promising, these performance estimates should be interpreted cautiously given the limited sample size. CONCLUSION:This study provides preliminary evidence that a 2D MRE protocol may help discriminate iNPH from other disorders causing cognitive impairment, providing a foundation for larger multi-center validation studies for assessing reproducibility, generalizability, and potential clinical utility.

Individuals with both Alzheimer’s Disease (AD) and cerebrospinal fluid (CSF) dynamics disorders, such as idiopathic normal-pressure hydrocephalus (iNPH), exhibit reduced CSF Aβ42 levels, complicating the interpretation of AD biomarkers. However, the influence of CSF dynamics on blood-based AD biomarkers remains unclear. This study investigated whether immunoprecipitation mass spectrometry (IP-MS)-based AD plasma biomarkers were associated with disproportionately enlarged subarachnoid space hydrocephalus (DESH) on MRI. This retrospective, cross-sectional study included 509 participants from the Mayo Clinic Study of Aging who underwent MRI, [¹¹C] Pittsburgh compound B (Aβ) PET imaging, and plasma assessments of phosphorylated tau 217 (p-Tau 217), Aβ40, and Aβ42. Age-adjusted logistic regression analyses were conducted to evaluate whether abnormal levels of p-Tau 217,

Background: Anterior cervical discectomy and fusion (ACDF) is a widely performed procedure for treating degenerative cervical spine conditions. While it effectively addresses neural decompression and restores segmental alignment, the interplay of baseline alignment and implant-specific factors on postoperative segmental alignment remains underexplored. This study evaluates the influence of preoperative cervical alignment and interbody cage design on segmental alignment changes following 1- to 3-level ACDF. Methods: Following institutional review board approval, we identified 258 patients undergoing ACDF for degenerative pathology between 1 January 2010 and 31 December 2023. Preoperative and postoperative radiographs were analyzed for cervical alignment, disc height, and segmental lordosis. Cage dimensions, lordosis, and positioning relative to vertebral landmarks were recorded. Multivariable linear regression models evaluated predictors of postoperative disc height, segmental lordosis, and their respective changes. Results: Postoperative disc height was positively associated with greater cage height (β = 1.13 mm per mm, p < 0.001) and negatively associated with greater cage lordosis (β = -0.10 mm per °, p = 0.001). Segmental lordosis was positively influenced by cage height (β = 0.78° per mm, p = 0.002) and lordosis (β = 0.42° per °, p = 0.002) but was negatively correlated with the distance of the cage from the anterior edge of the cranial vertebra (β = -1.76° per mm, p = 0.004). Greater preoperative segmental kyphosis predicted more significant postoperative lordosis correction (β = -1.07° per °, p < 0.001). Conclusions: This study underscores the importance of preoperative alignment and interbody cage design in achieving optimal segmental correction following ACDF. While cage height primarily drives disc height restoration, surgical technique, particularly anterior placement of the cage, is pivotal for enhancing segmental lordosis. These findings support personalized surgical planning to optimize alignment and patient outcomes.

STUDY DESIGN:Retrospective cohort. OBJECTIVE:This study aims to assess the effects of CT-based subsidence on lumbar sagittal alignment and patient-reported outcome measures (PROMs) after transforaminal lumbar interbody fusion (TLIF), and to determine if subsidence and cage properties are independent predictors of postoperative changes in regional lordosis. SUMMARY OF BACKGROUND DATA:Subsidence is a well-known complication following interbody fusion and has previously been associated with recurrence of preoperative symptoms and higher reoperation rates. There is incomplete evidence to characterize the effects of subsidence on lumbar alignment and PROMs following TLIF. METHODS:All adult patients who underwent 1- or 2-level TLIF at a multi-institutional academic center between 2017 and 2019 were retrospectively identified. Interbody subsidence at the superior and inferior endplate of each TLIF level was directly measured on both coronal and sagittal CT scans obtained between 6 months and 1 year postoperatively. Patients were grouped based on the maximum subsidence at each operative level: mild-moderate (<4 mm) or severe (≥4 mm). Preoperative, immediate (<3 mo), and intermediate (>6 mo) postoperative radiographic outcomes (local and global lumbar alignment) and PROMs (VAS Back, Oswestry Disability Index, PROMIS Physical Function and Mood) were collected. Univariate and multivariate analysis compared patient demographics, surgical factors, and changes in radiographic measures and PROMs across subsidence groups. Multiple linear regression analyzed independent effects of subsidence and cage characteristics on alignment. RESULTS:Sixty-seven patients with 85 unique fusion levels were included (55 with mild-moderate subsidence, 30 with severe subsidence). Levels with severe subsidence demonstrated significantly less regional lordosis at final follow-up than nonseverely subsided levels (6.4 vs. 9.1 degrees, P =0.032). No PROM significantly differed between severe and nonsevere subsidence subgroups. Linear regression analysis revealed that severe subsidence was a strong independent predictor of regional lordosis ( P =0.029) at final follow-up. CONCLUSIONS:Severe subsidence negates perioperative improvements in regional lordosis following TLIF, while changes in regional alignment are maintained in the absence of severe subsidence. LEVEL OF EVIDENCE:Level III.

BACKGROUND:The purpose of this study was to determine whether placement of triangular titanium implants (TTI) suprajacent to S2-alar-iliac (S2AI) pelvic fixation screws during multilevel spinal fusion surgery for adult spine deformity reduces pelvic fixation failures. METHODS:This prospective, multicenter, international, partially blinded randomized clinical trial included 222 patients scheduled for multilevel spinal fusion surgery with S2AI-based pelvic fixation. In the S2AI+TTI group, the mean age was 64.9 years, 54.1% were female, 3.7% were Hispanic, 5.5% were African American, and 1.8% were Asian. In the S2AI-alone group, the mean age was 64.8 years, 58.4% were female, 3.5% were Hispanic, 7.1% were African American, and 0.9% were Asian. Subjects were randomized to pelvic fixation using S2AI screws alone versus S2AI+TTI. Scheduled follow-up included a 24-month full-spine radiograph and a high-resolution computed tomography (CT) scan, which was independently interpreted. RESULTS:The primary composite radiographic end point (S2AI screw breakage, lucency, or pullout, or posterior spinal rod breakage distal to S1) occurred less frequently in the S2AI+TTI group than in the S2AI-alone group (11.0% versus 20.4%, p = 0.0415). Except for rod-screw dissociation and rod fracture distal to S1, all components of the primary composite end point occurred less frequently in the S2AI+TTI group. TTI placement did not affect sagittal or coronal spinal alignment parameters. The rate of rod fracture throughout the spinal construct was slightly higher in the S2AI+TTI group (9.2% versus 5.3%) but the difference was not significant (p = 0.197). CONCLUSIONS:Placement of TTI suprajacent to S2AI screws reduced the rate of pelvic fixation failure in patients undergoing multilevel spinal fusion with pelvic fixation. LEVEL OF EVIDENCE:Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Disorders of cerebrospinal fluid (CSF) dynamics, including idiopathic normal pressure hydrocephalus (iNPH), idiopathic intracranial hypertension (IIH), and spontaneous intracranial hypotension (SIH) frequently present clinical and imaging phenotypes that overlap with other disease processes. Although conventional MRI remains central for identifying characteristic morphologic features, many imaging findings have variable sensitivity, particularly across disease stages. As a result, current diagnostic pathways and treatment selection is still often reliant on invasive, snapshot-based physiologic tests. Magnetic resonance elastography (MRE) provides a noninvasive, quantitative approach to probe brain viscoelastic properties reflecting tissue microstructure and mechanical strain. These properties are influenced by intracranial pressure-volume states within the Monro-Kellie constraints, offering a potential "systems-level" biomarker of intracranial compliance and CSF-venous coupling. This review summarizes the technical foundations of brain MRE relevant to radiologists, including the fundamentals and technical aspects of the technique, and the key sources of measurement variability that influence interpretability and reproducibility. It synthesizes the current clinical evidence supporting MRE for diagnosis, phenotyping, and longitudinal treatment assessment across CSF dynamics disorders, with emphasis on practical integration into contemporary imaging workflows and standardized region-of-interest reporting. Finally, we highlight limitations of existing literature and priorities for future research for MRE in this patient population.

Spinal fusion is widely performed to treat instability of various spinal pathologies. Currently, the clinical gold standard is still autografts, which unfortunately are limited by donor site morbidity, restricted supply, and inconsistent outcomes. To overcome these challenges, we developed an organic-inorganic nanohybrid (click-ON) cement based on poly(propylene fumarate) (PPF) polymers cross-linked through the strain-promoted azide-alkyne cycloaddition (SPAAC) bioorthogonal click chemistry. This catalyst-free system cures rapidly in situ without external energy or toxic initiators, enabling safe and practical surgical handling. The cement was further reinforced with osteogenic nanohydroxyapatite (nHA) to improve osteoinductivity and microspheres releasing bioactive recombinant human bone morphogenetic protein 2 (rhBMP-2) and recombinant human vascular endothelial growth factor (rhVEGF) to promote coupled osteogenesis and angiogenesis. In a sheep lumbar spinal fusion model, the click-ON cement was implanted with an injectable formulation in the interbody space and a moldable formulation in the posterolateral fusion site with clinically used autograft/rhBMP-2 as the positive control. Longitudinal CT imaging demonstrated fusion with bridging bone formation across both the interbody space and posterolateral region after 6 months. Histological analyses confirmed extensive new bone deposition, integration with host tissue, and vascular ingrowth within the cement, while immunohistochemical staining showed the colocalization of CD31 and alkaline phosphatase (ALP), indicating active angiogenesis and osteogenesis, respectively. The outcomes are comparable to the positive control, which are clinical gold standard bone grafts. Manual palpation further verified the mechanical stability of the fused segments in sheep with a bioactive click-ON cement. These results established click-chemistry-enabled PPF-based cement as a promising alternative to autografts, offering advantages in moldability, biological activity, and functional fusion outcomes.

BACKGROUND Bertolotti syndrome is an underrecognized cause of chronic low back pain. Back pain generated from Bertolotti syndrome is believed to result from altered weight dissipation mechanics and/or instability of the pseudoarticulation, while local nerve root compression may result in radiculopathy. Here, the authors describe the findings of a patient with treatment-refractory low back pain found to have a cystic lesion arising from a Bertolotti joint causing L5 nerve root compression. To their knowledge, this has not been previously described in the literature. OBSERVATIONS Despite early recognition of Bertolotti syndrome, the patient’s back pain remained resistant to many years of both conservative and surgical management. The novel finding of a cyst arising from the pseudoarticulation complicated the management. The patient is scheduled to undergo further surgery this year. LESSONS This case highlights a pseudocyst associated with a Bertolotti joint. The cyst introduced additional clinical uncertainty to what is already an uncommon and difficult to treat condition. Resection of the Bertolotti joint failed to improve the patient’s symptoms. Postoperatively, a complex hemorrhagic pseudocyst was seen on imaging, possibly due to the pseudoarticulation with persistent motion. Ongoing efforts to characterize Bertolotti syndrome and its associated imaging findings are necessary to better optimize management strategies in these patients. https://thejns.org/doi/10.3171/CASE25948

Effective bone regeneration requires not only robust osteoinduction but also precise immunomodulation to orchestrate the complex healing process. In this study, we present a strategy for engineering multifunctional three-dimensional (3D) stem cell spheroids (Sphe-BP-IL4-BMP2) by integrating black phosphorus (BP) nanosheets coloaded with interleukin-4 (IL-4) together with recombinant human bone morphogenetic protein-2 (rhBMP-2). BP nanosheets served as a biodegradable scaffold and a delivery vehicle, enabling sustained release of rhBMP-2 and IL-4 to enhance osteogenic differentiation and to promote anti-inflammatory M2 macrophage polarization, respectively. The resulting spheroids exhibited a well-defined morphology, enhanced cell viability, and uniform BP nanosheet distribution. The in vitro studies demonstrated Sphe-BP-IL4-BMP2 has significantly upregulated osteogenic markers and ALP activity alongside potent immunomodulatory effects on macrophages. Further in vivo implantation into a rat calvarial defect model led to increased angiogenesis and accelerated bone regeneration without adverse effects. The results highlight the therapeutic synergy between osteoinductive and immunomodulatory cues within a 3D spheroid platform, offering a promising avenue for treating critical-sized bone defects.

Background/Objectives: To identify predictors of successful fusion and adjacent segment disease (ASD) following ALIF. Methods: Records of patients undergoing one- or two-level ALIF were queried for baseline and postoperative radiographic data, demographics, operative notes, and implant characteristics. All had ≥1 year of follow-up with CT, and multivariable Cox regression was used to identify predictors of radiographic fusion through the interbody, ASD, and ASD requiring reoperation. Results: In total, 177 patients (median 59 yr; 52.5% male) were treated at 245 unique levels, of which 193 fused (81.3% with posterior fixation and 59.6% with standalone), 43 had ASD (17.6%), and 14 had ASD requiring reoperation (5.7%). Fusion was predicted by anterior cage placement (HR 0.94/mm; 95% CI [0.90, 0.98]; p = 0.003) and BMP use (HR 1.92; [1.15, 3.18]; p = 0.012). Radiographic ASD was predicted by older age (HR 1.08 per year; [1.03, 1.14]; p < 0.001), undergoing a revision [vs. index] fusion operation (HR 3.51; [1.44; 8.59]; p = 0.006), lower preoperative disc height (HR 0.83/mm; [0.74, 0.94]; p = 0.003), and preoperative facet vacuum phenomenon (HR 2.46; [1.18, 5.15]; p = 0.017). None of the extracted variables predicted reoperation for ASD. Conclusions: BMP use along with anterior cage placement and posterior fixation may improve the odds of fusion through the interbody following one- or two-level ALIF. Adjacent segment pathology is more common in patients with greater preoperative degenerative pathology (vacuum sign; more collapsed disc) and advanced age. Pelvic fixation did not improve fusion odds, but the data highlight the benefits of supplementary posterior fixation vs. standalone ALIF.

BACKGROUND CONTEXT Achieving durable alignment at the lumbosacral junction remains a major challenge in adult spinal deformity (ASD) surgery. Although pelvic tilt (PT) correction is essential for restoring sagittal alignment, postoperative regression toward preoperative values is common. The impact of pelvic fixation density on maintenance of alignment remains unclear. PURPOSE To evaluate whether increased pelvic fixation density using multiple pelvic fixation (MPF) reduces postoperative pelvic tilt regression compared with single pelvic fixation (SPF) in ASD patients. STUDY DESIGN/SETTING Retrospective analysis of a multicenter prospective ASD database. PATIENT SAMPLE A total of 190 ASD patients (2010–2024) undergoing fusion to the sacrum with L5–S1 interbody arthrodesis and meeting SRS-Schwab criteria. OUTCOME MEASURES Primary outcome was pelvic tilt regression from 6 weeks to 1 and 2 years postoperatively. Predictor variable was magnitude of initial PT correction (preoperative to 6 weeks). Effect modifier was pelvic fixation density (MPF vs SPF). METHODS Patients were stratified into MPF (≥3 pelvic fixation points with bilateral constructs) and SPF (bilateral two-screw fixation). Inclusion criteria required ≥1 of the following: revision surgery, ≥5-level fusion, prior lumbosacral pseudarthrosis, three-column osteotomy, or multiple two-column osteotomies. Linear regression analysis evaluated the relationship between initial PT correction and subsequent PT regression, stratified by fixation density. RESULTS Among 190 patients, 53.1% were female, with a mean age of 68.9 years and BMI of 29.1 kg/m². Mean preoperative PT/pelvic incidence was 24.0°/53.4°, with an average of 9.2 levels fused. A total of 86 patients (45.3%) underwent MPF and 104 (54.7%) underwent SPF. At 1 year, greater initial PT correction was associated with increased PT regression; however, fixation density significantly modified this relationship. PT regression increased by 4.80° per 10° of correction in the SPF group versus 1.61° in the MPF group (p=0.001). At 2 years, similar trends were observed, with PT regression of 6.51° per 10° in the SPF group versus 0.92° in the MPF group (p=0.015). CONCLUSIONS Increased pelvic fixation density is associated with improved maintenance of pelvic tilt correction in ASD surgery. MPF allows greater initial correction with less regression over time, suggesting a key role for fixation strategy in long-term alignment durability. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND AND OBJECTIVES:Ventriculoperitoneal shunt (VPS) placement is a common treatment for idiopathic normal pressure hydrocephalus (iNPH), but patients may require VPS revision. This study aims to evaluate the effectiveness of a standardized VPS placement protocol by comparing indications and rates of shunt revision compared with a historical institutional cohort. METHODS:All patients treated with VPS for "suspected" iNPH at a tertiary care center between January 2000 and January 2023 were retrospectively reviewed and divided into temporally distinct historical (before 2017) and standardized (after 2017) cohorts. Cumulative incidence and timing of VPS revision were compared using competing risks analyses. RESULTS:A total of 561 patients (median age 75.0 years) were identified with 324 (57.8%) in the historical and 237 (42.2%) in the standardized cohorts. Significant variations in surgical technique and shunt hardware were noted between the cohorts. With a median follow-up of 11.4 months for historical and 12.4 months for standardized cohort, shunt revisions occurred in 19.4% and 8.4% of patients in the historical and standardized cohorts, respectively (P < .001). Revision indications also varied significantly with lower rates of overdrainage (P < .001), infection (P < .001), and proximal malfunction (P = .042) but higher rate of distal malfunction (P = .03) in the standardized cohort. Notably, no infections were noted in the standardized cohort. CONCLUSION:Risk of shunt revision among iNPH patients may be associated with modifiable factors related to surgical technique and shunt hardware selection. Importantly, no short-term complications such as hemorrhage, infection, or catheter malposition were observed with the standardized protocol. Development and refinement of standardized shunt protocols for iNPH patients should be commonplace to facilitate tracking, identification, and modification of modifiable technical risk factors.

Interest is surging in applications of artificial intelligence (AI) for automated measurement of spinopelvic parameters in patients with spine disorders. More than three-quarters of scientific papers citing the development of new AI-enabled algorithms have been published in the last five years, driven by spine surgeon demand for alternatives to manual measurement methods that are time consuming to apply and prone to significant inter- and intra-observer variability. The rapid evolution of AI technologies for automated spinopelvic measurement yields great promise, as published validation studies demonstrate continuous improvements in accuracy and reliability and substantial reductions in measurement time compared to manual and semi-automated methods. However, the absence of standardized protocols for landmark placement, vertebral labeling, and measurement reporting along with the limited availability of external ground truth data and consensus-based guidance on statistical reporting impede external validation, generalizability, comparison of algorithm performance, and widespread adoption. The development of publicly available, multi-institutional databases of ground truth data as well as expert-led standardization initiatives that promote harmonized measurement methods and reporting will ideally allow automated algorithms to reach their full clinical potential.