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Study design: Retrospective Cohort.

Objective: To investigate impact of controlled/uncontrolled sub-stratification of modified frailty index (MFI-5) on postoperative outcomes after lumbar fusion for degenerative disease.

Background: mFI-5 outperforms age as a predictor of postoperative risk. Sub-stratification of mFI-5 by controlled versus uncontrolled frailty has allowed for better risk prognostication in spinal deformity cases.

Methods: Adult patients who underwent elective, single-level lumbar fusion (2017-2021) were identified. Fusions for infection/trauma/tumor/revision were excluded. Patients were classified as frail/non-frail based on having any mFI-5 criteria (history of chronic obstructive pulmonary disease [COPD], congestive heart failure [CHF], diabetes mellitus [DM], hypertension [HTN] requiring medication, and functional status). Frailty was considered controlled unless patients had a COPD exacerbation within 3 months prior to surgery, preoperative hemoglobin A1c >7, or HTN ≥140/90 mmHg for ≥2 visits.

Results: 1,286 patients were included (controlled/uncontrolled/non-frail-804/159/323). Uncontrolled frailty patients had more 31-90 day ED visits (9.43% vs. 4.13%,P=0.009), 0-30 day readmissions (5.66% vs. 2.49%,P=0.042), and renal complications (13.2% vs. 6.38%,P=0.005) compared to controlled frailty patients. Controlled frailty patients were older (56.3 vs. 62.9, P<0.001) and had more 0-30 day ED visits (2.19% vs. 5.63%,P=0.021) compared to non-frail patients. Uncontrolled frailty patients were older (56.3 vs. 63.8,P<0.001), and had higher 0-30 (2.19% vs. 7.55%,P=0.010) and 31-90 day ED visits (1.88% vs. 9.43%,P<0.001), 0-30 day readmissions (0.93% vs. 5.66%,P=0.003), and renal complications (3.76% vs. 13.2%,P<0.001) compared to non-frail patients. Multivariable regression demonstrated that uncontrolled frailty alone was independently associated with 30-day ED visits (odds ratio [OR]-3.68,P=0.030), any ED visit (OR-3.33,P=0.008), 90-day readmission (OR-5.42,P=0.047) and any readmission (OR-5.41,P=0.005).

Conclusion: Multivariable regression demonstrated that uncontrolled frailty was an independent risk factor for ED visits and readmission after single-level lumbar fusion. Further work is needed to identify the best pre- and postoperative strategies to optimize outcomes for this vulnerable population.

Study design: Cadaveric validation study.

Objective: To evaluate the accuracy of a structured four-step ultrasound (US)-guided workflow for lumbar spinal level identification (SLI) using cadaveric specimens.

Summary of background data: Despite the routine use of fluoroscopic verification, wrong-level spinal surgery continues to be a documented and concerning complication. Fluoroscopy exposes patients and staff to ionizing radiation and requires specialized personnel and infrastructure. US has been utilized for SLI in obstetric and anesthetic applications but remains underexplored in surgical workflows.

Methods: Ten fresh-frozen cadavers underwent US imaging to identify lumbar levels. A newly developed four-step protocol was employed: (1) Midline localization, (2) Sacral surface tracing, (3) S1-Superior articular process (SAP) recognition, (4) Interlaminar space enumeration. Five spinal needles were placed under US guidance in each specimen (L1-2 through L5-S1), with one needle per level. Fluoroscopic imaging was then used to confirm needle placement accuracy. A level was defined as misidentified if the projected trajectory from the needle tip violated predefined radiographic boundaries.

Results: A total of 50 lumbar levels were assessed across ten cadaveric specimens, with 25 procedures performed from the right side and 25 from the left. Fluoroscopic validation demonstrated accurate level identification in 49/50 cases, yielding an accuracy rate of 98%. The single misidentification occurred at the L5-S1 level during the third step of the workflow, where the S1 SAP was erroneously interpreted as the L5 inferior articular process. No systematic error patterns were observed, and the four-step protocol proved reproducible across specimens.

Conclusion: This cadaveric feasibility study establishes a high accuracy of US-guided lumbar level identification. A structured and reproducible workflow for level localization was established, integrating a novel four-step protocol. These findings represent a first step toward a radiation-free alternative for preoperative lumbar level verification in spinal surgery. Further investigations are warranted to validate these results in clinical settings.

Study design: Cohort study of pooled data from patients enrolled in a behavior randomized trial (RCT) that successfully increased physical activity after complex lumbar surgery.

Objective: To assess associations between increased energy expenditure from walking and general functional status and lumbar-specific disability 12 months after enrollment.

Background: Many postoperative patients retain preoperative sedentary lifestyles and thus do not obtain general health and spine-related benefits of physical activity.

Methods: Three months after complex lumbar surgery (i.e. fusion, ≥3 levels) patients were enrolled in a behavior RCT aimed at increasing physical activity from walking measured by the Paffenbarger Physical Activity and Exercise Index (PAEI) in kcals/week. Data were pooled for this analysis to assess associations between kcals/week at 12 months and change in general functional status (RAND 12-Item Physical Component Summary score, PCS) and lumbar-specific disability (Oswestry Disability Index, ODI). Covariates considered included age, sex, body mass index, back pain, surgical complexity, depressive symptoms, and enrollment PCS, ODI and kcals/week.

Results: Among 231 patients (mean age 64, 47% women) enrollment walking was 1361±1294 kcals/week and increased to 1935±1979 kcals/week at 12 months, mean within-patient change 574 kcals/week (P<.0001). Enrollment PCS score was 37±10 and improved to 44±11 at 12 months, exceeding a clinically important difference (CID). Change in PCS score was associated with kcals/week at 12 months in multivariable analysis controlling for enrollment kcals/week and PCS score (coefficient .002, 95% CI .001-.003, P<.0001). Enrollment ODI score was 34±16 and improved to 27±19 at 12 months, exceeding a CID. Change in ODI score was associated with kcals/week at 12 months in multivariable analysis controlling for enrollment kcals/week and ODI score (coefficient .01, 95% CI 0.002-.005, P<0.0001).

Conclusions: Increased postoperative energy expenditure from walking at 12 months was associated with improvement in general functional status and reduced lumbar-specific disability in patients after complex lumbar surgery.

Study design: Prospective cohort study.

Objective: To identify patient factors that predict changes in adjacent segment kinematics three years after ACDF.

Summary of background data: Approximately 25% of patients who undergo anterior cervical discectomy and fusion (ACDF) develop symptomatic adjacent segment disease (ASD) requiring reoperation within 10 years. Studies have found associations between ASD and patient genetics, age, BMI, psychiatric history, and preoperative disc degeneration. Few studies have linked these factors to mechanical changes to explain ASD.

Methods: Patients performed flexion/extension and axial rotation captured by biplane radiography before, one year after, and three years after ACDF (3YR-POST). Digitally reconstructed cervical radiographs were matched to the biplane radiographs to calculate intervertebral kinematics and preoperative disc height. Patient age, sex, BMI, smoking, diabetes, psychiatric history, inciting event, length of symptoms, preoperative disc bulge, and NDI were collected. Multivariate linear regression identified patient factors associated with changes in adjacent segment kinematics and NDI 3YR-POST.

Results: 62 patients completed testing. Younger age (1.1° per 10 years, 95% CI [0.04, 1.8], P=0.011), female sex (1.8°, 95% CI [0.5, 3.1], P=0.016), lower BMI (1.4° per 10 kg/m², 95% CI [0.4, 2.5], P=0.019), and no superior adjacent disc bulge (1.4°, 95% CI [0.0, 2.7], P=0.035) predicted larger increase in superior adjacent segment flexion/extension range of motion (ROM) 3YR-POST. Lack of superior adjacent disc bulge (1.2°, 95% CI [0.2, 2.2], P=0.025) predicted larger increase in superior adjacent segment axial rotation ROM. No patient factors were associated with changes in inferior adjacent segment ROM.

Conclusion: Greater increase in superior adjacent segment motion 3YR-POST is predicted in younger, lower BMI, female patients with healthier preoperative discs. These results support the theory that disc degeneration progresses from early instability in younger, healthier discs to stabilization in older, less healthy discs.

Study design/setting: Retrospective study at a single academic tertiary care center.

Objective: To evaluate osseous and vascular structures at C1 on preoperative MRIs and CTAs.

Background data: No prior studies have compared the diagnostic accuracy between magnetic resonance imaging (MRI) and computed tomography angiography (CTA) to assess C1 and internal carotid artery (ICA) anatomy prior to surgical instrumentation.

Methods: We retrospectively reviewed adult patients who underwent both cervical spine CTA and MRI between 2007 and 2018. Patients with prior cervical surgery or MRIs not extending to the atlas were excluded. Ten standardized osseous and vascular measurements were performed on both modalities using anatomical landmarks at C1. Paired t-tests and intraclass correlation coefficients (ICCs) assessed differences and agreement. A sub-analysis normalized measurements to anterior-posterior C1 length to account for potential modality-based scaling differences.

Results: Of 209 patients reviewed, 119 met inclusion criteria (mean age 65.1 years; 56% female). The agreement between CTA and MRI across 10 anatomical measurements was low, with ICCs ranging from 0.006 to 0.427. All measurements except the distance from the end of the ideal screw trajectory to the anterior plane of C1 demonstrated statistically significant differences between CTA and MRI (P<0.05). After standardizing values to anterior-posterior C1 length, ICCs for the nine measurements remained low (0.012 to 0.305), with only standardized measurements, distance from the end of the ideal screw trajectory to the anterior plane of C1 and the distance from the origin of the ideal screw trajectory to the ICA showing no statistically significant differences.

Conclusions: This study evaluated the accuracy of preoperative CTA and MRI in assessing C1 and ICA anatomy for atlantoaxial fusion planning, revealing variability in measurement agreement between the two. The findings highlight the need to tailor imaging choices to each clinical scenario, balancing diagnostic value, radiation exposure and surgical risk.

Study design: Experimental animal study using a rabbit model of chronic cervical spinal cord compression.

Objective: To investigate the relationship between MRI T2-weighted signal intensity changes in the spinal cord and underlying apoptotic and neuroinflammatory mechanisms in chronic cervical spinal cord compression.

Summary of background data: T2-weighted MRI hyperintensity in degenerative cervical myelopathy (DCM) patients is commonly observed, but its pathological significance remains incompletely understood. Apoptosis and neuroinflammation are key pathophysiological mechanisms, yet their correlation with MRI signal changes lacks systematic investigation.

Methods: Twenty-four rabbits were randomized into control, mild compression, and severe compression groups (n=8/group). Chronic cervical spinal cord compression was induced at C3 using radiopaque resin pins. Motor function (Tarlov scores, Rivlin inclined plane test), somatosensory evoked potentials (SEPs), and MRI signal intensity ratios (SCR) were assessed at 1 week, 3 months, and 6 months. At 6 months, spinal cord tissues were analyzed via hematoxylin-eosin staining, TUNEL assay, immunofluorescence, and Western blotting for apoptotic (Bax, Bcl-2, Caspase-3) and neuroinflammatory markers (NLRP3, ASC, NF-κB).

Results: Compression severity correlated with functional decline and prolonged SEP latency (P<0.05). At 6 months, SCR was significantly elevated in severe compression group (1.16 vs. 1.00 in controls, P<0.001). TUNEL-positive cells increased proportionally with compression severity (3.2±0.8% control vs. 19.8±2.4% severe compression, P<0.001). Bax/Bcl-2 ratio and NLRP3 expression escalated with compression intensity. Spearman analysis revealed strong positive correlations between SCR and both Bax/Bcl-2 ratio (rs=0.817, P<0.001) and NLRP3 expression (rs=0.849, P<0.001).

Conclusions: In chronic cervical spinal cord compression, MRI T2 hyperintensity correlates significantly with the severity of neuronal apoptosis and NLRP3-mediated neuroinflammation, suggesting that SCR may serve as a quantitative imaging biomarker for underlying pathological changes in DCM.

Study design: Survey-based, prospective study.

Objective: To establish a baseline range of SRS-22r, analyzing the impact of age and sex within the American population.

Summary of background data: The Scoliosis Research Society-22r (SRS-22r) is a widely used PROM for evaluating satisfaction and quality of life in adult spinal deformity. However, normative age-stratified data, especially for adults over 80, remain limited. Establishing population-based SRS-22r values is essential for contextualizing outcomes and guiding treatment strategies.

Methods: A total of 658 participants were recruited in January 2025 through the Connect platform (CloudResearch) to complete a RedCap survey containing six demographic questions and the full SRS-22r. We targeted about 100 participants per decade and grouped them into four age cohorts: 18-39, 40-59, 60-79, and 80-89 years. Racial targets reflected U.S. Census distributions.

Results: Of 658 participants, 599 remained after exclusions for prior surgery and incomplete data. Of these, 301 (50.2%) were female with a mean BMI of 26.7±6.2. The mean SRS-22r Total score was 3.9±0.7, with domain scores of Function 4.1±0.8, Pain 3.9±0.8, Self-Image 3.7±0.8, and Mental Health 3.7±0.9. ANOVA showed a U-shaped age effect, with the 18-39 and 80+ groups reporting higher scores across most domains (P<.01). Females had lower scores on all domains (P<.01). BMI correlated negatively with Total (r=-0.24), Self-Image (r=-0.34), and Function (r=-0.23) (all P<.001).

Conclusion: Baseline SRS-22r scores in U.S. adults are strongly shaped by age, sex, and BMI. Scores follow a clear U-shaped pattern, with the youngest and oldest adults reporting the best health, while higher BMI and female sex consistently predict lower scores. These benchmarks provide essential context for interpreting SRS-22r scores in adult spinal deformity.

Study design: Retrospective cohort study of patients undergoing single-level L5-S1 anterior or transforaminal lumbar interbody fusion between 2012 and 2024 at a single academic institution, with preoperative and one-year postoperative radiographic assessment of sagittal alignment parameters.

Objective: To quantify changes in lumbar pelvic angle (LPA), pelvic tilt (PT), global lumbar lordosis (L1-S1), regional lumbar lordosis (L4-S1), and segmental lumbar lordosis (L5-S1) among single-level L5-S1 ALIF and TLIF patients.

Summary of background data: Restoration of sagittal alignment is a primary goal of lumbar fusion. While ALIF is regarded as superior to TLIF in restoring segmental lordosis, its effect on global and regional alignment remains uncertain, and few studies directly compare their impact on spinopelvic parameters.

Methods: The electronic medical record was queried for patients who underwent single-level L5-S1 ALIF or TLIF with preoperative and one-year postoperative imaging. Sagittal parameters were measured using Surgimap software. Group comparisons were assessed with unpaired t-tests or Wilcoxon signed-rank tests.

Results: Radiographic measurements were available for 174 patients (ALIF n=73, TLIF n=101). ALIF patients had significantly greater improvement in L4-S1 (+4.2° vs. -1.1°, P=0.002) and L5-S1 lordosis (+4.6° vs. -4.8°, P<0.001). No significant differences were observed in postoperative changes for L1-S1 lordosis (+2.2° vs. -1.4°, P=0.250), LPA (-1.9° vs. -1.4°, P=0.743), or PT (-0.9° vs. +0.4°, P=0.093). Permutation testing confirmed that the observed difference in LPA improvement between cohorts (-0.51°) was not statistically significant (P=0.673), and post hoc analysis confirmed adequate power to detect a difference of 3.37°. Sensitivity analyses using ANCOVA, adjusting for baseline radiographic values and covariates, were concordant.

Conclusion: ALIF provided superior regional and segmental lordosis but did not improve global alignment compared with TLIF. This study is the first to quantify the effect of ALIF versus TLIF on LPA, highlighting the limited impact of single-level fusion on global spinopelvic alignment.