Potes, Maria Astudillo

Abstract Professor Albert J. Rhoton Jr., MD, is renowned for his groundbreaking dissections, marking a monumental achievement in the field of neuroanatomy. Alongside his anatomical contributions, he also passed on his knowledge and skills to numerous fellows, leaving behind a profound legacy. Despite the widespread recognition of his influence, little quantitative work has been done to characterize the scholarly impact of his alumni. Data were collected on Rhoton fellows, including fellowship years, country of origin, current institutions, and titles, practice settings, and leadership roles. Scholarly productivity was evaluated by assessing publication counts, including publications before and after the fellowship, and publications focused on surgical anatomy. Additionally, H-indices and citation counts were recorded. Other variables analyzed included ownership of a surgical anatomy laboratory, and participation in organizing hands-on courses. We analyzed 118 alumni from diverse countries. There was a significant increase in publication output following the fellowship, with publications rising from an average of 7 to 76 (p < 0.001). Fellows from high-income countries had higher research productivity than those from middle-income countries, with greater average H-index (p = 0.003), publication count (p = 0.01), and citation score (p = 0.003). Overall, 65% of fellows pursued academic practice, with 18% owning a laboratory and 30% involved in hands-on courses. Dr. Rhoton's mentorship has shaped a generation of neurosurgeons who continue his legacy. His fellows have established careers worldwide, leading in academia, professional organizations, and surgical training. Their global impact underscores the lasting value of structured mentorship in neurosurgery.

OBJECTIVE Pelvic incidence (PI) is a key parameter of sagittal alignment. While conventionally held to be fixed, increasing evidence suggests PI may be variable. This study aimed to identify predictors of change in PI with patient position and to assess the association of preoperative radiographic characteristics and intraoperative maneuvers with postoperative PI. METHODS Patients who underwent thoracolumbosacral fusion were identified, and data were gathered on preoperative spinopelvic parameters, patient demographic characteristics, and operative details. Preoperative spinopelvic parameters were measured on upright, supine, and prone radiographs. Univariable comparisons of PI between the different patient positions were performed. Multivariable analysis was performed to identify variables independently correlated with PI on 6-week postoperative radiographs. Change in PI was defined as ≥ 5° change between positions. RESULTS In total, 138 patients were identified (mean ± SD age 66.0 ± 8.7 years; 38.4% male). Statistically significant differences in PI were noted between preoperative standing and supine (mean −3.2° ± 4.2°, p < 0.001), preoperative supine and prone (3.5° ± 4.7°, p < 0.001), preoperative and 6-week postoperative standing (1.5° ± 6.2°, p = 0.01), and immediate and 6-week upright (1.1° ± 3.9°, p = 0.007) radiographs. Univariable comparisons showed PI decrease from standing to supine was predicted only by weight (87.0 ± 15.0 vs 81.1 ± 19.3 kg, p = 0.04); there were no significant predictors of increase in PI from standing to prone. Increase in PI from preoperative to 6-week standing radiographs was predicted by lower preoperative PI class (p < 0.001), L5/S1 interbody placement (74.4% vs 52.0%, p = 0.02), and change in PI from preoperative standing to supine (12.8% vs 39.8%, p = 0.002) and from standing to prone (51.3% vs 13.3%, p < 0.001). Multivariable analysis showed that 6-week postoperative PI was associated with only preoperative supine PI (B = 0.293, 95% CI 0.10–0.48, p = 0.003) and prone PI (B = 0.647, 95% CI 0.44–0.85, p < 0.001). CONCLUSIONS There are position-dependent changes in PI among patients without prior pelvic fixation. Statistically significant changes in PI are seen even after pelvic fixation with a single S2-alar-iliac screw bilaterally. Postoperative PI was best predicted by preoperative PI on supine and prone radiographs rather than upright radiographs, suggesting that preoperative prone and supine radiographs may provide surgeons with the best information for achieving PI–lumbar lordosis mismatch < 10°.

OBJECTIVE Transforaminal lumbar interbody fusion (TLIF) offers both indirect decompression and segmental correction through restoration of disc height. However, stresses exerted on the vertebral endplates by the interbody device can result in implant subsidence and loss of correction. The present time-to-event analysis aimed to identify predictors of interbody subsidence. METHODS Patients who underwent 1- or 2-level TLIF were identified. Data on demographics, surgical details, preoperative bone quality using CT-based Hounsfield units (HU), and pre- and postoperative lumbopelvic parameters were collected. Univariable analyses were conducted to identify predictors of subsidence (≥ 2-mm intrusion of interbody into cranial or caudal vertebrae) and significant subsidence (≥ 4-mm intrusion). Multivariable Cox regression was performed to identify independent predictors of subsidence, expressed as hazard ratios with 95% confidence intervals. RESULTS A total of 198 patients treated at 241 levels were included (median age 66.6 years, IQR 59.5, 73.7 years; 56.6% were women). In 92 levels (38.2%) there was some subsidence and in 25 (10.4%) there was significant subsidence. Implanted levels demonstrating subsidence (≥ 2 mm) were associated with lower HU in cranial and caudal vertebrae; had interbodies positioned farther from the anterior apophyseal ring; were implanted with taller, more lordotic interbodies; and underwent greater disc height restoration. Those showing significant subsidence (≥ 4 mm) were similarly associated with lower HU in the cranial and caudal vertebrae; had interbodies positioned farther from the anterior apophyseal ring of the caudal vertebrae; and underwent greater disc height restoration. Multivariable Cox regression showed that time to subsidence was predicted by greater implant height (HR 1.20/mm, 95% CI 1.05–1.38; p = 0.009), greater postoperative disc height (HR 1.21/mm, 95% CI 1.09–1.34; p < 0.001), and greater disc height restoration (HR 1.11/mm, 95% CI 1.04–1.19; p = 0.002). The time-to-subsidence analysis for significant (≥ 4 mm) subsidence showed that it was predicted by lower HU in the cranial vertebrae (HR 0.98/unit, 95% CI 0.97–0.99; p = 0.001); increasing number of levels instrumented (HR 1.26, 95% CI 1.04–1.52; p = 0.016); and greater disc height restoration (HR 1.33/mm, 95% CI 1.18–1.51; p < 0.001). CONCLUSIONS This time-to-event analysis suggests that interbody subsidence following TLIF is best predicted by implantation of a taller interbody and aggressive disc height restoration. Significant subsidence is similarly predicted by aggressive disc height restoration along with poor baseline bone quality. The results suggest the need to balance aggressive correction at the time of surgery against the increased risk of subsequent interbody subsidence.

Introduction: Bone health optimization is a key component of the preoperative management of spine surgery patients, as poor bone quality increases the odds of mechanical complications. The present study aimed to achieve the following: (1) compare the relative efficacy of current osteoporosis medications in improving bone quality; (2) identify factors influencing treatment response in preoperative spine surgery patients. Methods: Patients treated at a single, multisite institution who received osteoporosis treatment were identified. Data were gathered on pre- and post-treatment lumbar spine Hounsfield Unit (HU) measurements, patient demographics, frailty scores (modified Frailty Index/mFI, risk analysis index/RAI), and pharmacologic treatment details. The primary outcome was a ≥7 point improvement in lumbar HU, and baseline and logistic regression models were utilized to identify factors associated with this improvement. Medications were grouped as anabolic (teriparatide, romosozumab) and antiresorptive (denosumab, alendronate) therapies. Results: A total of 267 patients were included (median age: 74 years; IQR [66–81]; 67.3% female), with 127 (47.6%) improving by ≥7 HU. The treatment agents used were alendronate (95), denosumab (113), romosozumab (31), and teriparatide (28). Univariable comparisons revealed significant differences across medication groups in age (p < 0.001), sex (p < 0.001), mFI (p < 0.001), RAI (p = 0.004), BMI (p < 0.001), pre-treatment HU (p = 0.022), and treatment duration (p < 0.001). The highest HU improvement rates (ΔHU ≥ 7) were observed in patients receiving the anabolic medications romosozumab (67.7%) and teriparatide (60.7%). Univariable logistic regression identified male sex (OR 0.54, p = 0.019), higher pre-treatment HU (OR 0.99, p = 0.006), and longer treatment duration (OR 0.97, p = 0.003) as factors associated with lower odds of HU improvement. Only romosozumab was associated with significantly higher odds of HU improvement relative to alendronate (OR 3.02, p = 0.012). In our multivariable analysis, male sex (OR 0.53, p = 0.028) and higher pre-treatment HU (OR 0.99, p = 0.002) remained significant predictors of HU improvement. However, medication type was not significant in the multivariable analysis. Conclusions: Our study highlights that male sex and higher pre-treatment HU were independently associated with lower odds of HU improvement, while medication type was not a significant predictor. Additionally, anabolic agents offered superior improvement relative to antiresorptive therapies.

Abstract Aging‐related bone loss significantly impacts the growing elderly population globally, leading to debilitating conditions such as osteoporosis. Senescent osteocytes play a crucial role in the aging process of bone. This longitudinal study examines the impact of continuous local and paracrine exposure to senescence‐associated secretory phenotype (SASP) factors on biophysical and biomolecular markers in osteocytes. Significant cytoskeletal stiffening in irradiated (IR) osteocytes are found, accompanied by expansion of F‐actin areas and a decline in dendritic integrity. These changes, correlating with alterations in pro‐inflammatory cytokine levels and osteocyte‐specific gene expression, support the reliability of biophysical markers for identifying senescent osteocytes. Notably, local accumulation of SASP factors have a more pronounced impact on osteocyte biophysical properties than paracrine effects, suggesting that the interplay between local and paracrine exposure can substantially influence cellular aging. This study underscores the importance of osteocyte mechanical and morphological properties as biophysical markers of senescence, highlighting their time dependence and differential effects of local and paracrine SASP exposure. Collectively, the investigation into biophysical senescence markers offers unique and reliable functional hallmarks for the non‐invasive identification of senescent osteocytes, providing insights that can inform therapeutic strategies to mitigate aging‐related bone loss.

BACKGROUND AND OBJECTIVES: Transforaminal lumbar interbody fusion (TLIF) allows for direct and indirect decompression and segmental lordosis in sagittal plane correction. This study compares the effectiveness of “Bullet” type and “Banana” type devices for sagittal plane correction. METHODS: Patients who underwent 1-level or 2-level TLIF for degenerative pathology at a single tertiary care center were identified. Details were extracted on demographics, interbody dimensions, and preoperative and postoperative lumbopelvic parameters from upright radiographs. Cages were categorized as “Bullet” or “Banana” type based on morphology and manufacturer description of optimal position. Univariable comparisons between levels treated with “Bullet” and “Banana” type interbodies were performed. Multivariable linear regression was performed to identify independent predictors of postoperative segmental lordosis and change in segmental lordosis. RESULTS: One hundred and ninety eight unique patients (median 66.6 years; [IQR 59.5, 73.7]; 56.6% female) were included with 241 levels treated, of which 114 (52.7%) were treated with “Banana” type interbodies and 127 (47.3%) with “Bullet” type. “Banana” type interbodies afforded both greater postoperative segmental lordosis (8.1 [6.2, 10.7] vs 7.5 [5.2, 9.6]; P = .048) and greater increase in segmental lordosis (3.3 [0.7, 7.0] vs 2.3 [0.1, 4.2]; P = .015). On multivariable linear regression, only preoperative segmental lordosis (β = 0.322 per degree; [0.244, 0.399]; P < .001), implant listed lordosis (β = 0.146 per degree; 95% CI [0.048, 0.244]; P = .004), preoperative pelvic incidence (0.072 per degree; [0.034, 0.111]; P < .001), and use of bilateral TLIF windows (β = 3.133; [1.213, 5.053]; P = .001) were predictive of postoperative segmental lordosis. CONCLUSION: The present analysis suggests that baseline lumbopelvic anatomy, interbody lordosis, and the use of bilateral TLIF windows are the most important predictors of postoperative segmental lordosis. Use of “Banana” vs “Bullet” type interbodies was not predictive of segmental lordosis achieved on immediate postoperative upright radiographs. Further work is merited to determine whether the 2 interbody types demonstrate differences regarding subsidence risk or maintenance of correction.

Background/Objectives: Both poor bone quality and paraspinal sarcopenia have been suggested as risk factors for proximal junctional kyphosis (PJK) at the upper instrumented vertebra (UIV) following long-segment thoracolumbar fusion. Methods: Adults ≥50 with a T1-6 UIV were identified, and data were gathered on pre- and postoperative spinopelvic parameters, bone quality (using Hounsfield units and vertebral bone quality score), and paraspinal cross-sectional area at L3 and the UIV. PJK was defined by a ≥10° increase in the proximal junctional angle. Cox regressions were performed to identify PJK risk factors; PJK was subdivided into types 1–3 based on the Yagi–Boachie classification. Results: In total, 15/76 patients (median age 66; 72.4% female) experienced PJK; 10 experienced type 1, 4 experienced type 2, and one experienced type 3. Univariable Cox regression showed that PJK was negatively correlated with total paraspinal muscle CSA at the UIV (HR 0.74/100 mm2; 95% CI [0.57, 0.6]; p = 0.02). Lower total paraspinal CSA at L3 (HR 0.94/100 mm2; p = 0.07) and higher postoperative global tilt (HR 1.03; p = 0.09) also trended toward significance. Similarly, type 1 PJK was predicted by smaller total paraspinal CSA at the UIV (HR 0.64/100 mm2; [0.45, 0.92]; p = 0.02). Paraspinal CSA was not predictive of type 2 PJK, but lower HU at the UIV and UIV + 1 trended toward significance (HR 0.98/unit; p = 0.16). A comparison of type 1 and 2 PJK showed a higher average of paraspinal CSA and a lower average of HU at the UIV. Conclusions: Global alignment and paraspinal sarcopenia were most predictive of PJK, though paraspinal sarcopenia was only predictive of type 1. Type 2 may be better predicted by bone quality.

OBJECTIVE Hounsfield units (HUs) may better predict biomechanical complications of instrumented fusion than conventional bone quality measures. Typically, noncontrast axial slices are used. This study aims to address the influence of reconstruction plane and contrast administration on measured HUs in patients undergoing lumbar spine imaging. METHODS Patients without prior spine surgery, infection, or tumor were identified for 3 groups: 1) 150 patients with high-resolution noncontrast lumbar CT, 2) 109 patients with noncontrast and contrast-enhanced lumbar CT, and 3) 100 patients with noncontrast lumbar CT and lumbar CT myelograms. Noncontrast HU measures in group 1 were compared between axial, sagittal, and coronal reconstructions. HU measures for groups 2 and 3 were compared on axial slice averages. HU measures between groups were compared using the Wilcoxon signed-rank test to investigate the presence of a statistically significant difference between groups (α = 0.05). Linear regression was also used to determine the degree of correlation between HU measures on noncontrast axial CT slices and HU measures on other sequences. RESULTS The mean patient age was 58.8 ± 15.9 years for group 1 (54.0% male), 65.5 ± 15.9 years for group 2 (61.5% male), and 65.2 ± 14.2 years (53.5% male) for group 3. Comparison of HU measures in group 1 showed significant differences across measurement modalities with the exception of axial average versus coronal average measures (p = 0.257) and sagittal average versus midsagittal measures (p = 0.726). There were significant differences in average axial HUs for each vertebral body between contrast and noncontrast lumbar CT and between CT myelography and noncontrast CT. Linear regression analysis demonstrated an extremely high correlation between measures for all methodologies (r2 = 0.950–0.986, all p < 0.001), and between contrast-enhanced and noncontrast studies (r2 = 0.870, p < 0.001). Measurements on CT myelography were significantly correlated with those in noncontrast studies, although to a lesser degree (r2 = 0.745, p < 0.001). CONCLUSIONS HU measures on noncontrast CT appear similar across multiple different planes, suggesting that a simpler methodology such as single-slice measurement on midsagittal reconstruction may allow for more rapid assessment of underlying bone quality. Consistent with prior work, contrast-enhanced CT sequences appear to reliably mirror underlying bone quality, although CT myelogram measures may vary in a more unpredictable way that precludes their use to interpret underlying bone quality. HU measures on contrast-enhanced studies are on average greater, suggesting the need for higher cutoff values.

Abstract Senescent osteocytes are key contributors to age‐related bone loss and fragility; however, the impact of mechanobiological changes in these cells remains poorly understood. This study provides a novel analysis of these changes in primary osteocytes following irradiation‐induced senescence. By integrating subcellular mechanical measurements with gene expression analyses, we identified significant, time‐dependent alterations in the mechanical properties of senescent bone cells. Increases in classical markers such as SA‐β‐Gal activity and p16 Ink4a expression levels confirmed the senescence status post‐irradiation. Our key findings include a time‐dependent increase in cytoskeletal Young's modulus and altered viscoelastic properties of the plasma membrane, affecting the contractility of primary osteocytes. Additionally, we observed a significant increase in Sclerostin ( Sost ) expression 21 days post‐irradiation. These biophysical changes may impair osteocyte mechanosensation and mechanotransduction, contributing to bone fragility. This is the first study to time‐map senescence‐associated mechanical changes in the osteocyte cytoskeleton. Our findings highlight the potential of biophysical markers as indicators of cellular senescence, providing more specificity than traditional, variable biomolecular markers. We believe these results may support biomechanical stimulation as a potential therapeutic strategy to rejuvenate aging osteocytes and enhance bone health.