Different Risk Factors between Bony and Ligamentous Proximal Junctional Failure in Patients Undergoing Thoracolumbar Fusion to Pelvis for Adult Spinal Deformity.

STUDY DESIGN: Retrospective study. OBJECTIVE: To analyze the risk factors for bony proximal junctional failure (B-PJF) and ligamentous PJF (L-PJF) separately after adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND DATA: Despite numerous studies about the risk factors of PJF, it remains unclear whether same risk factors can be applied to both B-PJF and L-PJF. METHODS: Patients who underwent corrective surgery from low thoracic level (T9-T12) to pelvis with minimum follow-up duration of two years were included in this study. Patients with PJF were divided into two groups according to the involvement of bony structure: B-PJF and L-PJF. The control group was created using patients who did not develop PJF for ≥2 years postoperatively (no-PJF group). Risk factors were analyzed by comparing various clinical and radiographic parameters between no PJF versus B-PJF group and between no PJF versus L-PJF groups. RESULTS: The final study cohort comprised 240 patients. The mean age was 68.7 years, and there were 205 women (85.4%). On average, 8.1 levels were fused. PJF developed in 103 patients, with 70 (68.0%) in the B-PJF group and 33 (32.0%) in the L-PJF group. Stepwise logistic regression analyses revealed that older age (odds ratio [OR]=1.088), higher body mass index (BMI) (OR=1.161), osteoporosis (OR=3.293), greater postoperative lumbar distribution index (OR=1.032), and overcorrection relative to the age-adjusted pelvic incidence - lumbar lordosis (OR=3.964) were significant risk factors for B-PJF. Meanwhile, no use of transverse process (TP) hook was the single risk factor for L-PJF (OR=4.724). CONCLUSIONS: Understanding the difference in risk factors between B-PJF and L-PJF will facilitate the optimization of surgical outcome for patients with ASD. Appropriate correction of sagittal malalignment along with use of TP hook is advisable to mitigate both B-PJF and L-PJF development.

Validation of Sagittal age-adjusted Score in Predicting Proximal Junctional Kyphosis/Failure and Clinical Outcomes Following Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective study. OBJECTIVES: To validate the sagittal age-adjusted score (SAAS) in predicting proximal junctional kyphosis/failure (PJK/F) and good clinical outcomes following adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND DATA: SAAS is a relatively new assessment system that incorporates age-adjusted sagittal parameters of pelvic incidence (PI) - lumbar lordosis (LL), pelvic tilt (PT), and T1 pelvic angle (TPA) to predict the PJK/F. External validation is required to verify its clinical usefulness. METHODS: We included patients with ASD undergoing ≥5-level fusion including the sacrum or pelvis. SAAS was calculated based on the scores of the three components: PI-LL, PT, and TPA. PJK/F rates and clinical outcomes were compared among the correction categories (undercorrection, matched correction, and overcorrection) for the SAAS as well as for each of the three components. PJK/F rates were compared according to the correction groups of the sagittal components and total SAAS using the chi-square test. Receiver operating characteristic (ROC) analysis was performed to evaluate the predictive ability of overcorrection to develop PJK/F for the three sagittal parameters and SAAS. PROMs at final follow-up were compared among correction groups using ANOVA with Bonferroni post-hoc corrections. RESULTS: A total 411 patients were included in the study (mean age: 69.3 y, mean body mass index: 25.9 kg/m2, total levels fused: 7.7 levels, and follow-up duration: 43.3 mo). Postoperative SAAS categories were as follow: undercorrection (13.4%), matched correction (30.2%), and overcorrection (56.4%). The PJK/F rates were significantly higher in the overcorrection group relative to PI-LL component (P=0.001) as well as SAAS (P=0.038) compared to undercorrection or matched correction groups. The clinical outcomes were best in patients who achieved matched correction relative to PI-LL component as well as SAAS compared to the other correction groups. However, the differentiating power of clinical outcomes across the correction categories was greater in the PI-LL component than in the SAAS. CONCLUSION: This study validated the efficacy of SAAS system to differentiate PJK/F development and good clinical outcomes. However, its differentiating power seems to be largely attributable to the function of the PI-LL component, as the PI-LL correction status better predicted PJK/F risk and clinical outcomes than SAAS.

Incidence and Risk Factors for Mechanical Failure after Anterior Column Realignment in Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective study. OBJECTIVES: To investigate the incidence and risk factors of mechanical failure (MF) following anterior column realignment (ACR) in patients with severe degenerative sagittal imbalance (DSI). SUMMARY OF BACKGROUND DATA: Considering the biomechanical properties of the procedure, ACR may increase the risk of MF, including proximal junctional kyphosis (PJK) and rod fracture (RF). However, this issue has been poorly documented in the literature. METHODS: We included patients aged ≥60 years with severe DSI radiographically defined by pelvic incidence (PI) - lumbar lordosis (LL) ≥20° undergoing ≥5-level fusion, including the sacrum. PJK was defined radiographically as a proximal junctional angle (PJA)>28° plus Δ PJA of>22°. RF was evaluated at ACR levels performed. Clinical and radiographic variables were compared to identify the risk factors for PJK and RF, then multivariate analysis was performed by combining PJK and RF into a single composite outcome of MF. RESULTS: We included a total of 147 patients in the final study cohort. The mean age was 70.3 years, and there were 126 women (90.6%). The median fusion length was 8 levels. After surgery, PI-LL was corrected from 48.1° to 4.3°. MF developed in 49 patients (33.3%); PJK in 41 (27.9%), RF in 11 (7.5%), and both PJK and RF in 3 (2.0%) patients. Multivariate analyses revealed that osteoporosis (odds ratio [OR]=2.361, 95% confidence interval [CI]=1.270 - 5.590, P=0.048) and an increased number of ACR levels (OR=1.762, 95% CI=1.039 - 3.587, P=0.036) were significant risk factors for MF. CONCLUSION: A considerable number of patients (33.3%) developed MF after deformity correction using ACR procedures. Therefore, appropriate surgical strategies are necessary to prevent MF in patients undergoing deformity correction using ACR, with special attention to the risk factors we identified here.

Risk Factors for Recurrent Proximal Junctional Failure Following Adult Spinal Deformity Surgery: Analysis of 60 Patients Undergoing Fusion Extension Surgery for Proximal Junctional Failure.

BACKGROUND: Despite numerous studies identifying risk factors for proximal junctional failure (PJF), risk factors for recurrent PJF (R-PJF) are still not well established. Therefore, we aimed to identify the risk factors for R-PJF following adult spinal deformity (ASD) surgery. METHODS: Among 479 patients who underwent ≥5-level fusion surgery for ASD, the focus was on those who experienced R-PJF at any time or did not experience R-PJF during a follow-up duration of ≥1 year. PJF was defined as a proximal junctional angle (PJA) ≥28° plus a difference in PJA ≥22° or performance of revision surgery regardless of PJA degree. The patients were divided into 2 groups according to R-PJF development: no R-PJF and R-PJF groups. Risk factors were evaluated focusing on patient, surgical, and radiographic factors at the index surgery as well as at the revision surgery. RESULTS: Of the 60 patients in the final study cohort, 24 (40%) experienced R-PJF. Significant risk factors included greater postoperative sagittal vertical axis (OR = 1.044), overcorrection relative to age-adjusted pelvic incidence-lumbar lordosis (PI-LL; OR = 7.794) at the index surgery, a greater total sum of the proximal junctional kyphosis severity scale (OR = 1.145), and no use of the upper instrumented vertebra cement (OR = 5.494) at the revision surgery. CONCLUSIONS: We revealed that the greater postoperative sagittal vertical axis and overcorrection relative to age-adjusted pelvic incidence-lumbar lordosis at the index surgery, a greater proximal junctional kyphosis severity scale score, and no use of upper instrumented vertebra cement at the revision surgery were significant risk factors for R-PJF. CLINICAL RELEVANCE: To reduce the risk of R-PJF after ASD surgery, avoiding under- and overcorrection during the initial surgery is recommended. Additionally, close assessment of the severity of PJF with timely intervention is crucial, and cement augmentation should be considered during revision surgery.

Different characteristics between acute and delayed proximal junctional failure in elderly patients undergoing corrective surgery for adult spinal deformity: comparative analysis of risk factor, failure mode, and clinical consequences.

BACKGROUND CONTEXT: While numerous studies have been conducted on proximal junctional failure (PJF), the clinical significance of acute and delayed PJF remains poorly understood. PURPOSE: The primary object of this study is to investigate the risk factors separately for acute and delayed PJF. Secondly, we aim to assess the incidence of each failure mode and their clinical consequences in relation to acute and delayed PJF. STUDY DESIGN/SETTING: Retrospective comparative study. PATIENT SAMPLE: Patients aged ≥60 years who underwent deformity correction with ≥5-level fusion to sacrum. OUTCOME MEASURES: Risk factor, failure modes, and patient-reported outcome measure (PROM). METHODS: Acute PJF is defined as PJF occurring within 6 months, while delayed PJF occurring after 6 months. Risk factors were analyzed by comparing various clinical and radiographic parameters among 3 groups: no, acute, and delayed PJF groups. The failure modes, including soft tissue failure, vertebral fracture, fixation failure, and myelopathy, were compared among these groups. The clinical subsequences after PJF development were evaluated by assessing the change in proximal junctional angle (PJA), revision rate, and patient-reported outcome measure (PROM). RESULTS: A study cohort of 363 patients was included in the analysis. Among them, 156 patients experienced PJF, with 87 patients (55.8%) in the acute PJF group and 69 patients (44.2%) in the delayed PJF group. Multivariate analyses showed that older age (Odds ratio [OR] = 1.057, 95% confidence interval [CI] = 1.002-1.118), osteoporosis (OR=2.149, 95% CI = 1.074-4.300), high American Society of Anesthesiology ASA score (OR=2.150, 95% CI = 1.089-4.245), and overcorrection relative to the age-adjusted pelvic incidence - lumbar lordosis target (OR=4.031, 95% CI = 1.962-8.280) were identified as risk factors for the development of acute PJF. On the other hand, a high body mass index (OR=1.150, 95% CI = 1.049-1.251) and an uppermost instrumented vertebra located at ≤T10 (OR=2.267, 95% CI = 1.205-4.268) were found to be associated with delayed occurrence of PJF. No radiographic parameters were found to be related to the development of delayed PJF. In terms of failure modes, vertebral fracture and fixation failure were more commonly observed in acute PJF, while soft tissue failure and myelopathy were more predominant in delayed PJF. The clinical course was more aggressive in the acute PJF group compared to the delayed PJF group, as evidenced by a greater increase in PJA, a higher revision rate, and worse PROM. CONCLUSIONS: This study demonstrated different risk factors between the acute and delayed PJF. It was found that overcorrection relative to the age-adjusted PI-LL target increased the risk of acute PJF, but had no impact on the development of delayed PJF. Therefore, a different surgical strategy needs to be established to mitigate both acute and delayed PJF.

Surgical Interventions Following Radiotherapy in Spinal Metastases with Intermediate Instability: A Risk Factor Analysis: The Korean Society of Spinal Tumor Multicenter Study (KSST 2022-02).

BACKGROUND: One important determinant in choosing a treatment modality is spinal instability. Clear management guidelines are suggested for stable and unstable spinal metastatic lesions, but lesions in the intermediate instability category (SINS [spinal instability neoplastic score] score of 7-12) remain a clinical dilemma. This study aims to analyze the risk factors necessitating surgical intervention after radiotherapy (RT) in patients with those lesions. METHODS: A multicenter cohort of 469 patients with spinal metastases of intermediate instability who received radiotherapy (RT) as the initial treatment between 2019 and 2021 were retrospectively enrolled. All patients were neurologically intact at the time of RT. According to the performance of surgical intervention after RT, various clinical and radiographic risk factors for surgical intervention were compared between surgery and non-surgery groups using uni- and multivariate analyses. A recursive partitioning analysis (RPA) was performed using significant determinants identified in multivariate analysis. RESULTS: The mean age at the time of RT was 59.9 years and there were 198 females. The lung was the most common primary site. During the mean follow-up duration of 18.2 months, surgical treatment was required in 79 (17.9%) of patients. The most common surgical method was decompressive laminectomy with stabilization (62.0%), followed by vertebrectomy with stabilization (22.8%) and stabilization only (15.2%). The mean SINS for the total cohort was 9.0. Multivariate regression analyses revealed that the primary tumor site of the lung, liver, and kidney, higher Bilsky grades of ESCC, lytic bone lesions, and higher EQD210 were significant risk factors for surgical intervention after RT. Among them, Bilsky grade, primary tumor type of the lung, liver, and kidney, and EQD210 were the most important determinants for expecting the probability of surgical intervention on RPA. CONCLUSIONS: Surgical intervention was performed in 17.9% of patients with intermediate instability after RT as the initial treatment. The primary tumor site of the lung, liver, and kidney, higher Bilsky grade of ESCC, and EQD210 were the most important determinants for expecting the probability of surgical intervention. Therefore, the optimal treatment strategy needs to be devised by carefully evaluating the risk of surgical intervention.

Are Surgical Outcomes Different According to Baseline Balance Status in Elderly Patients with Degenerative Sagittal Imbalance?

STUDY DESIGN: Retrospective study. OBJECTIVE: We sought to compare surgical outcomes according to baseline balance statuses in elderly patients with degenerative sagittal imbalance (DSI). SUMMARY OF BACKGROUND: Although optimal sagittal correction has been emphasized for good surgical outcomes, the effect of the state of preoperative balance on surgical outcome has been adequately described at present. METHODS: Patients aged ≥60 years with DSI who underwent ≥5-level fusion to the sacrum were included. Among them, only those who postoperatively achieved the optimal age-adjusted pelvic incidence (PI) - lumbar lordosis (LL) target were included in this study. Study participants were divided into two groups according to their preoperative sagittal vertical axis (SVA): compensatory balance (SVA <5 cm, group CB) and decompensation (SVA ≥5 cm, group D). Comparisons between the two groups were performed using the chi-squared test or Fisher's exact test for categorical variables and the independent t- test or Wilcoxon rank- sum test for continuous variables. RESULTS: A total of 156 patients whose postoperative sagittal alignment matched the age-adjusted PI-LL target constituted the study cohort. There were 59 patients in group CB and 97 patients in group D. Mean follow-up duration was 50.0 months after surgery. Immediate postoperatively, sacral slope and SVA were significantly greater in group D than in group CB. At last follow-up, the SVA was significantly greater in group D than in group CB (43.6 vs. 22.7 mm), while no significant differences were found in other sagittal parameters. The Oswestry disability index and Scoliosis Research Society -22 scores at the last follow-up were significantly worse in group D than in group CB. CONCLUSION: The SVA tended to experience less correction postoperatively, with evidence of further deterioration during follow-up in group D than in group CB. This suboptimal correction of SVA may contribute to the inferior clinical outcomes encountered in group D relative to group CB. Therefore, we recommend correction of PI-LL as close as possible to the lower limit of the suggested PI-LL target range in patients with evidence of preoperative decompensation.

The Optimal Lowest Instrumented Vertebra to Prevent the Distal Adding-On Phenomenon in Patients Undergoing Selective Thoracic Fusion for Adolescent Idiopathic Scoliosis with Lenke Type 1A and 1B Curves: Comparison of Nine Selection Criteria.

Background/Objectives: There is no solid consensus regarding which lowest instrumented vertebra (LIV) selection criterion is best to prevent distal adding-on (DA) after adolescent idiopathic scoliosis (AIS) surgery. This study aims to search out the LIV selection criteria in the literature and to compare the ability of each LIV selection criterion to prevent DA in patients with AIS. Methods: Patients who underwent thoracic fusion for AIS of Lenke type 1A or 1B were included in this study. Nine criteria for LIV selection were found in a literature review. For each patient, whether the postoperative actual location of LIV was met with the suggested locations of the LIV was assessed. The preventive ability of nine criteria against DA was evaluated using logistic regression analysis. The patients who met the LIV selection criteria but developed DA were investigated. Results: The study cohort consisted of 145 consecutive patients with a mean age of 14.8 years. The criteria of Suk (OR = 0.267), Parisini (OR = 0.230), Wang (OR = 0.289), and Qin (OR = 0.210) showed a significantly decreased risk of DA if the LIV selection criterion was chosen at each suggested landmark. As the additional levels were fused, there was no statistically significant benefit in further reducing the risk of DA. Among the patients who met each criterion, the incidence of DA was lower in criteria by Takahashi (5.9%), Qin (7.1%), and King (7.4%) than the others. Conclusions: Qin's criterion, using the substantially touching vertebra concept, has the highest preventive ability against DA development. Extending the instrumentation further distal to this suggested LIV criterion did not add further benefit.

Predictive Value of Bolster Supine X-Ray for the Correction of Segmental Deformity After Thoracolumbar Fusion Surgery.

BACKGROUND AND OBJECTIVES: Assessment of thoracolumbar spine flexibility is crucial for determining which osteotomy to perform (posterior column osteotomy or 3-column osteotomy) to restore sagittal balance. Although preoperative bolster supine X-rays have been used to evaluate spine flexibility, their correlation with postoperative spinopelvic parameters has not been reported. We aimed to evaluate the predictive value of bolster X-ray for correcting sagittal deformities after thoracolumbar fusion surgery. METHODS: We retrospectively evaluated patients who underwent bolster supine radiography before posterior thoracolumbar fusion. Demographic data, operative records, and radiographic parameters were also recorded. The segmental Cobb angle, defined as the angle between the upper endplate of the uppermost and lower endplates of the lowest instrumented vertebrae, was compared between bolster and postoperative X-ray to evaluate the correlation between them. The predictive value of bolster X-ray for postoperative deformity correction was measured using intraclass correlation coefficients (ICC). RESULTS: Forty-two patients were included. The preoperative segmental Cobb angle (-1.4 ± 22.4) was significantly lower than the bolster segmental Cobb angle (23.2 ± 18.7, P < .001) and postoperative segmental Cobb angle (27.9 ± 22.3, P < .001); however, no significant difference was observed between the bolster and postoperative segmental Cobb angles (P = .746). Bolster X-ray showed a very strong correlation with postoperative X-ray (r = 0.950, P < .001) for segmental Cobb angle. Bolster supine X-ray had good-to-excellent reliability for postoperative X-ray with an ICC of 0.913 (95% CI, 0.760-0.962, P < .001) for the segmental Cobb angle. CONCLUSION: Bolster supine X-rays demonstrate good-to-excellent reliability with postoperative X-rays for segmental Cobb angles. These findings offer valuable insights into the selection of appropriate osteotomy techniques for clinical practice.

Comparison of Surgical Burden, Radiographic and Clinical Outcomes According to the Severity of Baseline Sagittal Imbalance in Adult Spinal Deformity Patients.

OBJECTIVE: To determine the clinical impact of the baseline sagittal imbalance severity in patients with adult spinal deformity (ASD). METHODS: We retrospectively reviewed patients who underwent ≥ 5-level fusion including the pelvis, for ASD with a ≥ 2-year follow-up. Using the Scoliosis Research Society-Schwab classification system, patients were classified into 3 groups according to the severity of the preoperative sagittal imbalance: mild, moderate, and severe. Postoperative clinical and radiographic results were compared among the 3 groups. RESULTS: A total of 259 patients were finally included. There were 42, 62, and 155 patients in the mild, moderate, and severe groups, respectively. The perioperative surgical burden was greatest in the severe group. Postoperatively, this group also showed the largest pelvic incidence minus lumbar lordosis mismatch, suggesting a tendency towards undercorrection. No statistically significant differences were observed in proximal junctional kyphosis, proximal junctional failure, or rod fractures among the groups. Visual analogue scale for back pain and Scoliosis Research Society-22 scores were similar across groups. However, severe group's last follow-up Oswestry Disability Index (ODI) scores significantly lower than those of the severe group. CONCLUSION: Patients with severe sagittal imbalance were treated with more invasive surgical methods along with increased the perioperative surgical burden. All patients exhibited significant radiological and clinical improvements after surgery. However, regarding ODI, the severe group demonstrated slightly worse clinical outcomes than the other groups, probably due to relatively higher proportion of undercorrection. Therefore, more rigorous correction is necessary to achieve optimal sagittal alignment specifically in patients with severe baseline sagittal imbalance.

Hook Fixation at Uppermost Instrumented Vertebra +1 Reduced Proximal Junctional Failure in Adult Patients With Spinal Deformity Having Achieved Optimal Deformity Correction by Sagittal Age-Adjusted Score.

BACKGROUND AND OBJECTIVES: Appropriate correction relative to the age-adjusted sagittal alignment target reduces the proximal junctional failure (PJF) risk. Nonetheless, a considerable number of patients suffer from PJF despite optimal correction. The aim of this study was to identify the risk factors of PJF that occurs despite optimal correction relative to the sagittal age-adjusted score (SAAS) in adult spinal deformity surgery. METHODS: Patients aged 60 years or older with adult spinal deformity who underwent ≥5-level fusion to the sacrum were initially screened. Among them, only patients who achieved optimal sagittal correction relative to the SAAS were included in the study. Optimal correction was defined as the SAAS point between -1 and +1. Various clinical and radiographic factors were compared between the PJF and no PJF groups and were further evaluated using multivariate analysis. RESULTS: The final study cohort comprised 127 patients. The mean age was 67 years, and there were 111 women (87.4%). A mean of total fusion length was 7.2. PJF occurred in 42 patients (33.1%), while 85 patients (66.9%) did not develop PJF. Multivariate analysis showed that a high body mass index (odds ratio [OR] = 1.153, 95% CI = 1.027-1.295, P = .016), a higher lordosis distribution index (LDI) (OR = 1.024, 95% CI = 1.003-1.045, P = .022), and no use of hook fixation (OR = 9.708, 95% CI = 1.121-76.923, P = .032) were significant risk factors of PJF development. In the receiver operating characteristic curve analysis, the cutoff value for the LDI was calculated as 61.0% (area under the curve = 0.790, P < .001). CONCLUSION: PJF developed in a considerable portion of patients despite optimal correction relative to the age-adjusted alignment. The risk factors of PJF in this patient group were high body mass index, high LDI exceeding 61%, and no use of hook fixation. PJF could be further decreased by properly managing these risk factors along with optimal sagittal correction.

Ideal Lumbar Lordosis Correction in Patients with Adult Spinal Deformity Without Adversely Impacting Pelvic Tilt and Pelvic Incidence Minus Lumbar Lordosis: A Study of 426 Cases.

STUDY DESIGN: Retrospective study. OBJECTIVES: To determine the ideal pelvic incidence (PI) - lumbar lordosis (LL) range to prevent pelvic tilt (PT) undercorrection while avoiding PI-LL overcorrection following adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND: PI-LL and PT are the important sagittal parameters to be restored to an adequate range by surgery. Ideal PI-LL target without causing PI-LL overcorrection and PT undercorrection has not been documented. METHODS: We included patients with ASD undergoing ≥5-level fusion including the sacrum. Receiver operating characteristic (ROC) curve analysis was performed to calculate the lower limit of the ideal PI-LL without causing PI-LL overcorrection and the upper limit of ideal PI-LL without causing PT undercorrection. The calculated ideal PI-LL was validated in terms of proximal junctional kyphosis and failure (PJK and PJF) rates and clinical outcomes. Analyses were performed according to age subgroups (<70 and ≥70 y). RESULTS: In total, 426 patients were included in the study. Female patients were predominant (85.4%), with a mean age of 69.8 years. The lower limits of PI-LL were calculated as 4.9° for all patients, 2.3° for patients aged <70 years, and 7.9° for patients aged ≥70 years. Meanwhile, the upper limits of PI-LL were calculated as 12.7° for all patients, 12.5° for patients aged <70 years, and 13.3° for patients aged ≥70 years. There were no significant differences in the PJK and PJF rates among the new three PI-LL groups. Clinical outcomes were significantly better in patients with the ideal PI-LL group than those in patients with overcorrection or undercorrection groups for all age groups. CONCLUSION: The ideal PI-LL correction target without adversely impacting PT and PI-LL was calculated at 2.3°-12.5° for patients aged <70 years and 7.9°-13.3° for patients aged ≥70 years. These guideline parameters may help ensure optimal clinical outcomes without increasing the risk of PJK/F.

Quantitative Analysis of the Effect of Stereotactic Radiosurgery for Postoperative Residual Cervical Dumbbell Tumors: A Multicenter Retrospective Cohort Study.

OBJECTIVE: Stereotactic radiosurgery (SRS) has been performed for spinal tumors. However, the quantitative effect of SRS on postoperative residual cervical dumbbell tumors remains unknown. This study aimed to quantitatively evaluate the efficacy of SRS for treating postoperative residual cervical dumbbell tumors. METHODS: We retrospectively reviewed cases of postoperative residual cervical dumbbell tumors from 1995 to 2020 in 2 tertiary institutions. Residual tumors underwent SRS (SRS group) or were observed with clinical and magnetic resonance imaging (MRI) follow-up (observation group). Tumor regrowth rates were compared between the SRS and observation groups. Additionally, risk factors for tumor regrowth were analyzed. RESULTS: A total of 28 cervical dumbbell tumors were incompletely resected. Eight patients were in the SRS group, and 20 in the observation group. The mean regrowth rate was not significantly lower (p = 0.784) in the SRS group (0.18 ± 0.29 mm/mo) than in the observation group (0.33 ± 0.40 mm/mo). In the multivariable Cox regression analysis, SRS was not a significant variable (hazard ratio [HR], 0.57; 95% confidence interval [CI], 0.18-1.79; p = 0.336). CONCLUSION: SRS did not significantly decrease the tumor regrowth rate in our study. We believe that achieving maximal resection during the initial operation is more important than postoperative adjuvant SRS.

Innovative Developments in Lumbar Interbody Cage Materials and Design: A Comprehensive Narrative Review.

This review comprehensively examines the evolution and current state of interbody cage technology for lumbar interbody fusion (LIF). This review highlights the biomechanical and clinical implications of the transition from traditional static cage designs to advanced expandable variants for spinal surgery. The review begins by exploring the early developments in cage materials, highlighting the roles of titanium and polyetheretherketone in the advancement of LIF techniques. This review also discusses the strengths and limitations of these materials, leading to innovations in surface modifications and the introduction of novel materials, such as tantalum, as alternative materials. Advancements in three-dimensional printing and surface modification technologies form a significant part of this review, emphasizing the role of these technologies in enhancing the biomechanical compatibility and osseointegration of interbody cages. In addition, this review explores the increase in biodegradable and composite materials such as polylactic acid and polycaprolactone, addressing their potential to mitigate long-term implant-related complications. A critical evaluation of static and expandable cages is presented, including their respective clinical and radiological outcomes. While static cages have been a mainstay of LIF, expandable cages are noted for their adaptability to the patient's anatomy, reducing complications such as cage subsidence. However, this review highlights the ongoing debate and the lack of conclusive evidence regarding the superiority of either cage type in terms of clinical outcomes. Finally, this review proposes future directions for cage technology, focusing on the integration of bioactive substances and multifunctional coatings and the development of patient-specific implants. These advancements aim to further enhance the efficacy, safety, and personalized approach of spinal fusion surgeries. Moreover, this review offers a nuanced understanding of the evolving landscape of cage technology in LIF and provides insights into current practices and future possibilities in spinal surgery.

Efficacy of Total En Bloc Spondylectomy versus Stereotactic Ablative Radiotherapy for Single Spinal Metastasis.

To compare total en bloc spondylectomy (TES) with stereotactic ablative radiotherapy (SABR) for single spinal metastasis, we undertook a single center retrospective study. We identified patients who had undergone TES or SABR for a single spinal metastasis between 2000 and 2019. Medical records and images were reviewed for patient and tumor characteristics, and oncologic outcomes. Patients who received TES were matched to those who received SABR to compare local control and survival. A total of 89 patients were identified, of whom 20 and 69 received TES and SABR, respectively. A total of 38 matched patients were analyzed (19 TES and 19 SABR). The median follow-up period was 54.4 (TES) and 26.1 months (SABR) for matched patients. Two-year progression-free survival (PFS) and overall survival (OS) rates were 66.7% and 72.2% in the TES and 38.9% and 50.7% in the SABR group, respectively. At the final follow-up of the matched cohorts, no significant differences were noted in OS (p = 0.554), PFS (p = 0.345) or local progression (p = 0.133). The rate of major complications was higher in the TES than in the SABR group (21.1% vs. 10.5%, p = 0.660). These findings suggest that SABR leads to fewer complications compared to TES, while TES exhibits better mid-term control of metastatic tumors.

The Fate of Pre-Existing L5-S1 Degeneration following Oblique Lumbar Interbody Fusion of L4-L5 and Above.

BACKGROUND: Previous studies have identified various risk factors for adjacent segment disease (ASD) at the L5-S1 level after fusion surgery, including preoperative sagittal imbalance, longer fusion, and preoperative disc degeneration. However, only a few studies have explored the risk factors for ASD at the L5-S1 level after oblique lumbar interbody fusion (OLIF) at the L4-L5 level and above. This study aimed to identify the risk factors for symptomatic ASD at the L5-S1 level in patients with pre-existing degeneration after OLIF at L4-L5 and above. METHODS: We retrospectively reviewed the data of patients who underwent OLIF at L4-L5 and above, with a minimum follow-up period of 2 years. Patients with central stenosis or Lee grade 2 or 3 foraminal stenosis at L5-S1 preoperatively were excluded. Patients were divided into ASD and non-ASD groups based on the occurrence of new-onset L5 or S1 radicular pain requiring epidural steroid injection (ESI). The clinical and radiological factors were analyzed. Logistic regression was used to identify the risk factors for ASD of L5-S1. RESULTS: A total of 191 patients with a mean age ± standard deviation of 68.6 ± 8.3 years were included. Thirty-four (21.7%) patients underwent ESI at the L5 root after OLIF. In the logistic regression analyses, severe disc degeneration (OR (95% confidence interval (CI)): 2.65 (1.16-6.09)), the presence of facet effusion (OR (95% CI): 2.55 (1.05-6.23)), and severe paraspinal muscle fatty degeneration (OR (95% CI): 4.47 (1.53-13.05)) were significant risk factors for ASD in L5-S1. CONCLUSIONS: In this study, the presence of facet effusion, severe disc degeneration, and severe paraspinal muscle fatty degeneration at the L5-S1 level were associated with the development of ASD at L5-S1 following OLIF at L4-L5 and above. For patients with these conditions, surgeons could consider including L5-S1 in the fusion when considering OLIF at the L4-L5 level and above.

Differential effects of two phosphodiesterase 4 inhibitors against lipopolysaccharide-induced neuroinflammation in mice.

BACKGROUND: Several phosphodiesterase 4 (PDE4) inhibitors have emerged as potential therapeutics for central nervous system (CNS) diseases. This study investigated the pharmacological effects of two selective PDE4 inhibitors, roflumilast and zatolmilast, against lipopolysaccharide-induced neuroinflammation. RESULTS: In BV-2 cells, the PDE4 inhibitor roflumilast reduced the production of nitric oxide and tumor necrosis factor-α (TNF-α) by inhibiting NF-κB phosphorylation. Moreover, mice administered roflumilast had significantly reduced TNF-α, interleukin-1ß (IL-1ß), and IL-6 levels in plasma and brain tissues. By contrast, zatolmilast, a PDE4D inhibitor, showed no anti-neuroinflammatory effects in vitro or in vivo. Next, in vitro and in vivo pharmacokinetic studies of these compounds in the brain were performed. The apparent permeability coefficients of 3 µM roflumilast and zatolmilast were high (> 23 × 10-6 cm/s) and moderate (3.72-7.18 × 10-6 cm/s), respectively, and increased in a concentration-dependent manner in the MDR1-MDCK monolayer. The efflux ratios were < 1.92, suggesting that these compounds are not P-glycoprotein substrates. Following oral administration, both roflumilast and zatolmilast were slowly absorbed and eliminated, with time-to-peak drug concentrations of 2-2.3 h and terminal half-lives of 7-20 h. Assessment of their brain dispositions revealed the unbound brain-to-plasma partition coefficients of roflumilast and zatolmilast to be 0.17 and 0.18, respectively. CONCLUSIONS: These findings suggest that roflumilast, but not zatolmilast, has the potential for use as a therapeutic agent against neuroinflammatory diseases.

Is endotracheal tube displacement during head and neck extension due to ascending movement or tracheal lengthening? An observational ultrasonographic study.

Complications of the endotracheal tube (ETT) displacement during head and neck positional changes are related to not only the tip position but also the cuff pressure against the larynx. Here, we evaluated movement of the ETT cuff relative to laryngeal structures as well as tip displacement from the carina.Sixty-two patients scheduled for thyroidectomy were recruited. The distance from the cricoid cartilage to the upper margin of the cuff (CC) and that from the ETT tip to the carina (TC) were measured using ultrasonography and fiberoptic bronchoscopy, respectively, during flexion and extension. The total tracheal length (TTL) was defined as the combination of CC, TC, and the distance from the upper margin of the cuff to the tip.During flexion, the CC and TC were 1.5 ± 0.6 and 2.9 ± 1.0 cm respectively. Seven patients (11.7%) exhibited excessively deep intubation. After adjusting the cuff position under ultrasonography (CC = 0), the tip position was corrected in 96.7%. While the TC increased by 2.1 ± 1.0 cm after the positional change in extension, the CC decreased by 0.6 ± 0.7 cm because the TTL lengthened (1.4 ± 1.1 cm). Four patients (6.7%) exhibited excessive cuff displacement beyond the cricoid cartilage, which could have been corrected under ultrasonography.In conclusion, the ETT cuff displaced toward the larynx in a less degree than the tip did from the carina due to the tracheal lengthening during head and neck extension. Nevertheless, we suggest that ultrasonographic assessment of cuff position may avoid ETT misplacement. Trial registration https://cris.nih.go.kr/ (approval no. KCT0005319); registered on May 14, 2019.

An Updated Review on the Treatment Strategy for Spinal Metastasis from the Spine Surgeon's Perspective.

Spinal metastasis is a common issue causing significant pain and disability in cancer patients. A multidisciplinary approach consisting of chemotherapy, radiotherapy, and surgical treatment is used for treating patients with metastatic spinal tumors. Due to recent advancements in medical and radiation oncology, like tumor genetics and stereotactic radiotherapy, this treatment strategy would change inevitably. Therefore, the decision-making systems developed for assisting physicians and surgeons to choose the most appropriate treatment for each patient with spinal metastasis need to evolve. In this review, the recent developments, validations, and modifications of these systems, as well as suggestions for future systems have been discussed. Recently, separation surgery combined with stereotactic radiotherapy (hybrid therapy) has gained popularity. Additionally, the evidence for hybrid therapy presented in the literature has been reviewed.

Separation surgery followed by stereotactic ablative radiotherapy for metastatic epidural spinal cord compression: A systematic review and meta-analysis for local progression rate.

Introduction: Spinal metastasis is the most common metastatic skeletal disease in cancer patients. Metastatic epidural spinal cord compression (MESCC), which occurs in 5-14% of cancer patients, is an oncological emergency because it may cause a permanent neurological deficit. Separation surgery followed by stereotactic ablative radiotherapy (SABR), so-called "hybrid therapy," has shown effectiveness in local control of spinal metastasis and has become an integral treatment option for patients with MESCC. Therefore, we performed a meta-analysis and meta-regression analysis to clarify the local progression rate of hybrid therapy and the risk factors for local progression. Methods: We searched PubMed, EMBASE, Scopus, Cochrane Library, and Web of Science databases from inception to December 2021. Meta-analyses of proportions were used to analyze the data using a random-effects model to calculate the pooled 1-year local progression rate and confidence interval. Subgroup analyses were performed using meta-analyses of odds ratio (OR) for comparisons between groups. We also conducted a meta-regression analysis to identify the factors that caused heterogeneity. Results: A total of 661 patients from 13 studies (10 retrospective and 3 prospective) were included in the final meta-analysis. The quality of the included studies assessed using the Newcastle - Ottawa scale ranged from poor to fair (range, 4-6). The pooled local progression rate was 10.2 % (95 % confidence interval [CI], 7.8-12.8 %; I2 = 30 %) and 13.7 % (95 % CI, 9.3-18.8 %; I2 = 55 %) at postoperative 1 and 2 years, respectively. The subgroup analysis indicated that patients with a history of prior radiotherapy (OR, 5.14; 95 % CI, 1.71-15.51) and lower radiation dose per fraction (OR, 4.57; 95 % CI, 1.88-11.13) showed significantly higher pooled 1-year local progression rates. In the moderator analysis, the 1-year local progression rate was significantly associated with the proportion of patients with a history of prior radiotherapy (p = 0.036) and those with colorectal cancer as primary origin (p < 0.001). Conclusions: The pooled 1-year local progression rate of hybrid therapy for MESCC was 10.2%. In subgroup and moderator analyses, a lower radiation dose per fraction, history of prior radiotherapy, and colorectal cancer showed a significant association with the 1-year local progression rate.