Clinical Significance of Lordosis Orientation on Proximal Junctional Kyphosis Development in Long-Segment Fusion Surgery for Adult Spinal Deformity.

OBJECTIVE: We sought to evaluate the clinical impact of lordosis orientation (LO) on proximal junctional kyphosis (PJK) development in adult spinal deformity surgery. METHODS: This study included 152 patients who underwent low thoracic (T9-T12) to pelvis fusion and were followed up for ≥2 years. In the literature, 6 radiographic parameters representing LO were introduced, such as uppermost instrumented vertebra (UIV) slope, UIV inclination, UIV-femoral angle (UIVFA), thoracolumbar tilt, thoracolumbar slope, and lordosis tilt. Various clinical and radiographic factors including 6 LO parameters were investigated using logistic regression analysis to identify risk factors for PJK. RESULTS: The mean age was 69.4 years, and 136 patients were females (89.5%). PJK developed in 65 patients (42.8%). Multivariate logistic regression analysis revealed that only small postoperative pelvic incidence (PI)-lumbar lordosis (LL) (odds ratio [OR] = 0.962, 95% confidence interval: 0.929-0.996, P = 0.030) and large UIVFA (OR = 1.089, 95% confidence interval: 1.028-1.154, P = 0.004) were significant for PJK development. UIVFA showed significantly positive correlation with pelvic tilt (CC = 0.509), thoracic kyphosis (CC = 0.384), and lordosis distribution index (CC = 0.223). UIVFA was also negatively correlated with sagittal vertical axis (CC = -0.371). However, UIVFA did not correlate with LL, PI-LL, or T1 pelvic angle. CONCLUSIONS: LO significantly increases the risk of PJK development in ASD surgery. Multivariate analysis revealed that smaller postoperative PI-LL and greater UIVFA were significant risk factors for PJK. Surgeons should avoid undercorrection and overcorrection to prevent PJK development.

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.

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.

Risk factors of adjacent-segment disease after short-segment fusion in patients with de novo degenerative lumbar scoliosis.

OBJECTIVE: Short-segment fusion (SSF) is an effective surgical option for appropriately selected patients with de novo degenerative lumbar scoliosis (DNDLS). Considering that DNDLS is frequently accompanied by multisegment degeneration and potential instability across the entire lumbar segments, it is inevitable that unhealthy segments remain after SSF, thereby increasing the potential risk of adjacent-segment disease (ASD) occurrence. Therefore, the authors aimed to identify the risk factors for ASD in patients with DNDLS who underwent SSF. METHODS: This retrospective study included 80 patients with DNDLS (Cobb angle > 10°) who underwent SSF (1 or 2 levels) between December 2010 and July 2018 with a minimum follow-up duration of 5 years. The participants were divided into two groups: ASD and non-ASD. ASD was defined as clinical ASD rather than radiographic ASD. Various patient and operative variables were compared between the groups. Global and regional radiographic parameters (preoperatively and postoperatively) were also compared between the two groups using plain radiography and MRI. Consequently, univariate and multivariate analyses were conducted to identify the risk factors for ASD occurrence. The receiver operating characteristic (ROC) curve was used to calculate the cutoff values. RESULTS: The mean ± SD age was 67.7 ± 7.2 years at the time of SSF, and there were 62 women (77.5%) enrolled in the study. Thirty patients (37.5%) were in the ASD group and 50 patients (62.5%) were in the non-ASD group. The mean time from the surgery to ASD diagnosis was 34.9 ± 28.2 months in ASD group. Thirteen patients required revision surgery at a mean time of 8.8 ± 7.0 months after ASD occurrence. Multivariate logistic regression analysis demonstrated that preoperative disc wedging angle (OR 1.806, 95% CI 1.255-2.598, p = 0.001), presence of facet tropism (defined as ≥ 10° difference between the facet joint angles of the right and left sides) (OR 5.534, 95% CI 1.528-20.040, p = 0.009), and foraminal stenosis ≥ grade 2 (OR 5.935, 95% CI 1.253-28.117, p = 0.025) were significant risk factors for ASD development. The cutoff value of the preoperative disc wedging angle was calculated to be 2.5° using the ROC curve. CONCLUSIONS: Preoperative disc wedging angle ≥ 2.5°, presence of facet tropism, and foraminal stenosis ≥ grade 2 were identified as significant risk factors for ASD development after SSF in patients with DNDLS.

Trends in Survival and Surgical Methods in Patients Surgically Treated for Metastatic Spinal Tumors: 25-Year Experience in a Single Institution.

Background: This study aimed to examine trends in postoperative survival and surgical methods over a 25-year period in patients surgically treated for metastatic spinal tumors. Methods: We performed a retrospective study of patients who underwent surgical treatment for metastatic spinal tumors between 1996 and 2020. For trend analysis, the study cohort was divided into three groups according to the year of surgery: 1996-2004, 2005-2012, and 2013-2020. A Kaplan-Meier survival analysis was performed to examine survival, and the log-rank test was used to compare the survival of the top six common cancers among the periods. The surgical methods were grouped and examined as follows: fixation only, palliative decompression and fixation, gross total removal and fixation, and total en bloc spondylectomy. Results: This study included a total of 608 patients. There were 78 patients in 1996-2004, 236 in 2005-2012, and 294 in 2013-2020. Regarding the overall survival trend, the group 2013-2020 had a significantly improved survival as compared to the other two groups (p < 0.001). According to specific cancer sites, significant survival improvement was observed in patients with lung, kidney, and breast cancers (p < 0.001, p < 0.001, and p = 0.022, respectively). There were no significant changes in the primary sites of the liver, colorectum, or prostate. Regarding surgical methods, the proportion of gross total tumor removal declined, whereas the proportion of palliative decompression and fixation and fixation only procedures increased. Conclusions: During the past 25 years, significant survival improvement was observed in patients with lung, kidney, and breast cancers. There was no improvement in survival in patients with liver, colorectal, and prostate cancers. In terms of surgical techniques, palliative decompression and fixation only procedures increased, while gross total tumor removal declined.