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Study Design: A retrospective cohort study., Objective: To evaluate the impact of the upper instrumented vertebral (UIV) screw angle in adult spinal deformity (ASD) surgery on: (1) proximal junctional kyphosis/failure (PJK/F), (2) mechanical complications and radiographic measurements, and (3) patient-reported outcome measures (PROMs)., Summary of Background Data: The effect of UIV screw angle in ASD surgery on patient outcomes remains understudied., Materials and Methods: A single-institution, retrospective study was undertaken from 2011 to 2017. UIV screw angle was trichotomized into positive: cranially directed screws relative to the superior endplate (2°≤θ), neutral: parallel to the superior endplate (-2°<θ<2°), and negative: caudally directed screws relative to the superior endplate (-2°≥θ). The primary outcome was PJK/F. Secondary outcomes included remaining mechanical complications, reoperation, and PROMs: Oswestry Disability Index, Numeric Rating Scale (NRS) back/leg, and EuroQol. Regression controlled for age, body mass index, postoperative sagittal vertical axis (SVA), and pelvic incidence lumbar-lordosis mismatch., Results: Among 145 patients undergoing ASD surgery, UIV screw angles were 35 (24.1%) cranially directed, 24 (16.6%) neutral, and 86 (59.3%) caudally directed. PJK occurred in 47(32.4%) patients. Positive screws were independently associated with increased PJK [odds ratio (OR)=4.88; 95% CI, 1.85-13.5, P =0.002] and PJF (OR=3.06; 95% CI, 1.32-12.30, P =0.015). Among 108 (74.5%) patients with lower thoracic UIV, PJK occurred in 38 (35.1%). Cranially directed screws were independently associated with an increased odds of PJK (OR=5.56; 95% CI, 1.86-17.90, P =0.003) with a threshold of 0.2° (area under the curve =0.65; 95% CI, 0.54-0.76, P <0.001), above which the risk of PJK significantly increased. No association was found between positive screw angle and PJF (OR=3.13; 95% CI, 0.91-11.40, P =0.073). Because of the low number of patients with an upper thoracic UIV (N=37, 25.5%), no meaningful conclusions could be drawn from this subgroup. There was no association between UIV screw angle and remaining mechanical complications, reoperations, postoperative SVA and T1-pelvic angle, or PROMs., Conclusions: Cranially directed UIV screw angles increased the odds of PJK in patients with lower thoracic UIV. Meticulous attention should be paid to the lower thoracic UIV screw angle to mitigate the risk of PJK in ASD., Competing Interests: B.F.S.: consulting: Depuy-Synthes; Research Support: Stryker Spine. A.M.A. received an institutional research support from Stryker Spine. The remaining authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective case-control study., Objective: In a cohort of patients undergoing metastatic spine surgery, we sought to: (1) identify risk factors associated with unplanned readmission, and (2) determine the impact of an unplanned readmission on long-term outcomes., Summary of Background Data: Factors affecting readmission after metastatic spine surgery remain relatively unexplored., Materials and Methods: A single-center, retrospective, case-control study was undertaken of patients undergoing spine surgery for extradural metastatic disease between 02/2010 and 01/2021. The primary outcome was 3-month unplanned readmission. Preoperative, perioperative, and tumor-specific variables were collected. Multivariable Cox regression was performed, controlling for tumor size, other organ metastasis, and preoperative/postoperative radiotherapy/chemotherapy., Results: A total of 357 patients underwent surgery for spinal metastases with a mean follow-up of 538.7±648.6 days. Unplanned readmission within 3 months of surgery occurred in 64/357 (21.9%) patients, 37 (57.8%) were medical, 27 (42.2%) surgical, and 21 (77.7%) were related to their spine surgery. No significant differences were found regarding demographics and preoperative variables, except for insurance, where most readmitted patients had private insurance compared with nonreadmitted patients ( P =0.021). No significant difference was found in preoperative radiotherapy/chemotherapy. Regarding perioperative exposure variables, readmitted patients had a higher rate of postoperative complications (68.8% vs. 24.2%, P <0.001) and worse postoperative Karnofsky Performance Score ( P =0.021) and Modified McCormick Scale ( P =0.015) at the time of first follow-up. On multivariate logistic regression, postoperative complications were associated with increased readmissions (odds ratio=1.38, 95% CI=1.25-1.52, P <0.001). Regarding the impact of unplanned readmission on long-term tumor control, unplanned readmission was associated with shorter time to local recurrence (log-rank; P =0.029) and reduced overall survival (OS) (log-rank; P <0.001). On multivariate Cox regression, other organ metastasis [hazard ratio (HR)=1.48, 95% CI=1.13-1.93, P =0.004] and 3-month readmission (HR=1.75, 95% CI=1.28-2.39, P <0.001) were associated with worsened OS, with no impact on LR. Postoperative chemotherapy was significantly associated with longer OS (HR=0.59, 95% CI=0.45-0.77, P <0.001)., Conclusions: Postoperative complications were associated with unplanned readmission following metastatic spine surgery. Furthermore, 3-month unplanned readmission was associated with a shorter time to local recurrence and decreased OS. These results help surgeons understand the drivers of readmissions and the impact of readmissions on patient outcomes., Level of Evidence: 3., Competing Interests: S.L.Z. reports being an unaffiliated neurotrauma consultant for the National Football League. B.F.S. is a consultant for Nuvasive and Carbofix and receives institutional research support from Nuvasive and Stryker Spine. A.M.A. receives an institutional research support from Stryker Spine. The remaining authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)