L1-pelvic angle: a convenient measurement to attain optimal deformity correction.

PURPOSE: (1) Evaluate the associations between L1-pelvic angle (L1PA) and both sagittal vertical axis (SVA) and T1-pelvic angle (T1PA), and (2) assess the clinical impact of L1PA. METHODS: A single-institution retrospective cohort study was undertaken for patients undergoing adult spinal deformity (ASD) surgery from 2013 to 2017. Ideal L1PA was defined as (0.5xPelvic Incidence)-21. Pearson correlation was performed to compare L1PA, SVA, and T1PA. Univariate/multivariate regression was performed to assess the effect of L1PA on mechanical complications, controlling for age, BMI, and postoperative pelvic incidence-lumbar lordosis mismatch (PI/LL). Due to the overlapping nature of patients with pseudarthrosis and rod fracture, these patients were analyzed together. RESULTS: A total of 145 patients were included. Mean preoperative L1PA, SVA, and T1PA were 15.5 ± 8.9°, 90.7 ± 66.8 mm, and 27.1 ± 13.0°, respectively. Mean postoperative L1PA, SVA, and T1PA were 15.0 ± 8.9°, 66.7 ± 52.8 mm, and 22.3 ± 11.1°, respectively. Thirty-six (24.8%) patients achieved ideal L1PA. Though the correlation was modest, preoperative L1PA was linearly correlated with preoperative SVA (r2 = 0.16, r = 0.40, 95%CI = 0.22-0.60, p < 0.001) and T1PA (r2 = 0.41, r = 0.62, 95%CI = 0.46-0.76, p < 0.001). Postoperative L1PA was linearly correlated with postoperative SVA (r2 = 0.12, r = 0.37, 95%CI = 0.18-0.56, p < 0.001) and T1PA (r2 = 0.40, r = 0.62, 95%CI = 0.45-0.74, p < 0.001). Achieving ideal L1PA ± 5° was associated with a decreased risk of rod fracture/pseudarthrosis on univariate and multivariate regression (OR = 0.33, 95%CI = 0.12-0.86, p = 0.024). No association between achieving ideal L1PA and patient-reported outcomes was observed. CONCLUSION: L1PA was modestly correlated with SVA and T1PA, and achieving ideal L1PA was associated with lower rates of rod fracture/pseudarthrosis. Future studies are warranted to better define the clinical implications of achieving a normal L1PA. LEVEL OF EVIDENCE: III.

The clinical utility of dual-energy CT in post-thrombectomy care: Part 2, the predictive value of contrast density and volume for delayed hemorrhagic transformation.

OBJECTIVES: Dual-energy CT allows differentiation between blood and iodinated contrast. This study aims to determine the predictive value of contrast density and volume on post-thrombectomy dual-energy CT for delayed hemorrhagic transformation and its impact on 90-day outcomes. MATERIALS AND METHODS: A retrospective analysis was performed on patients who underwent thrombectomy for anterior circulation large-vessel occlusion at a comprehensive stroke center from 2018-2021. Per institutional protocol, all patients underwent dual-energy CT immediately post-thrombectomy and MRI or CT 24 hours afterward. The presence of hemorrhage and contrast staining was evaluated by dual-energy CT. Delayed hemorrhagic transformation was determined by 24-hour imaging and classified into petechial hemorrhage or parenchymal hematoma using ECASS III criteria. Univariable and multivariable analyses were performed to determine predictors and outcomes of delayed hemorrhagic transformation. RESULTS: Of 97 patients with contrast staining and without hemorrhage on dual-energy CT, 30 and 18 patients developed delayed petechial hemorrhage and delayed parenchymal hematoma, respectively. On multivariable analysis, delayed petechial hemorrhage was predicted by anticoagulant use (OR,3.53;p=0.021;95%CI,1.19-10.48) and maximum contrast density (OR,1.21;p=0.004;95%CI,1.06-1.37;per 10 HU increase), while delayed parenchymal hematoma was predicted by contrast volume (OR,1.37;p=0.023;95%CI,1.04-1.82;per 10 mL increase) and low-density lipoprotein (OR,0.97;p=0.043;95%CI,0.94-1.00;per 1 mg/dL increase). After adjusting for potential confounders, delayed parenchymal hematoma was associated with worse functional outcomes (OR,0.07;p=0.013;95%CI,0.01-0.58) and mortality (OR,7.83;p=0.008;95%CI,1.66-37.07), while delayed petechial hemorrhage was associated with neither. CONCLUSION: Contrast volume predicted delayed parenchymal hematoma, which was associated with worse functional outcomes and mortality. Contrast volume can serve as a useful predictor of delayed parenchymal hematoma following thrombectomy and may have implications for patient management.

The clinical utility of dual-energy CT in post-thrombectomy care: Part 1, predictors and outcomes of subarachnoid and intraparenchymal hemorrhage.

OBJECTIVES: Dual-energy CT allows differentiation between blood and iodinated contrast. We aimed to determine predictors of subarachnoid and intraparenchymal hemorrhage on dual-energy CT performed immediately post-thrombectomy and the impact of these hemorrhages on 90-day outcomes. MATERIALS AND METHODS: A retrospective analysis was performed on patients who underwent thrombectomy for anterior circulation large-vessel occlusion and subsequent dual-energy CT at a comprehensive stroke center from 2018-2021. The presence of contrast, subarachnoid hemorrhage, or intraparenchymal hemorrhage immediately post-thrombectomy was assessed by dual-energy CT. Univariable and multivariable analyses were performed to identify predictors of post-thrombectomy hemorrhages and 90-day outcomes. Patients with unknown 90-day mRS were excluded. RESULTS: Of 196 patients, subarachnoid hemorrhage was seen in 17, and intraparenchymal hemorrhage in 23 on dual-energy CT performed immediately post-thrombectomy. On multivariable analysis, subarachnoid hemorrhage was predicted by stent retriever use in the M2 segment of MCA (OR,4.64;p=0.017;95%CI,1.49-14.35) and the number of thrombectomy passes (OR,1.79;p=0.019;95%CI,1.09-2.94;per an additional pass), while intraparenchymal hemorrhage was predicted by preprocedural non-contrast CT-based ASPECTS (OR,8.66;p=0.049;95%CI,0.92-81.55;per 1 score decrease) and preprocedural systolic blood pressure (OR,5.10;p=0.037;95%CI,1.04-24.93;per 10 mmHg increase). After adjusting for potential confounders, intraparenchymal hemorrhage was associated with worse functional outcomes (OR,0.25;p=0.021;95%CI,0.07-0.82) and mortality (OR,4.30;p=0.023,95%CI,1.20-15.36), while subarachnoid hemorrhage was associated with neither. CONCLUSIONS: Intraparenchymal hemorrhage immediately post-thrombectomy was associated with worse functional outcomes and mortality and can be predicted by low ASPECTS and elevated preprocedural systolic blood pressure. Future studies focusing on management strategies for patients presenting with low ASPECTS or elevated blood pressure to prevent post-thrombectomy intraparenchymal hemorrhage are warranted.

Formation of a de novo intracranial arteriovenous fistula in a child with PTEN hamartoma tumor syndrome.

PURPOSE: Dural arteriovenous fistulae (dAVF) are an uncommon feature of PTEN hamartoma tumor syndrome (PHTS). We report a case of an adolescent male diagnosed with PHTS following the treatment of multiple intracranial dAVF to emphasize the association of vascular anomalies with this disorder and discuss potential implications. CASE REPORT: An adolescent male presented with bilateral proptosis secondary to intracranial venous hypertension. Workup revealed the presence of a complex intracranial dAVF which was treated with several embolization procedures. Following treatment, a de novo dAVF was identified on surveillance imaging. A genetic workup revealed a pathogenic mutation in PTEN consistent with a diagnosis of PHTS. CONCLUSIONS: Recognition that PHTS may be associated with dAVF, and potentially delayed spontaneous formation of dAVF, is critically important due to the potential for devastating yet preventable neurologic sequelae.

A Prospective Study of the Intra- and Postoperative Efficacy of Intraoperative Neuromonitoring in Spinal Cord Stimulation.

BACKGROUND: Accurate lead placement is critical for spinal cord stimulation (SCS) efficacy. The traditional gold standard of awake placement is often technically difficult. While there is retrospective evidence supporting the use of intraoperative neurophysiological monitoring (IOM) as an alternative, a prospective assessment has not yet been performed. OBJECTIVE: To prospectively evaluate pain and functionality outcomes for IOM-guided SCS, validate two IOM modalities as a means to lateralize lead placement and assess whether IOM can be useful for postoperative programming. METHODS: A total of 73 patients were implanted with SCS using electromyography (EMG) and somatosensory-evoked potential collision studies (SSEP-CS) to verify lead placement. Patient pain and function were assessed through serial administration of several validated questionnaires. Stimulation parameters at 6 months were documented. RESULTS: Statistically significant (p < 0.05) improvements were observed in the McGill Pain Questionnaire, Oswestry Disability Index, Pain Catastrophizing Scale, and Visual Analog Scale. EMG and SSEP-CS appropriately lateralized leads in 65/73 (89.0%) and 40/58 (69.0%) cases, respectively. EMG predicted active contacts in use at follow-up with 82.7% sensitivity. CONCLUSIONS: We provide prospective evidence that IOM can be used to verify SCS placement. Additionally, EMG may help to streamline device programming and thereby improve outcomes by predicting the ideal stimulation contacts in many cases.

"Home Field Advantage": The Presence of a "Home" Neurosurgical Residency Training Program is Associated With Improved Match Outcomes.

BACKGROUND AND OBJECTIVES: Competition for neurosurgical residency training positions remains fierce. The support provided by applicants' home neurosurgery residency training programs (NRTP) is suspected to play a key role in the National Resident Matching Program (NRMP) process. We sought to evaluate the impact of the presence of an Accreditation Council for Graduate Medical Education-accredited NRTP at medical students' home institutions has on NRMP match outcomes. METHODS: Our cross-sectional observational study examined all US allopathic senior student Electronic Residency Application Service applications to a single NRTP from 2016 to 2022. RESULTS: We analyzed a total of 1650 Electronic Residency Application Service applications to a single NRTP, of which 1432 (86.8%) were from schools with an Accreditation Council for Graduate Medical Education-accredited NRTP (NRTP+) and 218 (13.2%) were from schools without a residency (NRTP-). NRTP+ applicants matched a higher rate on both pooled analysis (80.8% vs 71.6%, P = .002) and paired analysis (P = .02) over the seven-cycle study period. This difference was present before (82.4% vs 73.9%, P = .01) and after (77.2% vs 65.6%, P = .046) the COVID-19 pandemic. Cohorts were overall similar; however, NRTP+ applicants had more publication experiences (19.6 ± 19.0 vs 13.1 ± 10.2, P < .001) and were more likely to complete a research gap year (RGY) (25.8% vs 17.0%, P = .004). Completing a RGY was associated with an increased likelihood of matching for NRTP+ applicants but not for NRTP- applicants: NRTP+: 84.9% vs 78.1% (P = .0056); NRTP-: 70.3% vs 70.9% (P = .94). CONCLUSION: The presence of a NRTP at a medical student's home institution is associated with improved NRMP match outcomes. This held true both before and after the COVID-19 pandemic. Applicants from schools with a NRTP had more publication experiences and were more likely to complete a RGY. Completion of a RGY is associated with an increased likelihood of matching only for students with an affiliated NRTP.

Comparison of Outcomes in Patients with Cervical Spine Metastasis After Different Surgical Approaches: A Single-Center Experience.

OBJECTIVE: In patients undergoing cervical spine surgery for metastatic spine disease, we sought to 1) compare perioperative and oncologic outcomes among 3 different operative approaches, 2) report fusion rates, and 3) compare different types of anterior vertebral body replacement. METHODS: A single-center retrospective cohort study of patients undergoing extradural cervical/cervicothoracic spine metastasis surgery between February 2010 and January 2021 was conducted. Operative approaches were anterior-alone, posterior-alone, or combined anterior-posterior, and the grafts/cages used in the anterior fusions were cortical allografts, static cages, or expandable cages. All cages were filled with autograft/allograft. Outcomes included perioperative/postoperative variables, along with fusion rates, functional status, local recurrence (LR), and overall survival (OS). RESULTS: Sixty-one patients underwent cervical spine surgery for metastatic disease, including 11 anterior (18.0%), 28 posterior (45.9%), and 22 combined (36.1%). New postoperative neurologic deficit was the highest in the anterior approach group (P = 0.038), and dysphagia was significantly higher in the combined approach group (P = 0.001). LR (P > 0.999), OS (P = 0.655), and time to both outcomes (log-rank test, OS, P = 0.051, LR, P = 0.187) were not significantly different. Of the 51 patients alive at 3 months, only 19 (37.2%) obtained imaging ≥3 months. Fusion was seen in 11/19 (57.8%) at a median of 8.3 months (interquartile range, 4.6-13.7). Among the anterior corpectomies, the following graft/cage was used: 6 allografts (54.5%), 4 static cages (36.3%), and 1 expandable cage (9.0%), with no difference found in outcomes among the 3 groups. CONCLUSIONS: The only discernible differences between operative approaches were that patients undergoing an anterior approach had higher rates of new postoperative neurologic deficit, and the combined approach group had higher rates of postoperative dysphagia.

Comparing the Upper Instrumented Vertebrae Tilt Angle vs Screw Angle in the Development of Proximal Junction Kyphosis After Adult Spinal Deformity Surgery: Which Matters More?

BACKGROUND: We sought to determine which aspect of the upper instrumented vertebrae (UIV)-tilt angle or screw angle-was more strongly associated with: (1) proximal junctional kyphosis/failure (PJK/F), (2) other mechanical complications and reoperations, and (3) patient-reported outcome measures (PROMs). METHODS: A single-institution, retrospective cohort study was undertaken for patients undergoing adult spinal deformity (ASD) surgery from 2011 to 2017. Only patients with UIV at T7 or below were included. The primary exposure variables were UIV tilt angle (the angle of the UIV inferior endplate and the horizontal) and UIV screw angle (the angle of the UIV screws and superior endplate). Multivariable logistic regression included age, body mass index, osteopenia/osteoporosis, postoperative sagittal vertical axis, postoperative pelvic-incidence lumbar lordosis mismatch, UIV tilt angle, and UIV screw angle. RESULTS: One hundred and seventeen patients underwent adult spinal deformity surgery with a minimum of 2-year follow-up. A total of 41 patients (35.0%) had PJK and 26 (22.2%) had PJF. (1) UIV tilt angle: 96 (82.1%) had lordotic UIV tilt angles, 6 (5.1%) were neutral, and 15 (12.8%) were kyphotic. (2) UIV screw angle: 38 (32.5%) had cranially directed screws, 4 (3.4%) were neutral, and 75 (64.1%) were caudally directed. Both lordotic-angled UIV endplate (OR = 1.06, 95% CI = 1.01-1.12, and P = 0.020) and cranially directed screws (OR = 1.19, 95% CI = 1.07-1.33, and P < 0.001) were associated with higher odds of PJK, with a more pronounced effect of UIV screw angle compared with UIV tilt angle (Wald test, 9.40 vs 4.42). Similar results were found for PJF. Neither parameter was associated with other mechanical complications, reoperations, or patient-reported outcome measures. CONCLUSIONS: UIV screw angle was more strongly associated with development of PJK/F compared with tilt angle. Overall, these modifiable parameters are directly under the surgeon's control and can mitigate the development of PJK/F. CLINICAL RELEVANCE: Surgeons may consider selecting a UIV with a neutral or kyphotically directed UIV tilt angle when performing ASD surgery with a UIV in the lower thoracic or lumbar region, as well as use UIV screw angles that are caudally directed, for the purprose of decreasing the risk of developing PJK/F.

Does Preoperative Bilsky Score Predict Outcome Following Surgical Resection of Primary Tumors of the Spine?

OBJECTIVE: In patients undergoing surgery for primary bone tumors of the spine, we sought to compare Bilsky score 0-1 versus 2-3 in: 1) preoperative presentation, 2) perioperative variables, and 3) long-term outcomes. METHODS: A single-center, retrospective cohort study was undertaken of patients undergoing surgery for extradural, primary bone tumors of the spine between January 2010 and January 2021. The primary exposure variable was Bilsky score, dichotomized as 0-1 versus 2-3. Survival analysis was performed to assess local recurrence (LR) and overall survival (OS). RESULTS: Of 38 patients undergoing resection of primary spinal tumors, 19 (50.0%) patients presented with Bilsky 0-1 and 19 (50.0%) Bilsky 2-3 grades. The most common diagnosis was chondrosarcoma (33.3%), followed by chordoma (16.7%). There were 15 (62.5%) malignant tumors. Preoperatively, there was no significant difference in demographics, Karnofsky Performance Scale (KPS) (P > 0.999), or motor deficit (P > 0.999). Perioperatively, no difference was found in operative time (P = 0.954), blood loss (P = 0.416), length of stay (P = 0.641), neurologic deficit (P > 0.999), or discharge disposition (P = 0.256). No difference was found in Enneking resection status (69.2% vs. 54.5%, P = 0.675). Long-term, no differences were found regarding reoperation (P = 0.327), neurologic deficit (P > 0.999), postoperative KPS (P = 0.605) and modified McCormick Scale (MMS) (P = 0.870). No difference was observed in KPS (P = 0.418) and MMS (P = 0.870) at last follow-up. However, patients with Bilsky 2-3 had shorter time to LR (1715.0 vs. 513.0 ± 633.4 days, log-rank; P = 0.002) and shorter OS (2025.0 ± 1165.3 vs. 794.0 ± 952.6 days, log-rank; P = 0.002). CONCLUSIONS: Bilsky 2-3 lesions were associated with shorter time to LR and shorter OS. Patients harboring primary spinal tumors with higher grade Bilsky score appear to be at a higher risk for worse outcomes.

Combined Anterior-Posterior vs. Posterior-Only Approach in Adult Spinal Deformity Surgery: Which Strategy Is Superior?

Introduction: Whether a combined anterior-posterior (AP) approach offers additional benefits over the posterior-only (P) approach in adult spinal deformity (ASD) surgery remains unknown. In a cohort of patients undergoing ASD surgery, we compared the combined AP vs. the P-only approach in: (1) preoperative/perioperative variables, (2) radiographic measurements, and (3) postoperative outcomes. Methods: A single-institution, retrospective cohort study was performed for patients undergoing ASD surgery from 2009 to 2021. Inclusion criteria were ≥5-level fusion, sagittal/coronal deformity, and 2-year follow-up. The primary exposure was the operative approach: a combined AP approach or P alone. Postoperative outcomes included mechanical complications, reoperation, and minimal clinically important difference (MCID), defined as 30% of patient-reported outcome measures (PROMs). Multivariable linear regression was controlled for age, BMI, and previous fusion. Results: Among 238 patients undergoing ASD surgery, 34 (14.3%) patients underwent the AP approach and 204 (85.7%) underwent the P-only approach. The AP group consisted mostly of anterior lumbar interbody fusion (ALIF) at L5/S1 (73.5%) and/or L4/L5 (38.0%). Preoperatively, the AP group had more previous fusions (64.7% vs. 28.9%, p < 0.001), higher pelvic tilt (PT) (29.6 ± 11.6° vs. 24.6 ± 11.4°, p = 0.037), higher T1 pelvic angle (T1PA) (31.8 ± 12.7° vs. 24.0 ± 13.9°, p = 0.003), less L1-S1 lordosis (-14.7 ± 28.4° vs. -24.3 ± 33.4°, p < 0.039), less L4-S1 lordosis (-25.4 ± 14.7° vs. 31.6 ± 15.5°, p = 0.042), and higher sagittal vertical axis (SVA) (102.6 ± 51.9 vs. 66.4 ± 71.2 mm, p = 0.005). Perioperatively, the AP approach had longer operative time (553.9 ± 177.4 vs. 397.4 ± 129.0 min, p < 0.001), more interbodies placed (100% vs. 17.6%, p < 0.001), and longer length of stay (8.4 ± 10.7 vs. 7.0 ± 9.6 days, p = 0.026). Radiographically, the AP group had more improvement in T1PA (13.4 ± 8.7° vs. 9.5 ± 8.6°, p = 0.005), L1-S1 lordosis (-14.3 ± 25.6° vs. -3.2 ± 20.2°, p < 0.001), L4-S1 lordosis (-4.7 ± 16.4° vs. 3.2 ± 13.7°, p = 0.008), and SVA (65.3 ± 44.8 vs. 44.8 ± 47.7 mm, p = 0.007). These outcomes remained statistically significant in the multivariable analysis controlling for age, BMI, and previous fusion. Postoperatively, no significant differences were found in mechanical complications, reoperations, or MCID of PROMs. Conclusions: Preoperatively, patients undergoing the combined anterior-posterior approach had higher PT, T1PA, and SVA and lower L1-S1 and L4-S1 lordosis than the posterior-only approach. Despite increased operative time and length of stay, the anterior-posterior approach provided greater sagittal correction without any difference in mechanical complications or PROMs.

Predictors of acute post-thrombectomy intracranial hemorrhage expansion in anterior circulation infarcts.

BACKGROUND: Post-mechanical thrombectomy (MT) intracranial hemorrhage (ICH) is a major source of morbidity in treated acute ischemic stroke patients with large vessel occlusion. ICH expansion may further contribute to morbidity. We sought to identify factors associated with ICH expansion on imaging evaluation post-MT. METHODS: We performed a retrospective cohort study of patients undergoing MT at a single comprehensive stroke center. Per protocol, patients underwent dual-energy head CT (DEHCT) post-MT followed by a 24-h interval non-contrast enhanced MRI. ICH expansion was defined as any increase in blood volume between the two studies if identified on the DEHCT. Univariate and multivariable analyses were performed to identify risk factors for ICH expansion. RESULTS: ICH was identified on DEHCT in 13% of patients (n = 35/262), with 20% (7/35) demonstrating expansion on interval MRI. The average increase in blood volume was 11.4 ml (SD 6.9). Univariate analysis identified anticoagulant usage (57% vs 14%, p = 0.03), petechial hemorrhage inside the infarct margins or intraparenchymal hematoma on DEHCT (ECASS-II HI2/PH1/PH2) (71% vs 14%, p < 0.01), basal ganglia hemorrhage (71% vs 21%, p = 0.02), and basal ganglia infarction (86% vs 32%, p = 0.03) as factors associated with ICH expansion. Multivariate regression demonstrated that anticoagulant usage (OR 20.3, 95% C.I. 2.43-446, p < 0.05) and ECASS II scores of HI2/PH1/PH2 (OR 11.7, 95% C.I. 1.24-264, p < 0.05) were significantly predictive of ICH expansion. CONCLUSION: Expansion of post-MT ICH on 24-h interval MRI relative to immediate post-thrombectomy DEHCT is significantly associated with baseline anticoagulant usage and petechial hemorrhage inside the infarct margins or presence of intraparenchymal hematoma (ECASS-II HI2/PH1/PH2).

Do Iliac Screws Placed Close to the Sciatic Notch Have Greater Pullout Strength?

BACKGROUND AND OBJECTIVES: Optimal iliac screw position in relation to the sciatic notch remains unknown. In 12 cadavers undergoing S2 alar-iliac (S2AI) screw placement, we tested the pullout strength of screws placed in proximity to the sciatic notch (≤5 mm) vs farther away from the sciatic notch (>5 mm). METHODS: A biomechanical, cadaver-based study was performed on 12 cadavers undergoing bilateral S2AI screw insertion. The position of the S2AI screw regarding the sciatic notch was dichotomized as ≤5 mm from the sciatic notch on the right side and >5 mm on the left side, confirmed using c-arm fluoroscopy. The primary outcome was the pullout strength of the screw (N). Secondary outcomes were stiffness (N/mm), yield force (N), and work to failure (N mm). Ischial tuberosity was embedded into polymethyl methacrylate and secured to a custom 3-axis vise grip mounted to a 14.5-kN load cell. Pullout testing was performed at 5 mm/min. Force and displacement data were collected at 100 Hz and evaluated using MATLAB. The Mann-Whitney test was performed. RESULTS: Of 24 S2AI screws, 3 screws could not be tested because of cement-bone interface failure. A positive though nonsignificant trend of screw pullout strength was found for screws close to the notch compared with those farther from the notch (861.8 ± 340.7 vs 778.7 ± 350.8 N, P = .859). Similarly, screws close to the notch demonstrated a higher trend of stiffness (149.4 ± 145.4 vs 111.34 ± 128.2 N/mm, P = .320) and force to yield (806.9 ± 352.0 vs 618.6 ± 342.9 N, P = .455). Conversely, screws farther from the notch had a higher but similarly nonsignificant area under the force-displacement curve (10 867.0 ± 9565.0 vs 14 196.6 ± 9578.3 N mm, P = .455), which might be due to excess sheer/translation force that could not be reliably quantified. CONCLUSION: Although placing S2AI screws ≤5 mm of the sciatic notch provided stronger fixation in 3 of 4 biomechanical testing categories, these results were not statistically significant. Therefore, placing S2AI screws ≤5 mm of the sciatic notch did not provide stronger fixation.

Impact of Targeted Systemic Therapy and Radiotherapy on Patients Undergoing Spine Surgery for Metastatic Renal Cell Carcinoma.

BACKGROUND: In patients undergoing spine surgery for renal cell carcinoma (RCC), we sought to: (1) describe patterns of postoperative targeted systemic therapy and radiotherapy (RT), (2) compare perioperative outcomes among those treated with targeted systemic therapy to those without, and (3) evaluate the impact of targeted systemic therapy and/or RT on overall survival (OS) and local recurrence (LR). METHODS: A single-institution, retrospective cohort study of patients undergoing spine surgery for metastatic RCC from 2010 to 2021 was undertaken. Treatment groups were RT alone, targeted systemic therapy alone, dual therapy consisting of RT and targeted systemic therapy, and neither therapy. Multivariable Cox regression controlled for age, race, sex, insurance, and preoperative targeted systemic therapy. RESULTS: Forty-nine patients underwent spine surgery for RCC. Postoperatively, 4 patients (8%) received RT alone, 19 (38.8%) targeted systemic therapy alone, 12 (24.5%) dual therapy, and 13 (28.6%) neither. All groups were similar in demographics, preoperative Karnofsky Performance Score (P = 0.372), tumor size (P = 0.413), readmissions (P = 0.884), complications (P = 0.272), Karnofsky Performance Score (P = 0.466), and Modified McCormick Scale (P = 0.980) at last follow-up. Higher 1-year survival was found in dual therapy (83.3%) compared with other therapies. OS was significantly longer in patients with dual therapy compared with other therapies (log-rank; P = 0.010). Multivariate Cox regression (HR = 0.08, 95% CI = 0.02-0.31, P < 0.001) showed longer OS in dual therapy compared with other therapies. Seven patients (14.3%) experienced LR, and a similar time to LR was found between groups (log-rank; P = 0.190). CONCLUSION: In patients undergoing metastatic spine surgery for RCC, postoperative dual therapy demonstrated significantly higher 1-year survival and OS compared with other therapies. CLINICAL RELEVANCE: Multidisciplinary management of metastatic RCC is necessary to ensure timely implementation of targeted systemic therapy and RT to improve outcomes.

Revision Strategies for Cervical Disc Arthroplasty.

STUDY DESIGN: Narrative review. OBJECTIVE: To review indications and strategies for revision of cervical disc arthroplasty (CDA). SUMMARY OF BACKGROUND DATA: No data were generated as part of this review. METHODS: A narrative review of the literature was performed. RESULTS: No results were generated as part of this review. CONCLUSIONS: CDA is a proven, motion-sparing surgical option for the treatment of myelopathy or radiculopathy secondary to cervical degenerative disc disease. As is the case with any operation, a small percentage of CDA will require revision, which can be a technically demanding endeavor. Here we review available revision strategies and associated indications, a thorough understanding of which will aid the surgeon in finely tailoring their approach to varying presentations.

How Much Blood Loss Is Appropriate for a 2- to 3-Level Posterior Lumbar Fusion?

BACKGROUND: Despite the known association between higher estimated blood loss (EBL) and suboptimal outcomes, the threshold of EBL that negatively impacts outcomes following elective spine surgery remains unknown. In an open 2- and 3-level posterolateral lumbar fusion, we sought to find a threshold of surgeon-reported EBL associated with length of stay (LOS), 30-day complications, and patient-reported outcomes (PROs). METHODS: A single-center, retrospective cohort study was performed for 2- and 3-level open posterolateral lumbar fusions between October 2010 and April 2021. Surgeon-reported EBL (milliliters) was the primary independent variable for predicting LOS (days). Secondary outcomes included 30-day complications and PROs as the minimal clinically important difference (MCID). Multivariable regression and receiver operating characteristic curve with Youden's Index were calculated. RESULTS: 2-Level Fusion: A total of 557 patients underwent 2-level fusions. Multivariable regression found EBL to be a significant risk factor for prolonged LOS. A threshold of 375 mL was associated with LOS beyond postoperative day 2 (POD2) (area under the curve [AUC] = 0.64, 95% CI 0.58-0.70, P < 0.001). 3-Level Fusion: A total of 287 patients underwent 3-level fusions. Similarly, EBL was a significant risk factor for prolonged LOS, with a threshold of 675 mL to predict LOS beyond POD2 (AUC = 0.63, 95% CI 0.54-0.73, P = 0.012). EBL was associated with increased odds of 30-day complications, with a threshold of 538 mL (AUC = 0.63, 95% CI 0.51-0.76, P < 0.001). For both 2- and 3-level fusions, EBL was not significantly associated with MCID for any of the PROs. CONCLUSIONS: In patients undergoing open, posterolateral lumbar fusions, surgeon-reported EBL thresholds at 375 mL for 2-level fusions and 675 mL for 3-level fusions were moderately associated with LOS beyond POD2. In 3-level lumbar fusions, EBL above 538 mL showed a potential association with an increased odds of 30-day complications. CLINICAL RELEVANCE: Surgeons should improve their ability to manage blood loss and implement methods to keep EBL below the provided thresholds to decrease LOS and minimize the risk of complications.

Which Approach Leads to More Reoperations in Single-Level, Open, Posterior Lumbar Fusion: Transforaminal Lumbar Interbody Fusion or Posterolateral Fusion Alone?

BACKGROUND: Transforaminal lumbar interbody fusion (TLIF) and posterolateral fusion (PLF) without an interbody device are two common approaches for single-level, open posterior fusion. Presently, it is unknown whether one of these operations leads to better outcomes. We sought to compare reoperation, complication, and readmission rates between TLIF and PLF for patients undergoing elective single-level, open, posterior lumbar fusion. METHODS: A single-center, retrospective cohort study utilizing prospectively collected data was performed. Inclusion criteria were patients undergoing elective single-level, open, posterior lumbar decompression and fusion between October 2010 and April 2021 with at least 1-year follow-up. The two comparison groups were TLIF vs PLF alone without interbody. The primary outcome was need for reoperation at most recent follow-up. Secondary outcomes included 90-day complication and readmission rates. Univariate and multivariable logistic regression analyses were performed. RESULTS: A total of 850 patients were included, 591 (69.5%) of whom underwent TLIF and 259 (30.5%) of whom underwent PLF. Median follow-up was 6.1 years (interquartile range 3.7-8.9). No significant difference was found in overall reoperation rates (12.4% vs 13.9%, P = 0.534). When stratified by <5-year follow-up (n = 231 TLIF, n = 85 PLF; 37.2%) and ≥5-year follow-up (n = 360 TLIF, n = 174 PLF; 62.8%), no significant differences were seen in either cohort (<5 years: n = 24 TLIF vs n = 9 PLF, P = 0.959; 5+ years: n = 49 TLIF vs n = 27 PLF, P = 0.555). On multivariable logistic regression analysis, the presence of interbody fusion was not associated with reoperation (OR 2.26, 95% CI 0.66-7.74, P = 0.194). CLINICAL RELEVANCE: For patients undergoing elective single-level, open, posterior lumbar fusion without isthmic spondylolisthesis, no differences were seen in reoperation rates at long-term follow-up. Similar 90-day complication and readmission rates were seen. These results suggest that in degenerative lumbar spine disease without isthmic spondylolisthesis, TLIF and PLF achieved similar outcomes.

Is lower screw density associated with mechanical complications in adult spinal deformity surgery?

PURPOSE: To assess the impact of screw density on: (1) rod fracture/pseudarthrosis, (2) proximal/distal junctional kyphosis/failure (PJK/DJK/PJF), and (3) deformity correction judged by sagittal vertical axis (SVA) and T1-pelvic angle (T1PA). METHODS: A single-center, retrospective cohort study of patients undergoing adult spinal deformity (ASD) surgery from 2013 to 2017 was undertaken. Screw density was calculated by dividing the number of screws placed by the total instrumented levels. Screw density was then dichotomized at our calculated mean density to ≥ 1.65 and < 1.65. Outcomes consisted of mechanical complications and the amount of correction obtained. RESULTS: 145 patients underwent ASD surgery with 2-year follow-up. Mean screw density (range) was 1.6 ± 0.3 (1.00-2.00). The most common levels with missing screws were L2 (n = 59, 40.7%), L3 (n = 57, 39.3%) and L1 (n = 51, 35.2%), located mainly along the concavity in 113(80.0%) patients and apices in 98 (67.6%) patients. Rod fracture/pseudarthrosis: 23/32 (71.8%) patients with rod fracture and 35/46 (76.0%) with pseudarthrosis had missing screws within two levels of the rod fracture/pseudarthrosis. Logistic regression showed no significant association between screw density and rod fracture/pseudarthrosis. PJK/F: 15/47 (31.9%) patients with PJK and 9/30 (30.0%) with PJF had missing screws within three levels of the upper instrumented vertebra (UIV). Logistic regression showed no significant association between screws density and PJK/F. Correction obtained: linear regression failed to show any significant association between screw density and SVA or T1PA correction. CONCLUSION: These findings showed that no significant association was found between screw density and mechanical complications or the amount of correction obtained, though approximately 3 out of 4 patients with rod fracture/pseudarthrosis had missing screws at or within two levels of the pathology. The prevention of mechanical complications is likely multifactorial and subject to both patient's characteristics and surgical techniques. LEVEL OF EVIDENCE: III.

How Much Blood Loss Is Too Much for a 1-Level Open Lumbar Fusion?

BACKGROUND: Despite the known association between increased estimated blood loss (EBL) and suboptimal perioperative outcomes, the exact threshold of EBL that impacts outcomes following elective spine surgery remains unknown. In a cohort of patients undergoing elective 1-level open posterior lumbar fusion, we sought to identify EBL thresholds associated with: (1) prolonged length of stay (LOS), (2) postoperative complications, and (3) patient-reported outcomes (PROs). METHODS: A retrospective, single-center study was performed of patients undergoing elective, 1-level open posterior lumbar fusion with and without interbody fusion between October 2010 and April 2021. The primary exposure variable was EBL. Primary outcomes included: (1) LOS, (2) 30-day complications, and (3) 3-month PROs. Minimum clinically important difference was set at 30% improvement from baseline. For purposes of receiver-operating characteristic curves, LOS was dichotomized as 1 vs ≥2 days. RESULTS: Of the 2028 patients undergoing posterior lumbar fusion surgery, 1183 underwent 1-level fusions, 763 (64.5%) with interbody fusion and 420 (35.5%) without. With interbody fusion: Median (interquartile range [IQR]) EBL was 350 mL (200-600), and median (IQR) LOS was 2 days (2-3). A positive linear association was found between EBL and LOS (P < 0.001) but not with PROs. EBL above 275 mL was associated with LOS beyond postoperative day 1 (POD1) (area under the curve [AUC] = 0.73, 95% CI 0.68-0.78, P < 0.001), with no significant association with overall complications or PROs. Without interbody fusion: Median EBL (IQR) was 300 mL (150-500), and median (IQR) LOS was 3 days (2-4). A positive linear association was found between EBL and LOS (P < 0.001) but not with PROs. EBL above 238 mL was associated with LOS beyond POD1 (AUC = 0.78, 95% CI 0.71-0.85, P < 0.001), with no impact on overall complications or PROs. CONCLUSIONS: In patients undergoing 1-level posterior lumbar fusion, EBL volumes greater than 275 and 238 mL in patients with and without interbody fusion, respectively, were associated with increased LOS beyond POD1. No effect was found regarding 30-day complications and 3-month PROs. Although EBL did not directly impact complications or PROs, surgeons may expect longer LOS when higher EBL is reported. CLINICAL RELEVANCE: EBL above 275 mL with an interbody and 238 mL without an interbody were associated with prolonged LOS beyond POD1 in 1-level open lumbar fusion.

Low Levels of Low-Density Lipoprotein Cholesterol Increase the Risk of Post-Thrombectomy Delayed Parenchymal Hematoma.

PURPOSE: Low levels of low-density lipoprotein cholesterol (LDL-C) have been suggested to increase the risk of hemorrhagic transformation (HT) following acute ischemic stroke. However, the literature on the relationship between LDL-C levels and post-thrombectomy HT is sparse. The aim of our study is to investigate the association between LDL-C and delayed parenchymal hematoma (PH) that was not seen on immediate post-thrombectomy dual-energy computed tomography (DECT). MATERIALS AND METHODS: A retrospective analysis was conducted on all patients with anterior circulation large vessel occlusion who underwent thrombectomy at a comprehensive stroke center from 2018-2021. Per institutional protocol, all patients received DECT immediately post-thrombectomy and magnetic resonance imaging or CT at 24 hours. The presence of immediate hemorrhage was assessed by DECT, while delayed PH was assessed by 24-hour imaging. Multivariable analysis was performed to identify predictors of delayed PH. Patients with hemorrhage on immediate post-thrombectomy DECT were excluded to select only those with delayed PH. RESULTS: Of 159 patients without hemorrhage on immediate post-thrombectomy DECT, 18 (11%) developed delayed PH on 24-hour imaging. In multivariable analysis, LDL-C (odds ratio [OR], 0.76; P=0.038; 95% confidence interval [CI], 0.59-0.99; per 10 mg/dL increase) independently predicted delayed PH. High-density lipoprotein cholesterol, triglyceride, and statin use were not associated. After adjusting for potential confounders, LDL-C ≤50 mg/dL was associated with an increased risk of delayed PH (OR, 5.38; P=0.004; 95% CI, 1.70-17.04), while LDL-C >100 mg/dL was protective (OR, 0.26; P=0.041; 95% CI, 0.07-0.96). CONCLUSION: LDL-C ≤50 mg/dL independently predicted delayed PH following thrombectomy and LDL-C >100 mg/dL was protective, irrespective of statin. Thus, patients with low LDL-C levels may warrant vigilant monitoring and necessary interventions, such as blood pressure control or anticoagulation management, following thrombectomy even in the absence of hemorrhage on immediate post-thrombectomy DECT.