Assessing Abnormal Proximal Junctional Angles in Adult Spinal Deformity: A Normative Data Approach to Define Proximal Junctional Kyphosis.

STUDY DESIGN: Multicentric retrospective study of prospectively collected data. OBJECTIVE: Based on normative data from a cohort of asymptomatic volunteers, this study sought to determine the rate of abnormal values of proximal junctional angles (PJA) in adult spinal deformity (ASD) surgery patients, and compare it with PJK rate. SUMMARY OF BACKGROUND DATA: Proximal junctional kyphosis (PJK) definition does not take the vertebral level into account. METHODS: This study included 721 healthy volunteers and 824 ASD surgery patients with 2-year postoperative follow-up. Normative values for each disc and vertebral body between T1 and T12 were analyzed, then normative values for PJA at each thoracic level were defined in the volunteer cohort as the mean±2 standard deviations. PJA abnormal values at the upper instrumented vertebra (UIV) were compared with Glattes' and Lovecchio's definitions for PJK in the ASD population at two years. RESULTS: Mean age was 37.7±16.3 in the volunteer cohort, with 50.5% of females. Mean thoracic kyphosis (TK) was -50.9±10.8°. Corridors of normality included PJA greater than 20° between T3 and T12. Mean age was 60.5±14.0 years in the ASD cohort, with 77.2% of females. Mean baseline TK was -37.4±19.9°, with a significant increase after surgery (-15.6±15.3°, P<0.001). There was 46.2% of PJK according to Glattes' versus 8.7% according to Lovecchio's and 22.9% of kyphotic PJA compared to normative values (P<0.001). CONCLUSION: This study provides normative values for segmental and regional alignment of thoracic spine, used to describe abnormal values of PJA for each level. Using level-adjusted PJA values allows a more precise assessment of abnormal proximal angles and question the definition for PJK. LEVEL OF EVIDENCE: II.

High-Dose TXA Is Associated with Less Blood Loss Than Low-Dose TXA without Increased Complications in Patients with Complex Adult Spinal Deformity.

BACKGROUND: Tranexamic acid (TXA) is commonly utilized to reduce blood loss in adult spinal deformity (ASD) surgery. Despite its widespread use, there is a lack of consensus regarding the optimal dosing regimen. The aim of this study was to assess differences in blood loss and complications between high, medium, and low-dose TXA regimens among patients undergoing surgery for complex ASD. METHODS: A multicenter database was retrospectively analyzed to identify 265 patients with complex ASD. Patients were separated into 3 groups by TXA regimen: (1) low dose (<20-mg/kg loading dose with ≤2-mg/kg/hr maintenance dose), (2) medium dose (20 to 50-mg/kg loading dose with 2 to 5-mg/kg/hr maintenance dose), and (3) high dose (>50-mg/kg loading dose with ≥5-mg/kg/hr maintenance dose). The measured outcomes included blood loss, complications, and red blood cell (RBC) units transfused intraoperatively and perioperatively. The multivariable analysis controlled for TXA dosing regimen, levels fused, operating room time, preoperative hemoglobin, 3-column osteotomy, and posterior interbody fusion. RESULTS: The cohort was predominantly White (91.3%) and female (69.1%) and had a mean age of 61.6 years. Of the 265 patients, 54 (20.4%) received low-dose, 131 (49.4%) received medium-dose, and 80 (30.2%) received high-dose TXA. The median blood loss was 1,200 mL (interquartile range [IQR], 750 to 2,000). The median RBC units transfused intraoperatively was 1.0 (IQR, 0.0 to 2.0), and the median RBC units transfused perioperatively was 2.0 (IQR, 1.0 to 4.0). Compared with the high-dose group, the low-dose group had increased blood loss (by 513.0 mL; p = 0.022) as well as increased RBC units transfused intraoperatively (by 0.6 units; p < 0.001) and perioperatively (by 0.3 units; p = 0.024). The medium-dose group had increased blood loss (by 491.8 mL; p = 0.006) as well as increased RBC units transfused intraoperatively (by 0.7 units; p < 0.001) and perioperatively (by 0.5 units; p < 0.001) compared with the high-dose group. CONCLUSIONS: Patients with ASD who received high-dose intraoperative TXA had fewer RBC transfusions intraoperatively, fewer RBC transfusions perioperatively, and less blood loss than those who received low or medium-dose TXA, with no differences in the rates of seizure or thromboembolic complications. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Comparison of intraoperative and postoperative outcomes between open, wiltse, and percutaneous approach to traumatic thoracolumbar spine fractures without neurological injury: A systematic review and meta-analysis.

Background: Traumatic thoracolumbar fracture fixation without neurological injury can be performed using the traditional open, mini-open Wiltse, and percutaneous approaches. This systematic review and meta-analysis aims to compare perioperative outcomes between these approaches. Methods: PubMed, Web of Science, Scopus, Embase, and the Cochrane Library were searched for all relevant observational comparative studies. Results: 5 randomized trials and 22 comparative cohort studies were included. Compared to the traditional open approach (n=959), the Wiltse approach (n=410) was associated with significantly lower operative time, intraoperative estimated blood loss (EBL), and length of stay (LOS). There was no significant difference between the two in terms of postoperative visual analog scale (VAS) and Cobb angle. Compared to the percutaneous approach (n=980), the Wiltse approach was associated with shorter operative and fluoroscopy time, as well as significantly improved Cobb and vertebral body angles. The percutaneous approach was associated with improved vertebral body height. There was no significant difference between the two for blood loss, postoperative VAS, or LOS. Compared to the traditional open approach, the percutaneous approach was associated with shorter operative time, lower EBL, shorter LOS and better postoperative VAS and Oswestry Disability Index. There was no difference between the two in postoperative Cobb angle, vertebral angle, or vertebral body height. Overall study heterogeneity was high. Conclusions: Utilization of minimally invasive surgical approaches holds great promise for lowering patient morbidity and optimizing care. A prospective trial is needed to assess outcomes and guide surgical decision making.

The Conceptualization and Derivation of the Cervical Lordosis Distribution Index.

SUMMARY OF BACKGROUND DATA: Yilgor et al developed the lumbar Lordosis Distribution Index to individualize the pelvic mismatch to each patient's pelvic incidence. The cervical lordosis distribution in relation to its apex has not been characterized. OBJECTIVE: Tailor correction of cervical deformity by incorporating the cervical apex into a distribution index(CLDI) to maximize clinical outcomes while lowering rates of junctional failure. STUDY DESIGN/SETTING: Retrospective cohort. METHODS: CD patients with complete 2Y data were included. Optimal outcome is defined by no DJF, and meeting Virk et al Good Clinical Outcome Criteria:[Meeting 2 of 3: 1)an NDI<20 or meeting MCID, 2)mJOA>=14, 3)an NRS-Neck<=5 or improved by 2 or more points]. C2-T2 lordosis was divided into cranial (C2 to apex) and caudal (apex to T2) arches postoperatively. A cervical lordosis distribution index(CLDI) was developed by dividing the cranial lordotic arch(C2 to apex) by the total segment(C2-T2) and multiplying by 100. Cross-tabulations developed categories for CLDI producing the highest chi-square values for achieving Optimal Outcome at two years and outcomes were assessed by multivariable analysis controlling for significant confounders. RESULTS: 84 CD patients were included. Cervical apex distribution postoperatively was: 1% C3, 42% C4, 30% C5, 27% C6. Mean cervical LDI was 117±138. Mean cranial lordosis was 23.2±12.5°. Using cross-tabulations, a CLDI between 70 and 90 was defined as 'Aligned'. Chi-square test revealed significant differences among CLDI categories for DJK, DJF, Good Clinical Outcome, and Optimal Outcome(all P<0.05). Patients aligned in CLDI were less likely to develop DJK(OR: 0.1, [0.01-0.88]), more like to achieve GCO (OR: 3.9, [1.2-13.2]) and Optimal Outcome (OR: 7.9, [2.1-29.3] at two years. Patients aligned in CLDI developed DJF at a rate of 0%. CONCLUSION: The cervical lordosis distribution index, classified through the cranial segment, takes each unique cervical apex into account and tailors correction to the patient in order to better achieve good clinical outcomes and minimize catastrophic complications following cervical deformity surgery. LEVEL OF EVIDENCE: III.

The T4-L1-Hip Axis: Sagittal Spinal Realignment Targets in Long-Construct Adult Spinal Deformity Surgery: Early Impact.

BACKGROUND: Our understanding of the relationship between sagittal alignment and mechanical complications is evolving. In normal spines, the L1-pelvic angle (L1PA) accounts for the magnitude and distribution of lordosis and is strongly associated with pelvic incidence (PI), and the T4-pelvic angle (T4PA) is within 4° of the L1PA. We aimed to examine the clinical implications of realignment to a normal L1PA and T4-L1PA mismatch. METHODS: A prospective multicenter adult spinal deformity registry was queried for patients who underwent fixation from the T1-T5 region to the sacrum and had 2-year radiographic follow-up. Normal sagittal alignment was defined as previously described for normal spines: L1PA = PI × 0.5 - 21°, and T4-L1PA mismatch = 0°. Mechanical failure was defined as severe proximal junctional kyphosis (PJK), displaced rod fracture, or reoperation for junctional failure, pseudarthrosis, or rod fracture within 2 years. Multivariable nonlinear logistic regression was used to define target ranges for L1PA and T4-L1PA mismatch that minimized the risk of mechanical failure. The relationship between changes in T4PA and changes in global sagittal alignment according to the C2-pelvic angle (C2PA) was determined using linear regression. Lastly, multivariable regression was used to assess associations between initial postoperative C2PA and patient-reported outcomes at 1 year, adjusting for preoperative scores and age. RESULTS: The median age of the 247 included patients was 64 years (interquartile range, 57 to 69 years), and 202 (82%) were female. Deviation from a normal L1PA or T4-L1PA mismatch in either direction was associated with a significantly higher risk of mechanical failure, independent of age. Risk was minimized with an L1PA of PI × 0.5 - (19° ± 2°) and T4-L1PA mismatch between -3° and +1°. Changes in T4PA and in C2PA at the time of final follow-up were strongly associated (r2 = 0.96). Higher postoperative C2PA was independently associated with more disability, more pain, and worse self-image at 1 year. CONCLUSIONS: We defined sagittal alignment targets using L1PA (relative to PI) and the T4-L1PA mismatch, which are both directly modifiable during surgery. In patients undergoing long fusion to the sacrum, realignment based on these targets may lead to fewer mechanical failures. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Do obese patients undergoing surgery for grade 1 spondylolisthesis have worse outcomes at 5 years' follow-up? A QOD study.

OBJECTIVE: The long-term effects of increased body mass index (BMI) on surgical outcomes are unknown for patients who undergo surgery for low-grade lumbar spondylolisthesis. The goal of this study was to assess long-term outcomes in obese versus nonobese patients after surgery for grade 1 spondylolisthesis. METHODS: Patients who underwent surgery for grade 1 spondylolisthesis at the Quality Outcomes Database's 12 highest enrolling sites (SpineCORe group) were identified. Long-term (5-year) outcomes were compared for patients with BMI ≥ 35 versus BMI < 35. RESULTS: In total, 608 patients (57.6% female) were included. Follow-up was 81% (excluding patients who had died) at 5 years. The BMI ≥ 35 cohort (130 patients, 21.4%) was compared to the BMI < 35 cohort (478 patients, 78.6%). At baseline, patients with BMI ≥ 35 were more likely to be younger (58.5 ± 11.4 vs 63.2 ± 12.0 years old, p < 0.001), to present with both back and leg pain (53.8% vs 37.0%, p = 0.002), and to require ambulation assistance (20.8% vs 9.2%, p < 0.001). Furthermore, the cohort with BMI ≥ 35 had worse baseline patient-reported outcomes including visual analog scale (VAS) back (7.6 ± 2.3 vs 6.5 ± 2.8, p < 0.001) and leg (7.1 ± 2.6 vs 6.4 ± 2.9, p = 0.031) pain, disability measured by the Oswestry Disability Index (ODI) (53.7 ± 15.7 vs 44.8 ± 17.0, p < 0.001), and quality of life on EuroQol-5D (EQ-5D) questionnaire (0.47 ± 0.22 vs 0.56 ± 0.22, p < 0.001). Patients with BMI ≥ 35 were more likely to undergo fusion (85.4% vs 74.7%, p = 0.01). There were no significant differences in 30- and 90-day readmission rates (p > 0.05). Five years postoperatively, there were no differences in reoperation rates or the development of adjacent-segment disease for patients in either BMI < 35 or ≥ 35 cohorts who underwent fusion (p > 0.05). On multivariate analysis, BMI ≥ 35 was a significant risk factor for not achieving minimal clinically important differences (MCIDs) for VAS leg pain (OR 0.429, 95% CI 0.209-0.876, p = 0.020), but BMI ≥ 35 was not a predictor for achieving MCID for VAS back pain, ODI, or EQ-5D at 5 years postoperatively. CONCLUSIONS: Both obese and nonobese patients benefit from surgery for grade 1 spondylolisthesis. At the 5-year time point, patients with BMI ≥ 35 have similarly low reoperation rates and achieve rates of satisfaction and MCID for back pain (but not leg pain), disability (ODI), and quality of life (EQ-5D) that are similar to those in patients with a BMI < 35.

Do class III obese patients achieve similar outcomes and satisfaction to nonobese patients following surgery for cervical myelopathy? A QOD study.

OBJECTIVE: The aim of this study was to compare the rate of achievement of the minimal clinically important difference (MCID) in patient-reported outcomes (PROs) and satisfaction between cervical spondylotic myelopathy (CSM) patients with and without class III obesity who underwent surgery. METHODS: The authors analyzed patients from the 14 highest-enrolling sites in the prospective Quality Outcomes Database CSM cohort. Patients were dichotomized based on whether or not they were obese (class III, BMI ≥ 35 kg/m2). PROs including visual analog scale (VAS) neck and arm pain, Neck Disability Index (NDI), modified Japanese Orthopaedic Association (mJOA), EQ-5D, and North American Spine Society patient satisfaction scores were collected at baseline and 24 months after cervical spine surgery. RESULTS: Of the 1141 patients with CSM who underwent surgery, 230 (20.2%) were obese and 911 (79.8%) were not. The 24-month follow-up rate was 87.4% for PROs. Patients who were obese were younger (58.1 ± 12.1 years vs 61.2 ± 11.6 years, p = 0.001), more frequently female (57.4% vs 44.9%, p = 0.001), and African American (22.6% vs 13.4%, p = 0.002) and had a lower education level (high school or less: 49.1% vs 40.8%, p = 0.002) and a higher American Society of Anesthesiologists grade (2.7 ± 0.5 vs 2.5 ± 0.6, p < 0.001). Clinically at baseline, the obese group had worse neck pain (VAS score: 5.7 ± 3.2 vs 5.1 ± 3.3), arm pain (VAS score: 5.4 ± 3.5 vs 4.8 ± 3.5), disability (NDI score: 42.7 ± 20.4 vs 37.4 ± 20.7), quality of life (EQ-5D score: 0.54 ± 0.22 vs 0.56 ± 0.22), and function (mJOA score: 11.6 ± 2.8 vs 12.2 ± 2.8) (all p < 0.05). At the 24-month follow-up, however, there was no difference in the change in PROs between the two groups. Even after accounting for relevant covariates, no significant difference in achievement of MCID and satisfaction was observed between the two groups at 24 months. CONCLUSIONS: Despite the class III obese group having worse baseline clinical presentations, the two cohorts achieved similar rates of satisfaction and MCID in PROs. Class III obesity should not preclude and/or delay surgical management for patients who would otherwise benefit from surgery for CSM.

Necessity of posterior osteotomies for mild flexible cervical deformity correction.

OBJECTIVE: Correction of mild flexible cervical deformity (CD) via the posterior approach has been described with and without the use of posterior osteotomies (POs), despite a lack of clarity regarding their necessity or risks. The purpose of this study was to determine whether the use of POs when correcting mild flexible CD leads to improved clinical or radiographic outcomes, as well as defining the relative risks in utilizing them. METHODS: A prospective multicenter registry of operative CD patients was analyzed. Inclusion criteria were cervical kyphosis > 10°, cervical scoliosis > 10°, cervical sagittal vertical axis (cSVA) > 4 cm, or chin-brow vertical angle > 25°. Mild deformity was defined by a cSVA of 3-5 cm and/or kyphosis < 15°. Flexibility was defined by a C2-7 angular change > 5° on preoperative flexion/extension radiographs. Patients who received a posterior column osteotomy (PCO) (Ames grades 1 and 2) were compared with patients who did not undergo a PCO (noPCO) as well as those who underwent a three-column osteotomy (3CO) (Ames grades 3-6). RESULTS: Ninety-five patients (33 PCO, 49 noPCO, 13 3CO) met the inclusion criteria. Both the number of levels fused (9.2 vs 7.7, p = 0.001) and the estimated blood loss (EBL) (1027 vs 486 mL, p = 0.012) were higher in the PCO cohort. Patients in the noPCO group were more likely to have a cervical apex of kyphosis (71.1%, p = 0.046), while those undergoing 3COs were more likely to have a thoracic apex (58.3%, p = 0.005). Preoperative cSVA (PCO vs noPCO: 45.4 vs 37.9 cm, p = 0.084), T1 slope (32.5° vs 29.6°, p = 0.376), C2-7 lordosis (-8.9° vs -9.2°, p = 0.942), and modified Japanese Orthopaedic Association (mJOA) score (13.4 vs 13.5, p = 0.854) were similar; however, both Neck Disability Index (NDI) (55.6 vs 42, p = 0.002) and numeric rating scale (NRS) neck (7.2 vs 5.8, p = 0.028) scores were higher in the PCO group before surgery. When adjusting for the use of an anterior approach, there was no significant difference in 1-year postoperative cSVA (35.7 and 35.6 cm, respectively; p = 0.969), C2-7 lordosis (13.7° and 10.1°, respectively; p = 0.393), and patient-reported outcome measures (NRS, NDI, and mJOA) between the PCO and noPCO groups. Two-year radiographic outcomes were largely similar, except for C2 slope, which was higher in the PCO group (29.1° vs 18°, p = 0.026). The overall complication rates progressively increased with more complex osteotomy use (noPCO 68.8% vs PCO 71.9% vs 3CO 75%) but did not reach significance (p = 0.063). CONCLUSIONS: The use of POs for mild flexible adult CD may not be necessary to achieve desirable radiographic correction. They are associated with greater EBL and fusion burden. Further studies are needed to fully delineate the risks of adverse events for various types of osteotomies.

Comparative analysis of patient-reported outcomes in myelopathy and myeloradiculopathy: a Quality Outcomes Database study.

OBJECTIVE: Myelopathy in the cervical spine can present with diverse symptoms, many of which can be debilitating for patients. Patients with radiculopathy symptoms demonstrate added complexity because of the overlapping symptoms and treatment considerations. The authors sought to assess outcomes in patients with myelopathy presenting with or without concurrent radiculopathy. METHODS: The Quality Outcomes Database, a prospectively collected multi-institutional database, was used to analyze demographic, clinical, and surgical variables of patients presenting with myelopathy or myeloradiculopathy as a result of degenerative pathology. Outcome measures included arm (VAS-arm) and neck (VAS-neck) visual analog scale (VAS) scores, modified Japanese Orthopaedic Association (mJOA) scale score, EuroQol VAS (EQ-VAS) score, and Neck Disability Index (NDI) at 3, 12, and 24 months compared with baseline. RESULTS: A total of 1015 patients were included in the study: 289 patients with myelopathy alone (M0), 239 with myeloradiculopathy but no arm pain (MRAP-), and 487 patients with myeloradiculopathy and arm pain (MRAP+). M0 patients were older than the myeloradiculopathy cohorts combined (M0 64.2 vs MRAP- + MRAP+ 59.5 years, p < 0.001), whereas MRAP+ patients had higher BMI and a greater incidence of current smoking compared with the other cohorts. There were more anterior approaches used in in MRAP+ patients and more posterior approaches used in M0 patients. In severely myelopathic patients (mJOA scale score ≤ 10), posterior approaches were used more often for M0 (p < 0.0001) and MRAP+ (p < 0.0001) patients. Patients with myelopathy and myeloradiculopathy both exhibited significant improvement at 1 and 2 years across all outcome domains. The amount of improvement did not vary based on surgical approach. In comparing cohort outcomes, postoperative outcome differences were associated with patient-reported scores at baseline. CONCLUSIONS: Patients with myelopathy and those with myeloradiculopathy demonstrated significant and similar improvement in arm and neck pain scores, myelopathy, disability, and quality of life at 3 months that was sustained at 1- and 2-year follow-up intervals. More radicular symptoms and arm pain increased the likelihood of a surgeon choosing an anterior approach, whereas more severe myelopathy increased the likelihood of approaching posteriorly. Surgical approach itself was not an independent predictor of outcome.

Does comorbid depression and anxiety portend poor long-term outcomes following surgery for lumbar spondylolisthesis? Five-year analysis of the Quality Outcomes Database.

OBJECTIVE: Depression and anxiety are associated with poor outcomes following spine surgery. However, the influence of these conditions on achieving a minimal clinically important difference (MCID) following lumbar spine surgery, as well as the potential compounding effects of comorbid depression and anxiety, is not well understood. This study explores the impact of comorbid depression and anxiety on long-term clinical outcomes following surgical treatment for degenerative lumbar spondylolisthesis. METHODS: This study was a retrospective analysis of the multicenter, prospectively collected Quality Outcomes Database (QOD). Patients with surgically treated grade 1 lumbar spondylolisthesis from 12 centers were included. Preoperative baseline characteristics and comorbidities were recorded, including self-reported depression and/or anxiety. Pre- and postoperative patient-reported outcomes (PROs) were recorded: the numeric rating scale (NRS) score for back pain (NRS-BP), NRS score for leg pain (NRS-LP), Oswestry Disability Index (ODI), and EQ-5D. Patients were grouped into 3 cohorts: no self-reported depression or anxiety (non-SRD/A), self-reported depression or anxiety (SRD/A), or presence of both comorbidities (SRD+A). Changes in PROs over time, satisfaction rates, and rates of MCID were compared. A multivariable regression analysis was performed to establish independent associations. RESULTS: Of the 608 patients, there were 452 (74.3%) with non-SRD/A, 81 (13.3%) with SRD/A, and 75 (12.3%) with SRD+A. Overall, 91.8% and 80.4% of patients had ≥ 24 and ≥ 60 months of follow-up, respectively. Baseline PROs were universally inferior for the SRD+A cohort. However, at 60-month follow-up, changes in all PROs were greatest for the SRD+A cohort, resulting in nonsignificant differences in absolute NRS-BP, NRS-LP, ODI, and EQ-5D across the 3 groups. MCID was achieved for the SRD+A cohort at similar rates to the non-SRD/A cohort. All groups achieved > 80% satisfaction rates with surgery without significant differences across the cohorts (p = 0.79). On multivariable regression, comorbid depression and anxiety were associated with worse baseline PROs, but they had no impact on 60-month PROs or 60-month achievement of MCIDs. CONCLUSIONS: Despite lower baseline PROs, patients with comorbid depression and anxiety achieved comparable rates of MCID and satisfaction after surgery for lumbar spondylolisthesis to those without either condition. This quality-of-life benefit was durable at 5-year follow-up. These data suggest that patients with self-reported comorbid depression and anxiety should not be excluded from consideration of surgical intervention and often substantially benefit from surgery.

Machine learning in the diagnosis, management, and care of patients with low back pain: a scoping review of the literature and future directions.

BACKGROUND CONTEXT: Low back pain (LBP) remains the leading cause of disability globally. In recent years, machine learning (ML) has emerged as a potentially useful tool to aid the diagnosis, management, and prognostication of LBP. PURPOSE: In this review, we assess the scope of ML applications in the LBP literature and outline gaps and opportunities. STUDY DESIGN/SETTING: A scoping review was performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. METHODS: Articles were extracted from the Web of Science, Scopus, PubMed, and IEEE Xplore databases. Title/abstract and full-text screening was performed by two reviewers. Data on model type, model inputs, predicted outcomes, and ML methods were collected. RESULTS: In total, 223 unique studies published between 1988 and 2023 were identified, with just over 50% focused on low-back-pain detection. Neural networks were used in 106 of these articles. Common inputs included patient history, demographics, and lab values (67% total). Articles published after 2010 were also likely to incorporate imaging data into their models (41.7% of articles). Of the 212 supervised learning articles identified, 168 (79.4%) mentioned use of a training or testing dataset, 116 (54.7%) utilized cross-validation, and 46 (21.7%) implemented hyperparameter optimization. Of all articles, only 8 included external validation and 9 had publicly available code. CONCLUSIONS: Despite the rapid application of ML in LBP research, a majority of articles do not follow standard ML best practices. Furthermore, over 95% of articles cannot be reproduced or authenticated due to lack of code availability. Increased collaboration and code sharing are needed to support future growth and implementation of ML in the care of patients with LBP.

Intraoperative fluid management in adult spinal deformity surgery: variation analysis and association with outcomes.

PURPOSE: To evaluate the variability in intraoperative fluid management during adult spinal deformity (ASD) surgery, and analyze the association with complications, intensive care unit (ICU) requirement, and length of hospital stay (LOS). METHODS: Multicenter comparative cohort study. Patients ≥ 18 years old and with ASD were included. Intraoperative intravenous (IV) fluid data were collected including: crystalloids, colloids, crystalloid/colloid ratio (C/C), total IV fluid (tIVF, ml), normalized total IV fluid (nIVF, ml/kg/h), input/output ratio (IOR), input-output difference (IOD), and normalized input-output difference (nIOD, ml/kg/h). Data from different centers were compared for variability analysis, and fluid parameters were analyzed for possible associations with the outcomes. RESULTS: Seven hundred ninety-eight patients with a median age of 65.2 were included. Among different surgical centers, tIVF, nIVF, and C/C showed significant variation (p < 0.001 for each) with differences of 4.8-fold, 3.7-fold, and 4.9-fold, respectively. Two hundred ninety-two (36.6%) patients experienced at least one in-hospital complication, and ninety-two (11.5%) were IV fluid related. Univariate analysis showed significant relations for: LOS and tIVF (ρ = 0.221, p < 0.001), IOD (ρ = 0.115, p = 0.001) and IOR (ρ = -0.138, p < 0.001); IV fluid-related complications and tIVF (p = 0.049); ICU stay and tIVF, nIVF, IOD and nIOD (p < 0.001 each); extended ICU stay and tIVF (p < 0.001), nIVF (p = 0.010) and IOD (p < 0.001). Multivariate analysis controlling for confounders showed significant relations for: LOS and tIVF (p < 0.001) and nIVF (p = 0.003); ICU stay and IOR (p = 0.002), extended ICU stay and tIVF (p = 0.004). CONCLUSION: Significant variability and lack of standardization in intraoperative IV fluid management exists between different surgical centers. Excessive fluid administration was found to be correlated with negative outcomes. LEVEL OF EVIDENCE: III.

Predictors of patient satisfaction after surgery for grade 1 degenerative spondylolisthesis: a 5-year analysis of the Quality Outcomes Database.

OBJECTIVE: Lumbar decompression and/or fusion surgery is a common operation for symptomatic lumbar spondylolisthesis refractory to conservative management. Multiyear follow-up of patient outcomes can be difficult to obtain but allows for identification of preoperative patient characteristics associated with durable pain relief, improved functional outcome, and higher patient satisfaction. METHODS: A query of the Quality Outcomes Database (QOD) low-grade spondylolisthesis module for patients who underwent surgery for grade 1 lumbar spondylolisthesis (from July 2014 to June 2016 at the 12 highest-enrolling sites) was used to identify patient satisfaction, as measured with the North American Spine Society (NASS) questionnaire, which uses a scale of 1-4. Patients were considered satisfied if they had a score ≤ 2. Multivariable logistic regression was performed to identify baseline demographic and clinical predictors of long-term satisfaction 5 years after surgery. RESULTS: Of 573 eligible patients from a cohort of 608, patient satisfaction data were available for 81.2%. Satisfaction (NASS score of 1 or 2) was reported by 389 patients (83.7%) at 5-year follow-up. Satisfied patients were predominantly White and ambulation independent and had lower baseline BMI, lower back pain levels, lower Oswestry Disability Index (ODI) scores, and greater EQ-5D index scores at baseline when compared to the unsatisfied group. No significant differences in reoperation rates between groups were reported at 5 years. On multivariate analysis, patients who were independently ambulating at baseline had greater odds of long-term satisfaction (OR 1.12, p = 0.04). Patients who had higher 5-year ODI scores (OR 0.99, p < 0.01) and were uninsured (OR 0.43, p = 0.01) were less likely to report long-term satisfaction. CONCLUSIONS: Lumbar surgery for the treatment of grade 1 spondylolisthesis can provide lasting pain relief with high patient satisfaction. Baseline independent ambulation is associated with a higher long-term satisfaction rate after surgery. Higher ODI scores at 5-year follow-up and uninsured status are associated with lower postoperative long-term satisfaction.

Impact of Prior Cervical Fusion on Patients Undergoing Thoracolumbar Deformity Correction.

STUDY DESIGN: Retrospective analysis of prospectively collected data. OBJECTIVE: Evaluate the impact of prior cervical constructs on upper instrumented vertebrae (UIV) selection and postoperative outcomes among patients undergoing thoracolumbar deformity correction. BACKGROUND: Surgical planning for adult spinal deformity (ASD) patients involves consideration of spinal alignment and existing fusion constructs. METHODS: ASD patients with (ANTERIOR or POSTERIOR) and without (NONE) prior cervical fusion who underwent thoracolumbar fusion were included. Demographics, radiographic alignment, patient-reported outcome measures (PROMs), and complications were compared. Univariate and multivariate analyses were performed on POSTERIOR patients to identify parameters predictive of UIV choice and to evaluate postoperative outcomes impacted by UIV selection. RESULTS: Among 542 patients, with 446 NONE, 72 ANTERIOR, and 24 POSTERIOR patients, mean age was 64.4 years and 432 (80%) were female. Cervical fusion patients had worse preoperative cervical and lumbosacral deformity, and PROMs (P<0.05). In the POSTERIOR cohort, preoperative LIV was frequently below the cervicothoracic junction (54%) and uncommonly (13%) connected to the thoracolumbar UIV. Multivariate analyses revealed that higher preoperative cervical SVA (coeff=-0.22, 95%CI=-0.43--0.01, P=0.038) and C2SPi (coeff=-0.72, 95%CI=-1.36--0.07, P=0.031), and lower preoperative thoracic kyphosis (coeff=0.14, 95%CI=0.01-0.28, P=0.040) and thoracolumbar lordosis (coeff=0.22, 95%CI=0.10-0.33, P=0.001) were predictive of cranial UIV. Two-year postoperatively, cervical patients continued to have worse cervical deformity and PROMs (P<0.05) but had comparable postoperative complications. Choice of thoracolumbar UIV below or above T6, as well as the number of unfused levels between constructs, did not affect patient outcomes. CONCLUSIONS: Among patients who underwent thoracolumbar deformity correction, prior cervical fusion was associated with more severe spinopelvic deformity and PROMs preoperatively. The choice of thoracolumbar UIV was strongly predicted by their baseline cervical and thoracolumbar alignment. Despite their poor preoperative condition, these patients still experienced significant improvements in their thoracolumbar alignment and PROMs after surgery, irrespective of UIV selection. LEVEL OF EVIDENCE: IV.

Spinal cord injury in high-risk complex adult spinal deformity surgery: review of incidence and outcomes from the Scoli-RISK-1 study.

STUDY DESIGN: Clinical case series. OBJECTIVE: To describe the cause, treatment and outcome of 6 cases of perioperative spinal cord injury (SCI) in high-risk adult deformity surgery. SETTING: Adult spinal deformity patients were enrolled in the multi-center Scoli-RISK-1 cohort study. METHODS: A total of 272 patients who underwent complex adult deformity surgery were enrolled in the prospective, multi-center Scoli-RISK-1 cohort study. Clinical follow up data were available up to a maximum of 2 years after index surgery. Cases of perioperative SCI were identified and an extensive case review was performed. RESULTS: Six individuals with SCI were identified from the Scoli-RISK-1 database (2.2%). Two cases occurred intraoperatively and four cases occurred postoperatively. The first case was an incomplete SCI due to a direct intraoperative insult and was treated postoperatively with Riluzole. The second SCI case was caused by a compression injury due to overcorrection of the deformity. Three cases of incomplete SCI occurred; one case of postoperative hematoma, one case of proximal junctional kyphosis (PJK) and one case of adjacent segment disc herniation. All cases of post-operative incomplete SCI were managed with revision decompression and resulted in excellent clinical recovery. One case of incomplete SCI resulted from infection and PJK. The patient's treatment was complicated by a delay in revision and the patient suffered persistent neurological deficits up to six weeks following the onset of SCI. CONCLUSION: Despite the low incidence in high-risk adult deformity surgeries, perioperative SCI can result in devastating consequences. Thus, appropriate postoperative care, follow up and timely management of SCI are essential.

Predictors of patient satisfaction in the surgical treatment of cervical spondylotic myelopathy.

OBJECTIVE: Patients with cervical spondylotic myelopathy (CSM) experience progressive neurological impairment. Surgical intervention is often pursued to halt neurological symptom progression and allow for recovery of function. In this paper, the authors explore predictors of patient satisfaction following surgical intervention for CSM. METHODS: This is a retrospective review of prospectively collected data from the multicenter Quality Outcomes Database. Patients who underwent surgical intervention for CSM with a minimum follow-up of 2 years were included. Patient-reported satisfaction was defined as a North American Spine Society (NASS) satisfaction score of 1 or 2. Patient demographics, surgical parameters, and outcomes were assessed as related to patient satisfaction. Patient quality of life scores were measured at baseline and 24-month time points. Univariate regression analyses were performed using the chi-square test or Student t-test to assess patient satisfaction measures. Multivariate logistic regression analysis was conducted to assess for factors predictive of postoperative satisfaction at 24 months. RESULTS: A total of 1140 patients at 14 institutions with CSM who underwent surgical intervention were included, and 944 completed a patient satisfaction survey at 24 months postoperatively. The baseline modified Japanese Orthopaedic Association (mJOA) score was 12.0 ± 2.8. A total of 793 (84.0%) patients reported satisfaction (NASS score 1 or 2) after 2 years. Male and female patients reported similar satisfaction rates (female sex: 47.0% not satisfied vs 48.5% satisfied, p = 0.73). Black race was associated with less satisfaction (26.5% not satisfied vs 13.2% satisfied, p < 0.01). Baseline psychiatric comorbidities, obesity, and length of stay did not correlate with 24-month satisfaction. Crossing the cervicothoracic junction did not affect satisfactory scores (p = 0.19), and minimally invasive approaches were not associated with increased patient satisfaction (p = 0.14). Lower baseline numeric rating scale neck pain scores (5.03 vs 5.61, p = 0.04) and higher baseline mJOA scores (12.28 vs 11.66, p = 0.01) were associated with higher satisfaction rates. CONCLUSIONS: Surgical treatment of CSM results in a high rate of patient satisfaction (84.0%) at the 2-year follow-up. Patients with milder myelopathy report higher satisfaction rates, suggesting that intervention earlier in the disease process may result in greater long-term satisfaction.

Cost-effectiveness of posterior lumbar interbody fusion and/or transforaminal lumbar interbody fusion for grade 1 lumbar spondylolisthesis: a 5-year Quality Outcomes Database study.

OBJECTIVE: Posterior lumbar interbody fusion (PLIF) and/or transforaminal lumbar interbody fusion (TLIF), referred to as "PLIF/TLIF," is a commonly performed operation for lumbar spondylolisthesis. Its long-term cost-effectiveness has not been well described. The aim of this study was to determine the 5-year cost-effectiveness of PLIF/TLIF for grade 1 degenerative lumbar spondylolisthesis using prospective data collected from the multicenter Quality Outcomes Database (QOD). METHODS: Patients enrolled in the prospective, multicenter QOD grade 1 lumbar spondylolisthesis module were included if they underwent single-stage PLIF/TLIF. EQ-5D scores at baseline, 3 months, 12 months, 24 months, 36 months, and 60 months were used to calculate gains in quality-adjusted life years (QALYs) associated with surgery relative to preoperative baseline. Healthcare-related costs associated with the index surgery and related reoperations were calculated using Medicare reimbursement-based cost estimates and validated using price transparency diagnosis-related group (DRG) charges and Medicare charge-to-cost ratios (CCRs). Cost per QALY gained over 60 months postoperatively was assessed. RESULTS: Across 12 surgical centers, 385 patients were identified. The mean patient age was 60.2 (95% CI 59.1-61.3) years, and 38% of patients were male. The reoperation rate was 5.7%. DRG 460 cost estimates were stable between our Medicare reimbursement-based models and the CCR-based model, validating the focus on Medicare reimbursement. Across the entire cohort, the mean QALY gain at 60 months postoperatively was 1.07 (95% CI 0.97-1.18), and the mean cost of PLIF/TLIF was $31,634. PLIF/TLIF was associated with a mean 60-month cost per QALY gained of $29,511. Among patients who did not undergo reoperation (n = 363), the mean 60-month QALY gain was 1.10 (95% CI 0.99-1.20), and cost per QALY gained was $27,591. Among those who underwent reoperation (n = 22), the mean 60-month QALY gain was 0.68 (95% CI 0.21-1.15), and the cost per QALY gained was $80,580. CONCLUSIONS: PLIF/TLIF for degenerative grade 1 lumbar spondylolisthesis was associated with a mean 60-month cost per QALY gained of $29,511 with Medicare fees. This is far below the well-established societal willingness-to-pay threshold of $100,000, suggesting long-term cost-effectiveness. PLIF/TLIF remains cost-effective for patients who undergo reoperation.

Thoracolumbar fusions for adult lumbar deformity show superior QALY gain and lower costs compared with upper thoracic fusions.

PURPOSE: Adult spinal deformity (ASD) patients with sagittal plane deformity (N) or structural lumbar/thoraco-lumbar (TL) curves can be treated with fusions stopping at the TL junction or extending to the upper thoracic (UT) spine. This study evaluates the impact on cost/cumulative quality-adjusted life year (QALY) in patients treated with TL vs UT fusion. METHODS: ASD patients with > 4-level fusion and 2-year follow-up were included. Index and total episode-of-care costs were estimated using average itemized direct costs obtained from hospital records. Cumulative QALY gained were calculated from preoperative to 2-year postoperative change in Short Form Six-Dimension (SF-6D) scores. The TL and UT groups comprised patients with upper instrumented vertebrae (UIV) at T9-T12 and T2-T5, respectively. RESULTS: Of 566 patients with type N or L curves, mean age was 63.2 ± 12.1 years, 72% were female and 93% Caucasians. Patients in the TL group had better sagittal vertical axis (7.3 ± 6.9 vs. 9.2 ± 8.1 cm, p = 0.01), lower surgical invasiveness (- 30; p < 0.001), and shorter OR time (- 35 min; p = 0.01). Index and total costs were 20% lower in the TL than in the UT group (p < 0.001). Cost/QALY was 65% lower (492,174.6 vs. 963,391.4), and 2-year QALY gain was 40% higher, in the TL than UT group (0.15 vs. 0.10; p = 0.02). Multivariate model showed TL fusions had lower total cost (p = 0.001) and higher QALY gain (p = 0.03) than UT fusions. CONCLUSION: In Schwab type N or L curves, TL fusions showed lower 2-year cost and improved QALY gain without increased reoperation rates or length of stay than UT fusions. LEVEL OF EVIDENCE: III.

Predictors of Delayed Clinical Benefit Following Surgical Treatment for Low Grade Spondylolisthesis.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: To investigate what factors predict delayed improvement after surgical treatment of low grade spondylolisthesis. SUMMARY OF BACKGROUND DATA: Lumbar surgery leads to clinical improvement in the majority of patients with low grade spondylolisthesis. Most patients improve rapidly after surgery, but some patients demonstrate a delayed clinical course. METHODS: The Quality and Outcomes Database (QOD) was queried for grade 1 spondylolisthesis patients who underwent surgery who had patient reported outcome measures (PROMs) collected at baseline, 3-, 6- and 12-months, including back and leg pain numeric rating scale (NRS), Oswestry Disability Index (ODI), and EuroQol-5D (EQ-5D). Patients were stratified as "Early responders" reaching MCID at 3 months and maintaining improvement through 12 months and "Delayed responders" not reaching MCID at 3 months but ultimately reaching MCID at 12 months. These two groups were compared with respect to factors which predicted delayed improvement. RESULTS: Of 608 patients enrolled, 436 (72%) met inclusion criteria for this study. Overall, 317 patients (72.7%) reached MCID for ODI at 12 months following surgery. Of these patients, 249 (78.5%) exhibited a rapid clinical improvement trajectory and had achieved ODI MCID threshold by the 3-month postop follow-up. 68 patients (21.4%) showed a delayed trajectory, and had not achieved ODI MCID threshold at 3 months, but did ultimately reach MCID at 12-month follow-up. Factors associated with delayed improvement included impaired preoperative ambulatory status, better baseline back and leg pain scores, and worse 3-month leg pain scores (P<0.01). CONCLUSIONS: The majority of patients undergoing surgery for low grade spondylolisthesis reach ODI MCID threshold rapidly, within the first three months after surgery. Factors associated with a delayed clinical course include impaired preoperative ambulation status, relatively better preoperative back and leg pain, and persistent leg pain at 3 months.

Shifting Trends in the Epidemiology of Cervical Spine Injuries: An Analysis of 11,822 Patients from the National Electronic Injury Surveillance System over Two Decades.

Cervical spine injuries (CSIs) are heterogeneous in nature and often lead to long-term disability and morbidity. However, there are few recent and comprehensive epidemiological studies on CSI. The objective of this study was to characterize recent trends in CSI patient demographics, incidence, etiology, and injury level. The National Electronic Injury Surveillance System was used to extract data on CSIs from 2002 to 2022. Weighted national estimates of CSI incidence were computed using yearly population estimates interpolated from U.S. census data. Data analysis involved extracting additional information from patient narratives to categorize injury etiology (i.e., fall) and identify CSI level. K-means clustering was performed on cervical levels to define upper versus lower cervical injuries. Appropriate summary statistics including mean with 95% confidence intervals and frequency were reported for age, sex, race, ethnicity, etiology, and disposition. Age between groups was compared using an independent weighted Z-test. All categorical variables were compared using Pearson chi-squared tests with Bonferroni correction for multiple comparisons. Ordinary least squares linear regression was used to quantify the rate of change of various metrics with time. A total of 11,822 patient records met the study criteria. The mean age of patients was 62.4 ± 22.7 years, 52.4% of whom were male and 61.4% of whom were White, 7.4% were Black, 27.8% were not specified, and the remaining comprised a variety of ethnicities. The most common mechanism of CSI was a fall (67.3%). There was a significant increase in the incidence of cervical injuries between 2003 and 2022 (p < 0.001). Unbiased K-means clustering defined upper cervical injuries as C1-C3 and lower cervical injuries as C4-C7. The mean age of patients with upper CSIs was 72.3 ± 19.6, significantly greater than the age of those with lower CSIs (57.1 ± 23.1, p < 0.001). Compared with lower CSI, White patients were more likely to have an upper CSI (67.4% vs. 73.7%; p < 0.001). While Black/African American (7.5% vs. 3.8%) and Hispanic (2.5% vs. 1.0%) patients were more likely to have a lower CSI (p < 0.001). Our study identified a significant increase in the incidence of CSIs over time, which was associated with increasing patient age. Our study detected a pragmatic demarcation of classifying upper injuries as C1-C3 and lower cervical injuries as C4-C7. Upper injuries were seen more often in older, White females who were treated and admitted, and lower injuries were seen more often in young, Black male patients who were released without admission.