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Objective: The objective of this study was to identify baseline patient and surgical factors predictive of optimal outcomes in staged versus same-day combined-approach surgery., Methods: Adult spinal deformity (ASD) patients with baseline and perioperative (by 6 weeks) data were stratified based on single-stage (same-day) or multistage (staged) surgery, excluding planned multiple hospitalizations. Means comparison analyses were used to assess baseline demographic, radiographic, and surgical differences between cohorts. Backstep logistic regression and conditional inference tree analysis were used to identify variable thresholds associated with study-specific definitions of an optimal outcome in each cohort, defined as no intraoperative or surgery-related in-hospital adverse event., Results: There were 439 patients with complex ASD in the dataset (mean age 64.0 ± 9.3 years, 68% female, mean BMI 28.7 ± 5.5 kg/m2). Overall, 58.8% of patients were in the same-day group, while 41.2% were in the staged group. Demographically, cohorts were not significantly different (p > 0.05), but staged patients were more frail per total Edmonton Frail Scale score (p = 0.043). Staged patients also reported greater numeric rating scale scores for back pain than same-day patients (p = 0.002). Cohorts were comparable in magnitude of planned correction of C7-S1 sagittal vertical axis, pelvic incidence-lumbar lordosis (PI-LL) mismatch, and T4-12 kyphosis (all p > 0.05). Controlling for baseline age, frailty, and number of levels fused, staged patients reported significantly higher PROMIS Discretionary Social Activities scores by 6 weeks (p = 0.029). Radiographic outcomes by 6 weeks were comparable between cohorts, in terms of both magnitude of change from baseline and overall result (all p > 0.05). Same-day patients were significantly more likely to experience in-hospital complications (p = 0.013). When considering frailty thresholds for staging, only a Charlson Comorbidity Index ≤ 1.0 was associated with optimal outcome in same-day patients, while Edmonton Frail Scale score ≥ 7 (p = 0.036), ≥ 9 levels fused (p = 0.016), and baseline PI-LL mismatch ≥ 15.3° (p = 0.028) were associated with optimal outcome for staged patients. Yet, staging alone was not significantly associated with an optimal outcome perioperatively (p = 0.056)., Conclusions: While staged and same-day combined-approach surgeries yield comparable radiographic and patient-reported outcomes, certain subsets of complex ASD patients may benefit from staged surgery despite the invariably increased hospital length of stay. Individuals with increased frailty, moderate to severe PI-LL mismatch, and increased anticipated number of levels fused may experience a lower risk of perioperative adverse events if they undergo a staged procedure. Clinical trial registration no.: NCT04194138 (ClinicalTrials.gov).

Objective: Sagittal alignment measured on standing radiography remains a fundamental component of surgical planning for adult spinal deformity (ASD). However, the relationship between classic sagittal alignment parameters and objective metrics, such as walking time (WT) and grip strength (GS), remains unknown. The objective of this work was to determine if ASD patients with worse baseline sagittal malalignment have worse objective physical metrics and if those metrics have a stronger relationship to patient-reported outcome metrics (PROMs) than standing alignment., Methods: The authors conducted a retrospective review of a multicenter ASD cohort. ASD patients underwent baseline testing with the timed up-and-go 6-m walk test (seconds) and for GS (pounds). Baseline PROMs were surveyed, including Oswestry Disability Index (ODI), Patient-Reported Outcomes Measurement Information System (PROMIS), Scoliosis Research Society (SRS)-22r, and Veterans RAND 12 (VR-12) scores. Standard spinopelvic measurements were obtained (sagittal vertical axis [SVA], pelvic tilt [PT], and mismatch between pelvic incidence and lumbar lordosis [PI-LL], and SRS-Schwab ASD classification). Univariate and multivariable linear regression modeling was performed to interrogate associations between objective physical metrics, sagittal parameters, and PROMs., Results: In total, 494 patients were included, with mean ± SD age 61 ± 14 years, and 68% were female. Average WT was 11.2 ± 6.1 seconds and average GS was 56.6 ± 24.9 lbs. With increasing PT, PI-LL, and SVA quartiles, WT significantly increased (p < 0.05). SRS-Schwab type N patients demonstrated a significantly longer average WT (12.5 ± 6.2 seconds), and type T patients had a significantly shorter WT time (7.9 ± 2.7 seconds, p = 0.03). With increasing PT quartiles, GS significantly decreased (p < 0.05). SRS-Schwab type T patients had a significantly higher average GS (68.8 ± 27.8 lbs), and type L patients had a significantly lower average GS (51.6 ± 20.4 lbs, p = 0.03). In the frailty-adjusted multivariable linear regression analyses, WT was more strongly associated with PROMs than sagittal parameters. GS was more strongly associated with ODI and PROMIS Physical Function scores., Conclusions: The authors observed that increasing baseline sagittal malalignment is associated with slower WT, and possibly weaker GS, in ASD patients. WT has a stronger relationship to PROMs than standing alignment parameters. Objective physical metrics likely offer added value to standard spinopelvic measurements in ASD evaluation and surgical planning.

Objective: Complex spinal deformity surgeries may involve significant blood loss. The use of antifibrinolytic agents such as tranexamic acid (TXA) has been proven to reduce perioperative blood loss. However, for patients with a history of thromboembolic events, there is concern of increased risk when TXA is used during these surgeries. This study aimed to assess whether TXA use in patients undergoing complex spinal deformity correction surgeries increases the risk of thromboembolic complications based on preexisting thromboembolic risk factors., Methods: Data were analyzed for adult patients who received TXA during surgical correction for spinal deformity at 21 North American centers between August 2018 and October 2022. Patients with preexisting thromboembolic events and other risk factors (history of deep venous thrombosis [DVT], pulmonary embolism [PE], myocardial infarction [MI], stroke, peripheral vascular disease, or cancer) were identified. Thromboembolic complication rates were assessed during the postoperative 90 days. Univariate and multivariate analyses were performed to assess thromboembolic outcomes in high-risk and low-risk patients who received intravenous TXA., Results: Among 411 consecutive patients who underwent complex spinal deformity surgery and received TXA intraoperatively, 130 (31.6%) were considered high-risk patients. There was no significant difference in thromboembolic complications between patients with and those without preexisting thromboembolic risk factors in univariate analysis (high-risk group vs low-risk group: 8.5% vs 2.8%, p = 0.45). Specifically, there were no significant differences between groups regarding the 90-day postoperative rates of DVT (high-risk group vs low-risk group: 1.5% vs 1.4%, p = 0.98), PE (2.3% vs 1.8%, p = 0.71), acute MI (1.5% vs 0%, p = 0.19), or stroke (0.8% vs 1.1%, p > 0.99). On multivariate analysis, high-risk status was not a significant independent predictor for any of the thromboembolic complications., Conclusions: Administration of intravenous TXA during the correction procedure did not change rates of thromboembolic events, acute MI, or stroke in this cohort of adult spinal deformity surgery patients.

Objective: The objective was to determine the degree of regional decompensation to pelvic tilt (PT) normalization after complex adult spinal deformity (ASD) surgery., Methods: Operative ASD patients with 1 year of PT measurements were included. Patients with normalized PT at baseline were excluded. Predicted PT was compared to actual PT, tested for change from baseline, and then compared against age-adjusted, Scoliosis Research Society-Schwab, and global alignment and proportion (GAP) scores. Lower-extremity (LE) parameters included the cranial-hip-sacrum angle, cranial-knee-sacrum angle, and cranial-ankle-sacrum angle. LE compensation was set as the 1-year upper tertile compared with intraoperative baseline. Univariate analyses were used to compare normalized and nonnormalized data against alignment outcomes. Multivariable logistic regression analyses were used to develop a model consisting of significant predictors for normalization related to regional compensation., Results: In total, 156 patients met the inclusion criteria (mean ± SD age 64.6 ± 9.1 years, BMI 27.9 ± 5.6 kg/m2, Charlson Comorbidity Index 1.9 ± 1.6). Patients with normalized PT were more likely to have overcorrected pelvic incidence minus lumbar lordosis and sagittal vertical axis at 6 weeks (p < 0.05). GAP score at 6 weeks was greater for patients with nonnormalized PT (0.6 vs 1.3, p = 0.08). At baseline, 58.5% of patients had compensation in the thoracic and cervical regions. Postoperatively, compensation was maintained by 42% with no change after matching in age-adjusted or GAP score. The patients with nonnormalized PT had increased rates of thoracic and cervical compensation (p < 0.05). Compensation in thoracic kyphosis differed between patients with normalized PT at 6 weeks and those with normalized PT at 1 year (69% vs 35%, p < 0.05). Those who compensated had increased rates of implant complications by 1 year (OR [95% CI] 2.08 [1.32-6.56], p < 0.05). Cervical compensation was maintained at 6 weeks and 1 year (56% vs 43%, p = 0.12), with no difference in implant complications (OR 1.31 [95% CI -2.34 to 1.03], p = 0.09). For the lower extremities at baseline, 61% were compensating. Matching age-adjusted alignment did not eliminate compensation at any joint (all p > 0.05). Patients with nonnormalized PT had higher rates of LE compensation across joints (all p < 0.01). Overall, patients with normalized PT at 1 year had the greatest odds of resolving LE compensation (OR 9.6, p < 0.001). Patients with normalized PT at 1 year had lower rates of implant failure (8.9% vs 19.5%, p < 0.05), rod breakage (1.3% vs 13.8%, p < 0.05), and pseudarthrosis (0% vs 4.6%, p < 0.05) compared with patients with nonnormalized PT. The complication rate was significantly lower for patients with normalized PT at 1 year (56.7% vs 66.1%, p = 0.02), despite comparable health-related quality of life scores., Conclusions: Patients with PT normalization had greater rates of resolution in thoracic and LE compensation, leading to lower rates of complications by 1 year. Thus, consideration of both the lower extremities and thoracic regions in surgical planning is vital to preventing adverse outcomes and maintaining pelvic alignment.

Objective: Surgery for spinal deformity has the potential to improve pain, disability, function, self-image, and mental health. These surgical procedures carry significant risk and require careful selection, optimization, and risk assessment. Epigenetic clocks are age estimation tools derived by measuring the methylation patterns of specific DNA regions. The study of biological age in the adult deformity population has the potential to shed insight onto the molecular basis of frailty and to improve current risk assessment tools., Methods: Adult patients who underwent deformity surgery were prospectively enrolled. Preoperative whole blood samples were used to assess epigenetic age and telomere length. DNA methylation patterns were quantified and processed to extract 4 principal component (PC)-based epigenetic age clocks (PC Horvath, PC Hannum, PC PhenoAge, and PC GrimAge) and the instantaneous pace of aging (DunedinPACE). Telomere length was assessed using both quantitative polymerase chain reaction (telomere to single gene [T/S] ratio) and a methylation-based telomere estimator (PC DNAmTL). Patient demographic and surgical data included age, BMI, American Society of Anesthesiologists Physical Status Classification System class, and scores on the Charlson Comorbidity Index, adult spinal deformity frailty index (ASD-FI), Edmonton Frail Scale (EFS), Oswestry Disability Index, and Scoliosis Research Society-22r questionnaire (SRS-22r). Medical or surgical complications within 90 days of surgery were collected. Spearman correlations and beta coefficients (β) from linear regression, adjusted for BMI and sex, were calculated., Results: Eighty-three patients were enrolled with a mean age of 65 years, and 45 were women (54%). All patients underwent posterior fusion with a mean of 11 levels fused and 33 (40%) 3-column osteotomies were performed. Among the epigenetic clocks adjusted for BMI and sex, DunedinPACE showed a significant association with ASD-FI (β = 0.041, p = 0.002), EFS (β = 0.696, p = 0.026), and SRS-22r (β = 0.174, p = 0.013) scores. PC PhenoAge showed associations with ASD-FI (β = 0.029, p = 0.028) and SRS-22r (β = 0.159, p = 0.018) scores. PC GrimAge showed associations with ASD-FI (β = 0.029, p = 0.037) and SRS-22r (β = 0.161, p = 0.025) scores. Patients with postoperative complications were noted to have shorter telomere length (T/S 0.790 vs 0.858, p = 0.049), even when the analysis controlled for BMI and sex (OR = 1.71, 95% CI 1.07-2.87, p = 0.031)., Conclusions: Epigenetic clocks showed significant associations with markers of frailty and disability, while patients with postoperative complications had shorter telomere length. These data suggest a potential role for aging biomarkers as components of surgical risk assessment. Integrating biological age into current risk calculators may improve their accuracy and provide valuable information for patients, surgeons, and payers.

Objective: The authors of this study sought to evaluate the predictive role of global sagittal alignment and upper instrumented vertebra (UIV) level in symptomatic proximal junctional kyphosis (PJK) among patients with adult spinal deformity (ASD)., Methods: Data on ASD patients who had undergone fusion of ≥ 5 vertebrae from 2008 to 2018 and with a minimum follow-up of 1 year were obtained from a prospectively collected multicenter database and evaluated (n = 1312). Radiographs were obtained preoperatively and at 6 weeks, 6 months, 1 year, 2 years, and 3 years postoperatively. The 22-Item Scoliosis Research Society Patient Questionnaire Revised (SRS-22r) scores were collected preoperatively, 1 year postoperatively, and 2 years postoperatively. Symptomatic PJK was defined as a kyphotic increase > 20° in the Cobb angle from the UIV to the UIV+2. At 6 weeks postoperatively, sagittal parameters were evaluated and patients were categorized by global alignment and proportion (GAP) score/category and SRS-Schwab sagittal modifiers. Patients were stratified by UIV level: upper thoracic (UT) UIV ≥ T8 or lower thoracic (LT) UIV ≤ T9., Results: Patients who developed symptomatic PJK (n = 260) had worse 1-year postoperative SRS-22r mental health (3.70 vs 3.86) and total (3.56 vs 3.67) scores, as well as worse 2-year postoperative self-image (3.45 vs 3.65) and satisfaction (4.03 vs 4.22) scores (all p ≤ 0.04). In the whole study cohort, patients with PJK had less pelvic incidence-lumbar lordosis (PI-LL) mismatch (-0.24° vs 3.29°, p < 0.001) but no difference in their GAP score/category or SRS-Schwab sagittal modifiers compared with the patients without PJK. Regression showed a higher risk of PJK with a pelvic tilt (PT) grade ++ (OR 2.35) and less risk with a PI-LL grade ++ (OR 0.35; both p < 0.01). When specifically analyzing the LT UIV cohort, patients with PJK had a higher GAP score (5.66 vs 4.79), greater PT (23.02° vs 20.90°), and less PI-LL mismatch (1.61° vs 4.45°; all p ≤ 0.02). PJK patients were less likely to be proportioned postoperatively (17.6% vs 30.0%, p = 0.015), and regression demonstrated a greater PJK risk with severe disproportion (OR 1.98) and a PT grade ++ (OR 3.15) but less risk with a PI-LL grade ++ (OR 0.45; all p ≤ 0.01). When specifically evaluating the UT UIV cohort, the PJK patients had less PI-LL mismatch (-2.11° vs 1.45°) but no difference in their GAP score/category. Regression showed a greater PJK risk with a PT grade + (OR 1.58) and a decreased risk with a PI-LL grade ++ (OR 0.21; both p < 0.05)., Conclusions: Symptomatic PJK leads to worse patient-reported outcomes and is associated with less postoperative PI-LL mismatch and greater postoperative PT. A worse postoperative GAP score and disproportion are only predictive of symptomatic PJK in patients with an LT UIV.

Objective: The aim of this study was to investigate whether surgery for high-risk patients is being optimized over time and if poor outcomes are being minimized., Methods: Patients who underwent surgery for cervical deformity (CD) and were ≥ 18 years with baseline and 2-year data were stratified by year of surgery from 2013 to 2018. The cohort was divided into two groups based on when the surgery was performed. Patients in the early cohort underwent surgery between 2013 and 2015 and those in the recent cohort underwent surgery between 2016 and 2018. High-risk patients met at least 2 of the following criteria: 1) baseline C2-7 Cobb angle > 15°, mismatch between T1 slope and cervical lordosis ≥ 35°, C2-7 sagittal vertical axis > 4 cm, or chin-brow vertical angle > 25°; 2) age ≥ 70 years; 3) severe baseline frailty (Miller index); 4) Charlson Comorbidity Index (CCI) ≥ 1 SD above the mean; 5) three-column osteotomy as treatment; and 6) fusion > 10 levels or > 7 levels for elderly patients. The mean comparison analysis assessed differences between groups. Stepwise multivariable linear regression described associations between increasing year of surgery and complications., Results: Eighty-two CD patients met high-risk criteria (mean age 62.11 ± 10.87 years, 63.7% female, mean BMI 29.70 ± 8.16 kg/m2, and mean CCI 1.07 ± 1.45). The proportion of high-risk patients increased with time, with 41.8% of patients in the early cohort classified as high risk compared with 47.6% of patients in the recent cohort (p > 0.05). Recent high-risk patients were more likely to be female (p = 0.008), have a lower BMI (p = 0.038), and have a higher baseline CCI (p = 0.013). Surgically, high-risk patients in the recent cohort were more likely to undergo low-grade osteotomy (p = 0.003). By postoperative complications, recent high-risk patients were less likely to experience any postoperative adverse events overall (p = 0.020) or complications such as dysphagia (p = 0.045) at 2 years. Regression analysis revealed increasing year of surgery to be correlated with decreasing minor complication rates (p = 0.030), as well as lowered rates of distal junctional kyphosis by 2 years (p = 0.048)., Conclusions: Over time, high-risk CD patients have an increase in frequency and comorbidity rates but have demonstrated improved postoperative outcomes. These findings suggest that spine surgeons have improved over time in optimizing selection and reducing potential adverse events in high-risk patients.

Objective: Multiple rods are utilized in adult spinal deformity (ASD) surgery to increase construct stiffness. However, the impact of multiple rods on proximal junctional kyphosis (PJK) is not well established. This study aimed to investigate the impact of multiple rods on PJK incidence in ASD patients., Methods: ASD patients from a prospective multicenter database with a minimum follow-up of 1 year were retrospectively reviewed. Clinical and radiographic data were collected preoperatively, at 6 weeks postoperatively, at 6 months postoperatively, at 1 year postoperatively, and at every subsequent year postoperatively. PJK was defined as a kyphotic increase of > 10° in the Cobb angle from the upper instrumented vertebra (UIV) to UIV+2 as compared with preoperative values. Demographic data, radiographic parameters, and PJK incidence were compared between the multirod and dual-rod patient cohorts. PJK-free survival analysis was performed using Cox regression to control for demographic characteristics, comorbidities, level of fusion, and radiographic parameters., Results: Overall, 307/1300 (23.62%) cases utilized multiple rods. Cases with multiple rods were more likely to be revisions (68.4% vs 46.5%, p < 0.001), to be posterior only (80.7% vs 61.5%, p < 0.001), involve more levels of fusion (mean 11.73 vs 10.60, p < 0.001), and include 3-column osteotomy (42.9% vs 17.1%, p < 0.001). Patients with multiple rods also had greater preoperative pelvic retroversion (mean pelvic tilt 27.95° vs 23.58°, p < 0.001), greater thoracolumbar junction kyphosis (-15.9° vs -11.9°, p = 0.001), and more severe sagittal malalignment (C7-S1 sagittal vertical axis 99.76 mm vs 62.23 mm, p < 0.001), all of which corrected postoperatively. Patients with multiple rods had similar incidence rates of PJK (58.6% vs 58.1%) and revision surgery (13.0% vs 17.7%). The PJK-free survival analysis demonstrated equivalent PJK-free survival durations among the patients with multiple rods (HR 0.889, 95% CI 0.745-1.062, p = 0.195) after controlling for demographic and radiographic parameters. Further stratification based on implant metal type demonstrated noninferior PJK incidence rates with multiple rods in the titanium (57.1% vs 54.6%, p = 0.858), cobalt chrome (60.5% vs 58.7%, p = 0.646), and stainless steel (20% vs 63.7%, p = 0.008) cohorts., Conclusions: Multirod constructs for ASD are most frequently utilized in revision, long-level reconstructions with 3-column osteotomy. The use of multiple rods in ASD surgery does not result in an increased incidence of PJK and is not affected by rod metal type.

Objective: The objective of this study was to calibrate an updated predictive model incorporating novel clinical, radiographic, and prophylactic measures to assess the risk of proximal junctional kyphosis (PJK) and failure (PJF)., Methods: Operative patients with adult spinal deformity (ASD) and baseline and 2-year postoperative data were included. PJK was defined as ≥ 10° in sagittal Cobb angle between the inferior uppermost instrumented vertebra (UIV) endplate and superior endplate of the UIV + 2 vertebrae. PJF was radiographically defined as a proximal junctional sagittal Cobb angle ≥ 15° with the presence of structural failure and/or mechanical instability, or PJK with reoperation. Backstep conditional binary supervised learning models assessed baseline demographic, clinical, and surgical information to predict the occurrence of PJK and PJF. Internal cross validation of the model was performed via a 70%/30% cohort split. Conditional inference tree analysis determined thresholds at an alpha level of 0.05., Results: Seven hundred seventy-nine patients with ASD (mean 59.87 ± 14.24 years, 78% female, mean BMI 27.78 ± 6.02 kg/m2, mean Charlson Comorbidity Index 1.74 ± 1.71) were included. PJK developed in 50.2% of patients, and 10.5% developed PJF by their last recorded visit. The six most significant demographic, radiographic, surgical, and postoperative predictors of PJK/PJF were baseline age ≥ 74 years, baseline sagittal age-adjusted score (SAAS) T1 pelvic angle modifier > 1, baseline SAAS pelvic tilt modifier > 0, levels fused > 10, nonuse of prophylaxis measures, and 6-week SAAS pelvic incidence minus lumbar lordosis modifier > 1 (all p < 0.015). Overall, the model was deemed significant (p < 0.001), and internally validated receiver operating characteristic analysis returned an area under the curve of 0.923, indicating robust model fit., Conclusions: PJK and PJF remain critical concerns in ASD surgery, and efforts to reduce the occurrence of PJK and PJF have resulted in the development of novel prophylactic techniques and enhanced clinical and radiographic selection criteria. This study demonstrates a validated model incorporating such techniques that may allow for the prediction of clinically significant PJK and PJF, and thus assist in optimizing patient selection, enhancing intraoperative decision making, and reducing postoperative complications in ASD surgery.

Objective: Vertebral osteomyelitis is a rare complication of coccidioidomycosis infection. Surgical intervention is indicated when there is failure of medical management or presence of neurological deficit, epidural abscess, or spinal instability. The relationship between timing of surgical intervention and recovery of neurological function has not been previously described. The purpose of this study was to investigate if the duration of neurological deficits at presentation affects neurological recovery after surgical intervention., Methods: This was a retrospective study of all patients diagnosed with coccidioidomycosis involving the spine at a single tertiary care center between 2012 and 2021. Data collected included patient demographics, clinical presentation, radiographic information, and surgical intervention. The primary outcome was change in neurological examination after surgical intervention, quantified according to the American Spinal Injury Association Impairment Scale. The secondary outcome was the complication rate. Logistic regression was used to test if the duration of neurological deficits was associated with improvement in the neurological examination after surgery., Results: Twenty-seven patients presented with spinal coccidioidomycosis between 2012 and 2021; 20 of these patients had vertebral involvement on spinal imaging with a median follow-up of 8.7 months (IQR 1.7-71.2 months). Of the 20 patients with vertebral involvement, 12 (60.0%) presented with a neurological deficit with a median duration of 20 days (range 1-61 days). Most patients presenting with neurological deficit (11/12, 91.7%) underwent surgical intervention. Nine (81.2%) of these 11 patients had an improved neurological examination after surgery and the other 2 had stable deficits. Seven patients had improved recovery sufficient to improve by 1 grade according to the AIS. The duration of neurological deficits on presentation was not significantly associated with neurological improvement after surgery (p = 0.49, Fisher's exact test)., Conclusions: The duration of neurological deficits on presentation should not deter surgeons from operative intervention in cases of spinal coccidioidomycosis.

Objective: The objective of this study was to evaluate spinopelvic sagittal alignment and spinal compensatory changes in adult cervical kyphotic deformity., Methods: A database composed of 13 US spine centers was retrospectively reviewed for adult patients who underwent cervical reconstruction with radiographic evidence of cervical kyphotic deformity: C2-7 sagittal vertical axis > 4 cm, chin-brow vertical angle > 25°, or cervical kyphosis (T1 slope [T1S] cervical lordosis [CL] > 15°) (n = 129). Sagittal parameters were evaluated preoperatively and in the early postoperative window (6 weeks to 6 months postoperatively) and compared with asymptomatic control patients. Adult cervical deformity patients were further stratified by degree of cervical kyphosis (severe kyphosis, C2-T3 Cobb angle ≤ -30°; moderate kyphosis, ≤ 0°; and minimal kyphosis, > 0°) and severity of sagittal malalignment (severe malalignment, sagittal vertical axis T3-S1 ≤ -60 mm; moderate malalignment, ≤ 20 mm; and minimal malalignment > 20 mm)., Results: Compared with asymptomatic control patients, cervical deformity was associated with increased C0-2 lordosis (32.9° vs 23.6°), T1S (33.5° vs 28.0°), thoracolumbar junction kyphosis (T10-L2 Cobb angle -7.0° vs -1.7°), and pelvic tilt (PT) (19.7° vs 15.9°) (p < 0.01). Cervicothoracic kyphosis was correlated with C0-2 lordosis (R = -0.57, p < 0.01) and lumbar lordosis (LL) (R = -0.20, p = 0.03). Cervical reconstruction resulted in decreased C0-2 lordosis, increased T1S, and increased thoracic and thoracolumbar junction kyphosis (p < 0.01). Patients with severe cervical kyphosis (n = 34) had greater C0-2 lordosis (p < 0.01) and postoperative reduction of C0-2 lordosis (p = 0.02) but no difference in PT. Severe cervical kyphosis was also associated with a greater increase in thoracic and thoracolumbar junction kyphosis postoperatively (p = 0.01). Patients with severe sagittal malalignment (n = 52) had decreased PT (p = 0.01) and increased LL (p < 0.01), as well as a greater postoperative reduction in LL (p < 0.01)., Conclusions: Adult cervical deformity is associated with upper cervical hyperlordotic compensation and thoracic hypokyphosis. In the setting of increased kyphotic deformity and sagittal malalignment, thoracolumbar junction kyphosis and lumbar hyperlordosis develop to restore normal center of gravity. There was no consistent compensatory pelvic retroversion or anteversion among the adult cervical deformity patients in this cohort.

Objective: Risk stratification is a critical element of surgical planning. Early tools were fairly crude, while newer instruments incorporate disease-specific elements and markers of frailty. It is unknown if discrepancies between chronological and cellular age can guide surgical planning or treatment. Telomeres are DNA-protein complexes that serve an important role in protecting genomic DNA. Their shortening is a consequence of aging and environmental exposures, with well-established associations with diseases of aging and mortality. There are compelling data to suggest that telomere length can provide insight toward overall health. The authors sought to determine potential associations between telomere length and postoperative complications., Methods: Adults undergoing elective surgery for spinal deformity were prospectively enrolled. Telomere length was measured from preoperative whole blood using quantitative polymerase chain reaction and expressed as the ratio of telomere (T) to single-copy gene (S) abundance (T/S ratio), with higher T/S ratios indicating longer telomere length. Demographic and patient data included age, BMI, and results for the following rating scales: the Adult Spinal Deformity Frailty Index (ASD-FI), Oswestry Disability Index (ODI), Scoliosis Research Society-22r (SRS-22r), American Society of Anesthesiology (ASA) classification, and Charlson Comorbidity Index (CCI). Operative and postoperative complication data (medical or surgical within 90 days) were also collected., Results: Forty-three patients were enrolled, including 31 women (53%), with a mean age of 66 years and a mean BMI of 28.5. The mean number of levels fused was 11, with 21 (48.8%) combined anterior-posterior approaches. Twenty-two patients (51.2%) had a medical or surgical complication. Patients with a postoperative complication had a significantly lower T/S ratio (0.712 vs 0.813, p = 0.008), indicating shorter telomere length, despite a mild difference in age compared with patients without a postoperative complication (68 vs 63 years, p = 0.069). Patients with complications also had higher CCI scores than patients without complications (2.3 vs 3.8, p = 0.004). There were no significant differences in sex, BMI, ASD-FI score, ASA class, preoperative ODI and SRS-22r scores, number of levels fused, or use of three-column osteotomies. In a multivariate model including age, frailty, ASA class, use of an anterior-posterior approach, CCI score, and telomere length, the authors found that short telomere length was significantly associated with postoperative complications. Patients whose telomere length fell in the shortest quartile had the highest risk (OR 18.184, p = 0.030)., Conclusions: Short telomere length was associated with an increased risk of postoperative complications despite only a mild difference in chronological age. Increasing comorbidity scores also trended toward significance. Larger prospective studies are needed; however, these data provide a compelling impetus to investigate the role of biological aging as a component of surgical risk stratification.

Objective: Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are well-recognized complications of long-segment spinal fusion. Previous studies have suggested that ligament augmentation can decrease rates of PJF by reducing junctional stress and strengthening upper instrumented vertebrae (UIVs) and adjacent segments. However, there is a paucity of long-term data on the efficacy of ligament augmentation in preventing PJF. In this study, the authors sought to determine the effect of ligament augmentation on rates of PJF in a cohort of adult spinal deformity patients with at least 1 year of follow-up., Methods: They conducted a retrospective analysis of ligament augmentation in a consecutive series of surgical patients with adult spinal deformity. Data on patient demographics, surgical characteristics, and surgery for PJF were collected. The minimum follow-up was 12 months. Univariate and multivariate analyses were performed to identify factors associated with reoperation for PJF., Results: The authors identified a total of 242 patients (166 women [68.6%]) with ligament augmentation whose mean age was 66 years. The mean number of fused levels was 10, with a UIV distribution as follows: 90 upper thoracic UIVs (37.2%) and 152 lower thoracic UIVs (62.8%). Compared to a historical cohort of 77 patients treated before implementation of ligament augmentation, reoperation for PJF was significantly lower with ligament augmentation (15.6% vs 3.3%, p < 0.001). In a multivariate model, only ligament augmentation (OR 0.184, 95% CI 0.071-0.478, p = 0.001) and number of fused levels (OR 0.762, 95% CI 0.620-0.937, p = 0.010) were associated with reductions in reoperation for PJF., Conclusions: Ligament augmentation was associated with significant reductions in the rate of reoperation for PJF at 12 months in a cohort of adult spinal deformity patients. The most dramatic reduction was seen among patients with lower thoracic UIV. These data suggest that in appropriately selected patients, ligament augmentation may be a valuable adjunct for PJF reduction; however, long-term follow-up is needed.

Objective: Anterior lumbar interbody fusion (ALIF) is an effective surgical modality for many lumbar degenerative pathologies, but a rare and infrequently reported complication is postoperative lymphocele. The goals of the present study were to review a large consecutive series of patients who underwent ALIF at a high-volume institution, estimate the rate of lymphocele occurrence after ALIF, and investigate the outcomes of patients who developed lymphocele after ALIF., Methods: A retrospective review of the electronic medical record was completed, identifying all patients (≥ 18 years old) who underwent at a minimum a single-level ALIF from 2012 through 2019. Postoperative spinal and abdominal images, as well as radiologist reports, were reviewed for mention of lymphocele. Clinical data were collected and reported., Results: A total of 1322 patients underwent a minimum 1-level ALIF. Of these patients, 937 (70.9%) had either postoperative abdominal or lumbar spine images, and the resulting lymphocele incidence was 2.1% (20/937 patients). The mean ± SD age was 67 ± 10.9 years, and the male/female ratio was 1:1. Patients with lymphocele were significantly older than those without lymphocele (66.9 vs 58.9 years, p = 0.006). In addition, patients with lymphocele had a greater number of mean levels fused (2.5 vs 1.8, p < 0.001) and were more likely to have undergone ALIF at L2-4 (95.0% vs 66.4%, p = 0.007) than patients without lymphocele. On subsequent multivariate analysis, age (OR 1.07, 95% CI 1.01-1.12, p = 0.013), BMI (OR 1.10, 95% CI 1.01-1.18, p = 0.021), and number of levels fused (OR 1.82, 95% CI 1.05-3.14, p = 0.032) were independent prognosticators of postoperative lymphocele development. Patients with symptomatic lymphocele were successfully treated with either interventional radiology (IR) drainage and/or sclerosis therapy and achieved radiographic resolution. The mean ± SD length of hospital stay was 9.1 ± 5.2 days. Ten patients (50%) were postoperatively discharged to a rehabilitation center: 8 patients (40%) were discharged to home, 1 (5%) to a skilled nursing facility, and 1 (5%) to a long-term acute care facility., Conclusions: After ALIF, 2.1% of patients were diagnosed with radiographically identified postoperative lymphocele and had risk factors such as increased age, BMI, and number of levels fused. Most patients presented within 1 month postoperatively, and their clinical presentations included abdominal pain, abdominal distension, and/or wound complications. Of note, 25% of identified lymphoceles were discovered incidentally. Patients with symptomatic lymphocele were successfully treated with either IR drainage and/or sclerosis therapy and achieved radiographic resolution.

Objective: It is being increasingly recognized that adult cervical deformity (ACD) is correlated with significant pain, myelopathy, and disability, and that patients who undergo deformity correction gain significant benefit. However, there are no defined thresholds of minimum clinically important difference (MCID) in Neck Disability Index (NDI) and modified Japanese Orthopaedic Association (mJOA) scores., Methods: Patients of interest were consecutive patients with ACD who underwent cervical deformity correction. ACD was defined as C2-7 sagittal Cobb angle ≥ 10° (kyphosis), C2-7 coronal Cobb angle ≥ 10° (cervical scoliosis), C2-7 sagittal vertical axis ≥ 4 cm, and/or chin-brow vertical angle ≥ 25°. Data were obtained from a consecutive cohort of patients from a multiinstitutional prospective database maintained across 13 sites. Distribution-based MCID, anchor-based MCID, and minimally detectable measurement difference (MDMD) were calculated., Results: A total of 73 patients met inclusion criteria and had sufficient 1-year follow-up. In the cohort, 42 patients (57.5%) were female. The mean age at the time of surgery was 62.23 years, and average body mass index was 29.28. The mean preoperative NDI was 46.49 and mJOA was 13.17. There was significant improvement in NDI at 1 year (46.49 vs 37.04; p = 0.0001). There was no significant difference in preoperative and 1-year mJOA (13.17 vs 13.7; p = 0.12). Using multiple techniques to yield MCID thresholds specific to the ACD population, the authors obtained values of 5.42 to 7.48 for the NDI, and 1.00 to 1.39 for the mJOA. The MDMD was 6.4 for the NDI, and 1.8 for the mJOA. Therefore, based on their results, the authors recommend using an MCID threshold of 1.8 for the mJOA, and 7.0 for the NDI in patients with ACD., Conclusions: The ACD-specific MCID thresholds for NDI and mJOA are similar to the reported MCID following surgery for degenerative cervical disease. Additional studies are needed to verify these findings. Nonetheless, the findings here will be useful for future studies evaluating the success of surgery for patients with ACD undergoing deformity correction.

Objective: Cervical deformity (CD) correction is clinically challenging. There is a high risk of developing complications with these highly complex procedures. The aim of this study was to use baseline demographic, clinical, and surgical factors to predict a poor outcome following CD surgery., Methods: The authors performed a retrospective review of a multicenter prospective CD database. CD was defined as at least one of the following: cervical kyphosis (C2-7 Cobb angle > 10°), cervical scoliosis (coronal Cobb angle > 10°), C2-7 sagittal vertical axis (cSVA) > 4 cm, or chin-brow vertical angle (CBVA) > 25°. Patients were categorized based on having an overall poor outcome or not. Health-related quality of life measures consisted of Neck Disability Index (NDI), EQ-5D, and modified Japanese Orthopaedic Association (mJOA) scale scores. A poor outcome was defined as having all 3 of the following categories met: 1) radiographic poor outcome: deterioration or severe radiographic malalignment 1 year postoperatively for cSVA or T1 slope-cervical lordosis mismatch (TS-CL); 2) clinical poor outcome: failing to meet the minimum clinically important difference (MCID) for NDI or having a severe mJOA Ames modifier; and 3) complications/reoperation poor outcome: major complication, death, or reoperation for a complication other than infection. Univariate logistic regression followed by multivariate regression models was performed, and internal validation was performed by calculating the area under the curve (AUC)., Results: In total, 89 patients with CD were included (mean age 61.9 years, female sex 65.2%, BMI 29.2 kg/m2). By 1 year postoperatively, 18 (20.2%) patients were characterized as having an overall poor outcome. For radiographic poor outcomes, patients' conditions either deteriorated or remained severe for TS-CL (73% of patients), cSVA (8%), horizontal gaze (34%), and global SVA (28%). For clinical poor outcomes, 80% and 60% of patients did not reach MCID for EQ-5D and NDI, respectively, and 24% of patients had severe symptoms (mJOA score 0-11). For the complications/reoperation poor outcome, 28 patients experienced a major complication, 11 underwent a reoperation, and 1 had a complication-related death. Of patients with a poor clinical outcome, 75% had a poor radiographic outcome; 35% of poor radiographic and 37% of poor clinical outcome patients had a major complication. A poor outcome was predicted by the following combination of factors: osteoporosis, baseline neurological status, use of a transition rod, number of posterior decompressions, baseline pelvic tilt, T2-12 kyphosis, TS-CL, C2-T3 SVA, C2-T1 pelvic angle (C2 slope), global SVA, and number of levels in maximum thoracic kyphosis. The final model predicting a poor outcome (AUC 86%) included the following: osteoporosis (OR 5.9, 95% CI 0.9-39), worse baseline neurological status (OR 11.4, 95% CI 1.8-70.8), baseline pelvic tilt > 20° (OR 0.92, 95% CI 0.85-0.98), > 9 levels in maximum thoracic kyphosis (OR 2.01, 95% CI 1.1-4.1), preoperative C2-T3 SVA > 5.4 cm (OR 1.01, 95% CI 0.9-1.1), and global SVA > 4 cm (OR 3.2, 95% CI 0.09-10.3)., Conclusions: Of all CD patients in this study, 20.2% had a poor overall outcome, defined by deterioration in radiographic and clinical outcomes, and a major complication. Additionally, 75% of patients with a poor clinical outcome also had a poor radiographic outcome. A poor overall outcome was most strongly predicted by severe baseline neurological deficit, global SVA > 4 cm, and including more of the thoracic maximal kyphosis in the construct.

OBJECTIVE Proximal junctional kyphosis (PJK) is a well-recognized, yet incompletely defined, complication of adult spinal deformity surgery. There is no standardized definition for PJK, but most studies describe PJK as an increase in the proximal junctional angle (PJA) of greater than 10°-20°. Ligament augmentation is a novel strategy for PJK reduction that provides strength to the upper instrumented vertebra (UIV) and adjacent segments while also reducing junctional stress at those levels. METHODS In this study, ligament augmentation was used in a consecutive series of adult spinal deformity patients at a single institution. Patient demographics, including age; sex; indication for surgery; revision surgery; surgical approach; and use of 3-column osteotomies, vertebroplasty, or hook fixation at the UIV, were collected. The PJA was measured preoperatively and at last follow-up using 36-inch radiographs. Data on change in PJA and need for revision surgery were collected. Univariate and multivariate analyses were performed to identify factors associated with change in PJA and proximal junctional failure (PJF), defined as PJK requiring surgical correction. RESULTS A total of 200 consecutive patients were included: 100 patients before implementation of ligament augmentation and 100 patients after implementation of this technique. The mean age of the ligament augmentation cohort was 66 years, and 67% of patients were women. Over half of these cases (51%) were revision surgeries, with 38% involving a combined anterior or lateral and posterior approach. The mean change in PJA was 6° in the ligament augmentation group compared with 14° in the control group (p < 0.001). Eighty-four patients had a change in PJA of less than 10°. In a multivariate linear regression model, age (p = 0.016), use of hook fixation at the UIV (p = 0.045), and use of ligament augmentation (p < 0.001) were associated with a change in PJA. In a separate model, only ligament augmentation (OR 0.193, p = 0.012) showed a significant association with PJF. CONCLUSIONS Ligament augmentation represents a novel technique for the prevention of PJK and PJF. Compared with a well-matched historical cohort, ligament augmentation is associated with a significant decrease in PJK and PJF. These data support the implementation of ligament augmentation in surgery for adult spinal deformity, particularly in patients with a high risk of developing PJK and PJF.

OBJECTIVE Although 3-column osteotomy (3CO) can provide powerful alignment correction in adult spinal deformity (ASD), these procedures are complex and associated with high complication rates. The authors' objective was to assess complications associated with ASD surgery that included 3CO based on a prospectively collected multicenter database. METHODS This study is a retrospective review of a prospectively collected multicenter consecutive case registry. ASD patients treated with 3CO and eligible for 2-year follow-up were identified from a prospectively collected multicenter ASD database. Early (≤ 6 weeks after surgery) and delayed (> 6 weeks after surgery) complications were collected using standardized forms and on-site coordinators. RESULTS Of 106 ASD patients treated with 3CO, 82 (77%; 68 treated with pedicle subtraction osteotomy [PSO] and 14 treated with vertebral column resection [VCR]) had 2-year follow-up (76% women, mean age 60.7 years, previous spine fusion in 80%). The mean number of posterior fusion levels was 12.9, and 17% also had an anterior fusion. A total of 76 early (44 minor, 32 major) and 66 delayed (13 minor, 53 major) complications were reported, with 41 patients (50.0%) and 45 patients (54.9%) affected, respectively. Overall, 64 patients (78.0%) had at least 1 complication, and 50 (61.0%) had at least 1 major complication. The most common complications were rod breakage (31.7%), dural tear (20.7%), radiculopathy (9.8%), motor deficit (9.8%), proximal junctional kyphosis (PJK, 9.8%), pleural effusion (8.5%), and deep wound infection (7.3%). Compared with patients who did not experience early or delayed complications, those who had these complications did not differ significantly with regard to age, sex, body mass index, Charlson Comorbidity Index, American Society of Anesthesiologists score, smoking status, history of previous spine surgery or spine fusion, or whether the 3CO performed was a PSO or VCR (p ≥ 0.06). Twenty-seven (33%) patients had 1-11 reoperations (total of 44 reoperations). The most common indications for reoperation were rod breakage (n = 14), deep wound infection (n = 15), and PJK (n = 6). The 24 patients who did not achieve 2-year follow-up had a mean of 0.85 years of follow-up, and the types of early and delayed complications encountered in these 24 patients were comparable to those encountered in the patients that achieved 2-year follow-up. CONCLUSIONS Among 82 ASD patients treated with 3CO, 64 (78.0%) had at least 1 early or delayed complication (57 minor, 85 major). The most common complications were instrumentation failure, dural tear, new neurological deficit, PJK, pleural effusion, and deep wound infection. None of the assessed demographic or surgical parameters were significantly associated with the occurrence of complications. These data may prove useful for surgical planning, patient counseling, and efforts to improve the safety and cost-effectiveness of these procedures.

OBJECTIVE The operative management of patients with adult spinal deformity (ASD) has a high complication rate and it remains unknown whether baseline patient characteristics and surgical variables can predict early complications (intraoperative and perioperative [within 6 weeks]). The development of an accurate preoperative predictive model can aid in patient counseling, shared decision making, and improved surgical planning. The purpose of this study was to develop a model based on baseline demographic, radiographic, and surgical factors that can predict if patients will sustain an intraoperative or perioperative major complication. METHODS This study was a retrospective analysis of a prospective, multicenter ASD database. The inclusion criteria were age ≥ 18 years and the presence of ASD. In total, 45 variables were used in the initial training of the model including demographic data, comorbidities, modifiable surgical variables, baseline health-related quality of life, and coronal and sagittal radiographic parameters. Patients were grouped as either having at least 1 major intraoperative or perioperative complication (COMP group) or not (NOCOMP group). An ensemble of decision trees was constructed utilizing the C5.0 algorithm with 5 different bootstrapped models. Internal validation was accomplished via a 70/30 data split for training and testing each model, respectively. Overall accuracy, the area under the receiver operating characteristic (AUROC) curve, and predictor importance were calculated. RESULTS Five hundred fifty-seven patients were included: 409 (73.4%) in the NOCOMP group, and 148 (26.6%) in the COMP group. The overall model accuracy was 87.6% correct with an AUROC curve of 0.89 indicating a very good model fit. Twenty variables were determined to be the top predictors (importance ≥ 0.90 as determined by the model) and included (in decreasing importance): age, leg pain, Oswestry Disability Index, number of decompression levels, number of interbody fusion levels, Physical Component Summary of the SF-36, Scoliosis Research Society (SRS)-Schwab coronal curve type, Charlson Comorbidity Index, SRS activity, T-1 pelvic angle, American Society of Anesthesiologists grade, presence of osteoporosis, pelvic tilt, sagittal vertical axis, primary versus revision surgery, SRS pain, SRS total, use of bone morphogenetic protein, use of iliac crest graft, and pelvic incidence-lumbar lordosis mismatch. CONCLUSIONS A successful model (87% accuracy, 0.89 AUROC curve) was built predicting major intraoperative or perioperative complications following ASD surgery. This model can provide the foundation toward improved education and point-of-care decision making for patients undergoing ASD surgery.

OBJECTIVE Mental disease burden can have a significant impact on levels of disability and health-related quality of life (HRQOL) measures. Therefore, the authors investigated the significance of mental health status in adults with spinal deformity and poor physical function. METHODS A retrospective analysis of a prospective multicenter database of 365 adult spinal deformity (ASD) patients who had undergone surgical treatment was performed. Health-related QOL variables were examined preoperatively and at the 2-year postoperative follow-up. Patients were grouped by their 36-Item Short Form Health Survey mental component summary (MCS) and physical component summary (PCS) scores. Both groups had PCS scores ≤ 25th percentile for matched norms; however, the low mental health (LMH) group consisted of patients with an MCS score ≤ 25th percentile, and the high mental health (HMH) group included patients with an MCS score ≥ 75th percentile. RESULTS Of the 264 patients (72.3%) with a 2-year follow-up, 104 (28.5%) met the inclusion criteria for LMH and 40 patients (11.0%) met those for HMH. The LMH group had a significantly higher overall rate of comorbidities, specifically leg weakness, depression, hypertension, and self-reported neurological and psychiatric disease processes, and were more likely to be unemployed as compared with the HMH group (p < 0.05 for all). The 2 groups had similar 2-year postoperative improvements in HRQOL (p > 0.05) except for the greater improvements in the MCS and the Scoliosis Research Society-22r questionnaire (SRS-22r) mental domain (p < 0.05) in the LMH group and greater improvements in PCS and SRS-22r satisfaction and back pain domains (p < 0.05) in the HMH group. The LMH group had a higher rate of reaching a minimal clinically important difference (MCID) on the SRS-22r mental domain (p < 0.01), and the HMH group had a higher rate of reaching an MCID on the PCS and SRS-22r activity domain (p < 0.05). On multivariable logistic regression, having LMH was a significant independent predictor of failure to reach an MCID on the PCS (p < 0.05). At the 2-year postoperative follow-up, 14 LMH patients (15.1%) were categorized as HMH. Two LMH patients (2.2%), and 3 HMH patients (7.7%) transitioned to a PCS score ≥ 75th percentile for age- and sex-matched US norms (p < 0.01). CONCLUSIONS While patients with poor mental and physical health, according to their MCS and PCS scores, have higher medical comorbidity and unemployment rates, they still demonstrate significant improvements in HRQOL measurements postoperatively. Both LMH and HMH patient groups demonstrated similar improvements in most HRQOL domains, except that the LMH patients had difficulties in obtaining improvements in the PCS domain.

OBJECTIVE The objective of this study was to isolate whether the effect of a baseline clinical history of depression on outcome is independent of associated physical disability and to evaluate which mental health screening tool has the most utility in determining 2-year clinical outcomes after adult spinal deformity (ASD) surgery. METHODS Consecutively enrolled patients with ASD in a prospective, multicenter ASD database who underwent surgical intervention with a minimum 2-year follow-up were retrospectively reviewed. A subset of patients who completed the Distress and Risk Assessment Method (DRAM) was also analyzed. The effects of categorical baseline depression and DRAM classification on the Oswestry Disability Index (ODI), SF-36, and Scoliosis Research Society questionnaire (SRS-22r) were assessed using univariate and multivariate linear regression analyses. The probability of achieving ≥ 1 minimal clinically important difference (MCID) on the ODI based on the DRAM's Modified Somatic Perceptions Questionnaire (MSPQ) score was estimated. RESULTS Of 267 patients, 66 (24.7%) had self-reported preoperative depression. Patients with baseline depression had significantly more preoperative back pain, greater BMI and Charlson Comorbidity Indices, higher ODIs, and lower SRS-22r and SF-36 Physical/Mental Component Summary (PCS/MCS) scores compared with those without self-reported baseline depression. They also had more severe regional and global sagittal malalignment. After adjusting for these differences, preoperative depression did not impact 2-year ODI, PCS/MCS, or SRS-22r totals (p > 0.05). Compared with those in the "normal" DRAM category, "distressed somatics" (n = 11) had higher ODI (+23.5 points), lower PCS (-10.9), SRS-22r activity (-0.9), and SRS-22r total (-0.8) scores (p ≤ 0.01), while "distressed depressives" (n = 25) had lower PCS (-8.4) and SRS-22r total (-0.5) scores (p < 0.05). After adjusting for important covariates, each additional point on the baseline MSPQ was associated with a 0.8-point increase in 2-year ODI (p = 0.03). The probability of improving by at least 1 MCID in 2-year ODI ranged from 77% to 21% for MSPQ scores 0-20, respectively. CONCLUSIONS A baseline clinical history of depression does not correlate with worse 2-year outcomes after ASD surgery after adjusting for baseline differences in comorbidities, health-related quality of life, and spinal deformity severity. Conversely, DRAM improved risk stratification of patient subgroups predisposed to achieving suboptimal surgical outcomes. The DRAM's MSPQ was more predictive than MCS and SRS mental domain for 2-year outcomes and may be a valuable tool for surgical screening.

OBJECTIVE Although multiple reports have documented significant benefit from surgical treatment of adult spinal deformity (ASD), these procedures can have high complication rates. Previously reported complications rates associated with ASD surgery are limited by retrospective design, single-surgeon or single-center cohorts, lack of rigorous data on complications, and/or limited follow-up. Accurate definition of complications associated with ASD surgery is important and may serve as a resource for patient counseling and efforts to improve the safety of patient care. The authors conducted a study to prospectively assess the rates of complications associated with ASD surgery with a minimum 2-year follow-up based on a multicenter study design that incorporated standardized data-collection forms, on-site study coordinators, and regular auditing of data to help ensure complete and accurate reporting of complications. In addition, they report age stratification of complication rates and provide a general assessment of factors that may be associated with the occurrence of complications. METHODS As part of a prospective, multicenter ASD database, standardized forms were used to collect data on surgery-related complications. On-site coordinators and central auditing helped ensure complete capture of complication data. Inclusion criteria were age older than 18 years, ASD, and plan for operative treatment. Complications were classified as perioperative (within 6 weeks of surgery) or delayed (between 6 weeks after surgery and time of last follow-up), and as minor or major. The primary focus for analyses was on patients who reached a minimum follow-up of 2 years. RESULTS Of 346 patients who met the inclusion criteria, 291 (84%) had a minimum 2-year follow-up (mean 2.1 years); their mean age was 56.2 years. The vast majority (99%) had treatment including a posterior procedure, 25% had an anterior procedure, and 19% had a 3-column osteotomy. At least 1 revision was required in 82 patients (28.2%). A total of 270 perioperative complications (145 minor; 125 major) were reported, with 152 patients (52.2%) affected, and a total of 199 delayed complications (62 minor; 137 major) were reported, with 124 patients (42.6%) affected. Overall, 469 complications (207 minor; 262 major) were documented, with 203 patients (69.8%) affected. The most common complication categories included implant related, radiographic, neurological, operative, cardiopulmonary, and infection. Higher complication rates were associated with older age (p = 0.009), greater body mass index (p ≤ 0.031), increased comorbidities (p ≤ 0.007), previous spine fusion (p = 0.029), and 3-column osteotomies (p = 0.036). Cases in which 2-year follow-up was not achieved included 2 perioperative mortalities (pulmonary embolus and inferior vena cava injury). CONCLUSIONS This study provides an assessment of complications associated with ASD surgery based on a prospective, multicenter design and with a minimum 2-year follow-up. Although the overall complication rates were high, in interpreting these findings, it is important to recognize that not all complications are equally impactful. This study represents one of the most complete and detailed reports of perioperative and delayed complications associated with ASD surgery to date. These findings may prove useful for treatment planning, patient counseling, benchmarking of complication rates, and efforts to improve the safety and cost-effectiveness of patient care.

Objective: A high prevalence of cervical deformity (CD) has been identified among adult patients with thoracolumbar spinal deformity undergoing surgical treatment. The clinical impact of this is uncertain. This study aimed to quantify the differences in patient-reported outcomes among patients with adult spinal deformity (ASD) based on presence of CD prior to treatment., Methods: A retrospective review was conducted of a multicenter prospective database of patients with ASD who underwent surgical treatment with 2-year follow-up. Patients were grouped by the presence of preoperative CD: 1) cervical positive sagittal malalignment (CPSM) C2-7 sagittal vertical axis ≥ 4 cm; 2) cervical kyphosis (CK) C2-7 angle > 0; 3) CPSM and CK (BOTH); and 4) no baseline CD (NONE). Health-related quality of life (HRQOL) scores included the Physical Component Summary and Mental Component Summary (PCS and MCS) scores of the 36-Item Short Form Health Survey (SF-36), Oswestry Disability Index (ODI), Scoliosis Research Society-22 questionnaire (SRS-22), and minimum clinically important difference (MCID) of these scores at 2 years. Standard radiographic measurements were conducted for cervical, thoracic, and thoracolumbar parameters., Results: One hundred eighty-two patients were included in this study: CPSM, 45; CK, 37; BOTH, 16; and NONE, 84. Patients with preoperative CD and those without had similar baseline thoracolumbar radiographic measurements and similar correction rates at 2 years. Patients with and without preoperative CD had similar baseline HRQOL and on average both groups experienced some HRQOL improvement. However, those with preoperative CPSM had significantly worse postoperative ODI, PCS, SRS-22 Activity, SRS-22 Appearance, SRS-22 Pain, SRS-22 Satisfaction, and SRS-22 Total score, and were less likely to meet MCID for ODI, PCS, SRS-22 Activity, and SRS-22 Pain scores with the following ORs and 95% CIs: ODI 0.19 (0.07-0.58), PCS 0.17 (0.06-0.47), SRS-22 Activity 0.23 (0.09-0.62), SRS-22 Pain 0.20 (0.08-0.53), and SRS-22 Appearance 0.34 (0.12-0.94). Preoperative CK did not have an effect on outcomes. Interestingly, despite correction of the thoracolumbar deformity, 53.3% and 51.4% of patients had persistent CPSM and persistent CK, respectively., Conclusions: Patients with thoracolumbar deformity without preoperative CD are likely to have greater improvements in HRQOL after surgery than patients with concomitant preoperative CD. Cervical positive sagittal alignment in adult patients with thoracolumbar deformity is strongly associated with inferior outcomes and failure to reach MCID at 2-year follow-up despite having similar baseline HRQOL to patients without CD. This was the first study to assess the impact of concomitant preoperative cervical malalignment in adult patients with thoracolumbar deformity. These results can help surgeons educate patients at risk for inferior outcomes and direct future research to identify an etiology and improve patient outcomes. Investigation into the etiology of the baseline cervical malalignment may be warranted in patients who present with thoracolumbar deformity.

Object: Despite the complexity of cervical spine deformity (CSD) and its significant impact on patient quality of life, there exists no comprehensive classification system. The objective of this study was to develop a novel classification system based on a modified Delphi approach and to characterize the intra- and interobserver reliability of this classification., Methods: Based on an extensive literature review and a modified Delphi approach with an expert panel, a CSD classification system was generated. The classification system included a deformity descriptor and 5 modifiers that incorporated sagittal, regional, and global spinopelvic alignment and neurological status. The descriptors included: "C," "CT," and "T" for primary cervical kyphotic deformities with an apex in the cervical spine, cervicothoracic junction, or thoracic spine, respectively; "S" for primary coronal deformity with a coronal Cobb angle ≥ 15°; and "CVJ" for primary craniovertebral junction deformity. The modifiers included C2-7 sagittal vertical axis (SVA), horizontal gaze (chin-brow to vertical angle [CBVA]), T1 slope (TS) minus C2-7 lordosis (TS-CL), myelopathy (modified Japanese Orthopaedic Association [mJOA] scale score), and the Scoliosis Research Society (SRS)-Schwab classification for thoracolumbar deformity. Application of the classification system requires the following: 1) full-length standing posteroanterior (PA) and lateral spine radiographs that include the cervical spine and femoral heads; 2) standing PA and lateral cervical spine radiographs; 3) completed and scored mJOA questionnaire; and 4) a clinical photograph or radiograph that includes the skull for measurement of the CBVA. A series of 10 CSD cases, broadly representative of the classification system, were selected and sufficient radiographic and clinical history to enable classification were assembled. A panel of spinal deformity surgeons was queried to classify each case twice, with a minimum of 1 intervening week. Inter- and intrarater reliability measures were based on calculations of Fleiss k coefficient values., Results: Twenty spinal deformity surgeons participated in this study. Interrater reliability (Fleiss k coefficients) for the deformity descriptor rounds 1 and 2 were 0.489 and 0.280, respectively, and mean intrarater reliability was 0.584. For the modifiers, including the SRS-Schwab components, the interrater (round 1/round 2) and intrarater reliabilities (Fleiss k coefficients) were: C2-7 SVA (0.338/0.412, 0.584), horizontal gaze (0.779/0.430, 0.768), TS-CL (0.721/0.567, 0.720), myelopathy (0.602/0.477, 0.746), SRS-Schwab curve type (0.590/0.433, 0.564), pelvic incidence-lumbar lordosis (0.554/0.386, 0.826), pelvic tilt (0.714/0.627, 0.633), and C7-S1 SVA (0.071/0.064, 0.233), respectively. The parameter with the poorest reliability was the C7-S1 SVA, which may have resulted from differences in interpretation of positive and negative measurements., Conclusions: The proposed classification provides a mechanism to assess CSD within the framework of global spinopelvic malalignment and clinically relevant parameters. The intra- and interobserver reliabilities suggest moderate agreement and serve as the basis for subsequent improvement and study of the proposed classification.

OBJECT The associations among global spinal alignment, patient-reported disability, and surgical outcomes have increasingly gained attention. The assessment of global spinal alignment requires standing long-cassette anteroposterior and lateral radiographs; however, spine surgeons routinely rely only on short-segment imaging when evaluating seemingly isolated lumbar pathology. This may prohibit adequate surgical planning and may predispose surgeons to not recognize associated pathology in the thoracic spine and sagittal spinopelvic malalignment. The authors used a case-based survey questionnaire to evaluate if including long-cassette radiographs led to changes to respondents' operative plans as compared with their chosen plan when cases contained standard imaging of the involved lumbar spine only. METHODS A case-based survey was distributed to AOSpine International members that consisted of 15 cases of lumbar spine pathology and lumbar imaging only. The same 15 cases were then shuffled and presented a second time with additional long-cassette radiographs. Each case required participants to select a single operative plan with 5 choices ranging from least to most extensive. The cases included 5 "control" cases with normal global spinal alignment and 10 "test" cases with significant sagittal and/or coronal malalignment. Mean scores were determined for each question with higher scores representing more invasive and/or extensive operative plans. RESULTS Of 712 spine surgeons who started the survey, 316 (44%) completed the entire series, including 68% of surgeons with spine fellowship training and representation from more than 40 countries. For test cases, but not for control cases, there were significantly higher average surgical invasiveness scores for cases presented with long-cassette radiographs (4.2) as compared with those cases with lumbar imaging only (3.4; p = 0.002). The addition of long-cassette radiographs resulted in 82.1% of respondents recommending instrumentation up to the thoracic spine, a 23.2% increase as compared with the same cases presented with lumbar imaging only (p = 0.008). CONCLUSIONS This study demonstrates the importance of maintaining a low threshold for performing standing long-cassette imaging when assessing seemingly isolated lumbar pathology. Such imaging is necessary for the assessment of spinopelvic and global spinal alignment, which can be important in operative planning. Deformity, particularly positive sagittal malalignment, may go undetected unless one maintains a high index of suspicion and obtains long-cassette radiographs. It is recommended that spine surgeons recognize the prevalence and importance of such deformity when contemplating operative intervention.

Object: Three-column osteotomies (3COs) are technically challenging techniques for correcting severe rigid spinal deformities. The impact of these interventions on outcomes reaching minimum clinically important difference (MCID) or substantial clinical benefit (SCB) is unclear. The objective of this study was to determine the rates of MCID and SCB in standard health-related quality of life (HRQOL) measures after 3COs in patients with adult spinal deformity (ASD). The impacts of location of the uppermost instrumented vertebra (UIV) on clinical outcomes and of maintenance on sagittal correction at 2 years postoperatively were also examined., Methods: The authors conducted a retrospective multicenter analysis of the records from adult patients who underwent 3CO with complete 2-year radiographic and clinical follow-ups. Cases were categorized according to established radiographic thresholds for pelvic tilt (> 22°), sagittal vertical axis (> 4.7 cm), and the mismatch between pelvic incidence and lumbar lordosis (> 11°). The cases were also analyzed on the basis of a UIV in the upper thoracic (T1-6) or thoracolumbar (T9-L1) region. Patient-reported outcome measures evaluated preoperatively and 2 years postoperatively included Oswestry Disability Index (ODI) scores, the Physical Component Summary and Mental Component Summary (MCS) scores of the 36-Item Short Form Health Survey, and Scoliosis Research Society-22 questionnaire (SRS-22) scores. The percentages of patients whose outcomes for these measures met MCID and SCB were compared among the groups., Results: Data from 140 patients (101 women and 39 men) were included in the analysis; the average patient age was 57.3 ± 12.4 years (range 20-82 years). Of these patients, 94 had undergone only pedicle subtraction osteotomy (PSO) and 42 only vertebral column resection (VCR); 113 patients had a UIV in the upper thoracic (n = 63) orthoracolumbar region (n = 50). On average, 2 years postoperatively the patients had significantly improved in all HRQOL measures except the MCS score. For the entire patient cohort, the improvements ranged from 57.6% for the SRS-22 pain score MCID to 24.4% for the ODI score SCB. For patients undergoing PSO or VCR, the likelihood of their outcomes reaching MCID or SCB ranged from 24.3% to 62.3% and from 16.2% to 47.8%, respectively. The SRS-22 self-image score of patients who had a UIV in the upper thoracic region reached MCID significantly more than that of patients who had a UIV in the thoracolumbar region (70.6% vs 41.9%, p = 0.0281). All other outcomes were similar for UIVs of upper thoracic and thoracolumbar regions. Comparison of patients whose spines were above or below the radiographic thresholds associated with disability indicated similar rates of meeting MCID and SCB for HRQOL at the 2-year follow-up., Conclusions: Outcomes for patients having UIVs in the upper thoracic region were no more likely to meet MCID or SCB than for those having UIVs in the thoracolumbar region, except for the MCID in the SRS-22 self-image measure. The HRQOL outcomes in patients who had optimal sagittal correction according to radiographic thresholds determined preoperatively were not significantly more likely to reach MCID or SCB at the 2-year follow-up. Future work needs to determine whether the Schwab preoperative radiographic thresholds for severe disability apply in postoperative settings.

Object: Although recent studies suggest that average clinical outcomes are improved following surgery for selected adult spinal deformity (ASD) patients, these outcomes span a broad range. Few studies have specifically addressed factors that may predict favorable clinical outcomes. The objective of this study was to compare patients with ASD with best versus worst clinical outcomes following surgical treatment to identify distinguishing factors that may prove useful for patient counseling and optimization of clinical outcomes., Methods: This is a retrospective review of a prospectively collected, multicenter, database of consecutively enrolled patients with ASD who were treated operatively. Inclusion criteria were age > 18 years and ASD. For patients with a minimum of 2-year follow-up, those with best versus worst outcomes were compared separately based on Scoliosis Research Society-22 (SRS-22) and Oswestry Disability Index (ODI) scores. Only patients with a baseline SRS-22 ≤ 3.5 or ODI ≥ 30 were included to minimize ceiling/floor effects. Best and worst outcomes were defined for SRS-22 (≥ 4.5 and ≤ 2.5, respectively) and ODI (≤ 15 and ≥ 50, respectively)., Results: Of 257 patients who met the inclusion criteria, 227 (88%) had complete baseline and 2-year follow-up SRS-22 and ODI outcomes scores and radiographic imaging and were analyzed in the present study. Of these 227 patients, 187 had baseline SRS-22 scores ≤ 3.5, and 162 had baseline ODI scores ≥ 30. Forthe SRS-22, best and worst outcomes criteria were met at follow-up for 25 and 27 patients, respectively. For the ODI, best and worst outcomes criteria were met at follow-up for 43 and 51 patients, respectively. With respect to the SRS-22, compared with best outcome patients, those with worst outcomes had higher baseline SRS-22 scores (p < 0.0001), higher prevalence of baseline depression (p < 0.001), more comorbidities (p = 0.012), greater prevalence of prior surgery (p = 0.007), a higher complication rate (p = 0.012), and worse baseline deformity (sagittal vertical axis [SVA], p = 0.045; pelvic incidence [PI] and lumbar lordosis [LL] mismatch, p = 0.034). The best-fit multivariate model for SRS-22 included baseline SRS-22 (p = 0.033), baseline depression (p = 0.012), and complications (p = 0.030). With respect to the ODI, compared with best outcome patients, those with worst outcomes had greater baseline ODI scores (p < 0.001), greater baseline body mass index (BMI; p = 0.002), higher prevalence of baseline depression (p < 0.028), greater baseline SVA (p = 0.016), a higher complication rate (p = 0.02), and greater 2-year SVA (p < 0.001) and PI-LL mismatch (p = 0.042). The best-fit multivariate model for ODI included baseline ODI score (p < 0.001), 2-year SVA (p = 0.014) and baseline BMI (p = 0.037). Age did not distinguish best versus worst outcomes for SRS-22 or ODI (p > 0.1)., Conclusions: Few studies have specifically addressed factors that distinguish between the best versus worst clinical outcomes for ASD surgery. In this study, baseline and perioperative factors distinguishing between the best and worst outcomes for ASD surgery included several patient factors (baseline depression, BMI, comorbidities, and disability), as well as residual deformity (SVA), and occurrence of complications. These findings suggest factors that may warrant greater awareness among clinicians to achieve optimal surgical outcomes for patients with ASD.

OBJECT Regional cervical sagittal alignment (C2-7 sagittal vertical axis [SVA]) has been shown to correlate with health-related quality of life (HRQOL). The study objective was to examine the relationship between cervical and thoracolumbar alignment parameters with HRQOL among patients with operative and nonoperative adult thoracolumbar deformity. METHODS This is a multicenter prospective data collection of consecutive patients with adult thoracolumbar spinal deformity. Clinical measures of disability included the Oswestry Disability Index (ODI), Scoliosis Research Society-22 Patient Questionnaire (SRS-22), and 36-Item Short-Form Health Survey (SF-36). Cervical radiographic parameters were correlated with global sagittal parameters within the nonoperative and operative cohorts. A partial correlation analysis was performed controlling for C-7 SVA. The operative group was subanalyzed by the magnitude of global deformity (C-7 SVA ≥ 5 cm vs < 5 cm). RESULTS A total of 318 patients were included (186 operative and 132 nonoperative). The mean age was 55.4 ± 14.9 years. Operative patients had significantly worse baseline HRQOL and significantly larger C-7 SVA, pelvic tilt (PT), mismatch between pelvic incidence and lumbar lordosis (PI-LL), and C2-7 SVA. The operative patients with baseline C-7 SVA ≥ 5 cm had significantly larger C2-7 lordosis (CL), C2-7 SVA, C-7 SVA, PI-LL, and PT than patients with a normal C-7 SVA. For all patients, baseline C2-7 SVA and CL significantly correlated with baseline ODI, Physical Component Summary (PCS), SRS Activity domain, and SRS Appearance domain. Baseline C2-7 SVA also correlated with SRS Pain and SRS Total. For the operative patients with baseline C-7 SVA ≥ 5 cm, the 2-year C2-7 SVA significantly correlated with 2-year Mental Component Summary, SRS Mental, SRS Satisfaction, and decreases in ODI. Decreases in C2-7 SVA at 2 years significantly correlated with lower ODI at 2 years. Using partial correlations while controlling for C-7 SVA, the C2-7 SVA correlated significantly with baseline ODI (r = 0.211, p = 0.002), PCS (r = -0.178, p = 0.009), and SRS Activity (r = -0.145, p = 0.034) for the entire cohort. In the subset of operative patients with larger thoracolumbar deformities, the change in C2-7 SVA correlated with change in ODI (r = -0.311, p = 0.03). CONCLUSIONS Changes in cervical lordosis correlate to HRQOL improvements in thoracolumbar deformity patients at 2-year follow-up. Regional cervical sagittal parameters such as CL and C2-7 SVA are correlated with clinical measures of regional disability and health status in patients with adult thoracolumbar scoliosis. This effect may be direct or a reciprocal effect of the underlying global deformities on regional cervical alignment. However, the partial correlation analysis, controlling for the magnitude of the thoracolumbar deformity, suggests that there is a direct effect of cervical alignment on health measures. Improvements in regional cervical alignment postoperatively correlated positively with improved HRQOL.

OBJECT Alignment changes in the cervical spine that occur following surgical correction for thoracic deformity remain poorly understood. The purpose of this study was to evaluate such changes in a cohort of adults with thoracic deformity treated surgically. METHODS The authors conducted a multicenter retrospective analysis of consecutive patients with thoracic deformity. Inclusion criteria for this study were as follows: corrective osteotomy for thoracic deformity, upper-most instrumented vertebra (UIV) between T-1 and T-4, lower-most instrumented vertebra (LIV) at or above L-5 (LIV ≥ L-5) or at the ilium (LIV-ilium), and a minimum radiographic follow-up of 2 years. Sagittal radiographic parameters were assessed preoperatively as well as at 3 months and 2 years postoperatively, including the C-7 sagittal vertical axis (SVA), C2-7 cervical lordosis (CL), C2-7 SVA, T-1 slope (T1S), T1S minus CL (T1S-CL), T2-12 thoracic kyphosis (TK), apical TK, lumbar lordosis (LL), pelvic incidence (PI), PI-LL, pelvic tilt (PT), and sacral slope (SS). RESULTS Fifty-seven patients with a mean age of 49.1 ± 14.6 years met the study inclusion criteria. The preoperative prevalence of increased CL (CL > 15°) was 48.9%. Both 3-month and 2-year apical TK improved from baseline (p < 0.05, statistically significant). At the 2-year follow-up, only the C2-7 SVA increased significantly from baseline (p = 0.01), whereas LL decreased from baseline (p < 0.01). The prevalence of increased CL was 35.3% at 3 months and 47.8% at 2 years, which did not represent a significant change. Postoperative cervical alignment changes were not significantly different from preoperative values regardless of the LIV (LIV ≥ L-5 or LIV-ilium, p > 0.05 for both). In a subset of patients with a maximum TK ≥ 60° (35 patients) and 3-column osteotomy (38 patients), no significant postoperative cervical changes were seen. CONCLUSION Increased CL is common in adult spinal deformity patients with thoracic deformities and, unlike after lumbar corrective surgery, does not appear to normalize after thoracic corrective surgery. Cervical sagittal malalignment (C2-7 SVA) also increases postoperatively. Surgeons should be aware that spontaneous cervical alignment normalization might not occur following thoracic deformity correction.

OBJECT Back and leg pain are the primary outcomes of adult spinal deformity (ASD) and predict patients' seeking of surgical management. The authors sought to characterize changes in back and leg pain after operative or nonoperative management of ASD. Outcomes were assessed according to pain severity, type of surgical procedure, Scoliosis Research Society (SRS)-Schwab spine deformity class, and patient satisfaction. METHODS This study retrospectively reviewed data in a prospective multicenter database of ASD patients. Inclusion criteria were the following: age > 18 years and presence of spinal deformity as defined by a scoliosis Cobb angle ≥ 20°, sagittal vertical axis length ≥ 5 cm, pelvic tilt angle ≥ 25°, or thoracic kyphosis angle ≥ 60°. Patients were grouped into nonoperated and operated subcohorts and by the type of surgical procedure, spine SRS-Schwab deformity class, preoperative pain severity, and patient satisfaction. Numerical rating scale (NRS) scores of back and leg pain, Oswestry Disability Index (ODI) scores, physical component summary (PCS) scores of the 36-Item Short Form Health Survey, minimum clinically important differences (MCIDs), and substantial clinical benefits (SCBs) were assessed. RESULTS Patients in whom ASD had been operatively managed were 6 times more likely to have an improvement in back pain and 3 times more likely to have an improvement in leg pain than patients in whom ASD had been nonoperatively managed. Patients whose ASD had been managed nonoperatively were more likely to have their back or leg pain remain the same or worsen. The incidence of postoperative leg pain was 37.0% at 6 weeks postoperatively and 33.3% at the 2-year follow-up (FU). At the 2-year FU, among patients with any preoperative back or leg pain, 24.3% and 37.8% were free of back and leg pain, respectively, and among patients with severe (NRS scores of 7-10) preoperative back or leg pain, 21.0% and 32.8% were free of back and leg pain, respectively. Decompression resulted in more patients having an improvement in leg pain and their pain scores reaching MCID. Although osteotomies improved back pain, they were associated with a higher incidence of leg pain. Patients whose spine had an SRS-Schwab coronal curve Type N deformity (sagittal malalignment only) were least likely to report improvements in back pain. Patients with a Type L deformity were most likely to report improved back or leg pain and to have reductions in pain severity scores reaching MCID and SCB. Patients with a Type D deformity were least likely to report improved leg pain and were more likely to experience a worsening of leg pain. Preoperative pain severity affected pain improvement over 2 years because patients who had higher preoperative pain severity experienced larger improvements, and their changes in pain severity were more likely to reach MCID/SCB than for those reporting lower preoperative pain. Reductions in back pain contributed to improvements in ODI and PCS scores and to patient satisfaction more than reductions in leg pain did. CONCLUSIONS The authors' results provide a valuable reference for counseling patients preoperatively about what improvements or worsening in back or leg pain they may experience after surgical intervention for ASD.

Object: Improved understanding of rod fracture (RF) following adult spinal deformity (ASD) surgery could prove valuable for surgical planning, patient counseling, and implant design. The objective of this study was to prospectively assess the rates of and risk factors for RF following surgery for ASD., Methods: This was a prospective, multicenter, consecutive series. Inclusion criteria were ASD, age > 18 years, ≥5 levels posterior instrumented fusion, baseline full-length standing spine radiographs, and either development of RF or full-length standing spine radiographs obtained at least 1 year after surgery that demonstrated lack of RF. ASD was defined as presence of at least one of the following: coronal Cobb angle ≥20°, sagittal vertical axis (SVA) ≥5 cm, pelvic tilt (PT) ≥25°, and thoracic kyphosis ≥60°., Results: Of 287 patients who otherwise met inclusion criteria, 200 (70%) either demonstrated RF or had radiographic imaging obtained at a minimum of 1 year after surgery showing lack of RF. The patients' mean age was 54.8 ± 15.8 years; 81% were women; 10% were smokers; the mean body mass index (BMI) was 27.1 ± 6.5; the mean number of levels fused was 12.0 ± 3.8; and 50 patients (25%) had a pedicle subtraction osteotomy (PSO). The rod material was cobalt chromium (CC) in 53%, stainless steel (SS), in 26%, or titanium alloy (TA) in 21% of cases; the rod diameters were 5.5 mm (in 68% of cases), 6.0 mm (in 13%), or 6.35 mm (in 19%). RF occurred in 18 cases (9.0%) at a mean of 14.7 months (range 3-27 months); patients without RF had a mean follow-up of 19 months (range 12-24 months). Patients with RF were older (62.3 vs 54.1 years, p = 0.036), had greater BMI (30.6 vs 26.7, p = 0.019), had greater baseline sagittal malalignment (SVA 11.8 vs 5.0 cm, p = 0.001; PT 29.1° vs 21.9°, p = 0.016; and pelvic incidence [PI]-lumbar lordosis [LL] mismatch 29.6° vs 12.0°, p = 0.002), and had greater sagittal alignment correction following surgery (SVA reduction by 9.6 vs 2.8 cm, p < 0.001; and PI-LL mismatch reduction by 26.3° vs 10.9°, p = 0.003). RF occurred in 22.0% of patients with PSO (10 of the 11 fractures occurred adjacent to the PSO level), with rates ranging from 10.0% to 31.6% across centers. CC rods were used in 68% of PSO cases, including all with RF. Smoking, levels fused, and rod diameter did not differ significantly between patients with and without RF (p > 0.05). In cases including a PSO, the rate of RF was significantly higher with CC rods than with TA or SS rods (33% vs 0%, p = 0.010). On multivariate analysis, only PSO was associated with RF (p = 0.001, OR 5.76, 95% CI 2.01-15.8)., Conclusions: Rod fracture occurred in 9.0% of ASD patients and in 22.0% of PSO patients with a minimum of 1-year follow-up. With further follow-up these rates would likely be even higher. There was a substantial range in the rate of RF with PSO across centers, suggesting potential variations in technique that warrant future investigation. Due to higher rates of RF with PSO, alternative instrumentation strategies should be considered for these cases.

Object: Increased sagittal vertical axis (SVA) correlates strongly with pain and disability for adults with spinal deformity. A subset of patients with sagittal spinopelvic malalignment (SSM) have flatback deformity (pelvic incidence-lumbar lordosis [PI-LL] mismatch > 10°) but remain sagittally compensated with normal SVA. Few data exist for SSM patients with flatback deformity and normal SVA. The authors' objective was to compare baseline disability and treatment outcomes for patients with compensated (SVA < 5 cm and PI-LL mismatch > 10°) and decompensated (SVA > 5 cm) SSM., Methods: The study was a multicenter, prospective analysis of adults with spinal deformity who consecutively underwent surgical treatment for SSM. Inclusion criteria included age older than 18 years, presence of adult spinal deformity with SSM, plan for surgical treatment, and minimum 1-year follow-up data. Patients with SSM were divided into 2 groups: those with compensated SSM (SVA < 5 cm and PI-LL mismatch > 10°) and those with decompensated SSM (SVA ≥ 5 cm). Baseline and 1-year follow-up radiographic and health-related quality of life (HRQOL) outcomes included Oswestry Disability Index, Short Form-36 scores, and Scoliosis Research Society-22 scores. Percentages of patients achieving minimal clinically important difference (MCID) were also assessed., Results: A total of 125 patients (27 compensated and 98 decompensated) met inclusion criteria. Compared with patients in the compensated group, patients in the decompensated group were older (62.9 vs. 55.1 years; p = 0.004) and had less scoliosis (43° vs 54°; p = 0.002), greater SVA (12.0 cm vs. 1.7 cm; p < 0.001), greater PI-LL mismatch (26° vs. 20°; p = 0.013), and poorer HRQOL scores (Oswestry Disability Index, Short Form-36 physical component score, Scoliosis Research Society-22 total; p ≤ 0.016). Although these baseline HRQOL differences between the groups reached statistical significance, only the mean difference in Short Form-36 physical component score reached threshold for MCID. Compared with baseline assessment, at 1 year after surgery improvement was noted for patients in both groups for mean SVA (compensated -1.1 cm, decompensated +4.8 cm; p ≤ 0.009), mean PI-LL mismatch (compensated 6°, decompensated 5°; p < 0.001), and all HRQOL measures assessed (p ≤ 0.005). No significant differences were found between the compensated and decompensated groups in the magnitude of HRQOL score improvement or in the percentages of patients achieving MCID for each of the outcome measures assessed., Conclusions: Decompensated SSM patients with elevated SVA experience significant disability; however, the amount of disability in compensated SSM patients with flatback deformity caused by PI-LL mismatch but normal SVA is underappreciated. Surgical correction of SSM demonstrated similar radiographic and HRQOL score improvements for patients in both groups. Evaluation of SSM should extend beyond measuring SVA. Among patients with concordant pain and disability, PI-LL mismatch must be evaluated for SSM patients and can be considered a primary indication for surgery.

Object: Spinal osteotomies for adult spinal deformity correction may include resection of all 3 spinal columns (pedicle subtraction osteotomy [PSO] and vertebral column resection [VCR]). The relationship between patient age and health-related quality of life (HRQOL) outcomes for patients undergoing major spinal deformity correction via PSO or VCR has not been well characterized. The goal of this study was to characterize that relationship., Methods: This study was a retrospective review of 374 patients who had undergone a 3-column osteotomy (299 PSOs and 75 VCRs) and were part of a prospectively collected, multicenter adult spinal deformity database. The consecutively enrolled patients were drawn from 11 sites across the United States. Health-related QOL outcomes, according to the visual analog scale (VAS), Oswestry Disability Index (ODI), 36-Item Short-Form Health Survey (SF-36, physical component score [PCS] and mental component score), and Scoliosis Research Society-22 questionnaire (SRS), were evaluated preoperatively and 1 and 2 years postoperatively. Differences and correlations between patient age and HRQOL outcomes were investigated. Age groupings included young (age ≤ 45 years), middle aged (age 46-64 years), and elderly (age ≥ 65 years)., Results: In patients who had undergone PSO, age significantly correlated (Spearman's correlation coefficient) with the 2-year ODI (ρ = 0.24, p = 0.0450), 2-year SRS function score (ρ = 0.30, p = 0.0123), and 2-year SRS total score (ρ = 0.30, p = 0.0133). Among all patients (PSO+VCR), the preoperative PCS and ODI in the young group were significantly higher and lower, respectively, than those in the elderly. Among the PSO patients, the elderly group had much greater improvement than the young group in the 1- and 2-year PCS, 2-year ODI, and 2-year SRS function and total scores. Among the VCR patients, the young age group had much greater improvement than the elderly in the 1-year SRS pain score, 1-year PCS, 2-year PCS, and 2-year ODI. There was no significant difference among all the age groups as regards the likelihood of reaching a minimum clinically important difference (MCID) within each of the HRQOL outcomes (p > 0.05 for all). Among the PSO patients, the elderly group was significantly more likely than the young to reach an MCID for the 1-year PCS (61% vs 21%, p = 0.0077) and the 2-year PCS (67% vs 17%, p = 0.0054), SRS pain score (57% vs 20%, p = 0.0457), and SRS function score (62% vs 20%, p = 0.0250). Among the VCR patients, the young group was significantly more likely than the elderly patients to reach an MCID for the 1-year (100% vs 20%, p = 0.0036) and 2-year (100% vs 0%, p = 0.0027) PCS scores and 1-year (60% vs 0%, p = 0.0173) and 2-year (70% vs 0%, p = 0.0433) SRS pain scores., Conclusions: The PSO and VCR are not equivalent surgeries in terms of HRQOL outcomes and patient age. Among patients who underwent PSO, the elderly group started with more preoperative disability than the younger patients but had greater improvements in HRQOL outcomes and was more likely to reach an MCID at 1 and 2 years after treatment. Among those who underwent VCR, all had similar preoperative disabilities, but the younger patients had greater improvements in HRQOL outcomes and were more likely to reach an MCID at 1 and 2 years after treatment.

Object: Complications and reoperation for surgery to correct adult spinal deformity are not infrequent, and many studies have analyzed the rates and factors that influence the likelihood of reoperation. However, there is a need for more comprehensive analyses of reoperation in adult spinal deformity surgery from a global standpoint, particularly focusing on the 1st year following operation and considering radiographic parameters and the effects of reoperation on health-related quality of life (HRQOL). This study attempts to determine the prevalence of reoperation following surgery for adult spinal deformity, assess the indications for these reoperations, evaluate for a relation between specific radiographic parameters and the need for reoperation, and determine the potential impact of reoperation on HRQOL measures., Methods: A retrospective review was conducted of a prospective, multicenter, adult spinal deformity database collected through the International Spine Study Group. Data collected included age, body mass index, sex, date of surgery, information regarding complications, reoperation dates, length of stay, and operation time. The radiographic parameters assessed were total number of levels instrumented, total number of interbody fusions, C-7 sagittal vertical axis, uppermost instrumented vertebra (UIV) location, and presence of 3-column osteotomies. The HRQOL assessment included Oswestry Disability Index (ODI), 36-Item Short Form Health Survey physical component and mental component summary, and SRS-22 scores. Smoking history, Charlson Comorbidity Index scores, and American Society of Anesthesiologists Physical Status classification grades were also collected and assessed for correlation with risk of early reoperation. Various statistical tests were performed for evaluation of specific factors listed above, and the level of significance was set at p < 0.05., Results: Fifty-nine (17%) of a total of 352 patients required reoperation. Forty-four (12.5%) of the reoperations occurred within 1 year after the initial surgery, including 17 reoperations (5%) within 30 days. Two hundred sixty-eight patients had a minimum of 1 year of follow-up. Fifty-three (20%) of these patients had a 3-column osteotomy, and 10 (19%) of these 53 required reoperation within 1 year of the initial procedure. However, 3-column osteotomy was not predictive of reoperation within 1 year, p = 0.5476). There were no significant differences between groups with regard to the distribution of UIV, and UIV did not have a significant effect on reoperation rates. Patients needing reoperation within 1 year had worse ODI and SRS-22 scores measured at 1-year follow-up than patients not requiring operation., Conclusions: Analysis of data from a large multicenter adult spinal deformity database shows an overall 17% reoperation rate, with a 19% reoperation rate for patients treated with 3-column osteotomy and a 16% reoperation rate for patients not treated with 3-column osteotomy. The most common indications for reoperation included instrumentation complications and radiographic failure. Reoperation significantly affected HRQOL outcomes at 1-year follow-up. The need for reoperation may be minimized by carefully considering spinal alignment, termination of fixation, and type of surgical procedure (presence of osteotomy). Precautions should be taken to avoid malposition or instrumentation (rod) failure.

Object: Cervical spine osteotomies are powerful techniques to correct rigid cervical spine deformity. Many variations exist, however, and there is no current standardized system with which to describe and classify cervical osteotomies. This complicates the ability to compare outcomes across procedures and studies. The authors' objective was to establish a universal nomenclature for cervical spine osteotomies to provide a common language among spine surgeons., Methods: A proposed nomenclature with 7 anatomical grades of increasing extent of bone/soft tissue resection and destabilization was designed. The highest grade of resection is termed the major osteotomy, and an approach modifier is used to denote the surgical approach(es), including anterior (A), posterior (P), anterior-posterior (AP), posterior-anterior (PA), anterior-posterior-anterior (APA), and posterior-anterior-posterior (PAP). For cases in which multiple grades of osteotomies were performed, the highest grade is termed the major osteotomy, and lower-grade osteotomies are termed minor osteotomies. The nomenclature was evaluated by 11 reviewers through 25 different radiographic clinical cases. The review was performed twice, separated by a minimum 1-week interval. Reliability was assessed using Fleiss kappa coefficients., Results: The average intrarater reliability was classified as "almost perfect agreement" for the major osteotomy (0.89 [range 0.60-1.00]) and approach modifier (0.99 [0.95-1.00]); it was classified as "moderate agreement" for the minor osteotomy (0.73 [range 0.41-1.00]). The average interrater reliability for the 2 readings was the following: major osteotomy, 0.87 ("almost perfect agreement"); approach modifier, 0.99 ("almost perfect agreement"); and minor osteotomy, 0.55 ("moderate agreement"). Analysis of only major osteotomy plus approach modifier yielded a classification that was "almost perfect" with an average intrarater reliability of 0.90 (0.63-1.00) and an interrater reliability of 0.88 and 0.86 for the two reviews., Conclusions: The proposed cervical spine osteotomy nomenclature provides the surgeon with a simple, standard description of the various cervical osteotomies. The reliability analysis demonstrated that this system is consistent and directly applicable. Future work will evaluate the relationship between this system and health-related quality of life metrics.

This paper is a narrative review of normal cervical alignment, methods for quantifying alignment, and how alignment is associated with cervical deformity, myelopathy, and adjacent-segment disease (ASD), with discussions of health-related quality of life (HRQOL). Popular methods currently used to quantify cervical alignment are discussed including cervical lordosis, sagittal vertical axis, and horizontal gaze with the chin-brow to vertical angle. Cervical deformity is examined in detail as deformities localized to the cervical spine affect, and are affected by, other parameters of the spine in preserving global sagittal alignment. An evolving trend is defining cervical sagittal alignment. Evidence from a few recent studies suggests correlations between radiographic parameters in the cervical spine and HRQOL. Analysis of the cervical regional alignment with respect to overall spinal pelvic alignment is critical. The article details mechanisms by which cervical kyphotic deformity potentially leads to ASD and discusses previous studies that suggest how postoperative sagittal malalignment may promote ASD. Further clinical studies are needed to explore the relationship of cervical malalignment and the development of ASD. Sagittal alignment of the cervical spine may play a substantial role in the development of cervical myelopathy as cervical deformity can lead to spinal cord compression and cord tension. Surgical correction of cervical myelopathy should always take into consideration cervical sagittal alignment, as decompression alone may not decrease cord tension induced by kyphosis. Awareness of the development of postlaminectomy kyphosis is critical as it relates to cervical myelopathy. The future direction of cervical deformity correction should include a comprehensive approach in assessing global cervicalpelvic relationships. Just as understanding pelvic incidence as it relates to lumbar lordosis was crucial in building our knowledge of thoracolumbar deformities, T-1 incidence and cervical sagittal balance can further our understanding of cervical deformities. Other important parameters that account for the cervical-pelvic relationship are surveyed in detail, and it is recognized that all such parameters need to be validated in studies that correlate HRQOL outcomes following cervical deformity correction.

Sagittal spinal misalignment (SSM) is an established cause of pain and disability. Treating physicians must be familiar with the radiographic findings consistent with SSM. Additionally, the restoration or maintenance of physiological sagittal spinal alignment after reconstructive spinal procedures is imperative to achieve good clinical outcomes. The C-7 plumb line (sagittal vertical axis) has traditionally been used to evaluate sagittal spinal alignment; however, recent data indicate that the measurement of spinopelvic parameters provides a more comprehensive assessment of sagittal spinal alignment. In this review the authors describe the proper analysis of spinopelvic alignment for surgical planning. Online videos supplement the text to better illustrate the key concepts.

Object: Sagittal imbalance of the cervicothoracic spine often causes severe pain and loss of horizontal gaze. Historically, the Smith-Peterson osteotomy has been used to restore sagittal balance. Cervicothoracic junction pedicle subtraction osteotomy (PSO) offers more controlled closure and greater biomechanical stability but has been infrequently reported in the literature. This study details the cervicothoracic PSO technique in 11 cases and correlates clinical kyphosis (chin-brow to vertical angle [CBVA]) with radiographic measurements., Methods: Between February 2008 and September 2010, 11 patients (mean age 70 years) underwent a modified PSO (10 at C-7, 1 at T-1) for treatment of sagittal imbalance. Preoperative and postoperative sagittal plane radiographic measurements were made. The CBVA was measured on clinical photographs. Operative technique and perioperative correction were reported for all 11 patients and long-term follow-up data was reported for 9 patients, in whom the mean duration of follow-up was 23 months. Outcome measures used for these 9 patients were the Neck Disability Index, the 36-Item Short Form Health Survey (SF-36), and a visual analog scale for neck pain., Results: The mean values for estimated blood loss, surgical time, and hospital stay in the 11 patients were 1100 ml, 4.3 hours, and 9.9 days, respectively. The mean preoperative and immediate postoperative values (± SD) for cervical sagittal imbalance were 7.9 ± 1.4 cm and 3.4 ± 1.7 cm. The mean overall correction was 4.5 ± 1.5 cm (42.8%), the mean PSO correction 19.0°, and the mean CBVA correction 36.7°. There was essentially no correlation between preoperative C2-T1 radiographic kyphosis and preoperative CBVA (R(2) = 0.0165). There was a moderate correlation with PSO correction angle and postoperative CBVA (R(2) = 0.38). There was a significant decrease in both the Neck Disability Index (51.1 to 38.6, p = 0.03) and visual analog scale scores for neck pain (8.1 to 3.9, p = 0.0021). The SF-36 physical component summary scores increased by 18.4% (30.2 to 35.8) with no neurological complications., Conclusions: The cervicothoracic junction PSO is a safe and effective procedure for the management of cervicothoracic kyphotic deformity. It results in excellent correction of cervical kyphosis and CBVA with a controlled closure and improvement in health-related quality-of-life measures even at early time points.

Object: The Goel technique, in which C1-2 intraarticular spacers are used, may be performed to restore stability to a disrupted atlantoaxial complex in conjunction with the Harms technique of placing polyaxial screws and bilateral rods. However, it has yet to be determined biomechanically whether the addition of the C1-2 joint spacers increases the multiaxial rigidity of the fixation construct. The goal of this study was to quantify changes in multiaxial rigidity of the combined Goel-Harms technique with the addition of C1-2 intraarticular spacers., Methods: Seven cadaveric cervical spines (occiput-C2) were submitted to nondestructive flexion-extension, lateral bending, and axial rotation tests in a material testing machine spine tester. The authors applied 1.5 Nm at a rate of 0.1 Nm/second and held it constant for 10 seconds. The specimens were loaded 3 times, and data were collected on the third cycle. Testing of the specimens was performed for the following groups: 1) intact (I); 2) with the addition of C-1 lateral mass/C-2 pedicle screws and rod system (I+SR); 3) with C1-2 joint capsule incision, decortication (2 mm on top and bottom of each joint [that is, the C-1 and C-2 surface) and addition of bilateral C1-2 intraarticular spacers at C1-2 junction to the screws and rods (I+SR+C); 4) after removal of the posterior rods and only the bilateral spacers in place (I+C); 5) after removal of spacers and further destabilization with simulated odontoidectomy for a completely destabilized case (D); 6) with addition of posterior rods to the destabilized case (D+SR); and 7) with addition of bilateral C1-2 intraarticular spacers at C1-2 junction to the destabilized case (D+SR+C). The motion of C-1 was measured by a 3D motion tracking system and the motion of C-2 was measured by the rotational sensor of the testing system. The range of motion (ROM) and neutral zone (NZ) across C-1 and C-2 were evaluated., Results: For the intact spine test groups, the addition of screws/rods (I+SR) and screws/rods/cages (I+SR+C) significantly reduced ROM and NZ compared with the intact spine (I) for flexion-extension and axial rotation (p < 0.05) but not lateral bending (p > 0.05). The 2 groups were not significantly different from each other in any bending mode for ROM and NZ, but in the destabilized condition the addition of screws/rods (D+SR) and screws/rods/cages (D+SR+C) significantly reduced ROM and NZ compared with the destabilized spine (D) in all bending modes (p < 0.05). Furthermore, the addition of the C1-2 intraarticular spacers (D+SR+C) significantly reduced ROM (flexion-extension and axial rotation) and NZ (lateral bending) compared with the screws and rods alone (D+SR)., Conclusions: Study result indicated that both the Goel and Harms techniques alone and with the addition of the C1-2 intraarticular spacers to the Goel-Harms technique are advantageous for stabilizing the atlantoaxial segment. The Goel technique combined with placement of a screw/rod construct appears to result in additional construct rigidity beyond the screw/rod technique and appears to be more useful in very unstable cases.

Object: Ankylosing spondylitis (AS) is a genetic condition that frequently results in spinal sagittal plane deformity of thoracolumbar or cervicothoracic junctions. Generally, a combination of osteotomy and spinal fixation is used to treat severe cases. Although surgical techniques for traumatic injury across the cervicothoracic junction have been well characterized in clinical and biomechanical literature, the specific model of instrumented opening wedge osteotomy in autofused AS has not been studied biomechanically. This study characterizes the structural stability of various posterior fixation techniques across the cervicothoracic junction in spines with AS, specifically considering the effects of posterior rod diameter and material type., Methods: For each of 10 fresh-frozen human spines (3 male, 7 female; mean age 60 ± 10 years; C3-T6), an opening wedge osteotomy was performed at C7-T1. Lateral mass screws were inserted bilaterally from C-4 to C-6 and pedicle screws from T-1 to T-3. For each specimen, 3.2-mm titanium (Ti), 3.5-mm Ti, and 3.5-mm cobalt chromium (CoCr) posterior spinal fusion rods were tested. To simulate the anterior autofusion and long lever arms characteristic of AS, anterior cervical plates were placed from C-4 to C-7 and T-1 to T-3 using fixed angle screws. Nondestructive flexion-extension, lateral bending, and axial rotation tests were conducted to 3.0 Nm in each anatomical direction; 3D motion tracking was used to monitor primary range of motion across the osteotomy (C7-T1). Biomechanical tests used a repeat-measures test design. The order of testing for each rod type was randomized across specimens., Results: Constructs instrumented with 3.5-mm Ti and 3.5-mm CoCr rods were significantly stiffer in flexion-extension than those with the 3.2-mm Ti rod (25.2% ± 16.4% and 48.1% ± 15.3% greater than 3.2-mm Ti, respectively, p < 0.05). For axial rotation, the 3.5-mm Ti and 3.5-mm CoCr constructs also exhibited a significant increase in rigidity compared with the 3.2-mm Ti construct (36.1% ± 12.2% and 52.0% ± 20.0%, respectively, p < 0.05). There were no significant differences in rigidity seen between the 3 types of rods in lateral bending (p > 0.05). The 3.5-mm CoCr rod constructs showed significantly higher rigidity in flexion-extension than the 3.5-mm Ti rod constructs (33.1% ± 15.5%, p < 0.05). There was a trend for 3.5-mm CoCr to have greater rigidity in axial rotation (36.2% ± 18.6%), but this difference was not statistically significant (p > 0.05)., Conclusions: The results of this study suggest that 3.5-mm CoCr rods are optimal for achieving the most rigid construct in opening wedge osteotomy in the cervicothoracic region of an AS model. Rod diameter and material properties should be considered in construct strategy. Some surgeons have advocated anterior plating in patients with AS after osteotomy for additional stability and bone graft surface. Although this effect was not examined in this study, additional posterior stability achieved with CoCr may decrease the need for additional anterior procedures.

Object: Primary spine tumors frequently involve the C-2 vertebra. Complete resection of the lesion may require total removal of the C-2 vertebral body, pedicles, and dens process. Authors of this biomechanical study are the first to evaluate a comprehensive set of reconstruction methods after C-2 resection to determine the optimal configuration depending on the degree of excision required., Methods: Eight human heads (from the skull to C-6) from 4 males and 4 females with a mean age of 68 +/- 18 years at death were cleaned of tissue, while leaving ligaments and discs intact. Nondestructive flexion and extension (FE), lateral bending (LB), and axial rotation (AR) tests were conducted using a nonconstraining, pure moment loading apparatus, and relative motion across the fusion site (C1-3) was measured using a 3D motion tracking system. Specimens were tested up to 1.5 Nm at 0.25-Nm intervals for 45 seconds each. The spines were instrumented using 3.5-mm titanium rods with a midline occipitocervical plate (4.0 x 12-mm screws) and lateral mass screws (excluding C-2) at the C-1 (3.0 x 40 mm) and C3-5 levels (3.0 x 16 mm). Testing was repeated for the following configurations: Configuration 1 (CF1), instrumentation only from occiput to C-5; CF2, C-2 corpectomy leaving the dens; CF3, titanium mesh cage (16-mm diameter) from C-3 to C-1 ring and dens; CF4, removal of cage, C-1 ring, and dens; CF5, titanium mesh cage from C-3 to clivus (16-mm diameter); CF6, removal of C-2 posterior elements leaving the C3-clivus cage (spondylectomy); CF7, titanium mesh cage from C-3 to clivus (16-mm diameter) with 2 titanium mesh cages from C-3 to C-1 lateral masses (12-mm diameter); and CF8, removal of all 3 cages. A crosslink was added connecting the posterior rods for CF1, CF6, and CF8. Range-of-motion (ROM) differences between all groups were compared via repeated-measures ANOVA with paired comparisons using the Student t-test with a Tukey post hoc adjustment. A p < 0.05 indicated significance., Results: The addition of a central cage significantly increased FE rigidity compared with posterior instrumentation alone but had less of an effect in AR and LB. The addition of lateral cages did not significantly improve rigidity in any bending direction (CF6 vs CF7, p > 0.05). With posterior instrumentation alone (CF1 and CF2), C-2 corpectomy reduced bending rigidity in only the FE direction (p < 0.05). The removal of C-2 posterior elements in the presence of a C3-clivus cage did not affect the ROM in any bending mode (CF5 vs CF6, p > 0.05). A crosslink addition in CF1, CF6, and CF8 did not significantly affect primary or off-axis ROM (p > 0.05)., Conclusions: Study results indicated that posterior instrumentation alone with 3.5-mm rods is insufficient for stability restoration after a C-2 corpectomy. Either C3-1 or C3-clivus cages can correct instability introduced by C-2 removal in the presence of posterior instrumentation. The addition of lateral cages to a C3-clivus fusion construct may be unnecessary since it does not significantly improve rigidity in any direction.