Surgical Adult Spinal Deformity Patients Research Articles

52. One-third of surgical adult spinal deformity patients are consuming opioids both pre- and postoperatively with significant international differences: this is partly a cultural issue

52. One-third of surgical adult spinal deformity patients are consuming opioids both pre- and postoperatively with significant international differences: this is partly a cultural issue

P89. Correct now or wait? An analysis of comorbidity burden and optimization thresholds in surgical adult spinal deformity patients

P89. Correct now or wait? An analysis of comorbidity burden and optimization thresholds in surgical adult spinal deformity patients

46. Lower limb compensation in the setting of adult spinal deformity

<h3>BACKGROUND CONTEXT</h3> Numerous studies have reported the interplay between spinal deformity and pelvis compensatory mechanisms, but little data exist evaluating the contribution of lower extremity compensation (LE) to maintain upright posture. We hypothesis that hip, knee and ankle compensation is proportional to the severity of the spinal deformity and varies by demographics. <h3>PURPOSE</h3> Evaluate the association between spinal alignment and lower limbs compensation. <h3>STUDY DESIGN/SETTING</h3> Multicenter, prospective cohort. <h3>PATIENT SAMPLE</h3> This study included 288 patients treated for complex adult spinal deformity (ASD) with full body images available. <h3>OUTCOME MEASURES</h3> Pelvic retroversion (PT), hip extension (SFA), knee flexion (KA), ankle dorsiflexion (AA), pelvic translation (P.Shift) and patient reported outcomes (ODI, PROMIS and SRS-22). <h3>METHODS</h3> Surgical ASD patients were enrolled into a prospective study based on three criteria: deformity severity (PI-LL>25°, TPA>30°, SVA>15cm, TCobb>70° or TLCobb>50°), procedure complexity (>12 levels fused, 3CO or ACR) and/or age (>65 and >7 levels fused). Associations between lower extremity compensation (hip extension, knee flexion, and ankle dorsiflexion) and the magnitude of spinal deformity, patient demographics, patient frailty, and patient-reported outcomes (ODI, SRS, PROMIS-CAT) were assessed via regressions and partial correlations. <h3>RESULTS</h3> A total of 288/329 patients met inclusion criteria (60±15yo, 70.5% female), had moderate to severe spinal deformity (PI-LL:15±24, TPA:24±14, SVA:65±69mm, lumbar Cobb:34±24), and reported high pain (PROMIS pain interference; PI=62.7±7.8) and reduced physical function (PROMIS physical function; PF=35.6±7.6). Lower extremity compensation included pelvic retroversion (PT:24.1± 11.8), hip extension (SFA: 203±10.5), knee flexion (KA:5.5± 9.6), ankle dorsiflexion (AA: 5.3±4.5), and posterior pelvic translation (P.Shift: 30±51mm). Overall, lower extremity compensation increased with age (all p <0.001), BMI and frailty (all p <0.001, except SFA). For a similar PT, women had greater hip extension than men (SFA: 206 vs 200, p <0.001), with less KA (3.6 vs. 10.1, p <0.001), AA, and P.Shift. Lower extremity compensation increased with PI (r=0.2-0.45, p <0.001), TPA (r=0.5-0.9, p <0.001) and correlated with PROMS (ODI:0.26 - 0.37, PROMIS PF: -0.28 - -0.39, SRS Acti.: -0.20 - -0.33). When controlling for deformity severity and PI, most associations between lower limbs compensation and PROMS were lost. However, P.Shift and SFA remained weakly correlated with physical scores (ODI and PROMIS PF). <h3>CONCLUSIONS</h3> The recruitment of LE compensation is overall proportional to the severity of adult spinal deformity, with different patterns observed between men and women. Patients achieved similar PT by recruiting different patterns of LE compensation. Hip extension and posterior pelvic translation are independently associated with impairment in patient-reported outcomes. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

31. Quantifying the contribution of lower limb compensation to upright posture: what happens if ASD patients do not compensate?

<h3>BACKGROUND CONTEXT</h3> Adult spinal deformity (ASD) patients maintain upright posture by compensating through their spine, pelvis and lower extremities. Little data exist quantifying the contribution of lower extremity compensation through the hips, knees, and ankles to maintain upright posture. <h3>PURPOSE</h3> Evaluate the effect of the lower limb compensation by numerically unfolding patients. <h3>STUDY DESIGN/SETTING</h3> Multicenter, prospective cohort. <h3>PATIENT SAMPLE</h3> A total of 288 patients surgically treated for complex ASD with preoperative full body images. <h3>OUTCOME MEASURES</h3> Horizontal distance between vertebra centroid and ankle. <h3>METHODS</h3> Surgical ASD patients were enrolled into a prospective study based on three criteria deformity severity (PI-LL>25°, TPA>30°, SVA>15cm, TCobb>70° or TLCobb>50°), procedure complexity (>12 levels fused, 3CO or ACR) and/or age (>65 and >7 levels fused). Preop full-body images were evaluated and age and PI-adjusted normative values were used to model spine alignment based upon three configurations: COMP (all lower extremity compensatory mechanisms maintained), PARTIAL (removal of ankle dorsiflexion and knee flexion, maintained hip extension), UNCOMP (ankle, knee, and hip compensation eliminated by reset PT to the age and PI norms). The three configurations were compared, and COMP alignment was stratified by TPA percentiles to investigate the offsets from each vertebra to the ankle joint acting as a surrogate of the gravity line in free-standing position. <h3>RESULTS</h3> A total of 288 patients met inclusion criteria (60±15yo, 70.5% female, 27.4±5.9 BMI). COMP spine deformity magnitude included PI-LL 15±24, TPA 24±14, and SVA 65±69mm. As the model transitioned from COMP to UNCOMP alignment, the initial posterior translation of the pelvis decreased significantly to an anterior translation vs the ankle (P.Shift 30 to -7.6 mm). This was associated with a decrease in pelvic retroversion (PT 24.1 to 16.1), hip extension (SFA 203 to 200), knee flexion (KA 5.5 to -0.4), and ankle dorsiflexion (AA 5.3 to 3.7). As a result, the anterior malalignment of the trunk significantly increased SVA (65 to 120mm) and G-SVA (C7-Ankle from 36 to 127 mm), leading to a three-fold increase in bending moments sustained by the ankle joint. The stratification of the COMP position by TPA percentiles revealed that as the deformity increases, the vertebrae above T8 translate anteriorly, those below T10 move posteriorly, with the T8-T10 segment remaining ∼3cm posterior to the ankle joint independently of the deformity severity. <h3>CONCLUSIONS</h3> Removal of lower limbs' compensation revealed an unsustainable truncal malalignment with a three-fold increase of bending moments at the ankle joints. Combined, lower limb compensations permit "reducing" the SVA by two-fold and the C7-ankle SVA by three-fold. From a mechanical point of view, this compensation permits maintaining the trunk center of mass (T9) at a fixed offset of ∼3 cm from the ankle joint. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P48. Mechanisms of lumbar spine ‘flattening’ in adult spinal deformity: defining changes in shape that occur relative to a normative population

<h3>BACKGROUND CONTEXT</h3> Loss of lumbar curvature is often expressed as an angular regional loss. Previous work comparing adult spinal deformity (ASD) lumbar alignment to their age-and-PI adjusted normative value demonstrated that, contrary to general belief, a large proportion of the curvature is lost proximally (L1-L4). This study is a follow-up looking not only at regional angles, but also at the spinal contour collectively. <h3>PURPOSE</h3> Investigate the difference of lumbar shape between ASD and age-and-PI adjusted normative values. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of an ASD registry. <h3>PATIENT SAMPLE</h3> A total of 119 asymptomatic volunteers and 362 ASD patients. <h3>OUTCOME MEASURES</h3> Sagittal alignment of the lumbar and thoracolumbar spine measures using vertebra pelvic angle from L5 to T10. <h3>METHODS</h3> Before studying ASD patients, 119 asymptomatic volunteers with full-body, free-standing radiographs were used to identify age-and-PI models of each vertebra pelvic angle (VPA) from L5 to T10, a validated methodology characterizing the detailed shape of the spine. Our study cohort was a registry of surgical primary ASD patients without coronal malalignment (SRS-Schwab Type=N). The formulas developed in the asymptomatic population were applied to the ASD group to calculate an age-and-PI normative spine shape for each patient. Loss of lumbar lordosis was defined as the offset between age-and-PI normative value and pre-operative spino-pelvic alignment. Patients were stratified into four groups by the amount of lordosis lost, ranging from "no loss" to "30° loss." Paired t-tests were performed to compare actual and normative VPA shapes within each group. <h3>RESULTS</h3> Out of 1,495 patients enrolled in this registry, 453 were primary cases, and 653 were categorized as a Schwab type N, leading to a cohort of 362 patients (age=64.4±13, 57.1% F). Pre-operative alignment demonstrated a large variability with a mean PI-LL of 15°±21, distal LL=31°±15, and PI=55°±13. Compared to their age-and-PI normative values, ASD patients demonstrated a significant lordosis loss of 17°±19 with the following distribution: 14.1% no loss (mean: 0.1±2.3), 22.9% with 10° loss (mean: 9.9±2.9), 22.1% with 20° loss (mean: 20.0±2.8), and 29.3% with 30° loss (mean:33.8±6.0). Comparison of the VPAs (and therefore the shape) between each LL group and the normative shape demonstrated that the "no loss" patients had a lumbar spine slightly anterior to the normative shape from L4 to T10 (VPA difference of 2°). The shape of the "small deformity" group (10°) superimposed on the normative one from L5 to L2 (VPA with p>0.1) and became anterior at the L1 level. As the lordosis loss increased, the offset between ASD and normative shapes began to propagate to the distal levels and became significant extending caudally to the L3 level for the "20° loss" group and further down to L4 for the more severe group. <h3>CONCLUSIONS</h3> As the deformity progresses and the loss of lordosis increases, the difference between ASD shape and normative shape happens first proximally and then progresses incrementally caudally with increasing deformity. Understanding the spinal contour and the location of this loss, in addition to regional parameters, may be key to achieving a sustainable correction by identifying optimal and personalized post-operative shape. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Improved Surgical Correction Relative to Patient-Specific Ideal Spinopelvic Alignment Reduces Pelvic Nonresponse for Severely Malaligned Adult Spinal Deformity Patients.

Persistent pelvic compensation following adult spinal deformity (ASD) corrective surgery may impair quality of life and result in persistent pathologic lower extremity compensation. Ideal age-specific alignment targets have been proposed to improve surgical outcomes, though it is unclear whether reaching these ideal targets reduces rates of pelvic nonresponse following surgery. Our aim was to assess the relationship between pelvic nonresponse, age-specific alignment, and lower-limb compensation following surgery for ASD. Single-center retrospective cohort study. ASD patients were grouped: those who did not improve in Scoliosis Research Society-Schwab pelvic tilt (PT) modifier (pelvic nonresponders [PNR]), and those who improved (pelvic responders [PR]). Groups were propensity score matched for preoperative PT and assessed for differences in spinal and lower extremity alignment. Rates of pelvic nonresponse were compared across patient groups who were undercorrected, overcorrected, or matched age-specific postoperative alignment targets. A total of 146 surgical ASD patients, 47.9% of whom showed pelvic nonresponse following surgery, were included. After propensity score matching, PNR (N = 29) and PR (N = 29) patients did not differ in demographics, preoperative alignment, or levels fused; however, PNR patients have less preoperative knee flexion (9° vs 14°, P = 0.043). PNR patients had inferior postoperative pelvic incidence and lumbar lordosis (PI-LL) alignment (17° vs 3°) and greater pelvic shift (53 vs 31 mm). PNR and PR patients did not differ in rates of reaching ideal age-specific postoperative alignment for sagittal vertical axis (SVA) or PI-LL, though patients who matched ideal PT had lower rates of PNR (25.0% vs 75.0%). For patients with moderate and severe preoperative SVA, more aggressive correction relative to either ideal postoperative PT or PI-LL was associated with significantly lower rates of pelvic nonresponse (all P < 0.05). For patients with moderate to severe baseline truncal inclination, more aggressive surgical correction relative to ideal age-specific PI-LL was associated with lower rates of pelvic nonresponse. Postoperative alignment targets may need to be adjusted to optimize alignment outcomes for patients with substantial preoperative sagittal deformity. These findings increase our understanding of the poor outcomes that occur despite ideal realignment. Surgical correction of severe global sagittal deformity should be prioritized to mitigate these occurrences.

How Much Lumbar Lordosis does a Patient Need to Reach their Age-Adjusted Alignment Target? A Formulated Approach Predicting Successful Surgical Outcomes.

Retrospective cohort study. Identify optimal lumbar lordosis in adult deformity correction to achieve age-adjusted targets and sustained alignment. Surgical adult spinal deformity patients reaching an age-adjusted ideal alignment at one year were identified. Multilinear regression analysis was used to identify the relationship between regional curvatures (LL and TK) that enabled achievement of a given global alignment (T1 pelvic angle, TPA) based on pelvic incidence (PI). 347 patients out of 1048 available reached their age-adjusted TPA within 5° (60-year-old, 72% women, body mass index 29 ± 6.2). They had a significant improvement in all sagittal parameters (except PI) from pre-operative baseline to 1year following surgery (P < .001). Multilinear regression predicting L1-S1 based on TK, TPA, and PI demonstrated excellent results (R2 = .85). Simplification of the coefficients of prediction combined with a conversion to an age-based formula led to the following: LL = PI - 0.3TK - 0.5Age + 10. Internal validation of the formula led to a mean error of -.4°, and an absolute error of 5.0°. Internal validation on patients with an age-adjusted alignment revealed similar accuracy across the entire age-adjusted TPA spectrum (ranges of LL errors: ME = .2° to 1.7°, AE = 4.0° to 5.3°). This study provides a simple guideline to identify the amount of LL needed to reach a given alignment (i.e., age-adjusted target) based on PI and associated TK. Implementation of this predictive formula during pre-operative surgical planning may help to reduce unexpected sub-optimal post-operative alignment outcomes.

Predictive Analytics for Determining Extended Operative Time in Corrective Adult Spinal Deformity Surgery.

More sophisticated surgical techniques for correcting adult spinal deformity (ASD) have increased operative times, adding to physiologic stress on patients and increased complication incidence. This study aims to determine factors associated with operative time using a statistical learning algorithm. Retrospective review of a prospective multicenter database containing 837 patients undergoing long spinal fusions for ASD. Conditional inference decision trees identified factors associated with skin-to-skin operative time and cutoff points at which factors have a global effect. A conditional variable-importance table was constructed based on a nonreplacement sampling set of 2000 conditional inference trees. Means comparison for the top 15 variables at their respective significant cutoffs indicated effect sizes. Included: 544 surgical ASD patients (mean age: 58.0 years; fusion length 11.3 levels; operative time: 378 minutes). The strongest predictor for operative time was institution/surgeon. Center/surgeons, grouped by decision tree hierarchy, a and b were, on average, 2 hours faster than center/surgeons c-f, who were 43 minutes faster than centers g-j, all P < 0.001. The next most important predictors were, in order, approach (combined vs posterior increases time by 139 minutes, P < 0.001), levels fused (<4 vs 5-9 increased time by 68 minutes, P < 0.050; 5-9 vs < 10 increased time by 47 minutes, P < 0.001), age (age <50 years increases time by 57 minutes, P < 0.001), and patient frailty (score <1.54 increases time by 65 minutes, P < 0.001). Surgical techniques, such as three-column osteotomies (35 minutes), interbody device (45 minutes), and decompression (48 minutes), also increased operative time. Both minor and major complications correlated with <66 minutes of increased operative time. Increased operative time also correlated with increased hospital length of stay (LOS), increased estimated intraoperative blood loss (EBL), and inferior 2-year Oswestry Disability Index (ODI) scores. Procedure location and specific surgeon are the most important factors determining operative time, accounting for operative time increases <2 hours. Surgical approach and number of levels fused were also associated with longer operative times, respectively. Extended operative time correlated with longer LOS, higher EBL, and inferior 2-y ODI outcomes. We further identified the poor outcomes associated with extended operative time during surgical correction of ASD, and attributed the useful predictors of time spent in the operating room, including site, surgeon, surgical approach, and the number of levels fused.

Health-related quality of life measures in adult spinal deformity: can we replace the SRS-22 with PROMIS?

To determine the validity and responsiveness of PROMIS metrics versus the SRS-22r questionnaire in adult spinal deformity (ASD). Surgical ASD patients undergoing ≥ 4 levels fused with complete baseline PROMIS and SRS-22r data were included. Internal consistency (Cronbach's alpha) and test-retest reliability [intraclass correlation coefficient (ICC)] were compared. Cronbach's alpha and ICC values ≥ 0.70 were predefined as satisfactory. Convergent validity was evaluated via Spearman's correlations. Responsiveness was assessed via paired samples t tests with Cohen's d to assess measure of effect (baseline to 3 months). One hundred and ten pts are included. Mean baseline SRS-22r score was 2.62 ± 0.67 (domains = Function: 2.6, Pain: 2.5, Self-image: 2.2, Mental Health: 3.0). Mean PROMIS domains = Physical Function (PF): 12.4, Pain Intensity (PI): 91.7, Pain Interference (Int): 55.9. Cronbach's alpha, and ICC were not satisfactory for any SRS-22 and PROMIS domains. PROMIS-Int reliability was low for all SRS-22 domains (0.037-0.225). Convergent validity demonstrated strong correlation via Spearman's rho between PROMIS-PI and overall SRS-22r (- 0.61), SRS-22 Function (- 0.781), and SRS-22 Pain (- 0.735). PROMIS-PF had strong correlation with SRS-22 Function (0.643), while PROMIS-Int had moderate correlation with SRS-22 Pain (- 0.507). Effect size via Cohen's d showed that PROMIS had superior responsiveness across all domains except for self-image. PROMIS is a valid measure compared to SRS-22r in terms of convergent validity, and has greater measure of effect in terms of responsiveness, but failed in reliability and internal consistency. Surgeons should consider the lack of reliability and internal consistency (despite validity and responsiveness) of the PROMIS to SRS-22r before replacing the traditional questionnaire with the computer-adaptive testing.

Increasing Cost Efficiency in Adult Spinal Deformity Surgery: Identifying Predictors of Lower Total Costs.

Retrospective study of a prospective multicenter database. The purpose of this study was to identify predictors of lower total surgery costs at 3 years for adult spinal deformity (ASD) patients. ASD surgery involves complex deformity correction. Inclusion criteria: surgical ASD (scoliosis ≥20°, sagittal vertical axis [SVA] ≥5 cm, pelvic tilt ≥25°, or thoracic kyphosis ≥60°) patients >18 years. Total costs for surgery were calculated using the PearlDiver database. Cost per quality-adjusted life year was assessed. A Conditional Variable Importance Table used nonreplacement sampling set of 20,000 Conditional Inference trees to identify top factors associated with lower cost surgery for low (LSVA), moderate (MSVA), and high (HSVA) SRS Schwab SVA grades. Three hundred sixtee of 322 ASD patients met inclusion criteria. At 3-year follow up, the potential cost of ASD surgery ranged from $57,606.88 to $116,312.54. The average costs of surgery at 3 years was found to be $72,947.87, with no significant difference in costs between deformity groups (P > 0.05). There were 152 LSVA patients, 53 MSVA patients, and 111 HSVA patients. For all patients, the top predictors of lower costs were frailty scores <0.19, baseline (BL) SRS Activity >1.5, BL Oswestry Disability Index <50 (all P < 0.05). For LSVA patients, no history of osteoporosis, SRS Activity scores >1.5, age <64, were the top predictors of lower costs (all P < 0.05). Among MSVA patients, ASD invasiveness scores <94.16, no past history of cancer, and frailty scores <0.3 trended toward lower total costs (P = 0.071, P = 0.210). For HSVA, no history of smoking and body mass index <27.8 trended toward lower costs (both P = 0.060). ASD surgery has the potential for improved cost efficiency, as costs ranged from $57,606.88 to $116,312.54. Predictors of lower costs included higher BL SRS activity, decreased frailty, and not having depression. Additionally, predictors of lower costs were identified for different BL deformity profiles, allowing for the optimization of cost efficiency for all patients.Level of Evidence: 3.

247. Multidisciplinary conference for complex surgery leads to improved quality and safety

<h3>BACKGROUND CONTEXT</h3> Complex surgery for adult spinal deformity has high rates of complications, reoperations, and readmissions. Multidisciplinary conferences have been shown to improve patient outcomes in many medical specialties but are not currently widespread in spine surgery. Preoperative discussions of high-risk operative spine patients at a multidisciplinary conference may decrease rates of these adverse outcomes through appropriate patient selection and surgical plan optimization. With this goal, we implemented a high-risk case conference involving orthopedic and neurosurgery spine, anesthesia, intraoperative monitoring neurology, and neurological intensive care on 2/19/2019. <h3>PURPOSE</h3> Examine rates of intraoperative and postoperative complications, readmissions, and reoperations in high-risk spine patients before and after the implementation of a multidisciplinary high risk case conference. <h3>STUDY DESIGN/SETTING</h3> Single institution retrospective review. <h3>PATIENT SAMPLE</h3> This study included 236 surgical adult spinal deformity patients who met one of the following criteria for presentation to the conference: 8+ levels fused, osteoporosis with 4+ levels fused, 3-column osteotomy, anterior revision of the same lumbar level, or severe myelopathy, scoliosis (>75˚), or kyphosis (>75˚) with planned significant correction. <h3>OUTCOME MEASURES</h3> Intra- and postoperative complications and 30- and 90-day readmissions and reoperations. <h3>METHODS</h3> Retrospective review was performed for the patient sample. Patients were categorized as Before Conference (BC): surgery before 2/19/2019 or After Conference (AC): surgery after 2/19/2019. Statistical analysis included independent samples t-tests and chi-squared analysis with significance set at p<0.05. <h3>RESULTS</h3> A total of 236 patients were included (67 AC, 169 BC). AC was older than BC (60.2 vs 54.4, p=0.033), but had similar BMI (27.0 vs 29.0, p=0.061), CCI (3.27 vs 2.92 p=0.266), and ASA classification (2.5 vs 2.6, p=0.911). Surgical characteristics, including levels fused (10.4 vs 10.7, p=0.558), levels decompressed (1.5 vs 1.2, p=0.375), 3-column osteotomies (11.9% vs 18.3%, p=0.232), anterior column release (13.4% vs 12.4%, p=0.834), and revision cases (50.7% vs 52.4%, p=0.821) were similar between AC and BC. AC had lower EBL (1174.0 vs 1850.2, p=0.001), fewer intraoperative complications (17.9% vs 33.7%, p=0.016) and fewer delayed extubations (6.0% vs 22.5%, p=0.003). Length of stay was similar between groups (7.0 vs 8.1, 0.245). AC had a lower incidence of DVT/PE (0% vs 5.9%, p=0.042), but a higher rate of hypotension requiring vasopressor therapy (19.4% vs 4.7%, p=0.002). Other postoperative complications were similar between groups. AC had lower rates of reoperation at 30 (0% vs 8.9%, p=0.012) and 90 days (1.5% vs 12.4%, p=0.009). AC trended toward lower readmission rates at 30 (4.5% vs 10.7%, p=0.133) and 90 days (7.5% vs 15.4%, p=0.104). <h3>CONCLUSIONS</h3> Following implementation of a multidisciplinary high-risk case conference, 30- and 90-day reoperation rates and intraoperative complications decreased in the high-risk spine surgery population. Postoperative thromboembolic events decreased. Hypotensive events requiring vasopressors increased, but this did not result in a longer length of stay or greater readmissions. These results demonstrate the important role of this conference in improving quality and safety for high-risk spine patients. Multidisciplinary conferences should be considered to minimize complications and optimize outcomes in complex spine surgery. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

34. Optimal intraoperative fluid management in adult spinal deformity correction surgery

<h3>BACKGROUND CONTEXT</h3> Intraoperative fluid management is a vital component in adult spinal deformity (ASD) surgery that is not standardized nor has consensus on the ideal management. Increased intraoperative use of crystalloids and colloids is correlated with an increased risk for developing postoperative complications, especially pulmonary complications. <h3>PURPOSE</h3> This study aims to assess and describe the fluid management protocol for ASD at a single-center with minimal pulmonary complications, high intraoperative extubation rate, and no intraoperative coagulopathies. Hypothesis: Intraoperative fluid management using liberal amounts of crystalloids and reduced colloids is safe and results in optimal postoperative outcomes in ASD correction surgery. <h3>STUDY DESIGN/SETTING</h3> Observational, retrospective cohort. <h3>PATIENT SAMPLE</h3> A total of 161 consecutive surgical adult spinal deformity patients at a single institution. <h3>OUTCOME MEASURES</h3> Postoperative pulmonary complications and length of stay. <h3>METHODS</h3> A total of 161 consecutive ASD patients who underwent corrective surgery at a single institution were included. Preop medical records, intraoperative anesthesia and surgical records, and postop complications were compiled. Descriptive statistics including means, percentages, and ratios were calculated. <h3>RESULTS</h3> Average age was 44.6±18.7 years, 67% (108) were female, and 53% (85) were primary cases. The average number of levels fused was 11.4±5.2 and an average length of surgery of 7.4±2.4 hours. 18% (26) of patients had a 3-column osteotomy (PSO or VCR) and the average estimated blood loss was 1373±793ccs. Only 50.3% of patients received an intraoperative packed red blood cell transfusion and there was 1 patient that received platelets and 3 patients that received fresh frozen plasma transfusions. Average intraoperative crystalloids given was 4917±1778cc while the average colloids given was 1565±1190cc. The ratio of crystalloids:colloids administered intraoperatively was 3.1:1. A total of 84% (135) were extubated intraoperatively. Twenty patients had postoperative pulmonary complications of either pulmonary edema or pleural effusion and 2 patients had a pulmonary embolism, with an average length of stay of 7.0±3.9 days. <h3>CONCLUSIONS</h3> Minimizing blood loss and administering a 3:1 ratio of crystalloids:colloids is an optimal intraoperative fluid management protocol that results in no intraoperative coagulopathies, an 84% intraoperative extubation rate, and minimal postoperative pulmonary complications in adult spinal deformity correction surgery. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

187. Lumbar lordosis is primarily lost in the upper lumbar spine in ASD patients with sagittal deformities

<h3>BACKGROUND CONTEXT</h3> In asymptomatic individuals, two-thirds of the lordosis comes from the L4-S1 level. It is commonly believed that the majority of loss of lordosis in adult spinal deformity (ASD) is attributable to the distal (L4-S1) levels. <h3>PURPOSE</h3> This study aims to investigate the location of loss of lordosis in a cohort of ASD patients prior to surgical intervention. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of prospective databases. <h3>PATIENT SAMPLE</h3> This study included 119 symptomatic adult volunteer and 357 adult spinal deformity patients. <h3>OUTCOME MEASURES</h3> Regional and focal alignment. Lordosis distribution. <h3>METHODS</h3> A registry of asymptomatic volunteers was used to build age and pelvic incidence (PI) adjusted normative models of PI-LL, L1-L4 lordosis, L4-S1 lordosis, TL kyphosis (T10-L2), and thoracic kyphosis (T1-T12). Our study cohort was a registry of surgical primary ASD patients without coronal malalignment (SRS-Schwab Type=N). The formulas developed in the asymptomatic population were applied to the ASD group to calculate normative values for each patient. The ASD population was divided into four groups based on quartiles of PI-LL: no, mild, moderate, and severe PI-LL mismatch. Within each group, paired t-tests were performed to compare actual and calculated normative sagittal alignment; actual alignment was also expressed in percentage of normative values. The level of significance was p<0.05. <h3>RESULTS</h3> The asymptomatic cohort used included 119 asymptomatic volunteers (50.7yo±17, PI: 52°±11.4) with the following regional alignment: L4-S1=34°, L1-L4=23°, TKL=3°, and TK=49°. The study cohort included 357 ASD patients (64.6yo, 58.5%F). The PI-LL of the 4 quartiles were -10°, 10°, 20°, and 40°. There were no significant differences in PI or in any of the coronal Cobb angles. Comparing each ASD group to the calculated normative values; the "no mismatch" group had a greater L4-S1 (+8°), a greater T10-L2 kyphosis (+14°) and T1-T12 kyphosis (+8°), but no difference in L1-L4. The "mild mismatch" group had a smaller L1-L4 (-12°), greater TLK (+5°), smaller TK (-7°) and no difference in L4-S1. The "moderate mismatch" had a smaller L4-S1 (-7°), L1-L4 (-15°), TK (-15°) but no difference in TLK. Finally, the "severe mismatch" group had a smaller L4-S1 (-15°), L1-L4 (-26°), and TK (-27°) but no difference in TKL (all with p<0.001). The analysis by percentage of actual alignment vs the calculated age and PI matched normative values permitted to identify the driver(s) of the sagittal malalignment. The "no mismatch" had an excess of TLK (+510%) compensated by an excess in L4-S1 (+27%). The "mild mismatch" had a loss of L1-L4 (-48%) with a normal L4-S1, while the "moderate mismatch" had mainly a deficit in L1-L4 (-66%) associated to a 22% loss on L4-S1. Finally, "severe-mismatch" presented a kyphotic L1-L4 (-115% vs norm) with a 46% deficit in L4-S1 <h3>CONCLUSIONS</h3> In this cohort of ASD patients with limited coronal deformity, the majority of the loss of lordosis is attributable to the proximal segment. As the deformity worsened, the loss of lordosis also involved the distal lumbar segments. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P85. Delayed staging during same hospitalization increases complication risk following adult spinal deformity surgery

<h3>BACKGROUND CONTEXT</h3> Since circumferential adult spinal deformity (ASD) surgery can lead to high surgical burden for the patient, surgeons may elect to stage these procedures during the same hospitalization. As a result, there is a trend toward planning same-hospitalization staged ASD surgeries by performing an anterior lumbar interbody fusion (ALIF) prior to a subsequent staged posterior fusion. <h3>PURPOSE</h3> The aim of this study was to determine optimal timing for staging (early vs delayed) thoracolumbar ASD surgery within the same hospitalization. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of a multicenter database. <h3>PATIENT SAMPLE</h3> A total of 158 surgical ASD patients undergoing anterior and staged posterior spinal fusion ≥5 levels. <h3>OUTCOME MEASURES</h3> Our outcome measures were 90-day complication rates, postoperative alignment, and 2-year ODI. <h3>METHODS</h3> Using a prospective, multicenter database, we identified 158 surgical ASD patients undergoing first an anterior surgery followed by a staged posterior spinal fusion ≥5 levels during the same hospitalization. Stratum-specific likelihood ratio (SSLR) analysis was performed to calculate a cutoff point beyond which 90-day complications were increased. The cutoff generated through SSLR were confirmed with multivariable logistic regression analysis controlling for age, gender, levels fused for each stage, preoperative alignment, three-column osteotomy, and Charlson Comorbidity Index. The outcome measures were 90-day complication rates, postoperative alignment, and 2-year ODI. Multivariable analyses were performed with logistic, Poisson and linear regressions where appropriate. <h3>RESULTS</h3> Utilization of staged procedures increased 4x from 2008-2019, and the mean staging interval was 3 days (range 1-8). On SSLR analysis, patients were divided into two staging categories based on complication risk: early (<6 days, range 1-5, N=139) versus delayed (≥ 6 day, range 6-8, N=19). On bivariate analysis, the delayed group had higher 90-day complication rates (68.4% vs 32.4%, p=0.002) and longer operative times (638 min vs 739 min, p=0.020) relative to the early group. Adjusting for covariates on multivariable analysis, patients with delayed staging had significantly greater odds of 90-day complications (OR=7.57, p=0.006), and longer total operative time (beta=119, p=0.035). With respect to specific complications, delayed staging carries increased odds of infection compared to early staging (OR=11.8 p=0.031). There were no significant differences in postoperative alignment or 2-year ODI between the groups (p>0.05 for all). <h3>CONCLUSIONS</h3> Compared to early staging (< 6 days) of ALIF and subsequent staged posterior fusion, delayed staging (≥ 6 days) is associated with greater odds of 90-day complications, particularly infection. With the growing trend toward staged ASD surgeries, efforts should be made to shorten the interval between ALIF and subsequent posterior fusion. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Frequency and Implications of Concurrent Complications Following Adult Spinal Deformity Corrective Surgery

Retrospective review. Identify co-occurring perioperative complications and associated predictors in a population of patients undergoing surgery for adult spinal deformity (ASD). Few studies have investigated the development of multiple, co-occurring complications following ASD-corrective surgery. Preoperative risk stratification may benefit from identification of factors associated with multiple, co-occurring complications. Elective ASD patients in National Surgical Quality Improvement Program (NSQIP) 2005 to 2016 were isolated; rates of co-occurring complications and affected body systems were assessed via cross tabulation. Random forest analysis identified top patient and surgical factors associated with complication co-occurrence, using conditional inference trees to identify significant cutoff points. Binary logistic regression indicated effect size of top influential factors associated with complication co-occurrence at each factor's respective cutoff point. Included: 6486 ASD patients. The overall perioperative complication rate was 34.8%; 28.5% of patients experienced one complication, 4.5% experienced two, and 1.8% experienced 3+. Overall, 11% of complication co-occurrences were pulmonary/cardiovascular, 9% pulmonary/renal, and 4% integumentary/renal. By complication type, the most common co-occurrences were transfusion/urinary tract infection (UTI) (24.3%) and transfusion/pneumonia (17.7%). Surgical factors of operative time ≥400 minutes and fusion ≥9 levels were the strongest factors associated with the incidence of co-occurring complications, followed by patient-specific variables like American Society of Anesthesiologists (ASA) physical status classification grade ≥2 and age ≥65 years. Regression analysis further showed associations between increasing complication number and longer length of stay (LOS), (R2 = 0.202, P < 0.001), non-home discharge (R2 = 0.111, P = 0.001), and readmission (R2 = 0.010, P < 0.001). For surgical ASD patients, the overall rate of co-occurring perioperative complications was 6.3%. Body systems most commonly affected by complication co-occurrences were pulmonary and cardiovascular, and common co-occurrences included transfusion/UTI (24.3%) and transfusion/pneumonia (17.7%). Increasing number of perioperative complications was associated with greater LOS, non-home discharge, and readmission, highlighting the importance of identifying risk factors for complication co-occurrences.Level of Evidence: 3.

Does Matching Roussouly Spinal Shape and Improvement in SRS-Schwab Modifier Contribute to Improved Patient-reported Outcomes?

Retrospective review. The aim of this study was to evaluate outcomes of matching Roussouly and improving in Schwab modifier following adult spinal deformity (ASD) surgery. The Roussouly Classification system of sagittal spinal shape and the SRS-Schwab classification system have become important indicators of spine deformity. No previous studies have examined the outcomes of matching both Roussouly type and improving in Schwab modifiers postoperatively. Surgical ASD patients with available baseline (BL) and 1 year (1Y) radiographic data were isolated in the single-center spine database. Patients were classified by their "theoretical" and "current" Roussouly types as previously published. Patients were considered a "Match" if their theoretical and current Roussouly types were the same, or a "Mismatch" if the types differed. Patients were noted as improved if they were Roussouly "Mismatch" preoperatively, and "Match" at 1Y postop. Schwab modifiers at BL were categorized as follows: no deformity (0), moderate deformity (+), and severe deformity (++) for PT, SVA, and PI-LL. Improvement in SRS-Schwab was defined as a decrease in any modifier severity at 1Y. 103 operative ASD patients (61.8 years, 63.1% female, 30 kg/m2) were included. At baseline, breakdown of "current" Roussouly type was: 28% Type 1, 25.3% Type 2, 32.0% Type 3, 14.7% Type 4. 65.3% of patients were classified as Roussouly "Mismatch" at BL. Breakdown of BL Schwab modifier severity: PT (+: 41.7%, ++: 49.5%), SVA (+: 20.3%, ++: 50%), PI-LL (+: 25.2%, ++: 46.6%). At 1 year postop, 19.2% of patients had Roussouly "Match". Analysis of Schwab modifiers showed that 12.6% improved in SVA, 42.7% in PI-LL, and 45.6% in PT. Count of patients who both had a Roussouly type "Match" at 1Y and improved in Schwab modifier severity: nine PT (8.7%), eight PI-LL (7.8%), and two SVA (1.9%). There were two patients (1.9%) who met their Roussouly type and improved in all three Schwab. 1Y matched Roussouly patients improved more in health-related quality of life scores (minimal clinically important difference [MCID] for Oswestry Disability Index [ODI], EuroQol-5D-3L [EQ5D], Visual Analogue Score Leg/Back Pain), compared to mismatched, but was not significant (P > 0.05). Match Roussouly and improvement in PT Schwab met MCID for EQ5D more (P = 0.050). Matched Roussouly and improvement in SVA Schwab met MCID for ODI more (P = 0.024). Patients who both matched Roussouly sagittal spinal type and improved in SRS-Schwab modifiers had superior patient-reported outcomes. Utilizing both classification systems in surgical decision-making can optimize postop outcomes.Level of Evidence: 3.

291. Adjustment of the global alignment and proportion scores accounting for frailty in adult spinal deformity surgical patients

BACKGROUND CONTEXT Frailty is a baseline measure of disability that transcends age alone and has been determined a strong predictor of outcomes following adult spinal deformity (ASD) surgery. This postop impact calls for investigation of unique adjustment of Global Alignment and Proportion (GAP) scores accounting for frailty. This adjustment in spinal proportion may help surgical planning for individualized, optimal postop outcomes. PURPOSE Modify the GAP score with frailty to optimize outcomes in surgical ASD patients. STUDY DESIGN/SETTING Retrospective review of a single-surgeon comprehensive ASD database PATIENT SAMPLE A total of 140 ASD patients OUTCOME MEASURES Frailty-adjusted GAP scores; Health Related Quality of Life scores (HRQLs): ODI, SRS-22 METHODS Surgical ASD patients (SVA≥5cm, PT≥25°, or TK ≥60°, >3 levels fused) ≥18 years old with available baseline (BL) radiographic data were isolated in the single-center Comprehensive Spine Quality Database (Quality). Patients were dichotomized by the ASD frailty index, F (Not Frail, Frail). Linear regression analysis established radiographic equations for frailty-adjusted GAP Scores at baseline and 2-years involving relative pelvic version, relative lumbar lordosis, lordosis distribution index, relative spinopelvic alignment, and an age factor to formulate a sagittal plane score. Patients were restratified into frailty-adjusted proportionality groups: Proportional ( 7). Frailty-adjusted GAP proportionality at 2-years were compared to adjusted-BL to determine whether patients improved, deteriorated or remained the same in their spine proportion. RESULTS A total of 140 patients were included (55.5±16.4 yrs, 77.5% female, 25.2±4.7 kg/m2). BL frailty: 32.8% not frail, 67.2% frail. Primary analyses demonstrated correlation between BL frailty score and BL and 2-year GAP scores(P 33.5%) compared to Proportional (12.8%), p=0.015. SD 2-year patients developed increased PJK at the 1-year mark (40%, Proportional: 13.9%, MD:7.1%, p=0.003), as well as had worse 2-year ODI and SRS-22 satisfaction scores(p CONCLUSIONS Significant associations exist between frailty and spinal proportion. By adjusting the GAP proportionality groups accounting for baseline frailty contributed to improved outcomes and minimized reoperations. The adjusted GAP groups appeal for less rigorous spine proportion goals in severely frail patients. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

245. Predicting massive intraoperative blood loss in adult spinal deformity surgery

BACKGROUND CONTEXT Due to inherent patient and surgical factors, some adult spinal deformity patients are at higher risk of larger blood loss. This is associated with increased risk of complications, coagulopathy, and higher requirements for blood component replacement intraoperatively. The medical team should be aware of expected blood loss in order to adequately plan patient monitoring and blood product requirements. PURPOSE This study aims to develop and validate a model based on patient characteristics and surgical strategies to predict which patients undergoing adult spinal deformity surgery are at greater risk of massive intra-operative blood loss. STUDY DESIGN/SETTING Retrospective analysis of a multicenter prospective database. PATIENT SAMPLE Surgical ASD patients undergoing long fusions (>5 levels). OUTCOME MEASURES Massive intraoperative blood loss (>7% of a patient's ideal body weight), ICU stay, complications. METHODS Surgical adult spinal deformity patients undergoing long fusions (> 5 levels) were analyzed. Massive blood loss was defined as an intraoperative blood loss over 7% of a patients’ ideal body weight, in accordance to the anesthesia literature. The impact of mEBL on complications and ICU stay was assessed through multivariate poisson and logistic regression, adjusting for baseline patient demographics and magnitude of surgery. Multivariate logistic regression modeling was used to build a prediction model of mEBL. Potential predictors were identified using univariate analysis. The model was built using a combination of backward elimination and bootstrap selection. Model fit was assessed using the Hosmer-Lemeshow test and the ROC curve. Split sample internal cross-validation was performed. RESULTS A total of 1,205 patients met inclusion criteria, and mEBL occurred in 7.8% (94/1205) of cases. In this cohort, mEBL was an independent risk factor for major complications (IRR 2.89, p=0.0001), and postoperative ICU stay (OR 4.68, p=0.001). Predictors of mEBL included: revision surgery (OR 1.66, p=0.05), performing a three-column osteotomy (OR 2.65, p=0.0001), number of levels fused (OR 1.19, p=0.0001), number of levels decompressed (OR 1.15, p=0.004), and number of LLIF interbodies (OR 0.69, p=0.066). The predictive model had a good discrimination (ROC curve 0.76), and good calibration (Hosmer-Lemeshow p=0.39), which held true when performing split-sample cross-validation. CONCLUSIONS We built and validated a model to predict massive intra operative blood loss in ASD surgery. In this model, baseline patient demographics and elements of the surgical strategy are used to predict which patients are at greater risk for massive blood loss. This tool would be of particular help to the anesthesia team, allowing to identify preoperatively which patients are at greater risk and plan intraoperative care and fluid management accordingly. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

211. Complications and outcomes in small vs large surgeries for ASD?

BACKGROUND CONTEXT Traditionally, adult spinal deformity (ASD) has been treated with long segment fusions with the goal of restoring sagittal and coronal alignment. Long segment fusions can be associated with high rates of complications and morbidity. Some patients are reluctant to undergo large procedures. Others have comorbidities excluding them as good surgical candidates for long fusions. PURPOSE To compare baseline and postoperative HRQL and radiographic outcomes and revisions and complications in small vs longer fusions for ASD. STUDY DESIGN/SETTING Retrospective analysis of a prospective, multicenter database PATIENT SAMPLE Surgical ASD patients OUTCOME MEASURES ODI, SF36-PCS, SRS22, NRS back and leg pain. METHODS A prospective database of operative ASD patients who completed two year follow up was analyzed. Prior thoracolumbar fusions were excluded. Patients were divided into short fusions (SF: £3 levels) and long fusions (LF: ³6 levels). LF and SF patients were compared in baseline alignment. Propensity matching (PSM) controlling for baseline alignment (TPA and maximum coronal cobb) was performed to compare SF and LF in HRQL improvement, postop alignment and complications. Subanalysis of SF identified which patients were more likely to have successful surgery. The level of significance was p RESULTS A total of 298 patients met inclusion criteria (SF n=20, mean levels fused 2.13; LF n=275, mean fusion levels 12.33). Prior to PSM, LF had greater PT, coronal cobb, and TPA. Following PSM, LF had better improvements in PILL (20.8 vs 3.37), PT (8.57 vs 0.21), TPA (8.68 vs 2.07), and coronal cobb (17.3 vs 5.33) all p CONCLUSIONS This study shows that a more limited fusion could be an alternative to the more traditional long segment fusion in carefully selected patients with adult spinal deformity since there were fewer complications but similar short-term (2-year) satisfaction rates and HRQL improvements. Patients undergoing long fusions had better improvements in alignment. The majority of sagittal only deformities undergoing short fusions required revision surgery. The durability of short fusions in the setting of ASD needs to be investigated with long term studies. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

P11. How much lumbar lordosis does a patient need to reach their age-adjusted alignment target? A formulated approach predicting successful surgical outcomes

BACKGROUND CONTEXT Age-adjusted alignment targets for adult spinal deformity (ASD) patients have the potential to reduce the incidence of PJK while ensuring optimal HRQL. Previous studies demonstrated the interplay between lumbar lordosis (LL) and thoracic kyphosis (TK) and their relationship with pelvic morphology as measured by the plevic incidence (PI). In clinical practice, reaching this ideal alignment remains challenging as the relationship between lordosis and kyphosis is not clearly elucidated. PURPOSE This study aimed at developing a pragmatic formula on how much lumbar lordosis is needed based on the patient age, PI and exiting thoracic kyphosis. STUDY DESIGN/SETTING Multicenter retrospective review of a prospective database. PATIENT SAMPLE A total of 347 adult spinal deformity patients reaching age-adjusted alignment at 1-year post surgery. OUTCOME MEASURES Sagittal alignment and internal validation of predictive formula. METHODS Surgical ASD patients reaching an age-adjusted ideal alignment at one year were identified. Multilinear regressions analysis was used to identify the relationship between regional curvatures (LL &TK) permitting to reach a given global alignment (TPA) based on pelvic incidence. RESULTS The 347 patients included (60 years old, 72% female, BMI 29±6.2) had a significant improvement in all sagittal parameters from pre-op to 1Y (p CONCLUSIONS This study provides a simple guideline to identify the amount of lordosis needed to reach a given alignment (ie, age-adjusted target) based on pelvic incidence and associated thoracic kyphosis. Implementation of this predictive formula during pre-operative surgical planning can help to reduce unexpected sub-optimal post-operative alignment outcomes. These values could be integrated into pre-contoured rods for true patient specific alignment. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.