Schwab Modifier Research Articles

Surgical treatment of Roussouly type 1 with realigning Roussouly spinal shape and improving SRS-Schwab modifier: effect on minimal clinically important difference.

To evaluate outcomes of choosing different Roussouly shapes and improving in Schwab modifiers for surgical Roussouly type 1 patients. Baseline (BL) and 2-year (2Y) clinical data of adult spinal deformity (ASD) patients presenting with Roussouly type 1 sagittal spinal alignment were isolated in the single-center spine database. Patients were grouped into Roussouly type 1, 2 and 3 with anteverted pelvis (3a) postoperatively. Schwab modifiers at BL and 2Y were categorized as follows: no deformity (0), moderate deformity (+), and severe deformity (++) for pelvic tilt (PT), sagittal vertical axis (SVA), and pelvic incidence and lumbar lordosis mismatch (PI-LL). Improvement in SRS-Schwab was defined as a decrease in the severity of any modifier at 2Y. A total of 96 patients (69.9 years, 72.9% female, 25.2kg/m2) were included. At 2Y, there were 34 type 1 backs, 60 type 2 backs and only 2 type 3a. Type 1 and type 2 did not differ in rates of reaching 2Y minimal clinically important difference (MCID) for health-related quality of life (HRQOL) scores (all P > 0.05). Two patients who presented with type 3a had poor HRQOL scores. Analysis of Schwab modifiers showed that 41.7% of patients improved in SVA, 45.8% in PI-LL, and 36.5% in PT. At 2Y, patients who improved in SRS-Schwab PT and SVA had lower Oswestry disability index (ODI) scores and significantly more of them reached MCID for ODI (all P < 0.001). Patients who improved in SRS-Schwab SVA and PI-LL had more changes of VAS Back and Short Form-36 (SF-36) outcomes questionnaire physical component summary (SF-36 PCS), and significantly more reached MCID (all P < 0.001). By 2Y, type 2 patients who improved in SRS-Schwab grades reached MCID for VAS back and ODI at the highest rate (P = 0.003, P = 0.001, respectively), and type 1 patients who improved in SRS-Schwab grades reached MCID for SF-36 PCS at the highest rate (P < 0.001). For ASD patients classified as Roussouly type 1, postoperative improvement in SRS-Schwab grades reflected superior patient-reported outcomes while type 1 and type 2 did not differ in clinical outcomes at 2Y. However, development of type 3a should be avoided at the risk of poor functional outcomes. Utilizing both classification systems in surgical decision-making can optimize postoperative outcomes.

Can Baseline Disability Predict Outcomes in Adult Spinal Deformity Surgery?

Retrospective Cohort Study. To assess if there is a threshold of baseline disability beyond which the patient-reported outcomes after surgical correction of adult spinal deformity (ASD) are adversely impacted. Patient-reported outcomes vary after correction of adult spinal deformity, even when patients are optimally realigned. There is a paucity of literature examining the impact of baseline disability on patient-reported outcomes in ASD. Patients with baseline (BL) and two-year data were included. Disability was ranked according to BL Oswestry Disability Index (ODI) into quintiles: Q1 (lowest ODI score) to Q5 (highest ODI score). Adjusted logistic regression analyses evaluated the likelihood of reaching ≥1 MCID in Scoliosis Research Society Outcomes Questionnaire (SRS-22) Pain, SRS-22 Activity, and Short Form-36 physical component summary at two years across disability groups Q1-Q4 with respect to Q5. Sensitivity tests were performed, excluding patients with any "0" Schwab modifiers at BL. Compared with patients in Q5, the odds of reaching MCID in SRS-22 Pain at 2Y were significantly higher for those in Q1 (OR: 3.771), Q2 (OR: 3.006), and Q3 (OR: 2.897), all P <0.021. Similarly, compared with patients in Q5, the odds of reaching MCID in SRS-22 Activity at two years were significantly higher for those in Q2 (OR: 3.454) and Q3 (OR: 2.801), both P <0.02. Lastly, compared with patients in Q5, odds of reaching MCID in Short Form-36 physical component summary at two years were significantly higher for patients in Q1 (OR: 5.350), Q2 (OR: 4.795), and Q3 (OR: 6.229), all P <0.004. This study found that patients presenting with moderate disability at BL (ODI<40) consistently surpassed health-related quality of life outcomes as compared with those presenting with greater levels of disability. We propose that a baseline ODI of 40 represents a disability threshold within which operative inte rvention maximizes patient-reported outcomes. Furthermore, delaying the intervention until patients progress to severe disability may limit the benefits of surgical correction in ASD patients. 3.

When Not to Operate in Spinal Deformity: Identifying Subsets of Patients with Simultaneous Clinical Deterioration, Major Complications, and Reoperation.

Retrospective review of a prospectively enrolled adult spinal deformity (ASD) database. To investigate what patient factors elevate the risk of sub-optimal outcomes after deformity correction. Currently, it is unknown what factors predict a poor outcome after adult spinal deformity surgery, which may require increased pre-operative consideration and counseling. Patients >18yrs undergoing surgery for ASD(scoliosis≥20°, SVA≥5cm, PT≥25°, or TK≥60°). An unsatisfactory outcome was defined by the following categories met at 2Y: (1) clinical: deteriorating in ODI at 2Y f/u (2) complications/reop: having a reoperation and major complication were deemed high risk for poor outcomes postoperatively (HR). Multivariate analyses assessed predictive factors of HR patients in adult spinal deformity patients. 633 ASD (59.9 years, 79%F, 27.7kg/m2, CCI: 1.74) were included. Baseline severe Schwab modifier incidence (++): 39.2% PI-LL, 28.8% SVA, 28.9% PT. 15.5% of patients deteriorated in ODI by 2 years, while 7.6% underwent a reoperation and had a major complication. This categorized 11 (1.7%) as HR. HR were more comorbid in terms of arthritis (73%) heart disease (36%) and kidney disease (18%), P<0.001. Surgically, HR had greater EBL (4431ccs), underwent more osteotomies (91%), specifically Ponte(36%) and Three Column Osteotomies(55%), which occurred more at L2(91%). HR underwent more PLIFs (45%) and had more blood transfusion units (2641ccs), all P<0.050. The multivariate regression determined a combination of a baseline DRAM score in the 75th percentile, having arthritis and kidney disease, a baseline right lower extremity motor score ≤3, cSVA >65mm, C2 slope >30.2°, CTPA >5.5° for an R2 value of 0.535 (P<0.001). When addressing adult spine deformities, poor outcomes tends to occur in severely comorbid patients with major baseline psychological distress scores, poor neurologic function, and concomitant cervical malalignment.

181 Costs of Surgery in Adult Spinal Deformity: Do Higher Cost Surgeries Lead to Better Outcomes?

INTRODUCTION: With increased focus on delivering cost effective healthcare, interventions associated with high resource utilization, such as adult spinal deformity (ASD) surgery, have received greater scrutiny. METHODS: A retrospective analysis of a single-center ASD database. ASD patients ≥18 years with baseline (BL) and 2-year (2Y) data were included. Surgical costs were calculated based on 2021 average Medicare reimbursement by CPT code. Costs of complications and reoperations were intentionally excluded. Patients were ranked into tertiles by surgical cost. The tertile with the highest surgical costs (HC) and lowest surgical costs (LC) were propensity score matched (PSM’d) to account for differences in baseline age and deformity. Multivariable logistic regressions assessed odds of achieving outcomes of interest in PSM’d groups. RESULTS: 421 patients met inclusion (139 LC; 127 HC). After PSM, 102 patients remained in each cost group with an average reimbursement of LC: $11,279 vs. HC: $29,274. PSM’d groups had similar demographics and baseline deformity (all p &gt;.05). Compared to LC patients, HC had higher odds of meeting SCB in SRS-22-Total (OR: 2.461, [1.321, 4.586], p = .005) and higher odds of meeting SCB in NRS Back (OR:1.961, [1.032, 3.723], p = .040). With respect to deformity, HC patients were more likely to have “0” Schwab modifier at 2Y in SVA (OR: 5.736, [2.798, 11.761], p&lt;.001), PI-LL (OR: 2.239, [1.100, 4.559], p = .026), and PT (OR: 2.456, [1.335, 4.518], p = .004). CONCLUSIONS: While patient presentation impacts surgical planning and costs, we sought to control for such variations to assess association between surgical costs and outcomes. Although higher cost did not guarantee an ideal outcome, high cost patients generally experienced superior patient reported outcomes and realignment at 2-years. Thus, isolating cost reduction as a public health priority may compromise outcomes in ASD patients.

Natural history of adult spinal deformity: how do patients with suboptimal surgical outcomes fare relative to nonoperative counterparts?

Management of adult spinal deformity (ASD) has increasingly favored operative intervention; however, the incidence of complications and reoperations is high, and patients may fail to achieve idealized postsurgical results. This study compared health-related quality of life (HRQOL) metrics between patients with suboptimal surgical outcomes and those who underwent nonoperative management as a proxy for the natural history (NH) of ASD. ASD patients with 2-year data were included. Patients who were offered surgery but declined were considered nonoperative (i.e., NH) patients. Operative patients with suboptimal outcome (SOp)-defined as any reoperation, major complication, or ≥ 2 severe Scoliosis Research Society (SRS)-Schwab modifiers at follow-up-were selected for comparison. Propensity score matching (PSM) on the basis of baseline age, deformity, SRS-22 Total, and Charlson Comorbidity Index score was used to match the groups. ANCOVA and stepwise logistic regression analysis were used to assess outcomes between groups at 2 years. In total, 441 patients were included (267 SOp and 174 NH patients). After PSM, 142 patients remained (71 SOp 71 and 71 NH patients). At baseline, the SOp and NH groups had similar demographic characteristics, HRQOL, and deformity (all p > 0.05). At 2 years, ANCOVA determined that NH patients had worse deformity as measured with sagittal vertical axis (36.7 mm vs 21.3 mm, p = 0.025), mismatch between pelvic incidence and lumbar lordosis (11.9° vs 2.9°, p < 0.001), and pelvic tilt (PT) (23.1° vs 20.7°, p = 0.019). The adjusted regression analysis found that SOp patients had higher odds of reaching the minimal clinically important differences in Oswestry Disability Index score (OR [95% CI] 4.5 [1.7-11.5], p = 0.002), SRS-22 Activity (OR [95% CI] 3.2 [1.5-6.8], p = 0.002), SRS-22 Pain (OR [95% CI] 2.8 [1.4-5.9], p = 0.005), and SRS-22 Total (OR [95% CI] 11.0 [3.5-34.4], p < 0.001). Operative patients with SOp still experience greater improvements in deformity and HRQOL relative to the progressive radiographic and functional deterioration associated with the NH of ASD. The NH of nonoperative management should be accounted for when weighing the risks and benefits of operative intervention for ASD.

Identifying Subsets of Patients With Adult Spinal Deformity Who Maintained a Positive Response to Nonoperative Management.

Adult spinal deformity (ASD) represents a major cause of disability in the elderly population in the United States. Surgical intervention has been shown to reduce disability and pain in properly indicated patients. However, there is a small subset of patients in whom nonoperative treatment is also able to durably maintain or improve symptoms. To examine the factors associated with successful nonoperative management in patients with ASD. We retrospectively evaluated a cohort of 207 patients with nonoperative ASD, stratified into 3 groups: (1) success, (2) no change, and (3) failure. Success was defined as a gain in minimal clinically importance difference in both Oswestry Disability Index and Scoliosis Research Society-Pain. Logistic regression model and conditional inference decision trees established cutoffs for success according to baseline (BL) frailty and sagittal vertical axis. In our cohort, 44.9% of patients experienced successful nonoperative treatment, 22.7% exhibited no change, and 32.4% failed. Successful nonoperative patients at BL were significantly younger, had a lower body mass index, decreased Charlson Comorbidity Index, lower frailty scores, lower rates of hypertension, obesity, depression, and neurological dysfunction (all P < .05) and significantly higher rates of grade 0 deformity for all Schwab modifiers (all P < .05). Conditional inference decision tree analysis determined that patients with a BL ASD-frailty index ≤ 1.579 (odds ratio: 8.3 [4.0-17.5], P < .001) were significantly more likely to achieve nonoperative success. Success of nonoperative treatment was more frequent among younger patients and those with less severe deformity and frailty at BL, with BL frailty the most important determinant factor. The factors presented here may be useful in informing preoperative discussion and clinical decision-making regarding treatment strategies.

143. Determining the best vertebra for measuring pelvic incidence and spinopelvic parameters in transitional anatomy

<h3>BACKGROUND CONTEXT</h3> Sacralization of L5 is a condition that affects 15% of the population. Because of the increased L5 articulations to the sacrum, it is unclear how pelvic incidence and spinopelvic parameters should be measured. <h3>PURPOSE</h3> Determine whether patients with L5 sacralization should be radiographically measured with relation to the L5 or S1 vertebrae. <h3>STUDY DESIGN/SETTING</h3> Retrospective analysis. <h3>PATIENT SAMPLE</h3> Prospective multicenter adult spinal deformity database. <h3>OUTCOME MEASURES</h3> ODI, SF36 PCS, radiographic spinopelvic parameters. <h3>METHODS</h3> Linear regression modeling was used to determine normative TPA and PI-LL based on PI and age in a database of asymptomatic subjects. In an adult spinal deformity database, patients with radiographic evidence of L5 sacralization, had PI, LL and TPA measured from the superior endplate S1 and then also from L5. Patients with instrumentation below L4 at baseline were excluded. The differences in TPA and PI-LL from normative were calculated in the sacralization cohort relative to L5 and S1 and correlated to ODI. Patients were grouped based on PI-LL Schwab modifier (0, +, ++) utilizing their L5 PI-LL and S1 PI-LL. Baseline ODI and SF36 PCS were compared across and within groups and their respective SRS Schwab class. <h3>RESULTS</h3> Among 1,179 ASD patients, 276 (23.4%) had transitional anatomy, 176 with sacralized L5 (14.9%) and 100 (8.48%) with lumbarization of S1. The 176 with sacralized L5 were analyzed. PI (24.5 ± 11.0 vs 55.7 ± 12.0, p=0.001), TPA (11.2 ± 12.0 vs 20.3 ± 12.5, p=0.001) and PI-LL (0.67 ± 21.1 vs 11.4 ± 20.8, p=0.001) measured utilizing the L5 superior endplate were significantly smaller than those who were measured relative to S1. When measured from S1, 76 (43. %) of patients were SRS Schwab 0, 45 (25.6%) were Class +, and 55 (31.3%) were class ++ compared to 124 (70.5%), 22 (12.5%), and 30 (17.0%) measured from L5 respectively. There were significant differences in ODI and PCS as the Schwab grade increased regardless of L5 or S1 measurement. The L5 group had higher PCS functional scores for Schwab 0 and ++ relative to same grades in the S1 group. Offset from normative TPA (0.5 ± 11.1 vs 9.6 ± 10.8, p=0.001) and PI-LL (0.67 ± 21.1 vs 11.4 ± 20.8, p=0.001) were smaller when measuring from L5. Moreover, S1 measurements were more correlated with disability by ODI (TPA offset from normative, S1: R=0.326 vs L5: R=0.285; PI-LL Offset from normative, S1: R=0.318 vs L5: R=0.274). <h3>CONCLUSIONS</h3> Measuring the PI at L5 in sacralized anatomy results in underestimating the PILL Schwab grade in a percentage of patients and less correlation with HRQLs. Patients with sacralized L5s should have spinopelvic parameters measured relative to S1. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Comparing and Contrasting the Clinical Utility of Sagittal Spine Alignment Classification Frameworks: Roussouly Versus SRS-Schwab.

Retrospective cohort study of a prospectively collected database. To compare clinical utility of two common classification systems for adult spinal deformity (ASD) and determine whether both should be considered in surgical planning to improve patient outcomes. Surgical restoration of appropriate Roussouly classification shape or SRS-Schwab ASD classification may improve outcomes. ASD patients with pre- and 2-year postop (2Y) radiographic/health-related quality of life (HRQL) data were grouped by "theoretical" and "current" Roussouly type. Univariate analyses assessed outcomes of patients who mismatched Roussouly types at both pre- and 2Y intervals (Mismatched) and those of preoperative mismatched patients who matched at 2-years (Matched). Subanalysis assessed outcomes of patients who improved in Schwab modifiers, and patients who both improved in both Schwab modifiers and matched Roussouly type by 2Y. Included: 515 ASD patients (59 ± 14 yrs, 80% F). Preoperative breakdown of "current" Roussouly types: Type 1 (10%), 2 (54%), 3 (24%), and 4 (12%). Matched and Mismatched groups did not differ in rates of reaching MCID for any HRQL metrics by 2Y (all P > 0.10). Reoperation, PJK, and complications did not differ between Matched and Mismatched (all P > 0.10), but Roussouly Matched patients had toward lower rates of instrumentation failure (17.2% vs. 24.8%, P = 0.038). By 2Y, 28% of patients improved in PT Schwab modifier, 37% in SVA, and 46% in PI-LL. Patients who both Matched Roussouly at 2Y and improved in all Schwab modifiers met MCID for Oswestry Disability Index (ODI) and Scoliosis Research Society (SRS) activity at higher rates than patients who did not. Isolated restoration per the Roussouly system was not associated with superior outcomes. Patients who both matched Roussouly type and improved in Schwab modifiers had superior patient-reported outcomes at 2-years. Concurrent consideration of both systems may offer utility in establishing optimal realignment goals.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.

P103. The modification of appropriateness criteria for a cervical deformity corrective surgery

BACKGROUND CONTEXT The Scoliosis Research Society established appropriateness criteria for surgery for degenerative lumbar scoliosis (DLS) in order to improve and unify clinical decision making. Though utilized and validated in various cohorts, an appropriateness criteria has yet to be developed in a cervical deformity (CD) population. PURPOSE To modify the DLS Appropriateness criteria to be utilized in a CD cohort. STUDY DESIGN/SETTING Retrospective review of a single-surgeon CD database PATIENT SAMPLE A total of 100 CD patients. OUTCOME MEASURES Appropriateness criteria. METHODS CD patients>18yrs were included. Each patient was scored based upon the SRS-appropriateness criteria, comprised of clinical or radiographic characteristics and was modified for a cervical deformity cohort: (1) Severity of Symptoms [NDI], (2) Severity of Myelopathy[mJOA.], (3) Progression of Deformity, (4) Global Sagittal Malalignment [Schwab modifiers], (5) Severity of Risk Factors, (6) Degree of the T1S-CL curvature. For the category ‘progression’, radiographs were only available at one preoperative time point, and we were unable to include this in the total score. Based upon certain combinations of criteria, patients were stratified into Appropriate and Not Appropriate. RESULTS A total of 100 patients were included (61yrs, 62% F, 29.5kg/m2). Assessment of the categories of Appropriateness of CD surgery: (1) Symptoms: 6% None to Mild, 94% Moderate to Severe; (2) Myelopathy: 16% None to Mild, 45% Moderate, 39% Severe; (3) All were grouped No Progression in the present study; (4) 19% demonstrated Global Malalignment (+/++Schwab), 81% did not; (5) Risk Factors: 27% had None to Mild, 63% Moderate, 10% Severe; (6) Curvature TS-CL demonstrated 88.6% of patients Severe (>20°). Not Appropriate: None to Mild (NDI 12) and Severe Risk Factors (2) None to Mild myelopathy (15-18) and No Progression or Imbalance (3) Moderate myelopathy (mJOA 12-15) and None to Moderate Risk Factors and no Progression, or imbalance and TSCL 25°. In the present cohort, 94% were deemed Appropriate for surgery, 6% Not Appropriate. Less Appropriate patients demonstrated higher rates of postop dysphagia complications (17% vs 2%), met MCID for NDI less (0% vs 30.9%), and had more occurrences of DJK (16.7% vs 6.4%) by 2 years, p CONCLUSIONS In light of the heterogeneity and uncertainty surrounding CD, this study developed CD appropriateness criteria, using established methodology, for surgeons to consider in the preoperative decision-making that correlate well with major postop occurrences. Application of the appropriateness criteria for CD may optimize patient selection and reduce the incidence of unwarranted surgery, although future validation is necessary. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

84. Low density pedicle screw constructs are associated with lower incidence of proximal junctional failure in adult spinal deformity surgery

BACKGROUND CONTEXT Proximal junctional failure (PJF) is a common and particularly adverse complication of adult spinal deformity (ASD) surgery. There is evidence that the rigidity of posterior spinal constructs may impact risk of PJF. PURPOSE We hypothesized that lower mean screws per level and decreased rod stiffness would be associated with lower incidence of PJF. STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE Patients with ASD and 2-year minimum follow-up were included. Only patients undergoing fusion of ≥5 levels, and with LIV at the sacro-pelvis were included. Patients undergoing revision surgery were excluded. In total, 420 patients were analyzed. OUTCOME MEASURES The primary outcome variable was PJF, defined using previously published radiographic criteria (PJ angle >28°and ∆PJ angle >22°, and ≥8mm/≥3mm listhesis at upper thoracic / thoracolumbar levels, respectively). METHODS The primary independent variables were the mean number of screws per level fused analyzed with a cutoff of 1.8 (determined by ROC analysis) and rod material/diameter. Multivariable logistic regression was utilized to investigate confounding factors, including age, history of osteoporosis, BMI, gender, CCI, preoperative Schwab modifiers, preoperative TPA, postoperative change in lumbar lordosis, upper instrumented vertebra, osteotomy, approach, UIV type (ie, pedicle screw vs other), and number of levels fused. RESULTS Of the total patients, 78.8% were female. PJF occurred in 14.1% of patients. The mean screws per level was 1.7 (SD 0.2), and 57.6% of patients had 0.2) were not significantly associated with PJF. Screw density specifically adjacent to the UIV was not related to PJF (p>0.2). CONCLUSIONS Among ASD patients undergoing long-segment primary fusion to the pelvis, the risk of PJF was lower among patients with FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

P71. When not to operate in spinal deformity: identifying subsets of patients with simultaneous clinical deterioration, major complications, and reoperation

BACKGROUND CONTEXT Due to the complexity and invasiveness of deformity correction, poor outcomes are often associated. Currently, it is unknown what factors predict an outcome which operation may not be warranted (reoperation, major complications, clinical deterioration). PURPOSE To investigate what patient factors justify determining a patient ineligible for a deformity correction. STUDY DESIGN/SETTING Retrospective review of a prospective, consecutively enrolled adult spinal deformity (ASD) database. PATIENT SAMPLE Operative patients with complete 2-year HRQL and radiographic data were included. OUTCOME MEASURES HRQLs: Oswestry Disability Index (ODI), complications; reoperations. METHODS Patients >18yrs undergoing surgery for ASD (scoliosis ≥20°, SVA ≥5cm, PT ≥25°, or TK ≥60°). An unsatisfactory outcome was defined by the following categories met at 2Y: (1) clinical: deteriorating in ODI at 2Y follow-up (2) complications/reop: having a reoperation and major complication were deemed unacceptable for surgery (NoOp). Baseline demographic, clinical and radiographic information were utilized through univariate/multivariate analyses to assess predictive factors of NoOp patients in adult spinal deformity patients. Multivariate regression with backward model selection was employed to create a model for when not to operate. RESULTS A total of 633 ASD patients (59.9 years, 79% F, 27.7 kg/m2, CCI: 1.74) were included. By approach, 0.6% were anterior, 69.7% posterior and 29.5% combined approaches, with a total number of levels fused as 7.5±2.1. Baseline severe Schwab modifier incidence (++): 39.2% PI-LL, 28.8% SVA, 28.9% PT. 15.5% of patients deteriorated in ODI by 2 years, while 7.6% underwent a reoperation and had a major complication. This categorized 11 (1.7%) of patients in the total cohort as NoOp. NoOp patients had were more comorbid in terms of arthritis (73%) heart disease (36%) and kidney disease (18%), p 65mm, C2 slope >30.2°, CTPA >5.5° for an R2 value of 0.535 (p CONCLUSIONS When addressing adult spine deformities, a negative outcome of clinical deterioration, major complications, and reoperations are exceedingly rare, but do occur. This tends to occur in severely comorbid patients with major baseline psychological distress scores, severe neurologic dysfunction and concomitant cervical malalignment not addressed at surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Factors Associated With Short Length of Stay After Long Fusions for Adult Spinal Deformity: Initial Steps Toward Developing an Enhanced Recovery Pathway.

Study Design:Retrospective cohort study.Objectives:The identification of case types and institutional factors associated with reduced length of stay (LOS) is a key initial step to inform the creation of clinical care pathways that can assist hospitals to maximize the benefit of value-based payment models. The objective of this study was to identify preoperative, intraoperative, and postoperative factors associated with shorter than expected LOS after adult spinal deformity (ASD) surgery.Methods:A retrospective cohort study was performed of 82 patients with ASD who underwent ≥5 levels of fusion to the pelvis between 2013 and 2018. A LOS <6 days was determined as a basis for comparison, as 5.7 days was the “expected LOS” generated through Poisson regression modeling of the sample. Clinical, radiographic, surgical, and postoperative factors were compared between those staying ≥6 days (L group) and <6 days (S group). Logistic regression was used to identify factors associated with LOS <6 days.Results:A total of 35 patients were in group S (42.7%). Gender, age, body mass index, ASA (American Society of Anesthesiologists) class, and use of preoperative narcotics, revision surgery, day of admission, and surgical complications did not vary between the cohorts (P > .05). Mild-moderate preoperative sagittal deformity (sagittal Schwab modifiers 0 or +), lower estimated blood loss (<1200 mL), fewer levels fused (7 vs 10 levels), shorter operating room time, procedure end time before 15:00, and no intensive care unit stay, were associated with short LOS (P < .05). Only 1 major medical complication occurred in the short LOS group (P < .05).Conclusions:This study identifies the ASD “case phenotype,” intra-, and postoperative benchmarks associated with shorter LOS, providing targets for pathways designed to reduce LOS.

The spino-pelvic ratio: a novel global sagittal parameter associated with clinical outcomes in adult spinal deformity patients.

Analysis of interactions of spinal alignment metrics may uncover novel alignment parameters, similar to PI-LL. This study utilized a data-driven approach to hypothesis generation by testing all possible division interactions between spinal alignment parameters. This study was a retrospective cohort analysis. In total, 1439 patients with baseline ODI were included for hypothesis generation. In total, 666 patients had 2-year postoperative follow-up and were included for validation. All possible combinations of division interactions between baseline metrics were assessed with linear regression against baseline ODI. From 247 raw alignment metrics, 32,398 division interactions were considered in hypothesis generation. Conceptually, the TPA divided by PI is a measure of the relative alignment of the line connecting T1 to the femoral head and the line perpendicular to the sacral endplate. The mean TPA/PI was 0.41 at baseline and 0.30 at 2years postoperatively. Higher TPA/PI was associated with worse baseline ODI (p < 0.0001). The change in ODI at 2years was linearly associated with the change in TPA/PI (p = 0.0172). The optimal statistical grouping of TPA/PI was low/normal (≤ 0.2), medium (0.2-0.4), and high (> 0.4). The R-squared for ODI against categorical TPA/PI alone (0.154) was directionally higher than that for each of the individual Schwab modifiers (SVA: 0.138, PI-LL 0.111, PT 0.057). This study utilized a data-driven approach for hypothesis generation and identified the spino-pelvic ratio (TPA divided by PI) as a promising measure of sagittal spinal alignment among ASD patients. Patients with SPR > 0.2 exhibited inferior ODI scores. III.

P102. Does matching Roussouly spinal shape and improvement in SRS-Schwab modifier contribute to improved patient-reported outcomes?

BACKGROUND CONTEXT The Roussouly Classification system of sagittal spinal shape and the SRS-Schwab adult spinal deformity (ASD) classification system have become important indicators of spine deformity. No prior studies have examined the outcomes of matching both Roussouly type and improving in Schwab modifiers postoperatively. PURPOSE Evaluate outcomes of matching Roussouly Type and improving in Schwab modifier following ASD surgery. STUDY DESIGN/SETTING Retrospective review of single-center ASD database. PATIENT SAMPLE A total of 103 ASD patients. OUTCOME MEASURES Roussouly types, Schwab modifiers, Health Related Quality of Life scores(HRQLs): Minimal Clinical Important Difference for ODI, EQ5D, VAS Leg B Type 2: PI 60°); (2) “current” Roussouly type (1: SS 45°), as previously published. One year (1Y) matched Roussouly: preoperative mismatched (Between ‘actual’ and ‘theoretical’ patients that matched at 1Y. Schwab modifiers at BL were identified: non-, moderate and severe deformity (0, +, ++) for PT, SVA, and PI-LL. Schwab improvement was defined as a decrease in a modifier at one year. RESULTS A total of 103 ASD patients (61.8yrs, 63.1%F, 30kg/m2). By surgical approach, 79.6% posterior, 10.7% combined, 2.9% anterior). Average levels fused: 4.6. BL breakdown of ‘current; Roussouly type: 28% Type 1, 25.3% Type 2, 32.0% Type 3, 14.7% Type 4. BL Roussouly mismatch: 65.3%. Breakdown BL Schwab modifiers: PT (0: 8.7%, +: 41.7%, ++: 49.5%), SVA (0: 29.7%, +: 20.3%, ++: 50%), PI-LL mismatch (0: 28.2%, +: 25.2%, ++: 46.6%). At one year, 19.2% of patients matched Roussouly target type, while according to Schwab modifiers, 12.6% improved in SVA, 42.7% in PI-LL, and 45.6% in PT. Patients who both met Roussouly type and improved in a Schwab by the modifiers: 9 PT (8.7%), 8 PI-LL (7.8%), 2 SVA (1.9%). There were 2 patients (1.9%) who met their Roussouly type and improved in all 3 Schwab modifiers. One year (1Y) matched Roussouly patients improved more in HRQLs (MCID for ODI, EQ5D, VAS Leg/Back Pain), when compared to mismatched Roussouly, but was not significant(P>0.05). Match Roussouly and improvement in PT Schwab met MCID for EQ5D significantly more (33.3% vs 10.6%, p=0.050). Matched Roussouly and PI-LL Schwab had more patients meet MCID for all HRQLs, yet none were significant, p>0.05. Matched Roussouly and improvement in SVA Schwab met MCID for ODI significantly more (p=0.024). CONCLUSIONS Patients who both matched Roussouly sagittal spinal type and improved in SRS-Schwab modifiers had superior patient-reported outcomes at 1-year. Utilizing both classification systems in surgical decision making can optimize postop patient outcomes. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

210. Comparing and contrasting the clinical utility of sagittal spine alignment classification frameworks: Roussouly vs SRS-Schwab

BACKGROUND CONTEXT For surgical adult spinal deformity (ASD) patients, incorporating restoration of appropriate Roussouly Classificaion shape into surgical planning may improve outcomes. With the introduction and use of the SRS-Schwab ASD classification system, it is important to compare the utility of both classification frameworks as they relate to surgical outcomes. PURPOSE Compare outcomes of surgical ASD patients classified by both Roussouly and Schwab systems. STUDY DESIGN/SETTING Retrospective review of prospective ASD database. PATIENT SAMPLE A total of 515 ASD patients. OUTCOME MEASURES Complications; Health-related quality of life (HRQL): ODI, SF-36 PCS, SRS-22r. METHODS ASD patients with pre- and 2-year postop (2Y) radiographic/HRQL data were grouped by “theoretical” Roussouly type (Type 1: PI 60°) and “current” Roussouly type (1: SS 45°), as published. Means comparison tests assessed outcomes of those that mismatched “theoretical” and “current” types at both pre- and 2Y intervals (mismatched) to those of preoperative mismatched patients that matched at 2-years (matched). Subanalysis assessed outcomes of patients that improved in Schwab modifiers, and patients that both improved in both Schwab modifiers and matched Roussouly type by 2Y. RESULTS Included 515 ASD patients (59±14yrs, 80%F). The overall cohort showed moderate preoperative global and lumbo-pelvic deformity: SVA(64mm±73), PT(25°±11), PI-LL(16°±21). Preoperative breakdown of “current” Roussouly types: Type 1 (10%), Type 2 (54%), Type 3 (24%), Type 4 (12%). Preoperative mismatch between “current” and “theoretical” types was 60%. By 2Y, 16% of patients matched Roussouly types. Matched and Mismatched groups did not differ in rates of reaching MCID for any HRQL metrics by 2Y(all p>0.1). Reop, PJK and complications did not differ between matched and mismatched(all p>0.1), though mismatched patients showed a trend of increased instrumentation failure(17% vs 26%, p=0.080). By 2Y, 28% of patients improved in PT Schwab modifier, 37% in SVA, and 46% in PI-LL. Patients that improved in PT modifier had lower instrumentation failure rates (16% vs 24%) and higher rates of reaching 2Y MCID for ODI (58% vs 48%) and SRS Activity (75% vs 64%) than patients that did not improve. Patients that both Matched Roussouly at 2Y and improved in all Schwab modifiers met MCID for ODI and SRS Activity at higher rates than patients that did not. Roussouly Match patients that improved in Schwab PT met SRS Activity MCID at a higher rate, and had less renal, infection, and neurologic complications than patients that did not. Roussouly Match patients that improved in Schwab SVA also had superior SF-36 scores and fewer cardiopulmonary complications(all p CONCLUSIONS For surgical ASD patients, isolated restoration of sagittal spinal shape per the Roussouly system was not associated with superior clinical outcomes or complications by 2 years. In contrast, improvement in PT, per the SRS-Schwab system, was associated with substantial improvement in low-back disability by 2 years. Collectively, patients that both matched Roussouly sagittal type and improved in Schwab modifiers had superior complication and patient-reported outcomes by 2 years. These results suggest that concurrent consideration of both existing systems may offer utility in establishing optimal realignment targets. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

209. Global spinal deformity from the upper cervical perspective: what is “abnormal” in the upper cervical spine?

BACKGROUND CONTEXT Reciprocal changes in cervical alignment occur with incremental degrees of adult spinal deformity (ASD) severity, or across different sagittal morphotypes as described respectively by Schwab and Roussouly systems. The extent to which these systems relate changes in the upper cervical spine remains underexplored. PURPOSE To investigate quantitative anatomical relationships with regards to abnormal alignment in the upper cervical spine. STUDY DESIGN/SETTING Retrospective review of a prospective multicenter ASD database. PATIENT SAMPLE A total of 343 patients who met criteria for ASD. OUTCOME MEASURES Cervical alignment parameters (C2-C7 angle, C2 slope, McGregor's Slope, CBVA when available, segmental tilt), Ostrow Disability Index (ODI) METHODS Patients >18 years with ASD (scoliosis≥20°, SVA≥5cm, PT≥25°, or thoracic kyphosis ≥60°) and complete radiographic data at baseline (BL) & 1-year (1Y) were identified. Patients were grouped by BL PI and apex of LL into component types of the Roussouly classification system (Type 1: PI 65°). Patients were categorized by increasing severity of SRS-Schwab modifiers at BL (0, +, ++) and further grouped by anatomical malalignment, moving cranially (P: pelvic only; LP: lumbopelvic; TL: thoracolumbopelvic; C: subaxial & thoracolumbo-pelvic). Analysis of variance (ANOVA) tests assessed differences in BL upper cervical alignment parameters (C0-C2, C0 slope, McGregor's slope, CBVA) and ODI scores across Roussouly and Schwab modifier groups. RESULTS A total of 343 ASD patients were analyzed. Schwab modifiers at BL were as follows: SVA (0: 45.8%, +: 20.3%, ++: 33.9%), PI-LL (0: 42.3%, +: 20.7%, ++: 37.0%), PT (0: 38.6%, +: 36.2%, ++: 25.3%). By Roussouly classification, 4.2% were Type 1, 19.3% were Type 2, 43.1% were Type 3, and 33.3% were Type 4. Moving cranially up the spine, Group P (10.6%), Group LP (54.7%) and Group TL (8.5%) did not differ in C0-C2 angle, C0 slope, MGS or CBVA (all P>0.05). Group C (26.2%) had a significantly smaller C0-C2 angle, and more negative MGS, C0 slope, and CBVA than non-cervical groups. By Roussouly type, Type 1 trended slightly higher CBVA and MGS than types 2-4 without statistical significance (all P>0.05). No differences in CL, C0-C2, or C0S were found between Types 1-4 (all P>0.05). McGregor's slope (r=-0.131, P=0.015), CBVA (r=-0.473, P 34mm predicted a 1 unit(°) decrease in MGS (OR: 0.970 [0.948 – 0.993], p=0.010), while cSVA>51mm predicted a 1 unit increase in MGS (OR: 1.25[1.12-1.38], p CONCLUSIONS Our present study suggests that upper cervical alignment remains relatively stable through most broad variations of adult thoracolumbar deformity. Changes in SVA correlated most with upper cervical changes compared to other TL modifiers. Incremental trends in upper cervical alignment changes were observed as TL deformity extended cranially, with greatest variation in pts who also had subaxial malalignment. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

189. A data-driven approach to assessment of sagittal alignment: defining the spinopelvic ratio's impact on clinical outcomes in adult spinal deformity patients

BACKGROUND CONTEXT Analysis of interactions spinal alignment metrics may uncover novel and powerful alignment parameters, similar to pelvic incidence minus lumbar lordosis (PI-LL). PURPOSE This study utilized a data driven approach to hypothesis generation by testing all possible division interactions between a set of spinal alignment parameters. TPA divided by PI (TPA/PI) was identified and subsequently characterized. STUDY DESIGN/SETTING Retrospective analysis of a multicenter, prospectively-defined, consecutive cohort of ASD patients. PATIENT SAMPLE A total of 1,439 patients with baseline ODI were included for hypothesis generation; 666 patients had 2-year postoperative follow-up and were included for validation. OUTCOME MEASURES The primary outcome measure was Oswestry Disability Index (ODI). METHODS All possible combinations of division interactions between baseline metrics were assessed with linear regression against baseline ODI. Further analyses also utilized linear regression. RESULTS From 247 raw alignment metrics, 32,398 division interactions were considered in hypothesis generation. Low-cervical and high-thoracic pelvic angles divided by pelvic incidence accounted for 7 of the top 10 most significant interactions. Conceptually, the TPA/PI is a measure of the relative alignment of the line connecting T1 to the femoral head and the line perpendicular to the sacral end plate. Among the validation cohort, the mean TPA/PI was 0.41 (SD 0.24) at baseline and 0.30 at 2 years postoperatively (SD 0.18). Higher TPA/PI was linearly associated with worse ODI at baseline (β 28.7 for TPA/PI 1 vs 0, p CONCLUSIONS This study utilized a data-driven approach for hypothesis generation and identified TPA/PI, the spinopelvic ratio (SPR), as a promising measure of sagittal spinal alignment among ASD patients. This value is strongly associated with the Schwab modifier classification system. Patients with SPR ≥0.21 exhibited inferior HRQOL. The SPR classification accounted for a directionally greater proportion of variance in ODI as compared to the three Schwab modifiers. These results highlight the interaction between global sagittal alignment and adequate pelvic structural support. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

240. Spinopelvic alignment and successful outcomes following cervical deformity correction

BACKGROUND CONTEXT Surgical correction of cervical deformity (CD) can improve a patient's functional status, but is often associated with suboptimal radiographic and clinical outcomes. Although prior studies have demonstrated a high prevalence of thoracolumbar deformity among CD patients, correction of the cervical deformity often fails to address global malalignment, which may contribute to the high rates of treatment failure. The relationship between global alignment and successful CD correction remains unclear. PURPOSE To investigate whether spinopelvic alignment (SPA) is associated with outcomes following CD correction STUDY DESIGN/SETTING Retrospective review of a prospective CD database PATIENT SAMPLE A total of 97 patients with CD. OUTCOME MEASURES One-year cervical alignment, Neck Disability Index (NDI) scores, distal junctional kyphosis (DJK). METHODS A database of operative CD patients was analyzed. Inclusion criteria: cSVA>4cm or C2-slope>20°. Failure was defined as: 1-year cSVA >4cm, NDI change 20°). Failed surgeries were compared with respect to pelvic angles (TPA, T10PA, C2PA), C2-pelvic tilt (CPT), and pelvic incidence (PI). Age- and PI-specific alignment targets were calculated for TPA and T10PA. RESULTS A total of 97 CD patients were included (mean 62±11y, 62%F). At 1 year 57% had alignment failure, 39% failed to reach NDI MCID and 12% developed DJK. 66% had baseline thoracolumbar malalignment (>1 +Schwab modifier). Alignment failure was associated with worse BL cervical alignment and higher rate of DJK (16% vs 2%), all p 48.5 reached NDI MCID( CONCLUSIONS Two-thirds of CD patients had concurrent TL deformity. Patients with failed alignment had worse BL CA, but successful cervical realignment was not associated with NDI improvement. This study demonstrates that SPA is associated with radiographic and clinical outcomes following CD correction. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

160. Increasing cost efficiency in adult spinal deformity surgery: identifying predictors of lower total costs

BACKGROUND CONTEXT Adult spinal deformity (ASD) surgery often involves complex deformity correction. It's unknown which baseline (BL) patient factors predict lower total costs in ASD surgery. PURPOSE Identify predictors of lower total surgery costs for ASD patients. STUDY DESIGN/SETTING Retrospective review of a prospective multicenter adult spinal deformity database. PATIENT SAMPLE A total of 311 operative ASD patients ≥18 years old with baseline and 3Y demographic, surgical, and frailty data. OUTCOME MEASURES Schwab sagittal vertebral axis (SVA) modifier grade, Owestry Disability Index (ODI), costs of ASD surgery, predictors of lower costs. METHODS Inclusion criteria included surgical ASD (scoliosis ≥20°, SVA ≥5cm, PT ≥25°, or thoracic kyphosis ≥60°) patients >18 years with available frailty, demographic, and radiographic data at BL and 1 year postop. Descriptive analyses assessed mean age, frailty, and surgical data. Total costs for surgery were calculated using the PearlDiver database. A conditional variable importance table used nonreplacement sampling set of 20,000 conditional inference trees to identify the top factors associated with lower cost surgery for low (LSVA), moderate (MSVA), and high (HSVA) Schwab modifier grades. LSVA were SVA 9.5 cm. Linear and logistic regression assessed the relationship between significant predictors and the odds of lower cost surgery. RESULTS Of the 322 total ASD patients, 322 met inclusion criteria. Descriptive statistics were: age 58.9 ± 14.9, 76% women, BMI 27.8 ± 6.2, 62% osteotomy, 54% decompression, and 11.0 ± 4.1 average levels fused. At 3yrfollow-up, the potential cost of ASD surgery ranged from $57,606.88 to $116,312.54. There were 152 LSVA patients, 53 MSVA patients, and 111 HSVA patients. For all patients, BL ODI 1.5 (2.62 [1.402-4.875], p=0.002], no previous spine surgery (1.77 [1.22-2.58], p=0.003), frailty scores 1.5 (6.76 [1.68-27.18] p=0.007), age 2.38 (3.93 [1.54-10.18] p=0.004), frailty scores CONCLUSIONS For ASD patients, low frailty, no prior spine surgery, no depression, and higher baseline SRS activity scores were predictive of lower total surgery costs. When assessed by baseline deformity, decreased frailty and the lack of comorbidities and risk factors such as cancer, smoking, or high BMI, were associated with lower costs. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.