Operative Adult Spinal Deformity Patients Research Articles

The more the better? Integration of vertebral pelvic angles (VPA) PJK thresholds to existing alignment schemas for prevention of mechanical complications after adult spinal deformity surgery.

While existing adult spinal deformity (ASD) alignment schemas acknowledge the dynamic relationship between the pelvis and spine, consideration of vertebral pelvic angles (VPA) thresholds for PJK may provide further insight into the relationship of each individual vertebra to the pelvis, which may allow for greater individualization of operative targets. Herein, we examine VPA's utility in preventing mechanical complications and its possible unification with prevalent scoring systems. In a retrospective cohort study of a prospectively collected database, operative ASD patients ≥ 18 years with complete baseline (BL) and two-year (Y) operative, radiographic, and health-related quality of life data were included. Descriptive analyses, means comparison, and logistic regression tests were applied to explore demographic and surgical differences, as well as the impact of alignment goals on outcomes. Cohorts were grouped as patients who met VPA non-PJK thresholds, as defined by Duvvuri et al. 2023 alone versus traditional GAP/SAAS alignment matching versus combined VPA + SAAS + GAP. The Non-PJK VPA validated mean for L1PA was 10.4 ± 7.0 and T9PA 8.9 ± 7.5. 398 patients met inclusion criteria (mean age 61 ± 14 years, 78% female, BL BMI 27 ± 6, BL CCI 2 ± 2). At baseline, mean vertebral pelvic angles were as follows: T1PA: 24 ± 14; T4PA 20 ± 13, T9PA 15 ± 12, L1PA 11 ± 10, L4PA 11 ± 6. Mean vertebral pelvic angles at 6W postoperatively: T1PA 16 ± 10, T4PA 12 ± 10, T9PA 8 ± 9, L1PA 9 ± 8, L4PA 11 ± 5. 240 (60%) patients attained optimal L1PA, while 104 patients (26.1%) reached non-PJK mean for T9PA. 89 patients (22%) were optimal by both VPA standards. VPA-Optimal group demonstrated significantly lower rates of 1Y PJK (17% v 83%, p = 0.042) and PJF by 2Y (7% v. 93%, p = 0.038). When patients attained VPA goals in addition to GAP/SAAS goals at 6W, they demonstrated significantly lower rates of Y1 PJK (p = 0.026) and Y1 and Y2 PJF. Those with optimal VPA registered greater SRS-22 scores across multiple domains (p < 0.02) as well as a greater rate of normal neurological examination at 6W (p = 0.048). Vertebral pelvic angles are a reliable measure of global alignment, and respecting certain targets may help prevent development of PJK/PJF. The value of VPA can be augmented through integration with GAP/SAAS frameworks to prevent complications and improve quality of life.

Durability of substantial clinical benefit leading to optimal outcomes in adult spinal deformity corrective surgery: a minimum 5-year analysis.

The objective was to evaluate factors associated with the long-term durability of outcomes in adult spinal deformity (ASD) patients. Operative ASD patients fused from at least L1 to the sacrum with baseline (BL) to 5-year (5Y) follow-up were included. Substantial clinical benefit (SCB) in Oswestry Disability Index (ODI), numeric rating scale (NRS)-back, NRS-leg, and Scoliosis Research Society (SRS)-22r scores and physical component score were assessed on the basis of previously published values. Factors were evaluated on the basis of meeting optimal outcomes (OO) at 2 years (2+) and 5 years (5+). Furthermore, 2+ patients were isolated and evaluated on the basis of meeting OO at 5 years (2+5+) or not at 5 years (2+5-). OO were defined as follows: no reoperation, major mechanical failure, proximal junctional failure, and meeting either 1) SCB in terms of ODI score (decrease > 18.8) or 2) ODI < 15 and SRS-22r total > 4.5. In total, 330 ASD patients met the inclusion criteria, with 45.5% meeting SCB for ODI at 2 years, while 46.0% met SCB at 5 years; 79% of those who achieved 2-year (2Y) SCB went on to achieve 5Y SCB. This rate was lower for OO, with 41% achieving 2Y OO (2+), while 37% met 5Y OO (5+) and 80% of 2+ patients had durable outcomes until 5+ (32% of the total cohort). Of the patient factors, frailty was significantly different among groups at 2 years, while comorbidity burden was significantly different at 5 years and the combination thereof differed in those with durable outcomes. Those who regained their level of activity postoperatively had 4 times higher odds of maintaining OO from 2 years to 5 years (p < 0.05). Osteoporosis rates, although equivocal at BL, were higher at the last follow-up in those who met 2Y OO but failed to meet 5Y OO. The odds of achieving OO at 5 years in 2+ patients decreased by 47% for each additional comorbidity and decreased by 74% in those who had lower-extremity paresthesias at BL (both p < 0.05). Controlling for patient factors and BL disability found fewer levels fused, decreased correction of sagittal vertical axis, and increased correction of pelvic incidence-lumbar lordosis mismatch to be predictive of maintaining 2Y OO until 5 years (p < 0.05). SCB was met in 46% of ASD patients at 5 years. The durability of OO was seen in a third of patients until 5 years postoperatively. Higher rates of medical complications were seen in those who failed to achieve and maintain OO until 5 years. Frailty and comorbidity burden were significant factors associated with the achievement and durability of OO until 5 years.

A comparative cohort study of surgical approaches for adult spinal deformity at a minimum 2-year follow-up.

This study was a retrospective multi-center comparative cohort study. A retrospective institutional database of operative adult spinal deformity patients was utilized. All fusions > 5 vertebral levels and including the sacrum/pelvis were eligible for inclusion. Revisions, 3 column osteotomies, and patients with < 2-year clinical follow-up were excluded. Patients were separated into 3 groups based on surgical approach: 1) posterior spinal fusion without interbody (PSF), 2) PSF with interbody (PSF-IB), and 3) anteroposterior (AP) fusion (anterior lumbar interbody fusion or lateral lumbar interbody fusion with posterior screw fixation). Intraoperative, radiographic, and clinical outcomes, as well as complications, were compared between groups with ANOVA and χ2 tests. One-hundred and thirty-eight patients were included for study (PSF, n = 37; PSF-IB, n = 44; AP, n = 57). Intraoperatively, estimated blood loss was similar between groups (p = 0.171). However, the AP group had longer operative times (547.5min) compared to PSF (385.1) and PSF-IB (370.7) (p < 0.001). Additionally, fusion length was shorter in PSF-IB (11.4) compared to AP (13.6) and PSF (12.9) (p = 0.004). There were no differences between the groups in terms of change in alignment from preoperative to 2years postoperative. There were no differences in clinical outcomes. While postoperative complications were largely similar between groups, operative complications were higher in the AP group (31.6%) compared to the PSF (5.4%) and PSF-IB (9.1) groups (p < 0.001). While there were differences in intraoperative outcomes (operative time and fusion length), there were no differences in postoperative clinical or radiographic outcomes. AP fusion was associated with a higher rate of operative complications.

Factors Associated With the Maintenance of Cost-effectiveness at Five Years in Adult Spinal Deformity Corrective Surgery.

Retrospective cohort. To evaluate factors associated with the long-term durability of cost-effectiveness (CE) in ASD patients. A substantial increase in costs associated with the surgical treatment for adult spinal deformity (ASD) has given precedence to scrutinize the value and utility it provides. We included 327 operative ASD patients with five-year (5yr) follow-up. Published methods were used to determine costs based on CMS.gov definitions and were based on the average DRG reimbursement rates. The utility was calculated using quality-adjusted life-years (QALY) utilizing the Oswestry Disability Index (ODI) converted to Short-Form Six-Dimension (SF-6D), with a 3% discount applied for its decline in life expectancy. The CE threshold of $150,000 was used for primary analysis. Major and minor complication rates were 11% and 47%, respectively, with 26% undergoing reoperation by five years. The mean cost associated with surgery was $91,095±$47,003, with a utility gain of 0.091±0.086 at one years, QALY gained at 2 years of 0.171±0.183, and at five years of 0.42±0.43. The cost per QALY at two years was $414,885, which decreased to $142,058 at five years.With the threshold of $150,000 for CE, 19% met CE at two years and 56% at five years. In those in which revision was avoided, 87% met cumulative CE till life expectancy. Controlling analysis depicted higher baseline CCI and pelvic tilt (PT) to be the strongest predictors for not maintaining durable CE to five years [CCI OR: 1.821 (1.159-2.862), P =0.009] [PT OR: 1.079 (1.007-1.155), P =0.030]. Most patients achieved cost-effectiveness after four years postoperatively, with 56% meeting at five years postoperatively. When revision was avoided, 87% of patients met cumulative cost-effectiveness till life expectancy. Mechanical complications were predictive of failure to achieve cost-effectiveness at two years, while comorbidity burden and medical complications were at five years.

Impact of Frailty on the Development of Proximal Junctional Failure: Does Frailty Supersede Achieving Optimal Realignment?

Patients undergoing surgery for adult spinal deformity (ASD) are often elderly, frail, and at elevated risk of adverse events perioperatively, with proximal junctional failure (PJF) occurring relatively frequently. Currently, the specific role of frailty in potentiating this outcome is poorly defined. To determine if the benefits of optimal realignment in ASD, with respect to the development of PJF, can be offset by increasing frailty. Retrospective cohort. Operative ASD patients (scoliosis >20°, SVA>5cm, pelvic tilt>25°, or TK>60°) fused to the pelvis or below with available baseline and 2-year (2Y) radiographic and HRQL data were included. The Miller Frailty Index (FI) was used to stratify patients into 2 categories: Not Frail (FI <3) and Frail (>3). Proximal Junctional Failure (PJF) was defined using the Lafage criteria. "Matched" and "unmatched" refers to ideal age-adjusted alignment postoperatively. Multivariable regression determined the impact of frailty on the development of PJF. Two hundred eighty-four ASD patients met inclusion criteria [62.2yrs±9.9, 81%F, BMI: 27.5kg/m 2 ±5.3, ASD-FI: 3.4±1.5, Charlson Comorbidity Index (CCI): 1.7±1.6]. Forty-three percent of patients were characterized as Not Frail (NF) and 57% were characterized as Frail (F). PJF development was lower in the NF group compared with the F group (7% vs . 18%; P =0.002). F patients had 3.2 × higher risk of PJF development compared to NF patients (OR: 3.2, 95% CI: 1.3-7.3, P =0.009). Controlling for baseline factors, F unmatched patients had a higher degree of PJF (OR: 1.4, 95% CI:1.02-1.8, P =0.03); however, with prophylaxis, there was no increased risk. Adjusted analysis shows F patients, when matched postoperatively in PI-LL, had no significantly higher risk of PJF. An increasingly frail state is significantly associated with the development of PJF after corrective surgery for ASD. Optimal realignment may mitigate the impact of frailty on eventual PJF. Prophylaxis should be considered in frail patients who do not reach ideal alignment goals.

144. Prophylactic proximal junctional measures improves cost efficacy of adult spinal deformity surgery, with optimal cost utility seen in those with concurrent optimal realignment

144. Prophylactic proximal junctional measures improves cost efficacy of adult spinal deformity surgery, with optimal cost utility seen in those with concurrent optimal realignment

166. A Hounsfield unit value below 125 on preoperative CT at upper instrumented vertebrae is predictive of proximal junctional kyphosis after adult spinal deformity surgery

<h3>BACKGROUND CONTEXT</h3> As adult spinal deformity (ASD) prevalence increases in our ever-aging population there is a concomitant increase in poor bone quality. ASD surgery is expensive and carries a high complication profile. It is important to optimize modifiable preoperative risk factors, such as osteopenia or osteoporosis. Additional diagnostic modalities such as a DEXA can add cost, delay diagnosis, and can be an additional insurance hurdle. Some studies suggest HU's can be utilized as a proxy for frailty, but it is unclear if this is useful in risk stratification. <h3>PURPOSE</h3> Our goal was to evaluate the relationship between bone health as measured by HU's and PJK and identify a HU threshold in which PJK risk is increased. We hypothesize that HU will correlate with occurrence of PJK after ASD surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of a prospective, multicenter ASD database. <h3>PATIENT SAMPLE</h3> Of 1,330 pts eligible, 997 (74.9%) had complete 2Y follow-up. Of these, 605 meet inclusion criteria with 110 (18.18%) patients having a PJK. <h3>OUTCOME MEASURES</h3> Development of PJK within 2 years of surgery. <h3>METHODS</h3> Operative ASD patients (scoliosis >20, SVA>5cm, PT>25, or TK>60) with available baseline (BL) and 2-year (2Y) radiographic and HRQL data were included if they had a preop CT. HU were measured from axial views within the cancellous body (x3) at both L1 and UIV with the mean value calculated for each. Threshold linear regression with Bayesian information criteria was utilized to identify optimal cut-offs of risk factors for PJK. Multivariable analysis (MVA) controlled for PJK prophylaxis and surgeon. Additionally, risk factors identified were controlled against each other. <h3>RESULTS</h3> Threshold regression identified that cut-offs of <125 HU for UIV, >63 years for age, >0.31 for ASD-FI, and >47° for preoperative T4-12 thoracic kyphosis, and <10 levels fused were predictive of PJK on bivariate analysis (P<0.05 for all). On MVA, age > 63 years old (OR 4.7; P = 0.003), female gender (OR 3.33; P=0.035), HU at UIV vertebrae <125 (2.83; P=0.008), ASD-FI >0.31 (OR 4.02; P=0.011), TK > 46° (OR 3.75; P=0.003), and < 10 levels fused (OR 3.31; P=0.0310) were associated with increased odds of PJK. <h3>CONCLUSIONS</h3> Bone health as measured by HU appears to be an independent predictor of PJK after ASD surgery, specifically values <125 at the UIV. It also parallels frailty in prediction of PJK and can potentially be used as a proxy for frailty assessment. This can be easily measured and could help with risk stratification in the future. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P97. An analysis of the capabilities and utilization of artificial intelligence in adult spinal deformity surgery

<h3>BACKGROUND CONTEXT</h3> Artificial intelligence (AI) has enhanced the orthopedic surgical tool kit by introducing a broad range of analytical advances that may offer enhanced preoperative planning, intraoperative robotic or navigational guidance and prediction of postoperative complications. However, there remains a paucity of literature in regards to the utility of AI in adult spinal deformity (ASD)-corrective surgery. <h3>PURPOSE</h3> To access the impact of AI utilization on ASD-corrective surgery outcomes. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort. <h3>PATIENT SAMPLE</h3> A total of 689 ASD patients. <h3>OUTCOME MEASURES</h3> Artificial intelligence, perioperative complications, radiographic outcomes <h3>METHODS</h3> Operative ASD patients with complete baseline (BL) and 2-year (2Y) radiographic/HRQL data were stratified by AI-based utilization and robotic or navigational assistance in pre- and peri-operative course (AI+) or not (AI-). Corrections were based on AI models linked to age, proportional alignment and frailty status algorithms to predict outcomes, junctional failure and thoracic compensations. Means comparison tests and regression analysis assessed differences between patient groups. <h3>RESULTS</h3> There were 158 patients included (57 AI+, 101 AI-). The cohort was 50% female, mean age of 58.8 yrs, BMI 31.6 kg/m2, CCI 3.9 and 6.6 levels fused. At baseline, patient groups were comparable in terms of BL radiographic parameters, all p < .05. Surgically, AI+ had significantly shorter operative times and EBL than AI-, both p < .05. AI+ had more combined approaches and less osteotomies overall, both p < .05. Postoperatively, AI+ patients were noted to have significantly improved segmental alignment in terms of decreased PT (p=0.006), and improved global alignment per decreased TPA and SVA by 2Y, both p < 0.05. Compared to AI-, AI+ patients had a lower overall complication rate by 2Y (28.1% vs 47.5%), p < 0.05. in a multivariate analysis controlling for age, CCI, and invasiveness, AI+ patients were 61.6% less likely to experience a perioperative complication (OR .384 [CI .149-.989], p=0.047). <h3>CONCLUSIONS</h3> This study demonstrates that when using artificial intelligence-based technologies, patients demonstrated lower intraoperative invasiveness, increased likelihood of reaching radiographic alignment targets, and decreased complication rates specifically in the perioperative period. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

117. Predictive analysis of risk factors and clinical outcomes of delayed extubation in adult spinal deformity surgery

<h3>BACKGROUND CONTEXT</h3> Due to the high physiologic stress adult spinal deformity (ASD) surgery often places upon patients, delayed intubation may be considered to prevent decompensation between stages or after surgery. However, previous studies in thoracolumbar patients have demonstrated it may be associated with worsened peri- and postoperative outcomes due to the increased risk of infection or airway edema. Yet, literature regarding predictive analysis of delayed extubation in ASD patients remains scarce. <h3>PURPOSE</h3> To identify risk factors and predictors of delayed extubation in ASD patients in order to enhance patient selection and reduce peri- and postoperative complication. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of prospective ASD database. <h3>PATIENT SAMPLE</h3> This study included 689 ASD patients. <h3>OUTCOME MEASURES</h3> Peri- and postoperative complication rates; HRQLs. <h3>METHODS</h3> Operative ASD patients 18yrs with complete pre-(baseline [BL]) and 2-year(2Y) postop radiographic/HRQL data were stratified by decision to delay postoperative extubation (Delayed) vs those who were extubated immediately after surgery (Extubated). Differences in demographics, clinical outcomes, and complication rates were assessed via means comparison analysis. Conditional binary backstep logistic regression assessed demographic, surgical, and perioperative predictors of delayed extubation at α=.05. <h3>RESULTS</h3> A total of 582 patients were included (58.11 ± 11.97 years, 48% female, 29.13 ± 6.89 kg/m2. Of these patients, 53 (9.1%) were classified as Delayed. When comparing staged vs same-day procedures, 96.2% (n=50) of Delayed patients were classified as same-day. At BL, Delayed patients were comparable in gender, BMI, frailty, and CCI (all p>.05). When assessing individual comorbidities, Delayed patients were significantly more likely to be previously diagnosed with arthritis (58% vs 91%, p=.024). In terms of BL HRQLs, Delayed patients presented with significantly lower scores in SF-36 physical function, general health, and mental health domains (all p .05). Predictive modeling demonstrated that female gender, high CCI, elevated EBL, elevated op time, levels fused and BL anemia were robust predictors of delayed extubation (model p <.001, AUC=.838). <h3>CONCLUSIONS</h3> This study demonstrates that female gender, high CCI, elevated intraoperative blood loss, elevated operative time, levels fused and prior history of anemia is predictive of patients experiencing delayed extubation following corrective spinal deformity surgery resulting in extended SICU and hospital stay. Though no significant difference in postoperative complication rates were noted overall, optimization of patients preoperatively to reduce the risk of delaying extubation should be strongly considered. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P84. Which components of the global alignment proportionality score have the greatest impact on outcomes in adult spinal deformity corrective surgery?

P84. Which components of the global alignment proportionality score have the greatest impact on outcomes in adult spinal deformity corrective surgery?

192. The effects of global alignment and proportionality scores on postoperative outcomes following adult spinal deformity correction

<h3>BACKGROUND CONTEXT</h3> Restoring sagittal alignment in adult spinal deformity (ASD) surgery is a common goal to improve patient clinical outcomes and minimize long-term complications. Recent enthusiasm has suggested that achievement of global alignment and proportionality alignment may influence mechanical failures and as such may potentially influence ultimate outcomes. <h3>PURPOSE</h3> To investigate which components of the GAP score are most associated with patient-reported and clinical outcomes. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study of prospective, multicenter ASD database. <h3>PATIENT SAMPLE</h3> This study included 227 ASD patients. <h3>OUTCOME MEASURES</h3> Complications; health-related quality of life (HRQL): ODI, SRS-22r, SF-36. <h3>METHODS</h3> Operative ASD patients (scoliosis >20°, SVA>5cm, PT>25°, or TK>60 °,) with a fusion at L1 or higher with available baseline and 2-year radiographic and HRQL data were included. Multivariate analysis (MVA) was used to find an association between the global alignment and proportionality (GAP) score higher risk individual categories: moderately disproportioned (MD) - (GAP >2 and <7) and severely disproportioned (SD) - (GAP >7). Severe sagittal deformity was defined by a ++ in SRS-Schwab for SVA, or PI-LL. Mechanical complications excluded PJK. <h3>RESULTS</h3> A total of 227 ASD patients met the inclusion criteria (59.9yrs±14.0, 79%F, BMI: 27.7 kg/m2 ±6.0, ASD-FI: 3.3±1.6, CCI: 1.8 ±1.7). Surgically, patients had mean levels fused of 11.1±4.4, length of stay (LOS) of 7.9 days±4.4, estimated blood loss (EBL) of 1577 mL, operative time of 377 min, with 63% undergoing an osteotomy. In the full cohort, controlling for age, and CCI, MVA showed no association of GAP MD or SD patients with PJF, or mechanical complications, (p>0.05) but MD patients showed a positive correlation with development of PJK [OR: 2, 95% CI: 1-3.7, p<0.05]. In a cohort of patients with severe sagittal deformity, GAP MD (4.2[1.3-13.4]) and GAP SD (3.3[1.06-10]) criteria was predictive of PJK by 2 years, and in a cohort of patients 65 and older, GAP MD (5[1.4-18], p=.014) and GAP SD (3.6[1-12], p=.04) were also predictive of 2-year PJK development. There was no association with PJF or mechanical complications. In a cohort of patients with a history of prior fusion, or in patients less than 65 years of age, there was no correlation of GAP MD/GAP SD with PJK, PJF, or mechanical complications. The continuous 6W GAP score, as well as the GAP categories, did not show significant correlations with patient reported outcomes at 2 years. <h3>CONCLUSIONS</h3> Since the introduction of the global alignment and proportionality (GAP), literature has been inconclusive on the utility of the GAP score in clinical practice. Our study shows that the GAP score had strong predictive potential for proximal junctional kyphosis (PJK), specifically, in patients with severe baseline sagittal malalignment and/or those 65 and older, and, may have less utility in younger patients, or those with a previous fusion. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

138. Radiographic malalignment has a far greater impact on clinical outcomes than perioperative and postoperative complications in ASD surgery

138. Radiographic malalignment has a far greater impact on clinical outcomes than perioperative and postoperative complications in ASD surgery

193. Should our corrective realignments be tailored to different frailty states?

<h3>BACKGROUND CONTEXT</h3> Adult spinal deformity is associated with severe pain and disability. Recent literature has shown that surgical intervention can significantly improve patients' quality of life and lessen disease burden. As many patients requiring spine surgery are elderly and often frail, restoration of alignment targets may differ. The literature is scarce on how different frailty states affect realignment goals. <h3>PURPOSE</h3> Modify the age-adjusted alignment goals using the Frailty Index to optimize outcomes in surgical adult spinal deformity (ASD) patients. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study of a prospective multicenter database of ASD patients. <h3>PATIENT SAMPLE</h3> This study included 245 ASD patients. <h3>OUTCOME MEASURES</h3> Complications, HRQLs (SRS-22, ODI, SF-36). <h3>METHODS</h3> Operative ASD patients (scoliosis ≥20°, SVA ≥5cm, PT ≥25°, or TK ≥60°) with available baseline and 2-year radiographic and HRQL data were included. ASD frailty index was used to stratify patients into not frail (NF) and frail (F) categories. Linear regression analysis established normative radiographic thresholds, utilizing previously published age specific US-Normative ODI values (Lafage et al) and the frailty index, based on a cohort of patients with an ideal clinical outcome (no major complications, no PJK, and an SRS-satisfaction of >4). Patients were considered "matched" if 2-year postop alignment was within 1 standard deviation (+1SD overcorrected-1SD undercorrected). <h3>RESULTS</h3> A total of 245 patients included (57±15yrs, 82% female, 26±5.14kg/m2, ASD-FI: 2.9±1.6, CCI: 1.8 ±1.7). Patients had a mean level fused of 11.1±4.4, LOS of 7.7 days±4.4, EBL of 1577 mL, operative time of 377 min, with 63% undergoing an osteotomy. In terms of surgical approach, 69.9% posterior-only, and 29.3% had a combined approach. Primary analyses demonstrated correlation between baseline frailty index, PT, PI-LL, SVA, and ODI, (p<0.05). Linear regression analysis developed age and frailty adjusted alignment threshold. Thresholds for correction were found to increase with age, as previously determined by Lafage et al, as well as, increase with a higher frailty index. Frail patients, corresponding to the same age, were found on average to have a higher alignment threshold than not frail patients in SVA, PI-LL, and PT. Controlling for age, CCI, and baseline deformity, frail patients experienced less overall PJK when undercorrected in PI-LL in the Lafage Schwab age-adjusted parameters (.28[.09-.85], p=.024). Patients who achieved a match in the newly developed age and frailty-adjusted parameters in PI-LL had lower rates of PJF (5% vs 15%, p=.014 with improved HRQLs, and those matched in SVA had improved HRQLs when compared to those who were under- or overcorrected. Matched SVA patients had a shorter LOS. <h3>CONCLUSIONS</h3> Age-adjusted alignment by Lafage et al was the first study to recognize that older age warrants a lower degree of correction, and, the original SRS-Schwab criteria was modified accordingly. Alignment targets accounting for both frailty and age were developed with larger thresholds for increasing frailty. In this study, we found patients who were matched in these age and frailty adjusted thresholds had lower rates of PJF and significantly improved HRQL outcomes. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

195. Are we getting better at 3-column osteotomy in terms of achieving optimal realignment and minimizing complications in adult spinal deformity surgery?

<h3>BACKGROUND CONTEXT</h3> Three-column osteotomies (3CO), in the form of pedicle subtraction or vertebral column resection, have become common in adult spinal deformity (ASD) in cases of severe deformity or iatrogenic sagittal malalignment. Although a powerful surgical intervention, 3COs can increase the risks associated with correction. The purpose of this study is to investigate whether more appropriate usage of 3CO is occurring over time. <h3>PURPOSE</h3> To investigate the evolution of 3CO usage. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study of a prospective adult thoracolumbar deformity database. <h3>PATIENT SAMPLE</h3> This study included 762 ASD patients. <h3>OUTCOME MEASURES</h3> Complications, patient-reported outcome measures (ODI, SRS, SF-36). <h3>METHODS</h3> Operative ASD patients (scoliosis >20º, SVA >5cm, PT >25º, or TK >60º) with available baseline and 2-year radiographic and HRQL data were included. Patients were stratified into 2 groups by DOS: Group I (2008-2013) and Group II (2013-2018). Patients who underwent a 3CO in Group I and Group II were then isolated for outcomes analysis. Severe sagittal deformity was defined by a SVA >9.5cm and "match" was defined by meeting ideal age-adjusted alignment. Best clinical outcome (BCO) was defined as ODI <15 and SRS >4.5 as per Smith et al. Univariate, bivariate (BVA) and multivariate analysis (MVA) was used to assess differences in surgical, radiographic, and clinical parameters. <h3>RESULTS</h3> A total of 762 ASD patients met inclusion criteria (59.9yrs±14.0, 79%F, BMI: 27.7 kg/m2 ±6.0, ASD-FI: 3.3±1.6, CCI: 1.8 ±1.7). Controlling for baseline SVA, mismatch, revision status, age, and CCI, Group II was less likely to have a 3CO (.6[.4-.97] compared with Group I (21% vs 31%, both p<0.05). Controlling for age, CCI, and baseline deformity, patients who achieved a match in SVA or PI-LL in Group II showed a lower rate of 3CO (.510[.27-.98], (p<0.05). In an isolated cohort of patients with severe sagittal deformity, controlling for age and CCI showed a lower likelihood of Group II receiving a 3CO (0.5[.3-.94], p<0.05). The following analysis is based solely on patients who had a 3CO from each Group (79 patients in Group I and 59 patients in Group II). MVA controlling for age, deformity, CCI, and invasiveness showed Group II trended towards a higher usage of hooks, tethers, and cement prophylaxis (2[.86-4.7], p=.11), a higher usage of supplemental rods 21.8[7.8- 61], (p=.001), and lower likelihood of PJF 0.23[.07-.76], PJK by 3Y 0.23[.1-.55], rod breakage 0.30[.1-.9], and overall hardware complications 0.28[.1-.8], (all p<0.05). Group II had a lower 2Y ODI and higher SF-36 Mental/Physical/Social/Emotional, SRS Activity/Mental/Pain and SRS-Total, p<0.05. Controlling for BL ODI, Group II was more likely to reach BCO ODI 2.8[1.2-6.4] and SRS 4.6[1.3-16], p<0.05. <h3>CONCLUSIONS</h3> Over a seven-year period, the rates of 3CO usage have declined, including in cases of severe deformity, with an increase in the usage of PJK prophylaxis. A better understanding of the utility of 3CO, along with a greater implementation of preventative measures, has led to a decrease in complications, PJF, PJK, and a significant improvement in patient reported outcome measures. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P106. Normalization of pelvic tilt following corrective adult spinal deformity surgery: Analysis of prevalence, timing, and factors determining occurrence

<h3>BACKGROUND CONTEXT</h3> Increasing pelvic tilt (PT) is a primary compensatory mechanism in adult spinal deformity (ASD). By SRS-Schwab criteria, PT >20° is considered pathologic. Some ASD patients improve their PT following ASD correction, while others do not. The driving forces behind this lack of PT-response are not well defined. <h3>PURPOSE</h3> To determine the perioperative characteristics associated with PT normalization after ASD corrective surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study. <h3>PATIENT SAMPLE</h3> A total of 176 ASD patients. <h3>OUTCOME MEASURES</h3> Patient profile, radiographic parameters, and surgical factors associated with PT normalization. <h3>METHODS</h3> Operative ASD patients fused to S1/pelvis with full preoperative data as well as preoperative (BL), 6-week (6W), 1-year (1Y), and 2-year (2Y) postop PT measurements were included. PT normalization was assessed at 6W and 2-year follow-up. Univariate analyses were used to compare normalized (PTNorm) and non-normalized (NON) patients in terms of demographics, surgical and radiographic descriptors, postoperative alignment, and clinical outcomes. Multivariate regression and ROC curve assessed periop factors predicting 6W PT normalization. Conditional inference tree (CIT) determined thresholds for the continuous variables identified as independent predictors of PT normalization. <h3>RESULTS</h3> There were 176 ASD patients that met inclusion criteria (62.9±10.2years, 80%F, BMI 26.9±4.9 kg/m2, CCI: 1.88), and underwent surgery (levels fused 12.1±3.9, EBL: 1955mL, op time: 402min). At each time point, mean PT was as follows: BL: 25.7º, 6-week: 19.0º, 1-year: 21.2º, and 2-year: 22.3°. Patients classified as having normal PT by SRS-Schwab criteria (PT<20º): BL: 27.8%(n=49), 6W: 52.3%, 1-year: 47.2%, 2-year: 40.9%. Of the 127 patients with non-normal PT at BL, 50 (39.4%) normalized postoperatively by 6 weeks. Few patients normalized in PT after the 6-week mark: 7 by 1-year and another 2 by 2-year postop for a total of 37 2-year PTNorm patients. Sixteen patients with non-normal PT at BL normalized by 6W, but reverted at 2-year. Both 6 weeks and 2 years PTNorm patients had higher levels fused than NON patients (both p<0.05). 6W PTNorm patients were more likely to undergo combined approach(p=0.005). Two-year PTNorm patients were more likely to have undergone VCR(p=0.011). Normalized and non-normalized patients did not differ in BL SRS-Schwab PI-LL and SVA or in GAP proportionality (all p>0.05). Six weeks PTNorm patients were more likely to be overcorrected in PT, PI-LL, and SVA compared to NON patients at 6 weeks postop (all p<0.05). The same held true for 2-year PTNorm patients and 2-year radiographic alignment. Compared to non-normalized patients, both 6 weeks PTNorm patients and 2-year PTNorm patients had lower rates of implant failure and rod fracture (all p<0.05). 6W PTNorm patients had a lower revision rate(p=0.018). Binary logistic regression with CIT identified independent predictors of PT normalization by 6 weeks: undergoing combined approach, UIV at or above T8, levels fused >10, invasiveness score >109, baseline cSVA<41.5°, 6 weeks PI-LL diff ≥21.0°, 6 weeks sacral slope diff ≥7.9°, 6 weeks PT diff ≥7.5°; all p<0.05. Validation of a predictive model for 6 weeks normalized vs non-normalized patients including these factors yielded an AUC of 85.2%. <h3>CONCLUSIONS</h3> PT normalization following ASD correction occurred in almost 40% of patients by 6 weeks postop. Normalization is more likely to occur in patients where reconstruction addresses lumbopelvic mismatch, extends above the apex of the thoracic kyphosis, and has adequate surgical invasiveness to achieve full alignment correction. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

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.

107. Effect of osteoporosis and bisphosphonate on reoperations in adult spinal deformity

BACKGROUND CONTEXT Adult spinal deformity is a complex pathology that often requires challenging surgical intervention for treatment. In patients with osteoporosis, there may be increased risk of complications and reoperations. Our study aimed to evaluate the effect of treating osteoporosis patients with bisphosphonate preoperatively on future reoperations. PURPOSE Investigate the effect of preoperative bisphosphonate on osteoporosis patients undergoing corrective surgery for adult spinal deformity. STUDY DESIGN/SETTING Retrospective review of the PearlDiver database between the years 2008-2015. PATIENT SAMPLE This study included 2,842 adult spinal deformity patients. OUTCOME MEASURES Ninety-day complications, reoperations. METHODS Adult spinal deformity patients undergoing a fusion were isolated using ICD-9 CM and CPT codes in the PearlDiver database between the years 2008-2015. Patients were stratified based on diagnosis of osteoporosis and whether there was a filled prescription for bisphosphonate 6 months prior to surgery. ASD patients with osteoporosis and bisphosphonate use who underwent corrective intervention were compared with age- and sex-matched cohorts of osteoporotic and nonosteoporotic controls with no bisphosphonate prescriptions. Means comparison tests compared differences in demographics, comorbidities, 90-day complications, and 2Y reoperation rates. Logistic regression analysis assessed the odds of complication and reoperations controlling for age, sex, and comorbidities (odds ratio [95% confidence interval]). Statistical significance was set p<0.05. RESULTS A total of 2,842 operative adult spinal deformity patients were isolated. Four hundred and six patients had osteoporosis and bisphosphonate use, 807 osteoporosis with no bisphosphonate use, and 1,629 non-osteoporosis patients. At baseline, osteoporosis patients had higher rates of obesity, diabetes, hyperlipidemia, and peripheral vascular disease compared to osteoporotic bisphosphonate cohort. There were no differences in 90-day complication rates or 2Y reoperations rates between osteoporosis bisphosphonate users and osteoporosis controls (p>0.05). Compared to nonosteoporotic patients, osteoporosis patients with bisphosphonate use trended toward lower rates of revisions at 1Y (5% vs 7%) and 2Y (7% vs 8%, both p>0.05). CONCLUSIONS In a matched cohort, osteoporosis patients treated preoperatively with bisphosphonates trended towards lower rates of revisions two years postoperatively compared to nonosteoporotic controls. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. Adult spinal deformity is a complex pathology that often requires challenging surgical intervention for treatment. In patients with osteoporosis, there may be increased risk of complications and reoperations. Our study aimed to evaluate the effect of treating osteoporosis patients with bisphosphonate preoperatively on future reoperations. Investigate the effect of preoperative bisphosphonate on osteoporosis patients undergoing corrective surgery for adult spinal deformity. Retrospective review of the PearlDiver database between the years 2008-2015. This study included 2,842 adult spinal deformity patients. Ninety-day complications, reoperations. Adult spinal deformity patients undergoing a fusion were isolated using ICD-9 CM and CPT codes in the PearlDiver database between the years 2008-2015. Patients were stratified based on diagnosis of osteoporosis and whether there was a filled prescription for bisphosphonate 6 months prior to surgery. ASD patients with osteoporosis and bisphosphonate use who underwent corrective intervention were compared with age- and sex-matched cohorts of osteoporotic and nonosteoporotic controls with no bisphosphonate prescriptions. Means comparison tests compared differences in demographics, comorbidities, 90-day complications, and 2Y reoperation rates. Logistic regression analysis assessed the odds of complication and reoperations controlling for age, sex, and comorbidities (odds ratio [95% confidence interval]). Statistical significance was set p<0.05. A total of 2,842 operative adult spinal deformity patients were isolated. Four hundred and six patients had osteoporosis and bisphosphonate use, 807 osteoporosis with no bisphosphonate use, and 1,629 non-osteoporosis patients. At baseline, osteoporosis patients had higher rates of obesity, diabetes, hyperlipidemia, and peripheral vascular disease compared to osteoporotic bisphosphonate cohort. There were no differences in 90-day complication rates or 2Y reoperations rates between osteoporosis bisphosphonate users and osteoporosis controls (p>0.05). Compared to nonosteoporotic patients, osteoporosis patients with bisphosphonate use trended toward lower rates of revisions at 1Y (5% vs 7%) and 2Y (7% vs 8%, both p>0.05). In a matched cohort, osteoporosis patients treated preoperatively with bisphosphonates trended towards lower rates of revisions two years postoperatively compared to nonosteoporotic controls.

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.

212. Operative treatment of adult spinal deformity patients with severe scoliosis: retrospective review of a prospectively collected multicenter series with minimum 2-year follow up

BACKGROUND CONTEXT Prior studies have demonstrated potential benefits of adult spinal deformity (ASD) surgery, but less outcomes data exist for operative ASD patients with severe scoliotic curves (thoracic [TH] curve ≥75°, thoracolumbar [TL] curve ≥50°, or lumbar [LL] curve ≥50°). Also, the surgical complication profile is less clear for this subset of patients with severe scoliotic deformity and warrants focused investigation. PURPOSE The objective of the current study was to assess treatment outcomes and complication rates associated with ASD surgery in patients with severe scoliosis. STUDY DESIGN/SETTING Retrospective review of a prospectively collected multicenter consecutive case registry PATIENT SAMPLE Enrollment required: age ≥18 yrs, scoliosis ≥20°, sagittal vertical axis (SVA) ≥5cm, pelvic tilt ≥25°, and/or thoracic kyphosis ≥60°. OUTCOME MEASURES Standard coronal and sagittal spinopelvic deformity measurements and health-related quality of life (HRQL) outcomes, which included Oswestry Disability Index (ODI), Short Form-36 (SF-36) scores, and Scoliosis Research Society-22 (SRS-22) scores. METHODS Using a prospective multicenter database, we identified surgically treated ASD patients with severe scoliosis (TH Cobb ≥75° or TL/LL Cobb ≥50°) and minimum 2-yr follow-up. Demographic data, surgical characteristics, radiographic alignment measurements, HRQL outcomes and associated complications were analyzed. RESULTS Of 178 patients, 146 (82%, mean age 54 yrs, 92% women, 88 TL, 50 LL, 8 TH) had minimum 2-yr follow-up (mean=3.1 yrs). Almost 30% had prior spine fusion, 6% were active or past smokers, 16% had osteoporosis and 77% had at least 1 comorbidity. Surgical details included: posterior-only (58%) or anterior-posterior approach (42%), SPO (65%), 3CO (14%), TLIF (23%), ALIF (37%), sacropelvic fixation (76%), upper thoracic UIV (64%) and mean posterior fusion length of 13.2 levels. Postoperative coronal alignment improved significantly for all patients (global coronal alignment 3.8 to 2.8 cm, p CONCLUSIONS Surgery for severe adult scoliosis is associated with significant improvement in radiographic alignment and HRQL measures. Although associated complication rates are high, these appear to be comparable to reports of less severe scoliosis. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

28. Does baseline thoracolumbar shape influence patterns of cervical decompensation following surgical adult spinal deformity correction?

BACKGROUND CONTEXT Adult spinal deformity (ASD) surgery is complex and may lead to new-onset cervical malalignment and/or proximal junctional kyphosis (PJK). Roussouly et al describes variations in baseline thoracolumbar (TL) shape (Types 1-4), which have been shown to differentially influence surgical ASD outcomes. The effect of morphological shape on patterns of postoperative CD development remains underexplored. PURPOSE Stratify patients by Roussouly type and assess patterns of conversion from baseline (BL) cervical alignment to postoperative cervical deformity (CD) in patients undergoing thoracolumbar ASD surgery. STUDY DESIGN/SETTING Retrospective review of a prospective multicenter database of ASD patients. PATIENT SAMPLE A total of 266 surgical ASD patients. OUTCOME MEASURES Rate and timing of conversion to CD, rate of PJK, radiographic alignment parameters. METHODS Operative ASD patients with complete radiographic data at baseline, 6W, 1Y, 2Y, & 3Y intervals were included. Patients were grouped by baseline PI and apex of LL into component types of the Roussouly classification system utilizing pelvic incidence as published by Pizones et al. Patients with no BL CD were postoperatively stratified by Ames CD criteria (TS-CL>20 °, cSVA>40mm), where CD was defined as fulfilling >1 criteria. Follow-up intervals were established post-ASD surgery, with 6W postop defined as “Early,” 6W-1Y “Intermediate,” 1-2Y “Late,” and 2-3Y “Long.” Univariate and Cox regression analyses identified CD conversion rate and PJK rate ( RESULTS A total of 266 surgical ASD patients (59.7yrs, 77.4% F) with complete radiographic data were included. By Roussouly classification, 9% were Type 1, 15.8% Type 2, 46.6% Type 3, and 28.6% Type 4. 28.6% of ASD patients converted to postop CD (Early: 14.3%, Intermediate: 5.3%, Late: 4.1%, Long: 4.9%). There were no significant differences in CD conversion rate across Roussouly types (1: 33.3%; 2: 28.6%; 3: 26.6%; 4: 30.3%, P=0.895). Types 2 (41.7%), 3 (60.6%), and 4 (43.5%) had their peak rates of conversion in the Early ( 1 year) than other types (50% vs 28.1%, P=0.135), while Type 1 patients trended higher rates of earlier CD conversion ( 0.05). There were no significant change in ODI, PCS, or SRS total among Roussouly Types in patients that converted to CD (p>0.05). Random forest analysis determined the top surgical (levels fused), radiographic (TS-CL), and demographic (frailty) factors associated with CD conversion. CONCLUSIONS Baseline thoracolumbar shape as described by the Roussouly classification has a differential effect on timing to CD conversion, though overall rates of CD conversion after TL-ASD correction were similar across Types 1-4. Type 1 patients with a lower apex of lumbar lordosis trended earlier conversion, while Type 2 patients with a higher apex of LL trended conversion beyond 1-year postop. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.