Adult Spinal Deformity Correction Research Articles

Patient satisfaction after multiple revision surgeries for adult spinal deformity.

Revision surgery is often necessary for adult spinal deformity (ASD) patients. Satisfaction with management is an important component of health-related quality of life. The authors hypothesized that patients who underwent multiple revision surgeries following ASD correction would exhibit lower self-reported satisfaction scores. This was a retrospective cohort study of 668 patients who underwent ASD surgery and were eligible for a minimum 2-year follow-up. Visits were stratified by occurrence prior to the index surgery (period 0), after the index surgery only (period 1), after the first revision only (period 2), and after the second revision only (period 3). Patients were further stratified by prior spine surgery before their index surgery. Scoliosis Research Society-22 (SRS-22r) health-related quality-of-life satisfaction subscore and total satisfaction scores were evaluated at all periods using multiple linear regression and adjustment for age, sex, and Charlson Comorbidity Index. In total, 46.6% of the study patients had undergone prior spine surgery before their index surgery. The overall revision rate was 21.3%. Among patients with no spine surgery prior to the index surgery, SRS-22r satisfaction scores increased from period 0 to 1 (from 2.8 to 4.3, p < 0.0001), decreased after one revision from period 1 to 2 (4.3 to 3.9, p = 0.0004), and decreased further after a second revision from period 2 to 3 (3.9 to 3.3, p = 0.0437). Among patients with spine surgery prior to the index procedure, SRS-22r satisfaction increased from period 0 to 1 (2.8 to 4.2, p < 0.0001) and decreased from period 1 to 2 (4.2 to 3.8, p = 0.0011). No differences in follow-up time from last surgery were observed (all p > 0.3). Among patients with multiple revisions, 40% experienced rod fracture, 40% proximal junctional kyphosis, and 33% pseudarthrosis. Among patients undergoing ASD surgery, revision surgery is associated with decreased satisfaction, and multiple revisions are associated with additive detriment to satisfaction among patients initially undergoing primary surgery. These findings have direct implications for preoperative patient counseling and establishment of postoperative expectations.

Three Cases of Additional Correction with Kickstand Rod Technique for Persisted Coronal Malalignment during Thoracic Spine to Iliac Fusion in Adult Spinal Deformity Correction Surgery

Three Cases of Additional Correction with Kickstand Rod Technique for Persisted Coronal Malalignment during Thoracic Spine to Iliac Fusion in Adult Spinal Deformity Correction Surgery

Postoperative Gravity Line-Hip Axis Offset as a Substantial Risk Factor for Mechanical Failure After Adult Spinal Deformity Correction Surgery.

Mechanical failure (MF) is a serious burden for patients with adult spinal deformity (ASD) who have undergone deformity correction surgery. Surgeons have sought to understand the mechanism and prevent this problematic complication, but this goal remains to be achieved. The gravity line (GL) of the whole body is a noteworthy parameter that represents global sagittal balance, for which normative values for the axial skeleton have been studied. To assess postoperative GL-hip axis (GL-HA) offset as a critical risk factor for MF after ASD correction surgery. Consecutive patients who underwent initial surgery for ASD at a single academic center were retrospectively included. Demographics, operative details, preoperative and postoperative spinopelvic parameters, global sagittal balance parameters, and Scoliosis Research Society-22 score were evaluated. These variables were analyzed for differences and correlations with MF. Thirty-five patients without MF and 30 patients with MF were identified in the study. Two groups showed no significant differences in baseline demographics, operative characteristics, preoperative global sagittal balance parameters, or preoperative and postoperative Scoliosis Research Society-22 scores. Significant differences and correlations with MF were observed for postoperative GL-HA offset using a cutoff value of 49.3 mm from logistic regression analysis, with an odds ratio of 11.0 (95% confidence interval: 3.45-35.01, P < .0001). Postoperative GL-HA offset is a substantial risk factor for MF after ASD surgery. Surgical correction of ASD with a GL-HA offset greater than 5 cm is significantly related to MF. The GL should be located near the HA after ASD surgery.

Vertebral Bone Quality Score Independently Predicts Proximal Junctional Kyphosis and/or Failure After Adult Spinal Deformity Surgery.

Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) can be catastrophic complications associated with adult spinal deformity (ASD) surgery. These complications are markedly influenced by osteoporosis, leading to additional vertebral fracture and pedicle screw loosening. The MRI-based vertebral bone quality score (VBQ) is a newly developed tool that can be used to assess bone quality. To investigate the utility of the VBQ score in predicting PJK and/or PJF (PJF/PJK) after ASD correction. We conducted a retrospective chart review to identify patients age ≥50 years who had received ASD surgery of 5 or more thoracolumbar levels. Demographic, spinopelvic parameters, and procedure-related variables were collected. Each patient's VBQ score was calculated using preoperative T1-weighted MRI. Univariate analysis and multivariate logistic regression were performed to determine potential risk factors of PJK/PJF. Receiver operating characteristic analysis and area-under-the-curve values were generated for prediction of PJK/PJF. A total of 116 patients were included (mean age, 64.1 ± 6.8 years). Among them, 34 patients (29.3%) developed PJK/PJF. Mean VBQ scores were 3.13 ± 0.46 for patients with PJK/PJF and 2.46 ± 0.49 for patients without, which was significantly different between the 2 groups ( P < .001). On multivariate analysis, VBQ score was the only significant predictor of PJK/PJF (odds ratio = 1.745, 95% CI = 1.558-1.953, P < .001), with a predictive accuracy of 94.3%. In patients undergoing ASD correction, higher VBQ was independently associated with PJK/PJF occurrence. Measurement of VBQ score on preoperative MRI may be a useful adjunct to ASD surgery planning.

Changes in health-related quality of life measures associated with degree of proximal junctional kyphosis.

To explore the changes in health-related quality of life parameters observed in patients experiencing varying degrees of proximal junctional kyphosis following corrective adult spinal deformity fusions. Inclusion: adult spinal deformity patients > 18 y/o, undergoing spinal fusion. PJK: ≥ 10° measure of the sagittal Cobb angle between the inferior endplate of the UIV and the superior endplate of the UIV + 2. Severe PJK: > 28° PJK. Mild PJK: ≥ 10oand ≤ 28°. ANOVA, followed by ANCOVA, compared the change in HRQoLs between time points (BL, 1Y, 2Y) among PJK groups. Correlation-related change in PJK and change in HRQoL for mild and severe groups. 969 patients (age: 64.5 y/o,75% F, posterior levels fused:12.3) were studied. 59% no PJK, 32% mild PJK, 9% severe PJK. No differences in HRQoLs were seen between no PJK and PJK groups at baseline, one year, and 2 years. Adjusted analysis revealed Severe PJK patients improved less in SRS-22 Satisfaction (NoPJK: 1.6, MildPJK: 1.6, SeverePJK: 1.0; p = 0.022) scores at 2years. Linear regression analysis only found clinical improvement in SRS-22 Satisfaction to correlate with the change of the PJK angle by 2years (R = 0.176, P = 0.008). No other HRQoL metric correlated with either the incidence of PJK or the change in the PJK angle by one or 2years. These results maintain that patients presenting with and without proximal junctional kyphosis report similar health-related qualities of life following corrective adult spinal deformity surgery, and SRS-22 Satisfaction may be a clinical correlate to the degree of PJK. Rather than proving proximal junctional kyphosis to have a minimal clinical impact overall on HRQoL metrics, these data suggest that future analysis of this phenomenon requires different assessments. Level of evidence: III.

Surgical sequence in anterior column realignment with posterior osteotomy is important for degree of adult spinal deformity correction: advantages and indications for posterior to anterior sequence

BackgroundWe hypothesized that posterior osteotomy prior to ACR (Anterior column realignment) through P-A-P surgical sequence would permit a greater correction for deformity corrective surgery than the traditional A-P sequence without posterior osteotomy. This study aimed to determine the impact of the P-A-P sequence on the restoration of lumbar lordosis (LL) compared to the A-P sequence in deformity corrective surgery for adult spinal deformity (ASD) patients and to identify the characteristics of patients who require this sequence. MethodsBetween 2017 and 2019, 260 ASD patients who had undergone combined corrective surgery were reviewed retrospectively. This study included 178 patients who underwent posterior osteotomy before the ACR (P-A group) and 82 patients who underwent the A-P sequence (A-P group). Sagittal spinopelvic parameters were determined from pre- and postoperative whole-spine radiographs and compared between the groups. To find better indications for the P-A-P sequence, we conducted additional analysis on postoperative outcomes of patients in the A-P group. ResultsThe P-A group showed a significantly higher change in LL (53.7° vs. 44.3°, p < 0.001), C7 sagittal vertical axis (C7 SVA: 197.4 mm vs. 146.1 mm, p = 0.021), segmental lordosis (SL) L2/3 (16.2° vs. 14.4°, p = 0.043), SL L3/4 (16.2° vs. 13.8°, p = 0.004), and SL L4/5 (15.1° vs. 11.3°, p = 0.001) compared to the A-P group. At the final follow-up, pelvic incidence (PI) minus LL mismatch (PI − LL mismatch) was significantly higher in the A-P group (13.4° vs. 2.9°, p < 0.001). Stepwise logistic regression analysis showed that age ≥ 75 years (odds ratio [OR] = 2.151; 95% confidence interval [CI], 1.414–3.272; p < 0.001), severe osteoporosis (OR = 2.824; 95% CI, 1.481–5.381; p = 0.002), rigid lumbar curve with dynamic changes in LL < 10° (OR = 5.150; 95% CI, 2.296–11.548; p < 0.001), and severe facet joint osteoarthritis (OR = 4.513; 95% CI, 1.958–10.402; p < 0.001) were independent risk factors for PI − LL mismatch ≥ 10° after A-P surgery.ConclusionP-A-P sequence for deformity corrective surgery in ASD offers greater LL correction than the A-P sequence. Indications for the procedure include patients aged ≥ 75 years, severe osteoporosis, rigid lumbar curve with dynamic change in LL < 10°, or more than four facet joints of Pathria grade 3 in the lumbar region.

The Relationship Among Surgeon Experience, Complications, and Radiographic Outcomes in Spine Deformity Surgery: The Experience of a Junior Surgeon

To examine complication rates and radiographic outcomes in patients undergoing surgery for adult spinal deformity (ASD) by a junior surgeon. A study was conducted of a retrospective cohort of patients who underwent an open posterior interbody fusion of the thoracic and/or lumbar regions by a single surgeon for ASD between 2018 and 2022. Patient characteristics, complications, and common radiographic parameters of spinopelvic alignment were collated. A total of 112 patients with an average of 4.2 comorbidities underwent surgical correction of ASD. Thirty-seven patients (33.0%) experienced 52 major complications and 50 patients (44.6%) experienced 66 minor complications. Twenty-three patients (20.5%) required a revision operation. Both sagittal vertical axis (P < 10-14) and pelvic incidence-lumbar lordosis mismatch (P < 10-7) significantly improved postoperatively. Number of levels (P < 0.05), operative time >650 minutes (P < 0.01), estimated blood loss >1500 mL (P < 0.01), length of intensive care unit stay >1 day (P < 0.05), and hospitalization length >5 days (P < 0.05) all significantly increased the risk of a major complication. No patient factors significantly increased the risk of minor complications or revision surgery. Observed complication and revision rates in this cohort were consistent with rates reported in the literature. No preoperative patient risk factors significantly increased risk of complications or need for revision, suggesting that no patient population is at increased risk undergoing surgery by a junior surgeon. The relatively high rate of complications observed in this cohort may be a result of high baseline morbidity.

An Economic Analysis of Early and Late Complications After Adult Spinal Deformity Correction.

Retrospective cohort. Adult spinal deformity (ASD) corrective surgery is often a highly invasive procedure portending patients to both immediate and long-term complications. Therefore, we sought to compare the economic impact of certain complications before and after 2years. ASD patients with minimum 3-year data included. Complication groups were defined as follows: any complication, major, medical, mechanical, radiographic, and reoperation. Complications stratified by occurrence before or after 2years postoperatively. Published methods converted ODI to SF-6D to QALYs. Cost was calculated using CMS.gov definitions. Marginalized means for utility gained and cost-per-QALY were calculated via ANCOVA controlling for significant confounders. 244 patients included. Before 2Y, complication rates: 76% ≥1 complication, 18% major, 26% required reoperation. After 2Y, complication rates: 32% ≥1 complication, 4% major, 2.5% required reoperation. Major complications after 2 years had worse cost-utility (.320 vs .441, P = .1). Patients suffering mechanical complications accrued the highest overall cost ($130,482.22), followed by infection and PJF for complications before 2years. Patients suffering a mechanical complication after 2years had lower cost-utility ($109,197.71 vs $130,482.22, P = .041). Patients developing PJF after 2years accrued a better cost-utility ($77,227.84 vs $96,873.57; P = .038), compared to PJF before 2years. Mechanical complications had the single greatest impact on cost-utility after adult spinal deformity surgery, but less so after 2years. Understanding the cost-utility of specific interventions at certain timepoints may mitigate economic burden and prophylactic efforts should strategically be made against early mechanical complications.

Level selection for optimal adult spinal deformity correction: A narrative review

Adult spine deformity (ASD) is the loss of the normal sagittal and coronal alignment necessary to maintain the head over the hips. ASD increases energy expenditure to maintain normal balance and horizontal gaze, and can lead to chronic pain, fatigue, and significant functional disability. Selection of upper and lower instrumented levels for ASD constructs is critical to achieving and maintaining an optimal post-operative alignment. While classifications and recommendations have improved level selection strategies, decision-making still remains largely dependent on the individual surgeon. This work summarizes available literature on level selection for ASD constructs.

162. Predictors of a sustained clinical benefit following adult spinal deformity correction with a minimum 3-year follow-up

<h3>BACKGROUND CONTEXT</h3> Despite multiple reports showing favorable long-term functional outcomes following adult spinal deformity (ASD) correction, it is still unclear which patient factors may impact the sustainability of these outcomes. <h3>PURPOSE</h3> To assess the sustainability of functional gains following ASD correction and determine predictors for postoperative loss of patient functionality. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort. <h3>PATIENT SAMPLE</h3> A total of 689 ASD patients. <h3>OUTCOME MEASURES</h3> Sustained clinical benefit, Oswestry Disability Index (ODI), reoperation, mechanical failure, proximal junctional failure (PJF) <h3>METHODS</h3> ASD patients with baseline (BL) and three-year (3Y) follow-up data were considered for analysis. Only patients who met the definition of sustained clinical benefit (SCB) at one-year (1Y) were included: 1)Passias et al's threshold for ODI (ODI<31.3), 2) did not develop PJF, and 3) did not have a reoperation for a mechanical failure. Patient groups were created by those who met SCB at 3Y, and those who did not. SCB outcomes were also reported at five-years (5Y) postoperatively. Means comparison tests assessed differences in patient groups. Factors predicting SCB were identified using adjusted regression and conditional inference tree (CIT) analysis. <h3>RESULTS</h3> A total of 157 patients met inclusion criteria and had SCB at 1Y. Patient breakdown for SCB was 75.0% at 3Y. Gender (78% vs 81%), BMI (25.5 vs 26.4), levels fused (10.6 vs 10.5), operative time (345 vs 362 min), and surgical invasiveness were similar between groups, all P>.05. Following surgery, patient groups were similarly aligned to Lafage et al's age-adjusted PT, PI-LL, and SVA, all P>.05. Regression and CIT analysis adjusting for BL deformity determined that patients who met SCB at 3Y were 95.4% less likely to have an ASD-mFI score > 11 (.046[.005-.420], p=0.006), 73.1% less likely to be older than 55 years at DOS (.269[.091-.798], p=.018), 69.4% less likely to have a CCI score > 0(.306[.116-.811], p=.017), and 86.9% less likely to have a BL EQ5D score < .723 (.131[.029-.585], p=.008). Adjusted for patients without follow-up, sustained clinical benefit at 5Y was 57.9%. Predictors of SCB from 3Y to 5Y included age, CCI and EQ5D, all P < .05. <h3>CONCLUSIONS</h3> Sustained clinical benefit was maintainable for 75.0% of the operative ASD cohort at 3Y. Similarly, a 57.9% maintenance rate of sustained clinical benefit at 5Y reflects the longevity of ASD correction. Independent predictors of sustained clinical benefit included age, frailty, comorbidities and the patient health state. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P98. An economic evaluation of early term and late term complications following adult spinal deformity correction

P98. An economic evaluation of early term and late term complications following adult spinal deformity correction

P85. Detailed risk factor stratification in adult spinal deformity corrective surgery: a 3-year cost utility analysis

BACKGROUND CONTEXT A previous study by Pellisé et al identified strong preoperative and surgical predictors of major complications. It is unknown which of these risk factors has the most significant impact on cost-effectiveness. PURPOSE To assess the impact of previously established risk factors on the cost effectiveness of ASD surgery. STUDY DESIGN/SETTING Retrospective. PATIENT SAMPLE A total of 689 ASD patients. OUTCOME MEASURES Quality adjusted life years (QALYs), utility gained, ODI, total cost. METHODS ASD patients with baseline (BL) and 2-year postoperative (2Y) data were included. Frailty score, sagittal deformity measures (SVA, PI-LL, T1 Sagittal Tilt), blood loss and surgical time were divided into tertiles, with the highest tertile being classified as high risk. Since some patients have multiple risk factors, they may be included in multiple groups. Descriptive analysis identified demographics, radiographic parameters and surgical factors. Published methods for cost was calculated using the PearlDiver database and CMS.gov definitions. Cost per QALY at 2Y was calculated for each risk factor. RESULTS There were 422 patients included. Of the 381 patients with a risk factor, 77% were fused to the pelvis, 44% were highly frail, 56% had a high deformity, 34% had high EBL and 34% had high operative time. When analyzing BL scores, highly frail patients had the highest mean ODI and EQ-5D. After undergoing surgery, patients with a high EBL had the highest rate of SICU admissions, rate of any complications and rate of major complications. This translated to patients with high EBL having the lowest utility gained at 2Y. Interestingly, patients with high frailty had the highest rates of implant complications and pseudarthrosis resulting in the second highest major complication rates and total estimated cost. Despite this high estimated cost, however, patients with high frailty also achieved the highest utility gained at 2Y resulting in the best cost-utility at two years. CONCLUSIONS Despite having higher rates of implant failures, pseudarthrosis, and major complications, highly frail patients managed to generate the highest utility gained and best cost-effectiveness, while higher blood loss had higher rates of complications as well, but demonstrated the lowest utility gained and cost-utility. Therefore, spine surgeons should limit intraoperative risk factors, such as blood loss and operative time, which would minimize postoperative complications and improve overall cost-effectiveness during correction of adult spinal deformity. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. A previous study by Pellisé et al identified strong preoperative and surgical predictors of major complications. It is unknown which of these risk factors has the most significant impact on cost-effectiveness. To assess the impact of previously established risk factors on the cost effectiveness of ASD surgery. Retrospective. A total of 689 ASD patients. Quality adjusted life years (QALYs), utility gained, ODI, total cost. ASD patients with baseline (BL) and 2-year postoperative (2Y) data were included. Frailty score, sagittal deformity measures (SVA, PI-LL, T1 Sagittal Tilt), blood loss and surgical time were divided into tertiles, with the highest tertile being classified as high risk. Since some patients have multiple risk factors, they may be included in multiple groups. Descriptive analysis identified demographics, radiographic parameters and surgical factors. Published methods for cost was calculated using the PearlDiver database and CMS.gov definitions. Cost per QALY at 2Y was calculated for each risk factor. There were 422 patients included. Of the 381 patients with a risk factor, 77% were fused to the pelvis, 44% were highly frail, 56% had a high deformity, 34% had high EBL and 34% had high operative time. When analyzing BL scores, highly frail patients had the highest mean ODI and EQ-5D. After undergoing surgery, patients with a high EBL had the highest rate of SICU admissions, rate of any complications and rate of major complications. This translated to patients with high EBL having the lowest utility gained at 2Y. Interestingly, patients with high frailty had the highest rates of implant complications and pseudarthrosis resulting in the second highest major complication rates and total estimated cost. Despite this high estimated cost, however, patients with high frailty also achieved the highest utility gained at 2Y resulting in the best cost-utility at two years. Despite having higher rates of implant failures, pseudarthrosis, and major complications, highly frail patients managed to generate the highest utility gained and best cost-effectiveness, while higher blood loss had higher rates of complications as well, but demonstrated the lowest utility gained and cost-utility. Therefore, spine surgeons should limit intraoperative risk factors, such as blood loss and operative time, which would minimize postoperative complications and improve overall cost-effectiveness during correction of adult spinal deformity.

182. Impact of realignment schemas on rates of proximal junctional changes in adult spinal deformity surgery

<h3>BACKGROUND CONTEXT</h3> Operative intervention for adult spinal deformity (ASD) is associated with high rates of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). Multiple attempts have been made to guide realignment for ASD corrective surgery, yet the predominance have been based on functional gains, which may or may not directly impact such junctional malcompensation. <h3>PURPOSE</h3> To assess impact of baseline patient deformity and surgical realignment on rates of PJK and PJF. <h3>STUDY DESIGN/SETTING</h3> Retrospective study of patients prospectively enrolled in a single center ASD database. <h3>PATIENT SAMPLE</h3> A total of 298 ASD patients. <h3>OUTCOME MEASURES</h3> Proximal junctional kyphosis (PJK); proximal junctional Failure (PJF). <h3>METHODS</h3> ASD patients with 2-year (2Y) data, UIV above L1 and LIV at S1 or pelvis were included. Those with evidence of PJK at 6-weeks postoperatively were excluded. Six-week radiographs were used to assess alignment by 5 published alignment systems: SRS-Schwab, GAP Score, age-adjusted (AA), Roussouly (Rous), and the newly published sagittal age-adjusted score (SAAS). To compare the impact of each alignment system on rates of PJK and PJF by level of baseline deformity, all radiographic measurements used to calculate SRS-Schwab, AA, Rous, GAP and SAAS were re-scaled from 0 to 100 using the min-max of the cohort for each respective angle. Normalized values were then summed to compute a composite "deformity score" for each patient. Patients were ranked by deformity score into 3 groups: mild, moderate, and severe. Means comparison tests were used to assess rates of PJK and PJF (defined as PJK with reoperation) by alignment system in the cohort and by deformity group. Multivariate logistic regressions controlling for covariates such as age, PJK prophylaxis, and osteoporosis were used to generate odds ratios (OR) and identify the alignment systems associated with lower odds of developing PJK and PJF. <h3>RESULTS</h3> A total of 298 patients met inclusion (62.5yrs, BMI: 27.5kg/m², CCI: 1.5, 76% F). Overall, 33.6% of the cohort developed PJK and 6.7% developed PJF. MVA of the cohort found those aligned to AA had a 55% lower odds of PJK (OR: 0.453, [0.283, 0.727], p=.001) and 60.4% lower odds of PJF (OR: 0.396, [0.169, 0.933], p=.034). Subanalysis of patients presenting with mild deformity scores (N=71) found none of the alignment systems reduced odds of PJK or PJF (all p>.05). Subanalysis of patients presenting with moderate deformity scores (N=108) found those meeting AA had 79% lower odds of PJK (OR: 0.210, [0.072, 0.615], p=.004), yet none of the alignment systems significantly reduced odds of PJF. In those severe deformity scores (N=119), meeting Schwab significantly reduced odds of PJK (OR: 0.492, [0.318, 0.761], p=.001). With regard to PJF, in those with severe deformity scores, alignment to Schwab (OR: 0.235, [0.104, 0.532], p=.001) and AA significantly reduced odds of PJF (OR: 0.352, [0.124, 0.994], p=.049). <h3>CONCLUSIONS</h3> This study aimed to assess impact of realignment to published systems on rates of PJK and PJF in surgical correction of adult spinal deformity. Overally, those meeting age-adjusted alignment had lowest rates of PJK and PJF. Morover, further analysis revealed that moderately and severely deformed patients beneit benefit from realignment to age adjusted criteria. However, none of the alignment systems were associated with lower odds of PJK or PJF in those presenting with mild deformity. This may indicate a certain level of PJK and PJF is not preventable by optimal realignment alone. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

163. Assessing the influence of modifiable patient-related factors on complication rates following adult spinal deformity surgery

<h3>BACKGROUND CONTEXT</h3> Surgical correction of adult spinal deformity (ASD) has been associated with superior alignment and functional outcomes. However, postoperative complication rates remain relatively high. The extent to which potentially modifiable patient-related factors can influence complication rates in adult spinal deformity patients has not been effectively evaluated. <h3>PURPOSE</h3> Evaluate the association between modifiable patient-related factors on complications following ASD corrective surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective. <h3>PATIENT SAMPLE</h3> A total of 689 ASD patients. <h3>OUTCOME MEASURES</h3> Complication and reoperation rates. <h3>METHODS</h3> ASD patients with 2-year (2Y) data were included. Complication groups were defined as follows: 1) any complication; 2) major; 3) medical (cardiac event, ileus, etc.); surgical (site infection, wound dehiscence, etc.); 5) major mechanical (implant failure, rod fracture); 6) major radiographic (PJF [proximal junctional failure], pseudarthrosis, adjacent segment disease); and 7) reoperation. Modifiable risk factors included current smoker, obesity (BMI >30kg/m²), osteoporosis, alcohol use, depression (BL SF-36 MCS <35, perMatcham), psychiatric diagnosis and hypertension. Patients were stratified by BL deformity severity in T1PA (LowDef/HighDef) and age above or below 65 (Young/Older). Means comparison tests assessed prevalence of modifiable risk factors present in those developing specified complications. Binary logistic regression analysis was used to adjust for confounders. <h3>RESULTS</h3> A total of 480 ASD patients met inclusion criteria (age 59±15 yrs, 77%F, BMI 27±5 kg/m², CCI: 1.7±1.7). By 2Y, comp rates: 72% one complication, 28% major, 21% medical, 27% surgical, 11% major radiographic, and 8% had a major mechanical complication. A total of 106 patients (22%) required reoperation. Overall, 318 patients (66%) had at least one of the preoperative risk factors. Age-Deformity Groups: 32% Young LowDef, 19% Young HighDef, 18% Older LowDef, 31% Older HighDef. Within Young LowDef, patients with osteoporosis were more likely to suffer either a major mechanical or radiographic comp (both OR >6, p<.05), although this trend was not seen in the overall cohort. Young HighDef patients were much more likely to develop complications if obese, especially major mechanical complications (OR: 2.8, [1.04-8.6]; p=.045), while patients with depression or a psychiatric diagnosis suffered major radiographic comps and underwent reoperation more often. Older patients with HighDef developed significantly more complications when diagnosed with depression, including major radiographic comps (23% vs 8%, OR: 3.5, [1.1-10.6]; p=.03). Overall, when controlling for baseline deformity, frailty, and osteoporosis, a diagnosis of depression proved to be a significant risk factor for development of major radiographic complications (OR: 2.4, [1.3-4.5]; p=.005). <h3>CONCLUSIONS</h3> Certain modifiable patient-related factors, especially mental health status, are associated with increased risk for complications following spinal deformity surgery. Therefore, with consideration to clinical presentation, elaborate on the utility in medical intervention prior to undergoing spinal deformity corrective surgery. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P95. A comparative analysis of thoracic decompensation versus proximal junctional kyphosis in response to adult spinal deformity corrective surgery

<h3>BACKGROUND CONTEXT</h3> Thoracic decompensation (TD) represents a distinct radiographic complexity from proximal junctional kyphosis (PJK). Few studies exist on the occurrence of TD following adult spinal deformity (ASD) corrective surgery. <h3>PURPOSE</h3> To assess the incidence of TD following ASD-corrective surgery in comparison with the occurrence of PJK. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort. <h3>PATIENT SAMPLE</h3> A total of 689 ASD patients. <h3>OUTCOME MEASURES</h3> ASD, TD, PJK, thoracic compensation. <h3>METHODS</h3> ASD patients with complete baseline (BL) and two-year (2Y) followup were included. Patients were divided into groups: those who developed TD: T4-T12 >54.2° and those who developed PJK. Further analysis assessed outcomes among patients with both TD and PJK (TDPJK). Thoracic compensation was defined as expected thoracic kyphosis minus BL thoracic kyphosis. Means comparison tests and multivariable logistic regression analysis assessed differences between patient groups. <h3>RESULTS</h3> A total of 373 patients met inclusion criteria. Patient breakdown by radiographic outcome was: TD (N=31), PJK (N=223) and TDPJK (N=119). Age, gender, and ASD-mFI were similar between TD and PJK patients. TD patients were more likely to be osteoporotic than PJK patients, p < 0.05. Procedures on TD patients were less invasive and utilized a shorter construct (9.3 vs 11.5 levels; both p < 0.05). TD patients had significantly greater cervical lordosis, thoracic kyphosis, and lumbar lordosis than PJK patients at BL and 2Y follow-up, all p < 0.05. Thoracic compensation was significantly associated with TD (OR 1.07 [CI 1.04-1.09], p < 0.001) controlling for age, ASD-mFI, and invasiveness. TDPJK had the highest complication rate (84.9%), significantly greater than PJK patients (70.9%), and TD patients (61.3%), both p < 0.05. PJK patients were 78.7% less likely to develop PJF than TDPJK patients (OR 0.213 [CI 0.101-0.453], p < 0.001). <h3>CONCLUSIONS</h3> Patients who developed thoracic decompensation were more likely to present with osteoporosis, but had less invasive procedures and levels fused than patients with proximal junctional kyphosis. The tradeoff between fusing too much resulting in proximal junctional kyphosis and fusing too little predisposing to thoracic decompensation can serve as the basis of future studies to determine optimal construct length to balance these two risks. Thoracic compensation was predictive of postoperative thoracic decompensation in adult spinal deformity-correction. Patients who developed TDPJK had the highest rate of complications and greater odds of junctional failure. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

146. Optimizing health prior to adult spinal deformity surgery: are costs outweighed by perioperative benefits?

<h3>BACKGROUND CONTEXT</h3> Operative adult spinal deformity (ASD) patients are particularly vulnerable to the deleterious impact of comorbidities, thus preoperative optimization of modifiable health factors may improve surgical outcomes and improve cost effectiveness. <h3>PURPOSE</h3> To assess impact of preoperative optimization of modifiable health conditions on perioperative complications and operative costs in patients undergoing surgical correction of ASD. <h3>STUDY DESIGN/SETTING</h3> Retrospective analysis of patients prospectively enrolled in a single center ASD database. <h3>PATIENT SAMPLE</h3> This study included 269 ASD patients. <h3>OUTCOME MEASURES</h3> Perioperative complications, cost effectiveness. <h3>METHODS</h3> ASD patients with perioperative data were included. Optimization of diabetes (DM), osteoporosis, and nutritional status was assessed. Patients with DM were considered optimized (Opt) if preop HbA1c≤7%. Those with osteoporosis were Opt if treated with an FDA-approved drug prior to surgery. In contrast, nutritional status was assessed by ranking patients into quartiles (Q1-Q4) by baseline BMI. Q1 (low BMI) and Q4 (high BMI) were considered N-Opt. Total Costs (TC) were calculated from average Medicare DRG reimbursement. Where applicable, preop (≤90 days) costs incurred that were directly related to optimization (eg, drugs) were added to TC. Multivariable analyses assessed perioperative outcomes while accounting for surgical and demographic differences between groups. <h3>RESULTS</h3> A total of 269 patients were included (24.2% DM; 15.2% osteoporotic). Of diabetics (70.8% Opt; 29.2% N-Opt), Opt patients had 94.1% lower odds of wound infection (OR: 0.059 [0.007, 0.491], p=.009) and 89.3% lower odds of 90-day readmission (OR: 0.107 [0.033, 0.352], p .05), odds of periop complications were significantly reduced for patients in Q2 (OR: 0.354 [0.200, 0.625], p <.001) and Q3 (OR: 0:380 [0.193, 0.751], p=.005) and TC were significantly lower in Opt quartiles (all p <.001). <h3>CONCLUSIONS</h3> Despite accounting for surgical differences and costs of preoperative interventions, total costs were significantly lower in optimized patients. Thus, optimizing modifiable health conditions prior to surgery may benefit ASD patients by reducing perioperative complications while also minimizing utilization of hospital resources and lowing total costs. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

54. PMMA augmentation is not protective against proximal junctional kyphosis in adult spinal deformity correction bridging the thoracolumbar junction

<h3>BACKGROUND CONTEXT</h3> Proximal junctional kyphosis (PJK) is a relatively common complication following adult spinal deformity surgery. Some studies have demonstrated cement augmentation of the upper instrumented vertebra (UIV) decreases development of acute PJK, while others have been inconclusive. This study quantifies the radiographic progression of PJK in patients undergoing instrumented spinal fusion for adult deformity crossing the thoracolumbar junction with and without polymethylmethacrylate (PMMA) vertebroplasty. <h3>PURPOSE</h3> Determine whether polymethylmethacrylate (PMMA) vertebroplasty is protective against development of proximal junctional kyphosis. <h3>STUDY DESIGN/SETTING</h3> Single center, retrospective. <h3>PATIENT SAMPLE</h3> One hundred patients who underwent thoracolumbar fusion between 2013 and 2020. <h3>OUTCOME MEASURES</h3> Development of proximal junctional kyphosis at 6 weeks, 6 months, 12 months and 24 months postoperative. <h3>METHODS</h3> A retrospective cohort of 100 patients who underwent thoracolumbar fusion between 2013 and 2020 was identified. PMMA augmentation at the UIV and UIV+1 was performed at the discretion of the treating surgeon. Degree of PJK was measured from preoperative scoliosis, immediate postoperative, 6-week, 6-month, 12-month, and 24-month radiographs. Osteoporosis and osteopenia were defined as a DEXA T score ≤ -2.5 and ≤ -1, respectively. Differences in PJK and reoperation rates between PMMA and non-PMMA groups were assessed with stratified Kaplan-Meier survival curves and 95% confidence intervals with log-rank tests. Other categorical variables were assessed with chi-square and Fisher's exact tests while continuous variables were assessed with Mann Whitney U tests. Bonferroni correction was used to adjust the error rate for the multiple time points when appropriate. Multivariable Cox proportional hazard models adjusted for osteoporosis, degenerative disc disease, number of levels fused, pain medications taken, osteoporosis medications taken, age, sex and PI-LL mismatch > ± 9. All analyses were performed with SAS vs 9.4 with a two-sided level of significance of α = 0.05. <h3>RESULTS</h3> One hundred patients were included. The median age was 68 (interquartile range (IQR) 64-73) and median follow up was 43 months (IQR 34 - 54). Of the cohort, 56% received PMMA, and this group was significantly older (p=0.021), more often female (p=0.04), and had a higher rate of osteopenia (p < 0.01) and osteoporosis (p=0.038), took more preoperative pain medications (p=0.02), and more often underwent concurrent decompression (p < 0.01). Patients augmented with PMMA had significantly lower DEXA scores (p=0.024). Of PMMA patients, 55.4% developed PJK compared to 44.6% of Non-PMMA patients (p=0.097). Patients augmented with PMMA had higher rates of PJK at 6 months, but there was no difference at any further time point. The rate of all cause reoperation was 7.1% in the PMMA group compared to 11.4% in the Non-PMMA group (p=0.501). In multivariable models, PJK risk was significantly predicted by the presence of osteopenia (p=0.002) and presence of osteoporosis (p < 0.03). After risk adjustment, there was no difference in PJK rates attributable to PMMA use (HR 0.77, 95% CI 0.38-1.6, p = 0.47). <h3>CONCLUSIONS</h3> In long thoracolumbar fusions for adult spinal deformity, PMMA augmentation was not protective against PJK. Osteopenia and osteoporosis were significantly associated with higher rates of PJK. This suggests a complex interplay of surgical, biomechanical and patient factors in achieving an optimal outcome. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P96. A parameter fixed to poor outcomes: a detailed analysis of high Pelvic incidence in adult spinal deformity surgery

<h3>BACKGROUND CONTEXT</h3> Pelvic incidence (PI) serves as the cornerstone for many deformity classifications and realignment schema to create a more individualized realignment target for each patient. Yet, previous literature has linked high PI to problematic outcomes following corrective surgery, including mechanical complications and hip pathologies. <h3>PURPOSE</h3> Investigate if patients with high pelvic incidence have increased risk for complications and poor clinical outcomes following ASD surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective. <h3>PATIENT SAMPLE</h3> A total of 689 ASD patients. <h3>OUTCOME MEASURES</h3> Clinical Outcomes (ODI, SF-36 PCS, MCS), mechanical failure, surgical details. <h3>METHODS</h3> ASD patients with 2-year (2Y) data included. Groups: PI >65° (HighPI) versus PI < 65° (NormPI). Means comparison tests assessed differences in demographics, surgical details and outcomes between groups. Multivariate analysis controlling for baseline age, frailty, baseline PI-LL, and history of prior fusion, analyzed complication rates and clinical improvement between groups. <h3>RESULTS</h3> Included: 445 ASD patients. There were 94 (21%) patients presented with a BL pelvic incidence greater than 65° (HighPI). HighPI patients were older (63 yrs), shorter, with higher BMI and frailty (all p<.05). HighPI were more likely to have had a prior fusion (OR: 1.9, [1.2-3.1]). HighPI were more likely to present with lower physical functioning scores, and severe pelvic compensation (OR: 5.5, [3.4-8.9]) and global deformity (OR: 3.5, [2.2-5.6]). During surgery, HighPI underwent more 3COs (OR: 1.8,[1.1-3.1]) and fusion to pelvis (OR: 2.1,[1.1-3.9]). Upon correction, adjusted analysis revealed HighPI were more likely to be undercorrected in each age-adjusted parameter compared to LowPI (OR: 4.8, [2.9-7.8]). Yet, HighPI patients were less likely to deteriorate within in-construct PI-based alignment (relative lordosis and lordosis distribution) (OR: 0.3,[0.1-0.9]). While not different at six weeks, HighPI were more likely to deteriorate in PI-based global alignment and pelvic compensation from six weeks to two years (OR: 3.2, [1.6-6.5]). This translated to a higher likelihood of developing a major or mechanical complication by 2Y (OR: 1.6, [1.04-2.6]) via adjusted analysis. <h3>CONCLUSIONS</h3> High pelvic incidence is associated with increased frailty, decreased physical functioning, and more severe lumbopelvic and global deformity upon presentation for adult spinal deformity correction. These patients are more often undercorrected by age-adjusted standards and deteriorate in out-of-construct alignment over time even when adequately corrected, leading to higher mechanical complications by two years. Despite our focus on PI-adjusted alignment, we have still not optimized treatment for the patient with high pelvic incidence. Further research should target which surgical techniques and strategies can achieve better results in this population. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

53. Determination of risk benefit thresholds for corrective adult spinal deformity surgery with consideration of frailty and severity of sagittal malalignment at presentation

<h3>BACKGROUND CONTEXT</h3> Adult spinal deformity is associated with severe pain and disability. Recent literature has shown that surgical intervention can significantly improve patient's quality of life and lessen disease burden. As many patients requiring spine surgery are elderly and often frail, restoration of alignment targets may differ. There is paucity in literature on whether different frailty and deformity states may warrant a different level of surgical invasiveness. <h3>PURPOSE</h3> To investigate the effect of frailty and deformity severity on appropriate surgical invasiveness. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study from multicenter database. <h3>PATIENT SAMPLE</h3> This study included 381 adult spinal deformity (ASD) patients. <h3>OUTCOME MEASURES</h3> Complications; health-related quality of life (HRQL); Oswestry Disability Index (ODI). <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. The ASD-FI was used to stratify patients into 2 categories: Not Frail (NF): 20. Four groups were formed by frailty and deformity severity: NF Low, F Low, NF Sev, F Sev. ANCOVA determined differences in Surgical Invasiveness (SI) among F/D groups. Logistic regression determined significant association between SI and reaching Ideal Clinical outcome (ICO), defined as: no major complications, no reoperations, and reaching MCID for ODI. Surgical Invasiveness (SI) was normalized to a scale of 0-100 using the SI range. Thresholds for invasiveness and achieving ICO were found through conditional inference tree (CIT) analysis. <h3>RESULTS</h3> A total of 381 ASD patients (59.3±15yrs, 26.9± kg/m2, CCI: 1.52±1.6, FI: 3.09±1.6) were included and underwent surgery (11.6±4 lvls fused, EBL: 1522±1275 mL, op time: 337±124 min, LOS: 7.3±3.9 days), with 62.2% having a posterior-only approach, 36.5% combined approach, 46% having a decompression and 65% an osteotomy. By deformity severity: 60% Low-Mod, 40% Severe, while frailty assessment was 49% NF, and 51% F. This categorized the patients into deformity/frailty groups as follows: 35% NF Low, 13% NF Sev, 22% F Low, 25% F Sev. Patients had a significantly different degree of SI: 35 NF Low/Mod, 38 F Low/mod, 48 NF Sev, 50 F Sev (p<0.001). CIT analysis found NF Sev patients had a higher likelihood of reaching ICO with an SI below 40 (OR: 3.6, 95% CI: 1.1-12.1, p=.037), and F Sev with a SI below 30 (OR: 4.6, 95% CI: 1.7-12.6, p=.003). Low/mod groups revealed no significant association between invasiveness and achieving ICO. <h3>CONCLUSIONS</h3> Analysis of increasing surgical invasiveness in patients stratified by frailty and baseline deformity showed frail severely deformed patients, compared with non-frail severely deformed patients, had a lower invasiveness threshold above which there was a higher risk of major complications, reoperations and failure to reach clinically important improvement in ODI. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Prevalence and Modes of Posterior Hardware Failure With a Staged Protocol for Circumferential Minimally Invasive Surgical Correction of Adult Spinal Deformity: A 13-Year Experience

One of the common complications of adult spinal deformity (ASD) correction is the failure to relieve pain. This may result from the failure of implanted hardware to provide adequate stabilization. While numerous studies exist, characterizing complications that can occur with minimally invasive correction of ASD and data regarding hardware failure in this setting are limited. This article characterizes the rate and mode of posterior hardware failure in the setting of circumferential minimally invasive surgery (CMIS) for ASD correction. Patients undergoing staged CMIS correction of ASD from January 2007 to September 2018 were identified. Patients with a minimum 2-year follow-up were included in the study. A total of 263 patients (168 women and 95 men) were included in the study. The mean age of patients was 64 years (21-85, SD 13.7), and the mean length of follow-up was 90 months (24-164, SD 40.2). An average of 6 levels (3-16, SD 3.15) was fused per patient.Eight patients had a mechanical hardware failure and required revision surgery (3.04%). No catastrophic failures were noted in our series. Hardware failures were characterized as follows: 2 patients with broken screws, 5 patients with loose screws, and 1 patient who had symptomatic T12-L1 and L5-S1 nonunion with bilateral distal rod fractures, iliac set screw loosening, and proximal T12 screw loosening. Following revision surgery, all of these patients had confirmed solid fusion on computed tomography (CT) scan at their latest follow-up visit.Interestingly, 3 other patients had loosening of the set screw on their iliac bolts. Five patients had rod fractures between L5 and S1 or below S1. All 8 of these patients were asymptomatic with confirmed fusion at L5-S1 on CT scans. The prevalence of clinically significant hardware failure needing revision in our series was low at 3.04%. Symptomatic hardware prominence requiring revision was 2.3%. Specifically, rod fractures were not common (2.2%). Our study suggests that in the appropriately selected patient, CMIS to correct ASD without osteotomies may result in acceptable rates of hardware failure. Future studies should compare the results of CMIS deformity correction to a matched population of patients undergoing open deformity correction. This study suggests that in the appropriately selected patient, CMIS to correct ASD without osteotomies may result in acceptable rates of hardware failure.