Corrective Surgery For Adult Spinal Deformity Research Articles

The Incremental Clinical Benefit of Adding Layers of Complexity to the Planning and Execution of Adult Spinal Deformity Corrective Surgery.

For patients with surgical adult spinal deformity (ASD), our understanding of alignment has evolved, especially in the last 20 years. Determination of optimal restoration of alignment and spinal shape has been increasingly studied, yet the assessment of how these alignment schematics have incrementally added benefit to outcomes remains to be evaluated. Patients with ASD with baseline and 2-year were included, classified by 4 alignment measures: Scoliosis Research Society (SRS)-Schwab, Age-Adjusted, Roussouly, and Global Alignment and Proportion (GAP). The incremental benefits of alignment schemas were assessed in chronological order as our understanding of optimal alignment progressed. Alignment was considered improved from baseline based on SRS-Schwab 0 or decrease in severity, Age-Adjusted ideal match, Roussouly current (based on sacral slope) matching theoretical (pelvic incidence-based), and decrease in proportion. Patients separated into 4 first improving in SRS-Schwab at 2-year, second Schwab improvement and matching Age-Adjusted, third two prior with Roussouly, and fourth improvement in all four. Comparison was accomplished with means comparison tests and χ2 analyses. Sevenhundredthirty-two. patients met inclusion. SRS-Schwab BL: pelvic incidence-lumbar lordosis mismatch (++:32.9%), sagittal vertical axis (++: 23%), pelvic tilt (++:24.6%). 640 (87.4%) met criteria for first, 517 (70.6%) second, 176 (24%) third, and 55 (7.5%) fourth. The addition of Roussouly (third) resulted in lower rates of mechanical complications and proximal junctional kyphosis (48.3%) and higher rates of meeting minimal clinically important difference (MCID) for physical component summary and SRS-Mental (P < .05) compared with the second. Fourth compared with the third had higher rates of MCID for ODI (44.2% vs third: 28.3%, P = .011) and SRS-Appearance (70.6% vs 44.8%, P < .001). Mechanical complications and proximal junctional kyphosis were lower with the addition of Roussouly (P = .024), while the addition of GAP had higher rates of meeting MCID for SRS-22 Appearance (P = .002) and Oswestry Disability Index (P = .085). Our evaluation of the incremental benefit that alignment schemas have provided in ASD corrective surgery suggests that the addition of Roussouly provided the greatest reduction in mechanical complications, while the incorporation of GAP provided the most significant improvement in patient-reported outcomes.

Highest Achievable Outcomes for Adult Spinal Deformity Corrective Surgery: Does Frailty Severity Exert a Ceiling Effect?

Retrospective Single-Center Study. To assess the influence of frailty on optimal outcome following ASD corrective surgery. Frailty is a determining factor in outcomes after ASD surgery and may exert a ceiling effect on best possible outcome. ASD patients with frailty measures, baseline and 2-year ODI included. Frailty was classified as Not Frail (NF), Frail (F) and Severely Frail (SF) based on the modified Frailty Index, then stratified into quartiles based on 2-year ODI improvement (most improved designated "Highest"). Logistic regression analyzed relationships between frailty and ODI score and improvement, maintenance, or deterioration. A Kaplan-Meier survival curve was used to analyze differences in time to complication or reoperation. 393 ASD patients were isolated (55.2% NF, 31.0% F, and 13.7% SF), then classified as 12.5% NF-Highest, 17.8% F-Highest, and 3.1% SF-Highest. The SF-group had the highest rate of deterioration (16.7%, P=0.025) at the second postoperative year but the groups were similar in improvement (NF: 10.1%, F: 11.5%, SF: 9.3%, P=0.886). Improvement of SF patients was greatest at 6 months (ΔODI of -22.6±18.0, P<0.001) but NF and F patients reached maximal ODI at 2 years (ΔODI of -15.7±17.9 and -20.5±18.4, respectively). SF patients initially showed the greatest improvement in ODI (NF: -4.8±19.0, F: -12.4±19.3, SF: -22.6±18.0 at 6 months, P<0.001). A Kaplan-Meier survival curve showed a trend of less time to major complication or reoperation by 2 years with increasing frailty (NF: 7.5±0.381 years, F: 6.7±0.511 years, SF: 5.8±0.757 years; P=0.113). Increasing frailty had a negative effect on maximal improvement, where severely frail patients exhibited a parabolic effect with greater initial improvement due to higher baseline disability, but reached a ceiling effect with less overall maximal improvement. Severe frailty may exert a ceiling effect on improvement and impair maintenance of improvement following surgery. III.

326 Factors Associated With the Maintenance of Cost-Effectiveness at 5 Years in Adult Spinal Deformity Corrective Surgery

INTRODUCTION: Substantial increase of costs in the surgical treatment of adult spinal deformity has given precedence to scrutinize the value it can provide hence cost-effectiveness (CE) is a vital analytical constituent. The analysis of factors associated with the durability of cost-effectiveness at 5 years has not been previously evaluated. METHODS: Adult spinal deformity (ASD) patients with baseline (BL) to 5-year (5Y) data were included. Cost calculation using PearlDiver database and CMS.gov definitions was used. Cost analysis was based on average DRG reimbursement rates. ODI was converted to SF-6D, with a 3% discount applied for residual decline in life expectancy. Cost per QALY gained at 2Y and 5Y was calculated. Threshold value for cost per QALY was $100,000. Patients that met 2Y (CE2+) were grouped based on meeting CE at 5Y(CE5+) or not(CE5-). Analysis based on meeting cost-effectiveness (CE) at 2Y and 5Y was conducted. Conditional-inference-tree (CIT) established cutoffs values for HRQLs. RESULTS: 299 patients with 5Y data were included. Major and minor complication rates were 11% and 47% respectively, while 26% underwent reoperation by 5Y. The mean cost of surgery was $91,095 ± $47,003, utility-gain of 0.091 ± 0.086, and QALY of 0.171 ± 0.183, CE of $118,976 ± $208,323. 85.5% of the cohort met CE at 2Y, 79.2% at 5Y, whereas 59.6% met both. Frailty was comparable at baseline but was worse in CE5- at 2Y. CIT depicted 2Y ODI &lt; 18 and SRS-22r &gt; 3.3 (both p &lt; 0.03) being associated with higher rates of C5+. Multivariable-regression depicted higher baseline CCI and pelvic tilt (PT) to be the strongest baseline predictors of not maintaining CE at 5Y (CCI OR: 1.821, p = 0.009) (PT OR: 1.079, p = .030). CONCLUSIONS: The majority that met cost-effectiveness at the 2 year went on to maintain it at 5 years. Lower baseline CCI and PT were strong predictive factors.

168 Sustenance of Substantial Clinical Benefit in Adult Spinal Deformity Corrective Surgery Patients: A Minimum 5-Year Outcomes Analysis

INTRODUCTION: Clinical outcomes for adult spinal deformity patients has been extensively reported on, however factors associated with sustaining two year (2Y) substantial clinical benefit (SCB) till five year (5Y) remains unclear. METHODS: ASD patients fused from at least L1 to sacrum with 5Y postoperative data were included. Good Outcome(GO) was defined as: no reoperation, mechanical failure, proximal junctional failure(PJF) based on Lafage criteria, and [meeting either: (1) SCB for Oswestry Disability Index(ODI)(decrease of &gt;18.8), or (2) ODI &lt;15 and Scoliosis Research Society(SRS-22r) Total&gt;4.5]. Multivariable analysis controlled for age, BMI, CCI, frailty, deformity, HRQLs, and surgical variations. RESULTS: 330 ASD patients were included. 42% achieved GO at 2Y(2+) while 47% at 5Y(5+) did. 71% of 2+ cohort attained 5+. In 2- cohort, 29% achieved 5+. Isolating 2+ cohort, assessing 5+ vs 5-: 5- had greater SVA deformity at 5Y (p &lt; .05). Regaining the level of activity postoperatively was associated with 4x higher odds of maintaining GO from 2Y to 5Y (p &lt; .05). The odds of achieving GO at 5Y in 2+ decreased by 47% for each additional comorbidity and decreased by 74% in those that had lower extremity paresthesias at BL (both p &lt; .05). Decreased number of levels fused, decreased correction in SVA and increased correction in PI-LL to be predictive of sustaining 2Y GO till 5Y (all p &lt; 0.05). CONCLUSIONS: Overall, 47% had substantial clinical benefit till 5Y. While 71% of patients at 2Y sustained good clinical outcome till 5Y, major contributors to its loss were adjacent segment changes and rod fracture. The odds of achieving SCB till 5Y decreased by nearly 50% for each additional comorbidity. Decreased levels fused along with decreased correction of SVA and increased correction in PI-LL were predictive of optimal sustaining of clinical outcomes.

1073 Prone Transpsoas (PTP)-LLIF Approach Versus Standard LLIF in Patients Undergoing Surgical Revision Following Adult Spinal Deformity Correction Surgery

INTRODUCTION: Both the prone transpsoas (PTP) and standard LLIF have been developed to facilitate minimally invasive (MIS) indirect decompression, alignment correction, and posterior instrumentation. METHODS: A multi-center cohort of all patients was identified and all relevant data were retrospectively collected. Preoperative standing 36” scoliosis radiographs were retrospectively reviewed for pelvic incidence (PI), lumbar lordosis (LL), and PI minus LL (PI-LL mismatch). Postoperative regional sagittal alignment parameters were measured using the first postoperative standing 36” scoliosis radiographs. Finally, multivariable analysis was performed to assess the primary outcome measure: postoperative change in regional sagittal alignment (PI-LL mismatch). RESULTS: Two-hundred and two (n = 202) patients were retrospectively identified and included for formal analysis. One-hundred and fifty one (n = 151, 74.8%) of the patients underwent PTP revision while 51 (25.2%) underwent standard LLIF revision. Univariate analysis demonstrated a greater value for baseline mean pre-operative PI-LL mismatch in the PTP versus standard LLIF cohort (21.4 vs. 10.45°; p = 0.0001). Furthermore, multiple linear regression demonstrated that the PTP approach enabled significantly greater PI-LL mismatch change (p = 0.0017) and that this change was associated with the number of levels fused (p = 0.0481) as well as percutaneous (vs. open) screw placement (p = 0.0193). Finally, multiple logistic regression identified standard LLIF (p = 0.0378), female sex (p &lt; 0.0001), non-osteoporotic bone density (p &lt; 0.0001), and younger age (p &lt; 0.0001) as predictive of postoperative PI-LL mismatch &lt; 10° (the threshold under which such mismatch is no longer regarded as clinically significant deformity). CONCLUSIONS: Ultimately, PTP-LLIF was associated with greater net improvement in postoperative PI-LL mismatch, the primary outcome measure of this study. The present retrospective analysis therefore corroborated results of previous studies in suggesting that the utility of PTP-LLIF is translatable to ASD revision surgery.

Causes of Intraoperative Neuromonitoring Events in Adult Spine Deformity Surgery: A Systematic Review.

Systematic review. Intraoperative neuromonitoring (IOMN) has become a standard practice in the detection and prevention of nerve damage and postoperative deficit. While multicenter studies have addressed this inquiry, there have been no systematic reviews to date. This systematic review identifies the leading causes of IONM alerts during adult spinal deformity (ASD) surgeries. Following PRISMA guidelines, a literature search was performed in PubMed and Embase. IONM alert causes were grouped by equivalent terms used across different studies and binned into larger categories, including surgical maneuver, Changes in blood pressure/temperature, Oxygenation, Anesthesia, Patient position, and Unknown. Inclusion criteria were studies on adult patients receiving ASD correction surgery using IONM with documented alert causes. 1544 references were included in abstract review, 128 in full text review, and 16 studies qualified for data extraction. From those studies, there was a total of 3945 adult patients with 299 IONM alerts. Surgical maneuver led the alert causes (258 alerts/86.3%), with signal loss most commonly occurring at correction or osteotomy (101/33.8% and 95/31.8% respectively). Pedicle screw placement caused 35 alerts (11.7%). Changes in temperature and blood pressure were the third largest category (34/11.4%). The most frequent causes of IONM alerts in ASD surgery were surgical maneuvers such as correction, osteotomy, and pedicle screw placement. This information provides spine surgeons with a quantitative perspective on the causes of IONM changes and show that most occur at predictable times during ASD surgery.

Factors Associated with the Maintenance of Cost-Effectiveness at 5 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 5-year (5Y) follow-up. Published methods were used to determine costs based on CMS.gov definitions and were based on the average DRG reimbursement rates. 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 with 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 5Y. The mean cost associated with surgery was $91,095±$47,003, with a utility gain of 0.091±0.086 at 1Y, QALY gained at 2Y of 0.171±0.183, and at 5Y of 0.42±0.43. The cost per QALY at 2Y was $414,885, which decreased to $142,058 at 5Y.With the threshold of $150,000 for CE, 19% met CE at 2Y and 56% at 5Y. 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 5Y (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 2Y, while comorbidity burden and medical complications were at 5Y.

Decisional regret following corrective adult spinal deformity surgery: a single institution study of incidence and risk factors.

To assess the characteristics and risk factors for decisional regret following corrective adult spinal deformity (ASD) surgery at our hospital. This is a retrospective cohort study of a single-surgeon ASD database. Adult patients (> 40years) who underwent ASD surgery from May 2016 to December 2020 with minimum 2-year follow-up were included (posterior-only, ≥ 4 levels fused to the pelvis) (n = 120). Ottawa decision regret questionnaires, a validated and reliable 5-item Likert scale, were sent to patients postoperatively. Regret scores were defined as (1) low regret: 0-39 (2) medium to high regret: 40-100. Risk factors for medium or high decisional regret were identified using multivariate models. Ninety patients were successfully contacted and 77 patients consented to participate. Nonparticipants were older, had a higher incidence of anxiety, and higher ASA class. There were 7 patients that reported medium or high decisional regret (9%). Ninety percentage of patients believed that surgery was the right decision, 86% believed that surgery was a wise choice, and 87% would do it again. 8% of patients regretted the surgery and 14% believed that surgery did them harm. 88% of patients felt better after surgery. On multivariate analysis, revision fusion surgery was independently associated with an increased risk of medium or high decisional regret (adjusted odds ratio: 6.000, 95% confidence interval: 1.074-33.534, p = 0.041). At our institution, we found a 9% incidence of decisional regret. Revision fusion was associated with increased decisional regret. Estimates for decisional regret should be based on single-institution experiences given differences in patient populations.

Achievement and Maintenance of Optimal Alignment After Adult Spinal Deformity Corrective Surgery: A 5-Year Outcome Analysis

We sought to assess factors contributing to optimal radiographic outcomes. Operative adult spinal deformity (ASD) patients with baseline and 5-year (5Y) data were included. Optimal alignment (O) was defined as improving in at least 1 Scoliosis Research Society-Schwab modifier without worsening in any Scoliosis Research Society-Schwab modifier. A robust outcome was defined as having optimal alignment 2 years (2Y) post operation that was maintained at 5Y. Predictors of robust outcomes were identified using multivariate regression analysis, with a conditional inference tree for continuous variables. Two-hundred and ninety-seven ASD patients met inclusion criteria. Most patients (77.4%) met O at 6W, which decreased to 54.2% at 2Y. The majority of patients (89.4%) that met O at 2Y went on to meet radiographic durability at 5Y (48.5% of total cohort). Rates of junctional failure were higher in O2+5- compared with O2+5- (P= 0.013), with reoperation rates of 17.2% due to loss of alignment. Multivariable regression identified the following independent predictors of optimal alignment at 5Y in those that had O at 2Y: inadequate correction of pelvic tilt and overcorrection of the difference between pelvic incidence and lumbar lordosis (P < 0.05). Increased age, body mass index, and invasiveness were the most significant nonradiographic predictors for not achieving 5Y durability (P < 0.05). The durability of optimal alignment after ASD corrective surgery was seen in about half of the patients at 5Y. While the majority of patients at 2Y maintained their radiographic outcomes at 5Y, major contributors to loss of alignment included junctional failure and adjacent region compensation, with only a minority of patients losing correction through the existing construct. The reoperation rate for loss of alignment was 17.2%. Loss of alignment requiring reoperation had a detrimental effect on 5Y clinical outcomes.

Adult spinal deformity correction surgery using age-adjusted alignment thresholds: clinical outcomes and mechanical complication rates. A systematic review of the literature.

Adult spinal deformity (ASD) surgery gives good clinical outcomes but has a high rate of mechanical complications (MC). In 2016, Lafage described the age-adjusted alignment thresholds (AAAT) to adapt the correction in relation to patient's age proposing less aggressive corrections for the elderly population. The aim of this review was to clarify the effectiveness of AAAT to achieve good health-related quality of life (HRQoL) and their relationship with post-operative MC. We performed a review of the literature, including articles reporting data on post-operative HRQoL and MC rates in relation to the AAAT. Data were stratified according to whether they matched the AAAT, dividing the population in undercorrected (U), matched (M) and overcorrected (O). The quality of the included studies was assessed using the GRADE and MINORS systems. Six articles reporting data from 1,825 patients were included. The different categories (U, M and O) had homogeneous pre-operative sagittal parameters (p > 0.05) that became statistically different after surgeries (p < 0.05). Proximal junctional kyphosis (PJK) was more frequent in the O group compared to U (p = 0.05). Post-operative HRQoL parameters were similar in the 3 groups (p > 0.05). The quality of the included studies was generally low with a high bias risk. The results extrapolated from this review are interesting, as for the same HRQoL the U group had a lower MC rate. Unfortunately, the results are inconsistent, mainly because of the low quality of the included studies and the lack of reporting of some important patient- and surgery-related factors.

5. Sustenance of substantial clinical benefit in adult spinal deformity corrective surgery patients: a minimum 5-year outcomes analysis

5. Sustenance of substantial clinical benefit in adult spinal deformity corrective surgery patients: a minimum 5-year outcomes analysis

137. Achievement and maintenance of optimal alignment following adult spinal deformity corrective surgery: a 5-year outcome analysis

137. Achievement and maintenance of optimal alignment following adult spinal deformity corrective surgery: a 5-year outcome analysis

Should realignment goals vary based on patient frailty status in adult spinal deformity?

The objective of this study was to adjust the sagittal age-adjusted score (SAAS) to accommodate frailty in alignment considerations and thereby increase the predictability of clinical outcomes and junctional failure. Surgical adult spinal deformity (ASD) patients with 2-year data were included. Frailty was assessed with the continuous ASD modified frailty index (ASD-mFI). Two-year outcomes were proximal junctional kyphosis (PJK), proximal junctional failure (PJF), major mechanical complications, and best clinical outcome (BCO), defined as Oswestry Disability Index (ODI) score < 15 and Scoliosis Research Society outcomes questionnaire total score > 4.5 by 2 years. Linear regression analysis established a 6-week score based on the component scores of SAAS, frailty, and US normal values for ODI score. Logistic regression analysis followed by conditional inference tree run forest analysis generated categorical thresholds. Multivariate analysis, controlling for age, baseline deformity, and history of revision, was used to compare outcome rates, and logistic regression generated odds ratios for the continuous score. Thirty percent of the cohort was used as a random sample for internal validation. In total, 412 patients were included (mean ± SD age 60.1 ± 14.2 years, 80% female, BMI 26.9 ± 5.4 kg/m2). Baseline frailty categories were as follows: 57% not frail, 30% frail, and 14% severely frail. Overall, by 2 years, 39% of patients had developed PJK, 8% PJF, and 21% mechanical complications; 22% had undergone a reoperation; and 15% met BCO. When the cohort as a whole was assessed, the 6-week SAAS had a correlation with the development of PJK and PJF, but not mechanical complications, reoperation, or BCO. Development of mechanical complications, PJF, reoperation, and BCO demonstrated correlations with ASD-mFI (all p < 0.05). Regression analysis modifying SAAS on the basis of ODI norms and frailty generated the following equation: frailty-adjusted SAAS (FAS) = 0.108 × T1 pelvic angle + 0.162 × pelvic tilt - 0.39 × pelvic incidence - lumbar lordosis - 0.03 × ASD-mFI - 1.6771. With conditional inference tree analysis, thresholds were derived for FAS: aligned < 1.7, offset 1.7-2.2, and severely offset > 2.2. Significance between FAS categories was found for PJK, PJF, mechanical complications, reoperation, and BCO by 2 years. Binary logistic regression, controlling for baseline deformity and revision status, demonstrated significance between FAS and all 5 outcome variables (all p < 0.01). Internal validation saw each outcome variable maintain significance between categories, with even greater odds for PJF (OR 13.4, 95% CI 4.7-38.3, p < 0.001). Consideration of physiological age, in addition to chronological age, may be beneficial in the management of operative goals to maximize clinical outcomes while minimizing junctional failure. This combination enables the spine surgeon to fortify a surgical plan for even the most challenging patients undergoing ASD corrective surgery.

External Validation of the Global Alignment and Proportion Score as Prognostic Tool for Corrective Surgery in Adult Spinal Deformity: A Systematic Review and Meta-Analysis

Since its proposal, the Global Alignment and Proportion (GAP) score has been the topic of several external validation studies, which have yielded conflicting results. Given the lack of consensus regarding this prognostic tool, the authors aim to assess the accuracy of GAP scores for predicting mechanical complications following adult spinal deformity correction surgery. A systematic search was performed using PubMed, Embase, and Cochrane Library for the purpose of identifying all studies evaluating the GAP score as a predictive tool for mechanical complications. GAP scores were pooled using a random-effects model to compare patients reporting mechanical complications after surgery versus those reporting no complications. Where receiver operator curves were provided, the area under the curve (AUC) was pooled. A total of 15 studies featuring 2092 patients were selected for inclusion. Qualitative analysis using Newcastle-Ottawa criteria revealed moderate quality among all included studies (5.99/9). With respect to sex, the cohort was predominantly female (82%). The pooled mean age among all patients in the cohort was 58.55years, with a mean follow-up of 33.86months after surgery. Upon pooled analysis, we found that mechanical complications were associated with higher mean GAP scores, albeit minimal (mean difference=0.571 [ 95% confidence interval: 0.163-0.979]; P= 0.006, n= 864). Additionally, age (P= 0.136, n= 202), fusion levels (P= 0.207, n= 358), and body mass index (P= 0.616, n= 350) were unassociated with mechanical complications. Pooled AUC revealed poor discrimination overall (AUC=0.69; n= 1206). GAP scores may have a minimal-to-moderate predictive capability for mechanical complications associated with adult spinal deformity correction.

Treatment of adult deformity surgery by orthopedic and neurological surgeons: trends in treatment, techniques, and costs by specialty

BACKGROUND CONTEXTSurgery to correct adult spinal deformity (ASD) is performed by both neurological surgeons and orthopedic surgeons. Despite well-documented high costs and complication rates following ASD surgery, there is a dearth of research investigating trends in treatment according to surgeon subspeciality. PURPOSEThe purpose of this investigation was to perform an analysis of surgical trends, costs and complications of ASD operations by physician specialty using a large, nationwide sample. STUDY DESIGN/SETTINGRetrospective cohort study using an administrative claims database. PATIENT SAMPLEA total of 12,929 patients were identified with ASD that underwent deformity surgery performed by neurological or orthopedic surgeons. OUTCOME MEASURESThe primary outcome was surgical case volume by surgeon specialty. Secondary outcomes included costs, medical complications, surgical complications, and reoperation rates (30-day, 1-year, 5-year, and total). METHODSThe PearlDiver Mariner database was queried to identify patients who underwent ASD correction from 2010 to 2019. The cohort was stratified to identify patients who were treated by either orthopedic or neurological surgeons. Surgical volume, baseline characteristics, and surgical techniques were examined between cohorts. Multivariable logistic regression was employed to assess the cost, rate of reoperation and complication according to each subspecialty while controlling for number of levels fused, rate of pelvic fixation, age, gender, region and Charlson Comorbidity Index (CCI). Alpha was set to 0.05 and a Bonferroni correction for multiple comparisons was utilized to set the significance threshold at p ≤.000521. RESULTSA total of 12,929 ASD patients underwent deformity surgery performed by neurological or orthopedic surgeons. Orthopedic surgeons performed most deformity procedures accounting for 64.57% (8,866/12,929) of all ASD operations, while the proportion treated by neurological surgeons increased 44.2% over the decade (2010: 24.39% vs 2019: 35.16%; p<.0005). Neurological surgeons more frequently operated on older patients (60.52 vs 55.18 years, p<.0005) with more medical comorbidities (CCI scores: 2.01 vs 1.47, p<.0005). Neurological surgeons also performed higher rates of arthrodesis between one and six levels (OR: 1.86, p<.0005), three column osteotomies (OR: 1.35, p<.0005) and navigated or robotic procedures (OR: 3.30, p<.0005). Procedures performed by orthopedic surgeons had significantly lower average costs as compared to neurological surgeons (orthopedic surgeons: $17,971.66 vs neurological surgeons: $22,322.64, p=.253). Adjusted logistic regression controlling for number of levels fused, pelvic fixation, age, sex, region, and comorbidities revealed that patients within neurosurgical care had similar odds of complications to orthopaedic surgery. CONCLUSIONSThis investigation of over 12,000 ASD patients demonstrates orthopedic surgeons continue to perform the majority of ASD correction surgery, although neurological surgeons are performing an increasingly larger percentage over time with a 44% increase in the proportion of surgeries performed in the decade. In this cohort, neurological surgeons more frequently operated on older and more comorbid patients, utilizing shorter-segment fixation with greater use of navigation and robotic assistance.

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.

123 Early Postural Stability Changes in Patients Undergoing Correction of Spinal Deformity

INTRODUCTION: Adult spinal deformity (ASD) is an increasingly prevalent cause of pain and disability. It is known that ASD correction results in improved alignment, but not whether this alignment results in objective improvements in postural stability. METHODS: A retrospective review of a prospectively maintained database identified 16 patients undergoing ASD correction surgery with five or more segments. Balance was assessed via a force plate pre- and three months postoperatively. Participants were instructed to stand still, with their hands at their sides and eyes open. Center of pressure (COP) and center of gravity (COG) parameters were analyzed and used to derive head sway in the Dubousset cone of economy (COE). Spinopelvic parameters (PI, PT, SVA, and LL) on standing scoliosis radiographic films were also measured pre- and three months postoperatively. RESULTS: In our 16-patient series, there was a mean age of 61.3 years-old, and a median of 10 segments fused. Postoperative force plate assessment showed a decrease in total COP sway and sway velocity (p &lt; 0.05). Coronal COP sway and sway velocity also decreased (p &lt; 0.05). There was a decrease in total, coronal and sagittal COG sway and sway velocity postoperatively (p &lt; 0.05). In the COE, total head sway decreased (p &lt; 0.05). PT remained unchanged following surgical correction, while LL and SVA improved from 44.9° to 56.7° (p &lt; 0.01) and 82.2 to 22.5 mm (p &lt; 0.01), respectively. PI-LL mismatch also improved from 16.2° to 4.8° (p &lt; 0.01). CONCLUSIONS: Following long segment fusion for ASD, postural stability may improve as early as three months, concomitant with improved spinopelvic alignment. We believe force plate assessment warrants further study for postoperative evaluation of postural alignment and clinical outcomes in ASD patients.

Does Adult Spinal Deformity Affect Cardiac Function? A Prospective Perioperative Study.

Prospective comparative study. The objective of this study was to investigate perioperative cardiac function using echocardiography in patients undergoing surgery for the adult spinal deformity (ASD). Corrective surgery for ASD has increased, especially in older persons. However, perioperative complication rates remain high in ASD surgery, including cardiopulmonary complications. This study included patients with ASD who underwent surgery between May 2016 and April 2018. A cardiologist performed all echocardiography imaging preoperatively and 2 weeks postoperatively. Left ventricular contractility was measured using left ventricular ejection fraction (LVEF), and right ventricular contractility was measured using tricuspid annular plane systolic excursion (TAPSE) and tricuspid annular peak systolic velocity (S'). Spinopelvic radiographic parameters, the apices of thoracic kyphosis and lumbar lordosis, and the inflection point where the vertebral curvature changes from kyphosis to lordosis were also measured. Differences between preoperative and postoperative measurements for continuous variables were analyzed using a paired Student t test. Differences in continuous and categorical variables between two independent groups were analyzed using an unpaired Student t test and Fisher exact test, respectively. Multivariate logistic regression analyses were performed to detect influential factors. Sixty-one patients were included [12 males and 49 females; average age, 64.0 (22-84)yr]. LVEF, TAPSE, and S', respectively changed from 64.4%, 24.9mm, and 14.3cm/s to 65.4%, 25mm, and 15cm/s postoperatively with no significance. However, in LVEF<59.3% (average-1SD), TAPSE<17mm, and S'<11.8cm/s cases, respectively, these increased significantly from 55.7%, 17.9mm, and 10.5cm/s to 60.9%, 21.4mm, and 14.2cm/s postoperatively ( P =0.036, 0.029, and 0.022, respectively). The LVEF<59.3% group showed a significantly lower inflection point level (1.5 vs. 2.9) preoperatively ( P =0.007). The S'<11.8cm/s group showed significantly larger thoracic kyphosis (28.3° vs. 19.4°) preoperatively ( P =0.013). Perioperative cardiac function did not deteriorate after surgery in patients with ASD. In those with lower cardiac function preoperatively, there were significant improvements noted postoperatively. The preoperative inflection point level was significantly lower in the lower LVEF group. Preoperative thoracic kyphosis was significantly larger in the lower tricuspid annular peak systolic velocity group.

External Validation of the National Surgical Quality Improvement Program Calculator Utilizing a Single Institutional Experience for Adult Spinal Deformity Corrective Surgery.

Identify the external applicability of the American College of Surgeons' National Surgical Quality Improvement Program (NSQIP) risk calculator in the setting of adult spinal deformity (ASD) and subsets of patients based on deformity and frailty status. ASD patients were isolated in our single-center database and analyzed for the shared predictive variables displayed in the NSQIP calculator. Patients were stratified by frailty (not frail <0.03, frail 0.3-0.5, severely frail >0.5), deformity [T1 pelvic angle (TPA) > 30, pelvic incidence minus lumbar lordosis (PI-LL) > 20], and reoperation status. Brier scores were calculated for each variable to validate the calculator's predictability in a single center's database (Quality). External validity of the calculator in our ASD patients was assessed via Hosmer-Lemeshow test, which identified whether the differences between observed and expected proportions are significant. A total of 1606 ASD patients were isolated from the Quality database (48.7 years, 63.8% women, 25.8 kg/m2); 33.4% received decompressions, and 100% received a fusion. For each subset of ASD patients, the calculator predicted lower outcome rates than what was identified in the Quality database. The calculator showed poor predictability for frail, deformed, and reoperation patients for the category "any complication" because they had Brier scores closer to 1. External validity of the calculator in each stratified patient group identified that the calculator was not valid, displaying P values >0.05. The NSQIP calculator was not a valid calculator in our single institutional database. It is unable to comment on surgical complications such as return to operating room, surgical site infection, urinary tract infection, and cardiac complications that are typically associated with poor patient outcomes. Physicians should not base their surgical plan solely on the NSQIP calculator but should consider multiple preoperative risk assessment tools.

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