C2-T3 SVA Research Articles

Prioritization of Realignment Associated With Superior Clinical Outcomes for Cervical Deformity Patients.

ObjectiveTo prioritize the cervical parameter targets for alignment. MethodsIncluded: cervical deformity (CD) patients (C2–7 Cobb angle > 10°, cervical lordosis > 10°, cervical sagittal vertical axis [cSVA] > 4 cm, or chin-brow vertical angle > 25°) with full baseline (BL) and 1-year (1Y) radiographic parameters and Neck Disability Index (NDI) scores; patients with cervical [C] or cervicothoracic [CT] Primary Driver Ames type. Patients with BL Ames classified as low CD for both parameters of cSVA (< 4 cm) and T1 slope minus cervical lordosis (TS–CL) (< 15°) were excluded. Patients assessed: meeting minimum clinically important differences (MCID) for NDI (< -15 ΔNDI). Ratios of correction were found for regional parameters categorized by primary Ames driver (C or CT). Decision tree analysis assessed cutoffs for differences associated with meeting NDI MCID at 1Y. ResultsSeventy-seven CD patients (mean age, 62.1 years; 64% female; body mass index, 28.8 kg/m2). Forty-one point six percent of patients met MCID for NDI. A backwards linear regression model including radiographic differences as predictors from BL to 1Y for meeting MCID for NDI demonstrated an R2 of 0.820 (p=0.032) included TS–CL, cSVA, McGregor’s slope (MGS), C2 sacral slope, C2–T3 angle, C2–T3 SVA, cervical lordosis. By primary Ames driver, 67.5% of patients were C, and 32.5% CT. Ratios of change in predictors for MCID NDI patients for C and CT were not significant between the 2 groups (p>0.050). Decision tree analysis determined cutoffs for radiographic change, prioritizing in the following order: ≥ 42.5° C2–T3 angle, > 35.4° cervical lordosis, < -31.76° C2 slope, < -11.57-mm cSVA, < -2.16° MGS, > -30.8-mm C2–T3 SVA, and ≤ -33.6° TS–CL. ConclusionCertain ratios of correction of cervical parameters contribute to improving neck disability. Prioritizing these radiographic alignment parameters may help optimize patient-reported outcomes for patients undergoing CD surgery.

P110. Improvements in cost effectiveness of adult cervical deformity corrective surgery over time: Analysis of a prospective adult cervical deformity database

<h3>BACKGROUND CONTEXT</h3> As operative measures and field knowledge advance, we hope that there is an improvement in outcomes for adult cervical deformity surgery. This improvement can be described by cost effectiveness, which encompasses operative cost, poor outcomes such as complications, and patient-reported measures. <h3>PURPOSE</h3> To determine whether surgical methods have improved by reducing the instance of complications and cost of cervical deformity (CD) surgery while improving patient reported outcomes. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study of a prospectively enrolled multicenter CD database. <h3>PATIENT SAMPLE</h3> A total of 132 CD patients. <h3>OUTCOME MEASURES</h3> Complications, Reoperations, EQ5D, total cost, utility gained, Quality Adjusted Life Years (QALYs), Distal Junctional Kyphosis (DJK) <h3>METHODS</h3> CD patients with baseline (BL) and up to 2-year (2Y) HRQL data from 2013-2017 were included. Data from 2017 was combined with 2016 due to an incomplete year. ANCOVA found estimated marginal means of complications and reoperations adjusting for BL age, sex, surgical approach, and invasiveness. Cost was calculated using PearlDiver and assessed for Complications/Major Complications and Comorbidities according to CMS.gov. QALYs were calculated from EQ5D improvement and utilized 3% discount rate for residual decline to life expectancy (LE, 78.7 years). This data represents national average Medicare costs by surgical approach, complications and revision status. Trendline analysis noted changes over time. In a sub-analysis relating to a previous study, patients were identified by amount of risk factors for revision (UIV>C3, LIV>T3, C2-T3 SVA<46.7°, C2-C7 SVA>57.6°, CTPA>7.8°, and C2S<60.4) met. QALYs were calculated from NDI improvement in this analysis. <h3>RESULTS</h3> There were 132 patients included in the study. Of these, 24 had surgery in 2013, 52 in 2014, 24 in 2015, and 32 in 2016. There was a trend downward with respect to 2-year total cost over the years (2013: $42,754; 2016: $39,155), as the trendline showed a yearly decrease of $2,753 (R2=0.6966). Concurrently, there was an increase EQ5D improvement after 2-year (2013: 0.0113; 2016: 0.0697). This resulted in an increase of 0.0172 per year in QALYs gained at 2-year (R2=0.8109) and a 0.2358 increase per year in QALYs gained at LE (R2=0.8533). Thus, there was a decrease in cost per QALY at 2-year of $6,057 per year (R2=0.0497) and at LE of $67,478 per year (R2=06588). Total cost at 2-year for those with Distal Junctional Kyphosis was $98,357 vs $59,129 for non-DJK; cost per QALY was $46,932 vs $28,571, respectively. Sub-analysis indicated increasing risk criteria were associated with major complications (2.085 [1.057-4.114], p=0.034) and reoperations (4.267 [1.604-11.352], p=0.004). Cost increased by $7,167 per factor (R2=0.9901). Patients with fewer factors had greater NDI improvement than high risk (1: -24.6; 2: -14.8; 3: -15.6; 4: -3.8, p=0.023). This translated to low cost per QALY at 2-year for 1 factor ($45,787), with worse cost efficiency per factor (2: $90,117; 3: $103,543; 4: $525,472). <h3>CONCLUSIONS</h3> Between 2013 and 2017, total cost for cervical deformity surgery decreased – possibly due to complication and risk reductions – while EQ5D improvement has increased, leading to improved cost effectiveness. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

233. Development of risk stratification predictive models for cervical deformity surgery

BACKGROUND CONTEXT As the field of corrective cervical deformity (CD) surgery progresses, surgeons continue to take on more challenging cases. In order to minimize suboptimal postoperative outcomes it is important to develop a tool that allows for proper preoperative risk stratification. PURPOSE Develop individualized predictive models for identification of risk-factors that lead to the development of major complications, revisions, and unplanned reoperation. STUDY DESIGN/SETTING Retrospective cohort study of a prospective adult cervical deformity database. PATIENT SAMPLE A total of 105 CD patients. OUTCOME MEASURES Major complications (prolonged hospitalization, invasive intervention, prolonged or permanent morbidity, death within 1 year[1Y]), unplanned revision or reoperation after CD surgery within 1Y, HRQOL (NDI, mJOA, EQ5D). METHODS CD patients (cervical kyphosis >10°, coronal scoliosis >10°, cSVA >4cm, TS-CL >10°, or CBVA >25°) ≥18 years old with complete baseline (BL), 1Y HRQoL and radiographic data. Patients were stratified into two groups based on their outcome from surgery: revision (Rev) and major complication (MC). Descriptive analysis identified cohort demographics, radiographic parameters and surgical details. Univariate analysis of preoperative and surgical factors was conducted to determine associations with any of the two outcomes. Stepwise logistic regressions identified surgical, radiographic, and HRQL factors that were associated with Rev or MC. Decision tree analysis established cut-offs for predictive variables. RESULTS A total of 105 CD patients were included (61.6yrs, 67%F, BMI: 28.4kg/m2, CCI: 0.96±1.3). Surgical details: 7.6± 3.7 levels fused; mean EBL of 816 mL. By surgical approach, 45.71% had a posterior approach, 35.24% combined approach, and 19.05% anterior approach. Radiographically at baseline, patients presented with: PT: 18.9± 11.3; PI: 53.0±11.2; PI-LL: -0.45±17.2; SVA: -4.3±66.8, TS-CL: 37.9 ±20.2; cSVA: 38.4±19.9. Postoperatively, 20 patients experienced a MC and 17 patients underwent a subsequent rev. instrumentation location (LIV: 1.1[1.0-1.3] and UIV: 1.5[1.1-2.1]) was significantly associated with undergoing a rev after index surgery (all p C3, LIV>T3, C2-T3 SVA 57.6°, CTPA>7.8°, and C2S 59.2°, C2-C7 SVA > 69.1°, C2-T3 SVA 4.25, surgical invasiveness and posterior osteotomies (AUC:0.83). CONCLUSIONS Major adverse events were not uncommon following adult cervical deformity correction. Risk stratification models were developed to predict with high accuracy the occurrence of these common significant postoperative events. Revisions were predicted with an accuracy of 80% using a predominance of radiographic variables, while the occurrence of other major complications was also predicted with high reliability utilizing additional baseline HRQoL data and surgical factors. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Recurrent Proximal Junctional Kyphosis: Incidence, Risk Factors, Revision Rates, and Outcomes at 2-Year Minimum Follow-up.

Retrospective comparative cohort study. Assess the incidence, risk factors, and outcomes of recurrent proximal junctional kyphosis (r-PJK) in PJK revision patients. Several studies have identified the incidence and risk factors for PJK after primary surgery. However, few studies have reported on PJK recurrence after revision for PJK. A multicenter database of patients who underwent PJK revision surgery with minimum 2-year follow-up was analyzed. Demographic, operative, and radiographic outcomes were compared in patients with r-PJK and patients without recurrence no-Proximal Junctional Kyphosis (n-PJK). Postoperative Scoliosis Research Society-22r, Short Form-36, and Oswestry Disability Index were compared. Preoperative and most recent spinopelvic, cervical, and cervicothoracic radiographic parameters were compared. Univariate and multivariate analyses were used to determine r-PJK risk factors. A predictive model was formulated based on our logistic regression analysis. A total of 70 patients met the inclusion criteria with an average follow-up of 21.8 months. The mean age was 66.3 ± 9.4 and 80% of patients were women. Before revision, patients had a proximal junctional angle angle of -31.7° ± 15.9°. The rate of recurrent PJK was 44.3%. Logistic regression showed that pre-revision thoracic pelvic angle (odds ratio [OR]: 1.060 95% confidence interval [CI] 1.002; 1.121; P = 0.042) and prerevision C2-T3 sagittal vertical axis (SVA; OR: 1.040 95% CI [1.007; 1.073] P = 0.016) were independent predictors of r-PJK. Classification with these parameters yielded an accuracy of 72.7%, precision of 80.6%, and recall of 73.5%. When examining correction, or change in alignment with revision surgery, we found that change in SVA (OR: 0.981 95% CI [0.968; 0.994] P = 0.005) was the only predictor of r-PJK with accuracy of 66.7%, precision of 74.2%, and recall of 69.7%. Patients after PJK revision surgery had a recurrence rate of 44%. Logistic regression based on the prerevision variables showed that prerevision thoracic pelvic angle and prerevision C2-T3 SVA were independent predictors of r-PJK. 4.

Predicting the combined occurrence of poor clinical and radiographic outcomes following cervical deformity corrective surgery.

Cervical deformity (CD) correction is clinically challenging. There is a high risk of developing complications with these highly complex procedures. The aim of this study was to use baseline demographic, clinical, and surgical factors to predict a poor outcome following CD surgery. The authors performed a retrospective review of a multicenter prospective CD database. CD was defined as at least one of the following: cervical kyphosis (C2-7 Cobb angle > 10°), cervical scoliosis (coronal Cobb angle > 10°), C2-7 sagittal vertical axis (cSVA) > 4 cm, or chin-brow vertical angle (CBVA) > 25°. Patients were categorized based on having an overall poor outcome or not. Health-related quality of life measures consisted of Neck Disability Index (NDI), EQ-5D, and modified Japanese Orthopaedic Association (mJOA) scale scores. A poor outcome was defined as having all 3 of the following categories met: 1) radiographic poor outcome: deterioration or severe radiographic malalignment 1 year postoperatively for cSVA or T1 slope-cervical lordosis mismatch (TS-CL); 2) clinical poor outcome: failing to meet the minimum clinically important difference (MCID) for NDI or having a severe mJOA Ames modifier; and 3) complications/reoperation poor outcome: major complication, death, or reoperation for a complication other than infection. Univariate logistic regression followed by multivariate regression models was performed, and internal validation was performed by calculating the area under the curve (AUC). In total, 89 patients with CD were included (mean age 61.9 years, female sex 65.2%, BMI 29.2 kg/m2). By 1 year postoperatively, 18 (20.2%) patients were characterized as having an overall poor outcome. For radiographic poor outcomes, patients' conditions either deteriorated or remained severe for TS-CL (73% of patients), cSVA (8%), horizontal gaze (34%), and global SVA (28%). For clinical poor outcomes, 80% and 60% of patients did not reach MCID for EQ-5D and NDI, respectively, and 24% of patients had severe symptoms (mJOA score 0-11). For the complications/reoperation poor outcome, 28 patients experienced a major complication, 11 underwent a reoperation, and 1 had a complication-related death. Of patients with a poor clinical outcome, 75% had a poor radiographic outcome; 35% of poor radiographic and 37% of poor clinical outcome patients had a major complication. A poor outcome was predicted by the following combination of factors: osteoporosis, baseline neurological status, use of a transition rod, number of posterior decompressions, baseline pelvic tilt, T2-12 kyphosis, TS-CL, C2-T3 SVA, C2-T1 pelvic angle (C2 slope), global SVA, and number of levels in maximum thoracic kyphosis. The final model predicting a poor outcome (AUC 86%) included the following: osteoporosis (OR 5.9, 95% CI 0.9-39), worse baseline neurological status (OR 11.4, 95% CI 1.8-70.8), baseline pelvic tilt > 20° (OR 0.92, 95% CI 0.85-0.98), > 9 levels in maximum thoracic kyphosis (OR 2.01, 95% CI 1.1-4.1), preoperative C2-T3 SVA > 5.4 cm (OR 1.01, 95% CI 0.9-1.1), and global SVA > 4 cm (OR 3.2, 95% CI 0.09-10.3). Of all CD patients in this study, 20.2% had a poor overall outcome, defined by deterioration in radiographic and clinical outcomes, and a major complication. Additionally, 75% of patients with a poor clinical outcome also had a poor radiographic outcome. A poor overall outcome was most strongly predicted by severe baseline neurological deficit, global SVA > 4 cm, and including more of the thoracic maximal kyphosis in the construct.

38. Prioritization of realignment associated with superior clinical outcomes for surgical cervical deformity patients

BACKGROUND CONTEXT Many patients are unable to undergo a major cervical deformity corrective surgery due to deformity severity, age, comorbidities, and overall frailty status. In order to optimize quality of life in patients with cervical deformity, there may be alignment targets to be prioritized. PURPOSE To prioritize the cervical parameter targets for alignment. STUDY DESIGN/SETTING Retrospective review of a multicenter prospective cervical deformity database. PATIENT SAMPLE Seventy-seven patients undergoing cervical deformity (CD) corrective surgery. OUTCOME MEASURES Cervical regional alignment parameters: cervical sagittal vertical axis(cSVA), cervical lordosis(CL), T1 Slope minus CL(TS-CL), chin brow vertical angle(CBVA), McGregor's slope(MGS), C2-T3 plumb line(C2-T3 SVA), C2-T3 angle, C2 Slope. Health-related quality of life measures: NDI. METHODS Included:CD patients (C2-C7 Cobb>10°, CL>10°, cSVA>4cm, or CBVA>25°) with full baseline (BL) and 1-year (1Y) radiographic parameters and NDI scores; patients with cervical or cervicothoracic Primary Driver Ames type. Patients with BL Ames classified as low CD for both parameters of cSVA( RESULTS Seventy-seven CD patients included (62.1yrs, 64%F, 28.8kg/m2). Average CCI: 0.94, 7% current smokers. By approach, anterior: 19.4%, posterior: 41.6%, combined approach: 39%. Mean anterior levels fused: 3.5, posterior: 8.3, total: 7.5. Average op time: 553.1min; mean EBL: 1128.1ccs. 41.6% met MCID for NDI. A backwards linear regression model including radiographic differences as predictors from BL to 1 year for meeting MCID for NDI demonstrated an R2 of 0.820 (p=0.032) included TS-CL, cSVA, MGS, C2SS, C2-T3 angle, C2-T3 SVA, CL. By primary Ames driver, 67.5% of patients were categorized as C, and 32.5% as CT. Ratios of change in predictors for MCID NDI patients (BL -1Y) for C driver patients: 260.8% MGS, 140.3% CL, 121.2% C2-T3 angle, 49.6% C2 slope, 41.1% cSVA, 20.5% TS-CL, 3.1%C2-T3 SVA. While correction in CT driver patients included: 168.7% CL, 93% MGS, 70.8% C2-T3 angle, 31.1% cSVA, 27.5% C2 slope, 24.9% TS-CL, 13.7% C2-T3 SVA. The ratios were not significant between the two groups(p>0.050). Decision tree analysis determined cut-offs for radiographic change, prioritizing in the following order (based upon ordinal regression values): a correction ≤42.5°C2-T3 angle (OR: 5.667[1.074-29.891], p=0.041), -31.76°C2 slope (OR: 3.2 [0.852-12.026], p=0.085), >-11.57mm cSVA (OR: 3.185[1.137-8.917], p=0.027), >-2.16° MGS (OR: 2.724[0.971-7.636], p=0.057). CONCLUSIONS Certain ratios of correction of cervical parameters contribute to improving neck disability. Specific cut-offs of radiographic differences from baseline to 1 year were found prioritizing C2-T3 angle, followed by cervical lordosis, C2 slope, C2-C7 plumb line, and McGregor's slope, all strongly associated with meeting the minimal clinically important difference for the neck disability index score. Prioritizing these radiographic alignment parameters will optimize patient-reported outcomes for patients undergoing cervical deformity surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Sagittal alignment of the cervical spine in the setting of adolescent idiopathic scoliosis.

OBJECTIVEThe goal of this study was to investigate the impact of thoracic and lumbar alignment on cervical alignment in patients with adolescent idiopathic scoliosis (AIS).METHODSEighty-one patients with AIS who had a Cobb angle > 40° and full-length spine radiographs were included. Radiographs were analyzed using dedicated software to measure pelvic parameters (sacral slope [SS], pelvic incidence [PI], pelvic tilt [PT]); regional parameters (C1 slope, C0-C2 angle, chin-brow vertical angle [CBVA], slope of line of sight [SLS], McRae slope, McGregor slope [MGS], C2-7 [cervical lordosis; CL], C2-7 sagittal vertical axis [SVA], C2-T3, C2-T3 SVA, C2-T1 Harrison measurement [C2-T1 Ha], T1 slope, thoracic kyphosis [TK], lumbar lordosis [LL], and PI-LL mismatch); and global parameters (SVA). Patients were stratified by their lumbar alignment into hyperlordotic (LL > 59.7°) and normolordotic (LL 39.3° to 59.7°) groups and also, based on their thoracic alignment, into hypokyphotic (TK < -33.1°) and normokyphotic (TK -33.1° to -54.9°) groups. Finally, they were grouped based on their global alignment into either an anterior-aligned group or a posterior-aligned group.RESULTSThe lumbar hyperlordotic group, in comparison to the normolordotic group, had a significantly larger LL, SS, PI (all p < 0.001), and TK (p = 0.014) and a significantly smaller PI-LL mismatch (p = 0.001). Lumbar lordosis had no influence on local cervical parameters.The thoracic hypokyphotic group had a significantly larger PI-LL mismatch (p < 0.002) and smaller T1 slope (p < 0.001), and was significantly more posteriorly aligned than the normokyphotic group (-15.02 ± 8.04 vs 13.54 ± 6.17 [mean ± SEM], p = 0.006). The patients with hypokyphotic AIS had a kyphotic cervical spine (cervical kyphosis [CK]) (p < 0.001). Furthermore, a posterior-aligned cervical spine in terms of C2-7 SVA (p < 0.006) and C2-T3 SVA (p < 0.001) was observed in the thoracic hypokyphotic group.Comparing patients in terms of global alignment, the posterior-aligned group had a significantly smaller T1 slope (p < 0.001), without any difference in terms of pelvic, lumbar, and thoracic parameters when compared to the anterior-aligned group. The posterior-aligned group also had a CK (-9.20 ± 1.91 vs 5.21 ± 2.95 [mean ± SEM], p < 0.001) and a more posterior-aligned cervical spine, as measured by C2-7 SVA (p = 0.003) and C2-T3 SVA (p < 0.001).CONCLUSIONSAlignment of the cervical spine is closely related to thoracic curvature and global alignment. In patients with AIS, a hypokyphotic thoracic alignment or posterior global alignment was associated with a global cervical kyphosis. Interestingly, upper cervical and cranial parameters were not statistically different in all investigated groups, meaning that the upper cervical spine was not recruited for compensation in order to maintain a horizontal gaze.

Cervical Alignment Changes in Patients Developing Proximal Junctional Kyphosis Following Surgical Correction of Adult Spinal Deformity.

Proximal junctional kyphosis (PJK) following adult spinal deformity (ASD) surgery is a well-documented complication, but associations between radiographic PJK and cervical malalignment onset remain unexplored. To study cervical malalignment in ASD surgical patients that develop PJK. Retrospective review of prospective multicenter database. Inclusion: primary ASD patients (≥5 levels fused, upper instrumented vertebra [UIV] at T2 or above, and 1-yr minimum follow-up) without baseline cervical deformity (CD), defined as ≥2 of the following criteria: T1 slope minus cervical lordosis < 20°, cervical sagittal vertical axis < 4 cm, C2-C7 cervical lordosis < 10°. PJK presence (<10° change in UIV and UIV + 2 kyphosis) and angle were identified 1 yr postoperative. Propensity score matching between PJK and nonPJK groups controlled for baseline alignment. Preoperative and 1-yr postoperative cervical alignment were compared between PJK and nonPJK patients. One hundred sixty-three patients without baseline CD (54.9 yr, 83.9% female) were included. PJK developed in 60 (36.8%) patients, with 27 (45%) having UIV above T7. PJK patients had significantly greater baseline T1 slope in unmatched and propensity score matching comparisons (P < .05). At 1 yr postoperative, PJK patients had significantly higher T1 slope (P < .001), C2-T3 Cobb (P = .04), and C2-T3 sagittal vertical axis (P = .02). New-onset CD rate in PJK patients was 15%, and 16.5% in nonPJK patients (P > .05). Increased PJK magnitude was associated with increasing T1 slope and C2-T3 SVA (P < .05). Patients who develop PJK following surgical correction of ASD have a 15% incidence of development of new-onset CD. Patients developing PJK following surgical correction of ASD tend to have an increased preoperative T1 slope. Increased progression of C2-T3 Cobb angle and C2-T3 SVA are associated with development of PJK following surgical correction of thoracolumbar deformity.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P83. Development of a novel cervical deformity surgical invasiveness index

BACKGROUND CONTEXT A surgical invasiveness index exists for general spine surgery and adult spinal deformity, but a cervical deformity (CD) index has not been developed. PURPOSE The aim of this study was to develop a novel surgical invasiveness index for CD surgery that incorporates CD-specific parameters. STUDY DESIGN/SETTING Retrospective review of a multicenter prospective CD database. PATIENT SAMPLE Eighty-five CD patients with complete baseline demographic, clinical, and surgical details and 1-year data. OUTCOME MEASURES Cervical and global alignment parameters: cSVA, cervical lordosis, C2 slope, C2-T3 angle, C2-T3 SVA, TS-CL, PI-LL, PT, and SVA. METHODS CD was defined as at least one of the following: C2–C7 Cobb>10°, CL>10°, cSVA>4 cm, CBVA>25°. Consensus from experienced spine and neurosurgeons selected weightings for each variable that went into the invasiveness index. Linear regression was used to predict operative time, EBL, and length of stay using the newly developed CD-specific invasiveness index, controlling for age, sex, and Charlson Comorbidity Index score. Binary logistic regression predicted high operative time (>338 minutes), high EBL (>600 cc), or high length of stay (>5 days) based on the median values of operative time, EBL and length of stay. Significance was set at P RESULTS Eighty-five CD patients were included (61.35±10.7years, 65.9% female). The variables included in the newly developed CD invasiveness index with their corresponding weightings were: history of prior cervical surgery (3), ACDF (2 per level), corpectomy (4 per level), levels fused (1 per level), implants (1 per level), posterior decompression (2 per level), Smith–Peterson osteotomy (2 per level), three column osteotomy (8 per level), fusion to upper cervical spine (2), absolute change in TS-CL, cSVA, T4-T12 thoracic kyphosis and SVA from baseline to 1-year follow-up. The newly developed CD invasiveness index was a significant independent predictor of estimated blood loss (R2=0.132, P=.042). This CD-specific index was also a significant independent predictor of operative time (R2=0.171, P=.004). CD-specific invasiveness index strongly predicted a hospital length of stay greater than 5days (R2=0.310, P CONCLUSIONS Extended length of stay, operative time, and high blood loss werestrongly predicted by the newly developed CD invasiveness index, incorporating surgical factors and radiographic parameters clinically relevant for patients undergoing cervical deformity corrective surgery.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P102. A comparison of three different positioning techniques on surgical corrections and postoperative alignment in cervical deformity (CD) surgery

BACKGROUND CONTEXT Cervical deformity surgery involves various methods to achieve sagittal alignment objectives. Instrumentation type, surgical approaches, interbody grafts and osteotomies can be used to achieve surgical goals. Furthermore, patient positioning may impact ultimate sagittal correction. To our knowledge, the effect of different patient positioning methods on sagittal alignment correction after cervical deformity surgery has not been studied. PURPOSE The purpose was to examine the differences in sagittal alignment correction between three positioning methods in cervical deformity surgery. STUDY DESIGN/SETTING Retrospective review or multicenter prospective database. PATIENT SAMPLE Eighty of 153 eligible subjects from a prospective cervical deformity database. OUTCOME MEASURES Differences in cervical sagittal radiographic corrections between three types of patient positioning used in cervical deformity surgery. METHODS A review of a prospective multicenter cervical deformity database was performed. Inclusion criteria were: pre- and post-op lateral radiographs, intraop positioning data, posterior approach (with and without anterior) and UIV at C6 or above. Patients with Grade 5, 6 or 7 osteotomies were excluded. Positioning groups were Mayfield (M), Bivector traction (BV) and Halo (H). Pre- and post-op sagittal parameters were analyzed. Segmental changes were analyzed using the Fergusson method. Significance defined as a=0.05. RESULTS Eighty (58% female) of 153 potential subjects were included. Mean age was 60.6±10.5 (range 31–83) and mean BMI 29.2±8.0 (17–58). Positioning groups were 48M, 20BV, and 12H. No differences existed in baseline demographics, baseline cervical sagittal radiographic parameters, primary vs revision, UIV levels or postoperative alignment between groups. Mean cohort postoperative C2-C7 lordosis was 7.8°±14 and C2-C7 SVA was 34.1 mm±15. BV had the largest number of levels fused (BV 13.8, H 8.9, M 8.9, P .05). No difference existed for pre-op sagittal flexibility between groups (P>.05). There was no difference in postop alignment parameters between groups (P>.05). A trend toward smaller postop C2-T3 SVA (mm) was observed in H, however, did not reach significance (H 58, BV 73, M 84, P=.053) Examining all groups, the majority of segmental correction was achieved at C4-5-6 (Mean 6.9°±11) with no difference between groups (P>.05). M had larger segmental correction at C3-4-5 than H and BV, but not significantly different (M 7.4°, H 1.9°, BV 0.6°, P=.054). Alternatively, BV had significantly more segmental correction at C7-T1-T2 (BV 4.2°, M 0.3°, −1.7°, P .05). CONCLUSIONS Patient positioning does not appear to affect the amount of correction or ultimate alignment in cervical deformity procedures. All positioning methods achieve the majority of segmental correction through C4-5-6 and BV appears to have the largest corrective abilities at the cervico-thoracic junction. These findings are important to consider when planning cervical deformity procedures.

Clinical and radiographic presentation and treatment of patients with cervical deformity secondary to thoracolumbar proximal junctional kyphosis are distinct despite achieving similar outcomes: Analysis of 123 prospective CD cases

CD development secondary to PJK was recently documented in adult spinal deformity patients after surgical correction for thoracolumbar ASD. This study analyzes surgical management of patients with CD secondary to proximal junctional kyphosis (PJK) versus patients with primary CD. Retrospective review of multicenter cervical deformity (CD) database. CD defined as at least one of the following: C2–C7 coronal Cobb > 10°, cervical lordosis (CL) > 10°, cervical sagittal vertical axis (cSVA) > 4cm, CBVA > 25°. Patients were grouped into those with PJK (UIV +2 < −10°) prior to cervical surgery versus who don’t (Non-PJK). Independent t-tests and chi-squared tests compared radiographic, clinical, and surgical metrics between PJK and non-PJK groups. Of 123 eligible CD patients, 26(21.1%) had radiographic PJK prior to cervical surgery. PJK patients had significantly greater T2–T12 thoracic kyphosis (−58.8° vs −45.0°, p = 0.002), cSVA (49.1 mm vs 38.9 mm, p = 0.020), T1 Slope (42.6° vs 28.4°, p < 0.001), TS-CL (44.1° vs 35.6°, p = 0.048), C2-T3 SVA (98.8 mm vs 75.8 mm, p = 0.015), C2 Slope (45.4° vs 36.0°, p = 0.043), and CTPA (6.4° vs 4.6°, p = 0.005). Comparing their surgeries, the PJK group had significantly more levels fused (10.7 vs 7.4, p = 0.01). There was significantly greater blood loss in PJK patients (1158 ± 1063vs 738 ± 793 cc, p = 0.028); operative time, surgical approach, and BMP-2 use were similar (all p > 0.05). PJK patients experienced higher rates of complications 30 and 90 days post-operatively (23.1% vs. 5.2%, p = 0.004; 30.8% vs. 19.6%, p = 0.026), and more instrumentation failure 30 days postoperatively (7.8% vs. 1.0%, p = 0.004). Patients with cervical deformity secondary to PJK had worse baseline CD, despite no differences in HRQL or demographics. Surgical correction of CD associated with PJK required more invasive surgery and had higher complication rates than non-PJK patients, despite achieving similar clinical outcomes.

Preoperative Cervical Hyperlordosis and C2–T3 Angle are Correlated to Increased Risk of Post-Op Sagittal Spinal Pelvic Malalignment in Adult Spinal Deformity Patients at 2-Year Follow-Up

Introduction Cervical deformity (CD) is prevalent among patients with adult spinal deformity (ASD). The effect of baseline cervical alignment and achieving optimal TL alignment in ASD surgery is unclear. This study assesses the relationship between preoperative cervical spinal parameters and global alignment following thoracolumbar ASD surgery at 2-year follow-up. Patients and Methods Using a multicenter prospective database of surgical patients with ASD, we included patients with 2-year follow-up and cervical X-rays. SRS-Schwab sagittal modifiers (PT, GA, and PI–LL) were assessed at 2-year postoperative as either normal (0) or abnormal (“ + ” or “ + +”). Patients were classified in the aligned group (AG) or maligned group (MG) if all the three sagittal modifiers were normal or abnormal, respectively. Patients were assessed for CD based on the following criteria: C2–C7 SVA &gt; 4 cm, C2–C7 SVA &lt; 4 cm, cervical kyphosis (CL &gt; 0), cervical lordosis (CL &lt; 0), any deformity (C2C7 SVA &gt; 4 cm or CL &gt; 0), and both CD (C2C7 SVA &gt; 4 cm and CL &gt; 0). Univariate testing was performed using t test or chi-square test, looking at the following pre-op parameters: CD, C2–C7 SVA, C2–T3 SVA, CL, T1S, T1S–CL, C2–T3 angle, LL, TK, PT, C7–S1 SVA, and PI–LL. Results A total of 184 patients met initial inclusion criteria with 70 in the AG and 34 in MG. Pre-op, patients in the MG had a higher cervical lordosis (11.7 vs. 4.9, p = 0.03), higher C2–T3 angle (13.59 vs. 4.9 p = 0.01), and higher PT ( p &lt; 0.0001), higher SVA ( p &lt; 0.0001), and higher PI–LL ( p &lt; 0.0001) compared with the AG. Interestingly, the prevalence of CD at baseline was similar for both the groups: MG and AG. There was no statistically significant difference in the amount of improvement over 2 years on the ODI or the SF-36 PCS. Conclusion Patients with 2-year sagittal TL malalignment also have preoperative sagittal TL malalignment and concomitant cervical hyperlordosis as a compensatory mechanism to maintain horizontal gaze. Cervical radiographs suggestive of cervical hyperlordosis should be followed up with complete standing radiographs to asses for sagittal TL malalignment.