Pelvic Incidence And Lumbar Lordosis Research Articles

Outcomes of Surgical Treatment for Patients With Mild Scoliosis and Age-Appropriate Sagittal Alignment With Minimum 2-Year Follow-up.

The goal of this study was to determine if patients with mild scoliosis and age-appropriate sagittal alignment have favorable outcomes following surgical correction. Retrospective review of a prospective, multicenter adult spinal deformity database. Inclusion criteria: operative patients age ≥18 years, and preoperative pelvic tilt, mismatch between pelvic incidence and lumbar lordosis (PI-LL), and C7 sagittal vertical axis all within established age-adjusted thresholds with minimum 2-year follow-up. Health-related quality of life (HRQoL) scores: Oswestry Disability Index (ODI), 36-item Short Form health survey (SF-36), Scoliosis Research Society-22R (SRS22R), back/leg pain Numerical Rating Scale and minimum clinically important difference (MCID)/substantial clinical benefit (SCB). Two-year and preoperative HRQoL radiographic data were compared. Patients with mild scoliosis (Mild Scoli, Max coronal Cobb 10°-30°) were compared to those with larger curves (Scoli). One hundred fifty-one patients included from 667 operative patients (82.8% women; average age, 56.4 ± 16.2 years). Forty-two patients (27.8%) included in Mild Scoli group. Mild Scoli group had significantly worse baseline leg pain, ODI, and physical composite scores (p < 0.02). Mean 2-year maximum coronal Cobb angle was significantly improved compared to baseline (p < 0.001). All 2-year HRQoL measures were significantly improved compared to (p < 0.001) except mental composite score, SRS activity and SRS mental for the Mild Scoli group (p > 0.05). From the mild Scoli group, 36%-74% met either MCID or SCB for the HRQoL measures. Sixty-four point three percent had minimum 1 complication, 28.6% had a major complication, 35.7% had reoperation. Mild scoliosis patients with age-appropriate sagittal alignment benefit from surgical correction, decompression, and stabilization at 2 years postoperative despite having a high complication rate.

Risk Factors for Adjacent Segment Disease in Short Segment Lumbar Interbody Fusion-A Case Series.

Adjacent segment disease (ASD) is a common problem after lumbar spinal fusions. Ways to reduce the rates of ASD are highly sought after to reduce the need for reoperation. To find predisposing factors of ASD after lumbar interbody fusions, especially in mismatch of pelvic incidence and lumbar lordosis (PI-LL). We conducted a retrospective cohort study of all patients undergoing lumbar interbody fusions of less than 4 levels from June 2015 to July 2020 with at least 1 year of follow-up and in those who had obtained postoperative standing X-rays. We found 243 patients who fit inclusion and exclusion criteria. Fourteen patients (5.8%) developed ASD, at a median of 24 months. Postoperative lumbar lordosis was significantly higher in the non-ASD cohort (median 46.4° ± 1.4° vs 36.9° ± 3.6°, P < .001), pelvic tilt was significantly lower in the non-ASD cohort (16.0° ± 0.66° vs 20.3° ± 2.4°, P = .002), PI-LL mismatch was significantly lower in the non-ASD cohort (5.28° ± 1.0° vs 17.1° ± 2.0°, P < .001), and age-appropriate PI-LL mismatch was less common in the non-ASD cohort (34 patients [14.8%] vs 13 [92.9%] of patients with high mismatch, P < .001). Using multivariate analysis, greater PI-LL mismatch was predictive of ASD (95% odds ratio CI = 1.393-2.458, P < .001) and age-appropriate PI-LL mismatch was predictive of ASD (95% odds ratio CI = 10.8-970.4, P < .001). Higher PI-LL mismatch, both age-independent and when adjusted for age, after lumbar interbody fusion was predictive for developing ASD. In lumbar degenerative disease, correction of spinopelvic parameters should be a main goal of surgical correction.

Surgical outcome of minimal invasive oblique lateral interbody fusion with percutaneous pedicle screw fixation in the treatment of adult degenerative scoliosis

Oblique lateral interbody fusion is performed for lumbar spinal restoration and stabilization, without extensive paraspinal muscle damage or massive bleeding. This study aimed to confirm the radiological and clinical outcomes of minimally invasive oblique lateral interbody fusion (OLIF) with percutaneous pedicle screw fixation (PPSF) as treatment for adult degenerative lumbar scoliosis. Medical records of 40 patients with degenerative lumbar spinal deformities who underwent selective OLIF and PPSF at our hospital between April 2018 and February 2021 were retrospectively reviewed. The study population comprised 7 male and 33 female patients aged 55-79 years. Standing radiography was performed, and the coronal cobb angle, distance between the C7 plumb line and central sacral vertical line, sagittal vertical axis, pelvic tilt, lumbar lordosis (LL), pelvic incidence (PI), and difference between PI and LL (PI-LL) were measured. Coronal scoliosis was defined as a lumbar coronal plane curve of > 15°. All patients achieved statistically significant improvements in coronal and sagittal alignment. The coronal cobb angle was corrected from 18.82° to 11.52°, and the central sacral vertical line was reduced from 18.30 mm to 15.47 mm. The sagittal vertical axis was significantly reduced from 45.95 mm to 32.72 mm. In contrast, the pelvic tilt and LL were minimally changed. For subgroup analyses, patients were divided into the convex and concave groups according to the direction of coronal curve correction. Vertebral body rotation was superior in the convex group than in the concave group. Furthermore, we checked for asymmetric facet degeneration at the upper instrumented vertebra (UIV) level at 1 year postoperatively. Of the 22 patients who underwent more than 3 level fusion surgery, 8 patients were confirmed the postoperative asymmetric facet degeneration in above UIV. Minor complications occurred in 16 patients, who recovered without any problems. Revision surgery was not performed in all cases. Minimally invasive OLIF with PPSF has a lower risk of complications and favorable surgical outcomes in patients with adult degenerative lumbar scoliosis. Access from the convex side is advantageous for the correction of the rotated vertebra. Extending the UIV level to the neutral vertebra can reduce the occurrence of postoperative asymmetric facet degeneration.

49. The impact of sagittal alignment on disability decreases after surgery as other factors become more influential: series of 925 patients with two-year follow-up

<h3>BACKGROUND CONTEXT</h3> The relationship of sagittal malalignment to outcomes has been emphasized in adult spinal deformity (ASD) surgery and it is known that sagittal parameters have some correlation to HRQOL measures overall. However, the specific relationship of HRQOL to postop sagittal alignment and changes in the strength of the relationship from preop to postop for deformity surgery has not been well defined. <h3>PURPOSE</h3> To determine how postop health-related quality of life (HRQOL) correlates to sagittal alignment. <h3>STUDY DESIGN/SETTING</h3> Retrospective analysis of a large prospective multicenter ASD database. <h3>PATIENT SAMPLE</h3> This study included 925 ASD patients. <h3>OUTCOME MEASURES</h3> HRQOL: Oswestry Disability Index (ODI), Short-Form-36 (SF-36), and Scoliosis Research Society-22r (SRS-22r). Radiographic sagittal alignment thresholds for C7-S1 sagittal vertical axis (SVA), pelvic tilt (PT), mismatch between pelvic incidence and lumbar lordosis (PI-LL). <h3>METHODS</h3> Adult (=18yrs), Cobb angle=20°, SVA=5cm, PT=25°, and/or thoracic kyphosis=60°, 2-yr follow up. Pts were grouped by having met 2/3 of the sagittal alignment thresholds (SVA,PT, and/or PI-LL) at 2 years postop for either the SRS-Schwab values (+SS0) or age-adjusted values (+AGE). The age-adjusted values were calculated within +/-10 years of their actual age. The groups –SS0 and –AGE were patients who didn't meet 2/3 of the SRS-Schwab or the age-adjusted values, respectively. Baseline/2-year HRQOL were evaluated via linear regression for all groups based on 2-year correction. <h3>RESULTS</h3> Total 925 pts, mean age 60.1±14.2yrs, 602(65.1%)+SS0, 323(35.9%)-SS0, 199(21.5%)+AGE, and 283(30.6%)–AGE pts. The remaining age-adjusted pts were either overcorrected or did not have 2/3 sagittal values matched (n=443). All pts had significant improvement in all HRQOL at 2 years and for each of the subgroups (p <0.001 for all). The overall baseline R2 values for all pts for SVA, PI-LL and PT with ODI were (0.110, 0.072, 0.043, respectively) and at 2 years they were lower (0.049, 0.016, 0.008, respectively). Of the pts with pelvic fixation (n=635,68.6%), the same 2-year R2 values increased slightly but were still very weak (0.058, 0.028, 0.021, respectively). Of the pts who developed PJK, the 2-year R2 values were (PJK: 0.007, 0.024, 0.004, noPJK: 0.057, 0.017, 0.006, respectively). This same trend of low values was observed in +/-SS0 and +/-AGE pts. However, the R2 for 2-year ODI vs MCS, SRS appearance, and SRS mental, increased postop (0.19, 0.43, 0.22, respectively) compared with preop (0.17, 0.25, 0.17, respectively). <h3>CONCLUSIONS</h3> Sagittal alignment correlates weakly with preop HRQOL and postop HRQOL is improved. Preop SVA explains only 11% of preop ODI scores based on the R2 value and this decreases postop to 5%. After alignment correction, other patient factors become increasingly important such as the relationship between ODI and SRS appearance, SRS mental, and MCS. More work is necessary to better understand the postop HRQOL relationships including the possibility of a better measurement tool for surgical success. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Cervical Deformity Correction Fails to Achieve Age-Adjusted Spinopelvic Alignment Targets.

To assess whether surgical cervical deformity (CD) patients meet spinopelvic age-adjusted alignment targets, reciprocal, and lower limb compensation changes. Retrospective review. CD was defined as C2-C7 lordosis >10°, cervical sagittal vertical angle (cSVA) >4 cm, or T1 slope minus cervical lordosis (TS-CL) >20°. Inclusion criteria were age >18 years and undergoing surgical correction with complete baseline and postoperative imaging. Published formulas were used to create age-adjusted alignment target for pelvic tilt (PT), pelvic incidence and lumbar lordosis (PI-LL), sagittal vertical angle (SVA), and lumbar lordosis and thoracic kyphosis (LL-TK). Actual alignment was compared with age-adjusted ideal values. Patients who matched ±10-year thresholds for age-adjusted targets were compared with unmatched cases (under- or overcorrected). A total of 120 CD patients were included (mean age, 55.1 years; 48.4% women; body mass index, 28.8 kg/m2). For PT, only 24.4% of patients matched age-adjusted alignment, 51.1% overcorrected for PT, and 24.4% undercorrected. For PI-LL, only 27.6% of CD patients matched age-adjusted targets, with 49.4% overcorrected and 23% undercorrected postoperatively. Forty percent of patients matched age-adjusted target for SVA, 41.3% overcorrected, and 18.8% undercorrected. CD patients who had worsened in TS-CL or cSVA postoperatively displayed increased TK (-41.1° to -45.3°, P = 1.06). With lower extremity compensation, CD patients decreased in ankle flexion angle postoperatively (6.1°-5.5°, P = 0.036) and trended toward smaller sacrofemoral angle (199.6-195.6 mm, P = 0.286) and knee flexion (2.6° to -1.1°, P = 0.269). In response to worsening CD postoperatively, patients increased in TK and recruited less lower limb compensation. Almost 75% of CD patients did not meet previously established spinopelvic alignment goals, of whom a subset of patients were actually made worse off in these parameters following surgery. This finding raises the question of whether we should be looking at the entire spine when treating CD.

Correlation between the Severity of the Lumbar Degenerative Disease and Sagittal Spinopelvic Alignment.

Objective To evaluate the impact of the severity of lumbar degenerative disease (LDD) on sagittal spinopelvic alignment. Methods In total, 130 patients (mean age: 57 years; 75% female) with LDD-associated low-back pain were prospectively included. The severity of the LDD was defined by the following findings on anteroposterior and lateral lumbar spine radiographs: osteophytosis; loss of of height of the intervertebral disc; terminal vertebral plate sclerosis; number of affected segments; deformities; and objective instability. The disease was classified as follows: grade 0–absence of signs of LDD in the lumbar spine; grade I – signs of LDD in up to two segments; grade II – three or more segments involved; grade III – association with scoliosis, spondylolisthesis, or laterolisthesis. Spinopelvic radiographic parameters, including pelvic incidence (PI), lumbar lordosis (LL), discrepancy between the PI and LL (PI-LL), pelvic tilt (PT), and sagittal vertical axis (SVA), were analyzed according to the LDD grades. Results The radiographic parameters differed according to the LDD grades; grade-III patients presented higher SVA ( p = 0.001) and PT ( p = 0.0005) values, denoting greater anterior inclination of the trunk and pelvic retroversion when compared to grade-0 andgrade-I subjects. In addition, grade-III patients had higher PI-LL values, which indicates loss of PI-related lordosis, than grade-I subjects ( p = 0.04). Conclusion Patients with more severe LDD tend to present greater spinopelvic sagittal misalignment compared to patients with a milder disease.

Relationship Between Age-Related Spinopelvic Sagittal Alignment and Low Back Pain in Adults of Population-Based Cohorts: The ROAD Study

PurposeThe demand for surgical correction in elderly patients with adult spinal deformity (ASD) has recently increased with the growth of the aging population. Age-related changes in spinopelvic sagittal alignment have been recently reported; thus, sagittal realignment should consider age-related changes. This study aimed to investigate the relationship between age-specific sagittal spinopelvic radiographic parameters and low back pain (LBP) to support the establishment of age-specific realignment targets for patients with ASD.Materials and MethodsA population-based cohort consisting of 1461 subjects (466 men and 995 women) was used. The participants were divided into five groups based on their age: (1) younger than 50 years, (2) 50–59 years, (3) 60–69 years, (4) 70–79 years, and (5) 80 years and older. Standing lateral whole-spine radiographs were assessed to measure lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), and sagittal vertical axis (SVA). In addition, all participants were asked if they had LBP or not, using the following question: “Have you experienced LBP on most days during the past month and/or now?”.ResultsThe crucial parameter associated with LBP was the mismatch between PI and LL (PI-LL). The mean values of all the radiographic parameters increased with age. PI-LL and PT reached 11.5° and 25.6°, respectively, for women without LBP in the super-aged group (age >80 years), which did not lie in the range of optimal values reported in the previous literature.ConclusionA new optimal age-related target may be needed for the management of patients with ASD.

Outcomes of Surgical Treatment for 138 Patients With Severe Sagittal Deformity at a Minimum 2-Year Follow-up: A Case Series.

Operative treatment of adult spinal deformity (ASD) can be very challenging with high complication rates. It is well established that patients benefit from such treatment; however, the surgical outcomes for patients with severe sagittal deformity have not been reported. To report the outcomes of patients undergoing surgical correction for severe sagittal deformity. Retrospective review of a prospective, multicenter ASD database. Inclusion criteria: operative patients age≥18, sagittal vertical axis (SVA)≥15 cm, mismatch between pelvic incidence and lumbar lordosis (PI-LL)≥30°, and/or lumbar kyphosis≥5° with minimum 2 yr follow-up. Health-related quality of life (HRQOL) scores including minimal clinically important difference (MCID)/substantial clinical benefit (SCB), sagittal and coronal radiographic values, demographic, frailty, surgical, and complication data were collected. Comparisons between 2 yr postoperative and baseline HRQOL/radiographic data were made. P<.05 was significant. A total of 138 patients were included from 502 operative patients (54.3% Female, Average (Avg) age 63.3±11.5 yr). Avg operating room (OR) time 386.2±136.5 min, estimated blood loss (EBL) 1829.8±1474.6 cc. A total of 71(51.4%) had prior fusion. A total of 89.9% were posterior fusion only. Mean posterior levels fused 11.5±4.1. A total of 44.9% had a 3-column osteotomy. All 2 yr postoperative radiographic parameters were significantly improved compared to baseline (P<.001 for all). All 2yr HRQOL measures were significantly improved compared to baseline (P<.004 for all). A total of 46.6% to 73.8% of patients met either MCID/SCB for all HRQOL. A total of 74.6% of patients had at least 1 complication, 11.6% had 4 or more complications, 33.3% had minimum 1 major complication, and 42(30.4%) had a postop revision. Patients with severe sagittal malalignment benefit from surgical correction at 2 yr postoperative both radiographically and clinically despite having a high complication rate.

Spine Treatment Appraisal Report (STAR): Patient-Reported Outcomes Following Short-Segment Lumbar Fusion: Does Pelvic Incidence and Lumbar Lordosis (PI-LL) Mismatch Matter?

Divi SN, Kepler CK, Hilibrand AS, et al. Patient Outcomes Following Short-segment Lumbar Fusion Are Not Affected by PI-LL Mismatch. Clin Spine Surg. Mar 1 2021;34(2):73-77.

At What Point Should the Thoracolumbar Region Be Addressed in Patients Undergoing Corrective Cervical Deformity Surgery?

Retrospective cohort study. The aim of this study was to investigate the impact of cervical to thoracolumbar ratios on poor outcomes in cervical deformity (CD) corrective surgery. Consideration of distal regional and global alignment is a critical determinant of outcomes in CD surgery. For operative CD patients, it is unknown whether certain thoracolumbar parameters play a significant role in poor outcomes and whether addressing such parameters is warranted. Included: surgical CD patients (C2-C7 Cobb >10°, cervical lordosis [CL] >10°, C2-C7 sagittal vertical axis (cSVA) >4 cm, or chin-brow vertical angle >25°) with baseline and 1-year data. Patients were assessed for ratios of preop cervical and global parameters including: C2 Slope/T1 slope, T1 slope minus C2-C7 lordosis (TS-CL)/mismatch between pelvic incidence and lumbar lordosis (PI-LL), cSVA/sagittal vertical axis (SVA). Deformity classification ratios of cervical (Ames-ISSG) to spinopelvic (SRS-Schwab) were investigated: cSVA modifier/SVA modifier, TS-CL modifier/PI-LL modifier. Cervical to thoracic ratios included C2-C7 lordosis/T4-T12 kyphosis. Correlations assessed the relationship between ratios and poor outcomes (major complication, reoperation, distal junctional kyphosis (DJK), or failure to meet minimal clinically important difference [MCID]). Decision tree analysis through multiple iterations of multivariate regressions assessed cut-offs for ratios for acquiring suboptimal outcomes. A total of 110 CD patients were included (61.5 years, 66% F, 28.8 kg/m2). Mean preoperative radiographic ratios calculated: C2 slope/T1 slope of 1.56, TS-CL/PI-LL of 11.1, cSVA/SVA of 5.4, CL/thoracic kyphosis (TK) of 0.26. Ames-ISSG and SRS-Schwab modifier ratios: cSVA/SVA of 0.1 and TS-CL/PI-LL of 0.35. Pearson correlations demonstrated a relationship between major complications and baseline TS-CL/PI-LL, Ames TS-CL/Schwab PI-LL modifiers, and the CL/TK ratios (P < 0.050). Reoperation had significant correlation with TS-CL/PI-LL and cSVA/SVA ratios. Postoperative DJK correlated with C2 slope/T1 slope and CL/TK ratios. Not meeting MCID for Neck Disability Index (NDI) correlated with CL/TK ratio and not meeting MCID for EQ5D correlated with Ames TS-CL/Schwab PI-LL. Consideration of cervical to global alignment is a critical determinant of outcomes in CD corrective surgery. Key ratios of cervical to global alignment correlate with suboptimal clinical outcomes. A larger cervical lordosis to TK predicted postoperative complication, DJK, and not meeting MCID for NDI.Level of Evidence: 4.

277. Is adjacent segment disease following instrumented short lumbosacral fusion influenced by postoperative sagittal alignment?

BACKGROUND CONTEXT Adjacent segment disease (ASD) is a common manifestation following lumbar fusion, potentially requiring revision of the construct. While several risk factor for the condition have been identified it is unclear what role sagittal imbalance following fusion plays in the development of ASD. Sagittal imbalance, when measured as mismatch between pelvic incidence and lumbar lordosis (PI-LL), has been associated with poorer clinical outcomes following lumbar surgery; however, it is unclear whether higher PI-LL contributes to ASD in the short lumbosacral fusion population. PURPOSE The aim of this study was to 1) determine the incidence of ASD among patients undergoing short lumbosacral fusion; 2) to evaluate if patients who went on to develop ASD have higher degree of PI-LL compared to those without (controls); 3) following subgroup analysis, determine if the relation between PI-LL and ASD was affected by length of fusion. STUDY DESIGN/SETTING Single institutional retrospective cohort study PATIENT SAMPLE A total of 126 patients undergoing instrumented short lumbosacral fusion were included OUTCOME MEASURES Radiographic evidence of postoperative ASD; Initial Postoperative PI-LL among ASD patients and controls METHODS Patients who underwent short instrumented lumbosacral fusion between the years of 2008 to 2019 at our institution were selected for the study. In addition, patients must have had a minimum of 2-year radiographic follow-up to meet inclusion criteria. Only elective cases for degenerative lumbar pathology were included; cases involving spinal infection, trauma, or malignancy were excluded. Postoperative PI-LL was measured using initial one-month postoperative standing radiographs. Subgroup analysis was also performed after separating the main cohort into 3 separate populations corresponding to the following fusion lengths: 5 segment (L2-S1), 4 segment (L3-S1), and 3 segment (L4-S1) fusions. PI-LL was compared between patients who went on to develop radiographic evidence of ASD and those who did not (controls) using student t-test. Significance was defined as p RESULTS Following application of inclusion and exclusion criteria, 126 patients with a mean age of 61.44 ± 12.22 years were selected for the study. Radiographic evidence of ASD was present in 59% of patients (n=74), with a mean time to ASD of 21.52 ± 21.74 months. No difference (p=0.781) was seen in initial postoperative PI-LL between ASD patients (11.42 ± 7.62) and controls (11.87 ± 9.94) in the main cohort. Following subgroup analysis, incidence of ASD was 57% (24/42) in L4-S1 fusions, 62% (29/47) in L3-S1 fusion, and 57% (21/37) among L2-S1 fusions. Postoperative rates of ASD were similar among the 3 cohorts (p=0.787). No difference was observed PI-LL between ASD patient and controls in the L4-S1 (10.74 ± 8.35 vs 8.89 ± 9.02, p=0.500), L3-S1 (11.69 ± 7.77 vs 11.24 ± 8.94, p=0.860), and L2-S1 fusion cohorts (11.81 ± 6.82 vs 15.98 ± 11.14, p=0.203). CONCLUSIONS No significant difference in PI-LL was observed between patients who went on to develop ASD and those who did not. Likewise, sagittal alignment was similar in each fusion length subgroup. Sagittal imbalance measured by PI-LL may not have a significant impact on the development of ASD following instrumented short lumbosacral fusion. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

25. The collective influence of lumbopelvic mismatch and proportional shape on clinical outcomes and proximal junctional kyphosis following adult spinal deformity corrective surgery

BACKGROUND CONTEXT The age-adjusted alignment ideal alignment was proposed in order reduce the occurrence of proximal junctional kyphosis (PJK) in an adult spinal deformity (ASD) population. The normative postoperative age ideal value for the mismatch between pelvic incidence and lumbar lordosis (PI-LL) has yet to be related to the global alignment and proportion (GAP) score postop proportionality. PURPOSE To assess the impact of normative age-adjusted PI-LL and proportionality via GAP score on postoperative patient-reported outcomes. STUDY DESIGN/SETTING Retrospective review of single-surgeon adult spinal deformity (ASD) database PATIENT SAMPLE 140 ASD patients. OUTCOME MEASURES Health-related quality-of-life (HRQLs); SRS-22r; PJK. METHODS ASD patients with baseline (BL) and 2-year postoperative (2Y) radiographic and HRQL data were included. Age-adjusted correction groups generated at postoperative follow-up for actual alignment compared to age-adjusted values for PI-LL-adjusted ideal values (matched, overcorrected, undercorrected). GAP Score in the literature includes the four parameters, and an age factor to formulate a sagittal plane score out of 13 (proportional, moderately disproportional [MD], severely disproportional [SD]). GAP improvement scores were noted as less at 2Y compared to BL. Patients were grouped by age-adjusted and 2Y GAP results: Match PI-LL/Proportional GAP, Match PI-LL/Disproportional GAP, Unmatch PI-LL/Proportional GAP, Unmatch PI-LL/Disproportional GAP. Means comparison and chi-squared ANOVA analyses assessed the outcomes between age-adjusted and GAP groups. RESULTS Included: 140 ASD patients (55.5±16.4 years, 81% female, 25.2±4.7kg/m2). At BL, mean sacral slope: 30.7°, pelvic tilt: 23°, pelvic incidence: 53.5°, PI-LL: 13.3°, SVA: 61.6 mm, and L1-S1: 40.4°. BL GAP proportionality: 17.8% proportional, 27.1% MD, 55% SD. PI-LL by baseline GAP proportionality groups: -6.4° Proportional, -4.6° MD, 26.8° SD, p CONCLUSIONS Collectively over or undercorrecting in age-adjusted mismatch pelvic incidence and lumbar lordosis and becoming disproportional in spinal shape at 2 years led to increased postoperative proximal junctional kyphosis and significantly worse patient-reported outcomes. Surgeons should be wary of the double mal-correction when utilizing these complex realignment schemas. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

217. Outcomes of surgical treatment for patients with mild scoliosis and age appropriate sagittal alignment with minimum 2-year follow up

BACKGROUND CONTEXT Operative treatment of adult spinal deformity (ASD) can be very challenging with high complication rates. Despite these challenges it's well established that pts benefit from such treatment. However, the surgical outcomes for pts with mild scoliosis and age appropriate sagittal alignment have not been reported. PURPOSE To determine if patients (pts) with mild scoliosis and age appropriate sagittal alignment have favorable outcomes following surgical correction. STUDY DESIGN/SETTING Retrospective review of a prospective, multicenter ASD database. PATIENT SAMPLE ASD patients: operative pts age≥18, and all preoperartive pelvic tilt (PT), mismatch between pelvic incidence and lumbar lordosis (PI-LL), and C7 sagittal vertical axis (SVA) within established age adjusted parameters with minimum 2-year follow up. A subanalysis for pts with max coronal cobb angle 10-30° (mild scoli) was done. OUTCOME MEASURES Health-related quality of life (HRQOL) scores: Oswestry Disability Index (ODI), Short form-36(SF36), Scoliosis Research Society (SRS22), back/leg pain numerical rating scale (NRS) and minimum clinically important difference (MCID)/substantial clinical benefit (SCB). Radiographic values: max coronal cobb angle, coronal C7 plumb line, PT, PI-LL, thoracic kyphosis (TK), SVA. Demographic, frailty, surgical and complications data were collected. METHODS Two-year and baseline HRQOL/radiographic data were compared. RESULTS A total of 103 pts were included from 667 operative patients (89.3% female, avg age 59.8±13.1yrs). Of the 103 pts, 29 (28.2%) had max preop coronal cobb angle 10-30°. Two-year max coronal cobb angle and C7 coronal plumb were significantly improved compared to baseline (p CONCLUSIONS Pts with mild scoliosis and sagittal alignment within age appropriate parameters benefit from surgical correction at 2 years postop both radiographically and clinically including 81.5% meeting MCID for SRS pain despite having high complication rates. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

The incidence and risk factors for adjacent vertebral fractures in community-dwelling people with prevalent vertebral fracture: the 3rd and 4th survey of the ROAD study.

This study aimed to clarify the incidence and risk factors of adjacent vertebral fractures (AVFs)-fractures adjacent to a prevalent vertebral fracture (VF)-using an established population-based cohort from the ROAD study. Among the 1213 participants who underwent whole-spine radiography in ROAD's third (2012-2013, the baseline) and fourth surveys (2015-2016, the follow-up), 66 (12 men, 54 women) had at least one VF at the baseline. VF and AVF were determined radiographically using Genant's semi-quantitative (SQ) method, where VF was SQ ≥ 2 and AVF was a one-level cranial or caudal vertebra with an SQ grade one or more higher at the follow-up. An interviewer-administered questionnaire was applied, and anthropometric measurements and bone mineral density (BMD) measurements at the lumbar spine and femoral neck were performed. Sagittal imbalance of the spine was defined as a mismatch between pelvic incidence and lumbar lordosis (PI-LL) of > 20°. Multivariate logistic regression analyses were performed to identify risk factors for AVF. AVF occurred in 12 participants (1 man, 11 women). The annual incidence of AVF was estimated at 6.1%/year. Logistic regression analyses revealed that lower BMD at the femoral neck and PI-LL > 20° were risk factors for AVF. The annual incidence of AVF in a general population with prevalent VF was 6.1%/year. In addition, lower BMD at the femoral neck and PI-LL > 20° were risk factors for AVF.

Surgical Treatment of Flat Back Syndrome With Anterior Hyperlordotic Cages.

Traditional correction for flat back syndrome is performed with a posterior-based surgery or combined approaches in revision cases. To evaluate outcome from anterior surgery with the use of hyperlordotic cages (HLCs) in patients with flat back syndrome. All patients operated with or without prior posterior lumbar surgery were studied. Pre- to postoperative sagittal alignment was analyzed. Radiographic parameters were analyzed including T1 pelvic angle (T1PA), sagittal vertical axis (SVA), pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL), sacral slope (SS), pelvic incidence and lumbar lordosis (PI-LL), and T4-12TK. All 50 patients (mean age of 58 yr, 72% female with mean body mass index of 28) demonstrated significant radiographic alignment difference in their spinopelvic and global parameters from pre- to postoperative standing: LL (-37.04° vs -59.55°, P<.001), SS (35.12 vs 41.13, P<.001), PI-LL (23.55 vs 6.46), T4-12 TK (30.59 vs 41.67), PT (28.22 vs 22.13), SVA in mm (80.94 vs 37.39), and T1PA (28.70° vs 18.43°, P<.001). Using linear regression analysis, predicted pre- to postoperative change in standing LL corresponded to a pre- to postoperative changes in standing PI-LL mismatch, T1PA, TK, SS, PT, and SVA (R2=0.59, 0.38, 0.25, 0.16, 0.12, and 0.17, respectively). Five degrees of pre- to postoperative change in T1PA translates to -4.15° change in LL. Anterior surgery with HLCs followed by posterior instrumentation is an effective technique to treat flat back syndrome. HLCs are effective to maximize LL up to 30°, which is equivalent in magnitude to a pedicle subtraction osteotomy, but associated with less blood loss, quicker recovery, lower complications, and good surgical outcome.

194. Outcomes of surgical treatment for 138 patients with severe sagittal deformity at a minimum two-year follow-up

BACKGROUND CONTEXT The operative treatment of adult spinal deformity (ASD) can be very technically challenging with high complication rates. Despite these challenges it is well established that patients ultimately benefit from such treatment. However the surgical outcomes for patients with severe sagittal deformity have not been reported. PURPOSE To investigate whether patients with severe sagittal deformity have favorable outcomes following surgical correction. STUDY DESIGN/SETTING Retrospective review of a prospective, multicenter adult spinal deformity (ASD) database. PATIENT SAMPLE Inclusion criteria: operative patients with age ≥18, SVA ≥15cm, PI-LL ≥30°, and/or lumbar kyphosis ≥5° with minimum 2-yr follow-up. OUTCOME MEASURES Health-related quality of life (HRQOL) scores included: Oswestry Disability Index (ODI), Short Form-36 (SF36), Scoliosis Research Society (SRS22), back/leg pain numerical rating scale (NRS) and minimum clinically important difference (MCID)/substantial clinical benefit (SCB) for pts eligible to meet them. Radiographic values included: max coronal cobb angle, coronal C7 plumb line, pelvic tilt (PT), mismatch between pelvic incidence and lumbar lordosis (PI-LL), thoracic kyphosis (TK), C7 sagittal vertical axis (SVA). Demographic, frailty, surgical, and complications data were also collected. METHODS Comparisons between 2-yr postop and baseline HRQOL/radiographic data were made. P RESULTS A total of 138 pts were included (54.3% Female, ave age 63.3±11.5yrs). Ave baseline frailty score was 4.1±1.4 indicating the pt to befrail. Ave OR time 386.2±136.5min, EBL 1829.8±1474.6cc. 71 (51.4%) of the pts had a prior fusion; 89.9% posterior fusion only, 9.4% combined anterior-posterior approach. Mean number posterior levels fused 11.5±4.1. 44.9% had a 3-column osteotomy and 68.8% had interbody fusion. All 2-yr postop radiographic parameters were significantly improved compared to baseline (p 0.05). All 2-yr HRQOL measures were significantly improved compared to baseline (p CONCLUSIONS Pts with severe sagittal malalignment benefit from surgical correction at 2-yrs postop both radiographically and clinically despite having a high complication rate. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

P83. Predictive modeling for pseudarthrosis performance benchmarking in 404 patients with a minimum two-year follow up

BACKGROUND CONTEXT In the past, averages from published studies have been used for performance benchmarking. However, in practice and in large studies, usually only a small subset of patients fall within the “average” and therefore the average may not provide a valid benchmark rate. One can overperform or underperform the average and still attain the predicted performance benchmark. Predictive modeling can be used to help set performance standards based on a large number of variables including patients' specific factors, procedure details, use of osteogenic products, site specific variations and many others. This study attempts to use predictive modeling for pseudarthrosis performance benchmarking as a proof of concept in ASD surgery. PURPOSE To use predictive modeling for performance benchmarking in high-volume centers and demonstrate that it is more appropriate than simply using averages. STUDY DESIGN/SETTING Retrospective review of a prospective, multicenter ASD database from 11 different sites PATIENT SAMPLE ASD operative patients with age ≥18, Coronal Cobb ≥ 20deg, SVA ≥5cm, PT≥25deg, and/or thoracic kyphosis (TK) ≥ 60deg with min 2-year follow-up. Exclusion criteria: having a revision for any indication other than pseudo in order to reduce confounding of potential pseudo as a result of the revision surgery. OUTCOME MEASURES HRQOL scores: Oswestry Disability Index (ODI), Short form-36 (SF36), Scoliosis Research Society (SRS22), back/leg pain numerical rating scale (NRS). Radiographic values: max coronal cobb angle, coronal C7 plumb line, pelvic tilt (PT), mismatch between pelvic incidence and lumbar lordosis (PI-LL), thoracic kyphosis (TK), C7 sagittal vertical axis (SVA). Posterior fusion was graded to determine if pseudo has occurred within 2 years postoperative. Demographic, frailty, surgical including BMP and complications data were also collected. METHODS A prior validated and published pseudo predictive model has been constructed from 336 ASD patients with an accuracy of 91.3% and an AUC of 0.94 using 21 out of 82 total variables listed above. This model was deployed with an updated set of patients to determine the predicted pseudo rate for each individual surgical site. Actual pseudo rates of the 11 contributing surgical sites were compared to the predicted values as a means to assess for performance benchmarking. RESULTS A total of 403 patients were included (80.1% Female, avg age 57.9±14.9 years) from a total of 502 operative patients with 99 excluded for having a revision for indication other than pseudo. A total of 129 (32.0%) had pseudo by 2 years. The overall pseudo rates per year were the following: 2008-20.0%, 2009-37.7%, 2010-31.4%, 2011-29.3%, 2012-36.7%, 2013-32.0%, 2014-26.6%, 2015-38.1%. Six sites had actual rates above the overall rate of 32% with 5 sites below. However, the predicted rates varied according to each site and included rates above/below the overall rate. All of the actual rates were larger than the predicted rates except for 4 sites in which the actual and predicted rates were the same. CONCLUSIONS The pseudo rate varied per year and per site. Predictive modeling was able to provide a customized pseudoarthosis rate for each site considering multiple variables allowing for performance benchmarking instead of the average. Even though a site was above the overall average rate, they may be predicted to have a higher rate given the type of patients being treated or procedures done at that site. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Physiological variations in the sagittal spine alignment in an asymptomatic elderly population

BACKGROUND CONTEXTSagittal plane alignment is of crucial importance for the treatment of spinal deformities. When planning corrective strategies, spine surgeons need to refer to normative parameters’ ranges which characterize the alignment in the asymptomatic population. Changes are known to occur with age. For the Caucasian population, the reference ranges are extensively documented for the young and middle-aged adults. In contrast, only a few studies have evaluated individuals in advanced age (>60 years) and in groups of limited numbers of subjects (less than 50). PURPOSETo describe the normative parameter ranges of sagittal spine alignment in a large population of asymptomatic elderly subjects. STUDY DESIGN/SETTINGMonocentric, prospective, cross-sectional study. PATIENT SAMPLEOne hundred sixty asymptomatic elderly volunteers (age>60 years, Caucasian heritage), consecutively enrolled. OUTCOME MEASURESSagittal parameters of spine and pelvis: thoracic kyphosis (TK); lumbar lordosis (LL); sacral slope (SS); pelvic incidence (PI); pelvic tilt (PT); sagittal vertical axis (SVA); T1 pelvic angle (TPA); mismatch between PI and LL (PI-LL); Roussouly classification of the lumbopelvic profile. METHODSEach subject underwent one radiographic scan, performed in standing position with EOS low-dose system (EOS Imaging, Paris, France). The radiographic images were processed with sterEOS software allowing identification of the anatomical parameters and the presence of scoliosis. SVA, TPA, and the lumbopelvic profile were manually measured in the lateral images. The results were compared to previous studies describing younger adult populations. The study was supported by the Italian Ministry of Health in the amount of $15,000. The authors declare that there are no conflicts of interests. RESULTSOverall, the average values of the spinopelvic parameters were the followings: TK, 55±14°; LL, 57±12°; PI, 55±11°; SS, 38±10°; PT, 16±7°. The average PI-LL, SVA, and TPA was −3±11°, 25±32 mm, and 14.6±7.4°, respectively. TK, TPA, and SVA were found increasing with age. As for classification of the lumbopelvic profile, 16% of subjects were excluded because they were considered not to belong to any of the Roussouly types. In the classified subjects, the distribution was similar to that of younger adults. Asymptomatic scoliosis (average Cobb angle, 22±7°) was identified in 27% of individuals. CONCLUSIONSThe ranges of values pointed out differences compared to younger adults and represent an important resource for spine surgeons in planning the surgical correction of spinal deformities. The characteristic changes occurring with age, as well as the observed presence of mild or moderate asymptomatic scoliosis, should be carefully taken into account. The classification of the lumbopelvic profile based on the Roussouly scheme revealed some limitations, although similar frequencies were identified compared to younger adults.

Technical Consideration for TLIF Cage Retrieval and Deformity Correction With Anterior Interbody Fusion in Lumbar Revision Surgeries

IntroductionSymptomatic pseudoarthrosis after transforaminal lumbar interbody fusion (TLIF) could result in sagittal malalignment. Revision posterior surgery with TLIF cage removal poses a challenge intraoperatively. The authors have proposed salvage anterior approach for cage removal and have discussed unique experience with the correction in their deformity patients. MethodsAll patients with symptoms of clinical deformity or symptomatic pseudoarthrosis operated from January of 2012 to February of 2018 were included in the study. TLIF cage removal followed by anterior lumbar interbody fusion (ALIF) surgery was performed in all patients. Radiographic sagittal parameters including thoracic kyphosis (TK; T4–T12), sagittal vertical axis (SVA), T1 pelvic angle (TPA), lumbar lordosis (LL), the mismatch between pelvic incidence (PI) and LL (PI-LL), sacral slope (SS), pelvic tilt (PT), and PI were analyzed. Results6 patients (mean age of 57 years, 83% female) underwent TLIF retrieval through anterior approach and ALIF with hyperlordotic cages (HLCs), followed by posterior spinal fusion surgery. Described technique entails use of tailored instruments with sequential gentle distraction of end plates with TLIF spreader could facilitate in the cage removal. Mean number of interbody levels fused pre as well as post were 1.5. The radiographic sagittal parameters from preoperative versus postoperative standing were as follows: T4–T12 TK, 16° vs. 37.6°; LL, −25° vs. −47.6°; PT, 36° vs. 26°; PI-LL, 35° vs. 12.4°; SVA, 12° vs. 5.6°; and TPA, 44° vs. 25°, with p<.001. Mean number of instrumented level fused were 8.1. Using linear regression analysis, change from pre-to postoperative standing in LL predicted pre-to postoperative change in SVA and TPA for global correction (R= −0.30 and −0.80, respectively). ConclusionsAnterior approach is a suitable technique for TLIF cage removal while preserving the end plates for subsequent optimal interbody fusion at the index level in symptomatic pseudoarthrosis patients or those with clinical deformity. ALIF with HLCs with or without Ponte osteotomy can restore segmental and overall sagittal alignment.

Impact of sagittal imbalance correction on clinical outcomes in patients undergoing MIS-TLIF for LSS

ObjectiveIn the present study, we aimed to evaluate the effect of sagittal imbalance correction on clinical outcomes in patients undergoing single-segment minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) for lumbar spinal stenosis (LSS). Patients and methodsA total of 114 LSS patients with a minimum 2-year follow-up were included. Preoperative and final follow-up sagittal parameters were determined. Sagittal imbalance was defined as a sagittal vertical axis (SVA) ≥40 mm. Patients were divided into balanced group (group A: preoperative SVA <40 mm) and imbalanced group (group B: preoperative SVA ≥40 mm), and group B was further divided into recovered group (postoperative SVA <40 mm) and unrecovered group (postoperative SVA ≥40 mm). Visual analog scale (VAS) score, Japanese Orthopaedic Association (JOA) score and Oswestry Disability Index (ODI) were used to assess clinical outcomes. ResultsThe incidence of preoperative sagittal imbalance in LSS patients was 36.0% (41/114). A large mismatch between pelvic incidence and lumbar lordosis (PI-LL) was a risk factor for sagittal imbalance. After 2-year follow-up, sagittal imbalance was normalized in 65.9% of patients. Single- segment MIS-TLIF led to a significant decrease in SVA, pelvic tilt (PT) and PI-LL, as well as a significant increase in LL, thoracic kyphosis (TK) and sacral slope (SS) in both group A and group B. Preoperatively, the VAS, JOA and ODI scores were significantly poorer in patients with sagittal imbalance compared with those without sagittal imbalance. After MIS-TLIF, all clinical outcomes improved significantly. However, there was no significant difference in postoperative VAS, JOA and ODI scores between the group A and group B. In addition, there was no significant difference in postoperative VAS, JOA, and ODI scores between the recovered group and unrecovered group. ConclusionsA significant proportion of LSS patients with preoperative sagittal malalignment had a compensatory mechanism rather than a structural malalignment, while single-segment MIS-TLIF could effectively improve sagittal imbalance at 2-year follow-up. However, we found no correlation between the improvements of sagittal imbalance and 2- year clinical outcomes. Reconstruction of sagittal balance might not be the main goal of single-segment MIS-TLIF for LSS, and did not affect its clinical results at two-year follow-up.