Faculty Bibliography

BACKGROUND:The Roussouly, SRS-Schwab, and Global Alignment and Proportion (GAP) classifications define alignment by spinal shape and deformity severity. The efficacy of different surgical approaches and techniques to successfully achieve these goals is not well understood. PURPOSE/OBJECTIVE:Identify the impact of surgical approach and/or technique on meeting complex realignment goals in adult spinal deformity (ASD) corrective surgery. STUDY DESIGN/SETTING/METHODS:Retrospective study. MATERIALS AND METHODS/METHODS:Included patients with ASD fused to pelvis with 2-year data. Patients were categorized by: (1) Roussouly: matching current and theoretical spinal shapes, (2) improving in SRS-Schwab modifiers (0, +, ++), and (3) improving GAP proportionality by 2 years. Analysis of covariance and multivariable logistic regression analyses controlling for age, levels fused, baseline deformity, and 3-column osteotomy usage compared the effect of different surgical approaches, interbody, and osteotomy use on meeting realignment goals. RESULTS:A total of 693 patients with ASD were included. By surgical approach, 65.7% were posterior-only and 34.3% underwent anterior-posterior approach with 76% receiving an osteotomy (21.8% 3-column osteotomy). By 2 years, 34% matched Roussouly, 58% improved in GAP, 45% in SRS-Schwab pelvic tilt (PT), 62% sagittal vertical axis, and 70% pelvic incidence-lumbar lordosis. Combined approaches were most effective for improvement in PT [odds ratio (OR): 1.7 (1.1-2.5)] and GAP [OR: 2.2 (1.5-3.2)]. Specifically, anterior lumbar interbody fusion (ALIF) below L3 demonstrated higher rates of improvement versus TLIFs in Roussouly [OR: 1.7 (1.1-2.5)] and GAP [OR: 1.9 (1.3-2.7)]. Patients undergoing pedicle subtraction osteotomy at L3 or L4 were more likely to improve in PT [OR: 2.0 (1.0-5.2)] and pelvic incidence-lumbar lordosis [OR: 3.8 (1.4-9.8)]. Clinically, patients undergoing the combined approach demonstrated higher rates of meeting SCB in Oswestry Disability Index by 2 years while minimizing rates of proximal junctional failure, most often with an ALIF at L5-S1 [Oswestry Disability Index-SCB: OR: 1.4 (1.1-2.0); proximal junctional failure: OR: 0.4 (0.2-0.8)]. CONCLUSIONS:Among patients undergoing ASD realignment, optimal lumbar shape and proportion can be achieved more often with a combined approach. Although TLIFs, incorporating a 3-column osteotomy, at L3 and L4 can restore lordosis and normalize pelvic compensation, ALIFs at L5-S1 were most likely to achieve complex realignment goals with an added clinical benefit and mitigation of junctional failure.

BACKGROUND:Postoperative reciprocal changes (RC) in the cervical spine associated with varying factors of proximal junctional kyphosis (PJK) following fusions of the thoracopelvic spine are poorly understood. PURPOSE/OBJECTIVE:Explore reciprocal changes in the cervical spine associated with varying factors (severity, progression, patient age) of PJK in patients undergoing adult spinal deformity (ASD) correction. PATIENTS AND METHODS/METHODS:Retrospective review of a multicenter ASD database. INCLUSION/METHODS:ASD patients > 18 y/o, undergoing fusions from the thoracic spine (UIV: T6-T12) to the pelvis with two-year radiographic data. ASD was defined as: Coronal Cobb angle ≥ 20°, Sagittal Vertical Axis ≥ 5 cm, Pelvic Tilt ≥ 25°, and/or Thoracic Kyphosis ≥ 60°. PJK was defined as a ≥ 10° measure of the sagittal Cobb angle between the inferior endplate of the UIV and the superior endplate of the UIV + 2. Patients were grouped by mild (M; 10°-20°) and severe (S; > 20°) PJK at one year. Propensity Score Matching (PSM) controlled for CCI, age, PI and UIV. Unpaired and paired t test analyses determined difference between RC parameters and change between time points. Pearson bi-variate correlations analyzed associations between RC parameters (T4-T12, TS-CL, cSVA, C2-Slope, and T1-Slope) and PJK descriptors. RESULTS:284 ASD patients (UIV: T6: 1.1%; T7: 0.7%; T8: 4.6%; T9: 9.9%; T10: 58.8%; T11: 19.4%; T12: 5.6%) were studied. PJK analysis consisted of 182 patients (Mild = 91 and Severe = 91). Significant difference between M and S groups were observed in T4-T12 Δ1Y(- 16.8 v - 22.8, P = 0.001), TS-CLΔ1Y(- 0.6 v 2.8, P = 0.037), cSVAΔ1Y(- 1.8 v 1.9, P = 0.032), and C2 slopeΔ1Y(- 1.6 v 2.3, P = 0.022). By two years post-op, all changes in cervical alignment parameters were similar between mild and severe groups. Correlation between age and cSVAΔ1Y(R = 0.153, P = 0.034) was found. Incidence of severe PJK was found to correlate with TS-CLΔ1Y(R = 0.142, P = 0.049), cSVAΔ1Y(R = 0.171, P = 0.018), C2SΔ1Y(R = 0.148, P = 0.040), and T1SΔ2Y(R = 0.256, P = 0.003). CONCLUSIONS:Compensation within the cervical spine differed between individuals with mild and severe PJK at one year postoperatively. However, similar levels of pathologic change in cervical alignment parameters were seen by two years, highlighting the progression of cervical compensation due to mild PJK over time. These findings provide greater evidence for the development of cervical deformity in individuals presenting with proximal junctional kyphosis.

STUDYDESIGN/METHODS:Retrospective cohort study of a prospectively collected multi-center adult spinal deformity (ASD) database. OBJECTIVE:To compare staged procedures to same-day interventions and identify the optimal time interval between staged surgeries for treatment of ASD. BACKGROUND:Surgical intervention for ASD is invasive and complex procedure that surgeons often elect to perform on different days (staging). Yet, there remains a paucity of literature on the timing and effects of the interval between stages. METHODS:ASD patients with two-year (2Y) data undergoing an anterior/posterior (A/P) fusion to the ilium were included. Propensity score matching (PSM) was performed for number of levels fused, number of interbody devices, surgical approaches, number of osteotomies/three-column osteotomy (3CO), frailty, Oswestry Disability Index (ODI), Charlson Comorbidity Index (CCI), revisions, sagittal vertical axis (SVA), pelvic incidence-lumbar lordosis (PI-LL), and UIV to create balanced cohorts of Same-Day and Staged surgical patients. Staged patients were stratified by intervening time-period between surgeries, using quartiles. RESULTS:176 PSM patients were included. Median interval between A/P staged procedures was 3 days. Staged patients had greater operative time and lower ICU stays postop (P<0.05). At 2Y, staged compared to same day showed a greater improvement in T1 slope - cervical lordosis (TS-CL), C2 sacral slope (C2SS), and SRS-Schwab SVA (P<0.05). Staged patients had higher rates of minimal clinically-important difference (MCID) for 1Y SRS-Appearance and 2Y physical component summary (PCS) scores. Assessing different intervals of staging, patients at the 75th percentile interval showed greater improvement in 1Y SRS Pain and Total postop as well as SRS Activity, Pain, Satisfaction, and Total scores (P<0.05) compared to patients in lower quartiles. Compared to the 25th percentile, patients reaching the 50th percentile interval were associated with increased odds of improvement in Global Alignment and Proportion (GAP) score proportionality (9.3[1.6-53.2], P=0.01). CONCLUSIONS:This investigation is among the first to compare multicenter staged and same day surgery anterior/posterior adult spinal deformity patients fused to ilium using propensity-matching. Staged procedures resulted in significant improvement radiographically, reduced ICU admissions, and superior patient reported outcomes compared to same day procedures. An interval of at least three days between staged procedures is associated with superior outcomes in terms of GAP score proportionality.

STUDY DESIGN/METHODS:Retrospective review. OBJECTIVE:To assess the factors contributing to durability of surgical results following adult spinal deformity surgery. SUMMARY OF BACKGROUND/BACKGROUND:Factors contributing to the long-term sustainability of ASD correction are currently undefined. METHODS:Operative ASD patients with preop(BL) and 3-year(3Y) postop radiographic/HRQL data were included. At 1Y and 3Y postop, a favorable outcome was defined as meeting at least 3 of 4 criteria: 1) no PJF or mechanical failure with reoperation, 2) best clinical outcome for SRS[≥4.5] or ODI[<15], 3) improving in at least one SRS-Schwab modifier, and 4) not worsening in any SRS-Schwab modifier. A robust surgical result was defined as having a favorable outcome at both 1Y and 3Y. Predictors of robust outcomes were identified using multivariable regression analysis, with conditional inference tree (CIT) for continuous variables. RESULTS:We included 157 ASD patients in this analysis. At 1Y postop, 62 patients (39.5%) met the best clinical outcome [BCO] definition for ODI and 33 (21.0%) met the BCO for SRS. At 3Y, 58 patients (36.9%) had BCO for ODI and 29 (18.5%) for SRS. 95 patients (60.5%) were identified as having a favorable outcome at 1Y postop. At 3Y, 85 patients (54.1%) had a favorable outcome. Seventy-eight (49.7%) patients met criteria for a durable surgical result. Multivariable adjusted analysis identified the following independent predictors of surgical durability: surgical invasiveness >65, being fused to S1/pelvis, baseline to 6 week PI-LL difference >13.9°, and having a proportional Global Alignment and Proportion (GAP) score at 6 weeks. CONCLUSIONS:Nearly 50% of the ASD cohort demonstrated good surgical durability, with favorable radiographic alignment and functional status maintained up to 3 years. Surgical durability was more likely in patients whose reconstruction was fused to the pelvis and addressed lumbopelvic mismatch with adequate surgical invasiveness to achieve full alignment correction.

SUMMARY OF BACKGROUND DATA/BACKGROUND:Differing presentations of adult spinal deformity(ASD) may influence the extent of surgical intervention and use of prophylaxis at the base or the summit of a fusion construct to influence junctional failure rates. OBJECTIVE:Evaluate the surgical technique that has greatest influence on the rate of junctional failure following ASD surgery. STUDY DESIGN/SETTING/METHODS:Retrospective. METHODS:ASD patients with two-year(2Y) data and at least 5-level fusion to pelvis were included. Patients were divided based on UIV: [Longer Construct:T1-T4; Shorter Construct:T8-T12]. Parameters assessed included matching in age-adjusted PI-LL or PT, aligning in GAP-Relative Pelvic Version or Lordosis Distribution Index. After assessing all lumbopelvic radiographic parameters, the combination of realigning the two parameters with the greatest minimizing effect of PJF constituted a Good Base. Good Summit defined as having: (1)prophylaxis at UIV(tethers,hooks,cement), (2)no lordotic change(under-contouring) greater than 10° of the UIV, (3)preoperative UIV inclination angle<30°. Multivariable regression analysis assessed effects of junction characteristics and radiographic correction individually and collectively on development of PJK and PJF in differing construct lengths, adjusting for confounders. RESULTS:261 patients were included. The cohort had lower odds of PJK(OR: 0.5,[0.2-0.9];P=0.044) and PJF was less likely (OR: 0.1,[0.0-0.7];P=0.014) in the presence of a Good Summit. Normalizing pelvic compensation had the greatest radiographic effect on preventing PJF overall (OR: 0.6,[0.3-1.0];P=0.044). In Shorter Constructs, realignment had greater effect on decreasing the odds of PJF(OR: 0.2,[0.02-0.9];P=0.036). With Longer Constructs, a Good Summit lowered likelihood of PJK(OR: 0.3,[0.1-0.9];P=0.027). Good Base led to zero occurrences of PJF. In patients with severe frailty/osteoporosis, a Good Summit lowered incidence of PJK(OR: 0.4,[0.2-0.9]; P=0.041) and PJF (OR: 0.1,[0.01-0.99];P=0.049). CONCLUSION/CONCLUSIONS:To mitigate junctional failure, our study demonstrated the utility of individualizing surgical approaches to emphasize an optimal basal construct. Achievement of tailored goals at the cranial end of the surgical construct may be equally important, especially for higher risk patients with longer fusions. LEVEL OF EVIDENCE/METHODS:III.

STUDY DESIGN/METHODS:Retrospective. OBJECTIVE:To assess impact of surgical costs on patient reported outcomes in ASD. SUMMARY OF BACKGROUND DATA/BACKGROUND:With increased focus on delivering cost effective healthcare, interventions with high resource utilization, such as adult spinal deformity (ASD) surgery, have received greater scrutiny. METHODS:ASD patients≥18 years with BL and 2Y data were included. Surgical costs were calculated using 2021 average Medicare reimbursement by CPT code. Costs of complications and reoperations were intentionally excluded. Patients were ranked into tertiles by surgical cost: highest surgical costs (HC) and lowest surgical costs (LC). They were propensity score matched (PSM) to account for differences in baseline age and deformity. Bivariate logistic regressions assessed odds of achieving outcomes. RESULTS:421 patients met inclusion (60.7 y, 81.8% female, CCI: 1.6, 27.1 kg/m2), 139 LC and 127 HC patients. After PSM, 102 patients remained in each cost group with an average reimbursement of LC: $12,494 versus HC: $29,248. Matched cohorts had similar demographics and baseline HRQLs. Matched groups had similar baseline SVA (HC: 59.0 vs. LC: 56.7 mm), PI-LL (HC: 13.1 vs. LC: 13.4°), and PT (HC: 25.3 vs. LC: 22.4°). Rates of complications were not significantly different between the cost groups. Compared to LC group, by 2Y HC patients had higher odds of reaching SCB in ODI (OR: 2.356, [1.220, 4.551], P=0.011), in SRS-Total (OR: 2.988, [1.515, 5.895], P=0.002), and in NRS Back (OR: 2.739, [1.105, 6.788], P=0.030). Similar findings were appreciated for HC patients in the setting of Schwab deformity outcome criteria. CONCLUSIONS:Although added cost did not guarantee an ideal outcome, HC patients experienced superior patient reported outcomes compared to LC patients. While cost efficiency remains an important priority for health policy, isolating cost reduction may compromise outcomes and add to future costs of re-intervention, particularly with more severe baseline deformity. LEVEL OF EVIDENCE/METHODS:III.

Understanding global body balance can optimize the postoperative course for patients undergoing spinal or lower limb surgical realignment. This observational cohort study aimed to characterize patients with reported imbalance and identify predictors. The CDC establishes a representative sample annually via the NHANES. All participants who said "yes" (Imbalanced) or "no" (Balanced) to the following question were identified from 1999-2004: "During the past 12 months, have you had dizziness, difficulty with balance or difficulty with falling?" Univariate analyses compared Imbalanced versus Balanced subjects and binary logistic regression modeling predicted for Imbalance. Of 9964 patients, imbalanced (26.5%) were older (65.4 vs. 60.6 years), with more females (60% vs. 48%). Imbalanced subjects reported higher rates of comorbidities, including osteoporosis (14.4% vs. 6.6%), arthritis (51.6% vs. 31.9%), and low back pain (54.4% vs 32.7%). Imbalanced patients had more difficulty with activities, including climbing 10 steps (43.8% vs. 21%) and stooping/crouching/kneeling (74.3% vs. 44.7%), and they needed greater time to walk 20 feet (9.5 vs. 7.1 s). Imbalanced subjects had significantly lower caloric and dietary intake. Regression revealed that difficulties using fingers to grasp small objects (OR: 1.73), female gender (OR: 1.43), difficulties with prolonged standing (OR: 1.29), difficulties stooping/crouching/kneeling (OR: 1.28), and increased time to walk 20 feet (OR: 1.06) were independent predictors of Imbalance (all p < 0.05). Imbalanced patients were found to have identifiable comorbidities and were detectable using simple functional assessments. Structured tests that assess dynamic functional status may be useful for preoperative optimization and risk-stratification for patients undergoing spinal or lower limb surgical realignment.

STUDY DESIGN/METHODS:Multicenter comparative cohort. OBJECTIVE:Studies have shown markedly higher rates of complications and all-cause mortality following surgery for adult cervical deformity (ACD) compared with adult thoracolumbar deformity (ATLD), though the reasons for these differences remain unclear. Our objectives were to compare baseline frailty, disability, and comorbidities between ACD and complex ATLD patients undergoing surgery. METHODS:Two multicenter prospective adult spinal deformity registries were queried, one ATLD and one ACD. Baseline clinical and frailty measures were compared between the cohorts. RESULTS:< .001). CONCLUSIONS:Compared with ATLD patients, ACD patients had worse baseline characteristics on all measures assessed (comorbidities/disability/frailty). These differences may help account for greater risk of complications and all-cause mortality previously observed in ACD patients and facilitate strategies for better preoperative optimization.

STUDY DESIGN/METHODS:Retrospective review. OBJECTIVES/OBJECTIVE:The International Spine Study Group-AO (ISSG-AO) Adult Spinal Deformity (ASD) Complication Classification System was developed to improve classification, reporting, and study of complications among patients undergoing ASD surgery. The ISSG-AO system classifies interventions to address complications by level of invasiveness: grade zero (none); grade 1, mild (e.g., medication change); grade 2, moderate (e.g., ICU admission); grade 3, severe (e.g., reoperation related to surgery of interest). To evaluate the efficacy of the ISSG-AO ASD Complication Classification System, we aimed to compare correlations between postoperative length of stay (LOS) and complication severity as classified by the ISSG-AO ASD and traditional major/minor complication classification systems. METHODS:Patients age ≥18 in a multicenter ASD database who sustained in-hospital complications were identified. Complications were classified with the major/minor and ISSG-AO systems and correlated with LOS using an ensemble-based machine learning algorithm (conditional random forest) and a generalized linear mixed model. RESULTS:490 patients at 19 sites were included. 64.9% of complications were major, and 35.1% were minor. By ISSG-AO classification, 20.4%, 66.1%, 6.7%, and 6.7% were grades 0-3, respectively. ISSG-AO complication grading demonstrated significant correlation with LOS, whereas major/minor complication classification demonstrated inverse correlation with LOS. In conditional random forest analysis, ISSG-AO classification had the greatest relative importance when assessing correlations across multiple variables with LOS. CONCLUSIONS:The ISSG-AO system may help identify specific complications associated with prolonged LOS. Targeted interventions to avoid or reduce these complications may improve ASD surgical quality and resource utilization.

OBJECTIVE:The goal of this study was to determine if patients with mild scoliosis and age-appropriate sagittal alignment have favorable outcomes following surgical correction. METHODS: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). RESULTS: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. CONCLUSION/CONCLUSIONS: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.