Faculty Bibliography

OBJECTIVE:The objective of this study was to use an unsupervised cluster approach to identify patterns of operative adult spinal deformity (ASD) and compare the perioperative outcomes of these groups. METHODS:A multicenter data set included patients with complex surgical ASD, including those with severe deformities, significant surgical complexity, or advanced age who underwent a multilevel fusion. An unsupervised cluster analysis allowing for 10% outliers was used to identify different deformity patterns. The perioperative outcomes of these clusters were then compared using ANOVA, Kruskal-Wallis, and chi-square tests, with p values < 0.05 considered significant. RESULTS:Two hundred eighty-six patients were classified into four clusters of deformity patterns: hyper-thoracic kyphosis (hyper-TK), severe coronal, severe sagittal, and moderate sagittal. Hyper-TK patients had the lowest disability (mean Oswestry Disability Index [ODI] 32.9 ± 17.1) and pain scores (median numeric rating scale [NRS] back score 6, leg score 1). The severe coronal cluster had moderate functional impairment (mean physical component score 34.4 ± 12.3) and pain (median NRS back score 7, leg score 4) scores. The severe sagittal cluster had the highest levels of disability (mean ODI 49.3 ± 15.6) and low appearance scores (mean 2.3 ± 0.7). The moderate cluster (mean 68.8 ± 7.8 years) had the highest pain interference subscores on the Patient-Reported Outcomes Measurement Information System (mean 65.2 ± 5.8). Overall 30-day adverse events were equivalent among the four groups. Fusion to the pelvis was most common in the moderate sagittal (89.4%) and severe sagittal (97.5%) clusters. The severe coronal cluster had more osteotomies per case (median 11, IQR 6.5-14) and a higher rate of 30-day implant-related complications (5.5%). The severe sagittal and hyper-TK clusters had more three-column osteotomies (43% and 32.3%, respectively). Hyper-TK patients had shorter hospital stays. CONCLUSIONS:This cohort of patients with complex ASD surgeries contained four natural clusters of deformity, each with distinct perioperative outcomes.

STUDY DESIGN/METHODS:Retrospective review of a cervical deformity database. OBJECTIVE:This study aimed to develop a model that can predict the postoperative DJK angle by using pre and post-operative radiographic measurements. SUMMARY OF BACKGROUND DATA/BACKGROUND:Distal junctional kyphosis (DJK) is a complication following cervical deformity correction that can reduce of patient quality of life and functional status. Although researchers have identified the risk factors for DJK, no model has been proposed to predict the magnitude of DJK. METHODS:The DJK angle was defined as the Cobb angle from LIV to LIV-2 with traditional DJK (tDJK) having a DJK angle change >10°. Models were trained using 66.6% of the randomly selected patients and validated in the remaining 33.3%. Pre-and post-operative radiographic parameters associated with DJK were identified and ranked using a conditional variable importance table. Linear regression models were developed using the factors most strongly associated with the postoperative DJK angle. RESULTS:131 patients were included with a mean follow-up duration of 14±8 months. The mean postoperative DJK angle was 14.6±14° and occurred in 35% of the patients. No significant differences between the training and validation cohort were observed. The variables most associated with post-operative DJK were: preoperative DJK angle (DJKApre), postoperative C2- lower Instrumented vertebral tilt (C2-LIV), and change in cervical lordosis (∆CL). The model identified the following equation as predictive of DJKA: DJKA=9.365 + (0.123*∆CL) - (0.315* ∆C2-LIV) - (0.054*DJKApre). The predicted and actual postoperative DJKA values were highly correlated (R=0.871, R2=0.759, P<0.001). CONCLUSION/CONCLUSIONS:The variables that most increased the DJK angle were the preoperative DJK angle, postoperative alignment within the construct, and change in CL. Future studies can build upon the model developed to be applied in a clinical setting when planning for cervical deformity correction.

BACKGROUND:Patients with less severe adult spinal deformity undergo surgical correction and often achieve good clinical outcomes. However, it is not well understood how much clinical improvement is due to sagittal correction rather than treatment of the spondylotic process. PURPOSE/OBJECTIVE:Determine baseline thresholds in radiographic parameters that, when exceeded, may result in substantive clinical improvement from surgical correction. STUDY DESIGN/METHODS:Retrospective. METHODS:ASD patients with BL and 2-year(2Y) data were included. Parameters assessed: SVA, PI-LL, PT, T1PA, L1PA, L4-S1 Lordosis, C2-C7 SVA(cSVA), C2-T3, C2 Slope(C2S). Outcomes: Good Outcome(GO) at 2Y: [Meeting either: 1) SCB for ODI(change greater than 18.8), or 2) ODI<15 and SRS-Total>4.5. Binary logistic regression assessed each parameter to determine if correction was more likely needed to achieve GO. Conditional inference tree(CIT) run machine learning analysis generated baseline thresholds for each parameter, above which, correction was necessary to achieve GO. RESULTS:We included 431 ASD patients. There were 223(50%) that achieved a GO by two years. Binary logistic regression analysis demonstrated, with increasing baseline severity in deformity, sagittal correction was more often seen in those achieving GO for each parameter(all P<0.001). Of patients with baseline T1PA above the threshold, 95% required correction to meet Good Outcome(95% vs. 54%,P<0.001). A baseline PI-LL above 10° (74% of patients meeting GO) needed correction to achieve GO (OR: 2.6,[95% CI 1.4-4.8]). A baseline C2 slope above 15° also necessitated correction to obtain clinical success (OR: 7.7,[95% CI 3.7-15.7]). CONCLUSION/CONCLUSIONS:Our study highlighted point may be present at which sagittal correction has an outsized influence on clinical improvement, reflecting the line where deformity becomes a significant contributor to disability. These new thresholds give us insight into which patients may be more suitable for sagittal correction, as opposed to intervention for the spondylotic process only, leading to a more efficient utility of surgical intervention for adult spinal deformity. LEVEL OF EVIDENCE/METHODS:III.

Study Design: Multicenter, prospective cohort Objectives: Malalignment following adult spine deformity (ASD) surgery can impact outcomes and increase mechanical complications. We assess whether preoperative goals for sagittal alignment following ASD surgery are achieved. Methods: ASD patients were prospectively enrolled based on 3 criteria: deformity severity (PI-LL ≥25°, TPA ≥30°, SVA ≥15 cm, TCobb≥70° or TLCobb≥50°), procedure complexity (≥12 levels fused, 3-CO or ACR) and/or age (>65 and ≥7 levels fused). The surgeon documented sagittal alignment goals prior to surgery. Goals were compared with achieved alignment on first follow-up standing radiographs. Results: The 266 enrolled patients had a mean age of 61.0 years (SD = 14.6) and 68% were women. Mean instrumented levels was 13.6 (SD = 3.8), and 23.2% had a 3-CO. Mean (SD) offsets (achieved-goal) were: SVA = −8.5 mm (45.6 mm), PI-LL = −4.6° (14.6°), TK = 7.2° (14.7°), reflecting tendencies to undercorrect SVA and PI-LL and increase TK. Goals were achieved for SVA, PI-LL, and TK in 74.4%, 71.4%, and 68.8% of patients, respectively, and was achieved for all 3 parameters in 37.2% of patients. Three factors were independently associated with achievement of all 3 alignment goals: use of PACs/equivalent for surgical planning (P <.001), lower baseline GCA (P =.009), and surgery not including a 3-CO (P =.037). Conclusions: Surgeons failed to achieve goal alignment of each sagittal parameter in ∼25-30% of ASD patients. Goal alignment for all 3 parameters was only achieved in 37.2% of patients. Those at greatest risk were patients with more severe deformity. Advancements are needed to enable more consistent translation of preoperative alignment goals to the operating room.

STUDY DESIGN/METHODS:Retrospective review of a multicenter comprehensive cervical deformity (CD) database. OBJECTIVE:To develop a novel risk index specific to each patient to aid in patient counseling and surgical planning to minimize postop DJK occurrence. BACKGROUND:Distal junctional kyphosis(DJK) is a radiographic finding identified after patients undergo instrumented spinal fusions which can result in sagittal spinal deformity, pain and disability, and potentially neurological compromise. DJK is considered multifactorial in nature and there is a lack of consensus on the true etiology of DJK. METHODS:CD pts with baseline(BL) and at least 1-year postoperative(1Y) radiographic follow-up were included. A patient-specific DJK score was created through use of unstandardized Beta weights of a multivariate regression model predicting DJK(end of fusion construct to the 2nd distal vertebra change in this angle by<-10° from BL to postop). RESULTS:110 CD pts included(61yrs, 66.4%F, 28.8kg/m2). 31.8% of these pts developed DJK (16.1% 3M, 11.4% 6M, 62.9% 1Y). At BL, DJK pts were more frail and underwent combined approach more (both P<0.05). Multivariate model regression analysis identified individualized scores through creation of a DJK equation: -0.55+0.009(BL Inclination) -0.078(Pre Inflection)+5.9×10-5(BL LIV angle) + 0.43(combine approach) - 0.002(BL TS-CL)- 0.002(BL PT)- 0.031(BL C2-C7)+ 0.02(∆T4-T12)+ 0.63(Osteoporosis)- 0.03(anterior approach) - 0.036( Frail) - 0.032(3 column osteotomy). This equation has a 77.8% accuracy of predicting DJK. A score ≥81 predicted DJK with an accuracy of 89.3%. The BL reference equation correlated with 2Y outcomes of NSR-Back percentage(P=0.003), reoperation(P=0.04), and MCID for EQ. 5D(P=0.04). CONCLUSIONS:This study proposes a novel risk index of DJK development that focuses on potentially modifiable surgical factors as well as established patient-related and radiographic determinants. The reference model created demonstrated strong correlations with relevant two year outcome measures, including axial pain-related symptoms, occurrence of related reoperations, and the achievement of minimal clinically importance differences for EQ. 5D.

Study Design: Retrospective review of prospective database. Objectives: Vertebral pelvic angles (VPAs) account for complexity in spine shape by assessing the relative position of each vertebra with regard to the pelvis. This study uses VPAs to investigate the shape of the fused spine after T10-pelvis fusion, in patients with adult spinal deformity (ASD), and then explores its association with proximal junctional kyphosis (PJK). Methods: Included patients had radiographic evidence of ASD and underwent T10-pelvis realignment. VPAs were used to construct a virtual shape of the post-operative spine. VPA-predicted and actual shapes were then compared between patients with and without PJK. Logistic regression was used to identify components of the VPA-based model that were independent predictors of PJK occurrence and post-operative shape. Results: 287 patients were included. VPA-predicted shape was representative of the true post-operative contour, with a mean point-to-point error of 1.6-2.9% of the T10-S1 spine length. At 6-weeks follow-up, 102 patients (35.5%) developed PJK. Comparison of the true post-operative shapes demonstrated that PJK patients had more posteriorly translated vertebrae from L3 to T7 (P <.001). Logistic regression demonstrated that L3PA (P =.047) and T11PA (P <.001) were the best independent predictors of PJK and were, in conjunction with pelvic incidence, sufficient to reproduce the actual spinal contour (error <3%). Conclusions: VPAs are reliable in reproducing the true, post-operative spine shape in patients undergoing T10-pelvis fusion for ASD. Because VPAs are independent of patient position, L3PA, T11PA, and PI measurements can be used for both pre- and intra-operative planning to ensure optimal alignment.

STUDY DESIGN/METHODS:Retrospective cohort. OBJECTIVE:To describe the 2-year outcomes for patients undergoing surgical correction of cervical deformity. BACKGROUND:Adult cervical deformity (CD) has been shown to compromise health-related quality of life. While advances in spinal realignment have shown promising short-term clinical results in this parameter, the long-term outcomes of CD corrective surgery remain unclear. METHODS:Operative CD patients >18 years with 2-year (2Y) HRQL/radiographic data were included. Improvement in radiographic, neurologic and HRQL outcomes were reported. Patients with a prior cervical fusion and patients with the greatest and smallest change based on NDI, NRS neck, mJOA were compared using multivariable analysis controlling for age, and frailty, and invasiveness. RESULTS:158 patients were included in this study. By 2Y, 96.3% of patients improved in Ames cSVA modifier, 34.2% in TS-CL, 42.0% in Horizontal gaze modifier, and 40.9% in SVA modifier. Additionally, 65.5% of patients improved in Passias CL modifier, 53.3% in TS-CL modifier, 100% in C2-T3 modifier, 88.9% in C2S modifier, and 81.0% in MGS modifier severity by 2Y. The cohort significantly improved from BL to 2Y in NDI, NRS Neck, and mJOA, all P<0.05. 59.3% of patients met MCID for NDI, 62.3% for NRS Neck, and 37.3% for mJOA. 97 patients presented with at least one neurologic deficit at BL and 63.9% no longer reported that deficit at follow-up. There were 45 (34.6%) cases of DJK (∆DJKA>10° between LIV and LIV-2), of which 17 were distal junctional failure (DJF-DJK requiring reoperation). Patients with the greatest beneficial change were less likely to have had a complication in the 2-year follow-up period. CONCLUSION/CONCLUSIONS:Correction of cervical deformity results in notable clinical and radiographic improvement with most patients achieving favorable outcomes after two years. However, complications including distal junctional kyphosis or failure remain prevalent.

BACKGROUND:Studies have utilized psychological questionnaires to identify the psychological distress among certain surgical populations. RESEARCH QUESTION/OBJECTIVE:Is there an additional psychological burden among patients undergoing surgical treatment for their symptomatic degenerative cervical disease? MATERIALS AND METHODS/METHODS:Patients>18 years of age with symptomatic, degenerative cervical spine disease were included and prospectively enrolled. Correlations and multivariable logistic regression analysis assessed the relationship between these mental health components (PCS, FABQ) and the severity of disability described by the NDI, EQ-5D, and mJOA score. Patient distress scores were compared to previously published benchmarks for other diagnoses. RESULTS:). Increasing neck disability and decreasing EQ-5D were correlated with greater PCS and FABQ(all p<0.001). Patients with severe psychological distress at baseline were more likely to report severe neck disability, while physician-reported mJOA had weaker associations. Compared to historical controls of lumbar patients, patients in our study had greater levels of psychological distress, as measured by FABQ (40.0 vs 17.6;p<0.001) and PCS (27.4 vs 19.3;p<0.001). DISCUSSION AND CONCLUSION/CONCLUSIONS:Degenerative cervical spine patients seeking surgery were found to have a significant level of psychological distress, with a large portion reporting severe fear avoidance beliefs and catastrophizing pain at baseline. Strong correlation was seen between patient-reported functional metrics, but less so with physician-reported signs and symptoms. Additionally, this population demonstrated higher psychological burden in certain respects than previously identified benchmarks of patients with other disorders. Preoperative treatment to help mitigate this distress, impact postoperative outcomes, and should be further investigated. LEVEL OF EVIDENCE/METHODS:Level III.

BACKGROUND:As corrective surgery for cervical deformity (CD) increases, so does the rate of complications and reoperations. To minimize suboptimal postoperative outcomes, it is important to develop a tool that allows for proper preoperative risk stratification. OBJECTIVE:To develop a prognostic utility for identification of risk factors that lead to the development of major complications and unplanned reoperations. METHODS:CD patients age 18 years or older were stratified into 2 groups based on the postoperative occurrence of a revision and/or major complication. Multivariable logistic regressions identified characteristics that were associated with revision or major complication. Decision tree analysis established cutoffs for predictive variables. Models predicting both outcomes were quantified using area under the curve (AUC) and receiver operating curve characteristics. RESULTS:A total of 109 patients with CD were included in this study. By 1 year postoperatively, 26 patients experienced a major complication and 17 patients underwent a revision. Predictive modeling incorporating preoperative and surgical factors identified development of a revision to include upper instrumented vertebrae > C5, lowermost instrumented vertebrae > T7, number of unfused lordotic cervical vertebrae > 1, baseline T1 slope > 25.3°, and number of vertebral levels in maximal kyphosis > 12 (AUC: 0.82). For developing a major complication, a model included a current smoking history, osteoporosis, upper instrumented vertebrae inclination angle < 0° or > 40°, anterior diskectomies > 3, and a posterior Smith Peterson osteotomy (AUC: 0.81). CONCLUSION/CONCLUSIONS:Revisions were predicted using a predominance of radiographic parameters while the occurrence of major complications relied on baseline bone health, radiographic, and surgical characteristics.

STUDY DESIGN/METHODS:Retrospective cohort study. OBJECTIVE:Assess changes in outcomes and surgical approaches for adult cervical deformity (ACD) surgery over time. SUMMARY OF BACKGROUND DATA/BACKGROUND:As the population ages and prevalence of cervical deformity increases, corrective surgery has been increasingly seen as a viable treatment. Dramatic surgical advancements and expansion of knowledge on this procedure have transpired over years, but the impact on cervical deformity surgery is unknown. METHODS:ACD patients (≥18 yrs) with complete baseline and up to two-year HRQL and radiographic data were included. Descriptive analysis included demographics, radiographic, and surgical details. Patients were grouped into Early(2013-2014) and Late(2015-2017) by DOS. Univariate and multivariable regression analyses were used to assess differences in surgical, radiographic, and clinical outcomes over time. RESULTS:119 cervical deformity patients met inclusion criteria. Early group consisted of 72 patients, and Late group consisted of 47. Late group had a higher CCI (1.3 vs. 0.72), more cerebrovascular disease (6% vs. 0%, both P<0.05), and no difference in age, frailty, deformity, or cervical rigidity. Controlling for baseline deformity, and age, Late group underwent fewer three-column osteotomies (OR=0.18, 95% CI:0.06-0.76, P=0.014). At last follow-up, Late group had less patients with: a moderate/high Ames horizontal modifier (71.7% vs. 88.2%), and overcorrection in PT (4.3% vs. 18.1%, both P<0.05). Controlling for baseline deformity, age, levels fused, and three-column osteotomies, Late group experienced fewer adverse events (OR =0.15, 95% CI: 0.28-0.8, P=0.03), and neurological complications (OR =0.1, 95% CI:0.012-0.87, P=0.03). CONCLUSION/CONCLUSIONS:Despite a population with greater co-morbidity and associated risk, outcomes remained consistent between early and later time-periods, indicating general improvements in care. The later cohort demonstrated fewer three-column osteotomies, less suboptimal realignments and concomitant reductions in adverse events and neurologic complications. This may suggest greater facility with less invasive techniques.