Browsing by Author "Schwab, Frank J"
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Item Open Access A Pilot Study on Posterior Polyethylene Tethers to Prevent Proximal Junctional Kyphosis After Multilevel Spinal Instrumentation for Adult Spinal Deformity.(Operative neurosurgery (Hagerstown, Md.), 2019-02) Buell, Thomas J; Buchholz, Avery L; Quinn, John C; Bess, Shay; Line, Breton G; Ames, Christopher P; Schwab, Frank J; Lafage, Virginie; Shaffrey, Christopher I; Smith, Justin SBACKGROUND:Proximal junctional kyphosis (PJK) is a common problem after multilevel spine instrumentation. OBJECTIVE:To determine if junctional tethers reduce PJK after multilevel instrumented surgery for adult spinal deformity (ASD). METHODS:ASD patients who underwent posterior instrumented fusion were divided into 3 groups: no tether (NT), polyethylene tether-only (TO; tied securely through the spinous processes of the uppermost instrumented vertebra [UIV] + 1 and UIV-1), and tether with crosslink (TC; passed through the spinous process of UIV+1 and tied to a crosslink between UIV-1 and UIV-2). PJK was defined as proximal junctional angle ≥ 10° and ≥ 10° greater than the corresponding preoperative measurement. RESULTS:One hundred eighty-four (96%) of 191 consecutive patients achieved minimum 3-mo follow-up (mean = 20 mo [range:3-56 mo]; mean age = 66 yr; 67.4% female). There were no significant differences between groups based on demographic, surgical, and sagittal radiographic parameters. PJK rates were 45.3% (29/64), 34.4% (22/64), and 17.9% (10/56) for NT, TO, and TC, respectively. PJK rate for all tethered patients (TO + TC; 26.7% [32/120]) was significantly lower than NT (P = .011). PJK rate for TC was significantly lower than NT (P = .001). Kaplan-Meier analysis showed significant time-dependent PJK reduction for TC vs NT (log rank test, P = .010). Older age and greater change in lumbar lordosis were independent predictors of PJK, while junctional tethers had a significant protective effect. CONCLUSION:Junctional tethers significantly reduced occurrence of PJK. This difference was progressive from NT to TO to TC, but only reached pairwise significance for NT vs TC. This suggests potential benefit of tethers to reduce PJK, and that future prospective studies are warranted.Item Open Access A Risk-Benefit Analysis of Increasing Surgical Invasiveness Relative to Frailty Status in Adult Spinal Deformity Surgery.(Spine, 2021-08) Passias, Peter G; Brown, Avery E; Bortz, Cole; Pierce, Katherine; Alas, Haddy; Ahmad, Waleed; Passfall, Lara; Kummer, Nicholas; Krol, Oscar; Lafage, Renaud; Lafage, Virginie; Burton, Douglas; Hart, Robert; Anand, Neel; Mundis, Gregory; Neuman, Brian; Line, Breton; Shaffrey, Christopher; Klineberg, Eric; Smith, Justin; Ames, Christopher; Schwab, Frank J; Bess, Shay; International Spine Study GroupStudy design
Retrospective review of a prospectively enrolled multicenter Adult Spinal Deformity (ASD) database.Objective
Investigate invasiveness and outcomes of ASD surgery by frailty state.Summary of background data
The ASD Invasiveness Index incorporates deformity-specific components to assess correction magnitude. Intersections of invasiveness, surgical outcomes, and frailty state are understudied.Methods
ASD patients with baseline and 3-year (3Y) data were included. Logistic regression analyzed the relationship between increasing invasiveness and major complications or reoperations and meeting minimal clinically important differences (MCID) for health-related quality-of-life measures at 3Y. Decision tree analysis assessed invasiveness risk-benefit cutoff points, above which experiencing complications or reoperations and not reaching MCID were higher. Significance was set to P < 0.05.Results
Overall, 195 of 322 patients were included. Baseline demographics: age 59.9 ± 14.4, 75% female, BMI 27.8 ± 6.2, mean Charlson Comorbidity Index: 1.7 ± 1.7. Surgical information: 61% osteotomy, 52% decompression, 11.0 ± 4.1 levels fused. There were 98 not frail (NF), 65 frail (F), and 30 severely frail (SF) patients. Relationships were found between increasing invasiveness and experiencing a major complication or reoperation for the entire cohort and by frailty group (all P < 0.05). Defining a favorable outcome as no major complications or reoperation and meeting MCID in any health-related quality of life at 3Y established an invasiveness cutoff of 63.9. Patients below this threshold were 1.8[1.38-2.35] (P < 0.001) times more likely to achieve favorable outcome. For NF patients, the cutoff was 79.3 (2.11[1.39-3.20] (P < 0.001), 111 for F (2.62 [1.70-4.06] (P < 0.001), and 53.3 for SF (2.35[0.78-7.13] (P = 0.13).Conclusion
Increasing invasiveness is associated with increased odds of major complications and reoperations. Risk-benefit cutoffs for successful outcomes were 79.3 for NF, 111 for F, and 53.3 for SF patients. Above these, increasing invasiveness has increasing risk of major complications or reoperations and not meeting MCID at 3Y.Level of Evidence: 3.Item Open Access A standardized nomenclature for cervical spine soft-tissue release and osteotomy for deformity correction: clinical article.(Journal of neurosurgery. Spine, 2013-09) Ames, Christopher P; Smith, Justin S; Scheer, Justin K; Shaffrey, Christopher I; Lafage, Virginie; Deviren, Vedat; Moal, Bertrand; Protopsaltis, Themistocles; Mummaneni, Praveen V; Mundis, Gregory M; Hostin, Richard; Klineberg, Eric; Burton, Douglas C; Hart, Robert; Bess, Shay; Schwab, Frank J; International Spine Study GroupObject
Cervical spine osteotomies are powerful techniques to correct rigid cervical spine deformity. Many variations exist, however, and there is no current standardized system with which to describe and classify cervical osteotomies. This complicates the ability to compare outcomes across procedures and studies. The authors' objective was to establish a universal nomenclature for cervical spine osteotomies to provide a common language among spine surgeons.Methods
A proposed nomenclature with 7 anatomical grades of increasing extent of bone/soft tissue resection and destabilization was designed. The highest grade of resection is termed the major osteotomy, and an approach modifier is used to denote the surgical approach(es), including anterior (A), posterior (P), anterior-posterior (AP), posterior-anterior (PA), anterior-posterior-anterior (APA), and posterior-anterior-posterior (PAP). For cases in which multiple grades of osteotomies were performed, the highest grade is termed the major osteotomy, and lower-grade osteotomies are termed minor osteotomies. The nomenclature was evaluated by 11 reviewers through 25 different radiographic clinical cases. The review was performed twice, separated by a minimum 1-week interval. Reliability was assessed using Fleiss kappa coefficients.Results
The average intrarater reliability was classified as "almost perfect agreement" for the major osteotomy (0.89 [range 0.60-1.00]) and approach modifier (0.99 [0.95-1.00]); it was classified as "moderate agreement" for the minor osteotomy (0.73 [range 0.41-1.00]). The average interrater reliability for the 2 readings was the following: major osteotomy, 0.87 ("almost perfect agreement"); approach modifier, 0.99 ("almost perfect agreement"); and minor osteotomy, 0.55 ("moderate agreement"). Analysis of only major osteotomy plus approach modifier yielded a classification that was "almost perfect" with an average intrarater reliability of 0.90 (0.63-1.00) and an interrater reliability of 0.88 and 0.86 for the two reviews.Conclusions
The proposed cervical spine osteotomy nomenclature provides the surgeon with a simple, standard description of the various cervical osteotomies. The reliability analysis demonstrated that this system is consistent and directly applicable. Future work will evaluate the relationship between this system and health-related quality of life metrics.Item Open Access Adult Cervical Deformity Patients Have Higher Baseline Frailty, Disability, and Comorbidities Compared With Complex Adult Thoracolumbar Deformity Patients: A Comparative Cohort Study of 616 Patients.(Global spine journal, 2023-11) Smith, Justin S; Kelly, Michael P; Buell, Thomas J; Ben-Israel, David; Diebo, Bassel; Scheer, Justin K; Line, Breton; Lafage, Virginie; Lafage, Renaud; Klineberg, Eric; Kim, Han Jo; Passias, Peter; Gum, Jeffrey L; Kebaish, Khal; Mullin, Jeffrey P; Eastlack, Robert; Daniels, Alan; Soroceanu, Alex; Mundis, Gregory; Hostin, Richard; Protopsaltis, Themistocles S; Hamilton, D Kojo; Gupta, Munish; Lewis, Stephen J; Schwab, Frank J; Lenke, Lawrence G; Shaffrey, Christopher I; Burton, Douglas; Ames, Christopher P; Bess, Shay; International Spine Study GroupStudy design
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
616 patients were identified (107 ACD and 509 ATLD). These groups had similar mean age (64.6 vs 60.8 years, respectively, P = .07). ACD patients were less likely to be women (51.9% vs 69.5%, P < .001) and had greater Charlson Comorbidity Index (1.5 vs .9, P < .001) and ASA grade (2.7 vs 2.4, P < .001). ACD patients had worse VR-12 Physical Component Score (PCS, 25.7 vs 29.9, P < .001) and PROMIS Physical Function Score (33.3 vs 35.3, P = .031). All frailty measures were significantly worse for ACD patients, including hand dynamometer (44.6 vs 55.6 lbs, P < .001), CSHA Clinical Frailty Score (CFS, 4.0 vs 3.2, P < .001), and Edmonton Frailty Scale (EFS, 5.15 vs 3.21, P < .001). Greater proportions of ACD patients were frail (22.9% vs 5.7%) or vulnerable (15.6% vs 10.9%) based on EFS (P < .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.Item Open Access After 9 Years of 3-Column Osteotomies, Are We Doing Better? Performance Curve Analysis of 573 Surgeries With 2-Year Follow-up.(Neurosurgery, 2018-07) Diebo, Bassel G; Lafage, Virginie; Varghese, Jeffrey J; Gupta, Munish; Kim, Han Jo; Ames, Christopher; Kebaish, Khaled; Shaffrey, Christopher; Hostin, Richard; Obeid, Ibrahim; Burton, Doug; Hart, Robert A; Lafage, Renaud; Schwab, Frank J; International Spine Study Group (ISSG) of Denver, ColoradoBackground
In spinal deformity treatment, the increased utilization of 3-column (3CO) osteotomies reflects greater comfort and better training among surgeons. This study aims to evaluate the longitudinal performance and adverse events (complications or revisions) for a multicenter group following a decade of 3CO.Objective
To investigate if performance of 3CO surgeries improves with years of practice.Methods
Patients who underwent 3CO for spinal deformity with intra/postoperative and revision data collected up to 2 yr were included. Patients were chronologically divided into 4 even groups. Demographics, baseline deformity/correction, and surgical metrics were compared using Student t-test. Postoperative and revision rates were compared using Chi-square analysis.Results
Five hundred seventy-three patients were stratified into: G1 (n = 143, 2004-2008), G2 (n = 142, 2008-2009), G3 (n = 144, 2009-2010), G4 (n = 144 2010-2013). The most recent patients were more disabled by Oswestry disability index (G4 = 49.2 vs G1 = 38.3, P = .001), and received a larger osteotomy resection (G4 = 26° vs G1 = 20°, P = .011) than the earliest group. There was a decrease in revision rate (45%, 35%, 33%, 30%, P = .039), notably in revisions for pseudarthrosis (16.7% G1 vs 6.9% G4, P = .007). Major complication rates also decreased (57%, 50%, 46%, 39%, P = .023) as did excessive blood loss (>4 L, 27.2 vs 16.7%, P = .023) and bladder/bowel deficit (4.2% vs 0.7% P = .002). Successful outcomes (no complications or revision) significantly increased (P = .001).Conclusion
Over 9 yr, 3COs are being performed on an increasingly disabled population while gaining a greater correction at the osteotomy site. Revisions and complication rate decreased while success rate improved during the 2-yr follow-up period.Item Open Access Alignment Risk Factors for Proximal Junctional Kyphosis and the Effect of Lower Thoracic Junctional Tethers for Adult Spinal Deformity.(World neurosurgery, 2019-01) Buell, Thomas J; Chen, Ching-Jen; Quinn, John C; Buchholz, Avery L; Mazur, Marcus D; Mullin, Jeffrey P; Nguyen, James H; Taylor, Davis G; Bess, Shay; Line, Breton G; Ames, Christopher P; Schwab, Frank J; Lafage, Virginie; Shaffrey, Christopher I; Smith, Justin SObjective
The aims of this retrospective cohort study were to 1) identify new alignment risk factors for proximal junctional kyphosis (PJK) in adult spinal deformity (ASD) patients with lower thoracic upper instrumented vertebra (UIV) and 2) determine the effect of junctional tethers on PJK and UIV alignment.Methods
We analyzed consecutive ASD patients who underwent posterior instrumented fusion with lower thoracic UIV (T9-T11). Posteriorly anchored junctional tethers were used more recently for ligamentous augmentation to prevent PJK. In addition to regional and global parameters, upper segmental lumbar lordosis (ULL) versus lower segmental lumbar lordosis and UIV angle (measured from UIV inferior endplate to horizontal) were assessed. Primary outcome of PJK was defined as proximal junctional angle >10° and >10° greater than the corresponding preoperative measurement. Univariable and multivariable analyses were performed.Results
The study cohort comprised 120 ASD patients (mean age, 67 years) with minimum 1-year follow-up. Preoperative ULL (P = 0.034) and UIV angle (P = 0.026) were associated with PJK. No independent preoperative alignment risk factors of PJK were identified in multivariable analysis. Tether use was protective against PJK (odds ratio, 0.063 [0.016-0.247]; P < 0.001). PJK in tethered patients was more common with greater postoperative ULL (P = 0.047) and UIV angle (P = 0.026).Conclusions
Junctional tethers significantly reduced PJK in ASD patients with lower thoracic UIV. In tethered patients, PJK was more common with greater postoperative lordosis of the upper lumbar spine and greater UIV angle. This finding suggests potential benefit of tethers to mitigate effects of segmental lumbar and focal UIV malalignment that may occur after deformity surgery.Item Open Access An Analysis of the Incidence and Outcomes of Major Versus Minor Neurological Decline After Complex Adult Spinal Deformity Surgery: A Subanalysis of Scoli-RISK-1 Study.(Spine, 2018-07) Kato, So; Fehlings, Michael G; Lewis, Stephen J; Lenke, Lawrence G; Shaffrey, Christopher I; Cheung, Kenneth MC; Carreon, Leah Y; Dekutoski, Mark B; Schwab, Frank J; Boachie-Adjei, Oheneba; Kebaish, Khaled M; Ames, Christopher P; Qiu, Yong; Matsuyama, Yukihiro; Dahl, Benny T; Mehdian, Hossein; Pellisé, Ferran; Berven, Sigurd HStudy design
A subanalysis from a prospective, multicenter, international cohort study in 15 sites (Scoli-RISK-1).Objective
To report detailed information regarding the severity of neurological decline related to complex adult spine deformity (ASD) surgery and to examine outcomes based on severity.Summary of background data
Postoperative neurological decline after ASD surgeries can occur due to nerve root(s) or spinal cord dysfunction. The impact of decline and the pattern of recovery may be related to the anatomic location and the severity of the injury.Methods
An investigation of 272 prospectively enrolled complex ASD surgical patients with neurological status measured by American Spinal Injury Association Lower Extremity Motor Scores (LEMS) was undertaken. Postoperative neurological decline was categorized into "major" (≥5 points loss) versus "minor" (<5 points loss) deficits. Timing and extent of recovery in LEMS were investigated for each group.Results
Among the 265 patients with LEMS available at discharge, 61 patients (23%) had neurological decline, with 20 (33%) experiencing major decline. Of note, 90% of the patients with major decline had deficits in three or more myotomes. Full recovery was seen in 24% at 6 weeks and increased to 65% at 6 months. However, 34% continued to experience some neurological decline at 24 months, with 6% demonstrating no improvement. Of 41 patients (67%) with minor decline, 73% had deficits in one or two myotomes. Full recovery was seen in 49% at 6 weeks and increased to 70% at 6 months. Of note, 26% had persistence of some neurological deficit at 24 months, with 18% demonstrating no recovery.Conclusion
In patients undergoing complex ASD correction, a rate of postoperative neurological decline of 23% was noted with 33% of these being "major." Although most patients showed substantial recovery by 6 months, approximately one-third continued to experience neurological dysfunction.Level of evidence
2.Item Open Access Analysis of tranexamic acid usage in adult spinal deformity patients with relative contraindications: does it increase the risk of complications?(JOURNAL OF NEUROSURGERY-SPINE, 2024) Mullin, Jeffrey P; Soliman, Mohamed AR; Smith, Justin S; Kelly, Michael P; Buell, Thomas J; Diebo, Bassel; Scheer, Justin K; Line, Breton; Lafage, Virginie; Lafage, Renaud; Klineberg, Eric; Kim, Han Jo; Passias, Peter G; Gum, Jeffrey L; Kebaish, Khaled; Eastlack, Robert K; Daniels, Alan H; Soroceanu, Alex; Mundis, Gregory; Hostin, Richard; Protopsaltis, Themistocles S; Hamilton, D Kojo; Gupta, Munish C; Lewis, Stephen J; Schwab, Frank J; Lenke, Lawrence G; Shaffrey, Christopher I; Bess, Shay; Ames, Christopher P; Burton, DouglasItem Open Access Analysis of tranexamic acid usage in adult spinal deformity patients with relative contraindications: does it increase the risk of complications?(Journal of neurosurgery. Spine, 2024-03) Mullin, Jeffrey P; Soliman, Mohamed AR; Smith, Justin S; Kelly, Michael P; Buell, Thomas J; Diebo, Bassel; Scheer, Justin K; Line, Breton; Lafage, Virginie; Lafage, Renaud; Klineberg, Eric; Kim, Han Jo; Passias, Peter G; Gum, Jeffrey L; Kebaish, Khaled; Eastlack, Robert K; Daniels, Alan H; Soroceanu, Alex; Mundis, Gregory; Hostin, Richard; Protopsaltis, Themistocles S; Hamilton, D Kojo; Gupta, Munish C; Lewis, Stephen J; Schwab, Frank J; Lenke, Lawrence G; Shaffrey, Christopher I; Bess, Shay; Ames, Christopher P; Burton, DouglasObjective
Complex spinal deformity surgeries may involve significant blood loss. The use of antifibrinolytic agents such as tranexamic acid (TXA) has been proven to reduce perioperative blood loss. However, for patients with a history of thromboembolic events, there is concern of increased risk when TXA is used during these surgeries. This study aimed to assess whether TXA use in patients undergoing complex spinal deformity correction surgeries increases the risk of thromboembolic complications based on preexisting thromboembolic risk factors.Methods
Data were analyzed for adult patients who received TXA during surgical correction for spinal deformity at 21 North American centers between August 2018 and October 2022. Patients with preexisting thromboembolic events and other risk factors (history of deep venous thrombosis [DVT], pulmonary embolism [PE], myocardial infarction [MI], stroke, peripheral vascular disease, or cancer) were identified. Thromboembolic complication rates were assessed during the postoperative 90 days. Univariate and multivariate analyses were performed to assess thromboembolic outcomes in high-risk and low-risk patients who received intravenous TXA.Results
Among 411 consecutive patients who underwent complex spinal deformity surgery and received TXA intraoperatively, 130 (31.6%) were considered high-risk patients. There was no significant difference in thromboembolic complications between patients with and those without preexisting thromboembolic risk factors in univariate analysis (high-risk group vs low-risk group: 8.5% vs 2.8%, p = 0.45). Specifically, there were no significant differences between groups regarding the 90-day postoperative rates of DVT (high-risk group vs low-risk group: 1.5% vs 1.4%, p = 0.98), PE (2.3% vs 1.8%, p = 0.71), acute MI (1.5% vs 0%, p = 0.19), or stroke (0.8% vs 1.1%, p > 0.99). On multivariate analysis, high-risk status was not a significant independent predictor for any of the thromboembolic complications.Conclusions
Administration of intravenous TXA during the correction procedure did not change rates of thromboembolic events, acute MI, or stroke in this cohort of adult spinal deformity surgery patients.Item Open Access Appropriate Risk Stratification and Accounting for Age-Adjusted Reciprocal Changes in the Thoracolumbar Spine Reduces the Incidence and Magnitude of Distal Junctional Kyphosis in Cervical Deformity Surgery.(Spine, 2021-11) Passias, Peter G; Bortz, Cole; Pierce, Katherine E; Kummer, Nicholas A; Lafage, Renaud; Diebo, Bassel G; Line, Breton G; Lafage, Virginie; Burton, Douglas C; Klineberg, Eric O; Kim, Han Jo; Daniels, Alan H; Mundis, Gregory M; Protopsaltis, Themistocles S; Eastlack, Robert K; Sciubba, Daniel M; Bess, Shay; Schwab, Frank J; Shaffrey, Christopher I; Smith, Justin S; Ames, Christopher P; International Spine Study Group (ISSG)Study design
Retrospective cohort study of a prospective cervical deformity (CD) database.Objective
Identify factors associated with distal junctional kyphosis (DJK); assess differences across DJK types.Summary of background data
DJK may develop as compensation for mal-correction of sagittal deformity in the thoracic curve. There is limited understanding of DJK drivers, especially for different DJK types.Methods
Included: patients with pre- and postoperative clinical/radiographic data. Excluded: patients with previous fusion to L5 or below. DJK was defined per surgeon note or DJK angle (kyphosis from LIV to LIV-2)<-10°, and pre- to postoperative change in DJK angle by<-10°. Age-specific target LL-TK alignment was calculated as published. Offset from target LL-TK was correlated to DJK magnitude and inclination. DJK types: severe (DJK<-20°), progressive (DJK increase>4.4°), symptomatic (reoperation or published disability thresholds of NDI ≥ 24 or mJOA≤14). Random forest identified factors associated with DJK. Means comparison tests assessed differences.Results
Included: 136 CD patients (61 ± 10 yr, 61%F). DJK rate was 30%. Postop offset from ideal LL-TK correlated with greater DJK angle (r = 0.428) and inclination of the distal end of the fusion construct (r = 0.244, both P < 0.02). Seven of the top 15 factors associated with DJK were radiographic, four surgical, and four clinical. Breakdown by type: severe (22%), progressive (24%), symptomatic (61%). Symptomatic had more posterior osteotomies than asymptomatic (P = 0.018). Severe had worse NDI and upper-cervical deformity (CL, C2 slope, C0-C2), as well as more posterior osteotomies than nonsevere (all P < 0.01). Progressive had greater malalignment both globally and in the cervical spine (all P < 0.03) than static. Each type had varying associated factors.Conclusion
Offset from age-specific alignment is associated with greater DJK and more anterior distal construct inclination, suggesting DJK may develop due to inappropriate realignment. Preoperative clinical and radiographic factors are associated with symptomatic and progressive DJK, suggesting the need for preoperative risk stratification.Level of Evidence: 3.Item Open Access Are Higher Global Alignment and Proportion Scores Associated With Increased Risks of Mechanical Complications After Adult Spinal Deformity Surgery? An External Validation.(Clinical orthopaedics and related research, 2021-02) Kwan, Kenny Yat Hong; Lenke, Lawrence G; Shaffrey, Christopher I; Carreon, Leah Y; Dahl, Benny T; Fehlings, Michael G; Ames, Christopher P; Boachie-Adjei, Oheneba; Dekutoski, Mark B; Kebaish, Khaled M; Lewis, Stephen J; Matsuyama, Yukihiro; Mehdian, Hossein; Qiu, Yong; Schwab, Frank J; Cheung, Kenneth Man Chee; AO Spine Knowledge Forum DeformityBackground
The Global Alignment and Proportion (GAP) score, based on pelvic incidence-based proportional parameters, was recently developed to predict mechanical complications after surgery for spinal deformities in adults. However, this score has not been validated in an independent external dataset.Questions/purposes
After adult spinal deformity surgery, is a higher GAP score associated with (1) an increased risk of mechanical complications, defined as rod fractures, implant-related complications, proximal or distal junctional kyphosis or failure; (2) a higher likelihood of undergoing revision surgery to treat a mechanical complication; and (3) is a lower (more proportioned) GAP score category associated with better validated outcomes scores using the Oswestry Disability Index (ODI), Scoliosis Research Society-22 (SRS-22) and the Short Form-36 questionnaires?Methods
A total of 272 patients who had undergone corrective surgeries for complex spinal deformities were enrolled in the Scoli-RISK-1 prospective trial. Patients were included in this secondary analysis if they fulfilled the original inclusion criteria by Yilgor et al. From the original 272 patients, 14% (39) did not satisfy the radiographic inclusion criteria, the GAP score could not be calculated in 14% (37), and 24% (64) did not have radiographic assessment at postoperative 2 years, leaving 59% (159) for analysis in this review of data from the original trial. A total of 159 patients were included in this study,with a mean age of 58 ± 14 years at the time of surgery. Most patients were female (72%, 115 of 159), the mean number of levels involved in surgery was 12 ± 4, and three-column osteotomy was performed in 76% (120 of 159) of patients. The GAP score was calculated using parameters from early postoperative radiographs (between 3 and 12 weeks) including pelvic incidence, sacral slope, lumbar lordosis, lower arc lordosis and global tilt, which were independently obtained from a computer software based on centralized patient radiographs. The GAP score was categorized as proportional (scores of 0 to 2), moderately disproportional (scores of 3 to 6), or severely disproportional (scores higher than 7 to 13). Receiver operating characteristic area under curve (AUC) was used to assess associations between GAP score and risk of mechanical complications and risk of revision surgery. An AUC of 0.5 to 0.7 was classified as "no or low associative power", 0.7 to 0.9 as "moderate" and greater than 0.9 as "high". We analyzed differences in validated outcome scores between the GAP categories using Wilcoxon rank sum test.Results
At a minimum of 2 years' follow-up, a higher GAP score was not associated with increased risks of mechanical complications (AUC = 0.60 [95% CI 0.50 to 0.70]). A higher GAP score was not associated with a higher likelihood of undergoing a revision surgery to treat a mechanical complication (AUC = 0.66 [95% 0.53 to 0.78]). However, a moderately disproportioned GAP score category was associated with better SF-36 physical component summary score (36 ± 10 versus 40 ± 11; p = 0.047), better SF-36 mental component summary score (46 ± 13 versus 51 ± 12; p = 0.01), better SRS-22 total score (3.4 ± 0.8 versus 3.7 ± 0.7, p = 0.02) and better ODI score (35 ± 21 versus 25 ± 20; p = 0.003) than severely disproportioned GAP score category.Conclusion
Based on the findings of this external validation study, we found that alignment targets based on the GAP score alone were not associated with increased risks of mechanical complications and mechanical revisions in patients with complex adult spinal disorders. Parameters not included in the original GAP score needed to be considered to reduce the likelihood of mechanical complications.Level of evidence
Level III, diagnostic study.Item Open Access Are insufficient corrections a major factor in distal junctional kyphosis? A simulated analysis of cervical deformity correction using in-construct measurements.(Journal of neurosurgery. Spine, 2024-05) Ani, Fares; Sissman, Ethan; Woo, Dainn; Soroceanu, Alex; Mundis, Gregory; Eastlack, Robert K; Smith, Justin S; Hamilton, D Kojo; Kim, Han Jo; Daniels, Alan H; Klineberg, Eric O; Neuman, Brian; Sciubba, Daniel M; Gupta, Munish C; Kebaish, Khaled M; Passias, Peter G; Hart, Robert A; Bess, Shay; Shaffrey, Christopher I; Schwab, Frank J; Lafage, Virginie; Ames, Christopher P; Protopsaltis, Themistocles SObjective
The present study utilized recently developed in-construct measurements in simulations of cervical deformity surgery in order to assess undercorrection and predict distal junctional kyphosis (DJK).Methods
A retrospective review of a database of operative cervical deformity patients was analyzed for severe DJK and mild DJK. C2-lower instrumented vertebra (LIV) sagittal angle (SA) was measured postoperatively, and the correction was simulated in the preoperative radiograph in order to match the C2-LIV by using the planning software. Linear regression analysis that used C2 pelvic angle (CPA) and pelvic tilt (PT) determined the simulated PT that matched the virtual CPA. Linear regression analysis was used to determine the C2-T1 SA, C2-T4 SA, and C2-T10 SA that corresponded to DJK of 20° and cervical sagittal vertical axis (cSVA) of 40 mm.Results
Sixty-nine cervical deformity patients were included. Severe and mild DJK occurred in 11 (16%) and 22 (32%) patients, respectively; 3 (4%) required DJK revision. Simulated corrections demonstrated that severe and mild DJK patients had worse alignment compared to non-DJK patients in terms of cSVA (42.5 mm vs 33.0 mm vs 23.4 mm, p < 0.001) and C2-LIV SVA (68.9 mm vs 57.3 mm vs 36.8 mm, p < 0.001). Linear regression revealed the relationships between in-construct measures (C2-T1 SA, C2-T4 SA, and C2-T10 SA), cSVA, and change in DJK (all R > 0.57, p < 0.001). A cSVA of 40 mm corresponded to C2-T4 SA of 10.4° and C2-T10 SA of 28.0°. A DJK angle change of 10° corresponded to C2-T4 SA of 5.8° and C2-T10 SA of 20.1°.Conclusions
Simulated cervical deformity corrections demonstrated that severe DJK patients have insufficient corrections compared to patients without DJK. In-construct measures assess sagittal alignment within the fusion separate from DJK and subjacent compensation. They can be useful as intraoperative tools to gauge the adequacy of cervical deformity correction.Item Open Access Are Minimally Invasive Spine Surgeons or Classical Open Spine Surgeons More Consistent with Their Treatment of Adult Spinal Deformity?(World neurosurgery, 2022-09) Uribe, Juan S; Koffie, Robert M; Wang, Michael Y; Mundis, Gregory M; Kanter, Adam S; Eastlack, Robert K; Anand, Neel; Park, Paul; Smith, Justin S; Burton, Douglas C; Chou, Dean; Kelly, Michael P; Kim, Han Jo; Bess, Shay; Shaffrey, Christopher I; Schwab, Frank J; Lenke, Lawrence G; Mummaneni, Praveen VObjective
Spine surgeons have a heuristic sense of how to surgically restore alignment and address adult spinal deformity (ASD) symptoms, but consensus on the extent of treatment remains unclear. We sought to determine the variability of surgical approaches in treating ASD.Methods
Sixteen spine surgeons were surveyed on treatment approaches in 10 select ASD cases. We repeated the survey with the same surgeons 4 weeks later, with cases ordered differently. We examined the variability in length of construct, use of interbody spacers, osteotomies, and pelvic fixation frequency.Results
Treatment approaches for each case varied by surgeon, with some surgeons opting for long fusion constructs in cases for which others offered no surgery. There was no consensus among surgeons on the number of levels fused, interbody spacer use, or anterior/posterior osteotomies. Intersurgeon and intrasurgeon variability was 48% (kappa = 0.31) and 59% (kappa = 0.44) for surgeons performing minimally invasive surgery (MIS) versus 37% (kappa = 0.21) and 47% (kappa = 0.30) for those performing open surgery. In the second-round survey, 8 of 15 (53%) surgeons substantially changed the construct length, number of interbody spacers, and osteotomies in at least half the cases they previously reviewed. Surgeons performing MIS versus open surgery were less likely to extend constructs to the pelvis (42.5% vs. 67.5%; P = 0.02), but construct length was not correlated with whether a surgeon performed MIS or open surgery.Conclusions
Spinal deformity surgeons lack consensus on the optimal surgical approach for treating ASD. Classifying surgeons as performing MIS or open surgery does not mitigate this variability.Item Open Access Are We Focused on the Wrong Early Postoperative Quality Metrics? Optimal Realignment Outweighs Perioperative Risk in Adult Spinal Deformity Surgery.(Journal of clinical medicine, 2023-08) Passias, Peter G; Williamson, Tyler K; Mir, Jamshaid M; Smith, Justin S; Lafage, Virginie; Lafage, Renaud; Line, Breton; Daniels, Alan H; Gum, Jeffrey L; Schoenfeld, Andrew J; Hamilton, David Kojo; Soroceanu, Alex; Scheer, Justin K; Eastlack, Robert; Mundis, Gregory M; Diebo, Bassel; Kebaish, Khaled M; Hostin, Richard A; Gupta, Munish C; Kim, Han Jo; Klineberg, Eric O; Ames, Christopher P; Hart, Robert A; Burton, Douglas C; Schwab, Frank J; Shaffrey, Christopher I; Bess, Shay; On Behalf Of The International Spine Study GroupBackground
While reimbursement is centered on 90-day outcomes, many patients may still achieve optimal, long-term outcomes following adult spinal deformity (ASD) surgery despite transient short-term complications.Objective
Compare long-term clinical success and cost-utility between patients achieving optimal realignment and suboptimally aligned peers.Study design/setting
Retrospective cohort study of a prospectively collected multicenter database.Methods
ASD patients with two-year (2Y) data included. Groups were propensity score matched (PSM) for age, frailty, body mass index (BMI), Charlson Comorbidity Index (CCI), and baseline deformity. Optimal radiographic criteria are defined as meeting low deformity in all three (Scoliosis Research Society) SRS-Schwab parameters or being proportioned in Global Alignment and Proportionality (GAP). Cost-per-QALY was calculated for each time point. Multivariable logistic regression analysis and ANCOVA (analysis of covariance) adjusting for baseline disability and deformity (pelvic incidence (PI), pelvic incidence minus lumbar lordosis (PI-LL)) were used to determine the significance of surgical details, complications, clinical outcomes, and cost-utility.Results
A total of 930 patients were considered. Following PSM, 253 "optimal" (O) and 253 "not optimal" (NO) patients were assessed. The O group underwent more invasive procedures and had more levels fused. Analysis of complications by two years showed that the O group suffered less overall major (38% vs. 52%, p = 0.021) and major mechanical complications (12% vs. 22%, p = 0.002), and less reoperations (23% vs. 33%, p = 0.008). Adjusted analysis revealed O patients more often met MCID (minimal clinically important difference) in SF-36 PCS, SRS-22 Pain, and Appearance. Cost-utility-adjusted analysis determined that the O group generated better cost-utility by one year and maintained lower overall cost and costs per QALY (both p < 0.001) at two years.Conclusions
Fewer late complications (mechanical and reoperations) are seen in optimally aligned patients, leading to better long-term cost-utility overall. Therefore, the current focus on avoiding short-term complications may be counterproductive, as achieving optimal surgical correction is critical for long-term success.Item Open Access Assessing Abnormal Proximal Junctional Angles in Adult Spinal Deformity: A Normative Data Approach to Define Proximal Junctional Kyphosis.(Spine, 2024-10) Khalifé, Marc; Lafage, Renaud; Daniels, Alan H; Diebo, Bassel G; Elysée, Jonathan; Ames, Christopher P; Bess, Shay R; Burton, Douglas C; Eastlack, Robert K; Gupta, Munish C; Hostin, Richard A; Kebaish, Khaled; Kim, Han-Jo; Klineberg, Eric O; Mundis, Gregory; Okonkwo, David O; Gille, Olivier; Guigui, Pierre; Ferrero, Emmanuelle; Skalli, Wafa; Assi, Ayman; Vergari, Claudio; Shaffrey, Christopher I; Smith, Justin S; Schwab, Frank J; Lafage, Virginie; International Spine Study GroupStudy design
Multicentric retrospective study of prospectively collected data.Objective
Based on normative data from a cohort of asymptomatic volunteers, this study sought to determine the rate of abnormal values of proximal junctional angles (PJA) in adult spinal deformity (ASD) surgery patients, and compare it with PJK rate.Summary of background data
Proximal junctional kyphosis (PJK) definition does not take the vertebral level into account.Methods
This study included 721 healthy volunteers and 824 ASD surgery patients with 2-year postoperative follow-up. Normative values for each disc and vertebral body between T1 and T12 were analyzed, then normative values for PJA at each thoracic level were defined in the volunteer cohort as the mean±2 standard deviations. PJA abnormal values at the upper instrumented vertebra (UIV) were compared with Glattes' and Lovecchio's definitions for PJK in the ASD population at two years.Results
Mean age was 37.7±16.3 in the volunteer cohort, with 50.5% of females. Mean thoracic kyphosis (TK) was -50.9±10.8°. Corridors of normality included PJA greater than 20° between T3 and T12. Mean age was 60.5±14.0 years in the ASD cohort, with 77.2% of females. Mean baseline TK was -37.4±19.9°, with a significant increase after surgery (-15.6±15.3°, P<0.001). There was 46.2% of PJK according to Glattes' versus 8.7% according to Lovecchio's and 22.9% of kyphotic PJA compared to normative values (P<0.001).Conclusion
This study provides normative values for segmental and regional alignment of thoracic spine, used to describe abnormal values of PJA for each level. Using level-adjusted PJA values allows a more precise assessment of abnormal proximal angles and question the definition for PJK.Level of evidence
II.Item Open Access Assessment of Adult Spinal Deformity Complication Timing and Impact on 2-Year Outcomes Using a Comprehensive Adult Spinal Deformity Classification System.(Spine, 2022-03) Wick, Joseph B; Le, Hai V; Lafage, Renaud; Gupta, Munish C; Hart, Robert A; Mundis, Gregory M; Bess, Shay; Burton, Douglas C; Ames, Christopher P; Smith, Justin S; Shaffrey, Christopher I; Schwab, Frank J; Passias, Peter G; Protopsaltis, Themistocles S; Lafage, Virginie; Klineberg, Eric O; International Spine Study GroupStudy design
Retrospective review of prospectively collected multicenter registry data.Objective
To identify rates and timing of postoperative complications in adult spinal deformity (ASD) patients, the impact of complication type and timing on health related quality of life (HRQoL) outcomes, and the impact of complication timing on readmission and reoperation rates. Better understanding of complication timing and impact on HRQoL may improve patient selection, preoperative counseling, and postoperative complication surveillance.Summary of background data
ASD is common and associated with significant disability. Surgical correction is often pursued, but is associated with high complication rates. The International Spine Study Group, AO Spinal Deformity Forum, and European Spine Study Group have developed a new complication classification system for ASD (ISSG-AO spine complications classification system).Methods
The ISSG-AO spine complications classification system was utilized to assess complications occurring over the 2-year postoperative time period amongst a multicenter, prospectively enrolled cohort of patients who underwent surgery for ASD. Kaplan-Meier survival curves were established for each complication type. Propensity score matching was performed to adjust for baseline disability and comorbidities. Associations between each complication type and HRQoL, and reoperation/readmission and complication timing, were assessed.Results
Of 584 patients meeting inclusion criteria, cardiopulmonary, gastrointestinal, infection, early adverse events, and operative complications contributed to a rapid initial decrease in complication-free survival. Implant-related, radiographic, and neurologic complications substantially decreased long-term complication-free survival. Only radiographic and implant-related complications were significantly associated with worse 2-year HRQoL outcomes. Need for readmission and/or reoperation was most frequent among those experiencing complications after postoperative day 90.Conclusion
Surgeons should recognize that long-term complications have a substantial negative impact on HRQoL, and should carefully monitor for implant-related and radiographic complications over long-term follow-up.Level of Evidence: 4.Item Open Access Assessment of Surgical Treatment Strategies for Moderate to Severe Cervical Spinal Deformity Reveals Marked Variation in Approaches, Osteotomies, and Fusion Levels.(World neurosurgery, 2016-07) Smith, Justin S; Klineberg, Eric; Shaffrey, Christopher I; Lafage, Virginie; Schwab, Frank J; Protopsaltis, Themistocles; Scheer, Justin K; Ailon, Tamir; Ramachandran, Subaraman; Daniels, Alan; Mundis, Gregory; Gupta, Munish; Hostin, Richard; Deviren, Vedat; Eastlack, Robert; Passias, Peter; Hamilton, D Kojo; Hart, Robert; Burton, Douglas C; Bess, Shay; Ames, Christopher P; International Spine Study GroupObjective
Although previous reports suggest that surgery can improve the pain and disability of cervical spinal deformity (CSD), techniques are not standardized. Our objective was to assess for consensus on recommended surgical plans for CSD treatment.Methods
Eighteen CSD cases were assembled, including a clinical vignette, cervical imaging (radiography, computed tomography/magnetic resonance imaging), and full-length standing radiography. Fourteen deformity surgeons (10 orthopedic, 4 neurosurgery) were queried regarding recommended surgical plans.Results
There was marked variation in treatment plans across all deformity types. Even for the least complex deformities (moderate midcervical apex kyphosis), there was lack of agreement on approach (50% combined anterior-posterior, 25% anterior only, 25% posterior only), number of anterior (range, 2-6) and posterior (range, 4-16) fusion levels, and types of osteotomies. As the kyphosis apex moved caudally (cervical-thoracic junction/upper thoracic spine) and for cases with chin-on-chest kyphosis, >80% of surgeons agreed on a posterior-only approach and >70% recommended a pedicle subtraction osteotomy or vertebral column resection, but the range in number of anterior (4-8) and posterior (4-27) fusion levels was exceptionally broad. Cases of cervical/cervical-thoracic scoliosis had the least agreement for approach (48% posterior only, 33% combined anterior-posterior, 17% anterior-posterior-anterior or posterior-anterior-posterior, 2% anterior only) and had broad variation in the number of anterior (2-5) and posterior (6-19) fusion levels, and recommended osteotomies (41% pedicle subtraction osteotomy/vertebral column resection).Conclusions
Among a panel of deformity surgeons, there was marked lack of consensus on recommended surgical approach, osteotomies, and fusion levels for CSD. Further study is warranted to assess whether specific surgical treatment approaches are associated with better outcomes.Item Open Access Assessment of symptomatic rod fracture after posterior instrumented fusion for adult spinal deformity.(Neurosurgery, 2012-10) Smith, Justin S; Shaffrey, Christopher I; Ames, Christopher P; Demakakos, Jason; Fu, Kai-Ming G; Keshavarzi, Sassan; Li, Carol MY; Deviren, Vedat; Schwab, Frank J; Lafage, Virginie; Bess, Shay; International Spine Study GroupBackground
Improved understanding of rod fracture (RF) in adult spinal deformity could be valuable for implant design, surgical planning, and patient counseling.Objective
To evaluate symptomatic RF after posterior instrumented fusion for adult spinal deformity.Methods
A multicenter, retrospective review of RF in adult spinal deformity was performed. Inclusion criteria were spinal deformity, age older than 18 years, and more than 5 levels posterior instrumented fusion. Rod failures were divided into early (≤12 months) and late (>12 months).Results
Of 442 patients, 6.8% had symptomatic RF. RF rates were 8.6% for titanium alloy, 7.4% for stainless steel, and 2.7% for cobalt chromium. RF incidence after pedicle subtraction osteotomy (PSO) was 15.8%. Among patients with a PSO and RF, 89% had RF at or adjacent to the PSO. Mean time to early RF (63%) was 6.4 months (range, 2-12 months). Mean time to late RF (37%) was 31.8 months (range, 14-73 months). The majority of RFs after PSO (71%) were early (mean, 10 months). Among RF cases, mean sagittal vertical axis improved from preoperative (163 mm) to postoperative (76.9 mm) measures (P<.001); however, 16 had postoperative malalignment (sagittal vertical axis>50 mm; mean, 109 mm).Conclusion
Symptomatic RF occurred in 6.8% of adult spinal deformity cases and in 15.8% of PSO patients. The rate of RF was lower with cobalt chromium than with titanium alloy or stainless steel. Early failure was most common after PSO and favored the PSO site, suggesting that RF may be caused by stress at the PSO site. Postoperative sagittal malalignment may increase the risk of RF.Item Open Access Association of myelopathy scores with cervical sagittal balance and normalized spinal cord volume: analysis of 56 preoperative cases from the AOSpine North America Myelopathy study.(Spine, 2013-10) Smith, Justin S; Lafage, Virginie; Ryan, Devon J; Shaffrey, Christopher I; Schwab, Frank J; Patel, Alpesh A; Brodke, Darrel S; Arnold, Paul M; Riew, K Daniel; Traynelis, Vincent C; Radcliff, Kris; Vaccaro, Alexander R; Fehlings, Michael G; Ames, Christopher PStudy design
Post hoc analysis of prospectively collected data.Objective
Development of methods to determine in vivo spinal cord dimensions and application to correlate preoperative alignment, myelopathy, and health-related quality-of-life scores in patients with cervical spondylotic myelopathy (CSM).Summary of background data
CSM is the leading cause of spinal cord dysfunction. The association between cervical alignment, sagittal balance, and myelopathy has not been well characterized.Methods
This was a post hoc analysis of the prospective, multicenter AOSpine North America CSM study. Inclusion criteria for this study required preoperative cervical magnetic resonance imaging (MRI) and neutral sagittal cervical radiography. Techniques for MRI assessment of spinal cord dimensions were developed. Correlations between imaging and health-related quality-of-life scores were assessed.Results
Fifty-six patients met inclusion criteria (mean age = 55.4 yr). The modified Japanese Orthopedic Association (mJOA) scores correlated with C2-C7 sagittal vertical axis (SVA) (r = -0.282, P = 0.035). Spinal cord volume correlated with cord length (r = 0.472, P < 0.001) and cord average cross-sectional area (r = 0.957, P < 0.001). For all patients, no correlations were found between MRI measurements of spinal cord length, volume, mean cross-sectional area or surface area, and outcomes. For patients with cervical lordosis, mJOA scores correlated positively with cord volume (r = 0.366, P = 0.022), external cord area (r = 0.399, P = 0.012), and mean cross-sectional cord area (r = 0.345, P = 0.031). In contrast, for patients with cervical kyphosis, mJOA scores correlated negatively with cord volume (r = -0.496, P = 0.043) and mean cross-sectional cord area (r = -0.535, P = 0.027).Conclusion
This study is the first to correlate cervical sagittal balance (C2-C7 SVA) to myelopathy severity. We found a moderate negative correlation in kyphotic patients of cord volume and cross-sectional area to mJOA scores. The opposite (positive correlation) was found for lordotic patients, suggesting a relationship of cord volume to myelopathy that differs on the basis of sagittal alignment. It is interesting to note that sagittal balance but not kyphosis is tied to myelopathy score. Future work will correlate alignment changes to cord morphology changes and myelopathy outcomes. SUMMARY STATEMENTS: This is the first study to correlate sagittal balance (C2-C7 SVA) to myelopathy severity. We found a moderate negative correlation in kyphotic patients of cord volume and cross-sectional area to mJOA scores. The opposite (positive correlation) was found for lordotic patients, suggesting a relationship of cord volume to myelopathy that differs on the basis of sagittal alignment.Item Open Access Baseline Patient-Reported Outcomes Correlate Weakly With Radiographic Parameters: A Multicenter, Prospective NIH Adult Symptomatic Lumbar Scoliosis Study of 286 Patients.(Spine, 2016-11) Chapman, Todd M; Baldus, Christine R; Lurie, Jon D; Glassman, Steven D; Schwab, Frank J; Shaffrey, Christopher I; Lafage, Virginie; Boachie-Adjei, Oheneba; Kim, Han J; Smith, Justin S; Crawford, Charles H; Lenke, Lawrence G; Buchowski, Jacob M; Edwards, Charles; Koski, Tyler; Parent, Stefan; Lewis, Stephen; Kang, Daniel G; McClendon, Jamal; Metz, Lionel; Zebala, Lukas P; Kelly, Michael P; Spratt, Kevin F; Bridwell, Keith HStudy design
Prospective, cross-sectional study.Objective
The aim of the study was to determine which radiographic parameters drive patient-reported outcomes (PROs) in primary presentation adult symptomatic lumbar scoliosis (ASLS).Summary of background data
Previous literature suggests correlations between PROs and sagittal plane deformity (sagittal vertical axis [SVA], pelvic incidence-lumbar lordosis [PI-LL] mismatch, pelvic tilt [PT]). Prior work included revision and primary adult spinal deformity patients. The present study addresses only primary presentation ASLS.Methods
Prospective baseline data were analyzed on 286 patients enrolled in an NIH RO1 clinical trial by nine centers from 2010 to 2014.Inclusion criteria
40 to 80 years old, lumbar Cobb (LC) 30° or higher and Scoliosis Research Society-23 score 4.0 or less in Pain, Function or Self-Image domains, or Oswestry Disability Index (ODI) 20 or higher. Patients were primary presentation (no prior spinal deformity surgery) and had complete baseline data: standing coronal/sagittal 36" radiographs and PROs (ODI, Scoliosis Research Society-23, Short Form-12). Correlation coefficients were calculated to evaluate relations between radiographic parameters and PROs for the study population and a subset of patients with ODI 40 or higher. Analysis of variance was used to identify differences in PROs for radiographic modifier groups.Results
Mean age was 60.3 years. Mean spinopelvic parameters were: LL = -39.2°; SVA = 3.1 cm; sacral slope = 32.5°; PT = 23.9°; PI-LL mismatch = 16.8°. Only weak correlations (0.2-0.4) were identified between population sacral slope, SVA and SVA modifiers, and SRS function. SVA and SVA modifiers were weakly associated with ODI. Although there were more correlations in subset analysis of high-symptom patients, all were weak. Analysis of variance identified significant differences in ODI reported by SVA modifier groups.Conclusion
In primary presentation patients with ASLS and a subset of "high-symptom" patients (ODI ≥ 40), only weak associations between baseline PROs and radiographic parameters were identified. For this patient population, these results suggest regional radiographic parameters (LC, LL, PT, PI-LL mismatch) are not drivers of PROs and cannot be used to extrapolate effect on patient-perceived pathology.Level of evidence
2.