Browsing by Author "Ames, Christopher"
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Item Open Access 1-Year Post-Operative Radiographic and Patient-Reported Outcomes following Cervical Deformity Correction are not Affected by a Short-Term Unplanned Return to the OR.(Spine, 2023-02) Fourman, Mitchell S; Lafage, Renaud; Ames, Christopher; Smith, Justin S; Passias, Peter G; Shaffrey, Christopher I; Mundis, Gregory; Protopsaltis, Themistocles; Gupta, Munish; Klineberg, Eric O; Bess, Shay; Lafage, Virginie; Kim, Han Jo; International Spine Study GroupStudy design
Retrospective analysis of a prospectively-collected multi-center database.Objective
Assess the radiographic and health-related quality of life (HRQoL) impact of a short term (<1 y) return to the OR after adult cervical spine deformity (ACSD) surgery.Summary of background data
Returns to the OR within a year of ACSD correction can be particularly devastating to these vulnerable hosts as they often involve compromise of the soft tissue envelope, neurologic deficits or hardware failure. This work sought to assess the impact of a short-term reoperation on 1-year radiographic and HRQoL outcomes.Methods
Patients operated on from 1/1/2013 to 1/1/2019 with at least 1-year of follow-up were included. The primary outcome was a short-term return to the OR. Variables of interest included patient demographics, Charlson Comorbidity Index (CCI), HRQoL measured with the Modified Japanese Orthopaedic Association (mJOA), Neck Disability Index (NDI) and EuroQuol-5D visual analogue scale (EQ-5D VAS) and radiographic outcomes, including T1-slope (TS), C2-C7 sagittal cobb angle (CL), TS-CL and cervical sagittal vertical axis (cSVA). Comparisons between those who did versus did not require a 1-year reoperation were performed using paired t-tests. A Kaplan Meier survival curve was used to estimate reoperation-free survival up to 2-years post-operatively.Results
A total of 121 patients were included in this work (age 61.9±10.1 y, BMI 28.4±6.9, CCI 1.0±1.4, 62.8% female). A 1-year unplanned return to the OR was required for 28 (23.1%) patients, of whom 19 followed-up for at least 1-year. Indications for a return to the OR were most commonly for neurologic complications (5%), infectious/wound complications (5.8%) and junctional failure (6.6%) No differences in demographics, comorbidities, pre-operative or 1-year post-operative HRQoL or radiographic outcomes were seen between operative groups.Conclusion
Reoperation <1 year after ACSD surgery did not influence 1-year radiographic outcomes or HRQoL.Item Open Access A New Piece of the Puzzle to Understand Cervical Sagittal Alignment: Utilizing a Novel Angle δ to Describe the Relationship among T1 Vertebral Body Slope, Cervical Lordosis, and Cervical Sagittal Alignment.(Neurosurgery, 2020-03) Goldschmidt, Ezequiel; Angriman, Federico; Agarwal, Nitin; Trevisan, Marcos; Zhou, James; Chen, Katherine; Gerszten, Peter C; Kanter, Adam S; Okonkwo, David O; Passias, Peter; Scheer, Justin; Protopsaltis, Themistocles; Lafage, Virginie; Lafage, Renaud; Schwab, Frank; Bess, Shay; Ames, Christopher; Smith, Justin S; Shaffrey, Christopher I; Miller, Emily; Jain, Amit; Neuman, Brian; Sciubba, Daniel M; Burton, Douglas; Hamilton, D Kojo; International Spine Study Group (ISSG)Cervical alignment has become increasingly important in the planning of spine surgery. A relationship between the slope of T1 (T1S), the cervical lordosis (CL), and the overall cervical sagittal vertical axis (cSVA) has previously been demonstrated, but the exact nature of this relationship is poorly understood. In this study, we derive theoretical and empirical equations to better understand how T1S and CL affect cSVA. The first equation was developed on a theoretical basis using inherent trigonometric relationships of the cervical spine. By treating the cervical spine as the arc of a circumference, and by taking into account the cervical height (CH), the geometric relationship between theT1S, CL, and cSVA was described via a trigonometric identity utilizing a novel angle δ subtended by the CH and cSVA (δ = T1S-CL/2). The second equation was developed on an empiric basis by performing a multiple linear regression on data obtained from a retrospective review of a large multicenter deformity database. The theoretical equation determined that the value of cSVA could be expressed as: $cSVA\ = \ CH*{\rm{tan}}( {\pi /180*( {T1S - CL/2} )} )$. The empirical equation determined that value of cSVA could be expressed as: $cSVA=({1.1*T1} )\ - ( {0.43*CL} ) + 6.69$. In both, the sagittal alignment of the head over the shoulders is directly proportional to the T1S and inversely proportional to CL/2. These 2 equations may allow surgeons to better understand how the CL compensates for the T1S, to accurately predict the postoperative cSVA, and to customize cervical interbody grafts by taking into consideration each individual patient's specific cervical spine parameters.Item Open Access A Novel Tool for Deformity Surgery Planning: Determining the Magnitude of Lordotic Correction Required to Achieve a Desired Sagittal Vertical Axis.(World neurosurgery, 2017-08) Goldschmidt, Ezequiel; Angriman, Federico; Agarwal, Nitin; Zhou, James; Chen, Katherine; Tempel, Zachary J; Gerszten, Peter C; Kanter, Adam S; Okonkwo, David O; Passias, Peter; Scheer, Justin; Protopsaltis, Themistocles; Lafage, Virginie; Lafage, Renaud; Schwab, Frank; Bess, Shay; Ames, Christopher; Smith, Justin S; Shaffrey, Christopher I; Miller, Emily; Jain, Amit; Neuman, Brian; Sciubba, Daniel M; Burton, Douglas; Hamilton, D Kojo; International Spine Study GroupObjective
We sought to create a model capable of predicting the magnitude of pelvic incidence-lumbar lordosis (PI-LL) correction necessary to achieve a desired change in sagittal vertical axis (SVA).Methods
A retrospective review was conducted of a prospectively maintained multicenter adult spinal deformity database collected by the International Spine Study Group between 2009 and 2014. The independent variable of interest was the degree of correction achieved in the PI-LL mismatch 6 weeks after surgery. Primary outcome was the change in global sagittal alignment 6 weeks and 1 year after surgery. We used a linear mixed-effects model to determine the extent to which corrections in the PI-LL relationship affected postoperative changes in SVA.Results
A total of 1053 adult patients were identified. Of these patients, 590 were managed surgically. Eighty-seven surgically managed patients were excluded because of incomplete or missing PI-LL measurements on follow-up; the remaining 503 patients were selected for inclusion. For each degree of improvement in the PI-LL mismatch at 6 weeks, the SVA decreased by 2.18 mm (95% confidence interval, -2.56, -1.79; P < 0.01) and 1.67 mm (95% confidence interval, -2.07, -1.27; P < 0.01) at 6 weeks and 12 months, respectively. A high SVA measurement (>50 mm) 1 year after surgery was negatively associated with health-related quality of life as measured by the Scoliosis Research Society 22 outcomes assessment.Conclusions
We describe a novel model that shows how surgical correction of the PI-LL relationship affects postoperative changes in SVA. This model may enable surgeons to determine preoperatively the amount of LL necessary to achieve a desired change in SVA.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 Adult cervical spine deformity: a state-of-the-art review.(Spine Deform, 2023-09-30) Jackson-Fowl, Brendan; Hockley, Aaron; Naessig, Sara; Ahmad, Waleed; Pierce, Katherine; Smith, Justin S; Ames, Christopher; Shaffrey, Christopher; Bennett-Caso, Claudia; Williamson, Tyler K; McFarland, Kimberly; Passias, Peter GAdult cervical deformity is a structural malalignment of the cervical spine that may present with variety of significant symptomatology for patients. There are clear and substantial negative impacts of cervical spine deformity, including the increased burden of pain, limited mobility and functionality, and interference with patients' ability to work and perform everyday tasks. Primary cervical deformities develop as the result of a multitude of different etiologies, changing the normal mechanics and structure of the cervical region. In particular, degeneration of the cervical spine, inflammatory arthritides and neuromuscular changes are significant players in the development of disease. Additionally, cervical deformities, sometimes iatrogenically, may present secondary to malalignment or correction of the thoracic, lumbar or sacropelvic spine. Previously, classification systems were developed to help quantify disease burden and influence management of thoracic and lumbar spine deformities. Following up on these works and based on the relationship between the cervical and distal spine, Ames-ISSG developed a framework for a standardized tool for characterizing and quantifying cervical spine deformities. When surgical intervention is required to correct a cervical deformity, there are advantages and disadvantages to both anterior and posterior approaches. A stepwise approach may minimize the drawbacks of either an anterior or posterior approach alone, and patients should have a surgical plan tailored specifically to their cervical deformity based upon symptomatic and radiographic indications. This state-of-the-art review is based upon a comprehensive overview of literature seeking to highlight the normal cervical spine, etiologies of cervical deformity, current classification systems, and key surgical techniques.Item Open Access Adult Scoliosis Deformity Surgery: Comparison of Outcomes Between One Versus Two Attending Surgeons.(Spine, 2017-07) Gomez, Jaime A; Lafage, Virginie; Sciubba, Daniel M; Bess, Shay; Mundis, Gregory M; Liabaud, Barthelemy; Hanstein, Regina; Shaffrey, Christopher; Kelly, Michael; Ames, Christopher; Smith, Justin S; Passias, Peter G; Errico, Thomas; Schwab, Frank; International Spine Study GroupStudy design
Retrospective review of prospectively collected data.Objective
Assess outcomes of adult spinal deformity (ASD) surgery performed by one versus two attending surgeons.Summary of background data
ASD centers have developed two attending teams to improve efficiency; their effects on complications and outcomes have not been reported.Methods
Patients with ASD with five or more levels fused and more than 2-year follow-up were included. Estimated blood loss (EBL), length of stay (LOS), operating room (OR) time, complications, quality of life (Health Related Quality of Life), and x-rays were analyzed. Outcomes were compared between one-surgeon (1S) and two-surgeon (2S) centers. A deformity-matched cohort was analyzed.Results
A total of 188 patients in 1S and 77 in 2S group were included. 2S group patients were older and had worse deformity based on the Scoliosis Research Society-Schwab classification (P < 0.05). There were no significant differences in levels fused (P = 0.57), LOS (8.7 vs 8.9 days), OR time (445.9 vs 453.2 min), or EBL (2008 vs 1898 cm; P > 0.05). 2S patients had more three-column osteotomies (3CO; P < 0.001) and used less bone morphogenetic protein 2 (BMP-2; 79.9% vs 15.6%; P < 0.001). The 2S group had fewer intraoperative complications (1.3% vs 11.1%; P = 0.006). Postoperative (6 wk to 2 yr) complications were more frequent in the 2S group (4.8% vs 15.6%; P < 0.002). After matching for deformity, there were no differences in (9.1 vs 10.1 days), OR time (467.8 vs 508.4 min), or EBL (3045 vs 2247 cm; P = 0.217). 2S group used less BMP-2 (20.6% vs 84.8%; P < 0.001), had fewer intraoperative complications (P = 0.015) but postoperative complications due to instrumentation failure/pseudarthrosis were more frequent (P < 0.01).Conclusion
No significant differences were found in LOS, OR time, or EBL between the 1S and 2S groups, even when matching for severity of deformity. 2S group had less BMP-2 use, fewer intraoperative complications but more postoperative complications.Level of evidence
2.Item Open Access Adult Spinal Deformity Surgery Is Associated with Increased Productivity and Decreased Absenteeism From Work and School.(Spine, 2022-02) Durand, Wesley M; Babu, Jacob M; Hamilton, David K; Passias, Peter G; Kim, Han Jo; Protopsaltis, Themistocles; Lafage, Virginie; Lafage, Renaud; Smith, Justin S; Shaffrey, Christopher; Gupta, Munish; Kelly, Michael P; Klineberg, Eric O; Schwab, Frank; Gum, Jeffrey L; Mundis, Gregory; Eastlack, Robert; Kebaish, Khaled; Soroceanu, Alex; Hostin, Richard A; Burton, Doug; Bess, Shay; Ames, Christopher; Hart, Robert A; Daniels, Alan H; International Spine Study Group (ISSG)Study design
Retrospective cohort study.Objective
We hypothesized that adult spinal deformity (ASD) surgery would be associated with improved work- and school-related productivity, as well as decreased rates of absenteeism.Summary of background data
ASD patients experience markedly decreased health-related quality of life along many dimensions.Methods
Only patients eligible for 2-year follow-up were included, and those with a history of previous spinal fusion were excluded. The primary outcome measures in this study were Scoliosis Research Society-22r score (SRS-22r) questions 9 and 17. A repeated measures mixed linear regression was used to analyze responses over time among patients managed operatively (OP) versus nonoperatively (NON-OP).Results
In total, 1188 patients were analyzed. 66.6% were managed operatively. At baseline, the mean percentage of activity at work/school was 56.4% (standard deviation [SD] 35.4%), and the mean days off from work/school over the past 90 days was 1.6 (SD 1.8). Patients undergoing ASD surgery exhibited an 18.1% absolute increase in work/school productivity at 2-year follow-up versus baseline (P < 0.0001), while no significant change was observed for the nonoperative cohort (P > 0.5). Similarly, the OP cohort experienced 1.1 fewer absent days over the past 90 days at 2 years versus baseline (P < 0.0001), while the NON-OP cohort showed no such difference (P > 0.3). These differences were largely preserved after stratifying by baseline employment status, age group, sagittal vertical axis (SVA), pelvic incidence minus lumbar lordosis (PI-LL), and deformity curve type.Conclusion
ASD patients managed operatively exhibited an average increase in work/school productivity of 18.1% and decreased absenteeism of 1.1 per 90 days at 2-year follow-up, while patients managed nonoperatively did not exhibit change from baseline. Given the age distribution of patients in this study, these findings should be interpreted as pertaining primarily to obligations at work or within the home. Further study of the direct and indirect economic benefits of ASD surgery to patients is warranted.Level of Evidence: 3.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 Are the Arbeitsgemeinschaft Für Osteosynthesefragen (AO) Principles for Long Bone Fractures Applicable to 3-Column Osteotomy to Reduce Rod Fracture Rates?(Clinical spine surgery, 2022-06) Virk, Sohrab; Lafage, Renaud; Bess, Shay; Shaffrey, Christopher; Kim, Han J; Ames, Christopher; Burton, Doug; Gupta, Munish; Smith, Justin S; Eastlack, Robert; Klineberg, Eric; Mundis, Gregory; Schwab, Frank; Lafage, Virginie; International Spine Study GroupObjective
The aim was to determine whether applying Arbeitsgemeinschaft für Osteosynthesefragen (AO) principles for external fixation of long bone fracture to patients with a 3-column osteotomy (3CO) would be associated with reduced rod fracture (RF) rates.Summary of background data
AO dictate principles to follow when fixating long bone fractures: (1) decrease bone-rod distance; (2) increase the number of connecting rods; (3) increase the diameter of rods; (4) increase the working length of screws; (5) use multiaxial fixation. We hypothesized that applying these principles to patients undergoing a 3CO reduces the rate of RF.Methods
Patients were categorized as having RF versus no rod fracture (non-RF). Details on location and type of instrumentation were collected. Dedicated software was used to calculate the distance between osteotomy site and adjacent pedicle screws, angle between screws and the distance between the osteotomy site and rod. Classic sagittal spinopelvic parameters were evaluated.Results
The study included 170 patients (34=RF, 136=non-RF). There was no difference in age (P=0.224), sagittal vertical axis correction (P=0.287), or lumbar lordosis correction (P=0.36). There was no difference in number of screws cephalad (P=0.62) or caudal (P=0.31) to 3CO site. There was a lower rate of RF for patients with >2 rods versus 2 rods (P<0.001). Patients with multiplanar rod fixation had a lower rod fracture rate (P=0.01). For patients with only 2 rods (N=68), the non-RF cohort had adjacent screws that trended to have less angulation to each other (P=0.06) and adjacent screws that had a larger working length (P=0.03).Conclusions
A portion of AO principles can be applied to 3CO to reduce RF rates. Placing more rods around a 3CO site, placing rods in multiple planes, and placing adjacent screws with a larger working length around the 3CO site is associated with lower RF rates.Item Open Access Artificial intelligence clustering of adult spinal deformity sagittal plane morphology predicts surgical characteristics, alignment, and outcomes.(European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, 2021-08) Durand, Wesley M; Lafage, Renaud; Hamilton, D Kojo; Passias, Peter G; Kim, Han Jo; Protopsaltis, Themistocles; Lafage, Virginie; Smith, Justin S; Shaffrey, Christopher; Gupta, Munish; Kelly, Michael P; Klineberg, Eric O; Schwab, Frank; Gum, Jeffrey L; Mundis, Gregory; Eastlack, Robert; Kebaish, Khaled; Soroceanu, Alex; Hostin, Richard A; Burton, Doug; Bess, Shay; Ames, Christopher; Hart, Robert A; Daniels, Alan H; International Spine Study Group (ISSG)Purpose
AI algorithms have shown promise in medical image analysis. Previous studies of ASD clusters have analyzed alignment metrics-this study sought to complement these efforts by analyzing images of sagittal anatomical spinopelvic landmarks. We hypothesized that an AI algorithm would cluster preoperative lateral radiographs into groups with distinct morphology.Methods
This was a retrospective review of a multicenter, prospectively collected database of adult spinal deformity. A total of 915 patients with adult spinal deformity and preoperative lateral radiographs were included. A 2 × 3, self-organizing map-a form of artificial neural network frequently employed in unsupervised classification tasks-was developed. The mean spine shape was plotted for each of the six clusters. Alignment, surgical characteristics, and outcomes were compared.Results
Qualitatively, clusters C and D exhibited only mild sagittal plane deformity. Clusters B, E, and F, however, exhibited marked positive sagittal balance and loss of lumbar lordosis. Cluster A had mixed characteristics, likely representing compensated deformity. Patients in clusters B, E, and F disproportionately underwent 3-CO. PJK and PJF were particularly prevalent among clusters A and E. Among clusters B and F, patients who experienced PJK had significantly greater positive sagittal balance than those who did not.Conclusions
This study clustered preoperative lateral radiographs of ASD patients into groups with highly distinct overall spinal morphology and association with sagittal alignment parameters, baseline HRQOL, and surgical characteristics. The relationship between SVA and PJK differed by cluster. This study represents significant progress toward incorporation of computer vision into clinically relevant classification systems in adult spinal deformity.Level of evidence iv
Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.Item Open Access Artificial Intelligence Models Predict Operative Versus Nonoperative Management of Patients with Adult Spinal Deformity with 86% Accuracy.(World neurosurgery, 2020-09) Durand, Wesley M; Daniels, Alan H; Hamilton, David K; Passias, Peter; Kim, Han Jo; Protopsaltis, Themistocles; LaFage, Virginie; Smith, Justin S; Shaffrey, Christopher; Gupta, Munish; Klineberg, Eric; Schwab, Frank; Burton, Doug; Bess, Shay; Ames, Christopher; Hart, Robert; International Spine Study GroupObjective
Patients with ASD show complex and highly variable disease. The decision to manage patients operatively is largely subjective and varies based on surgeon training and experience. We sought to develop models capable of accurately discriminating between patients receiving operative versus nonoperative treatment based only on baseline radiographic and clinical data at enrollment.Methods
This study was a retrospective analysis of a multicenter consecutive cohort of patients with ASD. A total of 1503 patients were included, divided in a 70:30 split for training and testing. Patients receiving operative treatment were defined as those undergoing surgery up to 1 year after their baseline visit. Potential predictors included available demographics, past medical history, patient-reported outcome measures, and premeasured radiographic parameters from anteroposterior and lateral films. In total, 321 potential predictors were included. Random forest, elastic net regression, logistic regression, and support vector machines (SVMs) with radial and linear kernels were trained.Results
Of patients in the training and testing sets, 69.0% (n = 727) and 69.1% (n = 311), respectively, received operative management. On evaluation with the testing dataset, performance for SVM linear (area under the curve =0.910), elastic net (0.913), and SVM radial (0.914) models was excellent, and the logistic regression (0.896) and random forest (0.830) models performed very well for predicting operative management of patients with ASD. The SVM linear model showed 86% accuracy.Conclusions
This study developed models showing excellent discrimination (area under the curve >0.9) between patients receiving operative versus nonoperative management, based solely on baseline study enrollment values. Future investigations may evaluate the implementation of such models for decision support in the clinical setting.Item Open Access Assessment of Patient Outcomes and Proximal Junctional Failure Rate of Adult Spinal Deformity Patients Undergoing Caudal Extension of Previous Spinal Fusion.(World neurosurgery, 2020-04-16) Daniels, Alan H; Reid, Daniel BC; Durand, Wesley M; Line, Breton; Passias, Peter; Kim, Han Jo; Protopsaltis, Themistocles; LaFage, Virginie; Smith, Justin S; Shaffrey, Christopher; Gupta, Munish; Klineberg, Eric; Schwab, Frank; Burton, Doug; Bess, Shay; Ames, Christopher; Hart, Robert A; International Spine Study GroupOBJECT:This case series examined patients undergoing caudal extension of prior fusion without alteration of the prior UIV to assess patient outcomes and rates of PJK/PJF. METHODS:Patients eligible for 2-year minimum follow-up undergoing caudal extension of prior fusion with unchanged UIVs were identified. These patients were evaluated for PJK/PJF, and patient reported outcomes were recorded. RESULTS:In total, 40 patients were included. Mean follow-up duration was 2.2 years (SD 0.3). Patients in this cohort had poor preoperative sagittal alignment (PI-LL 26.7°, TPA 29.0°, SVA 93.4mm) and achieved substantial sagittal correction (ΔSVA -62.2mm, ΔPI-LL -19.8°, ΔTPA -11.1°) following caudal extension surgery. At final follow-up, there was a 0% rate of PJF among patients undergoing caudal extension of previous fusion without creation of a new UIV, but 27.5% of patients experienced PJK. Patients experienced significant improvement in both ODI and SRS-22r total score at 2-years post-operatively (p<0.05). In total, 7.5% (n=3) of patients underwent further revision, at an average of 1.1 years (SD 0.54) after the surgery with unaltered UIV. All three of these patients underwent revision for rod fracture with no revisions for PJK/PJF. CONCLUSIONS:Patients undergoing caudal extension of previous fusions for sagittal alignment correction have high rates of clinical success, low revision surgery rates, and very low rates of PJF. Minimizing repetitive tissue trauma at the UIV may result in decreased PJF risk, as the PJF rate in this cohort of unaltered UIV patients is below historical PJF rates of patients undergoing sagittal balance correction.Item Open Access Author Correction: Sagittal age-adjusted score (SAAS) for adult spinal deformity (ASD) more effectively predicts surgical outcomes and proximal junctional kyphosis than previous classifications.(Spine deformity, 2023-03) Lafage, Renaud; Smith, Justin S; Elysee, Jonathan; Passias, Peter; Bess, Shay; Klineberg, Eric; Kim, Han Jo; Shaffrey, Christopher; Burton, Douglas; Hostin, Richard; Mundis, Gregory; Ames, Christopher; Schwab, Frank; Lafage, Virginie; International Spine Study Group (ISSG)In Fig. 4 of this article signs for points associated in all 3 components are incorrect and should be reversed, e.g. + 2 should be − 2 and vise versa; Fig. 4 should have appeared as shown below. The original article has been correctedItem Open Access Baseline Frailty Status Influences Recovery Patterns and Outcomes Following Alignment Correction of Cervical Deformity.(Neurosurgery, 2021-05) Pierce, Katherine E; Passias, Peter G; Daniels, Alan H; Lafage, Renaud; Ahmad, Waleed; Naessig, Sara; Lafage, Virginie; Protopsaltis, Themistocles; Eastlack, Robert; Hart, Robert; Burton, Douglas; Bess, Shay; Schwab, Frank; Shaffrey, Christopher; Smith, Justin S; Ames, ChristopherBackground
Frailty severity may be an important determinant for impaired recovery after cervical spine deformity (CD) corrective surgery.Objective
To evaluate postop clinical recovery among CD patients between frailty states undergoing primary procedures.Methods
Patients >18 yr old undergoing surgery for CD with health-related quality of life (HRQL) data at baseline, 3-mo, and 1-yr postoperative were identified. Patients were stratified by the modified CD frailty index scale from 0 to 1 (no frailty [NF] <0.3, mild/severe fraily [F] >0.3). Patients in NF and F groups were propensity score matched for TS-CL (T1 slope [TS] minus angle between the C2 inferior end plate and the C7 inferior end plate [CL]) to control for baseline deformity. Area under the curve was calculated for follow-up time intervals determining overall normalized, time-adjusted HRQL outcomes; Integrated Health State (IHS) was compared between NF and F groups.Results
A total of 106 CD patients were included (61.7 yr, 66% F, 27.7 kg/m2)-by frailty group: 52.8% NF, 47.2% F. After propensity score matching for TS-CL (mean: 38.1°), 38 patients remained in each of the NF and F groups. IHS-adjusted HRQL outcomes from baseline to 1 yr showed a significant difference in Euro-Qol 5 Dimension scores (NF: 1.02, F: 1.07, P = .016). No significant differences were found in the IHS Neck Disability Index (NDI) and modified Japanese Orthopedic Association between frailty groups (P > .05). F patients had more postop major complications (31.3%) compared to the NF (8.9%), P = .004, though DJK occurrence and reoperation between the groups was not significant.Conclusion
While all groups exhibited improved postop disability and pain scores, frail patients experienced greater amount of improvement in overall health state compared to baseline disability. This signifies that with frailty severity, patients have more room for improvement postop compared to baseline quality of life.Item Open Access Benchmark Values for Construct Survival and Complications by Type of ASD Surgery.(Spine, 2024-04) Bass, Robert Daniel; Lafage, Renaud; Smith, Justin S; Ames, Christopher; Bess, Shay; Eastlack, Robert; Gupta, Munish; Hostin, Richard; Kebaish, Khaled; Kim, Han Jo; Klineberg, Eric; Mundis, Gregory; Okonkwo, David; Shaffrey, Christopher; Schwab, Frank; Lafage, Virginie; Burton, Douglas; International Spine Study GroupObjective
Provide benchmarks for the rates of complications by type of surgery performed.Study design
Prospective multicenter database.Background
We have previously examined overall construct survival and complication rates for ASD surgery. However, the relationship between type of surgery and construct survival warrants more detailed assessment.Methods
Eight surgical scenarios were defined based on the levels treated, previous fusion status (primary [P] vs. revision [R]), and 3-column osteotomy use [3CO]: Short Lumbar fusion, LT-Pelvis with 5-12 levels treated (P, R or 3CO), UT-Pelvis with 13 levels treated (P, R or 3CO), and Thoracic to Lumbar fusion without pelvic fixation, representing 92.4% of the case in the cohort. Complication rates for each type were calculated and Kaplan Meier curves with multivariate Cox regression analysis was used to evaluate the effect of the case characteristics on construct survival rate, while controlling for patient profile.Results
1073 of 1494 patients eligible for 2-year follow-up (71.8%) were captured. Survival curves for major complications (with or without reoperation), while controlling for demographics differed significantly among surgical types (P<0.001). Fusion procedures short of the pelvis had the best survival rate, while UT-Pelvis with 3CO had the worst survival rate. Longer fusions and more invasive operations were associated with lower 2-year complication-free survival, however there were no significant associations between type of surgery and renal, cardiac, infection, wound, gastrointestinal, pulmonary, implant malposition or neurologic complications (all P>0.5).Conclusion
This study suggests that there is an inherent increased risk of complication for some types of ASD surgery independent of patient profile. The results of this paper can be used to produce a surgery-adjusted benchmark for ASD surgery with regard to complications and survival. Such a tool can have very impactful applications for surgical decision making and more informed patient counseling.Item Open Access Cervical mismatch: the normative value of T1 slope minus cervical lordosis and its ability to predict ideal cervical lordosis.(Journal of neurosurgery. Spine, 2018-10) Staub, Blake N; Lafage, Renaud; Kim, Han Jo; Shaffrey, Christopher I; Mundis, Gregory M; Hostin, Richard; Burton, Douglas; Lenke, Lawrence; Gupta, Munish C; Ames, Christopher; Klineberg, Eric; Bess, Shay; Schwab, Frank; Lafage, Virginie; International Spine Study GroupOBJECTIVE: Numerous studies have attempted to delineate the normative value for T1S-CL (T1 slope minus cervical lordosis) as a marker for both cervical deformity and a goal for correction similar to how PI-LL (pelvic incidence-lumbar lordosis) mismatch informs decision making in thoracolumbar adult spinal deformity (ASD). The goal of this study was to define the relationship between T1 slope (T1S) and cervical lordosis (CL). METHODS: This is a retrospective review of a prospective database. Surgical ASD cases were initially analyzed. Analysis across the sagittal parameters was performed. Linear regression analysis based on T1S was used to provide a clinically applicable equation to predict CL. Findings were validated using the postoperative alignment of the ASD patients. Further validation was then performed using a second, normative database. The range of normal alignment associated with horizontal gaze was derived from a multilinear regression on data from asymptomatic patients. RESULTS: A total of 103 patients (mean age 54.7 years) were included. Analysis revealed a strong correlation between T1S and C0-7 lordosis (r = 0.886), C2-7 lordosis (r = 0.815), and C0-2 lordosis (r = 0.732). There was no significant correlation between T1S and T1S-CL. Linear regression analysis revealed that T1S-CL assumed a constant value of 16.5° (R2 = 0.664, standard error 2°). These findings were validated on the postoperative imaging (mean absolute error [MAE] 5.9°). The equation was then applied to the normative database (MAE 6.7° controlling for McGregor slope [MGS] between -5° and 15°). A multilinear regression between C2-7, T1S, and MGS demonstrated a range of T1S-CL between 14.5° and 26.5° was necessary to maintain horizontal gaze. CONCLUSIONS: Normative CL can be predicted via the formula CL = T1S - 16.5° ± 2°. This implies a threshold of deformity and aids in providing a goal for surgical correction. Just as pelvic incidence (PI) can be used to determine the ideal LL, T1S can be used to predict ideal CL. This formula also implies that a kyphotic cervical alignment is to be expected for individuals with a T1S < 16.5°.Item Open Access Cervical sagittal deformity develops after PJK in adult thoracolumbar deformity correction: radiographic analysis utilizing a novel global sagittal angular parameter, the CTPA.(European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, 2017-04) Protopsaltis, Themistocles; Bronsard, Nicolas; Soroceanu, Alex; Henry, Jensen K; Lafage, Renaud; Smith, Justin; Klineberg, Eric; Mundis, Gregory; Kim, Han Jo; Hostin, Richard; Hart, Robert; Shaffrey, Christopher; Bess, Shay; Ames, Christopher; International Spine Study GroupPurpose
To describe reciprocal changes in cervical alignment after adult spinal deformity (ASD) correction and subsequent development of proximal junctional kyphosis (PJK). This study also investigated these changes using two novel global sagittal angular parameters, cervical-thoracic pelvic angle (CTPA) and the T1 pelvic angle (TPA).Methods
Multicenter, retrospective consecutive case series of ASD patients undergoing thoracolumbar three-column osteotomy (3CO) with fusion to the pelvis. Radiographs were analyzed at baseline and 1 year post-operatively. Patients were substratified into upper thoracic (UT; UIV T6 and above) and lower thoracic (LT; UIV below T6). PJK was defined by >10° angle between UIV and UIV + 2 and >10° change in the angle from baseline to post-op.Results
PJK developed in 29 % (78 of 267) of patients. CTPA was linearly correlated with cervical plumbline (CPL) as a measure of cervical sagittal alignment (R = 0.826, p < 0.001). PJK patients had significantly greater post-operative CTPA and SVA than patients without PJK (NPJK) (p = 0.042; p = 0.021). For UT (n = 141) but not LT (n = 136), PJK patients at 1 year had larger CTPA (4.9° vs. 3.7°, p = 0.015) and CPL (5.1 vs. 3.8 cm, p = 0.022) than NPJK patients, despite similar corrections in PT and PI-LL.Conclusions
The prevalence of PJK was 29 % at 1 year follow-up. CTPA, which correlates with CPL as a global analog of cervical sagittal balance, and TPA describe relative proportions of cervical and thoracolumbar deformities. Patients who develop PJK in the upper thoracic spine after thoracolumbar 3CO also develop concomitant cervical sagittal deformity, with increases in CPL and CTPA.Item Open Access Cervical Versus Thoracolumbar Spinal Deformities: A Comparison of Baseline Quality-of-Life Burden.(Clinical spine surgery, 2018-12) Passias, Peter G; Poorman, Gregory W; Lafage, Virginie; Smith, Justin; Ames, Christopher; Schwab, Frank; Shaffrey, Chris; Segreto, Frank A; Horn, Samantha R; Bortz, Cole A; Varlotta, Christopher G; Hockley, Aaron; Wang, Charles; Daniels, Alan; Neuman, Brian; Hart, Robert; Burton, Douglas; Javidan, Yashar; Line, Breton; LaFage, Renaud; Bess, Shay; Sciubba, Daniel; ISSGStudy design
Retrospective analysis of 2 prospectively collected multicenter databases, one for cervical deformity (CD) and the other for general adult spinal deformity.Objective
To investigate the relative quality-of-life and disability burden in patients with uncompensated cervical, thoracolumbar, or cervical and thoracolumbar deformities.Summary of background data
The relative quality-of-life burden of cervical and thoracolumbar deformities have never been compared with each other. This may have significant implications when deciding on the appropriate treatment intervention for patients with combined thoracolumbar and cervical deformities.Methods
When defining CD C2-C7 sagittal vertical axis (SVA)>4 cm was used while a C7-S1 SVA>5 cm was used to defined thoracolumbar deformity. Patients with both SVA criteria were defined as "combined." Primary analysis compared patients in the different groups by demographic, comorbidity data, and quality-of-life scores [EuroQOL 5 dimensions questionnaire (EQ-5D)] using t tests. Secondary analysis matched deformity groups with propensity scores matching based on baseline EQ-5D scores. Differences in disease-specific metrics [the Oswestry Disability Index, Neck Disability Index, modified Japanese Orthopaedic Association questionnaire (mJOA)] were analyzed using analysis of variance tests and post hoc analysis.Results
In total, 212 patients were included in our analysis. Patients with CD only had less neurological deficits (mJOA: 14.6) and better EQ-5D (0.746) scores compared with patients with combined deformities (11.9, 0.716), all P<0.05. Regarding propensity score-matched deformity cohorts, 99 patients were matched with similar quality-of-life burden, 33 per deformity cohort. CD only patients had fewer comorbidities (1.03 vs. 2.12 vs. 2.70; P<0.001), whereas patients with combined deformity had more baseline neurological impairment compared with CD only patients (mJOA: 12.00 vs. 14.25; P=0.050).Conclusions
Combined deformity patients were associated with the lowest quality-of-life and highest disability. Furthermore, regarding deformity cohorts matched by similar baseline quality-of-life status (EQ-5D), patients with combined deformities were associated with significantly worse neurological impairments. This finding implies that quality of life may not be a direct reflection of a patient's disability status, especially in patients with combined cervical and thoracolumbar deformities.Level of evidence
Level III.Item Open Access Changes in thoracic kyphosis negatively impact sagittal alignment after lumbar pedicle subtraction osteotomy: a comprehensive radiographic analysis.(Spine, 2012-02) Lafage, Virginie; Ames, Christopher; Schwab, Frank; Klineberg, Eric; Akbarnia, Behrooz; Smith, Justin; Boachie-Adjei, Oheneba; Burton, Douglas; Hart, Robert; Hostin, Richard; Shaffrey, Christopher; Wood, Kirkham; Bess, Shay; International Spine Study GroupStudy design
Consecutive, multicenter retrospective review.Objective
To evaluate if change in thoracic kyphosis (TK) has a positive or negative impact on spinopelvic alignment after lumbar pedicle subtraction osteotomy (PSO) with short fusions.Summary of background data
In the setting of sagittal malalignment, the effect of large vertebral resections can now be anticipated in long fusions, but their impact on unfused segments (reciprocal changes [RC]) remains poorly understood.Methods
A total of 34 adult patients (mean age = 54 years; SD = 12) who underwent lumbar PSO with upper instrumented vertebra below T10 were included. Radiographic analysis included pre- and postassessment of TK, lumbar lordosis (LL), sagittal vertical axis (SVA), T1 spinopelvic inclination (T1SPI), pelvic tilt (PT), and pelvic incidence (PI). Final SVA and PT were analyzed to determine successful realignment. RC in the thoracic spine was designated favorable or unfavorable on the basis of impact on final SVA and PT.Results
Mean PSO resection was 26°. LL increased from 20° to 49° (P < 0.001). SVA improved from 14 to 4 cm (P < 0.001), and PT improved from 33° to 25° (P < 0.001). Mean increase in TK was 13° (P = 0.002) but was unchanged in 11 patients. Five patients had a favorable RC, and 18 patients had an unfavorable RC. Unfavorable RC was attributed to junctional failure in 6 of 18 patients. Significant differences in the unfavorable RC group included age and greater preoperative PT, PI, SVA, and T1SPI.Conclusion
Significant postoperative alignment changes can occur through unfused thoracic spinal segments after lumbar PSO. Unfavorable RC may limit optimal correction and lead to clinical failures. Risk factors for unfavorable thoracic RC include older patients, larger preoperative PI and PT, and worse preoperative T1SPI and are not simply due to junctional failure. Care should be taken with selective lumbar fusion and PSO in older patients and in those with severe preoperative spinopelvic parameters.Item Open Access Clinical and radiographic presentation and treatment of patients with cervical deformity secondary to thoracolumbar proximal junctional kyphosis are distinct despite achieving similar outcomes: Analysis of 123 prospective CD cases.(Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia, 2018-10) Passias, Peter G; Horn, Samantha R; Poorman, Gregory W; Daniels, Alan H; Hamilton, D Kojo; Kim, Han Jo; Diebo, Bassel G; Steinmetz, Leah; Bortz, Cole A; Segreto, Frank A; Sciubba, Daniel M; Smith, Justin S; Neuman, Brian J; Shaffrey, Christopher I; Lafage, Renaud; Lafage, Virginie; Ames, Christopher; Hart, Robert; Mundis, Gregory; Eastlack, Robert K; Schwab, Frank J; International Spine Study Group (ISSG)CD development secondary to PJK was recently documented in adult spinal deformity patients after surgical correction for thoracolumbar ASD. This study analyzes surgical management of patients with CD secondary to proximal junctional kyphosis (PJK) versus patients with primary CD. Retrospective review of multicenter cervical deformity (CD) database. CD defined as at least one of the following: C2-C7 coronal Cobb > 10°, cervical lordosis (CL) > 10°, cervical sagittal vertical axis (cSVA) > 4cm, CBVA > 25°. Patients were grouped into those with PJK (UIV +2 < -10°) prior to cervical surgery versus who don't (Non-PJK). Independent t-tests and chi-squared tests compared radiographic, clinical, and surgical metrics between PJK and non-PJK groups. Of 123 eligible CD patients, 26(21.1%) had radiographic PJK prior to cervical surgery. PJK patients had significantly greater T2-T12 thoracic kyphosis (-58.8° vs -45.0°, p = 0.002), cSVA (49.1 mm vs 38.9 mm, p = 0.020), T1 Slope (42.6° vs 28.4°, p < 0.001), TS-CL (44.1° vs 35.6°, p = 0.048), C2-T3 SVA (98.8 mm vs 75.8 mm, p = 0.015), C2 Slope (45.4° vs 36.0°, p = 0.043), and CTPA (6.4° vs 4.6°, p = 0.005). Comparing their surgeries, the PJK group had significantly more levels fused (10.7 vs 7.4, p = 0.01). There was significantly greater blood loss in PJK patients (1158 ± 1063vs 738 ± 793 cc, p = 0.028); operative time, surgical approach, and BMP-2 use were similar (all p > 0.05). PJK patients experienced higher rates of complications 30 and 90 days post-operatively (23.1% vs. 5.2%, p = 0.004; 30.8% vs. 19.6%, p = 0.026), and more instrumentation failure 30 days postoperatively (7.8% vs. 1.0%, p = 0.004). Patients with cervical deformity secondary to PJK had worse baseline CD, despite no differences in HRQL or demographics. Surgical correction of CD associated with PJK required more invasive surgery and had higher complication rates than non-PJK patients, despite achieving similar clinical outcomes.