Browsing by Author "LaFage, Virginie"

Now showing 1 - 14 of 14
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    ItemOpen 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 Group

    Objective

    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.
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    ItemOpen 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 Group
    OBJECT: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.
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    ItemOpen Access
    Cell Saver for Adult Spinal Deformity Surgery Reduces Cost.
    (Spine deformity, 2017-07) Gum, Jeffrey L; Carreon, Leah Yacat; Kelly, Michael P; Hostin, Richard; Robinson, Chessie; Burton, Douglas C; Polly, David W; Shaffrey, Christopher I; LaFage, Virginie; Schwab, Frank J; Ames, Christopher P; Kim, Han Jo; Smith, Justin S; Bess, R Shay; International Spine Study Group

    Study design

    Retrospective cohort.

    Objectives

    To determine if the use of cell saver reduces overall blood costs in adult spinal deformity (ASD) surgery.

    Summary of background data

    Recent studies have questioned the clinical value of cell saver during spine procedures.

    Methods

    ASD patients enrolled in a prospective, multicenter surgical database who had complete preoperative and surgical data were identified. Patients were stratified into (1) cell saver available during surgery, but no intraoperative autologous infusion (No Infusion group), or (2) cell saver available and received autologous infusion (Infusion group).

    Results

    There were 427 patients in the Infusion group and 153 in the No infusion group. Patients in both groups had similar demographics. Mean autologous infusion volume was 698 mL. The Infusion group had a higher percentage of EBL relative to the estimated blood volume (42.2%) than the No Infusion group (19.6%, p < .000). Allogeneic transfusion was more common in the Infusion group (255/427, 60%) than the No Infusion group (67/153, 44%, p = .001). The number of allogeneic blood units transfused was also higher in the Infusion group (2.4) than the No Infusion group (1.7, p = .009). Total blood costs ranged from $396 to $2,146 in the No Infusion group and from $1,262 to $5,088 in the Infusion group. If the cost of cell saver blood was transformed into costs of allogeneic blood, total blood costs for the Infusion group would range from $840 to $5,418. Thus, cell saver use yielded a mean cost savings ranging from $330 to $422 (allogeneic blood averted). Linear regression showed that after an EBL of 614 mL, cell saver becomes cost-efficient.

    Conclusion

    Compared to transfusing allogeneic blood, cell saver autologous infusion did not reduce the proportion or the volume of allogeneic transfusion for patients undergoing surgery for adult spinal deformity. The use of cell saver becomes cost-efficient above an EBL of 614 mL, producing a cost savings of $330 to $422.

    Level of evidence

    Level III.
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    ItemOpen Access
    Cost-utility analysis of cervical deformity surgeries using 1-year outcome.
    (The spine journal : official journal of the North American Spine Society, 2018-09) Poorman, Gregory W; Passias, Peter G; Qureshi, Rabia; Hassanzadeh, Hamid; Horn, Samantha; Bortz, Cole; Segreto, Frank; Jain, Amit; Kelly, Michael; Hostin, Richard; Ames, Christopher; Smith, Justin; LaFage, Virginie; Burton, Douglas; Bess, Shay; Shaffrey, Chris; Schwab, Frank; Gupta, Munish

    Background context

    Cost-utility analysis, a special case of cost-effectiveness analysis, estimates the ratio between the cost of an intervention to the benefit it produces in number of quality-adjusted life years. Cervical deformity correction has not been evaluated in terms of cost-utility and in the context of value-based health care. Our objective, therefore, was to determine the cost-utility ratio of cervical deformity correction.

    Study design

    This is a retrospective review of a prospective, multicenter cervical deformity database. Patients with 1-year follow-up after surgical correction for cervical deformity were included. Cervical deformity was defined as the presence of at least one of the following: kyphosis (C2-C7 Cobb angle >10°), cervical scoliosis (coronal Cobb angle >10°), positive cervical sagittal malalignment (C2-C7 sagittal vertical axis >4 cm or T1-C6 >10°), or horizontal gaze impairment (chin-brow vertical angle >25°). Quality-adjusted life years were calculated by both EuroQol 5D (EQ5D) quality of life and Neck Disability Index (NDI) mapped to short form six dimensions (SF6D) index. Costs were assigned using Medicare 1-year average reimbursement for: 9+ level posterior fusions (PF), 4-8 level PF, 4-8 level PF with anterior fusion (AF), 2-3 level PF with AF, 4-8 level AF, and 4-8 level posterior refusion. Reoperations and deaths were added to cost and subtracted from utility, respectively. Quality-adjusted life year per dollar spent was calculated using standardized methodology at 1-year time point and subsequent time points relying on maintenance of 1-year utility.

    Results

    Eighty-four patients (average age: 61.2 years, 60% female, body mass index [BMI]: 30.1) were analyzed after cervical deformity correction (average levels fused: 7.2, osteotomy used: 50%). Costs associated with index procedures were 9+ level PF ($76,617), 4-8 level PF ($40,596), 4-8 level PF with AF ($67,098), 4-8 level AF ($31,392), and 4-8 level posterior refusion ($35,371). Average 1-year reimbursement of surgery was $55,097 at 1 year with eight revisions and three deaths accounted for. Cost per quality-adjusted life year (QALY) gained to 1-year follow-up was $646,958 by EQ5D and $477,316 by NDI SF6D. If 1-year benefit is sustained, upper threshold of cost-effectiveness is reached 3-4.5 years after intervention.

    Conclusions

    Medicare 1-year average reimbursement compared with 1-year QALYdescribed $646,958 by EQ5D and $477,316 by NDI SF6D. Cervical deformity surgeries reach accepted cost-effectiveness thresholds when benefit is sustained 3-4.5 years. Longer follow-up is needed for a more definitive cost-analysis, but these data are an important first step in justifying cost-utility ratio for cervical deformity correction.
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    ItemOpen Access
    Despite worse baseline status depressed patients achieved outcomes similar to those in nondepressed patients after surgery for cervical deformity.
    (Neurosurgical focus, 2017-12) Poorman, Gregory W; Passias, Peter G; Horn, Samantha R; Frangella, Nicholas J; Daniels, Alan H; Hamilton, D Kojo; Kim, Hanjo; Sciubba, Daniel; Diebo, Bassel G; Bortz, Cole A; Segreto, Frank A; Kelly, Michael P; Smith, Justin S; Neuman, Brian J; Shaffrey, Christopher I; LaFage, Virginie; LaFage, Renaud; Ames, Christopher P; Hart, Robert; Mundis, Gregory M; Eastlack, Robert; International Spine Study Group
    OBJECTIVE Depression and anxiety have been demonstrated to have negative impacts on outcomes after spine surgery. In patients with cervical deformity (CD), the psychological and physiological burdens of the disease may overlap without clear boundaries. While surgery has a proven record of bringing about significant pain relief and decreased disability, the impact of depression and anxiety on recovery from cervical deformity corrective surgery has not been previously reported on in the literature. The purpose of the present study was to determine the effect of depression and anxiety on patients' recovery from and improvement after CD surgery. METHODS The authors conducted a retrospective review of a prospective, multicenter CD database. Patients with a history of clinical depression, in addition to those with current self-reported anxiety or depression, were defined as depressed (D group). The D group was compared with nondepressed patients (ND group) with a similar baseline deformity determined by propensity score matching of the cervical sagittal vertical axis (cSVA). Baseline demographic, comorbidity, clinical, and radiographic data were compared among patients using t-tests. Improvement of symptoms was recorded at 3 months, 6 months, and 1 year postoperatively. All health-related quality of life (HRQOL) scores collected at these follow-up time points were compared using t-tests. RESULTS Sixty-six patients were matched for baseline radiographic parameters: 33 with a history of depression and/or current depression, and 33 without. Depressed patients had similar age, sex, race, and radiographic alignment: cSVA, T-1 slope minus C2-7 lordosis, SVA, and T-1 pelvic angle (p > 0.05). Compared with nondepressed individuals, depressed patients had a higher incidence of osteoporosis (21.2% vs 3.2%, p = 0.028), rheumatoid arthritis (18.2% vs 3.2%, p = 0.012), and connective tissue disorders (18.2% vs 3.2%, p = 0.012). At baseline, the D group had greater neck pain (7.9 of 10 vs 6.6 on a Numeric Rating Scale [NRS], p = 0.015), lower mean EQ-5D scores (68.9 vs 74.7, p < 0.001), but similar Neck Disability Index (NDI) scores (57.5 vs 49.9, p = 0.063) and myelopathy scores (13.4 vs 13.9, p = 0.546). Surgeries performed in either group were similar in terms of number of levels fused, osteotomies performed, and correction achieved (baseline to 3-month measurements) (p < 0.05). At 3 months, EQ-5D scores remained lower in the D group (74.0 vs 78.2, p = 0.044), and NDI scores were similar (48.5 vs 39.0, p = 0.053). However, neck pain improved in the D group (NRS score of 5.0 vs 4.3, p = 0.331), and modified Japanese Orthopaedic Association (mJOA) scores remained similar (14.2 vs 15.0, p = 0.211). At 6 months and 1 year, all HRQOL scores were similar between the 2 cohorts. One-year measurements were as follows: NDI 39.7 vs 40.7 (p = 0.878), NRS neck pain score of 4.1 vs 5.0 (p = 0.326), EQ-5D score of 77.1 vs 78.2 (p = 0.646), and mJOA score of 14.0 vs 14.2 (p = 0.835). Anxiety/depression levels reported on the EQ-5D scale were significantly higher in the depressed cohort at baseline, 3 months, and 6 months (all p < 0.05), but were similar between groups at 1 year postoperatively (1.72 vs 1.53, p = 0.416). CONCLUSIONS Clinical depression was observed in many of the study patients with CD. After matching for baseline deformity, depression symptomology resulted in worse baseline EQ-5D and pain scores. Despite these baseline differences, both cohorts achieved similar results in all HRQOL assessments 6 months and 1 year postoperatively, demonstrating no clinical impact of depression on recovery up until 1 year after CD surgery. Thus, a history of depression does not appear to have an impact on recovery from CD surgery.
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    ItemOpen Access
    Effect of Obesity on Radiographic Alignment and Short-Term Complications After Surgical Treatment of Adult Cervical Deformity.
    (World neurosurgery, 2019-05) Passias, Peter G; Poorman, Gregory W; Horn, Samantha R; Jalai, Cyrus M; Bortz, Cole; Segreto, Frank; Diebo, Bassel M; Daniels, Alan; Hamilton, D Kojo; Sciubba, Daniel; Smith, Justin; Neuman, Brian; Shaffrey, Christopher I; LaFage, Virginie; LaFage, Renaud; Schwab, Frank; Bess, Shay; Ames, Christopher; Hart, Robert; Soroceanu, Alexandra; Mundis, Gregory; Eastlack, Robert; International Spine Study Group

    Objective

    We investigated the 30-day complication incidence and 1-year radiographic correction in obese patients undergoing surgical treatment of cervical deformity.

    Methods

    The patients were stratified according to World Health Organization's definition for obesity: obese, patients with a body mass index of ≥30 kg/m2; and nonobese, patients with a body mass index of <30 kg/m2. The patients had undergone surgery for the treatment of cervical deformity. The patient baseline demographic, comorbidity, and radiographic data were compared between the 2 groups at baseline and 1 year postoperatively. The 30-day complication incidence was stratified according to complication severity (any, major, or minor), and type (cardiopulmonary, dysphagia, infection, neurological, and operative). Binary logistic regression models were used to assess the effect of obesity on developing those complications, with adjustment for patient age and levels fused.

    Results

    A total of 124 patients were included, 53 obese and 71 nonobese patients. The 2 groups had a similar T1 slope minus cervical lordosis (obese, 37.2° vs. nonobese, 36.9°; P = 0.932) and a similar C2-C7 (-5.9° vs. -7.3°; P = 0.718) and C2-C7 (50.1 mm vs. 44.1 mm; P = 0.184) sagittal vertical axis. At the 1-year follow-up examination, the T1 pelvic angle (1.0° vs. -3.1°; P = 0.021) and C2-S1 sagittal vertical axis (-5.9 mm vs. -35.0 mm; P = 0.036) were different, and the T1 spinopelvic inclination (-1.0° vs. -2.9°; P = 0.123) was similar. The obese patients had a greater risk of overall short-term complications (odds ratio, 2.5; 95% confidence interval, 1.1-6.1) and infectious complications (odds ratio, 5.0; 95% confidence interval, 1.0-25.6).

    Conclusions

    Obese patients had a 5 times greater odds of developing infections after surgery for adult cervical deformity. Obese patients also showed significantly greater pelvic anteversion after cervical correction.
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    ItemOpen Access
    Evolution in Surgical Approach, Complications, and Outcomes in an Adult Spinal Deformity Surgery Multicenter Study Group Patient Population.
    (Spine deformity, 2019-05) Daniels, Alan H; Reid, Daniel BC; Tran, Stacie Nguyen; Hart, Robert A; Klineberg, Eric O; Bess, Shay; Burton, Douglas; Smith, Justin S; Shaffrey, Christopher; Gupta, Munish; Ames, Christopher P; Hamilton, D Kojo; LaFage, Virginie; Schwab, Frank; Eastlack, Robert; Akbarnia, Behrooz; Kim, Han Jo; Kelly, Michael; Passias, Peter G; Protopsaltis, Themistocles; Mundis, Gregory M; International Spine Study Group

    Study design

    Retrospective review of a prospectively collected multicenter database.

    Objectives

    To evaluate the evolution of surgical treatment strategies, complications, and patient-reported outcomes for adult spinal deformity (ASD) patients.

    Summary of background data

    ASD surgery is associated with high complication rates. Evolving treatment strategies may reduce these risks.

    Methods

    Adult patients undergoing ASD surgery from 2009 to 2016 were analyzed (n = 905). Preoperative and surgical parameters were compared across years. Subgroup analysis of 436 patients with minimum two-year follow-up was also performed.

    Results

    From 2009 to 2016, there was a significant increase in the mean preoperative age (52 to 63.1, p < .001), body mass index (26.3 to 32.2, p = .003), Charlson Comorbidity index (1.4 to 2.2, p < .001), rate of previous spine surgery (39.8% to 53.1%, p = .01), and baseline disability (visual analog scale [VAS] back and leg pain) scores (p < .01), Oswestry Disability Index, and 22-item Scoliosis Research Society Questionnaire scores (p < .001). Preoperative Schwab sagittal alignment modifiers and overall surgical invasiveness index were similar across time. Three-column osteotomy utilization decreased from 36% in 2011 to 16.7% in 2016. Lateral lumbar interbody fusion increased from 6.4% to 24.1% (p = .004), anterior lumbar interbody fusion decreased from 22.9% to 16.7% (p = .043), and transforaminal lumbar interbody fusion/posterior lumbar interbody fusion utilization remained similar (p = .448). Use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in 2012 was 84.6%, declined to 58% in 2013, and rebounded to 76.3% in 2016 (p = .006). Tranexamic acid use increased rapidly from 2009 to 2016 (13.3% to 48.6%, p < .001). Two-year follow-up sagittal vertical axis, pelvic tilt, pelvic incidence-lumbar lordosis, and maximum Cobb angles were similar across years. Intraoperative complications decreased from 33% in 2010 to 9.3% in 2016 (p < .001). Perioperative (<30 days, <90 days) complications peaked in 2010 (42.7%, 46%) and decreased by 2016 (24.1%, p < .001; 29.6%, p = .007). The overall complication rate decreased from 73.2% in 2008-2014 patients to 62.6% in 2015-2016 patients (p = .03). Two-year health-related quality of life outcomes did not significantly differ across the years (p > .05).

    Conclusions

    From 2009 to 2016, despite an increasingly elderly, medically compromised, and obese patient population, complication rates decreased. Evolving strategies may result in improved treatment of ASD patients.

    Level of evidence

    Level IV.
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    ItemOpen Access
    Impact of cost valuation on cost-effectiveness in adult spine deformity surgery.
    (The spine journal : official journal of the North American Spine Society, 2017-01) Gum, Jeffrey L; Hostin, Richard; Robinson, Chessie; Kelly, Michael P; Carreon, Leah Yacat; Polly, David W; Bess, R Shay; Burton, Douglas C; Shaffrey, Christopher I; Smith, Justin S; LaFage, Virginie; Schwab, Frank J; Ames, Christopher P; Glassman, Steven D; International Spine Study Group

    Background context

    Over the past decade, the number of adult spinal deformity (ASD) surgeries has more than doubled in the United States. The complex surgeries needed to manage ASD are associated with significant resource utilization and high cost, making them a primary target for increased scrutiny. Accordingly, it is important to not only demonstrate value in ASD surgery as clinical effectiveness but also to translate outcome assessment to cost-effectiveness.

    Purpose

    To compare the difference between Medicare allowable rates and the actual, direct hospital costs for ASD surgeries.

    Study design

    Longitudinal cohort.

    Patient sample

    Consecutive patients enrolled in an ASD database from a single institution.

    Outcome measures

    Short Form (SF)-6D.

    Methods

    Consecutive patients enrolled in an ASD database from a single institution from 2008 to 2013 were identified. Direct hospital costs were collected from hospital administrative records for the entire inpatient episode of surgical care. Medicare allowable rates were calculated for the same inpatient stays using the year-appropriate Center for Medicare-Medicaid Services Inpatient Pricer Payment System Tool. The SF-6D, a utility index derived from the SF-36v1, was used to determine quality-adjusted life years (QALY). Costs and QALYs were discounted at 3.5% annually.

    Results

    Of 580 surgical ASD patients eligible for 2-year follow up, 346 (60%) had complete baseline and 2-year data, and 60 were Medicare beneficiaries comprising the cohort for the present study. Mean SF-6D gained is 0.10 during year 1 after surgery and 0.02 at year 2, resulting in a cumulative SF-6D gain of 0.12 over 2 years. Mean Medicare allowable rate over the 2 years is $82,050 (range $42,383 to $220,749) and mean direct cost is $99,114 (range $28,447 to $217,717). Mean cost per QALY over 2 years is $683,750 using Medicare allowable rates and $825,950 using direct costs. This difference of $17,181 between the 2 cost calculation represents a 17% difference, which was statistically significant (p<.001).

    Conclusions

    There is a significant difference in direct hospital costs versus Medicare allowable rates in ASD surgery and in turn, there is a similar difference in the cost per QALY calculation. Utilizing Medicare allowable rates not only underestimates (17%) the cost of ASD surgery, but it also creates inaccurate and unrealistic expectations for researchers and policymakers.
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    Predictive model for distal junctional kyphosis after cervical deformity surgery.
    (The spine journal : official journal of the North American Spine Society, 2018-12) Passias, Peter G; Vasquez-Montes, Dennis; Poorman, Gregory W; Protopsaltis, Themistocles; Horn, Samantha R; Bortz, Cole A; Segreto, Frank; Diebo, Bassel; Ames, Chris; Smith, Justin; LaFage, Virginie; LaFage, Renaud; Klineberg, Eric; Shaffrey, Chris; Bess, Shay; Schwab, Frank; ISSG

    Background context

    Distal junctional kyphosis (DJK) is a primary concern of surgeons correcting cervical deformity. Identifying patients and procedures at higher risk of developing this condition is paramount in improving patient selection and care.

    Purpose

    The present study aimed to develop a risk index for DJK development in the first year after surgery.

    Study design/setting

    This is a retrospective review of a prospective multicenter cervical deformity database.

    Patient sample

    Patients over the age of 18 meeting one of the following deformities were included in the study: cervical kyphosis (C2-7 Cobb angle>10°), cervical scoliosis (coronal Cobb angle>10°), positive cervical sagittal imbalance (C2-C7 sagittal vertical axis (SVA)>4 cm or T1-C6>10°), or horizontal gaze impairment (chin-brow vertical angle>25°).

    Outcome measures

    Development of DJK at any time before 1 year.

    Methods

    Distal junctional kyphosis was defined by both clinical diagnosis (by enrolling surgeon) and post hoc identification of development of an angle<-10° from the end of fusion construct to the second distal vertebra, as well as a change in this angle by <-10° from baseline. Conditional Inference Decision Trees were used to identify factors predictive of DJK incidence and the cut-off points at which they have an effect. A conditional Variable-Importance table was constructed based on a non-replacement sampling set of 2,000 Conditional Inference Trees. Twelve influencing factors were found; binary logistic regression for each variable at significant cutoffs indicated their effect size.

    Results

    Statistical analysis included 101 surgical patients (average age: 60.1 years, 58.3% female, body mass index: 30.2) undergoing long cervical deformity correction (mean levels fused: 7.1, osteotomy used: 49.5%, approach: 46.5% posterior, 17.8% anterior, 35.7% combined). In 2 years after surgery, 6% of patients were diagnosed with clinical DJK; however, 23.8% of patients met radiographic definition for DJK. Patients with neurologic symptoms were at risk of DJK (odds ratio [OR]: 3.71, confidence interval [CI]: 0.11-0.63). However, no significant relationship was found between osteoporosis, age, and ambulatory status with DJK incidence. Baseline radiographic malalignments were the most numerous and strong predictors for DJK: (1) C2-T1 tilt>5.33 (OR: 6.94, CI: 2.99-16.14); (2) kyphosis<-50.6° (OR: 5.89, CI: 0.07-0.43); (3) C2-C7 lordosis<-12° (OR: 5.7, CI: 0.08-0.41); (4) T1 slope minus cervical lordosis>36.4 (OR: 5.6, CI: 2.28-13.57); (5) C2-C7 SVA>56.3° (OR: 5.4, CI: 2.20-13.23); and (6) C4_Tilt>56.7 (OR: 5.0, CI: 1.90-13.1). Clinically, combined approaches (OR: 2.67, CI: 1.21-5.89) and usage of Smith-Petersen osteotomy (OR: 2.55, CI: 1.02-6.34) were the most important predictors of DJK.

    Conclusions

    In a surgical cohort of patients with cervical deformity, we found a 23.8% incidence of DJK. Different procedures and patient malalignment predicted incidence of DJK up to 1 year. Preoperative T1 slope-cervical lordosis, cervical kyphosis, SVA, and cervical lordosis all strongly predicted DJK at specific cut-off points. Knowledge of these factors will potentially help direct future study and strategy aimed at minimizing this potentially dramatic occurrence.
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    Rod Fracture After Apparently Solid Radiographic Fusion in Adult Spinal Deformity Patients.
    (World neurosurgery, 2018-09) Daniels, Alan H; DePasse, J Mason; Durand, Wesley; Hamilton, D Kojo; Passias, Peter; Kim, Han Jo; Protopsaltis, Themistocles; Reid, Daniel BC; 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 Group
    Rod fracture occurs with delayed fusion or pseudarthrosis after adult spinal deformity (ASD) surgery. Rod fracture after apparent radiographic fusion has not been previously investigated.Patients with ASD in a multicenter database were assessed for radiographic fusion by a committee of 3 spinal deformity surgeons. Fusions were rated as bilaterally fused (A), unilaterally fused (B), partially fused (C), or not fused (D). Patients with grade A or B fusion and 2-year follow-up were included. Patients with radiographic fusion were evaluated for subsequent rod fracture. Adjusted analyses were conducted with multiple logistic regression, using backwards-variable selection to a threshold of P < 0.2, to assess for associated factors.Of 402 patients with radiographically apparent solid fusion, 9.5% (38) subsequently suffered a broken rod. On multivariate analysis, greater rates of rod fracture were seen among patients of age group 60-69 years (vs. 18-49), body mass index 30-34 and 35+ (vs. <25), stainless-steel rods (vs. titanium), patients with rods ≤5.5 mm (vs. 6.35 mm), and patients with Charlson score 0 (vs. 3+). Of the 38 patients with rod fractures, 18 (47.4%) presented with worsened pain, and 8 (21.1%) required revision at minimum 2-year follow-up.Rod fracture occurred in 9.5% of patients with apparently solid radiographic fusion after ASD surgery. Advanced age, obesity, small diameter rods (5.5 mm), osteotomy, and lower comorbidity burden were significantly associated with rod fracture. Nearly one-half of these patients noted worsening pain, and 21.1% required revision surgery. Instrumentation failure may occur and may be symptomatic even in the setting of apparent fusion on plain radiographs.
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    Sexual Dysfunction Secondary to Lumbar Stiffness in Adult Spinal Deformity Patients before and after Long-Segment Spinal Fusion.
    (World neurosurgery, 2020-04-17) Daniels, Alan H; Reid, Daniel; Durand, Wesley; Disilvestro, Kevin; 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 Group
    OBJECT:Sexual function is an important factor which contributes to quality of life. ASD patients may have sexual limitations due to lumbar spinal stiffness which may be affected by long-segment fusion. METHODS:This study utilized a multi-center, prospectively defined, consecutive cohort of ASD patients. The primary outcome in this study was the LSDI question 10: "Choose the statement that best describes the effect of low back stiffness on your ability to engage in sexual intercourse". RESULTS:In total, 368 patients were included in this study, including 76 males and 292 females of which 80.7% (n=293) underwent 9 or more level fusion and 74.4% (n=270) had pelvic fixation. Baseline LSDI sexual function scores averaged 1.7 (SD 1.3), which improved to 1.3 (SD 1.2) at 2-year follow-up (p = 0.0008). After adjusting for confounding factors, worse LSDI sexual function score was strongly associated with worse ODI, SRS total, and SF-36 PCS and MCS scores at both baseline and 2-year follow-up (p<0.05 for all comparisons). Predictors of poorer baseline sexual function included older age, increased SVA, and increased back pain (p<0.05 for all comparisons). Predictors of improvement in sexual function at 2-year follow-up included SVA improvement (p=0.0032) and decreased postoperative back pain (p<0.0001). CONCLUSIONS:This study found that sexual dysfunction scores due to lumbar stiffness significantly improved following surgery for ASD. Additionally, lumbar stiffness related sexual dysfunction is strongly related to overall outcome measured by ODI and SRS total score, highlighting the importance of sexual health on overall outcome in ASD patients.
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    The effect of posterior polyester tethers on the biomechanics of proximal junctional kyphosis: a finite element analysis.
    (Journal of neurosurgery. Spine, 2017-01) Bess, Shay; Harris, Jeffrey E; Turner, Alexander WL; LaFage, Virginie; Smith, Justin S; Shaffrey, Christopher I; Schwab, Frank J; Haid, Regis W
    OBJECTIVE Proximal junctional kyphosis (PJK) remains problematic following multilevel instrumented spine surgery. Previous biomechanical studies indicate that providing less rigid fixation at the cranial aspect of a long posterior instrumented construct, via transition rods or hooks at the upper instrumented vertebra (UIV), may provide a gradual transition to normal motion and prevent PJK. The purpose of this study was to evaluate the ability of posterior anchored polyethylene tethers to distribute proximal motion segment stiffness in long instrumented spine constructs. METHODS A finite element model of a T7-L5 spine segment was created to evaluate range of motion (ROM), intradiscal pressure, pedicle screw loads, and forces in the posterior ligament complex within and adjacent to the proximal terminus of an instrumented spine construct. Six models were tested: 1) intact spine; 2) bilateral, segmental pedicle screws (PS) at all levels from T-11 through L-5; 3) bilateral pedicle screws from T-12 to L-5 and transverse process hooks (TPH) at T-11 (the UIV); 4) pedicle screws from T-11 to L5 and 1-level tethers from T-10 to T-11 (TE-UIV+1); 5) pedicle screws from T-11 to L-5 and 2-level tethers from T-9 to T-11 (TE-UIV+2); and 6) pedicle screws and 3-level tethers from T-8 to T-11 (TE-UIV+3). RESULTS Proximal-segment range of motion (ROM) for the PS construct increased from 16% at UIV-1 to 91% at UIV. Proximal-segment ROM for the TPH construct increased from 27% at UIV-1 to 92% at UIV. Posterior tether constructs distributed ROM at the UIV and cranial adjacent segments most effectively; ROM for TE-UIV+1 was 14% of the intact model at UIV-1, 76% at UIV, and 98% at UIV+1. ROM for TE-UIV+2 was 10% at UIV-1, 51% at UIV, 69% at UIV+1, and 97% at UIV+2. ROM for TE-UIV+3 was 7% at UIV-1, 33% at UIV, 45% at UIV+1, and 64% at UIV+2. Proximal segment intradiscal pressures, pedicle screw loads, and ligament forces in the posterior ligament complex were progressively reduced with increasing number of posterior tethers used. CONCLUSIONS Finite element analysis of long instrumented spine constructs demonstrated that posterior tethers created a more gradual transition in ROM and adjacent-segment stress from the instrumented to the noninstrumented spine compared with all PS and TPH constructs. Posterior tethers may limit the biomechanical risk factor for PJK; however, further clinical research is needed to evaluate clinical efficacy.
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    The Importance of C2 Slope, a Singular Marker of Cervical Deformity, Correlates With Patient-reported Outcomes.
    (Spine, 2020-02) Protopsaltis, Themistocles S; Ramchandran, Subaraman; Tishelman, Jared C; Smith, Justin S; Neuman, Brian J; Jr, Gregory M Mundis; Lafage, Renaud; Klineberg, Eric O; Hamilton, D Kojo; LaFage, Virginie; Gupta, Munish C; Hart, Robert A; Schwab, Frank J; Burton, Douglas C; Bess, Shay; Shaffrey, Christopher I; Ames, Christopher P; International Spine Study Group

    Study design

    Retrospective review of a prospectively collected database.

    Objective

    To define a simplified singular measure of cervical deformity (CD), C2 slope (C2S), which correlates with postoperative outcomes.

    Summary of background data

    Sagittal malalignment of the cervical spine, defined by the cervical sagittal vertical axis (cSVA) has been associated with poor outcomes following surgical correction of the deformity. There has been a proliferation of parameters to describe CD. This added complexity can lead to confusion in classifying, treating, and assessing outcomes of CD surgery.

    Methods

    A prospective database of CD patients was analyzed. Inclusion criteria were cervical kyphosis>10°, cervical scoliosis>10°, cSVA>4 cm, or chin-brow vertical angle >25°. Patients were categorized into two groups and compared based on whether the apex of the deformity was in the cervical (C) or the cervicothoracic (CT) region. Radiographic parameters were correlated to C2S, T1 slope (T1S) and 1-year health-related quality-of-life outcomes as measured by the EuroQol 5 Dimension questionnaire (EQ5D), modified Japanese Orthopedic Association Scale, numeric rating scale for neck pain, and the Neck Disability Index (NDI).

    Results

    One hundred four CD patients (C = 74, CT = 30; mean age 61 yr, 56% women, 42% revisions) were included. CT patients had higher baseline cSVA and T1S (P < 0.05). C2S correlated with T1 slope minus cervical lordosis (TS-CL) (r = 0.98, P < 0.001) and C0-C2 angle, cSVA, CL, T1S (r = 0.37-0.65, P < 0.001). Correlation of cSVA with C0-C2 was weaker (r = 0.48, P < 0.001). At 1-year postoperatively, higher C2S correlated with worse EQ-5D (r = 0.28, P = 0.02); in CT patients, higher C2S correlated with worse NDI, modified Japanese Orthopedic Association Scale, numeric rating scale for neck pain, and EQ5D (all r > 0.5, P≤0.05). Using linear regression, moderate disability by EQ5D corresponded to C2S of 20°(r = 0.08). For CT patients, C2S = 17° corresponded to moderate disability by NDI (r = 0.4), and C2S = 20° by EQ5D (r = 0.25).

    Conclusion

    C2S correlated with upper-cervical and subaxial alignment. C2S correlated strongly with TS-CL (R = 0.98, P < 0.001) because C2S is a mathematical approximation of TS-CL. C2S is a useful marker of CD, linking the occipitocervical and cervico-thoracic spine. C2S defines the presence of a mismatch between cervical lordosis and thoracolumbar alignment. Worse 1-year postoperative C2 slope correlated with worse health outcomes.

    Level of evidence

    3.
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    The spino-pelvic ratio: a novel global sagittal parameter associated with clinical outcomes in adult spinal deformity patients.
    (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, 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; Kelly, Michael P; Klineberg, Eric; Schwab, Frank; Burton, Doug; Bess, Shay; Ames, Christopher; Hart, Robert; International Spine Study Group (ISSG)

    Purpose

    Analysis of interactions of spinal alignment metrics may uncover novel alignment parameters, similar to PI-LL. This study utilized a data-driven approach to hypothesis generation by testing all possible division interactions between spinal alignment parameters.

    Methods

    This study was a retrospective cohort analysis. In total, 1439 patients with baseline ODI were included for hypothesis generation. In total, 666 patients had 2-year postoperative follow-up and were included for validation. All possible combinations of division interactions between baseline metrics were assessed with linear regression against baseline ODI.

    Results

    From 247 raw alignment metrics, 32,398 division interactions were considered in hypothesis generation. Conceptually, the TPA divided by PI is a measure of the relative alignment of the line connecting T1 to the femoral head and the line perpendicular to the sacral endplate. The mean TPA/PI was 0.41 at baseline and 0.30 at 2 years postoperatively. Higher TPA/PI was associated with worse baseline ODI (p < 0.0001). The change in ODI at 2 years was linearly associated with the change in TPA/PI (p = 0.0172). The optimal statistical grouping of TPA/PI was low/normal (≤ 0.2), medium (0.2-0.4), and high (> 0.4). The R-squared for ODI against categorical TPA/PI alone (0.154) was directionally higher than that for each of the individual Schwab modifiers (SVA: 0.138, PI-LL 0.111, PT 0.057).

    Conclusion

    This study utilized a data-driven approach for hypothesis generation and identified the spino-pelvic ratio (TPA divided by PI) as a promising measure of sagittal spinal alignment among ASD patients. Patients with SPR > 0.2 exhibited inferior ODI scores.

    Level of evidence

    III.