Publications by authors named "Nicholas Kummer"

8 Publications

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Does Matching Roussouly Spinal Shape and Improvement in SRS-Schwab Modifier Contribute to Improved Patient-reported Outcomes?

Spine (Phila Pa 1976) 2021 Sep;46(18):1258-1263

Department of Orthopedics, Hospital for Special Surgery, New York, NY.

Study Design: Retrospective review.

Objective: The aim of this study was to evaluate outcomes of matching Roussouly and improving in Schwab modifier following adult spinal deformity (ASD) surgery.

Summary Of Background Data: The Roussouly Classification system of sagittal spinal shape and the SRS-Schwab classification system have become important indicators of spine deformity. No previous studies have examined the outcomes of matching both Roussouly type and improving in Schwab modifiers postoperatively.

Methods: Surgical ASD patients with available baseline (BL) and 1 year (1Y) radiographic data were isolated in the single-center spine database. Patients were classified by their "theoretical" and "current" Roussouly types as previously published. Patients were considered a "Match" if their theoretical and current Roussouly types were the same, or a "Mismatch" if the types differed. Patients were noted as improved if they were Roussouly "Mismatch" preoperatively, and "Match" at 1Y postop. Schwab modifiers at BL were categorized as follows: no deformity (0), moderate deformity (+), and severe deformity (++) for PT, SVA, and PI-LL. Improvement in SRS-Schwab was defined as a decrease in any modifier severity at 1Y.

Results: 103 operative ASD patients (61.8 years, 63.1% female, 30 kg/m2) were included. At baseline, breakdown of "current" Roussouly type was: 28% Type 1, 25.3% Type 2, 32.0% Type 3, 14.7% Type 4. 65.3% of patients were classified as Roussouly "Mismatch" at BL. Breakdown of BL Schwab modifier severity: PT (+: 41.7%, ++: 49.5%), SVA (+: 20.3%, ++: 50%), PI-LL (+: 25.2%, ++: 46.6%). At 1 year postop, 19.2% of patients had Roussouly "Match". Analysis of Schwab modifiers showed that 12.6% improved in SVA, 42.7% in PI-LL, and 45.6% in PT. Count of patients who both had a Roussouly type "Match" at 1Y and improved in Schwab modifier severity: nine PT (8.7%), eight PI-LL (7.8%), and two SVA (1.9%). There were two patients (1.9%) who met their Roussouly type and improved in all three Schwab. 1Y matched Roussouly patients improved more in health-related quality of life scores (minimal clinically important difference [MCID] for Oswestry Disability Index [ODI], EuroQol-5D-3L [EQ5D], Visual Analogue Score Leg/Back Pain), compared to mismatched, but was not significant (P > 0.05). Match Roussouly and improvement in PT Schwab met MCID for EQ5D more (P = 0.050). Matched Roussouly and improvement in SVA Schwab met MCID for ODI more (P = 0.024).

Conclusion: Patients who both matched Roussouly sagittal spinal type and improved in SRS-Schwab modifiers had superior patient-reported outcomes. Utilizing both classification systems in surgical decision-making can optimize postop outcomes.Level of Evidence: 3.
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September 2021

Same Day Surgical Intervention Dramatically Minimizes Complication Occurrence and Optimizes Perioperative Outcomes for Central Cord Syndrome.

Clin Spine Surg 2021 Jul 21. Epub 2021 Jul 21.

Department of Orthopaedics, NYU Langone Orthopedic Hospital, New York, NY Department of Pediatric Neurosurgery, UT Southwestern Medical Center, Dallas, TX Department of Neurologic Surgery, University of Michigan, Ann Arbor, MI Department of Orthopaedic Surgery, University of Calgary, Calgary, AB, Canada Department of Neurological Surgery Montefiore Medical Center/Albert Einstein College of Medicine Bronx, NY Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD Deparment of Orthopedic Surgery, SUNY Downstate, New York, NY.

Study Design: This was a retrospective cohort study.

Objective: The aim of this study was to investigate associations between time to surgical intervention and outcomes for central cord syndrome (CCS) patients.

Background: As surgery is increasingly recommended for patients with neurological deterioration CCS, it is important to investigate the relationship between time to surgery and outcomes.

Materials And Methods: CCS patients were isolated in Nationwide Inpatient Sample database 2005-2013. Patients were grouped by time to surgery: same-day, 1-day delay, 2, 3, 4-7, 8-14, and >14 days. Means comparison tests compared patient factors, perioperative complications, and charges across patient groups. Controlling for age, comorbidities, length of stay, and concurrent traumatic fractures, binary logistic regression assessed surgical timing associated with increased odds of perioperative complication, using same-day as reference group.

Results: Included: 6734 CSS patients (64% underwent surgery). The most common injury mechanisms were falls (30%) and pedestrian accidents (7%). Of patients that underwent surgery, 52% underwent fusion, 30% discectomy, and 14% other decompression of the spinal canal. Breakdown by time to procedure was: 39% same-day, 16% 1-day, 10% 2 days, 8% 3 days, 16% 4-7 days, 8% 8-14 days, and 3% >14 days. Timing groups did not differ in trauma status at admission, although age varied: [minimum: 1 d (58±15 y), maximum: >14 d (63±13 y)]. Relative to other groups, same-day patients had the lowest hospital charges, highest rates of home discharge, and second lowest postoperative length of stay behind 2-day delay patients. Patients delayed >14 days to surgery had increased odds of perioperative cardiac and infection complications. Timing groups beyond 3 days showed increased odds of VTE and nonhome discharge.

Conclusions: CCS patients undergoing surgery on the same day as admission had lower odds of complication, hospital charges, and higher rates of home discharge than patients that experienced a delay to operation. Patients delayed >14 days to surgery were associated with inferior outcomes, including increased odds of cardiac complication and infection.
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July 2021

Bariatric surgery diminishes spinal diagnoses in a morbidly obese population: A 2-year survivorship analysis of cervical and lumbar pathologies.

J Clin Neurosci 2021 Aug 8;90:135-139. Epub 2021 Jun 8.

Department of Orthopedic Surgery, Brigham and Women's Faulkner Hospital, Boston, MA, USA.

The effects of bariatric surgery on diminishing spinal diagnoses have yet to be elucidated in the literature. The purpose of this study was to assess the rate in which various spinal diagnoses diminish after bariatric surgery. This was a retrospective analysis of the NYSID years 2004-2013. Patient linkage codes allow identification of multiple and return inpatient stays within the time-frame analyzed (720 days). Time from bariatric surgery until the patient's respective spinal diagnosis was no longer present was considered a loss of previous spinal diagnosis (LOD). Included: 4,351 bariatric surgery pts with a pre-op spinal diagnosis. Cumulative LOD rates at 90-day, 180-day, 360-day, and 720-day f/u were as follows: lumbar stenosis (48%,67.6%,79%,91%), lumbar herniation (61%,77%,86%,93%), lumbar spondylosis (47%,65%,80%,93%), lumbar spondylolisthesis (37%,58%,70%,87%), lumbar degeneration (37%,56%,72%,86%). By cervical region: cervical stenosis (48%,70%,84%,94%), cervical herniation (39%,58%,74%,87%), cervical spondylosis (46%, 70%,83%, 94%), cervical degeneration (44%,64%,78%,89%). Lumbar herniation pts saw significantly higher 90d-LOD than cervical herniation pts (p < 0.001). Cervical vs lumbar degeneration LOD rates did not differ @90d (p = 0.058), but did @180d (p = 0.034). Cervical and lumbar stenosis LOD was similar @90d & 180d, but cervical showed greater LOD by 1Y (p = 0.036). In conclusion, over 50% of bariatric patients diagnosed with a cervical or lumbar pathology before weight-loss surgery no longer sought inpatient care for their respective spinal diagnosis by 180 days post-op. Lumbar herniation had significantly higher LOD than cervical herniation by 90d, whereas cervical degeneration and stenosis resolved at higher rates than corresponding lumbar pathologies by 180d and 1Y f/u, respectively.
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August 2021

Increased cautiousness in adolescent idiopathic scoliosis patients concordant with syringomyelia fails to improve overall patient outcomes.

J Craniovertebr Junction Spine 2021 Apr-Jun;12(2):197-201. Epub 2021 Jun 10.

Department of Orthopedics and Neurological Surgery, NYU Langone Orthopedic Hospital, New York, NY, USA.

Background: Adolescent idiopathic scoliosis (AIS) is a common cause of spinal deformity in adolescents. AIS can be associated with certain intraspinal anomalies such as syringomyelia (SM). This study assessed the rate o f SM in AIS patients and compared trends in surgical approach and postoperative outcomes in AIS patients with and without SM.

Methods: The database was queried using ICD-9 codes for AIS patients from 2003-2012 (737.1-3, 737.39, 737.8, 737.85, and 756.1) and SM (336.0). The patients were separated into two groups: AIS-SM and AIS-N. Groups were compared using -tests and Chi-squared tests for categorical and discrete variables, respectively.

Results: Totally 77,183 AIS patients were included in the study (15.2 years, 64% F): 821 (1.2%) - AIS-SM (13.7 years, 58% F) and 76,362 - AIS-N (15.2 years, 64% F). The incidence of SM increased from 2003-2012 (0.9 to 1.2%, = 0.036). AIS-SM had higher comorbidity rates (79 vs. 56%, < 0.001). Comorbidities were assessed between AIS-SM and AIS-N, demonstrating significantly more neurological and pulmonary in AIS-SM patients. 41.2% of the patients were operative, 48% of AIS-SM, compared to 41.6% AIS-N. AIS-SM had fewer surgeries with fusion (anterior or posterior) and interbody device placement. AIS-SM patients had lower invasiveness scores (2.72 vs. 3.02, = 0.049) and less LOS (5.0 vs. 6.1 days, = 0.001). AIS-SM patients underwent more routine discharges (92.7 vs. 90.9%). AIS-SM had more nervous system complications, including hemiplegia and paraplegia, brain compression, hydrocephalous and cerebrovascular complications, all < 0.001. After controlling for respiratory, renal, cardiovascular, and musculoskeletal comorbidities, invasiveness score remained lower for AIS-SM patients ( < 0.001).

Conclusions: These results indicate that patients concordant with AIS and SM may be treated more cautiously (lower invasiveness score and less fusions) than those without SM.
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June 2021

The Five-item Modified Frailty Index is Predictive of 30-day Postoperative Complications in Patients Undergoing Spine Surgery.

Spine (Phila Pa 1976) 2021 Jul;46(14):939-943

Departments of Orthopedic and Neurologic Surgery, NYU Langone Orthopedic Hospital; New York Spine Institute, New York, NY.

Study Design: Retrospective cohort study.

Objective: This study aimed to evaluate the utility of the modified frailty index (mFI-5) in a population of patients undergoing spine surgery.

Summary Of Background Data: The original modified frailty index (mFI-11) published as an American College of Surgeons National Surgical Quality Improvement Program 11-factor index was modified to mFI-5 after variables were removed from recent renditions.

Methods: Surgical spine patients were isolated using current procedural terminology codes. mFI-11 (11) and mFI-5 (5) were calculated from 2005 to 2012. mFI was determined by dividing the factors present by available factors. To assess correlation, Spearman rho was used. Predictive values of indices were generated by binary logistic regression. Patients were stratified into groups by mFI-5: not frail (NF, <0.3), mildly frail (MF, 0.3-0.5), severely frail (SF, >0.5). Means comparison tests analyzed frailty and clinical outcomes.

Results: After calculating the mFI-5 and the mFI-11, Spearman rho between the two indices was 0.926(P < 0.001). Each index established significant (all P < 0.001) predictive values for unplanned readmission (11 = odds ratio [OR]: 5.65 [2.92-10.94]; 5 = OR: 3.68 [1.85-2.32]), post-op complications (11 = OR: 8.56 [7.12-10.31]; 5 = OR: 13.32 [10.89-16.29]), and mortality (11 = OR: 41.29 [21.92-77.76]; 5 = OR: 114.82 [54.64-241.28]). Frailty categories by mFI-5 were: 83.2% NF, 15.2% MF, and 1.6% SF. From 2005 to 2016, rates of NF decreased (88.8% to 82.2%, P < 0.001), whereas MF increased (9.2% to 16.2%, P < 0.001), and SF remained constant (2% to 1.6%, P > 0.05). With increase in severity, postoperative rates of morbidities and complications increased.

Conclusion: The five-factor National Surgical Quality Improvement Program modified frailty index is an effective predictor of postoperative events following spine surgery. Severity of frailty score by the mFI-5 was associated with increased morbidity and mortality. The mFI-5 within a surgical spine population can reliably predict post-op complications. This tool is less cumbersome than mFI-11 and relies on readily accessible variables at the time of surgical decision-making.Level of Evidence: 3.
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July 2021

Not Frail and Elderly: How Invasive Can We Go In This Different Type of Adult Spinal Deformity Patient?

Spine (Phila Pa 1976) 2021 Jun 15. Epub 2021 Jun 15.

Division of Spinal Surgery/Departments of Orthopaedic and Neurosurgery, NYU Medical Center, NY Spine Institute, New York, NY, USA UT Southwestern Medical Center, Dallas, TX, USA Department of Orthopaedic Surgery, NYU Langone Orthopedic Hospital, New York, NY Department of Orthopaedics, Hospital for Special Surgery, New York, NY, USA Department of Orthopaedic Surgery, SUNY Downstate, New York, NY.

Study Design: Retrospective review of a single-center spine database.

Objective: Investigate the intersections of chronological age and physiological age via frailty to determine the influence of surgical invasiveness on patient outcomes.

Summary Of Background Data: Frailty is a well-established factor in preoperative risk stratification and prediction of postoperative outcomes. The surgical profile of operative adult spinal deformity (ASD) patients who present as elderly and not frail has yet to be investigated. Our aim was to examine the surgical profile and outcomes of ASD patients who were not frail and elderly.

Methods: Included: ASD patients≥18 years old, ≥4 levels fused, with baseline(BL) and follow up data. Patients were categorized by ASD frailty index: Not Frail[NF], Frail[F], Severely Frail [SF]. An elderly patient was defined as ≥70 years. Patients were grouped into NF/elderly and F/elderly. SRS-Schwab modifiers were assessed at baseline and 1-year(0, +, ++). Logistic regression analysis assessed the relationship between increasing invasiveness, no reoperations, or major complications, and improvement in SRS-Schwab modifiers[Good Outcome]. Decision tree analysis assessed thresholds for an invasiveness risk/benefit cutoff point.

Results: 598 ASD pts included(55.3yrs, 59.7%F, 28.3 kg/m2). 29.8% of patients were above age 70. At baseline, 51.3% of patients were NF, 37.5% F, and 11.2% SF. 66(11%) of patients were NF and elderly. 24.2% of NF-Elderly patients improved in SRS-Schwab by 1-year and had no reoperation or complication postoperatively. Binary regression analysis found a relationship between worsening SRS-Schwab, postop complication, and reoperation with invasiveness score(OR: 1.056[1.013-1.102], p = 0.011). Risk/benefit cut-off was 10(p = 0.004). Patients below this threshold were 7.9[2.2-28.4] times more likely to have a Good Outcome. 156 patients were elderly and F/SF with 16.7% having Good Outcome, with a risk/benefit cut-off point of <8 (4.4[2.2-9.0], p < 0.001).

Conclusions: Frailty status impacted the balance of surgical invasiveness relative to operative risk in an inverse manner, while the opposite was seen amongst elderly patients with a frailty status less than their chronologic age. Surgeons should perhaps consider incorporation of frailty status over age status when determining realignment plans in patients of advanced age.Level of Evidence: ???
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June 2021

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 (Phila Pa 1976) 2021 Mar 11. Epub 2021 Mar 11.

Department of Orthopedics, NYU Langone Orthopedic Hospital, New York, NY, USA Department of Orthopedics, Hospital for Special Surgery, New York, NY, USA Department of Orthopedic Surgery, SUNY Downstate Medical Center, Brooklyn, NY, USA Department of Orthopaedic Surgery, Rocky Mountain Scoliosis and Spine, Denver, CO Department of Orthopedic Surgery, University of Kansas Medical Center, Kansas City, KS, USA Department of Orthopedic Surgery, University of California, Davis, Davis, CA, USA Department of Orthopaedic Surgery, Warren Alpert School of Medicine, Brown University, Providence, RI, USA San Diego Center for Spinal Disorders, La Jolla, CA, USA Division of Orthopaedic Surgery, Scripps Clinic, La Jolla, CA, USA Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA Department of Neurosurgery, University of Virginia, Charlottesville, VA, USA Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, USA.

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 ± 10yrs, 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 non-severe (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.
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March 2021

A Risk-Benefit Analysis of Increasing Surgical Invasiveness Relative to Frailty Status in Adult Spinal Deformity Surgery.

Spine (Phila Pa 1976) 2021 Aug;46(16):1087-1096

Department of Spine Surgery, Denver International Spine Clinic, Presbyterian St. Luke's/Rocky Mountain Hospital for Children, Denver, CO.

Study 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.
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August 2021