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- Hellum, C., et al.
(author)
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Surgery in degenerative spondylolisthesis: does fusion improve outcome in subgroups? A secondary analysis from a randomized trial (NORDSTEN trial)
- 2023
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In: Spine Journal. - 1529-9430. ; 23:11, s. 1613-1622
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Journal article (peer-reviewed)abstract
- BACKGROUND CONTEXT: Patients with spinal stenosis and degenerative spondylolisthesis are treated surgically with decompression alone or decompression with fusion. However, there is debate regarding which subgroups of patients may benefit from additional fusion. PURPOSE: To investigate possible treatment effect modifiers and prognostic variables among patients operated for spinal stenosis and degenerative spondylolisthesis. DESIGN: A secondary exploratory study using data from the Norwegian Degenerative Spondylo-listhesis and Spinal Stenosis (NORDSTEN-DS) trial. Patients were randomized to decompression alone or decompression with instrumented fusion. PATIENT SAMPLE: The sample in this study consists of 267 patients from a randomized multi-center trial involving 16 hospitals in Norway. Patients were enrolled from February 12, 2014, to December 18, 2017. The study did not include patients with degenerative scoliosis, severe forami-nal stenosis, multilevel spondylolisthesis, or previous surgery. OUTCOME MEASURES: The primary outcome was an improvement of >= 30% on the Oswestry Disability Index score (ODI) from baseline to 2-year follow-up. METHODS: When investigating possible variables that could modify the treatment effect, we ana-lyzed the treatment arms separately. When testing for prognostic factors we analyzed the whole cohort (both treatment groups). We used univariate and multiple regression analyses. The selection of variables was done a priori, according to the published trial protocol. RESULTS: Of the 267 patients included in the trial (183 female [67%]; mean [SD] age, 66 [7.6] years), complete baseline data for the variables required for the present analysis were available for 205 of the 267 individuals. We did not find any clinical or radiological variables at baseline that modified the treatment effect. Thus, none of the commonly used criteria for selecting patients for fusion surgery influenced the chosen primary outcome in the two treatment arms. For the whole cohort, less comorbidity (American Society of Anesthesiologists Classification [ASA], OR = 4.35; 95% confidence interval (CI [1.16-16.67]) and more preoperative leg pain (OR = 1.23; CI [1.02 -1.50]) were significantly associated with an improved primary outcome. CONCLUSIONS: In this study on patients with degenerative spondylolisthesis, neither previously defined instability criteria nor other pre-specified baseline variables were associated with better clinical outcome if fusion surgery was performed. None of the analyzed variables can be applied to guide the decision for fusion surgery in patients with degenerative spondylolisthesis. For both treat-ment groups, less comorbidity and more leg pain were associated with improved outcome 2 years after surgery. TRIAL REGISTRATION: NORDSTEN-DS ClinicalTrials.gov, NCT02051374. (c) 2023 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
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| 2. |
- Alfaro-Cuello, M., et al.
(author)
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A Deep View into the Nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. II. Kinematic Characterization of the Stellar Populations
- 2020
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 892:1
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Journal article (peer-reviewed)abstract
- The Sagittarius dwarf spheroidal galaxy is in an advanced stage of disruption but still hosts its nuclear star cluster (NSC), M54, at its center. In this paper, we present a detailed kinematic characterization of the three stellar populations present in M54: Young metal-rich (YMR); intermediate-age metal-rich (IMR); and old metal-poor (OMP), based on the spectra of 6500 individual M54 member stars extracted from a large Multi-Unit Spectroscopic Explorer (MUSE)/Very Large Telescope data set. We find that the OMP population is slightly flattened with a low amount of rotation (0.8 km s-1) and with a velocity dispersion that follows a Plummer profile. The YMR population displays a high amount of rotation (5 km s-1) and a high degree of flattening, with a lower and flat velocity dispersion profile. The IMR population shows a high but flat velocity dispersion profile, with some degree of rotation (2 km s-1). We complement our MUSE data with information from Gaia DR2 and confirm that the stars from the OMP and YMR populations are comoving in 3D space, suggesting that they are dynamically bound. While dynamical evolutionary effects (e.g., energy equipartition) are able to explain the differences in velocity dispersion between the stellar populations, the strong differences in rotation indicate different formation paths for the populations, as supported by an N-body simulation tailored to emulate the YMR-OMP system. This study provides additional evidence for the M54 formation scenario proposed in our previous work, where this NSC formed via GC accretion (OMP) and in situ formation from gas accretion in a rotationally supported disk (YMR).
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