Radiological Evidence of Spontaneous Spinal Arthrodesis in Patients With Lower Lumbar Spondylolisthesis
Bibliographic record
Abstract
STUDY DESIGN: Retrospective review of a consecutive series of patients with radiological evidence of spondylolisthesis. OBJECTIVE: To establish the incidence and characteristics of spontaneous spinal arthrodesis in the setting of lower lumbar spondylolisthesis. SUMMARY OF BACKGROUND DATA: Spontaneous spinal arthrodesis of lumbar spondylolisthesis is a finding that is not discussed in the literature outside of isolated case reports. Identifying spontaneous spinal arthrodesis may impact the surgical plan, as patients with existing fusion may not require instrumentation and might require more work to reduce their spondylolisthesis. METHODS: We reviewed a consecutive series of 1490 lumbar spine computed tomography scans from the year 2010 for radiological evidence of spondylolisthesis at either L4-L5 or L5-S1. Patients were excluded if they had undergone previous lumbar surgery. Scans were assessed for the presence of spontaneous fusion based on the following criteria: (1) a solid bridging anterior or posterior vertebral body osteophyte, (2) contiguous bone formation from one vertebral body to another, or (3) contiguous bone across the facet joints bilaterally. Patients were characterized by demographic variables, radiological characteristics including type of spondylolisthesis, and presenting symptomology. Differences between patients in the fused and nonfused cohorts were compared with univariate analysis. RESULTS: A total of 86 separate instances of spondylolisthesis were identified, of which 18 (20.9%) had radiological evidence of spontaneous fusion. The most common site of fusion was in the bilateral facets, followed by directly in the intervertebral disc space, and bridging osteophytes adjoining the vertebral bodies. There were significant differences between patients in the fused and nonfused cohorts in terms of average age (fused: 74.3 ± 10.7 yr vs. nonfused: 63.3 ± 18.6 yr, P = 0.019), sex (fused: 88.9% female vs. nonfused: 57.4% female, P = 0.013), and rate of pars defects (fused: 11.1% vs. nonfused: 35.3%, P = 0.047). CONCLUSION: In this study, 20.9% of patients with lumbar spondylolisthesis have radiological signs of spontaneous fusion. Further work is needed to better characterize the natural history and clinical-radiological correlation of spontaneous fusion in spondylolisthesis. LEVEL OF EVIDENCE: 4.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.007 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".