Upper Instrumented Vertebral Fractures in Long Lumbar Fusions
Bibliographic record
Abstract
STUDY DESIGN: A retrospective comparative study. OBJECTIVE: To investigate the risk factors associated with upper instrumented vertebral (UIV) fractures in adult lumbar deformity. SUMMARY OF BACKGROUND DATA: Long segment lumbar fusions may lead to junctional failures. The purpose of this study was to determine factors associated with junctional failures. METHODS: Twenty-seven consecutive patients from 2001 to 2008 with minimum 4 levels fused, lower instrumented vertebra (LIV) of L5 or S1, upper instrumented vertebra of T10 or distal, and no previous surgery proximal to the instrumentation were retrospectively reviewed. We describe the UIV angle, the sagittal angle of the upper instrumented vertebra with the horizontal. Patients were divided into 3 groups: group 1, 7 patients with UIV fractures; group 2, 6 patients with other proximal failures; and group 3, 14 patients with no proximal complications. RESULTS: The mean number of levels fused was 5.7 (4-7), 5.2 (4-8), and 6.2 (4-8); mean age was 64.1, 61.8, and 64.1, and mean body mass index was 33.5, 30.0, and 31.6 for groups 1, 2, and 3, respectively (P > 0.05). Osteotomies were performed in 5 of 7 in group 1, 1 of 6 in group 2, and 5 of 14 in group 3. Mean follow-up was 26.3 months. The average intraoperative UIV angle (UIV0) and immediate postoperative UIV angle (UIV1) were 18.6°/15.4° for group 1, 5.7°/5.3° for group 2, and 10.3°/7.1° for group 3 (P < 0.05). Surgical revision rates were higher in group 1 (71%) compared with groups 2 (50%) and 3 (43%). Eight of 11 (73%) patients with upper instrumented vertebra of L1 or L2 had either UIV fracture or other proximal failure compared with 5 of 16 (31%) in patients with upper instrumented vertebra of T10, T11, or T12. CONCLUSION: Our series of long lumbar fusions had a high long-term complication and revision rate. A high UIV angle on intraoperative lateral radiograph was strongly associated with UIV fractures. UIVs of L1 or L2 had a higher rate of adjacent segment or UIV failure.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| 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".