Listhesis and Spinopelvic Inclination of Upper Instrumented Vertebra Region and the Implications on Proximal Junctional Kyphosis
Bibliographic record
Abstract
STUDY DESIGN: Retrospective analysis of prospective data. OBJECTIVE: Evaluate the impact of radiographic and morphologic configuration of the uppermost instrumented vertebrae (UIV) region on proximal junctional kyphosis (PJK) rates. BACKGROUND: Literature is limited on evaluation of the preoperative landing zone (UIV-1 to UIV +2 levels) and its impact on development of PJK. MATERIALS AND METHODS: Adult ASD patients with native baseline thoracolumbar junction, postoperative UIV between T9 and T12 and LIV extending to pelvis, and two-year follow-up available were included. Landing zone was assessed on radiographs for Meyerding grade listhesis and posterior translation angle by 2 spine surgeons. Comparative analyses were performed on demographics, radiographic parameters, and PJK rates across patients with/without landing zone listhesis and above/below 15° UIV spinopelvic inclination (UIV SPi). Multivariable regression, accounting for listhesis, UIV SPi, PJK prophylaxis, age, osteoporosis, radiographic UIV quality (bridging osteophytes/degenerative disc disease), and change in PI-LL and SVA, was used to identify independent predictors of PJK. RESULTS: Among 244 patients, mean age was 64.41 years, 73.0% were females, mean CCI was 1.97. In total, 30% had preoperative landing zone listhesis and 42% had posterior translation (41% with baseline posterior translation and 59% with iatrogenic translation). Listhesis patients had similar baseline and two-year radiographic alignment but higher two-year PJK rates (32.9% vs . 20.5%, P = 0.04). UIV SPi >15° patients also had higher PJK (37.5% vs . 14.2%, P < 0.01) and PJK reoperation (16.3% vs . 5.8%, P = 0.01) rates. Patients with both listhesis and UIV SPi >15° had the highest PJK (45.5%, P = 0.03) and PJK reoperation (21.1%, P = 0.18) rates. Multivariable regression (R 2 = 0.33) identified landing zone listhesis (coeff = 1.0, P = 0.01) and UIV SPi (coeff = -0.22, P < 0.001) to be predictive of PJK. CONCLUSIONS: Preoperative listhesis and postoperative posterior translation are independent predictors of two-year PJK. These findings highlight the importance of meticulous selection of the UIV landing zone, with particular emphasis on preoperative listhesis and spinopelvic inclination. LEVEL OF EVIDENCE: Level IV.
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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 | 0.000 | 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".