Proximal Junctional Kyphosis in Adult Spinal Deformity After Segmental Posterior Spinal Instrumentation and Fusion
Bibliographic record
Abstract
In Brief Study Design. A retrospective study. Objective. To analyze time-dependent change of, prevalence of, and risk factors for proximal junctional kyphosis (PJK) in adult spinal deformity after long (≥5 vertebrae) segmental posterior spinal instrumented fusion with a minimum 5-year postoperative follow-up. Summary of Background Data. No study has focused on time-dependent long-term proximal junctional change in adult spinal deformity after segmental posterior spinal instrumented fusion with minimum 5-year follow-up. Methods. Clinical and radiographic data of 161 (140 women/21 men) adult spinal deformity patients with minimum 5-year follow-up (average 7.8 years, range 5–19.8 years) treated with long posterior spinal instrumentation and fusion were analyzed. Radiographic measurements included sagittal Cobb angle at the proximal junction on preoperative, 8-weeks postoperation, 2-year postoperation, and ultimate follow-up (≥5 years). Postoperative SRS outcome scores were also evaluated. Results. The prevalence of PJK at 7.8 years postoperation was 39% (62/161 patients). The PJK group (n = 62) demonstrated a significant increase in proximal junctional angle at 8 weeks (59%), between 2 years postoperation and ultimate postoperation (35%), and in thoracic kyphosis (T5–T12) at ultimate follow-up (P = 0.001). However, the sagittal vertical axis change at ultimate follow-up did not correlate with PJK (P = 0.53). Older age at surgery >55 years (vs. ≤55 years) and combined anterior and posterior spinal fusion (vs. posterior only) demonstrated significantly higher PJK prevalence (P = 0.001, 0.041, respectively). The SRS outcome scores did not demonstrate significant differences with the exception of the self-image domain when PJK exceeded 20°. Conclusion. The prevalence of PJK at 7.8 years postoperation was 39%. PJK progressed significantly within 8 weeks postoperation (59%) and between 2 years postoperation and ultimate follow-up (35%). Older age at surgery (>55 years) and combined anterior and posterior spinal fusion were identified as risk factors for developing PJK. The SRS outcome instrument was not adversely affected by PJK, except when PJK exceeded 20°. Proximal junctional kyphosis at 7.8 years postoperation in adult spinal deformity after long (≥5 vertebrae) segmental posterior spinal instrumented fusion demonstrated a prevalence of 39% significant progression at 8-weeks postoperation with minimal effect on Scoliosis Research Society outcome instruments at ultimate follow-up. Older age at surgery (>55 years) and combined anterior/posterior spinal fusion were identified as risk factors for developing proximal junctional kyphosis.
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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 | 0.001 |
| 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) | 0.001 | 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".