Factors Associated With the Development of and Revision for Proximal Junctional Kyphosis in 440 Consecutive Adult Spinal Deformity Patients
Bibliographic record
Abstract
MINI: Proximal junctional kyphosis (PJK) is a common, yet incompletely understood, complication of surgery for adult spinal deformity. We analyzed 440 consecutive adult spinal deformity patients for trends in development of PJK and need for revision surgery. pelvic tilt and thoracic kyphosis were predictive for developing PJK, while radiographic evidence of proximal junctional failure was predictive for proceeding to revision. STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: The aim of this study was to examine which radiographic parameters and surgical strategies are most closely associated with proximal junctional kyphosis (PJK) after adult spinal deformity (ASD) surgery, the need for revision surgery for PJK, and whether these differ based on the upper instrumented vertebra (UIV). SUMMARY OF BACKGROUND DATA: Multiple parameters are considered when planning correction of ASD. Determining which of these factors contribute to the development of and need for revision surgery for PJK presents a challenging problem. METHODS: Consecutive patients undergoing long fusion to the pelvis with age >18 years, minimum 6-month follow-up, and adequate radiographs for analysis in a single institution between 2003 and 2011 were included. Along with chart review, measurement of proximal junctional angle (PJA), sagittal balance, and pelvic parameters was performed on preoperative, postoperative, and latest follow-up radiographs. Postoperative radiographs were also examined for signs of PJF. RESULTS: A total of 440 patients with a mean follow-up of 34 months met inclusion criteria, 159 of whom developed PJK (36%), with 65 requiring revision surgery (41%). Higher preoperative pelvic tilt (PT) (P = 0.018) and postoperative thoracic kyphosis (TK) (P ≤ 0.001) were predictive for development of PJK, whereas hooks at UIV were protective (odds ratio [OR] 0.049). In patients who developed PJK, revision was more frequent in younger patients (P = 0.005) with greater postoperative sagittal vertical axis and PJA (P = 0.029, P = 0.018). PJF with spondylolisthesis, fracture, or instrumentation failure at the UIV had the highest ORs for proceeding to a revision (5.1, 1.6, and 2.2, respectively). CONCLUSION: TK and PT are important indicators of overall rigidity and reference the ability of the spine to compensate for sagittal plane deformity. Special attention should be paid to these characteristics and to the choice of proximal instrumentation when attempting to prevent PJK. Prevention of radiographically evident PJF may hold the key to reducing the need for revision surgery. LEVEL OF EVIDENCE: 3.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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) | 0.000 | 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 teacher head, 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".