Development of Postoperative Pain in Patients with End-Stage Knee Osteoarthritis Is Associated with Upregulation of Genes Related to Extracellular Matrix Degradation, Inflammation, and Apoptosis Measured in the Peripheral Blood before Knee Surgery
Bibliographic record
Abstract
Osteoarthritis (OA) pain implies an indication for joint replacement in patients with end-stage OA. However, chronic postoperative pain is observed in 10-40% of patients with OA. Here, we identified genes whose expression in the peripheral blood before surgery could denote the risk of postoperative pain development. We examined the peripheral blood of 26 healthy subjects and 50 patients with end-stage OA prior to joint replacement surgery. Pain was evaluated before surgery using the visual analog scale (VAS) index and neuropathic pain questionnaires, Douleur Neuropathique 4 Questions (DN4) and PainDETECT questionnaires. Functional activity was assessed using the Western Ontario and McMaster Universities osteoarthritis index (WOMAC). Three and six months after surgery, pain indices according to VAS of 30% and higher were considered. Metalloproteinase (MMP)-9 and tissue inhibitor of metalloproteinase (TIMP)1 protein levels were measured using ELISA in the peripheral blood mononuclear cells (PBMCs). Total RNA isolated from whole blood was analysed using quantitative real-time RT-PCR for caspase-3, MMP-9, TIMP1, cathepsins K and S, tumour necrosis factor (TNF)α, interleukin (IL)-1β, and cyclooxygenase (COX)-2 gene expression. Seventeen patients reported post-surgical pain. Expression of cathepsins K and S, caspase-3, TIMP1, IL-1β, and TNFα genes before surgery was significantly higher in these patients compared to pain-free patients with OA. Receiver-operating characteristic (ROC) curve analyses confirmed significant associations between these gene expressions and the likelihood of pain development after arthroplasty. High baseline expression of genes associated with extracellular matrix destruction (cathepsins S and K, TIMP1), inflammation (IL-1β, TNFα), and apoptosis (caspase-3) measured in the peripheral blood of patients with end-stage OA before knee arthroplasty might serve as an important biomarker of postoperative pain development.
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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 | 0.000 | 0.001 |
| 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) | 0.001 | 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".