The bulge sign – a simple physical examination for identifying progressive knee osteoarthritis: data from the Osteoarthritis Initiative
Bibliographic record
Abstract
OBJECTIVE: To examine whether the presence of bulge sign or patellar tap was associated with frequent knee pain, progression of radiographic OA (ROA) and total knee replacement (TKR). METHODS: This study included 4344 Osteoarthritis Initiative participants examined at baseline for bulge sign and/or patellar tap. The clinical signs were categorized as no (none at baseline and 2 years), resolved (present at baseline only), developed (present at 2 years only) and persistent (present at both time points). Frequent knee pain and progression of ROA over 4 years and TKR over 6 years were assessed. Binary logistic regression was used to examine the associations. RESULTS: A total of 12.7% of participants had bulge sign only, 2.0% had patellar tap only and 3.3% had both. A positive baseline bulge sign was associated with an increased risk of frequent knee pain [OR 1.31 (95% CI 1.04, 1.64), P = 0.02] and TKR [OR 1.47 (95% CI 1.06, 2.05), P = 0.02]. Developed bulge sign was associated with an increased risk of frequent knee pain [OR 1.75 (95% CI 1.34, 2.29), P < 0.001] and progressive ROA [OR 1.67 (95% CI 1.11, 2.51), P = 0.01]. Persistent bulge sign was associated with an increased risk of frequent knee pain [OR 1.60 (95% CI 1.09, 2.35), P = 0.02], progressive ROA [OR 1.84 (95% CI 1.01, 3.33), P = 0.045] and TKR [OR 2.13 (95% CI 1.23, 3.68), P = 0.007]. Patellar tap was not examined for its association with joint outcomes due to its low prevalence. CONCLUSION: The presence of bulge sign identifies individuals at increased risk of frequent knee pain, progression of ROA and TKR. This provides clinicians with a quick, simple, inexpensive method for identifying those at higher risk of progressive knee OA who should be targeted for therapy.
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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 | 0.001 | 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".