To Tap or Not to Tap: Safely Investigating Monoarthritis of the Knee in Children in a Lyme Endemic Region
Bibliographic record
Abstract
Objectives Differentiating Lyme arthritis (LA) from septic arthritis (SA), an orthopedic emergency, can be a diagnostic challenge. Arthrocentesis is often part of the workup in this setting.[1] A prospective study of >500 children presenting to emergency departments (EDs) with knee monoarthritis in a Lyme endemic area in the US found that a 2-factor prediction rule (absolute neutrophil count (ANC) < 10 000 cells/mm3 and ESR < 40 mm/hr) accurately identified children at low risk for SA.[2] Our objectives were to determine (1) the setting in which children with LA first present to care (2) the rate of arthrocentesis in the diagnostic workup of children with LA, and (3) in those presenting with knee monoarthritis, the proportion who would meet the criteria for low risk of SA. Methods Children with LA seen in pediatric rheumatology clinic at the IWK Health Centre in Halifax, NS (January 2008-June 2023) were identified from a clinical database. Medical record review was conducted to extract demographic, clinical, and laboratory variables relating to the initial point of presentation to care for LA. Descriptive statistics are reported. Results 230 children with LA were identified. 72% were seen in EDs with the remainder seen in office settings, primarily by family doctors. 72% presented with monoarthritis of the knee, 6% with monoarthritis of another joint, and 22% with arthritis in > 1 joint. 26% of children were febrile on presentation/had a history of fever and 46% had a history of episodic arthritis. 78/230 (34%) had an arthrocentesis performed with a median synovial fluid WBC of 57,730 x 10^6/L (range 6,908-97,550). 68/78 (87%) who underwent arthrocentesis presented with monoarthritis of the knee. Of these 49 (72%) had an ESR performed (median 39, range 5-78, <40 in 25) and 67 (99%) had an ANC performed (median 5.3, range 0.6-13.2, <10 in 66). 48/68 (71%) had both the ESR and ANC performed; of these 24 (50%) met the criteria for low risk of SA. Conclusion Approximately three-quarters of children with LA initially presented to EDs, typically with monoarthritis of the knee. When applying the prediction rule to those with sufficient data, we found that half of children would have been classified as low risk of SA raising the possibility that arthrocentesis, an invasive procedure in children, could have been safely avoided. The next phase of this work will be to further investigate factors associated with arthrocentesis in this cohort. [1.] Donders CM. World J Orthop 2022;13(2):122-30. [2.] Grant D. Pediatr Emer Care 2022;32:e881-5.
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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 | 0.002 | 0.010 |
| 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 | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".