Limited Evidence Suggests a Protective Association Between Oral Contraceptive Pill Use and Anterior Cruciate Ligament Injuries in Females: A Systematic Review
Bibliographic record
Abstract
CONTEXT: Female athletes aged 14 to 18 years are at particular risk for anterior cruciate ligament (ACL) injuries. Hormonal factors are thought to predispose them to this injury. Oral contraceptive pills (OCPs) might reduce ACL injury risk, although the literature appears controversial. OBJECTIVE: To evaluate the association between OCP use and ACL injuries in women. The secondary objective was to determine the rates of ACL injuries in the pre- and postovulatory phases of the menstrual cycle in OCP and non-OCP (NOCP) users. DATA SOURCES: Searches were performed across 4 reference databases (PubMed, CINAHL, Embase, Cochrane), abstracts from 6 specialty societies, ClinicalTrials.gov , and reference lists of relevant papers. STUDY SELECTION: We included studies investigating the association between OCP use and ACL injuries in females of any age or the distribution of ACL injuries across the menstrual cycle in OCP and NOCP users. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 3. DATA EXTRACTION: Data regarding study design, population characteristics, OCP details, outcome definitions, analytic methods, and results were extracted from the included studies. The methodological quality of each study was assessed using the Newcastle-Ottawa scale. RESULTS: The search yielded 1305 citations, of which 7 retrospective observational studies met the inclusion criteria. Two large case-control studies with higher methodological quality suggested that OCP use may reduce the risk of sustaining an ACL injury. Five comparative studies examining injury distribution across the menstrual cycle in OCP and NOCP users had conflicting findings, were heterogeneous, and were limited by low methodological quality. CONCLUSION: The evidence suggests OCP use may reduce the risk of ACL injury; however, no conclusions can be drawn regarding differences in risk of ACL injuries between OCP and NOCP users across the menstrual cycle. Studies were limited by small sample sizes, heterogeneity, and methodological concerns.
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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 | 0.007 | 0.058 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.007 | 0.007 |
| Bibliometrics | 0.008 | 0.010 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.003 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 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".