Hip morphology, clinical tests and pain in patients with FAI syndrome: what matters?
Bibliographic record
Abstract
Background Femoroacetabular impingement (FAI), characterized by cam and pincer morphologies, is a common source of hip pain. Understanding the relationships between hip morphology, clinical test outcomes, and pain severity is critical for improving FAI diagnosis and management. This study investigated correlations between cam signs, alpha angle, pincer/retroversion signs, lateral center-edge (LCE) angle, clinical tests, and pain in patients with FAI syndrome. Methods We analysed hip-level data from 51 hips (40 adults) with symptomatic cam and/or pincer morphologies, confirmed by both radiographs and MRI. Participants were physically active (sport≥2–3×/week). Cam, global pincer, and global retroversion signs were counted and measured. Nine clinical pain provocation tests were performed, and pain was measured using the i-HOT pain score. Spearman’s rank correlations (ρ) with 95% confidence intervals (CIs) were computed using pairwise deletion and cluster-robust standard errors to account for within-patient hip clustering. Monotonicity was confirmed. Analyses were conducted in R (version 4.3.2). Results The number of cam signs, alpha angle, as well as the number of pincer/retroversion signs showed no or small and non-significant correlations (ρ=0, 95% CI -0.28 to 0.27; ρ=0.23, 95% CI -0.05 to 0.48; ρ=-0.15, 95% CI -0.41 to 0.13, respectively), whereas LCE angle had a moderate and statistically significant correlation with clinical tests (ρ=0.3, 95% CI 0.03 to 0.54). Clinical tests themselves were strongly and statistically significantly correlated with pain (ρ=0.57, 95% CI 0.34 to 0.73). The number of cam signs (ρ=0.1, 95% CI -0.19 to 0.37), alpha angle (ρ=-0.13, 95% CI -0.4 to 0.15), the number of pincer/retroversion signs (ρ=0.2, 95% CI -0.09 to 0.46), and LCE angle (ρ=-0.23, 95% CI -0.48 to 0.06) showed no notable and non-significant correlations with pain. Conclusions Clinical tests were moderately to strongly correlated with pain. Radiological signs showed negligible to small associations with clinical tests and pain. Wide confidence intervals suggest considerable uncertainty, indicating that morphological severity alone may have limited clinical relevance. These findings suggest that, in addition to morphological alterations, joint movement toward impingement may contribute to symptom generation. Publication History Article published online: 23 October 2025 © 2025. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany
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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 | 0.001 | 0.009 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".