Hip muscle changes in femoroacetabular impingement: a systematic review and meta-analysis
Bibliographic record
Abstract
BACKGROUND & AIMS: Femoroacetabular impingement (FAI) is a common hip disorder characterized by abnormal contact between the femoral head and acetabulum, leading to pain, restricted mobility, and potential osteoarthritis. Despite its clinical significance, the role of periarticular muscle alterations in FAI progression remains controversial. This study aimed to systematically evaluate hip muscle strength alterations and their clinical implications in FAI through meta-analysis. METHODS: This systematic review and meta-analysis adhered to PRISMA and AMSTAR guidelines, analyzing five cross-sectional studies (118 FAI patients, 89 controls) to compare hip muscle strength (flexion, extension, abduction/adduction) and functional outcomes (e.g., iHOT-33, HAGOS). Risk of bias was assessed using the Newcastle-Ottawa Scale. RESULTS: FAI patients exhibited significantly reduced hip flexion (- 0.338 Nm/kg) and extension (- 0.379 Nm/kg) strength versus controls, with compensatory neuromuscular adaptations (e.g., preferential biceps femoris recruitment) and altered kinetic chains. Core muscle weakness and inconsistent fatigue patterns were also observed. Secondary outcomes lacked sufficient data for meta-analysis. CONCLUSION: Muscle deficits in FAI are multifactorial, involving strength loss, maladaptive coordination, and kinetic chain disruptions. Targeted rehabilitation should integrate hip-centric and core stabilization exercises, but longitudinal studies are needed to validate therapeutic efficacy.
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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 | 0.011 | 0.025 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.011 | 0.021 |
| Bibliometrics | 0.005 | 0.007 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".