Hip capsular thickness correlates with range of motion limitations in femoroacetabular impingement
Bibliographic record
Abstract
PURPOSE: Femoroacetabular impingement (FAI) is a clinical entity of the hip causing derangements in range of motion, pain, gait, and function. Computer-assisted modeling and clinical studies suggest that patients with FAI have increased capsular thickness compared to those without.A retrospective chart review was performed to assess relationships between capsular thickness, hip range of motion, and demographic factors in patients with FAI. METHODS: Local Research Ethics Board approval was obtained to extract electronic medical records for 188 patients at a single institution who had undergone hip arthroscopy. Procedures were performed from 2009 to 2017 by a single, fellowship-trained, board-certified sports medicine orthopaedic surgeon. Inclusion criteria were preoperative hip range of motion testing, positive clinical impingement testing, and magnetic resonance imaging (MRI) of the affected hip. Patient demographics, hip range of motion, and time to surgery were recorded. MRIs were reviewed by a board-certified musculoskeletal radiologist blinded to clinical data. Maximum thickness of the anterior hip capsule was measured in axial, axial oblique, and sagittal oblique sequences. Anterior capsular thickness was also measured at the level of the femoral head-neck junction in axial sequences (axial midline). RESULTS: Axial midline capsular thickness was negatively correlated with hip flexion (r = - 0.196, p = 0.0042) and internal rotation (r = - 0.143, p = 0.0278). Significant differences were seen between genders in axial midline thickness (5.3 ± 1.4 mm males/4.8 ± 1.3 mm females, p = 0.0079), flexion (113° ± 18° males/120° ± 17° females, p = 0.0029), and internal rotation (23° ± 13° males/29° ± 12° females, p = 0.0155). Significant differences also existed between side affected in flexion (116° ± 17° right/119° ± 17° left, p = 0.0396) and internal rotation (26° ± 12° right/29° ± 13° left, p = 0.0029). Positive correlation was observed between axial oblique capsular thickness and flexion (r = 0.2345) (p = 0.0229). CONCLUSIONS: Increased anterior hip capsular thickness at the femoral head-neck correlates with limitations in hip range of motion in FAI. The strength of this relationship may be affected between pathologies, genders, and affected side. Pathologic thickening of the hip capsule may contribute to restricted hip mobility on clinical examination, and elucidation of this relationship may provide guidance into capsular management during hip arthroscopy. LEVEL OF EVIDENCE: 4, retrospective case series.
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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 | 0.006 |
| 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".