FP4.12 Statistical Shape Modelling to Differentiate the Symptomatic and Asymptomatic Hip in Bilateral Cam FAI
Bibliographic record
Abstract
Abstract Introduction: Individuals commonly present with bilateral femoroacetabular impingement (FAI) but often only experience unilateral symptoms. This suggests that additional anatomic factors, aside from cam and pincer morphology, may contribute to the presence of symptoms. This study compared the anatomic variations between the symptomatic and asymptomatic hips in bilateral FAI patients using imaging measurements and 3D statistical shape modelling. Methods: Fifty patients with bilateral radiographic FAI, but only symptomatic unilateral FAI (n = 50, m:f = 30:20, age = 25 ± 6 years) were included in this study (IRB #114897). Each patient had plain radiographs along with pre-operative CT scans (SIEMENS Somatom, Germany) to further characterize impingement morphology. The measurements included femoral (femoral neck-shaft angle, medial proximal femoral angle, femoral torsion), acetabular (lateral centre-edge angle, acetabular version) and spinopelvic parameters (pelvic incidence, pelvic tilt, sacral slope). Each patient’s symptomatic and asymptomatic 3D hip models were segmented (Synopsys Simpleware, USA) and statistical shape modelling compared anatomic differences between mean symptomatic and asymptomatic shape models (ShapeWorks 6.4, USA). Results: From imaging measurements, although both symptomatic and asymptomatic sides showed similar femoral cam deformities, femoral torsions, lateral centre-edge angles, and spinopelvic parameters, the symptomatic sides had smaller femoral neck-shaft angles (p = 0.001), medial proximal femoral angles (p = 0.001), and acetabular versions at 1:00 (p = 0.004) than the contralateral asymptomatic sides. From the statistical shape models, the symptomatic group showed a more varus neck and a retroverted acetabulum with slightly increased anterosuperior and decreased posterior acetabular coverage. Additionally, the symptomatic sides’ sacroiliac joint and sacral alar were smaller and anteriorly tilted compared to their contralateral asymptomatic sides. Discussion: The symptomatic hip indicated a more varus neck, retroverted acetabulum, and greater anterior sacral tilt in comparison to the asymptomatic hip. As the cam deformity alone may not be the only indicator for symptoms, characterizing these anatomic relationships through statistical shape modelling can help guide patient-specific diagnosis and treatment strategies for FAI to improve patient outcomes and delay the progression of early hip osteoarthritis.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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) | 0.000 | 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 teacher head, 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".