EP256 Lower limb biomechanics in dynamic tasks before and after periacetabular osteotomy
Bibliographic record
Abstract
Abstract Hip dysplasia reduces femoral head coverage and elevates joint pressure, accelerating cartilage wear and risk of early osteoarthritis. Periacetabular osteotomy (PAO) aims to correct this anatomical defect and improve joint function. Despite clinical benefits, many patients ultimately require total hip arthroplasty. To better understand joint loading in dysplastic hips, this study assesses the effect of PAO on hip reaction forces during walking and squatting. Ten participants (4♂, 6♀; age 18–43) with unilateral acetabular dysplasia were assessed preoperatively and ~10 months post-PAO. Lateral center-edge angle (LCEA) and Tönnis were extracted from clinical imaging data. Three-dimensional kinematics of the pelvis and lower limbs during walking and squatting were captured using an optoelectronic motion analysis system (Vicon). Ground reaction forces were concurrently recorded via force platforms (AMTI). Joint kinematics and hip reaction forces were estimated via musculoskeletal modeling in OpenSim. Radiographic parameters were analyzed with paired t-tests. Time series data were evaluated using repeated-measures ANOVA through statistical parametric mapping to assess effects of side (healthy vs. affected) and surgery (pre vs. post; p < 0.05). Postoperatively, radiographic angles normalized (LCEA: 16±10 → 28±6°, Tönnis: 13±10 → 4±6°; p<0.001). In squatting, hip abduction during the descent decreased on the affected side (6.3±6.0 → 4.5±5.5°) and increased on the healthy side (4.2±4.1 → 5.8±3.7°; interaction: p<0.05). Peak posterior hip reaction force became more symmetric (interaction: p<0.05), reflecting increased loading on the healthy side (2.3±0.3 → 2.6±0.5 N/kg) and decreased loading on the affected side (2.8±0.3 → 2.7±0.4 N/kg). Walking showed a bilateral reduction in posterior reaction forces (1.0±0.1 → 0.7±0.2 N/kg; p<0.05) at toe-off, and in adduction angle (0.6±1.1 → -0.9±0.6°; p<0.05) during the loading phase. Both squatting and walking exhibited reduced posteriorly directed hip reaction forces following surgery. This change is likely attributable to the reorientation of the acetabulum, which increased anterior coverage. Prior to correction, patients may have compensated for deficient anterior coverage by anteriorly rotating the pelvis, thereby relying more heavily on the available posterior coverage. These biomechanical changes may help delay osteoarthritis progression by reducing joint loading in patients with acetabular dysplasia.
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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 | 0.000 | 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) | 0.011 | 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".