A rapid prototyping model for biomechanical evaluation of pelvic osteotomies / Ein Modell zur biomechanischen Bewertung von Beckenosteotomien
Bibliographic record
Abstract
The biomechanical consequences of Salter pelvic osteotomy are difficult to assess due to the complex three-dimensional anatomy of the pelvis. Therefore, models of the dysplastic pelvis are required to allow realistic biomechanical simulation of possible outcomes. A polyamide reversed-engineering model of the left hemipelvis and proximal femur was produced from a computed tomography dataset of an 8-year-old child with severe dysplasia of both hips using selective laser sintering. Hip joint forces before and after Salter osteotomy of the hip were measured using an experimental setup in which an industrial robot was exerting hip joint forces and moments representing one-legged stance. Hip extensor and abductor actuator forces were measured which counterbalanced the joint moments. The preoperative hip joint resultant force was 583 N (270% body weight), while after the operation a mean force of 266 N (120% body weight) was measured. The resulting bony model was geometrically accurate, while apparent joint incongruencies were due to the neglected cartilaginous structures in the model. The preoperative joint resultant force was within the limits reported in the literature. The results suggest that Salter innominate osteotomy not only increases joint contact area but also reduces the hip joint force. Zusammenfassung Die biomechanischen Auswirkungen der Salter-Beckenosteotomie sind wegen der komplizierten dreidimensionalen Anatomie des Beckens schwer abzuschätzen. Deswegen werden Modelle des dysplastischen Beckens benötigt, um die biomechanischen Folgen realistisch zu simulieren. Ein Polyamidmodell der linken Beckenhälfte und des proximalen Femurs wurde hergestellt mit dem selektiven Lasersinter-Verfahren auf Basis eines CT-Datensatzes eines achtjährigen Mädchens mit schwerer Hüftdysplasie. Hüftgelenkskräfte vor und nach der Salter-Osteotomie wurden mit einem Versuchsaufbau bestimmt, bei dem ein Industrieroboter Kräfte und Momente des Hüftgelenks im Einbeinstand erzeugte. Die Muskelkräfte der Abduktoren und Extensoren wurden bestimmt, mit denen die Momente im Gelenk ausgeglichen wurden. Die präoperative Hüftgelenksresultierende betrug 583 N (270% des Körpergewichts), nach der Operation wurde eine mittlere Kraft von 266 N gemessen (120% Körpergewicht). Das Modell des Knochens war geometrisch genau, allerdings fanden sich Inkongruenzen des Gelenks, da der Knorpel nicht berücksichtigt wurde. Die präoperative Hüftgelenkskraft liegt im Bereich der Werte, die in der Literatur berichtet werden. Die Ergebnisse weisen darauf hin, dass die Salter-Beckenosteotomie nicht nur die Kontaktfläche des Gelenks vergrößert, sondern auch die Hüftgelenkskraft reduziert.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.008 | 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".