ALTERED DYNAMIC TIBIOFEMORAL CONTACT PATH LENGTH IN ACL DEFICIENT KNEES
Notice bibliographique
Résumé
INTRODUCTION Osteoarthritis (OA) is a degenerative joint disease characterised by the irreversible degradation of cartilage. Ligament injuries in the knee are a known risk factor for post-traumatic OA (PTOA), 1 the aetiology of which may be due to a combination of altered mechanical and biological factors. In this study, we investigated how anterior cruciate ligament (ACL) tear affects the relative motion of the subchondral bone surfaces in the knee (i.e., “surface interactions”), which is abnormal in ACL-deficient animal models. 2 Tibiofemoral contact path was calculated based on the relative surface motions. We hypothesised that contact path length and shape are altered in ACL-deficient subjects. METHODS Two ACL-deficient subjects and one healthy control subject (male, ages 34-55) underwent magnetic resonance (MR) imaging scans (3T FIESTA sequence) of both knees, then performed walking trials on an instrumented treadmill. During the walking trials, ground reaction force data were collected and fluoroscopy images from two separate views of the knee were taken. Using Amira (VSG, Germany), 3D models of the tibia and femur were generated from segmented MR images, and the in vivo bone alignments were determined using AutoScoper (Brown University, RI). For each in vivo frame, tibiofemoral proximity was mapped in Matlab (version R2013a, Natick, MA). Weighted centroids were calculated for each of the four tibiofemoral surfaces, with closer proximities having a higher weighting. The weighting factor used was w = (15 mm – proximity) 3 , counting only proximities less than 15 mm. Contact path was defined as the path that the weighted centroid made across the frames analyzed. Differences in contact path between left and right knees were assessed qualitatively for each of the subjects. RESULTS For the healthy control subject, contact paths were similar between knees, and were in a straight line, primarily in the anterior-posterior direction. In the two ACL-deficient subjects, the unaffected limb contact path displayed a shape similar to the control limbs. In contrast, the paths in the affected knees were shorter, were not consistently in the same location, and underwent greater mediolateral excursions. DISCUSSION AND CONCLUSIONS The qualitative results from three subjects support the hypothesis that contact path location and direction may be altered in ACL-deficient individuals. The changes in contact path show similarities to past studies with animal models. 2 There exist limitations in the ability to measure surface interactions, as only a small portion of the gait cycle can be analyzed using the dual-fluoroscopy system. Despite this, the dual-fluoroscopy method of bone tracking is superior to traditional marker-based motion capture systems, as it is more accurate than marker-based methods. The results suggest that there may be a correlation between ACL status and contact path shape during level walking. Future studies will increase the number of subjects and explore means of comparing contact paths quantitatively. Identification of associations between contact path shape and severity of joint damage may provide new insight into the pathogenesis of osteoarthritis.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,003 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».