The Effect of Age on Tibia and Fibula Cross-sectional Areas in Young, Old, and Very Old Men
Notice bibliographique
Résumé
It is well established that changes in bone geometry occur with age. However, there has been little investigation about the influence of weight-bearing load on the magnitude of these changes. PURPOSE: To assess the impact of aging on cross-sectional areas of the main weight-bearing (tibia) and minimally weight-bearing (fibula) bones of the leg. METHODS: Serial transverse magnetic resonance images of the right leg were acquired in 13 young (26 ± 3y), 13 old (66 ± 2y), and 13 very old men (83 ± 4y) of similar heights and weights. Cortical area (CA) and medullary area (MA) of the tibia and fibula were measured for 5 images (7mm slice thickness, 3mm slice offset) centered one-third of the distance between the head of the fibula and the lateral malleolus. Total area (TA) for each image was calculated as the sum of CA and MA, and the relative percentage of cortical bone (CORT) was calculated as CA divided by TA. The mean of the 5 images was used for all statistical comparisons; significance set at P<0.05. RESULTS: In the tibia, CA was greater in young (434mm2) than old (377mm2) and very old (340mm2), whereas MA was greater in very old (265mm2) than young (178mm2); old (211mm2). Total bone was not different among the age groups (612, 588, and 604mm2 for young, old, and very old, respectively). Young and old had higher percentages (70% and 65%, respectively) of CORT than did the very old (57%), with no difference between young and old. In the fibula, CA was greater in young (109mm2) than very old (93mm2); old (95mm2). Medullary area was greater in very old (40mm2) than young (25mm2) and old (27mm2). Similar to the tibia, total bone of the fibula was unchanged with age (134, 122, and 133mm2 for young, old, and very old, respectively), and CA expressed as a percentage of the TAwas higher in young and old (81 % and 78%, respectively) as compared to very old (70%). CONCLUSION: Age-related decreases in CA and increases in MA led to a progressive decline in the relative percentage of CORT in both the tibia and fibula. These findings indicate that the weight-bearing role of the tibia does not prevent the age-related loss of CORT. In fact, the relative loss of CORT was slightly greater in the tibia than fibula which suggests that the weight-bearing role of the tibia makes it more susceptible than the fibula to the reduced activity typically associated with aging. Supported by NSERC
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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) | 0,001 | 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 ».