UNILATERAL TENDON INJURY ACCELERATES TENDON MINERALISATION BILATERALLY AND RESULTS IN ALTERED TENDON FAILURE AND VISCOELASTIC PROPERTIES
Notice bibliographique
Résumé
Introduction In humans, mineralised tendons are known to be weaker, possibly as a result of underuse due to pain. Underuse is also reported to cause an increase in hysteresis and a decrease in tendon stiffness. However, the impact of mineralisation on these other tendon properties is unknown. We have developed a needle-injury model which accelerates the spontaneous peritendinous mineralisation of murine Achilles tendons.1 Plain radiography suggests that unilateral injury accelerates mineralisation bilaterally. We hypothesised, therefore, that needle-injured murine Achilles tendons would show reduced strength and stiffness and increased creep (related to hysteresis) compared with contralateral non-injured tendons and tendons from non-injured controls. In addition, we hypothesised that unilateral injury would accelerate mineralisation bilaterally. Methods Ten week old male C57Bl/6 mice (Charles River) underwent left hind (LH) needle-injury and were sacrificed after 20 weeks along with non-injured controls. Hind limbs were examined by micro CT before testing isolated Achilles tendons using the following protocol: 30 cycles of loading between 0.23 and 4.5 N; 300 s dwell at 4.5 N; 495 s dwell at 0.23 N; and a ramp to failure at 5 mm/s. Creep was calculated as the percentage change in gauge length between the first loading peak and the end of the dwell at 4.5 N. Tangent stiffness was calculated from the slope of the force/displacement ramp to failure plot over the range 40–80% of failure force. Within and between group differences were examined using paired T and exact Mann-Whitney U tests respectively. Results Figure 1 shows that within injured individuals the volume of mineralisation was greater (p=0.01) in the LH compared with the right hind (RH) leg, and within non-injured individuals there was no difference between hind limbs (p=0.4). The volume of mineralisation was greater in the LH and RH of injured individuals compared with the respective limbs in non-injured individuals (both p=0.017). The mean failure force was lower (14.8±1.7 vs 16.7±0.7 N) and stiffness (22.9±2.7 vs 19.6±1.5N/mm) and creep (1.9±0.3 vs 3.1±1.2%) were higher in LH compared with RH limbs in six injured individuals (all P≤0.048). Differences between the mean values for seven LH limbs from injured (I) and three control individuals were not statistically significant for failure force (I=1.2 N lower, p=0.28), stiffness (I=3.5 N/mm higher, p=0.067) and creep (I=0.4% higher, p=0.067). All tendons failed close to the insertion except one injured tendon which failed partly in the mid substance and at the insertion. Figure 1. Mean volume (mm3) of peri-Achilles tendon mineralisation in injured (I, n=7) and control (C, n=3) animals. Discussion Unilateral needle-injury accelerated tendon mineralisation bilaterally. In humans, tendon mineralisation and other orthopaedic diseases often occur bilaterally, which may partly relate to interaction between contralateral limbs such as by altered loading of a non-injured limb, signal circulation or bilateral neurological effects of injury. The model presented here is therefore an excellent one to study this phenomenon. Needle-injured mineralised tendons were weaker (consistent with human clinical data), but stiffer and showed less creep than contralateral controls. This suggests that in patients, tendon mineralisation may alter limb function unless muscular adaptation occurs. Most injured and control tendons failed close to the insertion, in contrast to a report of similar tests in which most tendons from adult C57Bl/6J mice failed in the mid substance,2 perhaps explained by potential sub strain differences.
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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 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,001 |
| Bibliométrie | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,001 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,004 | 0,001 |
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 ».