DIFFERENCE IN THE MICROMOTION PREDICTED BY FINITE ELEMENT ANALYSIS WHEN PRESS-FIT AND CONTACT OR PRESS-FIT AND GAP IS ACHIEVED AFTER SURGERY
Notice bibliographique
Résumé
Introduction Cementless stems are fixed to the surrounding bone by means of mechanical press-fit. Short-, mid-, and long term outcomes are good for this type of fixation despite that only a part of the stem surface is in contact with the surrounding bone. Several studies show that the contact ratio achieved after surgery between the stem and the surrounding bone ranged between 15% and 60%. Then, only a part of the stem-bone interface presents a press-fit. The rest of the stem-bone interface is only in contact or presents an interfacial gap inherent to the surgical technique. Therefore, this study aimed to investigate the difference in the primary stability of a cementless stem between a press-fit combined with contact and a press-fit combined with gap achieved after the surgery. Materials & Methods A finite element study was carried out on a composite bone implanted with a femoral stem and subjected to physiological loading simulating stair climbing [1]. All materials were defined as isotropic homogeneous. The stem-bone interface was divided into 4 areas: the superior plasma spray, the inferior plasma spray, the polished surface of the stem in contact with the cancellous bone, and the plasma spray surface of the stem in contact with the cortical bone. Each contact area can be either in contact with a press-fit, either in contact without press-fit or can present a gap. This result in a total of 28 cases: 14 where there is a press-fit combined with contact and 14 cases where there is a press-fit combined with gap. Results When 1 press-fit is combined with 3 contacts, the average micromotion reaches 26µm. The average micromotion increases up to 47µm (+45%) when 1 press-fit is combined with 3 gaps. The detailed results can be seen on Figure 1. When 2 press-fits are combined with 2 contacts, the average micromotion reaches 28µm. The average micromotion increases up to 36µm (+29%) when 2 press-fit are combined with 2 gaps. The detailed results can be seen on Figure 2. When 3 press-fits are combined with 1 contact, the average micromotion reaches 31µm. The average micromotion increases up to 34µm (+9%) when 3 press-fits are combined to 1 gap. The detailed results can be seen on Figure 3. Discussion As expected, micromotion predicted when press-fit is combined with contact is lower than when press-fit is combined with gap. However, the average micromotion increases with the increase of press-fit when combined with contact (from 26µm to 31µm (+19%)). The increase of the press-fit area combined with contact lead to a slightly increase of the micromotion. Conversely, the average micromotion decreases with the increase of press-fit when combined with gap (from 47µm to 34µm (−28%)). This is due to the increase of the press-fit area, and then the gap has a lesser effect. This study also shows that the difference in the micromotion between press-fit when combined with contact and press-fit when combined with gap decreases with the increase of the press-fit.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 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 tête enseignante, 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 ».