Secondary stability of a composite biomimetic cementless hip stem

Peer reviewed: YesNRC publication: Ye

Bone remodeling in a new biomimetic polymer-composite hip stem

Adaptive bone remodeling is an important factor that leads to bone resorption in the surroudning femoral bone and implant loosening. Taking into account this factor in the design of hip implants is of clinical importance, since it allows the prediction of the bone-density redistribution and enables the monitoring of bone adaptation after prosthetic implantation. In this paper adaptive bone remodeling around a new biomimetic polymer-composite based (CF/PA12) hip prosthesis is investigated in order to evaluate the amount of stress shielding and bone resorption. The design concept of this new prosthesis is based on a hollow sub-structure made of hydroxyapatite-coated, continuous carbon fiber (BF) reinforced polyamide 12 (PA12) composite with an internal soft polymer-based core. Strain energy density theory coupled with 3-D Finite Element models are used to predict bone desity redistributions in the femoral bone before and after total hip replacement using both polymer-composite and titanium stems. The result of numerical simulations of bone remodeling revealed that the CF-PA12 composite stem generates an excellent bone density pattern compared to the titanium-based stem, indicating the effectiveness of the composite stem to reduce bone resorption caused by stress shielding phenomenon. This may result in an extended lifetime of Total Hip Replacement (THR).Le remodelage osseux adaptatif est un ph\ue9nom\ue8ne important menant \ue0 une r\ue9sorption du tissu osseux dans lequel est implant\ue9e une tige f\ue9morale, ce qui en affecte la stabilit\ue9. La prise en compte de ce facteur dans la conception des proth\ue8ses de hanche rev\ueat une importance clinique particuli\ue8re en permettant de pr\ue9voir la redistribution de la densit\ue9 min\ue9rale osseuse et d\u2019\ue9valuer l\u2019adaptation osseuse cons\ue9cutive \ue0 la pose de la proth\ue8se. Le pr\ue9sent article traite de l\u2019\ue9valuation du remodelage adaptatif du tissu osseux entourant un nouveau mod\ue8le de proth\ue8se de hanche en polym\ue8re composite FC/PA12 biomim\ue9tique que nous avons effectu\ue9e dans le but de quantifier la r\ue9sorption osseuse par d\ue9viation des contraintes (ph\ue9nom\ue8ne de court-circuitage des contraintes) attribuable \ue0 la proth\ue8se. Recouverte d\u2019hydroxyapatite de calcium, la tige f\ue9morale \ue9tudi\ue9e se compose d\u2019une structure externe creuse monopi\ue8ce en polyamide 12 (PA12) renforc\ue9 de fibre de carbone (FC) dont la cavit\ue9 interne est remplie de polym\ue8re mou. L\u2019utilisation du crit\ue8re de l\u2019\ue9nergie de d\ue9formation minimale et de mod\ue8les 3D d\u2019\ue9l\ue9ments finis nous a permis de pr\ue9dire la distribution de la densit\ue9 min\ue9rale du tissu osseux f\ue9moral avant et apr\ue8s la pose d\u2019une proth\ue8se totale de hanche (PTH) comportant une tige f\ue9morale en polym\ue8re composite ou une tige en titane (Ti). Les r\ue9sultats des simulations num\ue9riques du remodelage osseux r\ue9v\ue8lent que la tige f\ue9morale en polym\ue8re composite FC/PA12 permet le maintien d\u2019une meilleure densit\ue9 min\ue9rale osseuse que la tige en titane, ce qui t\ue9moigne de l\u2019efficacit\ue9 de la tige en polym\ue8re composite \ue0 r\ue9duire la r\ue9sorption osseuse attribuable \ue0 la d\ue9viation des contraintes. Ce mod\ue8le de tige f\ue9morale pourrait donc prolonger la dur\ue9e de vie utile de la proth\ue8se totale de hanche.Peer reviewed: YesNRC publication: Ye

Stabilit\ue9 primaire et secondaire d\u2019une proth\ue8se totale de hanche non-ciment\ue9e en mat\ue9riau composite biomim\ue9tique

Peer reviewed: YesNRC publication: Ye

Low thrombogenicity coating of nonwoven PET fiber structures for vascular grafts

Vascular PET grafts (Dacron) have shown good performance in large vessels ( 656mm) applications. To address the urgent unmet need for small-diameter (2\u20136mm) vascular grafts, proprietary high-compliance nonwoven PET fiber structures were modified with various PEG concentrations using PVA as a cross-linking agent, to fabricate non-thrombogenicmechanically compliant vascular grafts. The blood compatibility assays measured through platelet adhesion (SEM and mepacrine dye) and platelet activation (morphological changes, P-selectin secretion, and TXB2 production) demonstrate that functionalization using a 10% PEG solution was sufficient to significantly reduce platelet adhesion/activation close to optimal literature-reported levels observed on carbon-coated ePTFE.Peer reviewed: YesNRC publication: Ye