New cosurface capacitive stimulators for the development of active osseointegrative implantable devices.

Marco P Soares Dos Santos,José A O Simões,Sandra I Vieira,Ana Marote,Edward P Furlani,João Torrão,Jorge A F Ferreira,T Santos,Odete A B Da Cruz E Silva,A Ramos

doi:10.1038/srep30231

Marco P Soares Dos Santos, José A O Simões + Show 8 more

Open Access

https://doi.org/10.1038/srep30231

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Abstract

Non-drug strategies based on biophysical stimulation have been emphasized for the treatment and prevention of musculoskeletal conditions. However, to date, an effective stimulation system for intracorporeal therapies has not been proposed. This is particularly true for active intramedullary implants that aim to optimize osseointegration. The increasing demand for these implants, particularly for hip and knee replacements, has driven the design of innovative stimulation systems that are effective in bone-implant integration. In this paper, a new cosurface-based capacitive system concept is proposed for the design of implantable devices that deliver controllable and personalized electric field stimuli to target tissues. A prototype architecture of this system was constructed for in vitro tests, and its ability to deliver controllable stimuli was numerically analyzed. Successful results were obtained for osteoblastic proliferation and differentiation in the in vitro tests. This work provides, for the first time, a design of a stimulation system that can be embedded in active implantable devices for controllable bone-implant integration and regeneration. The proposed cosurface design holds potential for the implementation of novel and innovative personalized stimulatory therapies based on the delivery of electric fields to bone cells.

Highlights

Non-drug strategies based on biophysical stimulation have been emphasized for the treatment and prevention of musculoskeletal conditions
This study is multifaceted and includes the introduction of a novel cosurface architecture for capacitive coupling (CC) stimulators, the use of numerical models to predict the electric field (EF)/EMFs delivered by the stimulators to cell cultures, and the first osteogenic in vitro responses obtained using such an apparatus
Control of the peri-prosthetic bone stock is mandatory to avoid surgical revisions caused by adverse bone remodeling that can occur after implant insertion[10,13]

Summary

Introduction

Non-drug strategies based on biophysical stimulation have been emphasized for the treatment and prevention of musculoskeletal conditions. Another promising approach to enhance osseointegration and prevent peri-operative infections is to impregnate coatings with drugs (gentamicin, tobramycin and vancomycin, etc.) and/or biomolecules (growth factors, collagen and proteins, etc.)[17,20,21,22] These solutions can present significant drawbacks for bone-implant optimal bonding, namely: (i) extremely complex designs may be required, mainly for multifunctional coatings[17]; (ii) their controllability is reduced, as their behavior cannot be changed after implant insertion; (iii) their delivery dynamics do not consider current biochemical and biomechanical states of the target bone tissues; (iv) their ability to perform personalized delivery is quite limited; (v) long-term release of bioactive substances by these implants is currently unfeasible and will most likely be quite difficult to implement in the forthcoming years; (vi) the simultaneous delivery of different stimuli to different and nearby tissue areas is hard to achieve; and (vii) these solutions are unable to perform controlled time-dependent trajectories of the bone formation process

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