Differentialin vitrodegradation and protein adhesion behaviour of spark plasma sintering fabricated magnesium-based temporary orthopaedic implant in serum and simulated body fluid

Abstract

The interaction of proteins with implantable metallic surfaces has a great influence on the bioactivity and biodegradation of orthopaedic implants. Initial osseointegration is known to be critical for the long term success of orthopaedic implants. The surface properties of the implant and electrochemical milieu of the surrounding solution such as electrostatic, hydrophobic, and hydrogen bonding interactions significantly modulate protein adsorption by implants. Magnesium (Mg) is considered to improve the adhesion of osteoblasts via ligand binding of the integrin receptors. Mg-based composites, reinforced with hydroxyapatite (HA), are potential candidates for temporary orthopaedic implants. However, their clinical translation requires enhanced degradation resistance in physiological environment so that it is in sync with the healing rate of the bone. The present study deals with the protein adsorption characteristics and degradation behaviour of Mg-HA-based biodegradable implants. Quantitative analysis of apatite inducing ability of composites was evaluated in terms of mass gain in simulated body fluid (SBF) as well as in foetal bovine serum (FBS), by an in vitro immersion study. Incorporation of 5 and 15 wt% HA to Mg-3Zn improved apatite formation up to 35% and 66%, respectively, after 14 days of immersion in SBF. Compared to FBS, SBF is found to be significantly more effective in precipitating apatite on a Mg-HA surface. However, FBS offered more corrosion resistance to Mg-HA than SBF did, as evident from the significant differences in the protein adhesion capabilities of the composite surface when incubated separately in these two mediums. The addition of 15 wt% HA enhanced the protein adsorption capability by ∼35%. These studies highlight the possibility of modulating the degradation and bioactivity of Mg-based composite by tailoring the composition of HA. These findings, in turn, warrant the suitability of Mg-HA composite in orthopaedic application.

In Vivo Study of Local and Systemic Responses to Clinical Use of Mg–1Ca Bioresorbable Orthopedic Implants

“…Some drawbacks of Ma-1Ca alloys include degradation of the two components leading to increased Mg and Ca release from the implantation site [ 22 , 26 , 27 ]. However, continuous monitoring of Mg and Ca serum levels in our study did not record any pathological changes and the values were within limits of physiological scores for the species.…”

“…Some in vitro studies acknowledged the possibility of Mg–1Ca alloys to potentially alter the coagulation process by Mg ions being released as a result of a corrosion process [ 8 , 24 , 26 , 27 ]. However, our study did not find such behavior of the implants, this being demonstrated in two ways: by the evolution of coagulation markers and of the platelet numbers, both major indicators of coagulation power.…”

Biocompatibility and biodegradability evaluation of magnesium‐based intramedullary bone implants in avian model

“…Being light in weight, high strength to weight ratio, and excellent biocompatibility to the natural bone Mg‐3Zn/HA composites found to be the trustable biomaterials suitable especially in birds of wild, pet, and domestic ranges where surgical interventions are intended to be minimized. Additionally, HA positively affects the protein absorption, cell adhesion and bioorganic compound formation as per the in vitro study results 40,41 and also minimizes the adverse tissue reaction of the Mg in combination 42‐44 …”

In Vitro Degradation and In Vivo Biocompatibility of Strontium-Doped Magnesium Phosphate-Reinforced Magnesium Composites

“…The physiological solution consists of a higher concentration of Cl – ion, which further reacts with Mg­(OH) 2 and produces soluble MgCl 2. As a result, continuous degradation of Mg occurs in the immersion medium. On the other hand, in vitro dissolution of magnesium phosphate results in the release of Mg 2+ and PO 4 3– ions .…”