Recent advances in hydrothermal modification of calcium phosphorus coating on magnesium alloy

Magnesium(Mg) and its alloys have emerged as a favored candidate for bio-regenerative medical implants due to their superior biocompatibility, biodegradability and the elastic modulus close to that of human bone. Unfortunately, the rapid and uncontrollable degradation rate of Mg alloys in chloride-rich body microenvironments limits their clinical orthopedic applications. Recently, Calcium Phosphate(Ca-P)biomaterials, especially Hydroxyapatite(HA), have been broadly applied in the surface functional modification of metal-based biomaterials attributed to their excellent bioactivity and biocompatibility. Hydrothermal modification of Ca-P coatings on Mg alloys has been extensively exploited by researchers for its significant superiorities in controlling coating structure and improving interfacial bonding strength for better osseointegration and corrosion resistance. This work focuses on the up-to-the-minute advances in Ca-P coatings on the surface of Mg and its alloys via hydrothermal methods, including the strategies and mechanisms of hydrothermal modification. Herein, we are inclined to share some feasible and attractive hydrothermal surface modification strategies. From the perspectives of hydrothermal manufacturing technique innovation and coating structure optimization, we evaluate how to foster the corrosion resistance, coating bonding strength, osseointegration and antibacterial properties of Mg alloys with Ca-P coatings synthesized by hydrothermal method. The challenges and future perspectives on the follow-up exploration of Mg alloys for orthopedic applications are also elaborately proposed.

Hydroxyapatite/palmitic acid superhydrophobic composite coating on AZ31 magnesium alloy with both corrosion resistance and bacterial inhibition

The coating-modified magnesium(Mg)alloys exhibit controllable corrosion resistance,but the insufficient antibacterial performance limits their clinical applications as degradable implants.Superhydrophobic coatings show excellent performance in terms of both corrosion resistance and inhibition of bacterial adhesion and growth.In this work,a hydroxyapatite(HA)/palmitic acid(PA)superhydrophobic composite coating was fabricated on the Mg alloy by the hydrothermal technique and immersion treatment.The HA/PA composite coating showed superhydrophobicity with a contact angle of 153°and a sliding angle of 2°.The coated Mg alloy exhibited excellent corrosion resistance in the simulated body fluid,with high polarization resistance(77.10 kΩ·cm^(2))and low corrosion current density((0.491±0.015)μA·cm^(-2)).Meanwhile,the antibacterial efficiency of the composite coating was over 98% against E.coli and S.aureus in different periods.The results indicate that the construction of such superhydrophobic composite coating(HA/PA)on the Mg alloy can greatly improve the corrosion resistance of Mg alloy implants within the human body and avoid bacterial infection during the initial stages of implantation.

Pediatric idiopathic intervertebral disc calcification of the cervical spine

To the Editor:Pediatric idiopathic intervertebral disc calcification(PIIVDC)is a rare childhood disease characterized by calcification of the intervertebral disc and can progress to inflammation or extrusion.[1]The cause of intervertebral disk calcification in children remains unclear.Increasing inflammation and extrusion can eventually lead to neck or spinal pain in some patients.Most reported cases are asymptomatic or mildly symptomatic,and the diagnosis is largely incidental.PIIVDC is thought to be self-limited with favorable outcomes even when treated conservatively by immobilizing the spine and using analgesic therapy.[2]However,there are no gold guidelines for the treatment of this disease at present.[3]In this study,we reported 12 children with cervical disc calcification who presented to our hospital,nine of whom received non-interventional treatment with satisfactory outcomes,in an attempt to outline the presentation,clinical features,and clinical management of this rare disease.