A Brief Review of Current Trends in the Additive Manufacturing of Orthopedic Implants with Thermal Plasma-Sprayed Coatings to Improve the Implant Surface Biocompatibility

Abstract

The demand for orthopedic implants is increasing, driven by a rising number of young patients seeking an active lifestyle post-surgery. This has led to changes in manufacturing requirements. Joint arthroplasty operations are on the rise globally, and recovery times are being reduced by customized endoprostheses that promote better integration. Implants are primarily made from metals and ceramics such as titanium, hydroxyapatite, zirconium, and tantalum. Manufacturing processes, including additive manufacturing and thermal plasma spraying, continue to evolve. These advancements enable the production of tailored porous implants with uniform surface coatings. Coatings made of biocompatible materials are crucial to prevent degradation and enhance biocompatibility, and their composition, porosity, and roughness are actively explored through biocompatibility testing. This review article focuses on the additive manufacturing of orthopedic implants and thermal plasma spraying of biocompatible coatings, discussing their challenges and benefits based on the authors’ experience with selective laser melting and microplasma spraying of metal-ceramic coatings.

Biocompatibility and Corrosion of Microplasma-Sprayed Titanium and Tantalum Coatings versus Titanium Alloy

“…In recent decades, the medical implant industry has undergone profound transformations driven by the pursuit of advanced medical implant technologies to reduce implant failure after joint replacement, speed up implant healing, and prolong the life of implants in the patient's body. Meanwhile, the achievement of implant materials hinges on mechanical behaviors, biocompatibility, and corrosion resistance [1][2][3][4].…”

“…Anodization further augments corrosion resistance and biocompatibility, incorporating bioactive substances. Laser treatment creates specific patterns for bone integration, while plasma spraying offers precise control over microstructure, including essential porosity and roughness for optimal cell adhesion and implant longevity [3,4].…”

“…Therefore, the initial reaction of living tissue to the implant material depends on the properties of the implant surface. To provide the best outcomes, different techniques have been used to manufacture and develop biomaterial applications, such as gas abrasive surface treatment [1,2,4,12], powder technology [18,19], 3D printing technologies [2,4,13,17], vacuum plasma spraying (VPS) [11,12], thermal plasma spraying (TPS) of coatings from biocompatible materials on endoprosthetic implants [20][21][22][23][24], etc.…”

“…Nowadays, not only the choice of materials for coating medical implants and endoprostheses but also the optimal porosity and roughness of these coatings are the subject of debate among researchers; a detailed discussion of the problem can be found in the review article by Alontseva et al [4]. Porosity or surface roughness parameters are not included in international standards for medical implant coatings.…”

Polymer materials to produce wrist-hand orthoses using the additive method

“…Recently, additive manufacturing has become increasingly important in medicine and pharmacy [1]. In pharmacy it enables the creation of new drug delivery systems [2][3][4], and in medicine is being used in tissue engineering [5,6], cardiology [7], dentistry [8], prosthetics [9], neurology [10], orthopaedics [11], to produce precision surgical instruments [12], implants [13], medical devices [14] and anatomical structure models [15].…”