Development of Silver-Containing Hydroxyapatite-Coated Antimicrobial Implants for Orthopaedic and Spinal Surgery

Abstract

The prevention of surgical site infections is directly related to the minimization of surgical invasiveness, and is in line with the concept of minimally invasive spine therapy (MIST). In recent years, the incidence of postoperative infections has been increasing due to the increased use of spinal implant surgery in patients at high risk of infection, including the elderly and easily infected hosts, the limitations of poor bone marrow transfer of antibiotics, and the potential for contamination of surgical gloves and instruments. Thus, the development of antimicrobial implants in orthopedic and spinal surgery is becoming more and more popular, and implants with proven antimicrobial, safety, and osteoconductive properties (i.e., silver, iodine, antibiotics) in vitro, in vivo, and in clinical trials have become available for clinical use. We have developed silver-containing hydroxyapatite (Ag-HA)-coated implants to prevent post-operative infection, and increase bone fusion capacity, and have successfully commercialized antibacterial implants for hip prostheses and spinal interbody cages. This narrative review overviews the present status of available surface coating technologies and materials; describes how the antimicrobial, safety, and biocompatibility (osteoconductivity) of Ag-HA-coated implants have been demonstrated for commercialization; and reviews the clinical use of antimicrobial implants in orthopedic and spinal surgery, including Ag-HA-coated implants that we have developed.

What to Know about Antimicrobial Coatings in Arthroplasty: A Narrative Review

“…They observed white osseous tissue, both detected macroscopically and confirmed by SEM, on the retrieved implants [43]. Moreover, the same authors [39] published the results of a cohort of fifty cases with a five-year follow-up in which a Ag-HA prosthesis was implanted, reporting good clinical outcomes and no radiographic failures, further supporting the recent development of Ag-HA-coated implants intended for cementless fixation [13,39,44]. Finally, economic burden should be considered [8,28].…”

Use of Biomaterials in 3D Printing as a Solution to Microbial Infections in Arthroplasty and Osseous Reconstruction

“…Apatite also occurs in nature [ 163 , 164 , 165 ], sometimes as inclusions in gems [ 166 ] or in association with other minerals [ 167 , 168 ]. As a biomaterial, it has very good properties [ 169 ], and it is hoped that in combination with metal implants, it will be able to increase the biointegration of the latter [ 170 ]. The potential of hydroxyapatite as a biomaterial is indeed immense [ 24 ] and is associated with its capacity to promote cellular integration and responsiveness [ 171 ].…”

First clinical experience with posterior lumbar interbody fusion using a thermal-sprayed silver-containing hydroxyapatite-coated cage

“…Several antibacterial coatings have been developed for orthopedic implants [ 5 ]. Notable products include silver (Ag)-coated megaprostheses and antibiotic coatings [ 5 , 6 ]. Ag is a well-established coating used for various medical materials (e.g., megaprostheses, vascular and urinary catheters, dressing materials, vascular prostheses, bone cement, suture material, skin dressings, contact lenses, heart valves, and pins for external fixation) because it shows broad-spectrum antibacterial activity, is less resistant than are antibiotics, inhibits biofilm formation, has long-lasting effects, and shows low toxicity in the human body [ 5 – 7 ].…”

“…After it was established that a 3% Ag-HA coating has adequate biocompatibility and low toxicity in vitro and in vivo [ 14 – 16 ], this technology was applied to implants to create a cementless 3% Ag-HA-coated hip system for total hip arthroplasty (THA). However, cytotoxicity, including osteoblast, liver damage, nephropathy, neuropathy, leukopenia, and argyria, has been reported at high concentrations of Ag [ 6 , 8 ]. Argyria is a typical side reaction of Ag that is sometimes severely disfiguring with blue-gray skin discoloration due to Ag precipitation [ 6 , 8 ].…”

“…However, cytotoxicity, including osteoblast, liver damage, nephropathy, neuropathy, leukopenia, and argyria, has been reported at high concentrations of Ag [ 6 , 8 ]. Argyria is a typical side reaction of Ag that is sometimes severely disfiguring with blue-gray skin discoloration due to Ag precipitation [ 6 , 8 ].…”