Effects of hydroxyapatite coating on Ti‐6 Al‐4V implant‐site infection in a rabbit tibial model

Abstract

To investigate the effect of implant type after direct contamination, a hydroxyapatite-coated or noncoated Ti-6A1-4V implant was inserted into both tibiae of 32 New Zealand White rabbits. Prior to implantation, the left tibia was contaminated with increasing concentrations of Staphylococcus aureus (10(2)-10(5) colony-forming units), ranging from very low (10(2)) to relatively high (10(5)). Four weeks after implantation, half of the tibial bone adjacent to the implant was harvested for bacteriological examination. Bacterial counts were quantified by plating serial dilutions. For the histological evaluation, sections of the implant with the remaining tibia were examined by semiquantitative scoring of infection parameters. The bacteriological data showed the inoculum dose and implant type to have a significant effect on the culture outcome: more bacteria were retrieved from the hydroxyapatite-coated implants than from the noncoated titanium implants. Histological evaluation showed an increased score for the infected left tibiae compared with their contralateral control. In addition, with increasing inoculum dosage, the difference between the two types of implant increased. We demonstrated that infections can occur with biocompatible, noncemented implants and that they are related to the dose of the original inoculum. Bacteria were more likely to grow onto or next to the hydroxyapatite implants than on titanium implants and resulted in a more severe histopathological characterization of infection.

Decreased bacteria activity on Si3N4 surfaces compared with PEEK or titanium

“…64 Orthopedic implants made of porous Ti are commonly coated with hydroxyapatite to promote osteointegration, but this strategy may lead to increased harboring of S. aureus bacteria, more severe infection, and less osteointegration when compared with uncoated Ti. 65,66 The results of this present study show that Si 3 N 4 has intrinsic bacteriostatic properties, whether in an as-fired or smooth-surface morphology. This study did not elucidate the precise mechanism of Si 3 N 4 anti-infectivity, but results suggest that material hydrophilicity and surface chemistry may contribute to less biofilm formation ( Figure 3) and lower bacteria counts (Figure 4) on Si 3 N 4 when compared with Ti or PEEK.…”

A Silver Ion-doped Calcium Phosphate-based Ceramic Nanopowder-coated Prosthesis Increased Infection Resistance

“…The suspension was further diluted with sterile saline solution to achieve 10 4 CFU/mL. The rabbits were inoculated with 50 lL bacterial suspension (amount of inoculum: 5 9 10 2 CFU) [11,31].…”

“…Two examiners (CB, DB) blindly examined 10 serial bone sections from each animal and evaluated each section for degree of inflammation, type of inflammatory cells (polymorphonuclear or mononuclear), and edema. The medullary cavity (leukocytes, microabscesses, granulation tissue, fibrosis), cortex (destruction of the cortex, enlarged Haversian canals, leukocytes, microabscesses, granulation tissue, fibrosis), and periosteal reaction were scored according to methods reported previously [25,31] (according to severity from 0 to 4) in at least 10 regions of interest. The total score was calculated and noted for the statistical analysis.…”

Novel model for studying hematogenous infection in an experimental setting of implant‐related infection by a community‐acquired methicillin‐resistant S. aureus Strain

“…The animals were obtained from a professional stock breeder, and have been proven suitable for the investigation of osteomyelitis. [26][27][28] All animals were preoperatively evaluated by a veterinary doctor through physical examination (body weight, rectal temperature), complete white blood cell (WBC) count, and erythrocyte sedimentation rate (ESR) to rule out infection. Normal values for this type of animals are as follows: WBC (5.2-12.5 Â 10 3 /ml), 29 ESR (0-20 mm/h), 30 temperature (388-398C), 29 and weight (2.9-3.6 kg) 29 for approximately 4-monthold rabbits (skeletally mature) which were used in this study.…”

“…With the use of a sawing microtome, sections 3-4-mm thick were obtained for light microscopy evaluation for signs of infection. Semiquantitative scoring of all 30 specimens was performed blindly with the assistance of a pathologist (L. K.) according to the scoring system, first described by Petty et al 35 and then modified by Vogely et al 28 in order to be adapted to a situation of infection around a noncemented implant. Each sign of histological abnormality was scored according to severity as none (0), slight (2), moderate (4), or severe (6), depending on the presence of leucocytes, microabscesses, granulation tissue, fibrosis in the medullary canal and cortex (in addition destruction and presence of enlarged Haversian canals), and the quantity of periosteal reaction.…”