Abstract
Orthopaedic implants and temporary osteosynthesis devices are commonly based on Titanium (Ti). For short-term devices, cell-material contact should be restricted for easy removal after bone healing. This could be achieved with anti-adhesive plasma-fluorocarbon-polymer (PFP) films created by low-temperature plasma processes. Two different PFP thin film deposition techniques, microwave (MW) and radiofrequency (RF) discharge plasma, were applied to receive smooth, hydrophobic surfaces with octafluoropropane (C3F8) or hexafluorohexane (C6F6) as precursors. This study aimed at examining the immunological local tissue reactions after simultaneous intramuscular implantation of four different Ti samples, designated as MW-C3F8, MW-C6F6, RF-C3F8 and Ti-controls, in rats. A differentiated morphometric evaluation of the inflammatory reaction was conducted by immunohistochemical staining of CD68+ macrophages, CD163+ macrophages, MHC class II-positive cells, T lymphocytes, CD25+ regulatory T lymphocytes, NK cells and nestin-positive cells in cryosections of surrounding peri-implant tissue. Tissue samples were obtained on days 7, 14 and 56 for investigating the acute and chronical inflammation (n = 8 rats/group). Implants with a radiofrequency discharge plasma (RF-C3F8) coating exhibited a favorable short- and long-term immune/inflammatory response comparable to Ti-controls. This was also demonstrated by the significant decrease in pro-inflammatory CD68+ macrophages, possibly downregulated by significantly increasing regulatory T lymphocytes.
Highlights
Except for the RF-C3 F8 implants, this was seen for the nestin-positive cells
While the clinical purpose of fracture-fixation devices lies in bone healing, each bone is typically surrounded by muscles, which are a very well perfused and an especially convenient tissue to survey local inflammatory reactions [12]. With regard to the latter, we recently described an increased amount of natural killer cells (NK) cells in the peri-implant tissue of hydrophilic positively charged titanium surfaces coated with plasma polymerised ethylendiamine (PPEDA) compared to controls during the acute phase (d7) of inflammation [30]
The aim of this study was an in vivo evaluation of different anti-adhesive plasmafluorocarbon-polymer (PFP) films on titanium alloy samples, investigating their influence on the local inflammatory tissue response after simultaneous implantation in Lewis rats
Summary
Titanium alloys are still among the most commonly used materials for metallic implants in orthopedic and trauma surgery for long-term use such as joint or hard tissue replacement as well as in temporary fracture fixation devices, including internal and external fixators, intra-medullary nails and screws. This is mainly due to their excellent biocompatibility, high corrosion resistance and low ion-formation tendency [1], which leads to encouraged cell adhesion and the osseointegration process. To the present day the retrieval of metallic fracture-fixation devices is still associated with a risk of nerve and soft tissue damage, and the possibility of harming the newly formed bone by using a great amount of pullout force, and longer operation times [3,4]
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