In total knee arthroplalsties, there are risks of revision surgeries because of aseptic loosening, polyethylene wear, and metal component breakage. The data such as model, type, size, and manufacturing companies are required at the time of revision surgeries. However, it is sometimes difficult to acquire such data due to patient's change of address and the elimination and consolidation of hospitals in the long-term. Therefore, we try to use the Radio Frequency IDentification (RFID) in the total knee joint system. The FerVID family (Fujitsu Co. Ltd., Tokyo, Japan) was prepared as the RFID tag. It was radio-resistant below the dose of 50kGy, which allowed gamma sterilization. The RFID tags were embedded into the anterior side of GUR 1050 UHMWPE inserts and 0.3wt% vitamin E blended UHMWPE. The UHMWPE inserts were manufactured by thecompression molding method at the maximum temperature of 220°C and the maximum compressive force of 245kgf/cm2. The manufactured inserts were implanted in fresh cadaveric knees. The tibial base plate was made of Ti6Al4V. The femoral components were made of Co-Cr-Mo or Ti-6Al-4V. Communication Performance was measured with the interrogator (DOTR-920 MHz-band, Tohoku Systems Support Co. Ltd., Miyagi, Japan). The transmission output was up to 1W. Received Signal Strength Indicator (RSSI) was measured 500 times at 15 mm away from the surface of skin in the extension and 90° flexion of the knee (Fig1).Introduction
Materials and methods
The bioactive polyetheretherketone (PEEK) was fabricated by the combination of PEEK and CaO-SiO2 particles, which formed hydroxyapatite on its surfaces in simulated body fluid and showed good mechanical propeties. The study revealed osteoblast-like cell proliferation and gene expression on the bioactive PEEK. Peek and bioactive PEEK discs (24 mm in diameter and 2 mm in thickness) were prepared. Bioactive PEEk was produced by the combination of 80 vol% Peek powder and 20 vol% CaO-SiO2 particles (30CaO · 70SiO2). Discs were sterilized with ethylene oxide gas. The study was approved by the ethics committee in Chiba University. Human osteoblast-like cells were used in the study. The cells at passage 3–5 were used in the experiments. 2 × 105cells /disc were culture at 37°C in a humidified atmosphere with 5% CO2, and the media was replaced every 3 days. At days 3, 7, 21, the culture media, cells and discs were collected respectively. Cell attachment assay was performed. Cells were seeded at a density of 4 × 105 cells /well and incubated for 2 hours at 37 C in a humidified atmosphere with 5% CO2. The cells on the discs were evaluated by DNA content. The real-time PCR was performed with regard to type I collagen (COLI), osteocalcin (OC), osteonectin (ON), osteopontin (OPN), and GAPDH. The alkaline phosphatase activity (ALP) was measeured at 3, 7, and 21 days, which samples as used in the DNA-content assay. Alizalin Red Staining was performed at day 21 to quantify calcification deposits in discs. Results were analyzed using Student's The content of DNA showed similar increases on PEEK and bioactive PEEK in the course of day 3, 7, 21. The cell attachment of bioactive PEEK was two times larger than that of PEEK. Real-time PCR results of human osteoblast-like cells cultured on PEEK and bioactive PEEK discs were shown in Fig. 1. There were no significant differences between cells on PEEK and bioactive PEEK with respect to COL I and ON mRNA expression. However, human osteoblast-like cells on bioactive PEEK presented higher expression of OPN and OCN mRNA at day 21. No significant differences were found in ALP activity of both discs. Calcification deposits were observed only on bioactive PEEK at day 21Materials and Methods
Results
