Recently, the use of bone grafts increased in medical practice. Some bone grafts may have different mechanical and biological properties of natural bone. To improve bone grafts we need to record our knowledge about bone. In this work, we are interested in determining the chemical composition of bone fluid in the knee joint as it is a lipid-predominant fluid. Bone samples were obtained from knee cancellous bone. Samples were used of women aged 60 years old with osteoarthritis. Sample preparation is essential to guarantee the quality and dependability of the analysis results. Bone fluid was centrifuged for 15 minutes at 3000 rpm to eliminate the blood and debris. The supernatant was then gathered and filtered. Extraction of total lipids from the bone fluid according to the method of Bligh and Dyer (1959) with modification. The bone fluid of a fresh human cancellous bone was extracted by mechanical compression tests. It consists of 90% lipids. The fatty acid composition of the bone fluid was determined by gas chromatography. Methyl oleate is the most abundant.
