Fundamentals of tribology and the use of ferrography and bio-ferrography for monitoring the degradation of natural and artificial joints

Here, we summarize the principles of tribology and demonstrate the importance of wear particle analysis in condition monitoring. The principles of Ferrography, a technique that was originally developed for condition monitoring of engineering systems, are explained. A new modification of this technique, known as Bio-Ferrography, is reviewed and its application in magnetic isolation of target cells or tissues is demonstrated. Routes for magnetic labeling of biological matter and synthetic polymers are also presented. The hip and knee natural joints are discussed, along with osteoarthritis-their most common noninflammatory disorder. The use of Ferrography and Bio-Ferrography for isolating bone and cartilage particles from the synovial fluids in osteoarthritic joints is reviewed. Artificial joints and the use of Ferrography and Bio-Ferrography for monitoring their wear, either during the development stage or during service, are also reviewed. The concept of soft bearing materials is presented.