Structure and magnetic susceptibility of lubricating fluids in synovial joints

The lubricity of medical and tribological preparations based on blood serum and intended for injection into joints is studied. It is found that the lubricity of the blood serum of osteoarthritis patients improves after the use of Doxycycline, a semisynthetic antibiotic from the tetracycline group. The induction method is used to measure the magnetic susceptibility of preparations based on blood serum and synovia sampled from joints with various pathologies. It is shown that all of the preparations are diamagnetics. The atomic-force microscopy method is used to find variations in the structure of patients’ blood serum resulting from the biochemical bonding of Doxycycline with blood proteins. Increase in the imaginary part of the magnetic susceptibility, which characterizes the absorption of the magnetic energy by the sample, is caused by growth of the magnetic moment in the fluid; the moment is directed oppositely to the electromagnetic field of the joint. It initiates the transformation of the lubricating film structure, reduces friction in the joint, and acts as a biophysical ground for methods of transfusion chondroprotection that favor the improvement of the tribological state of joints.