Abstract

Studying the lubrication proprieties of the osteoarthritic synovial fluid allows us to understand the effect of the pathology on the boundary lubrication, mobility, and friction. However, tribological analyses have never been combined with the clinical reality of the presence of worn particles within the synovial fluid and how these may affect the osteoarthritic joint. Part of the problem relates to the tribology methods adopted to study friction which typically relies only on applying conventional, and often inadequate, pin-on-disc techniques.

In this context, we designed a customized two-axis tribometer based on a horizontal counter-face moving in three directions. It allowed us to load/unload the mating surfaces in both vertical and tangential directions and evaluate accurately the tribological performances of different materials under dry or lubricated contact conditions, according to needs. The device incorporates two main units used for driving and measuring purposes. The drive unit which contains three translation stages (two motorized and one manual) and allows the horizontal movement of the counter surface in the three directions to adjust the contact with the specimen, load the system, and perform friction tests.

In this study, synovial fluid with and without worn particles was studied using the customized tribometer described above. This method enables to open the contact at the end of each friction cycle and more accurately reproduces the contact conditions of a natural knee joint and can thus be applied for evaluating the severity of the joint OA and the effect of the treatment provided to patients.

Keywords:

Osteoarthritis (OA), Tribology, Synovial Fluid (SF), Pin-On-Plate