M.Sc Thesis

M.Sc StudentMerkher Yulia
SubjectThe Effect of New Lubricants on the Friction of Human
Cartilageon Cartilage
DepartmentDepartment of Mechanical Engineering
Supervisors PROFESSOR EMERITUS Izhak Etsion
PROF. Doritt Nitzan
PROF. Alice Maroudas
MS. Sarit Sivan


Efficient lubrication is essential for synovial joint mobility in both health and disease. It is well known that extremely low friction is required for proper functioning of synovial joints. Various joints dysfunctions were described in direct association with increased friction or adhesive forces. In several medical treatments, bio-lubricants are injected into human joints to maintain their proper functioning. These bio-lubricants may contain active additives to enhance their performance. In the course of developing and screening such additives, it is important to measure their effect under physiological conditions.

Much work has been done in the past in the field of joint lubrication, most of which utilizes cartilage-on-metal, cartilage-on-ceramic and recently animal cartilage-on-cartilage.  In the present study, a novel approach is undertaken by using a new human cartilage-on-cartilage system to investigate the influence of specific lubricants on the friction coefficients (both dynamic and static) under different conditions.

Exhaustive measurements, studying the ability of different suspensions and solutions to reduce the friction between the cartilage plugs under different conditions were undertaken. It was found that in all cases studied, higher loads resulted in lower friction coefficient. Lubrication of the cartilage surface by synovial fluid, unlike histidine buffer and saline, was impaired at low temperatures. An increase in dwell time resulted in higher friction coefficient. We demonstrated the potential of multi-layered nano scale liposomes to act as effective lubricants in reducing both the static and dynamic friction coefficient compared to various buffers and to synovial fluid from inflamed joints. It was found that DMPC-MLV acts as an effective lubricant by maintaining the friction coefficients within the physiological level (0.02).