Anglia Ruskin University

PhD research student: Dipankar Choudhury
Supervisory team: Dr David Reid, Prof Paul Ingle, Dr Rob Walker, Prof Kevin Cheah, Dr David Wilcox

The challenges facing metal-on-metal hip joints are: (a) the lifespan of the artificial joints and (b) the biological effect of metallic wear debris. According to the Swedish National Hip Arthroplasty Registry, 76% of revision hip surgery is performed because of aseptic loosening. Aseptic loosening is strongly correlated with the wear of the bearing surfaces, which ultimately creates a cytotoxic reaction. Honed surface is a very well established technique in the engine surface due to its better tribological performance. In the present study, a number of honed surfaces were investigated in a redesigned TE77 high frequency friction simulator. The dimensions of the specimens were- 50 mm diameters and 50 µm clearance. A dynamic loading was applied, synchronised with current gait analysis result from literature, while the temperature was controlled at 37o C. The output data including the friction coefficient, friction force and contact potential were recorded through a connected computer via COMPEND 2000 software. The plateau-honed surfaces were produced on the moving specimens with controlled load, speed and various grades of emery paper using a specially designed tool. The surface textures were scrutinised by using SEM and Taylor Hobson Precision.

The best honed surface (honed surface-3) among the selected experimental surfaces produced 50% less mean dynamic friction coefficient and 38% less static friction coefficient with compare to plane surface after at the end of 15x105 cycles. The wear and surface damage were also significantly less in that honed surface. On the other hand, the plane surface had number of wear signs including adhesive and fatigue wear, similar wear patterns were observed in each of the experimental plateau-honed surfaces. The honed parameters of the honed surface-3 were identified as- honed angle 45o, 40±10 µm width and 17±2 depth. The minimum film fluid film thickness also recorded relatively higher in case of the honed surface. This was evidence that lubrication distribution and hydrodynamic lubrication were better in well designed plateau-honed surfaces. Thus, this technique could reduce wear and wear debris release rate. Therefore, it could provide longer durability of joint and improve the acceptability of metal-on-metal hip joints longer.