Keywords
Friction; 50mm diameter metal-on-metal BHR hip resurfacing prostheses; Diametral clearances; Blood; Clotted Blood; BS+CMC; BS+HA+CMC
Abstract
In real life, immediately after joint replacement, the artificial joint is actually bathed in blood instead of synovial fluid. Blood contains large molecules and cells of size ~ 5 to 20 micron suspended in plasma and considered to be a non-Newtonian (pseudoplastic) fluid with viscosity ~ 0.01 Pas at shear rates of 3000 s-1. The effect of these properties on friction is not fully understood and, so far, hardly any studies have been carried out regarding friction of metal-on-metal bearings with various clearances in the presence of lubricants such as blood or a fluid containing macromolecules such as Hyaluronic Acid (HA) which is a major component of synovial f luid, increasing its viscosity and lubricating properties. In this work, therefore, the frictional behaviour of a group of Smith and Nephew Birmingham Hip Resurfacing devices with a nominal diameter of 50mm and diametral clearances in the range ~ 80 to 300µm, in the presence of blood (clotted and whole blood), a combination of Bovine Serum (BS) with Hyaluronic Acid (HA) and Carboxymethyl Cellulose (CMC) adjusted to a range of viscosities (~0.001-0.2 Pas), and bovine serum with CMC adjusted to a similar range of viscosities have been investigated.
The results suggest that reduced clearance bearings have the potential to generate high friction especially in the presence of blood which is indeed the in vivo lubricant in the early weeks after implantation. Friction factors in higher clearance bearings were found to be lower than those of the lower clearance bearings using blood as the lubricant.
Citation
Youseffi M, Afshinjavid S and Javid F. The Effect of Clearance upon Friction of Large Diameter Hip Resurfacing Prostheses using Blood and Combinations of Bovine Serum with Aqueous Solutions of Cmc and Hyaluronic Acid as Lubricants. SM J Biomed Eng. 2017; 3(3): 1019.