Change in the particle size distribution of poly (L-lactide) wear debris by gamma-ray irradiation

It has been known that the wear debris causes failure of implant prostheses. In this study, the convenient wear test of poly(L-lactide) (PLLA) was established and the particle size of PLLA wear debris was analyzed using the Coulter counter. Then, the changes in the particle size distribution of PLLA wear debris by gamma-ray irradiation were observed dose-dependently at the dose of 10, 25 and 50 kGy. With the increasing irradiation dose, the particle size distribution of PLLA wear debris shifted toward the smaller diameter size, and the mean diameter of PLLA wear debris significantly decreased. In addition, the tensile strength and the molecular weight of irradiated PLLA were also decreased by increasing the irradiation dose. The lowering of the molecular weight by gamma-irradiation resultingly caused the decreases in tensile strength of irradiated PLLA and the particle size of the wear debris derived from irradiated PLLA.