Abstract
This is a paper in two parts. Part 1 gives details of fatique tests carried out on Howse II hip prostheses. Three types of tests were carried out in accordance with three different draft test standards. Standard (I) was BSI DD91: 1984 in which the load range is 0.3–4.1 kN and the antero-posterior offset angle is 15°. Standard (II) was BSI DD91: 1986 where the load range is 0.3–2.3 kN and the offset angle is 9°. Standard (III) was ISO/DP 7206/3 in which the load range is 0.3–4.1 kN and the offset angle is 0°. Four specimens were tested according to each standard. It was found that all the specimens tested according to standard (I) failed by fatigue after less than 6 times 105 cycles. All the specimens tested according to standards (II) and (III) withstood 5 times 106 cycles without failure. It is clear that the offset angle has an important influence on the fatigue life of the prosthesis. It is concluded that tests according to standard (I) are too severe, while tests according to standards (II) and (III) are either adequate or lax. This led to Part 2 of the investigation where the stresses in the prostheses were measured and calculated.
Get full access to this article
View all access options for this article.
