The material that the prosthetic is made of has a very large impact on not only the price of the part but the ultimate strengths and stresses of the prosthetic. The more affordable materials for prosthetics such as Polypropylene and Polyethylene have Ultimate Tensile Strengths around 5,000 psi whereas the top of the line Carbon Fiber prosthetics, such as the blades worn by Pistorius have an Ultimate Tensile Strength around 500 ksi, a factor of 100,000 stronger. A finite element analysis of a Polypropylene revealed that under max stress the prosthetic would have a 5% elongation, while the percent elongation that the carbon fiber of Pistorius’ blades can top out at 24%.
Pistorius’ activity in the Olympics has caused quite an interesting debate to come about. If it takes him technically less energy to move his feet, but is able to produce less torque and unable to manage corners well due to his lack of ankles, should he still be able to compete? Researchers are currently working on completely replicating a human leg instead of the current J-curve prosthetic design, but have yet to make any real advancement due to weight and strength capabilities. Regardless of whether or not his blades have given him an advantage or a disadvantage, it is still incredible to see someone overcome such adversity with the advances in mechanical engineering and biomedical technology.
 Hasish, Rami “Oscar Pistorius’ Prosthetic Legs…” Huffington Post 8/10/2012 University of Southern California
 Richardson, Victoria “Analysis of a Lower Limb Prosthesis” Worecester Polytechnic Press 4/24/2008
 Gerschutz, Maria “Tensile Strength and Impact Resistance…” Journal of Rehabilitation Research and Development The Ohio Willow Wood Company, Mt. Sterling Ohio ,Volume 48 Number 8, pgs. 987-1004. 2011