Development of a new orthopedic wire fatigue tester

Abstract

Even though orthopedic wire is commonly used in orthopedic surgery, very little is known about its fatigue properties. This article describes the development of a simple, effective testing machine that simulates the in situ fatigue loading of orthopedic wire. A mathematical analysis has predicted the maximum stress that is generated in wires in the fatigue machine. The fatigue resistance of intact monofilament wires made from different materials was studied. It was found that F90 was more resistant than F562, which in turn was more resistant than F138, grade 2. Also studied was the effect of cold‐forming different notch sizes on the wire surface. It was found that even the slightest notch (1% of wire diameter) reduced the fatigue life by 63%.