Development of a thread testing machine and evaluation of a suture thread with a knot

Abstract

In this paper, a testing machine for a fine suture thread is developed, and a relation between tension and elongation of the thread with a knot is measured. A fine suture thread is used in microsurgery, and that makes the operation difficult because the thread is fragile. Therefore, an evaluation of the thread is required by surgeons. Conventionally, the thread is evaluated by weight, so that elongation of the thread cannot be measured. This paper develops a testing machine for the fine suture thread using a reaction force observer (RFOB) which calculates force from input of a motor and information of a position sensor, and it enables the machine to measure tension and elongation of the thread at the same time. The testing machine also use tension control which enables the machine to pull the thread from both sides. An experiment was conducted by using the machine. Results showed the tensile strength of a knotted thread was weaker than an unknotted thread and the elongation at rupture of a knotted thread was shorter than that of an unknotted thread. Moreover, the tensile strength and the elongation at rupture did not depend on the number of throws. The machine was verified that it can detect the difference among them,