Risk of tendon failure with repeated passage of Kirschner wires or hypodermic needles: an experimental study.

During hand surgery, tendons may be at risk of damage. This biomechanical study aims to assess the risk of tendon rupture due to passage of Kirschner wires or hypodermic needles. Porcine extensor tendons were divided into four groups. Group 1: a control group was tested to ensure that repeated stress alone did not cause failure. Group 2a: 1.1-mm Kirschner wires were hand pushed through tendons 50 times and then stressed to 40 N, repeated until tendon failure. In Group 2b, K-wires were passed while rotating using a drill. Group 3: the experiment was repeated using a 20 G hypodermic needle. Group 2a tendons required a median of 2450 passes (1150-3500) to propagate failure, Group 2b a median of 2250 (1200-3850) and Group 3a median of 200 passes (150-450). The risk of tendon rupture from wires or hypodermic needles in procedures appears very low.