Effect of K-wire Reuse and Drill Mode on Heat Generation in Bone.

Abstract

We examined the effect of Kirschner wire (K-wire) reuse and use of oscillating mode on heat generation within cortical bone. Two trocar-tipped K-wires were drilled through the diaphysis of each of 30 human metacarpals and phalanges: one K-wire was inserted in rotary mode and another in oscillating mode. Each wire was reused once. Thermocouples placed within the dorsal and volar bone adjacent to the K-wire drill path measured temperatures throughout each test. Peak cortex temperatures were 25°C to 164°C. Rotary drilling achieves peak temperatures quicker (31 ± 78 seconds vs 44 ± 78 seconds, <i>P</i> = .19) than oscillating drilling, but insertion time is also less, resulting in lower overall heat exposure. This effect is also seen when the K-wire is reused (34 ± 70 seconds vs 41 ± 85 seconds, <i>P</i> = .4). The length of time that cortical bone was exposed to critical temperatures (47°C or more) was significantly higher when a wire was reused (36 ± 72 seconds vs 43 ± 82 seconds, <i>P</i> = .008). Peak temperatures greater than 70°C (a temperature associated with instantaneous cell death) were observed on many occasions. Overall heat exposure may be higher if a K-wire is reused or inserted in oscillating mode. In the absence of external cooling, K-wire insertion into cortical bone can easily expose bone to temperatures that exceed 70°C and may increase the risk of osteonecrosis.