Cadaveric Study of Bone Tissue Temperature During Pin Site Drilling Using Fluoroptic Thermography

Using fluoroptic thermography, temperature was measured during pin site drilling of intact cortical human cadaver bone with a combination of 1-step drilling, graduated drilling, and 1-step drilling with irrigation of 5.0-mm Schanz pins.

A 1440 revolutions per minute constant force drilling was used on tibial diaphyses while a sensor probe placed 0.5 mm adjacent to the drill hole measured temperature. Four drilling techniques on each of the tibial segments were performed: 3.5-mm drill bit, 5.0-mm Schanz pin, 5.0-mm Schanz pin in a 3.5-mm predrilled entry site, and 5.0-mm Schanz pin using irrigation.

One-step drilling using a 5.0-mm Schanz pin without irrigation produced a temperature that exceeded the threshold temperature for heat-induced injury in 5 of the 8 trials. With the other 3 drilling techniques, only 1 in 24 trials produced a temperature that would result in thermal injury. This difference was found to be statistically significant (P = 0.003). The use of irrigation significantly reduced the maximum bone tissue temperature in 1-step drilling of a 5.0-mm Schanz pin (P = 0.02). One-step drilling with a 3.5-mm drill bit achieved maximum temperature significantly faster than graduated drilling and drilling with irrigation using a 5.0-mm Schanz pin (P < 0.01).

One-step drilling with a 5.0-mm Schanz pin into cortical bone can produce temperatures that can lead to heat-induced injury. Irrigation alone can reduce the temperatures sufficiently to avoid damage. Predrilling can increase temperatures significantly, but the extent of any injury should be small.