Heat of intramedullary reaming.

Cortical ischemia and necrosis after intramedullary reaming are well documented. Numerous authors have described ischemic changes attributed to mechanical disruption of the arterial system of the intramedullary canal. Few have investigated the potential thermal injury during extreme temperatures generated during intramedullary reaming. We reamed the medullary canal of cadaveric tibial and femoral diaphyses using a flexible shaft reaming device and stainless steel intramedullary reamer. The temperatures generated by reaming from 11 mm through 15 mm in 1 mm increments were measured after each pass. In the 17 specimens tested, we observed an incremental rise in temperature with reaming. The mean intramedullary temperature after reaming was 52 C ( +/- 8.3) with a range of 42 to 67 C. The mean extramedullary temperature was 46 C ( +/- 8.3) with a range of 36 to 59 C. There was a direct correlation between temperature increase and reamer size. Our results indicate that temperature elevations generated during intramedullary reaming are sufficient to cause thermal necrosis, and may cause delayed healing in vivo.