The assessment of cortical heat during intramedullary reaming of long bones

Background: This experimental study was designed to compare different in vi tro methods of measuring the cortical temperature when reaming the medullar y cavity. This was done to validate an approved mathematical model which ca n be used to determine the temperature gradient in cortical bone in the pre sence or absence of sensors. Methods: Artificial bone was used with an intr amedullary heat source instead of a reamer. Temperatures were measured with thermocouples placed radially and axially in the cortical wall. This metho d with these two measurement positions were compared and used to validate a n approved mathematical model. This model was used to determine the tempera ture gradient in cortical bone in the absence of sensors. Results: The meas urement of the cortical temperature with the thermocouples in a radial posi tion only reflects maximally 14% of the temperature of the reamer (calculat ed 55%). The measurement with the thermocouples in axial position reflects maximally 65% (calculated 70%) of the reamer temperature, which is similar to undisturbed bone. Conclusion: The measuring method with the thermocouple s in a radial position cannot be recommended. It is likely that a much high er temperature is generated and conducted through reaming than has been ass umed until now (C) 2001 Elsevier Science Ltd. All rights reserved.