The assessment of cortical heat during intramedullary reaming of long bones

Background: This experimental study was designed to compare different in vitro methods of measuring the cortical temperature when reaming the medullary cavity. This was done to validate an approved mathematical model which can be used to determine the temperature gradient in cortical bone in the presence or absence of sensors. Methods: Artificial bone was used with an intramedullary heat source instead of a reamer. Temperatures were measured with thermocouples placed radially and axially in the cortical wall. This method with these two measurement positions were compared and used to validate an approved mathematical model. This model was used to determine the temperature gradient in cortical bone in the absence of sensors. Results: The measurement of the cortical temperature with the thermocouples in a radial position only reflects maximally 14% of the temperature of the reamer (calculated 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 thermocouples in a radial position cannot be recommended. It is likely that a much higher temperature is generated and conducted through reaming than has been assumed until now (C) 2001 Elsevier Science Ltd. All rights reserved.