Assessment of thermal damage in total knee arthroplasty using an osteocyte injury model

Polymethylmethacrylate bone cement has been widely used for the anchorage of artificial implants in various orthopedic surgeries. Although it is one of the most successful biomaterials in use, excess heat generation intrinsically causes thermal damage to bone cells adjacent to the bone cement. To estimate a risk of thermal injury, a response of bone cells to cement polymerization must be elucidated because of the occurrence of thermal damage. Thermal damage is affected not only by maximal temperature but also by exposure time, temperature history, and cell type. This study aimed at quantifying the thermal tolerance of bone cells for the development of a thermal injury model, and applying this model for the estimation of thermal damage during cement polymerization in total knee arthroplasty. Osteocytes, osteoblasts, and fibroblasts were respectively subjected to steady supraphysiological temperatures ranging from 45 to 50°C. Survival curves of each cell and temperatures were used to formulate the Arrhenius model. A three-dimensional heat conduction analysis for total knee arthroplasty was conducted using the finite element model based on serial CT images of human knee. A maximal temperature rise of 50°C was observed at the interface between the 3-mm thick cement and the tissue immediately beneath the tibial tray of the prosthesis. The probability of thermal damage to the osteocyte, which was calculated using the Arrhenius model, was negligible at a distance of at least 1 mm away from the cement-bone interface. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2799-2807, 2017.