Conduction analysis of cement interface temperature in total knee arthroplasty.

We applied an axisymmetric model of the tibia to a finite element method and analyzed the heat conduction from bone cement in total knee arthroplasty using numerical simulation with the finite element analysis software, ABACUS. We hypothesized the thermal necrotic map of bone. Moreover, we suggested a method for preventing thermal necrosis of bone using this simulation. We adopted an initial temperature of 32?C and a cement layer of 3mm to our simulation and analyzed heat conduction. The maximum temperature into the cement layer was 65?C and 56?C at the bone-cement interface 200 sec after the start of heat generation. Bone necrosis was observed approximately 2mm from the bone-cement interface. To thin the cement layer, the maximum temperature and bone necrotic area reduced. At a cement layer of less than 1mm no bone necrotic area was observed. To lower the initial temperature of the bone surface, the maximum temperature and bone necrotic area was also reduced. At an initial temperature of less than 28?C we did not find any bone necrosis. Even if we hypothesized pouring cold water around the prosthesis, the maximum temperature did not reduce at any time, neither did the necrotic area reduce. We should make the cement layer as thin as possible and cool the bone before cementing to prevent thermal bone necrosis.