Numerical simulation of strain-adaptive bone remodelling in the ankle joint

FE models of the bone-implant assembly for both the tibia and the talus have been developed. Bone characteristics such as the density distribution have been applied corresponding to CT scans. A force of 5,200 N, which corresponds to the compression force during normal walking of a person with a weight of 100 kg according to Stauffer et al., has been used in the simulation. The bone adaptation law, previously developed by our research team, has been used for the calculation of the remodelling processes.A total bone mass loss of 2% in the tibia and 13% in the talus was calculated. The greater decline of density in the talus is due to its smaller size compared to the relatively large implant dimensions causing remodelling processes in the whole bone tissue. In the tibia, bone remodelling processes are only calculated in areas adjacent to the implant. Thus, a smaller bone mass loss than in the talus can be expected. There is a high agreement between the simulation results in the distal tibia and the literature regarding.In this study, strain-adaptive bone remodelling processes are simulated using the FE method. The results contribute to a better understanding of the biomechanical behaviour of the ankle joint and hence are useful for the optimisation of the implant geometry in the future.Arthrodesis is a preferred and most used operative therapy in advanced symptomatic arthrosis of the ankle [1]. The objective is pain relief with a stable osseous fusion. Disadvantages are the loss of movement in the joint accompanied by an increased mobility in the transversal joint (Chopart joint) as a compensation reaction. This can lead to secondary overloading and arthrosis. The activity of the patient is significantly limited by arthrodesis. Further disadvantages are the risk of non fusion as well as the long rehabilitation time [2-6].Total ankle replacement (TAR) is an often used alternative procedure in advanced arthrosis of the ankle. Preoperative and postoperative radiographs of