Mechano-biology of bone regeneration

• Applicant: Professor Dr. Lutz Claes
• Subject Area: Orthopaedics, Traumatology, Reconstructive Surgery
• Term: from 2013 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 245661770

Callus distraction is a surgical technique, which is widely used in orthopaedic surgery for e.g. bone lengthening or defect healing. Although this treatment has been improved in the last decades, there is still a high rate of complications mainly due to unsuitable biomechanical conditions with too much movement and too high tissue strain. To optimize bone regeneration, the fixation devices as well as the distraction protocols have to be further optimized. A prerequisite is the better understanding of the effects of mechanical signals on bone formation (mechano-biology). To make this knowledge useful for the patients, numerical simulation models are needed to calculate the effect of the fixation stability on bone regeneration under different clinical conditions. An important limitation of existing numerical models is, that they are not based upon reliable data but upon assumptions in terms of the material properties of the developing tissue regenerate, the mechanical signals acting at the site of bone regeneration and the mechano-biological tissue differentiation rules.Therefore, this proposal aims to develop an improved numerical model for callus distraction by the optimization of the mechano-biological tissue differentiation rules. For this we will study bone healing under exclusive tensile, compression and shear strain by preventing overlapping mechanical signals from physiological musculoskelettal loading using a new animal model previously developed by our group. Furthermore, we will measure the mechanical properties of the tissue regenerate during the healing process. The exact control of the mechanical conditions will allow improvement of the mechano-biological tissue differentiation rules by the correlation of the mechanical and histological data. The new information will be implemented in our existing numerical model for lateral callus distraction. The model will be calibrated using the data of the mechanical tissue properties measured in vivo. Then a parametric study will be performed. Interfragmentary movements, which differ in direction and magnitude, will be simulated and evaluated as to whether they are critical or not for bone healing. The outcome of this study will be an important step forward in the development of powerful numerical fracture healing and callus distraction models to calculate the effect of the fixation stability on bone regeneration under different clinical conditions.

• DFG Programme: Research Grants
• Participating Person: Professorin Dr. Anita Ignatius