The stabilisation of bone fragments during surgical fracture treatment substantially impacts the healing process. The osteosynthesis, which a surgeon can directly control, determines the mechanical situation at the fracture site. Groups at the Julius Wolff Institute, among others, have shown that mechanical loading has an influnce on the healing process. In addition, factors such as patient anatomy, activity level, and fracture geometry influence the mechanical conditions at the fracture site (internal kinematics, interfragmentary movement) and thus also directly affect tissue regeneration. A well controlled mechanical loading of the fracture site is an essential stimulus and driver of bone healing, yet local interfragmentary kinematics has not been directly investigated or even measured in human patients.

 

Current state of research

It is well known from animal experiments that a certain level of compression of fracture fragments can enhance healing while shear movement delays bone regeneration. Currently, there is no or only limited data available to verify if the findings derived from large animals are also valid and directly transferable to humans. How local mechanical conditions at the fracture site in humans can be controlled by intra operative and post‐operative means is so far largely unknown. Only recently, gait analysis combined with in silico musculoskeletal modelling allows for prediction of the subject‐specific musculoskeletal loading conditions. While such data exists in total joint replacement patients, measurements of the mechanical conditions at fracture sites have so far not been realized for larger groups of human fracture patients.

Factors affecting the deformation (strain) of the tissue in the fracture gap

Factors affecting the deformation of the tissue in the fracture gap (compression and shear).

 

Research goals

Out works aims to assess the ranges of interfragmentary motion occurring through 3D reconstructions of joint movements and implant positions in humans and to stratify beneficial versus detrimental interfragmentary motion by determining the threshold of critical straining in fracture patients. These results will allow a confirmation of the validity of large animal studies and tissue differentiation in in silico models. This project will also lay the foundation for validated recommendations on fracture fixation in humans (e.g. plate working length, plate position, screw positioning) and pave the way for personalised fracture treatment.