New approach to orthopaedic repair

The research has been inspired by the relationship between stress modulation and structures inside natural materials including bone, bird feathers and wood that have irregular architectures.

The broken edges in fractures of the femur cause stress to concentrate at the crack tip, increasing the chances that the fracture will lengthen. Conventional methods of repairing a fractured femur typically involve surgical procedures to attach a metal plate around the fracture with screws.

The study, led by University of Illinois Urbana-Champaign civil and environmental engineering Professor Shelly Zhang and graduate student Yingqi Jia in collaboration with Professor Ke Liu from Peking University, is said to introduce a new approach to orthopaedic repair that uses a fully controllable computational framework to produce a material that mimics bone.

The study findings are published in Nature Communications. 

“We started with materials database and used a virtual growth stimulator and machine learning algorithms to generate a virtual material, then learn the relationship between its structure and physical properties,” Zhang said in a statement. “What separates this work from past studies is that we took things a step further by developing a computational optimisation algorithm to maximise both the architecture and stress distribution we can control.”

In the lab, Zhang’s team used 3D printing to fabricate a full-scale resin prototype of the new bio-inspired material and attached it to a synthetic model of a fractured human femur. 

“Having a tangible model allowed us to run real-world measurements, test its efficacy and confirm that it is possible to grow a synthetic material in a way analogous to how biological systems are built,” said Zhang. “We envision this work helping to build materials that will stimulate bone repair by providing optimised support and protection from external forces.” 

Zhang said this technique can be applied to various biological implants wherever stress manipulation is needed.

“The method itself is quite general and can be applied to different types of materials such like metals, polymers — virtually any type of material,” she said. “The key is the geometry, local architecture and the corresponding mechanical properties, making applications almost endless.”