Complicated bone fractures: Smart robotic implant aims to improve healing

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Researchers at Saarland University are currently trying to find a way to improve the healing process of bone fractures that tend to heal poorly by using active smart implants. According to a news release from the university on Monday, the implants will not only provide information on how the bones are healing, but also use electrical stimulation to speed up the healing process.

In cases of complicated bone fractures, the healing process can proceed differently. Tibia fractures are especially challenging, because the bones do not always reattach. According to Bergita Ganse, holder of the professorship for innovative implant development (fracture healing) at Saarland University, complications occur in around 14 percent of the patients affected.

Currently, complicated bone fractures are treated by screwing standard implants to the bone pieces. How well new bone tissue forms and how the healing process proceeds can only be seen from X-ray images taken at certain intervals. It can take a long time to realize that healing is going poorly and intervetion would be necessary. The solution is to use an intelligent implant that is designed specifically to meet the patient's needs.

Intelligent implant with physiotherapist

After the operation, this intelligent implant will provide information about how the bones are growing together, such as fracture stiffness and any fracture malpositions. In addition, it should be possible to detect improper strain on the bones at an early stage in order to shorten the healing process. The first step taken by the research team of physicians, engineers and computer scientists was to determine what specific information active implants need to provide in order to optimize the healing process. The "Concepts and clinical aspects of active implants for the treatment of bone fractures," which Ganse calls a basic paper, which has been published in Acta Biomaterialia, summarizes the initial discoveries of the research group.

At the same time, the research team also provides approaches as to what such an active implant could look like. The researchers are using shape memory wires as sensors. These wires are nickel-titanium wires and are as thick as a hair. These wires run through the implant and can be deformed in any way, but then return to their original shape. The elongation of the wires can be used to detect small changes in the bone fracture via electrical resistance measurements.

The measured data will then be used to calculate and programme movement sequences in advance "and control the wires automatically". Because the wires can also be used as "muscles". The robotic implant inserted in the fracture gap is then supposed to "stimulate healing by shortening and lengthening, emitting impulses, waves and electromagnetic fields". The implant could then provide a kind of supportive "physiotherapy".

Promotion of the project

This is still a dream of the future. According to the university, the research team is currently working on "the fine-tuning and details" of the artificial muscles. A prototype of such a smart implant could be available in 2025. The research work is supported by the "Werner Siemens" Foundation. It has been funding the "Smart Implants" project since 2019 with eight million euros. Previously, the Federal Ministry of Education and Research had already funded the previous project "IIP-Extrem - Optimised Patient-Specific Implants" with 2.5 million euros.

(olb)