An implant identical to a natural one
For the first time, a polymer prosthesis imitating the bone structure has been successfully implanted
NUST MISIS Company blog, Habr
A team of scientists from Biomimetix, a small innovative enterprise implementing the development of NUST MISIS, successfully implanted a biomimetic hybrid prosthesis made of ultra-high molecular weight polyethylene and titanium alloy into the femur for the first time in the world. The successful operation was carried out by order of one of the Moscow veterinary clinics "MedVet".
An operation to implant an experimental biomimetic (similar in structure to the tissues of a living organism) prosthesis for a dog with osteosarcoma of the femur was successfully performed in August 2018. After a few days, the animal was able to walk again, and, according to forecasts, mobility will soon be fully restored.
Osteosarcoma (osteogenic sarcoma) is a fast–growing cancerous tumor, the cells of which originate from bone tissue, lead to its gradual destruction and, accordingly, loss of mobility. Osteosarcoma is the most common type of bone tumor in both humans and animals.
Treatment necessarily includes a course of chemotherapy and surgical intervention with the removal of the affected tissue. Advanced technologies allow for organ–preserving surgery - in this case, a metal, ceramic or polymer implant is placed instead of the removed bone section. Despite the fact that such prostheses allow you to restore mobility, they differ greatly in structure from bone tissue, and this can lead to a number of significant difficulties.
Fig. 1. X-ray of the hind limb of the animal before the operation. Osteosarcoma affected almost 11 cm of bone tissue.
"Traditional materials for medical prosthetics have a number of significant disadvantages: for example, titanium implants take on too much load intended for the bone, and the latter begins to thin out. In such a situation, the bone at the junction with the prosthesis may break. Another option is ceramics, but it is more fragile, which may limit the size of the bone tissue to be replaced. In addition, the structure of these materials does not allow them to "fuse" with the bone – constant tight fixation is required," explains Fyodor Senatov, CEO of Biomimetix, researcher at the Center for Composite Materials at NUST MISIS.
The Biomimetix team has been developing biomimetic implants for several years. Scientists work with ultra–high molecular weight polyethylene – a proven biocompatible material - but modify it in a unique way, giving the implants the required structure. This is the first experience in the world of creating biomimetic prostheses from such a polymer material.
Fig. 2. X-ray of the hind limb of the animal after the implant is installed.
By order of the network of veterinary centers "MedVet" in August of this year, the Biomimetix team developed an experimental biomimetic femoral prosthesis for a dog with osteosarcoma.
"Since the dog turned out to be large – a great dane, used to move actively, and it took about 11 cm of bone to be removed, it was decided to make the prosthesis hybrid. On a titanium tube made by 3D printing by our partners, the Konmet company, we have built up a layer of solid ultra-high molecular weight polyethylene, and the inner part was made of porous ultra-high molecular weight polyethylene identical to the structure of spongy bone. During the operation, part of the coating was cut off to "fit" the implant to the bone. A few days after the operation, the dog was able to walk fully. If the fusion of the polymer with the bone tissue is successful, after some time it will be possible to remove the fixing plates," says Fedor Senatov.
Fig. 3. Implants with a titanium reinforcing component, a "spongy" polymer core and a "cortical" polymer shell.
"My colleagues and I have successfully performed prosthetics surgery. The implant is strong, its size corresponds to the weight of the dog and the size of the bone. Long-term results are more important here, so that the implant gets used, grows into the bone. Then there will be a lot of progress, but it takes time. While we are watching the dog, she is currently undergoing chemotherapy," says the chief physician of MedVet, Ph.D. Ilya Vilkovisky.
According to the developers, it took 2 weeks to prepare, during this time they did:
– development of the implant design based on an X-ray image,
– 3D modeling,
– conducting computer simulations,
– development of engineering solutions to change the technology of creating a hybrid implant,
– obtaining test samples,
– conducting mechanical tests,
– manufacture of the final implant.
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