Dr. Antonio Silvestre, researcher in the INCLIVA Group of histopathology and tissue engineering, at the University of Valencia and head of Service of Orthopedic Surgery and Traumatology at the University Clinical Hospital has collaborated with researchers from the Polytechnic University of Valencia to design of a new intramedullary implant that, by combining different parts, is suitable for use as an intramedullary component for hips, knee, elbow, or shoulder prostheses. It can also be used as an intramedullary ‘nail’ implant for the reconstruction of fractures or in stumps for external prostheses (after amputations).
The implant, patented by INCLIVA, the University of Valencia, and the Polytechnic University of Valencia, stands out because of its novel design which comprises several expandable modules made of polymers that are loosely inserted into the bone, facilitating both their implementation and extraction. In addition, thanks to its geometry, it can be customized or adapted to the needs of each patient.
Most current implants are composed of one single piece that is inserted into the medullary canal by percussion (press-fit or snap-fit), i.e., a hammer blow; this is a traumatic process that sometimes causes the bone to break open. In addition, the rigidity of these implants causes the loss of bone tissue (osteoporosis due to disuse) and when an osseointegrated implant must be removed, surgeons have to resort to controlled fracture (enlarged osteotomy) in more than 50% of cases.
“The system we have devised reduces the main drawbacks of current implants: it is inserted loosely into the bone, it expands and is fixed by friction, allowing the tensions in the bone to be controlled, which is especially important when the bone is low quality. The implant subsequently becomes osseointegrated into the bone and remains fixed there in the long term. In addition, being made of polymers facilitates the implant’s removal, reducing the risk of bone fracture”, highlighted José Albelda, from the Center for Research in Mechanical Engineering (CIMM) at the Polytechnic University of Valencia.
Regarding its implementation, the researchers stressed that it can improve safety and facilitate surgical intervention: “with this technique, these processes are less traumatic and provide surgeons with greater control over the operation, which we hope will positively influence patient recovery”, added the surgeon, Antonio Silvestre.
Another of the fundamental aspects of this implant is its rigidity, which is like that of cortical bone. Thus, “the implanted bone distributions and tension levels are similar to those of bones without an implant, which is expected to improve the process of bone remodeling”, explained José Expósito, a PhD student in Health Technologies and Wellness.
When the implant designed by these Valencian researchers is used as a ‘nail’ for fractures, its main advantage is that it avoids the difficulty of machining holes in the bone for the use of transversal fixation screws. It also improves the stability of the fracture zone by compressing the different fragments together.
Finally, when it is used in femur or humerus amputations, it can be combined with a percutaneous collar, also designed by INCLIVA researchers at the University of Valencia and the Polytechnic University of Valencia, aimed at improving the anchorage of adjacent tissues and which favors the creation of a protective barrier against infections.