Wood biocomposite for manufacturing osteosynthesis implants

Title in Latvian "Koksnes biokompozīta izmantošanas iespējas osteosintēzes implantu izgatavošanai"
Description:
Bone fractures affect millions of people worldwide every year. Although some fractures can heal without surgical intervention, many require operative treatment and fracture fixation—osteosynthesis using implants such as screws, plates, rods, and other devices—to restore function and allow patients to return to their normal activities.
Currently, osteosynthesis implants are most commonly manufactured from metals such as stainless steel and titanium. Although these materials have traditionally been considered biologically inert, growing evidence suggests that they may undergo biocorrosion during long-term implantation. In addition, the density and stiffness of these metals are substantially greater than those of human bone. This mechanical mismatch, together with biocorrosion and other contributing factors, may lead to complications such as aseptic loosening. Such complications may require additional surgical procedures and may also increase the risk of recurrent fractures.
Metallic implants can also produce imaging artefacts, particularly in computed tomography (CT) and magnetic resonance imaging (MRI), which may complicate diagnostic interpretation. These limitations highlight the need for the development of new materials for bone implants.
Wood has been investigated as one of a potential biomaterial. Bone and wood share certain similarities in their morphological organisation and functional characteristics, including mechanical load transfer, structural support, and fluid transport. Wood has been studied as a potential material for bone defect reconstruction and osteosynthesis implants since the 1970s, including research conducted in Latvia.
In vivo studies have been performed using several wood species, including birch, ash, juniper, and bamboo, with most demonstrating good biocompatibility. Natural wood has also been reported to exhibit osteoconductive properties, which have been associated with its porous structure. Nevertheless, despite decades of research, a wood-based implant suitable for routine clinical use has not yet been developed. One of the principal limitations is the insufficient mechanical strength of natural wood, as adequate mechanical stability is essential for load-bearing bone implants.
The mechanical properties of wood can be substantially improved through densification. During this process, hemicelluloses and part of the lignin are removed from the wood, leaving a cellulose-rich structure. The remaining lignin is modified during processing and subsequently acts as a natural binding agent during compression. The material is then compressed under elevated temperature and pressure, producing a mechanically reinforced wood-based biocomposite.
The resulting material can be machined in a manner comparable to metals, allowing the fabrication of osteosynthesis implants with complex geometries. This approach therefore offers the potential to combine the biological and structural advantages of wood with the mechanical performance required for orthopaedic implant applications.