High performance resorbable composites for load-bearing bone fixation devices

Abstract

Bone fractures are some of the most common injuries annually, and many require a fixation device to help properly heal. The present study focuses on developing a bioresorbable composite that has high strength and stiffness for bone fixation applications. To achieve this, a design of experiments was performed, testing the effect of long fiber reinforcement type, matrix type, matrix amount, and particle reinforcement amount on the flexural properties of the composite. Based on these results, the ideal resorbable long fiber reinforcement, particle reinforcement, and matrix material are degummed silk fibroin, hydroxyapatite, and polylactic acid, respectively. Through further optimizations of the particle reinforcement phase a flexural modulus and strength of 13.7 GPa and 437 MPa, respectively, was achieved. Both values are among the highest found in literature, with the strength far exceeding the requirement for a fixation device and the highest for such a bioresorbable composite material, showing great promise for use as a bioresorbable fixation device.

Assessment of the Mechanical and Thermal Properties of Injection-Molded Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/Hydroxyapatite Nanoparticles Parts for Use in Bone Tissue Engineering

“…Lower values have been reported for titanium (Ti) and its light alloys, such as Ti-6Al-4V ELI, which are also widely used for making implant devices, having a value of around 110 GPa [ 57 ]. As shown above, in comparison to metal alloys, the elasticity of the P(3HB- co -3HHx)/nHA composites prepared in this study is nearer to that of the natural bone, which is in the 8–25 GPa range [ 5 ]. Thus, from a mechanical point of view, their use in bone scaffolds and resorbable plates or screws looks promising.…”

“…However, they prevent the bone from being subjected to the required mechanical loadings [ 4 ]. Indeed, while natural bone has a modulus ranging between 8 to 25 GPa, metals have a modulus of 110–210 GPa, which results in the load being imparted onto the device rather than the bone which then causes a localized decrease in bone mineral density [ 5 ]. Meanwhile, metal ion leaching increases inflammation and irritation around the implant [ 6 ].…”

Silk Polymers and Nanoparticles: A Powerful Combination for the Design of Versatile Biomaterials

“…In addition to scaffold-based applications for bone regeneration, silk/HAP/polylactic acid composites were developed for the fabrication of high strength bioresorbable fixation devices for clinical applications in orthopedics (Heimbach et al, 2018 ). Bioactive glass NPs have been also used in bone tissue engineering using silk-based materials.…”

Polylactide Composite Pins Reinforced with Bioresorbable Continuous Glass Fibers Demonstrating Bone-like Apatite Formation and Spiral Delamination Degradation

“…Previous studies [2,3,4,5,6,7,8,9,10,11,12] introduced biomimetic composites for orthopedic applications which used biodegradable polymers blended with β-tricalcium phosphate (TCP), hydroxyapatite (HA), or bioactive glass. Although the addition of these bioceramics improved the biological properties of the composites, including osteoconductivity [4,13] and/or osteoinductivity [10,14], the relatively low overall mechanical strength and modulus still resulted in unsatisfactory healing, particularly when used for load-bearing orthopedic applications [15].…”

“…Poly- D, L -lactide (PDLLA) materials with high mechanical performance have been reported to degrade after approximately 1–1.5 years, in comparison with the much longer degradation rate of 5–6 years for conventional poly- L -lactide (PLLA) [21]. The degradation behavior and bioactivity of implants may also be affected by other factors [1,5,15,22] such as the use of long fiber reinforcement [1,22] and the degradation environment [5]. However, little information is available on the mode of degradation and the bioactivity of such novel biocomposites.…”