1-Year pullout strength and degradation of ultrasound welded vs tapped craniomaxillofacial fixation screws

López, Alejandro; Ayyachi, Thayanithi; Brouwers, Tessa; Åberg, Jonas; Finne‐Wistrand, Anna; Engqvist, Håkan

doi:10.1016/j.polymertesting.2022.107519

Cited by 1 publication

(1 citation statement)

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“…They revealed that composition, screw size, and crystallinity of the polymer matrix are important parameters in the initial pull-out strength and also in long-term strength related to the degradation process. [ 33 ] Many studies try to design and fabricate degradable composite screws from hydroxyapatite/PLLA, self-reinforced-PLLA, etc., however, the lack of initial mechanical properties and its reduction in hydrolytic degradation environment is still a challenge, especially for load-bearing applications such as tendon and ligaments as well as long bone fracture fixations. [ 34 , 35 ] In the present study, the use of fiber reinforcement, an increase in the VF of reinforcement, layers with proper arrays, and optimization of thickness percentage assigned to each layer had an important role in achieving suitable mechanical properties.…”

Section: Discussionmentioning

confidence: 99%

Optimization of the Manufacturing Process and Mechanical Evaluation of a Functionally Graded Biodegradable Composite Screw for Orthopedic Applications

Zargar Kharazi,

Hosseini,

Shafaat

et al. 2023

Journal of Medical Signals &Amp; Sensors

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Background: Metal screws are commonly used for fracture fixations. However, the high modulus of elasticity relative to bones and releasing metallic ions by the metal screw needed a second surgery to remove the implant after the healing period. Furthermore, the removal of metal screws following the healing of the bone is a serious problem that can lead to refracture due to the presence of holes in the screw. Bioresorbable screws can overcome most of the problems associated with metallic screws which motivated research on manufacturing nonmetallic screws. Methods: In this study, three-layer poly L-lactic acid/bioactive glass composite screws were manufactured according to functionally graded material theory, by the forging process. All of the physical and chemical parameters in the manufacturing stages from making composite layers to the forging process were optimized to obtain suitable mechanical properties and durability off the screw in load-bearing positions. Results: The tri-layer composite screw with unidirectional, ±20° angled, and random fibers orientation from core to shell shows a flexural load of 661.5 ± 20.3 (N) with a decrease about 31% after 4-week degradation. Furthermore, its pull-out force was 1.8 ± 0.1 (N) which is considerably more than the degradable polymeric screws. Moreover, the integrity of the composite screws was maintained during the degradation process. Conclusions: By optimizing the manufacturing process and composition of the composite and crystallinity, mechanical properties (flexural, torsion, and pull-out) were improved and making it a perfect candidate for load-bearing applications in orthopedic implants. Improving the fiber/matrix interface through the use of a coupling agent was also considered to preserve the initial mechanical properties. The manufactured screw is sufficiently robust enough to replace metals for orthopedic load-bearing applications.

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Section: Discussionmentioning

confidence: 99%