No abstract

To prevent a premature failure, absorbable magnesium implants must possess an adequate mechanical stability. Among many ways to improve the mechanical properties of magnesium is by particle reinforcement, such as using carbon nanofiber (CNF). This work reports an experimental design for optimum materials and processing of CNF-reinforced Mg–Zn composites based on a two-level factorial design. Four factors were analyzed: percentage of CNF, compaction pressure, sintering temperature, and sintering time, for three recorded responses: elastic modulus, hardness, and weight loss. Based on the two-level factorial design, mechanical properties and degradation resistance of the composites reach its optimum at a composition of 2 wt % CNF, 400 MPa of compaction pressure, and 500 °C of sintering temperature. The analysis of variance reveals a significant effect of all variables (p < 0.0500) except for the sintering time (p > 0.0500). The elastic modulus and hardness reach their highest values at 4685 MPa and 60 Hv, respectively. The minimum and maximum weight loss after three days of immersion in PBS are recorded at 54% and 100%, respectively. This work concludes the percentage of CNF, compaction pressure, and sintering temperature as the main factors affecting the optimum elastic modulus, hardness, and degradation resistance of CNF-reinforced Mg–Zn composites.

Nowadays, magnesium (Mg) based alloys have gained much interest due to its potential use as biodegradable implants for the application of fixation, screws and plates in orthopaedics field. The main problems of biodegradable implants made from pure Mg are its low strength and easily corrodible. Therefore, the purpose of this study was to analyse the sintering temperature of magnesium-zinc (Mg-Zn) alloys reinforced with carbon nanofibres (CNF) through mechanical and morphological structures. Pure Mg, Zn, and CNF was prepared via powder metallurgy (PM) method. The samples were mechanically alloyed using planetary ball mill to create finer powder. Next, the samples were compacted using the Instron machine for 10 minutes at room temperature to produce a 10 mm diameter cylindrical platelet. Then, the specimens were heated with an argon gas flow for 4 hours at different sintering temperatures. The results showed that the optimum sintering temperature for Mg-Zn alloys reinforced with CNF was at 250℃ with elastic modulus and yield strength of 2729.886 MPa and 140.628 MPa, respectively. The findings of this study concluded that Mg-Zn alloys reinforced with CNF composites have great potential to be used as new biodegradable implants for medical applications in the future.

The effectiveness of malleolar fracture fixation is still questionable. Internal fixator is the one of the treatment for treating this fracture. However, the analysis of various type of internal fixator is still lacking in the literature in terms of biomechanical characteristics and behaviour. Thus, the aim of the study was to compare the stability of locking compression plate (LCP) and one third tubular plate (OTT) in different configuration of screws. Computed Tomography (CT) images of bone was used to develop 3D model of fibula bone. The plate was constructed in Solidworks software and number of screws used were 3 and 5. Further, finite element study was conducted for both model. For LCP, the highest von Mises stress (VMS) observed at the plate for 3 screws was 484 MPa, whereas for 5 screws plate was 667 MPa. Besides, for OTT, the highest VMS at plate observed for 3 screws was 300.5 MPa, whereas for 5 screws plate was 127.5 MPa. Based on the results, it can be noted that the usage of 3 screws can causes a low VMS at plate compare to 5 screws. However, the relation is valid for LCP. For OTT, 5 screws constructs gave a low VMS than 3 screws constructs.