Injectable bioactive calcium-magnesium phosphate cement for bone regeneration

Current research on bone graft materials focuses on injectable, biodegradable cements that can be delivered through minimally invasive techniques. Traditional calcium phosphate cements (CPCs) are known for their osteoconductivity but often lack rapid setting properties and sufficient mechanical strength. While injectable CPCs have been explored, they typically require extended setting times and may degrade too slowly for clinical applications. No prior work had resolved the challenge of achieving rapid setting while maintaining high compressive strength and accelerated degradation rates. This gap motivated the development of a new cement formulation that combines the benefits of calcium and magnesium phosphate systems. Prior research has shown that magnesium phosphate cement (MPC) can enhance setting speed and degradation rates. However, integrating these properties into a single injectable system remained unaddressed. The absence of a material that balances rapid setting, high initial strength, and accelerated degradation limited the potential for minimally invasive bone repair techniques. These limitations highlight the need for a novel composite cement with optimized mechanical and degradation properties.

The aim of this study was to develop a novel injectable calcium-magnesium phosphate cement (CMPC) that combines the advantages of calcium phosphate cement (CPC) and magnesium phosphate cement (MPC). The specific problem addressed was the lack of a cement that sets rapidly, achieves high initial mechanical strength, and degrades at a clinically relevant rate. The motivation stemmed from the demand for minimally invasive bone repair techniques that require injectable materials with optimal setting and degradation properties. The study sought to determine whether introducing MPC into CPC could improve workability, setting time, and degradation rate while maintaining injectability. The researchers proposed that the integration of magnesium phosphate into calcium phosphate systems could address the limitations of traditional CPCs. The study focused on optimizing the P/L ratio to achieve the desired properties. The goal was to create a material suitable for clinical applications where rapid setting and controlled degradation are essential. This work aimed to advance the development of injectable bone cements for minimally invasive procedures.

The researchers prepared calcium-magnesium phosphate cement (CMPC) by combining calcium phosphate cement (CPC) with magnesium phosphate cement (MPC). The cement was formulated under various P/L ratios to identify the optimal composition. The injectability of the cement was evaluated using a syringe-based method to assess its flowability and workability. Setting time was measured at 37°C under 100% relative humidity to simulate physiological conditions. Compressive strength was tested after 48 hours of setting to evaluate mechanical performance. In vitro degradation experiments were conducted in simulated body fluid (SBF) solution to assess the degradation rate of the cement. The degradation rate was compared with that of pure CPC to determine the effect of magnesium phosphate on degradability. The study used standardized testing procedures to ensure reproducibility and reliability of results. The combination of injectability, setting time, and degradation rate measurements provided a comprehensive assessment of the cement’s suitability for bone regeneration applications.

The calcium-magnesium phosphate cement (CMPC) prepared at the optimal P/L ratio demonstrated excellent injectability and workability. The cement set within 10 minutes at 37°C under 100% relative humidity, meeting the criteria for rapid-setting materials. After 48 hours, the compressive strength of the cement reached 47 MPa, indicating strong initial mechanical performance. In vitro degradation experiments showed that the CMPC degraded significantly faster than pure calcium phosphate cement (CPC) in simulated body fluid (SBF) solution. The degradation rate of CMPC was approximately 1.5 times higher than that of pure CPC, suggesting improved biodegradability. The mechanical strength of 47 MPa after 48 hours is comparable to that of other injectable bone cements used in clinical settings. The rapid setting time of 10 minutes supports its potential for minimally invasive applications. These findings suggest that the CMPC has favorable properties for bone regeneration and clinical use.

The study concluded that the novel injectable calcium-magnesium phosphate cement (CMPC) offers a promising solution for bone regeneration applications. The cement exhibited rapid setting, high initial compressive strength, and accelerated degradation rates compared to pure calcium phosphate cement (CPC). The authors propose that the integration of magnesium phosphate into calcium phosphate systems enhances the material’s performance for clinical use. The rapid setting time of 10 minutes at 37°C supports its suitability for minimally invasive procedures. The compressive strength of 47 MPa after 48 hours is sufficient for initial mechanical support in bone repair. The faster degradation rate in simulated body fluid (SBF) indicates improved biocompatibility and resorption properties. The combination of injectability, mechanical strength, and degradation rate positions CMPC as a viable material for bone regeneration. These findings suggest that CMPC is highly promising for a wide range of clinical applications, especially in minimally invasive techniques.