A novel injectable bioactive bone cement for spinal surgery: a developmental and preclinical study

Current spinal surgery techniques rely on bone cement for vertebral stabilization and fracture treatment. Traditional cements face limitations in biocompatibility and mechanical performance. Prior research has shown that hydroxyapatite-based materials can support bone integration. However, no prior work had resolved the need for injectable cements with both radiopacity and biomechanical similarity to natural bone. This gap motivated the development of a novel formulation combining strontium-containing hydroxyapatite with a methacrylate resin matrix. The study aimed to address these limitations by integrating radiopacity and structural stability into a single injectable material. The need for a cement that mimics natural bone stiffness and avoids cytotoxic effects remained unmet in clinical applications. This paper contributes a new approach by testing a cement composition that may offer improved spinal stabilization outcomes.

The purpose of this study was to develop and test a new injectable bone cement for spinal surgery applications. The goal was to create a material that could be delivered minimally invasively while maintaining structural integrity and biocompatibility. The study sought to evaluate the mechanical and biological properties of a strontium-containing hydroxyapatite cement (SrHAC). The researchers aimed to determine if SrHAC could match the stiffness of natural bone after injection. They also wanted to confirm that the cement would not cause cytotoxic or hemolytic effects in vitro. The study focused on optimizing the cement's setting time and radiopacity for clinical use. By combining a methacrylate resin with strontium hydroxyapatite filler, the team aimed to improve both mechanical and radiographic properties. The ultimate goal was to provide a safer and more effective alternative to existing spinal cement options.

The study involved synthesizing strontium-containing hydroxyapatite (Sr-HA) filler through precipitation and calcination. The Sr-HA was analyzed using Fourier transform infrared (FTIR) and X-ray diffraction (XRD) to confirm its structure. The cement was then formulated by combining the Sr-HA with Bisphenol A Diglycidylether Dimethacrylate (D-GMA) resin. Setting time and peak temperature of the cement were measured to evaluate handling properties. In vitro biocompatibility tests included cell relative growth rate (RGR), MTT assays, and haemolysis tests. Biomechanical testing was performed on pig spines to assess stiffness and fatigue resistance after cement injection. Radiopacity was evaluated using radiographic imaging techniques. The study combined material synthesis, mechanical testing, and biological evaluation to assess the cement's suitability for spinal surgery.

The setting time of the SrHAC cement was 15 minutes, and the peak temperature during setting was 55 degrees Celsius. The cement exhibited class 1 cytotoxicity, indicating no harmful effects on cells in vitro. Haemolysis was measured at 1%, suggesting no significant red blood cell damage. Stiffness after cement injection reached 112% of intact bone stiffness, and fatigue loading showed 95% of natural bone properties. These results suggest that the cement closely mimics the mechanical behavior of natural bone. Radiopacity of SrHAC allowed clear visualization under radiographic imaging. The combination of strontium-containing hydroxyapatite and methacrylate resin provided both structural and imaging advantages. The cement’s performance in pig spines supports its potential use in spinal stabilization procedures.

The SrHAC cement demonstrated favorable setting characteristics and biocompatibility in vitro. The cement’s mechanical properties matched those of natural bone, making it a promising candidate for spinal stabilization. Radiopacity enabled clear imaging, which is essential for surgical accuracy. The absence of cytotoxic or hemolytic effects supports its safety profile for clinical use. The study’s findings suggest that SrHAC could be a viable alternative to existing spinal cements. The combination of strontium hydroxyapatite and methacrylate resin provided both structural and imaging benefits. The cement’s performance in pig spines supports its potential for use in minimally invasive spinal procedures. These results align with the authors’ stated goal of developing a safer and more effective injectable bone cement.