Characterization of polymeric solutions as injectable vehicles for hydroxyapatite microspheres

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Orthopedic Surgery

Background:

• Injectable polymeric solutions are crucial for filling bone defects and enabling tissue regeneration.
• Biocompatibility and suitable rheological properties are essential for effective delivery of reinforcement phases like hydroxyapatite microspheres.
• Orthopedic injectable devices require optimized polymeric vehicles for minimally invasive surgeries.

Purpose of the Study:

• To optimize a biocompatible polymeric solution capable of transporting hydroxyapatite microspheres into bone defects.
• To evaluate Na-alginate (ALG) as a potential vehicle for orthopedic injectable applications.
• To assess the rheological properties and physical stability of Na-alginate (ALG) solutions post-sterilization.

Main Methods:

• Selected biocompatible polymers: sodium carboxymethylcellulose, hydroxypropylmethylcellulose, and Na-alginate (ALG).
• Assessed rheological properties of polymer solutions via viscosimetry before and after moist heat sterilization.
• Tested injectability using an orthopedic device and evaluated preliminary injection of hydroxyapatite microspheres.

Main Results:

• Na-alginate (ALG) solutions exhibited the most suitable properties for carrying hydroxyapatite microspheres.
• A non-sterile ALG 6% solution was successfully used for preliminary injection tests.
• Sterile ALG 7.25% solution closely matched non-sterile ALG 6% properties and demonstrated minor rheological changes upon storage.

Conclusions:

• Na-alginate (ALG) is a promising biocompatible polymer for developing injectable bone defect filling materials.
• Optimized ALG solutions can effectively carry hydroxyapatite microspheres for orthopedic applications.
• The selected sterile ALG 7.25% formulation shows good physical stability for potential clinical use.