Hydroxyapatite

Material Properties of Hydroxyapatite

Hydroxyapatite’s value as a biomaterial lies in its unique combination of biological affinity and tunable properties. As a synthetic analog of natural bone mineral, hydroxyapatite is highly biocompatible, osteoconductive, and chemically stable—making it ideal for applications where predictable integration with hard tissue is required. Himed produces hydroxyapatite under tightly controlled conditions to ensure reproducibility and enable tailored performance across orthopedic, dental, and laboratory use cases.

• BIOCOMPATIBILITY: Non-inflammatory, non-immunogenic
  
  

• OSTEOCONDUCTIVITY: Promotes bone ingrowth and osteoblast adhesion
  
  

• SURFACE REACTIVITY: Supports matrix protein binding and early mineralization
  
  

• POROSITY: Adjustable to support vascularization and cellular infiltration
  
  

• SOLUBILITY: Low, but tunable for controlled resorption over time

Although hydroxyapatite closely mimics the chemical composition of natural bone, its mechanical behavior—particularly in its pure, sintered form—is more similar to cancellous (trabecular) bone than to dense cortical bone. While optimized HA composites can reach compressive strengths that approach the lower end of cortical bone performance, its inherent brittleness, low fracture toughness, and relatively modest elastic modulus prevent it from serving as a structurally sufficient material for most load-bearing applications on its own.

To overcome these limitations, HA is commonly integrated into composite or hybrid systems where it contributes bioactivity, while other materials provide the necessary mechanical strength. For example, various forms of HA can be combined with a high-performance polymer such as polyetheretherketone (PEEK) in a spinal fusion device. In such instances, HA plays a biologically active role—stimulating osteoblast activity, supporting matrix formation, and promoting device integration—while the structural substrate manages applied loads and mechanical stress.

Additionally, incorporating HA can increase an implant’s surface area and surface roughness, which are known to improve cellular adhesion, proliferation, and differentiation. This makes it a valuable component in engineered biomaterial systems that aim to balance biological interaction with mechanical reliability.

Diagram of hydroxyapatite whiskers, a unique rod-like form of HA, incorporated into porous PEEK (A), and dense solid PEEK (B), to improve biocompatiblity.

Customization Strategies for Hydroxyapatite

To meet specific clinical and engineering requirements, Himed offers a wide range of HA customizations, including:

Particle Size, Distribution, and Morphology

From nanopowder to coarse granules, available in spherical or irregular form, with narrow particle size distributions suited for grafts, injectables, or pastes.

POROSITY and Surface Area

Adjustable to optimize bioactivity, dissolution rate, and implant fixation.

MULTI PHASE COMPOUNDS

Integration with β-tricalcium phosphate (β-TCP), or other calcium phosphates phases, to create biphasic compounds that allow control over degradation rate, mechanical behavior, and biological signaling.

Unique Forms

Powders, granules, cast shapes, laboratory substrates (discs/coated slides), and 3D-printable formulations tailored for clinical, manufacturing, or analytical workflows.

Ion Substitution (Doping)

Trace elements such as magnesium (Mg), strontium (Sr), zinc (Zn), and silicon (Si) can be introduced to enhance osteogenesis, angiogenesis, or antimicrobial performance.

Through these engineered modifications, Himed’s synthetic hydroxyapatite can be precisely tuned to support a wide range of performance targets—from fast-resorbing scaffold fillers to structurally stable substrates for pre-clinical testing. Whether incorporated into composite systems or applied as a material platform for new device development, our HA delivers the predictability and flexibility required by today's advanced medical products.