Biological and biomechanical benefits of hydroxyapatite coatings

Synthetic hydroxyapatite has been used for approximately fifty years and its use has been different throughout this time. Its first application was related to dental implants and today it has become the coating that favors bone growth par excellence.

Initially, and given its nature as a biocompatible material with the human body, it developed a function of filling congenital bone defects and cavities caused by trauma. Subsequently, hydroxyapatite began to be applied as a coating and, above all, with a clear osteoconductive function.

In general terms, and after the conclusion and analysis of some studies, osteoconductivity and osteoinductivity are the main functions to be highlighted by hydroxyapatite.

Osteoconductivity is its ability to support the growth of bone cells, tissues and blood capillaries in the space caused by the operation between the implant body and the existing bone surface. The coating pores will be the ones that favor the osseointegration process.

Osseoinductivity refers to the ability to transform undifferentiated precursor stem cells into osteoprogenitor cells. Here the hydroxyapatite absorbs the adhesion molecules and facilitates the formation of favorable adhesion centers.

The number of people receiving reconstructive implants for both the hip and the knee is growing. We are in the 10 million a year of metallic, polymeric and ceramic implants throughout the world.

Global figures for hip, knee orthopedic surgical joint replacement products are projected to be $33 million in 2022, and orthopedic surgeries continue to increase by 10-12% each year.

Thus, the repair or replacement of missing or diseased bones is growing, as are spinal or small joint implants, and hydroxyapatite coating is the material par excellence used in biomedical implantology.

Therefore, we conclude that the hydroxyapatite coating offers obvious biological and biomechanical benefits and is a reliable means of achieving long-lasting osseointegration.

However, for the survival of the implant, the following requirements must also met:

• An adequate selection of the implant design
• Adequate solid support surfaces
• That the patient has adequate bone density and life expectancy

Although it is true that implantology is moving towards molecular and biological repair and regeneration of damaged or lost tissue. Great developments are coming in this field in the long term and where hydroxyapatite will also have its leading role.