Superior Hydroxyapatite Coatings for Medical Implants
Himed’s MATRIX HA® uses raw hydroxyapatite (HA, or HAp) powder of exceptionally high purity to coat titanium dental implants and medical devices. Our MC Type HA is manufactured on site and consistently exceeds the compositional requirements for surgical implants established by ASTM F1185.
Medical implant manufacturers worldwide turn to Himed for customizable, but consistent, applications of bioactive hydroxyapatite to support improved osseointegration and encourage new bone growth around surgical implants. Decades of clinical studies suggest that hydroxyapatite, which is a form of inorganic calcium phosphate naturally present in human bone, is osteo-conductive and therefore has the potential to improve patient outcomes through a reduction in healing times and improved biocompatibility of implants.
Our MATRIX HA® Coating Process
The first step in achieving a quality hydroxyapatite coating is to blast the titanium implant substrate with Himed’s proprietary MCD apatitic abrasive; a biocompatible resorbable blast media that leaves a virtually residue-free surface after passivation. This initial step allows for incredible control of the implant surface texture while avoiding the contaminants common in conventional grit blasting methodologies.
The application of hydroxyapatite is then completed using our atmospheric plasma spray system (APS) which is held by our ABB robot capable of six axes of robotic motion. The robotics precisely control the spray pattern to guarantee consistent and reproducible coatings. The devices are placed on a multi-spindle turntable that rotates independently at a controlled speed during spraying. This wide range of motion results in uniform coatings on all types of complex surfaces.
The output of the MATRIX HA® coating can be precisely controlled and is customizable. We work closely with device manufacturers to identify the optimal coating thickness and desired treatment zones for the operational and aesthetic objectives desired.
Dental & Orthopedic Implant Applications
MATRIX HA® is a suitable coating for a wide variety of dental, orthopedic, and spinal implants composed of titanium, including:
Dental Implant Screws
Orthopedic Screws (Cortical/Cancellous/Cannulated,etc.)
Pedicle Screws
Sacroiliac SI Joint Screws
Lumbar Plates and Screws (Spinal Spacers)
Femoral Stems
Acetabular Cups
Hydroxyapatite Coating Characteristics
Appearance and Surface Morphology
The coating must be uniform and white in color. No visible surface defects are permitted when viewed under 10X magnification, even on highly convex surfaces such as screw threads.
Treatment Zone
Incredible control over the spray area is possible through precision customized masking, resulting in a sharp and distinct spray line bounding any regions specified to be free from coating.
HA Coating Thickness
The MATRIX HA® process is customizable to produce a variety of coating thickness ranges, from thin (5-15 μm), to nominal (20-40 μm), to thick (35-70 μm).
Phase Composition and Crystallinity
Via quantitative x-ray diffraction characterization, our materials engineers have validated the process to achieve a minimum hydroxyapatite coating composition of 90%. The coating crystallinity must exceed 62% per FDA guidance.
Mechanical Strength
It is generally known that the mechanical properties of thermal spray coatings decline with increased thickness due to residual tensile stresses that increase with thickness. Himed performs all mechanical tests of MATRIX HA® at (or near) the maximum coating thickness to demonstrate passing results when residual stresses are most prevalent. This “worst-case” scenario demonstrates that there is a substantial safety margin regarding these physical properties when applied to the subject device.
Conforming Standards
All MATRIX HA® orders receive a signed Certificate of Quality which includes confirmation of results against Himed’s own rigorous internal standards, FDA guidance, ISO 13779-2, and the following ASTM standards:
Phase Composition: ASTM F2024
Tensile Strength: ASTM F1147
Shear Strength: ASTM F1044
Grit Blast Passivation: ASTM F86
HAp Powder Chemistry: ASTM F1185
SEM image showing coating morphology & density
Consistent HAp coating thickness with no delamination