A novel in vivo method for quantifying the interfacial biochemical bond strength of bone implants

Abstract

Quantifying the in vivo interfacial biochemical bond strength of bone implants is a biological challenge. We have developed a new and novel in vivo method to identify an interfacial biochemical bond in bone implants and to measure its bonding strength. This method, named biochemical bond measurement (BBM), involves a combination of the implant devices to measure true interfacial bond strength and surface property controls, and thus enables the contributions of mechanical interlocking and biochemical bonding to be distinguished from the measured strength values. We applied the BBM method to a rabbit model, and observed great differences in bone integration between the oxygen (control group) and magnesium (test group) plasma immersion ion-implanted titanium implants (0.046 versus 0.086 MPa, nZ10, pZ0.005). The biochemical bond in the test implants resulted in superior interfacial behaviour of the implants to bone: (i) close contact to approximately 2 mm thin amorphous interfacial tissue, (ii) pronounced mineralization of the interfacial tissue, (iii) rapid bone healing in contact, and (iv) strong integration to bone. The BBM method can be applied to in vivo experimental models not only to validate the presence of a biochemical bond at the bone-implant interface but also to measure the relative quantity of biochemical bond strength. The present study may provide new avenues for better understanding the role of a biochemical bond involved in the integration of bone implants.

Metal plasma immersion ion implantation and deposition (MePIIID) on screw-shaped titanium implant: The effects of ion source, ion dose and acceleration voltage on surface chemistry and morphology

“…The change of surface topography after plasma immersion ion implantation and deposition process varied from study to study depending on their process parameters and substrate materials [25,[32][33][34].…”

“…Furthermore, MePIIID allows surface chemistry modification with negligible alteration of surface topography at the nanometer level thus enabling the investigation of the effect of bioactive implant surface chemistry on the bone response [25]. Our recent study in an animal model demonstrated stronger bone integration of the magnesium PIIIDprocessed titanium implants despite their low roughness values compared to the oxygen PIIID-processed titanium implants [25]. Note: Cathodic metal arc plasma was filtered using curved magnetic field and guided to the samples.…”

“…The results of animal studies using the implant groups fabricated by the present MePIIID process parameters have been published elsewhere [25].…”

“…MePIIID is a cyclic process of repeating cathodic arc deposition and plasma immersion ion implantation [21,22], which leads to excellent mechanical properties with the benefit of preventing biodelamination and biodegradation of implant surfaces in bone [23,24]. Furthermore, MePIIID allows surface chemistry modification with negligible alteration of surface topography at the nanometer level thus enabling the investigation of the effect of bioactive implant surface chemistry on the bone response [25]. Our recent study in an animal model demonstrated stronger bone integration of the magnesium PIIIDprocessed titanium implants despite their low roughness values compared to the oxygen PIIID-processed titanium implants [25].…”

An Improved Mechanical Testing Method to Assess Bone-implant Anchorage

“…In general, distance osteogenesis is associated with smooth, or machined, endosseous implant surfaces and is often seen in cortical bone healing, while microtopographically complex surfaces are associated with contact osteogenesis that is more typical of trabecular bone healing. Tensile test models using smooth implant surfaces and cortical bone healing have been able to test the adhesive properties of this amorphous biological matrix absent of the contact osteogenesis associated with topographically complex surfaces, and have shown that the so called "biochemical" bonding that occurs provides a minor component of the "tensile strength" values reported with topographically complex surfaces 21 . On the contrary, using a trabecular bone healing model, Wong et al 22 showed "an excellent correlation" between implant surface roughness and push-out failure load, and indicated that chemical bonding indeed played a negligible role in anchorage of bone to the implant surface.…”