Bone Regeneration in Critical-Sized Bone Defects Treated with Additively Manufactured Porous Metallic Biomaterials: The Effects of Inelastic Mechanical Properties

Abstract

Additively manufactured (AM) porous metallic biomaterials, in general, and AM porous titanium, in particular, have recently emerged as promising candidates for bone substitution. The porous design of such materials allows for mimicking the elastic mechanical properties of native bone tissue and showed to be effective in improving bone regeneration. It is, however, not clear what role the other mechanical properties of the bulk material such as ductility play in the performance of such biomaterials. In this study, we compared the bone tissue regeneration performance of AM porous biomaterials made from the commonly used titanium alloy Ti6Al4V-ELI with that of commercially pure titanium (CP-Ti). CP-Ti was selected because of its high ductility as compared to Ti6Al4V-ELI. Critical-sized (6 mm diameter) femoral defects in rats were treated with implants made from both Ti6Al4V-ELI and CP-Ti. Bone regeneration was assessed up to 11 weeks using micro-CT scanning. The regenerated bone volume was assessed ex vivo followed by histology and biomechanical testing to assess osseointegration of the implants. The bony defects treated with AM CP-Ti implants generally showed higher volumes of regenerated bone as compared to those treated with AM Ti6Al4V-ELI. The torsional strength of the two titanium groups were similar however, and both considerably lower than those measured for intact bony tissue. These findings show the importance of material type and ductility of the bulk material in the ability for bone tissue regeneration of AM porous biomaterials.

A systematic review of preclinical in vivo testing of 3D printed porous Ti6Al4V for orthopedic applications, part I: Animal models and bone ingrowth outcome measures

“…Long bone segmental defects were also common in the literature, though we found that the methods for additional implant fixation, a significant factor in bone response, 33,91 varied between these models. The fixation plates were made from PEEK, 68‐71,75 titanium alloy, 42 or stainless steel, 4 but the selection criteria for each material was not clear. Though it is understood that segmental implant fixation is meant to reflect clinical practice, 33 explanations regarding the selection of method and material may be helpful in future studies.…”

A simple, safe and easily accessible polyvinyl alcohol hydrogel for wound cleaning

“…Numerous reports have shown that the ductility of materials plays an important role in bone tissue regeneration. 42 Adjustable changes in tensile stress may also have applicability for wearable electronics, sensors, and similar devices. 43 Additionally, the adhesion of hydrogels to certain substances may be interesting in terms of exploring the adsorption of inflammatory factors.…”

Effect of different structures fabricated by additive manufacturing on bone ingrowth

“…Quantitative Micro-CT reconstruction data analysis and tissue staining analysis are both classic methods for judging the osteogenesis of metal implants. 24,25 Quantitative Micro-CT scans a clear image of rabbit femoral condyle specimens, and performs volumetric reconstruction, which can intuitively and comprehensively display the distribution characteristics of new bone formation around the scaffolds. Micro-CT scan can also reveal the soft tissue growths within the pores.…”