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

Marianne Koolen,Ruben Wauthle,Amir A Zadpoor,Saber Amin Yavari,Karel Lietaert,Harrie Weinans

doi:10.3390/ma13081992

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.

Highlights

Treatment of substantial bone defects that often result from removal of bone tumors or trauma is still a major challenge in orthopedic surgery
The wounds healed without complications and all animals stayed healthy during the rest of the study
Animals had an average weight of 406 ± 33 g at time of implantation, which increased during follow-up with an average of 66 ± 17 g

Summary

Introduction

Treatment of substantial (critical size) bone defects that often result from removal of bone tumors or trauma is still a major challenge in orthopedic surgery. Multiple treatment strategies including autografts or allografts are currently being used. Non-union is observed in 4.9% of the cases treated for bone fracture [1]. In 23% of ankle arthrodesis cases, for example, non-unions persist, requiring multiple invasive procedures and causing prolonged immobilization and even permanent morbidity [2]. It is important to develop bone substitutes that stimulate bone tissue regeneration and help in overcoming bony non-unions.

Methods

Results

Discussion

Conclusion