In vivo analysis of post-joint-preserving surgery fracture of 3D-printed Ti-6Al-4V implant to treat bone cancer

Abstract

Cancer growth in the bone due to its random shape disables bone strength and thus changes its capacity to support body weight or muscles, which can crucially affect the quality of human life in terms of normal walking or daily activities. For successful patient recovery, it is necessary to remove the cancer-affected minimal bone area and quickly replace it with a biocompatible metal implant within less than 2 weeks. An electron beam-melted Ti-6Al-4V implant was designed and applied in a patient to preserve the natural knee joint close to the bone tumor. The developed implant fits the bone defect well, and the independent ambulatory function of the natural knee joint was restored in the patient within six weeks after surgery. A delayed fracture occurred six months after the successful replacement of cancer-affected bone with Ti-6Al-4V implant at the proximal meshed junction of the implant because of a minor downward slip. Microstructural, mechanical, and computational analyses were conducted for the fractured area to find the main reason for the delayed fracture. Our findings pertaining to the mechanical and material investigation can help realize the safe implantation of the three-dimensionally printed titanium implant to preserve the natural joints of patients with massive bone defects of the extremities.

Fabrication of a lattice structure with periodic open pores through three-dimensional printing for bone ingrowth

“…The mechanical properties of lattice structures are dependent on unit cell conformation 15 , 31 . The yield strength of the various lattice structures reportedly ranges within tens of MPa and a similar level of strength; hence, using lattice structures alone as orthopedic implants may not be suitable 11 , 15 , 31 . Except for some spacers for small bone defects that induce bone regeneration and internal bone bridging, the role of lattice structures in orthopedic implants is limited to providing osteoconduction and mechanical stability, depending on the solid structure.…”

“…Zhao et al reported that the size of the partially melted powder on the surface in the SLM method was significantly smaller than that of the EBM method 9 . Sintered unmelted powders on a surface and lattice structure for use as orthopedic implants for a fractures have also been reported 11 . To compare the surfaces of struts that made by SLM and EBM methods, the same lattices with a 2.0-mm unit size were fabricated and examined with SEM (Fig.…”

“…The mechanical properties of 3D-printed Ti6Al4V solid structure have been shown to be suitable for orthopedic implants compared to those of traditionally fabricated solid structures 10 . However, lattice structures used for securing biocompatibility and bone ingrowth have poor mechanical properties and microstructural weakness 11 , so load bearing can be difficult to achieve with them 1 – 5 . The bone-inducing ability of the lattice structure with Ti6Al4V has been previously reported in animal experiments and human studies 12 – 15 .…”

Fabrication of a lattice structure with periodic open pores through three-dimensional printing for bone ingrowth

“…The mechanical properties of lattice structures are dependent of the unit cell conformation 15,31 . The yield strength of the various lattice structures reportedly range within tens of MPa and this level of strength; hence, using lattice structures alone as an orthopedic implant can be di cult 11,15,31 . Except for some of the spacers for small bone defects that induce bone regeneration and internal bone bridging, the roles of lattice structures in orthopedic implants are limited to osteoconduction and mechanical stability depending on the solid structure.…”

“…The mechanical property of the 3D-printed Ti6Al4V solid structure has been well proven to be compatible for orthopedic implants compared to that of the traditionally fabricated solid structure 10 . However, a lattice structure, used for securing biocompatibility and bone ingrowth, has poor mechanical property and microstructural weakness 11 , so load bearing can be di cult to achieve with it [1][2][3][4][5] . The bone-inducing ability of the lattice structure with Ti6Al4V has been previously reported in animal experiments and human studies [12][13][14][15] .…”