Porous Titanium‐6 Aluminum‐4 Vanadium Cage Has Better Osseointegration and Less Micromotion Than a Poly‐Ether‐Ether‐Ketone Cage in Sheep Vertebral Fusion

Abstract

Abstract:Interbody fusion cages made of poly-ether-etherketone (PEEK) have been widely used in clinics for spinal disorders treatment; however, they do not integrate well with surrounding bone tissue. Ti-6Al-4V (Ti) has demonstrated greater osteoconductivity than PEEK, but the traditional Ti cage is generally limited by its much greater elastic modulus (110 GPa) than natural bone (0.05-30 GPa).In this study, we developed a porous Ti cage using electron beam melting (EBM) technique to reduce its elastic modulus and compared its spinal fusion efficacy with a PEEK cage in a preclinical sheep anterior cervical fusion model. A porous Ti cage possesses a fully interconnected porous structure (porosity: 68 ± 5.3%; pore size: 710 ± 42 μm) and a similar Young's modulus as natural bone (2.5 ± 0.2 GPa). When implanted in vivo, the porous Ti cage promoted fast bone ingrowth, achieving similar bone volume fraction at 6 months as the PEEK cage without autograft transplantation. Moreover, it promoted better osteointegration with higher degree (2-10x) of bone-material binding, demonstrated by histomorphometrical analysis, and significantly higher mechanical stability (P < 0.01), shown by biomechanical testing. The porous Ti cage fabricated by EBM could achieve fast bone ingrowth. In addition, it had better osseointegration and superior mechanical stability than the conventional PEEK cage, demonstrating great potential for clinical application.

Do Surface Porosity and Pore Size Influence Mechanical Properties and Cellular Response to PEEK?

“…Interest in improving PEEK's osseointegration has accelerated in recent years after numerous reports have described its inability in smooth form to facilitate bone apposition [9,23,25,34,51]. Reasons why this interest persists (as opposed to abandoning PEEK altogether) are often attributed to the other qualities of PEEK that make it favorable in orthopaedic and spinal applications, mainly its radiolucency, MRI compatibility, high strength, and fatigue resistance.…”

A study on the mechanical characteristics of the EBM-printed Ti-6Al-4V LCP plates in vitro

“…To reduce its elastic modulus, designing implants with porous titanium can provide a lower bend modulus to decrease stress shielding [17,18]; implants with a porous titanium surface also facilitate bone ingrowth and are biocompatible [6,18,19]. Thus, we imagine that a porous plate surface can be designed to contact the bone, which will enhance the plate internal fixation system stability and reduce the friction between the plate and surrounding soft tissue.…”

An analysis of spine fusion outcomes in sheep pre-clinical models

“…Lastly, we chose to specifically focus on fusion rates across various control groups, so we are therefore unable to comment on the influence of different bone graft materials on fusion rates in sheep models. Readers should note that several additional papers studying sheep fusion models were published after the completion of our data analysis [31][32][33][34].…”