Can Activated Titanium Interbody Cages Accelerate or Enhance Spinal Fusion? A Review of the Literature and a Design for Clinical Trials

While spinal interbody cage options have proliferated in the past decade, relatively little work has been done to explore the comparative potential of biomaterial technologies in promoting stable fusion. Innovations such as micro-etching and nano-architectural designs have shown purported benefits in in vitro studies, but lack clinical data describing their optimal implementation. Here, we critically assess the pre-clinical data supportive of various commercially available interbody cage biomaterial, topographical, and structural designs. We describe in detail the osteointegrative and osteoconductive benefits conferred by these modifications with a focus on polyetheretherketone (PEEK) and titanium (Ti) interbody implants. Further, we describe the rationale and design for two randomized controlled trials, which aim to address the paucity of clinical data available by comparing interbody fusion outcomes between either PEEK or activated Ti lumbar interbody cages. Utilizing dual-energy computed tomography (DECT), these studies will evaluate the relative implant-bone integration and fusion rates achieved by either micro-etched Ti or standard PEEK interbody devices. Taken together, greater understanding of the relative osseointegration profile at the implant-bone interface of cages with distinct topographies will be crucial in guiding the rational design of further studies and innovations

Effect of layer thickness and printing orientation on mechanical properties and dimensional accuracy of 3D printed porous samples for bone tissue engineering.

Powder-based inkjet 3D printing method is one of the most attractive solid free form techniques. It involves a sequential layering process through which 3D porous scaffolds can be directly produced from computer-generated models. 3D printed products' quality are controlled by the optimal build parameters. In this study, Calcium Sulfate based powders were used for porous scaffolds fabrication. The printed scaffolds of 0.8 mm pore size, with different layer thickness and printing orientation, were subjected to the depowdering step. The effects of four layer thicknesses and printing orientations, (parallel to X, Y and Z), on the physical and mechanical properties of printed scaffolds were investigated. It was observed that the compressive strength, toughness and Young's modulus of samples with 0.1125 and 0.125 mm layer thickness were more than others. Furthermore, the results of SEM and μCT analyses showed that samples with 0.1125 mm layer thickness printed in X direction have more dimensional accuracy and significantly close to CAD software based designs with predefined pore size, porosity and pore interconnectivity

Compressive Stress-Strain Curve for different layer thickness in X (a), Y (b) and Z (c) direction printing.

<p>Compressive Stress-Strain Curve for different layer thickness in X (a), Y (b) and Z (c) direction printing.</p

Comparision of samples' specification between CAD design and μCT results.

<p>Comparision of samples' specification between CAD design and μCT results.</p

Average height of 3D printed samples with standard error.

<p>Average height of 3D printed samples with standard error.</p

Fabrication condition of samples.

<p>Fabrication condition of samples.</p

SEM image of one pore in 3D printed sample.

<p>SEM image of one pore in 3D printed sample.</p

XRD pattern of ZP150 powder, Calcium Sulfate semihydrate.

<p>XRD pattern of ZP150 powder, Calcium Sulfate semihydrate.</p

Different printing orientation of samples.

<p>Different printing orientation of samples.</p