Advancing spinal surgery with 3D-printed Tritanium® implants “engineered for bone”

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Stryker’s 3D-printed Tritanium In-Growth Technology continues to impact spinal surgery. A novel, highly porous titanium material designed for bone in-growth and biological fixation1, Tritanium was first introduced to spinal surgeons in 2016 when Stryker’s Spine division launched the Tritanium Posterior Lumbar (PL) Cage used in lumbar interbody fusion procedures for skeletally mature patients with degenerative disc disease and other conditions.

Enabled by AMagine, Stryker’s proprietary approach to implant creation using additive manufacturing (also known as 3D printing), Tritanium is inspired by the microstructure of cancellous bone2, and is deliberately designed for fusion. Its unique porous structure
is designed to create a favourable environment for cell attachment and proliferation, as demonstrated in an in vitro study,2,3* and may be able to wick or retain fluid when
compared to traditional titanium material.

Tritanium implants reflect Stryker Spine’s commitment to being at the forefront of technological advances in spinal surgery, and to providing surgeons with a range of options to address their preferences in spinal fusion products and meet the needs of their patients.

Scott Kutz, M.D., a neurosurgeon at Texas Back Institute in Plano, Texas, says, “I was intrigued by Tritanium because of the idea of bone in-growth. I really liked the large graft window and imaging characteristics of Tritanium vs. other metal implants I’ve used.”

According to Bradley Paddock, president of Stryker’s Spine division, the benefits of using additive manufacturing to create highly porous spinal implants that are ‘engineered for bone’ are becoming increasingly clear. “Additive manufacturing allows us to push beyond conventional manufacturing techniques to address design complexity and achieve previously unmanufacturable geometries, and to deliver the performance, reproducibility, and quality our customers have come to expect,” Paddock says.

Early feedback on the Tritanium C Cage has been overwhelmingly positive. According to Mohammed Faraz Khan, M.D., from Hackensack University Medical Center (New Jersey, USA), one of the first surgeons to use the new cage, the benefits of the Tritanium C Anterior Cervical Cage are clear. “In my opinion, this new addition is going to make all the difference in this space,” Khan says. “The inserter used with the system was super sleek and easy to use.”

Lance Smith, M.D., an orthopaedic surgeon based in Oklahoma City (Oklahoma, USA) says, “This is another great product by Stryker that brings revolutionary technology to the operating room. With many product sizes and lordosis options, I felt like I could truly match the anatomy and needs of the patient with the implant. I look forward to using more of this product.”

Tritanium in-growth technology
Tritanium is the culmination of more than 15 years of extensive research, development, and validation in material science and manufacturing, and it has been utilised clinically in hip and knee applications for more than 10 years — with more than 300,000 orthopaedic devices implanted5 (see Empowered by AMagine section below).

Stryker’s proprietary additive manufacturing process allows Stryker to create a material with precise and randomised porous structures that resemble cancellous bone, a type of spongy bone tissue.1,2 Tritanium’s porous matrix is specifically engineered based on studies that have sought to understand which geometry and pore size would provide a favorable environment for cells to attach and multiply within the structure for spinal applications.2,6,7

The Tritanium PL and C Cages feature precise randomisation2 of pore formation that differs from other technologies that have longitudinal channels and traverse windows that result in a uniform structure, as well as cages that offer porous technology that is only present on the surface.

Stryker’s high-resolution additive manufacturing process allows the company to push beyond the constraints of conventional manufacturing to create new implant designs. The process enables Tritanium cages to be designed and built with pinpoint precision, optimising pore size, porosity, geometry, and surface texture to help achieve fusion.5

Stryker’s spine division is committed to supporting research and pre-clinical studies on Tritanium in-growth technology. Key research is summarised below:

  • A pre-clinical animal study compared the biomechanical, radiographic, and histological performance of spinal implants with different surface technologies in an ovine lumbar interbody fusion model. The interbody fusion cages involved in this study included traditional PEEK cages, plasma-sprayed titanium-coated PEEK cages, and Stryker’s 3D-printed Tritanium PL cages.8 (No correlation to human clinical outcomes has been demonstrated or established.)
  • A recent wicking experiment demonstrated that a cube built with Tritanium material was able to wick fluid into the porous structure under specified conditions4, and it also absorbed and held fluid inside the porous structure4. This in vitro study was performed using heparinised porcine bone marrow aspirate. (No correlation to human clinical outcomes has been demonstrated or established.)
  • In a cell proliferation experiment, a coupon built with Tritanium material demonstrated that osteoblasts (cells) infiltrated, attached to, and proliferated on the porosity of the Tritanium technology.9 This in vitro study was performed with heparinised porcine bone marrow aspirate. (No correlation to human clinical outcomes has been demonstrated or established.)

Tritanium spinal fusion implants “engineered for bone”
The first spinal surgery products built with Tritanium technology are the Tritanium PL Posterior Lumbar Cage and the Tritanium C Anterior Cervical Cage.

The Tritanium PL and C Cages feature fully interconnected pores that span endplate to endplate with a mean porosity of 55–65 percent and a pore size range of 100–700μm. They are engineered for stability,10,11 designed to minimise subsidence, 12 and created to allow imaging.12-14 The roughened porous surfaces are designed to enhance interconnectivity and provide a stronger interface with surrounding bone compared to a smooth surface.4,7,15,16 The cages are offered in a variety of widths, lengths, heights, and lordotic angles designed to adapt to a variety of patient anatomies.

More information about Stryker’s Tritanium spinal implants can be found at www.stryker.com/builttofuse.

Next Up for Stryker’s spine division
In 2018, Stryker’s spine division will continue to focus on showing surgeons the value of Tritanium in-growth technology and how the Tritanium PL and C cages can support spinal surgery, and plans to expand Tritanium technology to additional spine applications.

Empowered by AMagine
The AMagine Institute, Stryker’s new global technology development centre located in
Cork, Ireland, is the world’s largest additive manufacturing facility for orthopaedic implants. The AMagine name reflects Stryker’s vision and unique approach to implant creation using additive manufacturing based on the company’s significant experience, expertise, and excellence in the field. Stryker’s surgeon customers have the unique opportunity to visit Stryker’s additive manufacturing facilities to get a first-hand look at the process and understand the “elegant complexity” of Tritanium products.

Stryker’s investment in additive manufacturing began in 2001 and, since then, Stryker has collaborated with leading universities in Ireland and the UK to industrialise 3D printing for the healthcare industry. From rapid prototyping to large-scale commercial production, the AMagine Institute allows Stryker to push beyond conventional manufacturing techniques to address design complexity and manufacture previously unmanufacturable geometries, and also to deliver the performance, reproducibility, and quality surgeons expect from Stryker products.

AMagine, which incorporates hundreds of quality checks per batch, enables Stryker to design and build the Tritanium PL and C Cages with pinpoint precision, and to optimise device characteristics, from pore size and porosity to shape and surgical features, for use in spinal surgery.5

The manufacturing of Tritanium technology is now in its third generation, and today Stryker makes and sells more orthopaedic implants using additive manufacturing than any company in the world.

References:
1. PROJ43909 Tritanium Technology Claim Support Memo.
2. Karageorgiou V, Kaplan D. Porosity of 3D biomaterial scaffolds and osteogenesis.
Biomaterials 2005;26:5474–91.
3. RD0000053710 | Tritanium cell infiltration and attachment experiment.
*No correlation to human clinical outcomes has been demonstrated or established
4. RD0000050927 | Tritanium material capillary evaluation.
5. Data on file, Stryker’s Spine division.
6. Bobyn JD, Pilliar RM, Cameron HU, Weatherly GC. (1980) The optimum pore size
for the fixation of porous-surfaced metal implants by the ingrowth of bone. Clinical
Orthopaedics and Related Research, 150, 263-270.
7. Webster TJ, Ejiofor JU. (2004) Increased osteoblast adhesion on nanophase metals;
Ti, Ti6AI4V, and CoCrMo. Biomaterials, 25, 4731-4739.
8. McGilvray KC, et al. Biomechanical and histologic comparison of a novel 3-D printed
porous titanium interbody cage to peek. The Spine J, 2016. 16(suppl. 10): S363–364
9. Olivares-Navarrete R, Gittens RA, Schneider JM, et al. Osteoblasts exhibit a more
differentiated phenotype and increased bone morphogenetic protein production on
titanium alloy substrates than on poly-ether-ether-ketone. Spine J. 2012;12(3):265–72.
10. PROJ44960: Coefficient of Friction Memo .
11. PROJ0000054458 | Tritanium C Insertion and Expulsion Marketing Memo.
12. PROJ0000054457 | Tritanium C Subsidence Marketing Memo.
13. PROJ0000054459 | Tritanium C Implant Imaging Marketing Memo.
14. Abbushi A, Cabraja M, Thomale UW et al. The influence of cage positioning and
cage type on cage migration and fusion rates in patients with monosegmental posterior
lumbar interbody fusion and posterior fixation. Eur Spine J. 2009;18(11):1621-8
15. Oldani C and Dominguez A (2012). Titanium as a Biomaterialf or Implants. Recent
Advances in Arthroplasty. Dr. Samo Fokter (Ed.). ISBN: 978-953-307-990-5. InTech.
16. Deligianni DD, Katsala N, Ladas S et al. Effect of surface roughness of the titanium
alloy Ti-6Al-4V on human bone marrow cell respose and on protein adsorption. Biomaterials.
2001;22(11):1241-51.
Surgeons quoted above may be paid consultants of Stryke.r The statements represent
their own opinions based on personal experience and are not necessarily those of
Stryker. Individual experiences may vary. A surgeon must always rely on his or her
own professional clinical judgment when deciding whether to use a particular product
when treating a particular patient. Stryker does not dispense medical advice and
recommends that surgeons be trained in the use of any particular product before using
it in surgery.
A surgeon must always rely on his or her own professional clinical judgment when
deciding whether to use a particular product when treating a particular patient. Stryker
does not dispense medical advice and recommends that
surgeons be trained in the use of any particular product before using it in surgery.
The information presented is intended to demonstrate the breadth of Stryker product
offerings. A surgeon must always refer to the package insert, product label and/or
instructions for use before using any Stryker product. Products may not be available
in all markets because product availability is subject to the regulatory and/or medical
practices in individual markets. Please contact your Stryker representative if you have
questions about the availability of Stryker products in your area.

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