Thomas Mosnier, chief scientific officer of Medicrea—manufacturer of personalised devices such as the UNiD Rod for scoliosis treatment—talks to Spinal News International about the opportunities 3D printing offers for the large-scale production of patient-specific spinal products.
What is the typical manufacturing process from patient consultation and imaging to surgery?
Actually, there is no ‘typical’ manufacturing process because every case is unique. Manufacturing for us means bringing the digital to the physical with personalised implants. As well as production, we involve strong information technology (IT) and data analytics components to our work to form an iterative system.
We use the company’s UNiD technology in this process. Part of my role is leading our team of biomechanical engineers, known collectively as the UNiD Lab. We run preoperative simulations for the surgeon based on patient imaging through our specialised software to adapt implant design to surgeon strategy, the morphology of the patient’s spinal column and to achieve the fundamental mechanical equilibrium shown through sagittal alignment parameters.
In reality this process only takes a couple of days. We aim to understand a surgeon’s strategic preferences and apply them directly, while also analysing the outcomes postoperatively to fine tune future cases using predictive algorithms.
What has led you towards manufacturing with 3D-printed titanium instead of PEKK?
Three-dimensional brings significant benefits to production, keeping lead times short, enabling micro-control of structural design and removing the potentially limiting existing economies of scale.
We were looking to expand our patient-specific implant capabilities quickly and formed a relationship with an innovative 3D printer and performed a world-first in the process: producing the patient-specific, 3D-printed interbody UNiD 3D anterior lumbar interbody fusion (ALIF) device, in May 2014. Since the supplier specialised in 3D printing polyetherketoneketone (PEKK), we printed the UNiD ALIF and the first generation of our subsequent 3D-printed UNiD 3D vertebral body replacement devices from this material.
In parallel, we invested in our own 3D-printing machine that would use titanium, the material we were already looking at for the next generation.
What are the surfaces of different implants like? Will using titanium offer different possibilities?
They vary. Because UNiD 3D implants involve collaboration of surgeon and biomechanical engineer in each case, we employ sophisticated modelling software to configure every surface and design element of the implant to precisely match patient morphology and alignment targets factoring in surgical strategy such as approach and preferences such as surface texturing or adding teeth for primary stabilisation.
These configurations are designed to save time in surgery sizing implants or cutting mesh for vertebral body replacement cases, and also to optimise contact with the patient’s bone to encourage fusion. The result is a patient-specific implant that should fit like a glove with structural and surface properties that would simply not be possible using traditional manufacturing methods. Going through this exercise in 3D-printed titanium will enable further possibilities for customisation.
What particular benefits could titanium offer for patient and surgeon?
There are a lot of very interesting things that you can do with 3D-printed titanium which are not possible with other materials, structurally speaking; titanium lends itself well to 3D printing. For example, we can add precision porosity and increase bone graft capacity and placement through the design.
Having dedicated significant resources to this project since focusing on the concept of personalised spine, launching the printing technology in-house will add new dimensions of manufacturing options that were not achievable before.
How is this technology limited?
For medical use, 3D-printing still requires a robust quality control of each implant after it comes out of the machine.
One day, we can imagine printing implants directly in the operating room. The surgeon will be able to confirm the implant shape and sizing during the operation and print there and then with minimal delay and total intraoperative flexibility. The technology used in the printing machine itself is just not there yet.
Spinal implants are usually made according to standard designs. Can Medicrea manufacture personalised implants in high volumes?
Absolutely—that is the beauty of additive manufacturing. 3D printing machines have changed the trajectory of the medical device industry by drastically altering the existing economies of scale and scope to make innovative technologies commercially feasible on a global scale.
There is no longer the need to produce a minimum quantity as the costs remain relatively similar whether one or 100 of an item are produced. This principle makes the technology so well adapted to implant personalisation. Also, this reduces the need to carry a security stock as small batches may be manufactured as needed. There is no associated cost in changing the complexity of a design or utilising multiple designs simultaneously. This means a far greater scope of devices may be created as the production changeover is painless and there are not multiple machines to reset. We see 3D printing as welcoming a new era of personalised care.
Do you think that, in the future, all spinal implants will be patient-specific?
We are already seeing that certain implant types stand to benefit more from personalisation than others. For example, it is crucial to get implants that are designed to impact the patient’s sagittal alignment exactly right. There is an extensive body of scientific publications that show balancing the spine with the rest of the body is critical to achieving long-term success and improving postoperative quality of life. Understanding the science has dictated the direction of our patient-specific development.
Making all implants ‘patient-specific’ is closely linked to material and manufacturing innovations. What we are focusing on today is delivering the most efficient set of implants required to achieve the surgical plan defined preoperatively by UNiD process. The deeper we dive into the predictive IT element, the better we will be able to shape and define the priority of implant development as well.