“The FDA is putting an acute focus on additively manufactured devices. They really are putting a lens on it.”

When John Bohenick dials in to a trans-Atlantic call during his morning commute on February 10th, it has been 45 days since Osseus Fusion Systems made its latest submission to the FDA.

As the medical device company’s R&D/ Engineering Manager, Bohenick, who has been central to this application, is waiting patiently for the FDA’s verdict, and has so far twice been required to provide minor clarifications. This, Bohenick notes, is par for the FDA certification course. But since Osseus is seeking a unique surgical indication that no other product currently has, satisfying the FDA at every step is paramount.

“[This] is going to be a differentiable product regardless,” Bohenick begins, “but I think it would make a huge splash on the market by getting an indication that no other device on the market has achieved or has been granted, which is what we’re going for.”

The product that has buoyed Bohenick with so much enthusiasm is an additively manufactured Standalone Anterior Lumbar Interbody Fusion (ALIF) device called Pisces that cannot be manufactured with subtractive methods.

It is not the first time Osseus has pursued FDA certification of a 3D printed product, having done so successfully in 2018 after launching its Aries interbody fusion device which is made from titanium and features a mesh structure with 80% porosity. This device was among the early additive interbody devices to be introduced on the market and ‘put a wind behind the sails’ of a company that was looking to carve out a niche. Four years on, Osseus has again sought to harness metal additive manufacturing, designing the Pisces device for this very process, but there is the notion that this wouldn’t have been possible in years gone by.

"There are actual functional features and aspects to this design that have to be done additively,” Bohenick explains. “[But] the way that it’s being manufactured would not have been feasible even two, three years ago because of how specific the tolerancing is being held. [The] postsubtractive process is extremely minor, it’s just a chase on the tap. It’s testament to [how far] additive manufacturing has come.”

Although not yet available for sale in the US, Osseus believes Pisces will become the new standard for Standalone ALIF devices. It is available at a range of heights between 9-19mm, in footprints between 23 x 29mm and 29 x 39mm and can be implanted with anchors or screws. By integrating a highly porous 3D printed interbody with anatomical morphology, the device has been designed for full osseointegration, streamlined instrumentation and anchor fixation technology for a minimally invasive approach. Additionally, a guided locking plate prevents any sort of dislodgment or motion of the fixation, while the mesh structure of the device boasts nearly 80% porosity and also provides load bearing support.

“[80% porosity] is, I think, pretty impressive considering the strength that we were able to get out of it,” Bohenick says. “A majority of the volume of the interbody is made up of a porous, bilateral mesh meaning that it cuts through from both sides, so not just a unilateral mesh that some interbody devices have. That mesh, which allows you to maximise strength while also decreasing mass and allows for bone growth through, acts more as a scaffold. You’re trying to optimise the load that you’re bearing, while not having unused material. That mesh structure is really impossible to be manufactured subtractively.”

The motivation for this product’s introduction to market is to help provide better treatments for spinal disc pain that could be brought on by tumours, traumas, or, more likely, degeneration as people age. If such a diagnosis was made and the surgeon decided to use an interbody with fixation through an anterior access, then Osseus’ Pisces device would be a potential solution. Once implanted, it would help to stabilise the patient’s spine and facilitate bone fusion.

“This device tries to capitalise on the theoretical mechanotransduction principle,” Bohenick says, referencing the process by which cells convert mechanical stimuli into biochemical signals that elicit cellular responses. “If you’re able to distribute load over the entire endplate as much as is reasonably possible then you’re able to allow for bone growth across that entire surface, as opposed to just on the edges. So, wherever there’s going to be cyclic loading, you’re going to end up having bone growth. It made sense for us to try and approach a larger surface area contact on the interbody or on the endplate surface. What comes with that, then, is an anatomic profile of the end plates. There really are not many cages at all worldwide that have an anatomic profile on the end plates. This device does.

“Being able to have that load distribution across the entire endplate and especially in that concavity would then lead to having lower incidence of subsidence, as well. So, we’re trying to maximise a number of different factors that really will differentiate the product on the market.

“All of this mumbo jumbo technical talk really just comes down to, ‘hey, it looks right.’ And that’s what we’re going for. If a surgeon feels comfortable when they take a look at their fluoroscopy in the AP (antero-posterior) and lateral planes, then that’s a job well done for us.”

Osseus is set to roll out the Pisces device via its biggest ever Alpha launch with 15 units deployed to partner surgeons before a full launch coming further down the line. Bohenick says Osseus has more demand for its Pisces series than it knows what to do with, but whether such demand is for an FDA-approved product is still pending.

“We’ve been in contact with the FDA for at least a year and a half now. And the FDA outlined to us from very early on that, if we were going to prove that this device is worthy or permissible for this indication, we were going to have to do more than what is generally accepted for a standalone ALIF interbody fixation device,” Bohenick says. “The FDA is putting an acute focus on additively manufactured devices and, in particular, going between different manufacturers, whether or not the devices are biocompatible. They really are putting a lens on it. They’re having us go through and really get into the nitty gritty details of explaining, as well as testing, bio comp for these additively manufactured devices. And it’s just more than what they have asked for in the past.”

While Osseus has encountered recent cadaver shortages at the major tissue banks in the US and the cost complications that are typical for start-ups (since addressed with the assistance of the RIH Orthopaedic Foundation), it has also been required to carry out a series of studies to prove Pisces’ worth. These have included a cadaveric biomechanical range of motion fatigue study and a cadaveric technique validation, the latter of which sought to demonstrate the safety and efficacy of its anchor type fixation with the help of five orthopaedic and neurosurgeons, as well as one ALIF access surgeon.

By Bohenick’s own admission, the process of getting Pisces its unique FDA indication has been ‘quite an endeavour,’ but there is an assurance at Osseus that its latest additively manufactured implant will eventually make the grade.

“We feel pretty confident that we’re going to be getting the indications,” Bohenick finishes. “But nothing is set in stone yet.”

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