Rising Awareness of Issues With 3D-Printed Spinal Implants
The earliest MDR we found for the Tritanium PL was received by MAUDE April 26, 2016, regarding an April 1, 2016 incident:
“It was reported that the doctor was inserting the cage into the disc space. He was malleting the cage in and the cage split in half. Half the cage was in the disc space and half was still on the inserter. Normal steps were taken to prepare the disc space; shavers, paddles, and trials.”
Stryker commented at the bottom of that report:
“Correspondence with the sales rep confirmed that distraction off of the screws was not performed initially and that the space was “pretty tight.” conclusion: this suggests that the most likely cause of the customer reported event is inadequate distraction of the disk space prior to insertion.”
There is no indication of which version of the IFU the surgeon used. For this news report, we reviewed only the first version and the post-recall version, which, from a filename, appears to be the fourth edition.
Orthopedics This Week sought an interview with Stryker officials over the recall and surgeons’ criticism. Through an outside media representative, Stryker had us submit written questions. This is Stryker’s full response to our several questions:
“The quality of our products for patients and caregivers is our top priority. Stryker updated the Tritanium PL Surgical Technique Guide to warn against using surgical techniques that are outside the approved instructions for use. As a point of clarification: FDA’s definition of a recall includes a firm’s removal or correction of a product. In this instance, the update to the labeling (Surgical Technique Guide) is considered a correction. This action does not require the physical removal of any Tritanium PL products.”
Stryker’s Tritanium technology (which the company also uses in knee and hip implants) is not the only porous implant structure on the market. Stryker’s marketing literature describes it as a unique lattice structure designed to “mimic” or “imitate” cancellous bone.
The Tritanium PL has been tested for bone in-growth in sheep. Stryker cites those tests in a Technical Summary as evidence that the porous Tritanium lattice promotes greater integration of bone with the device than competitors’ products.
Stryker has received 510(k)s for two similar implants, the Tritanium TL, a curved cage, and the Tritanium C, a cage for the cervical spine. Neither of those implants was subject to the recall.
200 Predicate Devices
The FDA lists 200 previous “intervertebral fusion device with bone graft, lumbar” devices in its FDA database which are substantially equivalent to the Tritanium PL implant. Those devices have accumulated 2,395 problem reports in the FDA database from 2004 through February 9, 2019 of which 705 are for reported breakage and 187 for fractures (the numbers aren’t additive, as some reports used both terms).
A study of census data put the number of lumbar fusion surgeries at 121,224 in 2004, 180,770 in 2012 and rising annually. Thus, 705 plus no more than 187 reported breakages or fractures for all predicate devices since 2004 adds up to no more than four per ten thousand.
We didn’t analyze or see any analysis of how many of those breakage reports were of non-porous titanium and how many were made of the biopolymer polyetheretherketone (PEEK). However, all the MDRs we saw for breakages in 2016-2019, other than the porous 3D titanium reports, were of PEEK cages.
Of these 200 prior devices, only 13 received pre-market approvals (PMAs), the latest of which was in 2006.
The Tritanium PL may have been only the second 3D lumbar cage on the market, after an August 20, 2015 clearance for the Cascadia Interbody System, which K2M, Inc. claims to have been the first.
Stryker acquired K2M August 30, 2018. It is not known whether Stryker intends to continue marketing both the Tritanium PL and the Cascadia cage. In our MAUDE searches since late 2015, we found only two reports of breakages for K2M’s Cascadia 3D porous cage.
The Tritanium material and the technology from which it is made have been in use in other implants for more than a decade. In a July 14, 2017 interview in Spinal News, John Mayer, who was vice president, Global Marketing for Stryker’s Spine division, said, “The material is the culmination of nearly 15 years of extensive research, development, and validation in material science and manufacturing, and it has been utilised clinically for more than 10 years—with more than 300,000 knee and hip devices implanted.”
Upcoming Related Stories
- FDA and ASTM International (formerly known as American Society for Testing and Materials) working on more vigorous tests for 3D porous cages
- Four studies of Stryker’s Tritanium acetabular cups
- Some Blue Cross-Blue Shield plans label porous 3D implants “investigational” or “experimental”
