Back in 2013, a study funded by Stryker Corporation reported that all (100%) enrolled patients receiving its porous, 3D-manufactured primary Tritanium acetabular cup were experiencing no problems and the cups were performing well two to four+ years postoperatively.
That was then. Here’s now.
Three independent studies published between February 2017 and November 2018 raise questions about the long-term osseointegration and survival of this implant.
A fifth study, of Tritanium revision cups, which are said to use a different manufacturing process than the primary cups, concluded that the revision cups have excellent 6- to 10-year survival results.
Stryker’s porous Trident 3D-printed Tritanium acetabular cups were introduced in 2008. Stryker announced a next generation version in March 2018.
The 2013 Primary Cup Study and the Study of the Revision Cup
The Stryker-funded 2013 study of 252 patients who had received a total of 288 hip arthroplasties using the Tritanium technology, “Excellent Results of Primary THA Using a Highly Porous Titanium Cup,” concluded that 100% of the 288 implants were still successful as of 24-56 months (mean 36 months) after surgery.
In that study, the surgeries were all performed by three of the study’s authors, who all reported receiving royalties from Stryker and had other financial relationships with Stryker. The study doesn’t say how the 252 subjects were selected, such as whether they were all patients who’d received the implants from the three surgeons or a chosen subset of all. The postoperative time period was fairly short—two to four+ years—and the study says a longer time period is needed to draw firm conclusions.
The independent study of the Tritanium revision cups, “Tritanium Acetabular Cup in Revision Hip Replacement: A Six to Ten Years of Follow-Up Study,” published in August 2018 in the Journal of Arthroplasty, followed 62 patients. It reports, “The acetabular cup aseptic survivorship was 98.4% at a mean follow-up of 87.6 months. The mean Oxford Hip Score improved from 14.5 (3-31) preoperatively to 38.5 (12-48) at the final follow-up. Two cups were revised (3.2%): 1 for aseptic loosening and 1 for infection.”
That’s just one bad result out of 62 for aseptic loosening, which is the issue raised by the three not-so-positive studies cited below. The authors, who report no financial conflicts or funding from Stryker, conclude that “Tritanium revision acetabular cup has shown excellent mid-term to long-term clinical and radiographic results with low failure rate and minimal complications. Longer term follow-up would be of value.”
However, the revision cup is apparently manufactured differently.
