Three Studies Question Long-Term Viability
The other three independent studies all raise questions about the long-term effectiveness of bone in-growth in primary (not revision) Tritanium acetabular cups.
“Short to Midterm Follow-Up of the Tritanium Primary Acetabular Component: A Cause for Concern,” a study of 109 hips in 95 patients published in February 2017 in the Journal of Arthroplasty, said, “At an average 4.24 + 1.49 years, implant survivorship of the Tritanium primary cup was 98.2%, with 2 cups revised for failure of osseointegration”—ostensibly, a high success rate.
However, the study found a high number of signs of future failure: “Despite adequate implant survivorship, over one-third of Tritanium primary cups had 2 or more zone radiolucency at minimum 5-year follow-up with associated lower Harris hip scores.” None of these 109 surgeries had hip screws implanted with the cups.
The group studied was a cohort of 118 patients who had the surgery at New York’s Hospital for Special Surgery in 2008 and 2009, Alberto Carli, M.D. FRCSC, the chief author, told Orthopedics This Week. Seven dropped out, one died, and one had revision surgery due to infection. Dr. Carli said the team hopes to do another follow-up next year.
A second study of five revision patients at NYU Langone Orthopedic Hospital, New York, published in June 2018 in Arthroplasty Today, “Early aseptic loosening of the Tritanium primary acetabular component with screw fixation,” found that bone in-growth had failed even when the surgeons had added screws as their “preference” rather than a specific medical reason, in five hip revision patients who had undergone their original hip arthroplasties between 2011 and 2016.
This study says, “In contrast to the Tritanium primary cups, we have not noticed similar loosening in the revision Tritanium acetabular cups.” This study describes very different manufacturing processes for the primary vs. revision Tritanium cups, adding, “It is likely that the Tritanium primary cup loosening is at least in part due to these differences in manufacturing processes. Specifically, the pore structure and polymeric binding agent used in the Tritanium primary cup may be directly related to its increased tendency to fail in comparison with the revision cup.”
