If the authors, William J. Long M.D.,FRCSC; Samir Nayyar, M.D., Kevin Chen. M.A., David Novikov, B.S., Roy I. Davidovitch, M.D., and Jonathan M. Vigdorchik, M.D., are correct in this conclusion, then their paper gives rise to this question: Why didn’t Stryker just make all its porous Tritanium acetabular cups using the latter process?
The newest study, titled, “Comparison of a highly porous titanium cup (Tritanium) and a conventional hydroxyapatite-coated porous titanium cup: A retrospective analysis of clinical and radiological outcomes in hip arthroplasty among Japanese patients,” was published in the November 2018 issue of the Journal of Orthopaedic Science.
This retrospective study compares aseptic loosening in 130 consecutive cases in 118 patients using the porous Tritanium primary acetabular cup as compared to 130 cases (130 patients) using a conventional Stryker cup, the Trident HA, between January 2011 and December 2014.
The mean follow-up duration was 41.3 months for the Tritanium cups and 38.1 months for the hydroxyapatite-coated cups.
“There were significant differences between the groups for radiolucent lines, cup abduction angle, and cup-center-edge angle. There were no significant differences in the clinical results,” the study concluded.
“Radiolucent lines increased in the Tritanium group (36.1% at 3 months and 60.7% at final follow-up), whereas they decreased in the Trident group (2.5% at 3 months and 0.8% at final follow-up). The occurrence of radiolucent lines was significantly higher in the Tritanium group than in the Trident group at each follow-up period.”
One cup loosening in the Tritanium group was identified at the final follow-up evaluation.
The study concluded, “the Tritanium group had a significantly higher rate of radiolucent line occurrence around the cups than did the Trident group. Thus, radiolucent lines can occur when using highly porous titanium cups; these lines indicate the possibility of future cup loosening. Longer follow-up and assessment of the results of using this implant are necessary.”
Orthopedics This Week provided the URLs of all the studies cited above to Stryker and requested comments for a follow-up report.
