Similar early migration when comparing CR and PS in Triathlon™ TKA: A prospective randomised RSA trial

ObjectivesThe objective of this study was to compare the early migration of the cruciate retaining and posterior stabilising versions of the recently introduced Triathlon™ total knee system, with a view to predicting long term fixation performance.MethodsSixty patients were prospectively randomised to receive either Triathlon™ posterior stabilised cemented knee prosthesis or Triathlon™ cruciate retaining cemented knee prosthesis. Tibial component migration was measured by radiostereometric analysis postoperatively and at three months, one year and two years.Clinical outcome was measured by the American Knee Society Score and Knee Osteoarthritis and Injury Outcome Score.ResultsThere were no differences in rotation around the three coordinal axes or in the maximum total point motion (MTPM) during the two year follow-up. The posterior stabilised prosthesis had more posterior–anterior translation at three months and one year and more caudal–cranial translation at one year and two years. There were no differences in functional outcome between the groups.ConclusionThe tibial tray of the Triathlon™ cemented knee prosthesis showed similar early stability.Level of evidenceLevel I.Article summaryArticle focus:This was a prospective randomised trial aiming to compare the single radius posterior stabilised (PS) Triathlon™ total knee arthroplasty (TKA) to the cruciate retaining Triathlon™ TKA system with regard to fixation.Strengths and limitations of this study:Strength of this study was that it is a randomised prospective trial using an objective measuring tool. The sample size of 25–30 patients was reportedly sufficient for the screening of implants using RSA [1].Trial registration:ClinicalTrials.gov Identifier: NCT00436982.