ALknee Follow-up Study of the Cementless ATTUNE Rotating Platform and the Cementless LCS Rotating Platform Knee System

The cementless ATTUNETM Rotating Platform Knee system was compared in a single-blind, randomized RSA trial to its predecessor, the LCS rotating platform Knee System. In this previous study, 61 knees were subjected to RSA examinations at 1-day and 3, 6, 12 and 24 months postoperative. This study found a promising equal migration of both tibial components and a lesser migration of the femoral component of the ATTUNETM knee system after two years, although with a similar migration rate between year 1 and 2. this raises the question of whether the migration of the prostheses relative to each other will increase or remain the same in the long term. To examine this, a mid-and long-term RSA follow-up to measure migration is necessary. In addition, another new RSA measurement parameter has become known in recent years that may provide an indication of the bonding of the prosthesis to the bone at the time of measurement. This new parameter, called the Induced Displacement (ID) of a prosthesis, measures the position and orientation relative to the bone while the prosthesis is under different loading conditions (e.g., patient in supine or standing position). This means that a large measured difference between these different loading condition measurements would indicate that osseointegration of the prosthesis never occurred or is no longer present. To improve the understanding of the tendency of both prostheses to aseptic loosening after a mid- to long-term follow up, migration over time and inducible displacement analyses are necessary.

The primary objective of this study is to accurately compare mid- and long-term migration of two uncemented TKR prostheses. The secondary objectives of this study are to evaluate if inducible displacement can be used as a parameter to detect loose implants, and to compare inducible displacement, clinical and radiological outcome and patient-reported outcomes (PROMS) after a follow-up of 5 and 10 years of two uncemented TKR prostheses.