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.

Inclusion Criteria:

In order to be eligible to participate in this study, a subject must meet all of the following criteria:

• The Patient participated in the initial study (NL58911.058.16) [1].
• The patient is capable of giving informed consent and expressing a willingness to comply with the study.

Exclusion Criteria:

A potential subject who meets any of the following criteria will be excluded from participation in this study:

• The patient underwent a major revision TKR (exchange of the tibial or femoral component).
• The patient is unable or unwilling to sign the informed consent specific to this study.

In this study, all subjects that participated in the initial study (ALknee study - NL58911.058.16) will be asked to participate. All these patients underwent a TKA for symptomatic osteoarthritis of the knee in the period of August 2017 and March 2018 at the Department of Orthopaedics in the Spaarne Gasthuis, Hoofddorp, The Netherlands.