The PFC Sigma Knee by DePuy Synthes is an excellent knee replacement with an excellent clinical track record, good survival rates (98% 10 years survival in patients aged < 55 years) and minimal early migration as measured with RSA (0.5mm MTPM at two years follow-up).

The Attune Knee by DePuy Synthes is an advancement in knee replacement options. It is designed to provide better range of motion and address the unstable feeling some patients experience during everyday activities, such as stair descent and bending. To date, more than 470,000 patients have received an Attune Knee and positive feedback was received regarding patient recovery, stability and motion.

The objective of this study is to accurately assess and compare migration, clinical and radiological outcome and patient reported outcomes of two knee prostheses: the Cemented Attune Fixed Bearing Cruciate Retaining Knee System and the Cemented PFC Sigma Fixed Bearing Cruciate Retaining Knee System, both by DePuy Synthes, Warsaw, Indiana, USA. The primary objective of this study is to compare the magnitude and pattern of migration of the prostheses (Femoral and Tibial component). The secondary objective of this study is to compare clinical and radiological outcome of the prostheses and PROMS.

This study is designed as a single-blind, randomized trial between the Attune Knee System and PFC Sigma Knee System. 32 patients with the Attune Knee System and 32 patients with PFC Sigma Knee System will be included in this study.

The study population will consist of patients with symptomatic osteoarthritis of the knee scheduled for knee replacement surgery at the Department of Orthopaedics, Haags Medisch Centrum The Hague (HMC), The Netherlands. Annually 350 TKA procedures are performed in this department, of which about 90% is Osteo Arthritis (OA) and 10% Rheumatoid Arthritis (RA) and other indications. We anticipate that inclusion can be accomplished within a 1 year period and that the total study duration is 3 years.

Main study parameters/endpoints are:

• Migration, measured by means of RSA.
• Patient Reported Outcome Measures by means of questionnaires.

Inclusion Criteria:

• Patient is diagnosed with osteoarthritis and requires primary knee arthroplasty
• All consecutive patients ("usual care") are included to prevent selection bias in the migration analysis.
• Patient is capable of giving informed consent and expressing a willingness to comply with this study

Exclusion Criteria:

• The patient has an a-priori risk for a posterior-stabilized total knee arthroplasty.

  • Insufficiency of the posterior cruciate ligament (PCL)
  • Status after patellectomy
  • In case flexion is less than 90 degrees
  • The patient is diagnosed with Rheumatoid Arthritis
  • When it is expected that the tibia cut during surgery will compromise the attachment of the PCL (because of bony defects)

• The patient is unable or unwilling to sign the Informed Consent specific to this study

• The patient does not understand the Dutch or English language good enough to participate

• Patients indicated for revision arthroplasty instruments because of bone defects or deformity of the bone

• When there are not enough markers visible in the baseline RSA photograph and it will not improve by placing the patient in another position, the patient will be excluded from the study (secondary exclusion criteria).