Table 1 The inclusion and exclusion criteria of the subjects

Inclusion criteria

• Patient with non-inflammatory knee osteoarthritis which is radiologically confirmed and which requires total knee replacement.

• Age between 40 and 75 years, inclusive.

• Patient plans to be available for follow-up until 2 years post-operative.

• Patient is in stable health and is free of or treated for cardiac, pulmonary, hematological, or other conditions that would pose excessive operative risk.

• Patient has < 10° fixed (non-correctable) varus or valgus deformity of the knee.

Exclusion criteria

• Patient has a BMI > 35.

• Patient’s expected physical activity after surgery is 2 or less on the UCLA Activity Scale.

• Patient has had previous hip or knee replacement surgery in the last 6 months or is planned to have a (second) hip or knee replacement in the next 6-12 months (because of the effect on function).

• Patient has had a previous hip replacement on the affected side (this may cause for a restriction for the rod placement during surgery).

• Patient has had major, non-arthroscopic surgery to the study knee, including HTO.

• Patient has an active, local infection or systemic infection.

• Patient has physical, emotional, or neurological conditions that would compromise compliance with post-operative rehabilitation and follow-up.

• Bone stock compromised by disease, infection, or prior implantation which cannot provide adequate support and/or fixation to the prosthesis.

• Severe instability of the knee joint secondary to the absence of collateral ligament integrity and function.

• Severe instability of the knee joint due to loss of cartilage reported as “substance loss.”

• Patient has knee flexion < 90°.

• Patient has fixed flexion deformity >10° (passive extension lag).

• Patient has >30° extension deficit (active restraint to extension).

• Patient does not have a proper functioning patella tendon on the affected side measured as inability of active extension of the knee.

• Patient has quadriceps weakness on the affected side; score on MRC scale < 4.

• Patient has rheumatoid arthritis, any auto-immune disorder, or immunosuppressive disorder.