Problem to be addressed Knee osteoarthritis is a degenerative joint disease that is very prevalent in the general population and can cause significant functional impairment. Total knee arthroplasty (TKA) is the definitive treatment of choice, but rarely accomplishes complete restoration of natural knee biomechanics. Various factors may influence post-operative function: pre-operative state of the knee, patient age, implant position, and design. The natural lower limb anatomy presents a femoral joint surface that is slightly valgus according to its mechanical axis (1-5 degrees) and a tibial joint surface that is slightly varus (1-4 degrees). This combination results in an oblique joint line orientation (1-3 degrees) and a mechanical axis passing near the centre of the knee joint (line between the centre of the femoral head and the centre of the ankle). Natural lower limb alignment helps balancing load between the internal and external knee compartments at heel strike. Current practice in orthopedics is to recommend TKA implantation with the femoral and tibial components perpendicular to their mechanical axis (0 degrees). In addition, in order to maintain ligament balance (a rectangular space) in flexion, external rotation of the femoral implant is suggested (2-5 degrees according to posterior femoral condyle surfaces). Therefore, current surgical technique does not replicate natural knee anatomy and biomechanics. An alternative alignment method that attempts to replicate the kinematics of the knee is " kinematic alignment ". The principle behind kinematic alignment is placement of the TKA components so that the orthogonal 3-D orientation of the 3 axes that describe normal knee kinematics is restored to that of the prearthritic knee. Theoretical benefits of kinematic alignment include less ligamentous release to balance the knee intra-operatively, more rapid recovery, better range of motion (ROM), less post-operative pain, better knee biomechanics, and improved patient satisfaction. However, a major concern is that there are no mid- or long-term data on implant survivorship (absence of loosening) in TKA based on "anatomical" implantation. Because the anatomical alignment differs from the classic mechanical alignment, some authors raised concerns regarding mid-term implant stability with the anatomical implantation technique.