Total knee arthroplasty (TKA) is still considered the treatment of choice for painful osteoarthritis. In the last decades neutral mechanical knee alignment in the coronal plane has been considered the gold standard. However, the optimal TKA alignment is still debated. Today, component rotation measurements on three-dimensional (3D) reconstructed computed tomography (CT) images are considered the gold standard for assessing native preoperative alignment and TKA component position. In this study pre-and postoperative radiographic measurements, functional scores, and biomechanical parameters of patients with knee osteoarthritis will be assessed with the aim to investigate the relationship between deviations of TKA alignment from native preoperative alignment and clinical, functional and biomechanical alignment.

Total knee arthroplasty (TKA) is still considered the treatment of choice for painful osteoarthritis resulting in pain and functional improvement. Despite the development of novel prosthetic design and improved outcome, about 20% of patients report persisting pain interfering with their daily activities.Total knee prostheses are aligned in the coronal, sagittal and axial planes during implantation. In the last decades, neutral mechanical knee alignment in the coronal plane has been considered the gold standard. The aim of mechanical alignment in TKA is to achieve a femorotibial joint line that is perpendicular to the mechanical axis of the long leg axis hence correcting any varus-valgus deformity via prosthesis placement with the goal of equally distributing the load between the medial and lateral prosthesis component. However, the optimal TKA alignment is still debated. Traditionally, knee alignment and total knee arthroplasty component position have been assessed using radiographs. However, this method has a low accuracy and reliability because of variation in limb rotation, knee extension deficit, patient positioning, or magnification factors. Component rotation measurements on three-dimensional (3D) reconstructed computed tomography (CT) images have replaced former methods and are now considered the gold standard for assessing native preoperative alignment and TKA component position. In this study pre-and postoperative radiographic measurements, functional scores, and biomechanical parameters of patients with knee osteoarthritis will be assessed with the aim to investigate the relationship between deviations of TKA alignment from native preoperative alignment and clinical, functional and biomechanical alignment.

Inclusion Criteria:

• Age > 18 years
• Diagnosed osteoarthritis of the knee
• Planned primary total knee arthroplasty (cruciate retaining (CR) or posterior stabilizing (PS) designs)

Exclusion Criteria:

• Inability to provide informed consent
• Inability to communicate in German, French, Italian or English
• Any previous ipsilateral bony knee procedure prior to TKA
• Planned partial knee arthroplasty, semi- or full-constrained knee prosthesis
• Patients unlikely to attend clinical follow-up (e.g., when living abroad)
• Pregnancy
• Female participants of childbearing potential, not using a medically reliable method of contraception, who do not wish to undergo a pregnancy test prior to exposure to i ionizing radiation

Patients with knee osteoarthritis who are scheduled for a primary total knee arthroplasty