This is a Post-Marketing Surveillance of GMK SpheriKA knee stem prosthesis.

The aim of the current study is to collect clinical and radiological data to monitor the performances of the "GMK® SpheriKA" Knee Prosthesis implanted via the kinematic alignment technique.

Inclusion Criteria:

• Patients willing to sign the informed consent.
• Patients able to comply with follow-up requirements, including postoperative weight-bearing restrictions and self-evaluations.
• Patients 18 - 80 years of age at the time of surgery.
• Patients requiring a primary total knee replacement (on label use).
• Patients with intact collateral ligaments.

Exclusion Criteria:

• Patients with inflammatory arthritis.
• Morbidly obese patients, with a body mass index (BMI) > 40.
• Patients with a history of total or unicompartmental reconstruction of the affected joint.
• Patients that have had a high tibial osteotomy or femoral osteotomy.
• Patients with neuromuscular or neurosensory deficiency, which would limit the ability to assess the performance of the device.
• Patients with a systemic or metabolic disorder leading to progressive bone deterioration.
• Patients that are immunologically compromised or receiving chronic steroids (> 30 days).
• Patients whose bone stock is compromised due to disease or infection, unable to provide adequate support and/or fixation to the prosthesis.
• Patients with an active or suspected latent infection in or surrounding the knee joint.
• Pregnant or breastfeeding women.

281 participants are planned for the entire project (all sites combined). Patients requiring "GMK® SpheriKA" implanted via the kinematic alignment technique will be informed and enrolled during the preoperative visit.

The study is conducted as standard of care treatment and participants will receive the same treatment and undergo the same postoperative assessments as non-participants.