The Medacta GMK SpheriKA Post-Marketing Surveillance Study

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.