A Prospective, Multicenter Study to Evaluate the ConforMIS iTotal® (CR) Knee Replacement System

Inclusion Criteria: * Clinical condition included in the approved Indications For Use for the iTotal® CR * Osteoarthritis, as confirmed by the investigator's assessment of disease status at screening visit that warrants a TKR procedure. Disease status is assessed by Clinical and Radiographic assessment. * Willingness to participate in the clinical study, to give informed consent and to attend all follow-up visits * \> 18 years of age Exclusion Criteria: * Simultaneous bilateral procedure required * BMI \> 40 * Active malignancy (defined as a history of any invasive malignancy - except non-melanoma skin cancer), unless patient has been treated with curative intent and there have been no clinical signs or symptoms of the malignancy for at least 5 years * Poorly Controlled diabetes * Neuromuscular conditions which prevent patient from participating in study activities * Active local or systemic infection * Immunocompromised * Fibromyalgia or other general body pain related condition * Rheumatoid arthritis or other forms of inflammatory joint disease * Loss of bone or musculature, osteonecrosis, neuromuscular or vascular compromise in the area of the joint to be operated to an extent that the procedure is unjustified * Diagnosed with or receiving treatment for Osteoporosis * Other physical disability affecting the hips, spine, or contralateral knee. * Severe instability due to advanced loss of osteochondral structure * Prior arthroplasty of the affected knee, including High Tibial Osteotomy (HTO) * Compromised PCL or collateral ligament * Severe fixed valgus or varus deformity of \>15º * Extensor lag \> 15 º * Fixed flexion contracture ≥ 15 º * Unwilling or unable to comply with study requirements * Participation in another clinical study which would confound results * Allergy to any of the implant materials