Inclusion Criteria:

• Male or female subjects, aged between 45 and 75 years inclusive.
• Subjects who are able to give voluntary, written informed consent to participate in this investigation and from whom consent has been obtained.
• Subjects who are able to achieve a pre-operative passive range of motion of equal to or greater than 125º.
• Subjects who, in the opinion of the Investigator, are able to understand this investigation, co-operate with the investigational procedures and are willing to return to the hospital for all the required post-operative follow-ups.
• Subjects who present with idiopathic osteoarthritis that in the opinion of the clinical investigator requires a primary total knee arthroplasty.
• Subjects who in the opinion of the Clinical Investigator are considered to be suitable for treatment with the P.F.C.â Sigma RPF knee, according to the indications specified in the package insert leaflet.

Exclusion Criteria:

• Subjects who, in the opinion of the Investigator, have an existing condition that would compromise their participation and follow-up in this study.
• Women who are pregnant.
• Subjects who are known drug or alcohol abusers or with psychological disorders that could effect follow-up care or treatment outcomes.
• Subjects who have participated in a clinical study with an investigational product in the last month (30 days).
• Subjects who are currently involved in any personal injury litigation claims.
• Subjects with a known history of poor compliance to medical treatment.
• Subjects who have a pre-operative limb deformity of equal to or greater than 10° varus or 15° valgus as defined using the anatomical axis.
• Subjects who have morbid obesity i.e. BMI ≥40.
• Subjects who wish to have a simultaneous bilateral procedure. However, subjects who have had a staged bilateral procedure may be included as long as the previous procedure was performed 9 or more months prior to their inclusion in the study.