This retrospective study evaluates the midterm results of the Rotating Platform PFC Sigma Total Knee Arthroplasty System. We reviewed 161 cases in 147 patients with an average follow-up of 5 years (4 to 7 years) operated on at our institution between June 2001 and June 2004. Patient outcomes were measured using the Oxford and American Knee Society Scores and radiographs underwent independent radiological evaluation. Average pre-operative Oxford Scores improved from 43(29-55) to 21 (13 - 44) postoperative;y and average Knee Society Scores improved from 57 (43-70) preoperatively to 80 (58-90) at last follow up. Range of movement improved from 91 degrees (70 - 110) to 113 degrees (75 - 130). There were 5 complications reported; one superficial infection treated with antibiotics, one patient required manipulation under anaesthesia at 3 months for post operative stiffness, which improved. There was one arthrotomy for dislocation of the bearing immediate postoperatively. There was one case of DVT and one non-fatal PE. There were no deep infections. The PFC Sigma Knee Rotating Platform system offers excellent mid-term results in our review.