100 patients suffering from non-inflammatory osteoarthritis of the knee, scheduled for unilateral primary total knee arthroplasty, were randomized to receive a posterior cruciate substituting or retaining implant to primarily assess differences in range of motion with secondary analysis of pain, function, and quality of life. Results from an average final follow up of 22.7 months indicated that both groups provided significant improvements in all outcomes from preoperative measures; however, there were no differences between the implants. This trial indicated that the posterior cruciate substituting device does not provide additional flexion and extension.