132 patients undergoing cruciate-retaining total knee arthroplasty (TKA) were randomized to evaluate the efficacy of high flexion implants against a standard prosthetic. 122 patients were included in the analysis with 51 patients receiving standard prosthetic and 71 receiving the High Flex implant. Patients' preoperative, intraoperative, and 1 year postoperative range of motion were assessed, along with other measures of knee function, and patient status. The evidence presented in this trial indicated superior intraoperative range of motion, associated with the high flexion implant. However, range of motion was comparable at all other time points, along with the similar clinical outcomes of Knee Society Score, and Short-Form 36. Knee flexion during the preoperative period was the only significant factor influencing knee flexion at follow-up.