Compared to a statistically similar cohort, patients implanted with a high-flex poster-stabilized prosthesis achieved greater return of flexion than that with a standard posterior stabilized implant. In addition, patients with a high flexion arc preoperatively retained this high arc of flexion after surgery. Finally, there was an increase in the range of flexion seen after surgery in both groups of patients, but larger in the group in which the modified high-flexion implant was used.