Despite clinical success, it is unclear which one, posterior-substituting (PS) or cruciate-retaining (CR) insert, has superior functional outcomes or longevity. We compared the collected results from 2 institutional review board–approved, multicenter, prospective observational studies following CR (412) and PS inserts (328). Participants were evaluated preoperatively, at 6 weeks, at 3 months, and at 1 and 2 years regarding pain, motion, function (Knee Society Score, Krackow Activity Score, Short Form–36), and procedure variables such as anesthesia and preoperative/perioperative/postoperative complications. Implant longevity was recorded at the 2-year follow-up. Improvement was observed within each group; however, there was no difference between groups in terms of pain, motion, or function at any end point. Two-year survival rate was higher than 95%. A higher incidence of wound hematoma was observed in the PS group. Both inserts can be used expecting satisfactory outcomes and high survival rates at 2 years.