A Randomized, Prospective Study of Primary Total Knee Components Designed for Increased Flexion

This prospective, randomized study reports early results for range of motion (ROM) after primary total knee arthroplasty. Group A received standard posterior-stabilized (PS) implants. Group B had PS implants designed for increased flexion. Average preoperative ROM was 2° to 121° for group A and 1.8° to 122° for group B. At 12-month follow-up, average ROM for group A was 0.6° to 120° as compared with 0.6° to 133° for group B (P < .05). Significantly more patients in group B flexed more than 135° (P < .05). Furthermore, 12 patients (48%) in group A failed to return to preoperative ROM versus 2 patients (8%) in group B (P < .05). Although long-term follow-up is desirable, these early results support the use of PS implants designed for increased flexion.