Inserting the best knee: A short-term analysis of posterior stabilized versus cruciate substituting ultracongruent tibial inserts for total knee replacement

Abstract

Objectives: As the posterior cruciate ligament is a primary stabilizer of the knee, it is functionally replaced using posterior stabilized (PS) or anterior stabilized ultracongruent (UC) inserts in cases where it is attenuated or requires resection. This study compared PS and UC inserts in terms of functional and pain scores in patients undergoing total knee replacement (TKR). Methods: This prospective randomized study included 90 consecutive patients who underwent total TKR; PS and UC inserts were used in 47 and 43 patients, respectively. Outcomes were measured over 1 year. The duration of surgery was recorded, and the pain was assessed using the Visual Analog Scale score; functional outcomes were evaluated by assessment of the range of motion (ROM), Knee Society Score, and joint stability. All parameters and scores were assessed pre-operatively, immediately post-operative, 1 month, 3 months, and at 1-year follow-up. Results: The groups showed no significant differences and matched similarly in terms of body mass index, sex, or age. At a minimum of 1-year follow-up, TKR using either insert significantly improved the mean ROM and Knee Society and functional scores, which were comparable between the groups. Overall, 14 and 13 patients with UC and PS inserts, respectively, had excellent outcomes; 2 and 1 patients from the PS and UC groups, respectively, were lost to follow-up. Surgery was significantly shorter in the UC group. Although the Visual Analog Scale score had reduced significantly in both groups at the end of 3 months, one patient from the PS group had persistent knee pain with decreased ROM. Conclusion: The inserts showed no significant differences in terms of the ROM and Knee Society and functional scores. Surgery was notably shorter in the UC group (by 5 min). TKR using UC inserts is an effective alternative in patients with small bony geometry and may preserve intercondylar bone.