Improved range of flexion after total knee arthroplasty. The total condylar knee versus the KU knee.

One objective of the modification of the total condylar knee is to increase the range of flexion without compromising the durability of the prosthesis. The KU knee prosthesis was designed to improve postoperative range of motion. This prosthesis has a unique ball-and-socket joint in the center of the posterior portion of the femorotibial articulation. A retrospective comparative study was undertaken to determine whether the KU knee prosthesis had achieved its design objectives. The study was based on the clinical observation of two populations: one (the TC group: 31 joints) with total condylar prostheses and the other (the KU group; 31 joints) with KU knee prostheses. At two years postoperatively, the mean postoperative range of flexion was 94 degrees (range: 60 degrees to 120 degrees) in the TC group and 120 degrees (range: 95 degrees to 150 degrees) in the KU group. The mean postoperative range of flexion was 24 degrees better in the KU group than in the TC group (p < 0.01). The mean functional score was 76 points (range: 61 to 86) in the TC group and 81 points (range: 56 to 92) in the KU group. There were no statistically significant difference in pain, walking ability, deformity, extension lag, and activities of daily living (ADL) score between the two groups. However, a statistically significant difference was detected in the range of motion (ROM) score (p < 0.01). No major complications occurred in either of the two groups. Although the follow-up period was not long enough, the KU knee was thought to be a promising modification of the total condylar knee prosthesis.