抄録
Total knee replacement has been performed in 79 knees of 54 patients using the prosthesis of resurfacing design in which it is possible to preserve both cruciate ligaments or the posterior cruciate ligament.
The original diagnosis was rheumatoid arthritis in 48 patients and osteoarthritis in 6. The average age at the time of surgery was 59 years (range, 33 to 77 years) . The follow-up period ranged from 2 to 9 years, with an average of 3.3 years. The U.C.I. type was used in 25 knees, the Kinematic anteriorly-joined type (AJT) in 34 and the Kinematic posterior cruciate retention type (PCRT) in 20.
The femoro-tibial angle (FTA) was measured in a standing anteroposterior radiograph of the knee while the patient stood on the leg.
In cases with the U.C.I. type, the average FTA (standing) was 174.8°±8.3° (standard deviation) at one year after the operation, 178.3°±7.7° at 3 years and 185.5°±10.7° after more than 6 years. That is, FTA (standing) showed a gradual increase after U.C.I. total knee replacement.
On the other hand, in Kinematic AJT cases, FTA (standing) demonstrated 171.2°±4.0° at 6 months after the surgery and 173.0°±8.1° at 3 years. In Kinematic PCRT ones, FTA (standing) was 172.7°±6.8° at 6 months and 172.8°±8.7° at 3 years. FTA (standing) hardly increased in these groups.
It is suggested that total knee replacement should be performed to have a postoperative femoro-tibial angle (standing) of at least 172° in which the mechanical axis of the lower extremity passes through the center of the knee.
