Abstract
Purpose
There is a large gap between UKA and TKA in terms of tissue preservation including bone stock and knee ligament. We have recently introduced bicompartmental UKA (Bi-UKA) to fill the gap and achieve more “physiological” knee than TKA. In this study, we report the short-term results of Bi-UKA.
Subjects and Methods
Thirty knees in twenty-nine osteoarthritis patients who underwent Bi-UKA from December 2010 to December 2013 (6 males and 23 females, average age of 75) were clinically and radiologically evaluated with an average observation period of 19 months. The operative indications were (1)confirmed diagnosis of medial and lateral osteoarthritis or osteonecrosis with preserved status of patellofemoral joint; (2)range of knee flexion greater than 110°; (3)flexion contracture less than 20°; (4)clinically stable knee in the frontal and sagittal plane; (5)correctable knee deformity with fine knee congruency. In all cases, fixed type UKA was implanted through a tibia dependent cut using a spacer block. Zimmer Uni and TRIBRID UKA (Kyocera Medical Corporation) were implanted in 18 and 12 cases, respectively.
Results
The mean JOA score improved significantly from 57 points preoperatively to 89 points postoperatively. With regard to ROM, the mean extension significantly improved from −6° to −1° (p<0.001), and the mean flexion was almost unchanged from 134° to 139°. Six knees achieved maximum flexion angles of more than 150°. The mean leg alignment was unchanged from 174.5° to 175.2°, although there were five knees in which alignment was corrected by more than 10° after the surgery. All implant alingnments were reasonably acceptable and particularly, the gaps of setting angle between medial and lateral components were quite small in lateral view radiograph. A only major postoperative complication we have experienced was a periprosthetic tibia fracture, which had been successfully treated with screw fixation.
Discussion
Bi-UKA is a bone- and ligament-sparing procedure that may provide better knee function and patient satisfaction than does TKA. Complicated surgical procedure, relationship of placement position between medial and lateral prostheses, ligament balancing, and longer-term results remain subjects to be resolved. However, tibia dependent cut technique using spacer block was quite useful to improve the accuracy of implants positioning during Bi-UKA procedure. Our short-term results of Bi-UKA were well acceptable although there were a few complaints or complications. We would like to confirm the usefulness of this procedure and further establish the best indication by increasing the number of patients in the future.
