Abstract
Purpose
The purpose of this study is to compare the mid-term outcomes between rotating platform(RP) and posterior cruciate substitute(PS) bearings in LCS-total knee arthroplasty (TKA).
Methods
This is a prospective randomized matched-pairs case–control study of patients who underwent primary TKAs with a minimum 2 years follow-up. The inclusion criteria was degenerative arthritis, and exclusion criteria was arthritis other than degeneration, previous operations such as osteotomy, body mass index (BMI) over 30 kg/m2. The matching criteria were set as age, BMI, preoperative ROM, gender, and the Knee Society (KS) and Hospital for Special Surgery (HSS) scores. After 1:1 matching, 50 cases involved the LCS RP bearing system as group 1 and 50 cases involved LCS PS bearing system group as group 2. Clinical and radiographic outcomes were evaluated.
Results
The overall survival was 100% at final follow up. There were no complications between groups, such as infection, dislocation of bearing. The postoperative ROM was 122.3° ± 9.3 in group 1, 121.2° ± 9.7 in group 2. The KSKS scores were 93.5±7.2 in group 1, 92.8±3.6 in group 2 at final follow up. The KSFS scores were 87.5±7.7 in group 1, 86.9±6.8 in group 2 at final follow up. The HSS scores were 93.1±8.8 in group 1, 91.7±6.1 in group 2 at final follow up. There was no statistical difference in Hospital for Special Surgery Scores (HSS), Knee Society Scores (KSS) score evaluations between groups. However, the improvement of KSS and HSS scores was faster in group 1, the final scores were achieved at 3 to 6 months in group 1, at 6 to 1 year in group 2. Moreover, the KSFS scores were improved continuously until 2 years follow up. The postoperative mechanical axis was found as 1.2° ± 1.2 in group 1, 0.9° ± 0.9 in group 2. There were no statistical differences between groups in radiological evaluations including radiolucent lines.
Conclusion
This study demonstrated that the PS-LCS prosthesis could provide satisfactory performance compared with that of the RP-LCS prosthesis with minimum 2-year follow-up, however, there could be disadvantages in PS-LCS prosthesis due to more bone loss in box cut in femur.
