Time-Dependent Clinical Results of Rotating-Platform Total Knee Arthroplasty According to Mechanical Axis Deviation

Lee, Han Jun; Jung, Ho Joong; Jung, Young Bok; Ko, Young Bong; Song, Min Ku; Kim, Seong Hwan

Abstract

PURPOSE
We hypothesized that the low contact stress (LCS) posterior stabilization system in knees with < or =3degrees deviation of coronal alignment would provide more favorable clinical outcomes and survival rate over the course of time.
MATERIALS AND METHODS
A retrospective study was performed on 253 consecutive cases of primary total knee arthroplasty (TKA). Patients were classified according to the degree of deviation of coronal alignment on the initial postoperative radiograph as Group 1 (< or =3degrees deviation) and Group 2 (>3degrees deviation). The clinical assessments were performed using the Knee Society score and Hospital for Special Surgery systems and Western Ontario and McMaster Universities index.
RESULTS
The survival rate was 97.4% in Group 1 and 96.8% in Group 2. No statistically significant intergroup difference was observed in the clinical scores before surgery and since 1 year after surgery (p>0.05). However, a significant intergroup difference was noted between 6 months to 1 year after surgery (p<0.001). Less than 2 mm radiolucent lines were found more frequently in Group 2. Time-dependent improvement was noted within one year after TKA in both groups.
CONCLUSIONS
Most of the expected improvements were achieved at 6 months after surgery in Group 1 and at 1 year after surgery in Group 2. The present study suggests that the LCS system yields time-dependent improvement regardless of coronal alignment deviation.