The Effect of Tibiofemoral Alignment on the Results of Total Knee Arthroplasty

There have been several reports that total knee arthroplasty(TKA) was most likely to survive successfully if the coronal tibiofemoral angle was close to 7 degree of valgus, the accepted normal. In order to know whether the postoperative coronal tibiofemoral angle influences the result of total knee arthroplasty, we examined the 152 TKA cases in 106 patients which had been performed at Department of Orthopaedic Surgery, Seoul National University Hospital from Jan. 1987 to Dec. 1991. In our series the average follow-up period was 31 months(range, 13 months to 75 months). Coronal tibiofemoral angles of all cases were checked on weight bearing anteroposterior plain X-rays and were divided into three groups(less than valgus 2° ; valgus 3° to 7° ; greater than valgus 8°). All cases were analyzed on the knee score of Hospital for Special Surgery and the American Knee Society total knee arthroplasty roentgenographic evaluation and scoring system and the cases with radiolucent lines wider than 2mm were checked. Three groups were analyzed comparatively with statistical means(Wilcoxon signed rank test, X2 test). There were no significant differences in the clinical results of total knee arthroplasty according to the postoperative coronal tibiofemoral angle. Lateral subluxation of the patella occurred more frequently when the postoperative coronal tibiofemoral angle was above valgus 8°. In the tibial components of group lesser than valgus 2°, the frequency of radiolucent lines wider than 2mm was higher than those of other groups, but its significance should be examined through long term follow-up.