Coronal Laxity after Total Knee Arthroplasty for Varus-deformed Knees : A Stress Radiographic Study

Abstract

The purpose of this study was to clarify coronal laxity after total knee arthroplasty for varus-deformed knees using varus and valgus stress radiography. Thirty patients (5 men and 25 women, 40 knees) were followed up for 1 to 36 months (mean 9.7 months) after surgery. The mean patient age was 77.9 years (range : 69 to 85 years). NexGen LPS-Flex-type TKA was used for all patients.
JOA score was improved from 50.9±8.6 before surgery to 78.0±7.8 after surgery. On stress radiography, varus laxity was 2.4±1.8° and valgus laxity was 3.3±1.9°. Total coranal laxity was 5.7±2.6° and the difference between varus laxity and valgus laxity was 1.9±1.9°. Increased varus instability was associated with lower JOA score, especially with walking ability.
Coronal stability after total knee arthroplasty for varus-deformed knees was relatively good, however, caution may be necessary for varus instability after surgery.