Preoperative laxity in osteoarthritis patients undergoing total knee arthroplasty

A preoperative quantitative evaluation of soft tissues is helpful for planning total knee arthroplasty, in addition to the conventional clinical examinations involved in moving the knee manually. We evaluated preoperative coronal laxity with osteoarthritis in patients undergoing total knee arthroplasty by applying a force of 150 N with an arthrometer. We examined a consecutive series of 120 knees in 102 patients. The median laxity was 0 degrees in abduction and 8 degrees in adduction. The femorotibial angle on non-weight-bearing standard anteroposterior radiographs was 180 degrees and correlated with both abduction (r=-0.244, p=0.007) and adduction (r=0.205, p=0.025) laxity. The results of a regression analysis suggested that the femorotibial angle is helpful for estimating both laxities. Considering the many reports on how to obtain well-balanced soft tissues, stress radiographs might help to improve the preoperative planning for gaining the optimal laxity deemed appropriate by surgeons.