Swing Test: A New Physical Examination Technique for Evaluating Valgus Knee Deformity

Background:

The origin of a valgus deformity affects the algorithmic and individualized approach used in total knee arthroplasty in valgus knees. We developed a new physical examination technique, the swing test, to evaluate whether valgus malalignment is present when the knee flexes.

Methods:

We performed the swing test on 44 valgus knees in 44 consecutive patients, and we conducted traditional malalignment analysis on each patient's long-film radiographs and computed tomography images to evaluate origin of valgus deformity. We did a diagnostic test to compare the results of the swing test with those of traditional malalignment analysis.

Results:

For the swing test, there were positive findings in 22 cases and negative findings in the other 22 cases, whereas for traditional malalignment analysis, there were positive findings in 26 cases and negative findings in 18. The sensitivity, specificity, and accuracy for the swing test were 84.6%, 100%, and 90.9%, respectively.

Conclusions:

The swing test is an effective technique in evaluating whether valgus deformity exists when the knee is flexed.

Level of Evidence: Level III. See Instructions to Authors for a complete description of levels of evidence.