A recent study determined that African-Americans were less likely to have a varus thrust, but more likely to have valgus thrust than Caucasians. Varus thrust is visualized during gait as the worsening or abrupt onset of varus (bow-legged) alignment as the leg accepts weight, with a return to less varus and more neutral alignment during lift-off of the foot and the swing phase of gait. Prior research has shown that varus thrust seen in gait is associated with a 4-fold increase in the risk of progression of knee osteoarthritis. Disparity in thrust presence between the races may help explain differences in the pattern of osteoarthritic involvement at the knee.