Genu valgum, commonly called "knock-knees", is a condition where the knees angle in and touch one another when the legs are straightened. Individuals with severe valgus deformities are typically unable to touch their feet together while simultaneously straightening the legs. The term originates from the Latin genu, "knee", and valgum, "knock-kneed.
Mild genu valgum can be seen in children from ages 2 to 5, and is often corrected naturally as children grow. However, the condition may continue or worsen with age, particularly when it is the result of a disease, such as rickets or obesity. Idiopathic is the term used to describe genu valgum that is congenital or has no known cause.
Adults with uncorrected genu valgum are typically prone to injury and chronic knee problems such as chondromalacia and osteoarthritis. In some cases, total knee replacement (TKR) surgery may be required later in life to relieve pain and complications resulting from severe genu valgum.