A valgus deformity is a condition in which the bone segment distal to a joint is angled outward, that is, angled laterally, away from the body's midline. The opposite deformation, where the twist or angulation is directed medially, toward the center of the body, is called varus. Common causes of valgus knee (genu valgum or "knock-knee") in adults include arthritis of the knee and traumatic injuries.
Valgus is a term for outward angulation of the distal segment of a bone or joint. The opposite condition is called varus, which is a medial deviation of the distal bone. The terms varus and valgus always refer to the direction that the distal segment of the joint points. For a discussion of the etymology of these words, see the entry under varus. A mnemonic to remember the two deformities is that valgus contains an "L", for Lateral deviation.
Canale & Beaty: Campbell's Operative Orthopaedics, 11th ed. - 2007 - Mosby, An Imprint of Elsevier
Bowed Leg (Varus) and Knock-Knee (Valgus) Malalignment: Everything You Need to Know to Make the Right Treatment Decision-Understanding lower limb malalignment-Tibial osteotomy for bowed legs, Noyes, Frank R. and Barber-Westin, Sue, Amazon Digital Version, Publish Green (October 6, 2013)