Genu valgum (knocked knees) is an angular deformity of the lower extremity. It is the opposite end of the spectrum from genu varum (bow legged).
Many children show a physiologic genu valgum prior to age 7 but this typically corrects with growth.
The intermalleolar distance is one measure of the condition. This is taken with the person standing straight with the medial femoral condyles touching. The distance between the medial malleoli is then measured, with a measurement > 8 cm abnormal.
Pathologic genu valgum occurs when there is a process causing the deformity may affect the distal femur, proximal tibia, or both.
Causes of unliteral genu valgum include:
(1) infection with asymmetric growth
(2) tumor
(3) post-traumatic
(4) iliotibial band contracture
Causes of bilateral genu valgum include:
(1) lysosomal storage disease
(2) metabolic bone disease, including hyperparathyroidism
(3) skeletal dysplasia
(4) osteogenesis imperfecta
(5) physiologic
(6) arthropathy
(7) congenital
(8) ligamentous laxity
