what is 'knock knee?'?

Answer 1

The opposite of bow-legged.

Knock-knee (or genu valgum) is the inward turning of the knees.

Bowleg (or genu vargus) is the outward turning of the knees.

Please refer to the website for pictures: http://www.orthoseek.com/articles/bowlegs-kk.html

Answer 2

In a knock-kneed person, the femur is deviated inward in relation to the hip, but in the same knock-kneed person, the opposite situation is found at the knee, with the distal segment now being deviated outward.

It is correct for a knock-kneed deformity to be called both a varus deformity at the hip/femur and a valgus deformity at the knee/tibia, although the common terminology is to refer to it as genu valgus.

In a VARUS deformity of the knee, the distal part of the leg below the knee is deviated inward, resulting in a bowlegged appearance. Conversely, a valgus deformity at the knee results in a knock-kneed appearance, with the distal part of the leg deviated outward.