A number of things can lead to a varus deformity. Some are congenital malformations which are evident at birth. Others are caused by trauma, such as strain, a poorly healed break, and poor posture. Over time, varus deformities can lead to serious problems, such as strain on accompanying joints, limps, shortening of limbs, and pain. The patient may also feel uncomfortable in social situations as the deformity becomes more noticeable.
One of the things I've had to look up.
In this case, the reason is poorly healed break.