Medial knee collapse is an issue not just on landings but also on take offs.
For example, I am a big fan of Alexandr Shade Zlat, but watching him I have always had this niggling feeling that his lower body mechanics were missing something. His tendency to wear baggy pants has made it difficult to suss out what was going on. As an aside this is why I hate the XXXL sweatpants fad.
In his most recent video, however, he was in skinny jeans, and I could finally see what was going on.
Shade’s landings are great, however when he takes off, he is exhibiting a huge amount of medial collapse in his knees.
It is impossible to know precisely what is the cause of this movement pattern just by watching the video, but the most common cause of this motor pattern in the clients I work with is collapsed arches, and weak glutes usually with a history of ankle sprains (ankle sprains cause inhibition of the glutes); and specifically glutes that are weaker in a shortened position.
The tendency then is to drives the femurs in prior to take off too pre-stretch the glutes, allowing them to operate in position they can work better from, and making it easier to activate a structure that has poor neural feedback.
Shade has already suffered an achilles tear, which this kind of movement pattern will predispose you too – I have similar biomechanical problems and also suffered an achilles tear. It is also a risk factor for ACL tears and Patello femoral pain.
My usual prescription when I see this motor pattern, is a series of glute and intrinsic foot musculature strengthening exercises at various joint angles, and dealing with different planes of motion to improve neural feedback and control through those joint complexes. .