A fallen arch, squats and deadlift

Hey Docs! There’s something that bothers me for a long time now.
I have a left flat foot(more of a fallen arch than completely flat).
The problem begins when I squat or deadlift. if I squat 90% or @9,10, my left knee buckles in, which causes to an ugly squat on the ascend.
On the deadlift, I miss the lift after my knee caves in. Sometimes though, i “succeed” to finish the lift, after my knee goes back to its normal “place”.
I have the feeling that from a strength standpoint, I can lift more, but when my knee buckles in, it’s as though all the energy is lost
(which makes sense due to a leak in the kinetic chain).

I’m stuck on my squat and deadlift for a long time now(4 months).

The cues of “spreading the floor”, “push your knees out” or “creating an arch in your feet” don’t really work on heavy sets, it’s impossible to control it with my giant brain.
Of course, weightlifting shoes are used(Adipower) which gives support to some extent.
Additionally, I execute glutes and adductors work for weak glutes and “muscular imbalances” - I can’t say it helps too much.

Now, of what I noticed, there are many people out there who deal with it as well - so I’m not a special snowflake, however, it seems that nobody knows how to fix it or what to do with it. (Is there a fix anyway?)

With that being said, I guess you guys after many years of trainees’ references have an idea or two.

stats: (bodyweight: 82kg)
Bench: 105kg
Squat: 130kg
DL: 175kg

Any help or advice is highly appreciated.
Thanks a lot for your time!

David

I’d suggest posting a form check to our FB group.

I am not surprised that your “muscular imbalance” work doesn’t help. I’m also not entirely sure whether your arch has anything to do with this.

Just to add my 2 cents…

I have extremely flat feet as well, and have struggled with knee cave. The main things that have helped me with the knee cave was narrowing my stance a bit and pointing my toes a bit more forward. None of the cues worked for me either, so it was a bit of a “form epiphany” when I just kind of let my knees track forward more and moved my stance so that my knees were tracking over my toes.

Try playing with your stance a bit and see if that helps.