I had mitral valve surgery. Please recommend suitable exercises.

Last year, after making kimchi, I had water buildup in my knee twice and had it drained. Since then, I have continued to feel discomfort, so I went back to the hospital.

The doctor suggested we get an MRI, and when I looked at the results, I saw that the meniscus was torn. It's been almost three months since the surgery, but it's still not fully normal.

After the first cartilage injection, I feel like I have aged a bit.

What kind of exercise should I do to help my knees?

I think I should focus on strengthening my thigh muscles above all.

I want to receive a recommendation.