Plica syndrome causes knee pain and is basically when a part of the synovial capsule of the knee becomes irritated, enlarged, or inflamed. This can cause the whole knee to be painful and hard to move.
These stretches and exercises should help.
The first stretch is for the IT band. This will help take pressure off the knee joint in general. Then you will do what is called a knee prop, which helps get knee extension, or straightening out the knee.
Next is a heel slide. This is a combination move. It helps gain knee flexion by bending the knee, and it helps strengthening the hamstring muscles.
After you are stretched out, you will do a four way hip exercise. Even though they are called hip exercises, these muscles go down to the knees and help them move as well. The straight leg raise, hip abduction, hip adduction, and hip extension are great for general leg strengthening.
Finally, a clamshell exercise is very helpful to strengthening your glutes and IT band.
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